debug("ACK");
if(len > sizeof hdr) {
- debug(" data=");
- for(int i = sizeof hdr; i < len; i++) {
- const char *data = pkt;
- debug("%c", data[i] >= 32 ? data[i] : '.');
+ uint32_t datalen = len - sizeof hdr;
+ uint8_t *str = malloc((datalen << 1) + 7);
+ memcpy(str, " data=", 6);
+ uint8_t *strptr = str + 6;
+ const uint8_t *data = pkt;
+ const uint8_t *dataend = data + datalen;
+
+ while(data != dataend) {
+ *strptr = (*data >> 4) > 9? (*data >> 4) + 55 : (*data >> 4) + 48;
+ ++strptr;
+ *strptr = (*data & 0xf) > 9? (*data & 0xf) + 55 : (*data & 0xf) + 48;
+ ++strptr;
+ ++data;
}
+ *strptr = 0;
+
+ debug(str);
+ free(str);
}
debug("\n");
memmove(cp, cp + 1, (utcp->nconnections - i - 1) * sizeof *cp);
utcp->nconnections--;
+ buffer_exit(&c->rcvbuf);
buffer_exit(&c->sndbuf);
free(c);
}
}
if(!buffer_init(&c->rcvbuf, DEFAULT_RCVBUFSIZE, DEFAULT_MAXRCVBUFSIZE)) {
+ buffer_exit(&c->sndbuf);
free(c);
return NULL;
}
return c;
}
+// Update RTT variables. See RFC 6298.
+static void update_rtt(struct utcp_connection *c, uint32_t rtt) {
+ if(!rtt) {
+ debug("invalid rtt\n");
+ return;
+ }
+
+ struct utcp *utcp = c->utcp;
+
+ if(!utcp->srtt) {
+ utcp->srtt = rtt;
+ utcp->rttvar = rtt / 2;
+ utcp->rto = rtt + max(2 * rtt, CLOCK_GRANULARITY);
+ } else {
+ utcp->rttvar = (utcp->rttvar * 3 + abs(utcp->srtt - rtt)) / 4;
+ utcp->srtt = (utcp->srtt * 7 + rtt) / 8;
+ utcp->rto = utcp->srtt + max(utcp->rttvar, CLOCK_GRANULARITY);
+ }
+
+ if(utcp->rto > MAX_RTO)
+ utcp->rto = MAX_RTO;
+
+ debug("rtt %u srtt %u rttvar %u rto %u\n", rtt, utcp->srtt, utcp->rttvar, utcp->rto);
+}
+
+static void start_retransmit_timer(struct utcp_connection *c) {
+ gettimeofday(&c->rtrx_timeout, NULL);
+ c->rtrx_timeout.tv_usec += c->utcp->rto;
+ while(c->rtrx_timeout.tv_usec >= 1000000) {
+ c->rtrx_timeout.tv_usec -= 1000000;
+ c->rtrx_timeout.tv_sec++;
+ }
+ debug("timeout set to %lu.%06lu (%u)\n", c->rtrx_timeout.tv_sec, c->rtrx_timeout.tv_usec, c->utcp->rto);
+}
+
+static void stop_retransmit_timer(struct utcp_connection *c) {
+ timerclear(&c->rtrx_timeout);
+ debug("timeout cleared\n");
+}
+
struct utcp_connection *utcp_connect(struct utcp *utcp, uint16_t dst, utcp_recv_t recv, void *priv) {
struct utcp_connection *c = allocate_connection(utcp, 0, dst);
if(!c)
pkt->hdr.ctl |= FIN;
}
+ if(!c->rtt_start.tv_sec) {
+ // Start RTT measurement
+ gettimeofday(&c->rtt_start, NULL);
+ c->rtt_seq = pkt->hdr.seq + seglen;
+ debug("Starting RTT measurement, expecting ack %u\n", c->rtt_seq);
+ }
+
print_packet(c->utcp, "send", pkt, sizeof pkt->hdr + seglen);
c->utcp->send(c->utcp, pkt, sizeof pkt->hdr + seglen);
} while(left);
c->snd.last += len;
ack(c, false);
+ if(!timerisset(&c->rtrx_timeout))
+ start_retransmit_timer(c);
return len;
}
pkt->hdr.src = c->src;
pkt->hdr.dst = c->dst;
+ pkt->hdr.wnd = c->rcv.wnd;
+ pkt->hdr.aux = 0;
switch(c->state) {
case SYN_SENT:
// Send our SYN again
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);
#ifdef UTCP_DEBUG
abort();
#endif
- timerclear(&c->rtrx_timeout);
- break;
+ stop_retransmit_timer(c);
+ goto cleanup;
}
+ start_retransmit_timer(c);
+ utcp->rto *= 2;
+ if(utcp->rto > MAX_RTO)
+ utcp->rto = MAX_RTO;
+ c->rtt_start.tv_sec = 0; // invalidate RTT timer
+
+cleanup:
free(pkt);
}
if(c->state == SYN_SENT)
acceptable = true;
-
- // TODO: handle packets overlapping c->rcv.nxt.
