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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.9 by pcg, Fri Mar 4 04:52:38 2005 UTC vs.
Revision 1.54 by root, Tue Oct 18 11:07:28 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) 2003-2011 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. 59 Temple Place, Suite 330, Boston, MA 02111-1307 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*/
31
32// TODO: EDNS0 option to increase dns mtu?
33// TODO: re-write dns packet parsing/creation using a safe mem-buffer
34// to ensure no buffer overflows or similar problems.
21 35
22#include "config.h" 36#include "config.h"
23 37
24#if ENABLE_DNS 38#if ENABLE_DNS
25 39
26// dns processing is EXTREMELY ugly. For obvious(?) reasons. 40// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27// it's a hack, use only in emergency situations please. 41// it's a hack, use only in emergency situations please.
28 42
29#include <cstring> 43#include <cstring>
44#include <cassert>
30 45
31#include <sys/types.h> 46#include <sys/types.h>
32#include <sys/socket.h> 47#include <sys/socket.h>
33#include <sys/wait.h> 48#include <sys/wait.h>
34#include <sys/uio.h> 49#include <sys/uio.h>
… …
37#include <unistd.h> 52#include <unistd.h>
38#include <fcntl.h> 53#include <fcntl.h>
39 54
40#include <map> 55#include <map>
41 56
57#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
42#include <gmp.h> 58#include <gmp.h>
43 59
44#include "netcompat.h" 60#include "netcompat.h"
45 61
46#include "vpn.h" 62#include "vpn.h"
47 63
48#define MIN_RETRY 1. 64#define MIN_POLL_INTERVAL 0.025 // poll at most this often when no data received
49#define MAX_RETRY 6. 65#define MAX_POLL_INTERVAL 1. // how often to poll minimally when the server has no data
50 66
51#define MAX_OUTSTANDING 400 // max. outstanding requests 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
69
70#define MAX_SEND_INTERVAL 5. // optimistic?
71
52#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
53#define MAX_RATE 100 // requests/s
54#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
55 74
56#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well 75#define MAX_DOMAIN_SIZE 235 // 255 is legal limit, but bind doesn't compress well
57// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
58// every two request byte sless give room for one reply byte 77// every request byte less give room for two reply bytes
59 78
60#define SEQNO_MASK 0xffff 79#define SEQNO_MASK 0x3fff
61#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
62 81
63#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
64#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
65 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
66#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
67#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
68#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
92
93#define CMD_IP_1 207
94#define CMD_IP_2 46
95#define CMD_IP_3 236
96
97#define CMD_IP_RST 29 // some error, reset and retry
98#define CMD_IP_REJ 32 // do not want you
99#define CMD_IP_SYN 113 // connection established
100#define CMD_IP_CSE 213 // connection established, but likely case mismatch
101
102static bool
103is_uc (char c)
104{
105 return 'A' <= c && c <= 'Z';
106}
107
108static bool
109is_lc (char c)
110{
111 return 'a' <= c && c <= 'z';
112}
69 113
70// works for cmaps up to 255 (not 256!) 114// works for cmaps up to 255 (not 256!)
71struct charmap 115struct charmap
72{ 116{
73 enum { INVALID = (u8)255 }; 117 enum { INVALID = (u8)255 };
… …
87 memset (enc, (char) 0, 256); 131 memset (enc, (char) 0, 256);
88 memset (dec, (char)INVALID, 256); 132 memset (dec, (char)INVALID, 256);
89 133
90 for (size = 0; cmap [size]; size++) 134 for (size = 0; cmap [size]; size++)
91 { 135 {
136 char c = cmap [size];
137
92 enc [size] = cmap [size]; 138 enc [size] = c;
93 dec [(u8)enc [size]] = size; 139 dec [(u8)c] = size;
140
141 // allow lowercase/uppercase aliases if possible
142 if (is_uc (c) && dec [c + ('a' - 'A')] == INVALID) dec [c + ('a' - 'A')] = size;
143 if (is_lc (c) && dec [c - ('a' - 'A')] == INVALID) dec [c - ('a' - 'A')] = size;
94 } 144 }
95 145
96 assert (size < 256); 146 assert (size < 256);
97} 147}
98 148
… …
105{ 155{
106 charmap cmap; 156 charmap cmap;
107 unsigned int enc_len [MAX_DEC_LEN]; 157 unsigned int enc_len [MAX_DEC_LEN];
108 unsigned int dec_len [MAX_ENC_LEN]; 158 unsigned int dec_len [MAX_ENC_LEN];
109 159
110 unsigned int encode_len (unsigned int len); 160 unsigned int encode_len (unsigned int len) const;
111 unsigned int decode_len (unsigned int len); 161 unsigned int decode_len (unsigned int len) const;
112 162
113 unsigned int encode (char *dst, u8 *src, unsigned int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
114 unsigned int decode (u8 *dst, char *src, unsigned int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
115 165
116 basecoder (const char *cmap); 166 basecoder (const char *cmap);
117}; 167};
118 168
119basecoder::basecoder (const char *cmap) 169basecoder::basecoder (const char *cmap)
… …
138 enc_len [len] = n; 188 enc_len [len] = n;
139 dec_len [n] = len; 189 dec_len [n] = len;
140 } 190 }
141} 191}
142 192
193unsigned int
143unsigned int basecoder::encode_len (unsigned int len) 194basecoder::encode_len (unsigned int len) const
144{ 195{
145 return enc_len [len]; 196 return enc_len [len];
146} 197}
147 198
199unsigned int
148unsigned int basecoder::decode_len (unsigned int len) 200basecoder::decode_len (unsigned int len) const
149{ 201{
150 while (len && !dec_len [len]) 202 while (len && !dec_len [len])
151 --len; 203 --len;
152 204
153 return dec_len [len]; 205 return dec_len [len];
154} 206}
155 207
208unsigned int
156unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 209basecoder::encode (char *dst, u8 *src, unsigned int len) const
157{ 210{
158 if (!len) 211 if (!len || len > MAX_DEC_LEN)
159 return 0; 212 return 0;
160 213
161 int elen = encode_len (len); 214 int elen = encode_len (len);
162 215
163 mp_limb_t m [MAX_LIMBS]; 216 mp_limb_t m [MAX_LIMBS];
… …
180 *dst++ = cmap.encode [dst_ [i]]; 233 *dst++ = cmap.encode [dst_ [i]];
181 234
182 return elen; 235 return elen;
183} 236}
184 237
238unsigned int
185unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 239basecoder::decode (u8 *dst, char *src, unsigned int len) const
