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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.10 by pcg, Fri Mar 4 08:15:04 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 .2 // how often to poll minimally when the server is having 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. 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 2. 68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
54 69
55#define MIN_SEND_INTERVAL (1./1000.)
56#define MAX_SEND_INTERVAL 0.5 // optimistic? 70#define MAX_SEND_INTERVAL 5. // optimistic?
57 71
58#define MAX_OUTSTANDING 400 // max. outstanding requests
59#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
60#define MAX_RATE 100 // requests/s
61#define MAX_BACKLOG (100*1024) // size of protocol backlog, must be > MAXSIZE 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
62 74
63#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
64// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
65// every two request byte sless give room for one reply byte 77// every request byte less give room for two reply bytes
66 78
67#define SEQNO_MASK 0xffff 79#define SEQNO_MASK 0x3fff
68#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
69 81
70#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
71#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
72 84
73#define RR_TYPE_A 1 85#define RR_TYPE_A 1
74#define RR_TYPE_NULL 10 86#define RR_TYPE_NULL 10
75#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
76#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
77 90
78#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
79 92
80#define CMD_IP_1 207 93#define CMD_IP_1 207
81#define CMD_IP_2 46 94#define CMD_IP_2 46
82#define CMD_IP_3 236 95#define CMD_IP_3 236
83#define CMD_IP_RST 29 96
84#define CMD_IP_SYN 113 97#define CMD_IP_RST 29 // some error, reset and retry
85#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}
86 113
87// works for cmaps up to 255 (not 256!) 114// works for cmaps up to 255 (not 256!)
88struct charmap 115struct charmap
89{ 116{
90 enum { INVALID = (u8)255 }; 117 enum { INVALID = (u8)255 };
… …
104 memset (enc, (char) 0, 256); 131 memset (enc, (char) 0, 256);
105 memset (dec, (char)INVALID, 256); 132 memset (dec, (char)INVALID, 256);
106 133
107 for (size = 0; cmap [size]; size++) 134 for (size = 0; cmap [size]; size++)
108 { 135 {
136 char c = cmap [size];
137
109 enc [size] = cmap [size]; 138 enc [size] = c;
110 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;
111 } 144 }
112 145
113 assert (size < 256); 146 assert (size < 256);
114} 147}
115 148
… …
122{ 155{
123 charmap cmap; 156 charmap cmap;
124 unsigned int enc_len [MAX_DEC_LEN]; 157 unsigned int enc_len [MAX_DEC_LEN];
125 unsigned int dec_len [MAX_ENC_LEN]; 158 unsigned int dec_len [MAX_ENC_LEN];
126 159
127 unsigned int encode_len (unsigned int len); 160 unsigned int encode_len (unsigned int len) const;
128 unsigned int decode_len (unsigned int len); 161 unsigned int decode_len (unsigned int len) const;
129 162
130 unsigned int encode (char *dst, u8 *src, unsigned int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
131 unsigned int decode (u8 *dst, char *src, unsigned int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
132 165
133 basecoder (const char *cmap); 166 basecoder (const char *cmap);
134}; 167};
135 168
136basecoder::basecoder (const char *cmap) 169basecoder::basecoder (const char *cmap)
… …
155 enc_len [len] = n; 188 enc_len [len] = n;
156 dec_len [n] = len; 189 dec_len [n] = len;
157 } 190 }
158} 191}
159 192
193unsigned int
160unsigned int basecoder::encode_len (unsigned int len) 194basecoder::encode_len (unsigned int len) const
161{ 195{
162 return enc_len [len]; 196 return enc_len [len];
163} 197}
164 198
199unsigned int
165unsigned int basecoder::decode_len (unsigned int len) 200basecoder::decode_len (unsigned int len) const
166{ 201{
167 while (len && !dec_len [len]) 202 while (len && !dec_len [len])
168 --len; 203 --len;
169 204
170 return dec_len [len]; 205 return dec_len [len];
171} 206}
172 207
208unsigned int
173unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 209basecoder::encode (char *dst, u8 *src, unsigned int len) const
174{ 210{
175 if (!len || len > MAX_DEC_LEN) 211 if (!len || len > MAX_DEC_LEN)
176 return 0; 212 return 0;
177 213
178 int elen = encode_len (len); 214 int elen = encode_len (len);
… …
197 *dst++ = cmap.encode [dst_ [i]]; 233 *dst++ = cmap.encode [dst_ [i]];
198 234
199 return elen; 235 return elen;
200} 236}
201 237
238unsigned int
202unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 239basecoder::decode (u8 *dst, char *src, unsigned int len) const
203{ 240{
204 if (!len || len > MAX_ENC_LEN) 241 if (!len || len > MAX_ENC_LEN)
205 return 0; 242 return 0;
206 243
207 u8 src_ [MAX_ENC_LEN]; 244 u8 src_ [MAX_ENC_LEN];
… …
256 } 293 }
257 abort (); 294 abort ();
258} 295}
259#endif 296#endif
260 297
261//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
