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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 1.51 by root, Sun Mar 6 19:40:28 2011 UTC

1/* 1/*
2 vpn_dns.C -- handle the dns tunnel part of the protocol. 2 vpn_dns.C -- handle the dns tunnel part of the protocol.
3 Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> 3 Copyright (C) 2003-2011 Marc Lehmann <gvpe@schmorp.de>
4 4
5 This file is part of GVPE. 5 This file is part of GVPE.
6 6
7 GVPE is free software; you can redistribute it and/or modify 7 GVPE is free software; you can redistribute it and/or modify it
8 it under the terms of the GNU General Public License as published by 8 under the terms of the GNU General Public License as published by the
9 the Free Software Foundation; either version 2 of the License, or 9 Free Software Foundation; either version 3 of the License, or (at your
10 (at your option) any later version. 10 option) any later version.
11 11
12 This program is distributed in the hope that it will be useful, 12 This program is distributed in the hope that it will be useful, but
13 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
15 GNU General Public License for more details. 15 Public License for more details.
16 16
17 You should have received a copy of the GNU General Public License 17 You should have received a copy of the GNU General Public License along
18 along with gvpe; if not, write to the Free Software 18 with this program; if not, see <http://www.gnu.org/licenses/>.
19 Foundation, Inc. 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 0.1 // 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 2. // 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 240 // 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 unsigned int len;
403
404 for (;;)
405 {
355 unsigned int len = (data [0] << 8) | data [1]; 406 len = (data [0] << 8) | data [1];
356 407
357 if (len > MAXSIZE && fill >= 2) 408 if (len <= MAXSIZE || fill < 2)
358 abort (); // TODO handle this gracefully, connection reset 409 break;
359 410
411 // TODO: handle this better than skipping, e.g. by reset
412 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
413 remove (1);
414 }
415
360 if (fill < len + 2) 416 if (fill < len + 2)
361 return 0; 417 return 0;
362 418
363 vpn_packet *pkt = new vpn_packet; 419 vpn_packet *pkt = new vpn_packet;
364 420
… …
392 448
393struct dns_cfg 449struct dns_cfg
394{ 450{
395 static int next_uid; 451 static int next_uid;
396 452
453 u8 chksum;
454 u8 rrtype;
455 u16 uid; // to make request unique
456
457 u8 version;
458 u8 flags;
459 u16 max_size;
460
397 u8 id1, id2, id3, id4; 461 u8 id1, id2, id3, id4;
398 u8 version; 462
399 u8 rrtype; 463 u16 client;
400 u8 flags;
401 u8 def_ttl; 464 u8 def_ttl;
402 u8 rcv_cdc; 465 u8 r0;
403 u8 snd_cdc;
404 u16 max_size;
405 u16 client;
406 u16 uid; // to make request unique
407 466
408 u8 reserved[8]; 467 u8 syn_cdc; // cdc en/decoder for syn (A?) requests
468 u8 hdr_cdc; // cdc en/decoder for regular request headers
469 u8 req_cdc; // cdc en/decoder for regular (ANY?) request data
470 u8 rep_cdc; // cdc en/decoder for regular (TXT) replies, 0 == 8 bit encoding
471
472 u8 r1, r2, r3, r4;
409 473
410 void reset (int clientid); 474 void reset (int clientid);
411 bool valid (); 475 bool valid ();
476 u8 get_chksum ();
412}; 477};
413 478
414int dns_cfg::next_uid; 479int dns_cfg::next_uid;
415 480
481void
416void dns_cfg::reset (int clientid) 482dns_cfg::reset (int clientid)
417{ 483{
484 // this ID must result in some mixed-case characters in cdc26-encoding
418 id1 = 'G'; 485 id1 = 'G';
419 id2 = 'V'; 486 id2 = 'V';
420 id3 = 'P'; 487 id3 = 'P';
421 id4 = 'E'; 488 id4 = 'E';
422 489
423 version = 1; 490 version = 2;
424 491
425 rrtype = RR_TYPE_TXT; 492 rrtype = RR_TYPE_TXT;
426 flags = 0; 493 flags = 0;
427 def_ttl = 0; 494 def_ttl = 0;
428 rcv_cdc = 0;
429 snd_cdc = 62; 495 syn_cdc = 26;
496 hdr_cdc = 36;
497 req_cdc = conf.dns_case_preserving ? 62 : 36;
498 rep_cdc = 0;
430 max_size = ntohs (MAX_PKT_SIZE); 499 max_size = htons (MAX_PKT_SIZE);
431 client = ntohs (clientid); 500 client = htons (clientid);
432 uid = next_uid++; 501 uid = ++next_uid;
433 502
434 memset (reserved, 0, 8); 503 r0 = r1 = r2 = r3 = r4 = 0;
435}
436 504
505 chksum = get_chksum ();
506}
507
508// simple but not trivial chksum
509u8
510dns_cfg::get_chksum ()
