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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.9 by pcg, Fri Mar 4 04:52:38 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_RETRY 1. 64#define MIN_POLL_INTERVAL 0.1 // poll at most this often when no data received
49#define MAX_RETRY 6. 65#define MAX_POLL_INTERVAL 1. // how often to poll minimally when the server has no data
50 66
51#define MAX_OUTSTANDING 400 // max. outstanding requests 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
69
70#define MAX_SEND_INTERVAL 2. // optimistic?
71
52#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
53#define MAX_RATE 100 // requests/s
54#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
55 74
56#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
57// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
58// every two request byte sless give room for one reply byte 77// every request byte less give room for two reply bytes
59 78
60#define SEQNO_MASK 0xffff 79#define SEQNO_MASK 0x3fff
61#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
62 81
63#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
64#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
65 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
66#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
67#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
68#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
92
93#define CMD_IP_1 207
94#define CMD_IP_2 46
95#define CMD_IP_3 236
96
97#define CMD_IP_RST 29 // some error, reset and retry
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}
69 113
70// works for cmaps up to 255 (not 256!) 114// works for cmaps up to 255 (not 256!)
71struct charmap 115struct charmap
72{ 116{
73 enum { INVALID = (u8)255 }; 117 enum { INVALID = (u8)255 };
… …
87 memset (enc, (char) 0, 256); 131 memset (enc, (char) 0, 256);
88 memset (dec, (char)INVALID, 256); 132 memset (dec, (char)INVALID, 256);
89 133
90 for (size = 0; cmap [size]; size++) 134 for (size = 0; cmap [size]; size++)
91 { 135 {
136 char c = cmap [size];
137
92 enc [size] = cmap [size]; 138 enc [size] = c;
93 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;
94 } 144 }
95 145
96 assert (size < 256); 146 assert (size < 256);
97} 147}
98 148
… …
105{ 155{
106 charmap cmap; 156 charmap cmap;
107 unsigned int enc_len [MAX_DEC_LEN]; 157 unsigned int enc_len [MAX_DEC_LEN];
108 unsigned int dec_len [MAX_ENC_LEN]; 158 unsigned int dec_len [MAX_ENC_LEN];
109 159
110 unsigned int encode_len (unsigned int len); 160 unsigned int encode_len (unsigned int len) const;
111 unsigned int decode_len (unsigned int len); 161 unsigned int decode_len (unsigned int len) const;
112 162
113 unsigned int encode (char *dst, u8 *src, unsigned int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
114 unsigned int decode (u8 *dst, char *src, unsigned int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
115 165
116 basecoder (const char *cmap); 166 basecoder (const char *cmap);
117}; 167};
118 168
119basecoder::basecoder (const char *cmap) 169basecoder::basecoder (const char *cmap)
… …
138 enc_len [len] = n; 188 enc_len [len] = n;
139 dec_len [n] = len; 189 dec_len [n] = len;
140 } 190 }
141} 191}
142 192
193unsigned int
143unsigned int basecoder::encode_len (unsigned int len) 194basecoder::encode_len (unsigned int len) const
144{ 195{
145 return enc_len [len]; 196 return enc_len [len];
146} 197}
147 198
199unsigned int
148unsigned int basecoder::decode_len (unsigned int len) 200basecoder::decode_len (unsigned int len) const
149{ 201{
150 while (len && !dec_len [len]) 202 while (len && !dec_len [len])
151 --len; 203 --len;
152 204
153 return dec_len [len]; 205 return dec_len [len];
154} 206}
155 207
208unsigned int
156unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 209basecoder::encode (char *dst, u8 *src, unsigned int len) const
157{ 210{
158 if (!len) 211 if (!len || len > MAX_DEC_LEN)
159 return 0; 212 return 0;
160 213
161 int elen = encode_len (len); 214 int elen = encode_len (len);
162 215
163 mp_limb_t m [MAX_LIMBS]; 216 mp_limb_t m [MAX_LIMBS];
… …
180 *dst++ = cmap.encode [dst_ [i]]; 233 *dst++ = cmap.encode [dst_ [i]];
181 234
182 return elen; 235 return elen;
183} 236}
184 237
238unsigned int
185unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 239basecoder::decode (u8 *dst, char *src, unsigned int len) const
186{ 240{
187 if (!len) 241 if (!len || len > MAX_ENC_LEN)
188 return 0; 242 return 0;
189 243
190 u8 src_ [MAX_ENC_LEN]; 244 u8 src_ [MAX_ENC_LEN];
191 unsigned int elen = 0; 245 unsigned int elen = 0;
192 246
… …
239 } 293 }
240 abort (); 294 abort ();
241} 295}
242#endif 296#endif
243 297
244// the following sequence has been crafted to
245// a) look somewhat random
246// b) the even (and odd) indices never share the same character as upper/lowercase
247// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)
248// the other sequences are obviously derived
