ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/gvpe/src/vpn_dns.C
(Generate patch)

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.6 by pcg, Thu Mar 3 08:38:32 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) 2003-2004 Marc Lehmann <pcg@goof.com> 3 Copyright (C) 2003-2008 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 MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45#define MAX_RETRY 60. 65#define ACTIVITY_INTERVAL 5.
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 2. // 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 240 // 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// seqno has 12 bits, but the lower bit is always left as zero
57// as bind caches ttl=0 records and we have to generate
58// sequence numbers that always differ case-insensitively
59#define SEQNO_MASK 0x07ff 79#define SEQNO_MASK 0x3fff
60 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
61/*
62
63protocol, in shorthand :)
64
65client -> server <req> ANY?
66server -> client <req> TXT <rep>
67
68<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
69<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
70
71if <client-id> is zero, the connection will be configured:
72
73<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
74
75*/
76 81
77#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
78#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
79 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
80#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
81#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
82#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
83 92
84// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 93#define CMD_IP_1 207
85struct dns64 94#define CMD_IP_2 46
86{ 95#define CMD_IP_3 236
87 static const char encode_chars[64 + 1]; 96#define CMD_IP_RST 29
88 static s8 decode_chars[256]; 97#define CMD_IP_SYN 113
98#define CMD_IP_REJ 32
89 99
90 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 100// works for cmaps up to 255 (not 256!)
91 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
92 static int encode (char *dst, u8 *src, int len); 143 unsigned int encode (char *dst, u8 *src, unsigned int len);
93 static int decode (u8 *dst, char *src, int len); 144 unsigned int decode (u8 *dst, char *src, unsigned int len);
94 145
95 dns64 (); 146 basecoder (const char *cmap);
96} dns64; 147};
97 148
98// the following sequence has been crafted to 149basecoder::basecoder (const char *cmap)
99// a) look somewhat random 150: cmap (cmap)
100// b) the even (and odd) indices never share the same character as upper/lowercase
101const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
102s8 dns64::decode_chars[256];
103
104dns64::dns64 ()
105{ 151{
106 for (int i = 0; i < 64; i++) 152 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
107 decode_chars [encode_chars [i]] = i + 1; 153 {
108} 154 u8 src [MAX_DEC_LEN];
155 u8 dst [MAX_ENC_LEN];
109 156
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
110int dns64::encode (char *dst, u8 *src, int len) 189basecoder::encode (char *dst, u8 *src, unsigned int len)
111{ 190{
112 // slow, but easy to debug 191 if (!len || len > MAX_DEC_LEN)
113 char *beg = dst; 192 return 0;
114 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;
115 226
116 while (len--) 227 while (len--)
117 { 228 {
118 accum <<= 8; 229 u8 val = cmap.decode [(u8)*src++];
119 accum |= *src++;
120 bits += 8;
121 230
122 while (bits >= 6) 231 if (val != charmap::INVALID)
123 { 232 src_ [elen++] = val;
124 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 233 }
125 bits -= 6; 234
126 } 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)
127 } 246 {
247 memset (dst, 0, dlen - n);
248 memcpy (dst + dlen - n, dst_, n);
249 }
250 else
251 memcpy (dst, dst_ + n - dlen, dlen);
128 252
129 if (bits) 253 return dlen;
130 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
131
132 return dst - beg;
133} 254}
134 255
135int dns64::decode (u8 *dst, char *src, int len) 256#if 0
136{ 257struct test { test (); } test;
137 // slow, but easy to debug
138 u8 *beg = dst;
