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

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.1 by pcg, Fri Apr 2 14:42:45 2004 UTC vs.
Revision 1.14 by pcg, Fri Mar 4 09:51:23 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		47
44	#if ENABLE_HTTP_PROXY	48	#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server is having data
45	# include "conf.h"	49	#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data
		50	#define ACTIVITY_INTERVAL 5.
		51
		52	#define INITIAL_TIMEOUT 1.
		53	#define INITIAL_SYN_TIMEOUT 2.
		54
		55	#define MIN_SEND_INTERVAL 0.01
		56	#define MAX_SEND_INTERVAL 0.5 // optimistic?
		57
		58	#define MAX_OUTSTANDING 40 // max. outstanding requests
		59	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING
		60	#define MAX_BACKLOG (100*1024) // size of protocol backlog, must be > MAXSIZE
		61
		62	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
		63	// 240 leaves about 4 bytes of server reply data
		64	// every two request byte sless give room for one reply byte
		65
		66	#define SEQNO_MASK 0xffff
		67	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
		68
		69	#define MAX_LBL_SIZE 63
		70	#define MAX_PKT_SIZE 512
		71
		72	#define RR_TYPE_A 1
		73	#define RR_TYPE_NULL 10
		74	#define RR_TYPE_TXT 16
		75	#define RR_TYPE_ANY 255
		76
		77	#define RR_CLASS_IN 1
		78
		79	#define CMD_IP_1 207
		80	#define CMD_IP_2 46
		81	#define CMD_IP_3 236
		82	#define CMD_IP_RST 29
		83	#define CMD_IP_SYN 113
		84	#define CMD_IP_REJ 32
		85
		86	// works for cmaps up to 255 (not 256!)
		87	struct charmap
		88	{
		89	enum { INVALID = (u8)255 };
		90
		91	char encode [256]; // index => char
		92	u8 decode [256]; // char => index
		93	unsigned int size;
		94
		95	charmap (const char *cmap);
		96	};
		97
		98	charmap::charmap (const char *cmap)
		99	{
		100	char *enc = encode;
		101	u8 *dec = decode;
		102
		103	memset (enc, (char) 0, 256);
		104	memset (dec, (char)INVALID, 256);
		105
		106	for (size = 0; cmap [size]; size++)
		107	{
		108	enc [size] = cmap [size];
		109	dec [(u8)enc [size]] = size;
		110	}
		111
		112	assert (size < 256);
		113	}
		114
		115	#define MAX_DEC_LEN 500
		116	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		117	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		118
		119	// ugly. minimum base is 16(!)
		120	struct basecoder
		121	{
		122	charmap cmap;
		123	unsigned int enc_len [MAX_DEC_LEN];
		124	unsigned int dec_len [MAX_ENC_LEN];
		125
		126	unsigned int encode_len (unsigned int len);
		127	unsigned int decode_len (unsigned int len);
		128
		129	unsigned int encode (char dst, u8 src, unsigned int len);
		130	unsigned int decode (u8 dst, char src, unsigned int len);
		131
		132	basecoder (const char *cmap);
		133	};
		134
		135	basecoder::basecoder (const char *cmap)
		136	: cmap (cmap)
		137	{
		138	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
		139	{
		140	u8 src [MAX_DEC_LEN];
		141	u8 dst [MAX_ENC_LEN];
		142
		143	memset (src, 255, len);
		144
		145	mp_limb_t m [MAX_LIMBS];
		146	mp_size_t n;
		147
		148	n = mpn_set_str (m, src, len, 256);
		149	n = mpn_get_str (dst, this->cmap.size, m, n);
		150
		151	for (int i = 0; !dst [i]; ++i)
		152	n--;
		153
		154	enc_len [len] = n;
		155	dec_len [n] = len;
		156	}
		157	}
		158
		159	unsigned int basecoder::encode_len (unsigned int len)
		160	{
		161	return enc_len [len];
		162	}
		163
		164	unsigned int basecoder::decode_len (unsigned int len)
		165	{
		166	while (len && !dec_len [len])
		167	--len;
		168
		169	return dec_len [len];
		170	}
		171
		172	unsigned int basecoder::encode (char dst, u8 src, unsigned int len)
		173	{
		174	if (!len \|\| len > MAX_DEC_LEN)
		175	return 0;
		176
