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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.5 by pcg, Thu Mar 3 07:24:57 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) 2003-2004 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 40 // 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 1000 // requests/s
50#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
51 74
52#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
53// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
54// every two request byte sless give room for one reply byte 77// every request byte less give room for two reply bytes
55 78
56#define SEQNO_MASK 0xffff 79#define SEQNO_MASK 0x3fff
57 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
58/*
59
60protocol, in shorthand :)
61
62client -> server <req> ANY?
63server -> client <req> TXT <rep>
64
65<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
66<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
67
68if <client-id> is zero, the connection will be configured:
69
70<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
71
72*/
73 81
74#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
75#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
76 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
77#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
78#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
79#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
80 92
81// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 93#define CMD_IP_1 207
82struct dns64 94#define CMD_IP_2 46
83{ 95#define CMD_IP_3 236
84 static const char encode_chars[64 + 1];
85 static s8 decode_chars[256];
86 96
87 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 97#define CMD_IP_RST 29 // some error, reset and retry
88 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
89 static int encode (char *dst, u8 *src, int len); 163 unsigned int encode (char *dst, u8 *src, unsigned int len) const;
90 static int decode (u8 *dst, char *src, int len); 164 unsigned int decode (u8 *dst, char *src, unsigned int len) const;
91 165
92 dns64 (); 166 basecoder (const char *cmap);
93} dns64; 167};
94 168
95const char dns64::encode_chars[64 + 1] = "_4B9dLphHzrqQmGjkTbJt5svlZX8xSaReEYfwKgF1DP2W6NyVOU70IouACcMn3i-"; 169basecoder::basecoder (const char *cmap)
96s8 dns64::decode_chars[256]; 170: cmap (cmap)
97
98dns64::dns64 ()
99{ 171{
100 for (int i = 0; i < 64; i++) 172 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
101 decode_chars [encode_chars [i]] = i + 1; 173 {
102} 174 u8 src [MAX_DEC_LEN];
175 u8 dst [MAX_ENC_LEN];
103 176
104int 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
105{ 195{
106 // slow, but easy to debug 196 return enc_len [len];
107 char *beg = dst; 197}
108 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;
109 246
110 while (len--) 247 while (len--)
111 { 248 {
112 accum <<= 8; 249 u8 val = cmap.decode [(u8)*src++];
113 accum |= *src++;
114 bits += 8;
115 250
116 while (bits >= 6) 251 if (val != charmap::INVALID)
117 { 252 src_ [elen++] = val;
118 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 253 }
119 bits -= 6; 254
120 } 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)
121 } 266 {
267 memset (dst, 0, dlen - n);
268 memcpy (dst + dlen - n, dst_, n);
269 }
270 else
271 memcpy (dst, dst_ + n - dlen, dlen);
122 272
123 if (bits) 273 return dlen;
124 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
125
126 return dst - beg;
127} 274}
128 275
129int dns64::decode (u8 *dst, char *src, int len) 276#if 0
130{ 277struct test { test (); } test;
131 // slow, but easy to debug
132 u8 *beg = dst;
133 unsigned int accum, bits = 0;
134 278
135 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++)
136 { 288 {
137 s8 chr = decode_chars [(u8)*src++]; 289 int elen = cdc.encode (enc, in, i);
290 int dlen = cdc.decode (dec, enc, elen);
138 291
139 if (!chr) 292 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
140 continue;
141
142 accum <<= 6;
143 accum |= chr - 1;
144 bits += 6;
145
146 while (bits >= 8)
147 {
148 *dst++ = accum >> (bits - 8);
149 bits -= 8;
150 }
151 } 293 }
294 abort ();
295}
296#endif
152 297
153 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;
154} 331}
155 332
