Commit | Line | Data |
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b9066fbb | 1 | /* -*-c-*- |
b9066fbb | 2 | * |
3 | * Tunnel packets via SLIP | |
4 | * | |
5 | * (c) 2005 Straylight/Edgeware | |
6 | */ | |
7 | ||
e04c2d50 | 8 | /*----- Licensing notice --------------------------------------------------* |
b9066fbb | 9 | * |
10 | * This file is part of Trivial IP Encryption (TrIPE). | |
11 | * | |
12 | * TrIPE is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
e04c2d50 | 16 | * |
b9066fbb | 17 | * TrIPE is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
e04c2d50 | 21 | * |
b9066fbb | 22 | * You should have received a copy of the GNU General Public License |
23 | * along with TrIPE; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
27 | /*----- Header files ------------------------------------------------------*/ | |
28 | ||
42da2a58 | 29 | #define TUN_INTERNALS |
30 | ||
b9066fbb | 31 | #include "tripe.h" |
32 | ||
42da2a58 | 33 | /*----- Data structures ---------------------------------------------------*/ |
34 | ||
35 | typedef struct slipif { | |
36 | struct slipif *next; /* Next one in the list */ | |
37 | int ifd, ofd; /* File descriptors to talk on */ | |
38 | char *name; /* Interface name */ | |
39 | pid_t kid; /* Child process id */ | |
40 | unsigned f; /* Various flags */ | |
41 | # define F_INUSE 1u /* Interface is in use */ | |
42 | # define F_DYNAMIC 2u /* Interface found dynamically */ | |
43 | } slipif; | |
44 | ||
45 | struct tunnel { | |
46 | const tunnel_ops *ops; /* Pointer to operations */ | |
47 | slipif *sl; /* My interface record */ | |
48 | sel_file f; /* Selector for SLIP tty */ | |
49 | struct peer *p; /* Pointer to my peer */ | |
50 | unsigned st; /* Current parser state */ | |
51 | # define ST_ESC 1u /* Last saw an escape character */ | |
52 | # define ST_BAD 2u /* This packet is malformed */ | |
574318e7 | 53 | # define ST_MASK 3u /* Mask for the above bits */ |
42da2a58 | 54 | # define ST_EOF 4u /* File descriptor reported EOF */ |
898975ee | 55 | # define ST_BROKEN 8u /* Sending side is broken */ |
42da2a58 | 56 | size_t n; /* Number of bytes used in buffer */ |
57 | octet buf[PKBUFSZ]; /* Buffer for incoming data */ | |
e04c2d50 | 58 | }; |
42da2a58 | 59 | |
b9066fbb | 60 | /*----- Static variables --------------------------------------------------*/ |
61 | ||
62 | static slipif *slipifs; /* List of available interfaces */ | |
98fdb08d | 63 | static const char *slipcmd; /* Script to make new interfaces */ |
b9066fbb | 64 | |
65 | /*----- Main code ---------------------------------------------------------*/ | |
66 | ||
b9066fbb | 67 | /* --- @t_read@ --- * |
68 | * | |
69 | * Arguments: @int fd@ = file descriptor to read | |
70 | * @unsigned mode@ = what's happened | |
71 | * @void *v@ = pointer to tunnel block | |
72 | * | |
73 | * Returns: --- | |
74 | * | |
75 | * Use: Reads data from the tunnel. | |
76 | */ | |
77 | ||
78 | static void t_read(int fd, unsigned mode, void *v) | |
79 | { | |
80 | tunnel *t = v; | |
81 | ssize_t n; | |
82 | const octet *p, *l, *ll; | |
83 | octet *q; | |
84 | unsigned st; | |
85 | octet o; | |
86 | buf b; | |
87 | ||
88 | /* --- Read the input data --- */ | |
89 | ||
90 | n = read(fd, buf_t, sizeof(buf_t)); | |
91 | if (n < 0) { | |
92 | if (errno == EINTR || | |
98fdb08d | 93 | #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN |
b9066fbb | 94 | errno == EWOULDBLOCK || |
95 | #endif | |
96 | errno == EAGAIN) | |
97 | return; | |
b476642f MW |
98 | a_warn("TUN", "%s", p_ifname(t->p), "slip", |
99 | "read-error", "?ERRNO", A_END); | |
b9066fbb | 100 | return; |
101 | } | |
102 | if (!n) { | |
72917fe7 | 103 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "eof", A_END); |
574318e7 | 104 | t->st = (t->st & ~ST_MASK) | ST_EOF; |
b9066fbb | 105 | sel_rmfile(&t->f); |
106 | return; | |
107 | } | |
108 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 109 | trace_block(T_PACKET, "tun-slip: SLIP-encapsulated data", |
b9066fbb | 110 | buf_t, n); |
111 | }) | |
112 | ||
113 | /* --- Decapsulate the packet --- */ | |
114 | ||
115 | for (p = buf_t, l = p + n, st = t->st, | |
116 | q = t->buf + t->n, ll = t->buf + sizeof(t->buf); | |
117 | p < l; | |
118 | p++) { | |
119 | o = *p; | |
120 | switch (o) { | |
121 | case SL_END: | |
42da2a58 | 122 | if (st & ST_BAD) |
b9066fbb | 123 | ; |
c85c1712 | 124 | else if (st & ST_ESC) { |
72917fe7 | 125 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "escape-end", A_END); |
c85c1712 MW |
126 | st |= ST_BAD; |
127 | } else if (q == t->buf) { | |
060ca767 | 128 | T( trace(T_TUNNEL, "tun-slip: empty packet"); ) |
b9066fbb | 129 | } else { |
130 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 131 | trace(T_TUNNEL, "tun-slip: packet arrived"); |
132 | trace_block(T_PACKET, "tun-slip: packet contents", | |
b9066fbb | 133 | t->buf, q - t->buf); |
134 | }) | |
135 | buf_init(&b, t->buf, q - t->buf); | |
136 | p_tun(t->p, &b); | |
137 | } | |
138 | q = t->buf; | |
574318e7 | 139 | st &= ~ST_MASK; |
b9066fbb | 140 | break; |
141 | case SL_ESC: | |
42da2a58 | 142 | if ((st & ST_ESC) && !(st & ST_BAD)) { |
72917fe7 | 143 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "bad-escape", A_END); |
42da2a58 | 144 | st |= ST_BAD; |
b9066fbb | 145 | } else |
42da2a58 | 146 | st |= ST_ESC; |
b9066fbb | 147 | break; |
148 | case SL_ESCEND: | |
42da2a58 | 149 | if (st & ST_ESC) |
b9066fbb | 150 | o = SL_END; |
151 | goto emit; | |
152 | case SL_ESCESC: | |
42da2a58 | 153 | if (st & ST_ESC) |
b9066fbb | 154 | o = SL_ESC; |
155 | goto emit; | |
156 | default: | |
42da2a58 | 157 | if ((st & ST_ESC) && !(st & ST_BAD)) { |
72917fe7 | 158 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "bad-escape", A_END); |
42da2a58 | 159 | st |= ST_BAD; |
b9066fbb | 160 | } |
161 | emit: | |
42da2a58 | 162 | if (!(st & ST_BAD)) { |
b9066fbb | 163 | if (q < ll) |
164 | *q++ = o; | |
165 | else { | |
72917fe7 | 166 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "overflow", A_END); |
42da2a58 | 167 | st |= ST_BAD; |
b9066fbb | 168 | } |
169 | } | |
42da2a58 | 170 | st &= ~ST_ESC; |
b9066fbb | 171 | break; |
172 | } | |
173 | } | |
174 | ||
175 | t->n = q - t->buf; | |
176 | t->st = st; | |
177 | } | |
178 | ||
42da2a58 | 179 | /* --- @t_init@ --- * |
b9066fbb | 180 | * |
181 | * Arguments: --- | |
182 | * | |
183 | * Returns: --- | |
184 | * | |
185 | * Use: Initializes the tunneling system. Maybe this will require | |
186 | * opening file descriptors or something. | |
187 | */ | |
188 | ||
42da2a58 | 189 | static void t_init(void) |
b9066fbb | 190 | { |
191 | char *p, *q; | |
192 | dstr d = DSTR_INIT; | |
193 | slipif *sl, **tail = &slipifs; | |
194 | unsigned long uli, ulo; | |
