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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.7 by pcg, Thu Mar 3 16:54:34 2005 UTC vs.
Revision 1.49 by root, Tue Feb 8 23:11:36 2011 UTC

1/* 1/*
2 vpn_dns.C -- handle the dns tunnel part of the protocol. 2 vpn_dns.C -- handle the dns tunnel part of the protocol.
3 Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> 3 Copyright (C) 2003-2008 Marc Lehmann <gvpe@schmorp.de>
4 4
5 This file is part of GVPE. 5 This file is part of GVPE.
6 6
7 GVPE is free software; you can redistribute it and/or modify 7 GVPE is free software; you can redistribute it and/or modify it
8 it under the terms of the GNU General Public License as published by 8 under the terms of the GNU General Public License as published by the
9 the Free Software Foundation; either version 2 of the License, or 9 Free Software Foundation; either version 3 of the License, or (at your
10 (at your option) any later version. 10 option) any later version.
11 11
12 This program is distributed in the hope that it will be useful, 12 This program is distributed in the hope that it will be useful, but
13 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
15 GNU General Public License for more details. 15 Public License for more details.
16 16
17 You should have received a copy of the GNU General Public License 17 You should have received a copy of the GNU General Public License along
18 along with gvpe; if not, write to the Free Software 18 with this program; if not, see <http://www.gnu.org/licenses/>.
19 Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19
20 Additional permission under GNU GPL version 3 section 7
21
22 If you modify this Program, or any covered work, by linking or
23 combining it with the OpenSSL project's OpenSSL library (or a modified
24 version of that library), containing parts covered by the terms of the
25 OpenSSL or SSLeay licenses, the licensors of this Program grant you
26 additional permission to convey the resulting work. Corresponding
27 Source for a non-source form of such a combination shall include the
28 source code for the parts of OpenSSL used as well as that of the
29 covered work.
20*/ 30*/
31
32// TODO: EDNS0 option to increase dns mtu?
33// TODO: re-write dns packet parsing/creation using a safe mem-buffer
34// to ensure no buffer overflows or similar problems.
21 35
22#include "config.h" 36#include "config.h"
23 37
24#if ENABLE_DNS 38#if ENABLE_DNS
25 39
26// dns processing is EXTREMELY ugly. For obvious(?) reasons. 40// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27// it's a hack, use only in emergency situations please. 41// it's a hack, use only in emergency situations please.
28 42
29#include <cstring> 43#include <cstring>
44#include <cassert>
30 45
31#include <sys/types.h> 46#include <sys/types.h>
32#include <sys/socket.h> 47#include <sys/socket.h>
33#include <sys/wait.h> 48#include <sys/wait.h>
34#include <sys/uio.h> 49#include <sys/uio.h>
… …
37#include <unistd.h> 52#include <unistd.h>
38#include <fcntl.h> 53#include <fcntl.h>
39 54
40#include <map> 55#include <map>
41 56
57#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
58#include <gmp.h>
59
42#include "netcompat.h" 60#include "netcompat.h"
43 61
44#include "vpn.h" 62#include "vpn.h"
45 63
46#define MIN_RETRY 1. 64#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
47#define MAX_RETRY 60. 65#define ACTIVITY_INTERVAL 5.
48 66
49#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 2. // optimistic?
71
50#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
51#define MAX_RATE 1000 // requests/s
52#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
53 74
54#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well 75#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
55// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
56// every two request byte sless give room for one reply byte 77// every request byte less give room for two reply bytes
57 78
58// seqno has 12 bits, but the lower bit is always left as zero
59// as bind caches ttl=0 records and we have to generate
60// sequence numbers that always differ case-insensitively
61#define SEQNO_MASK 0x07ff 79#define SEQNO_MASK 0x3fff
62 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
63/*
64
65protocol, in shorthand :)
66
67client -> server <req> ANY?
68server -> client <req> TXT <rep>
69
70<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
71<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
72
73if <client-id> is zero, the connection will be configured:
74
75<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
76
77*/
78 81
79#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
80#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
81 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
82#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
83#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
84#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
85 92
86// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 93#define CMD_IP_1 207
87struct dns64 94#define CMD_IP_2 46
88{ 95#define CMD_IP_3 236
89 static const char encode_chars[64 + 1]; 96#define CMD_IP_RST 29
90 static s8 decode_chars[256]; 97#define CMD_IP_SYN 113
98#define CMD_IP_REJ 32
91 99
92 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 100// works for cmaps up to 255 (not 256!)
93 static int decode_len (int bytes) { return (bytes * 6) / 8; } 101struct charmap
102{
103 enum { INVALID = (u8)255 };
104
105 char encode [256]; // index => char
106 u8 decode [256]; // char => index
107 unsigned int size;
108
109 charmap (const char *cmap);
110};
111
112charmap::charmap (const char *cmap)
113{
114 char *enc = encode;
115 u8 *dec = decode;
116
117 memset (enc, (char) 0, 256);
118 memset (dec, (char)INVALID, 256);
119
120 for (size = 0; cmap [size]; size++)
121 {
122 enc [size] = cmap [size];
123 dec [(u8)enc [size]] = size;
124 }
125
126 assert (size < 256);
127}
128
129#define MAX_DEC_LEN 500
130#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
131#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
132
133// ugly. minimum base is 16(!)
