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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 UTC vs.
Revision 1.49 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 10 // max. outstanding requests 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
69
70#define MAX_SEND_INTERVAL 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 1 // requests/s
50#define MAX_BACKLOG (10*1024) // size of protocol backlog 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51 74
52/* 75#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
76// 240 leaves about 4 bytes of server reply data
77// every request byte less give room for two reply bytes
53 78
54protocol, in shorthand :) 79#define SEQNO_MASK 0x3fff
55 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
56client -> server <req> ANY?
57server -> client <req> TXT <rep>
58
59<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
60<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
61
62if <client-id> is zero, the connection will be configured:
63
64<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
65
66*/
67 81
68#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
69#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
70 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
71#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
72#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
73#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
74 92
75// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 93#define CMD_IP_1 207
76struct dns64 94#define CMD_IP_2 46
77{ 95#define CMD_IP_3 236
78 static const char encode_chars[64 + 1]; 96#define CMD_IP_RST 29
79 static s8 decode_chars[256]; 97#define CMD_IP_SYN 113
98#define CMD_IP_REJ 32
80 99
81 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 100// works for cmaps up to 255 (not 256!)
82 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
83 static int encode (char *dst, u8 *src, int len); 143 unsigned int encode (char *dst, u8 *src, unsigned int len);
84 static int decode (u8 *dst, char *src, int len); 144 unsigned int decode (u8 *dst, char *src, unsigned int len);
85 145
86 dns64 (); 146 basecoder (const char *cmap);
87} dns64; 147};
88 148
89const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-"; 149basecoder::basecoder (const char *cmap)
90s8 dns64::decode_chars[256]; 150: cmap (cmap)
91
92dns64::dns64 ()
93{ 151{
94 for (int i = 0; i < 64; i++) 152 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95 decode_chars [encode_chars [i]] = i + 1; 153 {
96} 154 u8 src [MAX_DEC_LEN];
155 u8 dst [MAX_ENC_LEN];
97 156
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
98int dns64::encode (char *dst, u8 *src, int len) 189basecoder::encode (char *dst, u8 *src, unsigned int len)
99{ 190{
100 // slow, but easy to debug 191 if (!len || len > MAX_DEC_LEN)
101 char *beg = dst; 192 return 0;
102 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;
103 226
104 while (len--) 227 while (len--)
105 { 228 {
106 accum <<= 8; 229 u8 val = cmap.decode [(u8)*src++];
107 accum |= *src++;
108 bits += 8;
109 230
110 while (bits >= 6) 231 if (val != charmap::INVALID)
111 { 232 src_ [elen++] = val;
112 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 233 }
113 bits -= 6; 234
114 } 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)
115 } 246 {
247 memset (dst, 0, dlen - n);
248 memcpy (dst + dlen - n, dst_, n);
249 }
250 else
251 memcpy (dst, dst_ + n - dlen, dlen);
116 252
117 if (bits) 253 return dlen;
118 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120 return dst - beg;
121} 254}
122 255
123int dns64::decode (u8 *dst, char *src, int len) 256#if 0
124{ 257struct test { test (); } test;
125 // slow, but easy to debug
126 u8 *beg = dst;
127 unsigned int accum, bits = 0;
128 258
129 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++)
130 { 268 {
131 s8 chr = decode_chars [(u8)*src++]; 269 int elen = cdc.encode (enc, in, i);
270 int dlen = cdc.decode (dec, enc, elen);
132 271
133 if (!chr) 272 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
134 break;
135
136 accum <<= 6;
