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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 1.28 by pcg, Sun Mar 13 12:33:34 2005 UTC

25 25
26// dns processing is EXTREMELY ugly. For obvious(?) reasons. 26// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27// it's a hack, use only in emergency situations please. 27// it's a hack, use only in emergency situations please.
28 28
29#include <cstring> 29#include <cstring>
30#include <cassert>
30 31
31#include <sys/types.h> 32#include <sys/types.h>
32#include <sys/socket.h> 33#include <sys/socket.h>
33#include <sys/wait.h> 34#include <sys/wait.h>
34#include <sys/uio.h> 35#include <sys/uio.h>
47 48
48#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data 49#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 50#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data
50#define ACTIVITY_INTERVAL 5. 51#define ACTIVITY_INTERVAL 5.
51 52
52#define INITIAL_TIMEOUT 1. // retry timeouts 53#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn 54#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
54 55
55#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests 56#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
56#define MAX_SEND_INTERVAL 0.5 // optimistic? 57#define MAX_SEND_INTERVAL 2. // optimistic?
57 58
59#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
58#define MAX_OUTSTANDING 40 // max. outstanding requests 60#define MAX_OUTSTANDING 100 // 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 (100*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 two request bytes less give room for one reply byte
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 r2, r3, r4;
430
431 u8 r5, r6, r7, r8;
409 432
410 void reset (int clientid); 433 void reset (int clientid);
411 bool valid (); 434 bool valid ();
412}; 435};
413 436
423 version = 1; 446 version = 1;
424 447
425 rrtype = RR_TYPE_TXT; 448 rrtype = RR_TYPE_TXT;
426 flags = 0; 449 flags = 0;
427 def_ttl = 0; 450 def_ttl = 0;
451 seq_cdc = 26;
452 req_cdc = 62;
428 rcv_cdc = 0; 453 rep_cdc = 0;
429 snd_cdc = 62;
430 max_size = ntohs (MAX_PKT_SIZE); 454 max_size = htons (MAX_PKT_SIZE);
431 client = ntohs (clientid); 455 client = htons (clientid);
432 uid = next_uid++; 456 uid = next_uid++;
433 457
434 memset (reserved, 0, 8); 458 r2 = r3 = r4 = 0;
459 r4 = r5 = r6 = r7 = 0;
435} 460}
436 461
437bool dns_cfg::valid () 462bool dns_cfg::valid ()
438{ 463{
439 return id1 == 'G' 464 return id1 == 'G'
440 && id2 == 'V' 465 && id2 == 'V'
441 && id3 == 'P' 466 && id3 == 'P'
442 && id4 == 'E' 467 && id4 == 'E'
468 && seq_cdc == 26
469 && req_cdc == 62
470 && rep_cdc == 0
443 && version == 1 471 && version == 1;
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62
447 && max_size == ntohs (MAX_PKT_SIZE);
448} 472}
449 473
450struct dns_packet : net_packet 474struct dns_packet : net_packet
451{ 475{
452 u16 id; 476 u16 id;
453 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 477 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
454 u16 qdcount, ancount, nscount, arcount; 478 u16 qdcount, ancount, nscount, arcount;
455 479
456 u8 data[MAXSIZE - 6 * 2]; 480 u8 data [MAXSIZE - 6 * 2];
457 481
458 int decode_label (char *data, int size, int &offs); 482 int decode_label (char *data, int size, int &offs);
459}; 483};
460 484
461int dns_packet::decode_label (char *data, int size, int &offs) 485int dns_packet::decode_label (char *data, int size, int &offs)
492 return data - orig; 516 return data - orig;
493} 517}
494 518
495///////////////////////////////////////////////////////////////////////////// 519/////////////////////////////////////////////////////////////////////////////
496 520
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 521static u16 dns_id = 0; // TODO: should be per-vpn
513 522
514static u16 next_id () 523static u16 next_id ()
515{ 524{
525 if (!dns_id)
526 dns_id = time (0);
527
516 // the simplest lsfr with periodicity 65535 i could find 528 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 529 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 530 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 531 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 532 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 533 ^ (dns_id >> 15)) & 1);
522 534
523 return dns_id; 535 return dns_id;
524} 536}
525 537
538struct dns_rcv;
539struct dns_snd;
540
541struct dns_connection
542{
543 connection *c;
544 struct vpn *vpn;
545
546 dns_cfg cfg;
547
548 bool established;
549
550 tstamp last_received;
551 tstamp last_sent;
552 double min_latency;
553 double poll_interval, send_interval;
554
555 vector<dns_rcv *> rcvpq;
556
557 byte_stream rcvdq; int rcvseq;
558 byte_stream snddq; int sndseq;
559
560 void time_cb (time_watcher &w); time_watcher tw;
561 void receive_rep (dns_rcv *r);
562
563 dns_connection (connection *c);
564 ~dns_connection ();
565};
566
567struct dns_snd
