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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.3 by pcg, Tue Mar 1 06:27:20 2005 UTC vs.
Revision 1.42 by pcg, Sat Nov 10 05:14:22 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 <gmp.h>
48
40#include "netcompat.h" 49#include "netcompat.h"
41 50
42#include "vpn.h" 51#include "vpn.h"
43 52
44#define MIN_RETRY 1. 53#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45#define MAX_RETRY 60. 54#define ACTIVITY_INTERVAL 5.
46 55
47#define MAX_OUTSTANDING 10 // max. outstanding requests 56#define INITIAL_TIMEOUT 0.1 // retry timeouts
57#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
48 58
49/* 59#define MAX_SEND_INTERVAL 2. // optimistic?
50 60
51protocol, in shorthand :) 61#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
62#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
52 63
53client -> server <req> ANY? 64#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
54server -> client <req> TXT <rep> 65// 240 leaves about 4 bytes of server reply data
66// every request byte less give room for two reply bytes
55 67
56<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>] 68#define SEQNO_MASK 0x3fff
57<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>] 69#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
58
59if <client-id> is zero, the connection will be configured:
60
61<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
62
63*/
64 70
65#define MAX_LBL_SIZE 63 71#define MAX_LBL_SIZE 63
66#define MAX_PKT_SIZE 512 72#define MAX_PKT_SIZE 512
67 73
74#define RR_TYPE_A 1
75#define RR_TYPE_NULL 10
68#define RR_TYPE_TXT 16 76#define RR_TYPE_TXT 16
69#define RR_TYPE_ANY 255 77#define RR_TYPE_ANY 255
78
70#define RR_CLASS_IN 1 79#define RR_CLASS_IN 1
71 80
72// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) 81#define CMD_IP_1 207
73struct dns64 82#define CMD_IP_2 46
74{ 83#define CMD_IP_3 236
75 static const char encode_chars[64 + 1]; 84#define CMD_IP_RST 29
76 static s8 decode_chars[256]; 85#define CMD_IP_SYN 113
86#define CMD_IP_REJ 32
77 87
78 static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } 88// works for cmaps up to 255 (not 256!)
79 static int decode_len (int bytes) { return (bytes * 6) / 8; } 89struct charmap
90{
91 enum { INVALID = (u8)255 };
92
93 char encode [256]; // index => char
94 u8 decode [256]; // char => index
95 unsigned int size;
96
97 charmap (const char *cmap);
98};
99
100charmap::charmap (const char *cmap)
101{
102 char *enc = encode;
103 u8 *dec = decode;
104
105 memset (enc, (char) 0, 256);
106 memset (dec, (char)INVALID, 256);
107
108 for (size = 0; cmap [size]; size++)
109 {
110 enc [size] = cmap [size];
111 dec [(u8)enc [size]] = size;
112 }
113
114 assert (size < 256);
115}
116
117#define MAX_DEC_LEN 500
118#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
119#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
120
121// ugly. minimum base is 16(!)
122struct basecoder
123{
124 charmap cmap;
125 unsigned int enc_len [MAX_DEC_LEN];
126 unsigned int dec_len [MAX_ENC_LEN];
127
128 unsigned int encode_len (unsigned int len);
129 unsigned int decode_len (unsigned int len);
130
80 static void encode (char *dst, u8 *src, int len); 131 unsigned int encode (char *dst, u8 *src, unsigned int len);
81 static void decode (u8 *dst, char *src, int len); 132 unsigned int decode (u8 *dst, char *src, unsigned int len);
82 133
83 dns64 (); 134 basecoder (const char *cmap);
84} dns64; 135};
85 136
86const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 137basecoder::basecoder (const char *cmap)
87s8 dns64::decode_chars[256]; 138: cmap (cmap)
88
89dns64::dns64 ()
90{ 139{
91 for (int i = 0; i < 64; i++) 140 for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
92 decode_chars [encode_chars [i]] = i + 1; 141 {
93} 142 u8 src [MAX_DEC_LEN];
143 u8 dst [MAX_ENC_LEN];
94 144
95void dns64::encode (char *dst, u8 *src, int len) 145 memset (src, 255, len);
146
147 mp_limb_t m [MAX_LIMBS];
148 mp_size_t n;
149
150 n = mpn_set_str (m, src, len, 256);
