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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.15 by pcg, Fri Mar 4 10:15:45 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_POLL_INTERVAL .02 // how often to poll minimally when the server has data 64#define MIN_POLL_INTERVAL 0.025 // poll at most this often when no data received
49#define MAX_POLL_INTERVAL 6. // 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
50#define ACTIVITY_INTERVAL 5.
51 66
52#define INITIAL_TIMEOUT 1. // retry timeouts 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn 68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
54 69
55#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
56#define MAX_SEND_INTERVAL 0.5 // optimistic? 70#define MAX_SEND_INTERVAL 5. // optimistic?
57 71
58#define MAX_OUTSTANDING 40 // max. outstanding requests
59#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
60#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
61 74
62#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
63// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
64// every two request bytes less give room for one reply byte 77// every request byte less give room for two reply bytes
65 78
66#define SEQNO_MASK 0xffff 79#define SEQNO_MASK 0x3fff
67#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
68 81
69#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
70#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
71 84
72#define RR_TYPE_A 1 85#define RR_TYPE_A 1
73#define RR_TYPE_NULL 10 86#define RR_TYPE_NULL 10
74#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
75#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
76 90
77#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
78 92
79#define CMD_IP_1 207 93#define CMD_IP_1 207
80#define CMD_IP_2 46 94#define CMD_IP_2 46
81#define CMD_IP_3 236 95#define CMD_IP_3 236
82#define CMD_IP_RST 29 96
83#define CMD_IP_SYN 113 97#define CMD_IP_RST 29 // some error, reset and retry
84#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}
85 113
86// works for cmaps up to 255 (not 256!) 114// works for cmaps up to 255 (not 256!)
87struct charmap 115struct charmap
88{ 116{
89 enum { INVALID = (u8)255 }; 117 enum { INVALID = (u8)255 };
… …
103 memset (enc, (char) 0, 256); 131 memset (enc, (char) 0, 256);
104 memset (dec, (char)INVALID, 256); 132 memset (dec, (char)INVALID, 256);
105 133
106 for (size = 0; cmap [size]; size++) 134 for (size = 0; cmap [size]; size++)
107 { 135 {
136 char c = cmap [size];
137
108 enc [size] = cmap [size]; 138 enc [size] = c;
109 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;
110 } 144 }
111 145
112 assert (size < 256); 146 assert (size < 256);
113} 147}
114 148
… …
121{ 155{
122 charmap cmap; 156 charmap cmap;
123 unsigned int enc_len [MAX_DEC_LEN]; 157 unsigned int enc_len [MAX_DEC_LEN];
124 unsigned int dec_len [MAX_ENC_LEN]; 158 unsigned int dec_len [MAX_ENC_LEN];
125 159
126 unsigned int encode_len (unsigned int len); 160 unsigned int encode_len (unsigned int len) const;
127 unsigned int decode_len (unsigned int len); 161 unsigned int decode_len (unsigned int len) const;
128 162
129 unsigned int encode (char *dst, u8 *src, unsigned int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
130 unsigned int decode (u8 *dst, char *src, unsigned int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
131 165
132 basecoder (const char *cmap); 166 basecoder (const char *cmap);
133}; 167};
134 168
135basecoder::basecoder (const char *cmap) 169basecoder::basecoder (const char *cmap)
… …
154 enc_len [len] = n; 188 enc_len [len] = n;
155 dec_len [n] = len; 189 dec_len [n] = len;
156 } 190 }
157} 191}
158 192
193unsigned int
159unsigned int basecoder::encode_len (unsigned int len) 194basecoder::encode_len (unsigned int len) const
160{ 195{
161 return enc_len [len]; 196 return enc_len [len];
162} 197}
163 198
199unsigned int
164unsigned int basecoder::decode_len (unsigned int len) 200basecoder::decode_len (unsigned int len) const
165{ 201{
166 while (len && !dec_len [len]) 202 while (len && !dec_len [len])
167 --len; 203 --len;
168 204
169 return dec_len [len]; 205 return dec_len [len];
170} 206}
171 207
208unsigned int
172unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 209basecoder::encode (char *dst, u8 *src, unsigned int len) const
173{ 210{
174 if (!len || len > MAX_DEC_LEN) 211 if (!len || len > MAX_DEC_LEN)
175 return 0; 212 return 0;
176 213
177 int elen = encode_len (len); 214 int elen = encode_len (len);
… …
196 *dst++ = cmap.encode [dst_ [i]]; 233 *dst++ = cmap.encode [dst_ [i]];
197 234
198 return elen; 235 return elen;
199} 236}
200 237
238unsigned int
201unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 239basecoder::decode (u8 *dst, char *src, unsigned int len) const
202{ 240{
203 if (!len || len > MAX_ENC_LEN) 241 if (!len || len > MAX_ENC_LEN)
204 return 0; 242 return 0;
205 243
206 u8 src_ [MAX_ENC_LEN]; 244 u8 src_ [MAX_ENC_LEN];
… …
255 } 293 }
256 abort (); 294 abort ();
257} 295}
258#endif 296#endif
259 297
260//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
261//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
262static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
263//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet 299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
264static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
265 301
266///////////////////////////////////////////////////////////////////////////// 302/////////////////////////////////////////////////////////////////////////////
267 303
268#define HDRSIZE 6 304#define HDRSIZE 5
269 305
306inline void
270inline void encode_header (char *data, int clientid, int seqno) 307encode_header (char *data, int clientid, int seqno, int retry = 0)
271{ 308{
272 u8 hdr[3] = { clientid, seqno >> 8, seqno };
273
274 assert (clientid < 256); 309 assert (clientid < 256);
275 310
311 seqno &= SEQNO_MASK;
312
313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
316 clientid,
317 };
318
276 cdc26.encode (data, hdr, 3); 319 cdc36.encode (data, hdr, 3);
277} 320}
278 321
322inline void
279inline void decode_header (char *data, int &clientid, int &seqno) 323decode_header (char *data, int &clientid, int &seqno)
280{ 324{
281 u8 hdr[3]; 325 u8 hdr[3];
282 326
283 cdc26.decode (hdr, data, HDRSIZE); 327 cdc36.decode (hdr, data, HDRSIZE);
284 328
285 clientid = hdr[0]; 329 clientid = hdr[2];
286 seqno = (hdr[1] << 8) | hdr[2]; 330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
287} 331}
288 332
289///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
290 334
291struct byte_stream 335struct byte_stream
… …
317byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
318{ 362{
319 delete data; 363 delete data;
320} 364}
321 365
366void
322void byte_stream::remove (int count) 367byte_stream::remove (int count)
323{ 368{
324 if (count > fill) 369 if (count > fill)
325 abort (); 370 assert (count <= fill);
326 371
327 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
328} 373}
329 374
375bool
330bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
331{ 377{
332 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
333 return false; 379 return false;
334 380
335 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
336 382
337 return true; 383 return true;
338} 384}
339 385
386bool
340bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
341{ 388{
342 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
343 return false; 390 return false;
344 391
345 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
… …
350 return true; 397 return true;
351} 398}
352 399
353vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
354{ 401{
402 if (fill < 2)
403 return 0;
404
405 unsigned int len;
406
407 for (;;)
408 {
355 unsigned int len = (data [0] << 8) | data [1]; 409 len = (data [0] << 8) | data [1];
356 410
357 if (len > MAXSIZE && fill >= 2) 411 if (len <= MAXSIZE)
358 abort (); // TODO handle this gracefully, connection reset 412 break;
359 413
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
360 if (fill < len + 2) 419 if (fill < len + 2)
361 return 0; 420 return 0;
362 421
363 vpn_packet *pkt = new vpn_packet; 422 vpn_packet *pkt = new vpn_packet;
364 423
… …
392 451
393struct dns_cfg 452struct dns_cfg
394{ 453{
395 static int next_uid; 454 static int next_uid;
396 455
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
397 u8 id1, id2, id3, id4; 464 u8 id1, id2, id3, id4;
398 u8 version; 465
399 u8 rrtype; 466 u16 client;
400 u8 flags;
401 u8 def_ttl; 467 u8 def_ttl;
402 u8 rcv_cdc; 468 u8 r0;
403 u8 snd_cdc;
404 u16 max_size;
405 u16 client;
406 u16 uid; // to make request unique
407 469
408 u8 reserved[8]; 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;
409 476
410 void reset (int clientid); 477 void reset (int clientid);
411 bool valid (); 478 bool valid ();
479 u8 get_chksum ();
412}; 480};
413 481
414int dns_cfg::next_uid; 482int dns_cfg::next_uid;
415 483
484void
416void dns_cfg::reset (int clientid) 485dns_cfg::reset (int clientid)
417{ 486{
487 // this ID must result in some mixed-case characters in cdc26-encoding
418 id1 = 'G'; 488 id1 = 'G';
419 id2 = 'V'; 489 id2 = 'V';
420 id3 = 'P'; 490 id3 = 'P';
421 id4 = 'E'; 491 id4 = 'E';
422 492
423 version = 1; 493 version = 2;
424 494
425 rrtype = RR_TYPE_TXT; 495 rrtype = RR_TYPE_TXT;
426 flags = 0; 496 flags = 0;
