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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 1.39 by pcg, Tue Apr 26 00:55:56 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{
439 return id1 == 'G' 466 return id1 == 'G'
440 && id2 == 'V' 467 && id2 == 'V'
441 && id3 == 'P' 468 && id3 == 'P'
442 && id4 == 'E' 469 && id4 == 'E'
470 && seq_cdc == 26
471 && req_cdc == 62
472 && rep_cdc == 0
443 && version == 1 473 && version == 1;
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62
447 && max_size == ntohs (MAX_PKT_SIZE);
448} 474}
449 475
450struct dns_packet : net_packet 476struct dns_packet : net_packet
451{ 477{
452 u16 id; 478 u16 id;
453 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 479 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
454 u16 qdcount, ancount, nscount, arcount; 480 u16 qdcount, ancount, nscount, arcount;
455 481
456 u8 data[MAXSIZE - 6 * 2]; 482 u8 data [MAXSIZE - 6 * 2];
457 483
458 int decode_label (char *data, int size, int &offs); 484 int decode_label (char *data, int size, int &offs);
459}; 485};
460 486
461int dns_packet::decode_label (char *data, int size, int &offs) 487int dns_packet::decode_label (char *data, int size, int &offs)
492 return data - orig; 518 return data - orig;
493} 519}
494 520
495///////////////////////////////////////////////////////////////////////////// 521/////////////////////////////////////////////////////////////////////////////
496 522
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 523static u16 dns_id = 0; // TODO: should be per-vpn
513 524
514static u16 next_id () 525static u16 next_id ()
515{ 526{
527 if (!dns_id)
528 dns_id = time (0);
529
516 // the simplest lsfr with periodicity 65535 i could find 530 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 531 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 532 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 533 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 534 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 535 ^ (dns_id >> 15)) & 1);
522 536
523 return dns_id; 537 return dns_id;
524} 538}
525 539
540struct dns_rcv;
541struct dns_snd;
542
543struct dns_connection
544{
545 connection *c;
546 struct vpn *vpn;
547
548 dns_cfg cfg;
549
550 bool established;
551
552 tstamp last_received;
553 tstamp last_sent;
554 double min_latency;
555 double poll_interval, send_interval;
556
557 vector<dns_rcv *> rcvpq;
558
559 byte_stream rcvdq; int rcvseq; int repseq;
560 byte_stream snddq; int sndseq;
561
562 void time_cb (time_watcher &w); time_watcher tw;
563 void receive_rep (dns_rcv *r);
564
565 dns_connection (connection *c);
566 ~dns_connection ();
567};
568
569struct dns_snd
570{
571 dns_packet *pkt;
572 tstamp timeout, sent;
573 int retry;
574 struct dns_connection *dns;
575 int seqno;
576 bool stdhdr;
577
578 void gen_stream_req (int seqno, byte_stream &stream);
579 void gen_syn_req ();
580
581 dns_snd (dns_connection *dns);
582 ~dns_snd ();
583};
584
526dns_snd::dns_snd (dns_connection *dns) 585dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 586: dns (dns)
528{ 587{
529 timeout = 0; 588 timeout = 0;
530 retry = 0; 589 retry = 0;
531 seqno = 0; 590 seqno = 0;
532 sent = NOW; 591 sent = NOW;
592 stdhdr = false;
533 593
534 pkt = new dns_packet; 594 pkt = new dns_packet;
535 595
536 pkt->id = next_id (); 596 pkt->id = next_id ();
537} 597}
564 } 624 }
565} 625}
566 626
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 627void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 628{
629 stdhdr = true;
569 this->seqno = seqno; 630 this->seqno = seqno;
570 631
571 timeout = NOW + INITIAL_TIMEOUT; 632 timeout = NOW + INITIAL_TIMEOUT;
572 633
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 634 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 635 pkt->qdcount = htons (1);
575 636
576 int offs = 6*2; 637 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 638 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, 639 // 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 640 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
580 641
581 char enc[256], *encp = enc; 642 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 643 encode_header (enc, THISNODE->id, seqno);
600 encp += lbllen; 661 encp += lbllen;
601 662
602 enclen -= lbllen; 663 enclen -= lbllen;
603 } 664 }
604 665
605 append_domain (*pkt, offs, THISNODE->domain); 666 append_domain (*pkt, offs, dns->c->conf->domain);
606 667
607 (*pkt)[offs++] = 0; 668 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 669 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 670 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 671
611 pkt->len = offs; 672 pkt->len = offs;
612} 673}
613 674
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 675void dns_snd::gen_syn_req ()
615{ 676{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 677 timeout = NOW + INITIAL_SYN_TIMEOUT;
617 678
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 679 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 680 pkt->qdcount = htons (1);
620 681
621 int offs = 6*2; 682 int offs = 6 * 2;
622 683
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 684 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 685
625 assert (elen <= MAX_LBL_SIZE); 686 assert (elen <= MAX_LBL_SIZE);
626 687
627 (*pkt)[offs] = elen; 688 (*pkt)[offs] = elen;
628 offs += elen + 1; 689 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 690 append_domain (*pkt, offs, dns->c->conf->domain);
630 691