151 n = mpn_get_str (dst, this->cmap.size, m, n);
152
153 for (int i = 0; !dst [i]; ++i)
154 n--;
155
156 enc_len [len] = n;
157 dec_len [n] = len;
158 }
159}
160
161unsigned int basecoder::encode_len (unsigned int len)
96{ 162{
97 // slow, but easy to debug 163 return enc_len [len];
98 unsigned int accum, bits = 0; 164}
165
166unsigned int basecoder::decode_len (unsigned int len)
167{
168 while (len && !dec_len [len])
169 --len;
170
171 return dec_len [len];
172}
173
174unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
175{
176 if (!len || len > MAX_DEC_LEN)
177 return 0;
178
179 int elen = encode_len (len);
180
181 mp_limb_t m [MAX_LIMBS];
182 mp_size_t n;
183
184 u8 dst_ [MAX_ENC_LEN];
185
186 n = mpn_set_str (m, src, len, 256);
187 n = mpn_get_str (dst_, cmap.size, m, n);
188
189 int plen = elen; // for padding
190
191 while (n < plen)
192 {
193 *dst++ = cmap.encode [0];
194 plen--;
195 }
196
197 for (unsigned int i = n - plen; i < n; ++i)
198 *dst++ = cmap.encode [dst_ [i]];
199
200 return elen;
201}
202
203unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
204{
205 if (!len || len > MAX_ENC_LEN)
206 return 0;
207
208 u8 src_ [MAX_ENC_LEN];
209 unsigned int elen = 0;
99 210
100 while (len--) 211 while (len--)
101 { 212 {
102 accum <<= 8; 213 u8 val = cmap.decode [(u8)*src++];
103 accum |= *src++;
104 bits += 8;
105 214
106 while (bits >= 6) 215 if (val != charmap::INVALID)
107 { 216 src_ [elen++] = val;
108 *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; 217 }
109 bits -= 6; 218
110 } 219 int dlen = decode_len (elen);
220
221 mp_limb_t m [MAX_LIMBS];
222 mp_size_t n;
223
224 u8 dst_ [MAX_DEC_LEN];
225
226 n = mpn_set_str (m, src_, elen, cmap.size);
227 n = mpn_get_str (dst_, 256, m, n);
228
229 if (n < dlen)
111 } 230 {
231 memset (dst, 0, dlen - n);
232 memcpy (dst + dlen - n, dst_, n);
233 }
234 else
235 memcpy (dst, dst_ + n - dlen, dlen);
112 236
113 if (bits) 237 return dlen;
114 *dst++ = encode_chars [(accum << (6 - bits)) & 63];
115} 238}
116 239
117void dns64::decode (u8 *dst, char *src, int len) 240#if 0
118{ 241struct test { test (); } test;
119 // slow, but easy to debug
120 unsigned int accum, bits = 0;
121 242
122 while (len--) 243test::test ()
244{
245 basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
246
247 u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
248 static char enc[200];
249 static u8 dec[200];
250
251 for (int i = 1; i < 20; i++)
123 { 252 {
124 s8 chr = decode_chars [(u8)*src++]; 253 int elen = cdc.encode (enc, in, i);
254 int dlen = cdc.decode (dec, enc, elen);
125 255
256 printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
257 }
258 abort ();
259}
260#endif
126 261
127 if (!chr) 262//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
263//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
264static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
265//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
266static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
267
268/////////////////////////////////////////////////////////////////////////////
269
270#define HDRSIZE 6
271
272inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
273{
274 seqno &= SEQNO_MASK;
275
276 u8 hdr[3] = {
277 clientid,
278 (seqno >> 8) | (retry << 6),
279 seqno,
280 };
281
282 assert (clientid < 256);
283
284 cdc26.encode (data, hdr, 3);
285}
286
287inline void decode_header (char *data, int &clientid, int &seqno)
288{
289 u8 hdr[3];
290
291 cdc26.decode (hdr, data, HDRSIZE);
292
293 clientid = hdr[0];
294 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
295}
296
297/////////////////////////////////////////////////////////////////////////////
298
299struct byte_stream
300{
301 u8 *data;
302 int maxsize;
303 int fill;
304
305 byte_stream (int maxsize);
306 ~byte_stream ();
307
308 bool empty () { return !fill; }
309 int size () { return fill; }
310
311 bool put (u8 *data, unsigned int datalen);
312 bool put (vpn_packet *pkt);
313 vpn_packet *get ();
314
315 u8 *begin () { return data; }
316 void remove (int count);
