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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 1.44 by pcg, Tue Dec 4 14:55:59 2007 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>
37#include <unistd.h> 42#include <unistd.h>
38#include <fcntl.h> 43#include <fcntl.h>
39 44
40#include <map> 45#include <map>
41 46
47#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
42#include <gmp.h> 48#include <gmp.h>
43 49
44#include "netcompat.h" 50#include "netcompat.h"
45 51
46#include "vpn.h" 52#include "vpn.h"
47 53
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 54#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
50#define ACTIVITY_INTERVAL 5. 55#define ACTIVITY_INTERVAL 5.
51 56
52#define INITIAL_TIMEOUT 1. // retry timeouts 57#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn 58#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
54 59
55#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
56#define MAX_SEND_INTERVAL 0.5 // optimistic? 60#define MAX_SEND_INTERVAL 2. // optimistic?
57 61
58#define MAX_OUTSTANDING 40 // 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{
467 // although the protocol itself allows for some configurability,
468 // only the following encoding/decoding settings are implemented.
439 return id1 == 'G' 469 return id1 == 'G'
440 && id2 == 'V' 470 && id2 == 'V'
441 && id3 == 'P' 471 && id3 == 'P'
442 && id4 == 'E' 472 && id4 == 'E'
473 && seq_cdc == 26
474 && req_cdc == 62
475 && rep_cdc == 0
443 && version == 1 476 && version == 1;
444 && flags == 0
445 && rcv_cdc == 0
446 && snd_cdc == 62
447 && max_size == ntohs (MAX_PKT_SIZE);
448} 477}
449 478
450struct dns_packet : net_packet 479struct dns_packet : net_packet
451{ 480{
452 u16 id; 481 u16 id;
453 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 482 u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
454 u16 qdcount, ancount, nscount, arcount; 483 u16 qdcount, ancount, nscount, arcount;
455 484
456 u8 data[MAXSIZE - 6 * 2]; 485 u8 data [MAXSIZE - 6 * 2];
457 486
458 int decode_label (char *data, int size, int &offs); 487 int decode_label (char *data, int size, int &offs);
459}; 488};
460 489
461int dns_packet::decode_label (char *data, int size, int &offs) 490int dns_packet::decode_label (char *data, int size, int &offs)
492 return data - orig; 521 return data - orig;
493} 522}
494 523
495///////////////////////////////////////////////////////////////////////////// 524/////////////////////////////////////////////////////////////////////////////
496 525
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 526static u16 dns_id = 0; // TODO: should be per-vpn
513 527
514static u16 next_id () 528static u16 next_id ()
515{ 529{
530 if (!dns_id)
531 dns_id = time (0);
532
516 // the simplest lsfr with periodicity 65535 i could find 533 // the simplest lsfr with periodicity 65535 i could find
517 dns_id = (dns_id << 1) 534 dns_id = (dns_id << 1)
518 | (((dns_id >> 1) 535 | (((dns_id >> 1)
519 ^ (dns_id >> 2) 536 ^ (dns_id >> 2)
520 ^ (dns_id >> 4) 537 ^ (dns_id >> 4)
521 ^ (dns_id >> 15)) & 1); 538 ^ (dns_id >> 15)) & 1);
522 539
523 return dns_id; 540 return dns_id;
524} 541}
525 542
543struct dns_rcv;
544struct dns_snd;
545
546struct dns_connection
547{
548 connection *c;
549 struct vpn *vpn;
550
551 dns_cfg cfg;
552
553 bool established;
554
555 tstamp last_received;
556 tstamp last_sent;
557 double min_latency;
558 double poll_interval, send_interval;
559
560 vector<dns_rcv *> rcvpq;
561
562 byte_stream rcvdq; int rcvseq; int repseq;
563 byte_stream snddq; int sndseq;
564
565 void time_cb (ev::timer &w, int revents); ev::timer tw;
566 void receive_rep (dns_rcv *r);
567
568 dns_connection (connection *c);
569 ~dns_connection ();
570};
571
572struct dns_snd
573{
574 dns_packet *pkt;
575 tstamp timeout, sent;
576 int retry;
577 struct dns_connection *dns;
578 int seqno;
579 bool stdhdr;
580
581 void gen_stream_req (int seqno, byte_stream &stream);
582 void gen_syn_req ();
583