		177	int elen = encode_len (len);
		178
		179	mp_limb_t m [MAX_LIMBS];
		180	mp_size_t n;
		181
		182	u8 dst_ [MAX_ENC_LEN];
		183
		184	n = mpn_set_str (m, src, len, 256);
		185	n = mpn_get_str (dst_, cmap.size, m, n);
		186
		187	int plen = elen; // for padding
		188
		189	while (n < plen)
		190	{
		191	*dst++ = cmap.encode [0];
		192	plen--;
		193	}
		194
		195	for (unsigned int i = n - plen; i < n; ++i)
		196	*dst++ = cmap.encode [dst_ [i]];
		197
		198	return elen;
		199	}
		200
		201	unsigned int basecoder::decode (u8 dst, char src, unsigned int len)
		202	{
		203	if (!len \|\| len > MAX_ENC_LEN)
		204	return 0;
		205
		206	u8 src_ [MAX_ENC_LEN];
		207	unsigned int elen = 0;
		208
		209	while (len--)
		210	{
		211	u8 val = cmap.decode [(u8)*src++];
		212
		213	if (val != charmap::INVALID)
		214	src_ [elen++] = val;
		215	}
		216
		217	int dlen = decode_len (elen);
		218
		219	mp_limb_t m [MAX_LIMBS];
		220	mp_size_t n;
		221
		222	u8 dst_ [MAX_DEC_LEN];
		223
		224	n = mpn_set_str (m, src_, elen, cmap.size);
		225	n = mpn_get_str (dst_, 256, m, n);
		226
		227	if (n < dlen)
		228	{
		229	memset (dst, 0, dlen - n);
		230	memcpy (dst + dlen - n, dst_, n);
		231	}
		232	else
		233	memcpy (dst, dst_ + n - dlen, dlen);
		234
		235	return dlen;
		236	}
		237
		238	#if 0
		239	struct test { test (); } test;
		240
		241	test::test ()
		242	{
		243	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		244
		245	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		246	static char enc[200];
		247	static u8 dec[200];
		248
		249	for (int i = 1; i < 20; i++)
		250	{
		251	int elen = cdc.encode (enc, in, i);
		252	int dlen = cdc.decode (dec, enc, elen);
		253
		254	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
		255	}
		256	abort ();
		257	}
46	#endif	258	#endif
47		259
48	#define MIN_RETRY 1.	260	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
49	#define MAX_RETRY 60.	261	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		262	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		263	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		264	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
50		265
51	#define SERVER conf.dns_port	266	/////////////////////////////////////////////////////////////////////////////
52		267
53	/*	268	#define HDRSIZE 6
54		269
55	protocol, in shorthand :)	270	inline void encode_header (char *data, int clientid, int seqno)
		271	{
		272	u8 hdr[3] = { clientid, seqno >> 8, seqno };
56		273
57	<cseqno> ANY? poll for more data	274	assert (clientid < 256);
58	=> TXT <sseqno><data>
59	<cseqno><data> TXT? send more data
60	=> TXT <empty>
61		275
62	sequence numbers are 12 bit, 9 bit packet-number and 3 bit fragment id (7	276	cdc26.encode (data, hdr, 3);
63	- id, actually) last fragment is sent first, however	277	}
64		278
65	*/	279	inline void decode_header (char *data, int &clientid, int &seqno)
		280	{
		281	u8 hdr[3];
		282
		283	cdc26.decode (hdr, data, HDRSIZE);
		284
		285	clientid = hdr[0];
		286	seqno = (hdr[1] << 8) \| hdr[2];
		287	}
		288
		289	/////////////////////////////////////////////////////////////////////////////
		290
		291	struct byte_stream
		292	{
		293	u8 *data;
		294	int maxsize;
		295	int fill;
		296
		297	byte_stream (int maxsize);
		298	~byte_stream ();
		299
		300	bool empty () { return !fill; }
		301	int size () { return fill; }
		302
		303	bool put (u8 *data, unsigned int datalen);
		304	bool put (vpn_packet *pkt);
		305	vpn_packet *get ();
		306
		307	u8 *begin () { return data; }
		308	void remove (int count);
		309	};
		310
		311	byte_stream::byte_stream (int maxsize)
		312	: maxsize (maxsize), fill (0)
		313	{
		314	data = new u8 [maxsize];
		315	}
		316
