X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=utcp.c;h=802d95a2ba87ea3de46d9235176f5273361e6ca7;hb=eb85ec4ae5f32102430e0622e3855aaba110c032;hp=5938ea5bcea6af1a99b9d2e885b8fd68bdf70435;hpb=3bc564058072a79a22320f8c5bc50e8844896114;p=utcp

diff --git a/utcp.c b/utcp.c
index 5938ea5..802d95a 100644
--- a/utcp.c
+++ b/utcp.c
@@ -415,13 +415,13 @@ static void update_rtt(struct utcp_connection *c, uint32_t rtt) {
 	if(!utcp->srtt) {
 		utcp->srtt = rtt;
 		utcp->rttvar = rtt / 2;
-		utcp->rto = rtt + max(2 * rtt, CLOCK_GRANULARITY);
 	} else {
 		utcp->rttvar = (utcp->rttvar * 3 + absdiff(utcp->srtt, rtt)) / 4;
 		utcp->srtt = (utcp->srtt * 7 + rtt) / 8;
-		utcp->rto = utcp->srtt + max(utcp->rttvar, CLOCK_GRANULARITY);
 	}
 
+	utcp->rto = utcp->srtt + max(4 * utcp->rttvar, CLOCK_GRANULARITY);
+
 	if(utcp->rto > MAX_RTO) {
 		utcp->rto = MAX_RTO;
 	}
@@ -453,7 +453,7 @@ struct utcp_connection *utcp_connect_ex(struct utcp *utcp, uint16_t dst, utcp_re
 		return NULL;
 	}
 
-	assert((flags & ~0xf) == 0);
+	assert((flags & ~0x1f) == 0);
 
 	c->flags = flags;
 	c->recv = recv;
@@ -627,11 +627,17 @@ ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
 
 	// Add data to send buffer.
 
-	len = buffer_put(&c->sndbuf, data, len);
+	if(is_reliable(c) || (c->state != SYN_SENT && c->state != SYN_RECEIVED)) {
+		len = buffer_put(&c->sndbuf, data, len);
+	}
 
 	if(len <= 0) {
-		errno = EWOULDBLOCK;
-		return 0;
+		if(is_reliable(c)) {
+			errno = EWOULDBLOCK;
+			return 0;
+		} else {
+			return len;
+		}
 	}
 
 	c->snd.last += len;
@@ -1005,6 +1011,8 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		ptr += 2;
 	}
 
+	bool has_data = len || (hdr.ctl & (SYN | FIN));
+
 	// Try to match the packet to an existing connection
 
 	struct utcp_connection *c = find_connection(utcp, hdr.dst, hdr.src);
@@ -1047,6 +1055,7 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 				c->flags = UTCP_TCP;
 			}
 
+synack:
 			// Return SYN+ACK, go to SYN_RECEIVED state
 			c->snd.wnd = hdr.wnd;
 			c->rcv.irs = hdr.seq;
@@ -1099,8 +1108,6 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 
 	// It is for an existing connection.
 
-	uint32_t prevrcvnxt = c->rcv.nxt;
-
 	// 1. Drop invalid packets.
 
 	// 1a. Drop packets that should not happen in our current state.
@@ -1124,41 +1131,43 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		break;
 	}
 
-	// 1b. Drop packets with a sequence number not in our receive window.
+	// 1b. Discard data that is not in our receive window.
 
-	bool acceptable;
+	if(is_reliable(c)) {
+		bool acceptable;
 
-	if(c->state == SYN_SENT) {
-		acceptable = true;
-	} else if(len == 0) {
-		acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0;
-	} else {
-		int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
+		if(c->state == SYN_SENT) {
+			acceptable = true;
+		} else if(len == 0) {
+			acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0;
+		} else {
+			int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
 
-		// cut already accepted front overlapping
-		if(rcv_offset < 0) {
-			acceptable = len > (size_t) - rcv_offset;
+			// cut already accepted front overlapping
+			if(rcv_offset < 0) {
+				acceptable = len > (size_t) - rcv_offset;
 