186{ 240{
187 if (!len) 241 if (!len || len > MAX_ENC_LEN)
188 return 0; 242 return 0;
189 243
190 u8 src_ [MAX_ENC_LEN]; 244 u8 src_ [MAX_ENC_LEN];
191 unsigned int elen = 0; 245 unsigned int elen = 0;
192 246
… …
239 } 293 }
240 abort (); 294 abort ();
241} 295}
242#endif 296#endif
243 297
244// the following sequence has been crafted to
245// a) look somewhat random
246// b) the even (and odd) indices never share the same character as upper/lowercase
247// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)
248// the other sequences are obviously derived
249//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
250static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
251//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet 299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
252static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
253 301
254///////////////////////////////////////////////////////////////////////////// 302/////////////////////////////////////////////////////////////////////////////
255 303
256#define HDRSIZE 6 304#define HDRSIZE 5
257 305
306inline void
258inline void encode_header (char *data, int clientid, int seqno) 307encode_header (char *data, int clientid, int seqno, int retry = 0)
259{ 308{
260 u8 hdr[3] = { clientid, seqno >> 8, seqno };
261
262 assert (clientid < 256); 309 assert (clientid < 256);
263 310
311 seqno &= SEQNO_MASK;
312
313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
316 clientid,
317 };
318
264 cdc26.encode (data, hdr, 3); 319 cdc36.encode (data, hdr, 3);
265} 320}
266 321
322inline void
267inline void decode_header (char *data, int &clientid, int &seqno) 323decode_header (char *data, int &clientid, int &seqno)
268{ 324{
269 u8 hdr[3]; 325 u8 hdr[3];
270 326
271 cdc26.decode (hdr, data, HDRSIZE); 327 cdc36.decode (hdr, data, HDRSIZE);
272 328
273 clientid = hdr[0]; 329 clientid = hdr[2];
274 seqno = (hdr[1] << 8) | hdr[2]; 330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
275} 331}
276 332
277///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
278 334
279struct byte_stream 335struct byte_stream
… …
305byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
306{ 362{
307 delete data; 363 delete data;
308} 364}
309 365
366void
310void byte_stream::remove (int count) 367byte_stream::remove (int count)
311{ 368{
312 if (count > fill) 369 if (count > fill)
313 abort (); 370 assert (count <= fill);
314 371
315 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
316} 373}
317 374
375bool
318bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
319{ 377{
320 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
321 return false; 379 return false;
322 380
323 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
324 382
325 return true; 383 return true;
326} 384}
327 385
386bool
328bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
329{ 388{
330 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
331 return false; 390 return false;
332 391
333 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
334 data [fill++] = pkt->len; 393 data [fill++] = pkt->len;
335 394
336 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 395 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
337 396
338 return true; 397 return true;
339} 398}
340 399
341vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
342{ 401{
402 if (fill < 2)
403 return 0;
404
405 unsigned int len;
406
407 for (;;)
408 {
343 int len = (data [0] << 8) | data [1]; 409 len = (data [0] << 8) | data [1];
344 410
345 if (len > MAXSIZE && fill >= 2) 411 if (len <= MAXSIZE)
346 abort (); // TODO handle this gracefully, connection reset 412 break;
347 413
414 // TODO: handle this better than skipping, e.g. by reset
415 slog (L_DEBUG, _("DNS: corrupted packet (%02x %02x) stream skipping a byte..."), data [0], data [1]);
416 remove (1);
417 }
418
348 if (fill < len + 2) 419 if (fill < len + 2)
349 return 0; 420 return 0;
350 421
351 vpn_packet *pkt = new vpn_packet; 422 vpn_packet *pkt = new vpn_packet;
352 423
353 pkt->len = len; 424 pkt->len = len;
354 memcpy (&((*pkt)[0]), data + 2, len); 425 memcpy (pkt->at (0), data + 2, len);
355 remove (len + 2); 426 remove (len + 2);
356 427
357 return pkt; 428 return pkt;
358} 429}
359 430
… …
376#define FLAG_RCODE_REFUSED ( 5 << 0) 447#define FLAG_RCODE_REFUSED ( 5 << 0)
377 448
378#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 449#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
379#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) 450#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
380 451
452struct dns_cfg
453{
454 static int next_uid;
455
456 u8 chksum;
457 u8 rrtype;
458 u16 uid; // to make request unique
459
460 u8 version;
461 u8 flags;
462 u16 max_size;
463
464 u8 id1, id2, id3, id4;
465
466 u16 client;
467 u8 def_ttl;
468 u8 r0;
469
470 u8 syn_cdc; // cdc en/decoder for syn (A?) requests
471 u8 hdr_cdc; // cdc en/decoder for regular request headers
472 u8 req_cdc; // cdc en/decoder for regular (ANY?) request data
473 u8 rep_cdc; // cdc en/decoder for regular (TXT) replies, 0 == 8 bit encoding
474
475 u8 r1, r2, r3, r4;
476
477 void reset (int clientid);
478 bool valid ();
479 u8 get_chksum ();
480};
481
482int dns_cfg::next_uid;
483
484void
485dns_cfg::reset (int clientid)
486{
487 // this ID must result in some mixed-case characters in cdc26-encoding
488 id1 = 'G';
489 id2 = 'V';
490 id3 = 'P';
491 id4 = 'E';
492
493 version = 2;
494
495 rrtype = RR_TYPE_TXT;
496 flags = 0;
497 def_ttl = 0;
498 syn_cdc = 26;
499 hdr_cdc = 36;
500 req_cdc = conf.dns_case_preserving ? 62 : 36;
501 rep_cdc = 0;
502 max_size = htons (MAX_PKT_SIZE);
503 client = htons (clientid);
504 uid = ++next_uid;
505
506 r0 = r1 = r2 = r3 = r4 = 0;
507
508 chksum = get_chksum ();
509}
510
511// simple but not trivial chksum
512u8
513dns_cfg::get_chksum ()
514{
515 unsigned int sum = 0xff00; // only 16 bits required
516
517 u8 old_chksum = chksum;
518 chksum = 0;
519
520 for (unsigned int i = 0; i < sizeof (*this); ++i)
521 sum += ((u8 *)this)[i] * (i + 1);
522
523 chksum = old_chksum;
524
525 return sum + (sum >> 8);
526}
527
528bool
529dns_cfg::valid ()
530{
531 // although the protocol itself allows for some configurability,
532 // only the following encoding/decoding settings are implemented.
