lib, ipcpd: piggyback ECDHE on flow allocation

The initial implementation for the ECDHE key exchange was doing the
key exchange after a flow was established. The public keys are now
sent allowg on the flow allocation messages, so that an encrypted
tunnel can be created within 1 RTT. The flow allocation steps had to
be extended to pass the opaque data ('piggybacking').

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

8 files changed, 199 insertions, 100 deletions

diff --git a/src/ipcpd/broadcast/main.c b/src/ipcpd/broadcast/main.c
index 05338ee4..120b2bf1 100644
--- a/src/ipcpd/broadcast/main.c
+++ b/src/ipcpd/broadcast/main.c
@@ -235,7 +235,7 @@ static int broadcast_ipcp_join(int             fd,
 
         notifier_event(NOTIFY_DT_CONN_ADD, &conn);
 
-        ipcp_flow_alloc_reply(fd, 0);
+        ipcp_flow_alloc_reply(fd, 0, NULL, 0);
 
         return 0;
 }
diff --git a/src/ipcpd/eth/eth.c b/src/ipcpd/eth/eth.c
index 0c9daff4..6b17912b 100644
--- a/src/ipcpd/eth/eth.c
+++ b/src/ipcpd/eth/eth.c
@@ -138,7 +138,7 @@
 #define ALLOC_TIMEO          10    /* ms */
 #define NAME_QUERY_TIMEO     2000  /* ms */
 #define MGMT_TIMEO           100   /* ms */
-#define MGMT_FRAME_SIZE      512
+#define MGMT_FRAME_SIZE      2048
 
 #define FLOW_REQ             0
 #define FLOW_REPLY           1
@@ -201,6 +201,7 @@ struct mgmt_frame {
         struct list_head next;
         uint8_t          r_addr[MAC_SIZE];
         uint8_t          buf[MGMT_FRAME_SIZE];
+        size_t           len;
 };
 
 struct {
@@ -458,7 +459,9 @@ static int eth_ipcp_alloc(const uint8_t * dst_addr,
                           uint8_t         ssap,
 #endif
                           const uint8_t * hash,
-                          qosspec_t       qs)
+                          qosspec_t       qs,
+                          const void *    data,
+                          size_t          dlen)
 {
         uint8_t *         buf;
         struct mgmt_msg * msg;
@@ -467,7 +470,7 @@ static int eth_ipcp_alloc(const uint8_t * dst_addr,
 
         len = sizeof(*msg) + ipcp_dir_hash_len();
 
-        buf = malloc(len + ETH_HEADER_TOT_SIZE);
+        buf = malloc(len + ETH_HEADER_TOT_SIZE + dlen);
         if (buf == NULL)
                 return -1;
 
@@ -489,6 +492,7 @@ static int eth_ipcp_alloc(const uint8_t * dst_addr,
         msg->cypher_s     = hton16(qs.cypher_s);
 
         memcpy(msg + 1, hash, ipcp_dir_hash_len());
+        memcpy(buf + len + ETH_HEADER_TOT_SIZE, data, dlen);
 
         ret = eth_ipcp_send_frame(dst_addr,
 #if defined(BUILD_ETH_DIX)
@@ -497,26 +501,28 @@ static int eth_ipcp_alloc(const uint8_t * dst_addr,
                                   reverse_bits(MGMT_SAP),
                                   reverse_bits(MGMT_SAP),
 #endif
-                                  buf, len);
+                                  buf, len + dlen);
         free(buf);
 
         return ret;
 }
 
-static int eth_ipcp_alloc_resp(uint8_t * dst_addr,
+static int eth_ipcp_alloc_resp(uint8_t *    dst_addr,
 #if defined(BUILD_ETH_DIX)
-                               uint16_t  seid,
-                               uint16_t  deid,
+                               uint16_t     seid,
+                               uint16_t     deid,
 #elif defined(BUILD_ETH_LLC)
-                               uint8_t   ssap,
-                               uint8_t   dsap,
+                               uint8_t      ssap,
+                               uint8_t      dsap,
 #endif
-                               int       response)
+                               int          response,
+                               const void * data,
+                               size_t       len)
 {
         struct mgmt_msg * msg;
         uint8_t *         buf;
 
-        buf = malloc(sizeof(*msg) + ETH_HEADER_TOT_SIZE);
+        buf = malloc(sizeof(*msg) + ETH_HEADER_TOT_SIZE + len);
         if (buf == NULL)
                 return -1;
 
