[ViewVC] Diff of: cvs/gvpe/src/vpn

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.2 by pcg, Tue Mar 1 04:38:21 2005 UTC vs.
Revision 1.8 by pcg, Fri Mar 4 03:43:09 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
35	#include <unistd.h>	37	#include <unistd.h>
36	#include <fcntl.h>	38	#include <fcntl.h>
37		39
38	#include <map>	40	#include <map>
39		41
		42	#include <gmp.h>
		43
40	#include "netcompat.h"	44	#include "netcompat.h"
41		45
42	#include "vpn.h"	46	#include "vpn.h"
43
44	#if ENABLE_HTTP_PROXY
45	# include "conf.h"
46	#endif
47		47
48	#define MIN_RETRY 1.	48	#define MIN_RETRY 1.
49	#define MAX_RETRY 60.	49	#define MAX_RETRY 60.
50		50
51	#define SERVER conf.dns_port	51	#define MAX_OUTSTANDING 400 // max. outstanding requests
		52	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING
		53	#define MAX_RATE 10000 // requests/s
		54	#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE
52		55
53	/*	56	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
		57	// 240 leaves about 4 bytes of server reply data
		58	// every two request byte sless give room for one reply byte
54		59
55	protocol, in shorthand :)	60	// seqno has 12 bits (3 bytes a 4 bits in the header)
56		61	#define SEQNO_MASK 0x7fff
57	client -> server <req> ANY?	62	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
58	server -> client <req> TXT <rep>
59
60	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
61	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
62
63	if <client-id> is zero, the connection will be configured:
64
65	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
66
67	*/
68		63
69	#define MAX_LBL_SIZE 63	64	#define MAX_LBL_SIZE 63
70	#define MAX_PKT_SIZE 512	65	#define MAX_PKT_SIZE 512
71		66
72	#define RR_TYPE_TXT 16	67	#define RR_TYPE_TXT 16
73	#define RR_TYPE_ANY 255	68	#define RR_TYPE_ANY 255
74	#define RR_CLASS_IN 1	69	#define RR_CLASS_IN 1
75		70
		71	// works for cmaps up to 255 (not 256!)
		72	struct charmap
		73	{
		74	enum { INVALID = (u8)255 };
		75
		76	char encode [256]; // index => char
		77	u8 decode [256]; // char => index
		78	unsigned int size;
		79
		80	charmap (const char *cmap);
		81	};
		82
		83	charmap::charmap (const char *cmap)
		84	{
		85	char *enc = encode;
		86	u8 *dec = decode;
		87
		88	memset (enc, (char) 0, 256);
		89	memset (dec, (char)INVALID, 256);
		90
		91	for (size = 0; cmap [size]; size++)
		92	{
		93	enc [size] = cmap [size];
		94	dec [(u8)enc [size]] = size;
		95	}
		96
		97	assert (size < 256);
		98	}
		99
		100	#define MAX_DEC_LEN 500
		101	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		102	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		103
		104	// ugly. minimum base is 16(!)