262//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
263static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
264//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet 299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
265static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
266 301
267///////////////////////////////////////////////////////////////////////////// 302/////////////////////////////////////////////////////////////////////////////
268 303
269#define HDRSIZE 6 304#define HDRSIZE 5
270 305
306inline void
271inline void encode_header (char *data, int clientid, int seqno) 307encode_header (char *data, int clientid, int seqno, int retry = 0)
272{ 308{
273 u8 hdr[3] = { clientid, seqno >> 8, seqno };
274
275 assert (clientid < 256); 309 assert (clientid < 256);
276 310
311 seqno &= SEQNO_MASK;
312
313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
316 clientid,
317 };
318
277 cdc26.encode (data, hdr, 3); 319 cdc36.encode (data, hdr, 3);
278} 320}
279 321
322inline void
280inline void decode_header (char *data, int &clientid, int &seqno) 323decode_header (char *data, int &clientid, int &seqno)
281{ 324{
282 u8 hdr[3]; 325 u8 hdr[3];
283 326
284 cdc26.decode (hdr, data, HDRSIZE); 327 cdc36.decode (hdr, data, HDRSIZE);
285 328
286 clientid = hdr[0]; 329 clientid = hdr[2];
287 seqno = (hdr[1] << 8) | hdr[2]; 330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
288} 331}
289 332
290///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
291 334
292struct byte_stream 335struct byte_stream
… …
318byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
319{ 362{
320 delete data; 363 delete data;
321} 364}
322 365
366void
323void byte_stream::remove (int count) 367byte_stream::remove (int count)
324{ 368{
325 if (count > fill) 369 if (count > fill)
326 abort (); 370 assert (count <= fill);
327 371
328 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
329} 373}
330 374
375bool
331bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
332{ 377{
333 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
334 return false; 379 return false;
335 380
336 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
337 382
338 return true; 383 return true;
339} 384}
340 385
386bool
341bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
342{ 388{
343 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
344 return false; 390 return false;
345 391
346 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
… …
351 return true; 397 return true;
352} 398}
353 399
354vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
355{ 401{
402 if (fill < 2)
403 return 0;
404
405 unsigned int len;
406
407 for (;;)
408 {
356 int len = (data [0] << 8) | data [1]; 409 len = (data [0] << 8) | data [1];
357 410
358 if (len > MAXSIZE && fill >= 2) 411 if (len <= MAXSIZE)
359 abort (); // TODO handle this gracefully, connection reset 412 break;
360 413
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
361 if (fill < len + 2) 419 if (fill < len + 2)
362 return 0; 420 return 0;
363 421
364 vpn_packet *pkt = new vpn_packet; 422 vpn_packet *pkt = new vpn_packet;
365 423
… …
393 451
394struct dns_cfg 452struct dns_cfg
395{ 453{
396 static int next_uid; 454 static int next_uid;
397 455
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
398 u8 id1, id2, id3, id4; 464 u8 id1, id2, id3, id4;
399 u8 version; 465
400 u8 rrtype; 466 u16 client;
401 u8 flags;
402 u8 def_ttl; 467 u8 def_ttl;
403 u8 rcv_cdc; 468 u8 r0;
404 u8 snd_cdc;
405 u16 max_size;
406 u16 client;
407 u16 uid; // to make request unique
408 469
409 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;
410 476
411 void reset (int clientid); 477 void reset (int clientid);
412 bool valid (); 478 bool valid ();
479 u8 get_chksum ();
413}; 480};
414 481
415int dns_cfg::next_uid; 482int dns_cfg::next_uid;
416 483
484void
417void dns_cfg::reset (int clientid) 485dns_cfg::reset (int clientid)
418{ 486{
487 // this ID must result in some mixed-case characters in cdc26-encoding
419 id1 = 'G'; 488 id1 = 'G';
420 id2 = 'V'; 489 id2 = 'V';
421 id3 = 'P'; 490 id3 = 'P';
422 id4 = 'E'; 491 id4 = 'E';
423 492
424 version = 1; 493 version = 2;
425 494
426 rrtype = RR_TYPE_TXT; 495 rrtype = RR_TYPE_TXT;
427 flags = 0; 496 flags = 0;
428 def_ttl = 0; 497 def_ttl = 0;
429 rcv_cdc = 0;
430 snd_cdc = 62; 498 syn_cdc = 26;
499 hdr_cdc = 36;
500 req_cdc = conf.dns_case_preserving ? 62 : 36;
501 rep_cdc = 0;
431 max_size = ntohs (MAX_PKT_SIZE); 502 max_size = htons (MAX_PKT_SIZE);
432 client = ntohs (clientid); 503 client = htons (clientid);
433 uid = next_uid++; 504 uid = ++next_uid;
434 505
435 memset (reserved, 0, 8); 506 r0 = r1 = r2 = r3 = r4 = 0;
436}
437 507
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
438bool dns_cfg::valid () 529dns_cfg::valid ()
439{ 530{
531 // although the protocol itself allows for some configurability,
532 // only the following encoding/decoding settings are implemented.