134struct basecoder
135{
136 charmap cmap;
137 unsigned int enc_len [MAX_DEC_LEN];
138 unsigned int dec_len [MAX_ENC_LEN];
139
140 unsigned int encode_len (unsigned int len);
141 unsigned int decode_len (unsigned int len);
142
94 static int encode (char *dst, u8 *src, int len); 143 unsigned int encode (char *dst, u8 *src, unsigned int len);
95 static int decode (u8 *dst, char *src, int len); 144 unsigned int decode (u8 *dst, char *src, unsigned int len);
96 145
97 dns64 (); 146 basecoder (const char *cmap);
98} dns64; 147};
99 148
100// the following sequence has been crafted to 149basecoder::basecoder (const char *cmap)
101// a) look somewhat random 150: cmap (cmap)
102// b) the even (and odd) indices never share the same character as upper/lowercase
103const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
104s8 dns64::decode_chars[256];
105
106dns64::dns64 ()
107{ 151{
108 for (int i = 0; i < 64; i++) 152 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
109 decode_chars [encode_chars [i]] = i + 1; 153 {
110} 154 u8 src [MAX_DEC_LEN];
155 u8 dst [MAX_ENC_LEN];
111 156
157 memset (src, 255, len);
158
159 mp_limb_t m [MAX_LIMBS];
160 mp_size_t n;
161
162 n = mpn_set_str (m, src, len, 256);
163 n = mpn_get_str (dst, this->cmap.size, m, n);
164
165 for (int i = 0; !dst [i]; ++i)
166 n--;
167
168 enc_len [len] = n;
169 dec_len [n] = len;
170 }
171}
172
173unsigned int
174basecoder::encode_len (unsigned int len)
175{
176 return enc_len [len];
177}
178
179unsigned int
180basecoder::decode_len (unsigned int len)
181{
182 while (len && !dec_len [len])
183 --len;
184
185 return dec_len [len];
186}
187
188unsigned int
112int dns64::encode (char *dst, u8 *src, int len) 189basecoder::encode (char *dst, u8 *src, unsigned int len)
113{ 190{
114 // slow, but easy to debug 191 if (!len || len > MAX_DEC_LEN)
115 char *beg = dst; 192 return 0;
116 unsigned int accum, bits = 0; 193
194 int elen = encode_len (len);
195
196 mp_limb_t m [MAX_LIMBS];
197 mp_size_t n;
198
199 u8 dst_ [MAX_ENC_LEN];
200
201 n = mpn_set_str (m, src, len, 256);
202 n = mpn_get_str (dst_, cmap.size, m, n);
203
204 int plen = elen; // for padding
205
206 while (n < plen)
207 {
208 *dst++ = cmap.encode [0];
209 plen--;
210 }
211
212 for (unsigned int i = n - plen; i < n; ++i)
213 *dst++ = cmap.encode [dst_ [i]];
214
215 return elen;
216}
217
218unsigned int
219basecoder::decode (u8 *dst, char *src, unsigned int len)
220{
221 if (!len || len > MAX_ENC_LEN)
222 return 0;
223
224 u8 src_ [MAX_ENC_LEN];
225 unsigned int elen = 0;
117 226
118 while (len--) 227 while (len--)
119 { 228 {
120 accum <<= 8; 229 u8 val = cmap.decode [(u8)*src++];
121 accum |= *src++;
122 bits += 8;
123 230
124 while (bits >= 6) 231 if (val != charmap::INVALID)
125 { 232 src_ [elen++] = val;
126 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 233 }
127 bits -= 6; 234
128 } 235 int dlen = decode_len (elen);
236
237 mp_limb_t m [MAX_LIMBS];
238 mp_size_t n;
239
240 u8 dst_ [MAX_DEC_LEN];
241
242 n = mpn_set_str (m, src_, elen, cmap.size);
243 n = mpn_get_str (dst_, 256, m, n);
244
245 if (n < dlen)
129 } 246 {
247 memset (dst, 0, dlen - n);
248 memcpy (dst + dlen - n, dst_, n);
249 }
250 else
251 memcpy (dst, dst_ + n - dlen, dlen);
130 252
131 if (bits) 253 return dlen;
132 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
133
134 return dst - beg;
135} 254}
136 255
137int dns64::decode (u8 *dst, char *src, int len) 256#if 0
138{ 257struct test { test (); } test;
139 // slow, but easy to debug
140 u8 *beg = dst;
141 unsigned int accum, bits = 0;
142 258
143 while (len--) 259test::test ()
260{
261 basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
262
263 u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
264 static char enc[200];
265 static u8 dec[200];
266
267 for (int i = 1; i < 20; i++)
144 { 268 {
145 s8 chr = decode_chars [(u8)*src++]; 269 int elen = cdc.encode (enc, in, i);
270 int dlen = cdc.decode (dec, enc, elen);
146 271
147 if (!chr) 272 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
148 continue;
149
150 accum <<= 6;
151 accum |= chr - 1;
152 bits += 6;
153
154 while (bits >= 8)
155 {
156 *dst++ = accum >> (bits - 8);
157 bits -= 8;
158 }
159 } 273 }
274 abort ();
275}
276#endif
160 277
161 return dst - beg; 278//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
279//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
280static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
281//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
282static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
283
284/////////////////////////////////////////////////////////////////////////////
285
286#define HDRSIZE 6
287
288inline void
289encode_header (char *data, int clientid, int seqno, int retry = 0)
290{
291 seqno &= SEQNO_MASK;
292
293 u8 hdr[3] = {
294 clientid,
295 (seqno >> 8) | (retry << 6),
296 seqno,
297 };
298
299 assert (clientid < 256);