511{
512 unsigned int sum = 0xff00; // only 16 bits required
513
514 u8 old_chksum = chksum;
515 chksum = 0;
516
517 for (unsigned int i = 0; i < sizeof (*this); ++i)
518 sum += ((u8 *)this)[i] * (i + 1);
519
520 chksum = old_chksum;
521
522 return sum + (sum >> 8);
523}
524
525bool
437bool dns_cfg::valid () 526dns_cfg::valid ()
438{ 527{
528 // although the protocol itself allows for some configurability,
529 // only the following encoding/decoding settings are implemented.
439 return id1 == 'G' 530 return id1 == 'G'
440 && id2 == 'V' 531 && id2 == 'V'
441 && id3 == 'P' 532 && id3 == 'P'
442 && id4 == 'E' 533 && id4 == 'E'
443 && version == 1 534 && version == 2
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62 535 && syn_cdc == 26
447 && max_size == ntohs (MAX_PKT_SIZE); 536 && hdr_cdc == 36
537 && (req_cdc == 36 || req_cdc == 62)
538 && rep_cdc == 0
539 && chksum == get_chksum ();
448} 540}
449 541
450struct dns_packet : net_packet 542struct dns_packet : net_packet
451{ 543{
452 u16 id; 544 u16 id;
453 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 545 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
454 u16 qdcount, ancount, nscount, arcount; 546 u16 qdcount, ancount, nscount, arcount;
455 547
456 u8 data[MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
457 549
458 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
459}; 551};
460 552
553int
461int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
462{ 555{
463 char *orig = data; 556 char *orig = data;
464 557
465 memset (data, 0, size); 558 memset (data, 0, size);
466 559
… …
492 return data - orig; 585 return data - orig;
493} 586}
494 587
495///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
496 589
497struct dns_snd 590static
591u16 next_id ()
498{ 592{
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 593 static u16 dns_id = 0; // TODO: should be per-vpn
513 594
514static u16 next_id () 595 if (!dns_id)
515{ 596 dns_id = time (0);
597
516 // the simplest lsfr with periodicity 65535 i could find 598 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 599 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 600 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 601 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 602 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 603 ^ (dns_id >> 15)) & 1);
522 604
523 return dns_id; 605 return dns_id;
524} 606}
525 607
608struct dns_rcv;
609struct dns_snd;
610
611struct dns_connection
612{
613 connection *c;
614 struct vpn *vpn;
615
616 dns_cfg cfg;
617
618 bool established;
619 const basecoder *cdc;
620
621 tstamp last_received;
622 tstamp last_sent;
623 double min_latency;
624 double poll_interval, send_interval;
625
626 vector<dns_rcv *> rcvpq;
627
628 byte_stream rcvdq; int rcvseq; int repseq;
629 byte_stream snddq; int sndseq;
630
631 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
632 void receive_rep (dns_rcv *r);
633
634 void reset (); // quite like tcp RST
635 void set_cfg (); // to be called after any cfg changes
636
637 dns_connection (connection *c);
638 ~dns_connection ();
639};
640
641struct dns_snd
642{
643 dns_packet *pkt;
644 tstamp timeout, sent;
645 int retry;
646 struct dns_connection *dns;
647 int seqno;
648 bool stdhdr;
649
650 void gen_stream_req (int seqno, byte_stream &stream);
651 void gen_syn_req ();
652
653 dns_snd (dns_connection *dns);
654 ~dns_snd ();
655};
656
526dns_snd::dns_snd (dns_connection *dns) 657dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 658: dns (dns)
528{ 659{
529 timeout = 0; 660 timeout = 0;
530 retry = 0; 661 retry = 0;
531 seqno = 0; 662 seqno = 0;
532 sent = NOW; 663 sent = ev_now ();
664 stdhdr = false;
533 665
534 pkt = new dns_packet; 666 pkt = new dns_packet;
535 667
536 pkt->id = next_id (); 668 pkt->id = next_id ();
537} 669}
… …
539dns_snd::~dns_snd () 671dns_snd::~dns_snd ()
540{ 672{
541 delete pkt; 673 delete pkt;
542} 674}
543 675
676static void
544static void append_domain (dns_packet &pkt, int &offs, const char *domain) 677append_domain (dns_packet &pkt, int &offs, const char *domain)
545{ 678{
546 // add tunnel domain 679 // add tunnel domain
547 for (;;) 680 for (;;)
548 { 681 {
549 const char *end = strchr (domain, '.'); 682 const char *end = strchr (domain, '.');
… …
562 695
563 domain = end + 1; 696 domain = end + 1;
564 } 697 }
