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[tripe] / pkstream / pkstream.c
1 /* -*-c-*-
2 *
3 * Forwarding UDP packets over a stream
4 *
5 * (c) 2003 Straylight/Edgeware
6 */
7
8 /*----- Licensing notice --------------------------------------------------*
9 *
10 * This file is part of Trivial IP Encryption (TrIPE).
11 *
12 * TrIPE is free software: you can redistribute it and/or modify it under
13 * the terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 3 of the License, or (at your
15 * option) any later version.
16 *
17 * TrIPE is distributed in the hope that it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
20 * for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
24 */
25
26 /*----- Header files ------------------------------------------------------*/
27
28 #include "config.h"
29
30 #include <ctype.h>
31 #include <errno.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35
36 #include <sys/time.h>
37 #include <sys/types.h>
38 #include <unistd.h>
39 #include <fcntl.h>
40 #include <sys/uio.h>
41 #include <sys/socket.h>
42 #include <netinet/in.h>
43 #include <arpa/inet.h>
44 #include <netdb.h>
45
46 #include <mLib/alloc.h>
47 #include <mLib/bits.h>
48 #include <mLib/darray.h>
49 #include <mLib/dstr.h>
50 #include <mLib/fdflags.h>
51 #include <mLib/mdwopt.h>
52 #include <mLib/quis.h>
53 #include <mLib/report.h>
54 #include <mLib/sel.h>
55 #include <mLib/selpk.h>
56
57 #include "util.h"
58
59 /*----- Data structures ---------------------------------------------------*/
60
61 typedef union addr {
62 struct sockaddr sa;
63 struct sockaddr_in sin;
64 } addr;
65
66 DA_DECL(addr_v, addr);
67 DA_DECL(str_v, const char *);
68
69 typedef struct pk {
70 struct pk *next; /* Next packet in the chain */
71 octet *p, *o; /* Buffer start and current posn */
72 size_t n; /* Size of packet remaining */
73 } pk;
74
75 typedef struct pkstream {
76 unsigned f; /* Flags... */
77 #define PKF_FULL 1u /* Buffer is full: stop reading */
78 sel_file r, w; /* Read and write selectors */
79 pk *pks, **pk_tail; /* Packet queue */
80 size_t npk, szpk; /* Number and size of data */
81 selpk p; /* Packet parser */
82 } pkstream;
83
84 typedef struct connwait {
85 unsigned f; /* Various flags */
86 #define cwf_port 1u /* Port is defined => listen */
87 sel_file *sfv; /* Selectors */
88 addr_v me, peer; /* Who I'm meant to be; who peer is */
89 } connwait;
90
91 /*----- Static variables --------------------------------------------------*/
92
93 static sel_state sel;
94 static connwait cw;
95 static int fd_udp;
96 static size_t pk_nmax = 128, pk_szmax = 1024*1024;
97
98 /*----- Main code ---------------------------------------------------------*/
99
100 static int nonblockify(int fd)
101 { return (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)); }
102
103 static int cloexec(int fd)
104 { return (fdflags(fd, 0, 0, FD_CLOEXEC, FD_CLOEXEC)); }
105
106 static socklen_t addrsz(const addr *a)
107 {
108 switch (a->sa.sa_family) {
109 case AF_INET: return sizeof(a->sin);
110 default: abort();
111 }
112 }
113
114 static const char *addrstr(const addr *a)
115 {
116 static char buf[128];
117 socklen_t n = sizeof(buf);
118
119 if (getnameinfo(&a->sa, addrsz(a), buf, n, 0, 0, NI_NUMERICHOST))
120 return ("<addrstr failed>");
121 return (buf);
122 }
123
124 static int addreq(const addr *a, const addr *b)
125 {
126 if (a->sa.sa_family != b->sa.sa_family) return (0);
127 switch (a->sa.sa_family) {
128 case AF_INET:
