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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.7 by pcg, Thu Mar 3 16:54:34 2005 UTC vs.
Revision 1.50 by root, Sun Mar 6 13:49:50 2011 UTC

1/* 1/*
2 vpn_dns.C -- handle the dns tunnel part of the protocol. 2 vpn_dns.C -- handle the dns tunnel part of the protocol.
3 Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> 3 Copyright (C) 2003-2008 Marc Lehmann <gvpe@schmorp.de>
4 4
5 This file is part of GVPE. 5 This file is part of GVPE.
6 6
7 GVPE is free software; you can redistribute it and/or modify 7 GVPE is free software; you can redistribute it and/or modify it
8 it under the terms of the GNU General Public License as published by 8 under the terms of the GNU General Public License as published by the
9 the Free Software Foundation; either version 2 of the License, or 9 Free Software Foundation; either version 3 of the License, or (at your
10 (at your option) any later version. 10 option) any later version.
11 11
12 This program is distributed in the hope that it will be useful, 12 This program is distributed in the hope that it will be useful, but
13 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
15 GNU General Public License for more details. 15 Public License for more details.
16 16
17 You should have received a copy of the GNU General Public License 17 You should have received a copy of the GNU General Public License along
18 along with gvpe; if not, write to the Free Software 18 with this program; if not, see <http://www.gnu.org/licenses/>.
19 Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19
20 Additional permission under GNU GPL version 3 section 7
21
22 If you modify this Program, or any covered work, by linking or
23 combining it with the OpenSSL project's OpenSSL library (or a modified
24 version of that library), containing parts covered by the terms of the
25 OpenSSL or SSLeay licenses, the licensors of this Program grant you
26 additional permission to convey the resulting work. Corresponding
27 Source for a non-source form of such a combination shall include the
28 source code for the parts of OpenSSL used as well as that of the
29 covered work.
20*/ 30*/
31
32// TODO: EDNS0 option to increase dns mtu?
33// TODO: re-write dns packet parsing/creation using a safe mem-buffer
34// to ensure no buffer overflows or similar problems.
21 35
22#include "config.h" 36#include "config.h"
23 37
24#if ENABLE_DNS 38#if ENABLE_DNS
25 39
26// dns processing is EXTREMELY ugly. For obvious(?) reasons. 40// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27// it's a hack, use only in emergency situations please. 41// it's a hack, use only in emergency situations please.
28 42
29#include <cstring> 43#include <cstring>
44#include <cassert>
30 45
31#include <sys/types.h> 46#include <sys/types.h>
32#include <sys/socket.h> 47#include <sys/socket.h>
33#include <sys/wait.h> 48#include <sys/wait.h>
34#include <sys/uio.h> 49#include <sys/uio.h>
… …
37#include <unistd.h> 52#include <unistd.h>
38#include <fcntl.h> 53#include <fcntl.h>
39 54
40#include <map> 55#include <map>
41 56
57#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
58#include <gmp.h>
59
42#include "netcompat.h" 60#include "netcompat.h"
43 61
44#include "vpn.h" 62#include "vpn.h"
45 63
46#define MIN_RETRY 1. 64#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
47#define MAX_RETRY 60. 65#define ACTIVITY_INTERVAL 5.
48 66
49#define MAX_OUTSTANDING 40 // max. outstanding requests 67#define INITIAL_TIMEOUT 0.1 // retry timeouts
68#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
69
70#define MAX_SEND_INTERVAL 2. // optimistic?
71
50#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 72#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
51#define MAX_RATE 1000 // requests/s
52#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE 73#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
53 74
54#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well 75#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
55// 240 leaves about 4 bytes of server reply data 76// 240 leaves about 4 bytes of server reply data
56// every two request byte sless give room for one reply byte 77// every request byte less give room for two reply bytes
57 78
58// seqno has 12 bits, but the lower bit is always left as zero
59// as bind caches ttl=0 records and we have to generate
60// sequence numbers that always differ case-insensitively
61#define SEQNO_MASK 0x07ff 79#define SEQNO_MASK 0x3fff
62 80#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
63/*
64
65protocol, in shorthand :)
66
67client -> server <req> ANY?
68server -> client <req> TXT <rep>
69
70<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
71<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
72
73if <client-id> is zero, the connection will be configured:
74
75<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
76
77*/
78 81
79#define MAX_LBL_SIZE 63 82#define MAX_LBL_SIZE 63
80#define MAX_PKT_SIZE 512 83#define MAX_PKT_SIZE 512
81 84
85#define RR_TYPE_A 1
86#define RR_TYPE_NULL 10
82#define RR_TYPE_TXT 16 87#define RR_TYPE_TXT 16
88#define RR_TYPE_AAAA 28
83#define RR_TYPE_ANY 255 89#define RR_TYPE_ANY 255
90
84#define RR_CLASS_IN 1 91#define RR_CLASS_IN 1
85 92
86// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 93#define CMD_IP_1 207
87struct dns64 94#define CMD_IP_2 46
88{ 95#define CMD_IP_3 236
89 static const char encode_chars[64 + 1]; 96#define CMD_IP_RST 29
90 static s8 decode_chars[256]; 97#define CMD_IP_SYN 113
98#define CMD_IP_REJ 32
91 99
92 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 100// works for cmaps up to 255 (not 256!)
93 static int decode_len (int bytes) { return (bytes * 6) / 8; } 101struct charmap
102{
103 enum { INVALID = (u8)255 };
104
105 char encode [256]; // index => char
106 u8 decode [256]; // char => index
107 unsigned int size;
108
109 charmap (const char *cmap);
110};
111
112charmap::charmap (const char *cmap)
113{
114 char *enc = encode;
115 u8 *dec = decode;
116
117 memset (enc, (char) 0, 256);
118 memset (dec, (char)INVALID, 256);
119
120 for (size = 0; cmap [size]; size++)
121 {
122 char c = cmap [size];
123
124 enc [size] = c;
125 dec [(u8)c] = size;
126
127 // allow lowercase/uppercase aliases if possible
128 if (c >= 'A' && c <= 'Z' && dec [c + ('a' - 'A')] == INVALID) dec [c + ('a' - 'A')] = size;
129 if (c >= 'a' && c <= 'z' && dec [c - ('a' - 'A')] == INVALID) dec [c - ('a' - 'A')] = size;
130 }
131
132 assert (size < 256);
133}
134
135#define MAX_DEC_LEN 500
136#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
137#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
138
139// ugly. minimum base is 16(!)
