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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.15 by pcg, Fri Mar 4 10:15:45 2005 UTC vs.
Revision 1.40 by pcg, Sat Jul 9 20:29:29 2005 UTC

… …
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details. 15 GNU General 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
18 along with gvpe; if not, write to the Free Software 18 along with gvpe; if not, write to the Free Software
19 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
20*/ 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.
21 25
22#include "config.h" 26#include "config.h"
23 27
24#if ENABLE_DNS 28#if ENABLE_DNS
25 29
26// dns processing is EXTREMELY ugly. For obvious(?) reasons. 30// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27// it's a hack, use only in emergency situations please. 31// it's a hack, use only in emergency situations please.
28 32
29#include <cstring> 33#include <cstring>
34#include <cassert>
30 35
31#include <sys/types.h> 36#include <sys/types.h>
32#include <sys/socket.h> 37#include <sys/socket.h>
33#include <sys/wait.h> 38#include <sys/wait.h>
34#include <sys/uio.h> 39#include <sys/uio.h>
… …
43 48
44#include "netcompat.h" 49#include "netcompat.h"
45 50
46#include "vpn.h" 51#include "vpn.h"
47 52
48#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data
49#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data 53#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
50#define ACTIVITY_INTERVAL 5. 54#define ACTIVITY_INTERVAL 5.
51 55
52#define INITIAL_TIMEOUT 1. // retry timeouts 56#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn 57#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
54 58
55#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
56#define MAX_SEND_INTERVAL 0.5 // optimistic? 59#define MAX_SEND_INTERVAL 2. // optimistic?
57 60
58#define MAX_OUTSTANDING 40 // max. outstanding requests
59#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 61#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
60#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE 62#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
61 63
62#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well 64#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
63// 240 leaves about 4 bytes of server reply data 65// 240 leaves about 4 bytes of server reply data
64// every two request bytes less give room for one reply byte 66// every request byte less give room for two reply bytes
65 67
66#define SEQNO_MASK 0xffff 68#define SEQNO_MASK 0x3fff
67#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 69#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
68 70
69#define MAX_LBL_SIZE 63 71#define MAX_LBL_SIZE 63
70#define MAX_PKT_SIZE 512 72#define MAX_PKT_SIZE 512
71 73
… …
264static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 266static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
265 267
266///////////////////////////////////////////////////////////////////////////// 268/////////////////////////////////////////////////////////////////////////////
267 269
268#define HDRSIZE 6 270#define HDRSIZE 6
269 271
270inline void encode_header (char *data, int clientid, int seqno) 272inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
271{ 273{
272 u8 hdr[3] = { clientid, seqno >> 8, seqno }; 274 seqno &= SEQNO_MASK;
275
276 u8 hdr[3] = {
277 clientid,
278 (seqno >> 8) | (retry << 6),
279 seqno,
280 };
273 281
274 assert (clientid < 256); 282 assert (clientid < 256);
275 283
276 cdc26.encode (data, hdr, 3); 284 cdc26.encode (data, hdr, 3);
277} 285}
… …
281 u8 hdr[3]; 289 u8 hdr[3];
282 290
283 cdc26.decode (hdr, data, HDRSIZE); 291 cdc26.decode (hdr, data, HDRSIZE);
284 292
285 clientid = hdr[0]; 293 clientid = hdr[0];
286 seqno = (hdr[1] << 8) | hdr[2]; 294 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
287} 295}
288 296
289///////////////////////////////////////////////////////////////////////////// 297/////////////////////////////////////////////////////////////////////////////
290 298
291struct byte_stream 299struct byte_stream
… …
320} 328}
321 329
322void byte_stream::remove (int count) 330void byte_stream::remove (int count)
323{ 331{
324 if (count > fill) 332 if (count > fill)
325 abort (); 333 assert (count <= fill);
326 334
327 memmove (data, data + count, fill -= count); 335 memmove (data, data + count, fill -= count);
328} 336}
329 337
330bool byte_stream::put (u8 *data, unsigned int datalen) 338bool byte_stream::put (u8 *data, unsigned int datalen)
… …
350 return true; 358 return true;
351} 359}
352 360
353vpn_packet *byte_stream::get () 361vpn_packet *byte_stream::get ()
354{ 362{
363 unsigned int len;
364
365 for (;;)
366 {
355 unsigned int len = (data [0] << 8) | data [1]; 367 len = (data [0] << 8) | data [1];
356 368
357 if (len > MAXSIZE && fill >= 2) 369 if (len <= MAXSIZE || fill < 2)
358 abort (); // TODO handle this gracefully, connection reset 370 break;
