2 * Encrypting tunnel for userv-ipif tunnels, actual implementation
6 * udptunnel-forwarder <optchars>
7 * <public-local-fd> <private-in-fd> <private-out-fd>
9 * <mtu> <keepalive> <timeout>
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 must be numeric. There is very little argument checking.
31 * 0 terminated due to outbound packet stream EOF
38 * Copyright (C) 2000 Ian Jackson
40 * This is free software; you can redistribute it and/or modify it
41 * under the terms of the GNU General Public License as published by
42 * the Free Software Foundation; either version 2 of the License, or
43 * (at your option) any later version.
45 * This program is distributed in the hope that it will be useful, but
46 * WITHOUT ANY WARRANTY; without even the implied warranty of
47 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
48 * General Public License for more details.
50 * You should have received a copy of the GNU General Public License
51 * along with userv-utils; if not, write to the Free Software
52 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
55 #include <sys/socket.h>
56 #include <netinet/in.h>
57 #include <arpa/inet.h>
58 #include <sys/utsname.h>
69 #include "forwarder.h"
73 static size_t buffer_size;
74 static struct utsname uname_result;
76 static const char *opt_chars;
77 static int public_local_fd, private_in_fd, private_out_fd;
78 static int mtu2, keepalive, timeout;
79 static int public_remote_specd;
80 static struct sockaddr_in public_remote;
81 static int encdec_keys_fd, encdec_keys_write, crypto_debug;
83 static const struct mechanism *mechs[MAXMECHS];
85 static struct mechdata *md_in[MAXMECHS], *md_out[MAXMECHS];
86 static size_t maxprefix, maxsuffix;
88 static struct buffer buf_in, buf_out;
89 static unsigned char *accum_buf;
90 static size_t accum_used, accum_avail;
92 static time_t nextsendka;
94 static void cdebug(int mechno /*or -1*/, const char *msg) {
95 if (!crypto_debug) return;
96 printf("%-8.8s: CRYPTO: %-20s %s\n",
97 uname_result.nodename,
98 mechno >= 0 ? mechs[mechno]->name : "",
102 static void cdebughex(int mechno /*or -1*/, const char *msg, const void *ptr,
103 size_t sz, size_t skipbefore,
104 int spc_offset, int dot_offset) {
105 const unsigned char *p;
107 unsigned j= dot_offset;
109 if (!crypto_debug) return;
110 printf("%-8.8s: CRYPTO: %-20s %-10s",
111 uname_result.nodename,
112 mechno >= 0 ? mechs[mechno]->name : "",
115 for (i=0; i<spc_offset; i++, j++) fputs(j&3 ? " " : " ",stdout);
116 for (i=0; i<skipbefore; i++, j++) fputs(j&3 ? ".." : " ..",stdout);
117 for (i=0, p=ptr; i<sz; i++, j++, p++) printf(j&3 ? "%02x" : " %02x",*p);
122 static void cdebugbuf(int mechno /*or -1*/, const char *msg,
123 const struct buffer *buf, int spc_offset, int dot_offset) {
124 cdebughex(mechno, msg, buf->start, buf->size, buf->start - buf->base,
125 spc_offset, dot_offset);
128 void get_random(void *ptr, size_t sz) {
129 static FILE *randfile;
134 randfile= fopen("/dev/urandom","rb");
135 if (!randfile && errno==ENOENT) randfile= fopen("/dev/random","rb");
136 if (!randfile) sysfail("open random number generator");
139 r= fread(ptr,1,sz,randfile);
141 (ferror(randfile) ? sysfail : fail)("cannot read random number generator");