139 unsigned int accum, bits = 0;
140 258
141 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++)
142 { 268 {
143 s8 chr = decode_chars [(u8)*src++]; 269 int elen = cdc.encode (enc, in, i);
270 int dlen = cdc.decode (dec, enc, elen);
144 271
145 if (!chr) 272 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
146 continue;
147
148 accum <<= 6;
149 accum |= chr - 1;
150 bits += 6;
151
152 while (bits >= 8)
153 {
154 *dst++ = accum >> (bits - 8);
155 bits -= 8;
156 }
157 } 273 }
274 abort ();
275}
276#endif
158 277
159 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;
160} 313}
161 314
162///////////////////////////////////////////////////////////////////////////// 315/////////////////////////////////////////////////////////////////////////////
163 316
164struct byte_stream 317struct byte_stream
… …
190byte_stream::~byte_stream () 343byte_stream::~byte_stream ()
191{ 344{
192 delete data; 345 delete data;
193} 346}
194 347
348void
195void byte_stream::remove (int count) 349byte_stream::remove (int count)
196{ 350{
197 if (count > fill) 351 if (count > fill)
198 abort (); 352 assert (count <= fill);
199 353
200 memmove (data, data + count, fill -= count); 354 memmove (data, data + count, fill -= count);
201} 355}
202 356
357bool
203bool byte_stream::put (u8 *data, unsigned int datalen) 358byte_stream::put (u8 *data, unsigned int datalen)
204{ 359{
205 if (maxsize - fill < datalen) 360 if (maxsize - fill < datalen)
206 return false; 361 return false;
207 362
208 memcpy (this->data + fill, data, datalen); fill += datalen; 363 memcpy (this->data + fill, data, datalen); fill += datalen;
209 364
210 return true; 365 return true;
211} 366}
212 367
368bool
213bool byte_stream::put (vpn_packet *pkt) 369byte_stream::put (vpn_packet *pkt)
214{ 370{
215 if (maxsize - fill < pkt->len + 2) 371 if (maxsize - fill < pkt->len + 2)
216 return false; 372 return false;
217 373
218 data [fill++] = pkt->len >> 8; 374 data [fill++] = pkt->len >> 8;
219 data [fill++] = pkt->len; 375 data [fill++] = pkt->len;
220 376
221 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 377 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
222 378
223 return true; 379 return true;
224} 380}
225 381
226vpn_packet *byte_stream::get () 382vpn_packet *byte_stream::get ()
227{ 383{
384 unsigned int len;
385
386 for (;;)
387 {
228 int len = (data [0] << 8) | data [1]; 388 len = (data [0] << 8) | data [1];
229 389
230 if (len > MAXSIZE && fill >= 2) 390 if (len <= MAXSIZE || fill < 2)
231 abort (); // TODO handle this gracefully, connection reset 391 break;
232 392
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
233 if (fill < len + 2) 398 if (fill < len + 2)
234 return 0; 399 return 0;
235 400
236 vpn_packet *pkt = new vpn_packet; 401 vpn_packet *pkt = new vpn_packet;
237 402
238 pkt->len = len; 403 pkt->len = len;
239 memcpy (&((*pkt)[0]), data + 2, len); 404 memcpy (pkt->at (0), data + 2, len);
240 remove (len + 2); 405 remove (len + 2);
241 406
242 return pkt; 407 return pkt;
243} 408}
244 409
245///////////////////////////////////////////////////////////////////////////// 410/////////////////////////////////////////////////////////////////////////////
246 411
247#define FLAG_QUERY ( 0 << 15) 412#define FLAG_QUERY ( 0 << 15)
248#define FLAG_RESPONSE ( 1 << 15) 413#define FLAG_RESPONSE ( 1 << 15)
249#define FLAG_OP_MASK (15 << 14) 414#define FLAG_OP_MASK (15 << 11)
250#define FLAG_OP_QUERY ( 0 << 11) 415#define FLAG_OP_QUERY ( 0 << 11)
251#define FLAG_AA ( 1 << 10) 416#define FLAG_AA ( 1 << 10)
252#define FLAG_TC ( 1 << 9) 417#define FLAG_TC ( 1 << 9)
253#define FLAG_RD ( 1 << 8) 418#define FLAG_RD ( 1 << 8)
254#define FLAG_RA ( 1 << 7) 419#define FLAG_RA ( 1 << 7)
… …
261#define FLAG_RCODE_REFUSED ( 5 << 0) 426#define FLAG_RCODE_REFUSED ( 5 << 0)
262 427
263#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 428#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
264#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)
265 430
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
266struct dns_packet : net_packet 501struct dns_packet : net_packet
