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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 1.52 by root, Sun Mar 6 21:01:37 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 240 // 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 unsigned int len;
403
404 for (;;)
405 {
356 int len = (data [0] << 8) | data [1]; 406 len = (data [0] << 8) | data [1];
357 407
358 if (len > MAXSIZE && fill >= 2) 408 if (len <= MAXSIZE || fill < 2)
359 abort (); // TODO handle this gracefully, connection reset 409 break;
360 410
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
361 if (fill < len + 2) 416 if (fill < len + 2)
362 return 0; 417 return 0;
363 418
364 vpn_packet *pkt = new vpn_packet; 419 vpn_packet *pkt = new vpn_packet;
365 420
… …
393 448
394struct dns_cfg 449struct dns_cfg
395{ 450{
396 static int next_uid; 451 static int next_uid;
397 452
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
398 u8 id1, id2, id3, id4; 461 u8 id1, id2, id3, id4;
399 u8 version; 462
400 u8 rrtype; 463 u16 client;
401 u8 flags;
402 u8 def_ttl; 464 u8 def_ttl;
403 u8 rcv_cdc; 465 u8 r0;
404 u8 snd_cdc;
405 u16 max_size;
406 u16 client;
407 u16 uid; // to make request unique
408 466
409 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;
410 473
411 void reset (int clientid); 474 void reset (int clientid);
412 bool valid (); 475 bool valid ();
476 u8 get_chksum ();
413}; 477};
414 478
415int dns_cfg::next_uid; 479int dns_cfg::next_uid;
416 480
481void
417void dns_cfg::reset (int clientid) 482dns_cfg::reset (int clientid)
418{ 483{
484 // this ID must result in some mixed-case characters in cdc26-encoding
419 id1 = 'G'; 485 id1 = 'G';
420 id2 = 'V'; 486 id2 = 'V';
421 id3 = 'P'; 487 id3 = 'P';
422 id4 = 'E'; 488 id4 = 'E';
423 489
424 version = 1; 490 version = 2;
425 491
426 rrtype = RR_TYPE_TXT; 492 rrtype = RR_TYPE_TXT;
427 flags = 0; 493 flags = 0;
428 def_ttl = 0; 494 def_ttl = 0;
429 rcv_cdc = 0;
430 snd_cdc = 62; 495 syn_cdc = 26;
496 hdr_cdc = 36;
497 req_cdc = conf.dns_case_preserving ? 62 : 36;
498 rep_cdc = 0;
431 max_size = ntohs (MAX_PKT_SIZE); 499 max_size = htons (MAX_PKT_SIZE);
432 client = ntohs (clientid); 500 client = htons (clientid);
433 uid = next_uid++; 501 uid = ++next_uid;
434 502
435 memset (reserved, 0, 8); 503 r0 = r1 = r2 = r3 = r4 = 0;
436}
437 504
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
438bool dns_cfg::valid () 526dns_cfg::valid ()
439{ 527{
528 // although the protocol itself allows for some configurability,
529 // only the following encoding/decoding settings are implemented.