		105	struct basecoder
		106	{
		107	charmap cmap;
		108	unsigned int enc_len [MAX_DEC_LEN];
		109	unsigned int dec_len [MAX_ENC_LEN];
		110
		111	unsigned int encode_len (unsigned int len);
		112	unsigned int decode_len (unsigned int len);
		113
		114	unsigned int encode (char dst, u8 src, unsigned int len);
		115	unsigned int decode (u8 dst, char src, unsigned int len);
		116
		117	basecoder (const char *cmap);
		118	};
		119
		120	basecoder::basecoder (const char *cmap)
		121	: cmap (cmap)
		122	{
		123	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
		124	{
		125	u8 src [MAX_DEC_LEN];
		126	u8 dst [MAX_ENC_LEN];
		127
		128	memset (src, 255, len);
		129
		130	mp_limb_t m [MAX_LIMBS];
		131	mp_size_t n;
		132
		133	n = mpn_set_str (m, src, len, 256);
		134	n = mpn_get_str (dst, this->cmap.size, m, n);
		135
		136	for (int i = 0; !dst [i]; ++i)
		137	n--;
		138
		139	enc_len [len] = n;
		140	dec_len [n] = len;
		141	}
		142	}
		143
		144	unsigned int basecoder::encode_len (unsigned int len)
		145	{
		146	return enc_len [len];
		147	}
		148
		149	unsigned int basecoder::decode_len (unsigned int len)
		150	{
		151	while (len && !dec_len [len])
		152	--len;
		153
		154	return dec_len [len];
		155	}
		156
		157	unsigned int basecoder::encode (char dst, u8 src, unsigned int len)
		158	{
		159	if (!len)
		160	return 0;
		161
		162	int elen = encode_len (len);
		163
		164	mp_limb_t m [MAX_LIMBS];
		165	mp_size_t n;
		166
		167	u8 dst_ [MAX_ENC_LEN];
		168
		169	n = mpn_set_str (m, src, len, 256);
		170	n = mpn_get_str (dst_, cmap.size, m, n);
		171
		172	int plen = elen; // for padding
		173
		174	while (n < plen)
		175	{
		176	*dst++ = cmap.encode [0];
		177	plen--;
		178	}
		179
		180	for (unsigned int i = n - plen; i < n; ++i)
		181	*dst++ = cmap.encode [dst_ [i]];
		182
		183	return elen;
		184	}
		185
		186	unsigned int basecoder::decode (u8 dst, char src, unsigned int len)
		187	{
		188	if (!len)
		189	return 0;
		190
		191	u8 src_ [MAX_ENC_LEN];
		192	unsigned int elen = 0;
		193
		194	while (len--)
		195	{
		196	u8 val = cmap.decode [(u8)*src++];
		197
		198	if (val != charmap::INVALID)
		199	src_ [elen++] = val;
		200	}
		201
		202	int dlen = decode_len (elen);
		203
		204	mp_limb_t m [MAX_LIMBS];
		205	mp_size_t n;
		206
		207	u8 dst_ [MAX_DEC_LEN];
		208
		209	n = mpn_set_str (m, src_, elen, cmap.size);
		210	n = mpn_get_str (dst_, 256, m, n);
		211
		212	if (n < dlen)
		213	{
		214	memset (dst, 0, dlen - n);
		215	memcpy (dst + dlen - n, dst_, n);
		216	}
		217	else
		218	memcpy (dst, dst_ + n - dlen, dlen);
		219
		220	return dlen;
		221	}
		222
		223	#if 0
		224	struct test { test (); } test;
		225
		226	test::test ()
		227	{
		228	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		229
		230	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		231	static char enc[200];
		232	static u8 dec[200];
		233
		234	for (int i = 1; i < 20; i++)
		235	{
		236	int elen = cdc.encode (enc, in, i);
		237	int dlen = cdc.decode (dec, enc, elen);
		238
		239	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
		240	}
		241	abort ();
		242	}
		243	#endif
		244
		245	// the following sequence has been crafted to
		246	// a) look somewhat random
		247	// b) the even (and odd) indices never share the same character as upper/lowercase
76	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	248	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)
77	struct dns64	249	// the other sequences are obviously derived
78	{	250	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
79	static const char encode_chars[64 + 1];	251	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
80	static s8 decode_chars[256];	252	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		253	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
81		254
82	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	255	/////////////////////////////////////////////////////////////////////////////
83	static int decode_len (int bytes) { return (bytes * 6) / 8; }
84	static void encode (char dst, u8 src, int len);