140struct basecoder
141{
142 charmap cmap;
143 unsigned int enc_len [MAX_DEC_LEN];
144 unsigned int dec_len [MAX_ENC_LEN];
145
146 unsigned int encode_len (unsigned int len);
147 unsigned int decode_len (unsigned int len);
148
94 static int encode (char *dst, u8 *src, int len); 149 unsigned int encode (char *dst, u8 *src, unsigned int len);
95 static int decode (u8 *dst, char *src, int len); 150 unsigned int decode (u8 *dst, char *src, unsigned int len);
96 151
97 dns64 (); 152 basecoder (const char *cmap);
98} dns64; 153};
99 154
100// the following sequence has been crafted to 155basecoder::basecoder (const char *cmap)
101// a) look somewhat random 156: cmap (cmap)
102// b) the even (and odd) indices never share the same character as upper/lowercase
103const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
104s8 dns64::decode_chars[256];
105
106dns64::dns64 ()
107{ 157{
108 for (int i = 0; i < 64; i++) 158 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
109 decode_chars [encode_chars [i]] = i + 1; 159 {
110} 160 u8 src [MAX_DEC_LEN];
161 u8 dst [MAX_ENC_LEN];
111 162
163 memset (src, 255, len);
164
165 mp_limb_t m [MAX_LIMBS];
166 mp_size_t n;
167
168 n = mpn_set_str (m, src, len, 256);
169 n = mpn_get_str (dst, this->cmap.size, m, n);
170
171 for (int i = 0; !dst [i]; ++i)
172 n--;
173
174 enc_len [len] = n;
175 dec_len [n] = len;
176 }
177}
178
179unsigned int
180basecoder::encode_len (unsigned int len)
181{
182 return enc_len [len];
183}
184
185unsigned int
186basecoder::decode_len (unsigned int len)
187{
188 while (len && !dec_len [len])
189 --len;
190
191 return dec_len [len];
192}
193
194unsigned int
112int dns64::encode (char *dst, u8 *src, int len) 195basecoder::encode (char *dst, u8 *src, unsigned int len)
113{ 196{
114 // slow, but easy to debug 197 if (!len || len > MAX_DEC_LEN)
115 char *beg = dst; 198 return 0;
116 unsigned int accum, bits = 0; 199
200 int elen = encode_len (len);
201
202 mp_limb_t m [MAX_LIMBS];
203 mp_size_t n;
204
205 u8 dst_ [MAX_ENC_LEN];
206
207 n = mpn_set_str (m, src, len, 256);
208 n = mpn_get_str (dst_, cmap.size, m, n);
209
210 int plen = elen; // for padding
211
212 while (n < plen)
213 {
214 *dst++ = cmap.encode [0];
215 plen--;
216 }
217
218 for (unsigned int i = n - plen; i < n; ++i)
219 *dst++ = cmap.encode [dst_ [i]];
220
221 return elen;
222}
223
224unsigned int
225basecoder::decode (u8 *dst, char *src, unsigned int len)
226{
227 if (!len || len > MAX_ENC_LEN)
228 return 0;
229
230 u8 src_ [MAX_ENC_LEN];
231 unsigned int elen = 0;
117 232
118 while (len--) 233 while (len--)
119 { 234 {
120 accum <<= 8; 235 u8 val = cmap.decode [(u8)*src++];
121 accum |= *src++;
122 bits += 8;
123 236
124 while (bits >= 6) 237 if (val != charmap::INVALID)
125 { 238 src_ [elen++] = val;
126 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 239 }
127 bits -= 6; 240
128 } 241 int dlen = decode_len (elen);
242
243 mp_limb_t m [MAX_LIMBS];
244 mp_size_t n;
245
246 u8 dst_ [MAX_DEC_LEN];
247
248 n = mpn_set_str (m, src_, elen, cmap.size);
249 n = mpn_get_str (dst_, 256, m, n);
250
251 if (n < dlen)
129 } 252 {
253 memset (dst, 0, dlen - n);
254 memcpy (dst + dlen - n, dst_, n);
255 }
256 else
257 memcpy (dst, dst_ + n - dlen, dlen);
130 258
131 if (bits) 259 return dlen;
132 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
133
134 return dst - beg;
135} 260}
136 261
137int dns64::decode (u8 *dst, char *src, int len) 262#if 0
138{ 263struct test { test (); } test;
139 // slow, but easy to debug
140 u8 *beg = dst;
141 unsigned int accum, bits = 0;
142 264
143 while (len--) 265test::test ()
266{
267 basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
268
269 u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
270 static char enc[200];
271 static u8 dec[200];
272
273 for (int i = 1; i < 20; i++)
144 { 274 {
145 s8 chr = decode_chars [(u8)*src++]; 275 int elen = cdc.encode (enc, in, i);
276 int dlen = cdc.decode (dec, enc, elen);
146 277
147 if (!chr) 278 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
148 continue;
149
150 accum <<= 6;
151 accum |= chr - 1;
152 bits += 6;
153
154 while (bits >= 8)
155 {
156 *dst++ = accum >> (bits - 8);
157 bits -= 8;
158 }
159 } 279 }
280 abort ();
281}
282#endif
160 283
161 return dst - beg; 284//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
285//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
286static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
287//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
288static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
289
290/////////////////////////////////////////////////////////////////////////////
291
292#define HDRSIZE 6
293
294inline void
295encode_header (char *data, int clientid, int seqno, int retry = 0)
296{
297 seqno &= SEQNO_MASK;
298
299 u8 hdr[3] = {
300 clientid,
301 (seqno >> 8) | (retry << 6),
302 seqno,
303 };
304
305 assert (clientid < 256);