440 return id1 == 'G' 533 return id1 == 'G'
441 && id2 == 'V' 534 && id2 == 'V'
442 && id3 == 'P' 535 && id3 == 'P'
443 && id4 == 'E' 536 && id4 == 'E'
444 && version == 1 537 && version == 2
445 && flags == 0
446 && rcv_cdc == 0
447 && snd_cdc == 62 538 && syn_cdc == 26
448 && 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 ();
449} 543}
450 544
451struct dns_packet : net_packet 545struct dns_packet : net_packet
452{ 546{
453 u16 id; 547 u16 id;
454 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
455 u16 qdcount, ancount, nscount, arcount; 549 u16 qdcount, ancount, nscount, arcount;
456 550
457 u8 data[MAXSIZE - 6 * 2]; 551 u8 data [MAXSIZE - 6 * 2];
458 552
459 int decode_label (char *data, int size, int &offs); 553 int decode_label (char *data, int size, int &offs);
460}; 554};
461 555
556int
462int dns_packet::decode_label (char *data, int size, int &offs) 557dns_packet::decode_label (char *data, int size, int &offs)
463{ 558{
464 char *orig = data; 559 char *orig = data;
465 560
466 memset (data, 0, size); 561 memset (data, 0, size);
467 562
… …
493 return data - orig; 588 return data - orig;
494} 589}
495 590
496///////////////////////////////////////////////////////////////////////////// 591/////////////////////////////////////////////////////////////////////////////
497 592
498struct dns_snd 593static
594u16 next_id ()
499{ 595{
500 dns_packet *pkt;
501 tstamp timeout, sent;
502 int retry;
503 struct dns_connection *dns;
504 int seqno;
505
506 dns_snd (dns_connection *dns);
507 void gen_stream_req (int seqno, byte_stream &stream);
508 void gen_syn_req (const dns_cfg &cfg);
509};
510
511static u16 dns_id = 12098; // TODO: should be per-vpn 596 static u16 dns_id = 0; // TODO: should be per-vpn
512 597
513static u16 next_id () 598#if 1
514{ 599 if (!dns_id)
600 dns_id = time (0);
601
515 // the simplest lsfr with periodicity 65535 i could find 602 // the simplest lsfr with periodicity 65535 i could find
516 dns_id = (dns_id << 1) 603 dns_id = (dns_id << 1)
517 | (((dns_id >> 1) 604 | (((dns_id >> 1)
518 ^ (dns_id >> 2) 605 ^ (dns_id >> 2)
519 ^ (dns_id >> 4) 606 ^ (dns_id >> 4)
520 ^ (dns_id >> 15)) & 1); 607 ^ (dns_id >> 15)) & 1);
521 608
522 return dns_id; 609 return dns_id;
610#else
611 dns_id++;//D
612
613 return htons (dns_id);
614#endif
523} 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};
524 665
525dns_snd::dns_snd (dns_connection *dns) 666dns_snd::dns_snd (dns_connection *dns)
526: dns (dns) 667: dns (dns)
527{ 668{
528 timeout = 0; 669 timeout = 0;
529 retry = 0; 670 retry = 0;
530 seqno = 0; 671 seqno = 0;
672 sent = ev_now ();
673 stdhdr = false;
531 674
532 pkt = new dns_packet; 675 pkt = new dns_packet;
533 676
534 pkt->id = next_id (); 677 pkt->id = next_id ();
535} 678}
536 679
680dns_snd::~dns_snd ()
681{
682 delete pkt;
683}
684
685static void
537static void append_domain (dns_packet &pkt, int &offs, const char *domain) 686append_domain (dns_packet &pkt, int &offs, const char *domain)
538{ 687{
539 // add tunnel domain 688 // add tunnel domain
540 for (;;) 689 for (;;)
541 { 690 {
542 const char *end = strchr (domain, '.'); 691 const char *end = strchr (domain, '.');
… …
555 704
556 domain = end + 1; 705 domain = end + 1;
557 } 706 }
558} 707}
559 708
709void
560void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 710dns_snd::gen_stream_req (int seqno, byte_stream &stream)
561{ 711{
712 stdhdr = true;
562 this->seqno = seqno; 713 this->seqno = seqno;
563 714
564 timeout = NOW + INITIAL_TIMEOUT; 715 timeout = ev_now () + INITIAL_TIMEOUT;
565 716
566 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 717 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
567 pkt->qdcount = htons (1); 718 pkt->qdcount = htons (1);
568 719
569 int offs = 6*2; 720 int offs = 6*2;
570 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 721 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
571 // 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,
572 // 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
573 724
574 char enc[256], *encp = enc; 725 char enc[256], *encp = enc;
575 encode_header (enc, THISNODE->id, seqno); 726 encode_header (enc, THISNODE->id, seqno);
576 727
577 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);
578 729
579 if (datalen > stream.size ()) 730 if (datalen > stream.size ())
580 datalen = stream.size (); 731 datalen = stream.size ();
581 732
582 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 733 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
583 stream.remove (datalen); 734 stream.remove (datalen);
