X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=utcp.c;h=e8755ed14470577b6baafbab0d127476454e4dba;hb=b570e123128f3fafa583bae186fd61429dcb49a7;hp=a79304ca8114b717028e9f8d5e3ede76948e6ccf;hpb=62454c16e18ba9ed03b5bc55ea59d28d666d8a48;p=utcp

diff --git a/utcp.c b/utcp.c
index a79304c..e8755ed 100644
--- a/utcp.c
+++ b/utcp.c
@@ -103,6 +103,19 @@ static void set_state(struct utcp_connection *c, enum state state) {
 	debug("%p new state: %s\n", c->utcp, strstate[state]);
 }
 
+static bool fin_wanted(struct utcp_connection *c, uint32_t seq) {
+	if(seq != c->snd.last)
+		return false;
+	switch(c->state) {
+	case FIN_WAIT_1:
+	case CLOSING:
+	case LAST_ACK:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static inline void list_connections(struct utcp *utcp) {
 	debug("%p has %d connections:\n", utcp, utcp->nconnections);
 	for(int i = 0; i < utcp->nconnections; i++)
@@ -366,16 +379,9 @@ static void ack(struct utcp_connection *c, bool sendatleastone) {
 		c->snd.nxt += seglen;
 		left -= seglen;
 
-		if(c->state != ESTABLISHED && !left && seglen) {
-			switch(c->state) {
-			case FIN_WAIT_1:
-			case CLOSING:
-				seglen--;
-				pkt->hdr.ctl |= FIN;
-				break;
-			default:
-				break;
-			}
+		if(seglen && fin_wanted(c, c->snd.nxt)) {
+			seglen--;
+			pkt->hdr.ctl |= FIN;
 		}
 
 		print_packet(c->utcp, "send", pkt, sizeof pkt->hdr + seglen);
@@ -440,6 +446,81 @@ static void swap_ports(struct hdr *hdr) {
 	hdr->dst = tmp;
 }
 
+static void retransmit(struct utcp_connection *c) {
+	if(c->state == CLOSED || c->snd.nxt == c->snd.una)
+		return;
+
+	struct utcp *utcp = c->utcp;
+
+	struct {
+		struct hdr hdr;
+		char data[];
+	} *pkt;
+
+	pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
+	if(!pkt)
+		return;
+
+	pkt->hdr.src = c->src;
+	pkt->hdr.dst = c->dst;
+
+	switch(c->state) {
+		case SYN_SENT:
+			// Send our SYN again
+			pkt->hdr.seq = c->snd.iss;
+			pkt->hdr.ack = 0;
+			pkt->hdr.wnd = c->rcv.wnd;
+			pkt->hdr.ctl = SYN;
+			print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
+			utcp->send(utcp, pkt, sizeof pkt->hdr);
+			break;
+
+		case SYN_RECEIVED:
+			// Send SYNACK again
+			pkt->hdr.seq = c->snd.nxt;
+			pkt->hdr.ack = c->rcv.nxt;
+			pkt->hdr.ctl = SYN | ACK;
+			print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
+			utcp->send(utcp, pkt, sizeof pkt->hdr);
+			break;
+
+		case ESTABLISHED:
+		case FIN_WAIT_1:
+		case CLOSE_WAIT:
+		case CLOSING:
+		case LAST_ACK:
+			// Send unacked data again.
+			pkt->hdr.seq = c->snd.una;
+			pkt->hdr.ack = c->rcv.nxt;
+			pkt->hdr.ctl = ACK;
+			uint32_t len = seqdiff(c->snd.last, c->snd.una);
+			if(len > utcp->mtu)
+				len = utcp->mtu;
+			if(fin_wanted(c, c->snd.una + len)) {
+				len--;
+				pkt->hdr.ctl |= FIN;
+			}
+			buffer_copy(&c->sndbuf, pkt->data, 0, len);
+			print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr + len);
+			utcp->send(utcp, pkt, sizeof pkt->hdr + len);
+			break;
+
+		case CLOSED:
+		case LISTEN:
+		case TIME_WAIT:
+		case FIN_WAIT_2:
+			// We shouldn't need to retransmit anything in this state.
+#ifdef UTCP_DEBUG
+			abort();
+#endif
+			timerclear(&c->rtrx_timeout);
+			break;
+	}
+
+	free(pkt);
+}
+
+
 ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	if(!utcp) {
 		errno = EFAULT;
@@ -555,7 +636,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	case TIME_WAIT:
 		break;
 	default:
+#ifdef UTCP_DEBUG
 		abort();
+#endif
+		break;
 	}
 