440 return id1 == 'G' 530 return id1 == 'G'
441 && id2 == 'V' 531 && id2 == 'V'
442 && id3 == 'P' 532 && id3 == 'P'
443 && id4 == 'E' 533 && id4 == 'E'
444 && version == 1 534 && version == 2
445 && flags == 0
446 && rcv_cdc == 0
447 && snd_cdc == 62 535 && syn_cdc == 26
448 && 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 ();
449} 540}
450 541
451struct dns_packet : net_packet 542struct dns_packet : net_packet
452{ 543{
453 u16 id; 544 u16 id;
454 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
455 u16 qdcount, ancount, nscount, arcount; 546 u16 qdcount, ancount, nscount, arcount;
456 547
457 u8 data[MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
458 549
459 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
460}; 551};
461 552
553int
462int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
463{ 555{
464 char *orig = data; 556 char *orig = data;
465 557
466 memset (data, 0, size); 558 memset (data, 0, size);
467 559
… …
493 return data - orig; 585 return data - orig;
494} 586}
495 587
496///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
497 589
498struct dns_snd 590static
591u16 next_id ()
499{ 592{
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 593 static u16 dns_id = 0; // TODO: should be per-vpn
512 594
513static u16 next_id () 595 if (!dns_id)
514{ 596 dns_id = time (0);
597
515 // the simplest lsfr with periodicity 65535 i could find 598 // the simplest lsfr with periodicity 65535 i could find
516 dns_id = (dns_id << 1) 599 dns_id = (dns_id << 1)
517 | (((dns_id >> 1) 600 | (((dns_id >> 1)
518 ^ (dns_id >> 2) 601 ^ (dns_id >> 2)
519 ^ (dns_id >> 4) 602 ^ (dns_id >> 4)
520 ^ (dns_id >> 15)) & 1); 603 ^ (dns_id >> 15)) & 1);
521 604
522 return dns_id; 605 return dns_id;
523} 606}
524 607
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
525dns_snd::dns_snd (dns_connection *dns) 657dns_snd::dns_snd (dns_connection *dns)
526: dns (dns) 658: dns (dns)
527{ 659{
528 timeout = 0; 660 timeout = 0;
529 retry = 0; 661 retry = 0;
530 seqno = 0; 662 seqno = 0;
663 sent = ev_now ();
664 stdhdr = false;
531 665
532 pkt = new dns_packet; 666 pkt = new dns_packet;
533 667
534 pkt->id = next_id (); 668 pkt->id = next_id ();
535} 669}
536 670
671dns_snd::~dns_snd ()
672{
673 delete pkt;
674}
675
676static void
537static void append_domain (dns_packet &pkt, int &offs, const char *domain) 677append_domain (dns_packet &pkt, int &offs, const char *domain)
538{ 678{
539 // add tunnel domain 679 // add tunnel domain
540 for (;;) 680 for (;;)
541 { 681 {
542 const char *end = strchr (domain, '.'); 682 const char *end = strchr (domain, '.');
… …
555 695
556 domain = end + 1; 696 domain = end + 1;
557 } 697 }
558} 698}
559 699
700void
560void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 701dns_snd::gen_stream_req (int seqno, byte_stream &stream)
561{ 702{
703 stdhdr = true;
562 this->seqno = seqno; 704 this->seqno = seqno;
563 705
564 timeout = NOW + INITIAL_TIMEOUT; 706 timeout = ev_now () + INITIAL_TIMEOUT;
565 707
566 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 708 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
567 pkt->qdcount = htons (1); 709 pkt->qdcount = htons (1);
568 710
569 int offs = 6*2; 711 int offs = 6*2;
570 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 712 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, 713 // 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 714 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
573 715
574 char enc[256], *encp = enc; 716 char enc[256], *encp = enc;
575 encode_header (enc, THISNODE->id, seqno); 717 encode_header (enc, THISNODE->id, seqno);
576 718
577 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);
578 720
579 if (datalen > stream.size ()) 721 if (datalen > stream.size ())
580 datalen = stream.size (); 722 datalen = stream.size ();
581 723
582 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 724 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
583 stream.remove (datalen); 725 stream.remove (datalen);
584 726
585 while (enclen) 727 while (enclen)
586 { 728 {