427 def_ttl = 0; 497 def_ttl = 0;
428 rcv_cdc = 0;
429 snd_cdc = 62; 498 syn_cdc = 26;
499 hdr_cdc = 36;
500 req_cdc = conf.dns_case_preserving ? 62 : 36;
501 rep_cdc = 0;
430 max_size = ntohs (MAX_PKT_SIZE); 502 max_size = htons (MAX_PKT_SIZE);
431 client = ntohs (clientid); 503 client = htons (clientid);
432 uid = next_uid++; 504 uid = ++next_uid;
433 505
434 memset (reserved, 0, 8); 506 r0 = r1 = r2 = r3 = r4 = 0;
435}
436 507
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
437bool dns_cfg::valid () 529dns_cfg::valid ()
438{ 530{
531 // although the protocol itself allows for some configurability,
532 // only the following encoding/decoding settings are implemented.
439 return id1 == 'G' 533 return id1 == 'G'
440 && id2 == 'V' 534 && id2 == 'V'
441 && id3 == 'P' 535 && id3 == 'P'
442 && id4 == 'E' 536 && id4 == 'E'
443 && version == 1 537 && version == 2
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62 538 && syn_cdc == 26
447 && max_size == ntohs (MAX_PKT_SIZE); 539 && hdr_cdc == 36
540 && (req_cdc == 36 || req_cdc == 62)
541 && rep_cdc == 0
542 && chksum == get_chksum ();
448} 543}
449 544
450struct dns_packet : net_packet 545struct dns_packet : net_packet
451{ 546{
452 u16 id; 547 u16 id;
453 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
454 u16 qdcount, ancount, nscount, arcount; 549 u16 qdcount, ancount, nscount, arcount;
455 550
456 u8 data[MAXSIZE - 6 * 2]; 551 u8 data [MAXSIZE - 6 * 2];
457 552
458 int decode_label (char *data, int size, int &offs); 553 int decode_label (char *data, int size, int &offs);
459}; 554};
460 555
556int
461int dns_packet::decode_label (char *data, int size, int &offs) 557dns_packet::decode_label (char *data, int size, int &offs)
462{ 558{
463 char *orig = data; 559 char *orig = data;
464 560
465 memset (data, 0, size); 561 memset (data, 0, size);
466 562
… …
492 return data - orig; 588 return data - orig;
493} 589}
494 590
495///////////////////////////////////////////////////////////////////////////// 591/////////////////////////////////////////////////////////////////////////////
496 592
497struct dns_snd 593static
594u16 next_id ()
498{ 595{
499 dns_packet *pkt;
500 tstamp timeout, sent;
501 int retry;
502 struct dns_connection *dns;
503 int seqno;
504
505 void gen_stream_req (int seqno, byte_stream &stream);
506 void gen_syn_req (const dns_cfg &cfg);
507
508 dns_snd (dns_connection *dns);
509 ~dns_snd ();
510};
511
512static u16 dns_id = 12098; // TODO: should be per-vpn 596 static u16 dns_id = 0; // TODO: should be per-vpn
513 597
514static u16 next_id () 598#if 1
515{ 599 if (!dns_id)
600 dns_id = time (0);
601
516 // the simplest lsfr with periodicity 65535 i could find 602 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 603 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 604 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 605 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 606 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 607 ^ (dns_id >> 15)) & 1);
522 608
523 return dns_id; 609 return dns_id;
610#else
611 dns_id++;//D
612
613 return htons (dns_id);
614#endif
524} 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};
525 665
526dns_snd::dns_snd (dns_connection *dns) 666dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 667: dns (dns)
528{ 668{
529 timeout = 0; 669 timeout = 0;
530 retry = 0; 670 retry = 0;
531 seqno = 0; 671 seqno = 0;
532 sent = NOW; 672 sent = ev_now ();
673 stdhdr = false;
533 674
534 pkt = new dns_packet; 675 pkt = new dns_packet;
535 676
536 pkt->id = next_id (); 677 pkt->id = next_id ();
537} 678}
… …
539dns_snd::~dns_snd () 680dns_snd::~dns_snd ()
540{ 681{
541 delete pkt; 682 delete pkt;
542} 683}
543 684
685static void
544static void append_domain (dns_packet &pkt, int &offs, const char *domain) 686append_domain (dns_packet &pkt, int &offs, const char *domain)
545{ 687{
546 // add tunnel domain 688 // add tunnel domain
547 for (;;) 689 for (;;)
548 { 690 {
549 const char *end = strchr (domain, '.'); 691 const char *end = strchr (domain, '.');
… …
562 704
563 domain = end + 1; 705 domain = end + 1;
564 } 706 }
565} 707}
566 708
709void
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 710dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 711{
712 stdhdr = true;
569 this->seqno = seqno; 713 this->seqno = seqno;
570 714
571 timeout = NOW + INITIAL_TIMEOUT; 715 timeout = ev_now () + INITIAL_TIMEOUT;
572 716
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 717 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 718 pkt->qdcount = htons (1);
575 719
576 int offs = 6*2; 720 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 721 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