359 371
372 // TODO: handle this better than skipping, e.g. by reset
373 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
374 remove (1);
375 }
376
360 if (fill < len + 2) 377 if (fill < len + 2)
361 return 0; 378 return 0;
362 379
363 vpn_packet *pkt = new vpn_packet; 380 vpn_packet *pkt = new vpn_packet;
364 381
… …
393struct dns_cfg 410struct dns_cfg
394{ 411{
395 static int next_uid; 412 static int next_uid;
396 413
397 u8 id1, id2, id3, id4; 414 u8 id1, id2, id3, id4;
415
398 u8 version; 416 u8 version;
417 u8 flags;
399 u8 rrtype; 418 u8 rrtype;
400 u8 flags;
401 u8 def_ttl; 419 u8 def_ttl;
402 u8 rcv_cdc; 420
403 u8 snd_cdc;
404 u16 max_size;
405 u16 client; 421 u16 client;
406 u16 uid; // to make request unique 422 u16 uid; // to make request unique
407 423
408 u8 reserved[8]; 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;
409 433
410 void reset (int clientid); 434 void reset (int clientid);
411 bool valid (); 435 bool valid ();
412}; 436};
413 437
… …
423 version = 1; 447 version = 1;
424 448
425 rrtype = RR_TYPE_TXT; 449 rrtype = RR_TYPE_TXT;
426 flags = 0; 450 flags = 0;
427 def_ttl = 0; 451 def_ttl = 0;
452 seq_cdc = 26;
453 req_cdc = 62;
428 rcv_cdc = 0; 454 rep_cdc = 0;
429 snd_cdc = 62;
430 max_size = ntohs (MAX_PKT_SIZE); 455 max_size = htons (MAX_PKT_SIZE);
431 client = ntohs (clientid); 456 client = htons (clientid);
432 uid = next_uid++; 457 uid = next_uid++;
458 delay = 0;
433 459
434 memset (reserved, 0, 8); 460 r3 = r4 = 0;
461 r4 = r5 = r6 = r7 = 0;
435} 462}
436 463
437bool dns_cfg::valid () 464bool dns_cfg::valid ()
438{ 465{
466 // although the protocol itself allows for some configurability,
467 // only the following encoding/decoding settings are implemented.
439 return id1 == 'G' 468 return id1 == 'G'
440 && id2 == 'V' 469 && id2 == 'V'
441 && id3 == 'P' 470 && id3 == 'P'
442 && id4 == 'E' 471 && id4 == 'E'
472 && seq_cdc == 26
473 && req_cdc == 62
474 && rep_cdc == 0
443 && version == 1 475 && version == 1;
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62
447 && max_size == ntohs (MAX_PKT_SIZE);
448} 476}
449 477
450struct dns_packet : net_packet 478struct dns_packet : net_packet
451{ 479{
452 u16 id; 480 u16 id;
453 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
454 u16 qdcount, ancount, nscount, arcount; 482 u16 qdcount, ancount, nscount, arcount;
455 483
456 u8 data[MAXSIZE - 6 * 2]; 484 u8 data [MAXSIZE - 6 * 2];
457 485
458 int decode_label (char *data, int size, int &offs); 486 int decode_label (char *data, int size, int &offs);
459}; 487};
460 488
461int dns_packet::decode_label (char *data, int size, int &offs) 489int dns_packet::decode_label (char *data, int size, int &offs)
… …
492 return data - orig; 520 return data - orig;
493} 521}
494 522
495///////////////////////////////////////////////////////////////////////////// 523/////////////////////////////////////////////////////////////////////////////
496 524
497struct dns_snd
498{
499 dns_packet *pkt;
500 tstamp timeout, sent;
501 int retry;
502 struct dns_connection *dns;
503 int seqno;
504
505 void gen_stream_req (int seqno, byte_stream &stream);
506 void gen_syn_req (const dns_cfg &cfg);
507
508 dns_snd (dns_connection *dns);
509 ~dns_snd ();
510};
511
512static u16 dns_id = 12098; // TODO: should be per-vpn 525static u16 dns_id = 0; // TODO: should be per-vpn
513 526
514static u16 next_id () 527static u16 next_id ()
515{ 528{
529 if (!dns_id)
530 dns_id = time (0);
531
516 // the simplest lsfr with periodicity 65535 i could find 532 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 533 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 534 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 535 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 536 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 537 ^ (dns_id >> 15)) & 1);
522 538
523 return dns_id; 539 return dns_id;
524} 540}
525 541
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 (time_watcher &w); time_watcher tw;
565 void receive_rep (dns_rcv *r);
566
567 dns_connection (connection *c);
568 ~dns_connection ();
569};
570
571struct dns_snd
572{
573 dns_packet *pkt;
574 tstamp timeout, sent;
575 int retry;
576 struct dns_connection *dns;
577 int seqno;
578 bool stdhdr;
579
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 ();
585};
586
526dns_snd::dns_snd (dns_connection *dns) 587dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 588: dns (dns)
528{ 589{
529 timeout = 0; 590 timeout = 0;
530 retry = 0; 591 retry = 0;
531 seqno = 0; 592 seqno = 0;
532 sent = NOW; 593 sent = NOW;
594 stdhdr = false;
533 595
534 pkt = new dns_packet; 596 pkt = new dns_packet;
535 597
536 pkt->id = next_id (); 598 pkt->id = next_id ();
537} 599}
… …
564 } 626 }
565} 627}
566 628
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 629void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 630{
631 stdhdr = true;