137 accum |= chr - 1;
138 bits += 6;
139
140 while (bits >= 8)
141 {
142 *dst++ = accum >> (bits - 8);
143 bits -= 8;
144 }
145 } 273 }
274 abort ();
275}
276#endif
146 277
147 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;
148} 313}
149 314
150///////////////////////////////////////////////////////////////////////////// 315/////////////////////////////////////////////////////////////////////////////
151 316
152struct byte_stream 317struct byte_stream
… …
159 ~byte_stream (); 324 ~byte_stream ();
160 325
161 bool empty () { return !fill; } 326 bool empty () { return !fill; }
162 int size () { return fill; } 327 int size () { return fill; }
163 328
329 bool put (u8 *data, unsigned int datalen);
164 bool put (vpn_packet *pkt); 330 bool put (vpn_packet *pkt);
165 vpn_packet *get (); 331 vpn_packet *get ();
166 332
167 u8 *begin () { return data; } 333 u8 *begin () { return data; }
168 void remove (int count); 334 void remove (int count);
… …
177byte_stream::~byte_stream () 343byte_stream::~byte_stream ()
178{ 344{
179 delete data; 345 delete data;
180} 346}
181 347
348void
182void byte_stream::remove (int count) 349byte_stream::remove (int count)
183{ 350{
184 if (count > fill) 351 if (count > fill)
185 abort (); 352 assert (count <= fill);
186 353
187 memmove (data, data + count, fill -= count); 354 memmove (data, data + count, fill -= count);
188} 355}
189 356
357bool
358byte_stream::put (u8 *data, unsigned int datalen)
359{
360 if (maxsize - fill < datalen)
361 return false;
362
363 memcpy (this->data + fill, data, datalen); fill += datalen;
364
365 return true;
366}
367
368bool
190bool byte_stream::put (vpn_packet *pkt) 369byte_stream::put (vpn_packet *pkt)
191{ 370{
192 if (maxsize - fill < pkt->len + 2) 371 if (maxsize - fill < pkt->len + 2)
193 return false; 372 return false;
194 373
195 data [fill++] = pkt->len >> 8; 374 data [fill++] = pkt->len >> 8;
196 data [fill++] = pkt->len; 375 data [fill++] = pkt->len;
197 376
198 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 377 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199 378
200 return true; 379 return true;
201} 380}
202 381
203vpn_packet *byte_stream::get () 382vpn_packet *byte_stream::get ()
204{ 383{
384 unsigned int len;
385
386 for (;;)
387 {
205 int len = (data [0] << 8) | data [1]; 388 len = (data [0] << 8) | data [1];
206 389
390 if (len <= MAXSIZE || fill < 2)
391 break;
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
207 if (fill < len + 2) 398 if (fill < len + 2)
208 return 0; 399 return 0;
209 400
210 vpn_packet *pkt = new vpn_packet; 401 vpn_packet *pkt = new vpn_packet;
402
403 pkt->len = len;
211 memcpy (&((*pkt)[0]), data + 2, len); 404 memcpy (pkt->at (0), data + 2, len);
212 remove (len + 2); 405 remove (len + 2);
213 406
214 return pkt; 407 return pkt;
215} 408}
216 409
217///////////////////////////////////////////////////////////////////////////// 410/////////////////////////////////////////////////////////////////////////////
218 411
219#define FLAG_QUERY ( 0 << 15) 412#define FLAG_QUERY ( 0 << 15)
220#define FLAG_RESPONSE ( 1 << 15) 413#define FLAG_RESPONSE ( 1 << 15)
221#define FLAG_OP_MASK (15 << 14) 414#define FLAG_OP_MASK (15 << 11)
222#define FLAG_OP_QUERY ( 0 << 11) 415#define FLAG_OP_QUERY ( 0 << 11)
223#define FLAG_AA ( 1 << 10) 416#define FLAG_AA ( 1 << 10)
224#define FLAG_TC ( 1 << 9) 417#define FLAG_TC ( 1 << 9)
225#define FLAG_RD ( 1 << 8) 418#define FLAG_RD ( 1 << 8)
226#define FLAG_RA ( 1 << 7) 419#define FLAG_RA ( 1 << 7)
420#define FLAG_AUTH ( 1 << 5)
227#define FLAG_RCODE_MASK (15 << 0) 421#define FLAG_RCODE_MASK (15 << 0)
228#define FLAG_RCODE_OK ( 0 << 0) 422#define FLAG_RCODE_OK ( 0 << 0)
229#define FLAG_RCODE_FORMERR ( 1 << 0) 423#define FLAG_RCODE_FORMERR ( 1 << 0)
230#define FLAG_RCODE_SERVFAIL ( 2 << 0) 424#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231#define FLAG_RCODE_NXDOMAIN ( 3 << 0) 425#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232#define FLAG_RCODE_REFUSED ( 5 << 0) 426#define FLAG_RCODE_REFUSED ( 5 << 0)
233 427
