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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 1.35 by pcg, Wed Mar 16 14:56:32 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>
43 44
44#include "netcompat.h" 45#include "netcompat.h"
45 46
46#include "vpn.h" 47#include "vpn.h"
47 48
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 49#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
50#define ACTIVITY_INTERVAL 5. 50#define ACTIVITY_INTERVAL 5.
51 51
52#define TIMEOUT_FACTOR 2.
53
52#define INITIAL_TIMEOUT 1. // retry timeouts 54#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn 55#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
54 56
55#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests 57#define MIN_SEND_INTERVAL 0.001 // wait at least this time between sending requests
56#define MAX_SEND_INTERVAL 0.5 // optimistic? 58#define MAX_SEND_INTERVAL 2. // optimistic?
57 59
60#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
58#define MAX_OUTSTANDING 40 // max. outstanding requests 61#define MAX_OUTSTANDING 100 // max. outstanding requests
59#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING 62#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 63#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
61 64
62#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well 65#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 66// 240 leaves about 4 bytes of server reply data
64// every two request bytes less give room for one reply byte 67// every request byte less give room for two reply bytes
65 68
66#define SEQNO_MASK 0xffff 69#define SEQNO_MASK 0x3fff
67#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 70#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
68 71
69#define MAX_LBL_SIZE 63 72#define MAX_LBL_SIZE 63
70#define MAX_PKT_SIZE 512 73#define MAX_PKT_SIZE 512
71 74
264static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); 267static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
265 268
266///////////////////////////////////////////////////////////////////////////// 269/////////////////////////////////////////////////////////////////////////////
267 270
268#define HDRSIZE 6 271#define HDRSIZE 6
269 272
270inline void encode_header (char *data, int clientid, int seqno) 273inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
271{ 274{
272 u8 hdr[3] = { clientid, seqno >> 8, seqno }; 275 seqno &= SEQNO_MASK;
276
277 u8 hdr[3] = {
278 clientid,
279 (seqno >> 8) | (retry << 6),
280 seqno,
281 };
273 282
274 assert (clientid < 256); 283 assert (clientid < 256);
275 284
276 cdc26.encode (data, hdr, 3); 285 cdc26.encode (data, hdr, 3);
277} 286}
281 u8 hdr[3]; 290 u8 hdr[3];
282 291
283 cdc26.decode (hdr, data, HDRSIZE); 292 cdc26.decode (hdr, data, HDRSIZE);
284 293
285 clientid = hdr[0]; 294 clientid = hdr[0];
286 seqno = (hdr[1] << 8) | hdr[2]; 295 seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
287} 296}
288 297
289///////////////////////////////////////////////////////////////////////////// 298/////////////////////////////////////////////////////////////////////////////
290 299
291struct byte_stream 300struct byte_stream
320} 329}
321 330
322void byte_stream::remove (int count) 331void byte_stream::remove (int count)
323{ 332{
324 if (count > fill) 333 if (count > fill)
325 abort (); 334 assert (count <= fill);
326 335
327 memmove (data, data + count, fill -= count); 336 memmove (data, data + count, fill -= count);
328} 337}
329 338
330bool byte_stream::put (u8 *data, unsigned int datalen) 339bool byte_stream::put (u8 *data, unsigned int datalen)
350 return true; 359 return true;
351} 360}
352 361
353vpn_packet *byte_stream::get () 362vpn_packet *byte_stream::get ()
354{ 363{
364 unsigned int len;
365
366 for (;;)
367 {
355 unsigned int len = (data [0] << 8) | data [1]; 368 len = (data [0] << 8) | data [1];
356 369
357 if (len > MAXSIZE && fill >= 2) 370 if (len <= MAXSIZE || fill < 2)
358 abort (); // TODO handle this gracefully, connection reset 371 break;
359 372
373 // TODO: handle this better than skipping, e.g. by reset
374 slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
375 remove (1);
376 }
377
360 if (fill < len + 2) 378 if (fill < len + 2)
361 return 0; 379 return 0;
362 380
363 vpn_packet *pkt = new vpn_packet; 381 vpn_packet *pkt = new vpn_packet;
364 382
393struct dns_cfg 411struct dns_cfg
394{ 412{
