Merged in dstaesse/ouroboros/be-demux (pull request #267)

lib: Demultiplex the fast path

19 files changed, 1537 insertions, 1070 deletions

diff --git a/src/ipcpd/ipcp.c b/src/ipcpd/ipcp.c
index a9f80ee7..f9246c7a 100644
--- a/src/ipcpd/ipcp.c
+++ b/src/ipcpd/ipcp.c
@@ -323,9 +323,9 @@ void * ipcp_main_loop(void * o)
                         ret_msg.has_result = true;
                         ret_msg.result =
                                 ipcpi.ops->ipcp_flow_alloc(fd,
-                                                            msg->dst_name,
-                                                            msg->src_ae_name,
-                                                            msg->qos_cube);
+                                                           msg->dst_name,
+                                                           msg->src_ae_name,
+                                                           msg->qos_cube);
                         if (ret_msg.result < 0) {
                                 LOG_DBG("Deallocate failed on port_id %d.",
                                         msg->port_id);
diff --git a/src/ipcpd/local/main.c b/src/ipcpd/local/main.c
index 4e500a8a..68c9ae8c 100644
--- a/src/ipcpd/local/main.c
+++ b/src/ipcpd/local/main.c
@@ -25,7 +25,7 @@
 #include <ouroboros/errno.h>
 #include <ouroboros/dev.h>
 #include <ouroboros/fcntl.h>
-#include <ouroboros/select.h>
+#include <ouroboros/fqueue.h>
 #include <ouroboros/ipcp-dev.h>
 #include <ouroboros/local-dev.h>
 #define OUROBOROS_PREFIX "ipcpd/local"
@@ -39,6 +39,7 @@
 #include <sys/wait.h>
 #include <fcntl.h>
 
+#define EVENT_WAIT_TIMEOUT 100 /* us */
 #define THIS_TYPE IPCP_LOCAL
 
 /* global for trapping signal */
@@ -46,18 +47,25 @@ int irmd_api;
 
 struct {
         int                   in_out[IRMD_MAX_FLOWS];
+        flow_set_t *          flows;
 
         pthread_rwlock_t      lock;
         pthread_t             sduloop;
 } local_data;
 
-void local_data_init()
+int local_data_init()
 {
         int i;
         for (i = 0; i < IRMD_MAX_FLOWS; ++i)
                 local_data.in_out[i] = -1;
 
+        local_data.flows = flow_set_create();
+        if (local_data.flows == NULL)
+                return -ENFILE;
+
         pthread_rwlock_init(&local_data.lock, NULL);
+
+        return 0;
 }
 
 void local_data_fini()
@@ -67,11 +75,24 @@ void local_data_fini()
 
 static void * ipcp_local_sdu_loop(void * o)
 {
+        struct timespec timeout = {0, EVENT_WAIT_TIMEOUT * 1000};
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
+
         while (true) {
                 int fd;
-                struct rb_entry * e;
+                int ret;
+                ssize_t idx;
+
+                ret = flow_event_wait(local_data.flows, fq, &timeout);
+                if (ret == -ETIMEDOUT)
+                        continue;
 
-                fd = flow_select(NULL, NULL);
+                if (ret < 0) {
+                        LOG_ERR("Event wait returned error code %d.", -ret);
+                        continue;
+                }
 
                 pthread_rwlock_rdlock(&ipcpi.state_lock);
 
@@ -82,20 +103,20 @@ static void * ipcp_local_sdu_loop(void * o)
 
                 pthread_rwlock_rdlock(&local_data.lock);
 
-                e = local_flow_read(fd);
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        idx = local_flow_read(fd);
 
-                fd = local_data.in_out[fd];
+                        fd = local_data.in_out[fd];
 
-                if (fd != -1)
-                        local_flow_write(fd, e);
+                        if (fd != -1)
+                                local_flow_write(fd, idx);
+                }
 
                 pthread_rwlock_unlock(&local_data.lock);
                 pthread_rwlock_unlock(&ipcpi.state_lock);
-
-                free(e);
         }
 
-        return (void *) 1;
+        return (void *) 0;
 }
 
 void ipcp_sig_handler(int sig, siginfo_t * info, void * c)
@@ -152,7 +173,7 @@ static int ipcp_local_name_reg(char * name)
 
         if (ipcp_data_add_reg_entry(ipcpi.data, name)) {
                 pthread_rwlock_unlock(&ipcpi.state_lock);
-                LOG_DBGF("Failed to add %s to local registry.", name);
+                LOG_DBG("Failed to add %s to local registry.", name);
                 return -1;
         }
 
@@ -194,12 +215,14 @@ static int ipcp_local_flow_alloc(int           fd,
 
         if (ipcp_get_state() != IPCP_ENROLLED) {
                 pthread_rwlock_unlock(&ipcpi.state_lock);
-                LOG_DBGF("Won't register with non-enrolled IPCP.");
+                LOG_DBG("Won't register with non-enrolled IPCP.");
                 return -1; /* -ENOTENROLLED */
         }
 
         pthread_rwlock_wrlock(&local_data.lock);
 
+        flow_set_add(local_data.flows, fd);
+
         out_fd = ipcp_flow_req_arr(getpid(), dst_name, src_ae_name);
 
         local_data.in_out[fd]  = out_fd;
@@ -222,6 +245,7 @@ static int ipcp_local_flow_alloc_resp(int fd, int response)
                 return 0;
 
         pthread_rwlock_rdlock(&ipcpi.state_lock);
+        pthread_rwlock_rdlock(&local_data.lock);
 
         out_fd = local_data.in_out[fd];
         if (out_fd < 0) {
@@ -230,6 +254,9 @@ static int ipcp_local_flow_alloc_resp(int fd, int response)
                 return -1;
         }
 
+        flow_set_add(local_data.flows, fd);
+
+        pthread_rwlock_unlock(&local_data.lock);
         pthread_rwlock_unlock(&ipcpi.state_lock);
 
         if ((ret = ipcp_flow_alloc_reply(out_fd, response)) < 0)
@@ -247,6 +274,8 @@ static int ipcp_local_flow_dealloc(int fd)
         if (fd < 0)
                 return -EINVAL;
 
+        flow_set_del(local_data.flows, fd);
+
         while (flow_dealloc(fd) == -EBUSY)
                 nanosleep(&t, NULL);
 
@@ -289,9 +318,14 @@ int main(int argc, char * argv[])
                 exit(EXIT_FAILURE);
         }
 
-        local_data_init();
-
         if (ap_init(NULL) < 0) {
+                LOG_ERR("Failed to init application.");
+                close_logfile();
+                exit(EXIT_FAILURE);
+        }
+
+        if (local_data_init() < 0) {
+                LOG_ERR("Failed to init local data.");
                 close_logfile();
                 exit(EXIT_FAILURE);
         }
@@ -331,10 +365,10 @@ int main(int argc, char * argv[])
         pthread_cancel(local_data.sduloop);
         pthread_join(local_data.sduloop, NULL);
 
-        ap_fini();
-
         local_data_fini();
 
+        ap_fini();
+
         close_logfile();
 
         exit(EXIT_SUCCESS);
diff --git a/src/ipcpd/normal/fmgr.c b/src/ipcpd/normal/fmgr.c
index cb25072e..3da392c5 100644
--- a/src/ipcpd/normal/fmgr.c
+++ b/src/ipcpd/normal/fmgr.c
@@ -27,7 +27,7 @@
 #include <ouroboros/dev.h>
 #include <ouroboros/list.h>
 #include <ouroboros/ipcp-dev.h>
-#include <ouroboros/select.h>
+#include <ouroboros/fqueue.h>
 #include <ouroboros/errno.h>
 
 #include <stdlib.h>
@@ -185,39 +185,47 @@ static void * fmgr_np1_sdu_reader(void * o)
         struct shm_du_buff * sdb;
         struct timespec timeout = {0, FD_UPDATE_TIMEOUT};
         struct np1_flow * flow;
+        int fd;
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
 
         while (true) {
-                int fd = flow_select(fmgr.np1_set, &timeout);
-                if (fd == -ETIMEDOUT)
+                int ret = flow_event_wait(fmgr.np1_set, fq, &timeout);
+                if (ret == -ETIMEDOUT)
                         continue;
 
-                if (fd < 0) {
-                        LOG_ERR("Failed to get active fd.");
+                if (ret < 0) {
+                        LOG_ERR("Event error: %d.", ret);
                         continue;
                 }
 
-                if (ipcp_flow_read(fd, &sdb)) {
-                        LOG_ERR("Failed to read SDU from fd %d.", fd);
-                        continue;
-                }
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        if (ipcp_flow_read(fd, &sdb)) {
+                                LOG_ERR("Failed to read SDU from fd %d.", fd);
+                                continue;
+                        }
 
-                pthread_rwlock_rdlock(&fmgr.np1_flows_lock);
-                flow = fmgr.np1_flows[fd];
-                if (flow == NULL) {
-                        pthread_rwlock_unlock(&fmgr.np1_flows_lock);
-                        ipcp_flow_del(sdb);
-                        LOG_ERR("Failed to retrieve flow.");
-                        continue;
-                }
+                        pthread_rwlock_rdlock(&fmgr.np1_flows_lock);
+
+                        flow = fmgr.np1_flows[fd];
+                        if (flow == NULL) {
+                                pthread_rwlock_unlock(&fmgr.np1_flows_lock);
+                                ipcp_flow_del(sdb);
+                                LOG_ERR("Failed to retrieve flow.");
+                                continue;
+                        }
+
+                        if (frct_i_write_sdu(flow->cep_id, sdb)) {
+                                pthread_rwlock_unlock(&fmgr.np1_flows_lock);
+                                ipcp_flow_del(sdb);
+                                LOG_ERR("Failed to hand SDU to FRCT.");
+                                continue;
+                        }
 
-                if (frct_i_write_sdu(flow->cep_id, sdb)) {
                         pthread_rwlock_unlock(&fmgr.np1_flows_lock);
-                        ipcp_flow_del(sdb);
-                        LOG_ERR("Failed to hand SDU to FRCT.");
-                        continue;
-                }
 
-                pthread_rwlock_unlock(&fmgr.np1_flows_lock);
+                }
         }
 
         return (void *) 0;
@@ -228,66 +236,71 @@ void * fmgr_nm1_sdu_reader(void * o)
         struct timespec timeout = {0, FD_UPDATE_TIMEOUT};
         struct shm_du_buff * sdb;
         struct pci * pci;
-
+        int fd;
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
         while (true) {
-                int fd = flow_select(fmgr.nm1_set, &timeout);
-                if (fd == -ETIMEDOUT)
-                        continue;
-
-                if (fd < 0) {
-                        LOG_ERR("Failed to get active fd.");
+                int ret = flow_event_wait(fmgr.nm1_set, fq, &timeout);
+                if (ret == -ETIMEDOUT)
                         continue;
-                }
 
-                if (ipcp_flow_read(fd, &sdb)) {
-                        LOG_ERR("Failed to read SDU from fd %d.", fd);
+                if (ret < 0) {
+                        LOG_ERR("Event error: %d.", ret);
                         continue;
                 }
 
-                pci = shm_pci_des(sdb);
-                if (pci == NULL) {
-                        LOG_ERR("Failed to get PCI.");
-                        ipcp_flow_del(sdb);
-                        continue;
-                }
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        if (ipcp_flow_read(fd, &sdb)) {
+                                LOG_ERR("Failed to read SDU from fd %d.", fd);
+                                continue;
+                        }
 
-                if (pci->dst_addr != ribmgr_address()) {
-                        LOG_DBG("PDU needs to be forwarded.");
+                        pci = shm_pci_des(sdb);
+                        if (pci == NULL) {
+                                LOG_ERR("Failed to get PCI.");
+                                ipcp_flow_del(sdb);
+                                continue;
+                        }
 
-                        if (pci->ttl == 0) {
-                                LOG_DBG("TTL was zero.");
+                        if (pci->dst_addr != ribmgr_address()) {
+                                LOG_DBG("PDU needs to be forwarded.");
+
+                                if (pci->ttl == 0) {
+                                        LOG_DBG("TTL was zero.");
+                                        ipcp_flow_del(sdb);
+                                        free(pci);
+                                        continue;
+                                }
+
+                                if (shm_pci_dec_ttl(sdb)) {
+                                        LOG_ERR("Failed to decrease TTL.");
+                                        ipcp_flow_del(sdb);
+                                        free(pci);
+                                        continue;
+                                }
+                                /*
+                                 * FIXME: Dropping for now, since
+                                 * we don't have a PFF yet
+                                 */
                                 ipcp_flow_del(sdb);
                                 free(pci);
                                 continue;
                         }
 
-                        if (shm_pci_dec_ttl(sdb)) {
-                                LOG_ERR("Failed to decrease TTL.");
+                        if (shm_pci_shrink(sdb)) {
+                                LOG_ERR("Failed to shrink PDU.");
                                 ipcp_flow_del(sdb);
                                 free(pci);
                                 continue;
                         }
-                        /*
-                         * FIXME: Dropping for now, since
-                         * we don't have a PFF yet
-                         */
-                        ipcp_flow_del(sdb);
-                        free(pci);
-                        continue;
-                }
-
-                if (shm_pci_shrink(sdb)) {
-                        LOG_ERR("Failed to shrink PDU.");
-                        ipcp_flow_del(sdb);
-                        free(pci);
-                        continue;
-                }
 
-                if (frct_nm1_post_sdu(pci, sdb)) {
-                        LOG_ERR("Failed to hand PDU to FRCT.");
-                        ipcp_flow_del(sdb);
-                        free(pci);
-                        continue;
+                        if (frct_nm1_post_sdu(pci, sdb)) {
+                                LOG_ERR("Failed to hand PDU to FRCT.");
+                                ipcp_flow_del(sdb);
+                                free(pci);
+                                continue;
+                        }
                 }
         }
 
diff --git a/src/ipcpd/shim-eth-llc/main.c b/src/ipcpd/shim-eth-llc/main.c
index 399d3dc8..db258c8b 100644
--- a/src/ipcpd/shim-eth-llc/main.c
+++ b/src/ipcpd/shim-eth-llc/main.c
@@ -30,6 +30,8 @@
 #include <ouroboros/bitmap.h>
 #include <ouroboros/dev.h>
 #include <ouroboros/ipcp-dev.h>
+#include <ouroboros/fcntl.h>
+#include <ouroboros/fqueue.h>
 
 #define OUROBOROS_PREFIX "ipcpd/shim-eth-llc"
 
@@ -77,6 +79,8 @@ typedef ShimEthLlcMsg shim_eth_llc_msg_t;
 #define ETH_FRAME_SIZE (ETH_HEADER_SIZE + LLC_HEADER_SIZE \
                         + SHIM_ETH_LLC_MAX_SDU_SIZE)
 
+#define EVENT_WAIT_TIMEOUT 100 /* us */
+
 /* global for trapping signal */
 int irmd_api;
 
@@ -110,6 +114,7 @@ struct {
         uint8_t *          tx_ring;
         int                tx_offset;
 #endif
+        flow_set_t *       np1_flows;
         int *              ef_to_fd;
         struct ef *        fd_to_ef;
         pthread_rwlock_t   flows_lock;
@@ -139,6 +144,14 @@ static int eth_llc_data_init()
                 return -ENOMEM;
         }
 
+        eth_llc_data.np1_flows = flow_set_create();
+        if (eth_llc_data.np1_flows == NULL) {
+                bmp_destroy(eth_llc_data.saps);
+                free(eth_llc_data.ef_to_fd);
+                free(eth_llc_data.fd_to_ef);
+                return -ENOMEM;
+        }
+
         for (i = 0; i < MAX_SAPS; ++i)
                 eth_llc_data.ef_to_fd[i] = -1;
 
@@ -156,6 +169,7 @@ static int eth_llc_data_init()
 void eth_llc_data_fini()
 {
         bmp_destroy(eth_llc_data.saps);
+        flow_set_destroy(eth_llc_data.np1_flows);
         free(eth_llc_data.fd_to_ef);
         free(eth_llc_data.ef_to_fd);
         pthread_rwlock_destroy(&eth_llc_data.flows_lock);
@@ -416,23 +430,17 @@ static int eth_llc_ipcp_flow_dealloc_req(uint8_t ssap, uint8_t * r_addr)
                 return 0;
         }
 