578 // 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,
579 // 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
580 724
581 char enc[256], *encp = enc; 725 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 726 encode_header (enc, THISNODE->id, seqno);
583 727
584 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);
585 729
586 if (datalen > stream.size ()) 730 if (datalen > stream.size ())
587 datalen = stream.size (); 731 datalen = stream.size ();
588 732
589 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 733 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
590 stream.remove (datalen); 734 stream.remove (datalen);
591 735
592 while (enclen) 736 while (enclen)
593 { 737 {
594 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 738 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
600 encp += lbllen; 744 encp += lbllen;
601 745
602 enclen -= lbllen; 746 enclen -= lbllen;
603 } 747 }
604 748
605 append_domain (*pkt, offs, THISNODE->domain); 749 append_domain (*pkt, offs, dns->c->conf->domain);
606 750
607 (*pkt)[offs++] = 0; 751 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 752 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 753 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 754
611 pkt->len = offs; 755 pkt->len = offs;
612} 756}
613 757
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 758void
759dns_snd::gen_syn_req ()
615{ 760{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 761 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
617 762
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 763 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 764 pkt->qdcount = htons (1);
620 765
621 int offs = 6*2; 766 int offs = 6 * 2;
622 767
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 768 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 769
625 assert (elen <= MAX_LBL_SIZE); 770 assert (elen <= MAX_LBL_SIZE);
626 771
627 (*pkt)[offs] = elen; 772 (*pkt)[offs] = elen;
628 offs += elen + 1; 773 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 774 append_domain (*pkt, offs, dns->c->conf->domain);
630 775
631 (*pkt)[offs++] = 0; 776 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 777 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 778 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 779
… …
657 delete pkt; 802 delete pkt;
658} 803}
659 804
660///////////////////////////////////////////////////////////////////////////// 805/////////////////////////////////////////////////////////////////////////////
661 806
662struct dns_connection
663{
664 connection *c;
665 struct vpn *vpn;
666
667 dns_cfg cfg;
668
669 bool established;
670
671 tstamp last_received;
672 tstamp last_sent;
673 double poll_interval, send_interval;
674
675 vector<dns_rcv *> rcvpq;
676
677 byte_stream rcvdq; int rcvseq;
678 byte_stream snddq; int sndseq;
679
680 void time_cb (time_watcher &w); time_watcher tw;
681 void receive_rep (dns_rcv *r);
682
683 dns_connection (connection *c);
684 ~dns_connection ();
685};
686
687dns_connection::dns_connection (connection *c) 807dns_connection::dns_connection (connection *c)
688: c (c) 808: c (c)
689, rcvdq (MAX_BACKLOG * 2) 809, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 810, snddq (MAX_BACKLOG)
691, tw (this, &dns_connection::time_cb)
692{ 811{
812 tw.set<dns_connection, &dns_connection::time_cb> (this);
813
693 vpn = c->vpn; 814 vpn = c->vpn;
694 815
816 reset ();
817}
818
819dns_connection::~dns_connection ()
820{
821 reset ();
822}
823
824void
825dns_connection::reset ()
826{
827 while (!rcvpq.empty ())
828 {
829 delete rcvpq.back ();
830 rcvpq.pop_back ();
831 }
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
695 established = false; 840 established = false;
696 841
697 rcvseq = sndseq = 0; 842 rcvseq = repseq = sndseq = 0;
698 843
699 last_sent = last_received = 0; 844 last_sent = 0;
700 poll_interval = MIN_POLL_INTERVAL; 845 poll_interval = 0.5; // starting here
701 send_interval = 0.2; // starting rate 846 send_interval = 0.5; // starting rate
847 min_latency = INITIAL_TIMEOUT;
702} 848}
703 849
704dns_connection::~dns_connection () 850void
851dns_connection::set_cfg ()
705{ 852{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 853 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
707 i != rcvpq.end ();
708 ++i)
709 delete *i;
710} 854}
711 855
856void
712void dns_connection::receive_rep (dns_rcv *r) 857dns_connection::receive_rep (dns_rcv *r)
713{ 858{
714 if (r->datalen) 859 if (r->datalen)
715 { 860 poll_interval = max (poll_interval * (1. / 1.2), MIN_POLL_INTERVAL);
716 last_received = NOW;
717 tw.trigger ();
718