@@ -532,6 +538,8 @@ static int eth_ipcp_alloc_resp(uint8_t * dst_addr,
 #endif
         msg->response = response;
 
+        memcpy(msg + 1, data, len);
+
         if (eth_ipcp_send_frame(dst_addr,
 #if defined(BUILD_ETH_DIX)
                                 MGMT_EID,
@@ -539,7 +547,7 @@ static int eth_ipcp_alloc_resp(uint8_t * dst_addr,
                                 reverse_bits(MGMT_SAP),
                                 reverse_bits(MGMT_SAP),
 #endif
-                                buf, sizeof(*msg))) {
+                                buf, sizeof(*msg) + len)) {
                 free(buf);
                 return -1;
         }
@@ -556,7 +564,9 @@ static int eth_ipcp_req(uint8_t *       r_addr,
                         uint8_t         r_sap,
 #endif
                         const uint8_t * dst,
-                        qosspec_t       qs)
+                        qosspec_t       qs,
+                        const void *    data,
+                        size_t          len)
 {
         struct timespec ts = {0, ALLOC_TIMEO * MILLION};
         struct timespec abstime;
@@ -580,7 +590,7 @@ static int eth_ipcp_req(uint8_t *       r_addr,
         }
 
         /* reply to IRM, called under lock to prevent race */
-        fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs);
+        fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, data, len);
         if (fd < 0) {
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                 log_err("Could not get new flow from IRMd.");
@@ -607,19 +617,20 @@ static int eth_ipcp_req(uint8_t *       r_addr,
 #elif defined(BUILD_ETH_LLC)
         log_dbg("New flow request, fd %d, remote SAP %d.", fd, r_sap);
 #endif
-
         return 0;
 }
 
-static int eth_ipcp_alloc_reply(uint8_t * r_addr,
+static int eth_ipcp_alloc_reply(uint8_t *    r_addr,
 #if defined(BUILD_ETH_DIX)
-                                uint16_t  seid,
-                                uint16_t  deid,
+                                uint16_t     seid,
+                                uint16_t     deid,
 #elif defined(BUILD_ETH_LLC)
-                                uint8_t   ssap,
-                                int       dsap,
+                                uint8_t      ssap,
+                                int          dsap,
 #endif
-                                int       response)
+                                int          response,
+                                const void * data,
+                                size_t       len)
 {
         int ret = 0;
         int fd = -1;
@@ -657,7 +668,7 @@ static int eth_ipcp_alloc_reply(uint8_t * r_addr,
 #elif defined(BUILD_ETH_LLC)
         log_dbg("Flow reply, fd %d, SSAP %d, DSAP %d.", fd, ssap, dsap);
 #endif
-        if ((ret = ipcp_flow_alloc_reply(fd, response)) < 0)
+        if ((ret = ipcp_flow_alloc_reply(fd, response, data, len)) < 0)
                 return -1;
 
         return ret;
@@ -717,15 +728,21 @@ static int eth_ipcp_name_query_reply(const uint8_t * hash,
 }
 
 static int eth_ipcp_mgmt_frame(const uint8_t * buf,
+                               size_t          len,
                                uint8_t *       r_addr)
 {
         struct mgmt_msg * msg;
+        size_t            msg_len;
         qosspec_t         qs;
 
         msg = (struct mgmt_msg *) buf;
 
         switch (msg->code) {
         case FLOW_REQ:
+                msg_len = sizeof(*msg) + ipcp_dir_hash_len();
+
+                assert(len >= msg_len);
+
                 qs.delay = ntoh32(msg->delay);
                 qs.bandwidth = ntoh64(msg->bandwidth);
                 qs.availability = msg->availability;
@@ -744,10 +761,14 @@ static int eth_ipcp_mgmt_frame(const uint8_t * buf,
                                      msg->ssap,
 #endif
                                      buf + sizeof(*msg),
-                                     qs);
+                                     qs,
+                                     buf + msg_len,
+                                     len - msg_len);
                 }
                 break;
         case FLOW_REPLY:
+                assert(len >= sizeof(*msg));
+
                 eth_ipcp_alloc_reply(r_addr,
 #if defined(BUILD_ETH_DIX)
                                      ntohs(msg->seid),
@@ -756,7 +777,9 @@ static int eth_ipcp_mgmt_frame(const uint8_t * buf,
                                      msg->ssap,
                                      msg->dsap,
 #endif
-                                     msg->response);
+                                     msg->response,
+                                     buf + sizeof(*msg),
+                                     len - sizeof(*msg));
                 break;
         case NAME_QUERY_REQ:
                 eth_ipcp_name_query_req(buf + sizeof(*msg), r_addr);
@@ -814,7 +837,7 @@ static void * eth_ipcp_mgmt_handler(void * o)
                 list_del(&frame->next);
                 pthread_mutex_unlock(&eth_data.mgmt_lock);
 
