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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.43 by pcg, Sat Dec 1 23:35:31 2007 UTC vs.
Revision 1.49 by root, Tue Feb 8 23:11:36 2011 UTC

1/* 1/*
2 vpn_dns.C -- handle the dns tunnel part of the protocol. 2 vpn_dns.C -- handle the dns tunnel part of the protocol.
3 Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> 3 Copyright (C) 2003-2008 Marc Lehmann <gvpe@schmorp.de>
4 4
5 This file is part of GVPE. 5 This file is part of GVPE.
6 6
7 GVPE is free software; you can redistribute it and/or modify 7 GVPE is free software; you can redistribute it and/or modify it
8 it under the terms of the GNU General Public License as published by 8 under the terms of the GNU General Public License as published by the
9 the Free Software Foundation; either version 2 of the License, or 9 Free Software Foundation; either version 3 of the License, or (at your
10 (at your option) any later version. 10 option) any later version.
11 11
12 This program is distributed in the hope that it will be useful, 12 This program is distributed in the hope that it will be useful, but
13 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
15 GNU General Public License for more details. 15 Public License for more details.
16 16
17 You should have received a copy of the GNU General Public License 17 You should have received a copy of the GNU General Public License along
18 along with gvpe; if not, write to the Free Software 18 with this program; if not, see <http://www.gnu.org/licenses/>.
19 Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19
20 Additional permission under GNU GPL version 3 section 7
21
22 If you modify this Program, or any covered work, by linking or
23 combining it with the OpenSSL project's OpenSSL library (or a modified
24 version of that library), containing parts covered by the terms of the
25 OpenSSL or SSLeay licenses, the licensors of this Program grant you
26 additional permission to convey the resulting work. Corresponding
27 Source for a non-source form of such a combination shall include the
28 source code for the parts of OpenSSL used as well as that of the
29 covered work.
20*/ 30*/
21 31
22// TODO: EDNS0 option to increase dns mtu? 32// TODO: EDNS0 option to increase dns mtu?
23// TODO: re-write dns packet parsing/creation using a safe mem-buffer 33// TODO: re-write dns packet parsing/creation using a safe mem-buffer
24// to ensure no buffer overflows or similar problems. 34// to ensure no buffer overflows or similar problems.
… …
42#include <unistd.h> 52#include <unistd.h>
43#include <fcntl.h> 53#include <fcntl.h>
44 54
45#include <map> 55#include <map>
46 56
57#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
47#include <gmp.h> 58#include <gmp.h>
48 59
49#include "netcompat.h" 60#include "netcompat.h"
50 61
51#include "vpn.h" 62#include "vpn.h"
… …
72#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
73 84
74#define RR_TYPE_A 1 85#define RR_TYPE_A 1
75#define RR_TYPE_NULL 10 86#define RR_TYPE_NULL 10
76#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
77#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
78 90
79#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
80 92
81#define CMD_IP_1 207 93#define CMD_IP_1 207
… …
156 enc_len [len] = n; 168 enc_len [len] = n;
157 dec_len [n] = len; 169 dec_len [n] = len;
158 } 170 }
159} 171}
160 172
173unsigned int
161unsigned int basecoder::encode_len (unsigned int len) 174basecoder::encode_len (unsigned int len)
162{ 175{
163 return enc_len [len]; 176 return enc_len [len];
164} 177}
165 178
179unsigned int
166unsigned int basecoder::decode_len (unsigned int len) 180basecoder::decode_len (unsigned int len)
167{ 181{
168 while (len && !dec_len [len]) 182 while (len && !dec_len [len])
