5 * Tunnel packets via SLIP
7 * (c) 2005 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Trivial IP Encryption (TrIPE).
14 * TrIPE is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
19 * TrIPE is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with TrIPE; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Header files ------------------------------------------------------*/
33 /*----- Static variables --------------------------------------------------*/
35 static slipif *slipifs; /* List of available interfaces */
37 /*----- Main code ---------------------------------------------------------*/
39 #if TUN_TYPE != TUN_SLIP
40 # error "Tunnel type mismatch: fix the Makefile"
45 #define SL_ESCEND 0xdc
46 #define SL_ESCESC 0xdd
50 * Arguments: @int fd@ = file descriptor to read
51 * @unsigned mode@ = what's happened
52 * @void *v@ = pointer to tunnel block
56 * Use: Reads data from the tunnel.
59 static void t_read(int fd, unsigned mode, void *v)
63 const octet *p, *l, *ll;
69 /* --- Read the input data --- */
71 n = read(fd, buf_t, sizeof(buf_t));
75 errno == EWOULDBLOCK ||
79 a_warn("TUN %s read-error -- %s", t->sl->name, strerror(errno));
83 a_warn("TUN %s slip eof", t->sl->name);
88 IF_TRACING(T_TUNNEL, {
89 trace_block(T_PACKET, "tunnel: SLIP-encapsulated data",
93 /* --- Decapsulate the packet --- */
95 for (p = buf_t, l = p + n, st = t->st,
96 q = t->buf + t->n, ll = t->buf + sizeof(t->buf);
104 else if (st & SLIPST_ESC)
105 a_warn("TUN %s slip escape-end", t->sl->name);
106 else if (q == t->buf) {
107 T( trace(T_TUNNEL, "tunnel: empty packet"); )
109 IF_TRACING(T_TUNNEL, {
110 trace(T_TUNNEL, "tunnel: packet arrived");
111 trace_block(T_PACKET, "tunnel: packet contents",
114 buf_init(&b, t->buf, q - t->buf);
118 st &= ~(SLIPST_ESC | SLIPST_BAD);
121 if ((st & SLIPST_ESC) && !(st & SLIPST_BAD)) {
122 a_warn("TUN %s slip bad-escape", t->sl->name);
136 if ((st & SLIPST_ESC) && !(st & SLIPST_BAD)) {
137 a_warn("TUN %s slip bad-escape", t->sl->name);
141 if (!(st & SLIPST_BAD)) {
145 a_warn("TUN %s slip overflow", t->sl->name);
158 /* --- @tun_init@ --- *
164 * Use: Initializes the tunneling system. Maybe this will require
165 * opening file descriptors or something.
172 slipif *sl, **tail = &slipifs;
173 unsigned long uli, ulo;
176 /* --- Build the list of available interfaces --- */
178 if ((p = getenv("TRIPE_SLIPIF")) == 0)
179 die(1, "no slip interfaces listed: set TRIPE_SLIPIF");
184 uli = strtoul(p, &q, 0);
185 if (uli > INT_MAX || q == p)
191 ulo = strtoul(p, &q, 0);
192 if (ulo > INT_MAX || q == p)
195 if (*q != '=' || (n = strcspn(q + 1, ":")) == 0)
201 sl->name = xmalloc(n + 1);
203 memcpy(sl->name, q + 1, n);
207 T( trace(T_TUNNEL, "tunnel: declared slipif %d,%d=%s",
208 sl->ifd, sl->ofd, sl->name); )
217 die(1, "bad slip interface list");
220 /* --- @tun_create@ --- *
222 * Arguments: @tunnel *t@ = pointer to tunnel block
223 * @peer *p@ = pointer to peer block
225 * Returns: Zero if it worked, nonzero on failure.
227 * Use: Initializes a new tunnel.
230 int tun_create(tunnel *t, peer *p)
233 static const char end[] = { SL_END, SL_END };
235 for (sl = slipifs; sl; sl = sl->next) {
236 if (!(sl->f & SLIPIFF_INUSE))
239 a_warn("TUN - slip no-slip-interfaces");
247 sl->f |= SLIPIFF_INUSE;
248 sel_initfile(&sel, &t->f, sl->ifd, SEL_READ, t_read, t);
250 write(sl->ofd, end, sizeof(end));
251 T( trace(T_TUNNEL, "tunnel: attached interface %s to peer `%s'",
252 sl->name, p_name(p)); )
256 /* --- @tun_ifname@ --- *
258 * Arguments: @tunnel *t@ = pointer to tunnel block
260 * Returns: A pointer to the tunnel's interface name.
263 const char *tun_ifname(tunnel *t)
265 return (t->sl->name);
268 /* --- @tun_inject@ --- *
270 * Arguments: @tunnel *t@ = pointer to tunnel block
271 * @buf *b@ = buffer to send
275 * Use: Injects a packet into the local network stack.
278 void tun_inject(tunnel *t, buf *b)
280 octet buf[PKBUFSZ * 2 + 2];
284 IF_TRACING(T_TUNNEL, {
285 trace(T_TUNNEL, "tunnel: inject decrypted packet");
286 trace_block(T_PACKET, "tunnel: packet contents", BBASE(b), BLEN(b));
291 for (p = BBASE(b), l = BCUR(b); p < l; p++) {
293 case SL_END: *q++ = SL_ESC; *q++ = SL_ESCEND; break;
294 case SL_ESC: *q++ = SL_ESC; *q++ = SL_ESCESC; break;
295 default: *q++ = *p; break;
299 IF_TRACING(T_TUNNEL, {
300 trace_block(T_PACKET, "tunnel: SLIP-encapsulated contents",
303 write(t->sl->ofd, buf, q - buf);
306 /* --- @tun_destroy@ --- *
308 * Arguments: @tunnel *t@ = pointer to tunnel block
312 * Use: Destroys a tunnel.
315 void tun_destroy(tunnel *t)
317 /* --- If it reported EOF, leave it out-of-action --- */
319 if (!(t->st & SLIPST_EOF)) {
321 t->sl->f &= ~SLIPIFF_INUSE;
325 /*----- That's all, folks -------------------------------------------------*/