533 return id1 == 'G'
534 && id2 == 'V'
535 && id3 == 'P'
536 && id4 == 'E'
537 && version == 2
538 && syn_cdc == 26
539 && hdr_cdc == 36
540 && (req_cdc == 36 || req_cdc == 62)
541 && rep_cdc == 0
542 && chksum == get_chksum ();
543}
544
381struct dns_packet : net_packet 545struct dns_packet : net_packet
382{ 546{
383 u16 id; 547 u16 id;
384 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 548 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
385 u16 qdcount, ancount, nscount, arcount; 549 u16 qdcount, ancount, nscount, arcount;
386 550
387 u8 data[MAXSIZE - 6 * 2]; 551 u8 data [MAXSIZE - 6 * 2];
388 552
389 int decode_label (char *data, int size, int &offs); 553 int decode_label (char *data, int size, int &offs);
390}; 554};
391 555
556int
392int dns_packet::decode_label (char *data, int size, int &offs) 557dns_packet::decode_label (char *data, int size, int &offs)
393{ 558{
394 char *orig = data; 559 char *orig = data;
395 560
396 memset (data, 0, size); 561 memset (data, 0, size);
397 562
… …
423 return data - orig; 588 return data - orig;
424} 589}
425 590
426///////////////////////////////////////////////////////////////////////////// 591/////////////////////////////////////////////////////////////////////////////
427 592
428struct dns_req 593static
594u16 next_id ()
429{ 595{
430 dns_packet *pkt;
431 tstamp next;
432 int retry;
433 struct dns_connection *dns;
434 int seqno;
435
436 dns_req (dns_connection *dns);
437 void gen_stream_req (int seqno, byte_stream &stream);
438};
439
440static u16 dns_id = 12098; // TODO: should be per-vpn 596 static u16 dns_id = 0; // TODO: should be per-vpn
441 597
442static u16 next_id () 598#if 1
443{ 599 if (!dns_id)
600 dns_id = time (0);
601
444 // the simplest lsfr with periodicity 65535 i could find 602 // the simplest lsfr with periodicity 65535 i could find
445 dns_id = (dns_id << 1) 603 dns_id = (dns_id << 1)
446 | (((dns_id >> 1) 604 | (((dns_id >> 1)
447 ^ (dns_id >> 2) 605 ^ (dns_id >> 2)
448 ^ (dns_id >> 4) 606 ^ (dns_id >> 4)
449 ^ (dns_id >> 15)) & 1); 607 ^ (dns_id >> 15)) & 1);
450 608
451 return dns_id; 609 return dns_id;
452} 610#else
611 dns_id++;//D
453 612
613 return htons (dns_id);
614#endif
615}
616
617struct dns_rcv;
618struct dns_snd;
619
620struct dns_connection
621{
622 connection *c;
623 struct vpn *vpn;
624
625 dns_cfg cfg;
626
627 bool established;
628 const basecoder *cdc;
629
630 tstamp last_received;
631 tstamp last_sent;
632 double min_latency;
633 double poll_interval, send_interval;
634
635 vector<dns_rcv *> rcvpq;
636
637 byte_stream rcvdq; int rcvseq; int repseq;
638 byte_stream snddq; int sndseq;
639
640 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
641 void receive_rep (dns_rcv *r);
642
643 void reset (); // quite like tcp RST
644 void set_cfg (); // to be called after any cfg changes
645
646 dns_connection (connection *c);
647 ~dns_connection ();
648};
649
650struct dns_snd
651{
652 dns_packet *pkt;
653 tstamp timeout, sent;
654 int retry;
655 struct dns_connection *dns;
656 int seqno;
657 bool stdhdr;
658
659 void gen_stream_req (int seqno, byte_stream &stream);
660 void gen_syn_req ();
661
662 dns_snd (dns_connection *dns);
663 ~dns_snd ();
664};
665
454dns_req::dns_req (dns_connection *dns) 666dns_snd::dns_snd (dns_connection *dns)
455: dns (dns) 667: dns (dns)
456{ 668{
457 next = 0; 669 timeout = 0;
458 retry = 0; 670 retry = 0;
671 seqno = 0;
672 sent = ev_now ();
673 stdhdr = false;
459 674
460 pkt = new dns_packet; 675 pkt = new dns_packet;
461 676
462 pkt->id = next_id (); 677 pkt->id = next_id ();
463} 678}
464 679
680dns_snd::~dns_snd ()
681{
682 delete pkt;
683}
684
685static void
686append_domain (dns_packet &pkt, int &offs, const char *domain)
687{
688 // add tunnel domain
689 for (;;)
690 {
691 const char *end = strchr (domain, '.');
692
693 if (!end)
694 end = domain + strlen (domain);
695
696 int len = end - domain;
697
698 pkt [offs++] = len;
699 memcpy (pkt.at (offs), domain, len);
700 offs += len;
701
702 if (!*end)
703 break;
704
705 domain = end + 1;
706 }
707}
708
709void
465void dns_req::gen_stream_req (int seqno, byte_stream &stream) 710dns_snd::gen_stream_req (int seqno, byte_stream &stream)
466{ 711{
712 stdhdr = true;
467 this->seqno = seqno; 713 this->seqno = seqno;
714
715 timeout = ev_now () + INITIAL_TIMEOUT;
468 716
469 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 717 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
470 pkt->qdcount = htons (1); 718 pkt->qdcount = htons (1);
471 719
472 int offs = 6*2; 720 int offs = 6*2;
473 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 721 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
474 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, 722 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
475 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 723 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
476 724
477 char enc[256], *encp = enc; 725 char enc[256], *encp = enc;
478 encode_header (enc, THISNODE->id, seqno); 726 encode_header (enc, THISNODE->id, seqno);
479 727
480 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); 728 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
481 729
482 if (datalen > stream.size ()) 730 if (datalen > stream.size ())
483 datalen = stream.size (); 731 datalen = stream.size ();
484 732