249//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
250static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
251//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet 299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
252static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
253 301
254///////////////////////////////////////////////////////////////////////////// 302/////////////////////////////////////////////////////////////////////////////
255 303
256#define HDRSIZE 6 304#define HDRSIZE 5
257 305
306inline void
258inline void encode_header (char *data, int clientid, int seqno) 307encode_header (char *data, int clientid, int seqno, int retry = 0)
259{ 308{
260 u8 hdr[3] = { clientid, seqno >> 8, seqno };
261
262 assert (clientid < 256); 309 assert (clientid < 256);
263 310
311 seqno &= SEQNO_MASK;
312
313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
316 clientid,
317 };
318
264 cdc26.encode (data, hdr, 3); 319 cdc36.encode (data, hdr, 3);
265} 320}
266 321
322inline void
267inline void decode_header (char *data, int &clientid, int &seqno) 323decode_header (char *data, int &clientid, int &seqno)
268{ 324{
269 u8 hdr[3]; 325 u8 hdr[3];
270 326
271 cdc26.decode (hdr, data, HDRSIZE); 327 cdc36.decode (hdr, data, HDRSIZE);
272 328
273 clientid = hdr[0]; 329 clientid = hdr[2];
274 seqno = (hdr[1] << 8) | hdr[2]; 330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
275} 331}
276 332
277///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
278 334
279struct byte_stream 335struct byte_stream
… …
305byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
306{ 362{
307 delete data; 363 delete data;
308} 364}
309 365
366void
310void byte_stream::remove (int count) 367byte_stream::remove (int count)
311{ 368{
312 if (count > fill) 369 if (count > fill)
313 abort (); 370 assert (count <= fill);
314 371
315 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
316} 373}
317 374
375bool
318bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
319{ 377{
320 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
321 return false; 379 return false;
322 380
323 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
324 382
325 return true; 383 return true;
326} 384}
327 385
386bool
328bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
329{ 388{
330 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
331 return false; 390 return false;
332 391
333 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
334 data [fill++] = pkt->len; 393 data [fill++] = pkt->len;
335 394
336 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 395 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
337 396
338 return true; 397 return true;
339} 398}
340 399
341vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
342{ 401{
402 unsigned int len;
403
404 for (;;)
405 {
343 int len = (data [0] << 8) | data [1]; 406 len = (data [0] << 8) | data [1];
344 407
345 if (len > MAXSIZE && fill >= 2) 408 if (len <= MAXSIZE || fill < 2)
346 abort (); // TODO handle this gracefully, connection reset 409 break;
347 410
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
348 if (fill < len + 2) 416 if (fill < len + 2)
349 return 0; 417 return 0;
350 418
351 vpn_packet *pkt = new vpn_packet; 419 vpn_packet *pkt = new vpn_packet;
352 420
353 pkt->len = len; 421 pkt->len = len;
354 memcpy (&((*pkt)[0]), data + 2, len); 422 memcpy (pkt->at (0), data + 2, len);
355 remove (len + 2); 423 remove (len + 2);
356 424
357 return pkt; 425 return pkt;
358} 426}
359 427
… …
376#define FLAG_RCODE_REFUSED ( 5 << 0) 444#define FLAG_RCODE_REFUSED ( 5 << 0)
377 445
378#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 446#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
379#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) 447#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
380 448
449struct dns_cfg
450{
451 static int next_uid;
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
461 u8 id1, id2, id3, id4;
462
463 u16 client;
464 u8 def_ttl;
465 u8 r0;
466
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;
473
474 void reset (int clientid);
475 bool valid ();
476 u8 get_chksum ();
477};
478
479int dns_cfg::next_uid;
480
481void
482dns_cfg::reset (int clientid)
483{
484 // this ID must result in some mixed-case characters in cdc26-encoding
485 id1 = 'G';
486 id2 = 'V';
487 id3 = 'P';
488 id4 = 'E';
489
490 version = 2;
491
492 rrtype = RR_TYPE_TXT;
493 flags = 0;
494 def_ttl = 0;
495 syn_cdc = 26;
496 hdr_cdc = 36;
497 req_cdc = conf.dns_case_preserving ? 62 : 36;
498 rep_cdc = 0;
499 max_size = htons (MAX_PKT_SIZE);
500 client = htons (clientid);
501 uid = ++next_uid;
502
503 r0 = r1 = r2 = r3 = r4 = 0;
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
526dns_cfg::valid ()
527{
528 // although the protocol itself allows for some configurability,
529 // only the following encoding/decoding settings are implemented.
