2 utcp.c -- Userspace TCP
3 Copyright (C) 2014 Guus Sliepen <guus@tinc-vpn.org>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
31 #include <sys/socket.h>
33 #include "utcp_priv.h"
48 #define timersub(a, b, r) do {\
49 (r)->tv_sec = (a)->tv_sec - (b)->tv_sec;\
50 (r)->tv_usec = (a)->tv_usec - (b)->tv_usec;\
52 (r)->tv_sec--, (r)->tv_usec += 1000000;\
57 #define max(a, b) ((a) > (b) ? (a) : (b))
63 static void debug(const char *format, ...) {
66 vfprintf(stderr, format, ap);
70 static void print_packet(struct utcp *utcp, const char *dir, const void *pkt, size_t len) {
72 if(len < sizeof hdr) {
73 debug("%p %s: short packet (%zu bytes)\n", utcp, dir, len);
77 memcpy(&hdr, pkt, sizeof hdr);
78 fprintf (stderr, "%p %s: len=%zu, src=%u dst=%u seq=%u ack=%u wnd=%u ctl=", utcp, dir, len, hdr.src, hdr.dst, hdr.seq, hdr.ack, hdr.wnd);
88 if(len > sizeof hdr) {
90 for(int i = sizeof hdr; i < len; i++) {
91 const char *data = pkt;
92 debug("%c", data[i] >= 32 ? data[i] : '.');
100 #define print_packet(...)
103 static void set_state(struct utcp_connection *c, enum state state) {
105 if(state == ESTABLISHED)
106 timerclear(&c->conn_timeout);
107 debug("%p new state: %s\n", c->utcp, strstate[state]);
110 static bool fin_wanted(struct utcp_connection *c, uint32_t seq) {
111 if(seq != c->snd.last)
123 static inline void list_connections(struct utcp *utcp) {
124 debug("%p has %d connections:\n", utcp, utcp->nconnections);
125 for(int i = 0; i < utcp->nconnections; i++)
126 debug(" %u -> %u state %s\n", utcp->connections[i]->src, utcp->connections[i]->dst, strstate[utcp->connections[i]->state]);
129 static int32_t seqdiff(uint32_t a, uint32_t b) {
134 // TODO: convert to ringbuffers to avoid memmove() operations.
136 // Store data into the buffer
137 static ssize_t buffer_put_at(struct buffer *buf, size_t offset, const void *data, size_t len) {
138 if(buf->maxsize <= buf->used)
141 debug("buffer_put_at %zu %zu %zu\n", buf->used, offset, len);
143 size_t required = offset + len;
144 if(required > buf->maxsize) {
145 if(offset >= buf->maxsize)
148 len = buf->maxsize - offset;
149 required = buf->maxsize;
152 if(required > buf->size) {
153 size_t newsize = buf->size;
159 } while(newsize < buf->used + len);
161 if(newsize > buf->maxsize)
162 newsize = buf->maxsize;
163 char *newdata = realloc(buf->data, newsize);
170 memcpy(buf->data + offset, data, len);
171 if(required > buf->used)
172 buf->used = required;
176 static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
177 return buffer_put_at(buf, buf->used, data, len);
180 // Get data from the buffer. data can be NULL.
181 static ssize_t buffer_get(struct buffer *buf, void *data, size_t len) {
185 memcpy(data, buf->data, len);
187 memmove(buf->data, buf->data + len, buf->used - len);
192 // Copy data from the buffer without removing it.
193 static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t len) {
194 if(offset >= buf->used)
196 if(offset + len > buf->used)
197 len = buf->used - offset;
198 memcpy(data, buf->data + offset, len);
202 static bool buffer_init(struct buffer *buf, uint32_t len, uint32_t maxlen) {
203 memset(buf, 0, sizeof *buf);
205 buf->data = malloc(len);
210 buf->maxsize = maxlen;
214 static void buffer_exit(struct buffer *buf) {
216 memset(buf, 0, sizeof *buf);
219 static uint32_t buffer_free(const struct buffer *buf) {
220 return buf->maxsize - buf->used;
223 // Connections are stored in a sorted list.
224 // This gives O(log(N)) lookup time, O(N log(N)) insertion time and O(N) deletion time.