-#if 1
- // Only use this when accepting out-of-order packets.
else if(len == 0)
acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0;
- else
+ else {
+ int32_t rcv_offset = seqdiff(hdr.seq, c->rcv.nxt);
+
+ // cut already accepted front overlapping
+ if(rcv_offset < 0) {
+ acceptable = rcv_offset + len >= 0;
+ if(acceptable) {
+ data -= rcv_offset;
+ len += rcv_offset;
+ }
+ }
+
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->rcvbuf.maxsize);
// 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)) {
+ 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);
// Ignore unacceptable RST packets.
if(hdr.ctl & RST)
prevrcvnxt = c->rcv.nxt;
if(advanced) {
+ // RTT measurement
+ if(c->rtt_start.tv_sec) {
+ if(c->rtt_seq == hdr.ack) {
+ struct timeval now, diff;
+ gettimeofday(&now, NULL);
+ timersub(&now, &c->rtt_start, &diff);
+ update_rtt(c, diff.tv_sec * 1000000 + diff.tv_usec);
+ c->rtt_start.tv_sec = 0;
+ } else if(c->rtt_seq < hdr.ack) {
+ debug("Cancelling RTT measurement: %u < %u\n", c->rtt_seq, hdr.ack);
+ c->rtt_start.tv_sec = 0;
+ }
+ }
+
int32_t data_acked = advanced;
switch(c->state) {
//Reset the congestion window so we wait for ACKs.
c->snd.nxt = c->snd.una;
c->snd.cwnd = utcp->mtu;
+ start_retransmit_timer(c);
}
}
}
if(advanced) {
timerclear(&c->conn_timeout); // It will be set anew in utcp_timeout() if c->snd.una != c->snd.nxt.
- if(c->snd.una == c->snd.nxt)
- timerclear(&c->rtrx_timeout);
+ if(c->snd.una == c->snd.last)
+ stop_retransmit_timer(c);
+ else
+ start_retransmit_timer(c);
}
// 5. Process SYN stuff
// - or we got an ack, so we should maybe send a bit more data
// -> sendatleastone = false
-ack:
- ack(c, prevrcvnxt != c->rcv.nxt);
+ ack(c, len || prevrcvnxt != c->rcv.nxt);
return 0;
reset:
c->snd.last++;
ack(c, false);
+ if(!timerisset(&c->rtrx_timeout))
+ start_retransmit_timer(c);
return 0;
}
if(!c)
continue;
+ // delete connections that have been utcp_close()d.
if(c->state == CLOSED) {
if(c->reapable) {
debug("Reaping %p\n", c);
}
if(timerisset(&c->rtrx_timeout) && timercmp(&c->rtrx_timeout, &now, <)) {
+ debug("retransmit()\n");
retransmit(c);
}
if(timerisset(&c->conn_timeout) && timercmp(&c->conn_timeout, &next, <))
next = c->conn_timeout;
- if(c->snd.nxt != c->snd.una) {
- c->rtrx_timeout = now;
- c->rtrx_timeout.tv_sec++;
- } else {
- timerclear(&c->rtrx_timeout);
- }
-
if(timerisset(&c->rtrx_timeout) && timercmp(&c->rtrx_timeout, &next, <))
next = c->rtrx_timeout;
}
utcp->pre_accept = pre_accept;
utcp->send = send;
utcp->priv = priv;
- utcp->mtu = 1000;
- utcp->timeout = 60;
+ utcp->mtu = DEFAULT_MTU;
+ utcp->timeout = DEFAULT_USER_TIMEOUT; // s
+ utcp->rto = START_RTO; // us
return utcp;
}
for(int i = 0; i < utcp->nconnections; i++) {
if(!utcp->connections[i]->reapable)
debug("Warning, freeing unclosed connection %p\n", utcp->connections[i]);
+ buffer_exit(&utcp->connections[i]->rcvbuf);
buffer_exit(&utcp->connections[i]->sndbuf);
free(utcp->connections[i]);
}
projects / utcp / blobdiff