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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.8 by pcg, Fri Mar 4 03:43:09 2005 UTC vs.
Revision 1.53 by root, Tue Oct 18 10:54:17 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 0.025 // poll at most this often when no data received
49#define MAX_RETRY 60. 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 5. // 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 10000 // 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 235 // 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// seqno has 12 bits (3 bytes a 4 bits in the header)
61#define SEQNO_MASK 0x7fff 79#define SEQNO_MASK 0x3fff
62#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
63 81
64#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
65#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
66 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
67#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
68#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
69#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}
70 113
71// works for cmaps up to 255 (not 256!) 114// works for cmaps up to 255 (not 256!)
72struct charmap 115struct charmap
73{ 116{
74 enum { INVALID = (u8)255 }; 117 enum { INVALID = (u8)255 };
… …
88 memset (enc, (char) 0, 256); 131 memset (enc, (char) 0, 256);
89 memset (dec, (char)INVALID, 256); 132 memset (dec, (char)INVALID, 256);
90 133
91 for (size = 0; cmap [size]; size++) 134 for (size = 0; cmap [size]; size++)
92 { 135 {
136 char c = cmap [size];
137
93 enc [size] = cmap [size]; 138 enc [size] = c;
94 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;
95 } 144 }
96 145
97 assert (size < 256); 146 assert (size < 256);
98} 147}
99 148
… …
106{ 155{
107 charmap cmap; 156 charmap cmap;
108 unsigned int enc_len [MAX_DEC_LEN]; 157 unsigned int enc_len [MAX_DEC_LEN];
109 unsigned int dec_len [MAX_ENC_LEN]; 158 unsigned int dec_len [MAX_ENC_LEN];
110 159
111 unsigned int encode_len (unsigned int len); 160 unsigned int encode_len (unsigned int len) const;
112 unsigned int decode_len (unsigned int len); 161 unsigned int decode_len (unsigned int len) const;
113 162
114 unsigned int encode (char *dst, u8 *src, unsigned int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
115 unsigned int decode (u8 *dst, char *src, unsigned int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
116 165
117 basecoder (const char *cmap); 166 basecoder (const char *cmap);
118}; 167};
119 168
120basecoder::basecoder (const char *cmap) 169basecoder::basecoder (const char *cmap)
… …
139 enc_len [len] = n; 188 enc_len [len] = n;
140 dec_len [n] = len; 189 dec_len [n] = len;
141 } 190 }
142} 191}
143 192
193unsigned int
144unsigned int basecoder::encode_len (unsigned int len) 194basecoder::encode_len (unsigned int len) const
145{ 195{
146 return enc_len [len]; 196 return enc_len [len];
147} 197}
148 198
199unsigned int
149unsigned int basecoder::decode_len (unsigned int len) 200basecoder::decode_len (unsigned int len) const
150{ 201{
151 while (len && !dec_len [len]) 202 while (len && !dec_len [len])
152 --len; 203 --len;
153 204
154 return dec_len [len]; 205 return dec_len [len];
155} 206}
156 207
208unsigned int
157unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) 209basecoder::encode (char *dst, u8 *src, unsigned int len) const
158{ 210{
159 if (!len) 211 if (!len || len > MAX_DEC_LEN)
160 return 0; 212 return 0;
161 213
162 int elen = encode_len (len); 214 int elen = encode_len (len);
163 215
164 mp_limb_t m [MAX_LIMBS]; 216 mp_limb_t m [MAX_LIMBS];
… …
181 *dst++ = cmap.encode [dst_ [i]]; 233 *dst++ = cmap.encode [dst_ [i]];
182 234
183 return elen; 235 return elen;
184} 236}
185 237
238unsigned int
186unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) 239basecoder::decode (u8 *dst, char *src, unsigned int len) const
187{ 240{
188 if (!len) 241 if (!len || len > MAX_ENC_LEN)
189 return 0; 242 return 0;
190 243
191 u8 src_ [MAX_ENC_LEN]; 244 u8 src_ [MAX_ENC_LEN];
192 unsigned int elen = 0; 245 unsigned int elen = 0;
193 246
… …
240 } 293 }
241 abort (); 294 abort ();
242} 295}
243#endif 296#endif
244 297
245// the following sequence has been crafted to
246// a) look somewhat random
247// b) the even (and odd) indices never share the same character as upper/lowercase
248// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)
249// the other sequences are obviously derived
250//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
251static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
252//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet 299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
253static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
254 301
255///////////////////////////////////////////////////////////////////////////// 302/////////////////////////////////////////////////////////////////////////////
256 303
257#define HDRSIZE 6 304#define HDRSIZE 5
258 305
306inline void
259inline void encode_header (char *data, int clientid, int seqno) 307encode_header (char *data, int clientid, int seqno, int retry = 0)
260{ 308{