156///////////////////////////////////////////////////////////////////////////// 333/////////////////////////////////////////////////////////////////////////////
157 334
158struct byte_stream 335struct byte_stream
… …
184byte_stream::~byte_stream () 361byte_stream::~byte_stream ()
185{ 362{
186 delete data; 363 delete data;
187} 364}
188 365
366void
189void byte_stream::remove (int count) 367byte_stream::remove (int count)
190{ 368{
191 if (count > fill) 369 if (count > fill)
192 abort (); 370 assert (count <= fill);
193 371
194 memmove (data, data + count, fill -= count); 372 memmove (data, data + count, fill -= count);
195} 373}
196 374
375bool
197bool byte_stream::put (u8 *data, unsigned int datalen) 376byte_stream::put (u8 *data, unsigned int datalen)
198{ 377{
199 if (maxsize - fill < datalen) 378 if (maxsize - fill < datalen)
200 return false; 379 return false;
201 380
202 memcpy (this->data + fill, data, datalen); fill += datalen; 381 memcpy (this->data + fill, data, datalen); fill += datalen;
203 382
204 return true; 383 return true;
205} 384}
206 385
386bool
207bool byte_stream::put (vpn_packet *pkt) 387byte_stream::put (vpn_packet *pkt)
208{ 388{
209 if (maxsize - fill < pkt->len + 2) 389 if (maxsize - fill < pkt->len + 2)
210 return false; 390 return false;
211 391
212 data [fill++] = pkt->len >> 8; 392 data [fill++] = pkt->len >> 8;
213 data [fill++] = pkt->len; 393 data [fill++] = pkt->len;
214 394
215 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 395 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
216 396
217 return true; 397 return true;
218} 398}
219 399
220vpn_packet *byte_stream::get () 400vpn_packet *byte_stream::get ()
221{ 401{
402 unsigned int len;
403
404 for (;;)
405 {
222 int len = (data [0] << 8) | data [1]; 406 len = (data [0] << 8) | data [1];
223 407
224 printf ("get len %d, fill %d\n", len, fill);//D
225
226 if (len > MAXSIZE && fill >= 2) 408 if (len <= MAXSIZE || fill < 2)
227 abort (); // TODO handle this gracefully, connection reset 409 break;
228 410
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
229 if (fill < len + 2) 416 if (fill < len + 2)
230 return 0; 417 return 0;
231 418
232 vpn_packet *pkt = new vpn_packet; 419 vpn_packet *pkt = new vpn_packet;
233 420
234 pkt->len = len; 421 pkt->len = len;
235 memcpy (&((*pkt)[0]), data + 2, len); 422 memcpy (pkt->at (0), data + 2, len);
236 remove (len + 2); 423 remove (len + 2);
237 424
238 return pkt; 425 return pkt;
239} 426}
240 427
241///////////////////////////////////////////////////////////////////////////// 428/////////////////////////////////////////////////////////////////////////////
242 429
243#define FLAG_QUERY ( 0 << 15) 430#define FLAG_QUERY ( 0 << 15)
244#define FLAG_RESPONSE ( 1 << 15) 431#define FLAG_RESPONSE ( 1 << 15)
245#define FLAG_OP_MASK (15 << 14) 432#define FLAG_OP_MASK (15 << 11)
246#define FLAG_OP_QUERY ( 0 << 11) 433#define FLAG_OP_QUERY ( 0 << 11)
247#define FLAG_AA ( 1 << 10) 434#define FLAG_AA ( 1 << 10)
248#define FLAG_TC ( 1 << 9) 435#define FLAG_TC ( 1 << 9)
249#define FLAG_RD ( 1 << 8) 436#define FLAG_RD ( 1 << 8)
250#define FLAG_RA ( 1 << 7) 437#define FLAG_RA ( 1 << 7)
… …
257#define FLAG_RCODE_REFUSED ( 5 << 0) 444#define FLAG_RCODE_REFUSED ( 5 << 0)
258 445
259#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 446#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
260#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)
261 448
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
262struct dns_packet : net_packet 542struct dns_packet : net_packet
263{ 543{
264 u16 id; 544 u16 id;
265 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
266 u16 qdcount, ancount, nscount, arcount; 546 u16 qdcount, ancount, nscount, arcount;
267 547
268 u8 data[MAXSIZE - 6 * 2]; 548 u8 data [MAXSIZE - 6 * 2];
269 549
270 int decode_label (char *data, int size, int &offs); 550 int decode_label (char *data, int size, int &offs);
271}; 551};
272 552
553int
273int dns_packet::decode_label (char *data, int size, int &offs) 554dns_packet::decode_label (char *data, int size, int &offs)
274{ 555{
275 char *orig = data; 556 char *orig = data;
276 557
277 memset (data, 0, size); 558 memset (data, 0, size);
278 559
… …
304 return data - orig; 585 return data - orig;
305} 586}
306 587