565} 698}
566 699
700void
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 701dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 702{
703 stdhdr = true;
569 this->seqno = seqno; 704 this->seqno = seqno;
570 705
571 timeout = NOW + INITIAL_TIMEOUT; 706 timeout = ev_now () + INITIAL_TIMEOUT;
572 707
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 708 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 709 pkt->qdcount = htons (1);
575 710
576 int offs = 6*2; 711 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 712 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, 713 // 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 714 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
580 715
581 char enc[256], *encp = enc; 716 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 717 encode_header (enc, THISNODE->id, seqno);
583 718
584 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); 719 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
585 720
586 if (datalen > stream.size ()) 721 if (datalen > stream.size ())
587 datalen = stream.size (); 722 datalen = stream.size ();
588 723
589 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 724 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
590 stream.remove (datalen); 725 stream.remove (datalen);
591 726
592 while (enclen) 727 while (enclen)
593 { 728 {
594 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 729 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
600 encp += lbllen; 735 encp += lbllen;
601 736
602 enclen -= lbllen; 737 enclen -= lbllen;
603 } 738 }
604 739
605 append_domain (*pkt, offs, THISNODE->domain); 740 append_domain (*pkt, offs, dns->c->conf->domain);
606 741
607 (*pkt)[offs++] = 0; 742 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 743 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 744 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 745
611 pkt->len = offs; 746 pkt->len = offs;
612} 747}
613 748
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 749void
750dns_snd::gen_syn_req ()
615{ 751{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 752 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
617 753
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 754 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 755 pkt->qdcount = htons (1);
620 756
621 int offs = 6*2; 757 int offs = 6 * 2;
622 758
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 759 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 760
625 assert (elen <= MAX_LBL_SIZE); 761 assert (elen <= MAX_LBL_SIZE);
626 762
627 (*pkt)[offs] = elen; 763 (*pkt)[offs] = elen;
628 offs += elen + 1; 764 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 765 append_domain (*pkt, offs, dns->c->conf->domain);
630 766
631 (*pkt)[offs++] = 0; 767 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 768 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 769 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 770
… …
657 delete pkt; 793 delete pkt;
658} 794}
659 795
660///////////////////////////////////////////////////////////////////////////// 796/////////////////////////////////////////////////////////////////////////////
661 797
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) 798dns_connection::dns_connection (connection *c)
688: c (c) 799: c (c)
689, rcvdq (MAX_BACKLOG * 2) 800, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 801, snddq (MAX_BACKLOG)
691, tw (this, &dns_connection::time_cb)
692{ 802{
803 tw.set<dns_connection, &dns_connection::time_cb> (this);
804
693 vpn = c->vpn; 805 vpn = c->vpn;
694 806
807 reset ();
808}
809
810dns_connection::~dns_connection ()
811{
812 reset ();
813}
814
815void
816dns_connection::reset ()
817{
818 while (!rcvpq.empty ())
819 {
820 delete rcvpq.back ();
821 rcvpq.pop_back ();
822 }
823
824 for (int i = vpn->dns_sndpq.size (); i--; )
825 if (vpn->dns_sndpq [i]->dns == this)
826 {
827 vpn->dns_sndpq [i] = vpn->dns_sndpq.back ();
828 vpn->dns_sndpq.pop_back ();
829 }
830
695 established = false; 831 established = false;
696 832
697 rcvseq = sndseq = 0; 833 rcvseq = repseq = sndseq = 0;
698 834
699 last_sent = last_received = 0; 835 last_sent = last_received = 0;
700 poll_interval = MIN_POLL_INTERVAL; 836 poll_interval = 0.5; // starting here
701 send_interval = 0.2; // starting rate 837 send_interval = 0.5; // starting rate
