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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 UTC vs.
Revision 1.54 by root, Tue Oct 18 11:07:28 2011 UTC

1/* 1/*
2 vpn_dns.C -- handle the dns tunnel part of the protocol. 2 vpn_dns.C -- handle the dns tunnel part of the protocol.
3 Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com> 3 Copyright (C) 2003-2011 Marc Lehmann <gvpe@schmorp.de>
4 4
5 This file is part of GVPE.
6
5 This program is free software; you can redistribute it and/or modify 7 GVPE is free software; you can redistribute it and/or modify it
6 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
7 the Free Software Foundation; either version 2 of the License, or 9 Free Software Foundation; either version 3 of the License, or (at your
8 (at your option) any later version. 10 option) any later version.
9 11
10 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
11 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
13 GNU General Public License for more details. 15 Public License for more details.
14 16
15 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
16 along with this program; if not, write to the Free Software 18 with this program; if not, see <http://www.gnu.org/licenses/>.
17 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.
18*/ 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.
19 35
20#include "config.h" 36#include "config.h"
21 37
22#if ENABLE_DNS 38#if ENABLE_DNS
23 39
24// dns processing is EXTREMELY ugly. For obvious(?) reasons. 40// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25// it's a hack, use only in emergency situations please. 41// it's a hack, use only in emergency situations please.
26 42
27#include <cstring> 43#include <cstring>
44#include <cassert>
28 45
29#include <sys/types.h> 46#include <sys/types.h>
30#include <sys/socket.h> 47#include <sys/socket.h>
31#include <sys/wait.h> 48#include <sys/wait.h>
32#include <sys/uio.h> 49#include <sys/uio.h>
… …
35#include <unistd.h> 52#include <unistd.h>
36#include <fcntl.h> 53#include <fcntl.h>
37 54
38#include <map> 55#include <map>
39 56
57#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
58#include <gmp.h>
59
40#include "netcompat.h" 60#include "netcompat.h"
41 61
42#include "vpn.h" 62#include "vpn.h"
43 63
44#define MIN_RETRY 1. 64#define MIN_POLL_INTERVAL 0.025 // poll at most this often when no data received
45#define MAX_RETRY 60. 65#define MAX_POLL_INTERVAL 1. // how often to poll minimally when the server has no data
46 66
47#define MAX_OUTSTANDING 10 // 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
48#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
49#define MAX_RATE 1 // requests/s
50#define MAX_BACKLOG (10*1024) // size of protocol backlog 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51 74
52/* 75#define MAX_DOMAIN_SIZE 235 // 255 is legal limit, but bind doesn't compress well
76// 240 leaves about 4 bytes of server reply data
77// every request byte less give room for two reply bytes
53 78
54protocol, in shorthand :) 79#define SEQNO_MASK 0x3fff
55 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
56client -> server <req> ANY?
57server -> client <req> TXT <rep>
58
59<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
60<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
61
62if <client-id> is zero, the connection will be configured:
63
64<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
65
66*/
67 81
68#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
69#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
70 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
71#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
72#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
73#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
74 92
75// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 93#define CMD_IP_1 207
76struct dns64 94#define CMD_IP_2 46
77{ 95#define CMD_IP_3 236
78 static const char encode_chars[64 + 1];
79 static s8 decode_chars[256];
80 96
81 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 97#define CMD_IP_RST 29 // some error, reset and retry
82 static int decode_len (int bytes) { return (bytes * 6) / 8; } 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}
113
114// works for cmaps up to 255 (not 256!)
115struct charmap
116{
117 enum { INVALID = (u8)255 };
118
119 char encode [256]; // index => char
120 u8 decode [256]; // char => index
121 unsigned int size;
122
123 charmap (const char *cmap);
124};
125
126charmap::charmap (const char *cmap)
127{
128 char *enc = encode;
129 u8 *dec = decode;
130
131 memset (enc, (char) 0, 256);
132 memset (dec, (char)INVALID, 256);
133
134 for (size = 0; cmap [size]; size++)
135 {
136 char c = cmap [size];
137
138 enc [size] = c;
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;
144 }
145
146 assert (size < 256);
147}
148
149#define MAX_DEC_LEN 500
150#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
151#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
152
153// ugly. minimum base is 16(!)