317};
318
319byte_stream::byte_stream (int maxsize)
320: maxsize (maxsize), fill (0)
321{
322 data = new u8 [maxsize];
323}
324
325byte_stream::~byte_stream ()
326{
327 delete data;
328}
329
330void byte_stream::remove (int count)
331{
332 if (count > fill)
333 assert (count <= fill);
334
335 memmove (data, data + count, fill -= count);
336}
337
338bool byte_stream::put (u8 *data, unsigned int datalen)
339{
340 if (maxsize - fill < datalen)
341 return false;
342
343 memcpy (this->data + fill, data, datalen); fill += datalen;
344
345 return true;
346}
347
348bool byte_stream::put (vpn_packet *pkt)
349{
350 if (maxsize - fill < pkt->len + 2)
351 return false;
352
353 data [fill++] = pkt->len >> 8;
354 data [fill++] = pkt->len;
355
356 memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
357
358 return true;
359}
360
361vpn_packet *byte_stream::get ()
362{
363 unsigned int len;
364
365 for (;;)
366 {
367 len = (data [0] << 8) | data [1];
368
369 if (len <= MAXSIZE || fill < 2)
128 break; 370 break;
129 371
130 accum <<= 6; 372 // TODO: handle this better than skipping, e.g. by reset
131 accum |= chr - 1; 373 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
132 bits += 6; 374 remove (1);
133 375 }
134 while (bits >= 8)
135 { 376
136 *dst++ = accum >> (bits - 8); 377 if (fill < len + 2)
137 bits -= 8; 378 return 0;
138 } 379
139 } 380 vpn_packet *pkt = new vpn_packet;
381
382 pkt->len = len;
383 memcpy (pkt->at (0), data + 2, len);
384 remove (len + 2);
385
386 return pkt;
140} 387}
141 388
142///////////////////////////////////////////////////////////////////////////// 389/////////////////////////////////////////////////////////////////////////////
143 390
144#define FLAG_QUERY ( 0 << 15) 391#define FLAG_QUERY ( 0 << 15)
145#define FLAG_RESPONSE ( 1 << 15) 392#define FLAG_RESPONSE ( 1 << 15)
146#define FLAG_OP_MASK (15 << 14) 393#define FLAG_OP_MASK (15 << 11)
147#define FLAG_OP_QUERY ( 0 << 11) 394#define FLAG_OP_QUERY ( 0 << 11)
148#define FLAG_AA ( 1 << 10) 395#define FLAG_AA ( 1 << 10)
149#define FLAG_TC ( 1 << 9) 396#define FLAG_TC ( 1 << 9)
150#define FLAG_RD ( 1 << 8) 397#define FLAG_RD ( 1 << 8)
151#define FLAG_RA ( 1 << 7) 398#define FLAG_RA ( 1 << 7)
399#define FLAG_AUTH ( 1 << 5)
152#define FLAG_RCODE_MASK (15 << 0) 400#define FLAG_RCODE_MASK (15 << 0)
153#define FLAG_RCODE_OK ( 0 << 0) 401#define FLAG_RCODE_OK ( 0 << 0)
154#define FLAG_RCODE_FORMERR ( 1 << 0) 402#define FLAG_RCODE_FORMERR ( 1 << 0)
155#define FLAG_RCODE_SERVFAIL ( 2 << 0) 403#define FLAG_RCODE_SERVFAIL ( 2 << 0)
156#define FLAG_RCODE_NXDOMAIN ( 3 << 0) 404#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
157#define FLAG_RCODE_REFUSED ( 5 << 0) 405#define FLAG_RCODE_REFUSED ( 5 << 0)
158 406
159#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) 407#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
160#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD) 408#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
409
410struct dns_cfg
411{
412 static int next_uid;
413
414 u8 id1, id2, id3, id4;
415
416 u8 version;
417 u8 flags;
418 u8 rrtype;
419 u8 def_ttl;
420
421 u16 client;
422 u16 uid; // to make request unique
423
424 u16 max_size;
425 u8 seq_cdc;
426 u8 req_cdc;
427
428 u8 rep_cdc;
429 u8 delay; // time in 0.01s units that the server may delay replying packets
430 u8 r3, r4;
431
432 u8 r5, r6, r7, r8;
433
434 void reset (int clientid);
435 bool valid ();
436};
437
438int dns_cfg::next_uid;
439
440void dns_cfg::reset (int clientid)
441{
442 id1 = 'G';
443 id2 = 'V';
444 id3 = 'P';
445 id4 = 'E';
446
447 version = 1;
448
449 rrtype = RR_TYPE_TXT;
450 flags = 0;
451 def_ttl = 0;
452 seq_cdc = 26;
453 req_cdc = 62;
454 rep_cdc = 0;
455 max_size = htons (MAX_PKT_SIZE);
456 client = htons (clientid);
457 uid = next_uid++;
458 delay = 0;
459
460 r3 = r4 = 0;
461 r4 = r5 = r6 = r7 = 0;
462}
463
464bool dns_cfg::valid ()
465{
466 // although the protocol itself allows for some configurability,
467 // only the following encoding/decoding settings are implemented.
