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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.46 by pcg, Thu Dec 6 00:35:29 2007 UTC vs.
Revision 1.51 by root, Sun Mar 6 19:40:28 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. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19
20 Additional permission under GNU GPL version 3 section 7
21
22 If you modify this Program, or any covered work, by linking or
23 combining it with the OpenSSL project's OpenSSL library (or a modified
24 version of that library), containing parts covered by the terms of the
25 OpenSSL or SSLeay licenses, the licensors of this Program grant you
26 additional permission to convey the resulting work. Corresponding
27 Source for a non-source form of such a combination shall include the
28 source code for the parts of OpenSSL used as well as that of the
29 covered work.
20*/ 30*/
21 31
22// TODO: EDNS0 option to increase dns mtu? 32// TODO: EDNS0 option to increase dns mtu?
23// TODO: re-write dns packet parsing/creation using a safe mem-buffer 33// TODO: re-write dns packet parsing/creation using a safe mem-buffer
24// to ensure no buffer overflows or similar problems. 34// to ensure no buffer overflows or similar problems.
… …
49 59
50#include "netcompat.h" 60#include "netcompat.h"
51 61
52#include "vpn.h" 62#include "vpn.h"
53 63
64#define MIN_POLL_INTERVAL 0.1 // poll at most this often when no data received
54#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data 65#define MAX_POLL_INTERVAL 1. // how often to poll minimally when the server has no data
55#define ACTIVITY_INTERVAL 5.
56 66
57#define INITIAL_TIMEOUT 0.1 // retry timeouts 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
58#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn 68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
59 69
60#define MAX_SEND_INTERVAL 2. // optimistic? 70#define MAX_SEND_INTERVAL 2. // optimistic?
… …
73#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
74 84
75#define RR_TYPE_A 1 85#define RR_TYPE_A 1
76#define RR_TYPE_NULL 10 86#define RR_TYPE_NULL 10
77#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
78#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
79 90
80#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
81 92
82#define CMD_IP_1 207 93#define CMD_IP_1 207
83#define CMD_IP_2 46 94#define CMD_IP_2 46
84#define CMD_IP_3 236 95#define CMD_IP_3 236
85#define CMD_IP_RST 29 96
86#define CMD_IP_SYN 113 97#define CMD_IP_RST 29 // some error, reset and retry
87#define CMD_IP_REJ 32 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}
88 113
89// works for cmaps up to 255 (not 256!) 114// works for cmaps up to 255 (not 256!)
90struct charmap 115struct charmap
91{ 116{
92 enum { INVALID = (u8)255 }; 117 enum { INVALID = (u8)255 };
… …
106 memset (enc, (char) 0, 256); 131 memset (enc, (char) 0, 256);
107 memset (dec, (char)INVALID, 256); 132 memset (dec, (char)INVALID, 256);
108 133
109 for (size = 0; cmap [size]; size++) 134 for (size = 0; cmap [size]; size++)
110 { 135 {
136 char c = cmap [size];
137
111 enc [size] = cmap [size]; 138 enc [size] = c;
112 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;
113 } 144 }
114 145
115 assert (size < 256); 146 assert (size < 256);
116} 147}
117 148
… …
124{ 155{
125 charmap cmap; 156 charmap cmap;
126 unsigned int enc_len [MAX_DEC_LEN]; 157 unsigned int enc_len [MAX_DEC_LEN];
127 unsigned int dec_len [MAX_ENC_LEN]; 158 unsigned int dec_len [MAX_ENC_LEN];
128 159
129 unsigned int encode_len (unsigned int len); 160 unsigned int encode_len (unsigned int len) const;
130 unsigned int decode_len (unsigned int len); 161 unsigned int decode_len (unsigned int len) const;
131 162
132 unsigned int encode (char *dst, u8 *src, unsigned int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
133 unsigned int decode (u8 *dst, char *src, unsigned int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
134 165
135 basecoder (const char *cmap); 166 basecoder (const char *cmap);
136}; 167};
137 168
138basecoder::basecoder (const char *cmap) 169basecoder::basecoder (const char *cmap)
… …
157 enc_len [len] = n; 188 enc_len [len] = n;
158 dec_len [n] = len; 189 dec_len [n] = len;
159 } 190 }
160} 191}
161 192
193unsigned int