631 (*pkt)[offs++] = 0; 692 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 693 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 694 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 695
657 delete pkt; 718 delete pkt;
658} 719}
659 720
660///////////////////////////////////////////////////////////////////////////// 721/////////////////////////////////////////////////////////////////////////////
661 722
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) 723dns_connection::dns_connection (connection *c)
688: c (c) 724: c (c)
689, rcvdq (MAX_BACKLOG * 2) 725, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 726, snddq (MAX_BACKLOG)
691, tw (this, &dns_connection::time_cb) 727, tw (this, &dns_connection::time_cb)
692{ 728{
693 vpn = c->vpn; 729 vpn = c->vpn;
694 730
695 established = false; 731 established = false;
696 732
697 rcvseq = sndseq = 0; 733 rcvseq = repseq = sndseq = 0;
698 734
699 last_sent = last_received = 0; 735 last_sent = last_received = 0;
700 poll_interval = MIN_POLL_INTERVAL; 736 poll_interval = 0.5; // starting here
701 send_interval = 0.2; // starting rate 737 send_interval = 0.5; // starting rate
738 min_latency = INITIAL_TIMEOUT;
702} 739}
703 740
704dns_connection::~dns_connection () 741dns_connection::~dns_connection ()
705{ 742{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 743 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
718 755
719 poll_interval = send_interval; 756 poll_interval = send_interval;
720 } 757 }
721 else 758 else
722 { 759 {
723 poll_interval *= 1.1; 760 poll_interval *= 1.5;
761
724 if (poll_interval > MAX_POLL_INTERVAL) 762 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL; 763 poll_interval = MAX_POLL_INTERVAL;
726 } 764 }
727 765
728 rcvpq.push_back (r); 766 rcvpq.push_back (r);
746 } 784 }
747 785
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 786 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 787
750 if (!rcvdq.put (r->data, r->datalen)) 788 if (!rcvdq.put (r->data, r->datalen))
789 {
790 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
751 abort (); // MUST never overflow, can be caused by data corruption, TODO 791 abort (); // MUST never overflow, can be caused by data corruption, TODO
792 }
752 793
753 while (vpn_packet *pkt = rcvdq.get ()) 794 while (vpn_packet *pkt = rcvdq.get ())
754 { 795 {
755 sockinfo si; 796 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 797 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
757 798
758 vpn->recv_vpn_packet (pkt, si); 799 vpn->recv_vpn_packet (pkt, si);
759 800
760 delete pkt; 801 delete pkt;
761 } 802 }
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 816 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 817
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 818 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 819 && pkt.qdcount == htons (1))
779 { 820 {
780 char qname[MAXSIZE]; 821 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 822 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 823
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 824 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 825 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 826
786 pkt.qdcount = htons (1); 827 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 828 pkt.ancount = 0;
788 pkt.nscount = 0; // should be self, as other nameservers reply like this 829 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 830 pkt.arcount = 0; // a record for self, as other nameservers reply like this
790 831
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 832 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 833
793 int dlen = strlen (THISNODE->domain); 834 int dlen = strlen (THISNODE->domain);
794 835
795 if (qclass == RR_CLASS_IN 836 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 837 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 838 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 839 {
799 // now generate reply 840 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 841 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 842 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 843
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 865 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 866 {
826 // already seen that request: simply reply with the cached reply 867 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 868 dns_rcv *r = *i;
828 869
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 870 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
871
872 // refresh header & id, as the retry count could have changed
873 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
874 r->pkt->id = pkt.id;
830 875
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 876 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 877
833 goto duplicate_request; 878 goto duplicate_request;
834 } 879 }
835 880
836 // new packet, queue 881 // new packet, queue
837 rcv = new dns_rcv (seqno, data, datalen); 882 rcv = new dns_rcv (seqno, data, datalen);
838 dns->receive_rep (rcv); 883 dns->receive_rep (rcv);
839 } 884 }
840 885
886 {
841 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 887 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
842 888
843 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 889 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
844 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type 890 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