468 return id1 == 'G'
469 && id2 == 'V'
470 && id3 == 'P'
471 && id4 == 'E'
472 && seq_cdc == 26
473 && req_cdc == 62
474 && rep_cdc == 0
475 && version == 1;
476}
161 477
162struct dns_packet : net_packet 478struct dns_packet : net_packet
163{ 479{
164 u16 id; 480 u16 id;
165 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 481 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
166 u16 qdcount, ancount, nscount, arcount; 482 u16 qdcount, ancount, nscount, arcount;
167 483
168 u8 data[MAXSIZE - 6 * 2]; 484 u8 data [MAXSIZE - 6 * 2];
169 485
170 int decode_label (char *data, int size, int &offs); 486 int decode_label (char *data, int size, int &offs);
171}; 487};
172 488
173int dns_packet::decode_label (char *data, int size, int &offs) 489int dns_packet::decode_label (char *data, int size, int &offs)
204 return data - orig; 520 return data - orig;
205} 521}
206 522
207///////////////////////////////////////////////////////////////////////////// 523/////////////////////////////////////////////////////////////////////////////
208 524
525static u16 dns_id = 0; // TODO: should be per-vpn
526
527static u16 next_id ()
528{
529 if (!dns_id)
530 dns_id = time (0);
531
532 // the simplest lsfr with periodicity 65535 i could find
533 dns_id = (dns_id << 1)
534 | (((dns_id >> 1)
535 ^ (dns_id >> 2)
536 ^ (dns_id >> 4)
537 ^ (dns_id >> 15)) & 1);
538
539 return dns_id;
540}
541
209struct dns_req 542struct dns_rcv;
543struct dns_snd;
544
545struct dns_connection
546{
547 connection *c;
548 struct vpn *vpn;
549
550 dns_cfg cfg;
551
552 bool established;
553
554 tstamp last_received;
555 tstamp last_sent;
556 double min_latency;
557 double poll_interval, send_interval;
558
559 vector<dns_rcv *> rcvpq;
560
561 byte_stream rcvdq; int rcvseq; int repseq;
562 byte_stream snddq; int sndseq;
563
564 void time_cb (ev::timer &w, int revents); ev::timer tw;
565 void receive_rep (dns_rcv *r);
566
567 dns_connection (connection *c);
568 ~dns_connection ();
569};
570
571struct dns_snd
210{ 572{
211 dns_packet *pkt; 573 dns_packet *pkt;
212 tstamp next; 574 tstamp timeout, sent;
213 int retry; 575 int retry;
576 struct dns_connection *dns;
577 int seqno;
578 bool stdhdr;
214 579
215 dns_req (connection *c, vpn_packet *p, int &offs); 580 void gen_stream_req (int seqno, byte_stream &stream);
581 void gen_syn_req ();
582
583 dns_snd (dns_connection *dns);
584 ~dns_snd ();
216}; 585};
217 586
587dns_snd::dns_snd (dns_connection *dns)
588: dns (dns)
589{
590 timeout = 0;
591 retry = 0;
592 seqno = 0;
593 sent = ev::ev_now ();
594 stdhdr = false;
595
596 pkt = new dns_packet;
597
598 pkt->id = next_id ();
599}
600
601dns_snd::~dns_snd ()
602{
603 delete pkt;
604}
605
606static void append_domain (dns_packet &pkt, int &offs, const char *domain)
607{
608 // add tunnel domain
609 for (;;)
610 {
611 const char *end = strchr (domain, '.');
612
613 if (!end)
614 end = domain + strlen (domain);
615
616 int len = end - domain;
617
618 pkt [offs++] = len;
619 memcpy (pkt.at (offs), domain, len);
620 offs += len;
621
622 if (!*end)
623 break;
624
625 domain = end + 1;
626 }
627}
628
629void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
630{
631 stdhdr = true;
632 this->seqno = seqno;
633
634 timeout = ev::ev_now () + INITIAL_TIMEOUT;
635
636 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
637 pkt->qdcount = htons (1);
638
639 int offs = 6*2;
640 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
641 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
642 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
643
644 char enc[256], *encp = enc;
645 encode_header (enc, THISNODE->id, seqno);
646
647 int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
648
649 if (datalen > stream.size ())
650 datalen = stream.size ();
651
652 int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
653 stream.remove (datalen);
654
655 while (enclen)
656 {
657 int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
658
659 (*pkt)[offs++] = lbllen;
660 memcpy (pkt->at (offs), encp, lbllen);
661
662 offs += lbllen;
663 encp += lbllen;
664
665 enclen -= lbllen;
666 }
667
668 append_domain (*pkt, offs, dns->c->conf->domain);
669
670 (*pkt)[offs++] = 0;
671 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
672 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
673
674 pkt->len = offs;
675}
676
677void dns_snd::gen_syn_req ()
678{
679 timeout = ev::ev_now () + INITIAL_SYN_TIMEOUT;
680
681 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
682 pkt->qdcount = htons (1);
683
684 int offs = 6 * 2;
685
686 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
687
688 assert (elen <= MAX_LBL_SIZE);
689
690 (*pkt)[offs] = elen;
691 offs += elen + 1;
692 append_domain (*pkt, offs, dns->c->conf->domain);
693
694 (*pkt)[offs++] = 0;
695 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
696 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
697
698 pkt->len = offs;
699}
700
218struct dns_rep 701struct dns_rcv
219{ 702{
703 int seqno;
704 dns_packet *pkt; // reply packet
705 u8 data [MAXSIZE]; // actually part of the reply packet...
