[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 1.37 by pcg, Wed Mar 23 17:03:58 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
23		25
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	27	// it's a hack, use only in emergency situations please.
26		28
27	#include <cstring>	29	#include <cstring>
		30	#include <cassert>
28		31
29	#include <sys/types.h>	32	#include <sys/types.h>
30	#include <sys/socket.h>	33	#include <sys/socket.h>
31	#include <sys/wait.h>	34	#include <sys/wait.h>
32	#include <sys/uio.h>	35	#include <sys/uio.h>
…		…
35	#include <unistd.h>	38	#include <unistd.h>
36	#include <fcntl.h>	39	#include <fcntl.h>
37		40
38	#include <map>	41	#include <map>
39		42
		43	#include <gmp.h>
		44
40	#include "netcompat.h"	45	#include "netcompat.h"
41		46
42	#include "vpn.h"	47	#include "vpn.h"
43		48
44	#if ENABLE_HTTP_PROXY	49	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	# include "conf.h"	50	#define ACTIVITY_INTERVAL 5.
		51
		52	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		53	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
		54
		55	#define MAX_SEND_INTERVAL 2. // optimistic?
		56
		57	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
		58	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
		59
		60	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
		61	// 240 leaves about 4 bytes of server reply data
		62	// every request byte less give room for two reply bytes
		63
		64	#define SEQNO_MASK 0x3fff
		65	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
		66
		67	#define MAX_LBL_SIZE 63
		68	#define MAX_PKT_SIZE 512
		69
		70	#define RR_TYPE_A 1
		71	#define RR_TYPE_NULL 10
		72	#define RR_TYPE_TXT 16
		73	#define RR_TYPE_ANY 255
		74
		75	#define RR_CLASS_IN 1
		76
		77	#define CMD_IP_1 207
		78	#define CMD_IP_2 46
		79	#define CMD_IP_3 236
		80	#define CMD_IP_RST 29
		81	#define CMD_IP_SYN 113
		82	#define CMD_IP_REJ 32
		83
		84	// works for cmaps up to 255 (not 256!)
		85	struct charmap
		86	{
		87	enum { INVALID = (u8)255 };
		88
		89	char encode [256]; // index => char
		90	u8 decode [256]; // char => index
		91	unsigned int size;
		92
		93	charmap (const char *cmap);
		94	};
		95
		96	charmap::charmap (const char *cmap)
		97	{
		98	char *enc = encode;
		99	u8 *dec = decode;
		100
		101	memset (enc, (char) 0, 256);
		102	memset (dec, (char)INVALID, 256);
		103
		104	for (size = 0; cmap [size]; size++)
		105	{
		106	enc [size] = cmap [size];
		107	dec [(u8)enc [size]] = size;
		108	}
		109
		110	assert (size < 256);
		111	}
		112
		113	#define MAX_DEC_LEN 500
		114	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		115	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		116
		117	// ugly. minimum base is 16(!)
		118	struct basecoder
		119	{
		120	charmap cmap;
		121	unsigned int enc_len [MAX_DEC_LEN];
		122	unsigned int dec_len [MAX_ENC_LEN];
		123
		124	unsigned int encode_len (unsigned int len);
		125	unsigned int decode_len (unsigned int len);
		126
		127	unsigned int encode (char dst, u8 src, unsigned int len);
		128	unsigned int decode (u8 dst, char src, unsigned int len);
		129
		130	basecoder (const char *cmap);
		131	};
		132
		133	basecoder::basecoder (const char *cmap)
		134	: cmap (cmap)
		135	{
		136	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
		137	{
		138	u8 src [MAX_DEC_LEN];
		139	u8 dst [MAX_ENC_LEN];
		140
		141	memset (src, 255, len);
		142
		143	mp_limb_t m [MAX_LIMBS];
		144	mp_size_t n;
		145
		146	n = mpn_set_str (m, src, len, 256);
		147	n = mpn_get_str (dst, this->cmap.size, m, n);
		148
		149	for (int i = 0; !dst [i]; ++i)
		150	n--;
		151
		152	enc_len [len] = n;
		153	dec_len [n] = len;
		154	}
		155	}
		156
		157	unsigned int basecoder::encode_len (unsigned int len)
		158	{
		159	return enc_len [len];
		160	}
		161
		162	unsigned int basecoder::decode_len (unsigned int len)
		163	{
		164	while (len && !dec_len [len])
		165	--len;
		166
		167	return dec_len [len];
		168	}
		169
		170	unsigned int basecoder::encode (char dst, u8 src, unsigned int len)
		171	{
		172	if (!len \|\| len > MAX_DEC_LEN)
		173	return 0;
		174
		175	int elen = encode_len (len);
		176
		177	mp_limb_t m [MAX_LIMBS];