226 static int compare(const void *va, const void *vb) {
229 const struct utcp_connection *a = *(struct utcp_connection **)va;
230 const struct utcp_connection *b = *(struct utcp_connection **)vb;
233 assert(a->src && b->src);
235 int c = (int)a->src - (int)b->src;
238 c = (int)a->dst - (int)b->dst;
242 static struct utcp_connection *find_connection(const struct utcp *utcp, uint16_t src, uint16_t dst) {
243 if(!utcp->nconnections)
245 struct utcp_connection key = {
249 struct utcp_connection **match = bsearch(&keyp, utcp->connections, utcp->nconnections, sizeof *utcp->connections, compare);
250 return match ? *match : NULL;
253 static void free_connection(struct utcp_connection *c) {
254 struct utcp *utcp = c->utcp;
255 struct utcp_connection **cp = bsearch(&c, utcp->connections, utcp->nconnections, sizeof *utcp->connections, compare);
259 int i = cp - utcp->connections;
260 memmove(cp, cp + 1, (utcp->nconnections - i - 1) * sizeof *cp);
261 utcp->nconnections--;
263 buffer_exit(&c->sndbuf);
267 static struct utcp_connection *allocate_connection(struct utcp *utcp, uint16_t src, uint16_t dst) {
268 // Check whether this combination of src and dst is free
271 if(find_connection(utcp, src, dst)) {
275 } else { // If src == 0, generate a random port number with the high bit set
276 if(utcp->nconnections >= 32767) {
280 src = rand() | 0x8000;
281 while(find_connection(utcp, src, dst))
285 // Allocate memory for the new connection
287 if(utcp->nconnections >= utcp->nallocated) {
288 if(!utcp->nallocated)
289 utcp->nallocated = 4;
291 utcp->nallocated *= 2;
292 struct utcp_connection **new_array = realloc(utcp->connections, utcp->nallocated * sizeof *utcp->connections);
295 utcp->connections = new_array;
298 struct utcp_connection *c = calloc(1, sizeof *c);
302 if(!buffer_init(&c->sndbuf, DEFAULT_SNDBUFSIZE, DEFAULT_MAXSNDBUFSIZE)) {
307 if(!buffer_init(&c->rcvbuf, DEFAULT_RCVBUFSIZE, DEFAULT_MAXRCVBUFSIZE)) {
312 // Fill in the details
321 c->snd.una = c->snd.iss;
322 c->snd.nxt = c->snd.iss + 1;
323 c->rcv.wnd = utcp->mtu;
324 c->snd.last = c->snd.nxt;
325 c->snd.cwnd = utcp->mtu;
328 // Add it to the sorted list of connections
330 utcp->connections[utcp->nconnections++] = c;
331 qsort(utcp->connections, utcp->nconnections, sizeof *utcp->connections, compare);
336 struct utcp_connection *utcp_connect(struct utcp *utcp, uint16_t dst, utcp_recv_t recv, void *priv) {
337 struct utcp_connection *c = allocate_connection(utcp, 0, dst);
348 hdr.seq = c->snd.iss;
350 hdr.wnd = c->rcv.wnd;
354 set_state(c, SYN_SENT);
356 print_packet(utcp, "send", &hdr, sizeof hdr);
357 utcp->send(utcp, &hdr, sizeof hdr);
359 gettimeofday(&c->conn_timeout, NULL);
360 c->conn_timeout.tv_sec += utcp->timeout;
365 void utcp_accept(struct utcp_connection *c, utcp_recv_t recv, void *priv) {
366 if(c->reapable || c->state != SYN_RECEIVED) {
367 debug("Error: accept() called on invalid connection %p in state %s\n", c, strstate[c->state]);
371 debug("%p accepted, %p %p\n", c, recv, priv);
374 set_state(c, ESTABLISHED);
377 static void ack(struct utcp_connection *c, bool sendatleastone) {
378 int32_t left = seqdiff(c->snd.last, c->snd.nxt);
379 int32_t cwndleft = c->snd.cwnd - seqdiff(c->snd.nxt, c->snd.una);
380 debug("cwndleft = %d\n", cwndleft);
390 if(!left && !sendatleastone)
