chiark / gitweb /
server/peer.c, server/keyset.c: Fix key renegotiation behaviour.
[tripe] / server / tun-slip.c
CommitLineData
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
35typedef 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
45struct 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
60static slipif *slipifs; /* List of available interfaces */
98fdb08d 61static 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
76static 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 185static 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
242whine:
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
72917fe7 249 * @char **ifn@ = where to put the interface name
b9066fbb 250 *
42da2a58 251 * Returns: A tunnel block if it worked, or null on failure.
b9066fbb 252 *
253 * Use: Initializes a new tunnel.
254 */
255
72917fe7 256static tunnel *t_create(peer *p, char **ifn)
b9066fbb 257{
98fdb08d 258 slipif *sl = 0;
259 int pin[2] = { -1, -1 }, pout[2] = { -1, -1 };
260 pid_t kid = -1;
261 dstr d = DSTR_INIT;
262 unsigned char ch;
42da2a58 263 tunnel *t;
b9066fbb 264 static const char end[] = { SL_END, SL_END };
265
98fdb08d 266 /* --- Try to find a spare static interface --- */
267
b9066fbb 268 for (sl = slipifs; sl; sl = sl->next) {
42da2a58 269 if (!(sl->f & F_INUSE)) {
060ca767 270 T( trace(T_TUNNEL, "tun-slip: %s using static slipif %s",
98fdb08d 271 p_name(p), sl->name); )
b9066fbb 272 goto found;
98fdb08d 273 }
b9066fbb 274 }
98fdb08d 275
276 /* --- If no dynamic interfaces are available, give up --- */
277
278 if (!slipcmd) {
f43df819 279 a_warn("TUN", "-", "slip", "no-slip-interfaces", A_END);
98fdb08d 280 goto fail;
281 }
282
283 /* --- Fork off a child process to create a dynamic SLIP interface --- */
284
285 if (pipe(pin) || pipe(pout)) {
f43df819 286 a_warn("TUN", "-", "slip", "pipe-error", "?ERRNO", A_END);
98fdb08d 287 goto fail;
288 }
289 if ((kid = fork()) < 0) {
f43df819 290 a_warn("TUN", "-", "slip", "fork-error", "?ERRNO", A_END);
98fdb08d 291 goto fail;
292 }
293 if (!kid) {
294 close(pin[1]);
295 close(pout[0]);
296 dup2(pin[0], STDIN_FILENO);
297 dup2(pout[1], STDOUT_FILENO);
298 execlp(slipcmd, slipcmd, p_name(p), (char *)0);
299 _exit(127);
300 }
301
302 /* --- Read the interface name --- */
303
304 sl = CREATE(slipif);
305 close(pin[0]); pin[0] = -1;
306 close(pout[1]); pout[1] = -1;
307 for (;;) {
308 errno = EIO;
309 if (read(pout[0], &ch, 1) != 1 || ch == SL_END) {
f43df819 310 a_warn("TUN", "-", "slip", "read-ifname-failed", "?ERRNO", A_END);
98fdb08d 311 goto fail;
312 }
313 if (ch == '\n')
314 break;
315 DPUTC(&d, (char)ch);
316 }
317 DPUTZ(&d);
318 sl->name = xstrdup(d.buf);
319 sl->ifd = pout[0];
320 sl->ofd = pin[1];
321 sl->kid = kid;
322 sl->next = 0;
42da2a58 323 sl->f = F_DYNAMIC;
060ca767 324 T( trace(T_TUNNEL, "tun-slip: %s using dynamic slipif %s",
98fdb08d 325 p_name(p), sl->name); )
326 fdflags(pout[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
327 fdflags(pin[1], O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC);
328
329 /* --- Set up the new tunnel --- */
b9066fbb 330
331found:
42da2a58 332 t = CREATE(tunnel);
333 t->ops = &tun_slip;
b9066fbb 334 t->p = p;
335 t->sl = sl;
336 t->st = 0;
337 t->n = 0;
42da2a58 338 sl->f |= F_INUSE;
b9066fbb 339 sel_initfile(&sel, &t->f, sl->ifd, SEL_READ, t_read, t);
340 sel_addfile(&t->f);
341 write(sl->ofd, end, sizeof(end));
72917fe7 342 *ifn = xstrdup(sl->name);
98fdb08d 343 dstr_destroy(&d);
42da2a58 344 return (t);
98fdb08d 345
346 /* --- Tidy up after a failure --- */
347
348fail:
349#define CLOSE(fd) do if (fd != -1) close(fd); while (0)
350 CLOSE(pin[0]); CLOSE(pout[0]);
351 CLOSE(pin[1]); CLOSE(pout[1]);
352#undef CLOSE
353 if (kid != -1) kill(kid, SIGTERM);
42da2a58 354 if (sl && (sl->f & F_DYNAMIC)) DESTROY(sl);
98fdb08d 355 dstr_destroy(&d);
42da2a58 356 return (0);
b9066fbb 357}
358
72917fe7 359/* --- @t_setifname@ --- *
b9066fbb 360 *
361 * Arguments: @tunnel *t@ = pointer to tunnel block
72917fe7 362 * @const char *ifn@ = new interface name
b9066fbb 363 *
72917fe7
MW
364 * Returns: ---
365 *
366 * Use: Updates the interface name of a slip interface.