-                eth_ipcp_mgmt_frame(frame->buf, frame->r_addr);
+                eth_ipcp_mgmt_frame(frame->buf, frame->len, frame->r_addr);
                 free(frame);
         }
 
@@ -951,6 +974,7 @@ static void * eth_ipcp_packet_reader(void * o)
 
                         memcpy(frame->buf, &e_frame->payload, length);
                         memcpy(frame->r_addr, e_frame->src_hwaddr, MAC_SIZE);
+                        frame->len = length;
 
                         pthread_mutex_lock(&eth_data.mgmt_lock);
                         list_add(&frame->next, &eth_data.mgmt_frames);
@@ -1613,7 +1637,9 @@ static int eth_ipcp_query(const uint8_t * hash)
 
 static int eth_ipcp_flow_alloc(int             fd,
                                const uint8_t * hash,
-                               qosspec_t       qs)
+                               qosspec_t       qs,
+                               const void *    data,
+                               size_t          len)
 {
 #ifdef BUILD_ETH_LLC
         uint8_t  ssap = 0;
@@ -1652,7 +1678,10 @@ static int eth_ipcp_flow_alloc(int             fd,
 #elif defined(BUILD_ETH_LLC)
                            ssap,
 #endif
-                           hash, qs) < 0) {
+                           hash,
+                           qs,
+                           data,
+                           len) < 0) {
 #ifdef BUILD_ETH_LLC
                 pthread_rwlock_wrlock(&eth_data.flows_lock);
                 bmp_release(eth_data.saps, eth_data.fd_to_ef[fd].sap);
@@ -1672,8 +1701,10 @@ static int eth_ipcp_flow_alloc(int             fd,
         return 0;
 }
 
-static int eth_ipcp_flow_alloc_resp(int fd,
-                                    int response)
+static int eth_ipcp_flow_alloc_resp(int          fd,
+                                    int          response,
+                                    const void * data,
+                                    size_t       len)
 {
         struct timespec ts    = {0, ALLOC_TIMEO * MILLION};
         struct timespec abstime;
@@ -1730,7 +1761,9 @@ static int eth_ipcp_flow_alloc_resp(int fd,
 #elif defined(BUILD_ETH_LLC)
                                 ssap, r_sap,
 #endif
-                                response) < 0) {
+                                response,
+                                data,
+                                len) < 0) {
 #ifdef BUILD_ETH_LLC
                 pthread_rwlock_wrlock(&eth_data.flows_lock);
                 bmp_release(eth_data.saps, eth_data.fd_to_ef[fd].sap);
diff --git a/src/ipcpd/ipcp.c b/src/ipcpd/ipcp.c
index 8f9fcd7d..95d2f783 100644
--- a/src/ipcpd/ipcp.c
+++ b/src/ipcpd/ipcp.c
@@ -408,6 +408,8 @@ static void * mainloop(void * o)
                         }
 
                         assert(msg->hash.len == ipcp_dir_hash_len());
+                        assert(msg->pk.len > 0 ? msg->pk.data != NULL
+                                               : msg->pk.data == NULL);
 
                         if (ipcp_get_state() != IPCP_OPERATIONAL) {
                                 log_err("IPCP in wrong state.");
@@ -429,7 +431,9 @@ static void * mainloop(void * o)
                         ret_msg.result =
                                 ipcpi.ops->ipcp_flow_alloc(fd,
                                                            msg->hash.data,
-                                                           qs);
+                                                           qs,
+                                                           msg->pk.data,
+                                                           msg->pk.len);
                         break;
                 case IPCP_MSG_CODE__IPCP_FLOW_JOIN:
                         ret_msg.has_result = true;
@@ -488,9 +492,14 @@ static void * mainloop(void * o)
                                 }
                         }
 
