X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=utcp.c;h=ad19982ba95afdb613eb780e6ac8d8eff6511ee3;hb=7d8a65c11dd4b0555575ff75efab859236c4964f;hp=e6f6cf9ede28360df84fad0161b0a993e01a3c0f;hpb=ea89f59bebc6529e3270eebcc86825ee1eb7055e;p=utcp

diff --git a/utcp.c b/utcp.c
index e6f6cf9..ad19982 100644
--- a/utcp.c
+++ b/utcp.c
@@ -53,6 +53,10 @@
 } while (0)
 #endif
 
+#ifndef max
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
 #ifdef UTCP_DEBUG
 #include <stdarg.h>
 
@@ -197,9 +201,11 @@ static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t
 
 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;
+	if(len) {
+		buf->data = malloc(len);
+		if(!buf->data)
+			return false;
+	}
 	buf->size = len;
 	buf->maxsize = maxlen;
 	return true;
@@ -298,6 +304,11 @@ static struct utcp_connection *allocate_connection(struct utcp *utcp, uint16_t s
 		return NULL;
 	}
 
+	if(!buffer_init(&c->rcvbuf, DEFAULT_RCVBUFSIZE, DEFAULT_MAXRCVBUFSIZE)) {
+		free(c);
+		return NULL;
+	}
+
 	// Fill in the details
 
 	c->src = src;
@@ -367,6 +378,7 @@ 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);
+	debug("cwndleft = %d\n", cwndleft);
 
 	assert(left >= 0);
 
@@ -526,6 +538,7 @@ static void retransmit(struct utcp_connection *c) {
 				pkt->hdr.ctl |= FIN;
 			}
 			c->snd.nxt = c->snd.una + len;
+			c->snd.cwnd = utcp->mtu; // reduce cwnd on retransmit
 			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);
@@ -546,6 +559,114 @@ static void retransmit(struct utcp_connection *c) {
 	free(pkt);
 }
 
