2 net.c -- most of the network code
3 Copyright (C) 1998,1999,2000 Ivo Timmermans <itimmermans@bigfoot.com>,
4 2000 Guus Sliepen <guus@sliepen.warande.net>
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 $Id: net.c,v 1.35.4.14 2000/06/29 17:09:05 guus Exp $
25 #include <arpa/inet.h>
29 #include <netinet/in.h>
33 #include <sys/signal.h>
34 #include <sys/socket.h>
36 #include <sys/types.h>
55 int total_tap_out = 0;
56 int total_socket_in = 0;
57 int total_socket_out = 0;
59 int upstreamindex = 0;
60 static int seconds_till_retry;
62 /* The global list of existing connections */
63 conn_list_t *conn_list = NULL;
64 conn_list_t *myself = NULL;
67 strip off the MAC adresses of an ethernet frame
69 void strip_mac_addresses(vpn_packet_t *p)
71 unsigned char tmp[MAXSIZE];
73 memcpy(tmp, p->data, p->len);
75 memcpy(p->data, &tmp[12], p->len);
80 reassemble MAC addresses
82 void add_mac_addresses(vpn_packet_t *p)
84 unsigned char tmp[MAXSIZE];
86 memcpy(&tmp[12], p->data, p->len);
88 tmp[0] = tmp[6] = 0xfe;
89 tmp[1] = tmp[7] = 0xfd;
90 *((ip_t*)(&tmp[2])) = (ip_t)(htonl(myself->vpn_ip));
91 *((ip_t*)(&tmp[8])) = *((ip_t*)(&tmp[26]));
92 memcpy(p->data, &tmp[0], p->len);
96 int xsend(conn_list_t *cl, void *packet)
101 do_encrypt((vpn_packet_t*)packet, &rp, cl->key);
102 rp.from = htonl(myself->vpn_ip);
103 rp.data.len = htons(rp.data.len);
104 rp.len = htons(rp.len);
107 syslog(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
108 ntohs(rp.len), cl->vpn_hostname, cl->real_hostname);
110 if((r = send(cl->socket, (char*)&rp, ntohs(rp.len), 0)) < 0)
112 syslog(LOG_ERR, _("Error sending packet to %s (%s): %m"),
113 cl->vpn_hostname, cl->real_hostname);
117 total_socket_out += r;
124 int xrecv(conn_list_t *cl, void *packet)
129 do_decrypt((real_packet_t*)packet, &vp, cl->key);
130 add_mac_addresses(&vp);
133 syslog(LOG_ERR, _("Receiving packet of %d bytes from %s (%s)"),
134 ((real_packet_t*)packet)->len, cl->vpn_hostname, cl->real_hostname);
136 if((lenin = write(tap_fd, &vp, vp.len + sizeof(vp.len))) < 0)
137 syslog(LOG_ERR, _("Can't write to tap device: %m"));
139 total_tap_out += lenin;
142 cl->last_ping_time = time(NULL);
148 add the given packet of size s to the
149 queue q, be it the send or receive queue
151 void add_queue(packet_queue_t **q, void *packet, size_t s)
155 e = xmalloc(sizeof(*e));
156 e->packet = xmalloc(s);
157 memcpy(e->packet, packet, s);
161 *q = xmalloc(sizeof(**q));
162 (*q)->head = (*q)->tail = NULL;
165 e->next = NULL; /* We insert at the tail */
167 if((*q)->tail) /* Do we have a tail? */
169 (*q)->tail->next = e;
170 e->prev = (*q)->tail;
172 else /* No tail -> no head too */
182 /* Remove a queue element */
183 void del_queue(packet_queue_t **q, queue_element_t *e)
188 if(e->next) /* There is a successor, so we are not tail */
190 if(e->prev) /* There is a predecessor, so we are not head */
192 e->next->prev = e->prev;
193 e->prev->next = e->next;
195 else /* We are head */
197 e->next->prev = NULL;
198 (*q)->head = e->next;
201 else /* We are tail (or all alone!) */
203 if(e->prev) /* We are not alone :) */
205 e->prev->next = NULL;
206 (*q)->tail = e->prev;
220 flush a queue by calling function for
221 each packet, and removing it when that
222 returned a zero exit code
224 void flush_queue(conn_list_t *cl, packet_queue_t **pq,
225 int (*function)(conn_list_t*,void*))
227 queue_element_t *p, *next = NULL;
229 for(p = (*pq)->head; p != NULL; )
233 if(!function(cl, p->packet))
240 syslog(LOG_DEBUG, _("Queue flushed"));
245 flush the send&recv queues
246 void because nothing goes wrong here, packets
247 remain in the queue if something goes wrong
249 void flush_queues(conn_list_t *cl)
255 syslog(LOG_DEBUG, _("Flushing send queue for %s (%s)"),
256 cl->vpn_hostname, cl->real_hostname);
257 flush_queue(cl, &(cl->sq), xsend);
263 syslog(LOG_DEBUG, _("Flushing receive queue for %s (%s)"),
264 cl->vpn_hostname, cl->real_hostname);
265 flush_queue(cl, &(cl->rq), xrecv);
271 send a packet to the given vpn ip.