		317	byte_stream::~byte_stream ()
		318	{
		319	delete data;
		320	}
		321
		322	void byte_stream::remove (int count)
		323	{
		324	if (count > fill)
		325	abort ();
		326
		327	memmove (data, data + count, fill -= count);
		328	}
		329
		330	bool byte_stream::put (u8 *data, unsigned int datalen)
		331	{
		332	if (maxsize - fill < datalen)
		333	return false;
		334
		335	memcpy (this->data + fill, data, datalen); fill += datalen;
		336
		337	return true;
		338	}
		339
		340	bool byte_stream::put (vpn_packet *pkt)
		341	{
		342	if (maxsize - fill < pkt->len + 2)
		343	return false;
		344
		345	data [fill++] = pkt->len >> 8;
		346	data [fill++] = pkt->len;
		347
		348	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
		349
		350	return true;
		351	}
		352
		353	vpn_packet *byte_stream::get ()
		354	{
		355	unsigned int len = (data [0] << 8) \| data [1];
		356
		357	if (len > MAXSIZE && fill >= 2)
		358	abort (); // TODO handle this gracefully, connection reset
		359
		360	if (fill < len + 2)
		361	return 0;
		362
		363	vpn_packet *pkt = new vpn_packet;
		364
		365	pkt->len = len;
		366	memcpy (pkt->at (0), data + 2, len);
		367	remove (len + 2);
		368
		369	return pkt;
		370	}
		371
		372	/////////////////////////////////////////////////////////////////////////////
		373
		374	#define FLAG_QUERY ( 0 << 15)
		375	#define FLAG_RESPONSE ( 1 << 15)
		376	#define FLAG_OP_MASK (15 << 11)
		377	#define FLAG_OP_QUERY ( 0 << 11)
		378	#define FLAG_AA ( 1 << 10)
		379	#define FLAG_TC ( 1 << 9)
		380	#define FLAG_RD ( 1 << 8)
		381	#define FLAG_RA ( 1 << 7)
		382	#define FLAG_AUTH ( 1 << 5)
		383	#define FLAG_RCODE_MASK (15 << 0)
		384	#define FLAG_RCODE_OK ( 0 << 0)
		385	#define FLAG_RCODE_FORMERR ( 1 << 0)
		386	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
		387	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
		388	#define FLAG_RCODE_REFUSED ( 5 << 0)
		389
		390	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)
		391	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE \| FLAG_OP_QUERY \| FLAG_AA \| FLAG_RD \| FLAG_RA)
		392
		393	struct dns_cfg
		394	{
		395	static int next_uid;
		396
		397	u8 id1, id2, id3, id4;
		398	u8 version;
		399	u8 rrtype;
		400	u8 flags;
		401	u8 def_ttl;
		402	u8 rcv_cdc;
		403	u8 snd_cdc;
		404	u16 max_size;
		405	u16 client;
		406	u16 uid; // to make request unique
		407
		408	u8 reserved[8];
		409
		410	void reset (int clientid);
		411	bool valid ();
		412	};
		413
		414	int dns_cfg::next_uid;
		415
		416	void dns_cfg::reset (int clientid)
		417	{
		418	id1 = 'G';
		419	id2 = 'V';
		420	id3 = 'P';
		421	id4 = 'E';
		422
		423	version = 1;
		424
		425	rrtype = RR_TYPE_TXT;
		426	flags = 0;
		427	def_ttl = 0;
		428	rcv_cdc = 0;
		429	snd_cdc = 62;
		430	max_size = ntohs (MAX_PKT_SIZE);
		431	client = ntohs (clientid);
		432	uid = next_uid++;
		433
		434	memset (reserved, 0, 8);
		435	}
		436
		437	bool dns_cfg::valid ()
		438	{
		439	return id1 == 'G'
		440	&& id2 == 'V'
		441	&& id3 == 'P'
		442	&& id4 == 'E'
		443	&& version == 1
		444	&& flags == 0
		445	&& rcv_cdc == 0
		446	&& snd_cdc == 62
		447	&& max_size == ntohs (MAX_PKT_SIZE);
		448	}
		449
		450	struct dns_packet : net_packet
		451	{
		452	u16 id;
		453	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
		454	u16 qdcount, ancount, nscount, arcount;
		455
		456	u8 data[MAXSIZE - 6 * 2];
		457
		458	int decode_label (char *data, int size, int &offs);
		459	};
		460
		461	int dns_packet::decode_label (char *data, int size, int &offs)
		462	{
		463	char *orig = data;
		464
		465	memset (data, 0, size);
		466
		467	while (offs < size - 1)
		468	{
		469	u8 len = (*this)[offs++];
		470
		471	if (!len)
		472	break;
		473	else if (len < 64)
