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;
}
// 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);
+ } else {
+ return 0;
+ }
if(len <= 0) {
- errno = EWOULDBLOCK;
- return 0;
+ if(is_reliable(c)) {
+ errno = EWOULDBLOCK;
+ return 0;
+ } else {
+ return len;
+ }
}
c->snd.last += 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);
c->flags = UTCP_TCP;
}
+synack:
// Return SYN+ACK, go to SYN_RECEIVED state
c->snd.wnd = hdr.wnd;
c->rcv.irs = hdr.seq;
// 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.
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
// 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);
// 3. Advance snd.una
advanced = seqdiff(hdr.ack, c->snd.una);
- prevrcvnxt = c->rcv.nxt;
if(advanced) {
// RTT measurement
assert(data_acked >= 0);
+#ifndef NDEBUG
int32_t bufused = seqdiff(c->snd.last, c->snd.una);
assert(data_acked <= bufused);
+#endif
if(data_acked) {
buffer_get(&c->sndbuf, NULL, data_acked);
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);
}
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:
// 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:
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;
}
// 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:
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;
}
}
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;
}
}
projects / utcp / blobdiff