+                        assert(msg->pk.len > 0 ? msg->pk.data != NULL
+                               : msg->pk.data == NULL);
+
                         ret_msg.result =
                                 ipcpi.ops->ipcp_flow_alloc_resp(fd,
-                                                                msg->response);
+                                                                msg->response,
+                                                                msg->pk.data,
+                                                                msg->pk.len);
                         break;
                 case IPCP_MSG_CODE__IPCP_FLOW_DEALLOC:
                         ret_msg.has_result = true;
@@ -568,7 +577,7 @@ static int parse_args(int    argc,
         if (!(argc == 4 || argc == 3))
                 return -1;
 
-        /* argument 1: pid of irmd */
+        /* argument 1: pid of irm */
         if (atoi(argv[1]) == 0)
                 return -1;
 
diff --git a/src/ipcpd/ipcp.h b/src/ipcpd/ipcp.h
index 6afac3ea..02c74f50 100644
--- a/src/ipcpd/ipcp.h
+++ b/src/ipcpd/ipcp.h
@@ -60,14 +60,18 @@ struct ipcp_ops {
 
         int   (* ipcp_flow_alloc)(int             fd,
                                   const uint8_t * dst,
-                                  qosspec_t       qs);
+                                  qosspec_t       qs,
+                                  const void *    data,
+                                  size_t          len);
 
         int   (* ipcp_flow_join)(int             fd,
                                  const uint8_t * dst,
                                  qosspec_t       qs);
 
-        int   (* ipcp_flow_alloc_resp)(int fd,
-                                       int response);
+        int   (* ipcp_flow_alloc_resp)(int          fd,
+                                       int          response,
+                                       const void * data,
+                                       size_t       len);
 
         int   (* ipcp_flow_dealloc)(int fd);
 };
diff --git a/src/ipcpd/local/main.c b/src/ipcpd/local/main.c
index 009a3fde..a2e20017 100644
--- a/src/ipcpd/local/main.c
+++ b/src/ipcpd/local/main.c
@@ -186,14 +186,15 @@ static int ipcp_local_query(const uint8_t * hash)
 
 static int ipcp_local_flow_alloc(int             fd,
                                  const uint8_t * dst,
-                                 qosspec_t       qs)
+                                 qosspec_t       qs,
+                                 const void *    data,
+                                 size_t          len)
 {
         struct timespec ts     = {0, ALLOC_TIMEOUT * MILLION};
         struct timespec abstime;
         int             out_fd = -1;
 
         log_dbg("Allocating flow to " HASH_FMT " on fd %d.", HASH_VAL(dst), fd);
-
         assert(dst);
 
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
@@ -215,7 +216,7 @@ static int ipcp_local_flow_alloc(int             fd,
 
         assert(ipcpi.alloc_id == -1);
 
-        out_fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs);
+        out_fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, data, len);
         if (out_fd < 0) {
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                 log_dbg("Flow allocation failed: %d", out_fd);
@@ -241,8 +242,10 @@ static int ipcp_local_flow_alloc(int             fd,
         return 0;
 }
 
-static int ipcp_local_flow_alloc_resp(int fd,
-                                      int response)
+static int ipcp_local_flow_alloc_resp(int          fd,
+                                      int          response,
+                                      const void * data,
+                                      size_t       len)
 {
         struct timespec ts     = {0, ALLOC_TIMEOUT * MILLION};
         struct timespec abstime;
@@ -290,7 +293,7 @@ static int ipcp_local_flow_alloc_resp(int fd,
 
         fset_add(local_data.flows, fd);
 
-        if ((ret = ipcp_flow_alloc_reply(out_fd, response)) < 0)
+        if ((ret = ipcp_flow_alloc_reply(out_fd, response, data, len)) < 0)
                 return -1;
 
         log_info("Flow allocation completed, fds (%d, %d).", out_fd, fd);
diff --git a/src/ipcpd/udp/main.c b/src/ipcpd/udp/main.c
index 1f0bebf0..04c21a8b 100644
--- a/src/ipcpd/udp/main.c
+++ b/src/ipcpd/udp/main.c
@@ -62,8 +62,8 @@
 #define IPCP_UDP_MAX_PACKET_SIZE 8980
 #define OUR_HEADER_LEN           sizeof(uint32_t) /* adds eid */
 