b9066fbb 367 */
368
72917fe7
MW
369static void t_setifname(tunnel *t, const char *ifn)
370 { xfree(t->sl->name); t->sl->name = xstrdup(ifn); }
b9066fbb 371
42da2a58 372/* --- @t_inject@ --- *
b9066fbb 373 *
374 * Arguments: @tunnel *t@ = pointer to tunnel block
375 * @buf *b@ = buffer to send
376 *
377 * Returns: ---
378 *
379 * Use: Injects a packet into the local network stack.
380 */
381
42da2a58 382static void t_inject(tunnel *t, buf *b)
b9066fbb 383{
384 octet buf[PKBUFSZ * 2 + 2];
385 const octet *p, *l;
386 octet *q;
387
388 IF_TRACING(T_TUNNEL, {
060ca767 389 trace(T_TUNNEL, "tun-slip: inject decrypted packet");
390 trace_block(T_PACKET, "tun-slip: packet contents", BBASE(b), BLEN(b));
b9066fbb 391 })
392
393 q = buf;
394 *q++ = SL_END;
395 for (p = BBASE(b), l = BCUR(b); p < l; p++) {
396 switch (*p) {
397 case SL_END: *q++ = SL_ESC; *q++ = SL_ESCEND; break;
398 case SL_ESC: *q++ = SL_ESC; *q++ = SL_ESCESC; break;
399 default: *q++ = *p; break;
400 }
401 }
402 *q++ = SL_END;
403 IF_TRACING(T_TUNNEL, {
060ca767 404 trace_block(T_PACKET, "tun-slip: SLIP-encapsulated contents",
b9066fbb 405 buf, q - buf);
406 })
407 write(t->sl->ofd, buf, q - buf);
408}
409
42da2a58 410/* --- @t_destroy@ --- *
b9066fbb 411 *
412 * Arguments: @tunnel *t@ = pointer to tunnel block
413 *
414 * Returns: ---
415 *
416 * Use: Destroys a tunnel.
417 */
418
42da2a58 419static void t_destroy(tunnel *t)
b9066fbb 420{
98fdb08d 421 slipif *sl = t->sl;
422
b9066fbb 423 /* --- If it reported EOF, leave it out-of-action --- */
424
42da2a58 425 if (!(t->st & ST_EOF)) {
b9066fbb 426 sel_rmfile(&t->f);
42da2a58 427 sl->f &= ~F_INUSE;
98fdb08d 428 }
42da2a58 429 if (sl && (sl->f & F_DYNAMIC)) {
060ca767 430 T( trace(T_TUNNEL, "tun-slip: releasing dynamic slipif %s", sl->name); )
98fdb08d 431 close(sl->ofd);
432 close(sl->ifd);
433 kill(sl->kid, SIGTERM);
434 xfree(sl->name);
435 DESTROY(sl);
b9066fbb 436 }
42da2a58 437 DESTROY(t);
b9066fbb 438}
439
42da2a58 440const tunnel_ops tun_slip = {
441 "slip",
442 t_init,
443 t_create,
72917fe7 444 t_setifname,
42da2a58 445 t_inject,
446 t_destroy
447};
448
b9066fbb 449/*----- That's all, folks -------------------------------------------------*/