234#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 428#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
235#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD) 429#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
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}
236 500
237struct dns_packet : net_packet 501struct dns_packet : net_packet
238{ 502{
239 u16 id; 503 u16 id;
240 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
241 u16 qdcount, ancount, nscount, arcount; 505 u16 qdcount, ancount, nscount, arcount;
242 506
243 u8 data[MAXSIZE - 6 * 2]; 507 u8 data [MAXSIZE - 6 * 2];
244 508
245 int decode_label (char *data, int size, int &offs); 509 int decode_label (char *data, int size, int &offs);
246}; 510};
247 511
512int
248int dns_packet::decode_label (char *data, int size, int &offs) 513dns_packet::decode_label (char *data, int size, int &offs)
249{ 514{
250 char *orig = data; 515 char *orig = data;
251 516
252 memset (data, 0, size); 517 memset (data, 0, size);
253 518
… …
279 return data - orig; 544 return data - orig;
280} 545}
281 546
282///////////////////////////////////////////////////////////////////////////// 547/////////////////////////////////////////////////////////////////////////////
283 548
549static
550u16 next_id ()
551{
552 static u16 dns_id = 0; // TODO: should be per-vpn
553
554 if (!dns_id)
555 dns_id = time (0);
556
557 // the simplest lsfr with periodicity 65535 i could find
558 dns_id = (dns_id << 1)
559 | (((dns_id >> 1)
560 ^ (dns_id >> 2)
561 ^ (dns_id >> 4)
562 ^ (dns_id >> 15)) & 1);
563
564 return dns_id;
565}
566
284struct dns_req 567struct dns_rcv;
568struct dns_snd;
569
570struct dns_connection
571{
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
285{ 597{
286 dns_packet *pkt; 598 dns_packet *pkt;
287 tstamp next; 599 tstamp timeout, sent;
288 int retry; 600 int retry;
289 connection *conn; 601 struct dns_connection *dns;
602 int seqno;
603 bool stdhdr;
290 604
291 dns_req (connection *c, int seqno, byte_stream *stream); 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 ();
292}; 610};
293 611
294struct dns_rep 612dns_snd::dns_snd (dns_connection *dns)
613: dns (dns)
295{ 614{
296}; 615 timeout = 0;
297
298static u16 dns_id; // TODO: should be per-vpn
299
300dns_req::dns_req (connection *c, int seqno, byte_stream *stream)
301: conn (c)
302{
303 next = 0;
304 retry = 0; 616 retry = 0;
617 seqno = 0;
618 sent = ev_now ();
619 stdhdr = false;
305 620
306 pkt = new dns_packet; 621 pkt = new dns_packet;
307 622
308 pkt->id = dns_id++; 623 pkt->id = next_id ();
309 pkt->flags = DEFAULT_CLIENT_FLAGS; 624}
310 pkt->qdcount = htons (1);
311 pkt->ancount = 0;
312 pkt->nscount = 0;
313 pkt->arcount = 0;
314 625
315 int offs = 6*2; 626dns_snd::~dns_snd ()
316 int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length 627{
628 delete pkt;
629}
317 630
318 u8 lbl[64]; //D 631static void
319 char enc[65]; 632append_domain (dns_packet &pkt, int &offs, const char *domain)
320 int lbllen = 3; 633{
321 lbl[0] = c->conf->id; //D
322 lbl[1] = seqno >> 8; //D
323 lbl[2] = seqno; //D
324
325 while (dlen > 0)
326 {
327 int sndlen = dlen;
328
329 if (sndlen + lbllen > dns64::decode_len (MAX_LBL_SIZE))
330 sndlen = dns64::decode_len (MAX_LBL_SIZE) - lbllen;
331
332 if (sndlen > stream->size ())
333 sndlen = stream->size ();
334
335 if (sndlen + lbllen == 0)
336 break;
337
338 memcpy (lbl + lbllen, stream->begin (), sndlen);
339 stream->remove (sndlen);
340 lbllen += sndlen;
341
342 dns64::encode (enc, lbl, lbllen);
343
344 int elen = dns64::encode_len (lbllen);
345 (*pkt)[offs++] = elen;
346 memcpy (&((*pkt)[offs]), enc, elen);
347 offs += elen;
348 dlen -= elen + 1;
349
350 lbllen = 0;
351 }
352
353 const char *suffix = THISNODE->domain;
354
355 // add tunnel domain 634 // add tunnel domain
356 for (;;) 635 for (;;)
357 { 636 {
358 const char *end = strchr (suffix, '.'); 637 const char *end = strchr (domain, '.');
359 638
360 if (!end) 639 if (!end)
361 end = suffix + strlen (suffix); 640 end = domain + strlen (domain);
362 641
363 int len = end - suffix; 642 int len = end - domain;
364 643