306
307 cdc26.encode (data, hdr, 3);
308}
309
310inline void
311decode_header (char *data, int &clientid, int &seqno)
312{
313 u8 hdr[3];
314
315 cdc26.decode (hdr, data, HDRSIZE);
316
317 clientid = hdr[0];
318 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
162} 319}
163 320
164///////////////////////////////////////////////////////////////////////////// 321/////////////////////////////////////////////////////////////////////////////
165 322
166struct byte_stream 323struct byte_stream
… …
192byte_stream::~byte_stream () 349byte_stream::~byte_stream ()
193{ 350{
194 delete data; 351 delete data;
195} 352}
196 353
354void
197void byte_stream::remove (int count) 355byte_stream::remove (int count)
198{ 356{
199 if (count > fill) 357 if (count > fill)
200 abort (); 358 assert (count <= fill);
201 359
202 memmove (data, data + count, fill -= count); 360 memmove (data, data + count, fill -= count);
203} 361}
204 362
363bool
205bool byte_stream::put (u8 *data, unsigned int datalen) 364byte_stream::put (u8 *data, unsigned int datalen)
206{ 365{
207 if (maxsize - fill < datalen) 366 if (maxsize - fill < datalen)
208 return false; 367 return false;
209 368
210 memcpy (this->data + fill, data, datalen); fill += datalen; 369 memcpy (this->data + fill, data, datalen); fill += datalen;
211 370
212 return true; 371 return true;
213} 372}
214 373
374bool
215bool byte_stream::put (vpn_packet *pkt) 375byte_stream::put (vpn_packet *pkt)
216{ 376{
217 if (maxsize - fill < pkt->len + 2) 377 if (maxsize - fill < pkt->len + 2)
218 return false; 378 return false;
219 379
220 data [fill++] = pkt->len >> 8; 380 data [fill++] = pkt->len >> 8;
221 data [fill++] = pkt->len; 381 data [fill++] = pkt->len;
222 382
223 memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; 383 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
224 384
225 return true; 385 return true;
226} 386}
227 387
228vpn_packet *byte_stream::get () 388vpn_packet *byte_stream::get ()
229{ 389{
390 unsigned int len;
391
392 for (;;)
393 {
230 int len = (data [0] << 8) | data [1]; 394 len = (data [0] << 8) | data [1];
231 395
232 if (len > MAXSIZE && fill >= 2) 396 if (len <= MAXSIZE || fill < 2)
233 abort (); // TODO handle this gracefully, connection reset 397 break;
234 398
399 // TODO: handle this better than skipping, e.g. by reset
400 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
401 remove (1);
402 }
403
235 if (fill < len + 2) 404 if (fill < len + 2)
236 return 0; 405 return 0;
237 406
238 vpn_packet *pkt = new vpn_packet; 407 vpn_packet *pkt = new vpn_packet;
239 408
240 pkt->len = len; 409 pkt->len = len;
241 memcpy (&((*pkt)[0]), data + 2, len); 410 memcpy (pkt->at (0), data + 2, len);
242 remove (len + 2); 411 remove (len + 2);
243 412
244 return pkt; 413 return pkt;
245} 414}
246 415
247///////////////////////////////////////////////////////////////////////////// 416/////////////////////////////////////////////////////////////////////////////
248 417
249#define FLAG_QUERY ( 0 << 15) 418#define FLAG_QUERY ( 0 << 15)
250#define FLAG_RESPONSE ( 1 << 15) 419#define FLAG_RESPONSE ( 1 << 15)
251#define FLAG_OP_MASK (15 << 14) 420#define FLAG_OP_MASK (15 << 11)
252#define FLAG_OP_QUERY ( 0 << 11) 421#define FLAG_OP_QUERY ( 0 << 11)
253#define FLAG_AA ( 1 << 10) 422#define FLAG_AA ( 1 << 10)
254#define FLAG_TC ( 1 << 9) 423#define FLAG_TC ( 1 << 9)
255#define FLAG_RD ( 1 << 8) 424#define FLAG_RD ( 1 << 8)
256#define FLAG_RA ( 1 << 7) 425#define FLAG_RA ( 1 << 7)
… …
263#define FLAG_RCODE_REFUSED ( 5 << 0) 432#define FLAG_RCODE_REFUSED ( 5 << 0)
264 433
265#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 434#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
266#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) 435#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
267 436
437struct dns_cfg
438{
439 static int next_uid;
440
441 u8 id1, id2, id3, id4;
442
443 u8 version;
444 u8 flags;
445 u8 rrtype;
446 u8 def_ttl;
447
448 u16 client;
449 u16 uid; // to make request unique
450
451 u16 max_size;
452 u8 seq_cdc;
453 u8 req_cdc;
454
455 u8 rep_cdc;
456 u8 delay; // time in 0.01s units that the server may delay replying packets
457 u8 r3, r4;
458
459 u8 r5, r6, r7, r8;
460
461 void reset (int clientid);
462 bool valid ();
463};
464
465int dns_cfg::next_uid;
466
467void
468dns_cfg::reset (int clientid)
469{
470 id1 = 'G';
471 id2 = 'V';
472 id3 = 'P';
473 id4 = 'E';
474
475 version = 1;
476
477 rrtype = RR_TYPE_TXT;
478 flags = 0;
479 def_ttl = 0;
480 seq_cdc = 26;
481 req_cdc = 62;
482 rep_cdc = 0;
483 max_size = htons (MAX_PKT_SIZE);
484 client = htons (clientid);
485 uid = next_uid++;
486 delay = 0;
487
488 r3 = r4 = 0;
489 r4 = r5 = r6 = r7 = 0;
490}
491
492bool
493dns_cfg::valid ()
494{
495 // although the protocol itself allows for some configurability,
496 // only the following encoding/decoding settings are implemented.