706 int datalen;
707
708 dns_rcv (int seqno, u8 *data, int datalen);
709 ~dns_rcv ();
220}; 710};
221 711
222static u16 dns_id; // TODO: should be per-vpn 712dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
223 713: seqno (seqno), pkt (new dns_packet), datalen (datalen)
224dns_req::dns_req (connection *c, vpn_packet *p, int &offs)
225{ 714{
226 next = 0; 715 memcpy (this->data, data, datalen);
227 retry = 0; 716}
228 717
229 pkt = new dns_packet; 718dns_rcv::~dns_rcv ()
230 719{
231 pkt->id = dns_id++; 720 delete pkt;
232 pkt->flags = DEFAULT_CLIENT_FLAGS;
233 pkt->qdcount = htons (1 * 0);
234 pkt->ancount = 0;
235 pkt->nscount = 0;
236 pkt->arcount = 0;
237
238 offs += 10000;
239
240 c->dns_sndq.push_back (this);
241} 721}
242 722
243///////////////////////////////////////////////////////////////////////////// 723/////////////////////////////////////////////////////////////////////////////
244 724
245struct dns_cfg 725dns_connection::dns_connection (connection *c)
726: c (c)
727, rcvdq (MAX_BACKLOG * 2)
728, snddq (MAX_BACKLOG)
729, tw (this, &dns_connection::time_cb)
246{ 730{
247 u8 id1, id2, id3; 731 vpn = c->vpn;
248 u8 def_ttl;
249 u8 unused1;
250 u16 max_size;
251 u8 flags1, flags2;
252};
253 732
254// reply to client-poll 733 established = false;
255void dnsv4_poll (dns_packet *pkt, int &offs)
256{
257 int dlen = MAX_PKT_SIZE - offs - 2;
258 734
259 (*pkt) [offs++] = 0; 735 rcvseq = repseq = sndseq = 0;
260 (*pkt) [offs++] = 5;
261 memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5);
262 offs += 5;
263 736
264 pkt->ancount = htons (1); 737 last_sent = last_received = 0;
265 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 738 poll_interval = 0.5; // starting here
739 send_interval = 0.5; // starting rate
740 min_latency = INITIAL_TIMEOUT;
741}
266 742
267 printf ("we have room for %d bytes\n", dlen); 743dns_connection::~dns_connection ()
744{
745 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
746 i != rcvpq.end ();
747 ++i)
748 delete *i;
749}
750
751void dns_connection::receive_rep (dns_rcv *r)
752{
753 if (r->datalen)
754 {
755 last_received = ev::ev_now ();
756 tw ();
757
758 poll_interval = send_interval;
759 }
760 else
761 {
762 poll_interval *= 1.5;
763
764 if (poll_interval > MAX_POLL_INTERVAL)
765 poll_interval = MAX_POLL_INTERVAL;
766 }
767
768 rcvpq.push_back (r);
769
770 redo:
771
772 // find next packet
773 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
774 if (SEQNO_EQ (rcvseq, (*i)->seqno))
775 {
776 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
777 // enter the packet into our input stream
778 r = *i;
779
780 // remove the oldest packet, look forward, as it's oldest first
781 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
782 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
783 {
784 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
785 delete *j;
786 rcvpq.erase (j);
787 break;
788 }
789
790 rcvseq = (rcvseq + 1) & SEQNO_MASK;
791
792 if (!rcvdq.put (r->data, r->datalen))
793 {
794 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
795 abort (); // MUST never overflow, can be caused by data corruption, TODO
796 }
797
798 while (vpn_packet *pkt = rcvdq.get ())
799 {
800 sockinfo si;
801 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
802
803 vpn->recv_vpn_packet (pkt, si);
804
805 delete pkt;
806 }
807
808 // check for further packets
809 goto redo;
810 }
268} 811}
269 812
270void 813void
814vpn::dnsv4_server (dns_packet &pkt)
815{
816 u16 flags = ntohs (pkt.flags);
817
818 int offs = 6 * 2; // skip header
819
820 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
821
822 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
823 && pkt.qdcount == htons (1))
824 {
825 char qname [MAXSIZE];
826 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
827
828 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
829 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
830
831 pkt.qdcount = htons (1);
832 pkt.ancount = 0;
833 pkt.nscount = 0; // should be self, as other nameservers reply like this
834 pkt.arcount = 0; // a record for self, as other nameservers reply like this
835
836 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
837
838 int dlen = strlen (THISNODE->domain);
839
840 if (qclass == RR_CLASS_IN
841 && qlen > dlen + 1
842 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
843 {
844 // now generate reply
845 pkt.ancount = htons (1); // one answer RR
846 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
847
848 if ((qtype == RR_TYPE_ANY
849 || qtype == RR_TYPE_TXT
850 || qtype == RR_TYPE_NULL)
851 && qlen > dlen + 1 + HDRSIZE)
852 {
853 // correct class, domain: parse
854 int client, seqno;
855 decode_header (qname, client, seqno);
856
857 u8 data[MAXSIZE];
858 int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
859