195 | size_t n; | |
196 | ||
b9066fbb | 197 | if ((p = getenv("TRIPE_SLIPIF")) == 0) |
42da2a58 | 198 | return; |
98fdb08d | 199 | |
200 | /* --- Build the list of available interfaces --- */ | |
201 | ||
b9066fbb | 202 | dstr_puts(&d, p); |
203 | ||
204 | p = d.buf; | |
205 | for (;;) { | |
98fdb08d | 206 | if (*p == '/' || *p == '.') { |
207 | slipcmd = p; | |
060ca767 | 208 | T( trace(T_TUNNEL, "tun-slip: declared slip command `%s'", slipcmd); ) |
98fdb08d | 209 | break; |
210 | } | |
b9066fbb | 211 | uli = strtoul(p, &q, 0); |
212 | if (uli > INT_MAX || q == p) | |
213 | goto whine; | |
214 | if (*q != ',') | |
215 | ulo = uli; | |
216 | else { | |
217 | p = q + 1; | |
218 | ulo = strtoul(p, &q, 0); | |
219 | if (ulo > INT_MAX || q == p) | |
220 | goto whine; | |
221 | } | |
222 | if (*q != '=' || (n = strcspn(q + 1, ":")) == 0) | |
223 | goto whine; | |
224 | sl = CREATE(slipif); | |
225 | sl->next = 0; | |
226 | sl->ifd = uli; | |
98fdb08d | 227 | fdflags(sl->ifd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); |
228 | fdflags(sl->ofd, O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC); | |
b9066fbb | 229 | sl->ofd = ulo; |
230 | sl->name = xmalloc(n + 1); | |
98fdb08d | 231 | sl->kid = -1; |
b9066fbb | 232 | sl->f = 0; |
233 | memcpy(sl->name, q + 1, n); | |
234 | sl->name[n] = 0; | |
235 | *tail = sl; | |
236 | tail = &sl->next; | |
060ca767 | 237 | T( trace(T_TUNNEL, "tun-slip: declared slipif %d,%d=%s", |
b9066fbb | 238 | sl->ifd, sl->ofd, sl->name); ) |
239 | p = q + n + 1; | |
240 | if (!*p) | |
241 | break; | |
242 | p++; | |
243 | } | |
244 | return; | |
245 | ||
246 | whine: | |
42da2a58 | 247 | moan("bad slip interface list"); |
b9066fbb | 248 | } |
249 | ||
898975ee MW |
250 | /* --- @t_broken@ --- * |
251 | * | |
252 | * Arguments: @tunnel *t@ = pointer to the tunnel | |
253 | * | |
254 | * Returns: --- | |
255 | * | |
256 | * Use: Marks the tunnel as broken and reports an error. | |
257 | */ | |
258 | ||
259 | static void t_broken(tunnel *t) | |
260 | { | |
261 | if (errno == EINTR || | |
262 | #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN | |
263 | errno == EWOULDBLOCK || | |
264 | #endif | |
265 | errno == EAGAIN) | |
266 | return; | |
267 | a_warn("TUN", "%s", p_ifname(t->p), "slip", | |
268 | "write-error", "?ERRNO", A_END); | |
269 | T( trace(T_TUNNEL, "tun-slip: marking tunnel broken"); ) | |
270 | t->st |= ST_BROKEN; | |
271 | } | |
272 | ||
42da2a58 | 273 | /* --- @t_create@ --- * |
b9066fbb | 274 | * |
42da2a58 | 275 | * Arguments: @peer *p@ = pointer to peer block |
eb5f3fea | 276 | * @int fd@ = file descriptor of tunnel device (unused) |
72917fe7 | 277 | * @char **ifn@ = where to put the interface name |
b9066fbb | 278 | * |
42da2a58 | 279 | * Returns: A tunnel block if it worked, or null on failure. |
b9066fbb | 280 | * |
281 | * Use: Initializes a new tunnel. | |
282 | */ | |
283 | ||
eb5f3fea | 284 | static tunnel *t_create(peer *p, int fd, char **ifn) |
b9066fbb | 285 | { |
98fdb08d | 286 | slipif *sl = 0; |
287 | int pin[2] = { -1, -1 }, pout[2] = { -1, -1 }; | |
b9537f3b | 288 | mdup_fd md[2]; |
98fdb08d | 289 | pid_t kid = -1; |
290 | dstr d = DSTR_INIT; | |
291 | unsigned char ch; | |
42da2a58 | 292 | tunnel *t; |
8187950b | 293 | static const octet end[] = { SL_END, SL_END }; |
b9066fbb | 294 | |