300
301 cdc26.encode (data, hdr, 3);
302}
303
304inline void
305decode_header (char *data, int &clientid, int &seqno)
306{
307 u8 hdr[3];
308
309 cdc26.decode (hdr, data, HDRSIZE);
310
311 clientid = hdr[0];
312 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
162} 313}
163 314
164///////////////////////////////////////////////////////////////////////////// 315/////////////////////////////////////////////////////////////////////////////
165 316
166struct byte_stream 317struct byte_stream
… …
192byte_stream::~byte_stream () 343byte_stream::~byte_stream ()
193{ 344{
194 delete data; 345 delete data;
195} 346}
196 347
348void
197void byte_stream::remove (int count) 349byte_stream::remove (int count)
198{ 350{
199 if (count > fill) 351 if (count > fill)
200 abort (); 352 assert (count <= fill);
201 353
202 memmove (data, data + count, fill -= count); 354 memmove (data, data + count, fill -= count);
203} 355}
204 356
357bool
205bool byte_stream::put (u8 *data, unsigned int datalen) 358byte_stream::put (u8 *data, unsigned int datalen)
206{ 359{
207 if (maxsize - fill < datalen) 360 if (maxsize - fill < datalen)
208 return false; 361 return false;
209 362
210 memcpy (this->data + fill, data, datalen); fill += datalen; 363 memcpy (this->data + fill, data, datalen); fill += datalen;
211 364
212 return true; 365 return true;
213} 366}
214 367
368bool
215bool byte_stream::put (vpn_packet *pkt) 369byte_stream::put (vpn_packet *pkt)
216{ 370{
217 if (maxsize - fill < pkt->len + 2) 371 if (maxsize - fill < pkt->len + 2)
218 return false; 372 return false;
219 373
220 data [fill++] = pkt->len >> 8; 374 data [fill++] = pkt->len >> 8;
221 data [fill++] = pkt->len; 375 data [fill++] = pkt->len;
222 376
223 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 377 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
224 378
225 return true; 379 return true;
226} 380}
227 381
228vpn_packet *byte_stream::get () 382vpn_packet *byte_stream::get ()
229{ 383{
384 unsigned int len;
385
386 for (;;)
387 {
230 int len = (data [0] << 8) | data [1]; 388 len = (data [0] << 8) | data [1];
231 389
232 if (len > MAXSIZE && fill >= 2) 390 if (len <= MAXSIZE || fill < 2)
233 abort (); // TODO handle this gracefully, connection reset 391 break;
234 392
393 // TODO: handle this better than skipping, e.g. by reset
394 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
395 remove (1);
396 }
397
235 if (fill < len + 2) 398 if (fill < len + 2)
236 return 0; 399 return 0;
237 400
238 vpn_packet *pkt = new vpn_packet; 401 vpn_packet *pkt = new vpn_packet;
239 402
240 pkt->len = len; 403 pkt->len = len;
241 memcpy (&((*pkt)[0]), data + 2, len); 404 memcpy (pkt->at (0), data + 2, len);
242 remove (len + 2); 405 remove (len + 2);
243 406
244 return pkt; 407 return pkt;
245} 408}
246 409
247///////////////////////////////////////////////////////////////////////////// 410/////////////////////////////////////////////////////////////////////////////
248 411
249#define FLAG_QUERY ( 0 << 15) 412#define FLAG_QUERY ( 0 << 15)
250#define FLAG_RESPONSE ( 1 << 15) 413#define FLAG_RESPONSE ( 1 << 15)
251#define FLAG_OP_MASK (15 << 14) 414#define FLAG_OP_MASK (15 << 11)
252#define FLAG_OP_QUERY ( 0 << 11) 415#define FLAG_OP_QUERY ( 0 << 11)
253#define FLAG_AA ( 1 << 10) 416#define FLAG_AA ( 1 << 10)
254#define FLAG_TC ( 1 << 9) 417#define FLAG_TC ( 1 << 9)
255#define FLAG_RD ( 1 << 8) 418#define FLAG_RD ( 1 << 8)
256#define FLAG_RA ( 1 << 7) 419#define FLAG_RA ( 1 << 7)
… …
263#define FLAG_RCODE_REFUSED ( 5 << 0) 426#define FLAG_RCODE_REFUSED ( 5 << 0)
264 427
265#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 428#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
266#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) 429#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
267 430
431struct dns_cfg
432{
433 static int next_uid;
434
435 u8 id1, id2, id3, id4;
436
437 u8 version;
438 u8 flags;
439 u8 rrtype;
440 u8 def_ttl;
441
442 u16 client;
443 u16 uid; // to make request unique
444
445 u16 max_size;
446 u8 seq_cdc;
447 u8 req_cdc;
448
449 u8 rep_cdc;
450 u8 delay; // time in 0.01s units that the server may delay replying packets
451 u8 r3, r4;
452
453 u8 r5, r6, r7, r8;
454
455 void reset (int clientid);
456 bool valid ();
457};
458
459int dns_cfg::next_uid;
460
461void
462dns_cfg::reset (int clientid)
463{
464 id1 = 'G';
465 id2 = 'V';
466 id3 = 'P';
467 id4 = 'E';
468
469 version = 1;
470
471 rrtype = RR_TYPE_TXT;
472 flags = 0;
473 def_ttl = 0;
474 seq_cdc = 26;
475 req_cdc = 62;
476 rep_cdc = 0;
477 max_size = htons (MAX_PKT_SIZE);
478 client = htons (clientid);
479 uid = next_uid++;
480 delay = 0;
481
482 r3 = r4 = 0;
483 r4 = r5 = r6 = r7 = 0;
484}
485
486bool
487dns_cfg::valid ()
488{
489 // although the protocol itself allows for some configurability,
490 // only the following encoding/decoding settings are implemented.