568{
569 dns_packet *pkt;
570 tstamp timeout, sent;
571 int retry;
572 struct dns_connection *dns;
573 int seqno;
574 bool stdhdr;
575
576 void gen_stream_req (int seqno, byte_stream &stream);
577 void gen_syn_req ();
578
579 dns_snd (dns_connection *dns);
580 ~dns_snd ();
581};
582
526dns_snd::dns_snd (dns_connection *dns) 583dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 584: dns (dns)
528{ 585{
529 timeout = 0; 586 timeout = 0;
530 retry = 0; 587 retry = 0;
531 seqno = 0; 588 seqno = 0;
532 sent = NOW; 589 sent = NOW;
590 stdhdr = false;
533 591
534 pkt = new dns_packet; 592 pkt = new dns_packet;
535 593
536 pkt->id = next_id (); 594 pkt->id = next_id ();
537} 595}
564 } 622 }
565} 623}
566 624
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 625void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 626{
627 stdhdr = true;
569 this->seqno = seqno; 628 this->seqno = seqno;
570 629
571 timeout = NOW + INITIAL_TIMEOUT; 630 timeout = NOW + INITIAL_TIMEOUT;
572 631
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 632 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 633 pkt->qdcount = htons (1);
575 634
576 int offs = 6*2; 635 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 636 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, 637 // 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 638 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
580 639
581 char enc[256], *encp = enc; 640 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 641 encode_header (enc, THISNODE->id, seqno);
600 encp += lbllen; 659 encp += lbllen;
601 660
602 enclen -= lbllen; 661 enclen -= lbllen;
603 } 662 }
604 663
605 append_domain (*pkt, offs, THISNODE->domain); 664 append_domain (*pkt, offs, dns->c->conf->domain);
606 665
607 (*pkt)[offs++] = 0; 666 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 667 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 668 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 669
611 pkt->len = offs; 670 pkt->len = offs;
612} 671}
613 672
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 673void dns_snd::gen_syn_req ()
615{ 674{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 675 timeout = NOW + INITIAL_SYN_TIMEOUT;
617 676
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 677 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 678 pkt->qdcount = htons (1);
620 679
621 int offs = 6*2; 680 int offs = 6 * 2;
622 681
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 682 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 683
625 assert (elen <= MAX_LBL_SIZE); 684 assert (elen <= MAX_LBL_SIZE);
626 685
627 (*pkt)[offs] = elen; 686 (*pkt)[offs] = elen;
628 offs += elen + 1; 687 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 688 append_domain (*pkt, offs, dns->c->conf->domain);
630 689
631 (*pkt)[offs++] = 0; 690 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 691 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 692 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 693
657 delete pkt; 716 delete pkt;
658} 717}
659 718
660///////////////////////////////////////////////////////////////////////////// 719/////////////////////////////////////////////////////////////////////////////
661 720
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) 721dns_connection::dns_connection (connection *c)
688: c (c) 722: c (c)
689, rcvdq (MAX_BACKLOG * 2) 723, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 724, snddq (MAX_BACKLOG * 2)
691, tw (this, &dns_connection::time_cb) 725, tw (this, &dns_connection::time_cb)
696 730
697 rcvseq = sndseq = 0; 731 rcvseq = sndseq = 0;
698 732
699 last_sent = last_received = 0; 733 last_sent = last_received = 0;
700 poll_interval = MIN_POLL_INTERVAL; 734 poll_interval = MIN_POLL_INTERVAL;
701 send_interval = 0.2; // starting rate 735 send_interval = 0.5; // starting rate
736 min_latency = INITIAL_TIMEOUT;
702} 737}
703 738
704dns_connection::~dns_connection () 739dns_connection::~dns_connection ()
705{ 740{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 741 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
718 753
719 poll_interval = send_interval; 754 poll_interval = send_interval;
720 } 755 }
721 else 756 else
722 { 757 {
723 poll_interval *= 1.1; 758 poll_interval *= 1.5;
759
724 if (poll_interval > MAX_POLL_INTERVAL) 760 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL; 761 poll_interval = MAX_POLL_INTERVAL;
726 } 762 }
727 763
728 rcvpq.push_back (r); 764 rcvpq.push_back (r);
746 } 782 }
747 783
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 784 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 785
750 if (!rcvdq.put (r->data, r->datalen)) 786 if (!rcvdq.put (r->data, r->datalen))
787 {
788 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
751 abort (); // MUST never overflow, can be caused by data corruption, TODO 789 abort (); // MUST never overflow, can be caused by data corruption, TODO