-        bmp_release(eth_llc_data.saps, eth_llc_data.fd_to_ef[fd].sap);
-
         pthread_rwlock_unlock(&eth_llc_data.flows_lock);
         pthread_rwlock_unlock(&ipcpi.state_lock);
 
-        flow_dealloc(fd);
-
-        LOG_DBG("Flow with fd %d deallocated.", fd);
+        flow_cntl(fd, FLOW_F_SETFL, FLOW_O_WRONLY);
 
         return 0;
 }
 
 static int eth_llc_ipcp_mgmt_frame(uint8_t * buf, size_t len, uint8_t * r_addr)
 {
-        shim_eth_llc_msg_t * msg = NULL;
-
-        msg = shim_eth_llc_msg__unpack(NULL, len, buf);
+        shim_eth_llc_msg_t * msg = shim_eth_llc_msg__unpack(NULL, len, buf);
         if (msg == NULL) {
                 LOG_ERR("Failed to unpack.");
                 return -1;
@@ -590,32 +598,49 @@ static void * eth_llc_ipcp_sdu_reader(void * o)
 
 static void * eth_llc_ipcp_sdu_writer(void * o)
 {
+        int fd;
+        struct shm_du_buff * sdb;
+        uint8_t ssap;
+        uint8_t dsap;
+        uint8_t r_addr[MAC_SIZE];
+        struct timespec timeout = {0, EVENT_WAIT_TIMEOUT * 1000};
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
+
         while (true) {
-                int fd;
-                struct shm_du_buff * sdb;
-                uint8_t ssap;
-                uint8_t dsap;
-                uint8_t r_addr[MAC_SIZE];
-
-                fd = ipcp_read_shim(&sdb);
-                if (fd < 0)
+                int ret = flow_event_wait(eth_llc_data.np1_flows, fq, &timeout);
+                if (ret == -ETIMEDOUT)
                         continue;
 
-                pthread_rwlock_rdlock(&ipcpi.state_lock);
-                pthread_rwlock_rdlock(&eth_llc_data.flows_lock);
+                if (ret < 0) {
+                        LOG_ERR("Event wait returned error code %d.", -ret);
+                        continue;
+                }
 
-                ssap = reverse_bits(eth_llc_data.fd_to_ef[fd].sap);
-                dsap = reverse_bits(eth_llc_data.fd_to_ef[fd].r_sap);
-                memcpy(r_addr, eth_llc_data.fd_to_ef[fd].r_addr, MAC_SIZE);
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        if (ipcp_flow_read(fd, &sdb)) {
+                                LOG_ERR("Bad read from fd %d.", fd);
+                                continue;
+                        }
+                        pthread_rwlock_rdlock(&ipcpi.state_lock);
+                        pthread_rwlock_rdlock(&eth_llc_data.flows_lock);
 
-                pthread_rwlock_unlock(&eth_llc_data.flows_lock);
-                pthread_rwlock_unlock(&ipcpi.state_lock);
+                        ssap = reverse_bits(eth_llc_data.fd_to_ef[fd].sap);
+                        dsap = reverse_bits(eth_llc_data.fd_to_ef[fd].r_sap);
+                        memcpy(r_addr,
+                               eth_llc_data.fd_to_ef[fd].r_addr,
+                               MAC_SIZE);
+
+                        pthread_rwlock_unlock(&eth_llc_data.flows_lock);
+                        pthread_rwlock_unlock(&ipcpi.state_lock);
 
-                eth_llc_ipcp_send_frame(r_addr, dsap, ssap,
-                                        shm_du_buff_head(sdb),
-                                        shm_du_buff_tail(sdb)
-                                        - shm_du_buff_head(sdb));
-                ipcp_flow_del(sdb);
+                        eth_llc_ipcp_send_frame(r_addr, dsap, ssap,
+                                                shm_du_buff_head(sdb),
+                                                shm_du_buff_tail(sdb)
+                                                - shm_du_buff_head(sdb));
+                        ipcp_flow_del(sdb);
+                }
         }
 
         return (void *) 1;
@@ -859,7 +884,7 @@ static int eth_llc_ipcp_flow_alloc(int           fd,
         uint8_t ssap = 0;
         uint8_t r_addr[MAC_SIZE];
 
-        LOG_INFO("Allocating flow to %s.", dst_name);
+        LOG_DBG("Allocating flow to %s.", dst_name);
 
         if (dst_name == NULL || src_ae_name == NULL)
                 return -1;
@@ -903,6 +928,8 @@ static int eth_llc_ipcp_flow_alloc(int           fd,
                 return -1;
         }
 
+        flow_set_add(eth_llc_data.np1_flows, fd);
+
         LOG_DBG("Pending flow with fd %d on SAP %d.", fd, ssap);
 
         return 0;
@@ -941,6 +968,8 @@ static int eth_llc_ipcp_flow_alloc_resp(int fd, int response)
                 return -1;
         }
 
+        flow_set_add(eth_llc_data.np1_flows, fd);
+
         LOG_DBG("Accepted flow, fd %d, SAP %d.", fd, ssap);
 
         return 0;
@@ -948,11 +977,18 @@ static int eth_llc_ipcp_flow_alloc_resp(int fd, int response)
 
 static int eth_llc_ipcp_flow_dealloc(int fd)
 {
+        struct timespec t = {0, 10000};
+
         uint8_t sap;
         uint8_t r_sap;
         uint8_t addr[MAC_SIZE];
         int ret;
 
+        flow_set_del(eth_llc_data.np1_flows, fd);
+
+        while (flow_dealloc(fd) == -EBUSY)
+                nanosleep(&t, NULL);
+
         pthread_rwlock_rdlock(&ipcpi.state_lock);
         pthread_rwlock_wrlock(&eth_llc_data.flows_lock);
 
@@ -975,8 +1011,6 @@ static int eth_llc_ipcp_flow_dealloc(int fd)
         if (ret < 0)
                 LOG_DBG("Could not notify remote.");
 
-        flow_dealloc(fd);
-
         LOG_DBG("Flow with fd %d deallocated.", fd);
 
         return 0;
@@ -1008,10 +1042,12 @@ int main(int argc, char * argv[])
                 exit(EXIT_FAILURE);
         }
 
-        if (eth_llc_data_init() < 0)
+        if (ap_init(NULL) < 0) {
+                close_logfile();
                 exit(EXIT_FAILURE);
+        }
 
-        if (ap_init(NULL) < 0) {
+        if (eth_llc_data_init() < 0) {
                 close_logfile();
                 exit(EXIT_FAILURE);
         }
@@ -1054,10 +1090,10 @@ int main(int argc, char * argv[])
         pthread_join(eth_llc_data.sdu_writer, NULL);
         pthread_join(eth_llc_data.sdu_reader, NULL);
 
-        ap_fini();
-
         eth_llc_data_fini();
 
+        ap_fini();
+
         close_logfile();
 
         exit(EXIT_SUCCESS);
diff --git a/src/ipcpd/shim-udp/main.c b/src/ipcpd/shim-udp/main.c
index 7c109a8a..050623e4 100644
--- a/src/ipcpd/shim-udp/main.c
+++ b/src/ipcpd/shim-udp/main.c
@@ -27,6 +27,9 @@
 #include <ouroboros/utils.h>
 #include <ouroboros/dev.h>
 #include <ouroboros/ipcp-dev.h>
+#include <ouroboros/fqueue.h>
+#include <ouroboros/fcntl.h>
+#include <ouroboros/errno.h>
 
 #define OUROBOROS_PREFIX "ipcpd/shim-udp"
 
@@ -75,6 +78,7 @@ struct {
         struct sockaddr_in s_saddr;
         int                s_fd;
 
+        flow_set_t *       np1_flows;
         fd_set             flow_fd_s;
         /* bidir mappings of (n - 1) file descriptor to (n) flow descriptor */
         int                uf_to_fd[FD_SETSIZE];
@@ -90,7 +94,7 @@ struct {
         pthread_mutex_t    fd_set_lock;
 } udp_data;
 
-static void udp_data_init()
+static int udp_data_init()
 {
         int i;
 
@@ -104,13 +108,21 @@ static void udp_data_init()
 
         FD_ZERO(&udp_data.flow_fd_s);
 
+        udp_data.np1_flows = flow_set_create();
+        if (udp_data.np1_flows == NULL)
+                return -ENOMEM;
+
         pthread_rwlock_init(&udp_data.flows_lock, NULL);
         pthread_cond_init(&udp_data.fd_set_cond, NULL);
         pthread_mutex_init(&udp_data.fd_set_lock, NULL);
+
+        return 0;
 }
 
 static void udp_data_fini()
 {
+        flow_set_destroy(udp_data.np1_flows);
+
         pthread_rwlock_destroy(&udp_data.flows_lock);
         pthread_mutex_destroy(&udp_data.fd_set_lock);
         pthread_cond_destroy(&udp_data.fd_set_cond);
@@ -387,7 +399,7 @@ static int ipcp_udp_flow_dealloc_req(int udp_port)
         pthread_rwlock_unlock(&udp_data.flows_lock);
         pthread_rwlock_unlock(&ipcpi.state_lock);
 
-        flow_dealloc(fd);
+        flow_cntl(fd, FLOW_F_SETFL, FLOW_O_WRONLY);
 
         close(skfd);
 
@@ -505,30 +517,45 @@ static void * ipcp_udp_sdu_reader()
 
 static void * ipcp_udp_sdu_loop(void * o)
 {
+        int fd;
+        struct timespec timeout = {0, FD_UPDATE_TIMEOUT * 1000};
+        struct shm_du_buff * sdb;
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
 
         while (true) {
-                int fd;
-                struct shm_du_buff * sdb;
+                int ret = flow_event_wait(udp_data.np1_flows, fq, &timeout);
+                if (ret == -ETIMEDOUT)
+                        continue;
 
-                fd = ipcp_read_shim(&sdb);
-                if (fd < 0)
+                if (ret < 0) {
+                        LOG_ERR("Event wait returned error code %d.", -ret);
                         continue;
+                }
 
-                pthread_rwlock_rdlock(&ipcpi.state_lock);
-                pthread_rwlock_rdlock(&udp_data.flows_lock);
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        if (ipcp_flow_read(fd, &sdb)) {
+                                LOG_ERR("Bad read from fd %d.", fd);
+                                continue;
+                        }
 
-                fd = udp_data.fd_to_uf[fd].skfd;
+                        pthread_rwlock_rdlock(&ipcpi.state_lock);
+                        pthread_rwlock_rdlock(&udp_data.flows_lock);
 
-                pthread_rwlock_unlock(&udp_data.flows_lock);
-                pthread_rwlock_unlock(&ipcpi.state_lock);
+                        fd = udp_data.fd_to_uf[fd].skfd;
+
+                        pthread_rwlock_unlock(&udp_data.flows_lock);
+                        pthread_rwlock_unlock(&ipcpi.state_lock);
 
-                if (send(fd,
-                         shm_du_buff_head(sdb),
-                         shm_du_buff_tail(sdb) - shm_du_buff_head(sdb),
-                         0) < 0)
-                        LOG_ERR("Failed to send SDU.");
+                        if (send(fd,
+                                 shm_du_buff_head(sdb),
+                                 shm_du_buff_tail(sdb) - shm_du_buff_head(sdb),
+                                 0) < 0)
+                                LOG_ERR("Failed to send SDU.");
 
-                ipcp_flow_del(sdb);
+                        ipcp_flow_del(sdb);
+                }
         }
 
         return (void *) 1;
@@ -993,6 +1020,8 @@ static int ipcp_udp_flow_alloc(int           fd,
         udp_data.fd_to_uf[fd].skfd = skfd;
         udp_data.uf_to_fd[skfd]    = fd;
 
+        flow_set_add(udp_data.np1_flows, fd);
+
         pthread_rwlock_unlock(&udp_data.flows_lock);
         pthread_rwlock_unlock(&ipcpi.state_lock);
 
@@ -1049,6 +1078,8 @@ static int ipcp_udp_flow_alloc_resp(int fd, int response)
 
         set_fd(skfd);
 
+        flow_set_add(udp_data.np1_flows, fd);
+
         pthread_rwlock_unlock(&udp_data.flows_lock);
         pthread_rwlock_unlock(&ipcpi.state_lock);
 
@@ -1075,9 +1106,15 @@ static int ipcp_udp_flow_dealloc(int fd)
 {
         int skfd = -1;
         int remote_udp = -1;
+        struct timespec t = {0, 10000};
         struct sockaddr_in    r_saddr;
         socklen_t             r_saddr_len = sizeof(r_saddr);
 
+        flow_set_del(udp_data.np1_flows, fd);
+
+        while (flow_dealloc(fd) == -EBUSY)
+                nanosleep(&t, NULL);
+
         pthread_rwlock_rdlock(&ipcpi.state_lock);
         pthread_rwlock_wrlock(&udp_data.flows_lock);
 
@@ -1117,8 +1154,6 @@ static int ipcp_udp_flow_dealloc(int fd)
 
         close(skfd);
 
-        flow_dealloc(fd);
-
         LOG_DBG("Flow with fd %d deallocated.", fd);
 
         return 0;
@@ -1149,13 +1184,16 @@ int main(int argc, char * argv[])
                 exit(EXIT_FAILURE);
         }
 
-        udp_data_init();
-
         if (ap_init(NULL) < 0) {
                 close_logfile();
                 exit(EXIT_FAILURE);
         }
 
+        if (udp_data_init() < 0) {
+                close_logfile();
+                exit(EXIT_FAILURE);
+        }
+
         /* store the process id of the irmd */
         irmd_api = atoi(argv[1]);
 
@@ -1196,10 +1234,10 @@ int main(int argc, char * argv[])
         pthread_join(udp_data.handler, NULL);
         pthread_join(udp_data.sdu_reader, NULL);
 
-        ap_fini();
-
         udp_data_fini();
 
+        ap_fini();
+
         close_logfile();
 
         exit(EXIT_SUCCESS);
diff --git a/src/irmd/ipcp.c b/src/irmd/ipcp.c
index f79e6caf..33f7650a 100644
--- a/src/irmd/ipcp.c
+++ b/src/irmd/ipcp.c
@@ -111,6 +111,7 @@ pid_t ipcp_create(enum ipcp_type ipcp_type)
         char * full_name = NULL;
         char * exec_name = NULL;
         char * log_file = NULL;
+        char * argv[4];
 
         sprintf(irmd_api, "%u", getpid());
 
@@ -161,14 +162,12 @@ pid_t ipcp_create(enum ipcp_type ipcp_type)
         }
 
         /* log_file to be placed at the end */
-        char * argv[] = {full_name,
-                         irmd_api,
-                         log_file,
-                         0};
+        argv[0] = full_name;
+        argv[1] = irmd_api;
+        argv[2] = log_file;
+        argv[3] = NULL;
 
-        char * envp[] = {0};
-
-        execve(argv[0], &argv[0], envp);
+        execv(argv[0], &argv[0]);
 
         LOG_DBG("%s", strerror(errno));
         LOG_ERR("Failed to load IPCP daemon");
diff --git a/src/irmd/irm_flow.c b/src/irmd/irm_flow.c
index df1302b4..dc5d22d8 100644
--- a/src/irmd/irm_flow.c
+++ b/src/irmd/irm_flow.c
@@ -36,6 +36,9 @@ struct irm_flow * irm_flow_create()
         f->n_api   = -1;
         f->n_1_api = -1;
         f->port_id = -1;
+        f->n_rb    = NULL;
+        f->n_1_rb  = NULL;
+
         f->state   = FLOW_NULL;
 
         if (pthread_cond_init(&f->state_cond, NULL)) {
@@ -78,6 +81,9 @@ void irm_flow_destroy(struct irm_flow * f)
         pthread_cond_destroy(&f->state_cond);
         pthread_mutex_destroy(&f->state_lock);
 
