Handle channel closure during a receive callback when the ringbuffer wraps.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index 6279d925a781814eeb06710c406fa47063c2f052..04d2b194c20f193aa44f2d4006b9afc1bd356b29 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -268,7 +268,7 @@ static ssize_t buffer_put_at(struct buffer *buf, size_t offset, const void *data
 
        uint32_t realoffset = buf->offset + offset;
 
-       if(buf->size - buf->offset < offset) {
+       if(buf->size - buf->offset <= offset) {
                // The offset wrapped
                realoffset -= buf->size;
        }
@@ -305,7 +305,7 @@ static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t
 
        uint32_t realoffset = buf->offset + offset;
 
-       if(buf->size - buf->offset < offset) {
+       if(buf->size - buf->offset <= offset) {
                // The offset wrapped
                realoffset -= buf->size;
        }
@@ -322,7 +322,11 @@ static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t
 }
 
 // Copy data from the buffer without removing it.
-static ssize_t buffer_call(struct buffer *buf, utcp_recv_t cb, void *arg, size_t offset, size_t len) {
+static ssize_t buffer_call(struct utcp_connection *c, struct buffer *buf, size_t offset, size_t len) {
+       if(!c->recv) {
+               return len;
+       }
+
        // Ensure we don't copy more than is actually stored in the buffer
        if(offset >= buf->used) {
                return 0;
@@ -334,20 +338,25 @@ static ssize_t buffer_call(struct buffer *buf, utcp_recv_t cb, void *arg, size_t
 
        uint32_t realoffset = buf->offset + offset;
 
-       if(buf->size - buf->offset < offset) {
+       if(buf->size - buf->offset <= offset) {
                // The offset wrapped
                realoffset -= buf->size;
        }
 
        if(buf->size - realoffset < len) {
                // The data is wrapped
-               ssize_t rx1 = cb(arg, buf->data + realoffset, buf->size - realoffset);
+               ssize_t rx1 = c->recv(c, buf->data + realoffset, buf->size - realoffset);
 
                if(rx1 < buf->size - realoffset) {
                        return rx1;
                }
 
-               ssize_t rx2 = cb(arg, buf->data, len - (buf->size - realoffset));
+               // The channel might have been closed by the previous callback
+               if(!c->recv) {
+                       return len;
+               }
+
+               ssize_t rx2 = c->recv(c, buf->data, len - (buf->size - realoffset));
 
                if(rx2 < 0) {
                        return rx2;
@@ -355,7 +364,7 @@ static ssize_t buffer_call(struct buffer *buf, utcp_recv_t cb, void *arg, size_t
                        return rx1 + rx2;
                }
        } else {
-               return cb(arg, buf->data + realoffset, len);
+               return c->recv(c, buf->data + realoffset, len);
        }
 }
 
@@ -365,7 +374,7 @@ static ssize_t buffer_discard(struct buffer *buf, size_t len) {
                len = buf->used;
        }
 
-       if(buf->size - buf->offset < len) {
+       if(buf->size - buf->offset <= len) {
                buf->offset -= buf->size;
        }
 
@@ -816,7 +825,6 @@ 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 +856,7 @@ 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 +888,6 @@ static void fast_retransmit(struct utcp_connection *c) {
        default:
                break;
        }
-
-       free(pkt);
 }
 
 static void retransmit(struct utcp_connection *c) {
@@ -899,6 +899,10 @@ 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[];
@@ -1114,7 +1118,8 @@ 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);
+
+                       ssize_t rxd = buffer_call(c, &c->rcvbuf, offset, remainder);
 
                        if(rxd != (ssize_t)remainder) {
                                // TODO: handle the application not accepting all data.
@@ -1133,7 +1138,10 @@ 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;
        }
@@ -1161,7 +1169,7 @@ 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)) {
-               buffer_call(&c->rcvbuf, c->recv, c, 0, hdr->wnd + len);
+               buffer_call(c, &c->rcvbuf, 0, hdr->wnd + len);
        }
 
        c->rcv.nxt = hdr->seq + len;
@@ -1351,6 +1359,8 @@ 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 +1604,10 @@ 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 +1722,7 @@ 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 +1731,6 @@ skip_ack:
                                set_state(c, ESTABLISHED);
                        }
 
-                       // TODO: notify application of this somehow.
                        break;
 
                case SYN_RECEIVED:
@@ -1732,8 +1744,8 @@ 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 +1753,6 @@ skip_ack:
 #endif
                        return 0;
                }
-
-               // SYN counts as one sequence number
-               c->rcv.nxt++;
        }
 
        // 6. Process new data
@@ -2165,6 +2174,13 @@ 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 +2191,6 @@ 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 +2333,7 @@ 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 +2401,7 @@ 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 +2462,10 @@ 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;
 }