261 u8 hdr[3] = { clientid, seqno >> 8, seqno };
262
263 assert (clientid < 256); 309 assert (clientid < 256);
264 310
311 seqno &= SEQNO_MASK;
312
313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
316 clientid,
317 };
318
265 cdc26.encode (data, hdr, 3); 319 cdc36.encode (data, hdr, 3);
266} 320}
267 321
322inline void
268inline void decode_header (char *data, int &clientid, int &seqno) 323decode_header (char *data, int &clientid, int &seqno)
269{ 324{
270 u8 hdr[3]; 325 u8 hdr[3];
271 326
272 cdc26.decode (hdr, data, HDRSIZE); 327 cdc36.decode (hdr, data, HDRSIZE);
273 328
274 printf ("DEC %02x %02x %02x %02x\n", hdr[0], hdr[1], hdr[2], hdr[3]);
275
276 clientid = hdr[0]; 329 clientid = hdr[2];
277 seqno = (hdr[1] << 8) | hdr[2]; 330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
278} 331}
279 332
280///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
281 334
282struct byte_stream 335struct byte_stream
… …
308byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
309{ 362{
310 delete data; 363 delete data;
311} 364}
312 365
366void
313void byte_stream::remove (int count) 367byte_stream::remove (int count)
314{ 368{
315 if (count > fill) 369 if (count > fill)
316 abort (); 370 assert (count <= fill);
317 371
318 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
319} 373}
320 374
375bool
321bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
322{ 377{
323 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
324 return false; 379 return false;
325 380
326 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
327 382
328 return true; 383 return true;
329} 384}
330 385
386bool
331bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
332{ 388{
333 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
334 return false; 390 return false;
335 391
336 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
337 data [fill++] = pkt->len; 393 data [fill++] = pkt->len;
338 394
339 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 395 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
340 396
341 return true; 397 return true;
342} 398}
343 399
344vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
345{ 401{
402 unsigned int len;
403
404 for (;;)
405 {
346 int len = (data [0] << 8) | data [1]; 406 len = (data [0] << 8) | data [1];
347 407
348 if (len > MAXSIZE && fill >= 2) 408 if (len <= MAXSIZE || fill < 2)
349 abort (); // TODO handle this gracefully, connection reset 409 break;
350 410
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
351 if (fill < len + 2) 416 if (fill < len + 2)
352 return 0; 417 return 0;
353 418
354 vpn_packet *pkt = new vpn_packet; 419 vpn_packet *pkt = new vpn_packet;
355 420
356 pkt->len = len; 421 pkt->len = len;
357 memcpy (&((*pkt)[0]), data + 2, len); 422 memcpy (pkt->at (0), data + 2, len);
358 remove (len + 2); 423 remove (len + 2);
359 424
360 return pkt; 425 return pkt;
361} 426}
362 427
363///////////////////////////////////////////////////////////////////////////// 428/////////////////////////////////////////////////////////////////////////////
364 429
365#define FLAG_QUERY ( 0 << 15) 430#define FLAG_QUERY ( 0 << 15)
366#define FLAG_RESPONSE ( 1 << 15) 431#define FLAG_RESPONSE ( 1 << 15)
367#define FLAG_OP_MASK (15 << 14) 432#define FLAG_OP_MASK (15 << 11)
368#define FLAG_OP_QUERY ( 0 << 11) 433#define FLAG_OP_QUERY ( 0 << 11)
369#define FLAG_AA ( 1 << 10) 434#define FLAG_AA ( 1 << 10)
370#define FLAG_TC ( 1 << 9) 435#define FLAG_TC ( 1 << 9)
371#define FLAG_RD ( 1 << 8) 436#define FLAG_RD ( 1 << 8)
372#define FLAG_RA ( 1 << 7) 437#define FLAG_RA ( 1 << 7)
… …
379#define FLAG_RCODE_REFUSED ( 5 << 0) 444#define FLAG_RCODE_REFUSED ( 5 << 0)
380 445
381#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 446#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
382#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)
383 448
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
384struct dns_packet : net_packet 542struct dns_packet : net_packet
385{ 543{
386 u16 id; 544 u16 id;
387 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
388 u16 qdcount, ancount, nscount, arcount; 546 u16 qdcount, ancount, nscount, arcount;
389 547
390 u8 data[MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
391 549
392 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
393}; 551};
394 552
553int
395int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
396{ 555{
397 char *orig = data; 556 char *orig = data;
398 557
399 memset (data, 0, size); 558 memset (data, 0, size);
400 559
… …
426 return data - orig; 585 return data - orig;
427} 586}
428 587
429///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
430 589
431struct dns_req 590static
591u16 next_id ()
432{ 592{
433 dns_packet *pkt;
434 tstamp next;
435 int retry;
436 connection *conn;
437 int seqno;
438
439 dns_req (connection *c);
440 void gen_stream_req (int seqno, byte_stream *stream);
441};
442
443static u16 dns_id = 12098; // TODO: should be per-vpn 593 static u16 dns_id = 0; // TODO: should be per-vpn
444 594
445static u16 next_id () 595#if 1
446{ 596 if (!dns_id)
597 dns_id = time (0);
598