790 }
752 791
753 while (vpn_packet *pkt = rcvdq.get ()) 792 while (vpn_packet *pkt = rcvdq.get ())
754 { 793 {
755 sockinfo si; 794 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 795 si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
757 796
758 vpn->recv_vpn_packet (pkt, si); 797 vpn->recv_vpn_packet (pkt, si);
759 798
760 delete pkt; 799 delete pkt;
761 } 800 }
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 814 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 815
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 816 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 817 && pkt.qdcount == htons (1))
779 { 818 {
780 char qname[MAXSIZE]; 819 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 820 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 821
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 822 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 823 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 824
786 pkt.qdcount = htons (1); 825 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 826 pkt.ancount = 0;
788 pkt.nscount = 0; // should be self, as other nameservers reply like this 827 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 828 pkt.arcount = 0; // a record for self, as other nameservers reply like this
790 829
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 830 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 831
793 int dlen = strlen (THISNODE->domain); 832 int dlen = strlen (THISNODE->domain);
794 833
795 if (qclass == RR_CLASS_IN 834 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 835 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 836 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 837 {
799 // now generate reply 838 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 839 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 840 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 841
815 if (0 < client && client <= conns.size ()) 854 if (0 < client && client <= conns.size ())
816 { 855 {
817 connection *c = conns [client - 1]; 856 connection *c = conns [client - 1];
818 dns_connection *dns = c->dns; 857 dns_connection *dns = c->dns;
819 dns_rcv *rcv; 858 dns_rcv *rcv;
859 bool in_seq;
820 860
821 if (dns) 861 if (dns)
822 { 862 {
823 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 863 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 864 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 865 {
826 // already seen that request: simply reply with the cached reply 866 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 867 dns_rcv *r = *i;
828 868
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 869 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
870
871 // refresh header & id, as the retry count could have changed
872 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
873 r->pkt->id = pkt.id;
830 874
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 875 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 876
833 goto duplicate_request; 877 goto duplicate_request;
834 } 878 }
879
880 in_seq = dns->rcvseq == seqno;
835 881
836 // new packet, queue 882 // new packet, queue
837 rcv = new dns_rcv (seqno, data, datalen); 883 rcv = new dns_rcv (seqno, data, datalen);
838 dns->receive_rep (rcv); 884 dns->receive_rep (rcv);
839 } 885 }
840 886
887 {
841 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 888 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
842 889
843 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 890 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
844 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type 891 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
845 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 892 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
846 pkt [offs++] = 0; pkt [offs++] = 0; 893 pkt [offs++] = 0; pkt [offs++] = 0;
847 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 894 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
848 895
849 int rdlen_offs = offs += 2; 896 int rdlen_offs = offs += 2;
850 897
898 if (dns)
899 {
851 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 900 int dlen = ntohs (dns->cfg.max_size) - offs;
901
852 // bind doesn't compress well, so reduce further by one label length 902 // bind doesn't compress well, so reduce further by one label length
853 dlen -= qlen; 903 dlen -= qlen;
854 904
855 if (dns) 905 // only put data into in-order sequence packets, if
856 { 906 // we receive out-of-order packets we generate empty
907 // replies
857 while (dlen > 1 && !dns->snddq.empty ()) 908 while (dlen > 1 && !dns->snddq.empty () && in_seq)
858 { 909 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 910 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 911
861 if (txtlen > dns->snddq.size ()) 912 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 913 txtlen = dns->snddq.size ();