85	static void decode (u8 dst, char src, int len);
86		256
87	dns64 ();	257	#define HDRSIZE 6
88	} dns64;
89		258
90	const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ";	259	inline void encode_header (char *data, int clientid, int seqno)
91	s8 dns64::decode_chars[256];
92
93	dns64::dns64 ()
94	{	260	{
95	for (int i = 0; i < 64; i++)	261	u8 hdr[3] = { clientid, seqno >> 8, seqno };
96	decode_chars [encode_chars [i]] = i + 1;
97	}
98		262
99	void dns64::encode (char dst, u8 src, int len)	263	assert (clientid < 256);
100	{
101	// slow, but easy to debug
102	unsigned int accum, bits = 0;
103		264
104	while (len--)	265	cdc26.encode (data, hdr, 3);
105	{
106	accum <<= 8;
107	accum \|= *src++;
108	bits += 8;
109
110	while (bits >= 6)
111	{
112	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];
113	bits -= 6;
114	}
115	}
116
117	if (bits)
118	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
119	}	266	}
120		267
121	void dns64::decode (u8 dst, char src, int len)	268	inline void decode_header (char *data, int &clientid, int &seqno)
122	{	269	{
123	// slow, but easy to debug	270	u8 hdr[3];
124	unsigned int accum, bits = 0;
125		271
126	while (len--)	272	cdc26.decode (hdr, data, HDRSIZE);
127	{
128	s8 chr = decode_chars [(u8)*src++];
129		273
		274	printf ("DEC %02x %02x %02x %02x\n", hdr[0], hdr[1], hdr[2], hdr[3]);
130		275
131	if (!chr)	276	clientid = hdr[0];
132	break;	277	seqno = (hdr[1] << 8) \| hdr[2];
133
134	accum <<= 6;
135	accum \|= chr - 1;
136	bits += 6;
137
138	while (bits >= 8)
139	{
140	*dst++ = accum >> (bits - 8);
141	bits -= 8;
142	}
143	}
144	}	278	}
		279
		280	/////////////////////////////////////////////////////////////////////////////
		281
		282	struct byte_stream
		283	{
		284	u8 *data;
		285	int maxsize;
		286	int fill;
		287
		288	byte_stream (int maxsize);
		289	~byte_stream ();
		290
		291	bool empty () { return !fill; }
		292	int size () { return fill; }
		293
		294	bool put (u8 *data, unsigned int datalen);
		295	bool put (vpn_packet *pkt);
		296	vpn_packet *get ();
		297
		298	u8 *begin () { return data; }
		299	void remove (int count);
		300	};
		301
		302	byte_stream::byte_stream (int maxsize)
		303	: maxsize (maxsize), fill (0)
		304	{
		305	data = new u8 [maxsize];
		306	}
		307
		308	byte_stream::~byte_stream ()
		309	{
		310	delete data;
		311	}
		312
		313	void byte_stream::remove (int count)
		314	{
		315	if (count > fill)
		316	abort ();
		317
		318	memmove (data, data + count, fill -= count);
		319	}
		320
		321	bool byte_stream::put (u8 *data, unsigned int datalen)
		322	{
		323	if (maxsize - fill < datalen)
		324	return false;
		325
		326	memcpy (this->data + fill, data, datalen); fill += datalen;
		327
		328	return true;
		329	}
		330
		331	bool byte_stream::put (vpn_packet *pkt)
		332	{
		333	if (maxsize - fill < pkt->len + 2)
		334	return false;
		335
		336	data [fill++] = pkt->len >> 8;
		337	data [fill++] = pkt->len;
		338
		339	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;
		340
		341	return true;
		342	}
		343
		344	vpn_packet *byte_stream::get ()
		345	{
		346	int len = (data [0] << 8) \| data [1];
		347
		348	if (len > MAXSIZE && fill >= 2)
		349	abort (); // TODO handle this gracefully, connection reset
		350
		351	if (fill < len + 2)
		352	return 0;
		353
		354	vpn_packet *pkt = new vpn_packet;
		355
		356	pkt->len = len;
		357	memcpy (&((*pkt)[0]), data + 2, len);
		358	remove (len + 2);
		359
		360	return pkt;
		361	}
		362
		363	/////////////////////////////////////////////////////////////////////////////
145		364
146	#define FLAG_QUERY ( 0 << 15)	365	#define FLAG_QUERY ( 0 << 15)
147	#define FLAG_RESPONSE ( 1 << 15)	366	#define FLAG_RESPONSE ( 1 << 15)
148	#define FLAG_OP_MASK (15 << 14)	367	#define FLAG_OP_MASK (15 << 14)
149	#define FLAG_OP_QUERY ( 0 << 11)	368	#define FLAG_OP_QUERY ( 0 << 11)
150	#define FLAG_AA ( 1 << 10)	369	#define FLAG_AA ( 1 << 10)
151	#define FLAG_TC ( 1 << 9)	370	#define FLAG_TC ( 1 << 9)
152	#define FLAG_RD ( 1 << 8)	371	#define FLAG_RD ( 1 << 8)
153	#define FLAG_RA ( 1 << 7)	372	#define FLAG_RA ( 1 << 7)