530 return id1 == 'G'
531 && id2 == 'V'
532 && id3 == 'P'
533 && id4 == 'E'
534 && version == 2
535 && syn_cdc == 26
536 && hdr_cdc == 36
537 && (req_cdc == 36 || req_cdc == 62)
538 && rep_cdc == 0
539 && chksum == get_chksum ();
540}
541
381struct dns_packet : net_packet 542struct dns_packet : net_packet
382{ 543{
383 u16 id; 544 u16 id;
384 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
385 u16 qdcount, ancount, nscount, arcount; 546 u16 qdcount, ancount, nscount, arcount;
386 547
387 u8 data[MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
388 549
389 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
390}; 551};
391 552
553int
392int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
393{ 555{
394 char *orig = data; 556 char *orig = data;
395 557
396 memset (data, 0, size); 558 memset (data, 0, size);
397 559
… …
423 return data - orig; 585 return data - orig;
424} 586}
425 587
426///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
427 589
428struct dns_req 590static
591u16 next_id ()
429{ 592{
430 dns_packet *pkt;
431 tstamp next;
432 int retry;
433 struct dns_connection *dns;
434 int seqno;
435
436 dns_req (dns_connection *dns);
437 void gen_stream_req (int seqno, byte_stream &stream);
438};
439
440static u16 dns_id = 12098; // TODO: should be per-vpn 593 static u16 dns_id = 0; // TODO: should be per-vpn
441 594
442static u16 next_id () 595 if (!dns_id)
443{ 596 dns_id = time (0);
597
444 // the simplest lsfr with periodicity 65535 i could find 598 // the simplest lsfr with periodicity 65535 i could find
445 dns_id = (dns_id << 1) 599 dns_id = (dns_id << 1)
446 | (((dns_id >> 1) 600 | (((dns_id >> 1)
447 ^ (dns_id >> 2) 601 ^ (dns_id >> 2)
448 ^ (dns_id >> 4) 602 ^ (dns_id >> 4)
449 ^ (dns_id >> 15)) & 1); 603 ^ (dns_id >> 15)) & 1);
450 604
451 return dns_id; 605 return dns_id;
452} 606}
453 607
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
454dns_req::dns_req (dns_connection *dns) 657dns_snd::dns_snd (dns_connection *dns)
455: dns (dns) 658: dns (dns)
456{ 659{
457 next = 0; 660 timeout = 0;
458 retry = 0; 661 retry = 0;
662 seqno = 0;
663 sent = ev_now ();
664 stdhdr = false;
459 665
460 pkt = new dns_packet; 666 pkt = new dns_packet;
461 667
462 pkt->id = next_id (); 668 pkt->id = next_id ();
463} 669}
464 670
671dns_snd::~dns_snd ()
672{
673 delete pkt;
674}
675
676static void
677append_domain (dns_packet &pkt, int &offs, const char *domain)
678{
679 // add tunnel domain
680 for (;;)
681 {
682 const char *end = strchr (domain, '.');
683
684 if (!end)
685 end = domain + strlen (domain);
686
687 int len = end - domain;
688
689 pkt [offs++] = len;
690 memcpy (pkt.at (offs), domain, len);
691 offs += len;
692
693 if (!*end)
694 break;
695
696 domain = end + 1;
697 }
698}
699
700void
465void dns_req::gen_stream_req (int seqno, byte_stream &stream) 701dns_snd::gen_stream_req (int seqno, byte_stream &stream)
466{ 702{
703 stdhdr = true;
467 this->seqno = seqno; 704 this->seqno = seqno;
705
706 timeout = ev_now () + INITIAL_TIMEOUT;
468 707
469 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 708 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
470 pkt->qdcount = htons (1); 709 pkt->qdcount = htons (1);
471 710
472 int offs = 6*2; 711 int offs = 6*2;
473 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 712 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
474 // 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,
475 // 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
476 715
477 char enc[256], *encp = enc; 716 char enc[256], *encp = enc;
478 encode_header (enc, THISNODE->id, seqno); 717 encode_header (enc, THISNODE->id, seqno);
479 718
480 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);
481 720
482 if (datalen > stream.size ()) 721 if (datalen > stream.size ())
483 datalen = stream.size (); 722 datalen = stream.size ();
484 723
485 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; 724 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
486 stream.remove (datalen); 725 stream.remove (datalen);
487 726
488 while (enclen) 727 while (enclen)
489 { 728 {
490 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 729 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
… …
496 encp += lbllen; 735 encp += lbllen;
497 736
498 enclen -= lbllen; 737 enclen -= lbllen;
499 } 738 }
500 739
501 const char *suffix = THISNODE->domain; 740 append_domain (*pkt, offs, dns->c->conf->domain);
502
503 // add tunnel domain
504 for (;;)
505 {
506 const char *end = strchr (suffix, '.');
507
508 if (!end)
509 end = suffix + strlen (suffix);
510
511 int len = end - suffix;
512
513 (*pkt)[offs++] = len;
514 memcpy (&((*pkt)[offs]), suffix, len);
515 offs += len;
516
517 if (!*end)
518 break;
519