365 (*pkt)[offs++] = len; 644 pkt [offs++] = len;
366 memcpy (&((*pkt)[offs]), suffix, len); 645 memcpy (pkt.at (offs), domain, len);
367 offs += len; 646 offs += len;
368 647
369 if (!*end) 648 if (!*end)
370 break; 649 break;
371 650
372 suffix = end + 1; 651 domain = end + 1;
652 }
653}
654
655void
656dns_snd::gen_stream_req (int seqno, byte_stream &stream)
657{
658 stdhdr = true;
659 this->seqno = seqno;
660
661 timeout = ev_now () + INITIAL_TIMEOUT;
662
663 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
664 pkt->qdcount = htons (1);
665
666 int offs = 6*2;
667 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
668 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
669 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
670
671 char enc[256], *encp = enc;
672 encode_header (enc, THISNODE->id, seqno);
673
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;
680 stream.remove (datalen);
681
682 while (enclen)
373 } 683 {
684 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
685
686 (*pkt)[offs++] = lbllen;
687 memcpy (pkt->at (offs), encp, lbllen);
688
689 offs += lbllen;
690 encp += lbllen;
691
692 enclen -= lbllen;
693 }
694
695 append_domain (*pkt, offs, dns->c->conf->domain);
374 696
375 (*pkt)[offs++] = 0; 697 (*pkt)[offs++] = 0;
376 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 698 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 699 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378 700
379 pkt->len = offs; 701 pkt->len = offs;
702}
380 703
381 c->vpn->dns_sndpq.push_back (this); 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;
724 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
725
726 pkt->len = offs;
727}
728
729struct dns_rcv
730{
731 int seqno;
732 dns_packet *pkt; // reply packet
733 u8 data [MAXSIZE]; // actually part of the reply packet...
734 int datalen;
735
736 dns_rcv (int seqno, u8 *data, int datalen);
737 ~dns_rcv ();
738};
739
740dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
741: seqno (seqno), pkt (new dns_packet), datalen (datalen)
742{
743 memcpy (this->data, data, datalen);
744}
745
746dns_rcv::~dns_rcv ()
747{
748 delete pkt;
382} 749}
383 750
384///////////////////////////////////////////////////////////////////////////// 751/////////////////////////////////////////////////////////////////////////////
385 752
386struct dns_cfg 753dns_connection::dns_connection (connection *c)
754: c (c)
755, rcvdq (MAX_BACKLOG * 2)
756, snddq (MAX_BACKLOG)
387{ 757{
388 u8 id1, id2, id3; 758 tw.set<dns_connection, &dns_connection::time_cb> (this);
389 u8 def_ttl;
390 u8 unused1;
391 u16 max_size;
392 u8 flags1, flags2;
393};
394 759
395dns_packet * 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
781dns_connection::receive_rep (dns_rcv *r)
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
798 rcvpq.push_back (r);
799
800 redo:
801
802 // find next packet
803 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
804 if (SEQNO_EQ (rcvseq, (*i)->seqno))
805 {
806 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
807 // enter the packet into our input stream
808 r = *i;
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
820 rcvseq = (rcvseq + 1) & SEQNO_MASK;
821
822 if (!rcvdq.put (r->data, r->datalen))
823 {
824 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
825 abort (); // MUST never overflow, can be caused by data corruption, TODO
826 }
827
828 while (vpn_packet *pkt = rcvdq.get ())
829 {
830 sockinfo si;
831 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
832
833 vpn->recv_vpn_packet (pkt, si);
834
835 delete pkt;
836 }
837
838 // check for further packets
839 goto redo;
840 }
841}
842
843void
396vpn::dnsv4_server (dns_packet *pkt) 844vpn::dnsv4_server (dns_packet &pkt)
397{ 845{
398 u16 flags = ntohs (pkt->flags); 846 u16 flags = ntohs (pkt.flags);
399 847
400 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401 int offs = 6 * 2; // skip header 848 int offs = 6 * 2; // skip header
402 849
403 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 850 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404 851