+// Update receive buffer and SACK entries after consuming data.
+static void sack_consume(struct utcp_connection *c, size_t len) {
+	debug("sack_consume %zu\n", len);
+	if(len > c->rcvbuf.used)
+		abort();
+
+	buffer_get(&c->rcvbuf, NULL, len);
+
+	for(int i = 0; i < NSACKS && c->sacks[i].len; ) {
+		if(len < c->sacks[i].offset) {
+			c->sacks[i].offset -= len;
+			i++;
+		} else if(len < c->sacks[i].offset + c->sacks[i].len) {
+			c->sacks[i].offset = 0;
+			c->sacks[i].len -= len - c->sacks[i].offset;
+			i++;
+		} else {
+			if(i < NSACKS - 1) {
+				memmove(&c->sacks[i], &c->sacks[i + 1], (NSACKS - 1 - i) * sizeof c->sacks[i]);
+				c->sacks[i + 1].len = 0;
+			} else {
+				c->sacks[i].len = 0;
+				break;
+			}
+		}
+	}
+
+	for(int i = 0; i < NSACKS && c->sacks[i].len; i++)
+		debug("SACK[%d] offset %u len %u\n", i, c->sacks[i].offset, c->sacks[i].len);
+}
+
+static void handle_out_of_order(struct utcp_connection *c, uint32_t offset, const void *data, size_t len) {
+	debug("out of order packet, offset %u\n", offset);
+	// Packet loss or reordering occured. Store the data in the buffer.
+	ssize_t rxd = buffer_put_at(&c->rcvbuf, offset, data, len);
+	if(rxd < len)
+		abort();
+
+	// Make note of where we put it.
+	for(int i = 0; i < NSACKS; i++) {
+		if(!c->sacks[i].len) { // nothing to merge, add new entry
+			debug("New SACK entry %d\n", i);
+			c->sacks[i].offset = offset;
+			c->sacks[i].len = rxd;
+			break;
+		} else if(offset < c->sacks[i].offset) {
+			if(offset + rxd < c->sacks[i].offset) { // insert before
+				if(!c->sacks[NSACKS - 1].len) { // only if room left
+					debug("Insert SACK entry at %d\n", i);
+					memmove(&c->sacks[i + 1], &c->sacks[i], (NSACKS - i - 1) * sizeof c->sacks[i]);
+					c->sacks[i].offset = offset;
+					c->sacks[i].len = rxd;
+				}
+				break;
+			} else { // merge
+				debug("Merge with start of SACK entry at %d\n", i);
+				c->sacks[i].offset = offset;
+				break;
+			}
+		} else if(offset <= c->sacks[i].offset + c->sacks[i].len) {
+			if(offset + rxd > c->sacks[i].offset + c->sacks[i].len) { // merge
+				debug("Merge with end of SACK entry at %d\n", i);
+				c->sacks[i].len = offset + rxd - c->sacks[i].offset;
+				// TODO: handle potential merge with next entry
+			}
+			break;
+		}
+	}
+
+	for(int i = 0; i < NSACKS && c->sacks[i].len; i++)
+		debug("SACK[%d] offset %u len %u\n", i, c->sacks[i].offset, c->sacks[i].len);
+}
+
+static void handle_in_order(struct utcp_connection *c, const void *data, size_t len) {
+	// Check if we can process out-of-order data now.
+	if(c->sacks[0].len && len >= c->sacks[0].offset) { // TODO: handle overlap with second SACK
+		debug("incoming packet len %zu connected with SACK at %u\n", len, c->sacks[0].offset);
+		buffer_put_at(&c->rcvbuf, 0, data, len); // TODO: handle return value
+		len = max(len, c->sacks[0].offset + c->sacks[0].len);
+		data = c->rcvbuf.data;
+	}
+
+	if(c->recv) {
+		ssize_t rxd = c->recv(c, data, len);
+		if(rxd != len) {
+			// TODO: handle the application not accepting all data.
+			abort();
+		}
+	}
+
+	if(c->rcvbuf.used)
+		sack_consume(c, len);
+
+	c->rcv.nxt += len;
+}
+
+
+static void handle_incoming_data(struct utcp_connection *c, uint32_t seq, const void *data, size_t len) {
+	uint32_t offset = seqdiff(seq, c->rcv.nxt);
+	if(offset + len > c->rcvbuf.maxsize)
+		abort();
+
+	if(offset)
+		handle_out_of_order(c, offset, data, len);
+	else
+		handle_in_order(c, data, len);
+}
+
 
 ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	if(!utcp) {
@@ -676,28 +797,19 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		acceptable = true;
 
 	// TODO: handle packets overlapping c->rcv.nxt.
-#if 0
+#if 1
 	// Only use this when accepting out-of-order packets.
 	else if(len == 0)
-		if(c->rcv.wnd == 0)
-			acceptable = hdr.seq == c->rcv.nxt;
-		else
-			acceptable = (seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt + c->rcv.wnd) < 0);
+		acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0;
 	else
-		if(c->rcv.wnd == 0)
-			// We don't accept data when the receive window is zero.
-			acceptable = false;
-		else
-			// Both start and end of packet must be within the receive window
-			acceptable = (seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt + c->rcv.wnd) < 0)
-				|| (seqdiff(hdr.seq + len + 1, c->rcv.nxt) >= 0 && seqdiff(hdr.seq + len - 1, c->rcv.nxt + c->rcv.wnd) < 0);
+		acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
 #else
 	if(c->state != SYN_SENT)
 		acceptable = hdr.seq == c->rcv.nxt;
 #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->rcvbuf.maxsize);
 		// Ignore unacceptable RST packets.
 		if(hdr.ctl & RST)
 			return 0;
@@ -709,10 +821,14 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 	c->snd.wnd = hdr.wnd; // TODO: move below
 