154struct basecoder
155{
156 charmap cmap;
157 unsigned int enc_len [MAX_DEC_LEN];
158 unsigned int dec_len [MAX_ENC_LEN];
159
160 unsigned int encode_len (unsigned int len) const;
161 unsigned int decode_len (unsigned int len) const;
162
83 static int encode (char *dst, u8 *src, int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
84 static int decode (u8 *dst, char *src, int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
85 165
86 dns64 (); 166 basecoder (const char *cmap);
87} dns64; 167};
88 168
89const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-"; 169basecoder::basecoder (const char *cmap)
90s8 dns64::decode_chars[256]; 170: cmap (cmap)
91
92dns64::dns64 ()
93{ 171{
94 for (int i = 0; i < 64; i++) 172 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95 decode_chars [encode_chars [i]] = i + 1; 173 {
96} 174 u8 src [MAX_DEC_LEN];
175 u8 dst [MAX_ENC_LEN];
97 176
98int dns64::encode (char *dst, u8 *src, int len) 177 memset (src, 255, len);
178
179 mp_limb_t m [MAX_LIMBS];
180 mp_size_t n;
181
182 n = mpn_set_str (m, src, len, 256);
183 n = mpn_get_str (dst, this->cmap.size, m, n);
184
185 for (int i = 0; !dst [i]; ++i)
186 n--;
187
188 enc_len [len] = n;
189 dec_len [n] = len;
190 }
191}
192
193unsigned int
194basecoder::encode_len (unsigned int len) const
99{ 195{
100 // slow, but easy to debug 196 return enc_len [len];
101 char *beg = dst; 197}
102 unsigned int accum, bits = 0; 198
199unsigned int
200basecoder::decode_len (unsigned int len) const
201{
202 while (len && !dec_len [len])
203 --len;
204
205 return dec_len [len];
206}
207
208unsigned int
209basecoder::encode (char *dst, u8 *src, unsigned int len) const
210{
211 if (!len || len > MAX_DEC_LEN)
212 return 0;
213
214 int elen = encode_len (len);
215
216 mp_limb_t m [MAX_LIMBS];
217 mp_size_t n;
218
219 u8 dst_ [MAX_ENC_LEN];
220
221 n = mpn_set_str (m, src, len, 256);
222 n = mpn_get_str (dst_, cmap.size, m, n);
223
224 int plen = elen; // for padding
225
226 while (n < plen)
227 {
228 *dst++ = cmap.encode [0];
229 plen--;
230 }
231
232 for (unsigned int i = n - plen; i < n; ++i)
233 *dst++ = cmap.encode [dst_ [i]];
234
235 return elen;
236}
237
238unsigned int
239basecoder::decode (u8 *dst, char *src, unsigned int len) const
240{
241 if (!len || len > MAX_ENC_LEN)
242 return 0;
243
244 u8 src_ [MAX_ENC_LEN];
245 unsigned int elen = 0;
103 246
104 while (len--) 247 while (len--)
105 { 248 {
106 accum <<= 8; 249 u8 val = cmap.decode [(u8)*src++];
107 accum |= *src++;
108 bits += 8;
109 250
110 while (bits >= 6) 251 if (val != charmap::INVALID)
111 { 252 src_ [elen++] = val;
112 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 253 }
113 bits -= 6; 254
114 } 255 int dlen = decode_len (elen);
256
257 mp_limb_t m [MAX_LIMBS];
258 mp_size_t n;
259
260 u8 dst_ [MAX_DEC_LEN];
261
262 n = mpn_set_str (m, src_, elen, cmap.size);
263 n = mpn_get_str (dst_, 256, m, n);
264
265 if (n < dlen)
115 } 266 {
267 memset (dst, 0, dlen - n);
268 memcpy (dst + dlen - n, dst_, n);
269 }
270 else
271 memcpy (dst, dst_ + n - dlen, dlen);
116 272
117 if (bits) 273 return dlen;
118 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120 return dst - beg;
121} 274}
122 275
123int dns64::decode (u8 *dst, char *src, int len) 276#if 0
124{ 277struct test { test (); } test;
125 // slow, but easy to debug
126 u8 *beg = dst;
127 unsigned int accum, bits = 0;
128 278
129 while (len--) 279test::test ()
280{
281 basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
282
283 u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
284 static char enc[200];
285 static u8 dec[200];
286
287 for (int i = 1; i < 20; i++)
130 { 288 {
131 s8 chr = decode_chars [(u8)*src++]; 289 int elen = cdc.encode (enc, in, i);
290 int dlen = cdc.decode (dec, enc, elen);
132 291
133 if (!chr) 292 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
134 break;
135
136 accum <<= 6;
137 accum |= chr - 1;
138 bits += 6;
139
140 while (bits >= 8)
141 {
142 *dst++ = accum >> (bits - 8);
143 bits -= 8;
144 }
145 } 293 }
294 abort ();
295}
296#endif
146 297
147 return dst - beg; 298static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9
299static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers
300static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z
301
302/////////////////////////////////////////////////////////////////////////////
303
304#define HDRSIZE 5
305
306inline void
307encode_header (char *data, int clientid, int seqno, int retry = 0)
308{
309 assert (clientid < 256);
310
311 seqno &= SEQNO_MASK;
312
313 u8 hdr[3] = {
314 seqno,
315 (seqno >> 8) | (retry << 6),
316 clientid,
317 };
318
319 cdc36.encode (data, hdr, 3);
320}
321
322inline void
323decode_header (char *data, int &clientid, int &seqno)
324{
325 u8 hdr[3];
326
327 cdc36.decode (hdr, data, HDRSIZE);
328
329 clientid = hdr[2];
330 seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK;
148} 331}
149 332
150///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
151 334
152struct byte_stream 335struct byte_stream
… …
159 ~byte_stream (); 342 ~byte_stream ();
160 343
161 bool empty () { return !fill; } 344 bool empty () { return !fill; }
162 int size () { return fill; } 345 int size () { return fill; }
163 346
347 bool put (u8 *data, unsigned int datalen);
164 bool put (vpn_packet *pkt); 348 bool put (vpn_packet *pkt);