569 this->seqno = seqno; 632 this->seqno = seqno;
570 633
571 timeout = NOW + INITIAL_TIMEOUT; 634 timeout = NOW + INITIAL_TIMEOUT;
572 635
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 636 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 637 pkt->qdcount = htons (1);
575 638
576 int offs = 6*2; 639 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 640 int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
578 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, 641 // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
579 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 642 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
580 643
581 char enc[256], *encp = enc; 644 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 645 encode_header (enc, THISNODE->id, seqno);
… …
600 encp += lbllen; 663 encp += lbllen;
601 664
602 enclen -= lbllen; 665 enclen -= lbllen;
603 } 666 }
604 667
605 append_domain (*pkt, offs, THISNODE->domain); 668 append_domain (*pkt, offs, dns->c->conf->domain);
606 669
607 (*pkt)[offs++] = 0; 670 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 671 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 672 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 673
611 pkt->len = offs; 674 pkt->len = offs;
612} 675}
613 676
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 677void dns_snd::gen_syn_req ()
615{ 678{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 679 timeout = NOW + INITIAL_SYN_TIMEOUT;
617 680
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 681 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 682 pkt->qdcount = htons (1);
620 683
621 int offs = 6*2; 684 int offs = 6 * 2;
622 685
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 686 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 687
625 assert (elen <= MAX_LBL_SIZE); 688 assert (elen <= MAX_LBL_SIZE);
626 689
627 (*pkt)[offs] = elen; 690 (*pkt)[offs] = elen;
628 offs += elen + 1; 691 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 692 append_domain (*pkt, offs, dns->c->conf->domain);
630 693
631 (*pkt)[offs++] = 0; 694 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 695 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 696 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 697
… …
657 delete pkt; 720 delete pkt;
658} 721}
659 722
660///////////////////////////////////////////////////////////////////////////// 723/////////////////////////////////////////////////////////////////////////////
661 724
662struct dns_connection
663{
664 connection *c;
665 struct vpn *vpn;
666
667 dns_cfg cfg;
668
669 bool established;
670
671 tstamp last_received;
672 tstamp last_sent;
673 double poll_interval, send_interval;
674
675 vector<dns_rcv *> rcvpq;
676
677 byte_stream rcvdq; int rcvseq;
678 byte_stream snddq; int sndseq;
679
680 void time_cb (time_watcher &w); time_watcher tw;
681 void receive_rep (dns_rcv *r);
682
683 dns_connection (connection *c);
684 ~dns_connection ();
685};
686
687dns_connection::dns_connection (connection *c) 725dns_connection::dns_connection (connection *c)
688: c (c) 726: c (c)
689, rcvdq (MAX_BACKLOG * 2) 727, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 728, snddq (MAX_BACKLOG)
691, tw (this, &dns_connection::time_cb) 729, tw (this, &dns_connection::time_cb)
692{ 730{
693 vpn = c->vpn; 731 vpn = c->vpn;
694 732
695 established = false; 733 established = false;
696 734
697 rcvseq = sndseq = 0; 735 rcvseq = repseq = sndseq = 0;
698 736
699 last_sent = last_received = 0; 737 last_sent = last_received = 0;
700 poll_interval = MIN_POLL_INTERVAL; 738 poll_interval = 0.5; // starting here
701 send_interval = 0.2; // starting rate 739 send_interval = 0.5; // starting rate
740 min_latency = INITIAL_TIMEOUT;
702} 741}
703 742
704dns_connection::~dns_connection () 743dns_connection::~dns_connection ()
705{ 744{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 745 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
… …
718 757
719 poll_interval = send_interval; 758 poll_interval = send_interval;
720 } 759 }
721 else 760 else
722 { 761 {
723 poll_interval *= 1.1; 762 poll_interval *= 1.5;
763
724 if (poll_interval > MAX_POLL_INTERVAL) 764 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL; 765 poll_interval = MAX_POLL_INTERVAL;
726 } 766 }
727 767
728 rcvpq.push_back (r); 768 rcvpq.push_back (r);
… …
746 } 786 }
747 787
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 788 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 789
750 if (!rcvdq.put (r->data, r->datalen)) 790 if (!rcvdq.put (r->data, r->datalen))
791 {
792 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
751 abort (); // MUST never overflow, can be caused by data corruption, TODO 793 abort (); // MUST never overflow, can be caused by data corruption, TODO
794 }
752 795
753 while (vpn_packet *pkt = rcvdq.get ()) 796 while (vpn_packet *pkt = rcvdq.get ())
754 { 797 {