584 735
585 while (enclen) 736 while (enclen)
586 { 737 {
587 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 738 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
593 encp += lbllen; 744 encp += lbllen;
594 745
595 enclen -= lbllen; 746 enclen -= lbllen;
596 } 747 }
597 748
598 append_domain (*pkt, offs, THISNODE->domain); 749 append_domain (*pkt, offs, dns->c->conf->domain);
599 750
600 (*pkt)[offs++] = 0; 751 (*pkt)[offs++] = 0;
601 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 752 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
602 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 753 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
603 754
604 pkt->len = offs; 755 pkt->len = offs;
605} 756}
606 757
607void dns_snd::gen_syn_req (const dns_cfg &cfg) 758void
759dns_snd::gen_syn_req ()
608{ 760{
609 timeout = NOW + INITIAL_SYN_TIMEOUT; 761 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
610 762
611 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 763 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
612 pkt->qdcount = htons (1); 764 pkt->qdcount = htons (1);
613 765
614 int offs = 6*2; 766 int offs = 6 * 2;
615 767
616 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));
617 769
618 assert (elen <= MAX_LBL_SIZE); 770 assert (elen <= MAX_LBL_SIZE);
619 771
620 (*pkt)[offs] = elen; 772 (*pkt)[offs] = elen;
621 offs += elen + 1; 773 offs += elen + 1;
622 append_domain (*pkt, offs, THISNODE->domain); 774 append_domain (*pkt, offs, dns->c->conf->domain);
623 775
624 (*pkt)[offs++] = 0; 776 (*pkt)[offs++] = 0;
625 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 777 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
626 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 778 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
627 779
… …
650 delete pkt; 802 delete pkt;
651} 803}
652 804
653///////////////////////////////////////////////////////////////////////////// 805/////////////////////////////////////////////////////////////////////////////
654 806
655struct dns_connection
656{
657 connection *c;
658 struct vpn *vpn;
659
660 dns_cfg cfg;
661
662 bool established;
663
664 tstamp last_received;
665 tstamp last_sent;
666 double poll_interval, send_interval;
667
668 vector<dns_rcv *> rcvpq;
669
670 byte_stream rcvdq; int rcvseq;
671 byte_stream snddq; int sndseq;
672
673 void time_cb (time_watcher &w); time_watcher tw;
674 void receive_rep (dns_rcv *r);
675
676 dns_connection (connection *c);
677 ~dns_connection ();
678};
679
680dns_connection::dns_connection (connection *c) 807dns_connection::dns_connection (connection *c)
681: c (c) 808: c (c)
682, rcvdq (MAX_BACKLOG * 2) 809, rcvdq (MAX_BACKLOG * 2)
683, snddq (MAX_BACKLOG * 2) 810, snddq (MAX_BACKLOG)
684, tw (this, &dns_connection::time_cb)
685{ 811{
812 tw.set<dns_connection, &dns_connection::time_cb> (this);
813
686 vpn = c->vpn; 814 vpn = c->vpn;
687 815
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
688 established = false; 840 established = false;
689 841
690 rcvseq = sndseq = 0; 842 rcvseq = repseq = sndseq = 0;
691 843
692 last_sent = last_received = 0; 844 last_sent = 0;
693 poll_interval = MIN_POLL_INTERVAL; 845 poll_interval = 0.5; // starting here
694 send_interval = 0.2; // starting rate 846 send_interval = 0.5; // starting rate
847 min_latency = INITIAL_TIMEOUT;
695} 848}
696 849
697dns_connection::~dns_connection () 850void
851dns_connection::set_cfg ()
698{ 852{
699 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 853 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
700 i != rcvpq.end ();
701 ++i)
702 delete *i;
703} 854}
704 855
856void
705void dns_connection::receive_rep (dns_rcv *r) 857dns_connection::receive_rep (dns_rcv *r)
706{ 858{
707 if (r->datalen) 859 if (r->datalen)
708 { 860 poll_interval = max (poll_interval * (1. / 1.2), MIN_POLL_INTERVAL);
709 last_received = NOW;
710 tw.trigger ();
711
712 poll_interval *= 0.99;
713 if (poll_interval > MIN_POLL_INTERVAL)
714 poll_interval = MIN_POLL_INTERVAL;
715 }
716 else 861 else
717 { 862 poll_interval = min (poll_interval * 1.1, MAX_POLL_INTERVAL);
718 poll_interval *= 1.1;
719 if (poll_interval > MAX_POLL_INTERVAL)
720 poll_interval = MAX_POLL_INTERVAL;
721 }
722 863
723 rcvpq.push_back (r); 864 rcvpq.push_back (r);
724 865
725 redo: 866 redo:
726 867
727 // find next packet 868 // find next packet
728 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 869 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