273 int send_packet(ip_t to, vpn_packet_t *packet)
277 if((cl = lookup_conn(to)) == NULL)
281 syslog(LOG_NOTICE, _("Trying to look up %d.%d.%d.%d in connection list failed!"),
285 /* Is this really necessary? If we can't find "to", then neither should any uplink. (GS) */
289 for(cl = conn_list; cl != NULL && !cl->status.outgoing; cl = cl->next);
291 { /* No open outgoing connection has been found. */
293 syslog(LOG_NOTICE, _("There is no remote host I can send this packet to!"));
298 /* If we ourselves have indirectdata flag set, we should send only to our uplink! */
300 if(myself->flags & EXPORTINDIRECTDATA)
302 for(cl = conn_list; cl != NULL && !cl->status.outgoing; cl = cl->next);
304 { /* No open outgoing connection has been found. */
306 syslog(LOG_NOTICE, _("There is no remote host I can send this packet to!"));
312 /* If indirectdata flag is set for the destination we just looked up,
313 * then real_ip is actually the vpn_ip of the gateway tincd
317 if(cl->flags & INDIRECTDATA)
320 syslog(LOG_NOTICE, _("Indirect packet to %s via %s"),
321 cl->vpn_hostname, cl->real_hostname);
322 if((cl = lookup_conn(cl->real_ip)) == NULL)
325 syslog(LOG_NOTICE, _("Indirect look up %d.%d.%d.%d in connection list failed!"),
328 /* Gateway tincd dead? Should we kill it? (GS) */
332 if(cl->flags & INDIRECTDATA) /* This should not happen */
335 syslog(LOG_NOTICE, _("Double indirection for %d.%d.%d.%d"),
341 if(my_key_expiry <= time(NULL))
344 if(!cl->status.dataopen)
345 if(setup_vpn_connection(cl) < 0)
347 syslog(LOG_ERR, _("Could not open UDP connection to %s (%s)"), cl->vpn_hostname, cl->real_hostname);
351 if(!cl->status.validkey)
354 syslog(LOG_INFO, _("%s (%s) has no valid key, queueing packet"), cl->vpn_hostname, cl->real_hostname);
355 add_queue(&(cl->sq), packet, packet->len + 2);
356 if(!cl->status.waitingforkey)
357 send_key_request(cl->vpn_ip); /* Keys should be sent to the host running the tincd */
361 if(!cl->status.active)
364 syslog(LOG_INFO, _("%s (%s) is not ready, queueing packet"), cl->vpn_hostname, cl->real_hostname);
365 add_queue(&(cl->sq), packet, packet->len + 2);
366 return 0; /* We don't want to mess up, do we? */
369 /* can we send it? can we? can we? huh? */
371 return xsend(cl, packet);
375 open the local ethertap device
377 int setup_tap_fd(void)
380 const char *tapfname;
383 if((cfg = get_config_val(tapdevice)) == NULL)
384 tapfname = "/dev/tap0";
386 tapfname = cfg->data.ptr;
388 if((nfd = open(tapfname, O_RDWR | O_NONBLOCK)) < 0)
390 syslog(LOG_ERR, _("Could not open %s: %m"), tapfname);
400 set up the socket that we listen on for incoming
403 int setup_listen_meta_socket(int port)
406 struct sockaddr_in a;
409 if((nfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
411 syslog(LOG_ERR, _("Creating metasocket failed: %m"));
415 if(setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)))
417 syslog(LOG_ERR, _("setsockopt: %m"));
421 flags = fcntl(nfd, F_GETFL);
422 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0)
424 syslog(LOG_ERR, _("fcntl: %m"));
428 memset(&a, 0, sizeof(a));
429 a.sin_family = AF_INET;
430 a.sin_port = htons(port);
431 a.sin_addr.s_addr = htonl(INADDR_ANY);
433 if(bind(nfd, (struct sockaddr *)&a, sizeof(struct sockaddr)))
435 syslog(LOG_ERR, _("Can't bind to port %hd/tcp: %m"), port);
441 syslog(LOG_ERR, _("listen: %m"));
449 setup the socket for incoming encrypted
452 int setup_vpn_in_socket(int port)
455 struct sockaddr_in a;
458 if((nfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
