Merged in sandervrijders/ouroboros/be-frct (pull request #555)

lib: Add basic FRCT mechanisms

10 files changed, 988 insertions, 112 deletions

diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index 550bbc08..728d975a 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -86,6 +86,7 @@ set(SOURCE_FILES
   cdap_req.c
   crc32.c
   dev.c
+  frct_pci.c
   hash.c
   hashtable.c
   irm.c
@@ -104,6 +105,7 @@ set(SOURCE_FILES
   shm_rdrbuff.c
   sockets.c
   time_utils.c
+  timerwheel.c
   tpm.c
   utils.c
   )
diff --git a/src/lib/dev.c b/src/lib/dev.c
index 9354855b..e81bf105 100644
--- a/src/lib/dev.c
+++ b/src/lib/dev.c
@@ -34,6 +34,8 @@
 #include <ouroboros/utils.h>
 #include <ouroboros/fqueue.h>
 #include <ouroboros/qoscube.h>
+#include <ouroboros/timerwheel.h>
+#include <ouroboros/frct_pci.h>
 
 #include <stdlib.h>
 #include <string.h>
@@ -41,8 +43,14 @@
 
 #define BUF_SIZE 1500
 
+#define TW_ELEMENTS   6000
+#define TW_RESOLUTION 1   /* ms */
+
+#define MPL 2000 /* ms */
+
 struct flow_set {
         size_t idx;
+        bool   np1_set;
 };
 
 struct fqueue {
@@ -59,6 +67,26 @@ enum port_state {
         PORT_DESTROY
 };
 
+struct frcti {
+        bool          used;
+
+        struct tw_f * snd_inact;
+        bool          snd_drf;
+        uint64_t      snd_lwe;
+        uint64_t      snd_rwe;
+
+        struct tw_f * rcv_inact;
+        bool          rcv_drf;
+        uint64_t      rcv_lwe;
+        uint64_t      rcv_rwe;
+
+        bool          resource_control;
+        bool          reliable;
+        bool          error_check;
+        bool          ordered;
+        bool          partial;
+};
+
 struct port {
         int             fd;
 
@@ -89,10 +117,14 @@ struct {
         struct shm_rdrbuff *  rdrb;
         struct shm_flow_set * fqset;
 
+        struct timerwheel *   tw;
+        int                   tw_users;
+
         struct bmp *          fds;
         struct bmp *          fqueues;
         struct flow *         flows;
         struct port *         ports;
+        struct frcti *        frcti;
 
         pthread_rwlock_t      lock;
 } ai;
@@ -203,6 +235,242 @@ static int api_announce(char * ap_name)
         return ret;
 }
 