143 cdebughex(-1, "get_random", ptr, sz, 0,0,0);
146 void random_key(void *ptr, size_t sz) {
147 if (encdec_keys_write) {
149 write_must(encdec_keys_fd,ptr,sz,"write keys datastream");
151 read_must(encdec_keys_fd,ptr,sz,"read keys datastream");
152 cdebughex(-1, "random_key", ptr, sz, 0,0,0);
157 static void setnonblock(int fd, int nonblock) {
160 r= fcntl(fd,F_GETFL);
161 if (r==-1) sysfail("fcntl F_GETFL");
162 r= fcntl(fd,F_SETFL, nonblock ? r|O_NONBLOCK : r&~O_NONBLOCK);
163 if (r==-1) sysfail("fcntl F_SETFL");
166 static const struct mechanism *find_mech(const char *name) {
167 const struct mechanism *mech, *const *mechlist;
169 for (mechlist= mechanismlists;
172 for (mech= *mechlist; mech->name; mech++)
173 if (!strcmp(mech->name,name)) return mech;
175 fprintf(stderr,"%s: unknown mechanism: %s\n",programid,name);
179 static void inbound(void) {
180 static int any_recvd;
182 struct sockaddr_in this_saddr;
183 int r, i, different, this_saddrlen;
186 buf_in.start= buf_in.base+1;
187 buf_in.size= buffer_size-2;
189 setnonblock(public_local_fd,1);
190 this_saddrlen= sizeof(this_saddr);
191 r= recvfrom(public_local_fd, buf_in.start, buf_in.size, 0,
192 &this_saddr, &this_saddrlen);
193 if (!r) { diag("empty ciphertext"); return; }
196 if (errno != EAGAIN && errno != EINTR) { sysdiag("receive"); sleep(1); }
199 if (this_saddr.sin_family != AF_INET) {
200 fprintf(stderr,"%s: received unknown AF %lu\n",
201 programid, (unsigned long)this_saddr.sin_family);
204 assert(this_saddrlen == sizeof(this_saddr));
206 assert(r <= buf_in.size);
208 cdebugbuf(-1, "decode", &buf_in, 3,0);
209 for (i=n_mechs-1; i>=0; i--) {
210 emsg= mechs[i]->decode(md_in[i],&buf_in);
213 fprintf(stderr, "%s: bad packet: %s: %s\n",
214 programid, mechs[i]->name, emsg);
216 cdebug(i,"silently discarded");
219 cdebugbuf(i, "decode", &buf_in, 3,0);
224 different= (!public_remote_specd ||
225 public_remote.sin_addr.s_addr != this_saddr.sin_addr.s_addr ||
226 public_remote.sin_port != this_saddr.sin_port);
230 if (public_remote_specd==2) {
231 fprintf(stderr, "%s: packet from unexpected sender %s:%lu\n",
232 programid, inet_ntoa(this_saddr.sin_addr),
233 (unsigned long)ntohs(this_saddr.sin_port));
237 fprintf(stderr, "%s: tunnel open with peer %s:%lu\n",
238 programid, inet_ntoa(this_saddr.sin_addr),
239 (unsigned long)ntohs(this_saddr.sin_port));
241 public_remote_specd= 1;
242 memcpy(&public_remote,&this_saddr,sizeof(public_remote));
244 } else if (!any_recvd) {
252 if (!buf_in.size || *buf_in.start != 0300) {
253 *--buf_in.start= 0300;
256 if (buf_in.start[buf_in.size-1] != 0300) {
257 buf_in.start[buf_in.size++]= 0300;
260 setnonblock(private_in_fd,0);
261 write_must(private_in_fd, buf_in.start, buf_in.size, "write down");
264 static void sendpacket(const unsigned char *message, size_t size) {
267 buf_out.start= buf_out.base+maxprefix;
269 memcpy(buf_out.start, message, size);
271 nextsendka= now() + keepalive;
273 cdebugbuf(-1, "encode", &buf_out, 4,0);
274 for (i=0; i<n_mechs; i++) {
275 mechs[i]->encode(md_out[i],&buf_out);
276 cdebugbuf(i, "encode", &buf_out, 4,0);
278 assert(public_remote_specd);
280 setnonblock(public_local_fd,1);
282 r= sendto(public_local_fd, buf_out.start, buf_out.size, 0,