398 pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
402 pkt->hdr.src = c->src;
403 pkt->hdr.dst = c->dst;
404 pkt->hdr.ack = c->rcv.nxt;
405 pkt->hdr.wnd = c->snd.wnd;
410 uint32_t seglen = left > c->utcp->mtu ? c->utcp->mtu : left;
411 pkt->hdr.seq = c->snd.nxt;
413 buffer_copy(&c->sndbuf, pkt->data, seqdiff(c->snd.nxt, c->snd.una), seglen);
415 c->snd.nxt += seglen;
418 if(seglen && fin_wanted(c, c->snd.nxt)) {
423 print_packet(c->utcp, "send", pkt, sizeof pkt->hdr + seglen);
424 c->utcp->send(c->utcp, pkt, sizeof pkt->hdr + seglen);
430 ssize_t utcp_send(struct utcp_connection *c, const void *data, size_t len) {
432 debug("Error: send() called on closed connection %p\n", c);
442 debug("Error: send() called on unconnected connection %p\n", c);
453 debug("Error: send() called on closing connection %p\n", c);
458 // Add data to send buffer
468 len = buffer_put(&c->sndbuf, data, len);
479 static void swap_ports(struct hdr *hdr) {
480 uint16_t tmp = hdr->src;
485 static void retransmit(struct utcp_connection *c) {
486 if(c->state == CLOSED || c->snd.nxt == c->snd.una)
489 struct utcp *utcp = c->utcp;
496 pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
500 pkt->hdr.src = c->src;
501 pkt->hdr.dst = c->dst;
505 // Send our SYN again
506 pkt->hdr.seq = c->snd.iss;
508 pkt->hdr.wnd = c->rcv.wnd;
510 print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
511 utcp->send(utcp, pkt, sizeof pkt->hdr);
516 pkt->hdr.seq = c->snd.nxt;
517 pkt->hdr.ack = c->rcv.nxt;
518 pkt->hdr.ctl = SYN | ACK;
519 print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr);
520 utcp->send(utcp, pkt, sizeof pkt->hdr);
528 // Send unacked data again.
529 pkt->hdr.seq = c->snd.una;
530 pkt->hdr.ack = c->rcv.nxt;
532 uint32_t len = seqdiff(c->snd.last, c->snd.una);
535 if(fin_wanted(c, c->snd.una + len)) {
539 c->snd.nxt = c->snd.una + len;
540 c->snd.cwnd = utcp->mtu; // reduce cwnd on retransmit
541 buffer_copy(&c->sndbuf, pkt->data, 0, len);
542 print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr + len);
543 utcp->send(utcp, pkt, sizeof pkt->hdr + len);
550 // We shouldn't need to retransmit anything in this state.
554 timerclear(&c->rtrx_timeout);
561 // Update receive buffer and SACK entries after consuming data.
562 static void sack_consume(struct utcp_connection *c, size_t len) {
563 debug("sack_consume %zu\n", len);
564 if(len > c->rcvbuf.used)
567 buffer_get(&c->rcvbuf, NULL, len);
569 for(int i = 0; i < NSACKS && c->sacks[i].len; ) {
570 if(len < c->sacks[i].offset) {
571 c->sacks[i].offset -= len;
573 } else if(len < c->sacks[i].offset + c->sacks[i].len) {
574 c->sacks[i].offset = 0;
575 c->sacks[i].len -= len - c->sacks[i].offset;
579 memmove(&c->sacks[i], &c->sacks[i + 1], (NSACKS - 1 - i) * sizeof c->sacks[i]);
580 c->sacks[i + 1].len = 0;
588 for(int i = 0; i < NSACKS && c->sacks[i].len; i++)
589 debug("SACK[%d] offset %u len %u\n", i, c->sacks[i].offset, c->sacks[i].len);
592 static void handle_out_of_order(struct utcp_connection *c, uint32_t offset, const void *data, size_t len) {
593 debug("out of order packet, offset %u\n", offset);
594 // Packet loss or reordering occured. Store the data in the buffer.
595 ssize_t rxd = buffer_put_at(&c->rcvbuf, offset, data, len);
599 // Make note of where we put it.