+/* Call under flows lock */
+static int finalize_write(int    fd,
+                          size_t idx)
+{
+        if (shm_rbuff_write(ai.flows[fd].tx_rb, idx) < 0)
+                return -ENOTALLOC;
+
+        shm_flow_set_notify(ai.flows[fd].set, ai.flows[fd].port_id);
+
+        return 0;
+}
+
+static int frcti_init(int fd)
+{
+        ai.frcti[fd].used = true;
+
+        ai.frcti[fd].snd_drf = true;
+        ai.frcti[fd].snd_lwe = 0;
+        ai.frcti[fd].snd_rwe = 0;
+
+        ai.frcti[fd].rcv_drf = true;
+        ai.frcti[fd].rcv_lwe = 0;
+        ai.frcti[fd].rcv_rwe = 0;
+
+        return 0;
+}
+
+static void frcti_fini(int fd)
+{
+        struct frcti * frcti;
+
+        frcti = &(ai.frcti[fd]);
+
+        frcti->used = false;
+
+        /* FIXME: We actually need to wait until these timers become NULL. */
+        if (frcti->snd_inact != NULL)
+                timerwheel_stop(ai.tw, frcti->snd_inact);
+
+        if (frcti->rcv_inact != NULL)
+                timerwheel_stop(ai.tw, frcti->rcv_inact);
+}
+
+static int frcti_configure(int         fd,
+                           qosspec_t * qos)
+{
+        /* FIXME: Send configuration message here to other side. */
+
+        (void) fd;
+        (void) qos;
+
+        return 0;
+}
+
+static void frcti_snd_inactivity(void * arg)
+{
+        struct frcti *  frcti;
+
+        pthread_rwlock_wrlock(&ai.lock);
+
+        frcti = (struct frcti * ) arg;
+
+        frcti->snd_drf = true;
+        frcti->snd_inact = NULL;
+
+        pthread_rwlock_unlock(&ai.lock);
+}
+
+/* Called under flows lock */
+static int frcti_write(int                  fd,
+                       struct shm_du_buff * sdb)
+{
+        struct frcti *  frcti;
+        struct frct_pci pci;
+
+        memset(&pci, 0, sizeof(pci));
+
+        frcti = &(ai.frcti[fd]);
+
+        /*
+         * Set the DRF in the first packet of a new run of SDUs,
+         * otherwise simply recharge the timer.
+         */
+        if (frcti->snd_drf) {
+                frcti->snd_inact = timerwheel_start(ai.tw, frcti_snd_inactivity,
+                                                    frcti, 2 * MPL);
+                if (frcti->snd_inact == NULL)
+                        return -1;
+
+                pci.flags |= FLAG_DATA_RUN;
+                frcti->snd_drf = false;
+        } else {
+                if (timerwheel_restart(ai.tw, frcti->snd_inact, 2 * MPL))
+                        return -1;
+        }
+
+        pci.seqno = frcti->snd_lwe++;
+        pci.type |= PDU_TYPE_DATA;
+
+        if (frct_pci_ser(sdb, &pci, frcti->error_check))
+                return -1;
+
+        if (finalize_write(fd, shm_du_buff_get_idx(sdb)))
+                return -ENOTALLOC;
+
+        return 0;
+}
+
+static void frcti_rcv_inactivity(void * arg)
+{
+        struct frcti *  frcti;
+
+        pthread_rwlock_wrlock(&ai.lock);
+
+        frcti = (struct frcti * ) arg;
+
+        frcti->rcv_drf = true;
+        frcti->rcv_inact = NULL;
+
+        pthread_rwlock_unlock(&ai.lock);
+}
+
+static ssize_t frcti_read(int fd)
+{
+        ssize_t              idx = -1;
+        struct timespec      abstime;
+        struct frcti *       frcti;
+        struct frct_pci      pci;
+        struct shm_du_buff * sdb;
+
+        pthread_rwlock_rdlock(&ai.lock);
+
+        if (ai.flows[fd].oflags & FLOW_O_NONBLOCK) {
+                idx = shm_rbuff_read(ai.flows[fd].rx_rb);
+                pthread_rwlock_unlock(&ai.lock);
+        } else {
+                struct shm_rbuff * rb   = ai.flows[fd].rx_rb;
+                bool timeo = ai.flows[fd].timesout;
+                struct timespec timeout = ai.flows[fd].rcv_timeo;
+
+                pthread_rwlock_unlock(&ai.lock);
+
+                if (timeo) {
+                        clock_gettime(PTHREAD_COND_CLOCK, &abstime);
+                        ts_add(&abstime, &timeout, &abstime);
+                        idx = shm_rbuff_read_b(rb, &abstime);
+                } else {
+                        idx = shm_rbuff_read_b(rb, NULL);
+                }
+        }
+
+        if (idx < 0)
+                return idx;
+
+        pthread_rwlock_rdlock(&ai.lock);
+
+        frcti = &(ai.frcti[fd]);
+
+        sdb = shm_rdrbuff_get(ai.rdrb, idx);
+
+        /* SDU may be corrupted. */
+        if (frct_pci_des(sdb, &pci, frcti->error_check)) {
+                pthread_rwlock_unlock(&ai.lock);
+                shm_rdrbuff_remove(ai.rdrb, idx);
+                return -1;
+        }
+
+        /* We don't accept packets when there is no inactivity timer. */
+        if (frcti->rcv_drf && !(pci.flags & FLAG_DATA_RUN)) {
+                pthread_rwlock_unlock(&ai.lock);
+                shm_rdrbuff_remove(ai.rdrb, idx);
+                return -1;
+        }
+
+        /*
+         * If there is an inactivity timer and the DRF is set,
+         * reset the state of the connection.
+         */
+        if (pci.flags & FLAG_DATA_RUN) {
+                frcti->rcv_drf = true;
+                if (frcti->rcv_inact != NULL)
+                        timerwheel_stop(ai.tw, frcti->rcv_inact);
+                frcti->rcv_lwe = pci.seqno;
+        }
+
+        /*
+         * Start receiver inactivity if this packet has the DRF,
+         * otherwise simply restart it.
+         */
+        if (frcti->rcv_drf) {
+                frcti->rcv_inact = timerwheel_start(ai.tw, frcti_rcv_inactivity,
+                                                    frcti, 3 * MPL);
+                if (frcti->rcv_inact == NULL) {
+                        pthread_rwlock_unlock(&ai.lock);
+                        shm_rdrbuff_remove(ai.rdrb, idx);
+                        return -1;
+                }
+
+                frcti->rcv_drf = false;
+        } else {
+                if (timerwheel_restart(ai.tw, frcti->rcv_inact, 3 * MPL)) {
+                        pthread_rwlock_unlock(&ai.lock);
+                        shm_rdrbuff_remove(ai.rdrb, idx);
+                        return -1;
+                }
+        }
+
+        pthread_rwlock_unlock(&ai.lock);
+
+        return idx;
+}
+
+static int frcti_event_wait(struct flow_set *       set,
+                            struct fqueue *         fq,
+                            const struct timespec * timeout)
+{
+        int ret;
+
+        assert(set);
+        assert(fq);
+        assert(timeout);
+
+        /*
+         * FIXME: Return the fq only if a data SDU
+         * for the application is available.
+         */
+
+        ret = shm_flow_set_wait(ai.fqset, set->idx, fq->fqueue, timeout);
+        if (ret == -ETIMEDOUT) {
+                fq->fqsize = 0;
+                return -ETIMEDOUT;
+        }
+
+        return ret;
+}
+
 static void flow_clear(int fd)
 {
         assert(!(fd < 0));
@@ -230,6 +498,9 @@ static void flow_fini(int fd)
         if (ai.flows[fd].set != NULL)
                 shm_flow_set_close(ai.flows[fd].set);
 
+        if (ai.frcti[fd].used)
+                frcti_fini(fd);
+
         flow_clear(fd);
 }
 
@@ -316,8 +587,14 @@ int ouroboros_init(const char * ap_name)
         if (ai.flows == NULL)
                 goto fail_flows;
 
-        for (i = 0; i < AP_MAX_FLOWS; ++i)
+        ai.frcti = malloc(sizeof(*ai.frcti) * AP_MAX_FLOWS);
+        if (ai.frcti == NULL)
+                goto fail_frcti;
+
+        for (i = 0; i < AP_MAX_FLOWS; ++i) {
                 flow_clear(i);
+                frcti_fini(i);
+        }
 
         ai.ports = malloc(sizeof(*ai.ports) * IRMD_MAX_FLOWS);
         if (ai.ports == NULL)
@@ -353,8 +630,15 @@ int ouroboros_init(const char * ap_name)
         if (pthread_rwlock_init(&ai.lock, NULL))
                 goto fail_lock;
 
+        ai.tw = timerwheel_create(TW_RESOLUTION,
+                                  TW_RESOLUTION * TW_ELEMENTS);
+        if (ai.tw == NULL)
+                goto fail_timerwheel;
+
         return 0;
 