719 poll_interval = send_interval;
720 }
721 else 861 else
722 { 862 poll_interval = min (poll_interval * 1.1, MAX_POLL_INTERVAL);
723 poll_interval *= 1.1;
724 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL;
726 }
727 863
728 rcvpq.push_back (r); 864 rcvpq.push_back (r);
729 865
730 redo: 866 redo:
731 867
732 // find next packet 868 // find next packet
733 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 869 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
734 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 870 if (SEQNO_EQ (rcvseq, (*i)->seqno))
735 { 871 {
872 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
736 // enter the packet into our input stream 873 // enter the packet into our input stream
737 r = *i; 874 r = *i;
738 875
739 // remove the oldest packet, look forward, as it's oldest first 876 // remove the oldest packet, look forward, as it's oldest first
740 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)
741 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 878 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
742 { 879 {
880 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
743 delete *j; 881 delete *j;
744 rcvpq.erase (j); 882 rcvpq.erase (j);
745 break; 883 break;
746 } 884 }
747 885
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 886 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 887
750 if (!rcvdq.put (r->data, r->datalen)) 888 if (!rcvdq.put (r->data, r->datalen))
889 {
751 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 }
752 895
753 while (vpn_packet *pkt = rcvdq.get ()) 896 while (vpn_packet *pkt = rcvdq.get ())
754 { 897 {
755 sockinfo si; 898 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 899 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
757 900
758 vpn->recv_vpn_packet (pkt, si); 901 vpn->recv_vpn_packet (pkt, si);
759
760 delete pkt; 902 delete pkt;
761 } 903 }
762 904
763 // check for further packets 905 // check for further packets
764 goto redo; 906 goto redo;
… …
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 917 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 918
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 919 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 920 && pkt.qdcount == htons (1))
779 { 921 {
780 char qname[MAXSIZE]; 922 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 923 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 924
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 925 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 926 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 927
786 pkt.qdcount = htons (1); 928 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 929 pkt.ancount = 0;
788 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
789 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
790 932
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 933 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 934
793 int dlen = strlen (THISNODE->domain); 935 int dlen = strlen (THISNODE->domain);
794 936
795 if (qclass == RR_CLASS_IN 937 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 938 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 939 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 940 {
799 // now generate reply 941 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 942 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 943 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 944
… …
807 { 949 {
808 // correct class, domain: parse 950 // correct class, domain: parse
809 int client, seqno; 951 int client, seqno;
810 decode_header (qname, client, seqno); 952 decode_header (qname, client, seqno);
811 953
812 u8 data[MAXSIZE];
813 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
814
815 if (0 < client && client <= conns.size ()) 954 if (0 < client && client <= conns.size ())
816 { 955 {
817 connection *c = conns [client - 1]; 956 connection *c = conns [client - 1];
818 dns_connection *dns = c->dns; 957 dns_connection *dns = c->dns;
819 dns_rcv *rcv; 958 dns_rcv *rcv;
820 959
821 if (dns) 960 if (dns)
822 { 961 {
962 u8 data[MAXSIZE];
963 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
964
823 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 (); )
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 966 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 967 {
826 // already seen that request: simply reply with the cached reply 968 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 969 dns_rcv *r = *i;
828 970
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 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;
830 976