 	// 1b. Drop packets with a sequence number not in our receive window.
@@ -587,12 +671,13 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 #endif
 
 	if(!acceptable) {
-		debug("Packet not acceptable, %u  <= %u + %zu < %u\n", c->rcv.nxt, hdr.seq, len, c->rcv.nxt + c->rcv.wnd);
+		debug("Packet not acceptable, %u <= %u + %zu < %u\n", c->rcv.nxt, hdr.seq, len, c->rcv.nxt + c->rcv.wnd);
 		// Ignore unacceptable RST packets.
 		if(hdr.ctl & RST)
 			return 0;
 		// Otherwise, send an ACK back in the hope things improve.
-		goto ack;
+		ack(c, true);
+		return 0;
 	}
 
 	c->snd.wnd = hdr.wnd; // TODO: move below
@@ -654,7 +739,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 			set_state(c, CLOSED);
 			return 0;
 		default:
+#ifdef UTCP_DEBUG
 			abort();
+#endif
+			break;
 		}
 	}
 
@@ -710,10 +798,13 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	} else {
 		if(!len) {
 			c->dupack++;
-			if(c->dupack >= 3) {
+			if(c->dupack == 3) {
 				debug("Triplicate ACK\n");
 				//TODO: Resend one packet and go to fast recovery mode. See RFC 6582.
-				//abort();
+				//We do a very simple variant here; reset the nxt pointer to the last acknowledged packet from the peer.
+				//This will cause us to start retransmitting, but at the same speed as the incoming ACKs arrive,
+				//thus preventing a drop in speed.
+				c->snd.nxt = c->snd.una;
 			}
 		}
 	}
@@ -750,7 +841,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 			// Ehm, no. We should never receive a second SYN.
 			goto reset;
 		default:
+#ifdef UTCP_DEBUG
 			abort();
+#endif
+			return 0;
 		}
 
 		// SYN counts as one sequence number
@@ -780,7 +874,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		case SYN_SENT:
 		case SYN_RECEIVED:
 			// This should never happen.
+#ifdef UTCP_DEBUG
 			abort();
+#endif
+			return 0;
 		case ESTABLISHED:
 		case FIN_WAIT_1:
 		case FIN_WAIT_2:
@@ -792,7 +889,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 			// Ehm no, We should never receive more data after a FIN.
 			goto reset;
 		default:
+#ifdef UTCP_DEBUG
 			abort();
+#endif
+			return 0;
 		}
 
 		ssize_t rxd;
@@ -821,7 +921,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		case SYN_SENT:
 		case SYN_RECEIVED:
 			// This should never happen.
+#ifdef UTCP_DEBUG
 			abort();
+#endif
+			break;
 		case ESTABLISHED:
 			set_state(c, CLOSE_WAIT);
 			break;
@@ -840,7 +943,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 			// Ehm, no. We should never receive a second FIN.
 			goto reset;
 		default:
+#ifdef UTCP_DEBUG
 			abort();
+#endif
+			break;
 		}
 
 		// FIN counts as one sequence number
@@ -882,7 +988,7 @@ reset:
 }
 
 int utcp_shutdown(struct utcp_connection *c, int dir) {
-	debug("%p shutdown %d\n", c ? c->utcp : NULL, dir);
+	debug("%p shutdown %d at %u\n", c ? c->utcp : NULL, dir, c->snd.last);
 	if(!c) {
 		errno = EFAULT;
 		return -1;
@@ -895,6 +1001,7 @@ int utcp_shutdown(struct utcp_connection *c, int dir) {
 	}
 
 	// TODO: handle dir
+	// TODO: check that repeated calls with the same parameters should have no effect
 
 	switch(c->state) {
 	case CLOSED:
@@ -930,6 +1037,8 @@ int utcp_shutdown(struct utcp_connection *c, int dir) {
 int utcp_close(struct utcp_connection *c) {
 	if(utcp_shutdown(c, SHUT_RDWR))
 		return -1;
+	c->recv = NULL;
+	c->poll = NULL;
 	c->reapable = true;
 	return 0;
 }
@@ -946,6 +1055,8 @@ int utcp_abort(struct utcp_connection *c) {
 		return -1;
 	}
 
+	c->recv = NULL;
+	c->poll = NULL;
 	c->reapable = true;
 
 	switch(c->state) {
@@ -984,80 +1095,13 @@ int utcp_abort(struct utcp_connection *c) {
 	return 0;
 }
 
