X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=utcp.c;h=f5484ab82b92e53e5365f7de75a822881218a7f4;hb=aef3cad25ea81f727608689ef97fce9e0dbe5285;hp=75553d72567be387667b7ced7871cac32d0d6a46;hpb=5d25d40b5baf4bd60ccc1dc6db65b3e5b094e2cd;p=utcp

diff --git a/utcp.c b/utcp.c
index 75553d7..f5484ab 100644
--- a/utcp.c
+++ b/utcp.c
@@ -113,13 +113,84 @@ static int32_t seqdiff(uint32_t a, uint32_t b) {
 	return a - b;
 }
 
+// Buffer functions
+// TODO: convert to ringbuffers to avoid memmove() operations.
+
+// Store data into the buffer
+static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
+	if(buf->maxsize <= buf->used)
+		return 0;
+	if(len > buf->maxsize - buf->used)
+		len = buf->maxsize - buf->used;
+	if(len > buf->size - buf->used) {
+		size_t newsize = buf->size;
+		do {
+			newsize *= 2;
+		} while(newsize < buf->used + len);
+		if(newsize > buf->maxsize)
+			newsize = buf->maxsize;
+		char *newdata = realloc(buf->data, newsize);
+		if(!newdata)
+			return -1;
+		buf->data = newdata;
+		buf->size = newsize;
+	}
+	memcpy(buf->data + buf->used, data, len);
+	buf->used += len;
+	return len;
+}
+
+// Get data from the buffer. data can be NULL.
+static ssize_t buffer_get(struct buffer *buf, void *data, size_t len) {
+	if(len > buf->used)
+		len = buf->used;
+	if(data)
+		memcpy(data, buf->data, len);
+	if(len < buf->used)
+		memmove(buf->data, buf->data + len, buf->used - len);
+	buf->used -= len;
+	return len;
+}
+
+// Copy data from the buffer without removing it.
+static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t len) {
+	if(offset >= buf->used)
+		return 0;
+	if(offset + len > buf->used)
+		len = buf->used - offset;
+	memcpy(data, buf->data + offset, len);
+	return len;
+}
+
+static bool buffer_init(struct buffer *buf, uint32_t len, uint32_t maxlen) {
+	memset(buf, 0, sizeof *buf);
+	buf->data = malloc(len);
+	if(!len)
+		return false;
+	buf->size = len;
+	buf->maxsize = maxlen;
+	return true;
+}
+
+static void buffer_exit(struct buffer *buf) {
+	free(buf->data);
+	memset(buf, 0, sizeof *buf);
+}
+
+static uint32_t buffer_free(const struct buffer *buf) {
+	return buf->maxsize - buf->used;
+}
+
 // Connections are stored in a sorted list.
 // This gives O(log(N)) lookup time, O(N log(N)) insertion time and O(N) deletion time.
 
 static int compare(const void *va, const void *vb) {
+	assert(va && vb);
+
 	const struct utcp_connection *a = *(struct utcp_connection **)va;
 	const struct utcp_connection *b = *(struct utcp_connection **)vb;
 
+	assert(a && b);
 	assert(a->src && b->src);
 
 	int c = (int)a->src - (int)b->src;
@@ -147,10 +218,10 @@ static void free_connection(struct utcp_connection *c) {
 	assert(cp);
 
 	int i = cp - utcp->connections;
-	memmove(cp + i, cp + i + 1, (utcp->nconnections - i - 1) * sizeof *cp);
+	memmove(cp, cp + 1, (utcp->nconnections - i - 1) * sizeof *cp);
 	utcp->nconnections--;
 
-	free(c->sndbuf);
+	buffer_exit(&c->sndbuf);
 	free(c);
 }
 
@@ -189,10 +260,7 @@ static struct utcp_connection *allocate_connection(struct utcp *utcp, uint16_t s
 	if(!c)
 		return NULL;
 
-	c->sndbufsize = DEFAULT_SNDBUFSIZE;
-	c->maxsndbufsize = DEFAULT_MAXSNDBUFSIZE;
-	c->sndbuf = malloc(c->sndbufsize);
-	if(!c->sndbuf) {
+	if(!buffer_init(&c->sndbuf, DEFAULT_SNDBUFSIZE, DEFAULT_MAXSNDBUFSIZE)) {
 		free(c);
 		return NULL;
 	}
@@ -261,7 +329,6 @@ void utcp_accept(struct utcp_connection *c, utcp_recv_t recv, void *priv) {
 static void ack(struct utcp_connection *c, bool sendatleastone) {
 	int32_t left = seqdiff(c->snd.last, c->snd.nxt);
 	int32_t cwndleft = c->snd.cwnd - seqdiff(c->snd.nxt, c->snd.una);
-	char *data = c->sndbuf + seqdiff(c->snd.nxt, c->snd.una);
 
 	assert(left >= 0);
 