+        shm_rbuff_destroy(f->n_rb);
+        shm_rbuff_destroy(f->n_1_rb);
+
         free(f);
 }
 
diff --git a/src/irmd/irm_flow.h b/src/irmd/irm_flow.h
index 5ec6d90e..507295bd 100644
--- a/src/irmd/irm_flow.h
+++ b/src/irmd/irm_flow.h
@@ -24,6 +24,7 @@
 #define OUROBOROS_IRMD_IRM_FLOW_H
 
 #include <ouroboros/list.h>
+#include <ouroboros/shm_rbuff.h>
 
 #include <sys/types.h>
 #include <pthread.h>
@@ -38,18 +39,21 @@ enum flow_state {
 };
 
 struct irm_flow {
-        struct list_head next;
+        struct list_head   next;
 
-        int              port_id;
+        int                port_id;
 
-        pid_t            n_api;
-        pid_t            n_1_api;
+        pid_t              n_api;
+        pid_t              n_1_api;
 
-        struct timespec  t0;
+        struct shm_rbuff * n_rb;
+        struct shm_rbuff * n_1_rb;
 
-        enum flow_state  state;
-        pthread_cond_t   state_cond;
-        pthread_mutex_t  state_lock;
+        struct timespec    t0;
+
+        enum flow_state    state;
+        pthread_cond_t     state_cond;
+        pthread_mutex_t    state_lock;
 };
 
 struct irm_flow * irm_flow_create();
diff --git a/src/irmd/main.c b/src/irmd/main.c
index 157fd8eb..8d9d04ac 100644
--- a/src/irmd/main.c
+++ b/src/irmd/main.c
@@ -28,7 +28,7 @@
 #include <ouroboros/utils.h>
 #include <ouroboros/irm_config.h>
 #include <ouroboros/lockfile.h>
-#include <ouroboros/shm_ap_rbuff.h>
+#include <ouroboros/shm_rbuff.h>
 #include <ouroboros/shm_rdrbuff.h>
 #include <ouroboros/bitmap.h>
 #include <ouroboros/qos.h>
@@ -1164,6 +1164,24 @@ static struct irm_flow * flow_alloc(pid_t  api,
         port_id = f->port_id = bmp_allocate(irmd->port_ids);
         f->n_1_api = ipcp;
 
+        f->n_rb = shm_rbuff_create(api, port_id);
+        if (f->n_rb == NULL) {
+                pthread_rwlock_unlock(&irmd->flows_lock);
+                pthread_rwlock_unlock(&irmd->state_lock);
+                LOG_ERR("Could not create ringbuffer for AP-I %d.", api);
+                irm_flow_destroy(f);
+                return NULL;
+        }
+
+        f->n_1_rb = shm_rbuff_create(ipcp, port_id);
+        if (f->n_1_rb == NULL) {
+                pthread_rwlock_unlock(&irmd->flows_lock);
+                pthread_rwlock_unlock(&irmd->state_lock);
+                LOG_ERR("Could not create ringbuffer for AP-I %d.", ipcp);
+                irm_flow_destroy(f);
+                return NULL;
+        }
+
         list_add(&f->next, &irmd->irm_flows);
 
         pthread_rwlock_unlock(&irmd->flows_lock);
@@ -1346,7 +1364,7 @@ static struct irm_flow * flow_req_arr(pid_t  api,
                 pthread_rwlock_unlock(&irmd->reg_lock);
                 pthread_rwlock_unlock(&irmd->state_lock);
                 LOG_ERR("Unknown name: %s.", dst_name);
-                free(f);
+                irm_flow_destroy(f);
                 return NULL;
         }
 
@@ -1359,14 +1377,14 @@ static struct irm_flow * flow_req_arr(pid_t  api,
                 pthread_rwlock_unlock(&irmd->reg_lock);
                 pthread_rwlock_unlock(&irmd->state_lock);
                 LOG_ERR("No AP's for %s.", dst_name);
-                free(f);
+                irm_flow_destroy(f);
                 return NULL;
         case REG_NAME_AUTO_ACCEPT:
                 c_api = malloc(sizeof(*c_api));
                 if (c_api == NULL) {
                         pthread_rwlock_unlock(&irmd->reg_lock);
                         pthread_rwlock_unlock(&irmd->state_lock);
-                        free(f);
+                        irm_flow_destroy(f);
                         return NULL;
                 }
 
@@ -1384,7 +1402,7 @@ static struct irm_flow * flow_req_arr(pid_t  api,
                         pthread_rwlock_unlock(&irmd->state_lock);
                         LOG_ERR("Could not get start apn for reg_entry %s.",
                                 re->name);
-                        free(f);
+                        irm_flow_destroy(f);
                         free(c_api);
                         return NULL;
                 }
@@ -1411,6 +1429,7 @@ static struct irm_flow * flow_req_arr(pid_t  api,
                         pthread_mutex_unlock(&re->state_lock);
                         pthread_rwlock_unlock(&irmd->reg_lock);
                         pthread_rwlock_unlock(&irmd->state_lock);
+                        irm_flow_destroy(f);
                         return NULL;
                 }
 
@@ -1424,6 +1443,7 @@ static struct irm_flow * flow_req_arr(pid_t  api,
                         pthread_rwlock_unlock(&irmd->reg_lock);
                         pthread_rwlock_unlock(&irmd->state_lock);
                         LOG_ERR("Invalid api returned.");
+                        irm_flow_destroy(f);
                         return NULL;
                 }
 
@@ -1432,7 +1452,7 @@ static struct irm_flow * flow_req_arr(pid_t  api,
                 pthread_rwlock_unlock(&irmd->reg_lock);
                 pthread_rwlock_unlock(&irmd->state_lock);
                 LOG_ERR("IRMd in wrong state.");
-                free(f);
+                irm_flow_destroy(f);
                 return NULL;
         }
 
@@ -1441,6 +1461,26 @@ static struct irm_flow * flow_req_arr(pid_t  api,
         pthread_rwlock_wrlock(&irmd->flows_lock);
         f->port_id = bmp_allocate(irmd->port_ids);
 
+        f->n_rb = shm_rbuff_create(f->n_api, f->port_id);
+        if (f->n_rb == NULL) {
+                bmp_release(irmd->port_ids, f->port_id);
+                pthread_rwlock_unlock(&irmd->flows_lock);
+                pthread_rwlock_unlock(&irmd->state_lock);
+                LOG_ERR("Could not create ringbuffer for AP-I %d.", f->n_api);
+                irm_flow_destroy(f);
+                return NULL;
+        }
+
+        f->n_1_rb = shm_rbuff_create(f->n_1_api, f->port_id);
+        if (f->n_1_rb == NULL) {
+                bmp_release(irmd->port_ids, f->port_id);
+                pthread_rwlock_unlock(&irmd->flows_lock);
+                pthread_rwlock_unlock(&irmd->state_lock);
+                LOG_ERR("Could not create ringbuffer for AP-I %d.", f->n_1_api);
+                irm_flow_destroy(f);
+                return NULL;
+        }
+
         list_add(&f->next, &irmd->irm_flows);
 
         pthread_rwlock_unlock(&irmd->flows_lock);
@@ -1455,10 +1495,13 @@ static struct irm_flow * flow_req_arr(pid_t  api,
 
         e = api_table_get(&irmd->api_table, h_api);
         if (e == NULL) {
-                LOG_ERR("Could not get api table entry for %d.", h_api);
                 pthread_rwlock_unlock(&irmd->reg_lock);
+                pthread_rwlock_wrlock(&irmd->flows_lock);
+                bmp_release(irmd->port_ids, f->port_id);
+                pthread_rwlock_unlock(&irmd->flows_lock);
                 pthread_rwlock_unlock(&irmd->state_lock);
-                free(f);
+                LOG_ERR("Could not get api table entry for %d.", h_api);
+                irm_flow_destroy(f);
                 return NULL;
         }
 
@@ -1692,26 +1735,18 @@ void * irm_sanitize()
                         }
 
                         if (kill(f->n_api, 0) < 0) {
-                                struct shm_ap_rbuff * rb =
-                                        shm_ap_rbuff_open(f->n_api);
                                 bmp_release(irmd->port_ids, f->port_id);
                                 list_del(&f->next);
                                 LOG_INFO("AP-I %d gone, flow %d deallocated.",
                                          f->n_api, f->port_id);
                                 ipcp_flow_dealloc(f->n_1_api, f->port_id);
-                                if (rb != NULL)
-                                        shm_ap_rbuff_destroy(rb);
                                 irm_flow_destroy(f);
                                 continue;
                         }
                         if (kill(f->n_1_api, 0) < 0) {
-                                struct shm_ap_rbuff * rb =
-                                        shm_ap_rbuff_open(f->n_1_api);
                                 list_del(&f->next);
                                 LOG_ERR("IPCP %d gone, flow %d removed.",
                                         f->n_1_api, f->port_id);
-                                if (rb != NULL)
-                                        shm_ap_rbuff_destroy(rb);
                                 irm_flow_destroy(f);
                         }
                 }
diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index b94d0eea..20ea473d 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -35,7 +35,8 @@ set(SOURCE_FILES
   lockfile.c
   logs.c
   nsm.c
-  shm_ap_rbuff.c
+  shm_flow_set.c
+  shm_rbuff.c
   shm_rdrbuff.c
   sockets.c
   time_utils.c
diff --git a/src/lib/dev.c b/src/lib/dev.c
index 77c2d06a..146070b7 100644
--- a/src/lib/dev.c
+++ b/src/lib/dev.c
@@ -3,7 +3,8 @@
  *
  * API for applications
  *
- *    Sander Vrijders <sander.vrijders@intec.ugent.be>
+ *    Dimitri Staessens <dimitri.staessens@intec.ugent.be>
+ *    Sander Vrijders   <sander.vrijders@intec.ugent.be>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -26,20 +27,24 @@
 #include <ouroboros/sockets.h>
 #include <ouroboros/fcntl.h>
 #include <ouroboros/bitmap.h>
+#include <ouroboros/shm_flow_set.h>
 #include <ouroboros/shm_rdrbuff.h>
-#include <ouroboros/shm_ap_rbuff.h>
+#include <ouroboros/shm_rbuff.h>
 #include <ouroboros/utils.h>
-#include <ouroboros/select.h>
+#include <ouroboros/fqueue.h>
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 struct flow_set {
-        bool dirty;
-        bool b[IRMD_MAX_FLOWS]; /* working copy */
-        bool s[IRMD_MAX_FLOWS]; /* safe copy */
-        pthread_rwlock_t lock;
+        size_t idx;
+};
+
+struct fqueue {
+        int    fqueue[SHM_BUFFER_SIZE]; /* safe copy from shm */
+        size_t fqsize;
+        size_t next;
 };
 
 enum port_state {
@@ -124,7 +129,9 @@ enum port_state port_wait_assign(struct port * p)
 }
 
 struct flow {
-        struct shm_ap_rbuff * rb;
+        struct shm_rbuff *    rx_rb;
+        struct shm_rbuff *    tx_rb;
+        struct shm_flow_set * set;
         int                   port_id;
         int                   oflags;
 
@@ -139,10 +146,11 @@ struct {
         pid_t                 api;
 
         struct shm_rdrbuff *  rdrb;
-        struct shm_ap_rbuff * rb;
+        struct shm_flow_set * fqset;
         pthread_rwlock_t      data_lock;
 
         struct bmp *          fds;
+        struct bmp *          fqueues;
         struct flow *         flows;
         struct port *         ports;
 
@@ -194,40 +202,52 @@ int ap_init(char * ap_name)
         if (ai.fds == NULL)
                 return -ENOMEM;
 
-        ai.rdrb = shm_rdrbuff_open();
-        if (ai.rdrb == NULL) {
+        ai.fqueues = bmp_create(AP_MAX_FQUEUES, 0);
+        if (ai.fqueues == NULL) {
+                bmp_destroy(ai.fds);
+                return -ENOMEM;
+        }
+
+        ai.fqset = shm_flow_set_create();
+        if (ai.fqset == NULL) {
+                bmp_destroy(ai.fqueues);
                 bmp_destroy(ai.fds);
                 return -1;
         }
 
-        ai.rb = shm_ap_rbuff_create();
-        if (ai.rb == NULL) {
-                shm_rdrbuff_close(ai.rdrb);
+        ai.rdrb = shm_rdrbuff_open();
+        if (ai.rdrb == NULL) {
+                shm_flow_set_destroy(ai.fqset);
+                bmp_destroy(ai.fqueues);
                 bmp_destroy(ai.fds);
                 return -1;
         }
 
         ai.flows = malloc(sizeof(*ai.flows) * AP_MAX_FLOWS);
         if (ai.flows == NULL) {
-                shm_ap_rbuff_destroy(ai.rb);
                 shm_rdrbuff_close(ai.rdrb);
+                shm_flow_set_destroy(ai.fqset);
+                bmp_destroy(ai.fqueues);
                 bmp_destroy(ai.fds);
                 return -1;
         }
 
         for (i = 0; i < AP_MAX_FLOWS; ++i) {
-                ai.flows[i].rb = NULL;
+                ai.flows[i].rx_rb   = NULL;
+                ai.flows[i].tx_rb   = NULL;
+                ai.flows[i].set     = NULL;
                 ai.flows[i].port_id = -1;
-                ai.flows[i].oflags = 0;
-                ai.flows[i].api = -1;
+                ai.flows[i].oflags  = 0;
+                ai.flows[i].api     = -1;
                 ai.flows[i].timeout = NULL;
         }
 
         ai.ports = malloc(sizeof(*ai.ports) * IRMD_MAX_FLOWS);
-        if (ai.flows == NULL) {
+        if (ai.ports == NULL) {
                 free(ai.flows);
-                shm_ap_rbuff_destroy(ai.rb);
                 shm_rdrbuff_close(ai.rdrb);
+                shm_flow_set_destroy(ai.fqset);
+                bmp_destroy(ai.fqueues);
                 bmp_destroy(ai.fds);
                 return -1;
         }
@@ -253,16 +273,10 @@ void ap_fini()
 
         pthread_rwlock_wrlock(&ai.data_lock);
 
-        /* remove all remaining sdus */
-        while ((i = shm_ap_rbuff_pop_idx(ai.rb)) >= 0)
-                shm_rdrbuff_remove(ai.rdrb, i);
-
-        if (ai.fds != NULL)
-                bmp_destroy(ai.fds);
-        if (ai.rb != NULL)
-                shm_ap_rbuff_destroy(ai.rb);
-        if (ai.rdrb != NULL)
-                shm_rdrbuff_close(ai.rdrb);
+        bmp_destroy(ai.fds);
+        bmp_destroy(ai.fqueues);
+        shm_flow_set_destroy(ai.fqset);
+        shm_rdrbuff_close(ai.rdrb);
 
         if (ai.daf_name != NULL)
                 free(ai.daf_name);
@@ -270,8 +284,15 @@ void ap_fini()
         pthread_rwlock_rdlock(&ai.flows_lock);
 
         for (i = 0; i < AP_MAX_FLOWS; ++i) {
-                if (ai.flows[i].rb != NULL)
-                        shm_ap_rbuff_close(ai.flows[i].rb);
+                if (ai.flows[i].tx_rb != NULL) {
+                        int idx;
+                        while ((idx = shm_rbuff_read(ai.flows[i].rx_rb)) >= 0)
+                                shm_rdrbuff_remove(ai.rdrb, idx);
+                        shm_rbuff_close(ai.flows[i].rx_rb);
+                        shm_rbuff_close(ai.flows[i].tx_rb);
+                        shm_flow_set_close(ai.flows[i].set);
+                }
+
                 if (ai.flows[i].timeout != NULL)
                         free(ai.flows[i].timeout);
         }
@@ -328,8 +349,8 @@ int flow_accept(char ** ae_name)
                 return -1;
         }
 
-        ai.flows[fd].rb = shm_ap_rbuff_open(recv_msg->api);
-        if (ai.flows[fd].rb == NULL) {
+        ai.flows[fd].rx_rb = shm_rbuff_open(ai.api, recv_msg->port_id);
+        if (ai.flows[fd].rx_rb == NULL) {
                 bmp_release(ai.fds, fd);
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
@@ -337,10 +358,24 @@ int flow_accept(char ** ae_name)
                 return -1;
         }
 