+ fail_timerwheel:
+        pthread_rwlock_destroy(&ai.lock);
  fail_lock:
         for (i = 0; i < IRMD_MAX_FLOWS; ++i)
                 pthread_cond_destroy(&ai.ports[i].state_cond);
@@ -366,11 +650,13 @@ int ouroboros_init(const char * ap_name)
  fail_ap_name:
         free(ai.ports);
  fail_ports:
+        free(ai.frcti);
+ fail_frcti:
         free(ai.flows);
  fail_flows:
         shm_rdrbuff_close(ai.rdrb);
  fail_rdrb:
-      shm_flow_set_destroy(ai.fqset);
+        shm_flow_set_destroy(ai.fqset);
  fail_fqset:
         bmp_destroy(ai.fqueues);
  fail_fqueues:
@@ -409,6 +695,9 @@ void ouroboros_fini()
 
         shm_rdrbuff_close(ai.rdrb);
 
+        if (ai.tw != NULL)
+                timerwheel_destroy(ai.tw);
+
         free(ai.flows);
         free(ai.ports);
 
@@ -463,9 +752,15 @@ int flow_accept(qosspec_t *             qs,
         if (fd < 0)
                 return fd;
 
+        pthread_rwlock_wrlock(&ai.lock);
+
+        frcti_init(fd);
+
         if (qs != NULL)
                 *qs = ai.flows[fd].spec;
 
+        pthread_rwlock_unlock(&ai.lock);
+
         return fd;
 }
 
@@ -505,7 +800,7 @@ int flow_alloc(const char *            dst_name,
                 return -EIRMD;
         }
 
-        if (recv_msg->result !=  0) {
+        if (recv_msg->result != 0) {
                 int res =  recv_msg->result;
                 irm_msg__free_unpacked(recv_msg, NULL);
                 return res;
@@ -520,6 +815,22 @@ int flow_alloc(const char *            dst_name,
 
         irm_msg__free_unpacked(recv_msg, NULL);
 
+        if (fd < 0)
+                return fd;
+
+        pthread_rwlock_wrlock(&ai.lock);
+
+        frcti_init(fd);
+
+        if (frcti_configure(fd, qs)) {
+                flow_fini(fd);
+                bmp_release(ai.fds, fd);
+                pthread_rwlock_unlock(&ai.lock);
+                return -1;
+        }
+
+        pthread_rwlock_unlock(&ai.lock);
+
         return fd;
 }
 
@@ -720,34 +1031,31 @@ ssize_t flow_write(int          fd,
                         return idx;
                 }
 
-                if (shm_rbuff_write(ai.flows[fd].tx_rb, idx) < 0) {
-                        shm_rdrbuff_remove(ai.rdrb, idx);
-                        pthread_rwlock_unlock(&ai.lock);
-                        return -ENOTALLOC;
-                }
         } else { /* blocking */
-                struct shm_rdrbuff * rdrb = ai.rdrb;
-                struct shm_rbuff * tx_rb  = ai.flows[fd].tx_rb;
-
                 pthread_rwlock_unlock(&ai.lock);
 
-                assert(tx_rb);
-
-                idx = shm_rdrbuff_write_b(rdrb,
+                idx = shm_rdrbuff_write_b(ai.rdrb,
                                           DU_BUFF_HEADSPACE,
                                           DU_BUFF_TAILSPACE,
                                           buf,
                                           count);
 
-                if (shm_rbuff_write(tx_rb, idx) < 0) {
-                        shm_rdrbuff_remove(rdrb, idx);
-                        return -ENOTALLOC;
-                }
-
                 pthread_rwlock_rdlock(&ai.lock);
         }
 
-        shm_flow_set_notify(ai.flows[fd].set, ai.flows[fd].port_id);
+        if (!ai.frcti[fd].used) {
+                if (finalize_write(fd, idx)) {
+                        pthread_rwlock_unlock(&ai.lock);
+                        shm_rdrbuff_remove(ai.rdrb, idx);
+                        return -ENOTALLOC;
+                }
+        } else {
+                if (frcti_write(fd, shm_rdrbuff_get(ai.rdrb, idx))) {
+                        pthread_rwlock_unlock(&ai.lock);
+                        shm_rdrbuff_remove(ai.rdrb, idx);
+                        return -1;
+                }
+        }
 
         pthread_rwlock_unlock(&ai.lock);
 
@@ -772,21 +1080,12 @@ ssize_t flow_read(int    fd,
                 return -ENOTALLOC;
         }
 
-        if (ai.flows[fd].oflags & FLOW_O_NONBLOCK) {
-                idx = shm_rbuff_read(ai.flows[fd].rx_rb);
-                pthread_rwlock_unlock(&ai.lock);
-        } else {
-                struct shm_rbuff * rb   = ai.flows[fd].rx_rb;
-                bool timeo = ai.flows[fd].timesout;
-                struct timespec timeout = ai.flows[fd].rcv_timeo;
-
-                pthread_rwlock_unlock(&ai.lock);
+        pthread_rwlock_unlock(&ai.lock);
 
-                if (timeo)
-                        idx = shm_rbuff_read_b(rb, &timeout);
-                else
-                        idx = shm_rbuff_read_b(rb, NULL);
-        }
+        if (!ai.frcti[fd].used)
+                idx = shm_rbuff_read(ai.flows[fd].rx_rb);
+        else
+                idx = frcti_read(fd);
 
         if (idx < 0) {
                 assert(idx == -EAGAIN || idx == -ETIMEDOUT);
@@ -823,6 +1122,8 @@ struct flow_set * flow_set_create()
                 return NULL;
         }
 