307///////////////////////////////////////////////////////////////////////////// 588/////////////////////////////////////////////////////////////////////////////
308 589
309struct dns_req 590static
591u16 next_id ()
310{ 592{
311 dns_packet *pkt;
312 tstamp next;
313 int retry;
314 connection *conn;
315 int seqno;
316
317 dns_req (connection *c);
318 void gen_stream_req (int seqno, byte_stream *stream);
319};
320
321static u16 dns_id = 12098; // TODO: should be per-vpn 593 static u16 dns_id = 0; // TODO: should be per-vpn
322 594
323static u16 next_id () 595#if 1
324{ 596 if (!dns_id)
597 dns_id = time (0);
598
325 // the simplest lsfr with periodicity 65535 i could find 599 // the simplest lsfr with periodicity 65535 i could find
326 dns_id = (dns_id << 1) 600 dns_id = (dns_id << 1)
327 | (((dns_id >> 1) 601 | (((dns_id >> 1)
328 ^ (dns_id >> 2) 602 ^ (dns_id >> 2)
329 ^ (dns_id >> 4) 603 ^ (dns_id >> 4)
330 ^ (dns_id >> 15)) & 1); 604 ^ (dns_id >> 15)) & 1);
331 605
332 return dns_id; 606 return dns_id;
333} 607#else
608 dns_id++;//D
334 609
335dns_req::dns_req (connection *c) 610 return htons (dns_id);
336: conn (c) 611#endif
612}
613
614struct dns_rcv;
615struct dns_snd;
616
617struct dns_connection
337{ 618{
338 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;
339 retry = 0; 667 retry = 0;
668 seqno = 0;
669 sent = ev_now ();
670 stdhdr = false;
340 671
341 pkt = new dns_packet; 672 pkt = new dns_packet;
342 673
343 pkt->id = next_id (); 674 pkt->id = next_id ();
344} 675}
345 676
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
346void dns_req::gen_stream_req (int seqno, byte_stream *stream) 707dns_snd::gen_stream_req (int seqno, byte_stream &stream)
347{ 708{
709 stdhdr = true;
348 this->seqno = seqno; 710 this->seqno = seqno;
711
712 timeout = ev_now () + INITIAL_TIMEOUT;
349 713
350 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 714 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
351 pkt->qdcount = htons (1); 715 pkt->qdcount = htons (1);
352 716
353 int offs = 6*2; 717 int offs = 6*2;
354 int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2; 718 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
355 // 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,
356 // 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
357 721
358 u8 data[256]; //TODO
359
360 data[0] = THISNODE->id; //TODO
361 data[1] = seqno >> 8; //TODO
362 data[2] = seqno; //TODO
363
364 int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
365
366 if (datalen > stream->size ())
367 datalen = stream->size ();
368
369 char enc[256], *encp = enc; 722 char enc[256], *encp = enc;
370 723 encode_header (enc, THISNODE->id, seqno);
371 memcpy (data + 3, stream->begin (), datalen); 724
372 int enclen = dns64::encode (enc, data, datalen + 3); 725 int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
726
727 if (datalen > stream.size ())
728 datalen = stream.size ();
729
730 int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
373 stream->remove (datalen); 731 stream.remove (datalen);
374 732
375 while (enclen) 733 while (enclen)
376 { 734 {
377 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 735 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
378 736
… …
383 encp += lbllen; 741 encp += lbllen;
384 742
385 enclen -= lbllen; 743 enclen -= lbllen;
386 } 744 }
387 745
388 const char *suffix = THISNODE->domain; 746 append_domain (*pkt, offs, dns->c->conf->domain);
389
390 // add tunnel domain
391 for (;;)
392 {
393 const char *end = strchr (suffix, '.');
394
395 if (!end)
396 end = suffix + strlen (suffix);
397
398 int len = end - suffix;
399
400 (*pkt)[offs++] = len;
401 memcpy (&((*pkt)[offs]), suffix, len);
402 offs += len;
403
404 if (!*end)
405 break;
406
407 suffix = end + 1;
408 }
409 747
410 (*pkt)[offs++] = 0; 748 (*pkt)[offs++] = 0;
411 (*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;
412 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 775 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
413 776
414 pkt->len = offs; 777 pkt->len = offs;
415} 778}
416 779
… …
419 int seqno; 782 int seqno;
420 dns_packet *pkt; // reply packet 783 dns_packet *pkt; // reply packet
421 u8 data [MAXSIZE]; // actually part of the reply packet... 784 u8 data [MAXSIZE]; // actually part of the reply packet...