447 // the simplest lsfr with periodicity 65535 i could find 599 // the simplest lsfr with periodicity 65535 i could find
448 dns_id = (dns_id << 1) 600 dns_id = (dns_id << 1)
449 | (((dns_id >> 1) 601 | (((dns_id >> 1)
450 ^ (dns_id >> 2) 602 ^ (dns_id >> 2)
451 ^ (dns_id >> 4) 603 ^ (dns_id >> 4)
452 ^ (dns_id >> 15)) & 1); 604 ^ (dns_id >> 15)) & 1);
453 605
454 return dns_id; 606 return dns_id;
455} 607#else
608 dns_id++;//D
456 609
457dns_req::dns_req (connection *c) 610 return htons (dns_id);
458: conn (c) 611#endif
612}
613
614struct dns_rcv;
615struct dns_snd;
616
617struct dns_connection
459{ 618{
460 next = 0; 619 connection *c;
620 struct vpn *vpn;
621
622 dns_cfg cfg;
623
624 bool established;
625 const basecoder *cdc;
626
627 tstamp last_received;
628 tstamp last_sent;
629 double min_latency;
630 double poll_interval, send_interval;
631
632 vector<dns_rcv *> rcvpq;
633
634 byte_stream rcvdq; int rcvseq; int repseq;
635 byte_stream snddq; int sndseq;
636
637 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
638 void receive_rep (dns_rcv *r);
639
640 void reset (); // quite like tcp RST
641 void set_cfg (); // to be called after any cfg changes
642
643 dns_connection (connection *c);
644 ~dns_connection ();
645};
646
647struct dns_snd
648{
649 dns_packet *pkt;
650 tstamp timeout, sent;
651 int retry;
652 struct dns_connection *dns;
653 int seqno;
654 bool stdhdr;
655
656 void gen_stream_req (int seqno, byte_stream &stream);
657 void gen_syn_req ();
658
659 dns_snd (dns_connection *dns);
660 ~dns_snd ();
661};
662
663dns_snd::dns_snd (dns_connection *dns)
664: dns (dns)
665{
666 timeout = 0;
461 retry = 0; 667 retry = 0;
668 seqno = 0;
669 sent = ev_now ();
670 stdhdr = false;
462 671
463 pkt = new dns_packet; 672 pkt = new dns_packet;
464 673
465 pkt->id = next_id (); 674 pkt->id = next_id ();
466} 675}
467 676
677dns_snd::~dns_snd ()
678{
679 delete pkt;
680}
681
682static void
683append_domain (dns_packet &pkt, int &offs, const char *domain)
684{
685 // add tunnel domain
686 for (;;)
687 {
688 const char *end = strchr (domain, '.');
689
690 if (!end)
691 end = domain + strlen (domain);
692
693 int len = end - domain;
694
695 pkt [offs++] = len;
696 memcpy (pkt.at (offs), domain, len);
697 offs += len;
698
699 if (!*end)
700 break;
701
702 domain = end + 1;
703 }
704}
705
706void
468void dns_req::gen_stream_req (int seqno, byte_stream *stream) 707dns_snd::gen_stream_req (int seqno, byte_stream &stream)
469{ 708{
709 stdhdr = true;
470 this->seqno = seqno; 710 this->seqno = seqno;
711
712 timeout = ev_now () + INITIAL_TIMEOUT;
471 713
472 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 714 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
473 pkt->qdcount = htons (1); 715 pkt->qdcount = htons (1);
474 716
475 int offs = 6*2; 717 int offs = 6*2;
476 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 718 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
477 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, 719 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
478 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 720 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
479 721
480 char enc[256], *encp = enc; 722 char enc[256], *encp = enc;
481 encode_header (enc, THISNODE->id, seqno); 723 encode_header (enc, THISNODE->id, seqno);
482 724
483 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); 725 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
484 726
485 if (datalen > stream->size ()) 727 if (datalen > stream.size ())
486 datalen = stream->size (); 728 datalen = stream.size ();
487 729
488 int enclen = cdc62.encode (enc + HDRSIZE, stream->begin (), datalen) + HDRSIZE; 730 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
489
490 printf ("cdc62.encode %d->%d:%02x %02x %02x %02x\n", datalen, enclen,
491 stream->begin ()[0],
492 stream->begin ()[1],
493 stream->begin ()[2],
494 stream->begin ()[3]);
495
496 stream->remove (datalen); 731 stream.remove (datalen);
497 732
498 while (enclen) 733 while (enclen)
499 { 734 {
500 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 735 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
501 736
… …
506 encp += lbllen; 741 encp += lbllen;
507 742
508 enclen -= lbllen; 743 enclen -= lbllen;
509 } 744 }
510 745
511 const char *suffix = THISNODE->domain; 746 append_domain (*pkt, offs, dns->c->conf->domain);
512
513 // add tunnel domain
514 for (;;)
515 {
516 const char *end = strchr (suffix, '.');
517
518 if (!end)
519 end = suffix + strlen (suffix);
520
521 int len = end - suffix;
522
523 (*pkt)[offs++] = len;
524 memcpy (&((*pkt)[offs]), suffix, len);
525 offs += len;
526
527 if (!*end)
528 break;
529
530 suffix = end + 1;
531 }
532 747
533 (*pkt)[offs++] = 0; 748 (*pkt)[offs++] = 0;
534 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 749 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
750 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
751
752 pkt->len = offs;
753}
754
755void
756dns_snd::gen_syn_req ()
757{
758 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
759
760 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