600 for(int i = 0; i < NSACKS; i++) {
601 if(!c->sacks[i].len) { // nothing to merge, add new entry
602 debug("New SACK entry %d\n", i);
603 c->sacks[i].offset = offset;
604 c->sacks[i].len = rxd;
606 } else if(offset < c->sacks[i].offset) {
607 if(offset + rxd < c->sacks[i].offset) { // insert before
608 if(!c->sacks[NSACKS - 1].len) { // only if room left
609 debug("Insert SACK entry at %d\n", i);
610 memmove(&c->sacks[i + 1], &c->sacks[i], (NSACKS - i - 1) * sizeof c->sacks[i]);
611 c->sacks[i].offset = offset;
612 c->sacks[i].len = rxd;
616 debug("Merge with start of SACK entry at %d\n", i);
617 c->sacks[i].offset = offset;
620 } else if(offset <= c->sacks[i].offset + c->sacks[i].len) {
621 if(offset + rxd > c->sacks[i].offset + c->sacks[i].len) { // merge
622 debug("Merge with end of SACK entry at %d\n", i);
623 c->sacks[i].len = offset + rxd - c->sacks[i].offset;
624 // TODO: handle potential merge with next entry
630 for(int i = 0; i < NSACKS && c->sacks[i].len; i++)
631 debug("SACK[%d] offset %u len %u\n", i, c->sacks[i].offset, c->sacks[i].len);
634 static void handle_in_order(struct utcp_connection *c, const void *data, size_t len) {
635 // Check if we can process out-of-order data now.
636 if(c->sacks[0].len && len >= c->sacks[0].offset) { // TODO: handle overlap with second SACK
637 debug("incoming packet len %zu connected with SACK at %u\n", len, c->sacks[0].offset);
638 buffer_put_at(&c->rcvbuf, 0, data, len); // TODO: handle return value
639 len = max(len, c->sacks[0].offset + c->sacks[0].len);
640 data = c->rcvbuf.data;
644 ssize_t rxd = c->recv(c, data, len);
646 // TODO: handle the application not accepting all data.
652 sack_consume(c, len);
658 static void handle_incoming_data(struct utcp_connection *c, uint32_t seq, const void *data, size_t len) {
659 uint32_t offset = seqdiff(seq, c->rcv.nxt);
660 if(offset + len > c->rcvbuf.maxsize)
664 handle_out_of_order(c, offset, data, len);
666 handle_in_order(c, data, len);
670 ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
684 print_packet(utcp, "recv", data, len);
686 // Drop packets smaller than the header
689 if(len < sizeof hdr) {
694 // Make a copy from the potentially unaligned data to a struct hdr
696 memcpy(&hdr, data, sizeof hdr);
700 // Drop packets with an unknown CTL flag
702 if(hdr.ctl & ~(SYN | ACK | RST | FIN)) {
707 // Try to match the packet to an existing connection
709 struct utcp_connection *c = find_connection(utcp, hdr.dst, hdr.src);
711 // Is it for a new connection?
714 // Ignore RST packets
719 // Is it a SYN packet and are we LISTENing?
721 if(hdr.ctl & SYN && !(hdr.ctl & ACK) && utcp->accept) {
722 // If we don't want to accept it, send a RST back
723 if((utcp->pre_accept && !utcp->pre_accept(utcp, hdr.dst))) {
728 // Try to allocate memory, otherwise send a RST back
729 c = allocate_connection(utcp, hdr.dst, hdr.src);
735 // Return SYN+ACK, go to SYN_RECEIVED state
736 c->snd.wnd = hdr.wnd;
737 c->rcv.irs = hdr.seq;
738 c->rcv.nxt = c->rcv.irs + 1;
739 set_state(c, SYN_RECEIVED);
743 hdr.ack = c->rcv.irs + 1;
744 hdr.seq = c->snd.iss;
746 print_packet(c->utcp, "send", &hdr, sizeof hdr);
747 utcp->send(utcp, &hdr, sizeof hdr);
749 // No, we don't want your packets, send a RST back
757 debug("%p state %s\n", c->utcp, strstate[c->state]);
759 // In case this is for a CLOSED connection, ignore the packet.
760 // TODO: make it so incoming packets can never match a CLOSED connection.
