2 * Encrypting tunnel for userv-ipif tunnels, actual core implementation
6 * udptunnel-forwarder <optchars>
7 * <public-local-fd> <private-in-fd> <private-out-fd>
9 * <mtu> <keepalive> <timeout> <reannounce>
10 * <public-remote-addr> [<public-remote-port>]
11 * |<mech1> [<mech1-params> ...]
12 * |<mech2> [<mech2-params> ...]
15 * Remote addr may '' to mean wait to receive a packet and reply to
16 * whereever we get a good packet from first, in which case port
17 * should not be specified.
19 * <optchars> is zero or more of
20 * w means generate and write encdec keys, rather than reading them
21 * K means do crypto debug (use with care!)
23 * encdec keys datastream has keys for packets from key datastream
24 * writer to reader first, then keys for packets from reader to
27 * Every addr or port must be numeric. There is very little argument checking.
31 * 0 terminated due to outbound packet stream EOF
38 * Copyright (C) 2000,2003 Ian Jackson
39 * This file is part of ipif, part of userv-utils
41 * This is free software; you can redistribute it and/or modify it
42 * under the terms of the GNU General Public License as published by
43 * the Free Software Foundation; either version 2 of the License, or
44 * (at your option) any later version.
46 * This program is distributed in the hope that it will be useful, but
47 * WITHOUT ANY WARRANTY; without even the implied warranty of
48 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
49 * General Public License for more details.
51 * You should have received a copy of the GNU General Public License
52 * along with userv-utils; if not, write to the Free Software
53 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
56 #include <sys/socket.h>
57 #include <netinet/in.h>
58 #include <arpa/inet.h>
59 #include <sys/utsname.h>
70 #include "forwarder.h"
74 static size_t buffer_size;
75 static struct utsname uname_result;
77 static const char *opt_chars;
78 static int public_local_fd, private_in_fd, private_out_fd;
79 static int mtu2, keepalive, timeout, reannounce;
80 static int public_remote_specd;
81 static struct sockaddr_in public_remote;
82 static int encdec_keys_fd, encdec_keys_write, crypto_debug;
84 static const struct mechanism *mechs[MAXMECHS];
86 static struct mechdata *md_in[MAXMECHS], *md_out[MAXMECHS];
87 static size_t maxprefix, maxsuffix;
89 static struct buffer buf_in, buf_out;
90 static unsigned char *accum_buf;
91 static size_t accum_used, accum_avail;
93 static time_t nextsendka;
95 static void cdebug(int mechno /*or -1*/, const char *msg) {
96 if (!crypto_debug) return;
97 printf("%-8.8s: CRYPTO: %-20s %s\n",
98 uname_result.nodename,
99 mechno >= 0 ? mechs[mechno]->name : "",
103 static void cdebughex(int mechno /*or -1*/, const char *msg, const void *ptr,
104 size_t sz, size_t skipbefore,
105 int spc_offset, int dot_offset) {
106 const unsigned char *p;
108 unsigned j= dot_offset;
110 if (!crypto_debug) return;
111 printf("%-8.8s: CRYPTO: %-20s %-10s",
112 uname_result.nodename,
113 mechno >= 0 ? mechs[mechno]->name : "",
116 for (i=0; i<spc_offset; i++, j++) fputs(j&3 ? " " : " ",stdout);
117 for (i=0; i<skipbefore; i++, j++) fputs(j&3 ? ".." : " ..",stdout);
118 for (i=0, p=ptr; i<sz; i++, j++, p++) printf(j&3 ? "%02x" : " %02x",*p);
123 static void cdebugbuf(int mechno /*or -1*/, const char *msg,
124 const struct buffer *buf, int spc_offset, int dot_offset) {
125 cdebughex(mechno, msg, buf->start, buf->size, buf->start - buf->base,
126 spc_offset, dot_offset);
129 void get_random(void *ptr, size_t sz) {
130 static FILE *randfile;