485 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 733 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
486 stream.remove (datalen); 734 stream.remove (datalen);
487 735
488 while (enclen) 736 while (enclen)
489 { 737 {
490 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 738 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
496 encp += lbllen; 744 encp += lbllen;
497 745
498 enclen -= lbllen; 746 enclen -= lbllen;
499 } 747 }
500 748
501 const char *suffix = THISNODE->domain; 749 append_domain (*pkt, offs, dns->c->conf->domain);
502
503 // add tunnel domain
504 for (;;)
505 {
506 const char *end = strchr (suffix, '.');
507
508 if (!end)
509 end = suffix + strlen (suffix);
510
511 int len = end - suffix;
512
513 (*pkt)[offs++] = len;
514 memcpy (&((*pkt)[offs]), suffix, len);
515 offs += len;
516
517 if (!*end)
518 break;
519
520 suffix = end + 1;
521 }
522 750
523 (*pkt)[offs++] = 0; 751 (*pkt)[offs++] = 0;
524 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 752 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
753 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
754
755 pkt->len = offs;
756}
757
758void
759dns_snd::gen_syn_req ()
760{
761 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
762
763 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
764 pkt->qdcount = htons (1);
765
766 int offs = 6 * 2;
767
768 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
769
770 assert (elen <= MAX_LBL_SIZE);
771
772 (*pkt)[offs] = elen;
773 offs += elen + 1;
774 append_domain (*pkt, offs, dns->c->conf->domain);
775
776 (*pkt)[offs++] = 0;
777 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
525 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 778 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
526 779
527 pkt->len = offs; 780 pkt->len = offs;
528} 781}
529 782
… …
549 delete pkt; 802 delete pkt;
550} 803}
551 804
552///////////////////////////////////////////////////////////////////////////// 805/////////////////////////////////////////////////////////////////////////////
553 806
554struct dns_connection
555{
556 connection *c;
557 struct vpn *vpn;
558
559 vector<dns_rcv *> rcvpq;
560
561 int rcvseq;
562 int sndseq;
563
564 byte_stream rcvdq;
565 byte_stream snddq;
566
567 void time_cb (time_watcher &w); time_watcher tw;
568 void receive_rep (dns_rcv *r);
569
570 dns_connection (connection *c);
571 ~dns_connection ();
572};
573
574dns_connection::dns_connection (connection *c) 807dns_connection::dns_connection (connection *c)
575: c (c) 808: c (c)
576, rcvdq (MAX_BACKLOG * 2) 809, rcvdq (MAX_BACKLOG * 2)
577, snddq (MAX_BACKLOG * 2) 810, snddq (MAX_BACKLOG)
578, tw (this, &dns_connection::time_cb)
579{ 811{
812 tw.set<dns_connection, &dns_connection::time_cb> (this);
813
580 vpn = c->vpn; 814 vpn = c->vpn;
581 815
582 rcvseq = sndseq = 0; 816 reset ();
583} 817}
584 818
585dns_connection::~dns_connection () 819dns_connection::~dns_connection ()
586{ 820{
587 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 821 reset ();
588 i != rcvpq.end ();
589 ++i)
590 delete *i;
591} 822}
592 823
593struct dns_cfg 824void
825dns_connection::reset ()
594{ 826{
595 u8 id1, id2, id3; 827 while (!rcvpq.empty ())
596 u8 def_ttl; 828 {
597 u8 unused1; 829 delete rcvpq.back ();
598 u16 max_size; 830 rcvpq.pop_back ();
599 u8 flags1, flags2; 831 }
600};
601 832
833 for (int i = vpn->dns_sndpq.size (); i--; )
834 if (vpn->dns_sndpq [i]->dns == this)
835 {
836 vpn->dns_sndpq [i] = vpn->dns_sndpq.back ();
837 vpn->dns_sndpq.pop_back ();
838 }
839
840 established = false;
841
842 rcvseq = repseq = sndseq = 0;
843
844 last_sent = 0;
845 poll_interval = 0.5; // starting here
846 send_interval = 0.5; // starting rate
847 min_latency = INITIAL_TIMEOUT;
848}
849
850void
851dns_connection::set_cfg ()
852{
853 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
854}
855
856void
602void dns_connection::receive_rep (dns_rcv *r) 857dns_connection::receive_rep (dns_rcv *r)
603{ 858{
859 if (r->datalen)
860 poll_interval = max (poll_interval * (1. / 1.2), MIN_POLL_INTERVAL);
861 else
862 poll_interval = min (poll_interval * 1.1, MAX_POLL_INTERVAL);
863
604 rcvpq.push_back (r); 864 rcvpq.push_back (r);
605 865
606 redo: 866 redo:
607 867
608 // find next packet 868 // find next packet
609 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 869 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
610 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 870 if (SEQNO_EQ (rcvseq, (*i)->seqno))
611 { 871 {
872 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
612 // enter the packet into our input stream 873 // enter the packet into our input stream
613 r = *i; 874 r = *i;
614 875
615 // remove the oldest packet, look forward, as it's oldest first 876 // remove the oldest packet, look forward, as it's oldest first
616 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) 877 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
617 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 878 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
618 { 879 {
880 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
619 delete *j; 881 delete *j;
620 rcvpq.erase (j); 882 rcvpq.erase (j);
621 break; 883 break;
622 } 884 }
623 885
624 rcvseq = (rcvseq + 1) & SEQNO_MASK; 886 rcvseq = (rcvseq + 1) & SEQNO_MASK;
625 887