		474	{
		475	if (size < len + 1 \|\| offs + len >= MAXSIZE - 1)
		476	break;
		477
		478	memcpy (data, &((*this)[offs]), len);
		479
		480	data += len; size -= len; offs += len;
		481	*data++ = '.'; size--;
		482	}
		483	else
		484	{
		485	int offs2 = ((len & 63) << 8) + (*this)[offs++];
		486
		487	data += decode_label (data, size, offs2);
		488	break;
		489	}
		490	}
		491
		492	return data - orig;
		493	}
		494
		495	/////////////////////////////////////////////////////////////////////////////
		496
		497	struct 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
		512	static u16 dns_id = 12098; // TODO: should be per-vpn
		513
		514	static u16 next_id ()
		515	{
		516	// the simplest lsfr with periodicity 65535 i could find
		517	dns_id = (dns_id << 1)
		518	\| (((dns_id >> 1)
		519	^ (dns_id >> 2)
		520	^ (dns_id >> 4)
		521	^ (dns_id >> 15)) & 1);
		522
		523	return dns_id;
		524	}
		525
		526	dns_snd::dns_snd (dns_connection *dns)
		527	: dns (dns)
		528	{
		529	timeout = 0;
		530	retry = 0;
		531	seqno = 0;
		532	sent = NOW;
		533
		534	pkt = new dns_packet;
		535
		536	pkt->id = next_id ();
		537	}
		538
		539	dns_snd::~dns_snd ()
		540	{
		541	delete pkt;
		542	}
		543
		544	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		545	{
		546	// add tunnel domain
		547	for (;;)
		548	{
		549	const char *end = strchr (domain, '.');
		550
		551	if (!end)
		552	end = domain + strlen (domain);
		553
		554	int len = end - domain;
		555
		556	pkt [offs++] = len;
		557	memcpy (pkt.at (offs), domain, len);
		558	offs += len;
		559
		560	if (!*end)
		561	break;
		562
		563	domain = end + 1;
		564	}
		565	}
		566
		567	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		568	{
		569	this->seqno = seqno;
		570
		571	timeout = NOW + INITIAL_TIMEOUT;
		572
		573	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		574	pkt->qdcount = htons (1);
		575
		576	int offs = 6*2;
		577	int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2);
		578	// 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
		580
		581	char enc[256], *encp = enc;
		582	encode_header (enc, THISNODE->id, seqno);
		583
		584	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		585
		586	if (datalen > stream.size ())
		587	datalen = stream.size ();
		588
		589	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		590	stream.remove (datalen);
		591
		592	while (enclen)
		593	{
		594	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		595
		596	(*pkt)[offs++] = lbllen;
		597	memcpy (pkt->at (offs), encp, lbllen);
		598
		599	offs += lbllen;
		600	encp += lbllen;
		601
		602	enclen -= lbllen;
		603	}
		604
		605	append_domain (*pkt, offs, THISNODE->domain);
		606
		607	(*pkt)[offs++] = 0;
		608	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;
		609	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		610
		611	pkt->len = offs;
		612	}
		613
		614	void dns_snd::gen_syn_req (const dns_cfg &cfg)
		615	{
		616	timeout = NOW + INITIAL_SYN_TIMEOUT;
		617
		618	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		619	pkt->qdcount = htons (1);
		620
		621	int offs = 6*2;
		622
		623	int elen = cdc26.encode ((char )pkt->at (offs + 1), (u8 )&cfg, sizeof (dns_cfg));
		624
		625	assert (elen <= MAX_LBL_SIZE);
		626
		627	(*pkt)[offs] = elen;
		628	offs += elen + 1;
		629	append_domain (*pkt, offs, THISNODE->domain);
		630
		631	(*pkt)[offs++] = 0;
		632	(pkt)[offs++] = RR_TYPE_A >> 8; (pkt)[offs++] = RR_TYPE_A;
		633	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		634
		635	pkt->len = offs;
		636	}
		637
		638	struct dns_rcv
		639	{
		640	int seqno;
		641	dns_packet *pkt; // reply packet
		642	u8 data [MAXSIZE]; // actually part of the reply packet...
		643	int datalen;
		644
		645	dns_rcv (int seqno, u8 *data, int datalen);
		646	~dns_rcv ();
		647	};
		648
		649	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		650	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		651	{
		652	memcpy (this->data, data, datalen);
		653	}
		654
		655	dns_rcv::~dns_rcv ()
		656	{
		657	delete pkt;
		658	}
		659
		660	/////////////////////////////////////////////////////////////////////////////
		661
		662	struct 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
		687	dns_connection::dns_connection (connection *c)
		688	: c (c)
		689	, rcvdq (MAX_BACKLOG * 2)
		690	, snddq (MAX_BACKLOG * 2)
		691	, tw (this, &dns_connection::time_cb)
		692	{
		693	vpn = c->vpn;
		694
		695	established = false;
		696
		697	rcvseq = sndseq = 0;
		698
		699	last_sent = last_received = 0;
		700	poll_interval = MIN_POLL_INTERVAL;
		701	send_interval = 0.2; // starting rate
		702	}
		703
		704	dns_connection::~dns_connection ()
		705	{
		706	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		707	i != rcvpq.end ();
		708	++i)
		709	delete *i;
		710	}
		711
		712	void dns_connection::receive_rep (dns_rcv *r)
		713	{
		714	if (r->datalen)
		715	{
		716	last_received = NOW;
		717	tw.trigger ();
		718
		719	poll_interval = send_interval;
		720	}
		721	else
		722	{
		723	poll_interval *= 1.1;
		724	if (poll_interval > MAX_POLL_INTERVAL)
		725	poll_interval = MAX_POLL_INTERVAL;
		726	}
		727
		728	rcvpq.push_back (r);
		729
		730	redo:
		731
		732	// find next packet
		733	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		734	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		735	{
		736	// enter the packet into our input stream
		737	r = *i;
		738
		739	// remove the oldest packet, look forward, as it's oldest first
		740	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		741	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		742	{
		743	delete *j;
		744	rcvpq.erase (j);
		745	break;
		746	}
		747
		748	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		749
		750	if (!rcvdq.put (r->data, r->datalen))
		751	abort (); // MUST never overflow, can be caused by data corruption, TODO
		752
		753	while (vpn_packet *pkt = rcvdq.get ())
		754	{
		755	sockinfo si;
		756	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;
		757
		758	vpn->recv_vpn_packet (pkt, si);
		759
		760	delete pkt;
		761	}
		762
		763	// check for further packets
		764	goto redo;
		765	}
		766	}
		767
		768	void
		769	vpn::dnsv4_server (dns_packet &pkt)
		770	{
		771	u16 flags = ntohs (pkt.flags);
		772
		773	int offs = 6 * 2; // skip header
		774
		775	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		776
		777	if (0 == (flags & (FLAG_RESPONSE \| FLAG_OP_MASK))
		778	&& pkt.qdcount == htons (1))
		779	{
		780	char qname[MAXSIZE];
		781	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		782
		783	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		784	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		785
		786	pkt.qdcount = htons (1);
		787	pkt.ancount = 0;
		788	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
		790
		791	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_NXDOMAIN);
		792
		793	int dlen = strlen (THISNODE->domain);
		794
		795	if (qclass == RR_CLASS_IN
		796	&& qlen > dlen + 1
		797	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
		798	{
		799	// now generate reply
		800	pkt.ancount = htons (1); // one answer RR
		801	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);
		802
		803	if ((qtype == RR_TYPE_ANY
		804	\|\| qtype == RR_TYPE_TXT
		805	\|\| qtype == RR_TYPE_NULL)
		806	&& qlen > dlen + 1 + HDRSIZE)
		807	{
		808	// correct class, domain: parse
		809	int client, seqno;