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 977 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 978
833 goto duplicate_request; 979 goto duplicate_request;
834 } 980 }
835 981
836 // new packet, queue 982 // new packet, queue
837 rcv = new dns_rcv (seqno, data, datalen); 983 rcv = new dns_rcv (seqno, data, datalen);
838 dns->receive_rep (rcv); 984 dns->receive_rep (rcv);
839 } 985 }
840 986
987 {
841 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 988 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
842 989
843 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 990 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
844 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type 991 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
845 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 992 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
846 pkt [offs++] = 0; pkt [offs++] = 0; 993 pkt [offs++] = 0; pkt [offs++] = 0;
847 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 994 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
848 995
849 int rdlen_offs = offs += 2; 996 int rdlen_offs = offs += 2;
850 997
998 if (dns)
999 {
851 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 1000 int dlen = ntohs (dns->cfg.max_size) - offs;
1001
852 // bind doesn't compress well, so reduce further by one label length 1002 // bind doesn't compress well, so reduce further by one label length
853 dlen -= qlen; 1003 dlen -= qlen;
854 1004
855 if (dns) 1005 // only put data into in-order sequence packets, if
856 { 1006 // we receive out-of-order packets we generate empty
857 while (dlen > 1 && !dns->snddq.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)
858 { 1010 {
1011 dns->repseq = seqno;
1012
1013 while (dlen > 1 && !dns->snddq.empty ())
1014 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1015 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 1016
861 if (txtlen > dns->snddq.size ()) 1017 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 1018 txtlen = dns->snddq.size ();
863 1019
864 pkt[offs++] = txtlen; 1020 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 1021 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 1022 offs += txtlen;
867 dns->snddq.remove (txtlen); 1023 dns->snddq.remove (txtlen);
868 1024
869 dlen -= txtlen + 1; 1025 dlen -= txtlen + 1;
1026 }
870 } 1027 }
871 1028
872 // avoid empty TXT rdata 1029 // avoid completely empty TXT rdata
873 if (offs == rdlen_offs) 1030 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 1031 pkt[offs++] = 0;
875 1032
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 1033 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 1034 }
878 else 1035 else
879 { 1036 {
880 // send RST 1037 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 1038 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 1039 pkt [offs++] = CMD_IP_RST;
883 } 1040 }
884 1041
885 int rdlen = offs - rdlen_offs; 1042 int rdlen = offs - rdlen_offs;
886 1043
887 pkt [rdlen_offs - 2] = rdlen >> 8; 1044 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 1045 pkt [rdlen_offs - 1] = rdlen;
889 1046
890 if (dns) 1047 if (dns)
891 { 1048 {
892 // now update dns_rcv copy 1049 // now update dns_rcv copy
893 rcv->pkt->len = offs; 1050 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 1051 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 1052 }
1053 }
896 1054
897 duplicate_request: ; 1055 duplicate_request: ;
898 } 1056 }
899 else 1057 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 1058 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
… …
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 1070 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 1071 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 1072 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 1073 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 1074
917 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client);
918
919 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 1075 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 1076 pkt [offs++] = CMD_IP_REJ;
921 1077
922 if (0 < client && client <= conns.size ()) 1078 if (0 < client && client <= conns.size ())
923 { 1079 {
924 connection *c = conns [client - 1]; 1080 connection *c = conns [client - 1];
925 1081
926 if (cfg.valid ()) 1082 if (cfg.valid ())
927 { 1083 {
928 pkt [offs - 1] = CMD_IP_SYN; 1084 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
1085
1086 // check for any encoding mismatches - hints at a case problem
1087 char qname2 [MAX_ENC_LEN];
1088 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
929 1089
930 delete c->dns; 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