-#define IPCP_UDP_BUF_SIZE        256
-#define IPCP_UDP_MSG_SIZE        256
+#define IPCP_UDP_BUF_SIZE        8980
+#define IPCP_UDP_MSG_SIZE        8980
 #define DNS_TTL                  86400
 #define FD_UPDATE_TIMEOUT        100 /* microseconds */
 
@@ -74,7 +74,8 @@
 #define LOCAL_IP                 (udp_data.s_saddr.sin_addr.s_addr)
 
 #define MGMT_EID                 0
-#define MGMT_FRAME_SIZE          512
+#define MGMT_FRAME_SIZE          (sizeof(struct mgmt_msg))
+#define MGMT_FRAME_BUF_SIZE      2048
 
 /* Keep order for alignment. */
 struct mgmt_msg {
@@ -97,7 +98,8 @@ struct mgmt_msg {
 struct mgmt_frame {
         struct list_head   next;
         struct sockaddr_in r_saddr;
-        uint8_t            buf[MGMT_FRAME_SIZE];
+        uint8_t            buf[MGMT_FRAME_BUF_SIZE];
+        size_t             len;
 };
 
 /* UDP flow */
@@ -186,15 +188,19 @@ static void udp_data_fini(void)
 static int ipcp_udp_port_alloc(int             skfd,
                                uint32_t        s_eid,
                                const uint8_t * dst,
-                               qosspec_t       qs)
+                               qosspec_t       qs,
+                               const void *    data,
+                               size_t          dlen)
 {
         uint8_t *         buf;
         struct mgmt_msg * msg;
         size_t            len;
 
+        assert(dlen > 0 ? data != NULL : data == NULL);
+
         len = sizeof(*msg) + ipcp_dir_hash_len();
 
-        buf = malloc(len);
+        buf = malloc(len + dlen);
         if (buf == NULL)
                 return -1;
 
@@ -212,8 +218,9 @@ static int ipcp_udp_port_alloc(int             skfd,
         msg->cypher_s     = hton16(qs.cypher_s);
 
         memcpy(msg + 1, dst, ipcp_dir_hash_len());
+        memcpy(buf + len, data, dlen);
 
-        if (write(skfd, msg, len) < 0) {
+        if (write(skfd, msg, len + dlen) < 0) {
                 free(buf);
                 return -1;
         }
@@ -223,14 +230,16 @@ static int ipcp_udp_port_alloc(int             skfd,
         return 0;
 }
 
-static int ipcp_udp_port_alloc_resp(int      skfd,
-                                    uint32_t s_eid,
-                                    uint32_t d_eid,
-                                    int8_t   response)
+static int ipcp_udp_port_alloc_resp(int          skfd,
+                                    uint32_t     s_eid,
+                                    uint32_t     d_eid,
+                                    int8_t       response,
+                                    const void * data,
+                                    size_t       len)
 {
         struct mgmt_msg *  msg;
 
-        msg = malloc(sizeof(*msg));
+        msg = malloc(sizeof(*msg) + len);
         if (msg == NULL)
                 return -1;
 
@@ -240,7 +249,9 @@ static int ipcp_udp_port_alloc_resp(int      skfd,
         msg->d_eid    = hton32(d_eid);
         msg->response = response;
 
-        if (write(skfd, msg, sizeof(*msg)) < 0) {
+        memcpy(msg + 1, data, len);
+
+        if (write(skfd, msg, sizeof(*msg) + len) < 0) {
                 free(msg);
                 return -1;
         }
@@ -253,7 +264,9 @@ static int ipcp_udp_port_alloc_resp(int      skfd,
 static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
                              int                  d_eid,
                              const uint8_t *      dst,
-                             qosspec_t            qs)
+                             qosspec_t            qs,
+                             const void *         data,
+                             size_t               len)
 {
         struct timespec ts        = {0, FD_UPDATE_TIMEOUT * 1000};
         struct timespec abstime;
@@ -294,7 +307,7 @@ static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
         }
 
         /* reply to IRM */
-        fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs);
+        fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, data, len);
         if (fd < 0) {
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                 log_err("Could not get new flow from IRMd.");
@@ -320,9 +333,11 @@ static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
         return 0;
 }
 
-static int ipcp_udp_port_alloc_reply(uint32_t s_eid,
-                                     uint32_t d_eid,
-                                     int8_t   response)
+static int ipcp_udp_port_alloc_reply(uint32_t     s_eid,
+                                     uint32_t     d_eid,
+                                     int8_t       response,
+                                     const void * data,
+                                     size_t       len)
 {
         struct sockaddr_in t_saddr;
         socklen_t          t_saddr_len;
@@ -356,7 +371,7 @@ static int ipcp_udp_port_alloc_reply(uint32_t s_eid,
                 return -1;
         }
 