135 randfile= fopen("/dev/urandom","rb");
136 if (!randfile && errno==ENOENT) randfile= fopen("/dev/random","rb");
137 if (!randfile) sysfail("open random number generator");
140 r= fread(ptr,1,sz,randfile);
142 (ferror(randfile) ? sysfail : fail)("cannot read random number generator");
144 cdebughex(-1, "get_random", ptr, sz, 0,0,0);
147 void random_key(void *ptr, size_t sz) {
148 if (encdec_keys_write) {
150 write_must(encdec_keys_fd,ptr,sz,"write keys datastream");
152 read_must(encdec_keys_fd,ptr,sz,"read keys datastream");
153 cdebughex(-1, "random_key", ptr, sz, 0,0,0);
158 static void setnonblock(int fd, int nonblock) {
161 r= fcntl(fd,F_GETFL);
162 if (r==-1) sysfail("fcntl F_GETFL");
163 r= fcntl(fd,F_SETFL, nonblock ? r|O_NONBLOCK : r&~O_NONBLOCK);
164 if (r==-1) sysfail("fcntl F_SETFL");
167 static const struct mechanism *find_mech(const char *name) {
168 const struct mechanism *mech, *const *mechlist;
170 for (mechlist= mechanismlists;
173 for (mech= *mechlist; mech->name; mech++)
174 if (!strcmp(mech->name,name)) return mech;
176 fprintf(stderr,"%s: unknown mechanism: %s\n",programid,name);
180 static void inbound(void) {
181 static int any_recvd;
182 static time_t nextreann;
183 static unsigned long npackets, nbytes;
185 struct sockaddr_in this_saddr;
186 int r, i, different, this_saddrlen;
189 buf_in.start= buf_in.base+1;
190 buf_in.size= buffer_size-2;
192 setnonblock(public_local_fd,1);
193 this_saddrlen= sizeof(this_saddr);
194 r= recvfrom(public_local_fd, buf_in.start, buf_in.size, 0,
195 &this_saddr, &this_saddrlen);
196 if (!r) { diag("empty ciphertext"); return; }
199 if (errno != EAGAIN && errno != EINTR) { sysdiag("receive"); sleep(1); }
202 if (this_saddr.sin_family != AF_INET) {
203 fprintf(stderr,"%s: received unknown AF %lu\n",
204 programid, (unsigned long)this_saddr.sin_family);
207 assert(this_saddrlen == sizeof(this_saddr));
209 assert(r <= buf_in.size);
211 cdebugbuf(-1, "decode", &buf_in, 3,0);
212 for (i=n_mechs-1; i>=0; i--) {
213 emsg= mechs[i]->decode(md_in[i],&buf_in);
216 fprintf(stderr, "%s: bad packet: %s: %s\n",
217 programid, mechs[i]->name, emsg);
219 cdebug(i,"silently discarded");
222 cdebugbuf(i, "decode", &buf_in, 3,0);
226 nbytes += buf_in.size;
229 different= (!public_remote_specd ||
230 public_remote.sin_addr.s_addr != this_saddr.sin_addr.s_addr ||
231 public_remote.sin_port != this_saddr.sin_port);
235 if (public_remote_specd==2) {
236 fprintf(stderr, "%s: packet from unexpected sender %s:%lu\n",
237 programid, inet_ntoa(this_saddr.sin_addr),
238 (unsigned long)ntohs(this_saddr.sin_port));
242 fprintf(stderr, "%s: tunnel open with peer %s:%lu\n",
243 programid, inet_ntoa(this_saddr.sin_addr),
244 (unsigned long)ntohs(this_saddr.sin_port));
246 public_remote_specd= 1;
247 memcpy(&public_remote,&this_saddr,sizeof(public_remote));
249 } else if (!any_recvd) {
253 } else if (reannounce && now() >= nextreann) {
255 fprintf(stderr, "%s: tunnel still open: received %lu packets, %lu bytes\n",
256 programid, npackets, nbytes);
260 goto no_set_reann; /* only reset this if we don't print a message. */
265 nextreann= now() + reannounce;
271 if (!buf_in.size || *buf_in.start != 0300) {
272 *--buf_in.start= 0300;
275 if (buf_in.start[buf_in.size-1] != 0300) {
276 buf_in.start[buf_in.size++]= 0300;
279 setnonblock(private_in_fd,0);
280 write_must(private_in_fd, buf_in.start, buf_in.size, "write down");
283 static void sendpacket(const unsigned char *message, size_t size) {
286 buf_out.start= buf_out.base+maxprefix;
288 memcpy(buf_out.start, message, size);