+        ai.flows[fd].set = shm_flow_set_open(recv_msg->api);
+        if (ai.flows[fd].set == NULL) {
+                bmp_release(ai.fds, fd);
+                shm_rbuff_close(ai.flows[fd].rx_rb);
+                shm_rbuff_close(ai.flows[fd].tx_rb);
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                irm_msg__free_unpacked(recv_msg, NULL);
+                return -1;
+        }
+
+
         if (ae_name != NULL) {
                 *ae_name = strdup(recv_msg->ae_name);
                 if (*ae_name == NULL) {
-                        shm_ap_rbuff_close(ai.flows[fd].rb);
+                        shm_rbuff_close(ai.flows[fd].tx_rb);
+                        shm_rbuff_close(ai.flows[fd].tx_rb);
+                        shm_flow_set_close(ai.flows[fd].set);
                         bmp_release(ai.fds, fd);
                         pthread_rwlock_unlock(&ai.flows_lock);
                         pthread_rwlock_unlock(&ai.data_lock);
@@ -356,8 +391,6 @@ int flow_accept(char ** ae_name)
         ai.ports[recv_msg->port_id].fd    = fd;
         ai.ports[recv_msg->port_id].state = PORT_ID_ASSIGNED;
 
-        shm_ap_rbuff_open_port(ai.rb, recv_msg->port_id);
-
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -410,6 +443,17 @@ int flow_alloc_resp(int fd, int response)
 
         ret = recv_msg->result;
 
+        pthread_rwlock_wrlock(&ai.flows_lock);
+
+        ai.flows[fd].tx_rb = shm_rbuff_open(ai.flows[fd].api,
+                                            ai.flows[fd].port_id);
+        if (ai.flows[fd].tx_rb == NULL) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return -1;
+        }
+
+        pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
         irm_msg__free_unpacked(recv_msg, NULL);
@@ -461,8 +505,11 @@ int flow_alloc(char * dst_name, char * src_ae_name, struct qos_spec * qos)
                 return -1;
         }
 
-        ai.flows[fd].rb = shm_ap_rbuff_open(recv_msg->api);
-        if (ai.flows[fd].rb == NULL) {
+        ai.flows[fd].port_id = recv_msg->port_id;
+        ai.flows[fd].oflags  = FLOW_O_DEFAULT;
+        ai.flows[fd].api     = recv_msg->api;
+        ai.flows[fd].rx_rb   = shm_rbuff_open(ai.api, recv_msg->port_id);
+        if (ai.flows[fd].rx_rb == NULL) {
                 bmp_release(ai.fds, fd);
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
@@ -470,18 +517,12 @@ int flow_alloc(char * dst_name, char * src_ae_name, struct qos_spec * qos)
                 return -1;
         }
 
-        ai.flows[fd].port_id = recv_msg->port_id;
-        ai.flows[fd].oflags  = FLOW_O_DEFAULT;
-        ai.flows[fd].api     = recv_msg->api;
-
         ai.ports[recv_msg->port_id].fd    = fd;
         ai.ports[recv_msg->port_id].state = PORT_ID_ASSIGNED;
 
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
-        shm_ap_rbuff_open_port(ai.rb, recv_msg->port_id);
-
         irm_msg__free_unpacked(recv_msg, NULL);
 
         return fd;
@@ -510,6 +551,23 @@ int flow_alloc_res(int fd)
 
         msg.port_id = ai.flows[fd].port_id;
 
+        ai.flows[fd].tx_rb = shm_rbuff_open(ai.flows[fd].api,
+                                            ai.flows[fd].port_id);
+        if (ai.flows[fd].tx_rb == NULL) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                irm_msg__free_unpacked(recv_msg, NULL);
+                return -1;
+        }
+
+        ai.flows[fd].set = shm_flow_set_open(ai.flows[fd].api);
+        if (ai.flows[fd].set == NULL) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                irm_msg__free_unpacked(recv_msg, NULL);
+                return -1;
+        }
+
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -537,7 +595,7 @@ int flow_dealloc(int fd)
         msg.code         = IRM_MSG_CODE__IRM_FLOW_DEALLOC;
         msg.has_port_id  = true;
         msg.has_api      = true;
-        msg.api          = getpid();
+        msg.api          = ai.api;
 
         pthread_rwlock_rdlock(&ai.data_lock);
         pthread_rwlock_wrlock(&ai.flows_lock);
@@ -548,7 +606,7 @@ int flow_dealloc(int fd)
                 return -ENOTALLOC;
         }
 
-        if (shm_ap_rbuff_close_port(ai.rb, ai.flows[fd].port_id) == -EBUSY) {
+        if (shm_rbuff_block(ai.flows[fd].rx_rb) == -EBUSY) {
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
                 return -EBUSY;
@@ -559,8 +617,10 @@ int flow_dealloc(int fd)
         port_destroy(&ai.ports[msg.port_id]);
 
         ai.flows[fd].port_id = -1;
-        shm_ap_rbuff_close(ai.flows[fd].rb);
-        ai.flows[fd].rb = NULL;
+        shm_rbuff_close(ai.flows[fd].rx_rb);
+        ai.flows[fd].rx_rb = NULL;
+        shm_rbuff_close(ai.flows[fd].tx_rb);
+        ai.flows[fd].tx_rb = NULL;
         ai.flows[fd].oflags = 0;
         ai.flows[fd].api = -1;
         if (ai.flows[fd].timeout != NULL) {
@@ -604,9 +664,9 @@ int flow_cntl(int fd, int cmd, int oflags)
         case FLOW_F_SETFL: /* SET FLOW FLAGS */
                 ai.flows[fd].oflags = oflags;
                 if (oflags & FLOW_O_WRONLY)
-                        shm_ap_rbuff_close_port(ai.rb, ai.flows[fd].port_id);
+                        shm_rbuff_block(ai.flows[fd].rx_rb);
                 if (oflags & FLOW_O_RDWR)
-                        shm_ap_rbuff_open_port(ai.rb, ai.flows[fd].port_id);
+                        shm_rbuff_unblock(ai.flows[fd].rx_rb);
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
                 return old;
@@ -620,7 +680,6 @@ int flow_cntl(int fd, int cmd, int oflags)
 ssize_t flow_write(int fd, void * buf, size_t count)
 {
         ssize_t idx;
-        struct rb_entry e;
 
         if (buf == NULL)
                 return 0;
@@ -653,13 +712,10 @@ ssize_t flow_write(int fd, void * buf, size_t count)
                 if (idx < 0) {
                         pthread_rwlock_unlock(&ai.flows_lock);
                         pthread_rwlock_unlock(&ai.data_lock);
-                        return -idx;
+                        return idx;
                 }
 
-                e.index   = idx;
-                e.port_id = ai.flows[fd].port_id;
-
-                if (shm_ap_rbuff_write(ai.flows[fd].rb, &e) < 0) {
+                if (shm_rbuff_write(ai.flows[fd].tx_rb, idx) < 0) {
                         shm_rdrbuff_remove(ai.rdrb, idx);
                         pthread_rwlock_unlock(&ai.flows_lock);
                         pthread_rwlock_unlock(&ai.data_lock);
@@ -667,7 +723,7 @@ ssize_t flow_write(int fd, void * buf, size_t count)
                 }
         } else { /* blocking */
                 struct shm_rdrbuff * rdrb = ai.rdrb;
-                pid_t                api = ai.flows[fd].api;
+                pid_t                api  = ai.flows[fd].api;
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
 
@@ -681,17 +737,16 @@ ssize_t flow_write(int fd, void * buf, size_t count)
                 pthread_rwlock_rdlock(&ai.data_lock);
                 pthread_rwlock_rdlock(&ai.flows_lock);
 
-                e.index   = idx;
-                e.port_id = ai.flows[fd].port_id;
-
-                if (shm_ap_rbuff_write(ai.flows[fd].rb, &e) < 0) {
-                        shm_rdrbuff_remove(ai.rdrb, e.index);
+                if (shm_rbuff_write(ai.flows[fd].tx_rb, idx) < 0) {
+                        shm_rdrbuff_remove(ai.rdrb, idx);
                         pthread_rwlock_unlock(&ai.flows_lock);
                         pthread_rwlock_unlock(&ai.data_lock);
                         return -ENOTALLOC;
                 }
         }
 
+        shm_flow_set_notify(ai.flows[fd].set, ai.flows[fd].port_id);
+
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -717,15 +772,14 @@ ssize_t flow_read(int fd, void * buf, size_t count)
         }
 
         if (ai.flows[fd].oflags & FLOW_O_NONBLOCK) {
-                idx = shm_ap_rbuff_read_port(ai.rb, ai.flows[fd].port_id);
+                idx = shm_rbuff_read(ai.flows[fd].rx_rb);
                 pthread_rwlock_unlock(&ai.flows_lock);
         } else {
-                struct shm_ap_rbuff * rb      = ai.rb;
-                int                   port_id = ai.flows[fd].port_id;
-                struct timespec *     timeout = ai.flows[fd].timeout;
+                struct shm_rbuff * rb     = ai.flows[fd].rx_rb;
+                struct timespec * timeout = ai.flows[fd].timeout;
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
-                idx = shm_ap_rbuff_read_port_b(rb, port_id, timeout);
+                idx = shm_rbuff_read_b(rb, timeout);
                 pthread_rwlock_rdlock(&ai.data_lock);
         }
 
@@ -757,79 +811,163 @@ struct flow_set * flow_set_create()
         if (set == NULL)
                 return NULL;
 
-        if (pthread_rwlock_init(&set->lock, NULL)) {
+        assert(ai.fqueues);
+
+        set->idx = bmp_allocate(ai.fqueues);
+        if (!bmp_is_id_valid(ai.fqueues, set->idx)) {
                 free(set);
                 return NULL;
         }
 
-        memset(set->b, 0, IRMD_MAX_FLOWS);
-        memset(set->s, 0, IRMD_MAX_FLOWS);
+        return set;
+}
 
-        set->dirty = true;
+void flow_set_destroy(struct flow_set * set)
+{
+        if (set == NULL)
+                return;
 
-        return set;
+        flow_set_zero(set);
+        bmp_release(ai.fqueues, set->idx);
+        free(set);
 }
 
-void flow_set_zero(struct flow_set * set)
+struct fqueue * fqueue_create()
 {
-        pthread_rwlock_wrlock(&set->lock);
-        memset(set->b, 0, IRMD_MAX_FLOWS);
-        set->dirty = true;
-        pthread_rwlock_unlock(&set->lock);
+        struct fqueue * fq = malloc(sizeof(*fq));
+        if (fq == NULL)
+                return NULL;
+
+        memset(fq->fqueue, -1, SHM_BUFFER_SIZE);
+        fq->fqsize = 0;
+        fq->next   = 0;
+
+        return fq;
 }
 
-void flow_set_add(struct flow_set * set, int fd)
+void fqueue_destroy(struct fqueue * fq)
 {
-        pthread_rwlock_wrlock(&set->lock);
-        set->b[ai.flows[fd].port_id] = true;
-        set->dirty = true;
-        pthread_rwlock_unlock(&set->lock);
+        if (fq == NULL)
+                return
+        free(fq);
 }
 
-void flow_set_del(struct flow_set * set, int fd)
+void flow_set_zero(struct flow_set * set)
 {
-        pthread_rwlock_wrlock(&set->lock);
-        set->b[ai.flows[fd].port_id] = false;
-        set->dirty = true;
-        pthread_rwlock_unlock(&set->lock);
+        if (set == NULL)
+                return;
+
+        pthread_rwlock_rdlock(&ai.data_lock);
+
+        shm_flow_set_zero(ai.fqset, set->idx);
+
+        pthread_rwlock_unlock(&ai.data_lock);
 }
 
-bool flow_set_has(struct flow_set * set, int fd)
+int flow_set_add(struct flow_set * set, int fd)
 {
-        bool ret;
-        pthread_rwlock_rdlock(&set->lock);
-        ret = set->b[ai.flows[fd].port_id];
-        pthread_rwlock_unlock(&set->lock);
+        int ret;
+
+        if (set == NULL)
+                return -EINVAL;
+
+        pthread_rwlock_rdlock(&ai.data_lock);
+        pthread_rwlock_rdlock(&ai.flows_lock);
+
+        ret = shm_flow_set_add(ai.fqset, set->idx, ai.flows[fd].port_id);
+
+        pthread_rwlock_unlock(&ai.flows_lock);
+        pthread_rwlock_unlock(&ai.data_lock);
+
         return ret;
 }
 
-void flow_set_destroy(struct flow_set * set)
+void flow_set_del(struct flow_set * set, int fd)
 {
-        pthread_rwlock_destroy(&set->lock);
-        free(set);
+        if (set == NULL)
+                return;
+
+        pthread_rwlock_rdlock(&ai.data_lock);
+        pthread_rwlock_rdlock(&ai.flows_lock);
+
+        if (ai.flows[fd].port_id >= 0)
+                shm_flow_set_del(ai.fqset, set->idx, ai.flows[fd].port_id);
+
+        pthread_rwlock_unlock(&ai.flows_lock);
+        pthread_rwlock_unlock(&ai.data_lock);
 }
 
-static void flow_set_cpy(struct flow_set * set)
+bool flow_set_has(struct flow_set * set, int fd)
 {
-        pthread_rwlock_rdlock(&set->lock);
-        if (set->dirty)
-                memcpy(set->s, set->b, IRMD_MAX_FLOWS);
-        set->dirty = false;
-        pthread_rwlock_unlock(&set->lock);
+        bool ret = false;
+
+        if (set == NULL || fd < 0)
+                return false;
+
+        pthread_rwlock_rdlock(&ai.data_lock);
+        pthread_rwlock_rdlock(&ai.flows_lock);
+
+        if (ai.flows[fd].port_id < 0) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return false;
+        }
+
+        ret = (shm_flow_set_has(ai.fqset, set->idx, ai.flows[fd].port_id) == 1);
+
+        pthread_rwlock_unlock(&ai.flows_lock);
+        pthread_rwlock_unlock(&ai.data_lock);
+
+        return ret;
 }
 
-int flow_select(struct flow_set * set, const struct timespec * timeout)
+int fqueue_next(struct fqueue * fq)
 {
-        int port_id;
-        if (set == NULL) {
-                port_id = shm_ap_rbuff_peek_b(ai.rb, NULL, timeout);
-        } else {
-                flow_set_cpy(set);
-                port_id = shm_ap_rbuff_peek_b(ai.rb, (bool *) set->s, timeout);
+        int fd;
+
+        if (fq == NULL)
+                return -EINVAL;
+
+        if (fq->next == fq->fqsize) {
+                fq->fqsize = 0;
+                fq->next = 0;
+                return -EPERM;
         }
-        if (port_id < 0)
-                return port_id;
-        return ai.ports[port_id].fd;
+
+        pthread_rwlock_rdlock(&ai.data_lock);
+        pthread_rwlock_rdlock(&ai.flows_lock);
+
+        fd = ai.ports[fq->fqueue[fq->next++]].fd;
+
+        pthread_rwlock_unlock(&ai.flows_lock);
+        pthread_rwlock_unlock(&ai.data_lock);
+
+        return fd;
+}
+
+int flow_event_wait(struct flow_set *       set,
+                    struct fqueue *         fq,
+                    const struct timespec * timeout)
+{
+        int ret;
+
+        if (set == NULL)
+                return -EINVAL;
+
+        if (fq->fqsize > 0)
+                return 0;
+
+        ret = shm_flow_set_wait(ai.fqset, set->idx, fq->fqueue, timeout);
+        if (ret == -ETIMEDOUT)
+                return -ETIMEDOUT;
+
+        if (ret < 0)
+                return ret;
+
+        fq->fqsize = ret;
+        fq->next   = 0;
+
+        return 0;
 }
 
 /* ipcp-dev functions */
@@ -848,8 +986,8 @@ int np1_flow_alloc(pid_t n_api, int port_id)
                 return -1;
         }
 