762 if(c->state == CLOSED)
765 // It is for an existing connection.
767 uint32_t prevrcvnxt = c->rcv.nxt;
769 // 1. Drop invalid packets.
771 // 1a. Drop packets that should not happen in our current state.
791 // 1b. Drop packets with a sequence number not in our receive window.
795 if(c->state == SYN_SENT)
798 // TODO: handle packets overlapping c->rcv.nxt.
800 // Only use this when accepting out-of-order packets.
802 acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0;
804 acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
806 if(c->state != SYN_SENT)
807 acceptable = hdr.seq == c->rcv.nxt;
811 debug("Packet not acceptable, %u <= %u + %zu < %u\n", c->rcv.nxt, hdr.seq, len, c->rcv.nxt + c->rcvbuf.maxsize);
812 // Ignore unacceptable RST packets.
815 // Otherwise, send an ACK back in the hope things improve.
820 c->snd.wnd = hdr.wnd; // TODO: move below
822 // 1c. Drop packets with an invalid ACK.
823 // ackno should not roll back, and it should also not be bigger than what we ever could have sent
824 // (= snd.una + c->sndbuf.used).
827 ((seqdiff(hdr.ack, c->snd.una + c->sndbuf.used) > 0 &&
828 seqdiff(hdr.ack, c->snd.nxt) > 0) // TODO: simplify this if
829 || seqdiff(hdr.ack, c->snd.una) < 0)) {
830 debug("Packet ack seqno out of range, %u <= %u < %u\n", c->snd.una, hdr.ack, c->snd.una + c->sndbuf.used);
831 // Ignore unacceptable RST packets.
837 // 2. Handle RST packets
844 // The peer has refused our connection.
845 set_state(c, CLOSED);
846 errno = ECONNREFUSED;
853 // We haven't told the application about this connection yet. Silently delete.
862 // The peer has aborted our connection.
863 set_state(c, CLOSED);
873 // As far as the application is concerned, the connection has already been closed.
874 // If it has called utcp_close() already, we can immediately free this connection.
879 // Otherwise, immediately move to the CLOSED state.
880 set_state(c, CLOSED);
890 // 3. Advance snd.una
892 uint32_t advanced = seqdiff(hdr.ack, c->snd.una);
893 prevrcvnxt = c->rcv.nxt;
896 int32_t data_acked = advanced;
903 // TODO: handle FIN as well.
908 assert(data_acked >= 0);
910 int32_t bufused = seqdiff(c->snd.last, c->snd.una);
911 assert(data_acked <= bufused);
914 buffer_get(&c->sndbuf, NULL, data_acked);
916 // Also advance snd.nxt if possible
917 if(seqdiff(c->snd.nxt, hdr.ack) < 0)
918 c->snd.nxt = hdr.ack;
920 c->snd.una = hdr.ack;
923 c->snd.cwnd += utcp->mtu;
924 if(c->snd.cwnd > c->sndbuf.maxsize)
925 c->snd.cwnd = c->sndbuf.maxsize;
927 // Check if we have sent a FIN that is now ACKed.
930 if(c->snd.una == c->snd.last)
931 set_state(c, FIN_WAIT_2);
934 if(c->snd.una == c->snd.last) {
935 gettimeofday(&c->conn_timeout, NULL);
936 c->conn_timeout.tv_sec += 60;
937 set_state(c, TIME_WAIT);
947 debug("Triplicate ACK\n");
948 //TODO: Resend one packet and go to fast recovery mode. See RFC 6582.
949 //We do a very simple variant here; reset the nxt pointer to the last acknowledged packet from the peer.
950 //Reset the congestion window so we wait for ACKs.
951 c->snd.nxt = c->snd.una;
952 c->snd.cwnd = utcp->mtu;
960 timerclear(&c->conn_timeout); // It will be set anew in utcp_timeout() if c->snd.una != c->snd.nxt.
961 if(c->snd.una == c->snd.nxt)
962 timerclear(&c->rtrx_timeout);
965 // 5. Process SYN stuff
970 // This is a SYNACK. It should always have ACKed the SYN.
973 c->rcv.irs = hdr.seq;
974 c->rcv.nxt = hdr.seq;
975 set_state(c, ESTABLISHED);
976 // TODO: notify application of this somehow.
