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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 1.46 by pcg, Thu Dec 6 00:35:29 2007 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) 2003-2005 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
6 it under the terms of the GNU General Public License as published by 8 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or 9 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version. 10 (at your 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,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 but 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
13 GNU General Public License for more details. 15 GNU General 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
16 along with this program; if not, write to the Free Software 18 along with gvpe; if not, write to the Free Software
17 Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18*/ 20*/
21
22// TODO: EDNS0 option to increase dns mtu?
23// TODO: re-write dns packet parsing/creation using a safe mem-buffer
24// to ensure no buffer overflows or similar problems.
19 25
20#include "config.h" 26#include "config.h"
21 27
22#if ENABLE_DNS 28#if ENABLE_DNS
23 29
24// dns processing is EXTREMELY ugly. For obvious(?) reasons. 30// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25// it's a hack, use only in emergency situations please. 31// it's a hack, use only in emergency situations please.
26 32
27#include <cstring> 33#include <cstring>
34#include <cassert>
28 35
29#include <sys/types.h> 36#include <sys/types.h>
30#include <sys/socket.h> 37#include <sys/socket.h>
31#include <sys/wait.h> 38#include <sys/wait.h>
32#include <sys/uio.h> 39#include <sys/uio.h>
35#include <unistd.h> 42#include <unistd.h>
36#include <fcntl.h> 43#include <fcntl.h>
37 44
38#include <map> 45#include <map>
39 46
47#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
48#include <gmp.h>
49
40#include "netcompat.h" 50#include "netcompat.h"
41 51
42#include "vpn.h" 52#include "vpn.h"
43 53
44#define MIN_RETRY 1. 54#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45#define MAX_RETRY 60. 55#define ACTIVITY_INTERVAL 5.
46 56
47#define MAX_OUTSTANDING 10 // max. outstanding requests 57#define INITIAL_TIMEOUT 0.1 // retry timeouts
58#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
59
60#define MAX_SEND_INTERVAL 2. // optimistic?
61
48#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 62#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 63#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51 64
52/* 65#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
66// 240 leaves about 4 bytes of server reply data
67// every request byte less give room for two reply bytes
53 68
54protocol, in shorthand :) 69#define SEQNO_MASK 0x3fff
55 70#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 71
68#define MAX_LBL_SIZE 63 72#define MAX_LBL_SIZE 63
69#define MAX_PKT_SIZE 512 73#define MAX_PKT_SIZE 512
70 74
75#define RR_TYPE_A 1
76#define RR_TYPE_NULL 10
71#define RR_TYPE_TXT 16 77#define RR_TYPE_TXT 16
72#define RR_TYPE_ANY 255 78#define RR_TYPE_ANY 255
79
73#define RR_CLASS_IN 1 80#define RR_CLASS_IN 1
74 81
75// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 82#define CMD_IP_1 207
76struct dns64 83#define CMD_IP_2 46
77{ 84#define CMD_IP_3 236
78 static const char encode_chars[64 + 1]; 85#define CMD_IP_RST 29
79 static s8 decode_chars[256]; 86#define CMD_IP_SYN 113
87#define CMD_IP_REJ 32
80 88
81 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 89// works for cmaps up to 255 (not 256!)
82 static int decode_len (int bytes) { return (bytes * 6) / 8; } 90struct charmap
91{
92 enum { INVALID = (u8)255 };
93
94 char encode [256]; // index => char
95 u8 decode [256]; // char => index
96 unsigned int size;
97
98 charmap (const char *cmap);
99};
100
101charmap::charmap (const char *cmap)
102{
103 char *enc = encode;
104 u8 *dec = decode;
105
106 memset (enc, (char) 0, 256);
107 memset (dec, (char)INVALID, 256);
108
109 for (size = 0; cmap [size]; size++)
110 {
111 enc [size] = cmap [size];
112 dec [(u8)enc [size]] = size;
113 }
114
115 assert (size < 256);
116}
117
118#define MAX_DEC_LEN 500
119#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
120#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
121
122// ugly. minimum base is 16(!)