491 return id1 == 'G'
492 && id2 == 'V'
493 && id3 == 'P'
494 && id4 == 'E'
495 && seq_cdc == 26
496 && req_cdc == 62
497 && rep_cdc == 0
498 && version == 1;
499}
500
268struct dns_packet : net_packet 501struct dns_packet : net_packet
269{ 502{
270 u16 id; 503 u16 id;
271 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 504 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
272 u16 qdcount, ancount, nscount, arcount; 505 u16 qdcount, ancount, nscount, arcount;
273 506
274 u8 data[MAXSIZE - 6 * 2]; 507 u8 data [MAXSIZE - 6 * 2];
275 508
276 int decode_label (char *data, int size, int &offs); 509 int decode_label (char *data, int size, int &offs);
277}; 510};
278 511
512int
279int dns_packet::decode_label (char *data, int size, int &offs) 513dns_packet::decode_label (char *data, int size, int &offs)
280{ 514{
281 char *orig = data; 515 char *orig = data;
282 516
283 memset (data, 0, size); 517 memset (data, 0, size);
284 518
… …
310 return data - orig; 544 return data - orig;
311} 545}
312 546
313///////////////////////////////////////////////////////////////////////////// 547/////////////////////////////////////////////////////////////////////////////
314 548
315struct dns_req 549static
550u16 next_id ()
316{ 551{
317 dns_packet *pkt;
318 tstamp next;
319 int retry;
320 connection *conn;
321 int seqno;
322
323 dns_req (connection *c);
324 void gen_stream_req (int seqno, byte_stream *stream);
325};
326
327static u16 dns_id = 12098; // TODO: should be per-vpn 552 static u16 dns_id = 0; // TODO: should be per-vpn
328 553
329static u16 next_id () 554 if (!dns_id)
330{ 555 dns_id = time (0);
556
331 // the simplest lsfr with periodicity 65535 i could find 557 // the simplest lsfr with periodicity 65535 i could find
332 dns_id = (dns_id << 1) 558 dns_id = (dns_id << 1)
333 | (((dns_id >> 1) 559 | (((dns_id >> 1)
334 ^ (dns_id >> 2) 560 ^ (dns_id >> 2)
335 ^ (dns_id >> 4) 561 ^ (dns_id >> 4)
336 ^ (dns_id >> 15)) & 1); 562 ^ (dns_id >> 15)) & 1);
337 563
338 return dns_id; 564 return dns_id;
339} 565}
340 566
341dns_req::dns_req (connection *c) 567struct dns_rcv;
342: conn (c) 568struct dns_snd;
569
570struct dns_connection
343{ 571{
344 next = 0; 572 connection *c;
573 struct vpn *vpn;
574
575 dns_cfg cfg;
576
577 bool established;
578
579 tstamp last_received;
580 tstamp last_sent;
581 double min_latency;
582 double poll_interval, send_interval;
583
584 vector<dns_rcv *> rcvpq;
585
586 byte_stream rcvdq; int rcvseq; int repseq;
587 byte_stream snddq; int sndseq;
588
589 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
590 void receive_rep (dns_rcv *r);
591
592 dns_connection (connection *c);
593 ~dns_connection ();
594};
595
596struct dns_snd
597{
598 dns_packet *pkt;
599 tstamp timeout, sent;
600 int retry;
601 struct dns_connection *dns;
602 int seqno;
603 bool stdhdr;
604
605 void gen_stream_req (int seqno, byte_stream &stream);
606 void gen_syn_req ();
607
608 dns_snd (dns_connection *dns);
609 ~dns_snd ();
610};
611
612dns_snd::dns_snd (dns_connection *dns)
613: dns (dns)
614{
615 timeout = 0;
345 retry = 0; 616 retry = 0;
617 seqno = 0;
618 sent = ev_now ();
619 stdhdr = false;
346 620
347 pkt = new dns_packet; 621 pkt = new dns_packet;
348 622
349 pkt->id = next_id (); 623 pkt->id = next_id ();
350} 624}
351 625
626dns_snd::~dns_snd ()
627{
628 delete pkt;
629}
630
631static void
632append_domain (dns_packet &pkt, int &offs, const char *domain)
633{
634 // add tunnel domain
635 for (;;)
636 {
637 const char *end = strchr (domain, '.');
638
639 if (!end)
640 end = domain + strlen (domain);
641
642 int len = end - domain;
643
644 pkt [offs++] = len;
645 memcpy (pkt.at (offs), domain, len);
646 offs += len;
647
648 if (!*end)
649 break;
650
651 domain = end + 1;
652 }
653}
654
655void
352void dns_req::gen_stream_req (int seqno, byte_stream *stream) 656dns_snd::gen_stream_req (int seqno, byte_stream &stream)
353{ 657{
658 stdhdr = true;
354 this->seqno = seqno; 659 this->seqno = seqno;
660
661 timeout = ev_now () + INITIAL_TIMEOUT;
355 662
356 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 663 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
357 pkt->qdcount = htons (1); 664 pkt->qdcount = htons (1);
358 665
359 int offs = 6*2; 666 int offs = 6*2;
360 int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2; 667 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
361 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, 668 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
362 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 669 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
363 670
364 u8 data[256]; //TODO
365
366 data[0] = THISNODE->id; //TODO
367 data[1] = seqno >> 7; //TODO
368 data[2] = seqno << 1; //TODO
369
370 int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
371
372 if (datalen > stream->size ())
373 datalen = stream->size ();
374
375 char enc[256], *encp = enc; 671 char enc[256], *encp = enc;
376 672 encode_header (enc, THISNODE->id, seqno);
377 memcpy (data + 3, stream->begin (), datalen); 673
378 int enclen = dns64::encode (enc, data, datalen + 3); 674 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
675
676 if (datalen > stream.size ())
677 datalen = stream.size ();
678
679 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
379 stream->remove (datalen); 680 stream.remove (datalen);
380 681
381 while (enclen) 682 while (enclen)
382 { 683 {
383 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 684 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
384 685
… …
389 encp += lbllen; 690 encp += lbllen;
390 691
391 enclen -= lbllen; 692 enclen -= lbllen;
392 } 693 }
393 694
394 const char *suffix = THISNODE->domain; 695 append_domain (*pkt, offs, dns->c->conf->domain);
395
396 // add tunnel domain
397 for (;;)
398 {
399 const char *end = strchr (suffix, '.');
400
401 if (!end)
402 end = suffix + strlen (suffix);
403
404 int len = end - suffix;
405
406 (*pkt)[offs++] = len;
407 memcpy (&((*pkt)[offs]), suffix, len);
408 offs += len;
409
410 if (!*end)
411 break;
412
413 suffix = end + 1;
414 }
415 696