-        if (ipcp_flow_alloc_reply(s_eid, response) < 0) {
+        if (ipcp_flow_alloc_reply(s_eid, response, data, len) < 0) {
                 log_dbg("Failed to reply to flow allocation.");
                 return -1;
         }
@@ -368,15 +383,21 @@ static int ipcp_udp_port_alloc_reply(uint32_t s_eid,
 }
 
 static int ipcp_udp_mgmt_frame(const uint8_t *    buf,
+                               size_t             len,
                                struct sockaddr_in c_saddr)
 {
         struct mgmt_msg * msg;
+        size_t            msg_len;
         qosspec_t         qs;
 
         msg = (struct mgmt_msg *) buf;
 
         switch (msg->code) {
         case FLOW_REQ:
+                msg_len = sizeof(*msg) + ipcp_dir_hash_len();
+
+                assert(len >= msg_len);
+
                 qs.delay        = ntoh32(msg->delay);
                 qs.bandwidth    = ntoh64(msg->bandwidth);
                 qs.availability = msg->availability;
@@ -387,11 +408,17 @@ static int ipcp_udp_mgmt_frame(const uint8_t *    buf,
                 qs.cypher_s     = ntoh16(msg->cypher_s);
 
                 return ipcp_udp_port_req(&c_saddr, ntoh32(msg->s_eid),
-                                         (uint8_t *) (msg + 1), qs);
+                                         (uint8_t *) (msg + 1), qs,
+                                         buf + msg_len,
+                                         len - msg_len);
         case FLOW_REPLY:
+                assert(len >= sizeof(*msg));
+
                 return ipcp_udp_port_alloc_reply(ntoh32(msg->s_eid),
                                                  ntoh32(msg->d_eid),
-                                                 msg->response);
+                                                 msg->response,
+                                                 buf + sizeof(*msg),
+                                                 len - sizeof(*msg));
         default:
                 log_err("Unknown message received %d.", msg->code);
                 return -1;
@@ -421,7 +448,7 @@ static void * ipcp_udp_mgmt_handler(void * o)
 
                 pthread_mutex_unlock(&udp_data.mgmt_lock);
 
-                ipcp_udp_mgmt_frame(frame->buf, frame->r_saddr);
+                ipcp_udp_mgmt_frame(frame->buf, frame->len, frame->r_saddr);
 
                 free(frame);
         }
@@ -468,8 +495,8 @@ static void * ipcp_udp_packet_reader(void * o)
 
                 /* pass onto mgmt queue */
                 if (eid == MGMT_EID) {
-                        if (n > IPCP_UDP_MSG_SIZE) {
-                                log_warn("Dropped oversize management frame.");
+                        if ((size_t) n < MGMT_FRAME_SIZE) {
+                                log_warn("Dropped runt mgmt frame.");
                                 continue;
                         }
 
@@ -479,6 +506,7 @@ static void * ipcp_udp_packet_reader(void * o)
 
                         memcpy(frame->buf, buf, n);
                         memcpy(&frame->r_saddr, &r_saddr, sizeof(r_saddr));
+                        frame->len = n;
 
                         pthread_mutex_lock(&udp_data.mgmt_lock);
                         list_add(&frame->next, &udp_data.mgmt_frames);
@@ -962,7 +990,9 @@ static int ipcp_udp_query(const uint8_t * hash)
 
 static int ipcp_udp_flow_alloc(int             fd,
                                const uint8_t * dst,
-                               qosspec_t       qs)
+                               qosspec_t       qs,
+                               const void *    data,
+                               size_t          len)
 {
         struct sockaddr_in r_saddr; /* Server address */
         struct sockaddr_in c_saddr; /* Client address */
@@ -1026,7 +1056,7 @@ static int ipcp_udp_flow_alloc(int             fd,
                 return -1;
         }
 
-        if (ipcp_udp_port_alloc(skfd, fd, dst, qs) < 0) {
+        if (ipcp_udp_port_alloc(skfd, fd, dst, qs, data, len) < 0) {
                 log_err("Could not allocate port.");
                 close(skfd);
                 return -1;
@@ -1047,15 +1077,17 @@ static int ipcp_udp_flow_alloc(int             fd,
         return 0;
 }
 
