} while (0)
#endif
+#ifndef max
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
#ifdef UTCP_DEBUG
#include <stdarg.h>
return NULL;
}
+ if(!buffer_init(&c->rcvbuf, DEFAULT_RCVBUFSIZE, DEFAULT_MAXRCVBUFSIZE)) {
+ free(c);
+ return NULL;
+ }
+
// Fill in the details
c->src = src;
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);
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);
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) {
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;
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;
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;
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;
}
}
}
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:
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;
}
projects / utcp / blobdiff