Commit | Line | Data |
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b9066fbb | 1 | /* -*-c-*- |
2 | * | |
b9066fbb | 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 */ | |
53 | # define ST_EOF 4u /* File descriptor reported EOF */ | |
54 | size_t n; /* Number of bytes used in buffer */ | |
55 | octet buf[PKBUFSZ]; /* Buffer for incoming data */ | |
e04c2d50 | 56 | }; |
42da2a58 | 57 | |
b9066fbb | 58 | /*----- Static variables --------------------------------------------------*/ |
59 | ||
60 | static slipif *slipifs; /* List of available interfaces */ | |
98fdb08d | 61 | static const char *slipcmd; /* Script to make new interfaces */ |
b9066fbb | 62 | |
63 | /*----- Main code ---------------------------------------------------------*/ | |
64 | ||
b9066fbb | 65 | /* --- @t_read@ --- * |
66 | * | |
67 | * Arguments: @int fd@ = file descriptor to read | |
68 | * @unsigned mode@ = what's happened | |
69 | * @void *v@ = pointer to tunnel block | |
70 | * | |
71 | * Returns: --- | |
72 | * | |
73 | * Use: Reads data from the tunnel. | |
74 | */ | |
75 | ||
76 | static void t_read(int fd, unsigned mode, void *v) | |
77 | { | |
78 | tunnel *t = v; | |
79 | ssize_t n; | |
80 | const octet *p, *l, *ll; | |
81 | octet *q; | |
82 | unsigned st; | |
83 | octet o; | |
84 | buf b; | |
85 | ||
86 | /* --- Read the input data --- */ | |
87 | ||
88 | n = read(fd, buf_t, sizeof(buf_t)); | |
89 | if (n < 0) { | |
90 | if (errno == EINTR || | |
98fdb08d | 91 | #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN |
b9066fbb | 92 | errno == EWOULDBLOCK || |
93 | #endif | |
94 | errno == EAGAIN) | |
95 | return; | |
b476642f MW |
96 | a_warn("TUN", "%s", p_ifname(t->p), "slip", |
97 | "read-error", "?ERRNO", A_END); | |
b9066fbb | 98 | return; |
99 | } | |
100 | if (!n) { | |
72917fe7 | 101 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "eof", A_END); |
42da2a58 | 102 | t->st = ST_EOF; |
b9066fbb | 103 | sel_rmfile(&t->f); |
104 | return; | |
105 | } | |
106 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 107 | trace_block(T_PACKET, "tun-slip: SLIP-encapsulated data", |
b9066fbb | 108 | buf_t, n); |
109 | }) | |
110 | ||
111 | /* --- Decapsulate the packet --- */ | |
112 | ||
113 | for (p = buf_t, l = p + n, st = t->st, | |
114 | q = t->buf + t->n, ll = t->buf + sizeof(t->buf); | |
115 | p < l; | |
116 | p++) { | |
117 | o = *p; | |
118 | switch (o) { | |
119 | case SL_END: | |
42da2a58 | 120 | if (st & ST_BAD) |
b9066fbb | 121 | ; |
42da2a58 | 122 | else if (st & ST_ESC) |
72917fe7 | 123 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "escape-end", A_END); |
b9066fbb | 124 | else if (q == t->buf) { |
060ca767 | 125 | T( trace(T_TUNNEL, "tun-slip: empty packet"); ) |
b9066fbb | 126 | } else { |
127 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 128 | trace(T_TUNNEL, "tun-slip: packet arrived"); |
129 | trace_block(T_PACKET, "tun-slip: packet contents", | |
b9066fbb | 130 | t->buf, q - t->buf); |
131 | }) | |
132 | buf_init(&b, t->buf, q - t->buf); | |
133 | p_tun(t->p, &b); | |
134 | } | |
135 | q = t->buf; | |
42da2a58 | 136 | st &= ~(ST_ESC | ST_BAD); |
b9066fbb | 137 | break; |
138 | case SL_ESC: | |
42da2a58 | 139 | if ((st & ST_ESC) && !(st & ST_BAD)) { |
72917fe7 | 140 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "bad-escape", A_END); |
42da2a58 | 141 | st |= ST_BAD; |
b9066fbb | 142 | } else |
42da2a58 | 143 | st |= ST_ESC; |
b9066fbb | 144 | break; |
145 | case SL_ESCEND: | |