422 int datalen; 785 int datalen;
423 786
424 dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen); 787 dns_rcv (int seqno, u8 *data, int datalen);
425 ~dns_rcv (); 788 ~dns_rcv ();
426}; 789};
427 790
428dns_rcv::dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen) 791dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
429: seqno (seqno), pkt (new dns_packet), datalen (datalen) 792: seqno (seqno), pkt (new dns_packet), datalen (datalen)
430{ 793{
431 memcpy (this->data, data, datalen); 794 memcpy (this->data, data, datalen);
432 pkt->len = req->len;
433 memcpy (pkt->at (0), req->at (0), req->len);
434} 795}
435 796
436dns_rcv::~dns_rcv () 797dns_rcv::~dns_rcv ()
437{ 798{
438 delete pkt; 799 delete pkt;
439} 800}
440 801
441///////////////////////////////////////////////////////////////////////////// 802/////////////////////////////////////////////////////////////////////////////
442 803
443struct dns_cfg 804dns_connection::dns_connection (connection *c)
805: c (c)
806, rcvdq (MAX_BACKLOG * 2)
807, snddq (MAX_BACKLOG)
444{ 808{
445 u8 id1, id2, id3; 809 tw.set<dns_connection, &dns_connection::time_cb> (this);
446 u8 def_ttl;
447 u8 unused1;
448 u16 max_size;
449 u8 flags1, flags2;
450};
451 810
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
452void connection::dnsv4_receive_rep (struct dns_rcv *r) 854dns_connection::receive_rep (dns_rcv *r)
453{ 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
454 dns_rcvpq.push_back (r); 861 rcvpq.push_back (r);
455 862
456 redo: 863 redo:
457 864
865 // find next packet
458 for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin (); 866 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
459 i != dns_rcvpq.end ();
460 ++i)
461 if (dns_rcvseq == (*i)->seqno) 867 if (SEQNO_EQ (rcvseq, (*i)->seqno))
462 { 868 {
869 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
870 // enter the packet into our input stream
463 dns_rcv *r = *i; 871 r = *i;
464 872
873 // remove the oldest packet, look forward, as it's oldest first
874 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
875 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
876 {
877 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
878 delete *j;
879 rcvpq.erase (j);
880 break;
881 }
882
465 dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; 883 rcvseq = (rcvseq + 1) & SEQNO_MASK;
466 884
467 if (!dns_snddq && !dns_rcvdq) 885 if (!rcvdq.put (r->data, r->datalen))
468 { 886 {
469 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); 887 // MUST never overflow, can be caused by data corruption, TODO
470 dns_snddq = new byte_stream (MAX_BACKLOG); 888 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
471 889 reset ();
472 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 890 return;
473 } 891 }
474 892
475 if (!dns_rcvdq->put (r->data, r->datalen))
476 abort (); // MUST never overflow, can be caused by data corruption, TODO
477
478 while (vpn_packet *pkt = dns_rcvdq->get ()) 893 while (vpn_packet *pkt = rcvdq.get ())
479 { 894 {
480 sockinfo si; 895 sockinfo si;
481 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 896 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
482 897
483 vpn->recv_vpn_packet (pkt, si); 898 vpn->recv_vpn_packet (pkt, si);
899 delete pkt;
484 } 900 }
485 } 901
486 else if ((u32)dns_rcvseq - MAX_WINDOW - (u32)(*i)->seqno < MAX_WINDOW * 2) 902 // check for further packets
487 {
488 dns_rcvpq.erase (i);
489 goto redo; 903 goto redo;
490 } 904 }
491} 905}
492 906
493dns_packet * 907void
494vpn::dnsv4_server (dns_packet *pkt) 908vpn::dnsv4_server (dns_packet &pkt)
495{ 909{
496 u16 flags = ntohs (pkt->flags); 910 u16 flags = ntohs (pkt.flags);
497 911
498 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
499 int offs = 6 * 2; // skip header 912 int offs = 6 * 2; // skip header
500 913
501 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 914 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
502 915
503 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 916 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
504 && pkt->qdcount == htons (1)) 917 && pkt.qdcount == htons (1))
505 { 918 {
506 char qname[MAXSIZE]; 919 char qname [MAXSIZE];
507 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 920 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