587 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 729 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
593 encp += lbllen; 735 encp += lbllen;
594 736
595 enclen -= lbllen; 737 enclen -= lbllen;
596 } 738 }
597 739
598 append_domain (*pkt, offs, THISNODE->domain); 740 append_domain (*pkt, offs, dns->c->conf->domain);
599 741
600 (*pkt)[offs++] = 0; 742 (*pkt)[offs++] = 0;
601 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 743 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
602 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 744 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
603 745
604 pkt->len = offs; 746 pkt->len = offs;
605} 747}
606 748
607void dns_snd::gen_syn_req (const dns_cfg &cfg) 749void
750dns_snd::gen_syn_req ()
608{ 751{
609 timeout = NOW + INITIAL_SYN_TIMEOUT; 752 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
610 753
611 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 754 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
612 pkt->qdcount = htons (1); 755 pkt->qdcount = htons (1);
613 756
614 int offs = 6*2; 757 int offs = 6 * 2;
615 758
616 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));
617 760
618 assert (elen <= MAX_LBL_SIZE); 761 assert (elen <= MAX_LBL_SIZE);
619 762
620 (*pkt)[offs] = elen; 763 (*pkt)[offs] = elen;
621 offs += elen + 1; 764 offs += elen + 1;
622 append_domain (*pkt, offs, THISNODE->domain); 765 append_domain (*pkt, offs, dns->c->conf->domain);
623 766
624 (*pkt)[offs++] = 0; 767 (*pkt)[offs++] = 0;
625 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 768 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
626 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 769 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
627 770
… …
650 delete pkt; 793 delete pkt;
651} 794}
652 795
653///////////////////////////////////////////////////////////////////////////// 796/////////////////////////////////////////////////////////////////////////////
654 797
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) 798dns_connection::dns_connection (connection *c)
681: c (c) 799: c (c)
682, rcvdq (MAX_BACKLOG * 2) 800, rcvdq (MAX_BACKLOG * 2)
683, snddq (MAX_BACKLOG * 2) 801, snddq (MAX_BACKLOG)
684, tw (this, &dns_connection::time_cb)
685{ 802{
803 tw.set<dns_connection, &dns_connection::time_cb> (this);
804
686 vpn = c->vpn; 805 vpn = c->vpn;
687 806
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
688 established = false; 831 established = false;
689 832
690 rcvseq = sndseq = 0; 833 rcvseq = repseq = sndseq = 0;
691 834
692 last_sent = last_received = 0; 835 last_sent = 0;
693 poll_interval = MIN_POLL_INTERVAL; 836 poll_interval = 0.5; // starting here
694 send_interval = 0.2; // starting rate 837 send_interval = 0.5; // starting rate
838 min_latency = INITIAL_TIMEOUT;
695} 839}
696 840
697dns_connection::~dns_connection () 841void
842dns_connection::set_cfg ()
698{ 843{
699 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 844 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
700 i != rcvpq.end ();
701 ++i)
702 delete *i;
703} 845}
704 846
847void
705void dns_connection::receive_rep (dns_rcv *r) 848dns_connection::receive_rep (dns_rcv *r)
706{ 849{
707 if (r->datalen) 850 if (r->datalen)
708 { 851 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 852 else
717 { 853 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 }
722 854
723 rcvpq.push_back (r); 855 rcvpq.push_back (r);
724 856
725 redo: 857 redo:
726 858
727 // find next packet 859 // find next packet
728 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 860 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
729 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 861 if (SEQNO_EQ (rcvseq, (*i)->seqno))
730 { 862 {
863 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
731 // enter the packet into our input stream 864 // enter the packet into our input stream
732 r = *i; 865 r = *i;
733 866
734 // remove the oldest packet, look forward, as it's oldest first 867 // remove the oldest packet, look forward, as it's oldest first