129 return (a->sin.sin_addr.s_addr == b->sin.sin_addr.s_addr);
130 default:
131 abort();
132 }
133 }
134
135 static void initaddr(addr *a)
136 {
137 a->sin.sin_family = AF_INET;
138 a->sin.sin_addr.s_addr = INADDR_ANY;
139 a->sin.sin_port = 0;
140 }
141
142 static void dolisten(void);
143
144 static void doclose(pkstream *p)
145 {
146 pk *pk, *ppk;
147 close(p->w.fd);
148 close(p->p.reader.fd);
149 selpk_destroy(&p->p);
150 if (!(p->f&PKF_FULL)) sel_rmfile(&p->r);
151 if (p->npk) sel_rmfile(&p->w);
152 for (pk = p->pks; pk; pk = ppk) {
153 ppk = pk->next;
154 xfree(pk->p);
155 xfree(pk);
156 }
157 xfree(p);
158 if (cw.f&cwf_port) dolisten();
159 else exit(0);
160 }
161
162 static void rdtcp(octet *b, size_t sz, pkbuf *pk, size_t *k, void *vp)
163 {
164 pkstream *p = vp;
165 size_t pksz;
166
167 if (!sz) { doclose(p); return; }
168 pksz = LOAD16(b);
169 if (pksz + 2 == sz) {
170 DISCARD(write(fd_udp, b + 2, pksz));
171 selpk_want(&p->p, 2);
172 } else {
173 selpk_want(&p->p, pksz + 2);
174 *k = sz;
175 }
176 }
177
178 static void wrtcp(int fd, unsigned mode, void *vp)
179 {
180 #define NPK 16
181 struct iovec iov[NPK];
182 pkstream *p = vp;
183 size_t i;
184 ssize_t n;
185 pk *pk, *ppk;
186
187 for (i = 0, pk = p->pks; i < NPK && pk; i++, pk = pk->next) {
188 iov[i].iov_base = pk->o;
189 iov[i].iov_len = pk->n;
190 }
191
192 if ((n = writev(fd, iov, i)) < 0) {
193 if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
194 moan("couldn't write to TCP socket: %s", strerror(errno));
195 doclose(p);
196 return;
197 }
198
199 p->szpk -= n;
200 for (pk = p->pks; n && pk; pk = ppk) {
201 ppk = pk->next;
202 if (pk->n <= n) {
203 p->npk--;
204 n -= pk->n;
205 xfree(pk->p);
206 xfree(pk);
207 } else {
208 pk->n -= n;
209 pk->o += n;
210 break;
211 }
212 }
213 p->pks = pk;
214 if (!pk) { p->pk_tail = &p->pks; sel_rmfile(&p->w); }
215 if ((p->f&PKF_FULL) && p->npk < pk_nmax && p->szpk < pk_szmax)
216 { p->f &= ~PKF_FULL; sel_addfile(&p->r); }
217 }
218
219 static void rdudp(int fd, unsigned mode, void *vp)
220 {
221 octet buf[65536];
222 ssize_t n;
223 pkstream *p = vp;
224 pk *pk;
225
226 if ((n = read(fd, buf, sizeof(buf))) < 0) {
227 if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
228 return;
229 moan("couldn't read from UDP socket: %s", strerror(errno));
230 return;
231 }
232 pk = xmalloc(sizeof(*pk));
233 pk->next = 0;
234 pk->p = xmalloc(n + 2);
235 STORE16(pk->p, n);
236 memcpy(pk->p + 2, buf, n);
237 pk->o = pk->p;
238 pk->n = n + 2;
239 *p->pk_tail = pk;
240 p->pk_tail = &pk->next;
241 if (!p->npk) sel_addfile(&p->w);
242 sel_force(&p->w);
243 p->npk++;
244 p->szpk += n + 2;
245 if (p->npk >= pk_nmax || p->szpk >= pk_szmax)
246 { sel_rmfile(&p->r); p->f |= PKF_FULL; }
247 }
248
249 static void dofwd(int fd_in, int fd_out)
250 {
251 pkstream *p = xmalloc(sizeof(*p));
252 sel_initfile(&sel, &p->r, fd_udp, SEL_READ, rdudp, p);
253 sel_initfile(&sel, &p->w, fd_out, SEL_WRITE, wrtcp, p);
254 selpk_init(&p->p, &sel, fd_in, rdtcp, p);
255 selpk_want(&p->p, 2);
256 p->pks = 0;
257 p->pk_tail = &p->pks;
258 p->npk = p->szpk = 0;
259 p->f = 0;
260 sel_addfile(&p->r);
261 }
262
263 static void doaccept(int fd_s, unsigned mode, void *p)
264 {
265 int fd;
266 addr a;
267 socklen_t sz = sizeof(a);
268 size_t i, n;
269
270 if ((fd = accept(fd_s, &a.sa, &sz)) < 0) {
271 if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
272 moan("couldn't accept incoming connection: %s", strerror(errno));
273 return;
274 }
275 n = DA_LEN(&cw.peer);