755 sockinfo si; 798 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 799 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
757 800
758 vpn->recv_vpn_packet (pkt, si); 801 vpn->recv_vpn_packet (pkt, si);
759 802
760 delete pkt; 803 delete pkt;
761 } 804 }
… …
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 818 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 819
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 820 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 821 && pkt.qdcount == htons (1))
779 { 822 {
780 char qname[MAXSIZE]; 823 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 824 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 825
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 826 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 827 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 828
786 pkt.qdcount = htons (1); 829 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 830 pkt.ancount = 0;
788 pkt.nscount = 0; // should be self, as other nameservers reply like this 831 pkt.nscount = 0; // should be self, as other nameservers reply like this
789 pkt.arcount = 0; // a record for self, as other nameservers reply like this 832 pkt.arcount = 0; // a record for self, as other nameservers reply like this
790 833
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 834 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 835
793 int dlen = strlen (THISNODE->domain); 836 int dlen = strlen (THISNODE->domain);
794 837
795 if (qclass == RR_CLASS_IN 838 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 839 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 840 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 841 {
799 // now generate reply 842 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 843 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 844 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 845
… …
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 867 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 868 {
826 // already seen that request: simply reply with the cached reply 869 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 870 dns_rcv *r = *i;
828 871
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 872 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
873
874 // refresh header & id, as the retry count could have changed
875 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
876 r->pkt->id = pkt.id;
830 877
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 878 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 879
833 goto duplicate_request; 880 goto duplicate_request;
834 } 881 }
835 882
836 // new packet, queue 883 // new packet, queue
837 rcv = new dns_rcv (seqno, data, datalen); 884 rcv = new dns_rcv (seqno, data, datalen);
838 dns->receive_rep (rcv); 885 dns->receive_rep (rcv);
839 } 886 }
840 887
888 {
841 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 889 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
842 890
843 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 891 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
844 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type 892 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
845 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 893 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
846 pkt [offs++] = 0; pkt [offs++] = 0; 894 pkt [offs++] = 0; pkt [offs++] = 0;
847 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 895 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
848 896
849 int rdlen_offs = offs += 2; 897 int rdlen_offs = offs += 2;
850 898
899 if (dns)
900 {
851 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 901 int dlen = ntohs (dns->cfg.max_size) - offs;
902
852 // bind doesn't compress well, so reduce further by one label length 903 // bind doesn't compress well, so reduce further by one label length
853 dlen -= qlen; 904 dlen -= qlen;
854 905
855 if (dns) 906 // only put data into in-order sequence packets, if
856 { 907 // we receive out-of-order packets we generate empty
857 while (dlen > 1 && !dns->snddq.empty ()) 908 // replies
909 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
910 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
858 { 911 {
912 dns->repseq = seqno;
913
914 while (dlen > 1 && !dns->snddq.empty ())
915 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 916 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 917
861 if (txtlen > dns->snddq.size ()) 918 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 919 txtlen = dns->snddq.size ();
863 920
864 pkt[offs++] = txtlen; 921 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 922 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 923 offs += txtlen;
867 dns->snddq.remove (txtlen); 924 dns->snddq.remove (txtlen);
868 925
869 dlen -= txtlen + 1; 926 dlen -= txtlen + 1;
927 }
870 } 928 }
871 929
