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/cvs/gvpe/src/vpn_dns.C
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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.5 by pcg, Thu Mar 3 07:24:57 2005 UTC vs.
Revision 1.7 by pcg, Thu Mar 3 16:54:34 2005 UTC

1/* 1/*
2 vpn_dns.C -- handle the dns tunnel part of the protocol. 2 vpn_dns.C -- handle the dns tunnel part of the protocol.
3 Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com> 3 Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de>
4 4
5 This file is part of GVPE.
6
5 This program is free software; you can redistribute it and/or modify 7 GVPE is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by 8 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or 9 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version. 10 (at your option) any later version.
9 11
10 This program is distributed in the hope that it will be useful, 12 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details. 15 GNU General Public License for more details.
14 16
15 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
16 along with this program; if not, write to the Free Software 18 along with gvpe; if not, write to the Free Software
17 Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18*/ 20*/
19 21
20#include "config.h" 22#include "config.h"
21 23
… …
51 53
52#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well 54#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
53// 240 leaves about 4 bytes of server reply data 55// 240 leaves about 4 bytes of server reply data
54// every two request byte sless give room for one reply byte 56// every two request byte sless give room for one reply byte
55 57
58// seqno has 12 bits, but the lower bit is always left as zero
59// as bind caches ttl=0 records and we have to generate
60// sequence numbers that always differ case-insensitively
56#define SEQNO_MASK 0xffff 61#define SEQNO_MASK 0x07ff
57 62
58/* 63/*
59 64
60protocol, in shorthand :) 65protocol, in shorthand :)
61 66
… …
90 static int decode (u8 *dst, char *src, int len); 95 static int decode (u8 *dst, char *src, int len);
91 96
92 dns64 (); 97 dns64 ();
93} dns64; 98} dns64;
94 99
95const char dns64::encode_chars[64 + 1] = "_4B9dLphHzrqQmGjkTbJt5svlZX8xSaReEYfwKgF1DP2W6NyVOU70IouACcMn3i-"; 100// the following sequence has been crafted to
101// a) look somewhat random
102// b) the even (and odd) indices never share the same character as upper/lowercase
103const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
96s8 dns64::decode_chars[256]; 104s8 dns64::decode_chars[256];
97 105
98dns64::dns64 () 106dns64::dns64 ()
99{ 107{
100 for (int i = 0; i < 64; i++) 108 for (int i = 0; i < 64; i++)
… …
218} 226}
219 227
220vpn_packet *byte_stream::get () 228vpn_packet *byte_stream::get ()
221{ 229{
222 int len = (data [0] << 8) | data [1]; 230 int len = (data [0] << 8) | data [1];
223
224 printf ("get len %d, fill %d\n", len, fill);//D
225 231
226 if (len > MAXSIZE && fill >= 2) 232 if (len > MAXSIZE && fill >= 2)
227 abort (); // TODO handle this gracefully, connection reset 233 abort (); // TODO handle this gracefully, connection reset
228 234
229 if (fill < len + 2) 235 if (fill < len + 2)
… …
356 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra 362 // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
357 363
358 u8 data[256]; //TODO 364 u8 data[256]; //TODO
359 365
360 data[0] = THISNODE->id; //TODO 366 data[0] = THISNODE->id; //TODO
361 data[1] = seqno >> 8; //TODO 367 data[1] = seqno >> 7; //TODO
362 data[2] = seqno; //TODO 368 data[2] = seqno << 1; //TODO
363 369
364 int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3; 370 int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
365 371
366 if (datalen > stream->size ()) 372 if (datalen > stream->size ())
367 datalen = stream->size (); 373 datalen = stream->size ();
… …
419 int seqno; 425 int seqno;
420 dns_packet *pkt; // reply packet 426 dns_packet *pkt; // reply packet
421 u8 data [MAXSIZE]; // actually part of the reply packet... 427 u8 data [MAXSIZE]; // actually part of the reply packet...