626 if (!rcvdq.put (r->data, r->datalen)) 888 if (!rcvdq.put (r->data, r->datalen))
889 {
627 abort (); // MUST never overflow, can be caused by data corruption, TODO 890 // MUST never overflow, can be caused by data corruption, TODO
891 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
892 reset ();
893 return;
894 }
628 895
629 while (vpn_packet *pkt = rcvdq.get ()) 896 while (vpn_packet *pkt = rcvdq.get ())
630 { 897 {
631 sockinfo si; 898 sockinfo si;
632 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 899 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
633 900
634 vpn->recv_vpn_packet (pkt, si); 901 vpn->recv_vpn_packet (pkt, si);
902 delete pkt;
635 } 903 }
636 904
637 // check for further packets 905 // check for further packets
638 goto redo; 906 goto redo;
639 } 907 }
640} 908}
641 909
642dns_packet * 910void
643vpn::dnsv4_server (dns_packet *pkt) 911vpn::dnsv4_server (dns_packet &pkt)
644{ 912{
645 u16 flags = ntohs (pkt->flags); 913 u16 flags = ntohs (pkt.flags);
646 914
647 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
648 int offs = 6 * 2; // skip header 915 int offs = 6 * 2; // skip header
649 916
650 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 917 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
651 918
652 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 919 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
653 && pkt->qdcount == htons (1)) 920 && pkt.qdcount == htons (1))
654 { 921 {
655 char qname[MAXSIZE]; 922 char qname [MAXSIZE];
656 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 923 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
657 924
658 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 925 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
659 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 926 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
660 927
661 pkt->qdcount = htons (1); 928 pkt.qdcount = htons (1);
662 pkt->ancount = 0; 929 pkt.ancount = 0;
663 pkt->nscount = 0; // should be self, as other nameservers reply like this 930 pkt.nscount = 0; // should be self, as other nameservers reply like this
664 pkt->arcount = 0; // a record for self, as other nameservers reply like this 931 pkt.arcount = 0; // a record for self, as other nameservers reply like this
665 932
666 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 933 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
667 934
668 int dlen = strlen (THISNODE->domain); 935 int dlen = strlen (THISNODE->domain);
669 936
670 if (qclass == RR_CLASS_IN 937 if (qclass == RR_CLASS_IN
671 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
672 && qlen > dlen + 1 + HDRSIZE 938 && qlen > dlen + 1
673 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 939 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
674 { 940 {
675 // correct class, domain: parse 941 // now generate reply
676 int client, seqno; 942 pkt.ancount = htons (1); // one answer RR
677 decode_header (qname, client, seqno); 943 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
678 944
679 u8 data[MAXSIZE]; 945 if ((qtype == RR_TYPE_ANY
680 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); 946 || qtype == RR_TYPE_TXT
681 947 || qtype == RR_TYPE_NULL)
682 if (0 < client && client <= conns.size ()) 948 && qlen > dlen + 1 + HDRSIZE)
683 { 949 {
950 // correct class, domain: parse
951 int client, seqno;
952 decode_header (qname, client, seqno);
953
954 if (0 < client && client <= conns.size ())
955 {
684 connection *c = conns [client - 1]; 956 connection *c = conns [client - 1];
685
686 if (!c->dns)
687 c->dns = new dns_connection (c);
688
689 dns_connection *dns = c->dns; 957 dns_connection *dns = c->dns;
958 dns_rcv *rcv;
690 959
960 if (dns)
961 {
962 u8 data[MAXSIZE];
963 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
964
691 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 965 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
692 if (SEQNO_EQ ((*i)->seqno, seqno)) 966 if (SEQNO_EQ ((*i)->seqno, seqno))
967 {
968 // already seen that request: simply reply with the cached reply
969 dns_rcv *r = *i;
970
971 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
972
973 // refresh header & id, as the retry count could have changed
974 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
975 r->pkt->id = pkt.id;
976
977 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
978
979 goto duplicate_request;
980 }
981
982 // new packet, queue
983 rcv = new dns_rcv (seqno, data, datalen);
984 dns->receive_rep (rcv);
985 }
986
693 { 987 {
694 // already seen that request: simply reply with the cached reply 988 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
695 dns_rcv *r = *i;
696 989
697 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 990 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
991 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
992 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
993 pkt [offs++] = 0; pkt [offs++] = 0;
994 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
698 995
699 memcpy (pkt->at (0), r->pkt->at (0), offs = r->pkt->len); 996 int rdlen_offs = offs += 2;
700 pkt->id = r->pkt->id; 997
701 goto duplicate_request; 998 if (dns)
999 {
1000 int dlen = ntohs (dns->cfg.max_size) - offs;
1001
1002 // bind doesn't compress well, so reduce further by one label length
1003 dlen -= qlen;
1004
1005 // only put data into in-order sequence packets, if
1006 // we receive out-of-order packets we generate empty
1007 // replies
1008 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
1009 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
1010 {
1011 dns->repseq = seqno;
1012
1013 while (dlen > 1 && !dns->snddq.empty ())
1014 {
1015 int txtlen = dlen <= 255 ? dlen - 1 : 255;
1016
1017 if (txtlen > dns->snddq.size ())
1018 txtlen = dns->snddq.size ();
1019
1020 pkt[offs++] = txtlen;
1021 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
1022 offs += txtlen;
1023 dns->snddq.remove (txtlen);
1024
1025 dlen -= txtlen + 1;
1026 }
1027 }
1028
1029 // avoid completely empty TXT rdata
1030 if (offs == rdlen_offs)
1031 pkt[offs++] = 0;
1032
1033 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
1034 }
1035 else
1036 {
1037 // send RST
1038 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1039 pkt [offs++] = CMD_IP_RST;
1040 }
1041
1042 int rdlen = offs - rdlen_offs;
1043
1044 pkt [rdlen_offs - 2] = rdlen >> 8;
1045 pkt [rdlen_offs - 1] = rdlen;
1046
1047 if (dns)
1048 {
1049 // now update dns_rcv copy
1050 rcv->pkt->len = offs;
1051 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
1052 }
702 } 1053 }
703 1054
704 // new packet, queue 1055 duplicate_request: ;
705 dns_rcv *rcv = new dns_rcv (seqno, data, datalen); 1056 }
706 dns->receive_rep (rcv); 1057 else
707
708 // now generate reply
709 pkt->ancount = htons (1); // one answer RR
710 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 1058 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
1059 }
1060 else if (qtype == RR_TYPE_A
1061 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
1062 {
1063 dns_cfg cfg;
1064 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
1065 int client = ntohs (cfg.client);
711 1066
712 (*pkt) [offs++] = 0xc0;
713 (*pkt) [offs++] = 6 * 2; // same as in query section 1067 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
714 1068
715 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1069 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
716 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1070 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
717
718 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1071 pkt [offs++] = 0; pkt [offs++] = 0;
719 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL 1072 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1073 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
720 1074
721 int dlen = MAX_PKT_SIZE - offs - 2; 1075 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1076 pkt [offs++] = CMD_IP_REJ;
722 1077
723 // bind doesn't compress well, so reduce further by one label length 1078 if (0 < client && client <= conns.size ())
724 dlen -= qlen;
725
726 int rdlen_offs = offs += 2;
727
728 while (dlen > 1 && !dns->snddq.empty ())
729 { 1079 {
730 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1080 connection *c = conns [client - 1];
731 1081
732 if (txtlen > dns->snddq.size ()) 1082 if (cfg.valid ())
733 txtlen = dns->snddq.size (); 1083 {
1084 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
734 1085
735 (*pkt)[offs++] = txtlen; 1086 // check for any encoding mismatches - hints at a case problem
736 memcpy (pkt->at (offs), dns->snddq.begin (), txtlen); 1087 char qname2 [MAX_ENC_LEN];
737 offs += txtlen; 1088 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
738 dns->snddq.remove (txtlen);
739 1089
740 dlen -= txtlen + 1; 1090 delete c->dns;
1091
1092 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1093 ? CMD_IP_CSE : CMD_IP_SYN;
1094
1095 c->dns = new dns_connection (c);
1096 c->dns->cfg = cfg;
1097 c->dns->set_cfg ();
1098 }
741 } 1099 }
742
743 // avoid empty TXT rdata
744 if (offs == rdlen_offs)
745 (*pkt)[offs++] = 0;
746
747 int rdlen = offs - rdlen_offs;
748
749 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
750 (*pkt) [rdlen_offs - 1] = rdlen;
751
752 // now update dns_rcv copy
753 rcv->pkt->len = offs;
754 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
755
756 duplicate_request: ;
757 } 1100 }
758 else
759 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
760 } 1101 }
761 1102
762 pkt->len = offs; 1103 pkt.len = offs;
763 } 1104 }
764
765 return pkt;
766} 1105}
767 1106
768void 1107void
769vpn::dnsv4_client (dns_packet *pkt) 1108vpn::dnsv4_client (dns_packet &pkt)
770{ 1109{
771 u16 flags = ntohs (pkt->flags); 1110 u16 flags = ntohs (pkt.flags);
772 int offs = 6 * 2; // skip header 1111 int offs = 6 * 2; // skip header
773 1112
774 pkt->qdcount = ntohs (pkt->qdcount); 1113 pkt.qdcount = ntohs (pkt.qdcount);
775 pkt->ancount = ntohs (pkt->ancount); 1114 pkt.ancount = ntohs (pkt.ancount);
776 1115
777 // go through our request list and find the corresponding request 1116 // go through our request list and find the corresponding request
778 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1117 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
779 i != dns_sndpq.end (); 1118 i != dns_sndpq.end ();
780 ++i) 1119 ++i)
781 if ((*i)->pkt->id == pkt->id) 1120 if ((*i)->pkt->id == pkt.id)
782 { 1121 {
783 dns_connection *dns = (*i)->dns; 1122 dns_connection *dns = (*i)->dns;
1123 connection *c = dns->c;
784 int seqno = (*i)->seqno; 1124 int seqno = (*i)->seqno;
785 u8 data[MAXSIZE], *datap = data; 1125 u8 data[MAXSIZE], *datap = data;
1126 //printf ("rcv pkt %x\n", seqno);//D
1127
1128 if ((*i)->retry)
1129 {
1130 dns->send_interval *= 1.01;
1131 if (dns->send_interval > MAX_SEND_INTERVAL)
1132 dns->send_interval = MAX_SEND_INTERVAL;
1133 }
1134 else
1135 {
1136#if 0
1137 dns->send_interval *= 0.999;
1138#endif
1139 // the latency surely puts an upper bound on
1140 // the minimum send interval
1141 double latency = ev_now () - (*i)->sent;
1142
1143 if (latency < dns->min_latency)
1144 dns->min_latency = latency;
1145
1146 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1147 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1148
1149 if (dns->send_interval < conf.dns_send_interval)
1150 dns->send_interval = conf.dns_send_interval;
1151 }
786 1152
787 delete *i; 1153 delete *i;
788 dns_sndpq.erase (i); 1154 dns_sndpq.erase (i);
789 1155
790 if (flags & FLAG_RESPONSE && !(flags & (FLAG_OP_MASK | FLAG_TC))) 1156 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
791 { 1157 {
792 char qname[MAXSIZE]; 1158 char qname[MAXSIZE];
793 1159
794 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1160 while (pkt.qdcount-- && offs < MAXSIZE - 4)
795 { 1161 {
796 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1162 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
797 offs += 4; // skip qtype, qclass 1163 offs += 4; // skip qtype, qclass
798 } 1164 }
799 1165
800 while (pkt->ancount-- && offs < MAXSIZE - 10 && datap) 1166 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
801 { 1167 {
802 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1168 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
803 1169
804 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1170 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
805 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1171 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
806 u32 ttl = (*pkt) [offs++] << 24; 1172 u32 ttl = pkt [offs++] << 24;
807 ttl |= (*pkt) [offs++] << 16; 1173 ttl |= pkt [offs++] << 16;
808 ttl |= (*pkt) [offs++] << 8; 1174 ttl |= pkt [offs++] << 8;
809 ttl |= (*pkt) [offs++]; 1175 ttl |= pkt [offs++];
810
811 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1176 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
812 1177
813 if (rdlen <= MAXSIZE - offs) 1178 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
814 { 1179 {
815 // decode bytes, finally 1180 if (rdlen <= MAXSIZE - offs)
816
817 while (rdlen)
818 { 1181 {
1182 // decode bytes, finally
1183
1184 while (rdlen)
1185 {
819 int txtlen = (*pkt) [offs++]; 1186 int txtlen = pkt [offs++];
820 1187
821 assert (txtlen + offs < MAXSIZE - 1); 1188 assert (txtlen + offs < MAXSIZE - 1);
822 1189
823 memcpy (datap, pkt->at (offs), txtlen); 1190 memcpy (datap, pkt.at (offs), txtlen);
824 datap += txtlen; offs += txtlen; 1191 datap += txtlen; offs += txtlen;
825 1192
826 rdlen -= txtlen + 1; 1193 rdlen -= txtlen + 1;
1194 }
827 } 1195 }
828 } 1196 }
1197 else if (qtype == RR_TYPE_A)
1198 {
1199 u8 ip [4];
1200
1201 ip [0] = pkt [offs++];
1202 ip [1] = pkt [offs++];
1203 ip [2] = pkt [offs++];
1204 ip [3] = pkt [offs++];
1205
1206 if (ip [0] == CMD_IP_1
1207 && ip [1] == CMD_IP_2
1208 && ip [2] == CMD_IP_3)
1209 {
1210 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1211
1212 if (ip [3] == CMD_IP_RST)
1213 {
1214 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1215
1216 dns->reset ();
1217 return;
1218 }
1219 else if (ip [3] == CMD_IP_SYN)
1220 {
1221 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1222 dns->established = true;
1223 }
1224 else if (ip [3] == CMD_IP_CSE)
1225 {
1226 if (conf.dns_case_preserving)
1227 {
1228 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1229 conf.dns_case_preserving = false;
1230 dns->reset ();
1231 return;
1232 }
1233 else
1234 {
1235 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1236 dns->established = true;
1237 }
1238 }
1239 else if (ip [3] == CMD_IP_REJ)
1240 {
1241 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1242 dns->tw.start (60.);
1243 }
1244 else
1245 {
1246 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1247 dns->tw.start (60.);
1248 }
1249 }
1250 else
1251 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1252 ip [0], ip [1], ip [2], ip [3]);
1253
1254 return;
1255 }
829 1256
830 int client, rseqno; 1257 int client, rseqno;
831 decode_header (qname, client, rseqno); 1258 decode_header (qname, client, rseqno);
832 1259
833 if (client != THISNODE->id) 1260 if (client != THISNODE->id)
834 { 1261 {
835 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1262 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
836 datap = 0; 1263 datap = 0;
837 } 1264 }
838 else if (rseqno != seqno) 1265 else if (rseqno != seqno)
839 { 1266 {
840 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1267 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
841 datap = 0; 1268 datap = 0;
842 } 1269 }
843 } 1270 }
844 } 1271 }
845 1272
… …
847 if (datap) 1274 if (datap)
848 dns->receive_rep (new dns_rcv (seqno, data, datap - data)); 1275 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
849 1276
850 break; 1277 break;
851 } 1278 }
852
853 delete pkt;
854} 1279}
855 1280
856void 1281void
857vpn::dnsv4_ev (io_watcher &w, short revents) 1282vpn::dnsv4_ev (ev::io &w, int revents)
858{ 1283{
859 if (revents & EVENT_READ) 1284 if (revents & EV_READ)