-        ai.flows[fd].rb = shm_ap_rbuff_open(n_api);
-        if (ai.flows[fd].rb == NULL) {
+        ai.flows[fd].rx_rb = shm_rbuff_open(ai.api, port_id);
+        if (ai.flows[fd].rx_rb == NULL) {
                 bmp_release(ai.fds, fd);
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
@@ -863,8 +1001,6 @@ int np1_flow_alloc(pid_t n_api, int port_id)
         ai.ports[port_id].fd = fd;
         port_set_state(&ai.ports[port_id], PORT_ID_ASSIGNED);
 
-        shm_ap_rbuff_open_port(ai.rb, port_id);
-
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
@@ -890,7 +1026,6 @@ int np1_flow_dealloc(int port_id)
 int np1_flow_resp(pid_t n_api, int port_id)
 {
         int fd;
-        struct shm_ap_rbuff * rb;
 
         port_wait_assign(&ai.ports[port_id]);
 
@@ -904,18 +1039,26 @@ int np1_flow_resp(pid_t n_api, int port_id)
                 return fd;
         }
 
-        rb = shm_ap_rbuff_open(n_api);
-        if (rb == NULL) {
+        ai.flows[fd].tx_rb = shm_rbuff_open(n_api, port_id);
+        if (ai.flows[fd].tx_rb == NULL) {
                 ai.flows[fd].port_id = -1;
+                shm_rbuff_close(ai.flows[fd].rx_rb);
                 port_destroy(&ai.ports[port_id]);
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
                 return -1;
         }
 
-        ai.flows[fd].rb = rb;
-
-        shm_ap_rbuff_open_port(ai.rb, port_id);
+        ai.flows[fd].set = shm_flow_set_open(n_api);
+        if (ai.flows[fd].set == NULL) {
+                shm_rbuff_close(ai.flows[fd].tx_rb);
+                ai.flows[fd].port_id = -1;
+                shm_rbuff_close(ai.flows[fd].rx_rb);
+                port_destroy(&ai.ports[port_id]);
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return -1;
+        }
 
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
@@ -929,9 +1072,9 @@ int ipcp_create_r(pid_t api)
         irm_msg_t * recv_msg = NULL;
         int ret = -1;
 
-        msg.code         = IRM_MSG_CODE__IPCP_CREATE_R;
-        msg.has_api      = true;
-        msg.api          = api;
+        msg.code    = IRM_MSG_CODE__IPCP_CREATE_R;
+        msg.has_api = true;
+        msg.api     = api;
 
         recv_msg = send_recv_irm_msg(&msg);
         if (recv_msg == NULL)
@@ -958,11 +1101,11 @@ int ipcp_flow_req_arr(pid_t  api, char * dst_name, char * src_ae_name)
         if (dst_name == NULL || src_ae_name == NULL)
                 return -EINVAL;
 
-        msg.code          = IRM_MSG_CODE__IPCP_FLOW_REQ_ARR;
-        msg.has_api       = true;
-        msg.api           = api;
-        msg.dst_name      = dst_name;
-        msg.ae_name       = src_ae_name;
+        msg.code     = IRM_MSG_CODE__IPCP_FLOW_REQ_ARR;
+        msg.has_api  = true;
+        msg.api      = api;
+        msg.dst_name = dst_name;
+        msg.ae_name  = src_ae_name;
 
         pthread_rwlock_rdlock(&ai.data_lock);
         pthread_rwlock_wrlock(&ai.flows_lock);
@@ -974,7 +1117,7 @@ int ipcp_flow_req_arr(pid_t  api, char * dst_name, char * src_ae_name)
                 return -1; /* -ENOMOREFDS */
         }
 
-        ai.flows[fd].rb    = NULL;
+        ai.flows[fd].tx_rb    = NULL;
 
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
@@ -996,8 +1139,16 @@ int ipcp_flow_req_arr(pid_t  api, char * dst_name, char * src_ae_name)
         pthread_rwlock_rdlock(&ai.data_lock);
         pthread_rwlock_wrlock(&ai.flows_lock);
 
+        ai.flows[fd].rx_rb = shm_rbuff_open(ai.api, port_id);
+        if (ai.flows[fd].rx_rb == NULL) {
+                ai.flows[fd].port_id = -1;
+                port_destroy(&ai.ports[port_id]);
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return -1;
+        }
+
         ai.flows[fd].port_id = port_id;
-        ai.flows[fd].rb      = NULL;
 
         ai.ports[port_id].fd = fd;
         port_set_state(&(ai.ports[port_id]), PORT_ID_ASSIGNED);
@@ -1019,16 +1170,13 @@ int ipcp_flow_alloc_reply(int fd, int response)
 
         pthread_rwlock_rdlock(&ai.data_lock);
         pthread_rwlock_rdlock(&ai.flows_lock);
-        msg.port_id      = ai.flows[fd].port_id;
+        msg.port_id = ai.flows[fd].port_id;
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
         msg.has_response = true;
         msg.response     = response;
 
-        if (response)
-                shm_ap_rbuff_open_port(ai.rb, msg.port_id);
-
         recv_msg = send_recv_irm_msg(&msg);
         if (recv_msg == NULL)
                 return -1;
@@ -1039,6 +1187,26 @@ int ipcp_flow_alloc_reply(int fd, int response)
         }
 
         ret = recv_msg->result;
+
+        pthread_rwlock_wrlock(&ai.flows_lock);
+
+        ai.flows[fd].tx_rb = shm_rbuff_open(ai.flows[fd].api,
+                                            ai.flows[fd].port_id);
+        if (ai.flows[fd].tx_rb == NULL) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return -1;
+        }
+
+        ai.flows[fd].set = shm_flow_set_open(ai.flows[fd].api);
+        if (ai.flows[fd].set == NULL) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return -1;
+        }
+
+        pthread_rwlock_unlock(&ai.flows_lock);
+
         irm_msg__free_unpacked(recv_msg, NULL);
 
         return ret;
@@ -1061,7 +1229,7 @@ int ipcp_flow_read(int fd, struct shm_du_buff ** sdb)
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
-        idx = shm_ap_rbuff_read_port(ai.rb, port_id);
+        idx = shm_rbuff_read(ai.flows[fd].rx_rb);
         if (idx < 0) {
                 pthread_rwlock_rdlock(&ai.data_lock);
                 pthread_rwlock_rdlock(&ai.flows_lock);
@@ -1081,7 +1249,7 @@ int ipcp_flow_read(int fd, struct shm_du_buff ** sdb)
 
 int ipcp_flow_write(int fd, struct shm_du_buff * sdb)
 {
-        struct rb_entry e;
+        ssize_t idx;
 
         if (sdb == NULL)
                 return -EINVAL;
@@ -1095,16 +1263,16 @@ int ipcp_flow_write(int fd, struct shm_du_buff * sdb)
                 return -EPERM;
         }
 
-        if (ai.flows[fd].rb == NULL) {
+        if (ai.flows[fd].tx_rb == NULL) {
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
                 return -EPERM;
         }
 
-        e.index = shm_du_buff_get_idx(sdb);
-        e.port_id = ai.flows[fd].port_id;
+        idx = shm_du_buff_get_idx(sdb);
 
-        shm_ap_rbuff_write(ai.flows[fd].rb, &e);
+        shm_rbuff_write(ai.flows[fd].tx_rb, idx);
+        shm_flow_set_notify(ai.flows[fd].set, ai.flows[fd].port_id);
 
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
@@ -1112,46 +1280,28 @@ int ipcp_flow_write(int fd, struct shm_du_buff * sdb)
         return 0;
 }
 
-struct rb_entry * local_flow_read(int fd)
+ssize_t local_flow_read(int fd)
 {
-        int port_id;
-        struct rb_entry * e = NULL;
-
-        pthread_rwlock_rdlock(&ai.data_lock);
-        pthread_rwlock_rdlock(&ai.flows_lock);
-
-        port_id = ai.flows[fd].port_id;
-
-        pthread_rwlock_unlock(&ai.flows_lock);
-        pthread_rwlock_unlock(&ai.data_lock);
-
-        if (port_id != -1) {
-                e = malloc(sizeof(*e));
-                if (e == NULL)
-                        return NULL;
-                e->index = shm_ap_rbuff_read_port(ai.rb, port_id);
-        }
-
-        return e;
+        return shm_rbuff_read(ai.flows[fd].rx_rb);
 }
 
-int local_flow_write(int fd, struct rb_entry * e)
+int local_flow_write(int fd, ssize_t idx)
 {
-        if (e == NULL || fd < 0)
+        if (fd < 0)
                 return -EINVAL;
 
         pthread_rwlock_rdlock(&ai.data_lock);
         pthread_rwlock_rdlock(&ai.flows_lock);
 
-        if (ai.flows[fd].rb == NULL) {
+        if (ai.flows[fd].tx_rb == NULL) {
                 pthread_rwlock_unlock(&ai.flows_lock);
                 pthread_rwlock_unlock(&ai.data_lock);
                 return -EPERM;
         }
 
-        e->port_id = ai.flows[fd].port_id;
+        shm_rbuff_write(ai.flows[fd].tx_rb, idx);
 
-        shm_ap_rbuff_write(ai.flows[fd].rb, e);
+        shm_flow_set_notify(ai.flows[fd].set, ai.flows[fd].port_id);
 
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
@@ -1159,22 +1309,26 @@ int local_flow_write(int fd, struct rb_entry * e)
         return 0;
 }
 
-int ipcp_read_shim(struct shm_du_buff ** sdb)
+int ipcp_read_shim(int fd, struct shm_du_buff ** sdb)
 {
-        int fd;
-        struct rb_entry * e = shm_ap_rbuff_read(ai.rb);
+        ssize_t idx;
 
         pthread_rwlock_rdlock(&ai.data_lock);
         pthread_rwlock_rdlock(&ai.flows_lock);
 
-        fd = ai.ports[e->port_id].fd;
+        if (ai.flows[fd].rx_rb == NULL) {
+                pthread_rwlock_unlock(&ai.flows_lock);
+                pthread_rwlock_unlock(&ai.data_lock);
+                return -EPERM;
+        }
 
-        *sdb = shm_rdrbuff_get(ai.rdrb, e->index);
+        idx = shm_rbuff_read(ai.flows[fd].rx_rb);
+        *sdb = shm_rdrbuff_get(ai.rdrb, idx);
 
         pthread_rwlock_unlock(&ai.flows_lock);
         pthread_rwlock_unlock(&ai.data_lock);
 
-        return fd;
+        return 0;
 }
 
 void ipcp_flow_del(struct shm_du_buff * sdb)
diff --git a/src/lib/lockfile.c b/src/lib/lockfile.c
index 04ce9324..a0222f18 100644
--- a/src/lib/lockfile.c
+++ b/src/lib/lockfile.c
@@ -39,10 +39,10 @@
 
 struct lockfile {
         pid_t * api;
-        int fd;
 };
 
 struct lockfile * lockfile_create() {
+        int fd;
         mode_t mask;
         struct lockfile * lf = malloc(sizeof(*lf));
         if (lf == NULL)
@@ -50,8 +50,8 @@ struct lockfile * lockfile_create() {
 
         mask = umask(0);
 
-        lf->fd = shm_open(LOCKFILE_NAME, O_CREAT | O_EXCL | O_RDWR, 0666);
-        if (lf->fd == -1) {
+        fd = shm_open(LOCKFILE_NAME, O_CREAT | O_EXCL | O_RDWR, 0666);
+        if (fd == -1) {
                 LOG_DBGF("Could not create lock file.");
                 free(lf);
                 return NULL;
@@ -59,30 +59,24 @@ struct lockfile * lockfile_create() {
 
         umask(mask);
 
-        if (ftruncate(lf->fd, LF_SIZE - 1) < 0) {
+        if (ftruncate(fd, LF_SIZE - 1) < 0) {
                 LOG_DBGF("Failed to extend lockfile.");
                 free(lf);
                 return NULL;
         }
-#ifndef __APPLE__
-        if (write(lf->fd, "", 1) != 1) {
-                LOG_DBGF("Failed to finalise lockfile.");
-                free(lf);
-                return NULL;
-        }
-#endif
+
         lf->api = mmap(NULL,
                        LF_SIZE, PROT_READ | PROT_WRITE,
                        MAP_SHARED,
-                       lf->fd,
+                       fd,
                        0);
 
+        close (fd);
+
         if (lf->api == MAP_FAILED) {
                 LOG_DBGF("Failed to map lockfile.");
-
                 if (shm_unlink(LOCKFILE_NAME) == -1)
                         LOG_DBGF("Failed to remove invalid lockfile.");
-
                 free(lf);
                 return NULL;
         }
@@ -93,12 +87,13 @@ struct lockfile * lockfile_create() {
 }
 
 struct lockfile * lockfile_open() {
+        int fd;
         struct lockfile * lf = malloc(sizeof(*lf));
         if (lf == NULL)
                 return NULL;
 
-        lf->fd = shm_open(LOCKFILE_NAME, O_RDWR, 0666);
-        if (lf->fd < 0) {
+        fd = shm_open(LOCKFILE_NAME, O_RDWR, 0666);
+        if (fd < 0) {
                 LOG_DBGF("Could not open lock file.");
                 free(lf);
                 return NULL;
@@ -107,15 +102,15 @@ struct lockfile * lockfile_open() {
         lf->api = mmap(NULL,
                        LF_SIZE, PROT_READ | PROT_WRITE,
                        MAP_SHARED,
-                       lf->fd,
+                       fd,
                        0);
 
+        close(fd);
+
         if (lf->api == MAP_FAILED) {
                 LOG_DBGF("Failed to map lockfile.");
-
                 if (shm_unlink(LOCKFILE_NAME) == -1)
                         LOG_DBGF("Failed to remove invalid lockfile.");
-
                 free(lf);
                 return NULL;
         }
@@ -130,9 +125,6 @@ void lockfile_close(struct lockfile * lf)
                 return;
         }
 
-        if (close(lf->fd) < 0)
-                LOG_DBGF("Couldn't close lockfile.");
-
         if (munmap(lf->api, LF_SIZE) == -1)
                 LOG_DBGF("Couldn't unmap lockfile.");
 
@@ -151,9 +143,6 @@ void lockfile_destroy(struct lockfile * lf)
                 return;
         }
 