508 921
509 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 922 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
510 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 923 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
511 924
512 pkt->qdcount = htons (1); 925 pkt.qdcount = htons (1);
513 pkt->ancount = 0; 926 pkt.ancount = 0;
514 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
515 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
516 929
517 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 930 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
518 931
519 int dlen = strlen (THISNODE->domain); 932 int dlen = strlen (THISNODE->domain);
520 933
521 if (qclass == RR_CLASS_IN 934 if (qclass == RR_CLASS_IN
522 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
523 && qlen > dlen + 1 935 && qlen > dlen + 1
524 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 936 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
525 { 937 {
526 // correct class, domain: parse 938 // now generate reply
527 u8 data[MAXSIZE]; 939 pkt.ancount = htons (1); // one answer RR
528 int datalen = dns64::decode (data, qname, qlen - dlen - 1); 940 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
529 941
530 int client = data[0]; 942 if ((qtype == RR_TYPE_ANY
531 int seqno = ((data[1] << 8) | data[2]) & SEQNO_MASK; 943 || qtype == RR_TYPE_TXT
532 944 || qtype == RR_TYPE_NULL)
533 if (0 < client && client <= conns.size ()) 945 && qlen > dlen + 1 + HDRSIZE)
534 { 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 {
535 connection *c = conns [client - 1]; 953 connection *c = conns [client - 1];
954 dns_connection *dns = c->dns;
955 dns_rcv *rcv;
536 956
537 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin (); 957 if (dns)
538 i != c->dns_rcvpq.end ();
539 ++i) 958 {
959 u8 data[MAXSIZE];
960 int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
961
962 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
540 if ((*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
541 { 984 {
542 // already seen that request, just reply with the original reply 985 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
543 dns_rcv *r = *i;
544 986
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
992
993 int rdlen_offs = offs += 2;
994
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
545 offs = r->pkt->len; 1047 rcv->pkt->len = offs;
546 memcpy (pkt->at (0), r->pkt->at (0), offs); 1048 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
547 goto duplicate_request; 1049 }
548 } 1050 }
549 1051
550 // new packet, queue 1052 duplicate_request: ;
551 c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data + 3, datalen - 3)); 1053 }
552 1054 else
553 // now generate reply
554 pkt->ancount = htons (1); // one answer RR
555 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);
556 1063
557 (*pkt) [offs++] = 0xc0;
558 (*pkt) [offs++] = 6 * 2; // same as in query section 1064 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
559 1065
560 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1066 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
561 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1067 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
562
563 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1068 pkt [offs++] = 0; pkt [offs++] = 0;
564 (*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
565 1071
566 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;
567 1074
568 // bind doesn't compress well, so reduce further by one label length 1075 if (0 < client && client <= conns.size ())
569 dlen -= qlen;
570
571 int rdlen_offs = offs += 2;
572
573 while (c->dns_snddq
574 && !c->dns_snddq->empty ()
575 && dlen > 1)
576 { 1076 {
577 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1077 connection *c = conns [client - 1];
578 1078
579 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;
580 txtlen = c->dns_snddq->size (); 1094 c->dns->set_cfg ();
581 1095 }
582 (*pkt)[offs++] = txtlen;
583 memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);
584 offs += txtlen;
585 c->dns_snddq->remove (txtlen);
586
587 dlen -= txtlen + 1;
588 } 1096 }
589
590 // avoid empty TXT rdata
591 if (offs == rdlen_offs)
592 (*pkt)[offs++] = 0;
593
594 int rdlen = offs - rdlen_offs;