735 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) 868 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
736 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 869 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
737 { 870 {
871 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
738 delete *j; 872 delete *j;
739 rcvpq.erase (j); 873 rcvpq.erase (j);
740 break; 874 break;
741 } 875 }
742 876
743 rcvseq = (rcvseq + 1) & SEQNO_MASK; 877 rcvseq = (rcvseq + 1) & SEQNO_MASK;
744 878
745 if (!rcvdq.put (r->data, r->datalen)) 879 if (!rcvdq.put (r->data, r->datalen))
880 {
746 abort (); // MUST never overflow, can be caused by data corruption, TODO 881 // MUST never overflow, can be caused by data corruption, TODO
882 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
883 reset ();
884 return;
885 }
747 886
748 while (vpn_packet *pkt = rcvdq.get ()) 887 while (vpn_packet *pkt = rcvdq.get ())
749 { 888 {
750 sockinfo si; 889 sockinfo si;
751 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 890 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
752 891
753 vpn->recv_vpn_packet (pkt, si); 892 vpn->recv_vpn_packet (pkt, si);
893 delete pkt;
754 } 894 }
755 895
756 // check for further packets 896 // check for further packets
757 goto redo; 897 goto redo;
758 } 898 }
… …
768 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 908 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
769 909
770 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 910 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
771 && pkt.qdcount == htons (1)) 911 && pkt.qdcount == htons (1))
772 { 912 {
773 char qname[MAXSIZE]; 913 char qname [MAXSIZE];
774 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 914 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
775 915
776 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 916 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
777 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 917 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
778 918
779 pkt.qdcount = htons (1); 919 pkt.qdcount = htons (1);
780 pkt.ancount = 0; 920 pkt.ancount = 0;
781 pkt.nscount = 0; // should be self, as other nameservers reply like this 921 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 922 pkt.arcount = 0; // a record for self, as other nameservers reply like this
783 923
784 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 924 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
785 925
786 int dlen = strlen (THISNODE->domain); 926 int dlen = strlen (THISNODE->domain);
787 927
788 if (qclass == RR_CLASS_IN 928 if (qclass == RR_CLASS_IN
789 && qlen > dlen + 1 929 && qlen > dlen + 1
790 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 930 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
791 { 931 {
792 // now generate reply 932 // now generate reply
793 pkt.ancount = htons (1); // one answer RR 933 pkt.ancount = htons (1); // one answer RR
794 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 934 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
795 935
… …
800 { 940 {
801 // correct class, domain: parse 941 // correct class, domain: parse
802 int client, seqno; 942 int client, seqno;
803 decode_header (qname, client, seqno); 943 decode_header (qname, client, seqno);
804 944
805 u8 data[MAXSIZE];
806 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
807
808 if (0 < client && client <= conns.size ()) 945 if (0 < client && client <= conns.size ())
809 { 946 {
810 connection *c = conns [client - 1]; 947 connection *c = conns [client - 1];
811 dns_connection *dns = c->dns; 948 dns_connection *dns = c->dns;
812 dns_rcv *rcv; 949 dns_rcv *rcv;
813 950
814 if (dns) 951 if (dns)
815 { 952 {
953 u8 data[MAXSIZE];
954 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
955
816 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 956 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
817 if (SEQNO_EQ ((*i)->seqno, seqno)) 957 if (SEQNO_EQ ((*i)->seqno, seqno))
818 { 958 {