		373	#define FLAG_AUTH ( 1 << 5)
154	#define FLAG_RCODE_MASK (15 << 0)	374	#define FLAG_RCODE_MASK (15 << 0)
155	#define FLAG_RCODE_OK ( 0 << 0)	375	#define FLAG_RCODE_OK ( 0 << 0)
156	#define FLAG_RCODE_FORMERR ( 1 << 0)	376	#define FLAG_RCODE_FORMERR ( 1 << 0)
157	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	377	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
158	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	378	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
159	#define FLAG_RCODE_REFUSED ( 5 << 0)	379	#define FLAG_RCODE_REFUSED ( 5 << 0)
160		380
161	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)	381	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)
162	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE \| FLAG_OP_QUERY \| FLAG_AA \| FLAG_RD)	382	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE \| FLAG_OP_QUERY \| FLAG_AA \| FLAG_RD \| FLAG_RA)
163		383
164	struct dns_packet : net_packet	384	struct dns_packet : net_packet
165	{	385	{
166	u16 id;	386	u16 id;
167	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	387	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
…		…
204	}	424	}
205		425
206	return data - orig;	426	return data - orig;
207	}	427	}
208		428
		429	/////////////////////////////////////////////////////////////////////////////
		430
		431	struct dns_req
		432	{
		433	dns_packet *pkt;
		434	tstamp next;
		435	int retry;
		436	connection *conn;
		437	int seqno;
		438
		439	dns_req (connection *c);
		440	void gen_stream_req (int seqno, byte_stream *stream);
		441	};
		442
		443	static u16 dns_id = 12098; // TODO: should be per-vpn
		444
		445	static u16 next_id ()
		446	{
		447	// the simplest lsfr with periodicity 65535 i could find
		448	dns_id = (dns_id << 1)
		449	\| (((dns_id >> 1)
		450	^ (dns_id >> 2)
		451	^ (dns_id >> 4)
		452	^ (dns_id >> 15)) & 1);
		453
		454	return dns_id;
		455	}
		456
		457	dns_req::dns_req (connection *c)
		458	: conn (c)
		459	{
		460	next = 0;
		461	retry = 0;
		462
		463	pkt = new dns_packet;
		464
		465	pkt->id = next_id ();
		466	}
		467
		468	void dns_req::gen_stream_req (int seqno, byte_stream *stream)
		469	{
		470	this->seqno = seqno;
		471
		472	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		473	pkt->qdcount = htons (1);
		474
		475	int offs = 6*2;
		476	int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2);
		477	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		478	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		479
		480	char enc[256], *encp = enc;
		481	encode_header (enc, THISNODE->id, seqno);
		482
		483	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		484
		485	if (datalen > stream->size ())
		486	datalen = stream->size ();
		487
		488	int enclen = cdc62.encode (enc + HDRSIZE, stream->begin (), datalen) + HDRSIZE;
		489
		490	printf ("cdc62.encode %d->%d:%02x %02x %02x %02x\n", datalen, enclen,
		491	stream->begin ()[0],
		492	stream->begin ()[1],
		493	stream->begin ()[2],
		494	stream->begin ()[3]);
		495
		496	stream->remove (datalen);
		497
		498	while (enclen)
		499	{
		500	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		501
		502	(*pkt)[offs++] = lbllen;
		503	memcpy (pkt->at (offs), encp, lbllen);
		504
		505	offs += lbllen;
		506	encp += lbllen;
		507
		508	enclen -= lbllen;
		509	}
		510
		511	const char *suffix = THISNODE->domain;
		512
		513	// add tunnel domain
		514	for (;;)
		515	{
		516	const char *end = strchr (suffix, '.');
		517
		518	if (!end)
		519	end = suffix + strlen (suffix);
		520
		521	int len = end - suffix;
		522
		523	(*pkt)[offs++] = len;
		524	memcpy (&((*pkt)[offs]), suffix, len);
		525	offs += len;
		526
		527	if (!*end)
		528	break;
		529
		530	suffix = end + 1;
		531	}
		532
		533	(*pkt)[offs++] = 0;
		534	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;
		535	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		536
		537	pkt->len = offs;
		538	}
		539
		540	struct dns_rcv
		541	{
		542	int seqno;
		543	dns_packet *pkt; // reply packet
		544	u8 data [MAXSIZE]; // actually part of the reply packet...
