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