162unsigned int basecoder::encode_len (unsigned int len) 194basecoder::encode_len (unsigned int len) const
163{ 195{
164 return enc_len [len]; 196 return enc_len [len];
165} 197}
166 198
199unsigned int
167unsigned int basecoder::decode_len (unsigned int len) 200basecoder::decode_len (unsigned int len) const
168{ 201{
169 while (len && !dec_len [len]) 202 while (len && !dec_len [len])
170 --len; 203 --len;
171 204
172 return dec_len [len]; 205 return dec_len [len];
173} 206}
174 207
208unsigned int
175unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 209basecoder::encode (char *dst, u8 *src, unsigned int len) const
176{ 210{
177 if (!len || len > MAX_DEC_LEN) 211 if (!len || len > MAX_DEC_LEN)
178 return 0; 212 return 0;
179 213
180 int elen = encode_len (len); 214 int elen = encode_len (len);
… …
199 *dst++ = cmap.encode [dst_ [i]]; 233 *dst++ = cmap.encode [dst_ [i]];
200 234
201 return elen; 235 return elen;
202} 236}
203 237
238unsigned int
204unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 239basecoder::decode (u8 *dst, char *src, unsigned int len) const
205{ 240{
206 if (!len || len > MAX_ENC_LEN) 241 if (!len || len > MAX_ENC_LEN)
207 return 0; 242 return 0;
208 243
209 u8 src_ [MAX_ENC_LEN]; 244 u8 src_ [MAX_ENC_LEN];
… …
258 } 293 }
259 abort (); 294 abort ();
260} 295}
261#endif 296#endif
262 297
263//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
264//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
265static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
266//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet 299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
267static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
268 301
269///////////////////////////////////////////////////////////////////////////// 302/////////////////////////////////////////////////////////////////////////////
270 303
271#define HDRSIZE 6 304#define HDRSIZE 5
272 305
306inline void
273inline void encode_header (char *data, int clientid, int seqno, int retry = 0) 307encode_header (char *data, int clientid, int seqno, int retry = 0)
274{ 308{
309 assert (clientid < 256);
310
275 seqno &= SEQNO_MASK; 311 seqno &= SEQNO_MASK;
276 312
277 u8 hdr[3] = { 313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
278 clientid, 316 clientid,
279 (seqno >> 8) | (retry << 6),
280 seqno,
281 }; 317 };
282 318
283 assert (clientid < 256);
284
285 cdc26.encode (data, hdr, 3); 319 cdc36.encode (data, hdr, 3);
286} 320}
287 321
322inline void
288inline void decode_header (char *data, int &clientid, int &seqno) 323decode_header (char *data, int &clientid, int &seqno)
289{ 324{
290 u8 hdr[3]; 325 u8 hdr[3];
291 326
292 cdc26.decode (hdr, data, HDRSIZE); 327 cdc36.decode (hdr, data, HDRSIZE);
293 328
294 clientid = hdr[0]; 329 clientid = hdr[2];
295 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK; 330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
296} 331}
297 332
298///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
299 334
300struct byte_stream 335struct byte_stream
… …
326byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
327{ 362{
328 delete data; 363 delete data;
329} 364}
330 365
366void
331void byte_stream::remove (int count) 367byte_stream::remove (int count)
332{ 368{
333 if (count > fill) 369 if (count > fill)
334 assert (count <= fill); 370 assert (count <= fill);
335 371
336 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
337} 373}
338 374
375bool
339bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
340{ 377{
341 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
342 return false; 379 return false;
343 380
344 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
345 382
346 return true; 383 return true;
347} 384}
348 385
386bool
349bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
350{ 388{
351 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
352 return false; 390 return false;
353 391
354 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
… …
410 448
411struct dns_cfg 449struct dns_cfg
412{ 450{
413 static int next_uid; 451 static int next_uid;
414 452
415 u8 id1, id2, id3, id4; 453 u8 chksum;
454 u8 rrtype;
455 u16 uid; // to make request unique
416 456
417 u8 version; 457 u8 version;