931 c->dns = new dns_connection (c); 1095 c->dns = new dns_connection (c);
932 c->dns->cfg = cfg; 1096 c->dns->cfg = cfg;
1097 c->dns->set_cfg ();
933 } 1098 }
934 } 1099 }
935 } 1100 }
936 } 1101 }
937 1102
… …
956 { 1121 {
957 dns_connection *dns = (*i)->dns; 1122 dns_connection *dns = (*i)->dns;
958 connection *c = dns->c; 1123 connection *c = dns->c;
959 int seqno = (*i)->seqno; 1124 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1125 u8 data[MAXSIZE], *datap = data;
1126 //printf ("rcv pkt %x\n", seqno);//D
961 1127
962 if ((*i)->retry) 1128 if ((*i)->retry)
963 { 1129 {
964 dns->send_interval *= 1.001; 1130 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1131 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1132 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1133 }
968 else 1134 else
969 { 1135 {
970#if 1 1136#if 0
971 dns->send_interval *= 0.9999; 1137 dns->send_interval *= 0.999;
972#endif 1138#endif
973 if (dns->send_interval < MIN_SEND_INTERVAL)
974 dns->send_interval = MIN_SEND_INTERVAL;
975
976 // the latency surely puts an upper bound on 1139 // the latency surely puts an upper bound on
977 // the minimum send interval 1140 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1141 double latency = ev_now () - (*i)->sent;
979 1142
980 if (dns->send_interval > latency) 1143 if (latency < dns->min_latency)
981 dns->send_interval = 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;
982 } 1151 }
983 1152
984 delete *i; 1153 delete *i;
985 dns_sndpq.erase (i); 1154 dns_sndpq.erase (i);
986 1155
… …
1004 ttl |= pkt [offs++] << 16; 1173 ttl |= pkt [offs++] << 16;
1005 ttl |= pkt [offs++] << 8; 1174 ttl |= pkt [offs++] << 8;
1006 ttl |= pkt [offs++]; 1175 ttl |= pkt [offs++];
1007 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; 1176 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
1008 1177
1009 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) 1178 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
1010 { 1179 {
1011 if (rdlen <= MAXSIZE - offs) 1180 if (rdlen <= MAXSIZE - offs)
1012 { 1181 {
1013 // decode bytes, finally 1182 // decode bytes, finally
1014 1183
… …
1036 1205
1037 if (ip [0] == CMD_IP_1 1206 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1207 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1208 && ip [2] == CMD_IP_3)
1040 { 1209 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1210 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1211
1043 if (ip [3] == CMD_IP_RST) 1212 if (ip [3] == CMD_IP_RST)
1044 { 1213 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1214 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1046 1215
1047 delete dns; c->dns = 0; 1216 dns->reset ();
1048
1049 return; 1217 return;
1050 } 1218 }
1051 else if (ip [3] == CMD_IP_SYN) 1219 else if (ip [3] == CMD_IP_SYN)
1052 { 1220 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1221 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 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 }
1055 } 1238 }
1056 else if (ip [3] == CMD_IP_REJ) 1239 else if (ip [3] == CMD_IP_REJ)
1057 { 1240 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1241 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1059 abort (); 1242 dns->tw.start (60.);
1060 } 1243 }
1061 else 1244 else
1245 {
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1246 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1247 dns->tw.start (60.);
1248 }
1063 } 1249 }
1064 else 1250 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1251 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1252 ip [0], ip [1], ip [2], ip [3]);
1067 1253
1068 return; 1254 return;
1069 } 1255 }
1070 1256
1071 int client, rseqno; 1257 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1258 decode_header (qname, client, rseqno);
1073 1259
1074 if (client != THISNODE->id) 1260 if (client != THISNODE->id)
1075 { 1261 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1262 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1263 datap = 0;
1078 } 1264 }
1079 else if (rseqno != seqno) 1265 else if (rseqno != seqno)
1080 { 1266 {
1081 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?"));
1082 datap = 0; 1268 datap = 0;
1083 } 1269 }
1084 } 1270 }
1085 } 1271 }
1086 1272
… …
1091 break; 1277 break;
1092 } 1278 }
1093} 1279}
1094 1280
1095void 1281void
1096vpn::dnsv4_ev (io_watcher &w, short revents) 1282vpn::dnsv4_ev (ev::io &w, int revents)
1097{ 1283{
1098 if (revents & EVENT_READ) 1284 if (revents & EV_READ)
1099 { 1285 {
1100 dns_packet *pkt = new dns_packet; 1286 dns_packet *pkt = new dns_packet;
1101 struct sockaddr_in sa; 1287 struct sockaddr_in sa;