761 pkt->qdcount = htons (1);
762
763 int offs = 6 * 2;
764
765 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
766
767 assert (elen <= MAX_LBL_SIZE);
768
769 (*pkt)[offs] = elen;
770 offs += elen + 1;
771 append_domain (*pkt, offs, dns->c->conf->domain);
772
773 (*pkt)[offs++] = 0;
774 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
535 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 775 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
536 776
537 pkt->len = offs; 777 pkt->len = offs;
538} 778}
539 779
… …
558{ 798{
559 delete pkt; 799 delete pkt;
560} 800}
561 801
562///////////////////////////////////////////////////////////////////////////// 802/////////////////////////////////////////////////////////////////////////////
563 803
564struct dns_cfg 804dns_connection::dns_connection (connection *c)
805: c (c)
806, rcvdq (MAX_BACKLOG * 2)
807, snddq (MAX_BACKLOG)
565{ 808{
566 u8 id1, id2, id3; 809 tw.set<dns_connection, &dns_connection::time_cb> (this);
567 u8 def_ttl;
568 u8 unused1;
569 u16 max_size;
570 u8 flags1, flags2;
571};
572 810
811 vpn = c->vpn;
812
813 reset ();
814}
815
816dns_connection::~dns_connection ()
817{
818 reset ();
819}
820
821void
822dns_connection::reset ()
823{
824 while (!rcvpq.empty ())
825 {
826 delete rcvpq.back ();
827 rcvpq.pop_back ();
828 }
829
830 for (int i = vpn->dns_sndpq.size (); i--; )
831 if (vpn->dns_sndpq [i]->dns == this)
832 {
833 vpn->dns_sndpq [i] = vpn->dns_sndpq.back ();
834 vpn->dns_sndpq.pop_back ();
835 }
836
837 established = false;
838
839 rcvseq = repseq = sndseq = 0;
840
841 last_sent = 0;
842 poll_interval = 0.5; // starting here
843 send_interval = 0.5; // starting rate
844 min_latency = INITIAL_TIMEOUT;
845}
846
847void
848dns_connection::set_cfg ()
849{
850 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
851}
852
853void
573void connection::dnsv4_receive_rep (struct dns_rcv *r) 854dns_connection::receive_rep (dns_rcv *r)
574{ 855{
856 if (r->datalen)
857 poll_interval = max (poll_interval * (1. / 1.2), MIN_POLL_INTERVAL);
858 else
859 poll_interval = min (poll_interval * 1.1, MAX_POLL_INTERVAL);
860
575 dns_rcvpq.push_back (r); 861 rcvpq.push_back (r);
576 862
577 printf ("%d got inketc %d (%02x %02x %02x %02x)\n", THISNODE->id, r->seqno
578 ,r->data[0]
579 ,r->data[1]
580 ,r->data[2]
581 ,r->data[3]
582 );
583 redo: 863 redo:
584 864
585 // find next packet 865 // find next packet
586 for (vector<dns_rcv *>::iterator i = dns_rcvpq.end (); i-- != dns_rcvpq.begin (); ) 866 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
587 if (SEQNO_EQ (dns_rcvseq, (*i)->seqno)) 867 if (SEQNO_EQ (rcvseq, (*i)->seqno))
588 { 868 {
869 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
589 // enter the packet into our input stream 870 // enter the packet into our input stream
590 r = *i; 871 r = *i;
591 872
592 printf ("%d checking for older packet %d\n", THISNODE->id, dns_rcvseq);
593 // remove the oldest packet, look forward, as it's oldest first 873 // remove the oldest packet, look forward, as it's oldest first
594 for (vector<dns_rcv *>::iterator j = dns_rcvpq.begin (); j != dns_rcvpq.end (); ++j) 874 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
595 if (SEQNO_EQ ((*j)->seqno, dns_rcvseq - MAX_WINDOW)) 875 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
596 { 876 {
597 printf ("%d removing %d\n", THISNODE->id, (*j)->seqno); 877 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
598 delete *j; 878 delete *j;
599 dns_rcvpq.erase (j); 879 rcvpq.erase (j);
600 break; 880 break;
601 } 881 }
602 882
603 dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; 883 rcvseq = (rcvseq + 1) & SEQNO_MASK;
604 884
605 if (!dns_snddq && !dns_rcvdq) 885 if (!rcvdq.put (r->data, r->datalen))
606 { 886 {
607 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); 887 // MUST never overflow, can be caused by data corruption, TODO
608 dns_snddq = new byte_stream (MAX_BACKLOG); 888 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
609 889 reset ();
610 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 890 return;
611 } 891 }
612 892
613 if (!dns_rcvdq->put (r->data, r->datalen))
614 abort (); // MUST never overflow, can be caused by data corruption, TODO
615
616 while (vpn_packet *pkt = dns_rcvdq->get ()) 893 while (vpn_packet *pkt = rcvdq.get ())
617 { 894 {
618 sockinfo si; 895 sockinfo si;
619 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 896 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
620 897
621 vpn->recv_vpn_packet (pkt, si); 898 vpn->recv_vpn_packet (pkt, si);
899 delete pkt;
622 } 900 }
623 901
624 // check for further packets 902 // check for further packets
625 goto redo; 903 goto redo;
626 } 904 }
627} 905}
628 906
629dns_packet * 907void
630vpn::dnsv4_server (dns_packet *pkt) 908vpn::dnsv4_server (dns_packet &pkt)
631{ 909{
632 u16 flags = ntohs (pkt->flags); 910 u16 flags = ntohs (pkt.flags);
633 911
634 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
635 int offs = 6 * 2; // skip header 912 int offs = 6 * 2; // skip header
636 913
637 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 914 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