165 vpn_packet *get (); 349 vpn_packet *get ();
166 350
167 u8 *begin () { return data; } 351 u8 *begin () { return data; }
168 void remove (int count); 352 void remove (int count);
… …
177byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
178{ 362{
179 delete data; 363 delete data;
180} 364}
181 365
366void
182void byte_stream::remove (int count) 367byte_stream::remove (int count)
183{ 368{
184 if (count > fill) 369 if (count > fill)
185 abort (); 370 assert (count <= fill);
186 371
187 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
188} 373}
189 374
375bool
376byte_stream::put (u8 *data, unsigned int datalen)
377{
378 if (maxsize - fill < datalen)
379 return false;
380
381 memcpy (this->data + fill, data, datalen); fill += datalen;
382
383 return true;
384}
385
386bool
190bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
191{ 388{
192 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
193 return false; 390 return false;
194 391
195 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
196 data [fill++] = pkt->len; 393 data [fill++] = pkt->len;
197 394
198 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 395 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199 396
200 return true; 397 return true;
201} 398}
202 399
203vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
204{ 401{
402 if (fill < 2)
403 return 0;
404
405 unsigned int len;
406
407 for (;;)
408 {
205 int len = (data [0] << 8) | data [1]; 409 len = (data [0] << 8) | data [1];
206 410
411 if (len <= MAXSIZE)
412 break;
413
414 // TODO: handle this better than skipping, e.g. by reset
415 slog (L_DEBUG, _("DNS: corrupted packet (%02x %02x) stream skipping a byte..."), data [0], data [1]);
416 remove (1);
417 }
418
207 if (fill < len + 2) 419 if (fill < len + 2)
208 return 0; 420 return 0;
209 421
210 vpn_packet *pkt = new vpn_packet; 422 vpn_packet *pkt = new vpn_packet;
423
424 pkt->len = len;
211 memcpy (&((*pkt)[0]), data + 2, len); 425 memcpy (pkt->at (0), data + 2, len);
212 remove (len + 2); 426 remove (len + 2);
213 427
214 return pkt; 428 return pkt;
215} 429}
216 430
217///////////////////////////////////////////////////////////////////////////// 431/////////////////////////////////////////////////////////////////////////////
218 432
219#define FLAG_QUERY ( 0 << 15) 433#define FLAG_QUERY ( 0 << 15)
220#define FLAG_RESPONSE ( 1 << 15) 434#define FLAG_RESPONSE ( 1 << 15)
221#define FLAG_OP_MASK (15 << 14) 435#define FLAG_OP_MASK (15 << 11)
222#define FLAG_OP_QUERY ( 0 << 11) 436#define FLAG_OP_QUERY ( 0 << 11)
223#define FLAG_AA ( 1 << 10) 437#define FLAG_AA ( 1 << 10)
224#define FLAG_TC ( 1 << 9) 438#define FLAG_TC ( 1 << 9)
225#define FLAG_RD ( 1 << 8) 439#define FLAG_RD ( 1 << 8)
226#define FLAG_RA ( 1 << 7) 440#define FLAG_RA ( 1 << 7)
441#define FLAG_AUTH ( 1 << 5)
227#define FLAG_RCODE_MASK (15 << 0) 442#define FLAG_RCODE_MASK (15 << 0)
228#define FLAG_RCODE_OK ( 0 << 0) 443#define FLAG_RCODE_OK ( 0 << 0)
229#define FLAG_RCODE_FORMERR ( 1 << 0) 444#define FLAG_RCODE_FORMERR ( 1 << 0)
230#define FLAG_RCODE_SERVFAIL ( 2 << 0) 445#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231#define FLAG_RCODE_NXDOMAIN ( 3 << 0) 446#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232#define FLAG_RCODE_REFUSED ( 5 << 0) 447#define FLAG_RCODE_REFUSED ( 5 << 0)
233 448
234#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 449#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
235#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD) 450#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
451
452struct dns_cfg
453{
454 static int next_uid;
455
456 u8 chksum;
457 u8 rrtype;
458 u16 uid; // to make request unique
459
460 u8 version;
461 u8 flags;
462 u16 max_size;
463
464 u8 id1, id2, id3, id4;
465
466 u16 client;
467 u8 def_ttl;
468 u8 r0;
469
470 u8 syn_cdc; // cdc en/decoder for syn (A?) requests
471 u8 hdr_cdc; // cdc en/decoder for regular request headers
472 u8 req_cdc; // cdc en/decoder for regular (ANY?) request data
473 u8 rep_cdc; // cdc en/decoder for regular (TXT) replies, 0 == 8 bit encoding
474
475 u8 r1, r2, r3, r4;
476
477 void reset (int clientid);
478 bool valid ();
479 u8 get_chksum ();
480};
481
482int dns_cfg::next_uid;
483
484void
485dns_cfg::reset (int clientid)
486{
487 // this ID must result in some mixed-case characters in cdc26-encoding
488 id1 = 'G';
489 id2 = 'V';
490 id3 = 'P';
491 id4 = 'E';
492
493 version = 2;
494
495 rrtype = RR_TYPE_TXT;
496 flags = 0;
497 def_ttl = 0;
498 syn_cdc = 26;
499 hdr_cdc = 36;
500 req_cdc = conf.dns_case_preserving ? 62 : 36;
501 rep_cdc = 0;
502 max_size = htons (MAX_PKT_SIZE);
503 client = htons (clientid);
504 uid = ++next_uid;
505
506 r0 = r1 = r2 = r3 = r4 = 0;
507
508 chksum = get_chksum ();
509}
510
511// simple but not trivial chksum
512u8
513dns_cfg::get_chksum ()
514{
515 unsigned int sum = 0xff00; // only 16 bits required
516
517 u8 old_chksum = chksum;
518 chksum = 0;
519
520 for (unsigned int i = 0; i < sizeof (*this); ++i)
521 sum += ((u8 *)this)[i] * (i + 1);
522
523 chksum = old_chksum;
524
525 return sum + (sum >> 8);
526}
527
528bool
529dns_cfg::valid ()
530{
531 // although the protocol itself allows for some configurability,
532 // only the following encoding/decoding settings are implemented.