395 static int next_uid; 413 static int next_uid;
396 414
397 u8 id1, id2, id3, id4; 415 u8 id1, id2, id3, id4;
416
398 u8 version; 417 u8 version;
418 u8 flags;
399 u8 rrtype; 419 u8 rrtype;
400 u8 flags;
401 u8 def_ttl; 420 u8 def_ttl;
402 u8 rcv_cdc; 421
403 u8 snd_cdc;
404 u16 max_size;
405 u16 client; 422 u16 client;
406 u16 uid; // to make request unique 423 u16 uid; // to make request unique
407 424
408 u8 reserved[8]; 425 u16 max_size;
426 u8 seq_cdc;
427 u8 req_cdc;
428
429 u8 rep_cdc;
430 u8 delay; // time in 0.01s units that the server may delay replying packets
431 u8 r3, r4;
432
433 u8 r5, r6, r7, r8;
409 434
410 void reset (int clientid); 435 void reset (int clientid);
411 bool valid (); 436 bool valid ();
412}; 437};
413 438
423 version = 1; 448 version = 1;
424 449
425 rrtype = RR_TYPE_TXT; 450 rrtype = RR_TYPE_TXT;
426 flags = 0; 451 flags = 0;
427 def_ttl = 0; 452 def_ttl = 0;
453 seq_cdc = 26;
454 req_cdc = 62;
428 rcv_cdc = 0; 455 rep_cdc = 0;
429 snd_cdc = 62;
430 max_size = ntohs (MAX_PKT_SIZE); 456 max_size = htons (MAX_PKT_SIZE);
431 client = ntohs (clientid); 457 client = htons (clientid);
432 uid = next_uid++; 458 uid = next_uid++;
459 delay = 0;
433 460
434 memset (reserved, 0, 8); 461 r3 = r4 = 0;
462 r4 = r5 = r6 = r7 = 0;
435} 463}
436 464
437bool dns_cfg::valid () 465bool dns_cfg::valid ()
438{ 466{
439 return id1 == 'G' 467 return id1 == 'G'
440 && id2 == 'V' 468 && id2 == 'V'
441 && id3 == 'P' 469 && id3 == 'P'
442 && id4 == 'E' 470 && id4 == 'E'
471 && seq_cdc == 26
472 && req_cdc == 62
473 && rep_cdc == 0
443 && version == 1 474 && version == 1;
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62
447 && max_size == ntohs (MAX_PKT_SIZE);
448} 475}
449 476
450struct dns_packet : net_packet 477struct dns_packet : net_packet
451{ 478{
452 u16 id; 479 u16 id;
453 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 480 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
454 u16 qdcount, ancount, nscount, arcount; 481 u16 qdcount, ancount, nscount, arcount;
455 482
456 u8 data[MAXSIZE - 6 * 2]; 483 u8 data [MAXSIZE - 6 * 2];
457 484
458 int decode_label (char *data, int size, int &offs); 485 int decode_label (char *data, int size, int &offs);
459}; 486};
460 487
461int dns_packet::decode_label (char *data, int size, int &offs) 488int dns_packet::decode_label (char *data, int size, int &offs)
492 return data - orig; 519 return data - orig;
493} 520}
494 521
495///////////////////////////////////////////////////////////////////////////// 522/////////////////////////////////////////////////////////////////////////////
496 523
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 524static u16 dns_id = 0; // TODO: should be per-vpn
513 525
514static u16 next_id () 526static u16 next_id ()
515{ 527{
528 if (!dns_id)
529 dns_id = time (0);
530
516 // the simplest lsfr with periodicity 65535 i could find 531 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 532 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 533 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 534 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 535 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 536 ^ (dns_id >> 15)) & 1);
522 537
523 return dns_id; 538 return dns_id;
524} 539}
525 540
541struct dns_rcv;
542struct dns_snd;
543
544struct dns_connection
545{
546 connection *c;
547 struct vpn *vpn;
548
549 dns_cfg cfg;
550
551 bool established;
552
553 tstamp last_received;
554 tstamp last_sent;
555 double min_latency;
556 double poll_interval, send_interval;
557
558 vector<dns_rcv *> rcvpq;
559
560 byte_stream rcvdq; int rcvseq; int repseq;
561 byte_stream snddq; int sndseq;
562
563 void time_cb (time_watcher &w); time_watcher tw;
564 void receive_rep (dns_rcv *r);
565
566 dns_connection (connection *c);
567 ~dns_connection ();
568};
569
570struct dns_snd
571{
572 dns_packet *pkt;
573 tstamp timeout, sent;
574 int retry;
575 struct dns_connection *dns;
576 int seqno;
577 bool stdhdr;
578
579 void gen_stream_req (int seqno, byte_stream &stream);
580 void gen_syn_req ();
581
582 dns_snd (dns_connection *dns);
583 ~dns_snd ();
584};
585
526dns_snd::dns_snd (dns_connection *dns) 586dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 587: dns (dns)
528{ 588{
529 timeout = 0; 589 timeout = 0;
530 retry = 0; 590 retry = 0;
531 seqno = 0; 591 seqno = 0;
532 sent = NOW; 592 sent = NOW;