872 // avoid empty TXT rdata 930 // avoid completely empty TXT rdata
873 if (offs == rdlen_offs) 931 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 932 pkt[offs++] = 0;
875 933
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 934 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 935 }
878 else 936 else
879 { 937 {
880 // send RST 938 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 939 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 940 pkt [offs++] = CMD_IP_RST;
883 } 941 }
884 942
885 int rdlen = offs - rdlen_offs; 943 int rdlen = offs - rdlen_offs;
886 944
887 pkt [rdlen_offs - 2] = rdlen >> 8; 945 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 946 pkt [rdlen_offs - 1] = rdlen;
889 947
890 if (dns) 948 if (dns)
891 { 949 {
892 // now update dns_rcv copy 950 // now update dns_rcv copy
893 rcv->pkt->len = offs; 951 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 952 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 953 }
954 }
896 955
897 duplicate_request: ; 956 duplicate_request: ;
898 } 957 }
899 else 958 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 959 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
… …
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 971 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 972 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 973 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 974 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 975
917 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client); 976 slog (L_INFO, _("DNS: client %d connects"), client);
918 977
919 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 978 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 979 pkt [offs++] = CMD_IP_REJ;
921 980
922 if (0 < client && client <= conns.size ()) 981 if (0 < client && client <= conns.size ())
… …
959 int seqno = (*i)->seqno; 1018 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1019 u8 data[MAXSIZE], *datap = data;
961 1020
962 if ((*i)->retry) 1021 if ((*i)->retry)
963 { 1022 {
964 dns->send_interval *= 1.001; 1023 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1024 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1025 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1026 }
968 else 1027 else
969 { 1028 {
970#if 1 1029#if 0
971 dns->send_interval *= 0.9999; 1030 dns->send_interval *= 0.999;
972#endif 1031#endif
973 if (dns->send_interval < MIN_SEND_INTERVAL)
974 dns->send_interval = MIN_SEND_INTERVAL;
975
976 // the latency surely puts an upper bound on 1032 // the latency surely puts an upper bound on
977 // the minimum send interval 1033 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1034 double latency = NOW - (*i)->sent;
979 1035
980 if (dns->send_interval > latency) 1036 if (latency < dns->min_latency)
981 dns->send_interval = latency; 1037 dns->min_latency = latency;
1038
1039 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1040 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1041
1042 if (dns->send_interval < conf.dns_send_interval)
1043 dns->send_interval = conf.dns_send_interval;
982 } 1044 }
983 1045
984 delete *i; 1046 delete *i;
985 dns_sndpq.erase (i); 1047 dns_sndpq.erase (i);
986 1048
… …
1036 1098
1037 if (ip [0] == CMD_IP_1 1099 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1100 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1101 && ip [2] == CMD_IP_3)
1040 { 1102 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1103 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1104
1043 if (ip [3] == CMD_IP_RST) 1105 if (ip [3] == CMD_IP_RST)
1044 { 1106 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1107 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1046 1108
1047 delete dns; c->dns = 0; 1109 delete dns; c->dns = 0;
1048 1110
1049 return; 1111 return;
1050 } 1112 }
1051 else if (ip [3] == CMD_IP_SYN) 1113 else if (ip [3] == CMD_IP_SYN)
1052 { 1114 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1115 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 1116 dns->established = true;
1055 } 1117 }
1056 else if (ip [3] == CMD_IP_REJ) 1118 else if (ip [3] == CMD_IP_REJ)
1057 { 1119 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1120 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1059 abort (); 1121 abort ();
1060 } 1122 }
1061 else 1123 else
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1124 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1063 } 1125 }
1064 else 1126 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1127 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1128 ip [0], ip [1], ip [2], ip [3]);
1067 1129
1068 return; 1130 return;
1069 } 1131 }
1070 1132
1071 int client, rseqno; 1133 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1134 decode_header (qname, client, rseqno);
1073 1135
1074 if (client != THISNODE->id) 1136 if (client != THISNODE->id)