-        if (close(lf->fd) < 0)
-                LOG_DBGF("Couldn't close lockfile.");
-
         if (munmap(lf->api, LF_SIZE) == -1)
                 LOG_DBGF("Couldn't unmap lockfile.");
 
diff --git a/src/lib/shm_ap_rbuff.c b/src/lib/shm_ap_rbuff.c
deleted file mode 100644
index 5cbf5bd0..00000000
--- a/src/lib/shm_ap_rbuff.c
+++ /dev/null
@@ -1,661 +0,0 @@
-/*
- * Ouroboros - Copyright (C) 2016
- *
- * Ring buffer for application processes
- *
- *    Dimitri Staessens <dimitri.staessens@intec.ugent.be>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-#include <ouroboros/config.h>
-#include <ouroboros/shm_ap_rbuff.h>
-#include <ouroboros/lockfile.h>
-#include <ouroboros/time_utils.h>
-#include <ouroboros/errno.h>
-
-#define OUROBOROS_PREFIX "shm_ap_rbuff"
-
-#include <ouroboros/logs.h>
-
-#include <pthread.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdint.h>
-#include <unistd.h>
-#include <signal.h>
-#include <sys/stat.h>
-#include <assert.h>
-
-#define FN_MAX_CHARS 255
-
-#define SHM_RBUFF_FILE_SIZE (SHM_BUFFER_SIZE * sizeof(struct rb_entry)         \
-                             + IRMD_MAX_FLOWS * sizeof(int8_t)                 \
-                             + IRMD_MAX_FLOWS * sizeof (ssize_t)               \
-                             + 2 * sizeof(size_t) + sizeof(pthread_mutex_t)    \
-                             + 2 * sizeof (pthread_cond_t))
-
-#define shm_rbuff_used(rb)((*rb->head + SHM_BUFFER_SIZE - *rb->tail)   \
-                          & (SHM_BUFFER_SIZE - 1))
-#define shm_rbuff_free(rb)(shm_rbuff_used(rb) + 1 < SHM_BUFFER_SIZE)
-#define shm_rbuff_empty(rb) (*rb->head == *rb->tail)
-#define head_el_ptr(rb) (rb->shm_base + *rb->head)
-#define tail_el_ptr(rb) (rb->shm_base + *rb->tail)
-
-struct shm_ap_rbuff {
-        struct rb_entry * shm_base; /* start of entry                */
-        size_t *          head;     /* start of ringbuffer head      */
-        size_t *          tail;     /* start of ringbuffer tail      */
-        int8_t *          acl;      /* start of port_id access table */
-        ssize_t *         cntrs;    /* start of port_id counters     */
-        pthread_mutex_t * lock;     /* lock all free space in shm    */
-        pthread_cond_t *  add;      /* SDU arrived                   */
-        pthread_cond_t *  del;      /* SDU removed                   */
-        pid_t             api;      /* api to which this rb belongs  */
-        int               fd;
-};
-
-struct shm_ap_rbuff * shm_ap_rbuff_create()
-{
-        struct shm_ap_rbuff * rb;
-        int                   shm_fd;
-        struct rb_entry *     shm_base;
-        pthread_mutexattr_t   mattr;
-        pthread_condattr_t    cattr;
-        char                  fn[FN_MAX_CHARS];
-        mode_t                mask;
-        int                   i;
-
-        sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", getpid());
-
-        rb = malloc(sizeof(*rb));
-        if (rb == NULL) {
-                LOG_DBG("Could not allocate struct.");
-                return NULL;
-        }
-
-        mask = umask(0);
-
-        shm_fd = shm_open(fn, O_CREAT | O_EXCL | O_RDWR, 0666);
-        if (shm_fd == -1) {
-                LOG_DBG("Failed creating ring buffer.");
-                free(rb);
-                return NULL;
-        }
-
-        umask(mask);
-
-        if (ftruncate(shm_fd, SHM_RBUFF_FILE_SIZE - 1) < 0) {
-                LOG_DBG("Failed to extend ringbuffer.");
-                free(rb);
-                return NULL;
-        }
-#ifndef __APPLE__
-        if (write(shm_fd, "", 1) != 1) {
-                LOG_DBG("Failed to finalise extension of ringbuffer.");
-                free(rb);
-                return NULL;
-        }
-#endif
-        shm_base = mmap(NULL,
-                        SHM_RBUFF_FILE_SIZE,
-                        PROT_READ | PROT_WRITE,
-                        MAP_SHARED,
-                        shm_fd,
-                        0);
-
-        if (shm_base == MAP_FAILED) {
-                LOG_DBG("Failed to map shared memory.");
-                if (close(shm_fd) == -1)
-                        LOG_DBG("Failed to close invalid shm.");
-
-                if (shm_unlink(fn) == -1)
-                        LOG_DBG("Failed to remove invalid shm.");
-
-                free(rb);
-                return NULL;
-        }
-
-        rb->shm_base = shm_base;
-        rb->head     = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
-        rb->tail     = rb->head + 1;
-        rb->acl      = (int8_t *) (rb->tail + 1);
-        rb->cntrs    = (ssize_t *) (rb->acl + IRMD_MAX_FLOWS);
-        rb->lock     = (pthread_mutex_t *) (rb->cntrs + IRMD_MAX_FLOWS);
-        rb->add      = (pthread_cond_t *) (rb->lock + 1);
-        rb->del      = rb->add + 1;
-
-        pthread_mutexattr_init(&mattr);
-#ifndef __APPLE__
-        pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST);
-#endif
-        pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
-        pthread_mutex_init(rb->lock, &mattr);
-
-        pthread_condattr_init(&cattr);
-        pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
-#ifndef __APPLE__
-        pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
-#endif
-        for (i = 0; i < IRMD_MAX_FLOWS; ++i) {
-                rb->cntrs[i] = 0;
-                rb->acl[i] = -1;
-        }
-
-        pthread_cond_init(rb->add, &cattr);
-        pthread_cond_init(rb->del, &cattr);
-
-        *rb->head = 0;
-        *rb->tail = 0;
-
-        rb->fd  = shm_fd;
-        rb->api = getpid();
-
-        return rb;
-}
-
-struct shm_ap_rbuff * shm_ap_rbuff_open(pid_t api)
-{
-        struct shm_ap_rbuff * rb;
-        int                   shm_fd;
-        struct rb_entry *     shm_base;
-        char                  fn[FN_MAX_CHARS];
-
-        sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", api);
-
-        rb = malloc(sizeof(*rb));
-        if (rb == NULL) {
-                LOG_DBG("Could not allocate struct.");
-                return NULL;
-        }
-
-        shm_fd = shm_open(fn, O_RDWR, 0666);
-        if (shm_fd == -1) {
-                LOG_DBG("%d failed opening shared memory %s.", getpid(), fn);
-                free(rb);
-                return NULL;
-        }
-
-        shm_base = mmap(NULL,
-                        SHM_RBUFF_FILE_SIZE,
-                        PROT_READ | PROT_WRITE,
-                        MAP_SHARED,
-                        shm_fd,
-                        0);
-
-        if (shm_base == MAP_FAILED) {
-                LOG_DBG("Failed to map shared memory.");
-                if (close(shm_fd) == -1)
-                        LOG_DBG("Failed to close invalid shm.");
-
-                if (shm_unlink(fn) == -1)
-                        LOG_DBG("Failed to remove invalid shm.");
-
-                free(rb);
-                return NULL;
-        }
-
-        rb->shm_base = shm_base;
-        rb->head     = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
-        rb->tail     = rb->head + 1;
-        rb->acl      = (int8_t *) (rb->tail + 1);
-        rb->cntrs    = (ssize_t *) (rb->acl + IRMD_MAX_FLOWS);
-        rb->lock     = (pthread_mutex_t *) (rb->cntrs + IRMD_MAX_FLOWS);
-        rb->add      = (pthread_cond_t *) (rb->lock + 1);
-        rb->del      = rb->add + 1;
-
-        rb->fd = shm_fd;
-        rb->api = api;
-
-        return rb;
-}
-
-void shm_ap_rbuff_close(struct shm_ap_rbuff * rb)
-{
-        assert(rb);
-
-        if (close(rb->fd) < 0)
-                LOG_DBG("Couldn't close shared memory.");
-
-        if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
-                LOG_DBG("Couldn't unmap shared memory.");
-
-        free(rb);
-}
-
-void shm_ap_rbuff_open_port(struct shm_ap_rbuff * rb, int port_id)
-{
-        assert(rb);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        rb->acl[port_id] = 0; /* open */
-
-        pthread_mutex_unlock(rb->lock);
-}
-
-int shm_ap_rbuff_close_port(struct shm_ap_rbuff * rb, int port_id)
-{
-        int ret = 0;
-
-        assert(rb);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        rb->acl[port_id] = -1;
-
-        if (rb->cntrs[port_id] > 0)
-                ret = -EBUSY;
-
-        pthread_mutex_unlock(rb->lock);
-
-        return ret;
-}
-
-void shm_ap_rbuff_destroy(struct shm_ap_rbuff * rb)
-{
-        char fn[25];
-        struct lockfile * lf = NULL;
-
-        assert(rb);
-
-        if (rb->api != getpid()) {
-                lf = lockfile_open();
-                if (lf == NULL)
-                        return;
-                if (lockfile_owner(lf) == getpid()) {
-                        LOG_DBG("Ringbuffer %d destroyed by IRMd %d.",
-                                 rb->api, getpid());
-                        lockfile_close(lf);
-                } else {
-                        LOG_ERR("AP-I %d tried to destroy rbuff owned by %d.",
-                                getpid(), rb->api);
-                        lockfile_close(lf);
-                        return;
-                }
-        }
-
-        if (close(rb->fd) < 0)
-                LOG_DBG("Couldn't close shared memory.");
-
-        sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", rb->api);
-
-        if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
-                LOG_DBG("Couldn't unmap shared memory.");
-
-        if (shm_unlink(fn) == -1)
-                LOG_DBG("Failed to unlink shm.");
-
-        free(rb);
-}
-
-int shm_ap_rbuff_write(struct shm_ap_rbuff * rb, struct rb_entry * e)
-{
-        assert(rb);
-        assert(e);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        if (rb->acl[e->port_id]) {
-                pthread_mutex_unlock(rb->lock);
-                return -ENOTALLOC;
-        }
-
-        if (!shm_rbuff_free(rb)) {
-                pthread_mutex_unlock(rb->lock);
-                return -1;
-        }
-
-        if (shm_rbuff_empty(rb))
-                pthread_cond_broadcast(rb->add);
-
-        *head_el_ptr(rb) = *e;
-        *rb->head = (*rb->head + 1) & (SHM_BUFFER_SIZE -1);
-
-        ++rb->cntrs[e->port_id];
-
-        pthread_mutex_unlock(rb->lock);
-
-        return 0;
-}
-
-int shm_ap_rbuff_pop_idx(struct shm_ap_rbuff * rb)
-{
-        int ret = 0;
-
-        assert(rb);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        if (shm_rbuff_empty(rb)) {
-                pthread_mutex_unlock(rb->lock);
-                return -1;
-        }
-
-        ret = tail_el_ptr(rb)->index;
-        --rb->cntrs[tail_el_ptr(rb)->port_id];
-        *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
-
-        pthread_mutex_unlock(rb->lock);
-
-        return ret;
-}
-
-static int shm_ap_rbuff_peek_b_all(struct shm_ap_rbuff * rb,
-                                   const struct timespec * timeout)
-{
-        struct timespec abstime;
-        int ret = 0;
-
-        assert(rb);
-
-        if (timeout != NULL) {
-                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
-                ts_add(&abstime, timeout, &abstime);
-        }
-
-        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
-                             (void *) rb->lock);
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        while (shm_rbuff_empty(rb)) {
-                if (timeout != NULL)
-                        ret = pthread_cond_timedwait(rb->add,
-                                                     rb->lock,
-                                                     &abstime);
-                else
-                        ret = pthread_cond_wait(rb->add, rb->lock);
-#ifndef __APPLE__
-                if (ret == EOWNERDEAD) {
-                        LOG_DBG("Recovering dead mutex.");
-                        pthread_mutex_consistent(rb->lock);
-                }
-#endif
-                if (ret == ETIMEDOUT)
-                        break;
-        }
-
-        if (ret != ETIMEDOUT)
-                ret = tail_el_ptr(rb)->port_id;
-        else
-                ret = -ETIMEDOUT;
-
-        pthread_cleanup_pop(true);
-
-        return ret;
-}
-
-int shm_ap_rbuff_peek_b(struct shm_ap_rbuff *   rb,
-                        bool *                  set,
-                        const struct timespec * timeout)
-{
-        struct timespec abstime;
-        int ret;
-
-        assert(rb);
-
-        if (set == NULL)
-                return shm_ap_rbuff_peek_b_all(rb, timeout);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        if (timeout != NULL) {
-                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
-                ts_add(&abstime, timeout, &abstime);
-        }
-
-        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
-                             (void *) rb->lock);
-
-        while ((shm_rbuff_empty(rb) || !set[tail_el_ptr(rb)->port_id])
-               && (ret != ETIMEDOUT)) {
-                while (shm_rbuff_empty(rb)) {
-                        if (timeout != NULL)
-                                ret = pthread_cond_timedwait(rb->add,
-                                                             rb->lock,
-                                                             &abstime);
-                        else
-                                ret = pthread_cond_wait(rb->add, rb->lock);
-
-#ifndef __APPLE__
-                        if (ret == EOWNERDEAD) {
-                                LOG_DBG("Recovering dead mutex.");
-                                pthread_mutex_consistent(rb->lock);
-                        }
-#endif
-                        if (ret == ETIMEDOUT)
-                                break;
-                }
-
-                while (!set[tail_el_ptr(rb)->port_id]) {
-                        if (timeout != NULL)
-                                ret = pthread_cond_timedwait(rb->del,
-                                                             rb->lock,
-                                                             &abstime);
-                        else
-                                ret = pthread_cond_wait(rb->del, rb->lock);
-
-#ifndef __APPLE__
-                        if (ret == EOWNERDEAD) {
-                                LOG_DBG("Recovering dead mutex.");
-                                pthread_mutex_consistent(rb->lock);
-                        }
-#endif
-                        if (ret == ETIMEDOUT)
-                                break;
-                }
-        }
-
-        if (ret != ETIMEDOUT)
-                ret = tail_el_ptr(rb)->port_id;
-        else
-                ret = -ETIMEDOUT;
-
-        pthread_cleanup_pop(true);
-
-        return ret;
-}
-
-
-struct rb_entry * shm_ap_rbuff_read(struct shm_ap_rbuff * rb)
-{
-        struct rb_entry * e = NULL;
-
-        assert(rb);
-
-        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
-                             (void *) rb->lock);
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        while (shm_rbuff_empty(rb))
-#ifdef __APPLE__
-                pthread_cond_wait(rb->add, rb->lock);
-#else
-                if (pthread_cond_wait(rb->add, rb->lock) == EOWNERDEAD) {
-                        LOG_DBG("Recovering dead mutex.");
-                        pthread_mutex_consistent(rb->lock);
-                }
-#endif
-        e = malloc(sizeof(*e));
-        if (e != NULL) {
-                *e = *(rb->shm_base + *rb->tail);
-                --rb->cntrs[e->port_id];
-                *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
-        }
-
-        pthread_cleanup_pop(true);
-
-        return e;
-}
-
-ssize_t shm_ap_rbuff_read_port(struct shm_ap_rbuff * rb, int port_id)
-{
-        ssize_t idx = -1;
-
-        assert(rb);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        if (shm_rbuff_empty(rb) || tail_el_ptr(rb)->port_id != port_id) {
-                pthread_mutex_unlock(rb->lock);
-                return -1;
-        }
-
-        idx = tail_el_ptr(rb)->index;
-        --rb->cntrs[port_id];
-        *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
-
-        pthread_cond_broadcast(rb->del);
-        pthread_mutex_unlock(rb->lock);
-
-        return idx;
-}
-
-ssize_t shm_ap_rbuff_read_port_b(struct shm_ap_rbuff *   rb,
-                                 int                     port_id,
-                                 const struct timespec * timeout)
-{
-        struct timespec abstime;
-        int ret = 0;
-        ssize_t idx = -1;
-
-        assert(rb);
-
-#ifdef __APPLE__
-        pthread_mutex_lock(rb->lock);
-#else
-        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
-                LOG_DBG("Recovering dead mutex.");
-                pthread_mutex_consistent(rb->lock);
-        }
-#endif
-        if (timeout != NULL) {
-                idx = -ETIMEDOUT;
-                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
-                ts_add(&abstime, timeout, &abstime);
-        }
-
-        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
-                             (void *) rb->lock);
-
-        while ((shm_rbuff_empty(rb) || tail_el_ptr(rb)->port_id != port_id)
-               && (ret != ETIMEDOUT)) {
-                while (shm_rbuff_empty(rb)) {
-                        if (timeout != NULL)
-                                ret = pthread_cond_timedwait(rb->add,
-                                                             rb->lock,
-                                                             &abstime);
-                        else
-                                ret = pthread_cond_wait(rb->add, rb->lock);
-#ifndef __APPLE__
-                        if (ret == EOWNERDEAD) {
-                                LOG_DBG("Recovering dead mutex.");
-                                pthread_mutex_consistent(rb->lock);
-                        }
-#endif
-                        if (ret == ETIMEDOUT)
-                                break;
-                }
-
-                while (tail_el_ptr(rb)->port_id != port_id) {
-                        if (timeout != NULL)
-                                ret = pthread_cond_timedwait(rb->del,
-                                                             rb->lock,
-                                                             &abstime);
-                        else
-                                ret = pthread_cond_wait(rb->del, rb->lock);
-#ifndef __APPLE__
-                        if (ret == EOWNERDEAD) {
-                                LOG_DBG("Recovering dead mutex.");
-                                pthread_mutex_consistent(rb->lock);
-                        }
-#endif
-                        if (ret == ETIMEDOUT)
-                                break;
-                }
-        }
-
-        if (ret != ETIMEDOUT) {
-                idx = tail_el_ptr(rb)->index;
-                --rb->cntrs[port_id];
-                *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
-
-                pthread_cond_broadcast(rb->del);
-        }
-
-        pthread_cleanup_pop(true);
-
-        return idx;
-}
-
-void shm_ap_rbuff_reset(struct shm_ap_rbuff * rb)
-{
-        assert(rb);
-
-        pthread_mutex_lock(rb->lock);
-        *rb->tail = 0;
-        *rb->head = 0;
-        pthread_mutex_unlock(rb->lock);
-}
diff --git a/src/lib/shm_flow_set.c b/src/lib/shm_flow_set.c
new file mode 100644
index 00000000..04de9fc5
--- /dev/null
+++ b/src/lib/shm_flow_set.c
@@ -0,0 +1,407 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Management of flow_sets for fqueue
+ *
+ *    Dimitri Staessens <dimitri.staessens@intec.ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <ouroboros/config.h>
+#include <ouroboros/lockfile.h>
+#include <ouroboros/time_utils.h>
+#include <ouroboros/shm_flow_set.h>
+#include <ouroboros/fqueue.h>
+#include <ouroboros/errno.h>
+
+#define OUROBOROS_PREFIX "shm_flow_set"
+
+#include <ouroboros/logs.h>
+
+#include <pthread.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <assert.h>
+
+#define FN_MAX_CHARS 255
+
+#define FQUEUESIZE (SHM_BUFFER_SIZE * sizeof(int))
+
+#define SHM_FLOW_SET_FILE_SIZE (IRMD_MAX_FLOWS * sizeof(ssize_t)          \
+                                + AP_MAX_FQUEUES * sizeof(size_t)         \
+                                + AP_MAX_FQUEUES * sizeof(pthread_cond_t) \
+                                + AP_MAX_FQUEUES * FQUEUESIZE             \
+                                + sizeof(pthread_mutex_t))
+
+#define fqueue_ptr(fs, idx) (fs->fqueues + SHM_BUFFER_SIZE * idx)
+
+struct shm_flow_set {
+        ssize_t *         mtable;
+        size_t *          heads;
+        pthread_cond_t *  conds;
+        int *             fqueues;
+        pthread_mutex_t * lock;
+
+        pid_t             api;
+};
+
+struct shm_flow_set * shm_flow_set_create()
+{
+        struct shm_flow_set * set;
+        ssize_t *             shm_base;
+        pthread_mutexattr_t   mattr;
+        pthread_condattr_t    cattr;
+        char                  fn[FN_MAX_CHARS];
+        mode_t                mask;
+        int                   shm_fd;
+        int                   i;
+
+        sprintf(fn, SHM_FLOW_SET_PREFIX "%d", getpid());