418 u8 flags; 458 u8 flags;
419 u8 rrtype; 459 u16 max_size;
460
461 u8 id1, id2, id3, id4;
462
463 u16 client;
420 u8 def_ttl; 464 u8 def_ttl;
465 u8 r0;
421 466
422 u16 client; 467 u8 syn_cdc; // cdc en/decoder for syn (A?) requests
423 u16 uid; // to make request unique 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
424 471
425 u16 max_size;
426 u8 seq_cdc;
427 u8 req_cdc;
428
429 u8 rep_cdc;
430 u8 delay; // time in 0.01s units that the server may delay replying packets
431 u8 r3, r4;
432
433 u8 r5, r6, r7, r8; 472 u8 r1, r2, r3, r4;
434 473
435 void reset (int clientid); 474 void reset (int clientid);
436 bool valid (); 475 bool valid ();
476 u8 get_chksum ();
437}; 477};
438 478
439int dns_cfg::next_uid; 479int dns_cfg::next_uid;
440 480
481void
441void dns_cfg::reset (int clientid) 482dns_cfg::reset (int clientid)
442{ 483{
484 // this ID must result in some mixed-case characters in cdc26-encoding
443 id1 = 'G'; 485 id1 = 'G';
444 id2 = 'V'; 486 id2 = 'V';
445 id3 = 'P'; 487 id3 = 'P';
446 id4 = 'E'; 488 id4 = 'E';
447 489
448 version = 1; 490 version = 2;
449 491
450 rrtype = RR_TYPE_TXT; 492 rrtype = RR_TYPE_TXT;
451 flags = 0; 493 flags = 0;
452 def_ttl = 0; 494 def_ttl = 0;
453 seq_cdc = 26; 495 syn_cdc = 26;
454 req_cdc = 62; 496 hdr_cdc = 36;
497 req_cdc = conf.dns_case_preserving ? 62 : 36;
455 rep_cdc = 0; 498 rep_cdc = 0;
456 max_size = htons (MAX_PKT_SIZE); 499 max_size = htons (MAX_PKT_SIZE);
457 client = htons (clientid); 500 client = htons (clientid);
458 uid = next_uid++; 501 uid = ++next_uid;
459 delay = 0;
460 502
461 r3 = r4 = 0; 503 r0 = r1 = r2 = r3 = r4 = 0;
462 r4 = r5 = r6 = r7 = 0;
463}
464 504
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
465bool dns_cfg::valid () 526dns_cfg::valid ()
466{ 527{
467 // although the protocol itself allows for some configurability, 528 // although the protocol itself allows for some configurability,
468 // only the following encoding/decoding settings are implemented. 529 // only the following encoding/decoding settings are implemented.
469 return id1 == 'G' 530 return id1 == 'G'
470 && id2 == 'V' 531 && id2 == 'V'
471 && id3 == 'P' 532 && id3 == 'P'
472 && id4 == 'E' 533 && id4 == 'E'
534 && version == 2
473 && seq_cdc == 26 535 && syn_cdc == 26
474 && req_cdc == 62 536 && hdr_cdc == 36
537 && (req_cdc == 36 || req_cdc == 62)
475 && rep_cdc == 0 538 && rep_cdc == 0
476 && version == 1; 539 && chksum == get_chksum ();
477} 540}
478 541
479struct dns_packet : net_packet 542struct dns_packet : net_packet
480{ 543{
481 u16 id; 544 u16 id;
… …
485 u8 data [MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
486 549
487 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
488}; 551};
489 552
553int
490int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
491{ 555{
492 char *orig = data; 556 char *orig = data;
493 557
494 memset (data, 0, size); 558 memset (data, 0, size);
495 559
… …
521 return data - orig; 585 return data - orig;
522} 586}
523 587
524///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
525 589
590static
591u16 next_id ()
592{
526static u16 dns_id = 0; // TODO: should be per-vpn 593 static u16 dns_id = 0; // TODO: should be per-vpn
527 594
528static u16 next_id ()
529{
530 if (!dns_id) 595 if (!dns_id)
531 dns_id = time (0); 596 dns_id = time (0);
532 597
533 // the simplest lsfr with periodicity 65535 i could find 598 // the simplest lsfr with periodicity 65535 i could find
534 dns_id = (dns_id << 1) 599 dns_id = (dns_id << 1)
… …
549 struct vpn *vpn; 614 struct vpn *vpn;
550 615
551 dns_cfg cfg; 616 dns_cfg cfg;
552 617
553 bool established; 618 bool established;
619 const basecoder *cdc;
554 620
555 tstamp last_received; 621 tstamp last_received;
556 tstamp last_sent; 622 tstamp last_sent;
557 double min_latency; 623 double min_latency;
558 double poll_interval, send_interval; 624 double poll_interval, send_interval;
… …
562 byte_stream rcvdq; int rcvseq; int repseq; 628 byte_stream rcvdq; int rcvseq; int repseq;
563 byte_stream snddq; int sndseq; 629 byte_stream snddq; int sndseq;
564 630
565 inline void time_cb (ev::timer &w, int revents); ev::timer tw; 631 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
566 void receive_rep (dns_rcv *r); 632 void receive_rep (dns_rcv *r);