		810	decode_header (qname, client, seqno);
		811
		812	u8 data[MAXSIZE];
		813	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		814
		815	if (0 < client && client <= conns.size ())
		816	{
		817	connection *c = conns [client - 1];
		818	dns_connection *dns = c->dns;
		819	dns_rcv *rcv;
		820
		821	if (dns)
		822	{
		823	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		824	if (SEQNO_EQ ((*i)->seqno, seqno))
		825	{
		826	// already seen that request: simply reply with the cached reply
		827	dns_rcv r = i;
		828
		829	slog (L_DEBUG, "DUPLICATE %d\n", htons (r->pkt->id));
		830
		831	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		832	pkt.id = r->pkt->id;
		833	goto duplicate_request;
		834	}
		835
		836	// new packet, queue
		837	rcv = new dns_rcv (seqno, data, datalen);
		838	dns->receive_rep (rcv);
		839	}
		840
		841	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		842
		843	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		844	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		845	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		846	pkt [offs++] = 0; pkt [offs++] = 0;
		847	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		848
		849	int rdlen_offs = offs += 2;
		850
		851	int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs;
		852	// bind doesn't compress well, so reduce further by one label length
		853	dlen -= qlen;
		854
		855	if (dns)
		856	{
		857	while (dlen > 1 && !dns->snddq.empty ())
		858	{
		859	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		860
		861	if (txtlen > dns->snddq.size ())
		862	txtlen = dns->snddq.size ();
		863
		864	pkt[offs++] = txtlen;
		865	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		866	offs += txtlen;
		867	dns->snddq.remove (txtlen);
		868
		869	dlen -= txtlen + 1;
		870	}
		871
		872	// avoid empty TXT rdata
		873	if (offs == rdlen_offs)
		874	pkt[offs++] = 0;
		875	}
		876	else
		877	{
		878	// send RST
		879	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		880	pkt [offs++] = CMD_IP_RST;
		881	}
		882
		883	int rdlen = offs - rdlen_offs;
		884
		885	pkt [rdlen_offs - 2] = rdlen >> 8;
		886	pkt [rdlen_offs - 1] = rdlen;
		887
		888	if (dns)
		889	{
		890	// now update dns_rcv copy
		891	rcv->pkt->len = offs;
		892	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		893	}
		894
		895	duplicate_request: ;
		896	}
		897	else
		898	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		899	}
		900	else if (qtype == RR_TYPE_A
		901	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		902	{
		903	dns_cfg cfg;
		904	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		905	int client = ntohs (cfg.client);
		906
		907	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		908
		909	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
		910	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		911	pkt [offs++] = 0; pkt [offs++] = 0;
		912	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		913	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		914
		915	slog (L_INFO, _("DNS tunnel: client %d tries to connect"), client);
		916
		917	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		918	pkt [offs++] = CMD_IP_REJ;
		919
		920	if (0 < client && client <= conns.size ())
		921	{
		922	connection *c = conns [client - 1];
		923
		924	if (cfg.valid ())
		925	{
		926	pkt [offs - 1] = CMD_IP_SYN;
		927
		928	delete c->dns;
		929	c->dns = new dns_connection (c);
		930	c->dns->cfg = cfg;
		931	}
		932	}
		933	}
		934	}
		935
		936	pkt.len = offs;
		937	}
		938	}
		939
		940	void
		941	vpn::dnsv4_client (dns_packet &pkt)
		942	{
		943	u16 flags = ntohs (pkt.flags);
		944	int offs = 6 * 2; // skip header
		945
		946	pkt.qdcount = ntohs (pkt.qdcount);
		947	pkt.ancount = ntohs (pkt.ancount);
		948
		949	// go through our request list and find the corresponding request
		950	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
		951	i != dns_sndpq.end ();
		952	++i)
		953	if ((*i)->pkt->id == pkt.id)
		954	{
		955	dns_connection dns = (i)->dns;
		956	connection *c = dns->c;
		957	int seqno = (*i)->seqno;
		958	u8 data[MAXSIZE], *datap = data;
		959
		960	if ((*i)->retry)
		961	{
		962	dns->send_interval *= 1.001;
		963	if (dns->send_interval > MAX_SEND_INTERVAL)
		964	dns->send_interval = MAX_SEND_INTERVAL;
		965	}
		966	else
		967	{
		968	#if 1
		969	dns->send_interval *= 0.9999;
		970	#endif
		971	if (dns->send_interval < MIN_SEND_INTERVAL)
		972	dns->send_interval = MIN_SEND_INTERVAL;
		973
		974	// the latency surely puts an upper bound on
		975	// the minimum send interval
		976	double latency = NOW - (*i)->sent;
		977
		978	if (dns->send_interval > latency)
		979	dns->send_interval = latency;
		980	}
		981
		982	delete *i;
		983	dns_sndpq.erase (i);
		984
		985	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
		986	{
		987	char qname[MAXSIZE];
		988
		989	while (pkt.qdcount-- && offs < MAXSIZE - 4)
		990	{
		991	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		992	offs += 4; // skip qtype, qclass
		993	}
		994
		995	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
		996	{
		997	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		998
		999	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		1000	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		1001	u32 ttl = pkt [offs++] << 24;
		1002	ttl \|= pkt [offs++] << 16;
		1003	ttl \|= pkt [offs++] << 8;
		1004	ttl \|= pkt [offs++];
		1005	u16 rdlen = pkt [offs++] << 8; rdlen \|= pkt [offs++];
		1006
		1007	if (qtype == RR_TYPE_NULL \|\| qtype == RR_TYPE_TXT)
		1008	{
		1009	if (rdlen <= MAXSIZE - offs)
		1010	{
		1011	// decode bytes, finally
		1012
		1013	while (rdlen)
		1014	{
		1015	int txtlen = pkt [offs++];
		1016
		1017	assert (txtlen + offs < MAXSIZE - 1);
		1018
		1019	memcpy (datap, pkt.at (offs), txtlen);
		1020	datap += txtlen; offs += txtlen;
		1021
		1022	rdlen -= txtlen + 1;
		1023	}
		1024	}
		1025	}
		1026	else if (qtype == RR_TYPE_A)
		1027	{
		1028	u8 ip [4];
		1029
		1030	ip [0] = pkt [offs++];
		1031	ip [1] = pkt [offs++];
		1032	ip [2] = pkt [offs++];
		1033	ip [3] = pkt [offs++];
		1034
		1035	if (ip [0] == CMD_IP_1
		1036	&& ip [1] == CMD_IP_2
		1037	&& ip [2] == CMD_IP_3)
		1038	{
		1039	slog (L_TRACE, _("got tunnel meta command %02x"), ip [3]);
		1040
		1041	if (ip [3] == CMD_IP_RST)
		1042	{
		1043	slog (L_DEBUG, _("got tunnel RST request"));
		1044
		1045	delete dns; c->dns = 0;
		1046
		1047	return;
		1048	}
		1049	else if (ip [3] == CMD_IP_SYN)
		1050	{
		1051	slog (L_DEBUG, _("got tunnel SYN reply, server likes us."));
		1052	dns->established = true;
		1053	}
		1054	else if (ip [3] == CMD_IP_REJ)
		1055	{
		1056	slog (L_DEBUG, _("got tunnel REJ reply, server does not like us, aborting."));
		1057	abort ();
		1058	}
		1059	else
		1060	slog (L_INFO, _("got unknown meta command %02x"), ip [3]);
		1061	}
		1062	else
		1063	slog (L_INFO, _("got spurious a record %d.%d.%d.%d"),
		1064	ip [0], ip [1], ip [2], ip [3]);
		1065
		1066	return;
		1067	}
		1068
		1069	int client, rseqno;
		1070	decode_header (qname, client, rseqno);
		1071
		1072	if (client != THISNODE->id)
		1073	{
		1074	slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring"));
		1075	datap = 0;
		1076	}
		1077	else if (rseqno != seqno)
		1078	{
		1079	slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1080	datap = 0;
		1081	}
		1082	}
		1083	}
		1084
		1085	// todo: pkt now used