276 if (!n) goto match;
277 for (i = 0; i < n; i++) if (addreq(&a, &DA(&cw.peer)[i])) goto match;
278 moan("rejecting connection from %s", addrstr(&a));
279 close(fd); return;
280 match:
281 if (nonblockify(fd) || cloexec(fd)) {
282 moan("couldn't accept incoming connection: %s", strerror(errno));
283 close(fd); return;
284 }
285 dofwd(fd, fd);
286 n = DA_LEN(&cw.me);
287 for (i = 0; i < n; i++) { close(cw.sfv[i].fd); sel_rmfile(&cw.sfv[i]); }
288 }
289
290 static void dolisten1(const addr *a, sel_file *sf)
291 {
292 int fd;
293 int opt = 1;
294
295 if ((fd = socket(a->sa.sa_family, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
296 setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ||
297 bind(fd, &a->sa, addrsz(a)) ||
298 listen(fd, 1) || nonblockify(fd) || cloexec(fd))
299 die(1, "couldn't set up listening socket: %s", strerror(errno));
300 sel_initfile(&sel, sf, fd, SEL_READ, doaccept, 0);
301 sel_addfile(sf);
302 }
303
304 static void dolisten(void)
305 {
306 size_t i, n;
307
308 n = DA_LEN(&cw.me);
309 for (i = 0; i < n; i++)
310 dolisten1(&DA(&cw.me)[i], &cw.sfv[i]);
311 }
312
313 static void pushaddr(addr_v *av, const addr *a)
314 {
315 DA_ENSURE(av, 1);
316 DA(av)[DA_LEN(av)] = *a;
317 DA_EXTEND(av, 1);
318 }
319
320 #define paf_parse 1u
321 static void parseaddr(const char *host, const char *svc, unsigned f, addr *a)
322 {
323 char *alloc = 0, *sep;
324 struct hostent *h;
325 struct servent *s;
326 char *qq;
327 unsigned long n;
328
329 if (f&paf_parse) {
330 alloc = xstrdup(host);
331 if ((sep = strchr(alloc, ':')) == 0)
332 die(1, "missing port number in address `%s'", host);
333 host = alloc; *sep = 0; svc = sep + 1;
334 }
335
336 if (host) {
337 if ((h = gethostbyname(host)) == 0) die(1, "unknown host `%s'", host);
338 memcpy(&a->sin.sin_addr, h->h_addr, sizeof(a->sin.sin_addr));
339 }
340
341 if (svc) {
342 if ((n = strtoul(svc, &qq, 0)) > 0 && !*qq && n <= 0xffff)
343 a->sin.sin_port = htons(n);
344 else if ((s = getservbyname(svc, "tcp")) != 0)
345 a->sin.sin_port = s->s_port;
346 else
347 die(1, "bad service name/number `%s'", svc);
348 }
349
350 xfree(alloc);
351 }
352
353 static void usage(FILE *fp)
354 {
355 pquis(fp,
356 "Usage: $ [-l PORT] [-b ADDR] [-p ADDR] [-c ADDR:PORT]\n\
357 ADDR:PORT ADDR:PORT\n");
358 }
359
360 static void version(FILE *fp)
361 { pquis(fp, "$, tripe version " VERSION "\n"); }
362
363 static void help(FILE *fp)
364 {
365 version(fp);
366 fputc('\n', fp);
367 usage(fp);
368 fputs("\n\
369 Options:\n\
370 \n\
371 -h, --help Display this help text.\n\
372 -v, --version Display version number.\n\
373 -u, --usage Display pointless usage message.\n\
374 \n\
375 -l, --listen=PORT Listen for connections to TCP PORT.\n\
376 -p, --peer=ADDR Only accept connections from IP ADDR.\n\
377 -b, --bind=ADDR Bind to ADDR before connecting.\n\
378 -c, --connect=ADDR:PORT Connect to IP ADDR, TCP PORT.\n\
379 \n\
380 Forwards UDP packets over a reliable stream. By default, uses stdin and\n\
381 stdout; though it can use TCP sockets instead.\n\
382 ", fp);
383 }
384
385 int main(int argc, char *argv[])
386 {
387 unsigned f = 0;
388 str_v bindhosts = DA_INIT, peerhosts = DA_INIT;
389 const char *bindsvc = 0;
390 addr bindaddr;
391 const char *connhost = 0;
392 addr tmpaddr;
393 int fd = -1;
394 int len = 65536;
395 size_t i, n;
396
397 #define f_bogus 1u
398
399 cw.f = 0;
400
401 ego(argv[0]);
402 sel_init(&sel);
403 for (;;) {
404 static struct option opt[] = {
405 { "help", 0, 0, 'h' },