+        set->np1_set = false;
+
         pthread_rwlock_unlock(&ai.lock);
 
         return set;
@@ -891,6 +1192,9 @@ int flow_set_add(struct flow_set * set,
         for (i = 0; i < sdus; i++)
                 shm_flow_set_notify(ai.fqset, ai.flows[fd].port_id);
 
+        if (ai.frcti[fd].used)
+                set->np1_set = true;
+
         pthread_rwlock_unlock(&ai.lock);
 
         return ret;
@@ -960,7 +1264,8 @@ int flow_event_wait(struct flow_set *       set,
                     struct fqueue *         fq,
                     const struct timespec * timeout)
 {
-        ssize_t ret;
+        ssize_t         ret;
+        struct timespec abstime;
 
         if (set == NULL || fq == NULL)
                 return -EINVAL;
@@ -970,7 +1275,17 @@ int flow_event_wait(struct flow_set *       set,
 
         assert(!fq->next);
 
-        ret = shm_flow_set_wait(ai.fqset, set->idx, fq->fqueue, timeout);
+        if (timeout != NULL) {
+                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
+                ts_add(&abstime, timeout, &abstime);
+        }
+
+        if (set->np1_set)
+                ret = frcti_event_wait(set, fq, &abstime);
+        else
+                ret = shm_flow_set_wait(ai.fqset, set->idx,
+                                        fq->fqueue, &abstime);
+
         if (ret == -ETIMEDOUT) {
                 fq->fqsize = 0;
                 return -ETIMEDOUT;
@@ -1132,9 +1447,8 @@ int ipcp_flow_read(int                   fd,
 {
         ssize_t idx = -1;
         int port_id = -1;
-        struct shm_rbuff * rb;
 
-        assert(fd >=0);
+        assert(fd >= 0);
         assert(sdb);
 
         pthread_rwlock_rdlock(&ai.lock);
@@ -1144,11 +1458,13 @@ int ipcp_flow_read(int                   fd,
                 return -ENOTALLOC;
         }
 
-        rb = ai.flows[fd].rx_rb;
-
         pthread_rwlock_unlock(&ai.lock);
 
-        idx = shm_rbuff_read(rb);
+        if (!ai.frcti[fd].used)
+                idx = shm_rbuff_read(ai.flows[fd].rx_rb);
+        else
+                idx = frcti_read(fd);
+
         if (idx < 0)
                 return idx;
 
@@ -1160,8 +1476,6 @@ int ipcp_flow_read(int                   fd,
 int ipcp_flow_write(int                  fd,
                     struct shm_du_buff * sdb)
 {
-        size_t idx;
-
         if (sdb == NULL)
                 return -EINVAL;
 
@@ -1179,10 +1493,17 @@ int ipcp_flow_write(int                  fd,
 
         assert(ai.flows[fd].tx_rb);
 
-        idx = shm_du_buff_get_idx(sdb);
-
-        shm_rbuff_write(ai.flows[fd].tx_rb, idx);
-        shm_flow_set_notify(ai.flows[fd].set, ai.flows[fd].port_id);
+        if (!ai.frcti[fd].used) {
+                if (finalize_write(fd, shm_du_buff_get_idx(sdb))) {
+                        pthread_rwlock_unlock(&ai.lock);
+                        return -ENOTALLOC;
+                }
+        } else {
+                if (frcti_write(fd, sdb)) {
+                        pthread_rwlock_unlock(&ai.lock);
+                        return -1;
+                }
+        }
 
         pthread_rwlock_unlock(&ai.lock);
 
@@ -1274,32 +1595,11 @@ int local_flow_write(int    fd,
                 return -ENOTALLOC;
         }
 
-        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.lock);
-
-        return 0;
-}
-
-int ipcp_read_shim(int                   fd,
-                   struct shm_du_buff ** sdb)
-{
-        ssize_t idx;
-
-        pthread_rwlock_rdlock(&ai.lock);
-
-        assert(ai.flows[fd].rx_rb);
-
-        idx = shm_rbuff_read(ai.flows[fd].rx_rb);
-        if (idx < 0) {
+        if (finalize_write(fd, idx)) {
                 pthread_rwlock_unlock(&ai.lock);
-                return -EAGAIN;
+                return -ENOTALLOC;
         }
 
-        *sdb = shm_rdrbuff_get(ai.rdrb, idx);
-
         pthread_rwlock_unlock(&ai.lock);
 