98fdb08d | 295 | /* --- Try to find a spare static interface --- */ |
296 | ||
b9066fbb | 297 | for (sl = slipifs; sl; sl = sl->next) { |
42da2a58 | 298 | if (!(sl->f & F_INUSE)) { |
060ca767 | 299 | T( trace(T_TUNNEL, "tun-slip: %s using static slipif %s", |
98fdb08d | 300 | p_name(p), sl->name); ) |
b9066fbb | 301 | goto found; |
98fdb08d | 302 | } |
b9066fbb | 303 | } |
98fdb08d | 304 | |
305 | /* --- If no dynamic interfaces are available, give up --- */ | |
306 | ||
307 | if (!slipcmd) { | |
f43df819 | 308 | a_warn("TUN", "-", "slip", "no-slip-interfaces", A_END); |
98fdb08d | 309 | goto fail; |
310 | } | |
311 | ||
312 | /* --- Fork off a child process to create a dynamic SLIP interface --- */ | |
313 | ||
314 | if (pipe(pin) || pipe(pout)) { | |
f43df819 | 315 | a_warn("TUN", "-", "slip", "pipe-error", "?ERRNO", A_END); |
98fdb08d | 316 | goto fail; |
317 | } | |
318 | if ((kid = fork()) < 0) { | |
f43df819 | 319 | a_warn("TUN", "-", "slip", "fork-error", "?ERRNO", A_END); |
98fdb08d | 320 | goto fail; |
321 | } | |
322 | if (!kid) { | |
b9537f3b MW |
323 | close(pin[1]); close(pout[0]); |
324 | md[0].cur = pin[0]; md[0].want = STDIN_FILENO; | |
2d5c3e54 | 325 | md[1].cur = pout[1]; md[1].want = STDOUT_FILENO; |
b9537f3b | 326 | mdup(md, 2); |
98fdb08d | 327 | execlp(slipcmd, slipcmd, p_name(p), (char *)0); |
328 | _exit(127); | |
329 | } | |
330 | ||
331 | /* --- Read the interface name --- */ | |
332 | ||
333 | sl = CREATE(slipif); | |
334 | close(pin[0]); pin[0] = -1; | |
335 | close(pout[1]); pout[1] = -1; | |
336 | for (;;) { | |
337 | errno = EIO; | |
338 | if (read(pout[0], &ch, 1) != 1 || ch == SL_END) { | |
f43df819 | 339 | a_warn("TUN", "-", "slip", "read-ifname-failed", "?ERRNO", A_END); |
98fdb08d | 340 | goto fail; |
341 | } | |
342 | if (ch == '\n') | |
343 | break; | |
344 | DPUTC(&d, (char)ch); | |
345 | } | |
346 | DPUTZ(&d); | |
347 | sl->name = xstrdup(d.buf); | |
348 | sl->ifd = pout[0]; | |
349 | sl->ofd = pin[1]; | |
350 | sl->kid = kid; | |
351 | sl->next = 0; | |
42da2a58 | 352 | sl->f = F_DYNAMIC; |
060ca767 | 353 | T( trace(T_TUNNEL, "tun-slip: %s using dynamic slipif %s", |
98fdb08d | 354 | p_name(p), sl->name); ) |
355 | fdflags(pout[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); | |
356 | fdflags(pin[1], O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC); | |
357 | ||
358 | /* --- Set up the new tunnel --- */ | |
b9066fbb | 359 | |
360 | found: | |
42da2a58 | 361 | t = CREATE(tunnel); |
362 | t->ops = &tun_slip; | |
b9066fbb | 363 | t->p = p; |
364 | t->sl = sl; | |
365 | t->st = 0; | |
366 | t->n = 0; | |
42da2a58 | 367 | sl->f |= F_INUSE; |
b9066fbb | 368 | sel_initfile(&sel, &t->f, sl->ifd, SEL_READ, t_read, t); |
369 | sel_addfile(&t->f); | |
898975ee MW |
370 | if (write(sl->ofd, end, sizeof(end)) < 0) |
371 | t_broken(t); | |
72917fe7 | 372 | *ifn = xstrdup(sl->name); |
98fdb08d | 373 | dstr_destroy(&d); |
42da2a58 | 374 | return (t); |
98fdb08d | 375 | |
376 | /* --- Tidy up after a failure --- */ | |
377 | ||
378 | fail: | |
379 | #define CLOSE(fd) do if (fd != -1) close(fd); while (0) | |
380 | CLOSE(pin[0]); CLOSE(pout[0]); | |
381 | CLOSE(pin[1]); CLOSE(pout[1]); | |
382 | #undef CLOSE | |
383 | if (kid != -1) kill(kid, SIGTERM); | |
42da2a58 | 384 | if (sl && (sl->f & F_DYNAMIC)) DESTROY(sl); |
98fdb08d | 385 | dstr_destroy(&d); |