497 return id1 == 'G'
498 && id2 == 'V'
499 && id3 == 'P'
500 && id4 == 'E'
501 && seq_cdc == 26
502 && req_cdc == 62
503 && rep_cdc == 0
504 && version == 1;
505}
506
268struct dns_packet : net_packet 507struct dns_packet : net_packet
269{ 508{
270 u16 id; 509 u16 id;
271 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 510 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
272 u16 qdcount, ancount, nscount, arcount; 511 u16 qdcount, ancount, nscount, arcount;
273 512
274 u8 data[MAXSIZE - 6 * 2]; 513 u8 data [MAXSIZE - 6 * 2];
275 514
276 int decode_label (char *data, int size, int &offs); 515 int decode_label (char *data, int size, int &offs);
277}; 516};
278 517
518int
279int dns_packet::decode_label (char *data, int size, int &offs) 519dns_packet::decode_label (char *data, int size, int &offs)
280{ 520{
281 char *orig = data; 521 char *orig = data;
282 522
283 memset (data, 0, size); 523 memset (data, 0, size);
284 524
… …
310 return data - orig; 550 return data - orig;
311} 551}
312 552
313///////////////////////////////////////////////////////////////////////////// 553/////////////////////////////////////////////////////////////////////////////
314 554
315struct dns_req 555static
556u16 next_id ()
316{ 557{
317 dns_packet *pkt;
318 tstamp next;
319 int retry;
320 connection *conn;
321 int seqno;
322
323 dns_req (connection *c);
324 void gen_stream_req (int seqno, byte_stream *stream);
325};
326
327static u16 dns_id = 12098; // TODO: should be per-vpn 558 static u16 dns_id = 0; // TODO: should be per-vpn
328 559
329static u16 next_id () 560 if (!dns_id)
330{ 561 dns_id = time (0);
562
331 // the simplest lsfr with periodicity 65535 i could find 563 // the simplest lsfr with periodicity 65535 i could find
332 dns_id = (dns_id << 1) 564 dns_id = (dns_id << 1)
333 | (((dns_id >> 1) 565 | (((dns_id >> 1)
334 ^ (dns_id >> 2) 566 ^ (dns_id >> 2)
335 ^ (dns_id >> 4) 567 ^ (dns_id >> 4)
336 ^ (dns_id >> 15)) & 1); 568 ^ (dns_id >> 15)) & 1);
337 569
338 return dns_id; 570 return dns_id;
339} 571}
340 572
341dns_req::dns_req (connection *c) 573struct dns_rcv;
342: conn (c) 574struct dns_snd;
575
576struct dns_connection
343{ 577{
344 next = 0; 578 connection *c;
579 struct vpn *vpn;
580
581 dns_cfg cfg;
582
583 bool established;
584
585 tstamp last_received;
586 tstamp last_sent;
587 double min_latency;
588 double poll_interval, send_interval;
589
590 vector<dns_rcv *> rcvpq;
591
592 byte_stream rcvdq; int rcvseq; int repseq;
593 byte_stream snddq; int sndseq;
594
595 inline void time_cb (ev::timer &w, int revents); ev::timer tw;
596 void receive_rep (dns_rcv *r);
597
598 dns_connection (connection *c);
599 ~dns_connection ();
600};
601
602struct dns_snd
603{
604 dns_packet *pkt;
605 tstamp timeout, sent;
606 int retry;
607 struct dns_connection *dns;
608 int seqno;
609 bool stdhdr;
610
611 void gen_stream_req (int seqno, byte_stream &stream);
612 void gen_syn_req ();
613
614 dns_snd (dns_connection *dns);
615 ~dns_snd ();
616};
617
618dns_snd::dns_snd (dns_connection *dns)
619: dns (dns)
620{
621 timeout = 0;
345 retry = 0; 622 retry = 0;
623 seqno = 0;
624 sent = ev_now ();
625 stdhdr = false;
346 626
347 pkt = new dns_packet; 627 pkt = new dns_packet;
348 628
349 pkt->id = next_id (); 629 pkt->id = next_id ();
350} 630}
351 631
632dns_snd::~dns_snd ()
633{
634 delete pkt;
635}
636
637static void
638append_domain (dns_packet &pkt, int &offs, const char *domain)
639{
640 // add tunnel domain
641 for (;;)
642 {
643 const char *end = strchr (domain, '.');
644
645 if (!end)
646 end = domain + strlen (domain);
647
648 int len = end - domain;
649
650 pkt [offs++] = len;
651 memcpy (pkt.at (offs), domain, len);
652 offs += len;
653
654 if (!*end)
655 break;
656
657 domain = end + 1;
658 }
659}
660
661void
352void dns_req::gen_stream_req (int seqno, byte_stream *stream) 662dns_snd::gen_stream_req (int seqno, byte_stream &stream)
353{ 663{
664 stdhdr = true;
354 this->seqno = seqno; 665 this->seqno = seqno;
666
667 timeout = ev_now () + INITIAL_TIMEOUT;
355 668
356 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 669 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
357 pkt->qdcount = htons (1); 670 pkt->qdcount = htons (1);
358 671
359 int offs = 6*2; 672 int offs = 6*2;
360 int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2; 673 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
361 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, 674 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
362 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 675 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
363 676
364 u8 data[256]; //TODO
365
366 data[0] = THISNODE->id; //TODO
367 data[1] = seqno >> 7; //TODO
368 data[2] = seqno << 1; //TODO
369
370 int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
371
372 if (datalen > stream->size ())
373 datalen = stream->size ();
374
375 char enc[256], *encp = enc; 677 char enc[256], *encp = enc;
376 678 encode_header (enc, THISNODE->id, seqno);
377 memcpy (data + 3, stream->begin (), datalen); 679
378 int enclen = dns64::encode (enc, data, datalen + 3); 680 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
681
682 if (datalen > stream.size ())
683 datalen = stream.size ();
684
685 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
379 stream->remove (datalen); 686 stream.remove (datalen);
380 687
381 while (enclen) 688 while (enclen)
382 { 689 {
383 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; 690 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
384 691
… …
389 encp += lbllen; 696 encp += lbllen;
390 697
391 enclen -= lbllen; 698 enclen -= lbllen;
392 } 699 }
393 700
394 const char *suffix = THISNODE->domain; 701 append_domain (*pkt, offs, dns->c->conf->domain);
395
396 // add tunnel domain
397 for (;;)
398 {
399 const char *end = strchr (suffix, '.');
400
401 if (!end)
402 end = suffix + strlen (suffix);
403
404 int len = end - suffix;
405
406 (*pkt)[offs++] = len;
407 memcpy (&((*pkt)[offs]), suffix, len);
408 offs += len;
409
410 if (!*end)
411 break;
412
413 suffix = end + 1;
414 }
415 702