267{ 502{
268 u16 id; 503 u16 id;
269 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
270 u16 qdcount, ancount, nscount, arcount; 505 u16 qdcount, ancount, nscount, arcount;
271 506
272 u8 data[MAXSIZE - 6 * 2]; 507 u8 data [MAXSIZE - 6 * 2];
273 508
274 int decode_label (char *data, int size, int &offs); 509 int decode_label (char *data, int size, int &offs);
275}; 510};
276 511
512int
277int dns_packet::decode_label (char *data, int size, int &offs) 513dns_packet::decode_label (char *data, int size, int &offs)
278{ 514{
279 char *orig = data; 515 char *orig = data;
280 516
281 memset (data, 0, size); 517 memset (data, 0, size);
282 518
… …
308 return data - orig; 544 return data - orig;
309} 545}
310 546
311///////////////////////////////////////////////////////////////////////////// 547/////////////////////////////////////////////////////////////////////////////
312 548
313struct dns_req 549static
550u16 next_id ()
314{ 551{
315 dns_packet *pkt;
316 tstamp next;
317 int retry;
318 connection *conn;
319 int seqno;
320
321 dns_req (connection *c);
322 void gen_stream_req (int seqno, byte_stream *stream);
323};
324
325static u16 dns_id = 12098; // TODO: should be per-vpn 552 static u16 dns_id = 0; // TODO: should be per-vpn
326 553
327static u16 next_id () 554 if (!dns_id)
328{ 555 dns_id = time (0);
556
329 // the simplest lsfr with periodicity 65535 i could find 557 // the simplest lsfr with periodicity 65535 i could find
330 dns_id = (dns_id << 1) 558 dns_id = (dns_id << 1)
331 | (((dns_id >> 1) 559 | (((dns_id >> 1)
332 ^ (dns_id >> 2) 560 ^ (dns_id >> 2)
333 ^ (dns_id >> 4) 561 ^ (dns_id >> 4)
334 ^ (dns_id >> 15)) & 1); 562 ^ (dns_id >> 15)) & 1);
335 563
336 return dns_id; 564 return dns_id;
337} 565}
338 566
339dns_req::dns_req (connection *c) 567struct dns_rcv;
340: conn (c) 568struct dns_snd;
569
570struct dns_connection
341{ 571{
342 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;
343 retry = 0; 616 retry = 0;
617 seqno = 0;
618 sent = ev_now ();
619 stdhdr = false;
344 620
345 pkt = new dns_packet; 621 pkt = new dns_packet;
346 622
347 pkt->id = next_id (); 623 pkt->id = next_id ();
348} 624}
349 625
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
350void dns_req::gen_stream_req (int seqno, byte_stream *stream) 656dns_snd::gen_stream_req (int seqno, byte_stream &stream)
351{ 657{
658 stdhdr = true;
352 this->seqno = seqno; 659 this->seqno = seqno;
660
661 timeout = ev_now () + INITIAL_TIMEOUT;
353 662
354 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 663 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
355 pkt->qdcount = htons (1); 664 pkt->qdcount = htons (1);
356 665
357 int offs = 6*2; 666 int offs = 6*2;
358 int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2; 667 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
359 // 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,
360 // 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
361 670
362 u8 data[256]; //TODO
363
364 data[0] = THISNODE->id; //TODO
365 data[1] = seqno >> 7; //TODO
366 data[2] = seqno << 1; //TODO
367
368 int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
369
370 if (datalen > stream->size ())
371 datalen = stream->size ();
372
373 char enc[256], *encp = enc; 671 char enc[256], *encp = enc;
374 672 encode_header (enc, THISNODE->id, seqno);
375 memcpy (data + 3, stream->begin (), datalen); 673
376 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;
377 stream->remove (datalen); 680 stream.remove (datalen);
378 681
379 while (enclen) 682 while (enclen)
380 { 683 {
381 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 684 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
382 685
… …
387 encp += lbllen; 690 encp += lbllen;
388 691
389 enclen -= lbllen; 692 enclen -= lbllen;
390 } 693 }
391 694
392 const char *suffix = THISNODE->domain; 695 append_domain (*pkt, offs, dns->c->conf->domain);
393
394 // add tunnel domain
395 for (;;)
396 {
397 const char *end = strchr (suffix, '.');
398
399 if (!end)
400 end = suffix + strlen (suffix);
401
402 int len = end - suffix;