729 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 870 if (SEQNO_EQ (rcvseq, (*i)->seqno))
730 { 871 {
872 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
731 // enter the packet into our input stream 873 // enter the packet into our input stream
732 r = *i; 874 r = *i;
733 875
734 // remove the oldest packet, look forward, as it's oldest first 876 // remove the oldest packet, look forward, as it's oldest first
735 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)
736 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 878 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
737 { 879 {
880 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
738 delete *j; 881 delete *j;
739 rcvpq.erase (j); 882 rcvpq.erase (j);
740 break; 883 break;
741 } 884 }
742 885
743 rcvseq = (rcvseq + 1) & SEQNO_MASK; 886 rcvseq = (rcvseq + 1) & SEQNO_MASK;
744 887
745 if (!rcvdq.put (r->data, r->datalen)) 888 if (!rcvdq.put (r->data, r->datalen))
889 {
746 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 }
747 895
748 while (vpn_packet *pkt = rcvdq.get ()) 896 while (vpn_packet *pkt = rcvdq.get ())
749 { 897 {
750 sockinfo si; 898 sockinfo si;
751 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 899 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
752 900
753 vpn->recv_vpn_packet (pkt, si); 901 vpn->recv_vpn_packet (pkt, si);
902 delete pkt;
754 } 903 }
755 904
756 // check for further packets 905 // check for further packets
757 goto redo; 906 goto redo;
758 } 907 }
… …
768 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 917 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
769 918
770 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 919 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
771 && pkt.qdcount == htons (1)) 920 && pkt.qdcount == htons (1))
772 { 921 {
773 char qname[MAXSIZE]; 922 char qname [MAXSIZE];
774 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 923 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
775 924
776 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 925 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
777 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 926 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
778 927
779 pkt.qdcount = htons (1); 928 pkt.qdcount = htons (1);
780 pkt.ancount = 0; 929 pkt.ancount = 0;
781 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
782 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
783 932
784 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 933 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
785 934
786 int dlen = strlen (THISNODE->domain); 935 int dlen = strlen (THISNODE->domain);
787 936
788 if (qclass == RR_CLASS_IN 937 if (qclass == RR_CLASS_IN
789 && qlen > dlen + 1 938 && qlen > dlen + 1
790 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 939 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
791 { 940 {
792 // now generate reply 941 // now generate reply
793 pkt.ancount = htons (1); // one answer RR 942 pkt.ancount = htons (1); // one answer RR
794 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 943 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
795 944
… …
800 { 949 {
801 // correct class, domain: parse 950 // correct class, domain: parse
802 int client, seqno; 951 int client, seqno;
803 decode_header (qname, client, seqno); 952 decode_header (qname, client, seqno);
804 953
805 u8 data[MAXSIZE];
806 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
807
808 if (0 < client && client <= conns.size ()) 954 if (0 < client && client <= conns.size ())
809 { 955 {
810 connection *c = conns [client - 1]; 956 connection *c = conns [client - 1];
811 dns_connection *dns = c->dns; 957 dns_connection *dns = c->dns;
812 dns_rcv *rcv; 958 dns_rcv *rcv;
813 959
814 if (dns) 960 if (dns)
815 { 961 {
962 u8 data[MAXSIZE];
963 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
964
816 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 (); )
817 if (SEQNO_EQ ((*i)->seqno, seqno)) 966 if (SEQNO_EQ ((*i)->seqno, seqno))
818 { 967 {
819 // already seen that request: simply reply with the cached reply 968 // already seen that request: simply reply with the cached reply
820 dns_rcv *r = *i; 969 dns_rcv *r = *i;
821 970
822 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 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;
823 976
824 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);
825 pkt.id = r->pkt->id; 978
826 goto duplicate_request; 979 goto duplicate_request;
827 } 980 }
828 981
829 // new packet, queue 982 // new packet, queue