290 nextsendka= now() + keepalive;
292 cdebugbuf(-1, "encode", &buf_out, 4,0);
293 for (i=0; i<n_mechs; i++) {
294 mechs[i]->encode(md_out[i],&buf_out);
295 cdebugbuf(i, "encode", &buf_out, 4,0);
297 assert(public_remote_specd);
299 setnonblock(public_local_fd,1);
301 r= sendto(public_local_fd, buf_out.start, buf_out.size, 0,
302 &public_remote, sizeof(public_remote));
303 if (r == buf_out.size) break;
304 if (r >= 0) { diag("unexpected short send"); return; }
305 if (errno != EINTR) { sysdiag("send"); return; }
309 static void outbound(void) {
311 unsigned char *after_eaten, *delim;
314 setnonblock(private_out_fd,1);
317 r= read(private_out_fd, accum_buf + accum_used, accum_avail - accum_used);
318 if (!r) { diag("outbound datastream closed, quitting"); exit(0); }
320 if (errno == EAGAIN) return;
321 if (errno == EINTR) continue;
324 assert(accum_used<=accum_avail);
326 after_eaten= accum_buf;
327 while ((delim= memchr(after_eaten, 0300, accum_used))) {
328 this_packet= delim - after_eaten;
329 if (this_packet) sendpacket(after_eaten, this_packet);
330 accum_used -= this_packet+1;
331 after_eaten = delim+1;
333 memmove(accum_buf, after_eaten, accum_used);
335 if (accum_used == accum_avail) {
336 diag("missing interpacket delimiter in output datastream");
342 int main(int argc, const char *const *const argv_in) {
344 const char *const *argv_save;
345 const char *const *argv_done;
346 struct pollfd pollfds[2];
347 int i, polltimeout, r;
352 if (uname(&uname_result)) { perror(PROGRAM ": uname failed"); exit(16); }
353 sprintf(programid, PROGRAM ": %.*s", SYS_NMLN, uname_result.nodename);
355 opt_chars= getarg_string();
356 encdec_keys_write= !!strchr(opt_chars,'w');
357 crypto_debug= !!strchr(opt_chars,'K');
359 public_local_fd= getarg_ulong();
360 private_in_fd= getarg_ulong();
361 private_out_fd= getarg_ulong();
362 encdec_keys_fd= getarg_ulong();
364 mtu2= getarg_ulong() * 2;
365 keepalive= getarg_ulong();
366 timeout= getarg_ulong();
367 reannounce= getarg_ulong();
369 arg= getarg_string();
371 public_remote_specd= 1;
372 public_remote.sin_family= AF_INET;
373 arg_assert(inet_aton(arg,&public_remote.sin_addr));
374 public_remote.sin_port= htons(getarg_ulong());
378 diag("crypto debugging enabled!");
379 setvbuf(stdout,0,_IOLBF,0);
384 while ((arg= *++argv)) {
385 arg_assert(*arg++ == '|');
386 arg_assert(i <= MAXMECHS);
387 mechs[i]= find_mech(arg);
389 cdebug(i,"writer->reader setup");
392 if (encdec_keys_write)
393 mechs[i]->encsetup(&md_out[i], &maxprefix, &maxsuffix);
395 mechs[i]->decsetup(&md_in[i]);
399 cdebug(i,"reader->writer setup");
401 if (encdec_keys_write)
402 mechs[i]->decsetup(&md_in[i]);
404 mechs[i]->encsetup(&md_out[i], &maxprefix, &maxsuffix);
406 assert(argv == argv_done);
412 if (maxprefix<1) maxprefix= 1;
413 if (maxsuffix<1) maxsuffix= 1;
414 buffer_size= mtu2 + maxprefix + maxsuffix;
415 buf_in.base= xmalloc(buffer_size);
416 buf_out.base= xmalloc(buffer_size);
417 accum_avail= mtu2 + 1;
418 accum_buf= xmalloc(accum_avail);
422 pollfds[0].fd= public_local_fd;
423 pollfds[0].events= POLLIN;
424 pollfds[1].fd= private_out_fd;
426 pollfds[1].events= public_remote_specd ? POLLIN : 0;
427 pollfds[0].revents= 0;
428 pollfds[1].revents= 0;
432 if (tnow >= nextsendka && public_remote_specd) sendpacket("\300",1);
433 polltimeout= (nextsendka - tnow)*1000;
438 r= poll(pollfds,2,polltimeout);
440 if (r==-1 && errno==EINTR) continue;
441 if (r==-1) sysfail("poll");
443 if (pollfds[0].revents & (POLLIN|POLLERR)) inbound();
444 if (pollfds[1].revents & (POLLIN|POLLERR)) outbound();