838 min_latency = INITIAL_TIMEOUT;
702} 839}
703 840
704dns_connection::~dns_connection () 841void
842dns_connection::set_cfg ()
705{ 843{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 844 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
707 i != rcvpq.end ();
708 ++i)
709 delete *i;
710} 845}
711 846
847void
712void dns_connection::receive_rep (dns_rcv *r) 848dns_connection::receive_rep (dns_rcv *r)
713{ 849{
714 if (r->datalen) 850 if (r->datalen)
715 { 851 {
716 last_received = NOW; 852 last_received = ev_now ();
717 tw.trigger (); 853 tw ();
718 854
719 poll_interval = send_interval; 855 poll_interval = send_interval;
720 } 856 }
721 else 857 else
722 { 858 {
723 poll_interval *= 1.1; 859 poll_interval *= 1.5;
860
724 if (poll_interval > MAX_POLL_INTERVAL) 861 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL; 862 poll_interval = MAX_POLL_INTERVAL;
726 } 863 }
727 864
728 rcvpq.push_back (r); 865 rcvpq.push_back (r);
… …
731 868
732 // find next packet 869 // find next packet
733 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 870 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
734 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 871 if (SEQNO_EQ (rcvseq, (*i)->seqno))
735 { 872 {
873 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
736 // enter the packet into our input stream 874 // enter the packet into our input stream
737 r = *i; 875 r = *i;
738 876
739 // remove the oldest packet, look forward, as it's oldest first 877 // remove the oldest packet, look forward, as it's oldest first
740 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) 878 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
741 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 879 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
742 { 880 {
881 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
743 delete *j; 882 delete *j;
744 rcvpq.erase (j); 883 rcvpq.erase (j);
745 break; 884 break;
746 } 885 }
747 886
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 887 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 888
750 if (!rcvdq.put (r->data, r->datalen)) 889 if (!rcvdq.put (r->data, r->datalen))
890 {
751 abort (); // MUST never overflow, can be caused by data corruption, TODO 891 // MUST never overflow, can be caused by data corruption, TODO
892 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
893 reset ();
894 return;
895 }
752 896
753 while (vpn_packet *pkt = rcvdq.get ()) 897 while (vpn_packet *pkt = rcvdq.get ())
754 { 898 {
755 sockinfo si; 899 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 900 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
757 901
758 vpn->recv_vpn_packet (pkt, si); 902 vpn->recv_vpn_packet (pkt, si);
759
760 delete pkt; 903 delete pkt;
761 } 904 }
762 905
763 // check for further packets 906 // check for further packets
764 goto redo; 907 goto redo;
… …
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 918 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 919
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 920 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 921 && pkt.qdcount == htons (1))
779 { 922 {
780 char qname[MAXSIZE]; 923 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 924 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 925
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 926 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 927 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 928
786 pkt.qdcount = htons (1); 929 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 930 pkt.ancount = 0;
788 pkt.nscount = 0; // should be self, as other nameservers reply like this 931 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 932 pkt.arcount = 0; // a record for self, as other nameservers reply like this
790 933
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 934 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 935
793 int dlen = strlen (THISNODE->domain); 936 int dlen = strlen (THISNODE->domain);
794 937
795 if (qclass == RR_CLASS_IN 938 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 939 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 940 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 941 {