520 suffix = end + 1;
521 }
522 741
523 (*pkt)[offs++] = 0; 742 (*pkt)[offs++] = 0;
524 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 743 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
744 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
745
746 pkt->len = offs;
747}
748
749void
750dns_snd::gen_syn_req ()
751{
752 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
753
754 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
755 pkt->qdcount = htons (1);
756
757 int offs = 6 * 2;
758
759 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
760
761 assert (elen <= MAX_LBL_SIZE);
762
763 (*pkt)[offs] = elen;
764 offs += elen + 1;
765 append_domain (*pkt, offs, dns->c->conf->domain);
766
767 (*pkt)[offs++] = 0;
768 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
525 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 769 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
526 770
527 pkt->len = offs; 771 pkt->len = offs;
528} 772}
529 773
… …
549 delete pkt; 793 delete pkt;
550} 794}
551 795
552///////////////////////////////////////////////////////////////////////////// 796/////////////////////////////////////////////////////////////////////////////
553 797
554struct dns_connection
555{
556 connection *c;
557 struct vpn *vpn;
558
559 vector<dns_rcv *> rcvpq;
560
561 int rcvseq;
562 int sndseq;
563
564 byte_stream rcvdq;
565 byte_stream snddq;
566
567 void time_cb (time_watcher &w); time_watcher tw;
568 void receive_rep (dns_rcv *r);
569
570 dns_connection (connection *c);
571 ~dns_connection ();
572};
573
574dns_connection::dns_connection (connection *c) 798dns_connection::dns_connection (connection *c)
575: c (c) 799: c (c)
576, rcvdq (MAX_BACKLOG * 2) 800, rcvdq (MAX_BACKLOG * 2)
577, snddq (MAX_BACKLOG * 2) 801, snddq (MAX_BACKLOG)
578, tw (this, &dns_connection::time_cb)
579{ 802{
803 tw.set<dns_connection, &dns_connection::time_cb> (this);
804
580 vpn = c->vpn; 805 vpn = c->vpn;
581 806
582 rcvseq = sndseq = 0; 807 reset ();
583} 808}
584 809
585dns_connection::~dns_connection () 810dns_connection::~dns_connection ()
586{ 811{
587 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 812 reset ();
588 i != rcvpq.end ();
589 ++i)
590 delete *i;
591} 813}
592 814
593struct dns_cfg 815void
816dns_connection::reset ()
594{ 817{
595 u8 id1, id2, id3; 818 while (!rcvpq.empty ())
596 u8 def_ttl; 819 {
597 u8 unused1; 820 delete rcvpq.back ();
598 u16 max_size; 821 rcvpq.pop_back ();
599 u8 flags1, flags2; 822 }
600};
601 823
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
831 established = false;
832
833 rcvseq = repseq = sndseq = 0;
834
835 last_sent = last_received = 0;
836 poll_interval = 0.5; // starting here
837 send_interval = 0.5; // starting rate
838 min_latency = INITIAL_TIMEOUT;
839}
840
841void
842dns_connection::set_cfg ()
843{
844 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
845}
846
847void
602void dns_connection::receive_rep (dns_rcv *r) 848dns_connection::receive_rep (dns_rcv *r)
603{ 849{
850 if (r->datalen)
851 {
852 last_received = ev_now ();
853 tw ();
854
855 poll_interval = send_interval;
856 }
857 else
858 {
859 poll_interval *= 1.5;
860
861 if (poll_interval > MAX_POLL_INTERVAL)
862 poll_interval = MAX_POLL_INTERVAL;
863 }
864
604 rcvpq.push_back (r); 865 rcvpq.push_back (r);
605 866
606 redo: 867 redo:
607 868
608 // find next packet 869 // find next packet
609 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 870 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
610 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 871 if (SEQNO_EQ (rcvseq, (*i)->seqno))
611 { 872 {
873 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
612 // enter the packet into our input stream 874 // enter the packet into our input stream
613 r = *i; 875 r = *i;
614 876
615 // remove the oldest packet, look forward, as it's oldest first 877 // remove the oldest packet, look forward, as it's oldest first
616 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)
617 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 879 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
618 { 880 {
881 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
619 delete *j; 882 delete *j;
620 rcvpq.erase (j); 883 rcvpq.erase (j);
621 break; 884 break;
622 } 885 }
623 886
624 rcvseq = (rcvseq + 1) & SEQNO_MASK; 887 rcvseq = (rcvseq + 1) & SEQNO_MASK;
625 888
626 if (!rcvdq.put (r->data, r->datalen)) 889 if (!rcvdq.put (r->data, r->datalen))
890 {
627 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 }
628 896
629 while (vpn_packet *pkt = rcvdq.get ()) 897 while (vpn_packet *pkt = rcvdq.get ())
630 { 898 {
631 sockinfo si; 899 sockinfo si;
632 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 900 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