403
404 (*pkt)[offs++] = len;
405 memcpy (&((*pkt)[offs]), suffix, len);
406 offs += len;
407
408 if (!*end)
409 break;
410
411 suffix = end + 1;
412 }
413 696
414 (*pkt)[offs++] = 0; 697 (*pkt)[offs++] = 0;
415 (*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;
416 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 724 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
417 725
418 pkt->len = offs; 726 pkt->len = offs;
419} 727}
420 728
… …
439{ 747{
440 delete pkt; 748 delete pkt;
441} 749}
442 750
443///////////////////////////////////////////////////////////////////////////// 751/////////////////////////////////////////////////////////////////////////////
444 752
445struct dns_cfg 753dns_connection::dns_connection (connection *c)
754: c (c)
755, rcvdq (MAX_BACKLOG * 2)
756, snddq (MAX_BACKLOG)
446{ 757{
447 u8 id1, id2, id3; 758 tw.set<dns_connection, &dns_connection::time_cb> (this);
448 u8 def_ttl;
449 u8 unused1;
450 u16 max_size;
451 u8 flags1, flags2;
452};
453 759
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
454void connection::dnsv4_receive_rep (struct dns_rcv *r) 781dns_connection::receive_rep (dns_rcv *r)
455{ 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
456 dns_rcvpq.push_back (r); 798 rcvpq.push_back (r);
457 799
458 redo: 800 redo:
459 801
802 // find next packet
460 for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin (); 803 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461 i != dns_rcvpq.end ();
462 ++i)
463 if (dns_rcvseq == (*i)->seqno) 804 if (SEQNO_EQ (rcvseq, (*i)->seqno))
464 { 805 {
806 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
807 // enter the packet into our input stream
465 dns_rcv *r = *i; 808 r = *i;
466 809
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
467 dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; 820 rcvseq = (rcvseq + 1) & SEQNO_MASK;
468 821
469 if (!dns_snddq && !dns_rcvdq) 822 if (!rcvdq.put (r->data, r->datalen))
470 { 823 {
471 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); 824 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472 dns_snddq = new byte_stream (MAX_BACKLOG); 825 abort (); // MUST never overflow, can be caused by data corruption, TODO
473
474 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
475 } 826 }
476 827
477 if (!dns_rcvdq->put (r->data, r->datalen))
478 abort (); // MUST never overflow, can be caused by data corruption, TODO
479
480 while (vpn_packet *pkt = dns_rcvdq->get ()) 828 while (vpn_packet *pkt = rcvdq.get ())
481 { 829 {
482 sockinfo si; 830 sockinfo si;
483 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 831 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
484 832
485 vpn->recv_vpn_packet (pkt, si); 833 vpn->recv_vpn_packet (pkt, si);
834
835 delete pkt;
486 } 836 }
487 } 837
488 else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2) 838 // check for further packets
489 {
490 //D
491 //abort();
492 printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
493 dns_rcvpq.erase (i);
494 goto redo; 839 goto redo;
495 } 840 }
496} 841}
497 842
498dns_packet * 843void
499vpn::dnsv4_server (dns_packet *pkt) 844vpn::dnsv4_server (dns_packet &pkt)
500{ 845{
501 u16 flags = ntohs (pkt->flags); 846 u16 flags = ntohs (pkt.flags);
502 847
503 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504 int offs = 6 * 2; // skip header 848 int offs = 6 * 2; // skip header
505 849
506 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 850 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507 851
508 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 852 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509 && pkt->qdcount == htons (1)) 853 && pkt.qdcount == htons (1))
510 { 854 {
511 char qname[MAXSIZE]; 855 char qname [MAXSIZE];
512 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 856 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513 857
514 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 858 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 859 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516 860