416 (*pkt)[offs++] = 0; 703 (*pkt)[offs++] = 0;
417 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 704 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
705 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
706
707 pkt->len = offs;
708}
709
710void
711dns_snd::gen_syn_req ()
712{
713 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
714
715 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
716 pkt->qdcount = htons (1);
717
718 int offs = 6 * 2;
719
720 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
721
722 assert (elen <= MAX_LBL_SIZE);
723
724 (*pkt)[offs] = elen;
725 offs += elen + 1;
726 append_domain (*pkt, offs, dns->c->conf->domain);
727
728 (*pkt)[offs++] = 0;
729 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
418 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 730 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
419 731
420 pkt->len = offs; 732 pkt->len = offs;
421} 733}
422 734
… …
441{ 753{
442 delete pkt; 754 delete pkt;
443} 755}
444 756
445///////////////////////////////////////////////////////////////////////////// 757/////////////////////////////////////////////////////////////////////////////
446 758
447struct dns_cfg 759dns_connection::dns_connection (connection *c)
760: c (c)
761, rcvdq (MAX_BACKLOG * 2)
762, snddq (MAX_BACKLOG)
448{ 763{
449 u8 id1, id2, id3; 764 tw.set<dns_connection, &dns_connection::time_cb> (this);
450 u8 def_ttl;
451 u8 unused1;
452 u16 max_size;
453 u8 flags1, flags2;
454};
455 765
766 vpn = c->vpn;
767
768 established = false;
769
770 rcvseq = repseq = sndseq = 0;
771
772 last_sent = last_received = 0;
773 poll_interval = 0.5; // starting here
774 send_interval = 0.5; // starting rate
775 min_latency = INITIAL_TIMEOUT;
776}
777
778dns_connection::~dns_connection ()
779{
780 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
781 i != rcvpq.end ();
782 ++i)
783 delete *i;
784}
785
786void
456void connection::dnsv4_receive_rep (struct dns_rcv *r) 787dns_connection::receive_rep (dns_rcv *r)
457{ 788{
789 if (r->datalen)
790 {
791 last_received = ev_now ();
792 tw ();
793
794 poll_interval = send_interval;
795 }
796 else
797 {
798 poll_interval *= 1.5;
799
800 if (poll_interval > MAX_POLL_INTERVAL)
801 poll_interval = MAX_POLL_INTERVAL;
802 }
803
458 dns_rcvpq.push_back (r); 804 rcvpq.push_back (r);
459 805
460 redo: 806 redo:
461 807
808 // find next packet
462 for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin (); 809 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
463 i != dns_rcvpq.end ();
464 ++i)
465 if (dns_rcvseq == (*i)->seqno) 810 if (SEQNO_EQ (rcvseq, (*i)->seqno))
466 { 811 {
812 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
813 // enter the packet into our input stream
467 dns_rcv *r = *i; 814 r = *i;
468 815
816 // remove the oldest packet, look forward, as it's oldest first
817 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
818 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
819 {
820 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
821 delete *j;
822 rcvpq.erase (j);
823 break;
824 }
825
469 dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; 826 rcvseq = (rcvseq + 1) & SEQNO_MASK;
470 827
471 if (!dns_snddq && !dns_rcvdq) 828 if (!rcvdq.put (r->data, r->datalen))
472 { 829 {
473 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); 830 // MUST never overflow, can be caused by data corruption, TODO
474 dns_snddq = new byte_stream (MAX_BACKLOG); 831 slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)");
475 832 c->dnsv4_reset_connection ();
476 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 833 return;
477 } 834 }
478 835
479 if (!dns_rcvdq->put (r->data, r->datalen))
480 abort (); // MUST never overflow, can be caused by data corruption, TODO
481
482 while (vpn_packet *pkt = dns_rcvdq->get ()) 836 while (vpn_packet *pkt = rcvdq.get ())
483 { 837 {
484 sockinfo si; 838 sockinfo si;
485 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 839 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
486 840
487 vpn->recv_vpn_packet (pkt, si); 841 vpn->recv_vpn_packet (pkt, si);
842 delete pkt;
488 } 843 }
489 } 844
490 else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2) 845 // check for further packets
491 {
492 //D
493 //abort();
494 printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
495 dns_rcvpq.erase (i);
496 goto redo; 846 goto redo;
497 } 847 }
498} 848}
499 849
500dns_packet * 850void
501vpn::dnsv4_server (dns_packet *pkt) 851vpn::dnsv4_server (dns_packet &pkt)
502{ 852{
503 u16 flags = ntohs (pkt->flags); 853 u16 flags = ntohs (pkt.flags);
504 854
505 //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
506 int offs = 6 * 2; // skip header 855 int offs = 6 * 2; // skip header
507 856
508 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 857 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
509 858
510 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 859 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
511 && pkt->qdcount == htons (1)) 860 && pkt.qdcount == htons (1))
512 { 861 {
513 char qname[MAXSIZE]; 862 char qname [MAXSIZE];
514 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 863 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
515 864
516 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 865 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
517 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 866 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
518 867
519 pkt->qdcount = htons (1); 868 pkt.qdcount = htons (1);
520 pkt->ancount = 0; 869 pkt.ancount = 0;
521 pkt->nscount = 0; // should be self, as other nameservers reply like this 870 pkt.nscount = 0; // should be self, as other nameservers reply like this
522 pkt->arcount = 0; // a record for self, as other nameservers reply like this 871 pkt.arcount = 0; // a record for self, as other nameservers reply like this
523 872
524 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 873 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
525 874
526 int dlen = strlen (THISNODE->domain); 875 int dlen = strlen (THISNODE->domain);
527 876