		178	mp_size_t n;
		179
		180	u8 dst_ [MAX_ENC_LEN];
		181
		182	n = mpn_set_str (m, src, len, 256);
		183	n = mpn_get_str (dst_, cmap.size, m, n);
		184
		185	int plen = elen; // for padding
		186
		187	while (n < plen)
		188	{
		189	*dst++ = cmap.encode [0];
		190	plen--;
		191	}
		192
		193	for (unsigned int i = n - plen; i < n; ++i)
		194	*dst++ = cmap.encode [dst_ [i]];
		195
		196	return elen;
		197	}
		198
		199	unsigned int basecoder::decode (u8 dst, char src, unsigned int len)
		200	{
		201	if (!len \|\| len > MAX_ENC_LEN)
		202	return 0;
		203
		204	u8 src_ [MAX_ENC_LEN];
		205	unsigned int elen = 0;
		206
		207	while (len--)
		208	{
		209	u8 val = cmap.decode [(u8)*src++];
		210
		211	if (val != charmap::INVALID)
		212	src_ [elen++] = val;
		213	}
		214
		215	int dlen = decode_len (elen);
		216
		217	mp_limb_t m [MAX_LIMBS];
		218	mp_size_t n;
		219
		220	u8 dst_ [MAX_DEC_LEN];
		221
		222	n = mpn_set_str (m, src_, elen, cmap.size);
		223	n = mpn_get_str (dst_, 256, m, n);
		224
		225	if (n < dlen)
		226	{
		227	memset (dst, 0, dlen - n);
		228	memcpy (dst + dlen - n, dst_, n);
		229	}
		230	else
		231	memcpy (dst, dst_ + n - dlen, dlen);
		232
		233	return dlen;
		234	}
		235
		236	#if 0
		237	struct test { test (); } test;
		238
		239	test::test ()
		240	{
		241	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		242
		243	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		244	static char enc[200];
		245	static u8 dec[200];
		246
		247	for (int i = 1; i < 20; i++)
		248	{
		249	int elen = cdc.encode (enc, in, i);
		250	int dlen = cdc.decode (dec, enc, elen);
		251
		252	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
		253	}
		254	abort ();
		255	}
46	#endif	256	#endif
47		257
48	#define MIN_RETRY 1.	258	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
49	#define MAX_RETRY 60.	259	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		260	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		261	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		262	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
50		263
51	#define SERVER conf.dns_port	264	/////////////////////////////////////////////////////////////////////////////
52		265
53	/*	266	#define HDRSIZE 6
		267
		268	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		269	{
		270	seqno &= SEQNO_MASK;
54		271
55	protocol, in shorthand :)	272	u8 hdr[3] = {
		273	clientid,
		274	(seqno >> 8) \| (retry << 6),
		275	seqno,
		276	};
56		277
57	<cseqno> ANY? poll for more data	278	assert (clientid < 256);
58	=> TXT <sseqno><data>
59	<cseqno><data> TXT? send more data
60	=> TXT <empty>
61		279
62	sequence numbers are 12 bit, 9 bit packet-number and 3 bit fragment id (7	280	cdc26.encode (data, hdr, 3);
63	- id, actually) last fragment is sent first, however	281	}
64		282
65	*/	283	inline void decode_header (char *data, int &clientid, int &seqno)
		284	{
		285	u8 hdr[3];
		286
		287	cdc26.decode (hdr, data, HDRSIZE);
		288
		289	clientid = hdr[0];
		290	seqno = ((hdr[1] << 8) \| hdr[2]) & SEQNO_MASK;
		291	}
		292
		293	/////////////////////////////////////////////////////////////////////////////
		294
		295	struct byte_stream
		296	{
		297	u8 *data;
		298	int maxsize;
		299	int fill;
		300
		301	byte_stream (int maxsize);
		302	~byte_stream ();
		303
		304	bool empty () { return !fill; }
		305	int size () { return fill; }
		306
		307	bool put (u8 *data, unsigned int datalen);
		308	bool put (vpn_packet *pkt);
		309	vpn_packet *get ();
		310
		311	u8 *begin () { return data; }
		312	void remove (int count);
		313	};
		314
		315	byte_stream::byte_stream (int maxsize)
		316	: maxsize (maxsize), fill (0)
		317	{
		318	data = new u8 [maxsize];
		319	}
		320
		321	byte_stream::~byte_stream ()
		322	{
		323	delete data;
		324	}
		325
		326	void byte_stream::remove (int count)
		327	{
		328	if (count > fill)
		329	assert (count <= fill);
		330
		331	memmove (data, data + count, fill -= count);
		332	}
		333
		334	bool byte_stream::put (u8 *data, unsigned int datalen)
		335	{
		336	if (maxsize - fill < datalen)
		337	return false;
		338
		339	memcpy (this->data + fill, data, datalen); fill += datalen;