406 { "version", 0, 0, 'v' },
407 { "usage", 0, 0, 'u' },
408 { "listen", OPTF_ARGREQ, 0, 'l' },
409 { "peer", OPTF_ARGREQ, 0, 'p' },
410 { "bind", OPTF_ARGREQ, 0, 'b' },
411 { "connect", OPTF_ARGREQ, 0, 'c' },
412 { 0, 0, 0, 0 }
413 };
414 int i;
415
416 i = mdwopt(argc, argv, "hvul:p:b:c:", opt, 0, 0, 0);
417 if (i < 0)
418 break;
419 switch (i) {
420 case 'h': help(stdout); exit(0);
421 case 'v': version(stdout); exit(0);
422 case 'u': usage(stdout); exit(0);
423 case 'l': bindsvc = optarg; break;
424 case 'p': DA_PUSH(&peerhosts, optarg); break;
425 case 'b': DA_PUSH(&bindhosts, optarg); break;
426 case 'c': connhost = optarg; break;
427 default: f |= f_bogus; break;
428 }
429 }
430 if (optind + 2 != argc || (f&f_bogus)) { usage(stderr); exit(1); }
431
432 if (DA_LEN(&bindhosts) && !bindsvc && !connhost)
433 die(1, "bind addr only makes sense when listening or connecting");
434 if (DA_LEN(&peerhosts) && !bindsvc)
435 die(1, "peer addr only makes sense when listening");
436 if (bindsvc && connhost)
437 die(1, "can't listen and connect");
438
439 DA_CREATE(&cw.me); DA_CREATE(&cw.peer);
440
441 n = DA_LEN(&bindhosts);
442 if (n || bindsvc) {
443 if (!n) {
444 initaddr(&tmpaddr);
445 parseaddr(0, bindsvc, 0, &tmpaddr);
446 pushaddr(&cw.me, &tmpaddr);
447 } else if (!bindsvc) {
448 if (n != 1) die(1, "can only bind to one address as client");
449 initaddr(&bindaddr);
450 parseaddr(DA(&bindhosts)[0], 0, 0, &bindaddr);
451 } else for (i = 0; i < n; i++) {
452 initaddr(&tmpaddr);
453 parseaddr(DA(&bindhosts)[i], bindsvc, 0, &tmpaddr);
454 pushaddr(&cw.me, &tmpaddr);
455 }
456 if (bindsvc) {
457 cw.f |= cwf_port;
458 n = DA_LEN(&cw.me);
459 cw.sfv = xmalloc(n*sizeof(*cw.sfv));
460 }
461 }
462
463 n = DA_LEN(&peerhosts);
464 if (n) {
465 for (i = 0; i < n; i++) {
466 initaddr(&tmpaddr);
467 parseaddr(DA(&peerhosts)[0], 0, 0, &tmpaddr);
468 pushaddr(&cw.peer, &tmpaddr);
469 }
470 }
471
472 if (connhost) {
473 initaddr(&tmpaddr);
474 parseaddr(connhost, 0, paf_parse, &tmpaddr);
475 if ((fd = socket(tmpaddr.sa.sa_family, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
476 (DA_LEN(&bindhosts) &&
477 bind(fd, &bindaddr.sa, addrsz(&bindaddr))) ||
478 connect(fd, &tmpaddr.sa, addrsz(&tmpaddr)))
479 die(1, "couldn't connect to TCP server: %s", strerror(errno));
480 if (nonblockify(fd) || cloexec(fd))
481 die(1, "couldn't connect to TCP server: %s", strerror(errno));
482 }
483
484 initaddr(&tmpaddr);
485 parseaddr(argv[optind], 0, paf_parse, &tmpaddr);
486 if ((fd_udp = socket(tmpaddr.sa.sa_family, SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
487 nonblockify(fd_udp) || cloexec(fd_udp) ||
488 setsockopt(fd_udp, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
489 setsockopt(fd_udp, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) ||
490 bind(fd_udp, &tmpaddr.sa, addrsz(&tmpaddr)))
491 die(1, "couldn't set up UDP socket: %s", strerror(errno));
492 initaddr(&tmpaddr);
493 parseaddr(argv[optind + 1], 0, paf_parse, &tmpaddr);
494 if (connect(fd_udp, &tmpaddr.sa, addrsz(&tmpaddr)))
495 die(1, "couldn't set up UDP socket: %s", strerror(errno));
496
497 if (bindsvc) dolisten();
498 else if (connhost) dofwd(fd, fd);
499 else dofwd(STDIN_FILENO, STDOUT_FILENO);
500
501 for (;;) {
502 if (sel_select(&sel) && errno != EINTR)
503 die(1, "select failed: %s", strerror(errno));
504 }
505 return (0);
506 }
507
508 /*----- That's all, folks -------------------------------------------------*/
Trivial IP Encryption: a simple VPN