@@ -276,24 +343,27 @@ static void ack(struct utcp_connection *c, bool sendatleastone) {
 
 	struct {
 		struct hdr hdr;
-		char data[c->utcp->mtu];
-	} pkt;
+		char data[];
+	} *pkt;
+
+	pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
+	if(!pkt->data)
+		return;
 
-	pkt.hdr.src = c->src;
-	pkt.hdr.dst = c->dst;
-	pkt.hdr.ack = c->rcv.nxt;
-	pkt.hdr.wnd = c->snd.wnd;
-	pkt.hdr.ctl = ACK;
-	pkt.hdr.aux = 0;
+	pkt->hdr.src = c->src;
+	pkt->hdr.dst = c->dst;
+	pkt->hdr.ack = c->rcv.nxt;
+	pkt->hdr.wnd = c->snd.wnd;
+	pkt->hdr.ctl = ACK;
+	pkt->hdr.aux = 0;
 
 	do {
 		uint32_t seglen = left > c->utcp->mtu ? c->utcp->mtu : left;
-		pkt.hdr.seq = c->snd.nxt;
+		pkt->hdr.seq = c->snd.nxt;
 
-		memcpy(pkt.data, data, seglen);
+		buffer_copy(&c->sndbuf, pkt->data, seqdiff(c->snd.nxt, c->snd.una), seglen);
 
 		c->snd.nxt += seglen;
-		data += seglen;
 		left -= seglen;
 
 		if(c->state != ESTABLISHED && !left && seglen) {
@@ -301,16 +371,18 @@ static void ack(struct utcp_connection *c, bool sendatleastone) {
 			case FIN_WAIT_1:
 			case CLOSING:
 				seglen--;
-				pkt.hdr.ctl |= FIN;
+				pkt->hdr.ctl |= FIN;
 				break;
 			default:
 				break;
 			}
 		}
 
-		print_packet(c->utcp, "send", &pkt, sizeof pkt.hdr + seglen);
-		c->utcp->send(c->utcp, &pkt, sizeof pkt.hdr + seglen);
+		print_packet(c->utcp, "send", pkt, sizeof pkt->hdr + seglen);
+		c->utcp->send(c->utcp, pkt, sizeof pkt->hdr + seglen);
 	} while(left);
+
+	free(pkt);
 }
 
 ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
@@ -351,44 +423,13 @@ ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
 		return -1;
 	}
 
-	uint32_t bufused = seqdiff(c->snd.nxt, c->snd.una);
-
-	/* Check our send buffer.
-	 * - If it's big enough, just put the data in there.
-	 * - If not, decide whether to enlarge if possible.
-	 * - Cap len so it doesn't overflow our buffer.
-	 */
-
-	if(len > c->sndbufsize - bufused && c->sndbufsize < c->maxsndbufsize) {
-		uint32_t newbufsize;
-		if(c->sndbufsize > c->maxsndbufsize / 2)
-			newbufsize = c->maxsndbufsize;
-		else
-			newbufsize = c->sndbufsize * 2;
-		if(bufused + len > newbufsize) {
-			if(bufused + len > c->maxsndbufsize)
-				newbufsize = c->maxsndbufsize;
-			else
-				newbufsize = bufused + len;
-		}
-		char *newbuf = realloc(c->sndbuf, newbufsize);
-		if(newbuf) {
-			c->sndbuf = newbuf;
-			c->sndbufsize = newbufsize;
-		}
-	}
-
-	if(len > c->sndbufsize - bufused)
-		len = c->sndbufsize - bufused;
-
-	if(!len) {
-		errno == EWOULDBLOCK;
+	len = buffer_put(&c->sndbuf, data, len);
+	if(len <= 0) {
+		errno = EWOULDBLOCK;
 		return 0;
 	}
 