		340
		341	return true;
		342	}
		343
		344	bool byte_stream::put (vpn_packet *pkt)
		345	{
		346	if (maxsize - fill < pkt->len + 2)
		347	return false;
		348
		349	data [fill++] = pkt->len >> 8;
		350	data [fill++] = pkt->len;
		351
		352	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
		353
		354	return true;
		355	}
		356
		357	vpn_packet *byte_stream::get ()
		358	{
		359	unsigned int len;
		360
		361	for (;;)
		362	{
		363	len = (data [0] << 8) \| data [1];
		364
		365	if (len <= MAXSIZE \|\| fill < 2)
		366	break;
		367
		368	// TODO: handle this better than skipping, e.g. by reset
		369	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		370	remove (1);
		371	}
		372
		373	if (fill < len + 2)
		374	return 0;
		375
		376	vpn_packet *pkt = new vpn_packet;
		377
		378	pkt->len = len;
		379	memcpy (pkt->at (0), data + 2, len);
		380	remove (len + 2);
		381
		382	return pkt;
		383	}
		384
		385	/////////////////////////////////////////////////////////////////////////////
		386
		387	#define FLAG_QUERY ( 0 << 15)
		388	#define FLAG_RESPONSE ( 1 << 15)
		389	#define FLAG_OP_MASK (15 << 11)
		390	#define FLAG_OP_QUERY ( 0 << 11)
		391	#define FLAG_AA ( 1 << 10)
		392	#define FLAG_TC ( 1 << 9)
		393	#define FLAG_RD ( 1 << 8)
		394	#define FLAG_RA ( 1 << 7)
		395	#define FLAG_AUTH ( 1 << 5)
		396	#define FLAG_RCODE_MASK (15 << 0)
		397	#define FLAG_RCODE_OK ( 0 << 0)
		398	#define FLAG_RCODE_FORMERR ( 1 << 0)
		399	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
		400	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
		401	#define FLAG_RCODE_REFUSED ( 5 << 0)
		402
		403	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)
		404	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE \| FLAG_OP_QUERY \| FLAG_AA \| FLAG_RD \| FLAG_RA)
		405
		406	struct dns_cfg
		407	{
		408	static int next_uid;
		409
		410	u8 id1, id2, id3, id4;
		411
		412	u8 version;
		413	u8 flags;
		414	u8 rrtype;
		415	u8 def_ttl;
		416
		417	u16 client;
		418	u16 uid; // to make request unique
		419
		420	u16 max_size;
		421	u8 seq_cdc;
		422	u8 req_cdc;
		423
		424	u8 rep_cdc;
		425	u8 delay; // time in 0.01s units that the server may delay replying packets
		426	u8 r3, r4;
		427
		428	u8 r5, r6, r7, r8;
		429
		430	void reset (int clientid);
		431	bool valid ();
		432	};
		433
		434	int dns_cfg::next_uid;
		435
		436	void dns_cfg::reset (int clientid)
		437	{
		438	id1 = 'G';
		439	id2 = 'V';
		440	id3 = 'P';
		441	id4 = 'E';
		442
		443	version = 1;
		444
		445	rrtype = RR_TYPE_TXT;
		446	flags = 0;
		447	def_ttl = 0;
		448	seq_cdc = 26;
		449	req_cdc = 62;
		450	rep_cdc = 0;
		451	max_size = htons (MAX_PKT_SIZE);
		452	client = htons (clientid);
		453	uid = next_uid++;
		454	delay = 0;
		455
		456	r3 = r4 = 0;
		457	r4 = r5 = r6 = r7 = 0;
		458	}
		459
		460	bool dns_cfg::valid ()
		461	{
		462	return id1 == 'G'
		463	&& id2 == 'V'
		464	&& id3 == 'P'
		465	&& id4 == 'E'
		466	&& seq_cdc == 26
		467	&& req_cdc == 62
		468	&& rep_cdc == 0
		469	&& version == 1;
		470	}
		471
		472	struct dns_packet : net_packet
		473	{
		474	u16 id;
		475	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
		476	u16 qdcount, ancount, nscount, arcount;
		477
		478	u8 data [MAXSIZE - 6 * 2];
		479
		480	int decode_label (char *data, int size, int &offs);
		481	};
		482
		483	int dns_packet::decode_label (char *data, int size, int &offs)
		484	{
		485	char *orig = data;
		486
		487	memset (data, 0, size);
		488
		489	while (offs < size - 1)
		490	{
		491	u8 len = (*this)[offs++];
		492
		493	if (!len)
		494	break;
		495	else if (len < 64)
		496	{
		497	if (size < len + 1 \|\| offs + len >= MAXSIZE - 1)
		498	break;
		499
		500	memcpy (data, &((*this)[offs]), len);
		501
		502	data += len; size -= len; offs += len;
		503	*data++ = '.'; size--;
		504	}
		505	else
		506	{
		507	int offs2 = ((len & 63) << 8) + (*this)[offs++];
		508
		509	data += decode_label (data, size, offs2);
		510	break;
		511	}
		512	}
		513
		514	return data - orig;
		515	}
		516
		517	/////////////////////////////////////////////////////////////////////////////
		518
		519	static u16 dns_id = 0; // TODO: should be per-vpn
		520