860 if (0 < client && client <= conns.size ())
861 {
862 connection *c = conns [client - 1];
863 dns_connection *dns = c->dns;
864 dns_rcv *rcv;
865
866 if (dns)
867 {
868 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
869 if (SEQNO_EQ ((*i)->seqno, seqno))
870 {
871 // already seen that request: simply reply with the cached reply
872 dns_rcv *r = *i;
873
874 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
875
876 // refresh header & id, as the retry count could have changed
877 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
878 r->pkt->id = pkt.id;
879
880 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
881
882 goto duplicate_request;
883 }
884
885 // new packet, queue
886 rcv = new dns_rcv (seqno, data, datalen);
887 dns->receive_rep (rcv);
888 }
889
890 {
891 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
892
893 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
894 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
895 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
896 pkt [offs++] = 0; pkt [offs++] = 0;
897 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
898
899 int rdlen_offs = offs += 2;
900
901 if (dns)
902 {
903 int dlen = ntohs (dns->cfg.max_size) - offs;
904
905 // bind doesn't compress well, so reduce further by one label length
906 dlen -= qlen;
907
908 // only put data into in-order sequence packets, if
909 // we receive out-of-order packets we generate empty
910 // replies
911 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
912 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
913 {
914 dns->repseq = seqno;
915
916 while (dlen > 1 && !dns->snddq.empty ())
917 {
918 int txtlen = dlen <= 255 ? dlen - 1 : 255;
919
920 if (txtlen > dns->snddq.size ())
921 txtlen = dns->snddq.size ();
922
923 pkt[offs++] = txtlen;
924 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
925 offs += txtlen;
926 dns->snddq.remove (txtlen);
927
928 dlen -= txtlen + 1;
929 }
930 }
931
932 // avoid completely empty TXT rdata
933 if (offs == rdlen_offs)
934 pkt[offs++] = 0;
935
936 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
937 }
938 else
939 {
940 // send RST
941 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
942 pkt [offs++] = CMD_IP_RST;
943 }
944
945 int rdlen = offs - rdlen_offs;
946
947 pkt [rdlen_offs - 2] = rdlen >> 8;
948 pkt [rdlen_offs - 1] = rdlen;
949
950 if (dns)
951 {
952 // now update dns_rcv copy
953 rcv->pkt->len = offs;
954 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
955 }
956 }
957
958 duplicate_request: ;
959 }
960 else
961 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
962 }
963 else if (qtype == RR_TYPE_A
964 && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
965 {
966 dns_cfg cfg;
967 cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
968 int client = ntohs (cfg.client);
969
970 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
971
972 pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
973 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
974 pkt [offs++] = 0; pkt [offs++] = 0;
975 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
976 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
977
978 slog (L_INFO, _("DNS: client %d connects"), client);
979
980 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
981 pkt [offs++] = CMD_IP_REJ;
982
983 if (0 < client && client <= conns.size ())
984 {
985 connection *c = conns [client - 1];
986
987 if (cfg.valid ())
988 {
989 pkt [offs - 1] = CMD_IP_SYN;
990
991 delete c->dns;
992 c->dns = new dns_connection (c);
993 c->dns->cfg = cfg;
994 }
995 }
996 }
997 }
998
999 pkt.len = offs;
1000 }
1001}
1002
1003void
1004vpn::dnsv4_client (dns_packet &pkt)
1005{
1006 u16 flags = ntohs (pkt.flags);
1007 int offs = 6 * 2; // skip header
1008
1009 pkt.qdcount = ntohs (pkt.qdcount);
1010 pkt.ancount = ntohs (pkt.ancount);
1011
1012 // go through our request list and find the corresponding request
1013 for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
1014 i != dns_sndpq.end ();
1015 ++i)
1016 if ((*i)->pkt->id == pkt.id)
1017 {
1018 dns_connection *dns = (*i)->dns;
1019 connection *c = dns->c;
1020 int seqno = (*i)->seqno;
1021 u8 data[MAXSIZE], *datap = data;
1022 //printf ("rcv pkt %x\n", seqno);//D
1023
1024 if ((*i)->retry)
1025 {
1026 dns->send_interval *= 1.01;
1027 if (dns->send_interval > MAX_SEND_INTERVAL)
1028 dns->send_interval = MAX_SEND_INTERVAL;
1029 }
1030 else
1031 {
1032#if 0
1033 dns->send_interval *= 0.999;
1034#endif
1035 // the latency surely puts an upper bound on
1036 // the minimum send interval
1037 double latency = ev::ev_now () - (*i)->sent;
1038
1039 if (latency < dns->min_latency)
1040 dns->min_latency = latency;
1041
1042 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1043 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1044