819 // already seen that request: simply reply with the cached reply 959 // already seen that request: simply reply with the cached reply
820 dns_rcv *r = *i; 960 dns_rcv *r = *i;
821 961
822 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 962 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
963
964 // refresh header & id, as the retry count could have changed
965 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
966 r->pkt->id = pkt.id;
823 967
824 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 968 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
825 pkt.id = r->pkt->id; 969
826 goto duplicate_request; 970 goto duplicate_request;
827 } 971 }
828 972
829 // new packet, queue 973 // new packet, queue
830 rcv = new dns_rcv (seqno, data, datalen); 974 rcv = new dns_rcv (seqno, data, datalen);
831 dns->receive_rep (rcv); 975 dns->receive_rep (rcv);
832 } 976 }
833 977
978 {
834 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 979 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
835 980
836 // type
837 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 981 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
838 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; 982 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
839
840 // class
841 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; 983 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
842
843 // TTL
844 pkt [offs++] = 0; pkt [offs++] = 0; 984 pkt [offs++] = 0; pkt [offs++] = 0;
845 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; 985 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
846 986
847 int rdlen_offs = offs += 2; 987 int rdlen_offs = offs += 2;
848 988
989 if (dns)
990 {
849 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 991 int dlen = ntohs (dns->cfg.max_size) - offs;
992
850 // bind doesn't compress well, so reduce further by one label length 993 // bind doesn't compress well, so reduce further by one label length
851 dlen -= qlen; 994 dlen -= qlen;
852 995
853 if (dns) 996 // only put data into in-order sequence packets, if
854 { 997 // we receive out-of-order packets we generate empty
855 while (dlen > 1 && !dns->snddq.empty ()) 998 // replies
999 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
1000 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
856 { 1001 {
1002 dns->repseq = seqno;
1003
1004 while (dlen > 1 && !dns->snddq.empty ())
1005 {
857 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1006 int txtlen = dlen <= 255 ? dlen - 1 : 255;
858 1007
859 if (txtlen > dns->snddq.size ()) 1008 if (txtlen > dns->snddq.size ())
860 txtlen = dns->snddq.size (); 1009 txtlen = dns->snddq.size ();
861 1010
862 pkt[offs++] = txtlen; 1011 pkt[offs++] = txtlen;
863 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 1012 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
864 offs += txtlen; 1013 offs += txtlen;
865 dns->snddq.remove (txtlen); 1014 dns->snddq.remove (txtlen);
866 1015
867 dlen -= txtlen + 1; 1016 dlen -= txtlen + 1;
1017 }
868 } 1018 }
869 1019
870 // avoid empty TXT rdata 1020 // avoid completely empty TXT rdata
871 if (offs == rdlen_offs) 1021 if (offs == rdlen_offs)
872 pkt[offs++] = 0; 1022 pkt[offs++] = 0;
1023
1024 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
873 } 1025 }
874 else 1026 else
875 { 1027 {
876 // send RST 1028 // send RST
877 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 1029 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
878 pkt [offs++] = CMD_IP_RST; 1030 pkt [offs++] = CMD_IP_RST;
879 } 1031 }
880 1032
881 int rdlen = offs - rdlen_offs; 1033 int rdlen = offs - rdlen_offs;
882 1034
883 pkt [rdlen_offs - 2] = rdlen >> 8; 1035 pkt [rdlen_offs - 2] = rdlen >> 8;
884 pkt [rdlen_offs - 1] = rdlen; 1036 pkt [rdlen_offs - 1] = rdlen;
885 1037
886 if (dns) 1038 if (dns)
887 { 1039 {
888 // now update dns_rcv copy 1040 // now update dns_rcv copy
889 rcv->pkt->len = offs; 1041 rcv->pkt->len = offs;
890 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 1042 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
891 } 1043 }
1044 }
892 1045