986 // Ehm, no. We should never receive a second SYN.
995 // SYN counts as one sequence number
999 // 6. Process new data
1001 if(c->state == SYN_RECEIVED) {
1002 // This is the ACK after the SYNACK. It should always have ACKed the SYNACK.
1006 // Are we still LISTENing?
1008 utcp->accept(c, c->src);
1010 if(c->state != ESTABLISHED) {
1011 set_state(c, CLOSED);
1021 // This should never happen.
1034 // Ehm no, We should never receive more data after a FIN.
1043 handle_incoming_data(c, hdr.seq, data, len);
1046 // 7. Process FIN stuff
1048 if((hdr.ctl & FIN) && hdr.seq + len == c->rcv.nxt) {
1052 // This should never happen.
1058 set_state(c, CLOSE_WAIT);
1061 set_state(c, CLOSING);
1064 gettimeofday(&c->conn_timeout, NULL);
1065 c->conn_timeout.tv_sec += 60;
1066 set_state(c, TIME_WAIT);
1072 // Ehm, no. We should never receive a second FIN.
1081 // FIN counts as one sequence number
1085 // Inform the application that the peer closed the connection.
1088 c->recv(c, NULL, 0);
1092 // Now we send something back if:
1093 // - we advanced rcv.nxt (ie, we got some data that needs to be ACKed)
1094 // -> sendatleastone = true
1095 // - or we got an ack, so we should maybe send a bit more data
1096 // -> sendatleastone = false
1099 ack(c, prevrcvnxt != c->rcv.nxt);
1109 hdr.ack = hdr.seq + len;
1111 hdr.ctl = RST | ACK;
1113 print_packet(utcp, "send", &hdr, sizeof hdr);
1114 utcp->send(utcp, &hdr, sizeof hdr);
1119 int utcp_shutdown(struct utcp_connection *c, int dir) {
1120 debug("%p shutdown %d at %u\n", c ? c->utcp : NULL, dir, c ? c->snd.last : 0);
1127 debug("Error: shutdown() called on closed connection %p\n", c);
1132 if(!(dir == UTCP_SHUT_RD || dir == UTCP_SHUT_WR || dir == UTCP_SHUT_RDWR)) {
1137 // TCP does not have a provision for stopping incoming packets.
1138 // The best we can do is to just ignore them.
1139 if(dir == UTCP_SHUT_RD || dir == UTCP_SHUT_RDWR)
1142 // The rest of the code deals with shutting down writes.
1143 if(dir == UTCP_SHUT_RD)
1153 set_state(c, CLOSED);
1158 set_state(c, FIN_WAIT_1);
1164 set_state(c, CLOSING);
1179 int utcp_close(struct utcp_connection *c) {
1180 if(utcp_shutdown(c, SHUT_RDWR))
1188 int utcp_abort(struct utcp_connection *c) {
1195 debug("Error: abort() called on closed connection %p\n", c);
1212 set_state(c, CLOSED);
1220 set_state(c, CLOSED);
1230 hdr.seq = c->snd.nxt;
1235 print_packet(c->utcp, "send", &hdr, sizeof hdr);
1236 c->utcp->send(c->utcp, &hdr, sizeof hdr);
1241 * One call to this function will loop through all connections,
1242 * checking if something needs to be resent or not.
1243 * The return value is the time to the next timeout in milliseconds,
1244 * or maybe a negative value if the timeout is infinite.