169 --len; 183 --len;
170 184
171 return dec_len [len]; 185 return dec_len [len];
172} 186}
173 187
188unsigned int
174unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 189basecoder::encode (char *dst, u8 *src, unsigned int len)
175{ 190{
176 if (!len || len > MAX_DEC_LEN) 191 if (!len || len > MAX_DEC_LEN)
177 return 0; 192 return 0;
178 193
179 int elen = encode_len (len); 194 int elen = encode_len (len);
… …
198 *dst++ = cmap.encode [dst_ [i]]; 213 *dst++ = cmap.encode [dst_ [i]];
199 214
200 return elen; 215 return elen;
201} 216}
202 217
218unsigned int
203unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 219basecoder::decode (u8 *dst, char *src, unsigned int len)
204{ 220{
205 if (!len || len > MAX_ENC_LEN) 221 if (!len || len > MAX_ENC_LEN)
206 return 0; 222 return 0;
207 223
208 u8 src_ [MAX_ENC_LEN]; 224 u8 src_ [MAX_ENC_LEN];
… …
267 283
268///////////////////////////////////////////////////////////////////////////// 284/////////////////////////////////////////////////////////////////////////////
269 285
270#define HDRSIZE 6 286#define HDRSIZE 6
271 287
288inline void
272inline void encode_header (char *data, int clientid, int seqno, int retry = 0) 289encode_header (char *data, int clientid, int seqno, int retry = 0)
273{ 290{
274 seqno &= SEQNO_MASK; 291 seqno &= SEQNO_MASK;
275 292
276 u8 hdr[3] = { 293 u8 hdr[3] = {
277 clientid, 294 clientid,
… …
282 assert (clientid < 256); 299 assert (clientid < 256);
283 300
284 cdc26.encode (data, hdr, 3); 301 cdc26.encode (data, hdr, 3);
285} 302}
286 303
304inline void
287inline void decode_header (char *data, int &clientid, int &seqno) 305decode_header (char *data, int &clientid, int &seqno)
288{ 306{
289 u8 hdr[3]; 307 u8 hdr[3];
290 308
291 cdc26.decode (hdr, data, HDRSIZE); 309 cdc26.decode (hdr, data, HDRSIZE);
292 310
… …
325byte_stream::~byte_stream () 343byte_stream::~byte_stream ()
326{ 344{
327 delete data; 345 delete data;
328} 346}
329 347
348void
330void byte_stream::remove (int count) 349byte_stream::remove (int count)
331{ 350{
332 if (count > fill) 351 if (count > fill)
333 assert (count <= fill); 352 assert (count <= fill);
334 353
335 memmove (data, data + count, fill -= count); 354 memmove (data, data + count, fill -= count);
336} 355}
337 356
357bool
338bool byte_stream::put (u8 *data, unsigned int datalen) 358byte_stream::put (u8 *data, unsigned int datalen)
339{ 359{
340 if (maxsize - fill < datalen) 360 if (maxsize - fill < datalen)
341 return false; 361 return false;
342 362
343 memcpy (this->data + fill, data, datalen); fill += datalen; 363 memcpy (this->data + fill, data, datalen); fill += datalen;
344 364
345 return true; 365 return true;
346} 366}
347 367
368bool
348bool byte_stream::put (vpn_packet *pkt) 369byte_stream::put (vpn_packet *pkt)
349{ 370{
350 if (maxsize - fill < pkt->len + 2) 371 if (maxsize - fill < pkt->len + 2)
351 return false; 372 return false;
352 373
353 data [fill++] = pkt->len >> 8; 374 data [fill++] = pkt->len >> 8;
… …
435 bool valid (); 456 bool valid ();
436}; 457};
437 458
438int dns_cfg::next_uid; 459int dns_cfg::next_uid;
439 460
461void
440void dns_cfg::reset (int clientid) 462dns_cfg::reset (int clientid)
441{ 463{
442 id1 = 'G'; 464 id1 = 'G';
443 id2 = 'V'; 465 id2 = 'V';
444 id3 = 'P'; 466 id3 = 'P';
445 id4 = 'E'; 467 id4 = 'E';
… …
459 481
460 r3 = r4 = 0; 482 r3 = r4 = 0;
461 r4 = r5 = r6 = r7 = 0; 483 r4 = r5 = r6 = r7 = 0;
462} 484}
463 485
486bool
464bool dns_cfg::valid () 487dns_cfg::valid ()
465{ 488{
466 // although the protocol itself allows for some configurability, 489 // although the protocol itself allows for some configurability,
467 // only the following encoding/decoding settings are implemented. 490 // only the following encoding/decoding settings are implemented.