528 if (qclass == RR_CLASS_IN 877 if (qclass == RR_CLASS_IN
529 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
530 && qlen > dlen + 1 878 && qlen > dlen + 1
531 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 879 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
532 { 880 {
533 // correct class, domain: parse 881 // now generate reply
534 u8 data[MAXSIZE]; 882 pkt.ancount = htons (1); // one answer RR
535 int datalen = dns64::decode (data, qname, qlen - dlen - 1); 883 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
536 884
537 int client = data[0]; 885 if ((qtype == RR_TYPE_ANY
538 int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK; 886 || qtype == RR_TYPE_TXT
539 887 || qtype == RR_TYPE_NULL)
540 if (0 < client && client <= conns.size ()) 888 && qlen > dlen + 1 + HDRSIZE)
541 { 889 {
890 // correct class, domain: parse
891 int client, seqno;
892 decode_header (qname, client, seqno);
893
894 u8 data[MAXSIZE];
895 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
896
897 if (0 < client && client <= conns.size ())
898 {
542 connection *c = conns [client - 1]; 899 connection *c = conns [client - 1];
900 dns_connection *dns = c->dns;
901 dns_rcv *rcv;
543 902
544 redo: 903 if (dns)
545
546 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
547 i != c->dns_rcvpq.end ();
548 ++i) 904 {
905 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
549 if ((*i)->seqno == seqno) 906 if (SEQNO_EQ ((*i)->seqno, seqno))
907 {
908 // already seen that request: simply reply with the cached reply
909 dns_rcv *r = *i;
910
911 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
912
913 // refresh header & id, as the retry count could have changed
914 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
915 r->pkt->id = pkt.id;
916
917 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
918
919 goto duplicate_request;
920 }
921
922 // new packet, queue
923 rcv = new dns_rcv (seqno, data, datalen);
924 dns->receive_rep (rcv);
925 }
926
550 { 927 {
551 // already seen that request: simply reply with the cached reply 928 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
552 dns_rcv *r = *i;
553 929
554 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D 930 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
931 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
932 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
933 pkt [offs++] = 0; pkt [offs++] = 0;
934 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
555 935
936 int rdlen_offs = offs += 2;
937
938 if (dns)
939 {
940 int dlen = ntohs (dns->cfg.max_size) - offs;
941
942 // bind doesn't compress well, so reduce further by one label length
943 dlen -= qlen;
944
945 // only put data into in-order sequence packets, if
946 // we receive out-of-order packets we generate empty
947 // replies
948 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
949 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
950 {
951 dns->repseq = seqno;
952
953 while (dlen > 1 && !dns->snddq.empty ())
954 {
955 int txtlen = dlen <= 255 ? dlen - 1 : 255;
956
957 if (txtlen > dns->snddq.size ())
958 txtlen = dns->snddq.size ();
959
960 pkt[offs++] = txtlen;
961 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
962 offs += txtlen;
963 dns->snddq.remove (txtlen);
964
965 dlen -= txtlen + 1;
966 }
967 }
968
969 // avoid completely empty TXT rdata
970 if (offs == rdlen_offs)
971 pkt[offs++] = 0;
972
973 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
974 }
975 else
976 {
977 // send RST
978 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
979 pkt [offs++] = CMD_IP_RST;
980 }
981
982 int rdlen = offs - rdlen_offs;
983
984 pkt [rdlen_offs - 2] = rdlen >> 8;
985 pkt [rdlen_offs - 1] = rdlen;
986
987 if (dns)
988 {
989 // now update dns_rcv copy
556 offs = r->pkt->len; 990 rcv->pkt->len = offs;
557 memcpy (pkt->at (0), r->pkt->at (0), offs); 991 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
558 goto duplicate_request; 992 }
559 } 993 }
560 994
561 // new packet, queue 995 duplicate_request: ;
562 dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3); 996 }
563 c->dnsv4_receive_rep (rcv); 997 else
564
565 // now generate reply
566 pkt->ancount = htons (1); // one answer RR
567 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 998 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
999 }
1000 else if (qtype == RR_TYPE_A
1001 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
1002 {
1003 dns_cfg cfg;
1004 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
1005 int client = ntohs (cfg.client);
568 1006
569 (*pkt) [offs++] = 0xc0;
570 (*pkt) [offs++] = 6 * 2; // same as in query section 1007 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
571 1008
572 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; 1009 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
573 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; 1010 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
574
575 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; 1011 pkt [offs++] = 0; pkt [offs++] = 0;
576 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL 1012 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
1013 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
577 1014
578 int dlen = MAX_PKT_SIZE - offs - 2; 1015 slog (L_INFO, _("DNS: client %d connects"), client);
579 1016
580 // bind doesn't compress well, so reduce further by one label length 1017 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
581 dlen -= qlen; 1018 pkt [offs++] = CMD_IP_REJ;
582 1019
583 int rdlen_offs = offs += 2; 1020 if (0 < client && client <= conns.size ())
584
585 while (c->dns_snddq
586 && !c->dns_snddq->empty ()
587 && dlen > 1)
588 { 1021 {
589 int txtlen = dlen <= 255 ? dlen - 1 : 255; 1022 connection *c = conns [client - 1];
590 1023
591 if (txtlen > c->dns_snddq->size ()) 1024 if (cfg.valid ())
592 txtlen = c->dns_snddq->size (); 1025 {
1026 pkt [offs - 1] = CMD_IP_SYN;
593 1027
594 (*pkt)[offs++] = txtlen; 1028 delete c->dns;
595 memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen); 1029 c->dns = new dns_connection (c);