638 915
639 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 916 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
640 && pkt->qdcount == htons (1)) 917 && pkt.qdcount == htons (1))
641 { 918 {
642 char qname[MAXSIZE]; 919 char qname [MAXSIZE];
643 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 920 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
644 921
645 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 922 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
646 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 923 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
647 924
648 pkt->qdcount = htons (1); 925 pkt.qdcount = htons (1);
649 pkt->ancount = 0; 926 pkt.ancount = 0;
650 pkt->nscount = 0; // should be self, as other nameservers reply like this 927 pkt.nscount = 0; // should be self, as other nameservers reply like this
651 pkt->arcount = 0; // a record for self, as other nameservers reply like this 928 pkt.arcount = 0; // a record for self, as other nameservers reply like this
652 929
653 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 930 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
654 931
655 int dlen = strlen (THISNODE->domain); 932 int dlen = strlen (THISNODE->domain);
656 933
657 if (qclass == RR_CLASS_IN 934 if (qclass == RR_CLASS_IN
658 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
659 && qlen > dlen + 1 + HDRSIZE 935 && qlen > dlen + 1
660 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 936 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
661 { 937 {
662 // correct class, domain: parse 938 // now generate reply
663 int client, seqno; 939 pkt.ancount = htons (1); // one answer RR
664 decode_header (qname, client, seqno); 940 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
665 941
666 u8 data[MAXSIZE]; 942 if ((qtype == RR_TYPE_ANY
667 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); 943 || qtype == RR_TYPE_TXT
668 944 || qtype == RR_TYPE_NULL)
669 printf ("cdc62.decode %d(%d): %02x %02x %02x %02x\n",
670 qlen - (dlen + 1 + HDRSIZE), datalen 945 && qlen > dlen + 1 + HDRSIZE)
671 ,data[0]
672 ,data[1]
673 ,data[2]
674 ,data[3]);
675
676 printf ("SRV got %d <%.*s>\n", seqno, qlen, qname + HDRSIZE);//D
677 printf ("SRV got %d <%.*s>\n", seqno, qlen - (dlen + 1 + HDRSIZE), qname + HDRSIZE);//D
678
679 if (0 < client && client <= conns.size ())
680 { 946 {
947 // correct class, domain: parse
948 int client, seqno;
949 decode_header (qname, client, seqno);
950
951 if (0 < client && client <= conns.size ())
952 {
681 connection *c = conns [client - 1]; 953 connection *c = conns [client - 1];
954 dns_connection *dns = c->dns;
955 dns_rcv *rcv;
682 956
957 if (dns)
958 {
959 u8 data[MAXSIZE];
960 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
961
683 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.end (); i-- != c->dns_rcvpq.begin (); ) 962 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
684 if (SEQNO_EQ ((*i)->seqno, seqno)) 963 if (SEQNO_EQ ((*i)->seqno, seqno))
964 {
965 // already seen that request: simply reply with the cached reply
966 dns_rcv *r = *i;
967
968 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
969
970 // refresh header & id, as the retry count could have changed
971 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
972 r->pkt->id = pkt.id;
973
974 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
975
976 goto duplicate_request;
977 }
978
979 // new packet, queue
980 rcv = new dns_rcv (seqno, data, datalen);
981 dns->receive_rep (rcv);
982 }
983
685 { 984 {
686 // already seen that request: simply reply with the cached reply 985 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
687 dns_rcv *r = *i;
688 986
689 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 987 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
988 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
989 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
990 pkt [offs++] = 0; pkt [offs++] = 0;
991 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
690 992
691 memcpy (pkt->at (0), r->pkt->at (0), offs = r->pkt->len); 993 int rdlen_offs = offs += 2;
692 pkt->id = r->pkt->id; 994
693 goto duplicate_request; 995 if (dns)
996 {
997 int dlen = ntohs (dns->cfg.max_size) - offs;
998
999 // bind doesn't compress well, so reduce further by one label length
1000 dlen -= qlen;
1001
1002 // only put data into in-order sequence packets, if
1003 // we receive out-of-order packets we generate empty
1004 // replies
1005 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
1006 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
1007 {
1008 dns->repseq = seqno;
1009
1010 while (dlen > 1 && !dns->snddq.empty ())
1011 {
1012 int txtlen = dlen <= 255 ? dlen - 1 : 255;
1013
1014 if (txtlen > dns->snddq.size ())
1015 txtlen = dns->snddq.size ();
1016
1017 pkt[offs++] = txtlen;
1018 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
1019 offs += txtlen;
1020 dns->snddq.remove (txtlen);
1021
1022 dlen -= txtlen + 1;
1023 }
1024 }
1025
1026 // avoid completely empty TXT rdata