1102 socklen_t sa_len = sizeof (sa); 1288 socklen_t sa_len = sizeof (sa);
1103 1289
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1290 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1291
1106 if (pkt->len > 0) 1292 if (pkt->len > 0)
1107 { 1293 {
1108 if (THISNODE->dns_port) 1294 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1295 dnsv4_client (*pkt);
1296 else
1109 { 1297 {
1110 dnsv4_server (*pkt); 1298 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1299 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1300 }
1113 else
1114 dnsv4_client (*pkt);
1115 1301
1116 delete pkt; 1302 delete pkt;
1117 } 1303 }
1118 } 1304 }
1119} 1305}
1120 1306
1121bool 1307bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1308vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1309{
1310 int client = ntohl (si.host);
1311
1312 assert (0 < client && client <= conns.size ());
1313
1314 connection *c = conns [client - 1];
1315
1124 if (!dns) 1316 if (!c->dns)
1125 dns = new dns_connection (this); 1317 c->dns = new dns_connection (c);
1126 1318
1127 if (!dns->snddq.put (pkt)) 1319 if (c->dns->snddq.put (pkt))
1128 return false; 1320 {
1321 min_it (c->dns->poll_interval, 0.25);
1322 c->dns->tw ();
1323 }
1129 1324
1130 dns->tw.trigger (); 1325 // always return true even if the buffer overflows
1131
1132 return true; 1326 return true;
1133} 1327}
1134 1328
1135void 1329void
1136connection::dnsv4_reset_connection () 1330dns_connection::time_cb (ev::timer &w, int revents)
1137{
1138 //delete dns; dns = 0; //TODO
1139}
1140
1141#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1142
1143void
1144dns_connection::time_cb (time_watcher &w)
1145{ 1331{
1146 // servers have to be polled 1332 // servers have to be polled
1147 if (THISNODE->dns_port) 1333 if (THISNODE->dns_port)
1148 return; 1334 return;
1149 1335
1150 // check for timeouts and (re)transmit 1336 // check for timeouts and (re)transmit
1151 tstamp next = NOW + poll_interval; 1337 tstamp next = 86400 * 365;
1152 dns_snd *send = 0; 1338 dns_snd *send = 0;
1153 1339
1154 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); 1340 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
1155 i != vpn->dns_sndpq.end (); 1341 i != vpn->dns_sndpq.end ();
1156 ++i) 1342 ++i)
1157 { 1343 {
1158 dns_snd *r = *i; 1344 dns_snd *r = *i;
1159 1345
1160 if (r->timeout <= NOW) 1346 if (r->timeout <= ev_now ())
1161 { 1347 {
1162 if (!send) 1348 if (!send)
1163 { 1349 {
1164 send = r; 1350 send = r;
1165 1351
1166 r->retry++; 1352 r->retry++;
1167 r->timeout = 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);
1168 } 1360 }
1169 } 1361 }
1170 else 1362 else
1171 NEXT (r->timeout); 1363 min_it (next, r->timeout - ev_now ());
1172 }
1173
1174 if (last_sent + send_interval <= NOW)
1175 { 1364 }
1365
1176 if (!send) 1366 if (!send)
1367 {
1368 // generate a new packet, if wise
1369
1370 if (!established)
1177 { 1371 {
1178 // generate a new packet, if wise
1179
1180 if (!established)
1181 {
1182 if (vpn->dns_sndpq.empty ()) 1372 if (vpn->dns_sndpq.empty ())
1183 {
1184 send = new dns_snd (this);
1185
1186 cfg.reset (THISNODE->id);
1187 send->gen_syn_req (cfg);
1188 }
1189 }
1190 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING)
1191 { 1373 {
1192 send = new dns_snd (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);
1193 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
1194 1394
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1395 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1396 }
1197 1397 else
1198 if (send) 1398 min_it (next, last_sent + send_interval - ev_now ());
1199 vpn->dns_sndpq.push_back (send);
1200 } 1399 }
1201 1400
1202 if (send) 1401 if (send)
1203 { 1402 vpn->dns_sndpq.push_back (send);
1204 last_sent = NOW; 1403 }
1404
1405 if (send)
1406 {
1407 last_sent = ev_now ();
1205 sendto (vpn->dnsv4_fd, 1408 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1409 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1410 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1411 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1412
1413 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1414
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1415 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1416 poll_interval, send_interval, next - ev_now (),
1215 vpn->dns_sndpq.size (), snddq.size ()); 1417 vpn->dns_sndpq.size (), snddq.size (),
1216 1418 rcvpq.size ());
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem
1218 if (next < NOW + 0.0001)
1219 next = NOW + 0.1;
1220 1419
1221 w.start (next); 1420 w.start (next);
1222} 1421}
1223 1422
1224#endif 1423#endif

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