42da2a58 | 146 | if (st & ST_ESC) |
b9066fbb | 147 | o = SL_END; |
148 | goto emit; | |
149 | case SL_ESCESC: | |
42da2a58 | 150 | if (st & ST_ESC) |
b9066fbb | 151 | o = SL_ESC; |
152 | goto emit; | |
153 | default: | |
42da2a58 | 154 | if ((st & ST_ESC) && !(st & ST_BAD)) { |
72917fe7 | 155 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "bad-escape", A_END); |
42da2a58 | 156 | st |= ST_BAD; |
b9066fbb | 157 | } |
158 | emit: | |
42da2a58 | 159 | if (!(st & ST_BAD)) { |
b9066fbb | 160 | if (q < ll) |
161 | *q++ = o; | |
162 | else { | |
72917fe7 | 163 | a_warn("TUN", "%s", p_ifname(t->p), "slip", "overflow", A_END); |
42da2a58 | 164 | st |= ST_BAD; |
b9066fbb | 165 | } |
166 | } | |
42da2a58 | 167 | st &= ~ST_ESC; |
b9066fbb | 168 | break; |
169 | } | |
170 | } | |
171 | ||
172 | t->n = q - t->buf; | |
173 | t->st = st; | |
174 | } | |
175 | ||
42da2a58 | 176 | /* --- @t_init@ --- * |
b9066fbb | 177 | * |
178 | * Arguments: --- | |
179 | * | |
180 | * Returns: --- | |
181 | * | |
182 | * Use: Initializes the tunneling system. Maybe this will require | |
183 | * opening file descriptors or something. | |
184 | */ | |
185 | ||
42da2a58 | 186 | static void t_init(void) |
b9066fbb | 187 | { |
188 | char *p, *q; | |
189 | dstr d = DSTR_INIT; | |
190 | slipif *sl, **tail = &slipifs; | |
191 | unsigned long uli, ulo; | |
192 | size_t n; | |
193 | ||
b9066fbb | 194 | if ((p = getenv("TRIPE_SLIPIF")) == 0) |
42da2a58 | 195 | return; |
98fdb08d | 196 | |
197 | /* --- Build the list of available interfaces --- */ | |
198 | ||
b9066fbb | 199 | dstr_puts(&d, p); |
200 | ||
201 | p = d.buf; | |
202 | for (;;) { | |
98fdb08d | 203 | if (*p == '/' || *p == '.') { |
204 | slipcmd = p; | |
060ca767 | 205 | T( trace(T_TUNNEL, "tun-slip: declared slip command `%s'", slipcmd); ) |
98fdb08d | 206 | break; |
207 | } | |
b9066fbb | 208 | uli = strtoul(p, &q, 0); |
209 | if (uli > INT_MAX || q == p) | |
210 | goto whine; | |
211 | if (*q != ',') | |
212 | ulo = uli; | |
213 | else { | |
214 | p = q + 1; | |
215 | ulo = strtoul(p, &q, 0); | |
216 | if (ulo > INT_MAX || q == p) | |
217 | goto whine; | |
218 | } | |
219 | if (*q != '=' || (n = strcspn(q + 1, ":")) == 0) | |
220 | goto whine; | |
221 | sl = CREATE(slipif); | |
222 | sl->next = 0; | |
223 | sl->ifd = uli; | |
98fdb08d | 224 | fdflags(sl->ifd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); |
225 | fdflags(sl->ofd, O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC); | |
b9066fbb | 226 | sl->ofd = ulo; |
227 | sl->name = xmalloc(n + 1); | |
98fdb08d | 228 | sl->kid = -1; |
b9066fbb | 229 | sl->f = 0; |
230 | memcpy(sl->name, q + 1, n); | |
231 | sl->name[n] = 0; | |
232 | *tail = sl; | |
233 | tail = &sl->next; | |
060ca767 | 234 | T( trace(T_TUNNEL, "tun-slip: declared slipif %d,%d=%s", |
b9066fbb | 235 | sl->ifd, sl->ofd, sl->name); ) |
236 | p = q + n + 1; | |
237 | if (!*p) | |
238 | break; | |
239 | p++; | |
240 | } | |
241 | return; | |
242 | ||
243 | whine: | |
42da2a58 | 244 | moan("bad slip interface list"); |
b9066fbb | 245 | } |
246 | ||
42da2a58 | 247 | /* --- @t_create@ --- * |
b9066fbb | 248 | * |
42da2a58 | 249 | * Arguments: @peer *p@ = pointer to peer block |
eb5f3fea | 250 | * @int fd@ = file descriptor of tunnel device (unused) |
72917fe7 | 251 | * @char **ifn@ = where to put the interface name |
b9066fbb | 252 | * |
42da2a58 | 253 | * Returns: A tunnel block if it worked, or null on failure. |
b9066fbb | 254 | * |