123struct basecoder
124{
125 charmap cmap;
126 unsigned int enc_len [MAX_DEC_LEN];
127 unsigned int dec_len [MAX_ENC_LEN];
128
129 unsigned int encode_len (unsigned int len);
130 unsigned int decode_len (unsigned int len);
131
83 static int encode (char *dst, u8 *src, int len); 132 unsigned int encode (char *dst, u8 *src, unsigned int len);
84 static int decode (u8 *dst, char *src, int len); 133 unsigned int decode (u8 *dst, char *src, unsigned int len);
85 134
86 dns64 (); 135 basecoder (const char *cmap);
87} dns64; 136};
88 137
89const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-"; 138basecoder::basecoder (const char *cmap)
90s8 dns64::decode_chars[256]; 139: cmap (cmap)
91
92dns64::dns64 ()
93{ 140{
94 for (int i = 0; i < 64; i++) 141 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95 decode_chars [encode_chars [i]] = i + 1; 142 {
96} 143 u8 src [MAX_DEC_LEN];
144 u8 dst [MAX_ENC_LEN];
97 145
98int dns64::encode (char *dst, u8 *src, int len) 146 memset (src, 255, len);
147
148 mp_limb_t m [MAX_LIMBS];
149 mp_size_t n;
150
151 n = mpn_set_str (m, src, len, 256);
152 n = mpn_get_str (dst, this->cmap.size, m, n);
153
154 for (int i = 0; !dst [i]; ++i)
155 n--;
156
157 enc_len [len] = n;
158 dec_len [n] = len;
159 }
160}
161
162unsigned int basecoder::encode_len (unsigned int len)
99{ 163{
100 // slow, but easy to debug 164 return enc_len [len];
101 char *beg = dst; 165}
102 unsigned int accum, bits = 0; 166
167unsigned int basecoder::decode_len (unsigned int len)
168{
169 while (len && !dec_len [len])
170 --len;
171
172 return dec_len [len];
173}
174
175unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
176{
177 if (!len || len > MAX_DEC_LEN)
178 return 0;
179
180 int elen = encode_len (len);
181
182 mp_limb_t m [MAX_LIMBS];
183 mp_size_t n;
184
185 u8 dst_ [MAX_ENC_LEN];
186
187 n = mpn_set_str (m, src, len, 256);
188 n = mpn_get_str (dst_, cmap.size, m, n);
189
190 int plen = elen; // for padding
191
192 while (n < plen)
193 {
194 *dst++ = cmap.encode [0];
195 plen--;
196 }
197
198 for (unsigned int i = n - plen; i < n; ++i)
199 *dst++ = cmap.encode [dst_ [i]];
200
201 return elen;
202}
203
204unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
205{
206 if (!len || len > MAX_ENC_LEN)
207 return 0;
208
209 u8 src_ [MAX_ENC_LEN];
210 unsigned int elen = 0;
103 211
104 while (len--) 212 while (len--)
105 { 213 {
106 accum <<= 8; 214 u8 val = cmap.decode [(u8)*src++];
107 accum |= *src++;
108 bits += 8;
109 215
110 while (bits >= 6) 216 if (val != charmap::INVALID)
111 { 217 src_ [elen++] = val;
112 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 218 }
113 bits -= 6; 219
114 } 220 int dlen = decode_len (elen);
221
222 mp_limb_t m [MAX_LIMBS];
223 mp_size_t n;
224
225 u8 dst_ [MAX_DEC_LEN];
226
227 n = mpn_set_str (m, src_, elen, cmap.size);
228 n = mpn_get_str (dst_, 256, m, n);
229
230 if (n < dlen)
115 } 231 {
232 memset (dst, 0, dlen - n);
233 memcpy (dst + dlen - n, dst_, n);
234 }
235 else
236 memcpy (dst, dst_ + n - dlen, dlen);
116 237
117 if (bits) 238 return dlen;
118 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120 return dst - beg;
121} 239}
122 240
123int dns64::decode (u8 *dst, char *src, int len) 241#if 0
124{ 242struct test { test (); } test;
125 // slow, but easy to debug
126 u8 *beg = dst;
127 unsigned int accum, bits = 0;
128 243
129 while (len--) 244test::test ()
245{
246 basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
247
248 u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
249 static char enc[200];
250 static u8 dec[200];
251
252 for (int i = 1; i < 20; i++)
130 { 253 {
131 s8 chr = decode_chars [(u8)*src++]; 254 int elen = cdc.encode (enc, in, i);
255 int dlen = cdc.decode (dec, enc, elen);
132 256
133 if (!chr) 257 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 } 258 }
259 abort ();
260}
261#endif
146 262
147 return dst - beg; 263//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
264//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
265static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
266//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
267static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
268
269/////////////////////////////////////////////////////////////////////////////
270
271#define HDRSIZE 6
272
273inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
274{
275 seqno &= SEQNO_MASK;
276
277 u8 hdr[3] = {
278 clientid,
279 (seqno >> 8) | (retry << 6),
280 seqno,
281 };
282
283 assert (clientid < 256);
284
285 cdc26.encode (data, hdr, 3);
286}
287
288inline void decode_header (char *data, int &clientid, int &seqno)
289{
290 u8 hdr[3];
291
292 cdc26.decode (hdr, data, HDRSIZE);
293
294 clientid = hdr[0];
295 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
148} 296}
149 297
150///////////////////////////////////////////////////////////////////////////// 298/////////////////////////////////////////////////////////////////////////////
