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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 1.53 by root, Tue Oct 18 10:54:17 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 unsigned int len;
403
404 for (;;)
405 {
343 int len = (data [0] << 8) | data [1]; 406 len = (data [0] << 8) | data [1];
344 407
345 if (len > MAXSIZE && fill >= 2) 408 if (len <= MAXSIZE || fill < 2)
346 abort (); // TODO handle this gracefully, connection reset 409 break;
347 410
411 // TODO: handle this better than skipping, e.g. by reset
412 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
413 remove (1);
414 }
415
348 if (fill < len + 2) 416 if (fill < len + 2)
349 return 0; 417 return 0;
350 418
351 vpn_packet *pkt = new vpn_packet; 419 vpn_packet *pkt = new vpn_packet;
352 420
353 pkt->len = len; 421 pkt->len = len;
354 memcpy (&((*pkt)[0]), data + 2, len); 422 memcpy (pkt->at (0), data + 2, len);
355 remove (len + 2); 423 remove (len + 2);
356 424
357 return pkt; 425 return pkt;
358} 426}
359 427
… …
376#define FLAG_RCODE_REFUSED ( 5 << 0) 444#define FLAG_RCODE_REFUSED ( 5 << 0)
377 445
378#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 446#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) 447#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
380 448
449struct dns_cfg
450{
451 static int next_uid;
452
453 u8 chksum;
454 u8 rrtype;
455 u16 uid; // to make request unique
456
457 u8 version;
458 u8 flags;
459 u16 max_size;
460
461 u8 id1, id2, id3, id4;
462
463 u16 client;
464 u8 def_ttl;
465 u8 r0;
466
467 u8 syn_cdc; // cdc en/decoder for syn (A?) requests
468 u8 hdr_cdc; // cdc en/decoder for regular request headers
469 u8 req_cdc; // cdc en/decoder for regular (ANY?) request data
470 u8 rep_cdc; // cdc en/decoder for regular (TXT) replies, 0 == 8 bit encoding
471
472 u8 r1, r2, r3, r4;
473
474 void reset (int clientid);
475 bool valid ();
476 u8 get_chksum ();
477};
478
479int dns_cfg::next_uid;
480
481void
482dns_cfg::reset (int clientid)
483{
484 // this ID must result in some mixed-case characters in cdc26-encoding
485 id1 = 'G';
486 id2 = 'V';
487 id3 = 'P';
488 id4 = 'E';
489
490 version = 2;
491
492 rrtype = RR_TYPE_TXT;
493 flags = 0;
494 def_ttl = 0;
495 syn_cdc = 26;
496 hdr_cdc = 36;
497 req_cdc = conf.dns_case_preserving ? 62 : 36;
498 rep_cdc = 0;
499 max_size = htons (MAX_PKT_SIZE);
500 client = htons (clientid);
501 uid = ++next_uid;
502
503 r0 = r1 = r2 = r3 = r4 = 0;
504
505 chksum = get_chksum ();
506}
507
508// simple but not trivial chksum
509u8
510dns_cfg::get_chksum ()
511{
512 unsigned int sum = 0xff00; // only 16 bits required
513
514 u8 old_chksum = chksum;
515 chksum = 0;
516
517 for (unsigned int i = 0; i < sizeof (*this); ++i)
518 sum += ((u8 *)this)[i] * (i + 1);
519
520 chksum = old_chksum;
521
522 return sum + (sum >> 8);
523}
524
525bool
526dns_cfg::valid ()
527{
528 // although the protocol itself allows for some configurability,
529 // only the following encoding/decoding settings are implemented.