416 (*pkt)[offs++] = 0; 697 (*pkt)[offs++] = 0;
417 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 698 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
699 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
700
701 pkt->len = offs;
702}
703
704void
705dns_snd::gen_syn_req ()
706{
707 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
708
709 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
710 pkt->qdcount = htons (1);
711
712 int offs = 6 * 2;
713
714 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
715
716 assert (elen <= MAX_LBL_SIZE);
717
718 (*pkt)[offs] = elen;
719 offs += elen + 1;
720 append_domain (*pkt, offs, dns->c->conf->domain);
721
722 (*pkt)[offs++] = 0;
723 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
418 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 724 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
419 725
420 pkt->len = offs; 726 pkt->len = offs;
421} 727}
422 728
… …
441{ 747{
442 delete pkt; 748 delete pkt;
443} 749}
444 750
445///////////////////////////////////////////////////////////////////////////// 751/////////////////////////////////////////////////////////////////////////////
446 752
447struct dns_cfg 753dns_connection::dns_connection (connection *c)
754: c (c)
755, rcvdq (MAX_BACKLOG * 2)
756, snddq (MAX_BACKLOG)
448{ 757{
449 u8 id1, id2, id3; 758 tw.set<dns_connection, &dns_connection::time_cb> (this);
450 u8 def_ttl;
451 u8 unused1;
452 u16 max_size;
453 u8 flags1, flags2;
454};
455 759
760 vpn = c->vpn;
761
762 established = false;
763
764 rcvseq = repseq = sndseq = 0;
765
766 last_sent = last_received = 0;
767 poll_interval = 0.5; // starting here
768 send_interval = 0.5; // starting rate
769 min_latency = INITIAL_TIMEOUT;
770}
771
772dns_connection::~dns_connection ()
773{
774 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
775 i != rcvpq.end ();
776 ++i)
777 delete *i;
778}
779
780void
456void connection::dnsv4_receive_rep (struct dns_rcv *r) 781dns_connection::receive_rep (dns_rcv *r)
457{ 782{
783 if (r->datalen)
784 {
785 last_received = ev_now ();
786 tw ();
787
788 poll_interval = send_interval;
789 }
790 else
791 {
792 poll_interval *= 1.5;
793
794 if (poll_interval > MAX_POLL_INTERVAL)
795 poll_interval = MAX_POLL_INTERVAL;
796 }
797
458 dns_rcvpq.push_back (r); 798 rcvpq.push_back (r);
459 799
460 redo: 800 redo:
461 801
802 // find next packet
462 for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin (); 803 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
463 i != dns_rcvpq.end ();
464 ++i)
465 if (dns_rcvseq == (*i)->seqno) 804 if (SEQNO_EQ (rcvseq, (*i)->seqno))
466 { 805 {
806 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
807 // enter the packet into our input stream
467 dns_rcv *r = *i; 808 r = *i;
468 809
810 // remove the oldest packet, look forward, as it's oldest first
811 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
812 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
813 {
814 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
815 delete *j;
816 rcvpq.erase (j);
817 break;
818 }
819
469 dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; 820 rcvseq = (rcvseq + 1) & SEQNO_MASK;
470 821
471 if (!dns_snddq && !dns_rcvdq) 822 if (!rcvdq.put (r->data, r->datalen))
472 { 823 {
473 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); 824 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
474 dns_snddq = new byte_stream (MAX_BACKLOG); 825 abort (); // MUST never overflow, can be caused by data corruption, TODO
475
476 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
477 } 826 }
478 827
479 if (!dns_rcvdq->put (r->data, r->datalen))
480 abort (); // MUST never overflow, can be caused by data corruption, TODO
481
482 while (vpn_packet *pkt = dns_rcvdq->get ()) 828 while (vpn_packet *pkt = rcvdq.get ())
483 { 829 {
484 sockinfo si; 830 sockinfo si;
485 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 831 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
486 832
487 vpn->recv_vpn_packet (pkt, si); 833 vpn->recv_vpn_packet (pkt, si);
834
835 delete pkt;
488 } 836 }
489 } 837
490 else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2) 838 // check for further packets
491 {
492 //D
493 //abort();
494 printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
495 dns_rcvpq.erase (i);
496 goto redo; 839 goto redo;
497 } 840 }
498} 841}
499 842
500dns_packet * 843void
501vpn::dnsv4_server (dns_packet *pkt) 844vpn::dnsv4_server (dns_packet &pkt)
502{ 845{
503 u16 flags = ntohs (pkt->flags); 846 u16 flags = ntohs (pkt.flags);
504 847
505 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
506 int offs = 6 * 2; // skip header 848 int offs = 6 * 2; // skip header
507 849
508 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 850 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
509 851
510 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 852 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
511 && pkt->qdcount == htons (1)) 853 && pkt.qdcount == htons (1))
512 { 854 {
513 char qname[MAXSIZE]; 855 char qname [MAXSIZE];
514 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 856 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
515 857
516 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 858 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
517 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 859 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
518 860
519 pkt->qdcount = htons (1); 861 pkt.qdcount = htons (1);
520 pkt->ancount = 0; 862 pkt.ancount = 0;
521 pkt->nscount = 0; // should be self, as other nameservers reply like this 863 pkt.nscount = 0; // should be self, as other nameservers reply like this
522 pkt->arcount = 0; // a record for self, as other nameservers reply like this 864 pkt.arcount = 0; // a record for self, as other nameservers reply like this
523 865
524 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 866 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
525 867
526 int dlen = strlen (THISNODE->domain); 868 int dlen = strlen (THISNODE->domain);
527 869
528 if (qclass == RR_CLASS_IN 870 if (qclass == RR_CLASS_IN