151 299
152struct byte_stream 300struct byte_stream
159 ~byte_stream (); 307 ~byte_stream ();
160 308
161 bool empty () { return !fill; } 309 bool empty () { return !fill; }
162 int size () { return fill; } 310 int size () { return fill; }
163 311
312 bool put (u8 *data, unsigned int datalen);
164 bool put (vpn_packet *pkt); 313 bool put (vpn_packet *pkt);
165 vpn_packet *get (); 314 vpn_packet *get ();
166 315
167 u8 *begin () { return data; } 316 u8 *begin () { return data; }
168 void remove (int count); 317 void remove (int count);
180} 329}
181 330
182void byte_stream::remove (int count) 331void byte_stream::remove (int count)
183{ 332{
184 if (count > fill) 333 if (count > fill)
185 abort (); 334 assert (count <= fill);
186 335
187 memmove (data, data + count, fill -= count); 336 memmove (data, data + count, fill -= count);
337}
338
339bool byte_stream::put (u8 *data, unsigned int datalen)
340{
341 if (maxsize - fill < datalen)
342 return false;
343
344 memcpy (this->data + fill, data, datalen); fill += datalen;
345
346 return true;
188} 347}
189 348
190bool byte_stream::put (vpn_packet *pkt) 349bool byte_stream::put (vpn_packet *pkt)
191{ 350{
192 if (maxsize - fill < pkt->len + 2) 351 if (maxsize - fill < pkt->len + 2)
193 return false; 352 return false;
194 353
195 data [fill++] = pkt->len >> 8; 354 data [fill++] = pkt->len >> 8;
196 data [fill++] = pkt->len; 355 data [fill++] = pkt->len;
197 356
198 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 357 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199 358
200 return true; 359 return true;
201} 360}
202 361
203vpn_packet *byte_stream::get () 362vpn_packet *byte_stream::get ()
204{ 363{
364 unsigned int len;
365
366 for (;;)
367 {
205 int len = (data [0] << 8) | data [1]; 368 len = (data [0] << 8) | data [1];
206 369
370 if (len <= MAXSIZE || fill < 2)
371 break;
372
373 // TODO: handle this better than skipping, e.g. by reset
374 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
375 remove (1);
376 }
377
207 if (fill < len + 2) 378 if (fill < len + 2)
208 return 0; 379 return 0;
209 380
210 vpn_packet *pkt = new vpn_packet; 381 vpn_packet *pkt = new vpn_packet;
382
383 pkt->len = len;
211 memcpy (&((*pkt)[0]), data + 2, len); 384 memcpy (pkt->at (0), data + 2, len);
212 remove (len + 2); 385 remove (len + 2);
213 386
214 return pkt; 387 return pkt;
215} 388}
216 389
217///////////////////////////////////////////////////////////////////////////// 390/////////////////////////////////////////////////////////////////////////////
218 391
219#define FLAG_QUERY ( 0 << 15) 392#define FLAG_QUERY ( 0 << 15)
220#define FLAG_RESPONSE ( 1 << 15) 393#define FLAG_RESPONSE ( 1 << 15)
221#define FLAG_OP_MASK (15 << 14) 394#define FLAG_OP_MASK (15 << 11)
222#define FLAG_OP_QUERY ( 0 << 11) 395#define FLAG_OP_QUERY ( 0 << 11)
223#define FLAG_AA ( 1 << 10) 396#define FLAG_AA ( 1 << 10)
224#define FLAG_TC ( 1 << 9) 397#define FLAG_TC ( 1 << 9)
225#define FLAG_RD ( 1 << 8) 398#define FLAG_RD ( 1 << 8)
226#define FLAG_RA ( 1 << 7) 399#define FLAG_RA ( 1 << 7)
400#define FLAG_AUTH ( 1 << 5)
227#define FLAG_RCODE_MASK (15 << 0) 401#define FLAG_RCODE_MASK (15 << 0)
228#define FLAG_RCODE_OK ( 0 << 0) 402#define FLAG_RCODE_OK ( 0 << 0)
229#define FLAG_RCODE_FORMERR ( 1 << 0) 403#define FLAG_RCODE_FORMERR ( 1 << 0)
230#define FLAG_RCODE_SERVFAIL ( 2 << 0) 404#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231#define FLAG_RCODE_NXDOMAIN ( 3 << 0) 405#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232#define FLAG_RCODE_REFUSED ( 5 << 0) 406#define FLAG_RCODE_REFUSED ( 5 << 0)
233 407
234#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 408#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) 409#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
410
411struct dns_cfg
412{
413 static int next_uid;
414
415 u8 id1, id2, id3, id4;
416
417 u8 version;
418 u8 flags;
419 u8 rrtype;
420 u8 def_ttl;
421
422 u16 client;
423 u16 uid; // to make request unique
424
425 u16 max_size;
426 u8 seq_cdc;
427 u8 req_cdc;
428
429 u8 rep_cdc;
430 u8 delay; // time in 0.01s units that the server may delay replying packets
431 u8 r3, r4;
432
433 u8 r5, r6, r7, r8;
434
435 void reset (int clientid);
436 bool valid ();
437};
438
439int dns_cfg::next_uid;
440
441void dns_cfg::reset (int clientid)
442{
443 id1 = 'G';
444 id2 = 'V';
445 id3 = 'P';
446 id4 = 'E';
447
448 version = 1;
449
450 rrtype = RR_TYPE_TXT;
451 flags = 0;
452 def_ttl = 0;
453 seq_cdc = 26;
454 req_cdc = 62;
455 rep_cdc = 0;
456 max_size = htons (MAX_PKT_SIZE);
457 client = htons (clientid);
458 uid = next_uid++;
459 delay = 0;
460
461 r3 = r4 = 0;
462 r4 = r5 = r6 = r7 = 0;
463}
464
465bool dns_cfg::valid ()
466{
467 // although the protocol itself allows for some configurability,
468 // only the following encoding/decoding settings are implemented.