+
+        set = malloc(sizeof(*set));
+        if (set == NULL) {
+                LOG_DBG("Could not allocate struct.");
+                return NULL;
+        }
+
+        mask = umask(0);
+
+        shm_fd = shm_open(fn, O_CREAT | O_EXCL | O_RDWR, 0666);
+        if (shm_fd == -1) {
+                LOG_DBG("Failed creating flag file.");
+                free(set);
+                return NULL;
+        }
+
+        umask(mask);
+
+        if (ftruncate(shm_fd, SHM_FLOW_SET_FILE_SIZE - 1) < 0) {
+                LOG_DBG("Failed to extend flag file.");
+                free(set);
+                close(shm_fd);
+                return NULL;
+        }
+
+        shm_base = mmap(NULL,
+                        SHM_FLOW_SET_FILE_SIZE,
+                        PROT_READ | PROT_WRITE,
+                        MAP_SHARED,
+                        shm_fd,
+                        0);
+
+        close(shm_fd);
+
+        if (shm_base == MAP_FAILED) {
+                LOG_DBG("Failed to map shared memory.");
+                if (shm_unlink(fn) == -1)
+                        LOG_DBG("Failed to remove invalid shm.");
+
+                free(set);
+                return NULL;
+        }
+
+        set->mtable  = shm_base;
+        set->heads   = (size_t *) (set->mtable + IRMD_MAX_FLOWS);
+        set->conds   = (pthread_cond_t *)(set->heads + AP_MAX_FQUEUES);
+        set->fqueues = (int *) (set->conds + AP_MAX_FQUEUES);
+        set->lock    = (pthread_mutex_t *)
+                (set->fqueues + AP_MAX_FQUEUES * SHM_BUFFER_SIZE);
+
+        pthread_mutexattr_init(&mattr);
+#ifndef __APPLE__
+        pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST);
+#endif
+        pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
+        pthread_mutex_init(set->lock, &mattr);
+
+        pthread_condattr_init(&cattr);
+        pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
+#ifndef __APPLE__
+        pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
+#endif
+        for (i = 0; i < AP_MAX_FQUEUES; ++i) {
+                set->heads[i] = 0;
+                pthread_cond_init(&set->conds[i], &cattr);
+        }
+
+        for (i = 0; i < IRMD_MAX_FLOWS; ++i)
+                set->mtable[i] = -1;
+
+        set->api = getpid();
+
+        return set;
+}
+
+struct shm_flow_set * shm_flow_set_open(pid_t api)
+{
+        struct shm_flow_set * set;
+        ssize_t *             shm_base;
+        char                  fn[FN_MAX_CHARS];
+        int                   shm_fd;
+
+        sprintf(fn, SHM_FLOW_SET_PREFIX "%d", api);
+
+        set = malloc(sizeof(*set));
+        if (set == NULL) {
+                LOG_DBG("Could not allocate struct.");
+                return NULL;
+        }
+
+        shm_fd = shm_open(fn, O_RDWR, 0666);
+        if (shm_fd == -1) {
+                LOG_DBG("%d failed opening shared memory %s.", getpid(), fn);
+                free(set);
+                return NULL;
+        }
+
+        shm_base = mmap(NULL,
+                        SHM_FLOW_SET_FILE_SIZE,
+                        PROT_READ | PROT_WRITE,
+                        MAP_SHARED,
+                        shm_fd,
+                        0);
+
+        close(shm_fd);
+
+        if (shm_base == MAP_FAILED) {
+                LOG_DBG("Failed to map shared memory.");
+                if (shm_unlink(fn) == -1)
+                        LOG_DBG("Failed to remove invalid shm.");
+                free(set);
+                return NULL;
+        }
+
+        set->mtable  = shm_base;
+        set->heads   = (size_t *) (set->mtable + IRMD_MAX_FLOWS);
+        set->conds   = (pthread_cond_t *)(set->heads + AP_MAX_FQUEUES);
+        set->fqueues = (int *) (set->conds + AP_MAX_FQUEUES);
+        set->lock    = (pthread_mutex_t *)
+                (set->fqueues + AP_MAX_FQUEUES * SHM_BUFFER_SIZE);
+
+        set->api = api;
+
+        return set;
+}
+
+void shm_flow_set_destroy(struct shm_flow_set * set)
+{
+        char fn[25];
+        struct lockfile * lf = NULL;
+
+        assert(set);
+
+        if (set->api != getpid()) {
+                lf = lockfile_open();
+                if (lf == NULL) {
+                        LOG_ERR("Failed to open lockfile.");
+                        return;
+                }
+
+                if (lockfile_owner(lf) == getpid()) {
+                        LOG_DBG("Flow set %d destroyed by IRMd %d.",
+                                set->api, getpid());
+                        lockfile_close(lf);
+                } else {
+                        LOG_ERR("AP-I %d tried to destroy flowset owned by %d.",
+                                getpid(), set->api);
+                        lockfile_close(lf);
+                        return;
+                }
+        }
+
+        sprintf(fn, SHM_FLOW_SET_PREFIX "%d", set->api);
+
+        if (munmap(set->mtable, SHM_FLOW_SET_FILE_SIZE) == -1)
+                LOG_DBG("Couldn't unmap shared memory.");
+
+        if (shm_unlink(fn) == -1)
+                LOG_DBG("Failed to unlink shm.");
+
+        free(set);
+}
+
+void shm_flow_set_close(struct shm_flow_set * set)
+{
+        assert(set);
+
+        if (munmap(set->mtable, SHM_FLOW_SET_FILE_SIZE) == -1)
+                LOG_DBG("Couldn't unmap shared memory.");
+
+        free(set);
+}
+
+void shm_flow_set_zero(struct shm_flow_set * shm_set,
+                       ssize_t               idx)
+{
+        ssize_t i = 0;
+
+        assert(!(idx < 0) && idx < AP_MAX_FQUEUES);
+
+        pthread_mutex_lock(shm_set->lock);
+
+        for (i = 0; i < IRMD_MAX_FLOWS; ++i)
+                if (shm_set->mtable[i] == idx)
+                        shm_set->mtable[i] = -1;
+
+        shm_set->heads[idx] = 0;
+
+        pthread_mutex_unlock(shm_set->lock);
+}
+
+
+int shm_flow_set_add(struct shm_flow_set * shm_set,
+                     ssize_t               idx,
+                     int                   port_id)
+{
+        assert(shm_set);
+        assert(!(port_id < 0) && port_id < IRMD_MAX_FLOWS);
+        assert(!(idx < 0) && idx < AP_MAX_FQUEUES);
+
+        pthread_mutex_lock(shm_set->lock);
+
+        if (shm_set->mtable[port_id] != -1) {
+                pthread_mutex_unlock(shm_set->lock);
+                return -EPERM;
+        }
+
+        shm_set->mtable[port_id] = idx;
+
+        pthread_mutex_unlock(shm_set->lock);
+
+        return 0;
+}
+
+void shm_flow_set_del(struct shm_flow_set * shm_set,
+                      ssize_t               idx,
+                      int                   port_id)
+{
+        assert(shm_set);
+        assert(!(port_id < 0) && port_id < IRMD_MAX_FLOWS);
+        assert(!(idx < 0) && idx < AP_MAX_FQUEUES);
+
+        pthread_mutex_lock(shm_set->lock);
+
+        if (shm_set->mtable[port_id] == idx)
+                shm_set->mtable[port_id] = -1;
+
+        pthread_mutex_unlock(shm_set->lock);
+}
+
+int shm_flow_set_has(struct shm_flow_set * shm_set,
+                     ssize_t               idx,
+                     int                   port_id)
+{
+        int ret = 0;
+
+        assert(shm_set);
+        assert(!(port_id < 0) && port_id < IRMD_MAX_FLOWS);
+        assert(!(idx < 0) && idx < AP_MAX_FQUEUES);
+
+        pthread_mutex_lock(shm_set->lock);
+
+        if (shm_set->mtable[port_id] == idx)
+                ret = 1;
+
+        pthread_mutex_unlock(shm_set->lock);
+
+        return ret;
+}
+
+void shm_flow_set_notify(struct shm_flow_set * shm_set, int port_id)
+{
+        assert(shm_set);
+        assert(!(port_id < 0) && port_id < IRMD_MAX_FLOWS);
+
+        pthread_mutex_lock(shm_set->lock);
+
+        if (shm_set->mtable[port_id] == -1) {
+                pthread_mutex_unlock(shm_set->lock);
+                return;
+        }
+
+        *(fqueue_ptr(shm_set, shm_set->mtable[port_id]) +
+                     (shm_set->heads[shm_set->mtable[port_id]])++) = port_id;
+
+        pthread_cond_signal(&shm_set->conds[shm_set->mtable[port_id]]);
+
+        pthread_mutex_unlock(shm_set->lock);
+}
+
+
+int shm_flow_set_wait(const struct shm_flow_set * shm_set,
+                      ssize_t                     idx,
+                      int *                       fqueue,
+                      const struct timespec *     timeout)
+{
+        int ret = 0;
+        struct timespec abstime;
+
+        assert(shm_set);
+        assert(!(idx < 0) && idx < AP_MAX_FQUEUES);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(shm_set->lock);
+#else
+        if (pthread_mutex_lock(shm_set->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(shm_set->lock);
+        }
+#endif
+        if (timeout != NULL) {
+                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
+                ts_add(&abstime, timeout, &abstime);
+        }
+
+        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
+                             (void *) shm_set->lock);
+
+        while (shm_set->heads[idx] == 0 && ret != -ETIMEDOUT) {
+                if (timeout != NULL)
+                        ret = pthread_cond_timedwait(shm_set->conds + idx,
+                                                     shm_set->lock,
+                                                     &abstime);
+                else
+                        ret = pthread_cond_wait(shm_set->conds + idx,
+                                                shm_set->lock);
+#ifndef __APPLE__
+                if (ret == EOWNERDEAD) {
+                        LOG_DBG("Recovering dead mutex.");
+                        pthread_mutex_consistent(shm_set->lock);
+                }
+#endif
+                if (ret == ETIMEDOUT) {
+                        ret = -ETIMEDOUT;
+                        break;
+                }
+        }
+
+        if (ret != -ETIMEDOUT) {
+                memcpy(fqueue,
+                       fqueue_ptr(shm_set, idx),
+                       shm_set->heads[idx] * sizeof(int));
+                ret = shm_set->heads[idx];
+                shm_set->heads[idx] = 0;
+        }
+
+        pthread_cleanup_pop(true);
+
+        return ret;
+}
diff --git a/src/lib/shm_rbuff.c b/src/lib/shm_rbuff.c
new file mode 100644
index 00000000..a933fbff
--- /dev/null
+++ b/src/lib/shm_rbuff.c
@@ -0,0 +1,405 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Ring buffer for incoming SDUs
+ *
+ *    Dimitri Staessens <dimitri.staessens@intec.ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <ouroboros/config.h>
+#include <ouroboros/shm_rbuff.h>
+#include <ouroboros/lockfile.h>
+#include <ouroboros/time_utils.h>
+#include <ouroboros/errno.h>
+
+#define OUROBOROS_PREFIX "shm_rbuff"
+
+#include <ouroboros/logs.h>
+
+#include <pthread.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <assert.h>
+#include <stdbool.h>
+
+#define FN_MAX_CHARS 255
+
+#define SHM_RBUFF_FILE_SIZE (SHM_BUFFER_SIZE * sizeof(ssize_t)          \
+                             + 2 * sizeof(size_t) + sizeof(int8_t)      \
+                             + sizeof(pthread_mutex_t)                  \
+                             + 2 * sizeof (pthread_cond_t))
+
+#define shm_rbuff_used(rb) ((*rb->head + SHM_BUFFER_SIZE - *rb->tail)   \
+                            & (SHM_BUFFER_SIZE - 1))
+#define shm_rbuff_free(rb) (shm_rbuff_used(rb) + 1 < SHM_BUFFER_SIZE)
+#define shm_rbuff_empty(rb) (*rb->head == *rb->tail)
+#define head_el_ptr(rb) (rb->shm_base + *rb->head)
+#define tail_el_ptr(rb) (rb->shm_base + *rb->tail)
+
+struct shm_rbuff {
+        ssize_t *         shm_base; /* start of entry                */
+        size_t *          head;     /* start of ringbuffer head      */
+        size_t *          tail;     /* start of ringbuffer tail      */
+        int8_t *          acl;      /* access control                */
+        pthread_mutex_t * lock;     /* lock all free space in shm    */
+        pthread_cond_t *  add;      /* SDU arrived                   */
+        pthread_cond_t *  del;      /* SDU removed                   */
+        pid_t             api;      /* api of the owner              */
+        int               port_id;  /* port_id of the flow           */
+};
+
+struct shm_rbuff * shm_rbuff_create(pid_t api, int port_id)
+{
+        struct shm_rbuff *  rb;
+        int                 shm_fd;
+        ssize_t *           shm_base;
+        pthread_mutexattr_t mattr;
+        pthread_condattr_t  cattr;
+        char                fn[FN_MAX_CHARS];
+        mode_t              mask;
+
+        sprintf(fn, SHM_RBUFF_PREFIX "%d.%d", api, port_id);
+
+        rb = malloc(sizeof(*rb));
+        if (rb == NULL) {
+                LOG_DBG("Could not allocate struct.");
+                return NULL;
+        }
+
+        mask = umask(0);
+
+        shm_fd = shm_open(fn, O_CREAT | O_EXCL | O_RDWR, 0666);
+        if (shm_fd == -1) {
+                LOG_DBG("Failed creating ring buffer.");
+                free(rb);
+                return NULL;
+        }
+
+        umask(mask);
+
+        if (ftruncate(shm_fd, SHM_RBUFF_FILE_SIZE - 1) < 0) {
+                LOG_DBG("Failed to extend ringbuffer.");
+                free(rb);
+                close(shm_fd);
+                return NULL;
+        }
+
+        shm_base = mmap(NULL,
+                        SHM_RBUFF_FILE_SIZE,
+                        PROT_READ | PROT_WRITE,
+                        MAP_SHARED,
+                        shm_fd,
+                        0);
+
+        close(shm_fd);
+
+        if (shm_base == MAP_FAILED) {
+                LOG_DBG("Failed to map shared memory.");
+                if (shm_unlink(fn) == -1)
+                        LOG_DBG("Failed to remove invalid shm.");
+                free(rb);
+                return NULL;
+        }
+
+        rb->shm_base = shm_base;
+        rb->head     = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
+        rb->tail     = rb->head + 1;
+        rb->acl      = (int8_t *) (rb->tail + 1);
+        rb->lock     = (pthread_mutex_t *) (rb->acl + 1);
+        rb->add      = (pthread_cond_t *) (rb->lock + 1);
+        rb->del      = rb->add + 1;
+
+        pthread_mutexattr_init(&mattr);
+#ifndef __APPLE__
+        pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST);
+#endif
+        pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
+        pthread_mutex_init(rb->lock, &mattr);
+
+        pthread_condattr_init(&cattr);
+        pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
+#ifndef __APPLE__
+        pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
+#endif
+        pthread_cond_init(rb->add, &cattr);
+        pthread_cond_init(rb->del, &cattr);
+
+        *rb->acl = 0;
+        *rb->head = 0;
+        *rb->tail = 0;
+
+        rb->api = api;
+        rb->port_id = port_id;
+
+        if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
+                LOG_DBG("Couldn't unmap shared memory.");
+
+        return rb;
+}
+
+struct shm_rbuff * shm_rbuff_open(pid_t api, int port_id)
+{
+        struct shm_rbuff * rb;
+        int                shm_fd;
+        ssize_t *          shm_base;
+        char               fn[FN_MAX_CHARS];
+
+        sprintf(fn, SHM_RBUFF_PREFIX "%d.%d", api, port_id);
+
+        rb = malloc(sizeof(*rb));
+        if (rb == NULL) {
+                LOG_DBG("Could not allocate struct.");
+                return NULL;
+        }
+
+        shm_fd = shm_open(fn, O_RDWR, 0666);
+        if (shm_fd == -1) {
+                LOG_DBG("%d failed opening shared memory %s.", getpid(), fn);
+                free(rb);
+                return NULL;
+        }
+
+        shm_base = mmap(NULL,
+                        SHM_RBUFF_FILE_SIZE,
+                        PROT_READ | PROT_WRITE,
+                        MAP_SHARED,
+                        shm_fd,
+                        0);
+
+        close(shm_fd);
+
+        if (shm_base == MAP_FAILED) {
+                LOG_DBG("Failed to map shared memory.");
+                if (shm_unlink(fn) == -1)
+                        LOG_DBG("Failed to remove invalid shm.");
+
+                free(rb);
+                return NULL;
+        }
+
+        rb->shm_base = shm_base;
+        rb->head     = (size_t *) (rb->shm_base + SHM_BUFFER_SIZE);
+        rb->tail     = rb->head + 1;
+        rb->acl      = (int8_t *) (rb->tail + 1);
+        rb->lock     = (pthread_mutex_t *) (rb->acl + 1);
+        rb->add      = (pthread_cond_t *) (rb->lock + 1);
+        rb->del      = rb->add + 1;
+
+        rb->api = api;
+        rb->port_id = port_id;
+
+        return rb;
+}
+
+void shm_rbuff_close(struct shm_rbuff * rb)
+{
+        assert(rb);
+
+        if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
+                LOG_DBG("Couldn't unmap shared memory.");
+
+        free(rb);
+}
+
+void shm_rbuff_destroy(struct shm_rbuff * rb)
+{
+        char fn[25];
+
+        if (rb == NULL)
+                return;
+
+        sprintf(fn, SHM_RBUFF_PREFIX "%d.%d", rb->api, rb->port_id);
+
+        if (shm_unlink(fn) == -1)
+                LOG_DBG("Failed to unlink shm %s.", fn);
+
+        free(rb);
+}
+
+int shm_rbuff_write(struct shm_rbuff * rb, ssize_t idx)
+{
+        assert(rb);
+        assert(idx >= 0);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+        if (*rb->acl) {
+                pthread_mutex_unlock(rb->lock);
+                return -ENOTALLOC;
+        }
+
+        if (!shm_rbuff_free(rb)) {
+                pthread_mutex_unlock(rb->lock);
+                return -1;
+        }
+
+        if (shm_rbuff_empty(rb))
+                pthread_cond_broadcast(rb->add);
+
+        *head_el_ptr(rb) = idx;
+        *rb->head = (*rb->head + 1) & (SHM_BUFFER_SIZE -1);
+
+        pthread_mutex_unlock(rb->lock);
+
+        return 0;
+}
+
+ssize_t shm_rbuff_read(struct shm_rbuff * rb)
+{
+        int ret = 0;
+
+        assert(rb);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+        if (shm_rbuff_empty(rb)) {
+                pthread_mutex_unlock(rb->lock);
+                return -1;
+        }
+
+        ret = *tail_el_ptr(rb);
+        *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
+
+        pthread_mutex_unlock(rb->lock);
+
+        return ret;
+}
+
+ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
+                         const struct timespec * timeout)
+{
+        struct timespec abstime;
+        int ret = 0;
+        ssize_t idx = -1;
+
+        assert(rb);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+        if (timeout != NULL) {
+                idx = -ETIMEDOUT;
+                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
+                ts_add(&abstime, timeout, &abstime);
+        }
+
+        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
+                             (void *) rb->lock);
+
+        while (shm_rbuff_empty(rb) && (ret != ETIMEDOUT)) {
+                if (timeout != NULL)
+                        ret = pthread_cond_timedwait(rb->add,
+                                                     rb->lock,
+                                                     &abstime);
+                else
+                        ret = pthread_cond_wait(rb->add, rb->lock);
+#ifndef __APPLE__
+                if (ret == EOWNERDEAD) {
+                        LOG_DBG("Recovering dead mutex.");
+                        pthread_mutex_consistent(rb->lock);
+                }
+#endif
+                if (ret == ETIMEDOUT) {
+                        idx = -ETIMEDOUT;
+                        break;
+                }
+        }
+
+        if (idx != -ETIMEDOUT) {
+                idx = *tail_el_ptr(rb);
+                *rb->tail = (*rb->tail + 1) & (SHM_BUFFER_SIZE -1);
+                pthread_cond_broadcast(rb->del);
+        }
+
+        pthread_cleanup_pop(true);
+
+        return idx;
+}
+
+int shm_rbuff_block(struct shm_rbuff * rb)
+{
+        int ret = 0;
+
+        assert(rb);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+        *rb->acl = -1;
+
+        if (!shm_rbuff_empty(rb))
+                ret = -EBUSY;
+
+        pthread_mutex_unlock(rb->lock);
+
+        return ret;
+}
+
+void shm_rbuff_unblock(struct shm_rbuff * rb)
+{
+        assert(rb);
+
+#ifdef __APPLE__
+        pthread_mutex_lock(rb->lock);
+#else
+        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD) {
+                LOG_DBG("Recovering dead mutex.");
+                pthread_mutex_consistent(rb->lock);
+        }
+#endif
+        *rb->acl = 0; /* open */
+
+        pthread_mutex_unlock(rb->lock);
+}
+
+void shm_rbuff_reset(struct shm_rbuff * rb)
+{
+        assert(rb);
+
+        pthread_mutex_lock(rb->lock);
+        *rb->tail = 0;
+        *rb->head = 0;
+        pthread_mutex_unlock(rb->lock);
+}
diff --git a/src/lib/shm_rdrbuff.c b/src/lib/shm_rdrbuff.c
index f6683dc2..e5a37577 100644
--- a/src/lib/shm_rdrbuff.c
+++ b/src/lib/shm_rdrbuff.c
@@ -90,7 +90,6 @@ struct shm_rdrbuff {
         pthread_cond_t *  full;        /* run sanitizer when buffer full */
         pid_t *           api;         /* api of the irmd owner */
         enum qos_cube     qos;         /* qos id which this buffer serves */
-        int               fd;
 };
 