         return 0;
diff --git a/src/lib/frct_pci.c b/src/lib/frct_pci.c
new file mode 100644
index 00000000..92cf8cd9
--- /dev/null
+++ b/src/lib/frct_pci.c
@@ -0,0 +1,105 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2017
+ *
+ * Protocol Control Information of FRCT
+ *
+ *    Dimitri Staessens <dimitri.staessens@ugent.be>
+ *    Sander Vrijders   <sander.vrijders@ugent.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#include <ouroboros/config.h>
+#include <ouroboros/frct_pci.h>
+#include <ouroboros/hash.h>
+#include <ouroboros/errno.h>
+
+#include <assert.h>
+#include <string.h>
+
+#define TYPE_SIZE  1
+#define SEQNO_SIZE 8
+#define FLAGS_SIZE 1
+
+/* FIXME: Head size will differ on type */
+#define HEAD_SIZE TYPE_SIZE + FLAGS_SIZE + SEQNO_SIZE
+
+int frct_pci_ser(struct shm_du_buff * sdb,
+                 struct frct_pci *    pci,
+                 bool                 error_check)
+{
+        uint8_t * head;
+        uint8_t * tail;
+
+        assert(sdb);
+        assert(pci);
+
+        head = shm_du_buff_head_alloc(sdb, HEAD_SIZE);
+        if (head == NULL)
+                return -EPERM;
+
+        memcpy(head, &pci->type, TYPE_SIZE);
+        memcpy(head + TYPE_SIZE, &pci->flags, FLAGS_SIZE);
+        memcpy(head + TYPE_SIZE + FLAGS_SIZE, &pci->seqno, SEQNO_SIZE);
+
+        if (error_check) {
+                tail = shm_du_buff_tail_alloc(sdb, hash_len(HASH_CRC32));
+                if (tail == NULL) {
+                        shm_du_buff_head_release(sdb, HEAD_SIZE);
+                        return -EPERM;
+                }
+
+                *((uint32_t *) tail) = 0;
+                mem_hash(HASH_CRC32, (uint32_t *) tail, head, tail - head);
+        }
+
+        return 0;
+}
+
+int frct_pci_des(struct shm_du_buff * sdb,
+                 struct frct_pci *    pci,
+                 bool                 error_check)
+{
+        uint8_t * head;
+        uint8_t * tail;
+        uint32_t  crc;
+
+        assert(sdb);
+        assert(pci);
+
+        head = shm_du_buff_head(sdb);
+
+         /* FIXME: Depending on the type a different deserialization */
+        memcpy(&pci->type, head, TYPE_SIZE);
+        memcpy(&pci->flags, head + TYPE_SIZE, FLAGS_SIZE);
+        memcpy(&pci->seqno, head + TYPE_SIZE + FLAGS_SIZE, SEQNO_SIZE);
+
+        if (error_check) {
+                tail = shm_du_buff_tail(sdb);
+                if (tail == NULL)
+                        return -EPERM;
+
+                mem_hash(HASH_CRC32, &crc, head, tail - head);
+
+                /* Corrupted SDU */
+                if (crc != 0)
+                        return -1;
+
+                shm_du_buff_tail_release(sdb, hash_len(HASH_CRC32));
+        }
+
+        shm_du_buff_head_release(sdb, HEAD_SIZE);
+
+        return 0;
+}
diff --git a/src/lib/hash.c b/src/lib/hash.c
index d8cabfd3..e062a0ad 100644
--- a/src/lib/hash.c
+++ b/src/lib/hash.c
@@ -64,45 +64,46 @@ uint16_t hash_len(enum hash_algo algo)
 #endif
 }
 
-void str_hash(enum hash_algo algo,
-              void *         buf,
-              const char *   str)
+void mem_hash(enum hash_algo  algo,
+              void *          dst,
+              const uint8_t * buf,
+              size_t          len)
 {
 #ifdef HAVE_LIBGCRYPT
-        gcry_md_hash_buffer(algo, buf, str, strlen(str));
+        gcry_md_hash_buffer(algo, dst, buf, len);
 #else
         struct sha3_ctx sha3_ctx;
         struct md5_ctx md5_ctx;
 
         switch (algo) {
         case HASH_CRC32:
-                memset(buf, 0, CRC32_HASH_LEN);
-                crc32((uint32_t *) buf, str, strlen(str));
+                memset(dst, 0, CRC32_HASH_LEN);
+                crc32((uint32_t *) dst, buf, len);
                 break;
         case HASH_MD5:
                 rhash_md5_init(&md5_ctx);
-                rhash_md5_update(&md5_ctx, str, strlen(str));
-                rhash_md5_final(&md5_ctx, (uint8_t *) buf);
+                rhash_md5_update(&md5_ctx, buf, len);
+                rhash_md5_final(&md5_ctx, (uint8_t *) dst);
                 break;
         case HASH_SHA3_224:
                 rhash_sha3_224_init(&sha3_ctx);
-                rhash_sha3_update(&sha3_ctx, str, strlen(str));
-                rhash_sha3_final(&sha3_ctx, (uint8_t *) buf);
+                rhash_sha3_update(&sha3_ctx, buf, len);
+                rhash_sha3_final(&sha3_ctx, (uint8_t *) dst);
                 break;
         case HASH_SHA3_256:
                 rhash_sha3_256_init(&sha3_ctx);
-                rhash_sha3_update(&sha3_ctx, str, strlen(str));
-                rhash_sha3_final(&sha3_ctx, (uint8_t *) buf);
+                rhash_sha3_update(&sha3_ctx, buf, len);
+                rhash_sha3_final(&sha3_ctx, (uint8_t *) dst);
                 break;
         case HASH_SHA3_384:
                 rhash_sha3_384_init(&sha3_ctx);
-                rhash_sha3_update(&sha3_ctx, str, strlen(str));
-                rhash_sha3_final(&sha3_ctx, (uint8_t *) buf);
+                rhash_sha3_update(&sha3_ctx, buf, len);
+                rhash_sha3_final(&sha3_ctx, (uint8_t *) dst);
                 break;
         case HASH_SHA3_512:
                 rhash_sha3_512_init(&sha3_ctx);
-                rhash_sha3_update(&sha3_ctx, str, strlen(str));
-                rhash_sha3_final(&sha3_ctx, (uint8_t *) buf);
+                rhash_sha3_update(&sha3_ctx, buf, len);
+                rhash_sha3_final(&sha3_ctx, (uint8_t *) dst);
                 break;
         default:
                 assert(false);
@@ -110,3 +111,10 @@ void str_hash(enum hash_algo algo,
         }
 #endif
 }
+
+void str_hash(enum hash_algo algo,
+              void *         dst,
+              const char *   str)
+{
+        return mem_hash(algo, dst, (const uint8_t *) str, strlen(str));
+}
diff --git a/src/lib/shm_flow_set.c b/src/lib/shm_flow_set.c
index cd6946d4..2f1d4e33 100644
--- a/src/lib/shm_flow_set.c
+++ b/src/lib/shm_flow_set.c
@@ -326,10 +326,9 @@ void shm_flow_set_notify(struct shm_flow_set * set,
 ssize_t shm_flow_set_wait(const struct shm_flow_set * set,
                           size_t                      idx,
                           int *                       fqueue,
-                          const struct timespec *     timeout)
+                          const struct timespec *     abstime)
 {
         ssize_t ret = 0;
-        struct timespec abstime;
 