893 duplicate_request: ; 1046 duplicate_request: ;
894 } 1047 }
895 else 1048 else
896 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 1049 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
… …
908 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 1061 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
909 pkt [offs++] = 0; pkt [offs++] = 0; 1062 pkt [offs++] = 0; pkt [offs++] = 0;
910 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 1063 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
911 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 1064 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
912 1065
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; 1066 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
916 pkt [offs++] = CMD_IP_REJ; 1067 pkt [offs++] = CMD_IP_REJ;
917 1068
918 if (0 < client && client <= conns.size ()) 1069 if (0 < client && client <= conns.size ())
919 { 1070 {
920 connection *c = conns [client - 1]; 1071 connection *c = conns [client - 1];
921 1072
922 if (cfg.valid ()) 1073 if (cfg.valid ())
923 { 1074 {
924 pkt [offs - 1] = CMD_IP_SYN; 1075 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
1076
1077 // check for any encoding mismatches - hints at a case problem
1078 char qname2 [MAX_ENC_LEN];
1079 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
925 1080
926 delete c->dns; 1081 delete c->dns;
1082
1083 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1084 ? CMD_IP_CSE : CMD_IP_SYN;
1085
927 c->dns = new dns_connection (c); 1086 c->dns = new dns_connection (c);
928 c->dns->cfg = cfg; 1087 c->dns->cfg = cfg;
1088 c->dns->set_cfg ();
929 } 1089 }
930 } 1090 }
931 } 1091 }
932 } 1092 }
933 1093
… …
949 i != dns_sndpq.end (); 1109 i != dns_sndpq.end ();
950 ++i) 1110 ++i)
951 if ((*i)->pkt->id == pkt.id) 1111 if ((*i)->pkt->id == pkt.id)
952 { 1112 {
953 dns_connection *dns = (*i)->dns; 1113 dns_connection *dns = (*i)->dns;
1114 connection *c = dns->c;
954 int seqno = (*i)->seqno; 1115 int seqno = (*i)->seqno;
955 u8 data[MAXSIZE], *datap = data; 1116 u8 data[MAXSIZE], *datap = data;
1117 //printf ("rcv pkt %x\n", seqno);//D
956 1118
957 if ((*i)->retry) 1119 if ((*i)->retry)
958 { 1120 {
959 dns->send_interval *= 1.01; 1121 dns->send_interval *= 1.01;
960 if (dns->send_interval < MAX_SEND_INTERVAL) 1122 if (dns->send_interval > MAX_SEND_INTERVAL)
961 dns->send_interval = MAX_SEND_INTERVAL; 1123 dns->send_interval = MAX_SEND_INTERVAL;
962 } 1124 }
963 else 1125 else
964 { 1126 {
1127#if 0
965 dns->send_interval *= 0.99; 1128 dns->send_interval *= 0.999;
966 if (dns->send_interval < MIN_SEND_INTERVAL) 1129#endif
967 dns->send_interval = MIN_SEND_INTERVAL;
968
969 // the latency surely puts an upper bound on 1130 // the latency surely puts an upper bound on
970 // the minimum send interval 1131 // the minimum send interval
971 if (dns->send_interval > NOW - (*i)->sent) 1132 double latency = ev_now () - (*i)->sent;
972 dns->send_interval = NOW - (*i)->sent; 1133
1134 if (latency < dns->min_latency)
1135 dns->min_latency = latency;
1136
1137 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1138 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1139
1140 if (dns->send_interval < conf.dns_send_interval)
1141 dns->send_interval = conf.dns_send_interval;
973 } 1142 }
974 1143
975 delete *i; 1144 delete *i;
976 dns_sndpq.erase (i); 1145 dns_sndpq.erase (i);
977 1146
… …
995 ttl |= pkt [offs++] << 16; 1164 ttl |= pkt [offs++] << 16;
996 ttl |= pkt [offs++] << 8; 1165 ttl |= pkt [offs++] << 8;
997 ttl |= pkt [offs++]; 1166 ttl |= pkt [offs++];
998 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; 1167 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
999 1168
1000 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) 1169 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
1001 { 1170 {
1002 if (rdlen <= MAXSIZE - offs) 1171 if (rdlen <= MAXSIZE - offs)
1003 { 1172 {
1004 // decode bytes, finally 1173 // decode bytes, finally
1005 1174
… …
1027 1196
1028 if (ip [0] == CMD_IP_1 1197 if (ip [0] == CMD_IP_1
1029 && ip [1] == CMD_IP_2 1198 && ip [1] == CMD_IP_2