584 dns_snd (dns_connection *dns);
585 ~dns_snd ();
586};
587
526dns_snd::dns_snd (dns_connection *dns) 588dns_snd::dns_snd (dns_connection *dns)
527: dns (dns) 589: dns (dns)
528{ 590{
529 timeout = 0; 591 timeout = 0;
530 retry = 0; 592 retry = 0;
531 seqno = 0; 593 seqno = 0;
532 sent = NOW; 594 sent = ev_now ();
595 stdhdr = false;
533 596
534 pkt = new dns_packet; 597 pkt = new dns_packet;
535 598
536 pkt->id = next_id (); 599 pkt->id = next_id ();
537} 600}
564 } 627 }
565} 628}
566 629
567void dns_snd::gen_stream_req (int seqno, byte_stream &stream) 630void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
568{ 631{
632 stdhdr = true;
569 this->seqno = seqno; 633 this->seqno = seqno;
570 634
571 timeout = NOW + INITIAL_TIMEOUT; 635 timeout = ev_now () + INITIAL_TIMEOUT;
572 636
573 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 637 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
574 pkt->qdcount = htons (1); 638 pkt->qdcount = htons (1);
575 639
576 int offs = 6*2; 640 int offs = 6*2;
577 int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); 641 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, 642 // 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 643 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
580 644
581 char enc[256], *encp = enc; 645 char enc[256], *encp = enc;
582 encode_header (enc, THISNODE->id, seqno); 646 encode_header (enc, THISNODE->id, seqno);
600 encp += lbllen; 664 encp += lbllen;
601 665
602 enclen -= lbllen; 666 enclen -= lbllen;
603 } 667 }
604 668
605 append_domain (*pkt, offs, THISNODE->domain); 669 append_domain (*pkt, offs, dns->c->conf->domain);
606 670
607 (*pkt)[offs++] = 0; 671 (*pkt)[offs++] = 0;
608 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; 672 (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
609 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 673 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
610 674
611 pkt->len = offs; 675 pkt->len = offs;
612} 676}
613 677
614void dns_snd::gen_syn_req (const dns_cfg &cfg) 678void dns_snd::gen_syn_req ()
615{ 679{
616 timeout = NOW + INITIAL_SYN_TIMEOUT; 680 timeout = ev_now () + INITIAL_SYN_TIMEOUT;
617 681
618 pkt->flags = htons (DEFAULT_CLIENT_FLAGS); 682 pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
619 pkt->qdcount = htons (1); 683 pkt->qdcount = htons (1);
620 684
621 int offs = 6*2; 685 int offs = 6 * 2;
622 686
623 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg)); 687 int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
624 688
625 assert (elen <= MAX_LBL_SIZE); 689 assert (elen <= MAX_LBL_SIZE);
626 690
627 (*pkt)[offs] = elen; 691 (*pkt)[offs] = elen;
628 offs += elen + 1; 692 offs += elen + 1;
629 append_domain (*pkt, offs, THISNODE->domain); 693 append_domain (*pkt, offs, dns->c->conf->domain);
630 694
631 (*pkt)[offs++] = 0; 695 (*pkt)[offs++] = 0;
632 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; 696 (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
633 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; 697 (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
634 698
657 delete pkt; 721 delete pkt;
658} 722}
659 723
660///////////////////////////////////////////////////////////////////////////// 724/////////////////////////////////////////////////////////////////////////////
661 725
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) 726dns_connection::dns_connection (connection *c)
688: c (c) 727: c (c)
689, rcvdq (MAX_BACKLOG * 2) 728, rcvdq (MAX_BACKLOG * 2)
690, snddq (MAX_BACKLOG * 2) 729, snddq (MAX_BACKLOG)
691, tw (this, &dns_connection::time_cb) 730, tw (this, &dns_connection::time_cb)
692{ 731{
693 vpn = c->vpn; 732 vpn = c->vpn;
694 733
695 established = false; 734 established = false;
696 735
697 rcvseq = sndseq = 0; 736 rcvseq = repseq = sndseq = 0;
698 737
699 last_sent = last_received = 0; 738 last_sent = last_received = 0;
700 poll_interval = MIN_POLL_INTERVAL; 739 poll_interval = 0.5; // starting here