517 pkt->qdcount = htons (1); 861 pkt.qdcount = htons (1);
518 pkt->ancount = 0; 862 pkt.ancount = 0;
519 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
520 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
521 865
522 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 866 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523 867
524 int dlen = strlen (THISNODE->domain); 868 int dlen = strlen (THISNODE->domain);
525 869
526 if (qclass == RR_CLASS_IN 870 if (qclass == RR_CLASS_IN
527 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528 && qlen > dlen + 1 871 && qlen > dlen + 1
529 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 872 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
530 { 873 {
531 // correct class, domain: parse 874 // now generate reply
532 u8 data[MAXSIZE]; 875 pkt.ancount = htons (1); // one answer RR
533 int datalen = dns64::decode (data, qname, qlen - dlen - 1); 876 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534 877
535 int client = data[0]; 878 if ((qtype == RR_TYPE_ANY
536 int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK; 879 || qtype == RR_TYPE_TXT
537 880 || qtype == RR_TYPE_NULL)
538 if (0 < client && client <= conns.size ()) 881 && qlen > dlen + 1 + HDRSIZE)
539 { 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 {
540 connection *c = conns [client - 1]; 892 connection *c = conns [client - 1];
893 dns_connection *dns = c->dns;
894 dns_rcv *rcv;
541 895
542 redo: 896 if (dns)
543
544 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545 i != c->dns_rcvpq.end ();
546 ++i) 897 {
898 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547 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
548 { 920 {
549 // already seen that request: simply reply with the cached reply 921 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550 dns_rcv *r = *i;
551 922
552 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
553 928
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
554 offs = r->pkt->len; 983 rcv->pkt->len = offs;
555 memcpy (pkt->at (0), r->pkt->at (0), offs); 984 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556 goto duplicate_request; 985 }
557 } 986 }
558 987
559 // new packet, queue 988 duplicate_request: ;
560 dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3); 989 }
561 c->dnsv4_receive_rep (rcv); 990 else
562
563 // now generate reply
564 pkt->ancount = htons (1); // one answer RR
565 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);
566 999
567 (*pkt) [offs++] = 0xc0;
568 (*pkt) [offs++] = 6 * 2; // same as in query section 1000 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569 1001
570 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1002 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1003 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1004 pkt [offs++] = 0; pkt [offs++] = 0;
574 (*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
575 1007
576 int dlen = MAX_PKT_SIZE - offs - 2; 1008 slog (L_INFO, _("DNS: client %d connects"), client);
577 1009
578 // 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;
579 dlen -= qlen; 1011 pkt [offs++] = CMD_IP_REJ;
580 1012
581 int rdlen_offs = offs += 2; 1013 if (0 < client && client <= conns.size ())
582
583 while (c->dns_snddq
584 && !c->dns_snddq->empty ()
585 && dlen > 1)
586 { 1014 {
587 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1015 connection *c = conns [client - 1];
588 1016
589 if (txtlen > c->dns_snddq->size ()) 1017 if (cfg.valid ())
590 txtlen = c->dns_snddq->size (); 1018 {
1019 pkt [offs - 1] = CMD_IP_SYN;
591 1020
592 (*pkt)[offs++] = txtlen; 1021 delete c->dns;
593 memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen); 1022 c->dns = new dns_connection (c);
594 offs += txtlen; 1023 c->dns->cfg = cfg;
595 c->dns_snddq->remove (txtlen); 1024 }
596
597 dlen -= txtlen + 1;
598 } 1025 }
599
600 // avoid empty TXT rdata
601 if (offs == rdlen_offs)
602 (*pkt)[offs++] = 0;
603
604 int rdlen = offs - rdlen_offs;
605
606 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
607 (*pkt) [rdlen_offs - 1] = rdlen;
608
609 // now update dns_rcv copy