		521	static u16 next_id ()
		522	{
		523	if (!dns_id)
		524	dns_id = time (0);
		525
		526	// the simplest lsfr with periodicity 65535 i could find
		527	dns_id = (dns_id << 1)
		528	\| (((dns_id >> 1)
		529	^ (dns_id >> 2)
		530	^ (dns_id >> 4)
		531	^ (dns_id >> 15)) & 1);
		532
		533	return dns_id;
		534	}
		535
		536	struct dns_rcv;
		537	struct dns_snd;
		538
		539	struct dns_connection
		540	{
		541	connection *c;
		542	struct vpn *vpn;
		543
		544	dns_cfg cfg;
		545
		546	bool established;
		547
		548	tstamp last_received;
		549	tstamp last_sent;
		550	double min_latency;
		551	double poll_interval, send_interval;
		552
		553	vector<dns_rcv *> rcvpq;
		554
		555	byte_stream rcvdq; int rcvseq; int repseq;
		556	byte_stream snddq; int sndseq;
		557
		558	void time_cb (time_watcher &w); time_watcher tw;
		559	void receive_rep (dns_rcv *r);
		560
		561	dns_connection (connection *c);
		562	~dns_connection ();
		563	};
		564
		565	struct dns_snd
		566	{
		567	dns_packet *pkt;
		568	tstamp timeout, sent;
		569	int retry;
		570	struct dns_connection *dns;
		571	int seqno;
		572	bool stdhdr;
		573
		574	void gen_stream_req (int seqno, byte_stream &stream);
		575	void gen_syn_req ();
		576
		577	dns_snd (dns_connection *dns);
		578	~dns_snd ();
		579	};
		580
		581	dns_snd::dns_snd (dns_connection *dns)
		582	: dns (dns)
		583	{
		584	timeout = 0;
		585	retry = 0;
		586	seqno = 0;
		587	sent = NOW;
		588	stdhdr = false;
		589
		590	pkt = new dns_packet;
		591
		592	pkt->id = next_id ();
		593	}
		594
		595	dns_snd::~dns_snd ()
		596	{
		597	delete pkt;
		598	}
		599
		600	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		601	{
		602	// add tunnel domain
		603	for (;;)
		604	{
		605	const char *end = strchr (domain, '.');
		606
		607	if (!end)
		608	end = domain + strlen (domain);
		609
		610	int len = end - domain;
		611
		612	pkt [offs++] = len;
		613	memcpy (pkt.at (offs), domain, len);
		614	offs += len;
		615
		616	if (!*end)
		617	break;
		618
		619	domain = end + 1;
		620	}
		621	}
		622
		623	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		624	{
		625	stdhdr = true;
		626	this->seqno = seqno;
		627
		628	timeout = NOW + INITIAL_TIMEOUT;
		629
		630	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		631	pkt->qdcount = htons (1);
		632
		633	int offs = 6*2;
		634	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
		635	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		636	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		637
		638	char enc[256], *encp = enc;
		639	encode_header (enc, THISNODE->id, seqno);
		640
		641	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		642
		643	if (datalen > stream.size ())
		644	datalen = stream.size ();
		645
		646	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		647	stream.remove (datalen);
		648
		649	while (enclen)
		650	{
		651	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		652
		653	(*pkt)[offs++] = lbllen;
		654	memcpy (pkt->at (offs), encp, lbllen);
		655
		656	offs += lbllen;
		657	encp += lbllen;
		658
		659	enclen -= lbllen;
		660	}
		661
		662	append_domain (*pkt, offs, dns->c->conf->domain);
		663
		664	(*pkt)[offs++] = 0;
		665	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;
		666	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		667
		668	pkt->len = offs;
		669	}
		670
		671	void dns_snd::gen_syn_req ()
		672	{
		673	timeout = NOW + INITIAL_SYN_TIMEOUT;
		674
		675	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		676	pkt->qdcount = htons (1);
		677
		678	int offs = 6 * 2;
		679
		680	int elen = cdc26.encode ((char )pkt->at (offs + 1), (u8 )&dns->cfg, sizeof (dns_cfg));
		681
		682	assert (elen <= MAX_LBL_SIZE);
		683
		684	(*pkt)[offs] = elen;
		685	offs += elen + 1;
		686	append_domain (*pkt, offs, dns->c->conf->domain);
		687
		688	(*pkt)[offs++] = 0;
		689	(pkt)[offs++] = RR_TYPE_A >> 8; (pkt)[offs++] = RR_TYPE_A;
		690	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		691
		692	pkt->len = offs;
		693	}
		694
		695	struct dns_rcv
		696	{
		697	int seqno;
		698	dns_packet *pkt; // reply packet
		699	u8 data [MAXSIZE]; // actually part of the reply packet...
		700	int datalen;
		701
		702	dns_rcv (int seqno, u8 *data, int datalen);
		703	~dns_rcv ();
		704	};
		705
		706	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		707	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		708	{
		709	memcpy (this->data, data, datalen);
		710	}
		711
		712	dns_rcv::~dns_rcv ()
		713	{
		714	delete pkt;
		715	}
		716
		717	/////////////////////////////////////////////////////////////////////////////
		718
		719	dns_connection::dns_connection (connection *c)
		720	: c (c)
		721	, rcvdq (MAX_BACKLOG * 2)
		722	, snddq (MAX_BACKLOG)
		723	, tw (this, &dns_connection::time_cb)
		724	{
		725	vpn = c->vpn;
		726
		727	established = false;
		728
		729	rcvseq = repseq = sndseq = 0;
		730
		731	last_sent = last_received = 0;
		732	poll_interval = 0.5; // starting here
		733	send_interval = 0.5; // starting rate
		734	min_latency = INITIAL_TIMEOUT;
		735	}
		736
		737	dns_connection::~dns_connection ()
		738	{
		739	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		740	i != rcvpq.end ();
		741	++i)
		742	delete *i;
		743	}
		744
		745	void dns_connection::receive_rep (dns_rcv *r)
		746	{
		747	if (r->datalen)
		748	{
		749	last_received = NOW;
		750	tw.trigger ();
		751
		752	poll_interval = send_interval;
		753	}
		754	else
		755	{
		756	poll_interval *= 1.5;
		757
		758	if (poll_interval > MAX_POLL_INTERVAL)
		759	poll_interval = MAX_POLL_INTERVAL;
		760	}
		761
		762	rcvpq.push_back (r);
		763
		764	redo:
		765
		766	// find next packet
		767	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		768	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		769	{
		770	// enter the packet into our input stream
		771	r = *i;
		772
		773	// remove the oldest packet, look forward, as it's oldest first
		774	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		775	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		776	{
		777	delete *j;
		778	rcvpq.erase (j);
		779	break;
		780	}
		781
		782	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		783
		784	if (!rcvdq.put (r->data, r->datalen))
		785	{
		786	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		787	abort (); // MUST never overflow, can be caused by data corruption, TODO
		788	}
		789
		790	while (vpn_packet *pkt = rcvdq.get ())
		791	{
		792	sockinfo si;
		793	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
		794
		795	vpn->recv_vpn_packet (pkt, si);
		796
		797	delete pkt;
		798	}
		799
		800	// check for further packets
		801	goto redo;
		802	}
		803	}
		804
		805	void
		806	vpn::dnsv4_server (dns_packet &pkt)
		807	{
		808	u16 flags = ntohs (pkt.flags);
		809
		810	int offs = 6 * 2; // skip header
		811
		812	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		813
		814	if (0 == (flags & (FLAG_RESPONSE \| FLAG_OP_MASK))
		815	&& pkt.qdcount == htons (1))
		816	{
		817	char qname [MAXSIZE];
		818	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		819
		820	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		821	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		822
		823	pkt.qdcount = htons (1);
		824	pkt.ancount = 0;
		825	pkt.nscount = 0; // should be self, as other nameservers reply like this
		826	pkt.arcount = 0; // a record for self, as other nameservers reply like this
		827
		828	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_SERVFAIL);
		829
		830	int dlen = strlen (THISNODE->domain);
		831
		832	if (qclass == RR_CLASS_IN
		833	&& qlen > dlen + 1
		834	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
		835	{
		836	// now generate reply
		837	pkt.ancount = htons (1); // one answer RR
		838	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);
		839
		840	if ((qtype == RR_TYPE_ANY
		841	\|\| qtype == RR_TYPE_TXT
		842	\|\| qtype == RR_TYPE_NULL)
		843	&& qlen > dlen + 1 + HDRSIZE)
		844	{
		845	// correct class, domain: parse
		846	int client, seqno;
		847	decode_header (qname, client, seqno);
		848
		849	u8 data[MAXSIZE];
		850	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		851
		852	if (0 < client && client <= conns.size ())
		853	{
		854	connection *c = conns [client - 1];
		855	dns_connection *dns = c->dns;
		856	dns_rcv *rcv;
		857
		858	if (dns)
		859	{
		860	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		861	if (SEQNO_EQ ((*i)->seqno, seqno))
		862	{
		863	// already seen that request: simply reply with the cached reply
		864	dns_rcv r = i;
		865
		866	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		867
		868	// refresh header & id, as the retry count could have changed
		869	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		870	r->pkt->id = pkt.id;
		871
		872	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		873
		874	goto duplicate_request;
		875	}
		876
		877	// new packet, queue
		878	rcv = new dns_rcv (seqno, data, datalen);
		879	dns->receive_rep (rcv);
		880	}
		881
		882	{
		883	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		884
		885	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		886	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		887	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		888	pkt [offs++] = 0; pkt [offs++] = 0;
		889	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		890
		891	int rdlen_offs = offs += 2;
		892
		893	if (dns)
		894	{
		895	int dlen = ntohs (dns->cfg.max_size) - offs;
		896
		897	// bind doesn't compress well, so reduce further by one label length
		898	dlen -= qlen;
		899
		900	// only put data into in-order sequence packets, if
		901	// we receive out-of-order packets we generate empty
		902	// replies
		903	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		904	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		905	{
		906	dns->repseq = seqno;
		907
		908	while (dlen > 1 && !dns->snddq.empty ())
		909	{
		910	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		911
		912	if (txtlen > dns->snddq.size ())
		913	txtlen = dns->snddq.size ();
		914
		915	pkt[offs++] = txtlen;
		916	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		917	offs += txtlen;
		918	dns->snddq.remove (txtlen);
		919
		920	dlen -= txtlen + 1;
		921	}
		922	}
		923
		924	// avoid completely empty TXT rdata
		925	if (offs == rdlen_offs)
		926	pkt[offs++] = 0;
		927
		928	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		929	}
		930	else
		931	{
		932	// send RST
		933	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		934	pkt [offs++] = CMD_IP_RST;
		935	}
		936
		937	int rdlen = offs - rdlen_offs;
		938
		939	pkt [rdlen_offs - 2] = rdlen >> 8;
		940	pkt [rdlen_offs - 1] = rdlen;
		941
		942	if (dns)
		943	{
		944	// now update dns_rcv copy
		945	rcv->pkt->len = offs;
		946	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		947	}
		948	}
		949
		950	duplicate_request: ;
		951	}
		952	else
		953	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		954	}
		955	else if (qtype == RR_TYPE_A
		956	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		957	{
		958	dns_cfg cfg;
		959	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		960	int client = ntohs (cfg.client);
		961
		962	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		963
		964	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
		965	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		966	pkt [offs++] = 0; pkt [offs++] = 0;
		967	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		968	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		969
		970	slog (L_INFO, _("DNS: client %d connects"), client);
		971
		972	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		973	pkt [offs++] = CMD_IP_REJ;
		974
		975	if (0 < client && client <= conns.size ())
		976	{
		977	connection *c = conns [client - 1];
		978
		979	if (cfg.valid ())
		980	{
		981	pkt [offs - 1] = CMD_IP_SYN;
		982
		983	delete c->dns;
		984	c->dns = new dns_connection (c);
		985	c->dns->cfg = cfg;
		986	}
		987	}
		988	}
		989	}
		990
		991	pkt.len = offs;
		992	}
		993	}
		994
		995	void
		996	vpn::dnsv4_client (dns_packet &pkt)
		997	{
		998	u16 flags = ntohs (pkt.flags);
		999	int offs = 6 * 2; // skip header
		1000
		1001	pkt.qdcount = ntohs (pkt.qdcount);
		1002	pkt.ancount = ntohs (pkt.ancount);
		1003