460 syslog(LOG_ERR, _("Creating socket failed: %m"));
464 if(setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)))
466 syslog(LOG_ERR, _("setsockopt: %m"));
470 flags = fcntl(nfd, F_GETFL);
471 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0)
473 syslog(LOG_ERR, _("fcntl: %m"));
477 memset(&a, 0, sizeof(a));
478 a.sin_family = AF_INET;
479 a.sin_port = htons(port);
480 a.sin_addr.s_addr = htonl(INADDR_ANY);
482 if(bind(nfd, (struct sockaddr *)&a, sizeof(struct sockaddr)))
484 syslog(LOG_ERR, _("Can't bind to port %hd/udp: %m"), port);
492 setup an outgoing meta (tcp) socket
494 int setup_outgoing_meta_socket(conn_list_t *cl)
497 struct sockaddr_in a;
501 syslog(LOG_INFO, _("Trying to connect to %s"), cl->real_hostname);
503 if((cfg = get_config_val(upstreamport)) == NULL)
506 cl->port = cfg->data.val;
508 cl->meta_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
509 if(cl->meta_socket == -1)
511 syslog(LOG_ERR, _("Creating socket failed: %m"));
515 a.sin_family = AF_INET;
516 a.sin_port = htons(cl->port);
517 a.sin_addr.s_addr = htonl(cl->real_ip);
519 if(connect(cl->meta_socket, (struct sockaddr *)&a, sizeof(a)) == -1)
521 syslog(LOG_ERR, _("%s port %hd: %m"), cl->real_hostname, cl->port);
525 flags = fcntl(cl->meta_socket, F_GETFL);
526 if(fcntl(cl->meta_socket, F_SETFL, flags | O_NONBLOCK) < 0)
528 syslog(LOG_ERR, _("fcntl: %m"));
532 syslog(LOG_INFO, _("Connected to %s port %hd"),
533 cl->real_hostname, cl->port);
539 setup an outgoing connection. It's not
540 necessary to also open an udp socket as
541 well, because the other host will initiate
542 an authentication sequence during which
543 we will do just that.
545 int setup_outgoing_connection(ip_t ip)
549 ncn = new_conn_list();
551 ncn->real_hostname = hostlookup(htonl(ip));
553 if(setup_outgoing_meta_socket(ncn) < 0)
555 syslog(LOG_ERR, _("Could not set up a meta connection to %s"),
557 free_conn_element(ncn);
561 ncn->status.meta = 1;
562 ncn->status.outgoing = 1;
563 ncn->next = conn_list;
570 set up the local sockets (listen only)
572 int setup_myself(void)
576 myself = new_conn_list();
578 if(!(cfg = get_config_val(myvpnip)))
580 syslog(LOG_ERR, _("No value for my VPN IP given"));
584 myself->vpn_ip = cfg->data.ip->ip;
585 myself->vpn_hostname = hostlookup(htonl(myself->vpn_ip));
586 myself->real_hostname = hostlookup(htonl(myself->vpn_ip));
587 myself->vpn_mask = cfg->data.ip->mask;
590 if(!(cfg = get_config_val(listenport)))
593 myself->port = cfg->data.val;
595 if(cfg = get_config_val(indirectdata))
596 if(cfg->data.val == stupid_true)
597 myself->flags |= EXPORTINDIRECTDATA;
599 if((myself->meta_socket = setup_listen_meta_socket(myself->port)) < 0)
601 syslog(LOG_ERR, _("Unable to set up a listening socket"));
605 if((myself->socket = setup_vpn_in_socket(myself->port)) < 0)
607 syslog(LOG_ERR, _("Unable to set up an incoming vpn data socket"));
608 close(myself->meta_socket);
612 myself->status.active = 1;
614 syslog(LOG_NOTICE, _("Ready: listening on port %hd"), myself->port);
620 sigalrm_handler(int a)
624 cfg = get_next_config_val(upstreamip, upstreamindex++);
628 if(!setup_outgoing_connection(cfg->data.ip->ip)) /* function returns 0 when there are no problems */
630 signal(SIGALRM, SIG_IGN);
633 cfg = get_next_config_val(upstreamip, upstreamindex++); /* Or else we try the next ConnectTo line */
636 signal(SIGALRM, sigalrm_handler);
638 seconds_till_retry += 5;
639 if(seconds_till_retry>300) /* Don't wait more than 5 minutes. */