1027 if (offs == rdlen_offs)
1028 pkt[offs++] = 0;
1029
1030 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
1031 }
1032 else
1033 {
1034 // send RST
1035 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1036 pkt [offs++] = CMD_IP_RST;
1037 }
1038
1039 int rdlen = offs - rdlen_offs;
1040
1041 pkt [rdlen_offs - 2] = rdlen >> 8;
1042 pkt [rdlen_offs - 1] = rdlen;
1043
1044 if (dns)
1045 {
1046 // now update dns_rcv copy
1047 rcv->pkt->len = offs;
1048 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
1049 }
694 } 1050 }
695 1051
696 // new packet, queue 1052 duplicate_request: ;
697 dns_rcv *rcv = new dns_rcv (seqno, data, datalen); 1053 }
698 c->dnsv4_receive_rep (rcv); 1054 else
699
700 // now generate reply
701 pkt->ancount = htons (1); // one answer RR
702 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 1055 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
1056 }
1057 else if (qtype == RR_TYPE_A
1058 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
1059 {
1060 dns_cfg cfg;
1061 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
1062 int client = ntohs (cfg.client);
703 1063
704 (*pkt) [offs++] = 0xc0;
705 (*pkt) [offs++] = 6 * 2; // same as in query section 1064 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
706 1065
707 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1066 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
708 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1067 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
709
710 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1068 pkt [offs++] = 0; pkt [offs++] = 0;
711 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL 1069 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1070 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
712 1071
713 int dlen = MAX_PKT_SIZE - offs - 2; 1072 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1073 pkt [offs++] = CMD_IP_REJ;
714 1074
715 // bind doesn't compress well, so reduce further by one label length 1075 if (0 < client && client <= conns.size ())
716 dlen -= qlen;
717
718 int rdlen_offs = offs += 2;
719
720 while (c->dns_snddq
721 && !c->dns_snddq->empty ()
722 && dlen > 1)
723 { 1076 {
724 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1077 connection *c = conns [client - 1];
725 1078
726 if (txtlen > c->dns_snddq->size ()) 1079 if (cfg.valid ())
1080 {
1081 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
1082
1083 // check for any encoding mismatches - hints at a case problem
1084 char qname2 [MAX_ENC_LEN];
1085 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
1086
1087 delete c->dns;
1088
1089 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1090 ? CMD_IP_CSE : CMD_IP_SYN;
1091
1092 c->dns = new dns_connection (c);
1093 c->dns->cfg = cfg;
727 txtlen = c->dns_snddq->size (); 1094 c->dns->set_cfg ();
728 1095 }
729 (*pkt)[offs++] = txtlen;
730 memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);
731 offs += txtlen;
732 c->dns_snddq->remove (txtlen);
733
734 dlen -= txtlen + 1;
735 } 1096 }
736
737 // avoid empty TXT rdata
738 if (offs == rdlen_offs)
739 (*pkt)[offs++] = 0;
740
741 int rdlen = offs - rdlen_offs;
742
743 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
744 (*pkt) [rdlen_offs - 1] = rdlen;
745
746 // now update dns_rcv copy
747 rcv->pkt->len = offs;
748 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
749
750 duplicate_request: ;
751 } 1097 }
752 else
753 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
754 } 1098 }
755 1099
756 pkt->len = offs; 1100 pkt.len = offs;
757 } 1101 }
758
759 return pkt;
760} 1102}
761 1103
762void 1104void
763vpn::dnsv4_client (dns_packet *pkt) 1105vpn::dnsv4_client (dns_packet &pkt)
764{ 1106{
765 u16 flags = ntohs (pkt->flags); 1107 u16 flags = ntohs (pkt.flags);
766 int offs = 6 * 2; // skip header 1108 int offs = 6 * 2; // skip header
767 1109
768 pkt->qdcount = ntohs (pkt->qdcount); 1110 pkt.qdcount = ntohs (pkt.qdcount);
769 pkt->ancount = ntohs (pkt->ancount); 1111 pkt.ancount = ntohs (pkt.ancount);
770 1112
771 // go through our request list and find the corresponding request 1113 // go through our request list and find the corresponding request
772 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1114 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
773 i != dns_sndpq.end (); 1115 i != dns_sndpq.end ();
774 ++i) 1116 ++i)
775 if ((*i)->pkt->id == pkt->id) 1117 if ((*i)->pkt->id == pkt.id)
776 { 1118 {
1119 dns_connection *dns = (*i)->dns;
777 connection *c = (*i)->conn; 1120 connection *c = dns->c;
778 int seqno = (*i)->seqno; 1121 int seqno = (*i)->seqno;
779 u8 data[MAXSIZE], *datap = data; 1122 u8 data[MAXSIZE], *datap = data;
1123 //printf ("rcv pkt %x\n", seqno);//D
1124
1125 if ((*i)->retry)
1126 {
1127 dns->send_interval *= 1.01;
1128 if (dns->send_interval > MAX_SEND_INTERVAL)
1129 dns->send_interval = MAX_SEND_INTERVAL;
1130 }
1131 else
1132 {
1133#if 0
1134 dns->send_interval *= 0.999;
1135#endif
1136 // the latency surely puts an upper bound on
1137 // the minimum send interval
1138 double latency = ev_now () - (*i)->sent;