469 return id1 == 'G'
470 && id2 == 'V'
471 && id3 == 'P'
472 && id4 == 'E'
473 && seq_cdc == 26
474 && req_cdc == 62
475 && rep_cdc == 0
476 && version == 1;
477}
236 478
237struct dns_packet : net_packet 479struct dns_packet : net_packet
238{ 480{
239 u16 id; 481 u16 id;
240 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 482 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
241 u16 qdcount, ancount, nscount, arcount; 483 u16 qdcount, ancount, nscount, arcount;
242 484
243 u8 data[MAXSIZE - 6 * 2]; 485 u8 data [MAXSIZE - 6 * 2];
244 486
245 int decode_label (char *data, int size, int &offs); 487 int decode_label (char *data, int size, int &offs);
246}; 488};
247 489
248int dns_packet::decode_label (char *data, int size, int &offs) 490int dns_packet::decode_label (char *data, int size, int &offs)
279 return data - orig; 521 return data - orig;
280} 522}
281 523
282///////////////////////////////////////////////////////////////////////////// 524/////////////////////////////////////////////////////////////////////////////
283 525
526static u16 dns_id = 0; // TODO: should be per-vpn
527
528static u16 next_id ()
529{
530 if (!dns_id)
531 dns_id = time (0);
532
533 // the simplest lsfr with periodicity 65535 i could find
534 dns_id = (dns_id << 1)
535 | (((dns_id >> 1)
536 ^ (dns_id >> 2)
537 ^ (dns_id >> 4)
538 ^ (dns_id >> 15)) & 1);
539
540 return dns_id;
541}
542
284struct dns_req 543struct dns_rcv;
544struct dns_snd;
545
546struct dns_connection
547{
548 connection *c;
549 struct vpn *vpn;
550
551 dns_cfg cfg;
552
553 bool established;
554
555 tstamp last_received;
556 tstamp last_sent;
557 double min_latency;
558 double poll_interval, send_interval;
559
560 vector<dns_rcv *> rcvpq;
561
562 byte_stream rcvdq; int rcvseq; int repseq;
563 byte_stream snddq; int sndseq;
564
565 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
566 void receive_rep (dns_rcv *r);
567
568 dns_connection (connection *c);
569 ~dns_connection ();
570};
571
572struct dns_snd
285{ 573{
286 dns_packet *pkt; 574 dns_packet *pkt;
287 tstamp next; 575 tstamp timeout, sent;
288 int retry; 576 int retry;
289 connection *conn; 577 struct dns_connection *dns;
578 int seqno;
579 bool stdhdr;
290 580
291 dns_req (connection *c, int seqno, byte_stream *stream); 581 void gen_stream_req (int seqno, byte_stream &stream);
582 void gen_syn_req ();
583
584 dns_snd (dns_connection *dns);
585 ~dns_snd ();
292}; 586};
293 587
294struct dns_rep 588dns_snd::dns_snd (dns_connection *dns)
589: dns (dns)
295{ 590{
296}; 591 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; 592 retry = 0;
593 seqno = 0;
594 sent = ev_now ();
595 stdhdr = false;
305 596
306 pkt = new dns_packet; 597 pkt = new dns_packet;
307 598
308 pkt->id = dns_id++; 599 pkt->id = next_id ();
309 pkt->flags = DEFAULT_CLIENT_FLAGS; 600}
310 pkt->qdcount = htons (1);
311 pkt->ancount = 0;
312 pkt->nscount = 0;
313 pkt->arcount = 0;
314 601
315 int offs = 6*2; 602dns_snd::~dns_snd ()
316 int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length 603{
604 delete pkt;
605}
317 606
318 u8 lbl[64]; //D 607static void append_domain (dns_packet &pkt, int &offs, const char *domain)
319 char enc[65]; 608{
320 int lbllen = 3;
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 609 // add tunnel domain
356 for (;;) 610 for (;;)
357 { 611 {
358 const char *end = strchr (suffix, '.'); 612 const char *end = strchr (domain, '.');
359 613
360 if (!end) 614 if (!end)
361 end = suffix + strlen (suffix); 615 end = domain + strlen (domain);
362 616
363 int len = end - suffix; 617 int len = end - domain;
364 618
365 (*pkt)[offs++] = len; 619 pkt [offs++] = len;
366 memcpy (&((*pkt)[offs]), suffix, len); 620 memcpy (pkt.at (offs), domain, len);
367 offs += len; 621 offs += len;
368 622
369 if (!*end) 623 if (!*end)
370 break; 624 break;
371 625
372 suffix = end + 1; 626 domain = end + 1;
627 }
628}
629
630void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
631{
632 stdhdr = true;
633 this->seqno = seqno;
634
635 timeout = ev_now () + INITIAL_TIMEOUT;
636
637 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
638 pkt->qdcount = htons (1);
639
640 int offs = 6*2;
641 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
642 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
643 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
644
645 char enc[256], *encp = enc;
646 encode_header (enc, THISNODE->id, seqno);
647
648 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
649
650 if (datalen > stream.size ())
651 datalen = stream.size ();
652
653 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
654 stream.remove (datalen);
655
656 while (enclen)
373 } 657 {
658 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
659
660 (*pkt)[offs++] = lbllen;
661 memcpy (pkt->at (offs), encp, lbllen);
662
663 offs += lbllen;
664 encp += lbllen;
665
666 enclen -= lbllen;
667 }
668
669 append_domain (*pkt, offs, dns->c->conf->domain);
374 670
375 (*pkt)[offs++] = 0; 671 (*pkt)[offs++] = 0;
376 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 672 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 673 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378 674
379 pkt->len = offs; 675 pkt->len = offs;
676}
380 677
381 c->vpn->dns_sndpq.push_back (this); 678void dns_snd::gen_syn_req ()
679{
680 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
681
682 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
683 pkt->qdcount = htons (1);
684
685 int offs = 6 * 2;
686
687 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
688
689 assert (elen <= MAX_LBL_SIZE);
690
691 (*pkt)[offs] = elen;
692 offs += elen + 1;
693 append_domain (*pkt, offs, dns->c->conf->domain);
694
695 (*pkt)[offs++] = 0;
696 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
697 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
698
699 pkt->len = offs;
700}
701
702struct dns_rcv
703{
704 int seqno;
705 dns_packet *pkt; // reply packet
706 u8 data [MAXSIZE]; // actually part of the reply packet...