283 &public_remote, sizeof(public_remote));
284 if (r == buf_out.size) break;
285 if (r >= 0) { diag("unexpected short send"); return; }
286 if (errno != EINTR) { sysdiag("send"); return; }
290 static void outbound(void) {
292 unsigned char *after_eaten, *delim;
295 setnonblock(private_out_fd,1);
298 r= read(private_out_fd, accum_buf + accum_used, accum_avail - accum_used);
299 if (!r) { diag("outbound datastream closed, quitting"); exit(0); }
301 if (errno == EAGAIN) return;
302 if (errno == EINTR) continue;
305 assert(accum_used<=accum_avail);
307 after_eaten= accum_buf;
308 while ((delim= memchr(after_eaten, 0300, accum_used))) {
309 this_packet= delim - after_eaten;
310 if (this_packet) sendpacket(after_eaten, this_packet);
311 accum_used -= this_packet+1;
312 after_eaten = delim+1;
314 memmove(accum_buf, after_eaten, accum_used);
316 if (accum_used == accum_avail) {
317 diag("missing interpacket delimiter in output datastream");
323 int main(int argc, const char *const *const argv_in) {
325 const char *const *argv_save;
326 const char *const *argv_done;
327 struct pollfd pollfds[2];
328 int i, polltimeout, r;
333 if (uname(&uname_result)) { perror(PROGRAM ": uname failed"); exit(16); }
334 sprintf(programid, PROGRAM ": %.*s", SYS_NMLN, uname_result.nodename);
336 opt_chars= getarg_string();
337 encdec_keys_write= !!strchr(opt_chars,'w');
338 crypto_debug= !!strchr(opt_chars,'K');
340 public_local_fd= getarg_ulong();
341 private_in_fd= getarg_ulong();
342 private_out_fd= getarg_ulong();
343 encdec_keys_fd= getarg_ulong();
345 mtu2= getarg_ulong() * 2;
346 keepalive= getarg_ulong();
347 timeout= getarg_ulong();
349 arg= getarg_string();
351 public_remote_specd= 1;
352 public_remote.sin_family= AF_INET;
353 arg_assert(inet_aton(arg,&public_remote.sin_addr));
354 public_remote.sin_port= htons(getarg_ulong());
358 diag("crypto debugging enabled!");
359 setvbuf(stdout,0,_IOLBF,0);
364 while ((arg= *++argv)) {
365 arg_assert(*arg++ == '|');
366 arg_assert(i <= MAXMECHS);
367 mechs[i]= find_mech(arg);
369 cdebug(i,"writer->reader setup");
372 if (encdec_keys_write)
373 mechs[i]->encsetup(&md_out[i], &maxprefix, &maxsuffix);
375 mechs[i]->decsetup(&md_in[i]);
379 cdebug(i,"reader->writer setup");
381 if (encdec_keys_write)
382 mechs[i]->decsetup(&md_in[i]);
384 mechs[i]->encsetup(&md_out[i], &maxprefix, &maxsuffix);
386 assert(argv == argv_done);
392 if (maxprefix<1) maxprefix= 1;
393 if (maxsuffix<1) maxsuffix= 1;
394 buffer_size= mtu2 + maxprefix + maxsuffix;
395 buf_in.base= xmalloc(buffer_size);
396 buf_out.base= xmalloc(buffer_size);
397 accum_avail= mtu2 + 1;
398 accum_buf= xmalloc(accum_avail);
402 pollfds[0].fd= public_local_fd;
403 pollfds[0].events= POLLIN;
404 pollfds[1].fd= private_out_fd;
406 pollfds[1].events= public_remote_specd ? POLLIN : 0;
407 pollfds[0].revents= 0;
408 pollfds[1].revents= 0;
412 if (tnow >= nextsendka && public_remote_specd) sendpacket("\300",1);
413 polltimeout= (nextsendka - tnow)*1000;
418 r= poll(pollfds,2,polltimeout);
420 if (r==-1 && errno==EINTR) continue;
421 if (r==-1) sysfail("poll");
423 if (pollfds[0].revents & (POLLIN|POLLERR)) inbound();
424 if (pollfds[1].revents & (POLLIN|POLLERR)) outbound();