		545	int datalen;
		546
		547	dns_rcv (int seqno, u8 *data, int datalen);
		548	~dns_rcv ();
		549	};
		550
		551	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		552	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		553	{
		554	memcpy (this->data, data, datalen);
		555	}
		556
		557	dns_rcv::~dns_rcv ()
		558	{
		559	delete pkt;
		560	}
		561
		562	/////////////////////////////////////////////////////////////////////////////
		563
209	struct dns_cfg	564	struct dns_cfg
210	{	565	{
211	u8 id1, id2, id3;	566	u8 id1, id2, id3;
212	u8 def_ttl;	567	u8 def_ttl;
213	u8 unused1;	568	u8 unused1;
214	u16 max_size;	569	u16 max_size;
215	u8 flags1, flags2;	570	u8 flags1, flags2;
216	};	571	};
217		572
218	// reply to client-poll	573	void connection::dnsv4_receive_rep (struct dns_rcv *r)
219	void dnsv4_poll (dns_packet *pkt, int &offs)
220	{	574	{
221	int dlen = MAX_PKT_SIZE - offs - 2;	575	dns_rcvpq.push_back (r);
222		576
223	(*pkt) [offs++] = 0;	577	printf ("%d got inketc %d (%02x %02x %02x %02x)\n", THISNODE->id, r->seqno
224	(*pkt) [offs++] = 5;	578	,r->data[0]
225	memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5);	579	,r->data[1]
226	offs += 5;	580	,r->data[2]
		581	,r->data[3]
		582	);
		583	redo:
227		584
228	pkt->ancount = htons (1);	585	// find next packet
		586	for (vector<dns_rcv *>::iterator i = dns_rcvpq.end (); i-- != dns_rcvpq.begin (); )
		587	if (SEQNO_EQ (dns_rcvseq, (*i)->seqno))
		588	{
		589	// enter the packet into our input stream
		590	r = *i;
		591
		592	printf ("%d checking for older packet %d\n", THISNODE->id, dns_rcvseq);
		593	// remove the oldest packet, look forward, as it's oldest first
		594	for (vector<dns_rcv *>::iterator j = dns_rcvpq.begin (); j != dns_rcvpq.end (); ++j)
		595	if (SEQNO_EQ ((*j)->seqno, dns_rcvseq - MAX_WINDOW))
		596	{
		597	printf ("%d removing %d\n", THISNODE->id, (*j)->seqno);
		598	delete *j;
		599	dns_rcvpq.erase (j);
		600	break;
		601	}
		602
		603	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;
		604
		605	if (!dns_snddq && !dns_rcvdq)
		606	{
		607	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
		608	dns_snddq = new byte_stream (MAX_BACKLOG);
		609
		610	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
		611	}
		612
		613	if (!dns_rcvdq->put (r->data, r->datalen))
		614	abort (); // MUST never overflow, can be caused by data corruption, TODO
		615
		616	while (vpn_packet *pkt = dns_rcvdq->get ())
		617	{
		618	sockinfo si;
		619	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;
		620
		621	vpn->recv_vpn_packet (pkt, si);
		622	}
		623
		624	// check for further packets
		625	goto redo;
		626	}
		627	}
		628
		629	dns_packet *
		630	vpn::dnsv4_server (dns_packet *pkt)
		631	{
		632	u16 flags = ntohs (pkt->flags);
		633
		634	//memcpy (&((rep)[0]), &((pkt)[0]), pkt->len);
		635	int offs = 6 * 2; // skip header
		636
229	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);	637	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
230		638
231	printf ("we have room for %d bytes\n", dlen);	639	if (!(flags & (FLAG_RESPONSE \| FLAG_OP_MASK \| FLAG_TC))
		640	&& pkt->qdcount == htons (1))
		641	{
		642	char qname[MAXSIZE];
		643	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);
		644
		645	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];
		646	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];
		647
		648	pkt->qdcount = htons (1);
		649	pkt->ancount = 0;