845 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 891 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
846 pkt [offs++] = 0; pkt [offs++] = 0; 892 pkt [offs++] = 0; pkt [offs++] = 0;
847 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 893 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
848 894
849 int rdlen_offs = offs += 2; 895 int rdlen_offs = offs += 2;
850 896
897 if (dns)
898 {
851 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 899 int dlen = ntohs (dns->cfg.max_size) - offs;
900
852 // bind doesn't compress well, so reduce further by one label length 901 // bind doesn't compress well, so reduce further by one label length
853 dlen -= qlen; 902 dlen -= qlen;
854 903
855 if (dns) 904 // only put data into in-order sequence packets, if
856 { 905 // we receive out-of-order packets we generate empty
857 while (dlen > 1 && !dns->snddq.empty ()) 906 // replies
907 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
908 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
858 { 909 {
910 dns->repseq = seqno;
911
912 while (dlen > 1 && !dns->snddq.empty ())
913 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 914 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 915
861 if (txtlen > dns->snddq.size ()) 916 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 917 txtlen = dns->snddq.size ();
863 918
864 pkt[offs++] = txtlen; 919 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 920 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 921 offs += txtlen;
867 dns->snddq.remove (txtlen); 922 dns->snddq.remove (txtlen);
868 923
869 dlen -= txtlen + 1; 924 dlen -= txtlen + 1;
925 }
870 } 926 }
871 927
872 // avoid empty TXT rdata 928 // avoid completely empty TXT rdata
873 if (offs == rdlen_offs) 929 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 930 pkt[offs++] = 0;
875 931
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 932 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 933 }
878 else 934 else
879 { 935 {
880 // send RST 936 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 937 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 938 pkt [offs++] = CMD_IP_RST;
883 } 939 }
884 940
885 int rdlen = offs - rdlen_offs; 941 int rdlen = offs - rdlen_offs;
886 942
887 pkt [rdlen_offs - 2] = rdlen >> 8; 943 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 944 pkt [rdlen_offs - 1] = rdlen;
889 945
890 if (dns) 946 if (dns)
891 { 947 {
892 // now update dns_rcv copy 948 // now update dns_rcv copy
893 rcv->pkt->len = offs; 949 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 950 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 951 }
952 }
896 953
897 duplicate_request: ; 954 duplicate_request: ;
898 } 955 }
899 else 956 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 957 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 969 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 970 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 971 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 972 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 973
917 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client); 974 slog (L_INFO, _("DNS: client %d connects"), client);
918 975
919 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 976 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 977 pkt [offs++] = CMD_IP_REJ;
921 978
922 if (0 < client && client <= conns.size ()) 979 if (0 < client && client <= conns.size ())
959 int seqno = (*i)->seqno; 1016 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1017 u8 data[MAXSIZE], *datap = data;
961 1018
962 if ((*i)->retry) 1019 if ((*i)->retry)
963 { 1020 {
964 dns->send_interval *= 1.001; 1021 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1022 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1023 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1024 }
968 else 1025 else
969 { 1026 {
970#if 1 1027#if 0
971 dns->send_interval *= 0.9999; 1028 dns->send_interval *= 0.999;
972#endif 1029#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 1030 // the latency surely puts an upper bound on
977 // the minimum send interval 1031 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1032 double latency = NOW - (*i)->sent;
979 1033
980 if (dns->send_interval > latency) 1034 if (latency < dns->min_latency)
981 dns->send_interval = latency; 1035 dns->min_latency = latency;
1036
1037 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1038 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1039
1040 if (dns->send_interval < conf.dns_send_interval)
1041 dns->send_interval = conf.dns_send_interval;
982 } 1042 }
983 1043
984 delete *i; 1044 delete *i;
985 dns_sndpq.erase (i); 1045 dns_sndpq.erase (i);
986 1046
1036 1096
1037 if (ip [0] == CMD_IP_1 1097 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1098 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1099 && ip [2] == CMD_IP_3)
1040 { 1100 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1101 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1102
1043 if (ip [3] == CMD_IP_RST) 1103 if (ip [3] == CMD_IP_RST)
1044 { 1104 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1105 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1046 1106
1047 delete dns; c->dns = 0; 1107 delete dns; c->dns = 0;
1048 1108
1049 return; 1109 return;
1050 } 1110 }
1051 else if (ip [3] == CMD_IP_SYN) 1111 else if (ip [3] == CMD_IP_SYN)
1052 { 1112 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1113 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 1114 dns->established = true;