1030 && ip [2] == CMD_IP_3) 1199 && ip [2] == CMD_IP_3)
1031 { 1200 {
1032 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1201 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1033 1202
1034 if (ip [3] == CMD_IP_RST) 1203 if (ip [3] == CMD_IP_RST)
1035 { 1204 {
1036 slog (L_DEBUG, _("got tunnel RST request")); 1205 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1037 1206
1038 connection *c = dns->c; 1207 dns->reset ();
1039 delete c->dns; c->dns = 0;
1040
1041 return; 1208 return;
1042 } 1209 }
1043 else if (ip [3] == CMD_IP_SYN) 1210 else if (ip [3] == CMD_IP_SYN)
1211 {
1212 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1044 dns->established = true; 1213 dns->established = true;
1214 }
1215 else if (ip [3] == CMD_IP_CSE)
1216 {
1217 if (conf.dns_case_preserving)
1218 {
1219 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1220 conf.dns_case_preserving = false;
1221 dns->reset ();
1222 return;
1223 }
1224 else
1225 {
1226 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1227 dns->established = true;
1228 }
1229 }
1230 else if (ip [3] == CMD_IP_REJ)
1231 {
1232 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1233 dns->tw.start (60.);
1234 }
1045 else 1235 else
1236 {
1046 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1237 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1238 dns->tw.start (60.);
1239 }
1047 } 1240 }
1048 else 1241 else
1049 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1242 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1050 ip [0], ip [1], ip [2], ip [3]); 1243 ip [0], ip [1], ip [2], ip [3]);
1051 1244
1052 return; 1245 return;
1053 } 1246 }
1054 1247
1055 int client, rseqno; 1248 int client, rseqno;
1056 decode_header (qname, client, rseqno); 1249 decode_header (qname, client, rseqno);
1057 1250
1058 if (client != THISNODE->id) 1251 if (client != THISNODE->id)
1059 { 1252 {
1060 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1253 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1061 datap = 0; 1254 datap = 0;
1062 } 1255 }
1063 else if (rseqno != seqno) 1256 else if (rseqno != seqno)
1064 { 1257 {
1065 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1258 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1066 datap = 0; 1259 datap = 0;
1067 } 1260 }
1068 } 1261 }
1069 } 1262 }
1070 1263
… …
1075 break; 1268 break;
1076 } 1269 }
1077} 1270}
1078 1271
1079void 1272void
1080vpn::dnsv4_ev (io_watcher &w, short revents) 1273vpn::dnsv4_ev (ev::io &w, int revents)
1081{ 1274{
1082 if (revents & EVENT_READ) 1275 if (revents & EV_READ)
1083 { 1276 {
1084 dns_packet *pkt = new dns_packet; 1277 dns_packet *pkt = new dns_packet;
1085 struct sockaddr_in sa; 1278 struct sockaddr_in sa;
1086 socklen_t sa_len = sizeof (sa); 1279 socklen_t sa_len = sizeof (sa);
1087 1280
1088 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1281 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1089 1282
1090 if (pkt->len > 0) 1283 if (pkt->len > 0)
1091 { 1284 {
1092 if (THISNODE->dns_port) 1285 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1286 dnsv4_client (*pkt);
1287 else
1093 { 1288 {
1094 dnsv4_server (*pkt); 1289 dnsv4_server (*pkt);
1095 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1290 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1096 } 1291 }
1097 else
1098 dnsv4_client (*pkt);
1099 1292
1100 delete pkt; 1293 delete pkt;
1101 } 1294 }
1102 } 1295 }
1103} 1296}
1104 1297
1105bool 1298bool
1106connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1299vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1107{ 1300{
1301 int client = ntohl (si.host);
1302
1303 assert (0 < client && client <= conns.size ());
1304
1305 connection *c = conns [client - 1];
1306
1108 if (!dns) 1307 if (!c->dns)
1109 dns = new dns_connection (this); 1308 c->dns = new dns_connection (c);
1110 1309
1111 if (!dns->snddq.put (pkt)) 1310 if (c->dns->snddq.put (pkt))
1112 return false; 1311 {
1312 min_it (c->dns->poll_interval, 0.25);
1313 c->dns->tw ();
1314 }
1113 1315