-	memcpy(c->sndbuf + bufused, data, len);
 	c->snd.last += len;
-
 	ack(c, false);
 	return len;
 }
@@ -399,6 +440,74 @@ 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 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);
+}
+
+
 ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	if(!utcp) {
 		errno = EFAULT;
@@ -496,6 +605,8 @@ 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.
@@ -544,12 +655,13 @@ 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
@@ -618,7 +730,7 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	// 3. Advance snd.una
 
 	uint32_t advanced = seqdiff(hdr.ack, c->snd.una);
-	uint32_t prevrcvnxt = c->rcv.nxt;
+	prevrcvnxt = c->rcv.nxt;
 
 	if(advanced) {
 		int32_t data_acked = advanced;
@@ -638,18 +750,15 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		int32_t bufused = seqdiff(c->snd.last, c->snd.una);
 		assert(data_acked <= bufused);
 
-		// Make room in the send buffer.
-		// TODO: try to avoid memmoving too much. Circular buffer?
-		uint32_t left = bufused - data_acked;
-		if(data_acked && left)
-			memmove(c->sndbuf, c->sndbuf + data_acked, left);
+		if(data_acked)
+			buffer_get(&c->sndbuf, NULL, data_acked);
 
 		c->snd.una = hdr.ack;
 
 		c->dupack = 0;
 		c->snd.cwnd += utcp->mtu;
-		if(c->snd.cwnd > c->maxsndbufsize)
-			c->snd.cwnd = c->maxsndbufsize;
+		if(c->snd.cwnd > c->sndbuf.maxsize)
+			c->snd.cwnd = c->sndbuf.maxsize;
 
 		// Check if we have sent a FIN that is now ACKed.
 		switch(c->state) {
@@ -670,10 +779,13 @@ 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;
 			}
 		}
 	}
@@ -761,7 +873,6 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 			rxd = c->recv(c, data, len);
 			if(rxd != len) {
 				// TODO: once we have a receive buffer, handle the application not accepting all data.
-				fprintf(stderr, "c->recv(%p, %p, %zu) returned %zd\n", c, data, len, rxd);
 				abort();
 			}
 			if(rxd < 0)
@@ -891,6 +1002,8 @@ 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;
 }
@@ -907,6 +1020,8 @@ int utcp_abort(struct utcp_connection *c) {
 		return -1;
 	}
 
+	c->recv = NULL;
+	c->poll = NULL;
 	c->reapable = true;
 
 	switch(c->state) {
@@ -945,74 +1060,13 @@ 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[c->utcp->mtu];
-	} pkt;
-
-	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;
-			}
-			memcpy(pkt.data, c->sndbuf, len);
-			print_packet(c->utcp, "rtrx", &pkt, sizeof pkt.hdr + len);
-			utcp->send(utcp, &pkt, sizeof pkt.hdr + len);
-			break;
-
-		default:
-			// TODO: implement
-			abort();
-	}
-}
-
 /* 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};
@@ -1043,8 +1097,8 @@ int utcp_timeout(struct utcp *utcp) {
 			retransmit(c);
 		}
 
-		if(c->poll && c->sndbufsize < c->maxsndbufsize / 2)
-			c->poll(c, c->maxsndbufsize - c->sndbufsize);
+		if(c->poll && buffer_free(&c->sndbuf) && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
+			c->poll(c, buffer_free(&c->sndbuf));
 
 		if(timerisset(&c->conn_timeout) && timercmp(&c->conn_timeout, &next, <))
 			next = c->conn_timeout;
@@ -1062,9 +1116,7 @@ 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) {
@@ -1093,7 +1145,7 @@ void utcp_exit(struct utcp *utcp) {
 	for(int i = 0; i < utcp->nconnections; i++) {
 		if(!utcp->connections[i]->reapable)
 			debug("Warning, freeing unclosed connection %p\n", utcp->connections[i]);
-		free(utcp->connections[i]->sndbuf);
+		buffer_exit(&utcp->connections[i]->sndbuf);
 		free(utcp->connections[i]);
 	}
 	free(utcp->connections);
@@ -1118,17 +1170,17 @@ void utcp_set_user_timeout(struct utcp *u, int timeout) {
 }
 
 size_t utcp_get_sndbuf(struct utcp_connection *c) {
-	return c->maxsndbufsize;
+	return c->sndbuf.maxsize;
 }
 
 size_t utcp_get_sndbuf_free(struct utcp_connection *c) {
-	return c->maxsndbufsize - c->sndbufsize;
+	return buffer_free(&c->sndbuf);
 }
 
 void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
-	c->maxsndbufsize = size;
-	if(c->maxsndbufsize != size)
-		c->maxsndbufsize = -1;
+	c->sndbuf.maxsize = size;
+	if(c->sndbuf.maxsize != size)
+		c->sndbuf.maxsize = -1;
 }
 
 bool utcp_get_nodelay(struct utcp_connection *c) {