		650	pkt->nscount = 0; // should be self, as other nameservers reply like this
		651	pkt->arcount = 0; // a record for self, as other nameservers reply like this
		652
		653	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_NXDOMAIN);
		654
		655	int dlen = strlen (THISNODE->domain);
		656
		657	if (qclass == RR_CLASS_IN
		658	&& (qtype == RR_TYPE_ANY \|\| qtype == RR_TYPE_TXT)
		659	&& qlen > dlen + 1 + HDRSIZE
		660	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
		661	{
		662	// correct class, domain: parse
		663	int client, seqno;
		664	decode_header (qname, client, seqno);
		665
		666	u8 data[MAXSIZE];
		667	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		668
		669	printf ("cdc62.decode %d(%d): %02x %02x %02x %02x\n",
		670	qlen - (dlen + 1 + HDRSIZE), datalen
		671	,data[0]
		672	,data[1]
		673	,data[2]
		674	,data[3]);
		675
		676	printf ("SRV got %d <%.*s>\n", seqno, qlen, qname + HDRSIZE);//D
		677	printf ("SRV got %d <%.*s>\n", seqno, qlen - (dlen + 1 + HDRSIZE), qname + HDRSIZE);//D
		678
		679	if (0 < client && client <= conns.size ())
		680	{
		681	connection *c = conns [client - 1];
		682
		683	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.end (); i-- != c->dns_rcvpq.begin (); )
		684	if (SEQNO_EQ ((*i)->seqno, seqno))
		685	{
		686	// already seen that request: simply reply with the cached reply
		687	dns_rcv r = i;
		688
		689	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D
		690
		691	memcpy (pkt->at (0), r->pkt->at (0), offs = r->pkt->len);
		692	pkt->id = r->pkt->id;
		693	goto duplicate_request;
		694	}
		695
		696	// new packet, queue
		697	dns_rcv *rcv = new dns_rcv (seqno, data, datalen);
		698	c->dnsv4_receive_rep (rcv);
		699
		700	// now generate reply
		701	pkt->ancount = htons (1); // one answer RR
		702	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);
		703
		704	(*pkt) [offs++] = 0xc0;
		705	(pkt) [offs++] = 6 2; // same as in query section
		706
		707	(pkt) [offs++] = RR_TYPE_TXT >> 8; (pkt) [offs++] = RR_TYPE_TXT;
		708	(pkt) [offs++] = RR_CLASS_IN >> 8; (pkt) [offs++] = RR_CLASS_IN;
		709
		710	(pkt) [offs++] = 0; (pkt) [offs++] = 0;
		711	(pkt) [offs++] = 0; (pkt) [offs++] = 0; // TTL
		712
		713	int dlen = MAX_PKT_SIZE - offs - 2;
		714
		715	// bind doesn't compress well, so reduce further by one label length
		716	dlen -= qlen;
		717
		718	int rdlen_offs = offs += 2;
		719
		720	while (c->dns_snddq
		721	&& !c->dns_snddq->empty ()
		722	&& dlen > 1)
		723	{
		724	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		725
		726	if (txtlen > c->dns_snddq->size ())
		727	txtlen = c->dns_snddq->size ();
		728
		729	(*pkt)[offs++] = txtlen;
		730	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);
		731	offs += txtlen;
		732	c->dns_snddq->remove (txtlen);
		733
		734	dlen -= txtlen + 1;
		735	}
		736
		737	// avoid empty TXT rdata
		738	if (offs == rdlen_offs)
		739	(*pkt)[offs++] = 0;
		740
		741	int rdlen = offs - rdlen_offs;
		742
		743	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
		744	(*pkt) [rdlen_offs - 1] = rdlen;
		745
		746	// now update dns_rcv copy
		747	rcv->pkt->len = offs;
		748	memcpy (rcv->pkt->at (0), pkt->at (0), offs);
		749
		750	duplicate_request: ;
		751	}
		752	else
		753	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		754	}
		755
		756	pkt->len = offs;
		757	}
		758
		759	return pkt;
		760	}
		761
		762	void
		763	vpn::dnsv4_client (dns_packet *pkt)
		764	{
		765	u16 flags = ntohs (pkt->flags);