633
634 void reset (); // quite like tcp RST
635 void set_cfg (); // to be called after any cfg changes
567 636
568 dns_connection (connection *c); 637 dns_connection (connection *c);
569 ~dns_connection (); 638 ~dns_connection ();
570}; 639};
571 640
… …
602dns_snd::~dns_snd () 671dns_snd::~dns_snd ()
603{ 672{
604 delete pkt; 673 delete pkt;
605} 674}
606 675
676static void
607static void append_domain (dns_packet &pkt, int &offs, const char *domain) 677append_domain (dns_packet &pkt, int &offs, const char *domain)
608{ 678{
609 // add tunnel domain 679 // add tunnel domain
610 for (;;) 680 for (;;)
611 { 681 {
612 const char *end = strchr (domain, '.'); 682 const char *end = strchr (domain, '.');
… …
625 695
626 domain = end + 1; 696 domain = end + 1;
627 } 697 }
628} 698}
629 699
700void
630void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 701dns_snd::gen_stream_req (int seqno, byte_stream &stream)
631{ 702{
632 stdhdr = true; 703 stdhdr = true;
633 this->seqno = seqno; 704 this->seqno = seqno;
634 705
635 timeout = ev_now () + INITIAL_TIMEOUT; 706 timeout = ev_now () + INITIAL_TIMEOUT;
… …
643 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 714 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
644 715
645 char enc[256], *encp = enc; 716 char enc[256], *encp = enc;
646 encode_header (enc, THISNODE->id, seqno); 717 encode_header (enc, THISNODE->id, seqno);
647 718
648 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); 719 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
649 720
650 if (datalen > stream.size ()) 721 if (datalen > stream.size ())
651 datalen = stream.size (); 722 datalen = stream.size ();
652 723
653 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 724 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
654 stream.remove (datalen); 725 stream.remove (datalen);
655 726
656 while (enclen) 727 while (enclen)
657 { 728 {
658 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 729 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
673 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 744 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
674 745
675 pkt->len = offs; 746 pkt->len = offs;
676} 747}
677 748
749void
678void dns_snd::gen_syn_req () 750dns_snd::gen_syn_req ()
679{ 751{
680 timeout = ev_now () + INITIAL_SYN_TIMEOUT; 752 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
681 753
682 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 754 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
683 pkt->qdcount = htons (1); 755 pkt->qdcount = htons (1);
… …
730{ 802{
731 tw.set<dns_connection, &dns_connection::time_cb> (this); 803 tw.set<dns_connection, &dns_connection::time_cb> (this);
732 804
733 vpn = c->vpn; 805 vpn = c->vpn;
734 806
807 reset ();
808}
809
810dns_connection::~dns_connection ()
811{
812 reset ();
813}
814
815void
816dns_connection::reset ()
817{
818 while (!rcvpq.empty ())
819 {
820 delete rcvpq.back ();
821 rcvpq.pop_back ();
822 }
823
824 for (int i = vpn->dns_sndpq.size (); i--; )
825 if (vpn->dns_sndpq [i]->dns == this)
826 {
827 vpn->dns_sndpq [i] = vpn->dns_sndpq.back ();
828 vpn->dns_sndpq.pop_back ();
829 }
830
735 established = false; 831 established = false;
736 832
737 rcvseq = repseq = sndseq = 0; 833 rcvseq = repseq = sndseq = 0;
738 834
739 last_sent = last_received = 0; 835 last_sent = last_received = 0;
740 poll_interval = 0.5; // starting here 836 poll_interval = 0.5; // starting here
741 send_interval = 0.5; // starting rate 837 send_interval = 0.5; // starting rate
742 min_latency = INITIAL_TIMEOUT; 838 min_latency = INITIAL_TIMEOUT;
743} 839}
744 840
745dns_connection::~dns_connection () 841void
842dns_connection::set_cfg ()
746{ 843{
747 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 844 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
748 i != rcvpq.end ();
749 ++i)
750 delete *i;
751} 845}
752 846
847void
753void dns_connection::receive_rep (dns_rcv *r) 848dns_connection::receive_rep (dns_rcv *r)
754{ 849{
755 if (r->datalen) 850 if (r->datalen)
756 { 851 {
757 last_received = ev_now (); 852 last_received = ev_now ();
758 tw (); 853 tw ();
… …
791 886
792 rcvseq = (rcvseq + 1) & SEQNO_MASK; 887 rcvseq = (rcvseq + 1) & SEQNO_MASK;