701 send_interval = 0.2; // starting rate 740 send_interval = 0.5; // starting rate
741 min_latency = INITIAL_TIMEOUT;
702} 742}
703 743
704dns_connection::~dns_connection () 744dns_connection::~dns_connection ()
705{ 745{
706 for (vector<dns_rcv *>::iterator i = rcvpq.begin (); 746 for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
711 751
712void dns_connection::receive_rep (dns_rcv *r) 752void dns_connection::receive_rep (dns_rcv *r)
713{ 753{
714 if (r->datalen) 754 if (r->datalen)
715 { 755 {
716 last_received = NOW; 756 last_received = ev_now ();
717 tw.trigger (); 757 tw ();
718 758
719 poll_interval = send_interval; 759 poll_interval = send_interval;
720 } 760 }
721 else 761 else
722 { 762 {
723 poll_interval *= 1.1; 763 poll_interval *= 1.5;
764
724 if (poll_interval > MAX_POLL_INTERVAL) 765 if (poll_interval > MAX_POLL_INTERVAL)
725 poll_interval = MAX_POLL_INTERVAL; 766 poll_interval = MAX_POLL_INTERVAL;
726 } 767 }
727 768
728 rcvpq.push_back (r); 769 rcvpq.push_back (r);
731 772
732 // find next packet 773 // find next packet
733 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 774 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
734 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 775 if (SEQNO_EQ (rcvseq, (*i)->seqno))
735 { 776 {
777 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
736 // enter the packet into our input stream 778 // enter the packet into our input stream
737 r = *i; 779 r = *i;
738 780
739 // remove the oldest packet, look forward, as it's oldest first 781 // remove the oldest packet, look forward, as it's oldest first
740 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) 782 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
741 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 783 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
742 { 784 {
785 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
743 delete *j; 786 delete *j;
744 rcvpq.erase (j); 787 rcvpq.erase (j);
745 break; 788 break;
746 } 789 }
747 790
748 rcvseq = (rcvseq + 1) & SEQNO_MASK; 791 rcvseq = (rcvseq + 1) & SEQNO_MASK;
749 792
750 if (!rcvdq.put (r->data, r->datalen)) 793 if (!rcvdq.put (r->data, r->datalen))
794 {
795 slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
751 abort (); // MUST never overflow, can be caused by data corruption, TODO 796 abort (); // MUST never overflow, can be caused by data corruption, TODO
797 }
752 798
753 while (vpn_packet *pkt = rcvdq.get ()) 799 while (vpn_packet *pkt = rcvdq.get ())
754 { 800 {
755 sockinfo si; 801 sockinfo si;
756 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 802 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
757 803
758 vpn->recv_vpn_packet (pkt, si); 804 vpn->recv_vpn_packet (pkt, si);
759 805
760 delete pkt; 806 delete pkt;
761 } 807 }
775 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 821 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
776 822
777 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) 823 if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
778 && pkt.qdcount == htons (1)) 824 && pkt.qdcount == htons (1))
779 { 825 {
780 char qname[MAXSIZE]; 826 char qname [MAXSIZE];
781 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); 827 int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
782 828
783 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; 829 u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
784 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; 830 u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
785 831
786 pkt.qdcount = htons (1); 832 pkt.qdcount = htons (1);
787 pkt.ancount = 0; 833 pkt.ancount = 0;
788 pkt.nscount = 0; // should be self, as other nameservers reply like this 834 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 835 pkt.arcount = 0; // a record for self, as other nameservers reply like this
790 836
791 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); 837 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