593 stdhdr = false;
533 594
534 pkt = new dns_packet; 595 pkt = new dns_packet;
535 596
536 pkt->id = next_id (); 597 pkt->id = next_id ();
537} 598}
564 } 625 }
565} 626}
566 627
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 628void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 629{
630 stdhdr = true;
569 this->seqno = seqno; 631 this->seqno = seqno;
570 632
571 timeout = NOW + INITIAL_TIMEOUT; 633 timeout = NOW + INITIAL_TIMEOUT;
572 634
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 635 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 636 pkt->qdcount = htons (1);
575 637
576 int offs = 6*2; 638 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 639 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, 640 // 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 641 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
580 642
581 char enc[256], *encp = enc; 643 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 644 encode_header (enc, THISNODE->id, seqno);
600 encp += lbllen; 662 encp += lbllen;
601 663
602 enclen -= lbllen; 664 enclen -= lbllen;
603 } 665 }
604 666
605 append_domain (*pkt, offs, THISNODE->domain); 667 append_domain (*pkt, offs, dns->c->conf->domain);
606 668
607 (*pkt)[offs++] = 0; 669 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 670 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 671 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 672
611 pkt->len = offs; 673 pkt->len = offs;
612} 674}
613 675
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 676void dns_snd::gen_syn_req ()
615{ 677{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 678 timeout = NOW + INITIAL_SYN_TIMEOUT;
617 679
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 680 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 681 pkt->qdcount = htons (1);
620 682
621 int offs = 6*2; 683 int offs = 6 * 2;
622 684
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 685 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 686
625 assert (elen <= MAX_LBL_SIZE); 687 assert (elen <= MAX_LBL_SIZE);
626 688
627 (*pkt)[offs] = elen; 689 (*pkt)[offs] = elen;
628 offs += elen + 1; 690 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 691 append_domain (*pkt, offs, dns->c->conf->domain);
630 692
631 (*pkt)[offs++] = 0; 693 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 694 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 695 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 696
657 delete pkt; 719 delete pkt;
658} 720}
659 721
660///////////////////////////////////////////////////////////////////////////// 722/////////////////////////////////////////////////////////////////////////////
661 723
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) 724dns_connection::dns_connection (connection *c)
688: c (c) 725: c (c)
689, rcvdq (MAX_BACKLOG * 2) 726, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 727, snddq (MAX_BACKLOG)
691, tw (this, &dns_connection::time_cb) 728, tw (this, &dns_connection::time_cb)
692{ 729{
693 vpn = c->vpn; 730 vpn = c->vpn;
694 731
695 established = false; 732 established = false;
696 733
697 rcvseq = sndseq = 0; 734 rcvseq = repseq = sndseq = 0;
698 735
699 last_sent = last_received = 0; 736 last_sent = last_received = 0;
700 poll_interval = MIN_POLL_INTERVAL; 737 poll_interval = 0.5; // starting here
701 send_interval = 0.2; // starting rate 738 send_interval = 0.5; // starting rate
739 min_latency = INITIAL_TIMEOUT;
702} 740}
703 741
704dns_connection::~dns_connection () 742dns_connection::~dns_connection ()
705{ 743{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 744 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
718 756
719 poll_interval = send_interval; 757 poll_interval = send_interval;
720 } 758 }
721 else 759 else
722 { 760 {
723 poll_interval *= 1.1; 761 poll_interval *= 1.5;
762
724 if (poll_interval > MAX_POLL_INTERVAL) 763 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL; 764 poll_interval = MAX_POLL_INTERVAL;
726 } 765 }
727 766
728 rcvpq.push_back (r); 767 rcvpq.push_back (r);
746 } 785 }
747 786
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 787 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 788
750 if (!rcvdq.put (r->data, r->datalen)) 789 if (!rcvdq.put (r->data, r->datalen))
790 {
791 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