		1004	// go through our request list and find the corresponding request
		1005	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
		1006	i != dns_sndpq.end ();
		1007	++i)
		1008	if ((*i)->pkt->id == pkt.id)
		1009	{
		1010	dns_connection dns = (i)->dns;
		1011	connection *c = dns->c;
		1012	int seqno = (*i)->seqno;
		1013	u8 data[MAXSIZE], *datap = data;
		1014
		1015	if ((*i)->retry)
		1016	{
		1017	dns->send_interval *= 1.01;
		1018	if (dns->send_interval > MAX_SEND_INTERVAL)
		1019	dns->send_interval = MAX_SEND_INTERVAL;
		1020	}
		1021	else
		1022	{
		1023	#if 0
		1024	dns->send_interval *= 0.999;
		1025	#endif
		1026	// the latency surely puts an upper bound on
		1027	// the minimum send interval
		1028	double latency = NOW - (*i)->sent;
		1029
		1030	if (latency < dns->min_latency)
		1031	dns->min_latency = latency;
		1032
		1033	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1034	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1035
		1036	if (dns->send_interval < conf.dns_send_interval)
		1037	dns->send_interval = conf.dns_send_interval;
		1038	}
		1039
		1040	delete *i;
		1041	dns_sndpq.erase (i);
		1042
		1043	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
		1044	{
		1045	char qname[MAXSIZE];
		1046
		1047	while (pkt.qdcount-- && offs < MAXSIZE - 4)
		1048	{
		1049	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1050	offs += 4; // skip qtype, qclass
		1051	}
		1052
		1053	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
		1054	{
		1055	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1056
		1057	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		1058	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		1059	u32 ttl = pkt [offs++] << 24;
		1060	ttl \|= pkt [offs++] << 16;
		1061	ttl \|= pkt [offs++] << 8;
		1062	ttl \|= pkt [offs++];
		1063	u16 rdlen = pkt [offs++] << 8; rdlen \|= pkt [offs++];
		1064
		1065	if (qtype == RR_TYPE_NULL \|\| qtype == RR_TYPE_TXT)
		1066	{
		1067	if (rdlen <= MAXSIZE - offs)
		1068	{
		1069	// decode bytes, finally
		1070
		1071	while (rdlen)
		1072	{
		1073	int txtlen = pkt [offs++];
		1074
		1075	assert (txtlen + offs < MAXSIZE - 1);
		1076
		1077	memcpy (datap, pkt.at (offs), txtlen);
		1078	datap += txtlen; offs += txtlen;
		1079
		1080	rdlen -= txtlen + 1;
		1081	}
		1082	}
		1083	}
		1084	else if (qtype == RR_TYPE_A)
		1085	{
		1086	u8 ip [4];
		1087
		1088	ip [0] = pkt [offs++];
		1089	ip [1] = pkt [offs++];
		1090	ip [2] = pkt [offs++];
		1091	ip [3] = pkt [offs++];
		1092
		1093	if (ip [0] == CMD_IP_1
		1094	&& ip [1] == CMD_IP_2
		1095	&& ip [2] == CMD_IP_3)
		1096	{
		1097	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1098
		1099	if (ip [3] == CMD_IP_RST)
		1100	{
		1101	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1102
		1103	delete dns; c->dns = 0;
		1104
		1105	return;
		1106	}
		1107	else if (ip [3] == CMD_IP_SYN)
		1108	{
		1109	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1110	dns->established = true;
		1111	}
		1112	else if (ip [3] == CMD_IP_REJ)
		1113	{
		1114	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1115	abort ();
		1116	}
		1117	else
		1118	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1119	}
		1120	else
		1121	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1122	ip [0], ip [1], ip [2], ip [3]);
		1123
		1124	return;
		1125	}
		1126
		1127	int client, rseqno;
		1128	decode_header (qname, client, rseqno);
		1129
		1130	if (client != THISNODE->id)
		1131	{
		1132	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1133	datap = 0;
		1134	}
		1135	else if (rseqno != seqno)
		1136	{
		1137	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1138	datap = 0;
		1139	}
		1140	}
		1141	}
		1142
		1143	// todo: pkt now used
		1144	if (datap)
		1145	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1146
		1147	break;
		1148	}
		1149	}
66		1150
67	void	1151	void
68	vpn::dnsv4_ev (io_watcher &w, short revents)	1152	vpn::dnsv4_ev (io_watcher &w, short revents)
69	{	1153	{
70	if (revents & EVENT_READ)	1154	if (revents & EVENT_READ)
71	{	1155	{
		1156	dns_packet *pkt = new dns_packet;
72	struct sockaddr_in sa;	1157	struct sockaddr_in sa;
73	socklen_t sa_len = sizeof (sa);	1158	socklen_t sa_len = sizeof (sa);
74	int len;	1159
		1160	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
		1161
		1162	if (pkt->len > 0)
		1163	{
		1164	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1165	dnsv4_client (*pkt);
		1166	else
		1167	{
		1168	dnsv4_server (*pkt);
		1169	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
		1170	}
		1171
		1172	delete pkt;
		1173	}
75	}	1174	}
76	}	1175	}
77		1176
78	bool	1177	bool
79	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1178	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
80	{	1179	{
81	//return i->send_packet (pkt, tos);	1180	int client = ntohl (si.host);
		1181
		1182	assert (0 < client && client <= conns.size ());
		1183
		1184	connection *c = conns [client - 1];
		1185
		1186	if (!c->dns)
		1187	c->dns = new dns_connection (c);
		1188
		1189	if (c->dns->snddq.put (pkt))
		1190	c->dns->tw.trigger ();
		1191
		1192	// always return true even if the buffer overflows
		1193	return true;
		1194	}
		1195
		1196	void
		1197	connection::dnsv4_reset_connection ()
		1198	{
		1199	//delete dns; dns = 0; //TODO
		1200	}
		1201
		1202	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1203
		1204	void
		1205	dns_connection::time_cb (time_watcher &w)
		1206	{
		1207	// servers have to be polled
		1208	if (THISNODE->dns_port)
		1209	return;
		1210
		1211	// check for timeouts and (re)transmit
		1212	tstamp next = NOW + poll_interval;
		1213	dns_snd *send = 0;
		1214
		1215	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
		1216	i != vpn->dns_sndpq.end ();
		1217	++i)
		1218	{
		1219	dns_snd r = i;
		1220
		1221	if (r->timeout <= NOW)
		1222	{
		1223	if (!send)
		1224	{
		1225	send = r;
		1226
		1227	r->retry++;
		1228	r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
		1229
		1230	// the following code changes the query section a bit, forcing
		1231	// the forwarder to generate a new request
		1232	if (r->stdhdr)
		1233	{
		1234	//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1235	//encode_header ((char )r->pkt->at (6 2 + 1), THISNODE->id, r->seqno, r->retry);
		1236	}
		1237	}
		1238	}
		1239	else
		1240	NEXT (r->timeout);
		1241	}
		1242
		1243	if (!send)
		1244	{
		1245	// generate a new packet, if wise
		1246
		1247	if (!established)
		1248	{
		1249	if (vpn->dns_sndpq.empty ())
		1250	{
		1251	send = new dns_snd (this);
		1252
		1253	cfg.reset (THISNODE->id);
		1254	send->gen_syn_req ();
		1255	}
		1256	}
		1257	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1258	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1259	{
		1260	if (last_sent + send_interval <= NOW)
		1261	{
		1262	//printf ("sending data request etc.\n"); //D
		1263	if (!snddq.empty () \|\| last_received + 1. > NOW)
		1264	{
		1265	poll_interval = send_interval;
		1266	NEXT (NOW + send_interval);
		1267	}
		1268
		1269	send = new dns_snd (this);
		1270	send->gen_stream_req (sndseq, snddq);
		1271	send->timeout = NOW + min_latency * conf.dns_timeout_factor;
		1272
		1273	sndseq = (sndseq + 1) & SEQNO_MASK;
		1274	}
		1275	else
		1276	NEXT (last_sent + send_interval);
		1277	}
		1278
		1279	if (send)
		1280	vpn->dns_sndpq.push_back (send);
		1281	}
		1282
		1283	if (send)
		1284	{
		1285	last_sent = NOW;
		1286	sendto (vpn->dnsv4_fd,
		1287	send->pkt->at (0), send->pkt->len, 0,
		1288	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1289	}
		1290
		1291	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1292	poll_interval, send_interval, next - NOW,
		1293	vpn->dns_sndpq.size (), snddq.size (),
		1294	rcvpq.size ());
		1295
		1296	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1297	// doesn't seem to happen anymore
		1298	if (next < NOW + 0.001)
		1299	next = NOW + 0.1;
		1300
		1301	w.start (next);
82	}	1302	}
83		1303
84	#endif	1304	#endif
85		1305

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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 1.37 by pcg, Wed Mar 23 17:03:58 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 1.37 by pcg, Wed Mar 23 17:03:58 2005 UTC