860 { 1285 {
861 dns_packet *pkt = new dns_packet; 1286 dns_packet *pkt = new dns_packet;
862 struct sockaddr_in sa; 1287 struct sockaddr_in sa;
863 socklen_t sa_len = sizeof (sa); 1288 socklen_t sa_len = sizeof (sa);
864 1289
865 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1290 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
866 1291
867 if (pkt->len > 0) 1292 if (pkt->len > 0)
868 { 1293 {
869 if (pkt->flags & htons (FLAG_TC)) 1294 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1295 dnsv4_client (*pkt);
1296 else
870 { 1297 {
871 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1298 dnsv4_server (*pkt);
872 //TODO connection reset 1299 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
873 } 1300 }
874 1301
875 if (THISNODE->dns_port) 1302 delete pkt;
876 {
877 pkt = dnsv4_server (pkt);
878 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
879 }
880 else
881 dnsv4_client (pkt);
882 } 1303 }
883 } 1304 }
884} 1305}
885 1306
886bool 1307bool
887connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1308vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
888{ 1309{
1310 int client = ntohl (si.host);
1311
1312 assert (0 < client && client <= conns.size ());
1313
1314 connection *c = conns [client - 1];
1315
889 if (!dns) 1316 if (!c->dns)
890 dns = new dns_connection (this); 1317 c->dns = new dns_connection (c);
891 1318
892 if (!dns->snddq.put (pkt)) 1319 if (c->dns->snddq.put (pkt))
893 return false; 1320 {
1321 min_it (c->dns->poll_interval, 0.25);
1322 c->dns->tw ();
1323 }
894 1324
895 // start timer if neccessary 1325 // always return true even if the buffer overflows
896 if (!THISNODE->dns_port && !dns->tw.active)
897 dns->tw.trigger ();
898
899 return true; 1326 return true;
900} 1327}
901 1328
902void 1329void
903dns_connection::time_cb (time_watcher &w) 1330dns_connection::time_cb (ev::timer &w, int revents)
904{ 1331{
1332 // servers have to be polled
1333 if (THISNODE->dns_port)
1334 return;
1335
905 // check for timeouts and (re)transmit 1336 // check for timeouts and (re)transmit
906 tstamp next = NOW + 60; 1337 tstamp next = 86400 * 365;
907 dns_req *send = 0; 1338 dns_snd *send = 0;
908 1339
909 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1340 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
910 i != vpn->dns_sndpq.end (); 1341 i != vpn->dns_sndpq.end ();
911 ++i) 1342 ++i)
912 { 1343 {
913 dns_req *r = *i; 1344 dns_snd *r = *i;
914 1345
915 if (r->next <= NOW) 1346 if (r->timeout <= ev_now ())
916 { 1347 {
917 if (!send) 1348 if (!send)
918 { 1349 {
919 send = r; 1350 send = r;
920 1351
921 if (r->retry)//D
922 printf ("req %d:%d, retry %d\n", r->seqno, r->pkt->id, r->retry);
923 r->retry++; 1352 r->retry++;
924 r->next = NOW + r->retry; 1353 r->timeout = ev_now () + r->retry * min_latency * conf.dns_timeout_factor;
1354 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1355
1356 // the following code changes the query section a bit, forcing
1357 // the forwarder to generate a new request
1358 if (r->stdhdr)
1359 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
925 } 1360 }
926 } 1361 }
927 1362 else
928 if (r->next < next) 1363 min_it (next, r->timeout - ev_now ());
929 next = r->next;
930 } 1364 }
931 1365
932 if (!send 1366 if (!send)
933 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
934 { 1367 {
1368 // generate a new packet, if wise
1369
1370 if (!established)
1371 {
1372 if (vpn->dns_sndpq.empty ())
1373 {
935 send = new dns_req (this); 1374 send = new dns_snd (this);
1375
1376 cfg.reset (THISNODE->id);
1377 set_cfg ();
1378 send->gen_syn_req ();
1379 }
1380 }
1381 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1382 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1383 {
1384 if (last_sent + send_interval <= ev_now ())
1385 {
1386 //printf ("sending data request etc.\n"); //D
1387 if (!snddq.empty ())
1388 min_it (next, send_interval);
1389
1390 send = new dns_snd (this);
936 send->gen_stream_req (sndseq, snddq); 1391 send->gen_stream_req (sndseq, snddq);
1392 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1393 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1394
1395 sndseq = (sndseq + 1) & SEQNO_MASK;
1396 }
1397 else
1398 min_it (next, last_sent + send_interval - ev_now ());
1399 }
1400
1401 if (send)
937 vpn->dns_sndpq.push_back (send); 1402 vpn->dns_sndpq.push_back (send);
938
939 sndseq = (sndseq + 1) & SEQNO_MASK;
940 } 1403 }
941
942 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
943 1404
944 if (send) 1405 if (send)
945 { 1406 {
946 dns_packet *pkt = send->pkt; 1407 last_sent = ev_now ();
947 1408 sendto (vpn->dnsv4_fd,
948 next = min_next; 1409 send->pkt->at (0), send->pkt->len, 0,
949
950 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0,
951 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1410 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
952 } 1411 }
953 else if (next < min_next) 1412
954 next = min_next; 1413 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1414
1415 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1416 poll_interval, send_interval, next - ev_now (),
1417 vpn->dns_sndpq.size (), snddq.size (),
1418 rcvpq.size ());
955 1419
956 w.start (next); 1420 w.start (next);
957} 1421}
958 1422
959#endif 1423#endif

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