1055 } 1115 }
1056 else if (ip [3] == CMD_IP_REJ) 1116 else if (ip [3] == CMD_IP_REJ)
1057 { 1117 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1118 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1059 abort (); 1119 abort ();
1060 } 1120 }
1061 else 1121 else
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1122 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1063 } 1123 }
1064 else 1124 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1125 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1126 ip [0], ip [1], ip [2], ip [3]);
1067 1127
1068 return; 1128 return;
1069 } 1129 }
1070 1130
1071 int client, rseqno; 1131 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1132 decode_header (qname, client, rseqno);
1073 1133
1074 if (client != THISNODE->id) 1134 if (client != THISNODE->id)
1075 { 1135 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1136 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1137 datap = 0;
1078 } 1138 }
1079 else if (rseqno != seqno) 1139 else if (rseqno != seqno)
1080 { 1140 {
1081 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1141 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1082 datap = 0; 1142 datap = 0;
1083 } 1143 }
1084 } 1144 }
1085 } 1145 }
1086 1146
1103 1163
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1164 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1165
1106 if (pkt->len > 0) 1166 if (pkt->len > 0)
1107 { 1167 {
1108 if (THISNODE->dns_port) 1168 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1169 dnsv4_client (*pkt);
1170 else
1109 { 1171 {
1110 dnsv4_server (*pkt); 1172 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1173 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1174 }
1113 else
1114 dnsv4_client (*pkt);
1115 1175
1116 delete pkt; 1176 delete pkt;
1117 } 1177 }
1118 } 1178 }
1119} 1179}
1120 1180
1121bool 1181bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1182vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1183{
1184 int client = ntohl (si.host);
1185
1186 assert (0 < client && client <= conns.size ());
1187
1188 connection *c = conns [client - 1];
1189
1124 if (!dns) 1190 if (!c->dns)
1125 dns = new dns_connection (this); 1191 c->dns = new dns_connection (c);
1126 1192
1127 if (!dns->snddq.put (pkt)) 1193 if (c->dns->snddq.put (pkt))
1128 return false;
1129
1130 dns->tw.trigger (); 1194 c->dns->tw.trigger ();
1131 1195
1196 // always return true even if the buffer overflows
1132 return true; 1197 return true;
1133} 1198}
1134 1199
1135void 1200void
1136connection::dnsv4_reset_connection () 1201connection::dnsv4_reset_connection ()
1162 if (!send) 1227 if (!send)
1163 { 1228 {
1164 send = r; 1229 send = r;
1165 1230
1166 r->retry++; 1231 r->retry++;
1167 r->timeout = NOW + r->retry; 1232 r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
1233
1234 // the following code changes the query section a bit, forcing
1235 // the forwarder to generate a new request
1236 if (r->stdhdr)
1237 {
1238 //printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
1239 //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1240 }
1168 } 1241 }
1169 } 1242 }
1170 else 1243 else
1171 NEXT (r->timeout); 1244 NEXT (r->timeout);
1172 } 1245 }
1173 1246
1174 if (last_sent + send_interval <= NOW)
1175 {
1176 if (!send) 1247 if (!send)
1248 {
1249 // generate a new packet, if wise
1250
1251 if (!established)
1177 { 1252 {
1178 // generate a new packet, if wise
1179
1180 if (!established)
1181 {
1182 if (vpn->dns_sndpq.empty ()) 1253 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 { 1254 {
1192 send = new dns_snd (this); 1255 send = new dns_snd (this);
1256
1257 cfg.reset (THISNODE->id);
1258 send->gen_syn_req ();
1259 }
1260 }
1261 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1262 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1263 {
1264 if (last_sent + send_interval <= NOW)
1265 {
1266 //printf ("sending data request etc.\n"); //D
1267 if (!snddq.empty () || last_received + 1. > NOW)
1268 {
1269 poll_interval = send_interval;
1270 NEXT (NOW + send_interval);
1271 }
1272
1273 send = new dns_snd (this);
1193 send->gen_stream_req (sndseq, snddq); 1274 send->gen_stream_req (sndseq, snddq);
1275 send->timeout = NOW + min_latency * conf.dns_timeout_factor;
1194 1276
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1277 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1278 }
1197 1279 else
1198 if (send) 1280 NEXT (last_sent + send_interval);
1199 vpn->dns_sndpq.push_back (send);
1200 } 1281 }
1201 1282
1202 if (send) 1283 if (send)
1203 { 1284 vpn->dns_sndpq.push_back (send);
1285 }
1286
1287 if (send)
1288 {
1204 last_sent = NOW; 1289 last_sent = NOW;
1205 sendto (vpn->dnsv4_fd, 1290 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1291 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1292 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1293 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1294
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1295 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1296 poll_interval, send_interval, next - NOW,
1215 vpn->dns_sndpq.size (), snddq.size ()); 1297 vpn->dns_sndpq.size (), snddq.size (),
1298 rcvpq.size ());
1216 1299
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem 1300 // TODO: no idea when this happens, but when next < NOW, we have a problem
1301 // doesn't seem to happen anymore
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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