707 int datalen;
708
709 dns_rcv (int seqno, u8 *data, int datalen);
710 ~dns_rcv ();
711};
712
713dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
714: seqno (seqno), pkt (new dns_packet), datalen (datalen)
715{
716 memcpy (this->data, data, datalen);
717}
718
719dns_rcv::~dns_rcv ()
720{
721 delete pkt;
382} 722}
383 723
384///////////////////////////////////////////////////////////////////////////// 724/////////////////////////////////////////////////////////////////////////////
385 725
386struct dns_cfg 726dns_connection::dns_connection (connection *c)
727: c (c)
728, rcvdq (MAX_BACKLOG * 2)
729, snddq (MAX_BACKLOG)
387{ 730{
388 u8 id1, id2, id3; 731 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};
394 732
395dns_packet * 733 vpn = c->vpn;
734
735 established = false;
736
737 rcvseq = repseq = sndseq = 0;
738
739 last_sent = last_received = 0;
740 poll_interval = 0.5; // starting here
741 send_interval = 0.5; // starting rate
742 min_latency = INITIAL_TIMEOUT;
743}
744
745dns_connection::~dns_connection ()
746{
747 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
748 i != rcvpq.end ();
749 ++i)
750 delete *i;
751}
752
753void dns_connection::receive_rep (dns_rcv *r)
754{
755 if (r->datalen)
756 {
757 last_received = ev_now ();
758 tw ();
759
760 poll_interval = send_interval;
761 }
762 else
763 {
764 poll_interval *= 1.5;
765
766 if (poll_interval > MAX_POLL_INTERVAL)
767 poll_interval = MAX_POLL_INTERVAL;
768 }
769
770 rcvpq.push_back (r);
771
772 redo:
773
774 // find next packet
775 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
776 if (SEQNO_EQ (rcvseq, (*i)->seqno))
777 {
778 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
779 // enter the packet into our input stream
780 r = *i;
781
782 // remove the oldest packet, look forward, as it's oldest first
783 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
784 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
785 {
786 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
787 delete *j;
788 rcvpq.erase (j);
789 break;
790 }
791
792 rcvseq = (rcvseq + 1) & SEQNO_MASK;
793
794 if (!rcvdq.put (r->data, r->datalen))
795 {
796 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
797 abort (); // MUST never overflow, can be caused by data corruption, TODO
798 }
799
800 while (vpn_packet *pkt = rcvdq.get ())
801 {
802 sockinfo si;
803 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
804
805 vpn->recv_vpn_packet (pkt, si);
806
807 delete pkt;
808 }
809
810 // check for further packets
811 goto redo;
812 }
813}
814
815void
396vpn::dnsv4_server (dns_packet *pkt) 816vpn::dnsv4_server (dns_packet &pkt)
397{ 817{
398 u16 flags = ntohs (pkt->flags); 818 u16 flags = ntohs (pkt.flags);
399 819
400 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401 int offs = 6 * 2; // skip header 820 int offs = 6 * 2; // skip header
402 821
403 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 822 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404 823
405 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 824 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406 && pkt->qdcount == htons (1)) 825 && pkt.qdcount == htons (1))
407 { 826 {
408 char qname[MAXSIZE]; 827 char qname [MAXSIZE];
409 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 828 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410 829
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++]; 830 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 831 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416 832
417 pkt->qdcount = htons (1); 833 pkt.qdcount = htons (1);
418 pkt->ancount = 0; 834 pkt.ancount = 0;
419 pkt->nscount = 0; // should be self, as other nameservers reply like this 835 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 836 pkt.arcount = 0; // a record for self, as other nameservers reply like this
421 837
422 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 838 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423 839
424 int dlen = strlen (THISNODE->domain); 840 int dlen = strlen (THISNODE->domain);
425 841
426 if (qclass == RR_CLASS_IN 842 if (qclass == RR_CLASS_IN
427 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428 && qlen > dlen + 1 843 && qlen > dlen + 1
429 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 844 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430 { 845 {
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 846 // now generate reply
444 rep->ancount = htons (1); // one answer RR 847 pkt.ancount = htons (1); // one answer RR
445 rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 848 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446 849
447 (*rep) [offs++] = 0xc0; 850 if ((qtype == RR_TYPE_ANY
448 (*rep) [offs++] = 6 * 2; // same as in query section 851 || qtype == RR_TYPE_TXT
449 852 || qtype == RR_TYPE_NULL)
450 (*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT; 853 && 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 { 854 {