530 return id1 == 'G'
531 && id2 == 'V'
532 && id3 == 'P'
533 && id4 == 'E'
534 && version == 2
535 && syn_cdc == 26
536 && hdr_cdc == 36
537 && (req_cdc == 36 || req_cdc == 62)
538 && rep_cdc == 0
539 && chksum == get_chksum ();
540}
541
381struct dns_packet : net_packet 542struct dns_packet : net_packet
382{ 543{
383 u16 id; 544 u16 id;
384 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 545 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
385 u16 qdcount, ancount, nscount, arcount; 546 u16 qdcount, ancount, nscount, arcount;
386 547
387 u8 data[MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
388 549
389 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
390}; 551};
391 552
553int
392int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
393{ 555{
394 char *orig = data; 556 char *orig = data;
395 557
396 memset (data, 0, size); 558 memset (data, 0, size);
397 559
… …
423 return data - orig; 585 return data - orig;
424} 586}
425 587
426///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
427 589
428struct dns_req 590static
591u16 next_id ()
429{ 592{
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 593 static u16 dns_id = 0; // TODO: should be per-vpn
441 594
442static u16 next_id () 595#if 1
443{ 596 if (!dns_id)
597 dns_id = time (0);
598
444 // the simplest lsfr with periodicity 65535 i could find 599 // the simplest lsfr with periodicity 65535 i could find
445 dns_id = (dns_id << 1) 600 dns_id = (dns_id << 1)
446 | (((dns_id >> 1) 601 | (((dns_id >> 1)
447 ^ (dns_id >> 2) 602 ^ (dns_id >> 2)
448 ^ (dns_id >> 4) 603 ^ (dns_id >> 4)
449 ^ (dns_id >> 15)) & 1); 604 ^ (dns_id >> 15)) & 1);
450 605
451 return dns_id; 606 return dns_id;
452} 607#else
608 dns_id++;//D
453 609
610 return htons (dns_id);
611#endif
612}
613
614struct dns_rcv;
615struct dns_snd;
616
617struct dns_connection
618{
619 connection *c;
620 struct vpn *vpn;
621
622 dns_cfg cfg;
623
624 bool established;
625 const basecoder *cdc;
626
627 tstamp last_received;
628 tstamp last_sent;
629 double min_latency;
630 double poll_interval, send_interval;
631
632 vector<dns_rcv *> rcvpq;
633
634 byte_stream rcvdq; int rcvseq; int repseq;
635 byte_stream snddq; int sndseq;
636
637 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
638 void receive_rep (dns_rcv *r);
639
640 void reset (); // quite like tcp RST
641 void set_cfg (); // to be called after any cfg changes
642
643 dns_connection (connection *c);
644 ~dns_connection ();
645};
646
647struct dns_snd
648{
649 dns_packet *pkt;
650 tstamp timeout, sent;
651 int retry;
652 struct dns_connection *dns;
653 int seqno;
654 bool stdhdr;
655
656 void gen_stream_req (int seqno, byte_stream &stream);
657 void gen_syn_req ();
658
659 dns_snd (dns_connection *dns);
660 ~dns_snd ();
661};
662
454dns_req::dns_req (dns_connection *dns) 663dns_snd::dns_snd (dns_connection *dns)
455: dns (dns) 664: dns (dns)
456{ 665{
457 next = 0; 666 timeout = 0;
458 retry = 0; 667 retry = 0;
668 seqno = 0;
669 sent = ev_now ();
670 stdhdr = false;
459 671
460 pkt = new dns_packet; 672 pkt = new dns_packet;
461 673
462 pkt->id = next_id (); 674 pkt->id = next_id ();
463} 675}
464 676
677dns_snd::~dns_snd ()
678{
679 delete pkt;
680}
681
682static void
683append_domain (dns_packet &pkt, int &offs, const char *domain)
684{
685 // add tunnel domain
686 for (;;)
687 {
688 const char *end = strchr (domain, '.');
689
690 if (!end)
691 end = domain + strlen (domain);
692
693 int len = end - domain;
694
695 pkt [offs++] = len;
696 memcpy (pkt.at (offs), domain, len);
697 offs += len;
698
699 if (!*end)
700 break;
701
702 domain = end + 1;
703 }
704}
705
706void
465void dns_req::gen_stream_req (int seqno, byte_stream &stream) 707dns_snd::gen_stream_req (int seqno, byte_stream &stream)
466{ 708{
709 stdhdr = true;
467 this->seqno = seqno; 710 this->seqno = seqno;
711
712 timeout = ev_now () + INITIAL_TIMEOUT;
468 713
469 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 714 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
470 pkt->qdcount = htons (1); 715 pkt->qdcount = htons (1);
471 716
472 int offs = 6*2; 717 int offs = 6*2;
473 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 718 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, 719 // 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 720 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