-static int ipcp_udp_flow_alloc_resp(int fd,
-                                    int response)
+static int ipcp_udp_flow_alloc_resp(int          fd,
+                                    int          resp,
+                                    const void * data,
+                                    size_t       len)
 {
         struct timespec ts  = {0, FD_UPDATE_TIMEOUT * 1000};
         struct timespec abstime;
         int             skfd;
         int             d_eid;
 
-        if (response)
+        if (resp)
                 return 0;
 
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
@@ -1088,7 +1120,7 @@ static int ipcp_udp_flow_alloc_resp(int fd,
 
         pthread_rwlock_unlock(&udp_data.flows_lock);
 
-        if (ipcp_udp_port_alloc_resp(skfd, d_eid, fd, response) < 0) {
+        if (ipcp_udp_port_alloc_resp(skfd, d_eid, fd, resp, data, len) < 0) {
                 pthread_rwlock_rdlock(&udp_data.flows_lock);
                 fset_del(udp_data.np1_flows, fd);
                 pthread_rwlock_unlock(&udp_data.flows_lock);
diff --git a/src/ipcpd/unicast/fa.c b/src/ipcpd/unicast/fa.c
index 9ed9f710..e0727e85 100644
--- a/src/ipcpd/unicast/fa.c
+++ b/src/ipcpd/unicast/fa.c
@@ -51,6 +51,7 @@
 
 #define FLOW_REQ   0
 #define FLOW_REPLY 1
+#define MSGBUFSZ   2048
 
 struct fa_msg {
         uint64_t s_addr;
@@ -106,7 +107,7 @@ static void packet_handler(int                  fd,
 
 static void destroy_conn(int fd)
 {
-        fa.r_eid[fd]   = -1;
+        fa.r_eid[fd]  = -1;
         fa.r_addr[fd] = INVALID_ADDR;
 }
 
@@ -146,10 +147,12 @@ static void * fa_handle_packet(void * o)
         while (true) {
                 struct timespec abstime;
                 int             fd;
-                uint8_t *       buf;
+                uint8_t         buf[MSGBUFSZ];
                 struct fa_msg * msg;
                 qosspec_t       qs;
                 struct cmd *    cmd;
+                size_t          len;
+                size_t          msg_len;
 
                 pthread_mutex_lock(&fa.mtx);
 
@@ -164,10 +167,10 @@ static void * fa_handle_packet(void * o)
 
                 pthread_cleanup_pop(true);
 
-                buf = malloc(sizeof(*msg) + ipcp_dir_hash_len());
-                if (buf == NULL) {
-                        log_err("Failed to allocate memory.");
-                        ipcp_sdb_release(cmd->sdb);
+                len = shm_du_buff_tail(cmd->sdb) - shm_du_buff_head(cmd->sdb);
+
+                if (len > MSGBUFSZ) {
+                        log_err("Message over buffer size.");
                         free(cmd);
                         continue;
                 }
@@ -176,12 +179,7 @@ static void * fa_handle_packet(void * o)
 
                 /* Depending on the message call the function in ipcp-dev.h */
 
-                assert(sizeof(*msg) + ipcp_dir_hash_len() >=
-                       (unsigned long int) (shm_du_buff_tail(cmd->sdb) -
-                                            shm_du_buff_head(cmd->sdb)));
-
-                memcpy(msg, shm_du_buff_head(cmd->sdb),
-                       shm_du_buff_tail(cmd->sdb) - shm_du_buff_head(cmd->sdb));
+                memcpy(msg, shm_du_buff_head(cmd->sdb), len);
 
                 ipcp_sdb_release(cmd->sdb);
 
@@ -189,6 +187,10 @@ static void * fa_handle_packet(void * o)
 
                 switch (msg->code) {
                 case FLOW_REQ:
+                        msg_len = sizeof(*msg) + ipcp_dir_hash_len();
+
+                        assert(len >= msg_len);
+
                         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
 
                         pthread_mutex_lock(&ipcpi.alloc_lock);
@@ -205,7 +207,6 @@ static void * fa_handle_packet(void * o)
                                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                                 log_dbg("Won't allocate over non-operational"
                                         "IPCP.");
-                                free(msg);
                                 continue;
                         }
 
@@ -222,11 +223,12 @@ static void * fa_handle_packet(void * o)
 