792 838
793 int dlen = strlen (THISNODE->domain); 839 int dlen = strlen (THISNODE->domain);
794 840
795 if (qclass == RR_CLASS_IN 841 if (qclass == RR_CLASS_IN
796 && qlen > dlen + 1 842 && qlen > dlen + 1
797 && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) 843 && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
798 { 844 {
799 // now generate reply 845 // now generate reply
800 pkt.ancount = htons (1); // one answer RR 846 pkt.ancount = htons (1); // one answer RR
801 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 847 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
802 848
824 if (SEQNO_EQ ((*i)->seqno, seqno)) 870 if (SEQNO_EQ ((*i)->seqno, seqno))
825 { 871 {
826 // already seen that request: simply reply with the cached reply 872 // already seen that request: simply reply with the cached reply
827 dns_rcv *r = *i; 873 dns_rcv *r = *i;
828 874
829 slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id)); 875 slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
876
877 // refresh header & id, as the retry count could have changed
878 memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
879 r->pkt->id = pkt.id;
830 880
831 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 881 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
832 pkt.id = r->pkt->id; 882
833 goto duplicate_request; 883 goto duplicate_request;
834 } 884 }
835 885
836 // new packet, queue 886 // new packet, queue
837 rcv = new dns_rcv (seqno, data, datalen); 887 rcv = new dns_rcv (seqno, data, datalen);
838 dns->receive_rep (rcv); 888 dns->receive_rep (rcv);
839 } 889 }
840 890
891 {
841 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section 892 pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
842 893
843 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; 894 int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
844 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type 895 pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
845 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 896 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
846 pkt [offs++] = 0; pkt [offs++] = 0; 897 pkt [offs++] = 0; pkt [offs++] = 0;
847 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 898 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
848 899
849 int rdlen_offs = offs += 2; 900 int rdlen_offs = offs += 2;
850 901
902 if (dns)
903 {
851 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; 904 int dlen = ntohs (dns->cfg.max_size) - offs;
905
852 // bind doesn't compress well, so reduce further by one label length 906 // bind doesn't compress well, so reduce further by one label length
853 dlen -= qlen; 907 dlen -= qlen;
854 908
855 if (dns) 909 // only put data into in-order sequence packets, if
856 { 910 // we receive out-of-order packets we generate empty
857 while (dlen > 1 && !dns->snddq.empty ()) 911 // replies
912 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
913 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
858 { 914 {
915 dns->repseq = seqno;
916
917 while (dlen > 1 && !dns->snddq.empty ())
918 {
859 int txtlen = dlen <= 255 ? dlen - 1 : 255; 919 int txtlen = dlen <= 255 ? dlen - 1 : 255;
860 920
861 if (txtlen > dns->snddq.size ()) 921 if (txtlen > dns->snddq.size ())
862 txtlen = dns->snddq.size (); 922 txtlen = dns->snddq.size ();
863 923
864 pkt[offs++] = txtlen; 924 pkt[offs++] = txtlen;
865 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 925 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
866 offs += txtlen; 926 offs += txtlen;
867 dns->snddq.remove (txtlen); 927 dns->snddq.remove (txtlen);
868 928
869 dlen -= txtlen + 1; 929 dlen -= txtlen + 1;
930 }
870 } 931 }
871 932
872 // avoid empty TXT rdata 933 // avoid completely empty TXT rdata
873 if (offs == rdlen_offs) 934 if (offs == rdlen_offs)
874 pkt[offs++] = 0; 935 pkt[offs++] = 0;
875 936