533 return id1 == 'G'
534 && id2 == 'V'
535 && id3 == 'P'
536 && id4 == 'E'
537 && version == 2
538 && syn_cdc == 26
539 && hdr_cdc == 36
540 && (req_cdc == 36 || req_cdc == 62)
541 && rep_cdc == 0
542 && chksum == get_chksum ();
543}
236 544
237struct dns_packet : net_packet 545struct dns_packet : net_packet
238{ 546{
239 u16 id; 547 u16 id;
240 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 548 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
241 u16 qdcount, ancount, nscount, arcount; 549 u16 qdcount, ancount, nscount, arcount;
242 550
243 u8 data[MAXSIZE - 6 * 2]; 551 u8 data [MAXSIZE - 6 * 2];
244 552
245 int decode_label (char *data, int size, int &offs); 553 int decode_label (char *data, int size, int &offs);
246}; 554};
247 555
556int
248int dns_packet::decode_label (char *data, int size, int &offs) 557dns_packet::decode_label (char *data, int size, int &offs)
249{ 558{
250 char *orig = data; 559 char *orig = data;
251 560
252 memset (data, 0, size); 561 memset (data, 0, size);
253 562
… …
279 return data - orig; 588 return data - orig;
280} 589}
281 590
282///////////////////////////////////////////////////////////////////////////// 591/////////////////////////////////////////////////////////////////////////////
283 592
593static
594u16 next_id ()
595{
596 static u16 dns_id = 0; // TODO: should be per-vpn
597
598#if 1
599 if (!dns_id)
600 dns_id = time (0);
601
602 // the simplest lsfr with periodicity 65535 i could find
603 dns_id = (dns_id << 1)
604 | (((dns_id >> 1)
605 ^ (dns_id >> 2)
606 ^ (dns_id >> 4)
607 ^ (dns_id >> 15)) & 1);
608
609 return dns_id;
610#else
611 dns_id++;//D
612
613 return htons (dns_id);
614#endif
615}
616
284struct dns_req 617struct dns_rcv;
618struct dns_snd;
619
620struct dns_connection
621{
622 connection *c;
623 struct vpn *vpn;
624
625 dns_cfg cfg;
626
627 bool established;
628 const basecoder *cdc;
629
630 tstamp last_received;
631 tstamp last_sent;
632 double min_latency;
633 double poll_interval, send_interval;
634
635 vector<dns_rcv *> rcvpq;
636
637 byte_stream rcvdq; int rcvseq; int repseq;
638 byte_stream snddq; int sndseq;
639
640 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
641 void receive_rep (dns_rcv *r);
642
643 void reset (); // quite like tcp RST
644 void set_cfg (); // to be called after any cfg changes
645
646 dns_connection (connection *c);
647 ~dns_connection ();
648};
649
650struct dns_snd
285{ 651{
286 dns_packet *pkt; 652 dns_packet *pkt;
287 tstamp next; 653 tstamp timeout, sent;
288 int retry; 654 int retry;
289 connection *conn; 655 struct dns_connection *dns;
656 int seqno;
657 bool stdhdr;
290 658
291 dns_req (connection *c, int seqno, byte_stream *stream); 659 void gen_stream_req (int seqno, byte_stream &stream);
660 void gen_syn_req ();
661
662 dns_snd (dns_connection *dns);
663 ~dns_snd ();
292}; 664};
293 665
294struct dns_rep 666dns_snd::dns_snd (dns_connection *dns)
667: dns (dns)
295{ 668{
296}; 669 timeout = 0;
297
298static u16 dns_id; // TODO: should be per-vpn
299
300dns_req::dns_req (connection *c, int seqno, byte_stream *stream)
301: conn (c)
302{
303 next = 0;
304 retry = 0; 670 retry = 0;
671 seqno = 0;
672 sent = ev_now ();
673 stdhdr = false;
305 674
306 pkt = new dns_packet; 675 pkt = new dns_packet;
307 676
308 pkt->id = dns_id++; 677 pkt->id = next_id ();
309 pkt->flags = DEFAULT_CLIENT_FLAGS; 678}
310 pkt->qdcount = htons (1);
311 pkt->ancount = 0;
312 pkt->nscount = 0;
313 pkt->arcount = 0;
314 679
315 int offs = 6*2; 680dns_snd::~dns_snd ()
316 int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length 681{
682 delete pkt;
683}
317 684
318 u8 lbl[64]; //D 685static void
319 char enc[65]; 686append_domain (dns_packet &pkt, int &offs, const char *domain)
320 int lbllen = 3; 687{
321 lbl[0] = c->conf->id; //D
322 lbl[1] = seqno >> 8; //D
323 lbl[2] = seqno; //D
324
325 while (dlen > 0)
326 {
327 int sndlen = dlen;
328
329 if (sndlen + lbllen > dns64::decode_len (MAX_LBL_SIZE))
330 sndlen = dns64::decode_len (MAX_LBL_SIZE) - lbllen;
331
332 if (sndlen > stream->size ())
333 sndlen = stream->size ();
334
335 if (sndlen + lbllen == 0)
336 break;
337
338 memcpy (lbl + lbllen, stream->begin (), sndlen);
339 stream->remove (sndlen);
340 lbllen += sndlen;
341
342 dns64::encode (enc, lbl, lbllen);
343
344 int elen = dns64::encode_len (lbllen);
345 (*pkt)[offs++] = elen;
346 memcpy (&((*pkt)[offs]), enc, elen);
347 offs += elen;
348 dlen -= elen + 1;
349
350 lbllen = 0;
351 }
352
353 const char *suffix = THISNODE->domain;
354
355 // add tunnel domain 688 // add tunnel domain
356 for (;;) 689 for (;;)
357 { 690 {
358 const char *end = strchr (suffix, '.'); 691 const char *end = strchr (domain, '.');
359 692
360 if (!end) 693 if (!end)
361 end = suffix + strlen (suffix); 694 end = domain + strlen (domain);
362 695
363 int len = end - suffix; 696 int len = end - domain;
364 697
365 (*pkt)[offs++] = len; 698 pkt [offs++] = len;
366 memcpy (&((*pkt)[offs]), suffix, len); 699 memcpy (pkt.at (offs), domain, len);
367 offs += len; 700 offs += len;
368 701
369 if (!*end) 702 if (!*end)
370 break; 703 break;
371 704
372 suffix = end + 1; 705 domain = end + 1;
706 }
707}
708
709void
710dns_snd::gen_stream_req (int seqno, byte_stream &stream)
711{
712 stdhdr = true;
713 this->seqno = seqno;
714
715 timeout = ev_now () + INITIAL_TIMEOUT;
716
717 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
718 pkt->qdcount = htons (1);
719
720 int offs = 6*2;
721 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
722 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
723 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
724
725 char enc[256], *encp = enc;
726 encode_header (enc, THISNODE->id, seqno);
727
728 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
729
730 if (datalen > stream.size ())
731 datalen = stream.size ();
732
733 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
734 stream.remove (datalen);
735
736 while (enclen)
373 } 737 {
738 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
739
740 (*pkt)[offs++] = lbllen;
741 memcpy (pkt->at (offs), encp, lbllen);
742
743 offs += lbllen;
744 encp += lbllen;
745
746 enclen -= lbllen;
747 }
748
749 append_domain (*pkt, offs, dns->c->conf->domain);
374 750
375 (*pkt)[offs++] = 0; 751 (*pkt)[offs++] = 0;
376 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 752 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 753 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378 754
379 pkt->len = offs; 755 pkt->len = offs;
756}
380 757
381 c->vpn->dns_sndpq.push_back (this); 758void
759dns_snd::gen_syn_req ()
760{
761 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
762
763 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
764 pkt->qdcount = htons (1);
765
766 int offs = 6 * 2;
767
768 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
769
770 assert (elen <= MAX_LBL_SIZE);
771
772 (*pkt)[offs] = elen;
773 offs += elen + 1;
774 append_domain (*pkt, offs, dns->c->conf->domain);
775
776 (*pkt)[offs++] = 0;
777 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
778 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
779
780 pkt->len = offs;
781}
782
783struct dns_rcv
784{
785 int seqno;
786 dns_packet *pkt; // reply packet
787 u8 data [MAXSIZE]; // actually part of the reply packet...