470 int sndlen = --dlen; 855 // correct class, domain: parse
856 int client, seqno;
857 decode_header (qname, client, seqno);
471 858
472 if (sndlen + txtlen > 255) 859 u8 data[MAXSIZE];
473 sndlen = 255 - txtlen; 860 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
474 861
475 sndlen = 0; 862 if (0 < client && client <= conns.size ())
863 {
864 connection *c = conns [client - 1];
865 dns_connection *dns = c->dns;
866 dns_rcv *rcv;
476 867
477 (*rep)[offs++] = sndlen + txtlen; 868 if (dns)
478 memcpy (&((*rep)[offs]), txt, txtlen); 869 {
870 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
871 if (SEQNO_EQ ((*i)->seqno, seqno))
872 {
873 // already seen that request: simply reply with the cached reply
874 dns_rcv *r = *i;
875
876 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
877
878 // refresh header & id, as the retry count could have changed
879 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
880 r->pkt->id = pkt.id;
881
882 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
883
884 goto duplicate_request;
885 }
886
887 // new packet, queue
888 rcv = new dns_rcv (seqno, data, datalen);
889 dns->receive_rep (rcv);
890 }
891
892 {
893 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
894
895 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
896 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
897 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
898 pkt [offs++] = 0; pkt [offs++] = 0;
899 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
900
901 int rdlen_offs = offs += 2;
902
903 if (dns)
904 {
905 int dlen = ntohs (dns->cfg.max_size) - offs;
906
907 // bind doesn't compress well, so reduce further by one label length
908 dlen -= qlen;
909
910 // only put data into in-order sequence packets, if
911 // we receive out-of-order packets we generate empty
912 // replies
913 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
914 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
915 {
916 dns->repseq = seqno;
917
918 while (dlen > 1 && !dns->snddq.empty ())
919 {
920 int txtlen = dlen <= 255 ? dlen - 1 : 255;
921
922 if (txtlen > dns->snddq.size ())
923 txtlen = dns->snddq.size ();
924
925 pkt[offs++] = txtlen;
926 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
479 offs += txtlen; 927 offs += txtlen;
928 dns->snddq.remove (txtlen);
480 929
481 //if (sndlen + txtlen > dns_snddq. 930 dlen -= txtlen + 1;
931 }
932 }
933
934 // avoid completely empty TXT rdata
935 if (offs == rdlen_offs)
936 pkt[offs++] = 0;
937
938 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
939 }
940 else
941 {
942 // send RST
943 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
944 pkt [offs++] = CMD_IP_RST;
945 }
946
947 int rdlen = offs - rdlen_offs;
948
949 pkt [rdlen_offs - 2] = rdlen >> 8;
950 pkt [rdlen_offs - 1] = rdlen;
951
952 if (dns)
953 {
954 // now update dns_rcv copy
955 rcv->pkt->len = offs;
956 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
957 }
958 }
959
960 duplicate_request: ;
961 }
962 else
963 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
482 } 964 }
965 else if (qtype == RR_TYPE_A
966 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
967 {
968 dns_cfg cfg;
969 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
970 int client = ntohs (cfg.client);
483 971
484 int rdlen = offs - rdlen_offs; 972 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485 973
486 (*rep) [rdlen_offs - 2] = rdlen >> 8; 974 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487 (*rep) [rdlen_offs - 1] = rdlen; 975 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488#endif 976 pkt [offs++] = 0; pkt [offs++] = 0;
977 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
978 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
979
980 slog (L_INFO, _("DNS: client %d connects"), client);
981
982 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
983 pkt [offs++] = CMD_IP_REJ;
984
985 if (0 < client && client <= conns.size ())
986 {
987 connection *c = conns [client - 1];
988
989 if (cfg.valid ())
990 {
991 pkt [offs - 1] = CMD_IP_SYN;
992
993 delete c->dns;
994 c->dns = new dns_connection (c);
995 c->dns->cfg = cfg;
996 }
997 }
998 }
489 } 999 }
490 }
491 1000
492 pkt->len = offs; 1001 pkt.len = offs;
493 return pkt; 1002 }
494} 1003}
495 1004
496void 1005void
497vpn::dnsv4_client (dns_packet *pkt) 1006vpn::dnsv4_client (dns_packet &pkt)
498{ 1007{
499 u16 flags = ntohs (pkt->flags); 1008 u16 flags = ntohs (pkt.flags);
500 int offs = 6 * 2; // skip header 1009 int offs = 6 * 2; // skip header
501 1010
502 pkt->qdcount = ntohs (pkt->qdcount); 1011 pkt.qdcount = ntohs (pkt.qdcount);
503 pkt->ancount = ntohs (pkt->ancount); 1012 pkt.ancount = ntohs (pkt.ancount);
504 1013
1014 // go through our request list and find the corresponding request
505 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1015 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506 i != dns_sndpq.end (); 1016 i != dns_sndpq.end ();