		766	int offs = 6 * 2; // skip header
		767
		768	pkt->qdcount = ntohs (pkt->qdcount);
		769	pkt->ancount = ntohs (pkt->ancount);
		770
		771	// go through our request list and find the corresponding request
		772	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();
		773	i != dns_sndpq.end ();
		774	++i)
		775	if ((*i)->pkt->id == pkt->id)
		776	{
		777	connection c = (i)->conn;
		778	int seqno = (*i)->seqno;
		779	u8 data[MAXSIZE], *datap = data;
		780
		781	delete *i;
		782	dns_sndpq.erase (i);
		783
		784	if (flags & (FLAG_RESPONSE \| FLAG_OP_MASK \| FLAG_TC))
		785	{
		786	char qname[MAXSIZE];
		787
		788	while (pkt->qdcount-- && offs < MAXSIZE - 4)
		789	{
		790	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);
		791	offs += 4; // skip qtype, qclass
		792	}
		793
		794	while (pkt->ancount-- && offs < MAXSIZE - 10)
		795	{
		796	int qlen = //D
		797	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);
		798
		799	printf ("got reply to <%.*s>\n", qlen, qname);//D
		800
		801	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];
		802	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];
		803	u32 ttl = (*pkt) [offs++] << 24;
		804	ttl \|= (*pkt) [offs++] << 16;
		805	ttl \|= (*pkt) [offs++] << 8;
		806	ttl \|= (*pkt) [offs++];
		807
		808	u16 rdlen = (pkt) [offs++] << 8; rdlen \|= (pkt) [offs++];
		809
		810	if (rdlen <= MAXSIZE - offs)
		811	{
		812	// decode bytes, finally
		813
		814	while (rdlen)
		815	{
		816	int txtlen = (*pkt) [offs++];
		817
		818	assert (txtlen + offs < MAXSIZE - 1);
		819
		820	memcpy (datap, pkt->at (offs), txtlen);
		821	datap += txtlen; offs += txtlen;
		822
		823	rdlen -= txtlen + 1;
		824	}
		825
		826	}
		827
		828	}
		829	}
		830
		831	// todo: pkt now used
		832	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));
		833
		834	break;
		835	}
		836
		837	delete pkt;
232	}	838	}
233		839
234	void	840	void
235	vpn::dnsv4_ev (io_watcher &w, short revents)	841	vpn::dnsv4_ev (io_watcher &w, short revents)
236	{	842	{
…		…
238	{	844	{
239	dns_packet *pkt = new dns_packet;	845	dns_packet *pkt = new dns_packet;
240	struct sockaddr_in sa;	846	struct sockaddr_in sa;
241	socklen_t sa_len = sizeof (sa);	847	socklen_t sa_len = sizeof (sa);
242		848
243	int len = recvfrom (w.fd, &((pkt)[0]), MAXSIZE, 0, (sockaddr )&sa, &sa_len);	849	pkt->len = recvfrom (w.fd, &((pkt)[0]), MAXSIZE, 0, (sockaddr )&sa, &sa_len);
244	pkt->len = len;
245		850
246	u16 flags = ntohs (pkt->flags);	851	if (pkt->len > 0)
247
248	if (THISNODE->dns_port)
249	{	852	{
250	// server	853	if (pkt->flags & htons (FLAG_TC))
251	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
252
253	int offs = 6 * 2; // skip header
254
255	if (!(flags & (FLAG_RESPONSE \| FLAG_OP_MASK \| FLAG_TC))
256	&& pkt->qdcount == htons (1))
257	{	854	{
258	char qname[MAXSIZE];	855	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));
259	int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs);	856	//TODO connection reset
260
261	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len,
262	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
263
264	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];
265	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];
266
267	pkt->qdcount = htons (1);
268	pkt->ancount = 0;
269	pkt->nscount = 0; // should be self, as other nameservers reply like this
270	pkt->arcount = 0; // a record for self, as other nameservers reply like this
271
272	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_NXDOMAIN);