751 abort (); // MUST never overflow, can be caused by data corruption, TODO 792 abort (); // MUST never overflow, can be caused by data corruption, TODO
793 }
752 794
753 while (vpn_packet *pkt = rcvdq.get ()) 795 while (vpn_packet *pkt = rcvdq.get ())
754 { 796 {
755 sockinfo si; 797 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 798 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
757 799
758 vpn->recv_vpn_packet (pkt, si); 800 vpn->recv_vpn_packet (pkt, si);
759 801
760 delete pkt; 802 delete pkt;
761 } 803 }
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 817 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 818
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 819 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 820 && pkt.qdcount == htons (1))
779 { 821 {
780 char qname[MAXSIZE]; 822 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 823 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 824
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 825 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 826 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 827
786 pkt.qdcount = htons (1); 828 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 829 pkt.ancount = 0;
788 pkt.nscount = 0; // should be self, as other nameservers reply like this 830 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 831 pkt.arcount = 0; // a record for self, as other nameservers reply like this
790 832
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 833 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 834
793 int dlen = strlen (THISNODE->domain); 835 int dlen = strlen (THISNODE->domain);
794 836
795 if (qclass == RR_CLASS_IN 837 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 838 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 839 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 840 {
799 // now generate reply 841 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 842 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 843 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 844
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 866 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 867 {
826 // already seen that request: simply reply with the cached reply 868 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 869 dns_rcv *r = *i;
828 870
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 871 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
872
873 // refresh header & id, as the retry count could have changed
874 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
875 r->pkt->id = pkt.id;
830 876
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 877 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 878
833 goto duplicate_request; 879 goto duplicate_request;
834 } 880 }
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
857 while (dlen > 1 && !dns->snddq.empty ()) 907 // replies
908 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
909 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
858 { 910 {
911 dns->repseq = seqno;
912
913 while (dlen > 1 && !dns->snddq.empty ())
914 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 915 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 916
861 if (txtlen > dns->snddq.size ()) 917 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 918 txtlen = dns->snddq.size ();
863 919
864 pkt[offs++] = txtlen; 920 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 921 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 922 offs += txtlen;
867 dns->snddq.remove (txtlen); 923 dns->snddq.remove (txtlen);
868 924
869 dlen -= txtlen + 1; 925 dlen -= txtlen + 1;
926 }
870 } 927 }
871 928
872 // avoid empty TXT rdata 929 // avoid completely empty TXT rdata
873 if (offs == rdlen_offs) 930 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 931 pkt[offs++] = 0;
875 932
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 933 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 934 }
878 else 935 else
879 { 936 {
880 // send RST 937 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 938 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 939 pkt [offs++] = CMD_IP_RST;
883 } 940 }
884 941
885 int rdlen = offs - rdlen_offs; 942 int rdlen = offs - rdlen_offs;
886 943
887 pkt [rdlen_offs - 2] = rdlen >> 8; 944 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 945 pkt [rdlen_offs - 1] = rdlen;