 static void garbage_collect(struct shm_rdrbuff * rdrb)
@@ -189,17 +188,11 @@ struct shm_rdrbuff * shm_rdrbuff_create()
         if (ftruncate(shm_fd, SHM_FILE_SIZE - 1) < 0) {
                 LOG_DBGF("Failed to extend shared memory map.");
                 free(shm_rdrb_fn);
+                close(shm_fd);
                 free(rdrb);
                 return NULL;
         }
-#ifndef __APPLE
-        if (write(shm_fd, "", 1) != 1) {
-                LOG_DBGF("Failed to finalise extension of shared memory map.");
-                free(shm_rdrb_fn);
-                free(rdrb);
-                return NULL;
-        }
-#endif
+
         shm_base = mmap(NULL,
                         SHM_FILE_SIZE,
                         PROT_READ | PROT_WRITE,
@@ -207,6 +200,8 @@ struct shm_rdrbuff * shm_rdrbuff_create()
                         shm_fd,
                         0);
 
+        close(shm_fd);
+
         if (shm_base == MAP_FAILED) {
                 LOG_DBGF("Failed to map shared memory.");
                 if (shm_unlink(shm_rdrb_fn) == -1)
@@ -235,6 +230,9 @@ struct shm_rdrbuff * shm_rdrbuff_create()
 
         pthread_condattr_init(&cattr);
         pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
+#ifndef __APPLE__
+        pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
+#endif
         pthread_cond_init(rdrb->full, &cattr);
         pthread_cond_init(rdrb->healthy, &cattr);
 
@@ -246,7 +244,6 @@ struct shm_rdrbuff * shm_rdrbuff_create()
         *rdrb->api = getpid();
 
         rdrb->qos = qos;
-        rdrb->fd  = shm_fd;
 
         free(shm_rdrb_fn);
 
@@ -287,10 +284,11 @@ struct shm_rdrbuff * shm_rdrbuff_open()
                         MAP_SHARED,
                         shm_fd,
                         0);
+
+        close(shm_fd);
+
         if (shm_base == MAP_FAILED) {
                 LOG_DBGF("Failed to map shared memory.");
-                if (close(shm_fd) == -1)
-                        LOG_DBG("Failed to close invalid shm.");
                 if (shm_unlink(shm_rdrb_fn) == -1)
                         LOG_DBG("Failed to unlink invalid shm.");
                 free(shm_rdrb_fn);
@@ -309,7 +307,6 @@ struct shm_rdrbuff * shm_rdrbuff_open()
         rdrb->api = (pid_t *) (rdrb->full + 1);
 
         rdrb->qos = qos;
-        rdrb->fd = shm_fd;
 
         free(shm_rdrb_fn);
 
@@ -400,9 +397,6 @@ void shm_rdrbuff_close(struct shm_rdrbuff * rdrb)
 {
         assert(rdrb);
 
-        if (close(rdrb->fd) < 0)
-                LOG_DBGF("Couldn't close shared memory.");
-
         if (munmap(rdrb->shm_base, SHM_FILE_SIZE) == -1)
                 LOG_DBGF("Couldn't unmap shared memory.");
 
@@ -420,9 +414,6 @@ void shm_rdrbuff_destroy(struct shm_rdrbuff * rdrb)
                 return;
         }
 
-        if (close(rdrb->fd) < 0)
-                LOG_DBG("Couldn't close shared memory.");
-
         if (munmap(rdrb->shm_base, SHM_FILE_SIZE) == -1)
                 LOG_DBG("Couldn't unmap shared memory.");
 
diff --git a/src/tools/oping/oping.c b/src/tools/oping/oping.c
index 7d41b497..0ca40326 100644
--- a/src/tools/oping/oping.c
+++ b/src/tools/oping/oping.c
@@ -23,7 +23,7 @@
 
 #define _POSIX_C_SOURCE 199506L
 
-#include <ouroboros/select.h>
+#include <ouroboros/fqueue.h>
 #include <ouroboros/dev.h>
 
 #include <stdio.h>
@@ -53,6 +53,8 @@ struct c {
         float  rtt_avg;
         float  rtt_m2;
 
+        flow_set_t * flows;
+
         /* needs locking */
         struct timespec * times;
         pthread_mutex_t lock;
diff --git a/src/tools/oping/oping_client.c b/src/tools/oping/oping_client.c
index 4742d0de..40f75785 100644
--- a/src/tools/oping/oping_client.c
+++ b/src/tools/oping/oping_client.c
@@ -55,20 +55,21 @@ void * reader(void * o)
         struct timespec timeout = {2, 0};
         struct timespec now = {0, 0};
 
-        struct oping_msg * msg;
         char buf[OPING_BUF_SIZE];
+        struct oping_msg * msg = (struct oping_msg *) buf;
         int fd = 0;
         int msg_len = 0;
         float ms = 0;
         float d = 0;
-
-        msg = (struct oping_msg *) buf;
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
 
         /* FIXME: use flow timeout option once we have it */
-        while(client.rcvd != client.count &&
-              (fd = flow_select(NULL, &timeout)) != -ETIMEDOUT) {
-                flow_cntl(fd, FLOW_F_SETFL, FLOW_O_NONBLOCK);
-                while (!((msg_len = flow_read(fd, buf, OPING_BUF_SIZE)) < 0)) {
+        while (client.rcvd != client.count
+               && flow_event_wait(client.flows, fq, &timeout) != -ETIMEDOUT) {
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        msg_len = flow_read(fd, buf, OPING_BUF_SIZE);
                         if (msg_len < 0)
                                 continue;
 
@@ -165,12 +166,20 @@ int client_main()
         struct timespec tic;
         struct timespec toc;
 
-        int fd = flow_alloc(client.s_apn, NULL, NULL);
+        int fd;
+
+        client.flows = flow_set_create();
+        if (client.flows == NULL)
+                return 0;
+
+        fd = flow_alloc(client.s_apn, NULL, NULL);
         if (fd < 0) {
                 printf("Failed to allocate flow.\n");
                 return -1;
         }
 
+        flow_set_add(client.flows, fd);
+
         if (flow_alloc_res(fd)) {
                 printf("Flow allocation refused.\n");
                 flow_dealloc(fd);
diff --git a/src/tools/oping/oping_server.c b/src/tools/oping/oping_server.c
index 845f0cbd..8a5a3512 100644
--- a/src/tools/oping/oping_server.c
+++ b/src/tools/oping/oping_server.c
@@ -69,16 +69,23 @@ void * server_thread(void *o)
         struct oping_msg * msg = (struct oping_msg *) buf;
         struct timespec now = {0, 0};
         struct timespec timeout = {0, 100 * MILLION};
+        int fd;
+        fqueue_t * fq = fqueue_create();
+        if (fq == NULL)
+                return (void *) 1;
 
         while (true) {
-                int fd = flow_select(server.flows, &timeout);
-                if (fd == -ETIMEDOUT)
-                        continue;
-                if (fd < 0) {
-                        printf("Failed to get active fd.\n");
+                int ret = flow_event_wait(server.flows, fq, &timeout);
+                if (ret == -ETIMEDOUT)
                         continue;
+
+                if (ret < 0) {
+                        printf("Event error.\n");
+                        break;
                 }
-                while (!((msg_len = flow_read(fd, buf, OPING_BUF_SIZE)) < 0)) {
+
+                while ((fd = fqueue_next(fq)) >= 0) {
+                        msg_len = flow_read(fd, buf, OPING_BUF_SIZE);
                         if (msg_len < 0)
                                 continue;
 
@@ -160,8 +167,6 @@ int server_main()
         if (server.flows == NULL)
                 return 0;
 
-        flow_set_zero(server.flows);
-
         pthread_create(&server.cleaner_pt, NULL, cleaner_thread, NULL);
         pthread_create(&server.accept_pt, NULL, accept_thread, NULL);
         pthread_create(&server.server_pt, NULL, server_thread, NULL);