405 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 852 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406 && pkt->qdcount == htons (1)) 853 && pkt.qdcount == htons (1))
407 { 854 {
408 char qname[MAXSIZE]; 855 char qname [MAXSIZE];
409 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 856 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410 857
411 printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", pkt->len,
412 pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
413
414 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 858 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 859 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416 860
417 pkt->qdcount = htons (1); 861 pkt.qdcount = htons (1);
418 pkt->ancount = 0; 862 pkt.ancount = 0;
419 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
420 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
421 865
422 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 866 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423 867
424 int dlen = strlen (THISNODE->domain); 868 int dlen = strlen (THISNODE->domain);
425 869
426 if (qclass == RR_CLASS_IN 870 if (qclass == RR_CLASS_IN
427 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428 && qlen > dlen + 1 871 && qlen > dlen + 1
429 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 872 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430 { 873 {
431 // correct class, domain, parse
432 u8 data[MAXSIZE];
433 int datalen = dns64::decode (data, qname, qlen - dlen - 1);
434
435 for (int i = 0; i < datalen; i++)
436 printf ("%02x ", data[i]);
437 printf ("\n");
438
439
440
441
442#if 0
443 // now generate reply 874 // now generate reply
444 rep->ancount = htons (1); // one answer RR 875 pkt.ancount = htons (1); // one answer RR
445 rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 876 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446 877
447 (*rep) [offs++] = 0xc0; 878 if ((qtype == RR_TYPE_ANY
448 (*rep) [offs++] = 6 * 2; // same as in query section 879 || qtype == RR_TYPE_TXT
449 880 || qtype == RR_TYPE_NULL)
450 (*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT; 881 && qlen > dlen + 1 + HDRSIZE)
451 (*rep) [offs++] = RR_CLASS_IN >> 8; (*rep) [offs++] = RR_CLASS_IN;
452
453 (*rep) [offs++] = 0; (*rep) [offs++] = 0;
454 (*rep) [offs++] = 0; (*rep) [offs++] = 0; // TTL
455
456 int dlen = MAX_PKT_SIZE - offs - 2;
457
458 printf ("we have room for %d bytes\n", dlen);
459
460 int rdlen_offs = offs += 2;
461
462 u8 txt[255];
463 txt[0] = 0;
464 txt[1] = 0;
465
466 int txtlen = 2;
467
468 while (dlen > 1)
469 { 882 {
470 int sndlen = --dlen; 883 // correct class, domain: parse
884 int client, seqno;
885 decode_header (qname, client, seqno);
471 886
472 if (sndlen + txtlen > 255) 887 u8 data[MAXSIZE];
473 sndlen = 255 - txtlen; 888 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
474 889
475 sndlen = 0; 890 if (0 < client && client <= conns.size ())
891 {
892 connection *c = conns [client - 1];
893 dns_connection *dns = c->dns;
894 dns_rcv *rcv;
476 895
477 (*rep)[offs++] = sndlen + txtlen; 896 if (dns)
478 memcpy (&((*rep)[offs]), txt, txtlen); 897 {
898 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
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
920 {
921 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
922
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
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);
479 offs += txtlen; 955 offs += txtlen;
956 dns->snddq.remove (txtlen);
480 957
481 //if (sndlen + txtlen > dns_snddq. 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
983 rcv->pkt->len = offs;
984 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
985 }
986 }
987
988 duplicate_request: ;
989 }
990 else
991 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
482 } 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);
483 999
484 int rdlen = offs - rdlen_offs; 1000 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485 1001