529 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
530 && qlen > dlen + 1 871 && qlen > dlen + 1
531 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 872 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
532 { 873 {
533 // correct class, domain: parse 874 // now generate reply
534 u8 data[MAXSIZE]; 875 pkt.ancount = htons (1); // one answer RR
535 int datalen = dns64::decode (data, qname, qlen - dlen - 1); 876 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
536 877
537 int client = data[0]; 878 if ((qtype == RR_TYPE_ANY
538 int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK; 879 || qtype == RR_TYPE_TXT
539 880 || qtype == RR_TYPE_NULL)
540 if (0 < client && client <= conns.size ()) 881 && qlen > dlen + 1 + HDRSIZE)
541 { 882 {
883 // correct class, domain: parse
884 int client, seqno;
885 decode_header (qname, client, seqno);
886
887 u8 data[MAXSIZE];
888 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
889
890 if (0 < client && client <= conns.size ())
891 {
542 connection *c = conns [client - 1]; 892 connection *c = conns [client - 1];
893 dns_connection *dns = c->dns;
894 dns_rcv *rcv;
543 895
544 redo: 896 if (dns)
545
546 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
547 i != c->dns_rcvpq.end ();
548 ++i) 897 {
898 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
549 if ((*i)->seqno == seqno) 899 if (SEQNO_EQ ((*i)->seqno, seqno))
900 {
901 // already seen that request: simply reply with the cached reply
902 dns_rcv *r = *i;
903
904 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
905
906 // refresh header & id, as the retry count could have changed
907 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
908 r->pkt->id = pkt.id;
909
910 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
911
912 goto duplicate_request;
913 }
914
915 // new packet, queue
916 rcv = new dns_rcv (seqno, data, datalen);
917 dns->receive_rep (rcv);
918 }
919
550 { 920 {
551 // already seen that request: simply reply with the cached reply 921 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
552 dns_rcv *r = *i;
553 922
554 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 923 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
924 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
925 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
926 pkt [offs++] = 0; pkt [offs++] = 0;
927 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
555 928
929 int rdlen_offs = offs += 2;
930
931 if (dns)
932 {
933 int dlen = ntohs (dns->cfg.max_size) - offs;
934
935 // bind doesn't compress well, so reduce further by one label length
936 dlen -= qlen;
937
938 // only put data into in-order sequence packets, if
939 // we receive out-of-order packets we generate empty
940 // replies
941 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
942 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
943 {
944 dns->repseq = seqno;
945
946 while (dlen > 1 && !dns->snddq.empty ())
947 {
948 int txtlen = dlen <= 255 ? dlen - 1 : 255;
949
950 if (txtlen > dns->snddq.size ())
951 txtlen = dns->snddq.size ();
952
953 pkt[offs++] = txtlen;
954 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
955 offs += txtlen;
956 dns->snddq.remove (txtlen);
957
958 dlen -= txtlen + 1;
959 }
960 }
961
962 // avoid completely empty TXT rdata
963 if (offs == rdlen_offs)
964 pkt[offs++] = 0;
965
966 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
967 }
968 else
969 {
970 // send RST
971 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
972 pkt [offs++] = CMD_IP_RST;
973 }
974
975 int rdlen = offs - rdlen_offs;
976
977 pkt [rdlen_offs - 2] = rdlen >> 8;
978 pkt [rdlen_offs - 1] = rdlen;
979
980 if (dns)
981 {
982 // now update dns_rcv copy
556 offs = r->pkt->len; 983 rcv->pkt->len = offs;
557 memcpy (pkt->at (0), r->pkt->at (0), offs); 984 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
558 goto duplicate_request; 985 }
559 } 986 }
560 987
561 // new packet, queue 988 duplicate_request: ;
562 dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3); 989 }
563 c->dnsv4_receive_rep (rcv); 990 else
564
565 // now generate reply
566 pkt->ancount = htons (1); // one answer RR
567 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 991 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
992 }
993 else if (qtype == RR_TYPE_A
994 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
995 {
996 dns_cfg cfg;
997 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
998 int client = ntohs (cfg.client);
568 999
569 (*pkt) [offs++] = 0xc0;
570 (*pkt) [offs++] = 6 * 2; // same as in query section 1000 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
571 1001
572 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1002 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
573 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1003 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
574
575 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1004 pkt [offs++] = 0; pkt [offs++] = 0;
576 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL 1005 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1006 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
577 1007
578 int dlen = MAX_PKT_SIZE - offs - 2; 1008 slog (L_INFO, _("DNS: client %d connects"), client);
579 1009
580 // bind doesn't compress well, so reduce further by one label length 1010 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
581 dlen -= qlen; 1011 pkt [offs++] = CMD_IP_REJ;
582 1012
583 int rdlen_offs = offs += 2; 1013 if (0 < client && client <= conns.size ())
584
585 while (c->dns_snddq
586 && !c->dns_snddq->empty ()
587 && dlen > 1)
588 { 1014 {
589 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1015 connection *c = conns [client - 1];
590 1016
591 if (txtlen > c->dns_snddq->size ()) 1017 if (cfg.valid ())
592 txtlen = c->dns_snddq->size (); 1018 {
1019 pkt [offs - 1] = CMD_IP_SYN;
593 1020
594 (*pkt)[offs++] = txtlen; 1021 delete c->dns;
595 memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen); 1022 c->dns = new dns_connection (c);
596 offs += txtlen; 1023 c->dns->cfg = cfg;
597 c->dns_snddq->remove (txtlen); 1024 }
598
599 dlen -= txtlen + 1;
600 } 1025 }
601
602 // avoid empty TXT rdata
603 if (offs == rdlen_offs)
604 (*pkt)[offs++] = 0;
605
606 int rdlen = offs - rdlen_offs;
607
608 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
609 (*pkt) [rdlen_offs - 1] = rdlen;
610
611 // now update dns_rcv copy
612 rcv->pkt->len = offs;
613 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
614
615 duplicate_request: ;
616 } 1026 }
617 else
618 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
619 } 1027 }
620 1028
621 pkt->len = offs; 1029 pkt.len = offs;
622 } 1030 }
623
624 return pkt;
625} 1031}
626 1032
627void 1033void
628vpn::dnsv4_client (dns_packet *pkt) 1034vpn::dnsv4_client (dns_packet &pkt)
629{ 1035{
630 u16 flags = ntohs (pkt->flags); 1036 u16 flags = ntohs (pkt.flags);
631 int offs = 6 * 2; // skip header 1037 int offs = 6 * 2; // skip header
632 1038
633 pkt->qdcount = ntohs (pkt->qdcount); 1039 pkt.qdcount = ntohs (pkt.qdcount);
634 pkt->ancount = ntohs (pkt->ancount); 1040 pkt.ancount = ntohs (pkt.ancount);
635 1041
636 // go through our request list and find the corresponding request 1042 // go through our request list and find the corresponding request
637 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1043 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
638 i != dns_sndpq.end (); 1044 i != dns_sndpq.end ();
639 ++i) 1045 ++i)
640 if ((*i)->pkt->id == pkt->id) 1046 if ((*i)->pkt->id == pkt.id)
641 { 1047 {
1048 dns_connection *dns = (*i)->dns;
642 connection *c = (*i)->conn; 1049 connection *c = dns->c;
643 int seqno = (*i)->seqno; 1050 int seqno = (*i)->seqno;
644 u8 data[MAXSIZE], *datap = data; 1051 u8 data[MAXSIZE], *datap = data;
1052 //printf ("rcv pkt %x\n", seqno);//D
1053
1054 if ((*i)->retry)
1055 {
1056 dns->send_interval *= 1.01;
1057 if (dns->send_interval > MAX_SEND_INTERVAL)
1058 dns->send_interval = MAX_SEND_INTERVAL;
1059 }
1060 else
1061 {
1062#if 0
1063 dns->send_interval *= 0.999;
1064#endif
1065 // the latency surely puts an upper bound on
1066 // the minimum send interval
1067 double latency = ev_now () - (*i)->sent;
1068
1069 if (latency < dns->min_latency)
1070 dns->min_latency = latency;
1071
1072 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1073 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1074
1075 if (dns->send_interval < conf.dns_send_interval)
1076 dns->send_interval = conf.dns_send_interval;
1077 }
645 1078
646 delete *i; 1079 delete *i;
647 dns_sndpq.erase (i); 1080 dns_sndpq.erase (i);
648 1081
649 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1082 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
650 { 1083 {
651 char qname[MAXSIZE]; 1084 char qname[MAXSIZE];
652 1085
653 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1086 while (pkt.qdcount-- && offs < MAXSIZE - 4)
654 { 1087 {
655 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1088 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
656 offs += 4; // skip qtype, qclass 1089 offs += 4; // skip qtype, qclass
657 } 1090 }
658 1091
659 while (pkt->ancount-- && offs < MAXSIZE - 10) 1092 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
660 { 1093 {
661 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1094 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
662 1095
663 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1096 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
664 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1097 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
665 u32 ttl = (*pkt) [offs++] << 24; 1098 u32 ttl = pkt [offs++] << 24;
666 ttl |= (*pkt) [offs++] << 16; 1099 ttl |= pkt [offs++] << 16;
667 ttl |= (*pkt) [offs++] << 8; 1100 ttl |= pkt [offs++] << 8;
668 ttl |= (*pkt) [offs++]; 1101 ttl |= pkt [offs++];
669
670 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1102 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
671 1103
672 if (rdlen <= MAXSIZE - offs) 1104 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
673 { 1105 {
674 // decode bytes, finally 1106 if (rdlen <= MAXSIZE - offs)
675
676 while (rdlen)
677 { 1107 {
1108 // decode bytes, finally
1109
1110 while (rdlen)
1111 {
678 int txtlen = (*pkt) [offs++]; 1112 int txtlen = pkt [offs++];
679 1113
680 assert (txtlen + offs < MAXSIZE - 1); 1114 assert (txtlen + offs < MAXSIZE - 1);
681 1115
682 memcpy (datap, pkt->at (offs), txtlen); 1116 memcpy (datap, pkt.at (offs), txtlen);
683 datap += txtlen; offs += txtlen; 1117 datap += txtlen; offs += txtlen;
684 1118
685 rdlen -= txtlen + 1; 1119 rdlen -= txtlen + 1;
1120 }
686 } 1121 }
687
688 } 1122 }
1123 else if (qtype == RR_TYPE_A)
1124 {
1125 u8 ip [4];
689 1126
1127 ip [0] = pkt [offs++];
1128 ip [1] = pkt [offs++];
1129 ip [2] = pkt [offs++];
1130 ip [3] = pkt [offs++];
1131
1132 if (ip [0] == CMD_IP_1
1133 && ip [1] == CMD_IP_2
1134 && ip [2] == CMD_IP_3)
1135 {
1136 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1137
1138 if (ip [3] == CMD_IP_RST)
1139 {
1140 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1141
1142 delete dns; c->dns = 0;
1143
1144 return;
1145 }
1146 else if (ip [3] == CMD_IP_SYN)
1147 {
1148 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1149 dns->established = true;
1150 }
1151 else if (ip [3] == CMD_IP_REJ)
1152 {
1153 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1154 abort ();
1155 }
1156 else
1157 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1158 }
1159 else
1160 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1161 ip [0], ip [1], ip [2], ip [3]);
1162
1163 return;
1164 }
1165
1166 int client, rseqno;
1167 decode_header (qname, client, rseqno);
1168
1169 if (client != THISNODE->id)
1170 {
1171 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1172 datap = 0;
1173 }
1174 else if (rseqno != seqno)
1175 {
1176 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1177 datap = 0;
1178 }
690 } 1179 }
691 } 1180 }
692 1181
693 // todo: pkt now used 1182 // todo: pkt now used
1183 if (datap)
694 c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data)); 1184 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