468 return id1 == 'G' 491 return id1 == 'G'
469 && id2 == 'V' 492 && id2 == 'V'
… …
484 u8 data [MAXSIZE - 6 * 2]; 507 u8 data [MAXSIZE - 6 * 2];
485 508
486 int decode_label (char *data, int size, int &offs); 509 int decode_label (char *data, int size, int &offs);
487}; 510};
488 511
512int
489int dns_packet::decode_label (char *data, int size, int &offs) 513dns_packet::decode_label (char *data, int size, int &offs)
490{ 514{
491 char *orig = data; 515 char *orig = data;
492 516
493 memset (data, 0, size); 517 memset (data, 0, size);
494 518
… …
520 return data - orig; 544 return data - orig;
521} 545}
522 546
523///////////////////////////////////////////////////////////////////////////// 547/////////////////////////////////////////////////////////////////////////////
524 548
549static
550u16 next_id ()
551{
525static u16 dns_id = 0; // TODO: should be per-vpn 552 static u16 dns_id = 0; // TODO: should be per-vpn
526 553
527static u16 next_id ()
528{
529 if (!dns_id) 554 if (!dns_id)
530 dns_id = time (0); 555 dns_id = time (0);
531 556
532 // the simplest lsfr with periodicity 65535 i could find 557 // the simplest lsfr with periodicity 65535 i could find
533 dns_id = (dns_id << 1) 558 dns_id = (dns_id << 1)
… …
559 vector<dns_rcv *> rcvpq; 584 vector<dns_rcv *> rcvpq;
560 585
561 byte_stream rcvdq; int rcvseq; int repseq; 586 byte_stream rcvdq; int rcvseq; int repseq;
562 byte_stream snddq; int sndseq; 587 byte_stream snddq; int sndseq;
563 588
564 void time_cb (ev::timer &w, int revents); ev::timer tw; 589 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
565 void receive_rep (dns_rcv *r); 590 void receive_rep (dns_rcv *r);
566 591
567 dns_connection (connection *c); 592 dns_connection (connection *c);
568 ~dns_connection (); 593 ~dns_connection ();
569}; 594};
… …
601dns_snd::~dns_snd () 626dns_snd::~dns_snd ()
602{ 627{
603 delete pkt; 628 delete pkt;
604} 629}
605 630
631static void
606static void append_domain (dns_packet &pkt, int &offs, const char *domain) 632append_domain (dns_packet &pkt, int &offs, const char *domain)
607{ 633{
608 // add tunnel domain 634 // add tunnel domain
609 for (;;) 635 for (;;)
610 { 636 {
611 const char *end = strchr (domain, '.'); 637 const char *end = strchr (domain, '.');
… …
624 650
625 domain = end + 1; 651 domain = end + 1;
626 } 652 }
627} 653}
628 654
655void
629void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 656dns_snd::gen_stream_req (int seqno, byte_stream &stream)
630{ 657{
631 stdhdr = true; 658 stdhdr = true;
632 this->seqno = seqno; 659 this->seqno = seqno;
633 660
634 timeout = ev_now () + INITIAL_TIMEOUT; 661 timeout = ev_now () + INITIAL_TIMEOUT;
… …
672 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 699 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
673 700
674 pkt->len = offs; 701 pkt->len = offs;
675} 702}
676 703
704void
677void dns_snd::gen_syn_req () 705dns_snd::gen_syn_req ()
678{ 706{
679 timeout = ev_now () + INITIAL_SYN_TIMEOUT; 707 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
680 708
681 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 709 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
682 pkt->qdcount = htons (1); 710 pkt->qdcount = htons (1);
… …
724 752
725dns_connection::dns_connection (connection *c) 753dns_connection::dns_connection (connection *c)
726: c (c) 754: c (c)
727, rcvdq (MAX_BACKLOG * 2) 755, rcvdq (MAX_BACKLOG * 2)
728, snddq (MAX_BACKLOG) 756, snddq (MAX_BACKLOG)
729, tw (this, &dns_connection::time_cb)
730{ 757{
758 tw.set<dns_connection, &dns_connection::time_cb> (this);
759
731 vpn = c->vpn; 760 vpn = c->vpn;
732 761
733 established = false; 762 established = false;
734 763
735 rcvseq = repseq = sndseq = 0; 764 rcvseq = repseq = sndseq = 0;
… …
746 i != rcvpq.end (); 775 i != rcvpq.end ();
747 ++i) 776 ++i)
748 delete *i; 777 delete *i;
749} 778}
750 779
780void
751void dns_connection::receive_rep (dns_rcv *r) 781dns_connection::receive_rep (dns_rcv *r)
752{ 782{
753 if (r->datalen) 783 if (r->datalen)
754 { 784 {
755 last_received = ev_now (); 785 last_received = ev_now ();
756 tw (); 786 tw ();

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