1075 { 1137 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1138 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1139 datap = 0;
1078 } 1140 }
1079 else if (rseqno != seqno) 1141 else if (rseqno != seqno)
1080 { 1142 {
1081 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1143 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1082 datap = 0; 1144 datap = 0;
1083 } 1145 }
1084 } 1146 }
1085 } 1147 }
1086 1148
… …
1103 1165
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1166 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1167
1106 if (pkt->len > 0) 1168 if (pkt->len > 0)
1107 { 1169 {
1108 if (THISNODE->dns_port) 1170 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1171 dnsv4_client (*pkt);
1172 else
1109 { 1173 {
1110 dnsv4_server (*pkt); 1174 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1175 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1176 }
1113 else
1114 dnsv4_client (*pkt);
1115 1177
1116 delete pkt; 1178 delete pkt;
1117 } 1179 }
1118 } 1180 }
1119} 1181}
1120 1182
1121bool 1183bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1184vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1185{
1186 int client = ntohl (si.host);
1187
1188 assert (0 < client && client <= conns.size ());
1189
1190 connection *c = conns [client - 1];
1191
1124 if (!dns) 1192 if (!c->dns)
1125 dns = new dns_connection (this); 1193 c->dns = new dns_connection (c);
1126 1194
1127 if (!dns->snddq.put (pkt)) 1195 if (c->dns->snddq.put (pkt))
1128 return false;
1129
1130 dns->tw.trigger (); 1196 c->dns->tw.trigger ();
1131 1197
1198 // always return true even if the buffer overflows
1132 return true; 1199 return true;
1133} 1200}
1134 1201
1135void 1202void
1136connection::dnsv4_reset_connection () 1203connection::dnsv4_reset_connection ()
… …
1162 if (!send) 1229 if (!send)
1163 { 1230 {
1164 send = r; 1231 send = r;
1165 1232
1166 r->retry++; 1233 r->retry++;
1167 r->timeout = NOW + r->retry; 1234 r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
1235
1236 // the following code changes the query section a bit, forcing
1237 // the forwarder to generate a new request
1238 if (r->stdhdr)
1239 {
1240 //printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
1241 //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1242 }
1168 } 1243 }
1169 } 1244 }
1170 else 1245 else
1171 NEXT (r->timeout); 1246 NEXT (r->timeout);
1172 } 1247 }
1173 1248
1174 if (last_sent + send_interval <= NOW)
1175 {
1176 if (!send) 1249 if (!send)
1250 {
1251 // generate a new packet, if wise
1252
1253 if (!established)
1177 { 1254 {
1178 // generate a new packet, if wise
1179
1180 if (!established)
1181 {
1182 if (vpn->dns_sndpq.empty ()) 1255 if (vpn->dns_sndpq.empty ())
1183 {
1184 send = new dns_snd (this);
1185
1186 cfg.reset (THISNODE->id);
1187 send->gen_syn_req (cfg);
1188 }
1189 }
1190 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING)
1191 { 1256 {
1192 send = new dns_snd (this); 1257 send = new dns_snd (this);
1258
1259 cfg.reset (THISNODE->id);
1260 send->gen_syn_req ();
1261 }
1262 }
1263 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1264 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1265 {
1266 if (last_sent + send_interval <= NOW)
1267 {
1268 //printf ("sending data request etc.\n"); //D
1269 if (!snddq.empty () || last_received + 1. > NOW)
1270 {
1271 poll_interval = send_interval;
1272 NEXT (NOW + send_interval);
1273 }
1274
1275 send = new dns_snd (this);
1193 send->gen_stream_req (sndseq, snddq); 1276 send->gen_stream_req (sndseq, snddq);
1277 send->timeout = NOW + min_latency * conf.dns_timeout_factor;
1194 1278
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1279 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1280 }
1197 1281 else
1198 if (send) 1282 NEXT (last_sent + send_interval);
1199 vpn->dns_sndpq.push_back (send);
1200 } 1283 }
1201 1284
1202 if (send) 1285 if (send)
1203 { 1286 vpn->dns_sndpq.push_back (send);
1287 }
1288
1289 if (send)
1290 {
1204 last_sent = NOW; 1291 last_sent = NOW;
1205 sendto (vpn->dnsv4_fd, 1292 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1293 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1294 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1295 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1296
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1297 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1298 poll_interval, send_interval, next - NOW,
1215 vpn->dns_sndpq.size (), snddq.size ()); 1299 vpn->dns_sndpq.size (), snddq.size (),
1300 rcvpq.size ());
1216 1301
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem 1302 // TODO: no idea when this happens, but when next < NOW, we have a problem
1303 // doesn't seem to happen anymore
1218 if (next < NOW + 0.0001) 1304 if (next < NOW + 0.001)
1219 next = NOW + 0.1; 1305 next = NOW + 0.1;
1220 1306
1221 w.start (next); 1307 w.start (next);
1222} 1308}
1223 1309

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