788 int datalen;
789
790 dns_rcv (int seqno, u8 *data, int datalen);
791 ~dns_rcv ();
792};
793
794dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
795: seqno (seqno), pkt (new dns_packet), datalen (datalen)
796{
797 memcpy (this->data, data, datalen);
798}
799
800dns_rcv::~dns_rcv ()
801{
802 delete pkt;
382} 803}
383 804
384///////////////////////////////////////////////////////////////////////////// 805/////////////////////////////////////////////////////////////////////////////
385 806
386struct dns_cfg 807dns_connection::dns_connection (connection *c)
808: c (c)
809, rcvdq (MAX_BACKLOG * 2)
810, snddq (MAX_BACKLOG)
387{ 811{
388 u8 id1, id2, id3; 812 tw.set<dns_connection, &dns_connection::time_cb> (this);
389 u8 def_ttl;
390 u8 unused1;
391 u16 max_size;
392 u8 flags1, flags2;
393};
394 813
395dns_packet * 814 vpn = c->vpn;
815
816 reset ();
817}
818
819dns_connection::~dns_connection ()
820{
821 reset ();
822}
823
824void
825dns_connection::reset ()
826{
827 while (!rcvpq.empty ())
828 {
829 delete rcvpq.back ();
830 rcvpq.pop_back ();
831 }
832
833 for (int i = vpn->dns_sndpq.size (); i--; )
834 if (vpn->dns_sndpq [i]->dns == this)
835 {
836 vpn->dns_sndpq [i] = vpn->dns_sndpq.back ();
837 vpn->dns_sndpq.pop_back ();
838 }
839
840 established = false;
841
842 rcvseq = repseq = sndseq = 0;
843
844 last_sent = 0;
845 poll_interval = 0.5; // starting here
846 send_interval = 0.5; // starting rate
847 min_latency = INITIAL_TIMEOUT;
848}
849
850void
851dns_connection::set_cfg ()
852{
853 cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62;
854}
855
856void
857dns_connection::receive_rep (dns_rcv *r)
858{
859 if (r->datalen)
860 poll_interval = max (poll_interval * (1. / 1.2), MIN_POLL_INTERVAL);
861 else
862 poll_interval = min (poll_interval * 1.1, MAX_POLL_INTERVAL);
863
864 rcvpq.push_back (r);
865
866 redo:
867
868 // find next packet
869 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
870 if (SEQNO_EQ (rcvseq, (*i)->seqno))
871 {
872 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
873 // enter the packet into our input stream
874 r = *i;
875
876 // remove the oldest packet, look forward, as it's oldest first
877 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
878 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
879 {
880 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
881 delete *j;
882 rcvpq.erase (j);
883 break;
884 }
885
886 rcvseq = (rcvseq + 1) & SEQNO_MASK;
887
888 if (!rcvdq.put (r->data, r->datalen))
889 {
890 // MUST never overflow, can be caused by data corruption, TODO
891 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
892 reset ();
893 return;
894 }
895
896 while (vpn_packet *pkt = rcvdq.get ())
897 {
898 sockinfo si;
899 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
900
901 vpn->recv_vpn_packet (pkt, si);
902 delete pkt;
903 }
904
905 // check for further packets
906 goto redo;
907 }
908}
909
910void
396vpn::dnsv4_server (dns_packet *pkt) 911vpn::dnsv4_server (dns_packet &pkt)
397{ 912{
398 u16 flags = ntohs (pkt->flags); 913 u16 flags = ntohs (pkt.flags);
399 914
400 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401 int offs = 6 * 2; // skip header 915 int offs = 6 * 2; // skip header
402 916
403 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 917 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404 918
405 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 919 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406 && pkt->qdcount == htons (1)) 920 && pkt.qdcount == htons (1))
407 { 921 {
408 char qname[MAXSIZE]; 922 char qname [MAXSIZE];
409 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 923 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410 924
411 printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", pkt->len,
412 pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
413
414 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 925 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 926 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416 927
417 pkt->qdcount = htons (1); 928 pkt.qdcount = htons (1);
418 pkt->ancount = 0; 929 pkt.ancount = 0;
419 pkt->nscount = 0; // should be self, as other nameservers reply like this 930 pkt.nscount = 0; // should be self, as other nameservers reply like this
420 pkt->arcount = 0; // a record for self, as other nameservers reply like this 931 pkt.arcount = 0; // a record for self, as other nameservers reply like this
421 932
422 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 933 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423 934
424 int dlen = strlen (THISNODE->domain); 935 int dlen = strlen (THISNODE->domain);
425 936
426 if (qclass == RR_CLASS_IN 937 if (qclass == RR_CLASS_IN
427 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428 && qlen > dlen + 1 938 && qlen > dlen + 1
429 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 939 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430 { 940 {
431 // correct class, domain, parse
432 u8 data[MAXSIZE];
433 int datalen = dns64::decode (data, qname, qlen - dlen - 1);
434
435 for (int i = 0; i < datalen; i++)
436 printf ("%02x ", data[i]);
437 printf ("\n");
438
439
440
441
442#if 0
443 // now generate reply 941 // now generate reply
444 rep->ancount = htons (1); // one answer RR 942 pkt.ancount = htons (1); // one answer RR
445 rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 943 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446 944