863 914
864 pkt[offs++] = txtlen; 915 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 916 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 917 offs += txtlen;
867 dns->snddq.remove (txtlen); 918 dns->snddq.remove (txtlen);
868 919
869 dlen -= txtlen + 1; 920 dlen -= txtlen + 1;
870 } 921 }
871 922
872 // avoid empty TXT rdata 923 // avoid empty TXT rdata
873 if (offs == rdlen_offs) 924 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 925 pkt[offs++] = 0;
875 926
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 927 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 928 }
878 else 929 else
879 { 930 {
880 // send RST 931 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 932 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 933 pkt [offs++] = CMD_IP_RST;
883 } 934 }
884 935
885 int rdlen = offs - rdlen_offs; 936 int rdlen = offs - rdlen_offs;
886 937
887 pkt [rdlen_offs - 2] = rdlen >> 8; 938 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 939 pkt [rdlen_offs - 1] = rdlen;
889 940
890 if (dns) 941 if (dns)
891 { 942 {
892 // now update dns_rcv copy 943 // now update dns_rcv copy
893 rcv->pkt->len = offs; 944 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 945 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 946 }
947 }
896 948
897 duplicate_request: ; 949 duplicate_request: ;
898 } 950 }
899 else 951 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 952 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 964 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 965 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 966 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 967 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 968
917 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client); 969 slog (L_INFO, _("DNS: client %d connects"), client);
918 970
919 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 971 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 972 pkt [offs++] = CMD_IP_REJ;
921 973
922 if (0 < client && client <= conns.size ()) 974 if (0 < client && client <= conns.size ())
959 int seqno = (*i)->seqno; 1011 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1012 u8 data[MAXSIZE], *datap = data;
961 1013
962 if ((*i)->retry) 1014 if ((*i)->retry)
963 { 1015 {
964 dns->send_interval *= 1.001; 1016 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1017 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1018 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1019 }
968 else 1020 else
969 { 1021 {
970#if 1 1022#if 0
971 dns->send_interval *= 0.9999; 1023 dns->send_interval *= 0.999;
972#endif 1024#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 1025 // the latency surely puts an upper bound on
977 // the minimum send interval 1026 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1027 double latency = NOW - (*i)->sent;
979 1028
1029 if (latency < dns->min_latency)
1030 dns->min_latency = latency;
1031
980 if (dns->send_interval > latency) 1032 if (dns->send_interval > dns->min_latency * LATENCY_FACTOR)
981 dns->send_interval = latency; 1033 dns->send_interval = dns->min_latency * LATENCY_FACTOR;
1034
1035 if (dns->send_interval < MIN_SEND_INTERVAL)
1036 dns->send_interval = MIN_SEND_INTERVAL;
982 } 1037 }
983 1038
984 delete *i; 1039 delete *i;
985 dns_sndpq.erase (i); 1040 dns_sndpq.erase (i);
986 1041
1036 1091
1037 if (ip [0] == CMD_IP_1 1092 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1093 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1094 && ip [2] == CMD_IP_3)
1040 { 1095 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1096 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1097
1043 if (ip [3] == CMD_IP_RST) 1098 if (ip [3] == CMD_IP_RST)
1044 { 1099 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1100 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1046 1101
1047 delete dns; c->dns = 0; 1102 delete dns; c->dns = 0;
1048 1103
1049 return; 1104 return;
1050 } 1105 }
1051 else if (ip [3] == CMD_IP_SYN) 1106 else if (ip [3] == CMD_IP_SYN)
1052 { 1107 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1108 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 1109 dns->established = true;
1055 } 1110 }
1056 else if (ip [3] == CMD_IP_REJ) 1111 else if (ip [3] == CMD_IP_REJ)
1057 { 1112 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1113 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1059 abort (); 1114 abort ();
1060 } 1115 }
1061 else 1116 else
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1117 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1063 } 1118 }
1064 else 1119 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1120 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1121 ip [0], ip [1], ip [2], ip [3]);
1067 1122
1068 return; 1123 return;
1069 } 1124 }
1070 1125