476 721
477 char enc[256], *encp = enc; 722 char enc[256], *encp = enc;
478 encode_header (enc, THISNODE->id, seqno); 723 encode_header (enc, THISNODE->id, seqno);
479 724
480 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); 725 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
481 726
482 if (datalen > stream.size ()) 727 if (datalen > stream.size ())
483 datalen = stream.size (); 728 datalen = stream.size ();
484 729
485 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 730 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
486 stream.remove (datalen); 731 stream.remove (datalen);
487 732
488 while (enclen) 733 while (enclen)
489 { 734 {
490 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 735 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
496 encp += lbllen; 741 encp += lbllen;
497 742
498 enclen -= lbllen; 743 enclen -= lbllen;
499 } 744 }
500 745
501 const char *suffix = THISNODE->domain; 746 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 }
522 747
523 (*pkt)[offs++] = 0; 748 (*pkt)[offs++] = 0;
524 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 749 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
750 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
751
752 pkt->len = offs;
753}
754
755void
756dns_snd::gen_syn_req ()
757{
758 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
759
760 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
761 pkt->qdcount = htons (1);
762
763 int offs = 6 * 2;
764
765 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
766
767 assert (elen <= MAX_LBL_SIZE);
768
769 (*pkt)[offs] = elen;
770 offs += elen + 1;
771 append_domain (*pkt, offs, dns->c->conf->domain);
772
773 (*pkt)[offs++] = 0;
774 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
525 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 775 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
526 776
527 pkt->len = offs; 777 pkt->len = offs;
528} 778}
529 779
… …
549 delete pkt; 799 delete pkt;
550} 800}
551 801
552///////////////////////////////////////////////////////////////////////////// 802/////////////////////////////////////////////////////////////////////////////
553 803
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) 804dns_connection::dns_connection (connection *c)
575: c (c) 805: c (c)
576, rcvdq (MAX_BACKLOG * 2) 806, rcvdq (MAX_BACKLOG * 2)
577, snddq (MAX_BACKLOG * 2) 807, snddq (MAX_BACKLOG)
578, tw (this, &dns_connection::time_cb)
579{ 808{
809 tw.set<dns_connection, &dns_connection::time_cb> (this);
810
580 vpn = c->vpn; 811 vpn = c->vpn;
581 812
582 rcvseq = sndseq = 0; 813 reset ();
583} 814}
584 815
585dns_connection::~dns_connection () 816dns_connection::~dns_connection ()
586{ 817{
587 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 818 reset ();
588 i != rcvpq.end ();
589 ++i)
590 delete *i;
591} 819}
592 820
593struct dns_cfg 821void
822dns_connection::reset ()
594{ 823{
595 u8 id1, id2, id3; 824 while (!rcvpq.empty ())
596 u8 def_ttl; 825 {
597 u8 unused1; 826 delete rcvpq.back ();
598 u16 max_size; 827 rcvpq.pop_back ();
599 u8 flags1, flags2; 828 }
600};
601 829
830 for (int i = vpn->dns_sndpq.size (); i--; )
831 if (vpn->dns_sndpq [i]->dns == this)
832 {
833 vpn->dns_sndpq [i] = vpn->dns_sndpq.back ();
834 vpn->dns_sndpq.pop_back ();
835 }
836
837 established = false;
838
839 rcvseq = repseq = sndseq = 0;
840
841 last_sent = 0;
842 poll_interval = 0.5; // starting here
843 send_interval = 0.5; // starting rate
844 min_latency = INITIAL_TIMEOUT;
845}
846
847void
848dns_connection::set_cfg ()
849{
850 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
851}
852
853void
602void dns_connection::receive_rep (dns_rcv *r) 854dns_connection::receive_rep (dns_rcv *r)
603{ 855{
856 if (r->datalen)
857 poll_interval = max (poll_interval * (1. / 1.2), MIN_POLL_INTERVAL);
858 else
859 poll_interval = min (poll_interval * 1.1, MAX_POLL_INTERVAL);
860
604 rcvpq.push_back (r); 861 rcvpq.push_back (r);
605 862
606 redo: 863 redo:
607 864
608 // find next packet 865 // find next packet
609 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 866 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
610 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 867 if (SEQNO_EQ (rcvseq, (*i)->seqno))