799 // now generate reply 942 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 943 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 944 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 945
… …
807 { 950 {
808 // correct class, domain: parse 951 // correct class, domain: parse
809 int client, seqno; 952 int client, seqno;
810 decode_header (qname, client, seqno); 953 decode_header (qname, client, seqno);
811 954
812 u8 data[MAXSIZE];
813 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
814
815 if (0 < client && client <= conns.size ()) 955 if (0 < client && client <= conns.size ())
816 { 956 {
817 connection *c = conns [client - 1]; 957 connection *c = conns [client - 1];
818 dns_connection *dns = c->dns; 958 dns_connection *dns = c->dns;
819 dns_rcv *rcv; 959 dns_rcv *rcv;
820 960
821 if (dns) 961 if (dns)
822 { 962 {
963 u8 data[MAXSIZE];
964 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
965
823 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 966 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 967 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 968 {
826 // already seen that request: simply reply with the cached reply 969 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 970 dns_rcv *r = *i;
828 971
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 972 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
973
974 // refresh header & id, as the retry count could have changed
975 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
976 r->pkt->id = pkt.id;
830 977
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 978 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 979
833 goto duplicate_request; 980 goto duplicate_request;
834 } 981 }
835 982
836 // new packet, queue 983 // new packet, queue
837 rcv = new dns_rcv (seqno, data, datalen); 984 rcv = new dns_rcv (seqno, data, datalen);
838 dns->receive_rep (rcv); 985 dns->receive_rep (rcv);
839 } 986 }
840 987
988 {
841 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 989 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
842 990
843 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 991 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
844 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type 992 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
845 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 993 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
846 pkt [offs++] = 0; pkt [offs++] = 0; 994 pkt [offs++] = 0; pkt [offs++] = 0;
847 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 995 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
848 996
849 int rdlen_offs = offs += 2; 997 int rdlen_offs = offs += 2;
850 998
999 if (dns)
1000 {
851 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 1001 int dlen = ntohs (dns->cfg.max_size) - offs;
1002
852 // bind doesn't compress well, so reduce further by one label length 1003 // bind doesn't compress well, so reduce further by one label length
853 dlen -= qlen; 1004 dlen -= qlen;
854 1005
855 if (dns) 1006 // only put data into in-order sequence packets, if
856 { 1007 // we receive out-of-order packets we generate empty
857 while (dlen > 1 && !dns->snddq.empty ()) 1008 // replies
1009 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
1010 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
858 { 1011 {
1012 dns->repseq = seqno;
1013
1014 while (dlen > 1 && !dns->snddq.empty ())
1015 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1016 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 1017
861 if (txtlen > dns->snddq.size ()) 1018 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 1019 txtlen = dns->snddq.size ();
863 1020
864 pkt[offs++] = txtlen; 1021 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 1022 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 1023 offs += txtlen;
867 dns->snddq.remove (txtlen); 1024 dns->snddq.remove (txtlen);
868 1025
869 dlen -= txtlen + 1; 1026 dlen -= txtlen + 1;
1027 }
870 } 1028 }
871 1029
872 // avoid empty TXT rdata 1030 // avoid completely empty TXT rdata
873 if (offs == rdlen_offs) 1031 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 1032 pkt[offs++] = 0;
875 1033
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 1034 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 1035 }
878 else 1036 else
879 { 1037 {
880 // send RST 1038 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 1039 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 1040 pkt [offs++] = CMD_IP_RST;