1071 int client, rseqno; 1126 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1127 decode_header (qname, client, rseqno);
1073 1128
1074 if (client != THISNODE->id) 1129 if (client != THISNODE->id)
1075 { 1130 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1131 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1132 datap = 0;
1078 } 1133 }
1079 else if (rseqno != seqno) 1134 else if (rseqno != seqno)
1080 { 1135 {
1081 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1136 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1082 datap = 0; 1137 datap = 0;
1083 } 1138 }
1084 } 1139 }
1085 } 1140 }
1086 1141
1103 1158
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1159 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1160
1106 if (pkt->len > 0) 1161 if (pkt->len > 0)
1107 { 1162 {
1108 if (THISNODE->dns_port) 1163 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1164 dnsv4_client (*pkt);
1165 else
1109 { 1166 {
1110 dnsv4_server (*pkt); 1167 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1168 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1169 }
1113 else
1114 dnsv4_client (*pkt);
1115 1170
1116 delete pkt; 1171 delete pkt;
1117 } 1172 }
1118 } 1173 }
1119} 1174}
1120 1175
1121bool 1176bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1177vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1178{
1179 int client = ntohs (si.port);
1180
1181 assert (0 < client && client <= conns.size ());
1182
1183 connection *c = conns [client - 1];
1184
1124 if (!dns) 1185 if (!c->dns)
1125 dns = new dns_connection (this); 1186 c->dns = new dns_connection (c);
1126 1187
1127 if (!dns->snddq.put (pkt)) 1188 if (!c->dns->snddq.put (pkt))
1128 return false; 1189 return false;
1129 1190
1130 dns->tw.trigger (); 1191 c->dns->tw.trigger ();
1131 1192
1132 return true; 1193 return true;
1133} 1194}
1134 1195
1135void 1196void
1162 if (!send) 1223 if (!send)
1163 { 1224 {
1164 send = r; 1225 send = r;
1165 1226
1166 r->retry++; 1227 r->retry++;
1167 r->timeout = NOW + r->retry; 1228 r->timeout = NOW + (r->retry * min_latency * 8.);
1229
1230 // the following code changes the query section a bit, forcing
1231 // the forwarder to generate a new request
1232 if (r->stdhdr)
1233 {
1234 //printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
1235 //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1236 }
1168 } 1237 }
1169 } 1238 }
1170 else 1239 else
1171 NEXT (r->timeout); 1240 NEXT (r->timeout);
1172 } 1241 }
1173 1242
1243 if (!send)
1244 {
1174 if (last_sent + send_interval <= NOW) 1245 if (last_sent + send_interval <= NOW)
1175 {
1176 if (!send)
1177 { 1246 {
1178 // generate a new packet, if wise 1247 // generate a new packet, if wise
1179 1248
1180 if (!established) 1249 if (!established)
1181 { 1250 {
1182 if (vpn->dns_sndpq.empty ()) 1251 if (vpn->dns_sndpq.empty ())
1183 { 1252 {
1184 send = new dns_snd (this); 1253 send = new dns_snd (this);
1185 1254
1186 cfg.reset (THISNODE->id); 1255 cfg.reset (THISNODE->id);
1187 send->gen_syn_req (cfg); 1256 send->gen_syn_req ();
1188 } 1257 }
1189 } 1258 }
1190 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING) 1259 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
1260 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1191 { 1261 {
1262 //printf ("sending data request etc.\n"); //D
1263 if (!snddq.empty () || last_received + 1. > NOW)
1264 {
1265 poll_interval = send_interval;
1266 NEXT (NOW + send_interval);
1267 }
1268
1192 send = new dns_snd (this); 1269 send = new dns_snd (this);
1193 send->gen_stream_req (sndseq, snddq); 1270 send->gen_stream_req (sndseq, snddq);
1271 send->timeout = NOW + min_latency * 8.;
1194 1272
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1273 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1274 }
1197 1275
1198 if (send) 1276 if (send)
1199 vpn->dns_sndpq.push_back (send); 1277 vpn->dns_sndpq.push_back (send);
1200 } 1278 }
1279 else
1280 NEXT (last_sent + send_interval);
1281 }
1201 1282
1202 if (send) 1283 if (send)
1203 { 1284 {
1204 last_sent = NOW; 1285 last_sent = NOW;
1205 sendto (vpn->dnsv4_fd, 1286 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1287 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1288 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1289 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1290
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1291 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1292 poll_interval, send_interval, next - NOW,
1215 vpn->dns_sndpq.size (), snddq.size ()); 1293 vpn->dns_sndpq.size (), snddq.size (),
1294 rcvpq.size ());
1216 1295
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem 1296 // TODO: no idea when this happens, but when next < NOW, we have a problem
1218 if (next < NOW + 0.0001) 1297 if (next < NOW + 0.0001)
1219 next = NOW + 0.1; 1298 next = NOW + 0.1;
1220 1299

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