610 rcv->pkt->len = offs;
611 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
612
613 duplicate_request: ;
614 } 1026 }
615 else
616 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617 } 1027 }
618 1028
619 pkt->len = offs; 1029 pkt.len = offs;
620 } 1030 }
621
622 return pkt;
623} 1031}
624 1032
625void 1033void
626vpn::dnsv4_client (dns_packet *pkt) 1034vpn::dnsv4_client (dns_packet &pkt)
627{ 1035{
628 u16 flags = ntohs (pkt->flags); 1036 u16 flags = ntohs (pkt.flags);
629 int offs = 6 * 2; // skip header 1037 int offs = 6 * 2; // skip header
630 1038
631 pkt->qdcount = ntohs (pkt->qdcount); 1039 pkt.qdcount = ntohs (pkt.qdcount);
632 pkt->ancount = ntohs (pkt->ancount); 1040 pkt.ancount = ntohs (pkt.ancount);
633 1041
634 // go through our request list and find the corresponding request 1042 // go through our request list and find the corresponding request
635 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1043 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636 i != dns_sndpq.end (); 1044 i != dns_sndpq.end ();
637 ++i) 1045 ++i)
638 if ((*i)->pkt->id == pkt->id) 1046 if ((*i)->pkt->id == pkt.id)
639 { 1047 {
1048 dns_connection *dns = (*i)->dns;
640 connection *c = (*i)->conn; 1049 connection *c = dns->c;
641 int seqno = (*i)->seqno; 1050 int seqno = (*i)->seqno;
642 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 }
643 1078
644 delete *i; 1079 delete *i;
645 dns_sndpq.erase (i); 1080 dns_sndpq.erase (i);
646 1081
647 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1082 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648 { 1083 {
649 char qname[MAXSIZE]; 1084 char qname[MAXSIZE];
650 1085
651 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1086 while (pkt.qdcount-- && offs < MAXSIZE - 4)
652 { 1087 {
653 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1088 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654 offs += 4; // skip qtype, qclass 1089 offs += 4; // skip qtype, qclass
655 } 1090 }
656 1091
657 while (pkt->ancount-- && offs < MAXSIZE - 10) 1092 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658 { 1093 {
659 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1094 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660 1095
661 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1096 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1097 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663 u32 ttl = (*pkt) [offs++] << 24; 1098 u32 ttl = pkt [offs++] << 24;
664 ttl |= (*pkt) [offs++] << 16; 1099 ttl |= pkt [offs++] << 16;
665 ttl |= (*pkt) [offs++] << 8; 1100 ttl |= pkt [offs++] << 8;
666 ttl |= (*pkt) [offs++]; 1101 ttl |= pkt [offs++];
667
668 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1102 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669 1103
670 if (rdlen <= MAXSIZE - offs) 1104 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671 { 1105 {
672 // decode bytes, finally 1106 if (rdlen <= MAXSIZE - offs)
673
674 while (rdlen)
675 { 1107 {
1108 // decode bytes, finally
1109
1110 while (rdlen)
1111 {
676 int txtlen = (*pkt) [offs++]; 1112 int txtlen = pkt [offs++];
677 1113
678 assert (txtlen + offs < MAXSIZE - 1); 1114 assert (txtlen + offs < MAXSIZE - 1);
679 1115
680 memcpy (datap, pkt->at (offs), txtlen); 1116 memcpy (datap, pkt.at (offs), txtlen);
681 datap += txtlen; offs += txtlen; 1117 datap += txtlen; offs += txtlen;
682 1118
683 rdlen -= txtlen + 1; 1119 rdlen -= txtlen + 1;
1120 }
684 } 1121 }
685
686 } 1122 }
1123 else if (qtype == RR_TYPE_A)
1124 {
1125 u8 ip [4];
687 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 }
688 } 1179 }
689 } 1180 }
690 1181
691 // todo: pkt now used 1182 // todo: pkt now used
1183 if (datap)
692 c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data)); 1184 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693 1185
694 break; 1186 break;
695 } 1187 }
696
697 delete pkt;
698} 1188}
699 1189
700void 1190void
701vpn::dnsv4_ev (io_watcher &w, short revents) 1191vpn::dnsv4_ev (ev::io &w, int revents)
702{ 1192{
703 if (revents & EVENT_READ) 1193 if (revents & EV_READ)