273
274	int dlen = strlen (THISNODE->domain);
275
276	if (qclass == RR_CLASS_IN
277	&& (qtype == RR_TYPE_ANY \|\| qtype == RR_TYPE_TXT)
278	&& qlen > dlen + 1
279	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
280	{
281	// correct class, now generate reply
282	pkt->ancount = htons (1); // one answer RR
283
284	(*pkt) [offs++] = 0xc0;
285	(pkt) [offs++] = 6 2; // same as in query section
286
287	(pkt) [offs++] = RR_TYPE_TXT >> 8; (pkt) [offs++] = RR_TYPE_TXT;
288	(pkt) [offs++] = RR_CLASS_IN >> 8; (pkt) [offs++] = RR_CLASS_IN;
289
290	(pkt) [offs++] = 0; (pkt) [offs++] = 0;
291	(pkt) [offs++] = 0; (pkt) [offs++] = 0; // TTL
292
293	dnsv4_poll (pkt, offs);
294	printf ("correct class\n");
295	}
296	}	857	}
297		858
		859	if (THISNODE->dns_port)
		860	{
		861	pkt = dnsv4_server (pkt);
298	sendto (w.fd, &((pkt)[0]), offs, 0, (sockaddr )&sa, sa_len);	862	sendto (w.fd, &((pkt)[0]), pkt->len, 0, (sockaddr )&sa, sa_len);
		863	}
		864	else
		865	dnsv4_client (pkt);
299	}	866	}
300	else	867	}
		868	}
		869
		870	bool
		871	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
		872	{
		873	// never initialized
		874	if (!dns_snddq && !dns_rcvdq)
		875	{
		876	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
		877	dns_snddq = new byte_stream (MAX_BACKLOG);
		878
		879	//dns_rcvseq = dns_sndseq = 0;
		880
		881	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
		882	}
		883
		884	if (!dns_snddq->put (pkt))
		885	return false;
		886
		887	// start timer if neccessary
		888	if (!THISNODE->dns_port && !dnsv4_tw.active)
		889	dnsv4_cb (dnsv4_tw);
		890
		891	return true;
		892	}
		893
		894	void
		895	connection::dnsv4_cb (time_watcher &w)
		896	{
		897	// check for timeouts and (re)transmit
		898	tstamp next = NOW + 60;
		899	dns_req *send = 0;
		900
		901	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();
		902	i != vpn->dns_sndpq.end ();
		903	++i)
		904	{
		905	dns_req r = i;
		906
		907	if (r->next <= NOW)
301	{	908	{
302	// client	909	if (!send)
		910	{
		911	send = r;
		912
		913	if (r->retry)//D
		914	printf ("req %d:%d, retry %d\n", r->seqno, r->pkt->id, r->retry);
		915	r->retry++;
		916	r->next = NOW + r->retry;
		917	}
303	}	918	}
		919
		920	if (r->next < next)
		921	next = r->next;
		922	}
		923
		924	if (!send
		925	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
304	}	926	{
305	}	927	send = new dns_req (this);
		928	send->gen_stream_req (dns_sndseq, dns_snddq);
		929	vpn->dns_sndpq.push_back (send);
306		930
307	bool	931	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
308	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	932	}
309	{	933
310	//return i->send_packet (pkt, tos);	934	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
		935
		936	if (send)
		937	{
		938	dns_packet *pkt = send->pkt;
		939
		940	next = min_next;
		941
		942	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
		943	}
		944	else if (next < min_next)
		945	next = min_next;
		946
		947	w.start (next);
311	}	948	}
312		949
313	#endif	950	#endif
314		951

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Comparing gvpe/src/vpn_dns.C (file contents): Revision 1.2 by pcg, Tue Mar 1 04:38:21 2005 UTC vs. Revision 1.8 by pcg, Fri Mar 4 03:43:09 2005 UTC

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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.2 by pcg, Tue Mar 1 04:38:21 2005 UTC vs.
Revision 1.8 by pcg, Fri Mar 4 03:43:09 2005 UTC