1139
1140 if (latency < dns->min_latency)
1141 dns->min_latency = latency;
1142
1143 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1144 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1145
1146 if (dns->send_interval < conf.dns_send_interval)
1147 dns->send_interval = conf.dns_send_interval;
1148 }
780 1149
781 delete *i; 1150 delete *i;
782 dns_sndpq.erase (i); 1151 dns_sndpq.erase (i);
783 1152
784 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1153 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
785 { 1154 {
786 char qname[MAXSIZE]; 1155 char qname[MAXSIZE];
787 1156
788 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1157 while (pkt.qdcount-- && offs < MAXSIZE - 4)
789 { 1158 {
790 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1159 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
791 offs += 4; // skip qtype, qclass 1160 offs += 4; // skip qtype, qclass
792 } 1161 }
793 1162
794 while (pkt->ancount-- && offs < MAXSIZE - 10) 1163 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
795 { 1164 {
796 int qlen = //D
797 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1165 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
798 1166
799 printf ("got reply to <%.*s>\n", qlen, qname);//D
800
801 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1167 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
802 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1168 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
803 u32 ttl = (*pkt) [offs++] << 24; 1169 u32 ttl = pkt [offs++] << 24;
804 ttl |= (*pkt) [offs++] << 16; 1170 ttl |= pkt [offs++] << 16;
805 ttl |= (*pkt) [offs++] << 8; 1171 ttl |= pkt [offs++] << 8;
806 ttl |= (*pkt) [offs++]; 1172 ttl |= pkt [offs++];
807
808 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1173 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
809 1174
810 if (rdlen <= MAXSIZE - offs) 1175 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
811 { 1176 {
812 // decode bytes, finally 1177 if (rdlen <= MAXSIZE - offs)
813
814 while (rdlen)
815 { 1178 {
1179 // decode bytes, finally
1180
1181 while (rdlen)
1182 {
816 int txtlen = (*pkt) [offs++]; 1183 int txtlen = pkt [offs++];
817 1184
818 assert (txtlen + offs < MAXSIZE - 1); 1185 assert (txtlen + offs < MAXSIZE - 1);
819 1186
820 memcpy (datap, pkt->at (offs), txtlen); 1187 memcpy (datap, pkt.at (offs), txtlen);
821 datap += txtlen; offs += txtlen; 1188 datap += txtlen; offs += txtlen;
822 1189
823 rdlen -= txtlen + 1; 1190 rdlen -= txtlen + 1;
1191 }
824 } 1192 }
825
826 } 1193 }
1194 else if (qtype == RR_TYPE_A)
1195 {
1196 u8 ip [4];
827 1197
1198 ip [0] = pkt [offs++];
1199 ip [1] = pkt [offs++];
1200 ip [2] = pkt [offs++];
1201 ip [3] = pkt [offs++];
1202
1203 if (ip [0] == CMD_IP_1
1204 && ip [1] == CMD_IP_2
1205 && ip [2] == CMD_IP_3)
1206 {
1207 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1208
1209 if (ip [3] == CMD_IP_RST)
1210 {
1211 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1212
1213 dns->reset ();
1214 return;
1215 }
1216 else if (ip [3] == CMD_IP_SYN)
1217 {
1218 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1219 dns->established = true;
1220 }
1221 else if (ip [3] == CMD_IP_CSE)
1222 {
1223 if (conf.dns_case_preserving)
1224 {
1225 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1226 conf.dns_case_preserving = false;
1227 dns->reset ();
1228 return;
1229 }
1230 else
1231 {
1232 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1233 dns->established = true;
1234 }
1235 }
1236 else if (ip [3] == CMD_IP_REJ)
1237 {
1238 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1239 dns->tw.start (60.);
1240 }
1241 else
1242 {
1243 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1244 dns->tw.start (60.);
1245 }
1246 }
1247 else
1248 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1249 ip [0], ip [1], ip [2], ip [3]);
1250
1251 return;
1252 }
1253
1254 int client, rseqno;
1255 decode_header (qname, client, rseqno);
1256
1257 if (client != THISNODE->id)
1258 {
1259 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1260 datap = 0;
1261 }
1262 else if (rseqno != seqno)
1263 {
1264 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1265 datap = 0;
1266 }
828 } 1267 }
829 } 1268 }
830 1269
831 // todo: pkt now used 1270 // todo: pkt now used
1271 if (datap)
832 c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data)); 1272 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
833 1273
834 break; 1274 break;
835 } 1275 }
836
837 delete pkt;
838} 1276}
839 1277
840void 1278void
841vpn::dnsv4_ev (io_watcher &w, short revents) 1279vpn::dnsv4_ev (ev::io &w, int revents)
842{ 1280{
843 if (revents & EVENT_READ) 1281 if (revents & EV_READ)
844 { 1282 {
845 dns_packet *pkt = new dns_packet; 1283 dns_packet *pkt = new dns_packet;
846 struct sockaddr_in sa; 1284 struct sockaddr_in sa;
847 socklen_t sa_len = sizeof (sa); 1285 socklen_t sa_len = sizeof (sa);
848 1286
849 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1287 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
850 1288
851 if (pkt->len > 0) 1289 if (pkt->len > 0)