447 (*rep) [offs++] = 0xc0; 945 if ((qtype == RR_TYPE_ANY
448 (*rep) [offs++] = 6 * 2; // same as in query section 946 || qtype == RR_TYPE_TXT
449 947 || qtype == RR_TYPE_NULL)
450 (*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT; 948 && qlen > dlen + 1 + HDRSIZE)
451 (*rep) [offs++] = RR_CLASS_IN >> 8; (*rep) [offs++] = RR_CLASS_IN;
452
453 (*rep) [offs++] = 0; (*rep) [offs++] = 0;
454 (*rep) [offs++] = 0; (*rep) [offs++] = 0; // TTL
455
456 int dlen = MAX_PKT_SIZE - offs - 2;
457
458 printf ("we have room for %d bytes\n", dlen);
459
460 int rdlen_offs = offs += 2;
461
462 u8 txt[255];
463 txt[0] = 0;
464 txt[1] = 0;
465
466 int txtlen = 2;
467
468 while (dlen > 1)
469 { 949 {
470 int sndlen = --dlen; 950 // correct class, domain: parse
951 int client, seqno;
952 decode_header (qname, client, seqno);
471 953
472 if (sndlen + txtlen > 255) 954 if (0 < client && client <= conns.size ())
473 sndlen = 255 - txtlen; 955 {
956 connection *c = conns [client - 1];
957 dns_connection *dns = c->dns;
958 dns_rcv *rcv;
474 959
475 sndlen = 0; 960 if (dns)
961 {
962 u8 data[MAXSIZE];
963 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
476 964
477 (*rep)[offs++] = sndlen + txtlen; 965 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
478 memcpy (&((*rep)[offs]), txt, txtlen); 966 if (SEQNO_EQ ((*i)->seqno, seqno))
967 {
968 // already seen that request: simply reply with the cached reply
969 dns_rcv *r = *i;
970
971 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
972
973 // refresh header & id, as the retry count could have changed
974 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
975 r->pkt->id = pkt.id;
976
977 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
978
979 goto duplicate_request;
980 }
981
982 // new packet, queue
983 rcv = new dns_rcv (seqno, data, datalen);
984 dns->receive_rep (rcv);
985 }
986
987 {
988 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
989
990 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
991 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
992 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
993 pkt [offs++] = 0; pkt [offs++] = 0;
994 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
995
996 int rdlen_offs = offs += 2;
997
998 if (dns)
999 {
1000 int dlen = ntohs (dns->cfg.max_size) - offs;
1001
1002 // bind doesn't compress well, so reduce further by one label length
1003 dlen -= qlen;
1004
1005 // only put data into in-order sequence packets, if
1006 // we receive out-of-order packets we generate empty
1007 // replies
1008 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
1009 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
1010 {
1011 dns->repseq = seqno;
1012
1013 while (dlen > 1 && !dns->snddq.empty ())
1014 {
1015 int txtlen = dlen <= 255 ? dlen - 1 : 255;
1016
1017 if (txtlen > dns->snddq.size ())
1018 txtlen = dns->snddq.size ();
1019
1020 pkt[offs++] = txtlen;
1021 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
479 offs += txtlen; 1022 offs += txtlen;
1023 dns->snddq.remove (txtlen);
480 1024
481 //if (sndlen + txtlen > dns_snddq. 1025 dlen -= txtlen + 1;
1026 }
1027 }
1028
1029 // avoid completely empty TXT rdata
1030 if (offs == rdlen_offs)
1031 pkt[offs++] = 0;
1032
1033 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
1034 }
1035 else
1036 {
1037 // send RST
1038 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1039 pkt [offs++] = CMD_IP_RST;
1040 }
1041
1042 int rdlen = offs - rdlen_offs;
1043
1044 pkt [rdlen_offs - 2] = rdlen >> 8;
1045 pkt [rdlen_offs - 1] = rdlen;
1046
1047 if (dns)
1048 {
1049 // now update dns_rcv copy
1050 rcv->pkt->len = offs;
1051 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
1052 }
1053 }
1054
1055 duplicate_request: ;
1056 }
1057 else
1058 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
482 } 1059 }
1060 else if (qtype == RR_TYPE_A
1061 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
1062 {
1063 dns_cfg cfg;
1064 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
1065 int client = ntohs (cfg.client);
483 1066
484 int rdlen = offs - rdlen_offs; 1067 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485 1068
486 (*rep) [rdlen_offs - 2] = rdlen >> 8; 1069 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487 (*rep) [rdlen_offs - 1] = rdlen; 1070 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488#endif 1071 pkt [offs++] = 0; pkt [offs++] = 0;
1072 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1073 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
1074
1075 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1076 pkt [offs++] = CMD_IP_REJ;
1077
1078 if (0 < client && client <= conns.size ())
1079 {
1080 connection *c = conns [client - 1];
1081
1082 if (cfg.valid ())
1083 {
1084 slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc);
1085
1086 // check for any encoding mismatches - hints at a case problem
1087 char qname2 [MAX_ENC_LEN];
1088 cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg));
1089
1090 delete c->dns;
1091
1092 pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg)))
1093 ? CMD_IP_CSE : CMD_IP_SYN;
1094
1095 c->dns = new dns_connection (c);
1096 c->dns->cfg = cfg;
1097 c->dns->set_cfg ();
1098 }
1099 }
1100 }
489 } 1101 }
490 }
491 1102
492 pkt->len = offs; 1103 pkt.len = offs;
493 return pkt; 1104 }
494} 1105}
495 1106
496void 1107void
497vpn::dnsv4_client (dns_packet *pkt) 1108vpn::dnsv4_client (dns_packet &pkt)