1045 if (dns->send_interval < conf.dns_send_interval)
1046 dns->send_interval = conf.dns_send_interval;
1047 }
1048
1049 delete *i;
1050 dns_sndpq.erase (i);
1051
1052 if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
1053 {
1054 char qname[MAXSIZE];
1055
1056 while (pkt.qdcount-- && offs < MAXSIZE - 4)
1057 {
1058 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
1059 offs += 4; // skip qtype, qclass
1060 }
1061
1062 while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
1063 {
1064 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
1065
1066 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
1067 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
1068 u32 ttl = pkt [offs++] << 24;
1069 ttl |= pkt [offs++] << 16;
1070 ttl |= pkt [offs++] << 8;
1071 ttl |= pkt [offs++];
1072 u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
1073
1074 if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
1075 {
1076 if (rdlen <= MAXSIZE - offs)
1077 {
1078 // decode bytes, finally
1079
1080 while (rdlen)
1081 {
1082 int txtlen = pkt [offs++];
1083
1084 assert (txtlen + offs < MAXSIZE - 1);
1085
1086 memcpy (datap, pkt.at (offs), txtlen);
1087 datap += txtlen; offs += txtlen;
1088
1089 rdlen -= txtlen + 1;
1090 }
1091 }
1092 }
1093 else if (qtype == RR_TYPE_A)
1094 {
1095 u8 ip [4];
1096
1097 ip [0] = pkt [offs++];
1098 ip [1] = pkt [offs++];
1099 ip [2] = pkt [offs++];
1100 ip [3] = pkt [offs++];
1101
1102 if (ip [0] == CMD_IP_1
1103 && ip [1] == CMD_IP_2
1104 && ip [2] == CMD_IP_3)
1105 {
1106 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1107
1108 if (ip [3] == CMD_IP_RST)
1109 {
1110 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1111
1112 delete dns; c->dns = 0;
1113
1114 return;
1115 }
1116 else if (ip [3] == CMD_IP_SYN)
1117 {
1118 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1119 dns->established = true;
1120 }
1121 else if (ip [3] == CMD_IP_REJ)
1122 {
1123 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1124 abort ();
1125 }
1126 else
1127 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1128 }
1129 else
1130 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1131 ip [0], ip [1], ip [2], ip [3]);
1132
1133 return;
1134 }
1135
1136 int client, rseqno;
1137 decode_header (qname, client, rseqno);
1138
1139 if (client != THISNODE->id)
1140 {
1141 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1142 datap = 0;
1143 }
1144 else if (rseqno != seqno)
1145 {
1146 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1147 datap = 0;
1148 }
1149 }
1150 }
1151
1152 // todo: pkt now used
1153 if (datap)
1154 dns->receive_rep (new dns_rcv (seqno, data, datap - data));
1155
1156 break;
1157 }
1158}
1159
1160void
271vpn::dnsv4_ev (io_watcher &w, short revents) 1161vpn::dnsv4_ev (ev::io &w, int revents)
272{ 1162{
273 if (revents & EVENT_READ) 1163 if (revents & EV_READ)
274 { 1164 {
275 dns_packet *pkt = new dns_packet; 1165 dns_packet *pkt = new dns_packet;
276 struct sockaddr_in sa; 1166 struct sockaddr_in sa;
277 socklen_t sa_len = sizeof (sa); 1167 socklen_t sa_len = sizeof (sa);
278 1168
279 int len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1169 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
280 pkt->len = len;
281 1170
282 u16 flags = ntohs (pkt->flags); 1171 if (pkt->len > 0)
283
284 if (THISNODE->dns_port)
285 { 1172 {
286 // server 1173 if (ntohs (pkt->flags) & FLAG_RESPONSE)
287 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 1174 dnsv4_client (*pkt);
288 1175 else
289 int offs = 6 * 2; // skip header
290
291 if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))
292 && pkt->qdcount == htons (1))
293 { 1176 {
294 char qname[MAXSIZE]; 1177 dnsv4_server (*pkt);
295 int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs); 1178 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
296
297 printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len,
298 pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
299
300 u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];
301 u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];
302
303 pkt->qdcount = htons (1);
304 pkt->ancount = 0;
305 pkt->nscount = 0; // should be self, as other nameservers reply like this
306 pkt->arcount = 0; // a record for self, as other nameservers reply like this
307
308 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);
309
310 int dlen = strlen (THISNODE->domain);
311
312 if (qclass == RR_CLASS_IN
313 && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
314 && qlen > dlen + 1
315 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
316 {
317 // correct class, now generate reply
318 pkt->ancount = htons (1); // one answer RR
319
320 (*pkt) [offs++] = 0xc0;
321 (*pkt) [offs++] = 6 * 2; // same as in query section
322
323 (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;