		1086	if (datap)
		1087	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1088
		1089	break;
		1090	}
		1091	}
66		1092
67	void	1093	void
68	vpn::dnsv4_ev (io_watcher &w, short revents)	1094	vpn::dnsv4_ev (io_watcher &w, short revents)
69	{	1095	{
70	if (revents & EVENT_READ)	1096	if (revents & EVENT_READ)
71	{	1097	{
		1098	dns_packet *pkt = new dns_packet;
72	struct sockaddr_in sa;	1099	struct sockaddr_in sa;
73	socklen_t sa_len = sizeof (sa);	1100	socklen_t sa_len = sizeof (sa);
74	int len;	1101
		1102	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
		1103
		1104	if (pkt->len > 0)
		1105	{
		1106	if (THISNODE->dns_port)
		1107	{
		1108	dnsv4_server (*pkt);
		1109	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
		1110	}
		1111	else
		1112	dnsv4_client (*pkt);
		1113
		1114	delete pkt;
		1115	}
75	}	1116	}
76	}	1117	}
77		1118
78	bool	1119	bool
79	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1120	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
80	{	1121	{
81	//return i->send_packet (pkt, tos);	1122	if (!dns)
		1123	dns = new dns_connection (this);
		1124
		1125	if (!dns->snddq.put (pkt))
		1126	return false;
		1127
		1128	dns->tw.trigger ();
		1129
		1130	return true;
		1131	}
		1132
		1133	void
		1134	connection::dnsv4_reset_connection ()
		1135	{
		1136	//delete dns; dns = 0; //TODO
		1137	}
		1138
		1139	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1140
		1141	void
		1142	dns_connection::time_cb (time_watcher &w)
		1143	{
		1144	// servers have to be polled
		1145	if (THISNODE->dns_port)
		1146	return;
		1147
		1148	// check for timeouts and (re)transmit
		1149	tstamp next = NOW + poll_interval;
		1150	dns_snd *send = 0;
		1151
		1152	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
		1153	i != vpn->dns_sndpq.end ();
		1154	++i)
		1155	{
		1156	dns_snd r = i;
		1157
		1158	if (r->timeout <= NOW)
		1159	{
		1160	if (!send)
		1161	{
		1162	send = r;
		1163
		1164	r->retry++;
		1165	r->timeout = NOW + r->retry;
		1166	}
		1167	}
		1168	else
		1169	NEXT (r->timeout);
		1170	}
		1171
		1172	if (last_sent + send_interval <= NOW)
		1173	{
		1174	if (!send)
		1175	{
		1176	// generate a new packet, if wise
		1177
		1178	if (!established)
		1179	{
		1180	if (vpn->dns_sndpq.empty ())
		1181	{
		1182	send = new dns_snd (this);
		1183
		1184	cfg.reset (THISNODE->id);
		1185	send->gen_syn_req (cfg);
		1186	}
		1187	}
		1188	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING)
		1189	{
		1190	send = new dns_snd (this);
		1191	send->gen_stream_req (sndseq, snddq);
		1192
		1193	sndseq = (sndseq + 1) & SEQNO_MASK;
		1194	}
		1195
		1196	if (send)
		1197	vpn->dns_sndpq.push_back (send);
		1198	}
		1199
		1200	if (send)
		1201	{
		1202	last_sent = NOW;
		1203	sendto (vpn->dnsv4_fd,
		1204	send->pkt->at (0), send->pkt->len, 0,
		1205	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1206	}
		1207	}
		1208	else
		1209	NEXT (last_sent + send_interval);
		1210
		1211	slog (L_NOISE, "pi %f si %f N %f (%d:%d)",
		1212	poll_interval, send_interval, next - NOW,
		1213	vpn->dns_sndpq.size (), snddq.size ());
		1214
		1215	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1216	if (next < NOW + 0.0001)
		1217	next = NOW + 0.1;
		1218
		1219	w.start (next);
82	}	1220	}
83		1221
84	#endif	1222	#endif
85		1223

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Comparing gvpe/src/vpn_dns.C (file contents): Revision 1.1 by pcg, Fri Apr 2 14:42:45 2004 UTC vs. Revision 1.14 by pcg, Fri Mar 4 09:51:23 2005 UTC

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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.1 by pcg, Fri Apr 2 14:42:45 2004 UTC vs.
Revision 1.14 by pcg, Fri Mar 4 09:51:23 2005 UTC