611 { 868 {
869 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
612 // enter the packet into our input stream 870 // enter the packet into our input stream
613 r = *i; 871 r = *i;
614 872
615 // remove the oldest packet, look forward, as it's oldest first 873 // remove the oldest packet, look forward, as it's oldest first
616 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) 874 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
617 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 875 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
618 { 876 {
877 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
619 delete *j; 878 delete *j;
620 rcvpq.erase (j); 879 rcvpq.erase (j);
621 break; 880 break;
622 } 881 }
623 882
624 rcvseq = (rcvseq + 1) & SEQNO_MASK; 883 rcvseq = (rcvseq + 1) & SEQNO_MASK;
625 884
626 if (!rcvdq.put (r->data, r->datalen)) 885 if (!rcvdq.put (r->data, r->datalen))
886 {
627 abort (); // MUST never overflow, can be caused by data corruption, TODO 887 // MUST never overflow, can be caused by data corruption, TODO
888 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
889 reset ();
890 return;
891 }
628 892
629 while (vpn_packet *pkt = rcvdq.get ()) 893 while (vpn_packet *pkt = rcvdq.get ())
630 { 894 {
631 sockinfo si; 895 sockinfo si;
632 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 896 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
633 897
634 vpn->recv_vpn_packet (pkt, si); 898 vpn->recv_vpn_packet (pkt, si);
899 delete pkt;
635 } 900 }
636 901
637 // check for further packets 902 // check for further packets
638 goto redo; 903 goto redo;
639 } 904 }
640} 905}
641 906
642dns_packet * 907void
643vpn::dnsv4_server (dns_packet *pkt) 908vpn::dnsv4_server (dns_packet &pkt)
644{ 909{
645 u16 flags = ntohs (pkt->flags); 910 u16 flags = ntohs (pkt.flags);
646 911
647 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
648 int offs = 6 * 2; // skip header 912 int offs = 6 * 2; // skip header
649 913
650 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 914 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
651 915
652 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 916 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
653 && pkt->qdcount == htons (1)) 917 && pkt.qdcount == htons (1))
654 { 918 {
655 char qname[MAXSIZE]; 919 char qname [MAXSIZE];
656 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 920 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
657 921
658 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 922 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
659 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 923 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
660 924
661 pkt->qdcount = htons (1); 925 pkt.qdcount = htons (1);
662 pkt->ancount = 0; 926 pkt.ancount = 0;
663 pkt->nscount = 0; // should be self, as other nameservers reply like this 927 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 928 pkt.arcount = 0; // a record for self, as other nameservers reply like this
665 929
666 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 930 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
667 931
668 int dlen = strlen (THISNODE->domain); 932 int dlen = strlen (THISNODE->domain);
669 933
670 if (qclass == RR_CLASS_IN 934 if (qclass == RR_CLASS_IN
671 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
672 && qlen > dlen + 1 + HDRSIZE 935 && qlen > dlen + 1
673 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 936 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
674 { 937 {
675 // correct class, domain: parse 938 // now generate reply
676 int client, seqno; 939 pkt.ancount = htons (1); // one answer RR
677 decode_header (qname, client, seqno); 940 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
678 941
679 u8 data[MAXSIZE]; 942 if ((qtype == RR_TYPE_ANY
680 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); 943 || qtype == RR_TYPE_TXT
681 944 || qtype == RR_TYPE_NULL)
682 if (0 < client && client <= conns.size ()) 945 && qlen > dlen + 1 + HDRSIZE)
683 { 946 {
947 // correct class, domain: parse
948 int client, seqno;
949 decode_header (qname, client, seqno);
950
951 if (0 < client && client <= conns.size ())
952 {
684 connection *c = conns [client - 1]; 953 connection *c = conns [client - 1];