596 offs += txtlen; 1030 c->dns->cfg = cfg;
597 c->dns_snddq->remove (txtlen); 1031 }
598
599 dlen -= txtlen + 1;
600 } 1032 }
601
602 // avoid empty TXT rdata
603 if (offs == rdlen_offs)
604 (*pkt)[offs++] = 0;
605
606 int rdlen = offs - rdlen_offs;
607
608 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
609 (*pkt) [rdlen_offs - 1] = rdlen;
610
611 // now update dns_rcv copy
612 rcv->pkt->len = offs;
613 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
614
615 duplicate_request: ;
616 } 1033 }
617 else
618 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
619 } 1034 }
620 1035
621 pkt->len = offs; 1036 pkt.len = offs;
622 } 1037 }
623
624 return pkt;
625} 1038}
626 1039
627void 1040void
628vpn::dnsv4_client (dns_packet *pkt) 1041vpn::dnsv4_client (dns_packet &pkt)
629{ 1042{
630 u16 flags = ntohs (pkt->flags); 1043 u16 flags = ntohs (pkt.flags);
631 int offs = 6 * 2; // skip header 1044 int offs = 6 * 2; // skip header
632 1045
633 pkt->qdcount = ntohs (pkt->qdcount); 1046 pkt.qdcount = ntohs (pkt.qdcount);
634 pkt->ancount = ntohs (pkt->ancount); 1047 pkt.ancount = ntohs (pkt.ancount);
635 1048
636 // go through our request list and find the corresponding request 1049 // go through our request list and find the corresponding request
637 for (vector<dns_req *>::iterator i = dns_sndpq.begin (); 1050 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
638 i != dns_sndpq.end (); 1051 i != dns_sndpq.end ();
639 ++i) 1052 ++i)
640 if ((*i)->pkt->id == pkt->id) 1053 if ((*i)->pkt->id == pkt.id)
641 { 1054 {
1055 dns_connection *dns = (*i)->dns;
642 connection *c = (*i)->conn; 1056 connection *c = dns->c;
643 int seqno = (*i)->seqno; 1057 int seqno = (*i)->seqno;
644 u8 data[MAXSIZE], *datap = data; 1058 u8 data[MAXSIZE], *datap = data;
1059 //printf ("rcv pkt %x\n", seqno);//D
1060
1061 if ((*i)->retry)
1062 {
1063 dns->send_interval *= 1.01;
1064 if (dns->send_interval > MAX_SEND_INTERVAL)
1065 dns->send_interval = MAX_SEND_INTERVAL;
1066 }
1067 else
1068 {
1069#if 0
1070 dns->send_interval *= 0.999;
1071#endif
1072 // the latency surely puts an upper bound on
1073 // the minimum send interval
1074 double latency = ev_now () - (*i)->sent;
1075
1076 if (latency < dns->min_latency)
1077 dns->min_latency = latency;
1078
1079 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1080 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1081
1082 if (dns->send_interval < conf.dns_send_interval)
1083 dns->send_interval = conf.dns_send_interval;
1084 }
645 1085
646 delete *i; 1086 delete *i;
647 dns_sndpq.erase (i); 1087 dns_sndpq.erase (i);
648 1088
649 if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) 1089 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
650 { 1090 {
651 char qname[MAXSIZE]; 1091 char qname[MAXSIZE];
652 1092
653 while (pkt->qdcount-- && offs < MAXSIZE - 4) 1093 while (pkt.qdcount-- && offs < MAXSIZE - 4)
654 { 1094 {
655 int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1095 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
656 offs += 4; // skip qtype, qclass 1096 offs += 4; // skip qtype, qclass
657 } 1097 }
658 1098
659 while (pkt->ancount-- && offs < MAXSIZE - 10) 1099 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
660 { 1100 {
661 pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); 1101 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
662 1102
663 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; 1103 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
664 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; 1104 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
665 u32 ttl = (*pkt) [offs++] << 24; 1105 u32 ttl = pkt [offs++] << 24;
666 ttl |= (*pkt) [offs++] << 16; 1106 ttl |= pkt [offs++] << 16;
667 ttl |= (*pkt) [offs++] << 8; 1107 ttl |= pkt [offs++] << 8;
668 ttl |= (*pkt) [offs++]; 1108 ttl |= pkt [offs++];
669
670 u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; 1109 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
671 1110
672 if (rdlen <= MAXSIZE - offs) 1111 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
673 { 1112 {
674 // decode bytes, finally 1113 if (rdlen <= MAXSIZE - offs)
675
676 while (rdlen)
677 { 1114 {
1115 // decode bytes, finally
1116
1117 while (rdlen)
1118 {
678 int txtlen = (*pkt) [offs++]; 1119 int txtlen = pkt [offs++];
679 1120
680 assert (txtlen + offs < MAXSIZE - 1); 1121 assert (txtlen + offs < MAXSIZE - 1);
681 1122
682 memcpy (datap, pkt->at (offs), txtlen); 1123 memcpy (datap, pkt.at (offs), txtlen);
683 datap += txtlen; offs += txtlen; 1124 datap += txtlen; offs += txtlen;
684 1125
685 rdlen -= txtlen + 1; 1126 rdlen -= txtlen + 1;
1127 }
686 } 1128 }
687
688 } 1129 }
1130 else if (qtype == RR_TYPE_A)
1131 {
1132 u8 ip [4];
689 1133
1134 ip [0] = pkt [offs++];
1135 ip [1] = pkt [offs++];
1136 ip [2] = pkt [offs++];
1137 ip [3] = pkt [offs++];
1138
1139 if (ip [0] == CMD_IP_1
1140 && ip [1] == CMD_IP_2
1141 && ip [2] == CMD_IP_3)
1142 {
1143 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1144
1145 if (ip [3] == CMD_IP_RST)
1146 {
1147 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1148
1149 c->dnsv4_reset_connection ();
1150 }
1151 else if (ip [3] == CMD_IP_SYN)
1152 {
1153 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1154 dns->established = true;
1155 }
1156 else if (ip [3] == CMD_IP_REJ)
1157 slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us."));
1158 else
1159 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1160 }
1161 else
1162 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1163 ip [0], ip [1], ip [2], ip [3]);
1164
1165 return;
1166 }
1167
1168 int client, rseqno;
1169 decode_header (qname, client, rseqno);
1170
1171 if (client != THISNODE->id)
1172 {
1173 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1174 datap = 0;
1175 }
1176 else if (rseqno != seqno)
1177 {
1178 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1179 datap = 0;
1180 }
690 } 1181 }
691 } 1182 }
692 1183
693 // todo: pkt now used 1184 // todo: pkt now used
1185 if (datap)
694 c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data)); 1186 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