830 rcv = new dns_rcv (seqno, data, datalen); 983 rcv = new dns_rcv (seqno, data, datalen);
831 dns->receive_rep (rcv); 984 dns->receive_rep (rcv);
832 } 985 }
833 986
987 {
834 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
835 989
836 // type
837 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 990 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
838 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; 991 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
839
840 // class
841 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; 992 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
842
843 // TTL
844 pkt [offs++] = 0; pkt [offs++] = 0; 993 pkt [offs++] = 0; pkt [offs++] = 0;
845 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; 994 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
846 995
847 int rdlen_offs = offs += 2; 996 int rdlen_offs = offs += 2;
848 997
998 if (dns)
999 {
849 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 1000 int dlen = ntohs (dns->cfg.max_size) - offs;
1001
850 // 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
851 dlen -= qlen; 1003 dlen -= qlen;
852 1004
853 if (dns) 1005 // only put data into in-order sequence packets, if
854 { 1006 // we receive out-of-order packets we generate empty
855 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)
856 { 1010 {
1011 dns->repseq = seqno;
1012
1013 while (dlen > 1 && !dns->snddq.empty ())
1014 {
857 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1015 int txtlen = dlen <= 255 ? dlen - 1 : 255;
858 1016
859 if (txtlen > dns->snddq.size ()) 1017 if (txtlen > dns->snddq.size ())
860 txtlen = dns->snddq.size (); 1018 txtlen = dns->snddq.size ();
861 1019
862 pkt[offs++] = txtlen; 1020 pkt[offs++] = txtlen;
863 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 1021 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
864 offs += txtlen; 1022 offs += txtlen;
865 dns->snddq.remove (txtlen); 1023 dns->snddq.remove (txtlen);
866 1024
867 dlen -= txtlen + 1; 1025 dlen -= txtlen + 1;
1026 }
868 } 1027 }
869 1028
870 // avoid empty TXT rdata 1029 // avoid completely empty TXT rdata
871 if (offs == rdlen_offs) 1030 if (offs == rdlen_offs)
872 pkt[offs++] = 0; 1031 pkt[offs++] = 0;
1032
1033 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
873 } 1034 }
874 else 1035 else
875 { 1036 {
876 // send RST 1037 // send RST
877 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;
878 pkt [offs++] = CMD_IP_RST; 1039 pkt [offs++] = CMD_IP_RST;
879 } 1040 }
880 1041
881 int rdlen = offs - rdlen_offs; 1042 int rdlen = offs - rdlen_offs;
882 1043
883 pkt [rdlen_offs - 2] = rdlen >> 8; 1044 pkt [rdlen_offs - 2] = rdlen >> 8;
884 pkt [rdlen_offs - 1] = rdlen; 1045 pkt [rdlen_offs - 1] = rdlen;
885 1046
886 if (dns) 1047 if (dns)
887 { 1048 {
888 // now update dns_rcv copy 1049 // now update dns_rcv copy
889 rcv->pkt->len = offs; 1050 rcv->pkt->len = offs;
890 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 1051 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
891 } 1052 }
1053 }
892 1054
893 duplicate_request: ; 1055 duplicate_request: ;
894 } 1056 }
895 else 1057 else
896 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 1058 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
… …
908 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
909 pkt [offs++] = 0; pkt [offs++] = 0; 1071 pkt [offs++] = 0; pkt [offs++] = 0;
910 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 1072 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
911 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 1073 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
912 1074
913 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client);
914
915 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;
916 pkt [offs++] = CMD_IP_REJ; 1076 pkt [offs++] = CMD_IP_REJ;
917 1077
918 if (0 < client && client <= conns.size ()) 1078 if (0 < client && client <= conns.size ())
919 { 1079 {
920 connection *c = conns [client - 1]; 1080 connection *c = conns [client - 1];
921 1081
922 if (cfg.valid ()) 1082 if (cfg.valid ())
923 { 1083 {
924 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));
925 1089
926 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
927 c->dns = new dns_connection (c); 1095 c->dns = new dns_connection (c);
928 c->dns->cfg = cfg; 1096 c->dns->cfg = cfg;
1097 c->dns->set_cfg ();
929 } 1098 }
930 } 1099 }
931 } 1100 }
932 } 1101 }
933 1102
… …
949 i != dns_sndpq.end (); 1118 i != dns_sndpq.end ();
950 ++i) 1119 ++i)
951 if ((*i)->pkt->id == pkt.id) 1120 if ((*i)->pkt->id == pkt.id)