640 seconds_till_retry = 300;
641 alarm(seconds_till_retry);
642 syslog(LOG_ERR, _("Still failed to connect to other, will retry in %d seconds"),
648 setup all initial network connections
650 int setup_network_connections(void)
654 if((cfg = get_config_val(pingtimeout)) == NULL)
657 timeout = cfg->data.val;
659 if(setup_tap_fd() < 0)
662 if(setup_myself() < 0)
665 if((cfg = get_next_config_val(upstreamip, upstreamindex++)) == NULL)
666 /* No upstream IP given, we're listen only. */
671 if(!setup_outgoing_connection(cfg->data.ip->ip)) /* function returns 0 when there are no problems */
673 cfg = get_next_config_val(upstreamip, upstreamindex++); /* Or else we try the next ConnectTo line */
676 signal(SIGALRM, sigalrm_handler);
678 seconds_till_retry = 300;
679 alarm(seconds_till_retry);
680 syslog(LOG_NOTICE, _("Trying to re-establish outgoing connection in 5 minutes"));
686 close all open network connections
688 void close_network_connections(void)
692 for(p = conn_list; p != NULL; p = p->next)
694 if(p->status.dataopen)
696 shutdown(p->socket, 0); /* No more receptions */
702 shutdown(p->meta_socket, 0); /* No more receptions */
703 close(p->meta_socket);
708 if(myself->status.active)
710 close(myself->meta_socket);
711 close(myself->socket);
717 syslog(LOG_NOTICE, _("Terminating"));
723 create a data (udp) socket
725 int setup_vpn_connection(conn_list_t *cl)
728 struct sockaddr_in a;
731 syslog(LOG_DEBUG, _("Opening UDP socket to %s"), cl->real_hostname);
733 nfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
736 syslog(LOG_ERR, _("Creating UDP socket failed: %m"));
740 a.sin_family = AF_INET;
741 a.sin_port = htons(cl->port);
742 a.sin_addr.s_addr = htonl(cl->real_ip);
744 if(connect(nfd, (struct sockaddr *)&a, sizeof(a)) == -1)
746 syslog(LOG_ERR, _("Connecting to %s port %d failed: %m"),
747 cl->real_hostname, cl->port);
751 flags = fcntl(nfd, F_GETFL);
752 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0)
754 syslog(LOG_ERR, _("This is a bug: %s:%d: %d:%m"), __FILE__, __LINE__, nfd);
759 cl->status.dataopen = 1;
765 handle an incoming tcp connect call and open
768 conn_list_t *create_new_connection(int sfd)
771 struct sockaddr_in ci;
772 int len = sizeof(ci);
776 if(getpeername(sfd, &ci, &len) < 0)
778 syslog(LOG_ERR, _("Error: getpeername: %m"));
782 p->vpn_hostname = _("unknown");
783 p->real_ip = ntohl(ci.sin_addr.s_addr);
784 p->real_hostname = hostlookup(ci.sin_addr.s_addr);
785 p->meta_socket = sfd;
788 p->last_ping_time = time(NULL);
792 syslog(LOG_NOTICE, _("Connection from %s port %d"),
793 p->real_hostname, htons(ci.sin_port));
795 if(send_basic_info(p) < 0)
805 put all file descriptors in an fd_set array
807 void build_fdset(fd_set *fs)
813 for(p = conn_list; p != NULL; p = p->next)
816 FD_SET(p->meta_socket, fs);
817 if(p->status.dataopen)
818 FD_SET(p->socket, fs);
821 FD_SET(myself->meta_socket, fs);
822 FD_SET(myself->socket, fs);
828 receive incoming data from the listening
829 udp socket and write it to the ethertap
830 device after being decrypted
832 int handle_incoming_vpn_data(conn_list_t *cl)
836 int x, l = sizeof(x);
839 if(getsockopt(cl->socket, SOL_SOCKET, SO_ERROR, &x, &l) < 0)
841 syslog(LOG_ERR, _("This is a bug: %s:%d: %d:%m"), __FILE__, __LINE__, cl->socket);
846 syslog(LOG_ERR, _("Incoming data socket error: %s"), sys_errlist[x]);
851 lenin = recvfrom(cl->socket, &rp, MTU, 0, NULL, NULL);
854 syslog(LOG_ERR, _("Receiving packet from %s failed: %m"), cl->real_hostname);