498{ 1109{
499 u16 flags = ntohs (pkt->flags); 1110 u16 flags = ntohs (pkt.flags);
500 int offs = 6 * 2; // skip header 1111 int offs = 6 * 2; // skip header
501 1112
502 pkt->qdcount = ntohs (pkt->qdcount); 1113 pkt.qdcount = ntohs (pkt.qdcount);
503 pkt->ancount = ntohs (pkt->ancount); 1114 pkt.ancount = ntohs (pkt.ancount);
504 1115
1116 // go through our request list and find the corresponding request
505 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1117 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506 i != dns_sndpq.end (); 1118 i != dns_sndpq.end ();
507 ++i) 1119 ++i)
508 if ((*i)->pkt->id == pkt->id) 1120 if ((*i)->pkt->id == pkt.id)
509 { 1121 {
1122 dns_connection *dns = (*i)->dns;
510 connection *c = (*i)->conn; 1123 connection *c = dns->c;
511 printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D 1124 int seqno = (*i)->seqno;
1125 u8 data[MAXSIZE], *datap = data;
1126 //printf ("rcv pkt %x\n", seqno);//D
1127
1128 if ((*i)->retry)
1129 {
1130 dns->send_interval *= 1.01;
1131 if (dns->send_interval > MAX_SEND_INTERVAL)
1132 dns->send_interval = MAX_SEND_INTERVAL;
1133 }
1134 else
1135 {
1136#if 0
1137 dns->send_interval *= 0.999;
1138#endif
1139 // the latency surely puts an upper bound on
1140 // the minimum send interval
1141 double latency = ev_now () - (*i)->sent;
1142
1143 if (latency < dns->min_latency)
1144 dns->min_latency = latency;
1145
1146 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1147 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1148
1149 if (dns->send_interval < conf.dns_send_interval)
1150 dns->send_interval = conf.dns_send_interval;
1151 }
1152
512 delete *i; 1153 delete *i;
513 dns_sndpq.erase (i); 1154 dns_sndpq.erase (i);
514 1155
515 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1156 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516 { 1157 {
517 char qname[MAXSIZE]; 1158 char qname[MAXSIZE];
518 1159
519 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1160 while (pkt.qdcount-- && offs < MAXSIZE - 4)
520 { 1161 {
521 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1162 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522 offs += 4; // skip qtype, qclass 1163 offs += 4; // skip qtype, qclass
523 } 1164 }
524 1165
525 while (pkt->ancount-- && offs < MAXSIZE - 10) 1166 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526 { 1167 {
527 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1168 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528 1169
529 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1170 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1171 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531 u32 ttl = (*pkt) [offs++] << 24; 1172 u32 ttl = pkt [offs++] << 24;
532 ttl |= (*pkt) [offs++] << 16; 1173 ttl |= pkt [offs++] << 16;
533 ttl |= (*pkt) [offs++] << 8; 1174 ttl |= pkt [offs++] << 8;
534 ttl |= (*pkt) [offs++]; 1175 ttl |= pkt [offs++];
535
536 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1176 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537 1177
538 printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen); 1178 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
539
540 offs += rdlen;
541
542 if (MAXSIZE - offs < rdlen)
543 { 1179 {
1180 if (rdlen <= MAXSIZE - offs)
1181 {
544 // decode bytes, finally 1182 // decode bytes, finally
1183
1184 while (rdlen)
1185 {
1186 int txtlen = pkt [offs++];
1187
1188 assert (txtlen + offs < MAXSIZE - 1);
1189
1190 memcpy (datap, pkt.at (offs), txtlen);
1191 datap += txtlen; offs += txtlen;
1192
1193 rdlen -= txtlen + 1;
1194 }
1195 }
1196 }
1197 else if (qtype == RR_TYPE_A)
1198 {
1199 u8 ip [4];
1200
1201 ip [0] = pkt [offs++];
1202 ip [1] = pkt [offs++];
1203 ip [2] = pkt [offs++];
1204 ip [3] = pkt [offs++];
1205
1206 if (ip [0] == CMD_IP_1
1207 && ip [1] == CMD_IP_2
1208 && ip [2] == CMD_IP_3)
1209 {
1210 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1211
1212 if (ip [3] == CMD_IP_RST)
1213 {
1214 slog (L_DEBUG, _("DNS: got tunnel RST request."));
1215
1216 dns->reset ();
1217 return;
1218 }
1219 else if (ip [3] == CMD_IP_SYN)
1220 {
1221 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1222 dns->established = true;
1223 }
1224 else if (ip [3] == CMD_IP_CSE)
1225 {
1226 if (conf.dns_case_preserving)
1227 {
1228 slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol."));
1229 conf.dns_case_preserving = false;
1230 dns->reset ();
1231 return;
1232 }
1233 else
1234 {
1235 slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us."));
1236 dns->established = true;
1237 }
1238 }
1239 else if (ip [3] == CMD_IP_REJ)
1240 {
1241 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1242 dns->tw.start (60.);
1243 }
1244 else
1245 {
1246 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1247 dns->tw.start (60.);
1248 }
1249 }
1250 else
1251 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1252 ip [0], ip [1], ip [2], ip [3]);
1253
1254 return;
1255 }
1256
1257 int client, rseqno;
1258 decode_header (qname, client, rseqno);
1259
1260 if (client != THISNODE->id)
1261 {
1262 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1263 datap = 0;
1264 }
1265 else if (rseqno != seqno)
1266 {
1267 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1268 datap = 0;
545 } 1269 }
546 } 1270 }
547 } 1271 }
548 1272
1273 // todo: pkt now used
1274 if (datap)
1275 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
1276
549 break; 1277 break;
550 } 1278 }