42da2a58 | 386 | return (0); |
b9066fbb | 387 | } |
388 | ||
72917fe7 | 389 | /* --- @t_setifname@ --- * |
b9066fbb | 390 | * |
391 | * Arguments: @tunnel *t@ = pointer to tunnel block | |
72917fe7 | 392 | * @const char *ifn@ = new interface name |
b9066fbb | 393 | * |
72917fe7 MW |
394 | * Returns: --- |
395 | * | |
396 | * Use: Updates the interface name of a slip interface. | |
b9066fbb | 397 | */ |
398 | ||
72917fe7 MW |
399 | static void t_setifname(tunnel *t, const char *ifn) |
400 | { xfree(t->sl->name); t->sl->name = xstrdup(ifn); } | |
b9066fbb | 401 | |
42da2a58 | 402 | /* --- @t_inject@ --- * |
b9066fbb | 403 | * |
404 | * Arguments: @tunnel *t@ = pointer to tunnel block | |
405 | * @buf *b@ = buffer to send | |
406 | * | |
407 | * Returns: --- | |
408 | * | |
409 | * Use: Injects a packet into the local network stack. | |
410 | */ | |
411 | ||
42da2a58 | 412 | static void t_inject(tunnel *t, buf *b) |
b9066fbb | 413 | { |
414 | octet buf[PKBUFSZ * 2 + 2]; | |
415 | const octet *p, *l; | |
416 | octet *q; | |
417 | ||
418 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 419 | trace(T_TUNNEL, "tun-slip: inject decrypted packet"); |
420 | trace_block(T_PACKET, "tun-slip: packet contents", BBASE(b), BLEN(b)); | |
b9066fbb | 421 | }) |
422 | ||
898975ee MW |
423 | if (t-> st & ST_BROKEN) { |
424 | T( trace(T_TUNNEL, "tun-slip: tunnel broken; discarding"); ) | |
425 | return; | |
426 | } | |
b9066fbb | 427 | q = buf; |
428 | *q++ = SL_END; | |
429 | for (p = BBASE(b), l = BCUR(b); p < l; p++) { | |
430 | switch (*p) { | |
431 | case SL_END: *q++ = SL_ESC; *q++ = SL_ESCEND; break; | |
432 | case SL_ESC: *q++ = SL_ESC; *q++ = SL_ESCESC; break; | |
433 | default: *q++ = *p; break; | |
434 | } | |
435 | } | |
436 | *q++ = SL_END; | |
437 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 438 | trace_block(T_PACKET, "tun-slip: SLIP-encapsulated contents", |
b9066fbb | 439 | buf, q - buf); |
440 | }) | |
898975ee MW |
441 | if (write(t->sl->ofd, buf, q - buf) < 0) |
442 | t_broken(t); | |
b9066fbb | 443 | } |
444 | ||
42da2a58 | 445 | /* --- @t_destroy@ --- * |
b9066fbb | 446 | * |
447 | * Arguments: @tunnel *t@ = pointer to tunnel block | |
448 | * | |
449 | * Returns: --- | |
450 | * | |
451 | * Use: Destroys a tunnel. | |
452 | */ | |
453 | ||
42da2a58 | 454 | static void t_destroy(tunnel *t) |
b9066fbb | 455 | { |
98fdb08d | 456 | slipif *sl = t->sl; |
457 | ||
b9066fbb | 458 | /* --- If it reported EOF, leave it out-of-action --- */ |
459 | ||
42da2a58 | 460 | if (!(t->st & ST_EOF)) { |
b9066fbb | 461 | sel_rmfile(&t->f); |
42da2a58 | 462 | sl->f &= ~F_INUSE; |
98fdb08d | 463 | } |
42da2a58 | 464 | if (sl && (sl->f & F_DYNAMIC)) { |
060ca767 | 465 | T( trace(T_TUNNEL, "tun-slip: releasing dynamic slipif %s", sl->name); ) |
98fdb08d | 466 | close(sl->ofd); |
467 | close(sl->ifd); | |
468 | kill(sl->kid, SIGTERM); | |
469 | xfree(sl->name); | |
470 | DESTROY(sl); | |
b9066fbb | 471 | } |
42da2a58 | 472 | DESTROY(t); |
b9066fbb | 473 | } |
474 | ||
42da2a58 | 475 | const tunnel_ops tun_slip = { |
476 | "slip", | |
eb5f3fea | 477 | 0, |
388e0319 | 478 | t_init, |
42da2a58 | 479 | t_create, |
72917fe7 | 480 | t_setifname, |
42da2a58 | 481 | t_inject, |
482 | t_destroy | |
483 | }; | |
484 | ||
b9066fbb | 485 | /*----- That's all, folks -------------------------------------------------*/ |