793 888
794 if (!rcvdq.put (r->data, r->datalen)) 889 if (!rcvdq.put (r->data, r->datalen))
795 { 890 {
891 // MUST never overflow, can be caused by data corruption, TODO
796 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)"); 892 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
797 abort (); // MUST never overflow, can be caused by data corruption, TODO 893 reset ();
894 return;
798 } 895 }
799 896
800 while (vpn_packet *pkt = rcvdq.get ()) 897 while (vpn_packet *pkt = rcvdq.get ())
801 { 898 {
802 sockinfo si; 899 sockinfo si;
803 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4; 900 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
804 901
805 vpn->recv_vpn_packet (pkt, si); 902 vpn->recv_vpn_packet (pkt, si);
806
807 delete pkt; 903 delete pkt;
808 } 904 }
809 905
810 // check for further packets 906 // check for further packets
811 goto redo; 907 goto redo;
… …
854 { 950 {
855 // correct class, domain: parse 951 // correct class, domain: parse
856 int client, seqno; 952 int client, seqno;
857 decode_header (qname, client, seqno); 953 decode_header (qname, client, seqno);
858 954
859 u8 data[MAXSIZE];
860 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
861
862 if (0 < client && client <= conns.size ()) 955 if (0 < client && client <= conns.size ())
863 { 956 {
864 connection *c = conns [client - 1]; 957 connection *c = conns [client - 1];
865 dns_connection *dns = c->dns; 958 dns_connection *dns = c->dns;
866 dns_rcv *rcv; 959 dns_rcv *rcv;
867 960
868 if (dns) 961 if (dns)
869 { 962 {
963 u8 data[MAXSIZE];
964 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
965
870 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 966 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
871 if (SEQNO_EQ ((*i)->seqno, seqno)) 967 if (SEQNO_EQ ((*i)->seqno, seqno))
872 { 968 {
873 // already seen that request: simply reply with the cached reply 969 // already seen that request: simply reply with the cached reply
874 dns_rcv *r = *i; 970 dns_rcv *r = *i;
… …
975 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 1071 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
976 pkt [offs++] = 0; pkt [offs++] = 0; 1072 pkt [offs++] = 0; pkt [offs++] = 0;
977 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 1073 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
978 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 1074 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
979 1075
980 slog (L_INFO, _("DNS: client %d connects"), client);
981
982 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 1076 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
983 pkt [offs++] = CMD_IP_REJ; 1077 pkt [offs++] = CMD_IP_REJ;
984 1078
985 if (0 < client && client <= conns.size ()) 1079 if (0 < client && client <= conns.size ())
986 { 1080 {
987 connection *c = conns [client - 1]; 1081 connection *c = conns [client - 1];
988 1082
989 if (cfg.valid ()) 1083 if (cfg.valid ())
990 { 1084 {
991 pkt [offs - 1] = CMD_IP_SYN; 1085 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
1086
1087 // check for any encoding mismatches - hints at a case problem
1088 char qname2 [MAX_ENC_LEN];
1089 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
992 1090
993 delete c->dns; 1091 delete c->dns;
1092
1093 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1094 ? CMD_IP_CSE : CMD_IP_SYN;
1095
994 c->dns = new dns_connection (c); 1096 c->dns = new dns_connection (c);
995 c->dns->cfg = cfg; 1097 c->dns->cfg = cfg;
1098 c->dns->set_cfg ();
996 } 1099 }
997 } 1100 }
998 } 1101 }
999 } 1102 }
1000 1103
… …
1020 dns_connection *dns = (*i)->dns; 1123 dns_connection *dns = (*i)->dns;
1021 connection *c = dns->c; 1124 connection *c = dns->c;
1022 int seqno = (*i)->seqno; 1125 int seqno = (*i)->seqno;
1023 u8 data[MAXSIZE], *datap = data; 1126 u8 data[MAXSIZE], *datap = data;
1024 //printf ("rcv pkt %x\n", seqno);//D 1127 //printf ("rcv pkt %x\n", seqno);//D
1128 bool back_off = (*i)->retry;
1025 1129
1026 if ((*i)->retry) 1130 if (back_off)
1027 { 1131 {
1028 dns->send_interval *= 1.01; 1132 dns->send_interval *= 1.01;
1029 if (dns->send_interval > MAX_SEND_INTERVAL) 1133 if (dns->send_interval > MAX_SEND_INTERVAL)
1030 dns->send_interval = MAX_SEND_INTERVAL; 1134 dns->send_interval = MAX_SEND_INTERVAL;
1031 } 1135 }
… …
1071 ttl |= pkt [offs++] << 16; 1175 ttl |= pkt [offs++] << 16;
1072 ttl |= pkt [offs++] << 8; 1176 ttl |= pkt [offs++] << 8;
1073 ttl |= pkt [offs++]; 1177 ttl |= pkt [offs++];
1074 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; 1178 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
1075 1179
1076 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) 1180 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
1077 { 1181 {
1078 if (rdlen <= MAXSIZE - offs) 1182 if (rdlen <= MAXSIZE - offs)
1079 { 1183 {
1080 // decode bytes, finally 1184 // decode bytes, finally
1081 1185
… …
1107 { 1211 {
1108 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); 1212 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1109 1213
1110 if (ip [3] == CMD_IP_RST) 1214 if (ip [3] == CMD_IP_RST)
1111 { 1215 {
1112 slog (L_DEBUG, _("DNS: got tunnel RST request")); 1216 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1113 1217
1114 delete dns; c->dns = 0; 1218 dns->reset ();
1115
1116 return; 1219 return;
1117 } 1220 }
1118 else if (ip [3] == CMD_IP_SYN) 1221 else if (ip [3] == CMD_IP_SYN)
1119 { 1222 {
1120 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); 1223 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1121 dns->established = true; 1224 dns->established = true;
1122 } 1225 }
1226 else if (ip [3] == CMD_IP_CSE)
1227 {
1228 if (conf.dns_case_preserving)
1229 {
1230 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1231 conf.dns_case_preserving = false;
1232 dns->reset ();
1233 return;
1234 }
1235 else
1236 {
1237 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1238 dns->established = true;
1239 }
1240 }
1123 else if (ip [3] == CMD_IP_REJ) 1241 else if (ip [3] == CMD_IP_REJ)
1124 { 1242 {
1125 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting.")); 1243 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1126 abort (); 1244 dns->tw.start (60.);
1127 } 1245 }
1128 else 1246 else
1247 {
1129 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); 1248 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1249 dns->tw.start (60.);
1250 }
1130 } 1251 }
1131 else 1252 else
1132 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), 1253 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1133 ip [0], ip [1], ip [2], ip [3]); 1254 ip [0], ip [1], ip [2], ip [3]);
1134 1255
… …
1152 } 1273 }
1153 1274
1154 // todo: pkt now used 1275 // todo: pkt now used
1155 if (datap) 1276 if (datap)
1156 dns->receive_rep (new dns_rcv (seqno, data, datap - data)); 1277 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
1278 else if (dns_sndpq.empty ()) // no data received, and nothing to send - idle
1279 {
1280 dns->send_interval *= 1.1;
1281
1282 if (dns->send_interval < MIN_POLL_INTERVAL)
1283 dns->send_interval = MIN_POLL_INTERVAL;
1284
1285 if (dns->send_interval > MAX_POLL_INTERVAL && !back_off)
1286 dns->send_interval = MAX_POLL_INTERVAL;
1287 }
1157 1288
1158 break; 1289 break;
1159 } 1290 }
1160} 1291}
1161 1292
… …
1202 1333
1203 // always return true even if the buffer overflows 1334 // always return true even if the buffer overflows
1204 return true; 1335 return true;
1205} 1336}
1206 1337
1207void
1208connection::dnsv4_reset_connection ()
1209{
1210 //delete dns; dns = 0; //TODO
1211}
1212
1213#define NEXT(w) do { if (next > (w)) next = w; } while (0) 1338#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1214 1339
1215void 1340void
1216dns_connection::time_cb (ev::timer &w, int revents) 1341dns_connection::time_cb (ev::timer &w, int revents)
1217{ 1342{
… …
1258 if (vpn->dns_sndpq.empty ()) 1383 if (vpn->dns_sndpq.empty ())
1259 { 1384 {
1260 send = new dns_snd (this); 1385 send = new dns_snd (this);
1261 1386
1262 cfg.reset (THISNODE->id); 1387 cfg.reset (THISNODE->id);
1388 set_cfg ();
1263 send->gen_syn_req (); 1389 send->gen_syn_req ();
1264 } 1390 }
1265 } 1391 }
1266 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding 1392 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1267 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) 1393 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))

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