883 } 1041 }
884 1042
885 int rdlen = offs - rdlen_offs; 1043 int rdlen = offs - rdlen_offs;
886 1044
887 pkt [rdlen_offs - 2] = rdlen >> 8; 1045 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 1046 pkt [rdlen_offs - 1] = rdlen;
889 1047
890 if (dns) 1048 if (dns)
891 { 1049 {
892 // now update dns_rcv copy 1050 // now update dns_rcv copy
893 rcv->pkt->len = offs; 1051 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 1052 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 1053 }
1054 }
896 1055
897 duplicate_request: ; 1056 duplicate_request: ;
898 } 1057 }
899 else 1058 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 1059 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
… …
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 1071 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 1072 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 1073 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 1074 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 1075
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; 1076 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 1077 pkt [offs++] = CMD_IP_REJ;
921 1078
922 if (0 < client && client <= conns.size ()) 1079 if (0 < client && client <= conns.size ())
923 { 1080 {
924 connection *c = conns [client - 1]; 1081 connection *c = conns [client - 1];
925 1082
926 if (cfg.valid ()) 1083 if (cfg.valid ())
927 { 1084 {
928 pkt [offs - 1] = CMD_IP_SYN; 1085 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
1086
1087 // check for any encoding mismatches - hints at a case problem
1088 char qname2 [MAX_ENC_LEN];
1089 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
929 1090
930 delete c->dns; 1091 delete c->dns;
1092
1093 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1094 ? CMD_IP_CSE : CMD_IP_SYN;
1095
931 c->dns = new dns_connection (c); 1096 c->dns = new dns_connection (c);
932 c->dns->cfg = cfg; 1097 c->dns->cfg = cfg;
1098 c->dns->set_cfg ();
933 } 1099 }
934 } 1100 }
935 } 1101 }
936 } 1102 }
937 1103
… …
956 { 1122 {
957 dns_connection *dns = (*i)->dns; 1123 dns_connection *dns = (*i)->dns;
958 connection *c = dns->c; 1124 connection *c = dns->c;
959 int seqno = (*i)->seqno; 1125 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1126 u8 data[MAXSIZE], *datap = data;
1127 //printf ("rcv pkt %x\n", seqno);//D
1128 bool back_off = (*i)->retry;
961 1129
962 if ((*i)->retry) 1130 if (back_off)
963 { 1131 {
964 dns->send_interval *= 1.001; 1132 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1133 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1134 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1135 }
968 else 1136 else
969 { 1137 {
970#if 1 1138#if 0
971 dns->send_interval *= 0.9999; 1139 dns->send_interval *= 0.999;
972#endif 1140#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 1141 // the latency surely puts an upper bound on
977 // the minimum send interval 1142 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1143 double latency = ev_now () - (*i)->sent;
979 1144
980 if (dns->send_interval > latency) 1145 if (latency < dns->min_latency)
981 dns->send_interval = latency; 1146 dns->min_latency = latency;
1147
1148 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1149 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1150
1151 if (dns->send_interval < conf.dns_send_interval)
1152 dns->send_interval = conf.dns_send_interval;
982 } 1153 }
983 1154
984 delete *i; 1155 delete *i;
985 dns_sndpq.erase (i); 1156 dns_sndpq.erase (i);
986 1157
… …
1004 ttl |= pkt [offs++] << 16; 1175 ttl |= pkt [offs++] << 16;
1005 ttl |= pkt [offs++] << 8; 1176 ttl |= pkt [offs++] << 8;
1006 ttl |= pkt [offs++]; 1177 ttl |= pkt [offs++];
1007 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; 1178 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
1008 1179
1009 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) 1180 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
1010 { 1181 {
1011 if (rdlen <= MAXSIZE - offs) 1182 if (rdlen <= MAXSIZE - offs)
1012 { 1183 {
1013 // decode bytes, finally 1184 // decode bytes, finally
1014 1185
… …
1036 1207
1037 if (ip [0] == CMD_IP_1 1208 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1209 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1210 && ip [2] == CMD_IP_3)