-			if(acceptable) {
-				ptr -= rcv_offset;
-				len += rcv_offset;
-				hdr.seq -= rcv_offset;
+				if(acceptable) {
+					ptr -= rcv_offset;
+					len += rcv_offset;
+					hdr.seq -= rcv_offset;
+				}
+			} else {
+				acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
 			}
-		} else {
-			acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
 		}
-	}
 
-	if(!acceptable) {
-		debug("Packet not acceptable, %u <= %u + %lu < %u\n", c->rcv.nxt, hdr.seq, (unsigned long)len, c->rcv.nxt + c->rcvbuf.maxsize);
+		if(!acceptable) {
+			debug("Packet not acceptable, %u <= %u + %lu < %u\n", c->rcv.nxt, hdr.seq, (unsigned long)len, c->rcv.nxt + c->rcvbuf.maxsize);
 
-		// Ignore unacceptable RST packets.
-		if(hdr.ctl & RST) {
-			return 0;
-		}
+			// Ignore unacceptable RST packets.
+			if(hdr.ctl & RST) {
+				return 0;
+			}
 
-		// Otherwise, continue processing.
-		len = 0;
+			// Otherwise, continue processing.
+			len = 0;
+		}
 	}
 
 	c->snd.wnd = hdr.wnd; // TODO: move below
@@ -1167,6 +1176,12 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	// ackno should not roll back, and it should also not be bigger than what we ever could have sent
 	// (= snd.una + c->sndbuf.used).
 
+	if(!is_reliable(c)) {
+		if(hdr.ack != c->snd.last && c->state >= ESTABLISHED) {
+			hdr.ack = c->snd.una;
+		}
+	}
+
 	if(hdr.ctl & ACK && (seqdiff(hdr.ack, c->snd.last) > 0 || seqdiff(hdr.ack, c->snd.una) < 0)) {
 		debug("Packet ack seqno out of range, %u <= %u < %u\n", c->snd.una, hdr.ack, c->snd.una + c->sndbuf.used);
 
@@ -1195,6 +1210,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 				c->recv(c, NULL, 0);
 			}
 
+			if(c->poll && !c->reapable) {
+				c->poll(c, 0);
+			}
+
 			return 0;
 
 		case SYN_RECEIVED:
@@ -1222,6 +1241,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 				c->recv(c, NULL, 0);
 			}
 
+			if(c->poll && !c->reapable) {
+				c->poll(c, 0);
+			}
+
 			return 0;
 
 		case CLOSING:
@@ -1260,7 +1283,6 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	// 3. Advance snd.una
 
 	advanced = seqdiff(hdr.ack, c->snd.una);
-	prevrcvnxt = c->rcv.nxt;
 
 	if(advanced) {
 		// RTT measurement
@@ -1325,7 +1347,7 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		case CLOSING:
 			if(c->snd.una == c->snd.last) {
 				gettimeofday(&c->conn_timeout, NULL);
-				c->conn_timeout.tv_sec += 60;
+				c->conn_timeout.tv_sec += utcp->timeout;
 				set_state(c, TIME_WAIT);
 			}
 
@@ -1389,6 +1411,9 @@ skip_ack:
 			break;
 
 		case SYN_RECEIVED:
+			// This is a retransmit of a SYN, send back the SYNACK.
+			goto synack;
+
 		case ESTABLISHED:
 		case FIN_WAIT_1:
 		case FIN_WAIT_2:
@@ -1464,7 +1489,7 @@ skip_ack:
 
 	// 7. Process FIN stuff
 
-	if((hdr.ctl & FIN) && hdr.seq + len == c->rcv.nxt) {
+	if((hdr.ctl & FIN) && (!is_reliable(c) || hdr.seq + len == c->rcv.nxt)) {
 		switch(c->state) {
 		case SYN_SENT:
 		case SYN_RECEIVED:
@@ -1484,7 +1509,7 @@ skip_ack:
 
 		case FIN_WAIT_2:
 			gettimeofday(&c->conn_timeout, NULL);
-			c->conn_timeout.tv_sec += 60;
+			c->conn_timeout.tv_sec += utcp->timeout;
 			set_state(c, TIME_WAIT);
 			break;
 