857 total_socket_in += lenin;
859 rp.data.len = ntohs(rp.data.len);
860 rp.len = ntohs(rp.len);
861 rp.from = ntohl(rp.from);
865 f = lookup_conn(rp.from);
868 syslog(LOG_ERR, _("Got packet from %s (%s) with unknown origin %d.%d.%d.%d?"),
869 cl->vpn_hostname, cl->real_hostname, IP_ADDR_V(rp.from));
873 if(f->status.validkey)
877 add_queue(&(f->rq), &rp, rp.len);
878 if(!cl->status.waitingforkey)
879 send_key_request(rp.from);
882 if(my_key_expiry <= time(NULL))
890 terminate a connection and notify the other
891 end before closing the sockets
893 void terminate_connection(conn_list_t *cl)
898 if(cl->status.remove)
902 syslog(LOG_NOTICE, _("Closing connection with %s (%s)"),
903 cl->vpn_hostname, cl->real_hostname);
905 if(cl->status.timeout)
907 else if(!cl->status.termreq)
912 close(cl->meta_socket);
914 if(cl->status.outgoing)
916 signal(SIGALRM, sigalrm_handler);
917 seconds_till_retry = 5;
918 alarm(seconds_till_retry);
919 syslog(LOG_NOTICE, _("Trying to re-establish outgoing connection in 5 seconds"));
922 cl->status.remove = 1;
924 /* If this cl isn't active, don't send any DEL_HOSTs. */
925 if(!cl->status.active)
928 cl->status.active = 0;
929 notify_others(cl,NULL,send_del_host);
932 /* Find all connections that were lost because they were behind cl
933 (the connection that was dropped). */
935 for(p = conn_list; p != NULL; p = p->next)
940 notify_others(p,cl,send_del_host);
941 p->status.active = 0;
942 p->status.remove = 1;
947 /* Then send a notification about all these connections to all hosts
948 that are still connected to us.
949 for(p = conn_list; p != NULL; p = p->next)
950 if(p->status.active && p->status.meta)
951 for(q = conn_list; q != NULL; q = q->next)
959 Check if the other end is active.
960 If we have sent packets, but didn't receive any,
961 then possibly the other end is dead. We send a
962 PING request over the meta connection. If the other
963 end does not reply in time, we consider them dead
964 and close the connection.
966 int check_dead_connections(void)
972 for(p = conn_list; p != NULL; p = p->next)
976 if(p->status.active && p->status.meta)
978 if(p->last_ping_time + timeout < now)
980 if(p->status.pinged && !p->status.got_pong)
983 syslog(LOG_INFO, _("%s (%s) didn't respond to PING"),
984 p->vpn_hostname, p->real_hostname);
985 p->status.timeout = 1;
986 terminate_connection(p);
988 else if(p->want_ping)
991 p->last_ping_time = now;
992 p->status.pinged = 1;
993 p->status.got_pong = 0;
1003 accept a new tcp connect and create a
1006 int handle_new_meta_connection(conn_list_t *cl)
1009 struct sockaddr client;
1010 int nfd, len = sizeof(client);
1012 if((nfd = accept(cl->meta_socket, &client, &len)) < 0)
1014 syslog(LOG_ERR, _("Accepting a new connection failed: %m"));
1018 if((ncn = create_new_connection(nfd)) == NULL)
1022 syslog(LOG_NOTICE, _("Closed attempted connection"));
1026 ncn->status.meta = 1;
1027 ncn->next = conn_list;
1034 dispatch any incoming meta requests
1036 int handle_incoming_meta_data(conn_list_t *cl)
1038 int x, l = sizeof(x);
1039 int request, oldlen, i;
1042 if(getsockopt(cl->meta_socket, SOL_SOCKET, SO_ERROR, &x, &l) < 0)
1044 syslog(LOG_ERR, _("This is a bug: %s:%d: %d:%m"), __FILE__, __LINE__, cl->meta_socket);
1049 syslog(LOG_ERR, _("Metadata socket error: %s"), sys_errlist[x]);
1053 if(cl->buflen >= MAXBUFSIZE)
1055 syslog(LOG_ERR, _("Metadata read buffer overflow!"));
1059 lenin = read(cl->meta_socket, cl->buffer, MAXBUFSIZE-cl->buflen);