952 { 1121 {
953 dns_connection *dns = (*i)->dns; 1122 dns_connection *dns = (*i)->dns;
1123 connection *c = dns->c;
954 int seqno = (*i)->seqno; 1124 int seqno = (*i)->seqno;
955 u8 data[MAXSIZE], *datap = data; 1125 u8 data[MAXSIZE], *datap = data;
1126 //printf ("rcv pkt %x\n", seqno);//D
956 1127
957 if ((*i)->retry) 1128 if ((*i)->retry)
958 { 1129 {
959 dns->send_interval *= 1.01; 1130 dns->send_interval *= 1.01;
960 if (dns->send_interval < MAX_SEND_INTERVAL) 1131 if (dns->send_interval > MAX_SEND_INTERVAL)
961 dns->send_interval = MAX_SEND_INTERVAL; 1132 dns->send_interval = MAX_SEND_INTERVAL;
962 } 1133 }
963 else 1134 else
964 { 1135 {
1136#if 0
965 dns->send_interval *= 0.99; 1137 dns->send_interval *= 0.999;
966 if (dns->send_interval < MIN_SEND_INTERVAL) 1138#endif
967 dns->send_interval = MIN_SEND_INTERVAL;
968
969 // the latency surely puts an upper bound on 1139 // the latency surely puts an upper bound on
970 // the minimum send interval 1140 // the minimum send interval
971 if (dns->send_interval > NOW - (*i)->sent) 1141 double latency = ev_now () - (*i)->sent;
972 dns->send_interval = NOW - (*i)->sent; 1142
1143 if (latency < dns->min_latency)
1144 dns->min_latency = latency;
1145
1146 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1147 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1148
1149 if (dns->send_interval < conf.dns_send_interval)
1150 dns->send_interval = conf.dns_send_interval;
973 } 1151 }
974 1152
975 delete *i; 1153 delete *i;
976 dns_sndpq.erase (i); 1154 dns_sndpq.erase (i);
977 1155
… …
995 ttl |= pkt [offs++] << 16; 1173 ttl |= pkt [offs++] << 16;
996 ttl |= pkt [offs++] << 8; 1174 ttl |= pkt [offs++] << 8;
997 ttl |= pkt [offs++]; 1175 ttl |= pkt [offs++];
998 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; 1176 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
999 1177
1000 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) 1178 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
1001 { 1179 {
1002 if (rdlen <= MAXSIZE - offs) 1180 if (rdlen <= MAXSIZE - offs)
1003 { 1181 {
1004 // decode bytes, finally 1182 // decode bytes, finally
1005 1183
… …
1027 1205
1028 if (ip [0] == CMD_IP_1 1206 if (ip [0] == CMD_IP_1
1029 && ip [1] == CMD_IP_2 1207 && ip [1] == CMD_IP_2
1030 && ip [2] == CMD_IP_3) 1208 && ip [2] == CMD_IP_3)
1031 { 1209 {
1032 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1210 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1033 1211
1034 if (ip [3] == CMD_IP_RST) 1212 if (ip [3] == CMD_IP_RST)
1035 { 1213 {
1036 slog (L_DEBUG, _("got tunnel RST request")); 1214 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1037 1215
1038 connection *c = dns->c; 1216 dns->reset ();
1039 delete c->dns; c->dns = 0;
1040
1041 return; 1217 return;
1042 } 1218 }
1043 else if (ip [3] == CMD_IP_SYN) 1219 else if (ip [3] == CMD_IP_SYN)
1220 {
1221 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1044 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 }
1238 }
1239 else if (ip [3] == CMD_IP_REJ)
1240 {
1241 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1242 dns->tw.start (60.);
1243 }
1045 else 1244 else
1245 {
1046 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 }
1047 } 1249 }
1048 else 1250 else
1049 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1251 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1050 ip [0], ip [1], ip [2], ip [3]); 1252 ip [0], ip [1], ip [2], ip [3]);
1051 1253
1052 return; 1254 return;
1053 } 1255 }
1054 1256
1055 int client, rseqno; 1257 int client, rseqno;
1056 decode_header (qname, client, rseqno); 1258 decode_header (qname, client, rseqno);
1057 1259
1058 if (client != THISNODE->id) 1260 if (client != THISNODE->id)
1059 { 1261 {
1060 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1262 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1061 datap = 0; 1263 datap = 0;
1062 } 1264 }
1063 else if (rseqno != seqno) 1265 else if (rseqno != seqno)
1064 { 1266 {
1065 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?"));
1066 datap = 0; 1268 datap = 0;
1067 } 1269 }
1068 } 1270 }
1069 } 1271 }
1070 1272
… …
1075 break; 1277 break;
1076 } 1278 }
1077} 1279}
1078 1280
1079void 1281void
1080vpn::dnsv4_ev (io_watcher &w, short revents) 1282vpn::dnsv4_ev (ev::io &w, int revents)
1081{ 1283{
1082 if (revents & EVENT_READ) 1284 if (revents & EV_READ)
1083 { 1285 {
1084 dns_packet *pkt = new dns_packet; 1286 dns_packet *pkt = new dns_packet;
1085 struct sockaddr_in sa; 1287 struct sockaddr_in sa;
