c->snd.una = c->snd.iss;
c->snd.nxt = c->snd.iss + 1;
c->snd.last = c->snd.nxt;
- c->snd.cwnd = (utcp->mtu > 2190 ? 2 : utcp->mtu > 1095 ? 3 : 4) * utcp->mtu;
+ c->snd.cwnd = (utcp->mss > 2190 ? 2 : utcp->mss > 1095 ? 3 : 4) * utcp->mss;
c->snd.ssthresh = ~0;
debug_cwnd(c);
c->utcp = utcp;
} else if(cwndleft < left) {
left = cwndleft;
- if(!sendatleastone || cwndleft > c->utcp->mtu) {
- left -= left % c->utcp->mtu;
+ if(!sendatleastone || cwndleft > c->utcp->mss) {
+ left -= left % c->utcp->mss;
}
}
uint8_t data[];
} *pkt;
- pkt = malloc(sizeof(pkt->hdr) + c->utcp->mtu);
+ pkt = malloc(c->utcp->mtu);
if(!pkt) {
return;
pkt->hdr.aux = 0;
do {
- uint32_t seglen = left > c->utcp->mtu ? c->utcp->mtu : left;
+ uint32_t seglen = left > c->utcp->mss ? c->utcp->mss : left;
pkt->hdr.seq = c->snd.nxt;
buffer_copy(&c->sndbuf, pkt->data, seqdiff(c->snd.nxt, c->snd.una), seglen);
uint8_t data[];
} *pkt;
- pkt = malloc(sizeof(pkt->hdr) + c->utcp->mtu);
+ pkt = malloc(c->utcp->mtu);
if(!pkt) {
return;
pkt->hdr.seq = c->snd.una;
pkt->hdr.ack = c->rcv.nxt;
pkt->hdr.ctl = ACK;
- uint32_t len = min(seqdiff(c->snd.last, c->snd.una), utcp->mtu);
+ uint32_t len = min(seqdiff(c->snd.last, c->snd.una), utcp->mss);
if(fin_wanted(c, c->snd.una + len)) {
len--;
uint8_t data[];
} *pkt;
- pkt = malloc(sizeof(pkt->hdr) + c->utcp->mtu);
+ pkt = malloc(c->utcp->mtu);
if(!pkt) {
return;
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;
- }
+ uint32_t len = min(seqdiff(c->snd.last, c->snd.una), utcp->mss);
if(fin_wanted(c, c->snd.una + len)) {
len--;
pkt->hdr.ctl |= FIN;
}
- c->snd.nxt = c->snd.una + len;
-
// RFC 5681 slow start after timeout
- c->snd.ssthresh = max(c->snd.cwnd / 2, utcp->mtu * 2); // eq. 4
- c->snd.cwnd = utcp->mtu;
+ uint32_t flightsize = seqdiff(c->snd.nxt, c->snd.una);
+ c->snd.ssthresh = max(flightsize / 2, utcp->mss * 2); // eq. 4
+ c->snd.cwnd = utcp->mss;
debug_cwnd(c);
buffer_copy(&c->sndbuf, pkt->data, 0, len);
print_packet(c, "rtrx", pkt, sizeof(pkt->hdr) + len);
utcp->send(utcp, pkt, sizeof(pkt->hdr) + len);
+
+ c->snd.nxt = c->snd.una + len;
break;
case CLOSED:
}
c->rtt_start.tv_sec = 0; // invalidate RTT timer
+ c->dupack = 0; // cancel any ongoing fast recovery
cleanup:
free(pkt);
// Otherwise, continue processing.
len = 0;
}
+ } else {
+#if UTCP_DEBUG
+ int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
+
+ if(rcv_offset) {
+ debug(c, "packet out of order, offset %u bytes", rcv_offset);
+ }
+
+ if(rcv_offset >= 0) {
+ c->rcv.nxt = hdr.seq + len;
+ }
+
+#endif
}
c->snd.wnd = hdr.wnd; // TODO: move below
// Increase the congestion window according to RFC 5681
if(c->snd.cwnd < c->snd.ssthresh) {
- c->snd.cwnd += min(advanced, utcp->mtu); // eq. 2
+ c->snd.cwnd += min(advanced, utcp->mss); // eq. 2
} else {
- c->snd.cwnd += max(1, (utcp->mtu * utcp->mtu) / c->snd.cwnd); // eq. 3
+ c->snd.cwnd += max(1, (utcp->mss * utcp->mss) / c->snd.cwnd); // eq. 3
}
if(c->snd.cwnd > c->sndbuf.maxsize) {
break;
}
} else {
- if(!len && is_reliable(c)) {
+ if(!len && is_reliable(c) && c->snd.una != c->snd.last) {
c->dupack++;
debug(c, "duplicate ACK %d\n", c->dupack);
if(c->dupack == 3) {
// RFC 5681 fast recovery
debug(c, "fast recovery started\n", c->dupack);
- c->snd.ssthresh = max(c->snd.cwnd / 2, utcp->mtu * 2); // eq. 4
- c->snd.cwnd = min(c->snd.ssthresh + 3 * utcp->mtu, c->sndbuf.maxsize);
+ uint32_t flightsize = seqdiff(c->snd.nxt, c->snd.una);
+ c->snd.ssthresh = max(flightsize / 2, utcp->mss * 2); // eq. 4
+ c->snd.cwnd = min(c->snd.ssthresh + 3 * utcp->mss, c->sndbuf.maxsize);
if(c->snd.cwnd > c->sndbuf.maxsize) {
c->snd.cwnd = c->sndbuf.maxsize;
fast_retransmit(c);
} else if(c->dupack > 3) {
- c->snd.cwnd += utcp->mtu;
+ c->snd.cwnd += utcp->mss;
if(c->snd.cwnd > c->sndbuf.maxsize) {
c->snd.cwnd = c->sndbuf.maxsize;
debug_cwnd(c);
}
+
+ // We got an ACK which indicates the other side did get one of our packets.
+ // Reset the retransmission timer to avoid going to slow start,
+ // but don't touch the connection timeout.
+ start_retransmit_timer(c);
}
}
utcp->send = send;
utcp->priv = priv;
utcp->mtu = DEFAULT_MTU;
+ utcp->mss = DEFAULT_MTU - sizeof(struct hdr);
utcp->timeout = DEFAULT_USER_TIMEOUT; // sec
utcp->rto = START_RTO; // usec
// TODO: handle overhead of the header
if(utcp) {
utcp->mtu = mtu;
+ utcp->mss = mtu - sizeof(struct hdr);
}
}