422 int datalen; 428 int datalen;
423 429
424 dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen); 430 dns_rcv (int seqno, u8 *data, int datalen);
425 ~dns_rcv (); 431 ~dns_rcv ();
426}; 432};
427 433
428dns_rcv::dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen) 434dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
429: seqno (seqno), pkt (new dns_packet), datalen (datalen) 435: seqno (seqno), pkt (new dns_packet), datalen (datalen)
430{ 436{
431 memcpy (this->data, data, datalen); 437 memcpy (this->data, data, datalen);
432 pkt->len = req->len;
433 memcpy (pkt->at (0), req->at (0), req->len);
434} 438}
435 439
436dns_rcv::~dns_rcv () 440dns_rcv::~dns_rcv ()
437{ 441{
438 delete pkt; 442 delete pkt;
… …
481 si.host = 0; si.port = 0; si.prot = PROT_DNSv4; 485 si.host = 0; si.port = 0; si.prot = PROT_DNSv4;
482 486
483 vpn->recv_vpn_packet (pkt, si); 487 vpn->recv_vpn_packet (pkt, si);
484 } 488 }
485 } 489 }
486 else if ((u32)dns_rcvseq - MAX_WINDOW - (u32)(*i)->seqno < MAX_WINDOW * 2) 490 else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)
487 { 491 {
492 //D
493 //abort();
494 printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
488 dns_rcvpq.erase (i); 495 dns_rcvpq.erase (i);
489 goto redo; 496 goto redo;
490 } 497 }
491} 498}
492 499
… …
526 // correct class, domain: parse 533 // correct class, domain: parse
527 u8 data[MAXSIZE]; 534 u8 data[MAXSIZE];
528 int datalen = dns64::decode (data, qname, qlen - dlen - 1); 535 int datalen = dns64::decode (data, qname, qlen - dlen - 1);
529 536
530 int client = data[0]; 537 int client = data[0];
531 int seqno = ((data[1] << 8) | data[2]) & SEQNO_MASK; 538 int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;
532 539
533 if (0 < client && client <= conns.size ()) 540 if (0 < client && client <= conns.size ())
534 { 541 {
535 connection *c = conns [client - 1]; 542 connection *c = conns [client - 1];
543
544 redo:
536 545
537 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin (); 546 for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
538 i != c->dns_rcvpq.end (); 547 i != c->dns_rcvpq.end ();
539 ++i) 548 ++i)
540 if ((*i)->seqno == seqno) 549 if ((*i)->seqno == seqno)
541 { 550 {
542 // already seen that request, just reply with the original reply 551 // already seen that request: simply reply with the cached reply
543 dns_rcv *r = *i; 552 dns_rcv *r = *i;
553
554 printf ("DUPLICATE %d\n", htons (r->pkt->id));//D
544 555
545 offs = r->pkt->len; 556 offs = r->pkt->len;
546 memcpy (pkt->at (0), r->pkt->at (0), offs); 557 memcpy (pkt->at (0), r->pkt->at (0), offs);
547 goto duplicate_request; 558 goto duplicate_request;
548 } 559 }
549 560
550 // new packet, queue 561 // new packet, queue
551 c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data + 3, datalen - 3)); 562 dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);
563 c->dnsv4_receive_rep (rcv);
552 564
553 // now generate reply 565 // now generate reply
554 pkt->ancount = htons (1); // one answer RR 566 pkt->ancount = htons (1); // one answer RR
555 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); 567 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
556 568
… …
594 int rdlen = offs - rdlen_offs; 606 int rdlen = offs - rdlen_offs;
595 607
596 (*pkt) [rdlen_offs - 2] = rdlen >> 8; 608 (*pkt) [rdlen_offs - 2] = rdlen >> 8;
597 (*pkt) [rdlen_offs - 1] = rdlen; 609 (*pkt) [rdlen_offs - 1] = rdlen;
598 610
611 // now update dns_rcv copy
612 rcv->pkt->len = offs;
613 memcpy (rcv->pkt->at (0), pkt->at (0), offs);
614
599 duplicate_request: ; 615 duplicate_request: ;
600 } 616 }
601 else 617 else
602 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); 618 pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
603 } 619 }
604 }
605 else
606 offs = pkt->len;
607 620
608 pkt->len = offs; 621 pkt->len = offs;
622 }
623
609 return pkt; 624 return pkt;
610} 625}
611 626
612void 627void
613vpn::dnsv4_client (dns_packet *pkt) 628vpn::dnsv4_client (dns_packet *pkt)
… …
673 } 688 }
674 689
675 } 690 }
676 } 691 }
677 692
678 if (datap != data) 693 // todo: pkt now used
679 printf ("%02x %02x %02x %02x\n",
680 data[0],
681 data[1],
682 data[2],
683 data[3]);
684
685 printf ("recv %d,%d\n", pkt->id, seqno, datap - data);//D
686 c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data, datap - data)); 694 c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));
687 695
688 break; 696 break;
689 } 697 }
690 698
691 delete pkt; 699 delete pkt;

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