595
596 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
597 (*pkt) [rdlen_offs - 1] = rdlen;
598
599 duplicate_request: ;
600 } 1097 }
601 else
602 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
603 } 1098 }
604 }
605 else
606 offs = pkt->len;
607 1099
608 pkt->len = offs; 1100 pkt.len = offs;
609 return pkt; 1101 }
610} 1102}
611 1103
612void 1104void
613vpn::dnsv4_client (dns_packet *pkt) 1105vpn::dnsv4_client (dns_packet &pkt)
614{ 1106{
615 u16 flags = ntohs (pkt->flags); 1107 u16 flags = ntohs (pkt.flags);
616 int offs = 6 * 2; // skip header 1108 int offs = 6 * 2; // skip header
617 1109
618 pkt->qdcount = ntohs (pkt->qdcount); 1110 pkt.qdcount = ntohs (pkt.qdcount);
619 pkt->ancount = ntohs (pkt->ancount); 1111 pkt.ancount = ntohs (pkt.ancount);
620 1112
621 // go through our request list and find the corresponding request 1113 // go through our request list and find the corresponding request
622 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1114 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
623 i != dns_sndpq.end (); 1115 i != dns_sndpq.end ();
624 ++i) 1116 ++i)
625 if ((*i)->pkt->id == pkt->id) 1117 if ((*i)->pkt->id == pkt.id)
626 { 1118 {
1119 dns_connection *dns = (*i)->dns;
627 connection *c = (*i)->conn; 1120 connection *c = dns->c;
628 int seqno = (*i)->seqno; 1121 int seqno = (*i)->seqno;
629 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 }
630 1149
631 delete *i; 1150 delete *i;
632 dns_sndpq.erase (i); 1151 dns_sndpq.erase (i);
633 1152
634 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1153 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
635 { 1154 {
636 char qname[MAXSIZE]; 1155 char qname[MAXSIZE];
637 1156
638 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1157 while (pkt.qdcount-- && offs < MAXSIZE - 4)
639 { 1158 {
640 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1159 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
641 offs += 4; // skip qtype, qclass 1160 offs += 4; // skip qtype, qclass
642 } 1161 }
643 1162
644 while (pkt->ancount-- && offs < MAXSIZE - 10) 1163 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
645 { 1164 {
646 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1165 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
647 1166
648 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1167 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
649 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1168 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
650 u32 ttl = (*pkt) [offs++] << 24; 1169 u32 ttl = pkt [offs++] << 24;
651 ttl |= (*pkt) [offs++] << 16; 1170 ttl |= pkt [offs++] << 16;
652 ttl |= (*pkt) [offs++] << 8; 1171 ttl |= pkt [offs++] << 8;
653 ttl |= (*pkt) [offs++]; 1172 ttl |= pkt [offs++];
654
655 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1173 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
656 1174
657 if (rdlen <= MAXSIZE - offs) 1175 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype)
658 { 1176 {
659 // decode bytes, finally 1177 if (rdlen <= MAXSIZE - offs)
660
661 while (rdlen)
662 { 1178 {
1179 // decode bytes, finally
1180
1181 while (rdlen)
1182 {
663 int txtlen = (*pkt) [offs++]; 1183 int txtlen = pkt [offs++];
664 1184
665 assert (txtlen + offs < MAXSIZE - 1); 1185 assert (txtlen + offs < MAXSIZE - 1);
666 1186
667 memcpy (datap, pkt->at (offs), txtlen); 1187 memcpy (datap, pkt.at (offs), txtlen);
668 datap += txtlen; offs += txtlen; 1188 datap += txtlen; offs += txtlen;
669 1189
670 rdlen -= txtlen + 1; 1190 rdlen -= txtlen + 1;
1191 }
671 } 1192 }
672
673 } 1193 }
1194 else if (qtype == RR_TYPE_A)
1195 {
1196 u8 ip [4];
674 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 }
675 } 1267 }
676 } 1268 }
677 1269
1270 // todo: pkt now used
678 if (datap != data) 1271 if (datap)
679 printf ("%02x %02x %02x %02x\n",
680 data[0],
681 data[1],
682 data[2],
683 data[3]);
684
685 printf ("recv %d,%d\n", pkt->id, seqno, datap - data);//D
686 c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data, datap - data)); 1272 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
687 1273
688 break; 1274 break;
689 } 1275 }
690
691 delete pkt;
692} 1276}
693 1277
694void 1278void
695vpn::dnsv4_ev (io_watcher &w, short revents) 1279vpn::dnsv4_ev (ev::io &w, int revents)