486 (*rep) [rdlen_offs - 2] = rdlen >> 8; 1002 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487 (*rep) [rdlen_offs - 1] = rdlen; 1003 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488#endif 1004 pkt [offs++] = 0; pkt [offs++] = 0;
1005 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1006 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
1007
1008 slog (L_INFO, _("DNS: client %d connects"), client);
1009
1010 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
1011 pkt [offs++] = CMD_IP_REJ;
1012
1013 if (0 < client && client <= conns.size ())
1014 {
1015 connection *c = conns [client - 1];
1016
1017 if (cfg.valid ())
1018 {
1019 pkt [offs - 1] = CMD_IP_SYN;
1020
1021 delete c->dns;
1022 c->dns = new dns_connection (c);
1023 c->dns->cfg = cfg;
1024 }
1025 }
1026 }
489 } 1027 }
490 }
491 1028
492 pkt->len = offs; 1029 pkt.len = offs;
493 return pkt; 1030 }
494} 1031}
495 1032
496void 1033void
497vpn::dnsv4_client (dns_packet *pkt) 1034vpn::dnsv4_client (dns_packet &pkt)
498{ 1035{
499 u16 flags = ntohs (pkt->flags); 1036 u16 flags = ntohs (pkt.flags);
500 int offs = 6 * 2; // skip header 1037 int offs = 6 * 2; // skip header
501 1038
502 pkt->qdcount = ntohs (pkt->qdcount); 1039 pkt.qdcount = ntohs (pkt.qdcount);
503 pkt->ancount = ntohs (pkt->ancount); 1040 pkt.ancount = ntohs (pkt.ancount);
504 1041
1042 // go through our request list and find the corresponding request
505 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1043 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506 i != dns_sndpq.end (); 1044 i != dns_sndpq.end ();
507 ++i) 1045 ++i)
508 if ((*i)->pkt->id == pkt->id) 1046 if ((*i)->pkt->id == pkt.id)
509 { 1047 {
1048 dns_connection *dns = (*i)->dns;
510 connection *c = (*i)->conn; 1049 connection *c = dns->c;
511 printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D 1050 int seqno = (*i)->seqno;
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 }
1078
512 delete *i; 1079 delete *i;
513 dns_sndpq.erase (i); 1080 dns_sndpq.erase (i);
514 1081
515 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1082 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516 { 1083 {
517 char qname[MAXSIZE]; 1084 char qname[MAXSIZE];
518 1085
519 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1086 while (pkt.qdcount-- && offs < MAXSIZE - 4)
520 { 1087 {
521 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1088 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522 offs += 4; // skip qtype, qclass 1089 offs += 4; // skip qtype, qclass
523 } 1090 }
524 1091
525 while (pkt->ancount-- && offs < MAXSIZE - 10) 1092 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526 { 1093 {
527 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1094 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528 1095
529 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1096 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1097 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531 u32 ttl = (*pkt) [offs++] << 24; 1098 u32 ttl = pkt [offs++] << 24;
532 ttl |= (*pkt) [offs++] << 16; 1099 ttl |= pkt [offs++] << 16;
533 ttl |= (*pkt) [offs++] << 8; 1100 ttl |= pkt [offs++] << 8;
534 ttl |= (*pkt) [offs++]; 1101 ttl |= pkt [offs++];
535
536 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1102 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537 1103
538 printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen); 1104 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
539
540 offs += rdlen;
541
542 if (MAXSIZE - offs < rdlen)
543 { 1105 {
1106 if (rdlen <= MAXSIZE - offs)
1107 {
544 // decode bytes, finally 1108 // decode bytes, finally
1109
1110 while (rdlen)
1111 {
1112 int txtlen = pkt [offs++];
1113
1114 assert (txtlen + offs < MAXSIZE - 1);
1115
1116 memcpy (datap, pkt.at (offs), txtlen);
1117 datap += txtlen; offs += txtlen;
1118
1119 rdlen -= txtlen + 1;
1120 }
1121 }
1122 }
1123 else if (qtype == RR_TYPE_A)
1124 {
1125 u8 ip [4];
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;
545 } 1178 }
546 } 1179 }
547 } 1180 }
548 1181
1182 // todo: pkt now used
1183 if (datap)
1184 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
1185
549 break; 1186 break;
550 } 1187 }
551} 1188}