685
686 if (!c->dns)
687 c->dns = new dns_connection (c);
688
689 dns_connection *dns = c->dns; 954 dns_connection *dns = c->dns;
955 dns_rcv *rcv;
690 956
957 if (dns)
958 {
959 u8 data[MAXSIZE];
960 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
961
691 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 962 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
692 if (SEQNO_EQ ((*i)->seqno, seqno)) 963 if (SEQNO_EQ ((*i)->seqno, seqno))
964 {
965 // already seen that request: simply reply with the cached reply
966 dns_rcv *r = *i;
967
968 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
969
970 // refresh header & id, as the retry count could have changed
971 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
972 r->pkt->id = pkt.id;
973
974 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
975
976 goto duplicate_request;
977 }
978
979 // new packet, queue
980 rcv = new dns_rcv (seqno, data, datalen);
981 dns->receive_rep (rcv);
982 }
983
693 { 984 {
694 // already seen that request: simply reply with the cached reply 985 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
695 dns_rcv *r = *i;
696 986
697 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 987 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
988 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
989 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
990 pkt [offs++] = 0; pkt [offs++] = 0;
991 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
698 992
699 memcpy (pkt->at (0), r->pkt->at (0), offs = r->pkt->len); 993 int rdlen_offs = offs += 2;
700 pkt->id = r->pkt->id; 994
701 goto duplicate_request; 995 if (dns)
996 {
997 int dlen = ntohs (dns->cfg.max_size) - offs;
998
999 // bind doesn't compress well, so reduce further by one label length
1000 dlen -= qlen;
1001
1002 // only put data into in-order sequence packets, if
1003 // we receive out-of-order packets we generate empty
1004 // replies
1005 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
1006 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
1007 {
1008 dns->repseq = seqno;
1009
1010 while (dlen > 1 && !dns->snddq.empty ())
1011 {
1012 int txtlen = dlen <= 255 ? dlen - 1 : 255;
1013
1014 if (txtlen > dns->snddq.size ())
1015 txtlen = dns->snddq.size ();
1016
1017 pkt[offs++] = txtlen;
1018 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
1019 offs += txtlen;
1020 dns->snddq.remove (txtlen);
1021
1022 dlen -= txtlen + 1;
1023 }
1024 }
1025
1026 // avoid completely empty TXT rdata
1027 if (offs == rdlen_offs)
1028 pkt[offs++] = 0;
1029
1030 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
1031 }
1032 else
1033 {
1034 // send RST
1035 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1036 pkt [offs++] = CMD_IP_RST;
1037 }
1038
1039 int rdlen = offs - rdlen_offs;
1040
1041 pkt [rdlen_offs - 2] = rdlen >> 8;
1042 pkt [rdlen_offs - 1] = rdlen;
1043
1044 if (dns)
1045 {
1046 // now update dns_rcv copy
1047 rcv->pkt->len = offs;
1048 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
1049 }
702 } 1050 }
703 1051
704 // new packet, queue 1052 duplicate_request: ;
705 dns_rcv *rcv = new dns_rcv (seqno, data, datalen); 1053 }
706 dns->receive_rep (rcv); 1054 else
707
708 // now generate reply
709 pkt->ancount = htons (1); // one answer RR
710 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 1055 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
1056 }
1057 else if (qtype == RR_TYPE_A
1058 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
1059 {
1060 dns_cfg cfg;
1061 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
1062 int client = ntohs (cfg.client);
711 1063
712 (*pkt) [offs++] = 0xc0;
713 (*pkt) [offs++] = 6 * 2; // same as in query section 1064 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
714 1065
715 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1066 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
716 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1067 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
717
718 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1068 pkt [offs++] = 0; pkt [offs++] = 0;
719 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL 1069 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1070 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