507 ++i) 1017 ++i)
508 if ((*i)->pkt->id == pkt->id) 1018 if ((*i)->pkt->id == pkt.id)
509 { 1019 {
1020 dns_connection *dns = (*i)->dns;
510 connection *c = (*i)->conn; 1021 connection *c = dns->c;
511 printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D 1022 int seqno = (*i)->seqno;
1023 u8 data[MAXSIZE], *datap = data;
1024 //printf ("rcv pkt %x\n", seqno);//D
1025
1026 if ((*i)->retry)
1027 {
1028 dns->send_interval *= 1.01;
1029 if (dns->send_interval > MAX_SEND_INTERVAL)
1030 dns->send_interval = MAX_SEND_INTERVAL;
1031 }
1032 else
1033 {
1034#if 0
1035 dns->send_interval *= 0.999;
1036#endif
1037 // the latency surely puts an upper bound on
1038 // the minimum send interval
1039 double latency = ev_now () - (*i)->sent;
1040
1041 if (latency < dns->min_latency)
1042 dns->min_latency = latency;
1043
1044 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1045 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1046
1047 if (dns->send_interval < conf.dns_send_interval)
1048 dns->send_interval = conf.dns_send_interval;
1049 }
1050
512 delete *i; 1051 delete *i;
513 dns_sndpq.erase (i); 1052 dns_sndpq.erase (i);
514 1053
515 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1054 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516 { 1055 {
517 char qname[MAXSIZE]; 1056 char qname[MAXSIZE];
518 1057
519 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1058 while (pkt.qdcount-- && offs < MAXSIZE - 4)
520 { 1059 {
521 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1060 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522 offs += 4; // skip qtype, qclass 1061 offs += 4; // skip qtype, qclass
523 } 1062 }
524 1063
525 while (pkt->ancount-- && offs < MAXSIZE - 10) 1064 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526 { 1065 {
527 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1066 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528 1067
529 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1068 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1069 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531 u32 ttl = (*pkt) [offs++] << 24; 1070 u32 ttl = pkt [offs++] << 24;
532 ttl |= (*pkt) [offs++] << 16; 1071 ttl |= pkt [offs++] << 16;
533 ttl |= (*pkt) [offs++] << 8; 1072 ttl |= pkt [offs++] << 8;
534 ttl |= (*pkt) [offs++]; 1073 ttl |= pkt [offs++];
535
536 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1074 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537 1075
538 printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen); 1076 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
539
540 offs += rdlen;
541
542 if (MAXSIZE - offs < rdlen)
543 { 1077 {
1078 if (rdlen <= MAXSIZE - offs)
1079 {
544 // decode bytes, finally 1080 // decode bytes, finally
1081
1082 while (rdlen)
1083 {
1084 int txtlen = pkt [offs++];
1085
1086 assert (txtlen + offs < MAXSIZE - 1);
1087
1088 memcpy (datap, pkt.at (offs), txtlen);
1089 datap += txtlen; offs += txtlen;
1090
1091 rdlen -= txtlen + 1;
1092 }
1093 }
1094 }
1095 else if (qtype == RR_TYPE_A)
1096 {
1097 u8 ip [4];
1098
1099 ip [0] = pkt [offs++];
1100 ip [1] = pkt [offs++];
1101 ip [2] = pkt [offs++];
1102 ip [3] = pkt [offs++];
1103
1104 if (ip [0] == CMD_IP_1
1105 && ip [1] == CMD_IP_2
1106 && ip [2] == CMD_IP_3)
1107 {
1108 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1109
1110 if (ip [3] == CMD_IP_RST)
1111 {
1112 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1113
1114 delete dns; c->dns = 0;
1115
1116 return;
1117 }
1118 else if (ip [3] == CMD_IP_SYN)
1119 {
1120 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1121 dns->established = true;
1122 }
1123 else if (ip [3] == CMD_IP_REJ)
1124 {
1125 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1126 abort ();
1127 }
1128 else
1129 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1130 }
1131 else
1132 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1133 ip [0], ip [1], ip [2], ip [3]);
1134
1135 return;
1136 }
1137
1138 int client, rseqno;
1139 decode_header (qname, client, rseqno);
1140
1141 if (client != THISNODE->id)
1142 {
1143 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1144 datap = 0;
1145 }
1146 else if (rseqno != seqno)
1147 {
1148 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1149 datap = 0;
545 } 1150 }
546 } 1151 }
547 } 1152 }
548 1153
1154 // todo: pkt now used
1155 if (datap)
1156 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
1157
549 break; 1158 break;
550 } 1159 }
551} 1160}
552 1161
553void 1162void
554vpn::dnsv4_ev (io_watcher &w, short revents) 1163vpn::dnsv4_ev (ev::io &w, int revents)
555{ 1164{
556 if (revents & EVENT_READ) 1165 if (revents & EV_READ)
557 { 1166 {
558 dns_packet *pkt = new dns_packet; 1167 dns_packet *pkt = new dns_packet;
559 struct sockaddr_in sa; 1168 struct sockaddr_in sa;
560 socklen_t sa_len = sizeof (sa); 1169 socklen_t sa_len = sizeof (sa);
561 1170