633 901
634 vpn->recv_vpn_packet (pkt, si); 902 vpn->recv_vpn_packet (pkt, si);
903 delete pkt;
635 } 904 }
636 905
637 // check for further packets 906 // check for further packets
638 goto redo; 907 goto redo;
639 } 908 }
640} 909}
641 910
642dns_packet * 911void
643vpn::dnsv4_server (dns_packet *pkt) 912vpn::dnsv4_server (dns_packet &pkt)
644{ 913{
645 u16 flags = ntohs (pkt->flags); 914 u16 flags = ntohs (pkt.flags);
646 915
647 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
648 int offs = 6 * 2; // skip header 916 int offs = 6 * 2; // skip header
649 917
650 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 918 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
651 919
652 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 920 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
653 && pkt->qdcount == htons (1)) 921 && pkt.qdcount == htons (1))
654 { 922 {
655 char qname[MAXSIZE]; 923 char qname [MAXSIZE];
656 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 924 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
657 925
658 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 926 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
659 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 927 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
660 928
661 pkt->qdcount = htons (1); 929 pkt.qdcount = htons (1);
662 pkt->ancount = 0; 930 pkt.ancount = 0;
663 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
664 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
665 933
666 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 934 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
667 935
668 int dlen = strlen (THISNODE->domain); 936 int dlen = strlen (THISNODE->domain);
669 937
670 if (qclass == RR_CLASS_IN 938 if (qclass == RR_CLASS_IN
671 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
672 && qlen > dlen + 1 + HDRSIZE 939 && qlen > dlen + 1
673 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 940 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
674 { 941 {
675 // correct class, domain: parse 942 // now generate reply
676 int client, seqno; 943 pkt.ancount = htons (1); // one answer RR
677 decode_header (qname, client, seqno); 944 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
678 945
679 u8 data[MAXSIZE]; 946 if ((qtype == RR_TYPE_ANY
680 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); 947 || qtype == RR_TYPE_TXT
681 948 || qtype == RR_TYPE_NULL)
682 if (0 < client && client <= conns.size ()) 949 && qlen > dlen + 1 + HDRSIZE)
683 { 950 {
951 // correct class, domain: parse
952 int client, seqno;
953 decode_header (qname, client, seqno);
954
955 if (0 < client && client <= conns.size ())
956 {
684 connection *c = conns [client - 1]; 957 connection *c = conns [client - 1];
685
686 if (!c->dns)
687 c->dns = new dns_connection (c);
688
689 dns_connection *dns = c->dns; 958 dns_connection *dns = c->dns;
959 dns_rcv *rcv;
690 960
961 if (dns)
962 {
963 u8 data[MAXSIZE];
964 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
965
691 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 (); )
692 if (SEQNO_EQ ((*i)->seqno, seqno)) 967 if (SEQNO_EQ ((*i)->seqno, seqno))
968 {
969 // already seen that request: simply reply with the cached reply
970 dns_rcv *r = *i;
971
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;
977
978 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
979
980 goto duplicate_request;
981 }
982
983 // new packet, queue
984 rcv = new dns_rcv (seqno, data, datalen);
985 dns->receive_rep (rcv);
986 }
987
693 { 988 {
694 // already seen that request: simply reply with the cached reply 989 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
695 dns_rcv *r = *i;
696 990
697 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 991 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
992 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
993 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
994 pkt [offs++] = 0; pkt [offs++] = 0;
995 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
698 996
699 memcpy (pkt->at (0), r->pkt->at (0), offs = r->pkt->len); 997 int rdlen_offs = offs += 2;
700 pkt->id = r->pkt->id; 998
701 goto duplicate_request; 999 if (dns)
1000 {
1001 int dlen = ntohs (dns->cfg.max_size) - offs;
1002
1003 // bind doesn't compress well, so reduce further by one label length
1004 dlen -= qlen;
1005
1006 // only put data into in-order sequence packets, if
1007 // we receive out-of-order packets we generate 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)
1011 {
1012 dns->repseq = seqno;
1013
1014 while (dlen > 1 && !dns->snddq.empty ())
1015 {
1016 int txtlen = dlen <= 255 ? dlen - 1 : 255;
1017
1018 if (txtlen > dns->snddq.size ())
1019 txtlen = dns->snddq.size ();
1020
1021 pkt[offs++] = txtlen;
1022 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
1023 offs += txtlen;
1024 dns->snddq.remove (txtlen);
1025
1026 dlen -= txtlen + 1;
1027 }
1028 }
1029
1030 // avoid completely empty TXT rdata
1031 if (offs == rdlen_offs)
1032 pkt[offs++] = 0;
1033
1034 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
1035 }
1036 else
1037 {
1038 // send RST
1039 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1040 pkt [offs++] = CMD_IP_RST;
1041 }
1042
1043 int rdlen = offs - rdlen_offs;
1044
1045 pkt [rdlen_offs - 2] = rdlen >> 8;
1046 pkt [rdlen_offs - 1] = rdlen;
1047
1048 if (dns)
1049 {
1050 // now update dns_rcv copy
1051 rcv->pkt->len = offs;
1052 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
1053 }
702 } 1054 }
703 1055
704 // new packet, queue 1056 duplicate_request: ;
705 dns_rcv *rcv = new dns_rcv (seqno, data, datalen); 1057 }
706 dns->receive_rep (rcv); 1058 else
707
708 // now generate reply
709 pkt->ancount = htons (1); // one answer RR
710 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 1059 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
1060 }
1061 else if (qtype == RR_TYPE_A
1062 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
1063 {
1064 dns_cfg cfg;
1065 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
1066 int client = ntohs (cfg.client);
711 1067
712 (*pkt) [offs++] = 0xc0;
713 (*pkt) [offs++] = 6 * 2; // same as in query section 1068 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
714 1069
715 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1070 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
716 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1071 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
717
718 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1072 pkt [offs++] = 0; pkt [offs++] = 0;
719 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL 1073 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1074 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
720 1075
721 int dlen = MAX_PKT_SIZE - offs - 2; 1076 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1077 pkt [offs++] = CMD_IP_REJ;
722 1078
723 // bind doesn't compress well, so reduce further by one label length 1079 if (0 < client && client <= conns.size ())
724 dlen -= qlen;
725
726 int rdlen_offs = offs += 2;
727
728 while (dlen > 1 && !dns->snddq.empty ())
729 { 1080 {
730 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1081 connection *c = conns [client - 1];
731 1082
732 if (txtlen > dns->snddq.size ()) 1083 if (cfg.valid ())
733 txtlen = dns->snddq.size (); 1084 {
1085 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
734 1086
735 (*pkt)[offs++] = txtlen; 1087 // check for any encoding mismatches - hints at a case problem
736 memcpy (pkt->at (offs), dns->snddq.begin (), txtlen); 1088 char qname2 [MAX_ENC_LEN];
737 offs += txtlen; 1089 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
738 dns->snddq.remove (txtlen);
739 1090
740 dlen -= txtlen + 1; 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
1096 c->dns = new dns_connection (c);
1097 c->dns->cfg = cfg;
1098 c->dns->set_cfg ();
1099 }
741 } 1100 }
742
743 // avoid empty TXT rdata
744 if (offs == rdlen_offs)
745 (*pkt)[offs++] = 0;
746
747 int rdlen = offs - rdlen_offs;
748
749 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
750 (*pkt) [rdlen_offs - 1] = rdlen;
751
752 // now update dns_rcv copy
753 rcv->pkt->len = offs;
754 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
755
756 duplicate_request: ;
757 } 1101 }
758 else
759 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
760 } 1102 }
761 1103
762 pkt->len = offs; 1104 pkt.len = offs;
763 } 1105 }
764
765 return pkt;
766} 1106}
767 1107
768void 1108void
769vpn::dnsv4_client (dns_packet *pkt) 1109vpn::dnsv4_client (dns_packet &pkt)
770{ 1110{
771 u16 flags = ntohs (pkt->flags); 1111 u16 flags = ntohs (pkt.flags);
772 int offs = 6 * 2; // skip header 1112 int offs = 6 * 2; // skip header
773 1113
774 pkt->qdcount = ntohs (pkt->qdcount); 1114 pkt.qdcount = ntohs (pkt.qdcount);
775 pkt->ancount = ntohs (pkt->ancount); 1115 pkt.ancount = ntohs (pkt.ancount);
776 1116
777 // go through our request list and find the corresponding request 1117 // go through our request list and find the corresponding request
778 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1118 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
779 i != dns_sndpq.end (); 1119 i != dns_sndpq.end ();
780 ++i) 1120 ++i)
781 if ((*i)->pkt->id == pkt->id) 1121 if ((*i)->pkt->id == pkt.id)
782 { 1122 {
783 dns_connection *dns = (*i)->dns; 1123 dns_connection *dns = (*i)->dns;