         assert(set);
         assert(idx < AP_MAX_FQUEUES);
@@ -341,19 +340,15 @@ ssize_t shm_flow_set_wait(const struct shm_flow_set * set,
         if (pthread_mutex_lock(set->lock) == EOWNERDEAD)
                 pthread_mutex_consistent(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 *) set->lock);
 
         while (set->heads[idx] == 0 && ret != -ETIMEDOUT) {
-                if (timeout != NULL)
+                if (abstime != NULL)
                         ret = -pthread_cond_timedwait(set->conds + idx,
                                                       set->lock,
-                                                      &abstime);
+                                                      abstime);
                 else
                         ret = -pthread_cond_wait(set->conds + idx,
                                                  set->lock);
diff --git a/src/lib/shm_rbuff_ll.c b/src/lib/shm_rbuff_ll.c
index 33e236b0..b420b785 100644
--- a/src/lib/shm_rbuff_ll.c
+++ b/src/lib/shm_rbuff_ll.c
@@ -281,9 +281,8 @@ ssize_t shm_rbuff_read(struct shm_rbuff * rb)
 }
 
 ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
-                         const struct timespec * timeout)
+                         const struct timespec * abstime)
 {
-        struct timespec abstime;
         ssize_t idx = -1;
 
         assert(rb);
@@ -293,11 +292,6 @@ ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
         if (idx != -EAGAIN)
                 return idx;
 
-        if (timeout != NULL) {
-                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
-                ts_add(&abstime, timeout, &abstime);
-        }
-
 #ifndef HAVE_ROBUST_MUTEX
         pthread_mutex_lock(rb->lock);
 #else
@@ -308,10 +302,10 @@ ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
                              (void *) rb->lock);
 
         while (shm_rbuff_empty(rb) && (idx != -ETIMEDOUT)) {
-                if (timeout != NULL)
+                if (abstime != NULL)
                         idx = -pthread_cond_timedwait(rb->add,
                                                       rb->lock,
-                                                      &abstime);
+                                                      abstime);
                 else
                         idx = -pthread_cond_wait(rb->add, rb->lock);
 #ifdef HAVE_ROBUST_MUTEX
diff --git a/src/lib/shm_rbuff_pthr.c b/src/lib/shm_rbuff_pthr.c
index 44001458..7dc5f5d9 100644
--- a/src/lib/shm_rbuff_pthr.c
+++ b/src/lib/shm_rbuff_pthr.c
@@ -284,18 +284,12 @@ ssize_t shm_rbuff_read(struct shm_rbuff * rb)
 }
 
 ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
-                         const struct timespec * timeout)
+                         const struct timespec * abstime)
 {
-        struct timespec abstime;
         ssize_t idx = -1;
 
         assert(rb);
 
-        if (timeout != NULL) {
-                clock_gettime(PTHREAD_COND_CLOCK, &abstime);
-                ts_add(&abstime, timeout, &abstime);
-        }
-
 #ifndef HAVE_ROBUST_MUTEX
         pthread_mutex_lock(rb->lock);
 #else
@@ -306,10 +300,10 @@ ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
                              (void *) rb->lock);
 
         while (shm_rbuff_empty(rb) && (idx != -ETIMEDOUT)) {
-                if (timeout != NULL)
+                if (abstime != NULL)
                         idx = -pthread_cond_timedwait(rb->add,
                                                       rb->lock,
-                                                      &abstime);
+                                                      abstime);
                 else
                         idx = -pthread_cond_wait(rb->add, rb->lock);
 #ifdef HAVE_ROBUST_MUTEX
diff --git a/src/lib/tests/CMakeLists.txt b/src/lib/tests/CMakeLists.txt
index 41c2074a..fd3c1c6a 100644
--- a/src/lib/tests/CMakeLists.txt
+++ b/src/lib/tests/CMakeLists.txt
@@ -11,6 +11,7 @@ create_test_sourcelist(${PARENT_DIR}_tests test_suite.c
   rib_test.c
   sha3_test.c
   time_utils_test.c
+  timerwheel_test.c
   )
 