876 slog (L_NOISE, "snddq %d", dns->snddq.size ()); 937 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
877 } 938 }
878 else 939 else
879 { 940 {
880 // send RST 941 // send RST
881 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 942 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
882 pkt [offs++] = CMD_IP_RST; 943 pkt [offs++] = CMD_IP_RST;
883 } 944 }
884 945
885 int rdlen = offs - rdlen_offs; 946 int rdlen = offs - rdlen_offs;
886 947
887 pkt [rdlen_offs - 2] = rdlen >> 8; 948 pkt [rdlen_offs - 2] = rdlen >> 8;
888 pkt [rdlen_offs - 1] = rdlen; 949 pkt [rdlen_offs - 1] = rdlen;
889 950
890 if (dns) 951 if (dns)
891 { 952 {
892 // now update dns_rcv copy 953 // now update dns_rcv copy
893 rcv->pkt->len = offs; 954 rcv->pkt->len = offs;
894 memcpy (rcv->pkt->at (0), pkt.at (0), offs); 955 memcpy (rcv->pkt->at (0), pkt.at (0), offs);
895 } 956 }
957 }
896 958
897 duplicate_request: ; 959 duplicate_request: ;
898 } 960 }
899 else 961 else
900 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 962 pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
912 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class 974 pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
913 pkt [offs++] = 0; pkt [offs++] = 0; 975 pkt [offs++] = 0; pkt [offs++] = 0;
914 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL 976 pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
915 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength 977 pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
916 978
917 slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client); 979 slog (L_INFO, _("DNS: client %d connects"), client);
918 980
919 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; 981 pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
920 pkt [offs++] = CMD_IP_REJ; 982 pkt [offs++] = CMD_IP_REJ;
921 983
922 if (0 < client && client <= conns.size ()) 984 if (0 < client && client <= conns.size ())
956 { 1018 {
957 dns_connection *dns = (*i)->dns; 1019 dns_connection *dns = (*i)->dns;
958 connection *c = dns->c; 1020 connection *c = dns->c;
959 int seqno = (*i)->seqno; 1021 int seqno = (*i)->seqno;
960 u8 data[MAXSIZE], *datap = data; 1022 u8 data[MAXSIZE], *datap = data;
1023 //printf ("rcv pkt %x\n", seqno);//D
961 1024
962 if ((*i)->retry) 1025 if ((*i)->retry)
963 { 1026 {
964 dns->send_interval *= 1.001; 1027 dns->send_interval *= 1.01;
965 if (dns->send_interval > MAX_SEND_INTERVAL) 1028 if (dns->send_interval > MAX_SEND_INTERVAL)
966 dns->send_interval = MAX_SEND_INTERVAL; 1029 dns->send_interval = MAX_SEND_INTERVAL;
967 } 1030 }
968 else 1031 else
969 { 1032 {
970#if 1 1033#if 0
971 dns->send_interval *= 0.9999; 1034 dns->send_interval *= 0.999;
972#endif 1035#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 1036 // the latency surely puts an upper bound on
977 // the minimum send interval 1037 // the minimum send interval
978 double latency = NOW - (*i)->sent; 1038 double latency = ev_now () - (*i)->sent;
979 1039
980 if (dns->send_interval > latency) 1040 if (latency < dns->min_latency)
981 dns->send_interval = latency; 1041 dns->min_latency = latency;
1042
1043 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1044 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1045
1046 if (dns->send_interval < conf.dns_send_interval)
1047 dns->send_interval = conf.dns_send_interval;
982 } 1048 }
983 1049
984 delete *i; 1050 delete *i;
985 dns_sndpq.erase (i); 1051 dns_sndpq.erase (i);
986 1052
1036 1102
1037 if (ip [0] == CMD_IP_1 1103 if (ip [0] == CMD_IP_1
1038 && ip [1] == CMD_IP_2 1104 && ip [1] == CMD_IP_2
1039 && ip [2] == CMD_IP_3) 1105 && ip [2] == CMD_IP_3)
1040 { 1106 {
1041 slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]); 1107 slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
1042 1108
1043 if (ip [3] == CMD_IP_RST) 1109 if (ip [3] == CMD_IP_RST)
1044 { 1110 {
1045 slog (L_DEBUG, _("got tunnel RST request")); 1111 slog (L_DEBUG, _("DNS: got tunnel RST request"));
1046 1112