695 1187
696 break; 1188 break;
697 } 1189 }
698
699 delete pkt;
700} 1190}
701 1191
702void 1192void
703vpn::dnsv4_ev (io_watcher &w, short revents) 1193vpn::dnsv4_ev (ev::io &w, int revents)
704{ 1194{
705 if (revents & EVENT_READ) 1195 if (revents & EV_READ)
706 { 1196 {
707 dns_packet *pkt = new dns_packet; 1197 dns_packet *pkt = new dns_packet;
708 struct sockaddr_in sa; 1198 struct sockaddr_in sa;
709 socklen_t sa_len = sizeof (sa); 1199 socklen_t sa_len = sizeof (sa);
710 1200
711 pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1201 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
712 1202
713 if (pkt->len > 0) 1203 if (pkt->len > 0)
714 { 1204 {
715 if (pkt->flags & htons (FLAG_TC)) 1205 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1206 dnsv4_client (*pkt);
1207 else
716 { 1208 {
717 slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); 1209 dnsv4_server (*pkt);
718 //TODO connection reset 1210 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
719 } 1211 }
720 1212
721 if (THISNODE->dns_port) 1213 delete pkt;
722 {
723 pkt = dnsv4_server (pkt);
724 sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
725 }
726 else
727 dnsv4_client (pkt);
728 } 1214 }
729 } 1215 }
730} 1216}
731 1217
732bool 1218bool
733connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1219vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
734{ 1220{
735 // never initialized 1221 int client = ntohl (si.host);
736 if (!dns_snddq && !dns_rcvdq)
737 {
738 dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
739 dns_snddq = new byte_stream (MAX_BACKLOG);
740 1222
741 //dns_rcvseq = dns_sndseq = 0; 1223 assert (0 < client && client <= conns.size ());
742 1224
743 dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); 1225 connection *c = conns [client - 1];
744 } 1226
1227 if (!c->dns)
1228 c->dns = new dns_connection (c);
745 1229
746 if (!dns_snddq->put (pkt)) 1230 if (c->dns->snddq.put (pkt))
747 return false; 1231 c->dns->tw ();
748 1232
749 // start timer if neccessary 1233 // always return true even if the buffer overflows
750 if (!THISNODE->dns_port && !dnsv4_tw.active)
751 dnsv4_cb (dnsv4_tw);
752
753 return true; 1234 return true;
754} 1235}
755 1236
756void 1237void
757connection::dnsv4_cb (time_watcher &w) 1238connection::dnsv4_reset_connection ()
758{ 1239{
1240 //delete dns; dns = 0; //TODO
1241}
1242
1243#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1244
1245void
1246dns_connection::time_cb (ev::timer &w, int revents)
1247{
1248 // servers have to be polled
1249 if (THISNODE->dns_port)
1250 return;
1251
759 // check for timeouts and (re)transmit 1252 // check for timeouts and (re)transmit
760 tstamp next = NOW + 60; 1253 tstamp next = ev::now () + poll_interval;
761 dns_req *send = 0; 1254 dns_snd *send = 0;
762 1255
763 for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin (); 1256 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
764 i != vpn->dns_sndpq.end (); 1257 i != vpn->dns_sndpq.end ();
765 ++i) 1258 ++i)
766 { 1259 {
767 dns_req *r = *i; 1260 dns_snd *r = *i;
768 1261
769 if (r->next <= NOW) 1262 if (r->timeout <= ev_now ())
770 { 1263 {
771 if (!send) 1264 if (!send)
772 { 1265 {
773 send = r; 1266 send = r;
774 1267
775 if (r->retry)//D
776 printf ("req %d, retry %d\n", r->pkt->id, r->retry);
777 r->retry++; 1268 r->retry++;
778 r->next = NOW + r->retry; 1269 r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
1270 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1271
1272 // the following code changes the query section a bit, forcing
1273 // the forwarder to generate a new request
1274 if (r->stdhdr)
1275 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
779 } 1276 }
780 } 1277 }
781 1278 else
782 if (r->next < next) 1279 NEXT (r->timeout);
783 next = r->next;
784 } 1280 }
785 1281
786 if (!send 1282 if (!send)
787 && vpn->dns_sndpq.size () < MAX_OUTSTANDING)
788 { 1283 {
1284 // generate a new packet, if wise
1285
1286 if (!established)
1287 {
1288 if (vpn->dns_sndpq.empty ())
1289 {
789 send = new dns_req (this); 1290 send = new dns_snd (this);
1291
1292 cfg.reset (THISNODE->id);
1293 send->gen_syn_req ();
1294 }
1295 }
1296 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1297 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1298 {
1299 if (last_sent + send_interval <= ev_now ())
1300 {
1301 //printf ("sending data request etc.\n"); //D
1302 if (!snddq.empty () || last_received + 1. > ev_now ())
1303 {
1304 poll_interval = send_interval;
1305 NEXT (ev_now () + send_interval);
1306 }
1307
1308 send = new dns_snd (this);
790 send->gen_stream_req (dns_sndseq, dns_snddq); 1309 send->gen_stream_req (sndseq, snddq);
1310 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1311 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1312
1313 sndseq = (sndseq + 1) & SEQNO_MASK;
1314 }
1315 else
1316 NEXT (last_sent + send_interval);
1317 }
1318
1319 if (send)
791 vpn->dns_sndpq.push_back (send); 1320 vpn->dns_sndpq.push_back (send);
792
793 dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
794 } 1321 }
795
796 tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
797 1322
798 if (send) 1323 if (send)
799 { 1324 {
800 dns_packet *pkt = send->pkt; 1325 last_sent = ev_now ();
801 1326 sendto (vpn->dnsv4_fd,
802 next = min_next; 1327 send->pkt->at (0), send->pkt->len, 0,
803 1328 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
804 sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
805 } 1329 }
806 else if (next < min_next)
807 next = min_next;
808 1330
809 w.start (next); 1331 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1332 poll_interval, send_interval, next - ev_now (),
1333 vpn->dns_sndpq.size (), snddq.size (),
1334 rcvpq.size ());
1335
1336 // TODO: no idea when this happens, but when next < ev_now (), we have a problem
1337 // doesn't seem to happen anymore
1338 if (next < ev_now () + 0.001)
1339 next = ev_now () + 0.1;
1340
1341 w.start (next - ev_now ());
810} 1342}
811 1343
812#endif 1344#endif
813 1345

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