562 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1171 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563 1172
564 if (pkt->len > 0) 1173 if (pkt->len > 0)
565 if (THISNODE->dns_port)
566 { 1174 {
567 pkt = dnsv4_server (pkt); 1175 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); 1176 dnsv4_client (*pkt);
1177 else
1178 {
1179 dnsv4_server (*pkt);
1180 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1181 }
1182
1183 delete pkt;
1184 }
572 } 1185 }
573} 1186}
574 1187
575bool 1188bool
576connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1189vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577{ 1190{
578 // never initialized 1191 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 1192
584 dns_rcvseq = dns_sndseq = 0; 1193 assert (0 < client && client <= conns.size ());
585 1194
586 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1195 connection *c = conns [client - 1];
587 } 1196
1197 if (!c->dns)
1198 c->dns = new dns_connection (c);
588 1199
589 if (!dns_snddq->put (pkt)) 1200 if (c->dns->snddq.put (pkt))
590 return false; 1201 c->dns->tw ();
591 1202
592 // start timer if neccessary 1203 // always return true even if the buffer overflows
593 if (!dnsv4_tw.active)
594 dnsv4_cb (dnsv4_tw);
595
596 return true; 1204 return true;
597} 1205}
598 1206
599void 1207void
600connection::dnsv4_cb (time_watcher &w) 1208connection::dnsv4_reset_connection ()
601{ 1209{
1210 //delete dns; dns = 0; //TODO
1211}
1212
1213#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1214
1215void
1216dns_connection::time_cb (ev::timer &w, int revents)
1217{
1218 // servers have to be polled
1219 if (THISNODE->dns_port)
1220 return;
1221
602 // check for timeouts and (re)transmit 1222 // check for timeouts and (re)transmit
603 tstamp next = NOW + 60; 1223 tstamp next = ev::now () + poll_interval;
604 dns_req *send = 0; 1224 dns_snd *send = 0;
605 1225
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 (); 1226 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609 i != vpn->dns_sndpq.end (); 1227 i != vpn->dns_sndpq.end ();
610 ++i) 1228 ++i)
611 { 1229 {
612 dns_req *r = *i; 1230 dns_snd *r = *i;
613 1231
614 if (r->next <= NOW) 1232 if (r->timeout <= ev_now ())
615 { 1233 {
616 if (!send) 1234 if (!send)
617 { 1235 {
618 send = r; 1236 send = r;
619 1237
620 slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621 r->retry++; 1238 r->retry++;
622 r->next = NOW + r->retry; 1239 r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
1240 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1241
1242 // the following code changes the query section a bit, forcing
1243 // the forwarder to generate a new request
1244 if (r->stdhdr)
1245 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
623 } 1246 }
624 } 1247 }
625 1248 else
626 if (r->next < next) 1249 NEXT (r->timeout);
627 next = r->next;
628 } 1250 }
629 1251
630 if (!send 1252 if (!send)
631 && vpn->dns_sndpq.size () < MAX_OUTSTANDING) 1253 {
632 send = new dns_req (this, dns_sndseq++, dns_snddq); 1254 // generate a new packet, if wise
633 1255
634 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE); 1256 if (!established)
1257 {
1258 if (vpn->dns_sndpq.empty ())
1259 {
1260 send = new dns_snd (this);
1261
1262 cfg.reset (THISNODE->id);
1263 send->gen_syn_req ();
1264 }
1265 }
1266 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1267 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1268 {
1269 if (last_sent + send_interval <= ev_now ())
1270 {
1271 //printf ("sending data request etc.\n"); //D
1272 if (!snddq.empty () || last_received + 1. > ev_now ())
1273 {
1274 poll_interval = send_interval;
1275 NEXT (ev_now () + send_interval);
1276 }
1277
1278 send = new dns_snd (this);
1279 send->gen_stream_req (sndseq, snddq);
1280 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1281 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1282
1283 sndseq = (sndseq + 1) & SEQNO_MASK;
1284 }
1285 else
1286 NEXT (last_sent + send_interval);
1287 }
1288
1289 if (send)
1290 vpn->dns_sndpq.push_back (send);
1291 }
635 1292
636 if (send) 1293 if (send)
637 { 1294 {
638 dns_packet *pkt = send->pkt; 1295 last_sent = ev_now ();
639 1296 sendto (vpn->dnsv4_fd,
640 next = min_next; 1297 send->pkt->at (0), send->pkt->len, 0,
641 1298 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 } 1299 }
644 else if (next < min_next)
645 next = min_next;
646 1300
647 w.start (next); 1301 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1302 poll_interval, send_interval, next - ev_now (),
1303 vpn->dns_sndpq.size (), snddq.size (),
1304 rcvpq.size ());
1305
1306 // TODO: no idea when this happens, but when next < ev_now (), we have a problem
1307 // doesn't seem to happen anymore
1308 if (next < ev_now () + 0.001)
1309 next = ev_now () + 0.1;
1310
1311 w.start (next - ev_now ());
648} 1312}
649 1313
650#endif 1314#endif
651 1315

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