1040 { 1211 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1212 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1213
1043 if (ip [3] == CMD_IP_RST) 1214 if (ip [3] == CMD_IP_RST)
1044 { 1215 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1216 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1046 1217
1047 delete dns; c->dns = 0; 1218 dns->reset ();
1048
1049 return; 1219 return;
1050 } 1220 }
1051 else if (ip [3] == CMD_IP_SYN) 1221 else if (ip [3] == CMD_IP_SYN)
1052 { 1222 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1223 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 1224 dns->established = true;
1225 }
1226 else if (ip [3] == CMD_IP_CSE)
1227 {
1228 if (conf.dns_case_preserving)
1229 {
1230 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1231 conf.dns_case_preserving = false;
1232 dns->reset ();
1233 return;
1234 }
1235 else
1236 {
1237 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1238 dns->established = true;
1239 }
1055 } 1240 }
1056 else if (ip [3] == CMD_IP_REJ) 1241 else if (ip [3] == CMD_IP_REJ)
1057 { 1242 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1243 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1059 abort (); 1244 dns->tw.start (60.);
1060 } 1245 }
1061 else 1246 else
1247 {
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1248 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1249 dns->tw.start (60.);
1250 }
1063 } 1251 }
1064 else 1252 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1253 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1254 ip [0], ip [1], ip [2], ip [3]);
1067 1255
1068 return; 1256 return;
1069 } 1257 }
1070 1258
1071 int client, rseqno; 1259 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1260 decode_header (qname, client, rseqno);
1073 1261
1074 if (client != THISNODE->id) 1262 if (client != THISNODE->id)
1075 { 1263 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1264 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1265 datap = 0;
1078 } 1266 }
1079 else if (rseqno != seqno) 1267 else if (rseqno != seqno)
1080 { 1268 {
1081 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1269 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1082 datap = 0; 1270 datap = 0;
1083 } 1271 }
1084 } 1272 }
1085 } 1273 }
1086 1274
1087 // todo: pkt now used 1275 // todo: pkt now used
1088 if (datap) 1276 if (datap)
1089 dns->receive_rep (new dns_rcv (seqno, data, datap - data)); 1277 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
1278 else if (dns_sndpq.empty ()) // no data received, and nothing to send - idle
1279 {
1280 dns->send_interval *= 1.1;
1281
1282 if (dns->send_interval < MIN_POLL_INTERVAL)
1283 dns->send_interval = MIN_POLL_INTERVAL;
1284
1285 if (dns->send_interval > MAX_POLL_INTERVAL && !back_off)
1286 dns->send_interval = MAX_POLL_INTERVAL;
1287 }
1090 1288
1091 break; 1289 break;
1092 } 1290 }
1093} 1291}
1094 1292
1095void 1293void
1096vpn::dnsv4_ev (io_watcher &w, short revents) 1294vpn::dnsv4_ev (ev::io &w, int revents)
1097{ 1295{
1098 if (revents & EVENT_READ) 1296 if (revents & EV_READ)
1099 { 1297 {
1100 dns_packet *pkt = new dns_packet; 1298 dns_packet *pkt = new dns_packet;
1101 struct sockaddr_in sa; 1299 struct sockaddr_in sa;
1102 socklen_t sa_len = sizeof (sa); 1300 socklen_t sa_len = sizeof (sa);
1103 1301
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1302 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1303
1106 if (pkt->len > 0) 1304 if (pkt->len > 0)
1107 { 1305 {
1108 if (THISNODE->dns_port) 1306 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1307 dnsv4_client (*pkt);
1308 else
1109 { 1309 {
1110 dnsv4_server (*pkt); 1310 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1311 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1312 }
1113 else
1114 dnsv4_client (*pkt);
1115 1313
1116 delete pkt; 1314 delete pkt;
1117 } 1315 }
1118 } 1316 }
1119} 1317}
1120 1318
1121bool 1319bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1320vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1321{
1322 int client = ntohl (si.host);
1323
1324 assert (0 < client && client <= conns.size ());
1325
1326 connection *c = conns [client - 1];
1327
1124 if (!dns) 1328 if (!c->dns)
1125 dns = new dns_connection (this); 1329 c->dns = new dns_connection (c);
1126 1330