720 1071
721 int dlen = MAX_PKT_SIZE - offs - 2; 1072 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1073 pkt [offs++] = CMD_IP_REJ;
722 1074
723 // bind doesn't compress well, so reduce further by one label length 1075 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 { 1076 {
730 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1077 connection *c = conns [client - 1];
731 1078
732 if (txtlen > dns->snddq.size ()) 1079 if (cfg.valid ())
733 txtlen = dns->snddq.size (); 1080 {
1081 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
734 1082
735 (*pkt)[offs++] = txtlen; 1083 // check for any encoding mismatches - hints at a case problem
736 memcpy (pkt->at (offs), dns->snddq.begin (), txtlen); 1084 char qname2 [MAX_ENC_LEN];
737 offs += txtlen; 1085 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
738 dns->snddq.remove (txtlen);
739 1086
740 dlen -= txtlen + 1; 1087 delete c->dns;
1088
1089 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1090 ? CMD_IP_CSE : CMD_IP_SYN;
1091
1092 c->dns = new dns_connection (c);
1093 c->dns->cfg = cfg;
1094 c->dns->set_cfg ();
1095 }
741 } 1096 }
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 } 1097 }
758 else
759 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
760 } 1098 }
761 1099
762 pkt->len = offs; 1100 pkt.len = offs;
763 } 1101 }
764
765 return pkt;
766} 1102}
767 1103
768void 1104void
769vpn::dnsv4_client (dns_packet *pkt) 1105vpn::dnsv4_client (dns_packet &pkt)
770{ 1106{
771 u16 flags = ntohs (pkt->flags); 1107 u16 flags = ntohs (pkt.flags);
772 int offs = 6 * 2; // skip header 1108 int offs = 6 * 2; // skip header
773 1109
774 pkt->qdcount = ntohs (pkt->qdcount); 1110 pkt.qdcount = ntohs (pkt.qdcount);
775 pkt->ancount = ntohs (pkt->ancount); 1111 pkt.ancount = ntohs (pkt.ancount);
776 1112
777 // go through our request list and find the corresponding request 1113 // go through our request list and find the corresponding request
778 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1114 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
779 i != dns_sndpq.end (); 1115 i != dns_sndpq.end ();
780 ++i) 1116 ++i)
781 if ((*i)->pkt->id == pkt->id) 1117 if ((*i)->pkt->id == pkt.id)
782 { 1118 {
783 dns_connection *dns = (*i)->dns; 1119 dns_connection *dns = (*i)->dns;
1120 connection *c = dns->c;
784 int seqno = (*i)->seqno; 1121 int seqno = (*i)->seqno;
785 u8 data[MAXSIZE], *datap = data; 1122 u8 data[MAXSIZE], *datap = data;
1123 //printf ("rcv pkt %x\n", seqno);//D
1124
1125 if ((*i)->retry)
1126 {
1127 dns->send_interval *= 1.01;
1128 if (dns->send_interval > MAX_SEND_INTERVAL)
1129 dns->send_interval = MAX_SEND_INTERVAL;
1130 }
1131 else
1132 {
1133#if 0
1134 dns->send_interval *= 0.999;
1135#endif
1136 // the latency surely puts an upper bound on
1137 // the minimum send interval
1138 double latency = ev_now () - (*i)->sent;
1139
1140 if (latency < dns->min_latency)
1141 dns->min_latency = latency;
1142
1143 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1144 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1145
1146 if (dns->send_interval < conf.dns_send_interval)
1147 dns->send_interval = conf.dns_send_interval;
1148 }
786 1149
787 delete *i; 1150 delete *i;
788 dns_sndpq.erase (i); 1151 dns_sndpq.erase (i);
789 1152
790 if (flags & FLAG_RESPONSE && !(flags & (FLAG_OP_MASK | FLAG_TC))) 1153 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
791 { 1154 {
792 char qname[MAXSIZE]; 1155 char qname[MAXSIZE];
793 1156
794 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1157 while (pkt.qdcount-- && offs < MAXSIZE - 4)
795 { 1158 {
796 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1159 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
797 offs += 4; // skip qtype, qclass 1160 offs += 4; // skip qtype, qclass
798 } 1161 }
799 1162
800 while (pkt->ancount-- && offs < MAXSIZE - 10 && datap) 1163 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
801 { 1164 {
802 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1165 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
803 1166
804 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1167 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
805 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1168 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