1065 syslog(LOG_ERR, _("Metadata socket read error: %m"));
1069 oldlen = cl->buflen;
1070 cl->buflen += lenin;
1076 for(i = oldlen; i < cl->buflen; i++)
1078 if(cl->buffer[i] == '\n')
1080 cl->buffer[i] = 0; /* replace end-of-line by end-of-string so we can use sscanf */
1089 syslog(LOG_DEBUG, _("Got request from %s (%s): %s"),
1090 cl->vpn_hostname, cl->real_hostname, cl->buffer);
1091 if(sscanf(cl->buffer, "%d", &request) == 1)
1093 if((request < 0) || (request > 255) || (request_handlers[request] == NULL))
1095 syslog(LOG_ERR, _("Unknown request from %s (%s)"),
1096 cl->vpn_hostname, cl->real_hostname);
1100 if(request_handlers[request](cl)) /* Something went wrong. Probably scriptkiddies. Terminate. */
1102 syslog(LOG_ERR, _("Error while processing request from %s (%s)"),
1103 cl->vpn_hostname, cl->real_hostname);
1109 syslog(LOG_ERR, _("Bogus data received from %s (%s)"),
1110 cl->vpn_hostname, cl->real_hostname);
1114 cl->buflen -= cl->reqlen;
1115 memmove(cl->buffer, cl->buffer + cl->reqlen, cl->buflen);
1124 cl->last_ping_time = time(NULL);
1131 check all connections to see if anything
1132 happened on their sockets
1134 void check_network_activity(fd_set *f)
1137 int x, l = sizeof(x);
1139 for(p = conn_list; p != NULL; p = p->next)
1141 if(p->status.remove)
1144 if(p->status.dataopen)
1145 if(FD_ISSET(p->socket, f))
1148 The only thing that can happen to get us here is apparently an
1149 error on this outgoing(!) UDP socket that isn't immediate (i.e.
1150 something that will not trigger an error directly on send()).
1151 I've once got here when it said `No route to host'.
1153 getsockopt(p->socket, SOL_SOCKET, SO_ERROR, &x, &l);
1154 syslog(LOG_ERR, _("Outgoing data socket error for %s (%s): %s"),
1155 p->vpn_hostname, p->real_hostname, sys_errlist[x]);
1156 terminate_connection(p);
1161 if(FD_ISSET(p->meta_socket, f))
1162 if(handle_incoming_meta_data(p) < 0)
1164 terminate_connection(p);
1169 if(FD_ISSET(myself->socket, f))
1170 handle_incoming_vpn_data(myself);
1172 if(FD_ISSET(myself->meta_socket, f))
1173 handle_new_meta_connection(myself);
1178 read, encrypt and send data that is
1179 available through the ethertap device
1181 void handle_tap_input(void)
1185 int ether_type, lenin;
1187 memset(&vp, 0, sizeof(vp));
1188 if((lenin = read(tap_fd, &vp, MTU)) <= 0)
1190 syslog(LOG_ERR, _("Error while reading from tapdevice: %m"));
1194 total_tap_in += lenin;
1196 ether_type = ntohs(*((unsigned short*)(&vp.data[12])));
1197 if(ether_type != 0x0800)
1200 syslog(LOG_INFO, _("Non-IP ethernet frame %04x from " MAC_ADDR_S),
1201 ether_type, MAC_ADDR_V(vp.data[6]));
1208 syslog(LOG_INFO, _("Dropping short packet"));
1212 from = ntohl(*((unsigned long*)(&vp.data[26])));
1213 to = ntohl(*((unsigned long*)(&vp.data[30])));
1215 vp.len = (length_t)lenin - 2;
1217 strip_mac_addresses(&vp);
1219 send_packet(to, &vp);
1224 this is where it all happens...
1226 void main_loop(void)
1231 time_t last_ping_check;
1233 last_ping_check = time(NULL);
1237 tv.tv_sec = timeout;
1243 if((r = select(FD_SETSIZE, &fset, NULL, NULL, &tv)) < 0)
1245 if(errno == EINTR) /* because of alarm */
1247 syslog(LOG_ERR, _("Error while waiting for input: %m"));
1251 if(last_ping_check + timeout < time(NULL))
1252 /* Let's check if everybody is still alive */
1254 check_dead_connections();
1255 last_ping_check = time(NULL);
1259 check_network_activity(&fset);
1261 /* local tap data */
1262 if(FD_ISSET(tap_fd, &fset))