1114 dns->tw.trigger (); 1316 // always return true even if the buffer overflows
1115
1116 return true; 1317 return true;
1117} 1318}
1118 1319
1119#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1120
1121void 1320void
1122dns_connection::time_cb (time_watcher &w) 1321dns_connection::time_cb (ev::timer &w, int revents)
1123{ 1322{
1124 // servers have to be polled 1323 // servers have to be polled
1125 if (THISNODE->dns_port) 1324 if (THISNODE->dns_port)
1126 return; 1325 return;
1127 1326
1128 // check for timeouts and (re)transmit 1327 // check for timeouts and (re)transmit
1129 tstamp next = NOW + poll_interval; 1328 tstamp next = 86400 * 365;
1130 dns_snd *send = 0; 1329 dns_snd *send = 0;
1131 1330
1132 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); 1331 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
1133 i != vpn->dns_sndpq.end (); 1332 i != vpn->dns_sndpq.end ();
1134 ++i) 1333 ++i)
1135 { 1334 {
1136 dns_snd *r = *i; 1335 dns_snd *r = *i;
1137 1336
1138 if (r->timeout <= NOW) 1337 if (r->timeout <= ev_now ())
1139 { 1338 {
1140 if (!send) 1339 if (!send)
1141 { 1340 {
1142 send = r; 1341 send = r;
1143 1342
1144 r->retry++; 1343 r->retry++;
1145 r->timeout = NOW + r->retry; 1344 r->timeout = ev_now () + r->retry * min_latency * conf.dns_timeout_factor;
1345 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1346
1347 // the following code changes the query section a bit, forcing
1348 // the forwarder to generate a new request
1349 if (r->stdhdr)
1350 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1146 } 1351 }
1147 } 1352 }
1148 else if (r->timeout < next) 1353 else
1149 NEXT (r->timeout); 1354 min_it (next, r->timeout - ev_now ());
1150 }
1151
1152 if (last_sent + send_interval <= NOW)
1153 { 1355 }
1356
1154 if (!send) 1357 if (!send)
1358 {
1359 // generate a new packet, if wise
1360
1361 if (!established)
1155 { 1362 {
1156 // generate a new packet, if wise
1157
1158 if (!established)
1159 {
1160 if (vpn->dns_sndpq.empty ()) 1363 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 { 1364 {
1170 send = new dns_snd (this); 1365 send = new dns_snd (this);
1366
1367 cfg.reset (THISNODE->id);
1368 set_cfg ();
1369 send->gen_syn_req ();
1370 }
1371 }
1372 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1373 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1374 {
1375 if (last_sent + send_interval <= ev_now ())
1376 {
1377 //printf ("sending data request etc.\n"); //D
1378 if (!snddq.empty ())
1379 min_it (next, send_interval);
1380
1381 send = new dns_snd (this);
1171 send->gen_stream_req (sndseq, snddq); 1382 send->gen_stream_req (sndseq, snddq);
1383 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1384 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1172 1385
1173 sndseq = (sndseq + 1) & SEQNO_MASK; 1386 sndseq = (sndseq + 1) & SEQNO_MASK;
1174 } 1387 }
1175 1388 else
1176 if (send) 1389 min_it (next, last_sent + send_interval - ev_now ());
1177 vpn->dns_sndpq.push_back (send);
1178 } 1390 }
1179 1391
1180 if (send) 1392 if (send)
1181 { 1393 vpn->dns_sndpq.push_back (send);
1182 printf ("send pkt\n"); 1394 }
1183 last_sent = NOW;
1184 1395
1185 if (!send->retry) 1396 if (send)
1186 send->sent = NOW; 1397 {
1187 1398 last_sent = ev_now ();
1188 sendto (vpn->dnsv4_fd, 1399 sendto (vpn->dnsv4_fd,
1189 send->pkt->at (0), send->pkt->len, 0, 1400 send->pkt->at (0), send->pkt->len, 0,
1190 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1401 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1191 }
1192 } 1402 }
1193 else
1194 NEXT (last_sent + send_interval);
1195 1403
1196 printf ("pi %f si %f N %f (%d:%d)\n", poll_interval, send_interval, next - NOW, vpn->dns_sndpq.size (), snddq.size ()); 1404 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1405
1406 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1407 poll_interval, send_interval, next - ev_now (),
1408 vpn->dns_sndpq.size (), snddq.size (),
1409 rcvpq.size ());
1197 1410
1198 w.start (next); 1411 w.start (next);
1199} 1412}
1200 1413
1201#endif 1414#endif

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