@@ -1506,7 +1531,7 @@ skip_ack:
 		c->rcv.nxt++;
 		len++;
 
-		// Inform the application that the peer closed the connection.
+		// Inform the application that the peer closed its end of the connection.
 		if(c->recv) {
 			errno = 0;
 			c->recv(c, NULL, 0);
@@ -1514,12 +1539,15 @@ skip_ack:
 	}
 
 	// Now we send something back if:
-	// - we advanced rcv.nxt (ie, we got some data that needs to be ACKed)
+	// - we received data, so we have to send back an ACK
 	//   -> sendatleastone = true
 	// - or we got an ack, so we should maybe send a bit more data
 	//   -> sendatleastone = false
 
-	ack(c, len || prevrcvnxt != c->rcv.nxt);
+	if(is_reliable(c) || hdr.ctl & SYN || hdr.ctl & FIN) {
+		ack(c, has_data);
+	}
+
 	return 0;
 
 reset:
@@ -1685,6 +1713,7 @@ void utcp_abort_all_connections(struct utcp *utcp) {
 		}
 
 		utcp_recv_t old_recv = c->recv;
+		utcp_poll_t old_poll = c->poll;
 
 		reset_connection(c);
 
@@ -1692,6 +1721,11 @@ void utcp_abort_all_connections(struct utcp *utcp) {
 			errno = 0;
 			old_recv(c, NULL, 0);
 		}
+
+		if(old_poll && !c->reapable) {
+			errno = 0;
+			old_poll(c, 0);
+		}
 	}
 
 	return;
@@ -1754,7 +1788,7 @@ struct timeval utcp_timeout(struct utcp *utcp) {
 				c->recv(c, NULL, 0);
 			}
 
-			if(c->poll) {
+			if(c->poll && !c->reapable) {
 				c->poll(c, 0);
 			}
 
@@ -1838,11 +1872,16 @@ void utcp_exit(struct utcp *utcp) {
 	for(int i = 0; i < utcp->nconnections; i++) {
 		struct utcp_connection *c = utcp->connections[i];
 
-		if(!c->reapable)
+		if(!c->reapable) {
 			if(c->recv) {
 				c->recv(c, NULL, 0);
 			}
 
+			if(c->poll && !c->reapable) {
+				c->poll(c, 0);
+			}
+		}
+
 		buffer_exit(&c->rcvbuf);
 		buffer_exit(&c->sndbuf);
 		free(c);
@@ -1883,8 +1922,14 @@ void utcp_reset_timers(struct utcp *utcp) {
 			continue;
 		}
 
-		c->rtrx_timeout = now;
-		c->conn_timeout = then;
+		if(timerisset(&c->rtrx_timeout)) {
+			c->rtrx_timeout = now;
+		}
+
+		if(timerisset(&c->conn_timeout)) {
+			c->conn_timeout = then;
+		}
+
 		c->rtt_start.tv_sec = 0;
 	}
 
@@ -2035,19 +2080,24 @@ void utcp_expect_data(struct utcp_connection *c, bool expect) {
 }
 
 void utcp_offline(struct utcp *utcp, bool offline) {
+	struct timeval now;
+	gettimeofday(&now, NULL);
+
 	for(int i = 0; i < utcp->nconnections; i++) {
 		struct utcp_connection *c = utcp->connections[i];
 
-		if(!c->reapable) {
-			utcp_expect_data(c, offline);
-
-			// If we are online again, reset the retransmission timers, but keep the connection timeout as it is,
-			// to prevent peers toggling online/offline state frequently from keeping connections alive
-			// if there is no progress in sending actual data.
-			if(!offline) {
-				gettimeofday(&utcp->connections[i]->rtrx_timeout, NULL);
-				utcp->connections[i]->rtt_start.tv_sec = 0;
+		if(c->reapable) {
+			continue;
+		}
+
+		utcp_expect_data(c, offline);
+
+		if(!offline) {
+			if(timerisset(&c->rtrx_timeout)) {
+				c->rtrx_timeout = now;
 			}
+
+			utcp->connections[i]->rtt_start.tv_sec = 0;
 		}
 	}