806 u32 ttl = (*pkt) [offs++] << 24; 1169 u32 ttl = pkt [offs++] << 24;
807 ttl |= (*pkt) [offs++] << 16; 1170 ttl |= pkt [offs++] << 16;
808 ttl |= (*pkt) [offs++] << 8; 1171 ttl |= pkt [offs++] << 8;
809 ttl |= (*pkt) [offs++]; 1172 ttl |= pkt [offs++];
810
811 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1173 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
812 1174
813 if (rdlen <= MAXSIZE - offs) 1175 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
814 { 1176 {
815 // decode bytes, finally 1177 if (rdlen <= MAXSIZE - offs)
816
817 while (rdlen)
818 { 1178 {
1179 // decode bytes, finally
1180
1181 while (rdlen)
1182 {
819 int txtlen = (*pkt) [offs++]; 1183 int txtlen = pkt [offs++];
820 1184
821 assert (txtlen + offs < MAXSIZE - 1); 1185 assert (txtlen + offs < MAXSIZE - 1);
822 1186
823 memcpy (datap, pkt->at (offs), txtlen); 1187 memcpy (datap, pkt.at (offs), txtlen);
824 datap += txtlen; offs += txtlen; 1188 datap += txtlen; offs += txtlen;
825 1189
826 rdlen -= txtlen + 1; 1190 rdlen -= txtlen + 1;
1191 }
827 } 1192 }
828 } 1193 }
1194 else if (qtype == RR_TYPE_A)
1195 {
1196 u8 ip [4];
1197
1198 ip [0] = pkt [offs++];
1199 ip [1] = pkt [offs++];
1200 ip [2] = pkt [offs++];
1201 ip [3] = pkt [offs++];
1202
1203 if (ip [0] == CMD_IP_1
1204 && ip [1] == CMD_IP_2
1205 && ip [2] == CMD_IP_3)
1206 {
1207 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1208
1209 if (ip [3] == CMD_IP_RST)
1210 {
1211 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1212
1213 dns->reset ();
1214 return;
1215 }
1216 else if (ip [3] == CMD_IP_SYN)
1217 {
1218 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1219 dns->established = true;
1220 }
1221 else if (ip [3] == CMD_IP_CSE)
1222 {
1223 if (conf.dns_case_preserving)
1224 {
1225 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1226 conf.dns_case_preserving = false;
1227 dns->reset ();
1228 return;
1229 }
1230 else
1231 {
1232 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1233 dns->established = true;
1234 }
1235 }
1236 else if (ip [3] == CMD_IP_REJ)
1237 {
1238 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1239 dns->tw.start (60.);
1240 }
1241 else
1242 {
1243 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1244 dns->tw.start (60.);
1245 }
1246 }
1247 else
1248 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1249 ip [0], ip [1], ip [2], ip [3]);
1250
1251 return;
1252 }
829 1253
830 int client, rseqno; 1254 int client, rseqno;
831 decode_header (qname, client, rseqno); 1255 decode_header (qname, client, rseqno);
832 1256
833 if (client != THISNODE->id) 1257 if (client != THISNODE->id)
834 { 1258 {
835 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1259 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
836 datap = 0; 1260 datap = 0;
837 } 1261 }
838 else if (rseqno != seqno) 1262 else if (rseqno != seqno)
839 { 1263 {
840 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1264 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
841 datap = 0; 1265 datap = 0;
842 } 1266 }
843 } 1267 }
844 } 1268 }
845 1269
… …
847 if (datap) 1271 if (datap)
848 dns->receive_rep (new dns_rcv (seqno, data, datap - data)); 1272 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
849 1273
850 break; 1274 break;
851 } 1275 }
852
853 delete pkt;
854} 1276}
855 1277
856void 1278void
857vpn::dnsv4_ev (io_watcher &w, short revents) 1279vpn::dnsv4_ev (ev::io &w, int revents)
858{ 1280{
859 if (revents & EVENT_READ) 1281 if (revents & EV_READ)
860 { 1282 {
861 dns_packet *pkt = new dns_packet; 1283 dns_packet *pkt = new dns_packet;
862 struct sockaddr_in sa; 1284 struct sockaddr_in sa;
863 socklen_t sa_len = sizeof (sa); 1285 socklen_t sa_len = sizeof (sa);
864 1286
865 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1287 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
866 1288
867 if (pkt->len > 0) 1289 if (pkt->len > 0)
868 { 1290 {
869 if (pkt->flags & htons (FLAG_TC)) 1291 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1292 dnsv4_client (*pkt);
1293 else
870 { 1294 {
871 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1295 dnsv4_server (*pkt);
872 //TODO connection reset 1296 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
873 } 1297 }
874 1298
875 if (THISNODE->dns_port) 1299 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 } 1300 }