324 (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;
325
326 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0;
327 (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL
328
329 dnsv4_poll (pkt, offs);
330 printf ("correct class\n");
331 }
332 } 1179 }
333 1180
334 sendto (w.fd, &((*pkt)[0]), offs, 0, (sockaddr *)&sa, sa_len); 1181 delete pkt;
1182 }
1183 }
1184}
1185
1186bool
1187vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1188{
1189 int client = ntohl (si.host);
1190
1191 assert (0 < client && client <= conns.size ());
1192
1193 connection *c = conns [client - 1];
1194
1195 if (!c->dns)
1196 c->dns = new dns_connection (c);
1197
1198 if (c->dns->snddq.put (pkt))
1199 c->dns->tw ();
1200
1201 // always return true even if the buffer overflows
1202 return true;
1203}
1204
1205void
1206connection::dnsv4_reset_connection ()
1207{
1208 //delete dns; dns = 0; //TODO
1209}
1210
1211#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1212
1213void
1214dns_connection::time_cb (ev::timer &w, int revents)
1215{
1216 // servers have to be polled
1217 if (THISNODE->dns_port)
1218 return;
1219
1220 // check for timeouts and (re)transmit
1221 tstamp next = ev::now () + poll_interval;
1222 dns_snd *send = 0;
1223
1224 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
1225 i != vpn->dns_sndpq.end ();
1226 ++i)
1227 {
1228 dns_snd *r = *i;
1229
1230 if (r->timeout <= ev::ev_now ())
1231 {
1232 if (!send)
1233 {
1234 send = r;
1235
1236 r->retry++;
1237 r->timeout = ev::ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
1238 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev::ev_now ());//D
1239
1240 // the following code changes the query section a bit, forcing
1241 // the forwarder to generate a new request
1242 if (r->stdhdr)
1243 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1244 }
335 } 1245 }
336 else 1246 else
1247 NEXT (r->timeout);
1248 }
1249
1250 if (!send)
1251 {
1252 // generate a new packet, if wise
1253
1254 if (!established)
337 { 1255 {
338 // client 1256 if (vpn->dns_sndpq.empty ())
1257 {
1258 send = new dns_snd (this);
1259
1260 cfg.reset (THISNODE->id);
1261 send->gen_syn_req ();
1262 }
339 } 1263 }
340 } 1264 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
341} 1265 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
342
343bool
344connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
345{
346 if (dns_sndq.size () >= MAX_OUTSTANDING)
347 return false;
348
349 // split vpn packet into dns packets, add to sndq
350 for (int offs = 0; offs < pkt->len; )
351 new dns_req (this, pkt, offs);
352
353 // force transmit
354 dnsv4_cb (dnsv4_tw);
355
356 return true;
357}
358
359void
360connection::dnsv4_cb (time_watcher &w)
361{
362 // check for timeouts and (re)transmit
363 tstamp next = NOW + 60;
364
365 slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), dns_sndq.size ());
366
367 if (dns_sndq.empty ())
368 {
369 next = NOW + 1;
370 // push poll packet
371 }
372
373 for (vector<dns_req *>::iterator i = dns_sndq.begin ();
374 i != dns_sndq.end ();
375 ++i)
376 {
377 dns_req *r = *i;
378
379 if (r->next <= NOW)
380 { 1266 {
381 slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id); 1267 if (last_sent + send_interval <= ev::ev_now ())
382 r->retry++; 1268 {
383 r->next = NOW + r->retry; 1269 //printf ("sending data request etc.\n"); //D
1270 if (!snddq.empty () || last_received + 1. > ev::ev_now ())
1271 {
1272 poll_interval = send_interval;
1273 NEXT (ev::ev_now () + send_interval);
1274 }
1275
1276 send = new dns_snd (this);
1277 send->gen_stream_req (sndseq, snddq);
1278 send->timeout = ev::ev_now () + min_latency * conf.dns_timeout_factor;
1279 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev::ev_now (), min_latency, conf.dns_timeout_factor);//D
1280
1281 sndseq = (sndseq + 1) & SEQNO_MASK;
1282 }
1283 else
1284 NEXT (last_sent + send_interval);
384 } 1285 }
385 1286
386 if (r->next < next) 1287 if (send)
387 next = r->next; 1288 vpn->dns_sndpq.push_back (send);
1289 }
1290
1291 if (send)
388 } 1292 {
1293 last_sent = ev::ev_now ();
1294 sendto (vpn->dnsv4_fd,
1295 send->pkt->at (0), send->pkt->len, 0,
1296 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1297 }
389 1298
390 printf ("%f next\n", next); 1299 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
391 w.start (next); 1300 poll_interval, send_interval, next - ev::ev_now (),
1301 vpn->dns_sndpq.size (), snddq.size (),
1302 rcvpq.size ());
1303
1304 // TODO: no idea when this happens, but when next < ev::ev_now (), we have a problem
1305 // doesn't seem to happen anymore
1306 if (next < ev::ev_now () + 0.001)
1307 next = ev::ev_now () + 0.1;
1308
1309 w.start (next - ev::ev_now ());
392} 1310}
393 1311
394#endif 1312#endif
395 1313

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