 add_executable(${PARENT_DIR}_test EXCLUDE_FROM_ALL ${${PARENT_DIR}_tests})
diff --git a/src/lib/tests/timerwheel_test.c b/src/lib/tests/timerwheel_test.c
new file mode 100644
index 00000000..d9ca164e
--- /dev/null
+++ b/src/lib/tests/timerwheel_test.c
@@ -0,0 +1,106 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2017
+ *
+ * Test of the timer wheel
+ *
+ *    Dimitri Staessens <dimitri.staessens@ugent.be>
+ *    Sander Vrijders   <sander.vrijders@ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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., http://www.fsf.org/about/contact/.
+ */
+
+#include "timerwheel.c"
+
+#include <pthread.h>
+#include <time.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define MAX_ELEMENTS   100
+#define MAX_RESOLUTION 10  /* ms */
+#define MAX_ADDITIONS  1000
+
+int total;
+
+int add(void * o)
+{
+        total += *((int *) o);
+        return 0;
+}
+
+int timerwheel_test(int argc, char ** argv)
+{
+        struct timerwheel * tw;
+        long resolution;
+        long elements;
+        struct timespec wait;
+
+        int additions;
+
+        int check_total = 0;
+
+        int i;
+        int var = 5;
+
+        struct tw_f * f;
+
+        (void) argc;
+        (void) argv;
+
+        total = 0;
+
+        srand(time(NULL));
+
+        resolution = rand() % (MAX_RESOLUTION - 1) + 1;
+        elements = rand() % (MAX_ELEMENTS - 10) + 10;
+
+        tw = timerwheel_create(resolution, resolution * elements);
+        if (tw == NULL) {
+                printf("Failed to create timerwheel.\n");
+                return -1;
+        }
+
+        wait.tv_sec = (resolution * elements) / 1000;
+        wait.tv_nsec = ((resolution * elements) % 1000) * MILLION;
+
+        additions = rand() % MAX_ADDITIONS + 1000;
+
+        for (i = 0; i < additions; ++i) {
+                int delay = rand() % (resolution * elements);
+                check_total += var;
+                f = timerwheel_start(tw,
+                                     (void (*)(void *)) add,
+                                     (void *) &var,
+                                     delay);
+                if (f == NULL) {
+                        printf("Failed to add function.");
+                        return -1;
+                }
+        }
+
+        nanosleep(&wait, NULL);
+
+        /* On some systems and VMs, the scheduler may be too slow. */
+        if (total != check_total)
+                nanosleep(&wait, NULL);
+
+        timerwheel_destroy(tw);
+
+        if (total != check_total) {
+                printf("Totals do not match.\n");
+                return -1;
+        }
+
+        return 0;
+}
diff --git a/src/lib/timerwheel.c b/src/lib/timerwheel.c
new file mode 100644
index 00000000..7e2779d0
--- /dev/null
+++ b/src/lib/timerwheel.c
@@ -0,0 +1,371 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2017
+ *
+ * Timerwheel
+ *
+ *    Dimitri Staessens <dimitri.staessens@ugent.be>
+ *    Sander Vrijders   <sander.vrijders@ugent.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#include <ouroboros/config.h>
+#include <ouroboros/time_utils.h>
+#include <ouroboros/errno.h>
+#include <ouroboros/list.h>
+
+#include <pthread.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#define FRAC 10 /* accuracy of the timer */
+
+#define tw_used(tw) ((tw->head + tw->elements - tw->tail) & (tw->elements - 1));
+#define tw_free(tw) (tw_used(tw) + 1 < tw->elements)
+#define tw_empty(tw) (tw->head == tw->tail)
+
+enum tw_state {
+        TW_NULL = 0,
+        TW_RUNNING,
+        TW_DESTROY
+};
+
+struct tw_f {
+        struct list_head next;
+        void (* func)(void *);
+        void * arg;
+};
+
+struct tw_el {
+        struct list_head funcs;
+        struct timespec  expiry;
+};
+
+struct timerwheel {
+        struct tw_el *   wheel;
+
+        struct timespec  intv;
+
+        size_t           pos;
+
+        struct list_head wq;
+
+        pthread_cond_t   work;
+        pthread_mutex_t  lock;
+
+        int              resolution;
+        unsigned int     elements;
+
+        enum tw_state    state;
+        pthread_mutex_t  s_lock;
+
+        pthread_t        ticker;
+        pthread_t        worker;
+};
+
+static void tw_el_fini(struct tw_el * e)
+{
+        struct list_head * p;
+        struct list_head * h;
+
+        list_for_each_safe(p, h, &e->funcs) {
+                struct tw_f * f = list_entry(p, struct tw_f, next);
+                list_del(&f->next);
+        }
+}
+
+static enum tw_state tw_get_state(struct timerwheel * tw)
+{
+        enum tw_state state;
+
+        assert(tw);
+
+        pthread_mutex_lock(&tw->s_lock);
+
+        state = tw->state;
+
+        pthread_mutex_unlock(&tw->s_lock);
+
+        return state;
+}
+
+static void tw_set_state(struct timerwheel * tw, enum tw_state state)
+{
+        assert(tw);
+        assert(state != TW_NULL);
+
+        pthread_mutex_lock(&tw->s_lock);
+
+        tw->state = state;
+
+        pthread_mutex_unlock(&tw->s_lock);
+}
+
+static void * worker(void * o)
+{
+        struct list_head * p;
+        struct list_head * h;
+
+        struct timerwheel * tw = (struct timerwheel *) o;
+        struct timespec dl;
+        struct timespec now;
+
+        clock_gettime(PTHREAD_COND_CLOCK, &now);
+
+        ts_add(&now, &tw->intv, &dl);
+
+        pthread_mutex_lock(&tw->lock);
+
+        while (tw_get_state(tw) == TW_RUNNING) {
+                if (pthread_cond_timedwait(&tw->work, &tw->lock, &dl)
+                    == ETIMEDOUT)
+                        ts_add(&dl, &tw->intv, &dl);
+
+                list_for_each_safe(p, h, &tw->wq) {
+                        struct tw_f * f = list_entry(p, struct tw_f, next);
+                        list_del(&f->next);
+                        pthread_mutex_unlock(&tw->lock);
+                        f->func(f->arg);
+                        free(f);
+
+                        pthread_mutex_lock(&tw->lock);
+                }
+        }
+
+        pthread_mutex_unlock(&tw->lock);
+
+        return (void *) o;
+}
+
+static void * movement(void * o)
+{
+        struct timerwheel * tw = (struct timerwheel *) o;