1246 struct timeval utcp_timeout(struct utcp *utcp) {
1248 gettimeofday(&now, NULL);
1249 struct timeval next = {now.tv_sec + 3600, now.tv_usec};
1251 for(int i = 0; i < utcp->nconnections; i++) {
1252 struct utcp_connection *c = utcp->connections[i];
1256 if(c->state == CLOSED) {
1258 debug("Reaping %p\n", c);
1265 if(timerisset(&c->conn_timeout) && timercmp(&c->conn_timeout, &now, <)) {
1269 c->recv(c, NULL, 0);
1273 if(timerisset(&c->rtrx_timeout) && timercmp(&c->rtrx_timeout, &now, <)) {
1277 if(c->poll && buffer_free(&c->sndbuf) && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
1278 c->poll(c, buffer_free(&c->sndbuf));
1280 if(timerisset(&c->conn_timeout) && timercmp(&c->conn_timeout, &next, <))
1281 next = c->conn_timeout;
1283 if(c->snd.nxt != c->snd.una) {
1284 c->rtrx_timeout = now;
1285 c->rtrx_timeout.tv_sec++;
1287 timerclear(&c->rtrx_timeout);
1290 if(timerisset(&c->rtrx_timeout) && timercmp(&c->rtrx_timeout, &next, <))
1291 next = c->rtrx_timeout;
1294 struct timeval diff;
1295 timersub(&next, &now, &diff);
1299 bool utcp_is_active(struct utcp *utcp) {
1303 for(int i = 0; i < utcp->nconnections; i++)
1304 if(utcp->connections[i]->state != CLOSED && utcp->connections[i]->state != TIME_WAIT)
1310 struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_send_t send, void *priv) {
1316 struct utcp *utcp = calloc(1, sizeof *utcp);
1320 utcp->accept = accept;
1321 utcp->pre_accept = pre_accept;
1330 void utcp_exit(struct utcp *utcp) {
1333 for(int i = 0; i < utcp->nconnections; i++) {
1334 if(!utcp->connections[i]->reapable)
1335 debug("Warning, freeing unclosed connection %p\n", utcp->connections[i]);
1336 buffer_exit(&utcp->connections[i]->sndbuf);
1337 free(utcp->connections[i]);
1339 free(utcp->connections);
1343 uint16_t utcp_get_mtu(struct utcp *utcp) {
1344 return utcp ? utcp->mtu : 0;
1347 void utcp_set_mtu(struct utcp *utcp, uint16_t mtu) {
1348 // TODO: handle overhead of the header
1353 int utcp_get_user_timeout(struct utcp *u) {
1354 return u ? u->timeout : 0;
1357 void utcp_set_user_timeout(struct utcp *u, int timeout) {
1359 u->timeout = timeout;
1362 size_t utcp_get_sndbuf(struct utcp_connection *c) {
1363 return c ? c->sndbuf.maxsize : 0;
1366 size_t utcp_get_sndbuf_free(struct utcp_connection *c) {
1367 if(c && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
1368 return buffer_free(&c->sndbuf);
1373 void utcp_set_sndbuf(struct utcp_connection *c, size_t size) {
1376 c->sndbuf.maxsize = size;
1377 if(c->sndbuf.maxsize != size)
1378 c->sndbuf.maxsize = -1;
1381 size_t utcp_get_rcvbuf(struct utcp_connection *c) {
1382 return c ? c->rcvbuf.maxsize : 0;
1385 size_t utcp_get_rcvbuf_free(struct utcp_connection *c) {
1386 if(c && (c->state == ESTABLISHED || c->state == CLOSE_WAIT))
1387 return buffer_free(&c->rcvbuf);
1392 void utcp_set_rcvbuf(struct utcp_connection *c, size_t size) {
1395 c->rcvbuf.maxsize = size;
1396 if(c->rcvbuf.maxsize != size)
1397 c->rcvbuf.maxsize = -1;
1400 bool utcp_get_nodelay(struct utcp_connection *c) {
1401 return c ? c->nodelay : false;
1404 void utcp_set_nodelay(struct utcp_connection *c, bool nodelay) {
1406 c->nodelay = nodelay;
1409 bool utcp_get_keepalive(struct utcp_connection *c) {
1410 return c ? c->keepalive : false;
1413 void utcp_set_keepalive(struct utcp_connection *c, bool keepalive) {
1415 c->keepalive = keepalive;
1418 size_t utcp_get_outq(struct utcp_connection *c) {
1419 return c ? seqdiff(c->snd.nxt, c->snd.una) : 0;
1422 void utcp_set_recv_cb(struct utcp_connection *c, utcp_recv_t recv) {
1427 void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
1432 void utcp_set_accept_cb(struct utcp *utcp, utcp_accept_t accept, utcp_pre_accept_t pre_accept) {
1434 utcp->accept = accept;
1435 utcp->pre_accept = pre_accept;