1124 connection *c = dns->c;
784 int seqno = (*i)->seqno; 1125 int seqno = (*i)->seqno;
785 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;
1129
1130 if (back_off)
1131 {
1132 dns->send_interval *= 1.01;
1133 if (dns->send_interval > MAX_SEND_INTERVAL)
1134 dns->send_interval = MAX_SEND_INTERVAL;
1135 }
1136 else
1137 {
1138#if 0
1139 dns->send_interval *= 0.999;
1140#endif
1141 // the latency surely puts an upper bound on
1142 // the minimum send interval
1143 double latency = ev_now () - (*i)->sent;
1144
1145 if (latency < dns->min_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;
1153 }
786 1154
787 delete *i; 1155 delete *i;
788 dns_sndpq.erase (i); 1156 dns_sndpq.erase (i);
789 1157
790 if (flags & FLAG_RESPONSE && !(flags & (FLAG_OP_MASK | FLAG_TC))) 1158 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
791 { 1159 {
792 char qname[MAXSIZE]; 1160 char qname[MAXSIZE];
793 1161
794 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1162 while (pkt.qdcount-- && offs < MAXSIZE - 4)
795 { 1163 {
796 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1164 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
797 offs += 4; // skip qtype, qclass 1165 offs += 4; // skip qtype, qclass
798 } 1166 }
799 1167
800 while (pkt->ancount-- && offs < MAXSIZE - 10 && datap) 1168 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
801 { 1169 {
802 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1170 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
803 1171
804 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1172 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
805 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1173 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
806 u32 ttl = (*pkt) [offs++] << 24; 1174 u32 ttl = pkt [offs++] << 24;
807 ttl |= (*pkt) [offs++] << 16; 1175 ttl |= pkt [offs++] << 16;
808 ttl |= (*pkt) [offs++] << 8; 1176 ttl |= pkt [offs++] << 8;
809 ttl |= (*pkt) [offs++]; 1177 ttl |= pkt [offs++];
810
811 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1178 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
812 1179
813 if (rdlen <= MAXSIZE - offs) 1180 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
814 { 1181 {
815 // decode bytes, finally 1182 if (rdlen <= MAXSIZE - offs)
816
817 while (rdlen)
818 { 1183 {
1184 // decode bytes, finally
1185
1186 while (rdlen)
1187 {
819 int txtlen = (*pkt) [offs++]; 1188 int txtlen = pkt [offs++];
820 1189
821 assert (txtlen + offs < MAXSIZE - 1); 1190 assert (txtlen + offs < MAXSIZE - 1);
822 1191
823 memcpy (datap, pkt->at (offs), txtlen); 1192 memcpy (datap, pkt.at (offs), txtlen);
824 datap += txtlen; offs += txtlen; 1193 datap += txtlen; offs += txtlen;
825 1194
826 rdlen -= txtlen + 1; 1195 rdlen -= txtlen + 1;
1196 }
827 } 1197 }
828 } 1198 }
1199 else if (qtype == RR_TYPE_A)
1200 {
1201 u8 ip [4];
1202
1203 ip [0] = pkt [offs++];
1204 ip [1] = pkt [offs++];
1205 ip [2] = pkt [offs++];
1206 ip [3] = pkt [offs++];
1207
1208 if (ip [0] == CMD_IP_1
1209 && ip [1] == CMD_IP_2
1210 && ip [2] == CMD_IP_3)
1211 {
1212 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1213
1214 if (ip [3] == CMD_IP_RST)
1215 {
1216 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1217
1218 dns->reset ();
1219 return;
1220 }
1221 else if (ip [3] == CMD_IP_SYN)
1222 {
1223 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
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 }
1240 }
1241 else if (ip [3] == CMD_IP_REJ)
1242 {
1243 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1244 dns->tw.start (60.);
1245 }
1246 else
1247 {
1248 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1249 dns->tw.start (60.);
1250 }
1251 }
1252 else
1253 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1254 ip [0], ip [1], ip [2], ip [3]);
1255
1256 return;
1257 }
829 1258
830 int client, rseqno; 1259 int client, rseqno;
831 decode_header (qname, client, rseqno); 1260 decode_header (qname, client, rseqno);
832 1261
833 if (client != THISNODE->id) 1262 if (client != THISNODE->id)
834 { 1263 {
835 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1264 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
836 datap = 0; 1265 datap = 0;
837 } 1266 }
838 else if (rseqno != seqno) 1267 else if (rseqno != seqno)
839 { 1268 {
840 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?"));
841 datap = 0; 1270 datap = 0;
842 } 1271 }
843 } 1272 }
844 } 1273 }
845 1274
846 // todo: pkt now used 1275 // todo: pkt now used
847 if (datap) 1276 if (datap)
848 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 }
849 1288
850 break; 1289 break;
851 } 1290 }
852
853 delete pkt;
854} 1291}
855 1292
856void 1293void