1086 socklen_t sa_len = sizeof (sa); 1288 socklen_t sa_len = sizeof (sa);
1087 1289
1088 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);
1089 1291
1090 if (pkt->len > 0) 1292 if (pkt->len > 0)
1091 { 1293 {
1092 if (THISNODE->dns_port) 1294 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1295 dnsv4_client (*pkt);
1296 else
1093 { 1297 {
1094 dnsv4_server (*pkt); 1298 dnsv4_server (*pkt);
1095 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);
1096 } 1300 }
1097 else
1098 dnsv4_client (*pkt);
1099 1301
1100 delete pkt; 1302 delete pkt;
1101 } 1303 }
1102 } 1304 }
1103} 1305}
1104 1306
1105bool 1307bool
1106connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1308vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1107{ 1309{
1310 int client = ntohl (si.host);
1311
1312 assert (0 < client && client <= conns.size ());
1313
1314 connection *c = conns [client - 1];
1315
1108 if (!dns) 1316 if (!c->dns)
1109 dns = new dns_connection (this); 1317 c->dns = new dns_connection (c);
1110 1318
1111 if (!dns->snddq.put (pkt)) 1319 if (c->dns->snddq.put (pkt))
1112 return false; 1320 {
1321 min_it (c->dns->poll_interval, 0.25);
1322 c->dns->tw ();
1323 }
1113 1324
1114 dns->tw.trigger (); 1325 // always return true even if the buffer overflows
1115
1116 return true; 1326 return true;
1117} 1327}
1118 1328
1119#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1120
1121void 1329void
1122dns_connection::time_cb (time_watcher &w) 1330dns_connection::time_cb (ev::timer &w, int revents)
1123{ 1331{
1124 // servers have to be polled 1332 // servers have to be polled
1125 if (THISNODE->dns_port) 1333 if (THISNODE->dns_port)
1126 return; 1334 return;
1127 1335
1128 // check for timeouts and (re)transmit 1336 // check for timeouts and (re)transmit
1129 tstamp next = NOW + poll_interval; 1337 tstamp next = 86400 * 365;
1130 dns_snd *send = 0; 1338 dns_snd *send = 0;
1131 1339
1132 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); 1340 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
1133 i != vpn->dns_sndpq.end (); 1341 i != vpn->dns_sndpq.end ();
1134 ++i) 1342 ++i)
1135 { 1343 {
1136 dns_snd *r = *i; 1344 dns_snd *r = *i;
1137 1345
1138 if (r->timeout <= NOW) 1346 if (r->timeout <= ev_now ())
1139 { 1347 {
1140 if (!send) 1348 if (!send)
1141 { 1349 {
1142 send = r; 1350 send = r;
1143 1351
1144 r->retry++; 1352 r->retry++;
1145 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);
1146 } 1360 }
1147 } 1361 }
1148 else if (r->timeout < next) 1362 else
1149 NEXT (r->timeout); 1363 min_it (next, r->timeout - ev_now ());
1150 }
1151
1152 if (last_sent + send_interval <= NOW)
1153 { 1364 }
1365
1154 if (!send) 1366 if (!send)
1367 {
1368 // generate a new packet, if wise
1369
1370 if (!established)
1155 { 1371 {
1156 // generate a new packet, if wise
1157
1158 if (!established)
1159 {
1160 if (vpn->dns_sndpq.empty ()) 1372 if (vpn->dns_sndpq.empty ())
1161 {
1162 send = new dns_snd (this);
1163
1164 cfg.reset (THISNODE->id);
1165 send->gen_syn_req (cfg);
1166 }
1167 }
1168 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING)
1169 { 1373 {
1170 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);
1171 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
1172 1394
1173 sndseq = (sndseq + 1) & SEQNO_MASK; 1395 sndseq = (sndseq + 1) & SEQNO_MASK;
1174 } 1396 }
1175 1397 else
1176 if (send) 1398 min_it (next, last_sent + send_interval - ev_now ());
1177 vpn->dns_sndpq.push_back (send);
1178 } 1399 }
1179 1400
1180 if (send) 1401 if (send)
1181 { 1402 vpn->dns_sndpq.push_back (send);
1182 printf ("send pkt\n"); 1403 }
1183 last_sent = NOW;
1184 1404
1185 if (!send->retry) 1405 if (send)
1186 send->sent = NOW; 1406 {
1187 1407 last_sent = ev_now ();
1188 sendto (vpn->dnsv4_fd, 1408 sendto (vpn->dnsv4_fd,
1189 send->pkt->at (0), send->pkt->len, 0, 1409 send->pkt->at (0), send->pkt->len, 0,
1190 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1410 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1191 }
1192 } 1411 }
1193 else
1194 NEXT (last_sent + send_interval);
1195 1412
1196 printf ("pi %f si %f N %f (%d:%d)\n", poll_interval, send_interval, next - NOW, vpn->dns_sndpq.size (), snddq.size ()); 1413 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1414
1415 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1416 poll_interval, send_interval, next - ev_now (),
1417 vpn->dns_sndpq.size (), snddq.size (),
1418 rcvpq.size ());
1197 1419
1198 w.start (next); 1420 w.start (next);
1199} 1421}
1200 1422
1201#endif 1423#endif

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