551} 1279}
552 1280
553void 1281void
554vpn::dnsv4_ev (io_watcher &w, short revents) 1282vpn::dnsv4_ev (ev::io &w, int revents)
555{ 1283{
556 if (revents & EVENT_READ) 1284 if (revents & EV_READ)
557 { 1285 {
558 dns_packet *pkt = new dns_packet; 1286 dns_packet *pkt = new dns_packet;
559 struct sockaddr_in sa; 1287 struct sockaddr_in sa;
560 socklen_t sa_len = sizeof (sa); 1288 socklen_t sa_len = sizeof (sa);
561 1289
562 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1290 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563 1291
564 if (pkt->len > 0) 1292 if (pkt->len > 0)
565 if (THISNODE->dns_port)
566 { 1293 {
567 pkt = dnsv4_server (pkt); 1294 if (ntohs (pkt->flags) & FLAG_RESPONSE)
568 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
569 }
570 else
571 dnsv4_client (pkt); 1295 dnsv4_client (*pkt);
1296 else
1297 {
1298 dnsv4_server (*pkt);
1299 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1300 }
1301
1302 delete pkt;
1303 }
572 } 1304 }
573} 1305}
574 1306
575bool 1307bool
576connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1308vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577{ 1309{
578 // never initialized 1310 int client = ntohl (si.host);
579 if (!dns_snddq && !dns_rcvdq)
580 {
581 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
582 dns_snddq = new byte_stream (MAX_BACKLOG);
583 1311
584 dns_rcvseq = dns_sndseq = 0; 1312 assert (0 < client && client <= conns.size ());
585 1313
586 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1314 connection *c = conns [client - 1];
587 } 1315
1316 if (!c->dns)
1317 c->dns = new dns_connection (c);
588 1318
589 if (!dns_snddq->put (pkt)) 1319 if (c->dns->snddq.put (pkt))
590 return false; 1320 {
1321 min_it (c->dns->poll_interval, 0.25);
1322 c->dns->tw ();
1323 }
591 1324
592 // start timer if neccessary 1325 // always return true even if the buffer overflows
593 if (!dnsv4_tw.active)
594 dnsv4_cb (dnsv4_tw);
595
596 return true; 1326 return true;
597} 1327}
598 1328
599void 1329void
600connection::dnsv4_cb (time_watcher &w) 1330dns_connection::time_cb (ev::timer &w, int revents)
601{ 1331{
1332 // servers have to be polled
1333 if (THISNODE->dns_port)
1334 return;
1335
602 // check for timeouts and (re)transmit 1336 // check for timeouts and (re)transmit
603 tstamp next = NOW + 60; 1337 tstamp next = 86400 * 365;
604 dns_req *send = 0; 1338 dns_snd *send = 0;
605 1339
606 slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), vpn->dns_sndpq.size ());
607
608 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1340 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609 i != vpn->dns_sndpq.end (); 1341 i != vpn->dns_sndpq.end ();
610 ++i) 1342 ++i)
611 { 1343 {
612 dns_req *r = *i; 1344 dns_snd *r = *i;
613 1345
614 if (r->next <= NOW) 1346 if (r->timeout <= ev_now ())
615 { 1347 {
616 if (!send) 1348 if (!send)
617 { 1349 {
618 send = r; 1350 send = r;
619 1351
620 slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621 r->retry++; 1352 r->retry++;
622 r->next = NOW + r->retry; 1353 r->timeout = ev_now () + r->retry * min_latency * conf.dns_timeout_factor;
1354 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1355
1356 // the following code changes the query section a bit, forcing
1357 // the forwarder to generate a new request
1358 if (r->stdhdr)
1359 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
623 } 1360 }
624 } 1361 }
625 1362 else
626 if (r->next < next) 1363 min_it (next, r->timeout - ev_now ());
627 next = r->next;
628 } 1364 }
629 1365
630 if (!send 1366 if (!send)
631 && vpn->dns_sndpq.size () < MAX_OUTSTANDING) 1367 {
632 send = new dns_req (this, dns_sndseq++, dns_snddq); 1368 // generate a new packet, if wise
633 1369
634 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE); 1370 if (!established)
1371 {
1372 if (vpn->dns_sndpq.empty ())
1373 {
1374 send = new dns_snd (this);
1375
1376 cfg.reset (THISNODE->id);
1377 set_cfg ();
1378 send->gen_syn_req ();
1379 }
1380 }
1381 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1382 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1383 {
1384 if (last_sent + send_interval <= ev_now ())
1385 {
1386 //printf ("sending data request etc.\n"); //D
1387 if (!snddq.empty ())
1388 min_it (next, send_interval);
1389
1390 send = new dns_snd (this);
1391 send->gen_stream_req (sndseq, snddq);
1392 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1393 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1394
1395 sndseq = (sndseq + 1) & SEQNO_MASK;
1396 }
1397 else
1398 min_it (next, last_sent + send_interval - ev_now ());
1399 }
1400
1401 if (send)
1402 vpn->dns_sndpq.push_back (send);
1403 }
635 1404
636 if (send) 1405 if (send)
637 { 1406 {
638 dns_packet *pkt = send->pkt; 1407 last_sent = ev_now ();
639 1408 sendto (vpn->dnsv4_fd,
640 next = min_next; 1409 send->pkt->at (0), send->pkt->len, 0,
641 1410 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
642 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
643 } 1411 }
644 else if (next < min_next) 1412
645 next = min_next; 1413 min_it (next, last_sent + max (poll_interval, send_interval) - ev_now ());
1414
1415 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1416 poll_interval, send_interval, next - ev_now (),
1417 vpn->dns_sndpq.size (), snddq.size (),
1418 rcvpq.size ());
646 1419
647 w.start (next); 1420 w.start (next);
648} 1421}
649 1422
650#endif 1423#endif

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