696{ 1280{
697 if (revents & EVENT_READ) 1281 if (revents & EV_READ)
698 { 1282 {
699 dns_packet *pkt = new dns_packet; 1283 dns_packet *pkt = new dns_packet;
700 struct sockaddr_in sa; 1284 struct sockaddr_in sa;
701 socklen_t sa_len = sizeof (sa); 1285 socklen_t sa_len = sizeof (sa);
702 1286
703 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);
704 1288
705 if (pkt->len > 0) 1289 if (pkt->len > 0)
706 { 1290 {
707 if (pkt->flags & htons (FLAG_TC)) 1291 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1292 dnsv4_client (*pkt);
1293 else
708 { 1294 {
709 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1295 dnsv4_server (*pkt);
710 //TODO connection reset 1296 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
711 } 1297 }
712 1298
713 if (THISNODE->dns_port) 1299 delete pkt;
714 {
715 pkt = dnsv4_server (pkt);
716 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
717 }
718 else
719 dnsv4_client (pkt);
720 } 1300 }
721 } 1301 }
722} 1302}
723 1303
724bool 1304bool
725connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1305vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
726{ 1306{
727 // never initialized 1307 int client = ntohl (si.host);
728 if (!dns_snddq && !dns_rcvdq)
729 {
730 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
731 dns_snddq = new byte_stream (MAX_BACKLOG);
732 1308
733 //dns_rcvseq = dns_sndseq = 0; 1309 assert (0 < client && client <= conns.size ());
734 1310
735 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1311 connection *c = conns [client - 1];
736 } 1312
1313 if (!c->dns)
1314 c->dns = new dns_connection (c);
737 1315
738 if (!dns_snddq->put (pkt)) 1316 if (c->dns->snddq.put (pkt))
739 return false; 1317 {
1318 min_it (c->dns->poll_interval, 0.25);
1319 c->dns->tw ();
1320 }
740 1321
741 // start timer if neccessary 1322 // always return true even if the buffer overflows
742 if (!THISNODE->dns_port && !dnsv4_tw.active)
743 dnsv4_cb (dnsv4_tw);
744
745 return true; 1323 return true;
746} 1324}
747 1325
748void 1326void
749connection::dnsv4_cb (time_watcher &w) 1327dns_connection::time_cb (ev::timer &w, int revents)
750{ 1328{
1329 // servers have to be polled
1330 if (THISNODE->dns_port)
1331 return;
1332
751 // check for timeouts and (re)transmit 1333 // check for timeouts and (re)transmit
752 tstamp next = NOW + 60; 1334 tstamp next = 86400 * 365;
753 dns_req *send = 0; 1335 dns_snd *send = 0;
754 1336
755 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1337 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
756 i != vpn->dns_sndpq.end (); 1338 i != vpn->dns_sndpq.end ();
757 ++i) 1339 ++i)
758 { 1340 {
759 dns_req *r = *i; 1341 dns_snd *r = *i;
760 1342
761 if (r->next <= NOW) 1343 if (r->timeout <= ev_now ())
762 { 1344 {
763 if (!send) 1345 if (!send)
764 { 1346 {
765 send = r; 1347 send = r;
766 1348
767 if (r->retry)//D
768 printf ("req %d, retry %d\n", r->pkt->id, r->retry);
769 r->retry++; 1349 r->retry++;
770 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);
771 } 1357 }
772 } 1358 }
773 1359 else
774 if (r->next < next) 1360 min_it (next, r->timeout - ev_now ());
775 next = r->next;
776 } 1361 }
777 1362
778 if (!send 1363 if (!send)
779 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
780 { 1364 {
1365 // generate a new packet, if wise
1366
1367 if (!established)
1368 {
1369 if (vpn->dns_sndpq.empty ())
1370 {
781 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);
782 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)
783 vpn->dns_sndpq.push_back (send); 1399 vpn->dns_sndpq.push_back (send);
784
785 dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
786 } 1400 }
787
788 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
789 1401
790 if (send) 1402 if (send)
791 { 1403 {
792 dns_packet *pkt = send->pkt; 1404 last_sent = ev_now ();
793 1405 sendto (vpn->dnsv4_fd,
794 next = min_next; 1406 send->pkt->at (0), send->pkt->len, 0,
795 1407 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
796 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
797 } 1408 }
798 else if (next < min_next) 1409
799 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 ());
800 1416
801 w.start (next); 1417 w.start (next);
802} 1418}
803 1419
804#endif 1420#endif

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