 	// 1c. Drop packets with an invalid ACK.
-	// ackno should not roll back, and it should also not be bigger than snd.nxt.
-
-	if(hdr.ctl & ACK && (seqdiff(hdr.ack, c->snd.nxt) > 0 || seqdiff(hdr.ack, c->snd.una) < 0)) {
-		debug("Packet ack seqno out of range, %u %u %u\n", hdr.ack, c->snd.una, c->snd.nxt);
+	// 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(hdr.ctl & ACK &&
+			((seqdiff(hdr.ack, c->snd.una + c->sndbuf.used) > 0 &&
+			  seqdiff(hdr.ack, c->snd.nxt) > 0) // TODO: simplify this if
+			 || 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);
 		// Ignore unacceptable RST packets.
 		if(hdr.ctl & RST)
 			return 0;
@@ -798,6 +914,10 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 		if(data_acked)
 			buffer_get(&c->sndbuf, NULL, data_acked);
 
+		// Also advance snd.nxt if possible
+		if(seqdiff(c->snd.nxt, hdr.ack) < 0)
+			c->snd.nxt = hdr.ack;
+
 		c->snd.una = hdr.ack;
 
 		c->dupack = 0;
@@ -828,9 +948,9 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 				debug("Triplicate ACK\n");
 				//TODO: Resend one packet and go to fast recovery mode. See RFC 6582.
 				//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.
+				//Reset the congestion window so we wait for ACKs.
 				c->snd.nxt = c->snd.una;
+				c->snd.cwnd = utcp->mtu;
 			}
 		}
 	}
@@ -921,28 +1041,12 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 			return 0;
 		}
 
-		ssize_t rxd;
-
-		if(c->recv) {
-			rxd = c->recv(c, data, len);
-			if(rxd != len) {
-				// TODO: once we have a receive buffer, handle the application not accepting all data.
-				abort();
-			}
-			if(rxd < 0)
-				rxd = 0;
-			else if(rxd > len)
-				rxd = len; // Bad application, bad!
-		} else {
-			rxd = len;
-		}
-
-		c->rcv.nxt += len;
+		handle_incoming_data(c, hdr.seq, data, len);
 	}
 
 	// 7. Process FIN stuff
 
-	if(hdr.ctl & FIN) {
+	if((hdr.ctl & FIN) && hdr.seq + len == c->rcv.nxt) {
 		switch(c->state) {
 		case SYN_SENT:
 		case SYN_RECEIVED:
@@ -1205,15 +1309,15 @@ bool utcp_is_active(struct utcp *utcp) {
 }
 
 struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_send_t send, void *priv) {
-	struct utcp *utcp = calloc(1, sizeof *utcp);
-	if(!utcp)
-		return NULL;
-
 	if(!send) {
 		errno = EFAULT;
 		return NULL;
 	}
 
+	struct utcp *utcp = calloc(1, sizeof *utcp);
+	if(!utcp)
+		return NULL;
+
 	utcp->accept = accept;
 	utcp->pre_accept = pre_accept;
 	utcp->send = send;
@@ -1275,6 +1379,25 @@ void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
 		c->sndbuf.maxsize = -1;
 }
 
+size_t utcp_get_rcvbuf(struct utcp_connection *c) {
+	return c ? c->rcvbuf.maxsize : 0;
+}
+
+size_t utcp_get_rcvbuf_free(struct utcp_connection *c) {
+	if(c && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
+		return buffer_free(&c->rcvbuf);
+	else
+		return 0;
+}
+
+void utcp_set_rcvbuf(struct utcp_connection *c, size_t size) {
+	if(!c)
+		return;
+	c->rcvbuf.maxsize = size;
+	if(c->rcvbuf.maxsize != size)
+		c->rcvbuf.maxsize = -1;
+}
+
 bool utcp_get_nodelay(struct utcp_connection *c) {
 	return c ? c->nodelay : false;
 }