1047 delete dns; c->dns = 0; 1113 delete dns; c->dns = 0;
1048 1114
1049 return; 1115 return;
1050 } 1116 }
1051 else if (ip [3] == CMD_IP_SYN) 1117 else if (ip [3] == CMD_IP_SYN)
1052 { 1118 {
1053 slog (L_DEBUG, _("got tunnel SYN reply, server likes us.")); 1119 slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
1054 dns->established = true; 1120 dns->established = true;
1055 } 1121 }
1056 else if (ip [3] == CMD_IP_REJ) 1122 else if (ip [3] == CMD_IP_REJ)
1057 { 1123 {
1058 slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting.")); 1124 slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
1059 abort (); 1125 abort ();
1060 } 1126 }
1061 else 1127 else
1062 slog (L_INFO, _("got unknown meta command %02x"), ip [3]); 1128 slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
1063 } 1129 }
1064 else 1130 else
1065 slog (L_INFO, _("got spurious a record %d.%d.%d.%d"), 1131 slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
1066 ip [0], ip [1], ip [2], ip [3]); 1132 ip [0], ip [1], ip [2], ip [3]);
1067 1133
1068 return; 1134 return;
1069 } 1135 }
1070 1136
1071 int client, rseqno; 1137 int client, rseqno;
1072 decode_header (qname, client, rseqno); 1138 decode_header (qname, client, rseqno);
1073 1139
1074 if (client != THISNODE->id) 1140 if (client != THISNODE->id)
1075 { 1141 {
1076 slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); 1142 slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
1077 datap = 0; 1143 datap = 0;
1078 } 1144 }
1079 else if (rseqno != seqno) 1145 else if (rseqno != seqno)
1080 { 1146 {
1081 slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); 1147 slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
1082 datap = 0; 1148 datap = 0;
1083 } 1149 }
1084 } 1150 }
1085 } 1151 }
1086 1152
1091 break; 1157 break;
1092 } 1158 }
1093} 1159}
1094 1160
1095void 1161void
1096vpn::dnsv4_ev (io_watcher &w, short revents) 1162vpn::dnsv4_ev (ev::io &w, int revents)
1097{ 1163{
1098 if (revents & EVENT_READ) 1164 if (revents & EV_READ)
1099 { 1165 {
1100 dns_packet *pkt = new dns_packet; 1166 dns_packet *pkt = new dns_packet;
1101 struct sockaddr_in sa; 1167 struct sockaddr_in sa;
1102 socklen_t sa_len = sizeof (sa); 1168 socklen_t sa_len = sizeof (sa);
1103 1169
1104 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); 1170 pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
1105 1171
1106 if (pkt->len > 0) 1172 if (pkt->len > 0)
1107 { 1173 {
1108 if (THISNODE->dns_port) 1174 if (ntohs (pkt->flags) & FLAG_RESPONSE)
1175 dnsv4_client (*pkt);
1176 else
1109 { 1177 {
1110 dnsv4_server (*pkt); 1178 dnsv4_server (*pkt);
1111 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); 1179 sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
1112 } 1180 }
1113 else
1114 dnsv4_client (*pkt);
1115 1181
1116 delete pkt; 1182 delete pkt;
1117 } 1183 }
1118 } 1184 }
1119} 1185}
1120 1186
1121bool 1187bool
1122connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1188vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1123{ 1189{
1190 int client = ntohl (si.host);
1191
1192 assert (0 < client && client <= conns.size ());
1193
1194 connection *c = conns [client - 1];
1195
1124 if (!dns) 1196 if (!c->dns)
1125 dns = new dns_connection (this); 1197 c->dns = new dns_connection (c);
1126 1198
1127 if (!dns->snddq.put (pkt)) 1199 if (c->dns->snddq.put (pkt))
1128 return false; 1200 c->dns->tw ();
1129 1201
1130 dns->tw.trigger (); 1202 // always return true even if the buffer overflows
1131
1132 return true; 1203 return true;
1133} 1204}
1134 1205
1135void 1206void
1136connection::dnsv4_reset_connection () 1207connection::dnsv4_reset_connection ()
1139} 1210}
1140 1211
1141#define NEXT(w) do { if (next > (w)) next = w; } while (0) 1212#define NEXT(w) do { if (next > (w)) next = w; } while (0)
1142 1213
1143void 1214void
1144dns_connection::time_cb (time_watcher &w) 1215dns_connection::time_cb (ev::timer &w, int revents)
1145{ 1216{
1146 // servers have to be polled 1217 // servers have to be polled