255 | * Use: Initializes a new tunnel. | |
256 | */ | |
257 | ||
eb5f3fea | 258 | static tunnel *t_create(peer *p, int fd, char **ifn) |
b9066fbb | 259 | { |
98fdb08d | 260 | slipif *sl = 0; |
261 | int pin[2] = { -1, -1 }, pout[2] = { -1, -1 }; | |
b9537f3b | 262 | mdup_fd md[2]; |
98fdb08d | 263 | pid_t kid = -1; |
264 | dstr d = DSTR_INIT; | |
265 | unsigned char ch; | |
42da2a58 | 266 | tunnel *t; |
b9066fbb | 267 | static const char end[] = { SL_END, SL_END }; |
268 | ||
98fdb08d | 269 | /* --- Try to find a spare static interface --- */ |
270 | ||
b9066fbb | 271 | for (sl = slipifs; sl; sl = sl->next) { |
42da2a58 | 272 | if (!(sl->f & F_INUSE)) { |
060ca767 | 273 | T( trace(T_TUNNEL, "tun-slip: %s using static slipif %s", |
98fdb08d | 274 | p_name(p), sl->name); ) |
b9066fbb | 275 | goto found; |
98fdb08d | 276 | } |
b9066fbb | 277 | } |
98fdb08d | 278 | |
279 | /* --- If no dynamic interfaces are available, give up --- */ | |
280 | ||
281 | if (!slipcmd) { | |
f43df819 | 282 | a_warn("TUN", "-", "slip", "no-slip-interfaces", A_END); |
98fdb08d | 283 | goto fail; |
284 | } | |
285 | ||
286 | /* --- Fork off a child process to create a dynamic SLIP interface --- */ | |
287 | ||
288 | if (pipe(pin) || pipe(pout)) { | |
f43df819 | 289 | a_warn("TUN", "-", "slip", "pipe-error", "?ERRNO", A_END); |
98fdb08d | 290 | goto fail; |
291 | } | |
292 | if ((kid = fork()) < 0) { | |
f43df819 | 293 | a_warn("TUN", "-", "slip", "fork-error", "?ERRNO", A_END); |
98fdb08d | 294 | goto fail; |
295 | } | |
296 | if (!kid) { | |
b9537f3b MW |
297 | close(pin[1]); close(pout[0]); |
298 | md[0].cur = pin[0]; md[0].want = STDIN_FILENO; | |
2d5c3e54 | 299 | md[1].cur = pout[1]; md[1].want = STDOUT_FILENO; |
b9537f3b | 300 | mdup(md, 2); |
98fdb08d | 301 | execlp(slipcmd, slipcmd, p_name(p), (char *)0); |
302 | _exit(127); | |
303 | } | |
304 | ||
305 | /* --- Read the interface name --- */ | |
306 | ||
307 | sl = CREATE(slipif); | |
308 | close(pin[0]); pin[0] = -1; | |
309 | close(pout[1]); pout[1] = -1; | |
310 | for (;;) { | |
311 | errno = EIO; | |
312 | if (read(pout[0], &ch, 1) != 1 || ch == SL_END) { | |
f43df819 | 313 | a_warn("TUN", "-", "slip", "read-ifname-failed", "?ERRNO", A_END); |
98fdb08d | 314 | goto fail; |
315 | } | |
316 | if (ch == '\n') | |
317 | break; | |
318 | DPUTC(&d, (char)ch); | |
319 | } | |
320 | DPUTZ(&d); | |
321 | sl->name = xstrdup(d.buf); | |
322 | sl->ifd = pout[0]; | |
323 | sl->ofd = pin[1]; | |
324 | sl->kid = kid; | |
325 | sl->next = 0; | |
42da2a58 | 326 | sl->f = F_DYNAMIC; |
060ca767 | 327 | T( trace(T_TUNNEL, "tun-slip: %s using dynamic slipif %s", |
98fdb08d | 328 | p_name(p), sl->name); ) |
329 | fdflags(pout[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); | |
330 | fdflags(pin[1], O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC); | |
331 | ||
332 | /* --- Set up the new tunnel --- */ | |
b9066fbb | 333 | |
334 | found: | |
42da2a58 | 335 | t = CREATE(tunnel); |
336 | t->ops = &tun_slip; | |
b9066fbb | 337 | t->p = p; |
338 | t->sl = sl; | |
339 | t->st = 0; | |
340 | t->n = 0; | |
42da2a58 | 341 | sl->f |= F_INUSE; |
b9066fbb | 342 | sel_initfile(&sel, &t->f, sl->ifd, SEL_READ, t_read, t); |
343 | sel_addfile(&t->f); | |
344 | write(sl->ofd, end, sizeof(end)); | |
72917fe7 | 345 | *ifn = xstrdup(sl->name); |
98fdb08d | 346 | dstr_destroy(&d); |
42da2a58 | 347 | return (t); |
98fdb08d | 348 | |
349 | /* --- Tidy up after a failure --- */ | |
350 | ||