695 1185
696 break; 1186 break;
697 } 1187 }
698
699 delete pkt;
700} 1188}
701 1189
702void 1190void
703vpn::dnsv4_ev (io_watcher &w, short revents) 1191vpn::dnsv4_ev (ev::io &w, int revents)
704{ 1192{
705 if (revents & EVENT_READ) 1193 if (revents & EV_READ)
706 { 1194 {
707 dns_packet *pkt = new dns_packet; 1195 dns_packet *pkt = new dns_packet;
708 struct sockaddr_in sa; 1196 struct sockaddr_in sa;
709 socklen_t sa_len = sizeof (sa); 1197 socklen_t sa_len = sizeof (sa);
710 1198
711 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1199 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
712 1200
713 if (pkt->len > 0) 1201 if (pkt->len > 0)
714 { 1202 {
715 if (pkt->flags & htons (FLAG_TC)) 1203 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1204 dnsv4_client (*pkt);
1205 else
716 { 1206 {
717 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1207 dnsv4_server (*pkt);
718 //TODO connection reset 1208 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
719 } 1209 }
720 1210
721 if (THISNODE->dns_port) 1211 delete pkt;
722 {
723 pkt = dnsv4_server (pkt);
724 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
725 }
726 else
727 dnsv4_client (pkt);
728 } 1212 }
729 } 1213 }
730} 1214}
731 1215
732bool 1216bool
733connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1217vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
734{ 1218{
735 // never initialized 1219 int client = ntohl (si.host);
736 if (!dns_snddq && !dns_rcvdq)
737 {
738 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
739 dns_snddq = new byte_stream (MAX_BACKLOG);
740 1220
741 //dns_rcvseq = dns_sndseq = 0; 1221 assert (0 < client && client <= conns.size ());
742 1222
743 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1223 connection *c = conns [client - 1];
744 } 1224
1225 if (!c->dns)
1226 c->dns = new dns_connection (c);
745 1227
746 if (!dns_snddq->put (pkt)) 1228 if (c->dns->snddq.put (pkt))
747 return false; 1229 c->dns->tw ();
748 1230
749 // start timer if neccessary 1231 // always return true even if the buffer overflows
750 if (!THISNODE->dns_port && !dnsv4_tw.active)
751 dnsv4_cb (dnsv4_tw);
752
753 return true; 1232 return true;
754} 1233}
755 1234
756void 1235void
757connection::dnsv4_cb (time_watcher &w) 1236connection::dnsv4_reset_connection ()
758{ 1237{
1238 //delete dns; dns = 0; //TODO
1239}
1240
1241#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1242
1243void
1244dns_connection::time_cb (ev::timer &w, int revents)
1245{
1246 // servers have to be polled
1247 if (THISNODE->dns_port)
1248 return;
1249
759 // check for timeouts and (re)transmit 1250 // check for timeouts and (re)transmit
760 tstamp next = NOW + 60; 1251 tstamp next = ev::now () + poll_interval;
761 dns_req *send = 0; 1252 dns_snd *send = 0;
762 1253
763 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1254 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
764 i != vpn->dns_sndpq.end (); 1255 i != vpn->dns_sndpq.end ();
765 ++i) 1256 ++i)
766 { 1257 {
767 dns_req *r = *i; 1258 dns_snd *r = *i;
768 1259
769 if (r->next <= NOW) 1260 if (r->timeout <= ev_now ())
770 { 1261 {
771 if (!send) 1262 if (!send)
772 { 1263 {
773 send = r; 1264 send = r;
774 1265
775 if (r->retry)//D
776 printf ("req %d, retry %d\n", r->pkt->id, r->retry);
777 r->retry++; 1266 r->retry++;
778 r->next = NOW + r->retry; 1267 r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
1268 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1269
1270 // the following code changes the query section a bit, forcing
1271 // the forwarder to generate a new request
1272 if (r->stdhdr)
1273 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
779 } 1274 }
780 } 1275 }
781 1276 else
782 if (r->next < next) 1277 NEXT (r->timeout);
783 next = r->next;
784 } 1278 }
785 1279
786 if (!send 1280 if (!send)
787 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
788 { 1281 {
1282 // generate a new packet, if wise
1283
1284 if (!established)
1285 {
1286 if (vpn->dns_sndpq.empty ())
1287 {
789 send = new dns_req (this); 1288 send = new dns_snd (this);
1289
1290 cfg.reset (THISNODE->id);
1291 send->gen_syn_req ();
1292 }
1293 }
1294 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1295 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1296 {
1297 if (last_sent + send_interval <= ev_now ())
1298 {
1299 //printf ("sending data request etc.\n"); //D
1300 if (!snddq.empty () || last_received + 1. > ev_now ())
1301 {
1302 poll_interval = send_interval;
1303 NEXT (ev_now () + send_interval);
1304 }
1305
1306 send = new dns_snd (this);
790 send->gen_stream_req (dns_sndseq, dns_snddq); 1307 send->gen_stream_req (sndseq, snddq);
1308 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1309 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1310
1311 sndseq = (sndseq + 1) & SEQNO_MASK;
1312 }
1313 else
1314 NEXT (last_sent + send_interval);
1315 }
1316
1317 if (send)
791 vpn->dns_sndpq.push_back (send); 1318 vpn->dns_sndpq.push_back (send);
792
793 dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
794 } 1319 }
795
796 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
797 1320
798 if (send) 1321 if (send)
799 { 1322 {
800 dns_packet *pkt = send->pkt; 1323 last_sent = ev_now ();
801 1324 sendto (vpn->dnsv4_fd,
802 next = min_next; 1325 send->pkt->at (0), send->pkt->len, 0,
803 1326 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
804 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
805 } 1327 }
806 else if (next < min_next)
807 next = min_next;
808 1328
809 w.start (next); 1329 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1330 poll_interval, send_interval, next - ev_now (),
1331 vpn->dns_sndpq.size (), snddq.size (),
1332 rcvpq.size ());
1333
1334 // TODO: no idea when this happens, but when next < ev_now (), we have a problem
1335 // doesn't seem to happen anymore
1336 if (next < ev_now () + 0.001)
1337 next = ev_now () + 0.1;
1338
1339 w.start (next - ev_now ());
810} 1340}
811 1341
812#endif 1342#endif
813 1343

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