-static void retransmit(struct utcp_connection *c) {
-	if(c->state == CLOSED || c->snd.nxt == c->snd.una)
-		return;
-
-	struct utcp *utcp = c->utcp;
-
-	struct {
-		struct hdr hdr;
-		char data[];
-	} *pkt;
-
-	pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
-	if(!pkt)
-		return;
-
-	pkt->hdr.src = c->src;
-	pkt->hdr.dst = c->dst;
-
-	switch(c->state) {
-		case LISTEN:
-			// TODO: this should not happen
-			break;
-
-		case SYN_SENT:
-			pkt->hdr.seq = c->snd.iss;
-			pkt->hdr.ack = 0;
-			pkt->hdr.wnd = c->rcv.wnd;
-			pkt->hdr.ctl = SYN;
-			print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
-			utcp->send(utcp, pkt, sizeof pkt->hdr);
-			break;
-
-		case SYN_RECEIVED:
-			pkt->hdr.seq = c->snd.nxt;
-			pkt->hdr.ack = c->rcv.nxt;
-			pkt->hdr.ctl = SYN | ACK;
-			print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
-			utcp->send(utcp, pkt, sizeof pkt->hdr);
-			break;
-
-		case ESTABLISHED:
-		case FIN_WAIT_1:
-			pkt->hdr.seq = c->snd.una;
-			pkt->hdr.ack = c->rcv.nxt;
-			pkt->hdr.ctl = ACK;
-			uint32_t len = seqdiff(c->snd.nxt, c->snd.una);
-			if(c->state == FIN_WAIT_1)
-				len--;
-			if(len > utcp->mtu)
-				len = utcp->mtu;
-			else {
-				if(c->state == FIN_WAIT_1)
-					pkt->hdr.ctl |= FIN;
-			}
-			buffer_copy(&c->sndbuf, pkt->data, 0, len);
-			print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr + len);
-			utcp->send(utcp, pkt, sizeof pkt->hdr + len);
-			break;
-
-		default:
-			// TODO: implement
-			abort();
-	}
-
-	free(pkt);
-}
-
 /* Handle timeouts.
  * One call to this function will loop through all connections,
  * checking if something needs to be resent or not.
  * The return value is the time to the next timeout in milliseconds,
  * or maybe a negative value if the timeout is infinite.
  */
-int utcp_timeout(struct utcp *utcp) {
+struct timeval utcp_timeout(struct utcp *utcp) {
 	struct timeval now;
 	gettimeofday(&now, NULL);
 	struct timeval next = {now.tv_sec + 3600, now.tv_usec};
@@ -1107,9 +1151,7 @@ int utcp_timeout(struct utcp *utcp) {
 
 	struct timeval diff;
 	timersub(&next, &now, &diff);
-	if(diff.tv_sec < 0)
-		return 0;
-	return diff.tv_sec * 1000 + diff.tv_usec / 1000;
+	return diff;
 }
 
 struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_send_t send, void *priv) {
@@ -1146,60 +1188,71 @@ void utcp_exit(struct utcp *utcp) {
 }
 
 uint16_t utcp_get_mtu(struct utcp *utcp) {
-	return utcp->mtu;
+	return utcp ? utcp->mtu : 0;
 }
 
 void utcp_set_mtu(struct utcp *utcp, uint16_t mtu) {
 	// TODO: handle overhead of the header
-	utcp->mtu = mtu;
+	if(utcp)
+		utcp->mtu = mtu;
 }
 
 int utcp_get_user_timeout(struct utcp *u) {
-	return u->timeout;
+	return u ? u->timeout : 0;
 }
 
 void utcp_set_user_timeout(struct utcp *u, int timeout) {
-	u->timeout = timeout;
+	if(u)
+		u->timeout = timeout;
 }
 
 size_t utcp_get_sndbuf(struct utcp_connection *c) {
-	return c->sndbuf.maxsize;
+	return c ? c->sndbuf.maxsize : 0;
 }
 
 size_t utcp_get_sndbuf_free(struct utcp_connection *c) {
-	return buffer_free(&c->sndbuf);
+	if(c && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
+		return buffer_free(&c->sndbuf);
+	else
+		return 0;
 }
 
 void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
+	if(!c)
+		return;
 	c->sndbuf.maxsize = size;
 	if(c->sndbuf.maxsize != size)
 		c->sndbuf.maxsize = -1;
 }
 
 bool utcp_get_nodelay(struct utcp_connection *c) {
-	return c->nodelay;
+	return c ? c->nodelay : false;
 }
 
 void utcp_set_nodelay(struct utcp_connection *c, bool nodelay) {
-	c->nodelay = nodelay;
+	if(c)
+		c->nodelay = nodelay;
 }
 
 bool utcp_get_keepalive(struct utcp_connection *c) {
-	return c->keepalive;
+	return c ? c->keepalive : false;
 }
 
 void utcp_set_keepalive(struct utcp_connection *c, bool keepalive) {
-	c->keepalive = keepalive;
+	if(c)
+		c->keepalive = keepalive;
 }
 
 size_t utcp_get_outq(struct utcp_connection *c) {
-	return seqdiff(c->snd.nxt, c->snd.una);
+	return c ? seqdiff(c->snd.nxt, c->snd.una) : 0;
 }
 
 void utcp_set_recv_cb(struct utcp_connection *c, utcp_recv_t recv) {
-	c->recv = recv;
+	if(c)
+		c->recv = recv;
 }
 
 void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
-	c->poll = poll;
+	if(c)
+		c->poll = poll;
 }