857vpn::dnsv4_ev (io_watcher &w, short revents) 1294vpn::dnsv4_ev (ev::io &w, int revents)
858{ 1295{
859 if (revents & EVENT_READ) 1296 if (revents & EV_READ)
860 { 1297 {
861 dns_packet *pkt = new dns_packet; 1298 dns_packet *pkt = new dns_packet;
862 struct sockaddr_in sa; 1299 struct sockaddr_in sa;
863 socklen_t sa_len = sizeof (sa); 1300 socklen_t sa_len = sizeof (sa);
864 1301
865 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1302 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
866 1303
867 if (pkt->len > 0) 1304 if (pkt->len > 0)
868 { 1305 {
869 if (pkt->flags & htons (FLAG_TC)) 1306 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1307 dnsv4_client (*pkt);
1308 else
870 { 1309 {
871 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1310 dnsv4_server (*pkt);
872 //TODO connection reset 1311 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
873 } 1312 }
874 1313
875 if (THISNODE->dns_port) 1314 delete pkt;
876 {
877 pkt = dnsv4_server (pkt);
878 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
879 }
880 else
881 dnsv4_client (pkt);
882 } 1315 }
883 } 1316 }
884} 1317}
885 1318
886bool 1319bool
887connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1320vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
888{ 1321{
1322 int client = ntohl (si.host);
1323
1324 assert (0 < client && client <= conns.size ());
1325
1326 connection *c = conns [client - 1];
1327
889 if (!dns) 1328 if (!c->dns)
890 dns = new dns_connection (this); 1329 c->dns = new dns_connection (c);
891 1330
892 if (!dns->snddq.put (pkt)) 1331 if (c->dns->snddq.put (pkt))
893 return false; 1332 c->dns->tw ();
894 1333
895 // start timer if neccessary 1334 // always return true even if the buffer overflows
896 if (!THISNODE->dns_port && !dns->tw.active)
897 dns->tw.trigger ();
898
899 return true; 1335 return true;
900} 1336}
901 1337
1338#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1339
902void 1340void
903dns_connection::time_cb (time_watcher &w) 1341dns_connection::time_cb (ev::timer &w, int revents)
904{ 1342{
1343 // servers have to be polled
1344 if (THISNODE->dns_port)
1345 return;
1346
905 // check for timeouts and (re)transmit 1347 // check for timeouts and (re)transmit
906 tstamp next = NOW + 60; 1348 tstamp next = ev::now () + poll_interval;
907 dns_req *send = 0; 1349 dns_snd *send = 0;
908 1350
909 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1351 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
910 i != vpn->dns_sndpq.end (); 1352 i != vpn->dns_sndpq.end ();
911 ++i) 1353 ++i)
912 { 1354 {
913 dns_req *r = *i; 1355 dns_snd *r = *i;
914 1356
915 if (r->next <= NOW) 1357 if (r->timeout <= ev_now ())
916 { 1358 {
917 if (!send) 1359 if (!send)
918 { 1360 {
919 send = r; 1361 send = r;
920 1362
921 if (r->retry)//D
922 printf ("req %d:%d, retry %d\n", r->seqno, r->pkt->id, r->retry);
923 r->retry++; 1363 r->retry++;
924 r->next = 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);
925 } 1371 }
926 } 1372 }
927 1373 else
928 if (r->next < next) 1374 NEXT (r->timeout);
929 next = r->next;
930 } 1375 }
931 1376
932 if (!send 1377 if (!send)
933 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
934 { 1378 {
1379 // generate a new packet, if wise
1380
1381 if (!established)
1382 {
1383 if (vpn->dns_sndpq.empty ())
1384 {
935 send = new dns_req (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);
936 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
1408
1409 sndseq = (sndseq + 1) & SEQNO_MASK;
1410 }
1411 else
1412 NEXT (last_sent + send_interval);
1413 }
1414
1415 if (send)
937 vpn->dns_sndpq.push_back (send); 1416 vpn->dns_sndpq.push_back (send);
938
939 sndseq = (sndseq + 1) & SEQNO_MASK;
940 } 1417 }
941
942 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
943 1418
944 if (send) 1419 if (send)
945 { 1420 {
946 dns_packet *pkt = send->pkt; 1421 last_sent = ev_now ();
947 1422 sendto (vpn->dnsv4_fd,
948 next = min_next; 1423 send->pkt->at (0), send->pkt->len, 0,
949
950 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0,
951 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1424 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
952 } 1425 }
953 else if (next < min_next)
954 next = min_next;
955 1426
956 w.start (next); 1427 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1428 poll_interval, send_interval, next - ev_now (),
1429 vpn->dns_sndpq.size (), snddq.size (),
1430 rcvpq.size ());
1431
1432 // TODO: no idea when this happens, but when next < ev_now (), we have a problem
1433 // doesn't seem to happen anymore
1434 if (next < ev_now () + 0.001)
1435 next = ev_now () + 0.1;
1436
1437 w.start (next - ev_now ());
957} 1438}
958 1439
959#endif 1440#endif
960 1441

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