351 | fail: | |
352 | #define CLOSE(fd) do if (fd != -1) close(fd); while (0) | |
353 | CLOSE(pin[0]); CLOSE(pout[0]); | |
354 | CLOSE(pin[1]); CLOSE(pout[1]); | |
355 | #undef CLOSE | |
356 | if (kid != -1) kill(kid, SIGTERM); | |
42da2a58 | 357 | if (sl && (sl->f & F_DYNAMIC)) DESTROY(sl); |
98fdb08d | 358 | dstr_destroy(&d); |
42da2a58 | 359 | return (0); |
b9066fbb | 360 | } |
361 | ||
72917fe7 | 362 | /* --- @t_setifname@ --- * |
b9066fbb | 363 | * |
364 | * Arguments: @tunnel *t@ = pointer to tunnel block | |
72917fe7 | 365 | * @const char *ifn@ = new interface name |
b9066fbb | 366 | * |
72917fe7 MW |
367 | * Returns: --- |
368 | * | |
369 | * Use: Updates the interface name of a slip interface. | |
b9066fbb | 370 | */ |
371 | ||
72917fe7 MW |
372 | static void t_setifname(tunnel *t, const char *ifn) |
373 | { xfree(t->sl->name); t->sl->name = xstrdup(ifn); } | |
b9066fbb | 374 | |
42da2a58 | 375 | /* --- @t_inject@ --- * |
b9066fbb | 376 | * |
377 | * Arguments: @tunnel *t@ = pointer to tunnel block | |
378 | * @buf *b@ = buffer to send | |
379 | * | |
380 | * Returns: --- | |
381 | * | |
382 | * Use: Injects a packet into the local network stack. | |
383 | */ | |
384 | ||
42da2a58 | 385 | static void t_inject(tunnel *t, buf *b) |
b9066fbb | 386 | { |
387 | octet buf[PKBUFSZ * 2 + 2]; | |
388 | const octet *p, *l; | |
389 | octet *q; | |
390 | ||
391 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 392 | trace(T_TUNNEL, "tun-slip: inject decrypted packet"); |
393 | trace_block(T_PACKET, "tun-slip: packet contents", BBASE(b), BLEN(b)); | |
b9066fbb | 394 | }) |
395 | ||
396 | q = buf; | |
397 | *q++ = SL_END; | |
398 | for (p = BBASE(b), l = BCUR(b); p < l; p++) { | |
399 | switch (*p) { | |
400 | case SL_END: *q++ = SL_ESC; *q++ = SL_ESCEND; break; | |
401 | case SL_ESC: *q++ = SL_ESC; *q++ = SL_ESCESC; break; | |
402 | default: *q++ = *p; break; | |
403 | } | |
404 | } | |
405 | *q++ = SL_END; | |
406 | IF_TRACING(T_TUNNEL, { | |
060ca767 | 407 | trace_block(T_PACKET, "tun-slip: SLIP-encapsulated contents", |
b9066fbb | 408 | buf, q - buf); |
409 | }) | |
410 | write(t->sl->ofd, buf, q - buf); | |
411 | } | |
412 | ||
42da2a58 | 413 | /* --- @t_destroy@ --- * |
b9066fbb | 414 | * |
415 | * Arguments: @tunnel *t@ = pointer to tunnel block | |
416 | * | |
417 | * Returns: --- | |
418 | * | |
419 | * Use: Destroys a tunnel. | |
420 | */ | |
421 | ||
42da2a58 | 422 | static void t_destroy(tunnel *t) |
b9066fbb | 423 | { |
98fdb08d | 424 | slipif *sl = t->sl; |
425 | ||
b9066fbb | 426 | /* --- If it reported EOF, leave it out-of-action --- */ |
427 | ||
42da2a58 | 428 | if (!(t->st & ST_EOF)) { |
b9066fbb | 429 | sel_rmfile(&t->f); |
42da2a58 | 430 | sl->f &= ~F_INUSE; |
98fdb08d | 431 | } |
42da2a58 | 432 | if (sl && (sl->f & F_DYNAMIC)) { |
060ca767 | 433 | T( trace(T_TUNNEL, "tun-slip: releasing dynamic slipif %s", sl->name); ) |
98fdb08d | 434 | close(sl->ofd); |
435 | close(sl->ifd); | |
436 | kill(sl->kid, SIGTERM); | |
437 | xfree(sl->name); | |
438 | DESTROY(sl); | |
b9066fbb | 439 | } |
42da2a58 | 440 | DESTROY(t); |
b9066fbb | 441 | } |
442 | ||
42da2a58 | 443 | const tunnel_ops tun_slip = { |
444 | "slip", | |
eb5f3fea | 445 | 0, |
388e0319 | 446 | t_init, |
42da2a58 | 447 | t_create, |
72917fe7 | 448 | t_setifname, |
42da2a58 | 449 | t_inject, |
450 | t_destroy | |
451 | }; | |
452 | ||
b9066fbb | 453 | /*----- That's all, folks -------------------------------------------------*/ |