883 } 1301 }
884} 1302}
885 1303
886bool 1304bool
887connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1305vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
888{ 1306{
1307 int client = ntohl (si.host);
1308
1309 assert (0 < client && client <= conns.size ());
1310
1311 connection *c = conns [client - 1];
1312
889 if (!dns) 1313 if (!c->dns)
890 dns = new dns_connection (this); 1314 c->dns = new dns_connection (c);
891 1315
892 if (!dns->snddq.put (pkt)) 1316 if (c->dns->snddq.put (pkt))
893 return false; 1317 {
1318 min_it (c->dns->poll_interval, 0.25);
1319 c->dns->tw ();
1320 }
894 1321
895 // start timer if neccessary 1322 // always return true even if the buffer overflows
896 if (!THISNODE->dns_port && !dns->tw.active)
897 dns->tw.trigger ();
898
899 return true; 1323 return true;
900} 1324}
901 1325
902void 1326void
903dns_connection::time_cb (time_watcher &w) 1327dns_connection::time_cb (ev::timer &w, int revents)
904{ 1328{
1329 // servers have to be polled
1330 if (THISNODE->dns_port)
1331 return;
1332
905 // check for timeouts and (re)transmit 1333 // check for timeouts and (re)transmit
906 tstamp next = NOW + 60; 1334 tstamp next = 86400 * 365;
907 dns_req *send = 0; 1335 dns_snd *send = 0;
908 1336
909 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1337 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
910 i != vpn->dns_sndpq.end (); 1338 i != vpn->dns_sndpq.end ();
911 ++i) 1339 ++i)
912 { 1340 {
913 dns_req *r = *i; 1341 dns_snd *r = *i;
914 1342
915 if (r->next <= NOW) 1343 if (r->timeout <= ev_now ())
916 { 1344 {
917 if (!send) 1345 if (!send)
918 { 1346 {
919 send = r; 1347 send = r;
920 1348
921 if (r->retry)//D
922 printf ("req %d:%d, retry %d\n", r->seqno, r->pkt->id, r->retry);
923 r->retry++; 1349 r->retry++;
924 r->next = NOW + r->retry; 1350 r->timeout = ev_now () + r->retry * min_latency * conf.dns_timeout_factor;
1351 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1352
1353 // the following code changes the query section a bit, forcing
1354 // the forwarder to generate a new request
1355 if (r->stdhdr)
1356 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
925 } 1357 }
926 } 1358 }
927 1359 else
928 if (r->next < next) 1360 min_it (next, r->timeout - ev_now ());
929 next = r->next;
930 } 1361 }
931 1362
932 if (!send 1363 if (!send)
933 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
934 { 1364 {
1365 // generate a new packet, if wise
1366
1367 if (!established)
1368 {
1369 if (vpn->dns_sndpq.empty ())
1370 {
935 send = new dns_req (this); 1371 send = new dns_snd (this);
1372
1373 cfg.reset (THISNODE->id);
1374 set_cfg ();
1375 send->gen_syn_req ();
1376 }
1377 }
1378 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1379 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1380 {
1381 if (last_sent + send_interval <= ev_now ())
1382 {
1383 //printf ("sending data request etc.\n"); //D
1384 if (!snddq.empty ())
1385 min_it (next, send_interval);
1386
1387 send = new dns_snd (this);
936 send->gen_stream_req (sndseq, snddq); 1388 send->gen_stream_req (sndseq, snddq);
1389 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1390 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1391
1392 sndseq = (sndseq + 1) & SEQNO_MASK;
1393 }
1394 else
1395 min_it (next, last_sent + send_interval - ev_now ());
1396 }
1397
1398 if (send)
937 vpn->dns_sndpq.push_back (send); 1399 vpn->dns_sndpq.push_back (send);
938
939 sndseq = (sndseq + 1) & SEQNO_MASK;
940 } 1400 }
941
942 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
943 1401
944 if (send) 1402 if (send)
945 { 1403 {
946 dns_packet *pkt = send->pkt; 1404 last_sent = ev_now ();
947 1405 sendto (vpn->dnsv4_fd,
948 next = min_next; 1406 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 ()); 1407 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
952 } 1408 }
953 else if (next < min_next) 1409
954 next = min_next; 1410 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1411
1412 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1413 poll_interval, send_interval, next - ev_now (),
1414 vpn->dns_sndpq.size (), snddq.size (),
1415 rcvpq.size ());
955 1416
956 w.start (next); 1417 w.start (next);
957} 1418}
958 1419
959#endif 1420#endif

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