+        struct timespec now = {0, 0};
+        long ms = tw->resolution * tw->elements;
+        struct timespec total = {ms / 1000,
+                                 (ms % 1000) * MILLION};
+        struct list_head * p;
+        struct list_head * h;
+
+        while (tw_get_state(tw) == TW_RUNNING) {
+                clock_gettime(CLOCK_MONOTONIC, &now);
+
+                pthread_mutex_lock(&tw->lock);
+
+                if (ts_diff_us(&tw->wheel[tw->pos].expiry, &now) < 0) {
+                        pthread_mutex_unlock(&tw->lock);
+                        nanosleep(&tw->intv, NULL);
+                        continue;
+                }
+
+                list_for_each_safe(p, h, &tw->wheel[tw->pos].funcs) {
+                        struct tw_f * f = list_entry(p, struct tw_f, next);
+                        list_del(&f->next);
+                        list_add(&f->next, &tw->wq);
+                }
+
+                ts_add(&tw->wheel[tw->pos].expiry,
+                       &total,
+                       &tw->wheel[tw->pos].expiry);
+
+                tw->pos = (tw->pos + 1) & (tw->elements - 1);
+
+                pthread_cond_signal(&tw->work);
+
+                pthread_mutex_unlock(&tw->lock);
+        }
+
+        return (void *) 0;
+}
+
+struct timerwheel * timerwheel_create(time_t resolution,
+                                      time_t max_delay)
+{
+        struct timespec now = {0, 0};
+        struct timespec res_ts = {resolution / 1000,
+                                  (resolution % 1000) * MILLION};
+        unsigned long i;
+
+        struct timerwheel * tw;
+
+        pthread_condattr_t cattr;
+
+        assert(resolution != 0);
+
+        tw = malloc(sizeof(*tw));
+        if (tw == NULL)
+                return NULL;
+
+        if (pthread_mutex_init(&tw->lock, NULL))
+                return NULL;
+
+        tw->elements = 1;
+
+        while (tw->elements < max_delay / resolution)
+                tw->elements <<= 1;
+
+        tw->wheel = malloc(sizeof(*tw->wheel) * tw->elements);
+        if (tw->wheel == NULL)
+                goto fail_wheel_malloc;
+
+        tw->resolution = resolution;
+
+        tw->intv.tv_sec = (tw->resolution / FRAC) / 1000;
+        tw->intv.tv_nsec = ((tw->resolution / FRAC) % 1000) * MILLION;
+
+        list_head_init(&tw->wq);
+
+        if (pthread_mutex_init(&tw->lock, NULL))
+                goto fail_lock_init;
+
+        if (pthread_mutex_init(&tw->s_lock, NULL))
+                goto fail_s_lock_init;
+
+        if (pthread_condattr_init(&cattr))
+                goto fail_cond_init;
+
+#ifndef __APPLE__
+        pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
+#endif
+        if (pthread_cond_init(&tw->work, &cattr))
+                goto fail_cond_init;
+
+        tw->pos = 0;
+        tw->state = TW_RUNNING;
+
+        clock_gettime(CLOCK_MONOTONIC, &now);
+        now.tv_nsec -= (now.tv_nsec % MILLION);
+
+        for (i = 0; i < tw->elements; ++i) {
+                list_head_init(&tw->wheel[i].funcs);
+                tw->wheel[i].expiry = now;
+                ts_add(&now, &res_ts, &now);
+        }
+
+        if (pthread_create(&tw->worker, NULL, worker, (void *) tw))
+                goto fail_worker_create;
+
+        if (pthread_create(&tw->ticker, NULL, movement, (void *) tw)) {
+                tw_set_state(tw, TW_DESTROY);
+                goto fail_ticker_create;
+        }
+
+        return tw;
+
+ fail_ticker_create:
+         pthread_join(tw->worker, NULL);
+ fail_worker_create:
+         pthread_cond_destroy(&tw->work);
+ fail_cond_init:
+         pthread_mutex_destroy(&tw->s_lock);
+ fail_s_lock_init:
+         pthread_mutex_destroy(&tw->lock);
+ fail_lock_init:
+         free(tw->wheel);
+ fail_wheel_malloc:
+         free(tw);
+         return NULL;
+}
+
+void timerwheel_destroy(struct timerwheel * tw)
+{
+        unsigned long i;
+
+        struct list_head * p;
+        struct list_head * h;
+
+        tw_set_state(tw, TW_DESTROY);
+
+        pthread_join(tw->ticker, NULL);
+        pthread_join(tw->worker, NULL);
+
+        for (i = 0; i < tw->elements; ++i)
+                tw_el_fini(&tw->wheel[i]);
+
+        pthread_mutex_lock(&tw->lock);
+
+        list_for_each_safe(p, h, &tw->wq) {
+                struct tw_f * f = list_entry(p, struct tw_f, next);
+                list_del(&f->next);
+                free(f);
+        }
+
+        pthread_mutex_unlock(&tw->lock);
+
+        pthread_cond_destroy(&tw->work);
+        pthread_mutex_destroy(&tw->lock);
+        pthread_mutex_destroy(&tw->s_lock);
+
+        free(tw->wheel);
+        free(tw);
+}
+
+struct tw_f * timerwheel_start(struct timerwheel * tw,
+                               void (* func)(void *),
+                               void *              arg,
+                               time_t              delay)
+{
+        int pos;
+        struct tw_f * f = malloc(sizeof(*f));
+        if (f == NULL)
+                return NULL;
+
+        f->func = func;
+        f->arg = arg;
+
+        assert(delay < tw->elements * tw->resolution);
+
+        pthread_mutex_lock(&tw->lock);
+
+        pos = (tw->pos + delay / tw->resolution) & (tw->elements - 1);
+        list_add(&f->next, &tw->wheel[pos].funcs);
+
+        pthread_mutex_unlock(&tw->lock);
+
+        return f;
+}
+
+int timerwheel_restart(struct timerwheel * tw,
+                       struct tw_f *       f,
+                       time_t              delay)
+{
+        int pos;
+
+        assert(tw);
+        assert(delay < tw->elements * tw->resolution);
+
+        pthread_mutex_lock(&tw->lock);
+
+        list_del(&f->next);
+        pos = (tw->pos + delay / tw->resolution) & (tw->elements - 1);
+        list_add(&f->next, &tw->wheel[pos].funcs);
+
+        pthread_mutex_unlock(&tw->lock);
+
+        return 0;
+}
+
+void timerwheel_stop(struct timerwheel * tw,
+                     struct tw_f *       f)
+{
+        assert(tw);
+
+        pthread_mutex_lock(&tw->lock);
+
+        list_del(&f->next);
+        free(f);
+
+        pthread_mutex_unlock(&tw->lock);
+}