                         fd = ipcp_flow_req_arr((uint8_t *) (msg + 1),
                                                ipcp_dir_hash_len(),
-                                               qs);
+                                               qs,
+                                               buf + msg_len,
+                                               len - msg_len);
                         if (fd < 0) {
                                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                                 log_err("Failed to get fd for flow.");
-                                free(msg);
                                 continue;
                         }
 
@@ -244,12 +246,16 @@ static void * fa_handle_packet(void * o)
 
                         break;
                 case FLOW_REPLY:
+                        assert(len >= sizeof(*msg));
+
                         pthread_rwlock_wrlock(&fa.flows_lock);
 
                         fa.r_eid[ntoh32(msg->r_eid)] = ntoh32(msg->s_eid);
 
                         ipcp_flow_alloc_reply(ntoh32(msg->r_eid),
-                                              msg->response);
+                                              msg->response,
+                                              buf + sizeof(*msg),
+                                              len - sizeof(*msg));
 
                         if (msg->response < 0)
                                 destroy_conn(ntoh32(msg->r_eid));
@@ -263,8 +269,6 @@ static void * fa_handle_packet(void * o)
                         log_err("Got an unknown flow allocation message.");
                         break;
                 }
-
-                free(msg);
         }
 }
 
@@ -363,18 +367,23 @@ void fa_stop(void)
 
 int fa_alloc(int             fd,
              const uint8_t * dst,
-             qosspec_t       qs)
+             qosspec_t       qs,
+             const void *    data,
+             size_t          dlen)
 {
         struct fa_msg *      msg;
         uint64_t             addr;
         struct shm_du_buff * sdb;
         qoscube_t            qc;
+        size_t               len;
 
         addr = dir_query(dst);
         if (addr == 0)
                 return -1;
 
-        if (ipcp_sdb_reserve(&sdb, sizeof(*msg) + ipcp_dir_hash_len()))
+        len = sizeof(*msg) + ipcp_dir_hash_len();
+
+        if (ipcp_sdb_reserve(&sdb, len + dlen))
                 return -1;
 
         msg               = (struct fa_msg *) shm_du_buff_head(sdb);
@@ -391,6 +400,7 @@ int fa_alloc(int             fd,
         msg->cypher_s     = hton16(qs.cypher_s);
 
         memcpy(msg + 1, dst, ipcp_dir_hash_len());
+        memcpy(shm_du_buff_head(sdb) + len, data, dlen);
 
         qc = qos_spec_to_cube(qs);
 
@@ -409,8 +419,10 @@ int fa_alloc(int             fd,
         return 0;
 }
 
-int fa_alloc_resp(int fd,
-                  int response)
+int fa_alloc_resp(int          fd,
+                  int          response,
+                  const void * data,
+                  size_t       len)
 {
         struct timespec      ts = {0, TIMEOUT * 1000};
         struct timespec      abstime;
@@ -439,7 +451,7 @@ int fa_alloc_resp(int fd,
 
         pthread_mutex_unlock(&ipcpi.alloc_lock);
 
-        if (ipcp_sdb_reserve(&sdb, sizeof(*msg) + ipcp_dir_hash_len())) {
+        if (ipcp_sdb_reserve(&sdb, sizeof(*msg) + len)) {
                 destroy_conn(fd);
                 return -1;
         }
@@ -452,6 +464,8 @@ int fa_alloc_resp(int fd,
         msg->s_eid    = hton32(fd);
         msg->response = response;
 
+        memcpy(msg + 1, data, len);
+
         if (response < 0) {
                 destroy_conn(fd);
                 ipcp_sdb_release(sdb);
diff --git a/src/ipcpd/unicast/fa.h b/src/ipcpd/unicast/fa.h
index 8ced5e84..12a10a0c 100644
--- a/src/ipcpd/unicast/fa.h
+++ b/src/ipcpd/unicast/fa.h
@@ -36,10 +36,14 @@ void fa_stop(void);
 
 int  fa_alloc(int             fd,
               const uint8_t * dst,
-              qosspec_t       qs);
-
-int  fa_alloc_resp(int fd,
-                   int response);
+              qosspec_t       qs,
+              const void *    data,
+              size_t          len);
+
+int  fa_alloc_resp(int          fd,
+                   int          response,
+                   const void * data,
+                   size_t       len);
 
 int  fa_dealloc(int fd);