889 946
890 if (dns) 947 if (dns)
891 { 948 {
892 // now update dns_rcv copy 949 // now update dns_rcv copy
893 rcv->pkt->len = offs; 950 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 951 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 952 }
953 }
896 954
897 duplicate_request: ; 955 duplicate_request: ;
898 } 956 }
899 else 957 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 958 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 970 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 971 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 972 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 973 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 974
917 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client); 975 slog (L_INFO, _("DNS: client %d connects"), client);
918 976
919 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 977 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 978 pkt [offs++] = CMD_IP_REJ;
921 979
922 if (0 < client && client <= conns.size ()) 980 if (0 < client && client <= conns.size ())
959 int seqno = (*i)->seqno; 1017 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1018 u8 data[MAXSIZE], *datap = data;
961 1019
962 if ((*i)->retry) 1020 if ((*i)->retry)
963 { 1021 {
964 dns->send_interval *= 1.001; 1022 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1023 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1024 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1025 }
968 else 1026 else
969 { 1027 {
970#if 1 1028#if 0
971 dns->send_interval *= 0.9999; 1029 dns->send_interval *= 0.999;
972#endif 1030#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 1031 // the latency surely puts an upper bound on
977 // the minimum send interval 1032 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1033 double latency = NOW - (*i)->sent;
979 1034
1035 if (latency < dns->min_latency)
1036 dns->min_latency = latency;
1037
980 if (dns->send_interval > latency) 1038 if (dns->send_interval > dns->min_latency * LATENCY_FACTOR)
981 dns->send_interval = latency; 1039 dns->send_interval = dns->min_latency * LATENCY_FACTOR;
1040
1041 if (dns->send_interval < MIN_SEND_INTERVAL)
1042 dns->send_interval = MIN_SEND_INTERVAL;
982 } 1043 }
983 1044
984 delete *i; 1045 delete *i;
985 dns_sndpq.erase (i); 1046 dns_sndpq.erase (i);
986 1047
1036 1097
1037 if (ip [0] == CMD_IP_1 1098 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1099 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1100 && ip [2] == CMD_IP_3)
1040 { 1101 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1102 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1103
1043 if (ip [3] == CMD_IP_RST) 1104 if (ip [3] == CMD_IP_RST)
1044 { 1105 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1106 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1046 1107
1047 delete dns; c->dns = 0; 1108 delete dns; c->dns = 0;
1048 1109
1049 return; 1110 return;
1050 } 1111 }
1051 else if (ip [3] == CMD_IP_SYN) 1112 else if (ip [3] == CMD_IP_SYN)
1052 { 1113 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1114 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 1115 dns->established = true;
1055 } 1116 }
1056 else if (ip [3] == CMD_IP_REJ) 1117 else if (ip [3] == CMD_IP_REJ)
1057 { 1118 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1119 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1059 abort (); 1120 abort ();
1060 } 1121 }
1061 else 1122 else
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1123 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1063 } 1124 }
1064 else 1125 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1126 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1127 ip [0], ip [1], ip [2], ip [3]);
1067 1128
1068 return; 1129 return;
1069 } 1130 }
1070 1131
1071 int client, rseqno; 1132 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1133 decode_header (qname, client, rseqno);
1073 1134
1074 if (client != THISNODE->id) 1135 if (client != THISNODE->id)
1075 { 1136 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1137 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1138 datap = 0;
1078 } 1139 }
1079 else if (rseqno != seqno) 1140 else if (rseqno != seqno)
1080 { 1141 {
1081 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1142 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1082 datap = 0; 1143 datap = 0;