852 { 1290 {
853 if (pkt->flags & htons (FLAG_TC)) 1291 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1292 dnsv4_client (*pkt);
1293 else
854 { 1294 {
855 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1295 dnsv4_server (*pkt);
856 //TODO connection reset 1296 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
857 } 1297 }
858 1298
859 if (THISNODE->dns_port) 1299 delete pkt;
860 {
861 pkt = dnsv4_server (pkt);
862 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
863 }
864 else
865 dnsv4_client (pkt);
866 } 1300 }
867 } 1301 }
868} 1302}
869 1303
870bool 1304bool
871connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1305vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
872{ 1306{
873 // never initialized 1307 int client = ntohl (si.host);
874 if (!dns_snddq && !dns_rcvdq)
875 {
876 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
877 dns_snddq = new byte_stream (MAX_BACKLOG);
878 1308
879 //dns_rcvseq = dns_sndseq = 0; 1309 assert (0 < client && client <= conns.size ());
880 1310
881 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1311 connection *c = conns [client - 1];
882 } 1312
1313 if (!c->dns)
1314 c->dns = new dns_connection (c);
883 1315
884 if (!dns_snddq->put (pkt)) 1316 if (c->dns->snddq.put (pkt))
885 return false; 1317 {
1318 min_it (c->dns->poll_interval, 0.25);
1319 c->dns->tw ();
1320 }
886 1321
887 // start timer if neccessary 1322 // always return true even if the buffer overflows
888 if (!THISNODE->dns_port && !dnsv4_tw.active)
889 dnsv4_cb (dnsv4_tw);
890
891 return true; 1323 return true;
892} 1324}
893 1325
894void 1326void
895connection::dnsv4_cb (time_watcher &w) 1327dns_connection::time_cb (ev::timer &w, int revents)
896{ 1328{
1329 // servers have to be polled
1330 if (THISNODE->dns_port)
1331 return;
1332
897 // check for timeouts and (re)transmit 1333 // check for timeouts and (re)transmit
898 tstamp next = NOW + 60; 1334 tstamp next = 86400 * 365;
899 dns_req *send = 0; 1335 dns_snd *send = 0;
900 1336
901 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1337 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
902 i != vpn->dns_sndpq.end (); 1338 i != vpn->dns_sndpq.end ();
903 ++i) 1339 ++i)
904 { 1340 {
905 dns_req *r = *i; 1341 dns_snd *r = *i;
906 1342
907 if (r->next <= NOW) 1343 if (r->timeout <= ev_now ())
908 { 1344 {
909 if (!send) 1345 if (!send)
910 { 1346 {
911 send = r; 1347 send = r;
912 1348
913 if (r->retry)//D
914 printf ("req %d:%d, retry %d\n", r->seqno, r->pkt->id, r->retry);
915 r->retry++; 1349 r->retry++;
916 r->next = NOW + r->retry; 1350 r->timeout = ev_now () + r->retry * min_latency * conf.dns_timeout_factor;
1351 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1352
1353 // the following code changes the query section a bit, forcing
1354 // the forwarder to generate a new request
1355 if (r->stdhdr)
1356 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
917 } 1357 }
918 } 1358 }
919 1359 else
920 if (r->next < next) 1360 min_it (next, r->timeout - ev_now ());
921 next = r->next;
922 } 1361 }
923 1362
924 if (!send 1363 if (!send)
925 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
926 { 1364 {
1365 // generate a new packet, if wise
1366
1367 if (!established)
1368 {
1369 if (vpn->dns_sndpq.empty ())
1370 {
927 send = new dns_req (this); 1371 send = new dns_snd (this);
1372
1373 cfg.reset (THISNODE->id);
1374 set_cfg ();
1375 send->gen_syn_req ();
1376 }
1377 }
1378 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1379 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1380 {
1381 if (last_sent + send_interval <= ev_now ())
1382 {
1383 //printf ("sending data request etc.\n"); //D
1384 if (!snddq.empty ())
1385 min_it (next, send_interval);
1386
1387 send = new dns_snd (this);
928 send->gen_stream_req (dns_sndseq, dns_snddq); 1388 send->gen_stream_req (sndseq, snddq);
1389 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1390 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1391
1392 sndseq = (sndseq + 1) & SEQNO_MASK;
1393 }
1394 else
1395 min_it (next, last_sent + send_interval - ev_now ());
1396 }
1397
1398 if (send)
929 vpn->dns_sndpq.push_back (send); 1399 vpn->dns_sndpq.push_back (send);
930
931 dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
932 } 1400 }
933
934 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
935 1401
936 if (send) 1402 if (send)
937 { 1403 {
938 dns_packet *pkt = send->pkt; 1404 last_sent = ev_now ();
939 1405 sendto (vpn->dnsv4_fd,
940 next = min_next; 1406 send->pkt->at (0), send->pkt->len, 0,
941 1407 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
942 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
943 } 1408 }
944 else if (next < min_next) 1409
945 next = min_next; 1410 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1411
1412 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1413 poll_interval, send_interval, next - ev_now (),
1414 vpn->dns_sndpq.size (), snddq.size (),
1415 rcvpq.size ());
946 1416
947 w.start (next); 1417 w.start (next);
948} 1418}
949 1419
950#endif 1420#endif

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