1147 if (THISNODE->dns_port) 1218 if (THISNODE->dns_port)
1148 return; 1219 return;
1149 1220
1150 // check for timeouts and (re)transmit 1221 // check for timeouts and (re)transmit
1151 tstamp next = NOW + poll_interval; 1222 tstamp next = ev::now () + poll_interval;
1152 dns_snd *send = 0; 1223 dns_snd *send = 0;
1153 1224
1154 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); 1225 for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
1155 i != vpn->dns_sndpq.end (); 1226 i != vpn->dns_sndpq.end ();
1156 ++i) 1227 ++i)
1157 { 1228 {
1158 dns_snd *r = *i; 1229 dns_snd *r = *i;
1159 1230
1160 if (r->timeout <= NOW) 1231 if (r->timeout <= ev_now ())
1161 { 1232 {
1162 if (!send) 1233 if (!send)
1163 { 1234 {
1164 send = r; 1235 send = r;
1165 1236
1166 r->retry++; 1237 r->retry++;
1167 r->timeout = NOW + r->retry; 1238 r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
1239 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
1240
1241 // the following code changes the query section a bit, forcing
1242 // the forwarder to generate a new request
1243 if (r->stdhdr)
1244 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1168 } 1245 }
1169 } 1246 }
1170 else 1247 else
1171 NEXT (r->timeout); 1248 NEXT (r->timeout);
1172 } 1249 }
1173 1250
1174 if (last_sent + send_interval <= NOW)
1175 {
1176 if (!send) 1251 if (!send)
1252 {
1253 // generate a new packet, if wise
1254
1255 if (!established)
1177 { 1256 {
1178 // generate a new packet, if wise
1179
1180 if (!established)
1181 {
1182 if (vpn->dns_sndpq.empty ()) 1257 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 { 1258 {
1192 send = new dns_snd (this); 1259 send = new dns_snd (this);
1260
1261 cfg.reset (THISNODE->id);
1262 send->gen_syn_req ();
1263 }
1264 }
1265 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1266 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1267 {
1268 if (last_sent + send_interval <= ev_now ())
1269 {
1270 //printf ("sending data request etc.\n"); //D
1271 if (!snddq.empty () || last_received + 1. > ev_now ())
1272 {
1273 poll_interval = send_interval;
1274 NEXT (ev_now () + send_interval);
1275 }
1276
1277 send = new dns_snd (this);
1193 send->gen_stream_req (sndseq, snddq); 1278 send->gen_stream_req (sndseq, snddq);
1279 send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
1280 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
1194 1281
1195 sndseq = (sndseq + 1) & SEQNO_MASK; 1282 sndseq = (sndseq + 1) & SEQNO_MASK;
1196 } 1283 }
1197 1284 else
1198 if (send) 1285 NEXT (last_sent + send_interval);
1199 vpn->dns_sndpq.push_back (send);
1200 } 1286 }
1201 1287
1202 if (send) 1288 if (send)
1203 { 1289 vpn->dns_sndpq.push_back (send);
1204 last_sent = NOW; 1290 }
1291
1292 if (send)
1293 {
1294 last_sent = ev_now ();
1205 sendto (vpn->dnsv4_fd, 1295 sendto (vpn->dnsv4_fd,
1206 send->pkt->at (0), send->pkt->len, 0, 1296 send->pkt->at (0), send->pkt->len, 0,
1207 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1297 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1208 }
1209 } 1298 }
1210 else
1211 NEXT (last_sent + send_interval);
1212 1299
1213 slog (L_NOISE, "pi %f si %f N %f (%d:%d)", 1300 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1214 poll_interval, send_interval, next - NOW, 1301 poll_interval, send_interval, next - ev_now (),
1215 vpn->dns_sndpq.size (), snddq.size ()); 1302 vpn->dns_sndpq.size (), snddq.size (),
1303 rcvpq.size ());
1216 1304
1217 // TODO: no idea when this happens, but when next < NOW, we have a problem 1305 // TODO: no idea when this happens, but when next < ev_now (), we have a problem
1306 // doesn't seem to happen anymore
1218 if (next < NOW + 0.0001) 1307 if (next < ev_now () + 0.001)
1219 next = NOW + 0.1; 1308 next = ev_now () + 0.1;
1220 1309
1221 w.start (next); 1310 w.start (next - ev_now ());
1222} 1311}
1223 1312
1224#endif 1313#endif
1225 1314

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