552 1189
553void 1190void
554vpn::dnsv4_ev (io_watcher &w, short revents) 1191vpn::dnsv4_ev (ev::io &w, int revents)
555{ 1192{
556 if (revents & EVENT_READ) 1193 if (revents & EV_READ)
557 { 1194 {
558 dns_packet *pkt = new dns_packet; 1195 dns_packet *pkt = new dns_packet;
559 struct sockaddr_in sa; 1196 struct sockaddr_in sa;
560 socklen_t sa_len = sizeof (sa); 1197 socklen_t sa_len = sizeof (sa);
561 1198
562 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);
563 1200
564 if (pkt->len > 0) 1201 if (pkt->len > 0)
565 if (THISNODE->dns_port)
566 { 1202 {
567 pkt = dnsv4_server (pkt); 1203 if (ntohs (pkt->flags) & FLAG_RESPONSE)
568 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
569 }
570 else
571 dnsv4_client (pkt); 1204 dnsv4_client (*pkt);
1205 else
1206 {
1207 dnsv4_server (*pkt);
1208 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1209 }
1210
1211 delete pkt;
1212 }
572 } 1213 }
573} 1214}
574 1215
575bool 1216bool
576connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1217vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577{ 1218{
578 // never initialized 1219 int client = ntohl (si.host);
579 if (!dns_snddq && !dns_rcvdq)
580 {
581 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
582 dns_snddq = new byte_stream (MAX_BACKLOG);
583 1220
584 dns_rcvseq = dns_sndseq = 0; 1221 assert (0 < client && client <= conns.size ());
585 1222
586 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1223 connection *c = conns [client - 1];
587 } 1224
1225 if (!c->dns)
1226 c->dns = new dns_connection (c);
588 1227
589 if (!dns_snddq->put (pkt)) 1228 if (c->dns->snddq.put (pkt))
590 return false; 1229 c->dns->tw ();
591 1230
592 // start timer if neccessary 1231 // always return true even if the buffer overflows
593 if (!dnsv4_tw.active)
594 dnsv4_cb (dnsv4_tw);
595
596 return true; 1232 return true;
597} 1233}
598 1234
599void 1235void
600connection::dnsv4_cb (time_watcher &w) 1236connection::dnsv4_reset_connection ()
601{ 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
602 // check for timeouts and (re)transmit 1250 // check for timeouts and (re)transmit
603 tstamp next = NOW + 60; 1251 tstamp next = ev::now () + poll_interval;
604 dns_req *send = 0; 1252 dns_snd *send = 0;
605 1253
606 slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), vpn->dns_sndpq.size ());
607
608 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1254 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609 i != vpn->dns_sndpq.end (); 1255 i != vpn->dns_sndpq.end ();
610 ++i) 1256 ++i)
611 { 1257 {
612 dns_req *r = *i; 1258 dns_snd *r = *i;
613 1259
614 if (r->next <= NOW) 1260 if (r->timeout <= ev_now ())
615 { 1261 {
616 if (!send) 1262 if (!send)
617 { 1263 {
618 send = r; 1264 send = r;
619 1265
620 slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621 r->retry++; 1266 r->retry++;
622 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);
623 } 1274 }
624 } 1275 }
625 1276 else
626 if (r->next < next) 1277 NEXT (r->timeout);
627 next = r->next;
628 } 1278 }
629 1279
630 if (!send 1280 if (!send)
631 && vpn->dns_sndpq.size () < MAX_OUTSTANDING) 1281 {
632 send = new dns_req (this, dns_sndseq++, dns_snddq); 1282 // generate a new packet, if wise
633 1283
634 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE); 1284 if (!established)
1285 {
1286 if (vpn->dns_sndpq.empty ())
1287 {
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);
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)
1318 vpn->dns_sndpq.push_back (send);
1319 }
635 1320
636 if (send) 1321 if (send)
637 { 1322 {
638 dns_packet *pkt = send->pkt; 1323 last_sent = ev_now ();
639 1324 sendto (vpn->dnsv4_fd,
640 next = min_next; 1325 send->pkt->at (0), send->pkt->len, 0,
641 1326 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
642 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
643 } 1327 }
644 else if (next < min_next)
645 next = min_next;
646 1328
647 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 ());
648} 1340}
649 1341
650#endif 1342#endif
651 1343

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