1127 if (!dns->snddq.put (pkt)) 1331 if (c->dns->snddq.put (pkt))
1128 return false; 1332 c->dns->tw ();
1129 1333
1130 dns->tw.trigger (); 1334 // always return true even if the buffer overflows
1131
1132 return true; 1335 return true;
1133} 1336}
1134 1337
1338#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1339
1135void 1340void
1136connection::dnsv4_reset_connection () 1341dns_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{ 1342{
1146 // servers have to be polled 1343 // servers have to be polled
1147 if (THISNODE->dns_port) 1344 if (THISNODE->dns_port)
1148 return; 1345 return;
1149 1346
1150 // check for timeouts and (re)transmit 1347 // check for timeouts and (re)transmit
1151 tstamp next = NOW + poll_interval; 1348 tstamp next = ev::now () + poll_interval;
1152 dns_snd *send = 0; 1349 dns_snd *send = 0;
1153 1350
1154 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); 1351 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
1155 i != vpn->dns_sndpq.end (); 1352 i != vpn->dns_sndpq.end ();
1156 ++i) 1353 ++i)
1157 { 1354 {
1158 dns_snd *r = *i; 1355 dns_snd *r = *i;
1159 1356
1160 if (r->timeout <= NOW) 1357 if (r->timeout <= ev_now ())
1161 { 1358 {
1162 if (!send) 1359 if (!send)
1163 { 1360 {
1164 send = r; 1361 send = r;
1165 1362
1166 r->retry++; 1363 r->retry++;
1167 r->timeout = NOW + r->retry; 1364 r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
1365 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1366
1367 // the following code changes the query section a bit, forcing
1368 // the forwarder to generate a new request
1369 if (r->stdhdr)
1370 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1168 } 1371 }
1169 } 1372 }
1170 else 1373 else
1171 NEXT (r->timeout); 1374 NEXT (r->timeout);
1172 } 1375 }
1173 1376
1174 if (last_sent + send_interval <= NOW)
1175 {
1176 if (!send) 1377 if (!send)
1378 {
1379 // generate a new packet, if wise
1380
1381 if (!established)
1177 { 1382 {
1178 // generate a new packet, if wise
1179
1180 if (!established)
1181 {
1182 if (vpn->dns_sndpq.empty ()) 1383 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 { 1384 {
1192 send = new dns_snd (this); 1385 send = new dns_snd (this);
1386
1387 cfg.reset (THISNODE->id);
1388 set_cfg ();
1389 send->gen_syn_req ();
1390 }
1391 }
1392 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1393 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1394 {
1395 if (last_sent + send_interval <= ev_now ())
1396 {
1397 //printf ("sending data request etc.\n"); //D
1398 if (!snddq.empty () || last_received + 1. > ev_now ())
1399 {
1400 poll_interval = send_interval;
1401 NEXT (ev_now () + send_interval);
1402 }
1403
1404 send = new dns_snd (this);
1193 send->gen_stream_req (sndseq, snddq); 1405 send->gen_stream_req (sndseq, snddq);
1406 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1407 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1194 1408
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1409 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1410 }
1197 1411 else
1198 if (send) 1412 NEXT (last_sent + send_interval);
1199 vpn->dns_sndpq.push_back (send);
1200 } 1413 }
1201 1414
1202 if (send) 1415 if (send)
1203 { 1416 vpn->dns_sndpq.push_back (send);
1204 last_sent = NOW; 1417 }
1418
1419 if (send)
1420 {
1421 last_sent = ev_now ();
1205 sendto (vpn->dnsv4_fd, 1422 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1423 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1424 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1425 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1426
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1427 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1428 poll_interval, send_interval, next - ev_now (),
1215 vpn->dns_sndpq.size (), snddq.size ()); 1429 vpn->dns_sndpq.size (), snddq.size (),
1430 rcvpq.size ());
1216 1431
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem 1432 // TODO: no idea when this happens, but when next < ev_now (), we have a problem
1433 // doesn't seem to happen anymore
1218 if (next < NOW + 0.0001) 1434 if (next < ev_now () + 0.001)
1219 next = NOW + 0.1; 1435 next = ev_now () + 0.1;
1220 1436
1221 w.start (next); 1437 w.start (next - ev_now ());
1222} 1438}
1223 1439
1224#endif 1440#endif
1225 1441

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