1083 } 1144 }
1084 } 1145 }
1085 } 1146 }
1086 1147
1103 1164
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1165 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1166
1106 if (pkt->len > 0) 1167 if (pkt->len > 0)
1107 { 1168 {
1108 if (THISNODE->dns_port) 1169 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1170 dnsv4_client (*pkt);
1171 else
1109 { 1172 {
1110 dnsv4_server (*pkt); 1173 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1174 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1175 }
1113 else
1114 dnsv4_client (*pkt);
1115 1176
1116 delete pkt; 1177 delete pkt;
1117 } 1178 }
1118 } 1179 }
1119} 1180}
1120 1181
1121bool 1182bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1183vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1184{
1185 int client = ntohl (si.host);
1186
1187 assert (0 < client && client <= conns.size ());
1188
1189 connection *c = conns [client - 1];
1190
1124 if (!dns) 1191 if (!c->dns)
1125 dns = new dns_connection (this); 1192 c->dns = new dns_connection (c);
1126 1193
1127 if (!dns->snddq.put (pkt)) 1194 if (c->dns->snddq.put (pkt))
1128 return false;
1129
1130 dns->tw.trigger (); 1195 c->dns->tw.trigger ();
1131 1196
1197 // always return true even if the buffer overflows
1132 return true; 1198 return true;
1133} 1199}
1134 1200
1135void 1201void
1136connection::dnsv4_reset_connection () 1202connection::dnsv4_reset_connection ()
1162 if (!send) 1228 if (!send)
1163 { 1229 {
1164 send = r; 1230 send = r;
1165 1231
1166 r->retry++; 1232 r->retry++;
1167 r->timeout = NOW + r->retry; 1233 r->timeout = NOW + (r->retry * min_latency * TIMEOUT_FACTOR);
1234
1235 // the following code changes the query section a bit, forcing
1236 // the forwarder to generate a new request
1237 if (r->stdhdr)
1238 {
1239 //printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
1240 //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1241 }
1168 } 1242 }
1169 } 1243 }
1170 else 1244 else
1171 NEXT (r->timeout); 1245 NEXT (r->timeout);
1172 } 1246 }
1173 1247
1174 if (last_sent + send_interval <= NOW)
1175 {
1176 if (!send) 1248 if (!send)
1249 {
1250 // generate a new packet, if wise
1251
1252 if (!established)
1177 { 1253 {
1178 // generate a new packet, if wise
1179
1180 if (!established)
1181 {
1182 if (vpn->dns_sndpq.empty ()) 1254 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 { 1255 {
1192 send = new dns_snd (this); 1256 send = new dns_snd (this);
1257
1258 cfg.reset (THISNODE->id);
1259 send->gen_syn_req ();
1260 }
1261 }
1262 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
1263 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1264 {
1265 if (last_sent + send_interval <= NOW)
1266 {
1267 //printf ("sending data request etc.\n"); //D
1268 if (!snddq.empty () || last_received + 1. > NOW)
1269 {
1270 poll_interval = send_interval;
1271 NEXT (NOW + send_interval);
1272 }
1273
1274 send = new dns_snd (this);
1193 send->gen_stream_req (sndseq, snddq); 1275 send->gen_stream_req (sndseq, snddq);
1276 send->timeout = NOW + min_latency * TIMEOUT_FACTOR;
1194 1277
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1278 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1279 }
1197 1280 else
1198 if (send) 1281 NEXT (last_sent + send_interval);
1199 vpn->dns_sndpq.push_back (send);
1200 } 1282 }
1201 1283
1202 if (send) 1284 if (send)
1203 { 1285 vpn->dns_sndpq.push_back (send);
1286 }
1287
1288 if (send)
1289 {
1204 last_sent = NOW; 1290 last_sent = NOW;
1205 sendto (vpn->dnsv4_fd, 1291 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1292 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1293 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1294 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1295
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1296 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1297 poll_interval, send_interval, next - NOW,
1215 vpn->dns_sndpq.size (), snddq.size ()); 1298 vpn->dns_sndpq.size (), snddq.size (),
1299 rcvpq.size ());
1216 1300
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem 1301 // TODO: no idea when this happens, but when next < NOW, we have a problem
1218 if (next < NOW + 0.0001) 1302 if (next < NOW + 0.001)
1219 next = NOW + 0.1; 1303 next = NOW + 0.1;
1220 1304
1221 w.start (next); 1305 w.start (next);
1222} 1306}
1223 1307

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