704 { 1194 {
705 dns_packet *pkt = new dns_packet; 1195 dns_packet *pkt = new dns_packet;
706 struct sockaddr_in sa; 1196 struct sockaddr_in sa;
707 socklen_t sa_len = sizeof (sa); 1197 socklen_t sa_len = sizeof (sa);
708 1198
709 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);
710 1200
711 if (pkt->len > 0) 1201 if (pkt->len > 0)
712 { 1202 {
713 if (pkt->flags & htons (FLAG_TC)) 1203 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1204 dnsv4_client (*pkt);
1205 else
714 { 1206 {
715 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1207 dnsv4_server (*pkt);
716 //TODO connection reset 1208 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717 } 1209 }
718 1210
719 if (THISNODE->dns_port) 1211 delete pkt;
720 {
721 pkt = dnsv4_server (pkt);
722 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
723 }
724 else
725 dnsv4_client (pkt);
726 } 1212 }
727 } 1213 }
728} 1214}
729 1215
730bool 1216bool
731connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1217vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
732{ 1218{
733 // never initialized 1219 int client = ntohl (si.host);
734 if (!dns_snddq && !dns_rcvdq)
735 {
736 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
737 dns_snddq = new byte_stream (MAX_BACKLOG);
738 1220
739 //dns_rcvseq = dns_sndseq = 0; 1221 assert (0 < client && client <= conns.size ());
740 1222
741 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1223 connection *c = conns [client - 1];
742 } 1224
1225 if (!c->dns)
1226 c->dns = new dns_connection (c);
743 1227
744 if (!dns_snddq->put (pkt)) 1228 if (c->dns->snddq.put (pkt))
745 return false; 1229 c->dns->tw ();
746 1230
747 // start timer if neccessary 1231 // always return true even if the buffer overflows
748 if (!THISNODE->dns_port && !dnsv4_tw.active)
749 dnsv4_cb (dnsv4_tw);
750
751 return true; 1232 return true;
752} 1233}
753 1234
754void 1235void
755connection::dnsv4_cb (time_watcher &w) 1236connection::dnsv4_reset_connection ()
756{ 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
757 // check for timeouts and (re)transmit 1250 // check for timeouts and (re)transmit
758 tstamp next = NOW + 60; 1251 tstamp next = ev::now () + poll_interval;
759 dns_req *send = 0; 1252 dns_snd *send = 0;
760 1253
761 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1254 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762 i != vpn->dns_sndpq.end (); 1255 i != vpn->dns_sndpq.end ();
763 ++i) 1256 ++i)
764 { 1257 {
765 dns_req *r = *i; 1258 dns_snd *r = *i;
766 1259
767 if (r->next <= NOW) 1260 if (r->timeout <= ev_now ())
768 { 1261 {
769 if (!send) 1262 if (!send)
770 { 1263 {
771 send = r; 1264 send = r;
772 1265
773 if (r->retry)//D
774 printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775 r->retry++; 1266 r->retry++;
776 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);
777 } 1274 }
778 } 1275 }
779 1276 else
780 if (r->next < next) 1277 NEXT (r->timeout);
781 next = r->next;
782 } 1278 }
783 1279
784 if (!send 1280 if (!send)
785 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
786 { 1281 {
1282 // generate a new packet, if wise
1283
1284 if (!established)
1285 {
1286 if (vpn->dns_sndpq.empty ())
1287 {
787 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);
788 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)
789 vpn->dns_sndpq.push_back (send); 1318 vpn->dns_sndpq.push_back (send);
790
791 dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792 } 1319 }
793
794 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795 1320
796 if (send) 1321 if (send)
797 { 1322 {
798 dns_packet *pkt = send->pkt; 1323 last_sent = ev_now ();
799 1324 sendto (vpn->dnsv4_fd,
800 next = min_next; 1325 send->pkt->at (0), send->pkt->len, 0,
801 1326 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
802 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
803 } 1327 }
804 else if (next < min_next)
805 next = min_next;
806 1328
807 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 ());
808} 1340}
809 1341
810#endif 1342#endif
811 1343

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines