Ensure we retransmit the SYNACK packet if we didn't get an ACK back for it.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index 6279d925a781814eeb06710c406fa47063c2f052..47acf221318bca518eca4d88bdd7ba04b0982071 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -816,7 +816,6 @@ ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
        if(!is_reliable(c)) {
                c->snd.una = c->snd.nxt = c->snd.last;
                buffer_discard(&c->sndbuf, c->sndbuf.used);
-               c->do_poll = true;
        }
 
        if(is_reliable(c) && !timespec_isset(&c->rtrx_timeout)) {
@@ -848,13 +847,7 @@ static void fast_retransmit(struct utcp_connection *c) {
        struct {
                struct hdr hdr;
                uint8_t data[];
-       } *pkt;
-
-       pkt = malloc(c->utcp->mtu);
-
-       if(!pkt) {
-               return;
-       }
+       } *pkt = c->utcp->pkt;
 
        pkt->hdr.src = c->src;
        pkt->hdr.dst = c->dst;
@@ -886,8 +879,6 @@ static void fast_retransmit(struct utcp_connection *c) {
        default:
                break;
        }
-
-       free(pkt);
 }
 
 static void retransmit(struct utcp_connection *c) {
@@ -899,6 +890,10 @@ static void retransmit(struct utcp_connection *c) {
 
        struct utcp *utcp = c->utcp;
 
+       if(utcp->retransmit) {
+               utcp->retransmit(c);
+       }
+
        struct {
                struct hdr hdr;
                uint8_t data[];
@@ -1114,11 +1109,14 @@ static void handle_in_order(struct utcp_connection *c, const void *data, size_t
                        size_t offset = len;
                        len = c->sacks[0].offset + c->sacks[0].len;
                        size_t remainder = len - offset;
-                       ssize_t rxd = buffer_call(&c->rcvbuf, c->recv, c, offset, remainder);
 
-                       if(rxd != (ssize_t)remainder) {
-                               // TODO: handle the application not accepting all data.
-                               abort();
+                       if(c->recv) {
+                               ssize_t rxd = buffer_call(&c->rcvbuf, c->recv, c, offset, remainder);
+
+                               if(rxd != (ssize_t)remainder) {
+                                       // TODO: handle the application not accepting all data.
+                                       abort();
+                               }
                        }
                }
        }
@@ -1133,7 +1131,10 @@ static void handle_in_order(struct utcp_connection *c, const void *data, size_t
 static void handle_unreliable(struct utcp_connection *c, const struct hdr *hdr, const void *data, size_t len) {
        // Fast path for unfragmented packets
        if(!hdr->wnd && !(hdr->ctl & MF)) {
-               c->recv(c, data, len);
+               if(c->recv) {
+                       c->recv(c, data, len);
+               }
+
                c->rcv.nxt = hdr->seq + len;
                return;
        }
@@ -1160,7 +1161,7 @@ static void handle_unreliable(struct utcp_connection *c, const struct hdr *hdr,
        }
 
        // Send the packet if it's the final fragment
-       if(!(hdr->ctl & MF)) {
+       if(!(hdr->ctl & MF) && c->recv) {
                buffer_call(&c->rcvbuf, c->recv, c, 0, hdr->wnd + len);
        }
 
@@ -1351,6 +1352,8 @@ synack:
                                print_packet(c, "send", &pkt, sizeof(hdr));
                                utcp->send(utcp, &pkt, sizeof(hdr));
                        }
+
+                       start_retransmit_timer(c);
                } else {
                        // No, we don't want your packets, send a RST back
                        len = 1;
@@ -1594,7 +1597,10 @@ synack:
 
                if(data_acked) {
                        buffer_discard(&c->sndbuf, data_acked);
-                       c->do_poll = true;
+
+                       if(is_reliable(c)) {
+                               c->do_poll = true;
+                       }
                }
 
                // Also advance snd.nxt if possible
@@ -1709,7 +1715,7 @@ skip_ack:
                        }
 
                        c->rcv.irs = hdr.seq;
-                       c->rcv.nxt = hdr.seq;
+                       c->rcv.nxt = hdr.seq + 1;
 
                        if(c->shut_wr) {
                                c->snd.last++;
@@ -1718,7 +1724,6 @@ skip_ack:
                                set_state(c, ESTABLISHED);
                        }
 
-                       // TODO: notify application of this somehow.
                        break;
 
                case SYN_RECEIVED:
@@ -1732,8 +1737,8 @@ skip_ack:
                case CLOSING:
                case LAST_ACK:
                case TIME_WAIT:
-                       // Ehm, no. We should never receive a second SYN.
-                       return 0;
+                       // This could be a retransmission. Ignore the SYN flag, but send an ACK back.
+                       break;
 
                default:
 #ifdef UTCP_DEBUG
@@ -1741,9 +1746,6 @@ skip_ack:
 #endif
                        return 0;
                }
-
-               // SYN counts as one sequence number
-               c->rcv.nxt++;
        }
 
        // 6. Process new data
@@ -2165,6 +2167,13 @@ struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_
                return NULL;
        }
 
+       utcp_set_mtu(utcp, DEFAULT_MTU);
+
+       if(!utcp->pkt) {
+               free(utcp);
+               return NULL;
+       }
+
        if(!CLOCK_GRANULARITY) {
                struct timespec res;
                clock_getres(UTCP_CLOCK, &res);
@@ -2175,7 +2184,6 @@ struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_
        utcp->pre_accept = pre_accept;
        utcp->send = send;
        utcp->priv = priv;
-       utcp_set_mtu(utcp, DEFAULT_MTU);
        utcp->timeout = DEFAULT_USER_TIMEOUT; // sec
 
        return utcp;
@@ -2318,7 +2326,7 @@ void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
                c->sndbuf.maxsize = -1;
        }
 
-       c->do_poll = buffer_free(&c->sndbuf);
+       c->do_poll = is_reliable(c) && buffer_free(&c->sndbuf);
 }
 
 size_t utcp_get_rcvbuf(struct utcp_connection *c) {
@@ -2386,7 +2394,7 @@ void utcp_set_recv_cb(struct utcp_connection *c, utcp_recv_t recv) {
 void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
        if(c) {
                c->poll = poll;
-               c->do_poll = buffer_free(&c->sndbuf);
+               c->do_poll = is_reliable(c) && buffer_free(&c->sndbuf);
        }
 }
 
@@ -2447,6 +2455,10 @@ void utcp_offline(struct utcp *utcp, bool offline) {
        }
 }
 
+void utcp_set_retransmit_cb(struct utcp *utcp, utcp_retransmit_t retransmit) {
+       utcp->retransmit = retransmit;
+}
+
 void utcp_set_clock_granularity(long granularity) {
        CLOCK_GRANULARITY = granularity;
 }