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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 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	#define MIN_RETRY 1.	49	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	50	#define ACTIVITY_INTERVAL 5.
46		51
47	#define MAX_OUTSTANDING 10 // max. outstanding requests	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
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	57	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
49	#define MAX_RATE 1 // requests/s
50	#define MAX_BACKLOG (10*1024) // size of protocol backlog	58	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		59
52	/*	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
53		63
54	protocol, in shorthand :)	64	#define SEQNO_MASK 0x3fff
55		65	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
56	client -> server <req> ANY?
57	server -> client <req> TXT <rep>
58
59	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
60	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
61
62	if <client-id> is zero, the connection will be configured:
63
64	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
65
66	*/
67		66
68	#define MAX_LBL_SIZE 63	67	#define MAX_LBL_SIZE 63
69	#define MAX_PKT_SIZE 512	68	#define MAX_PKT_SIZE 512
70		69
		70	#define RR_TYPE_A 1
		71	#define RR_TYPE_NULL 10
71	#define RR_TYPE_TXT 16	72	#define RR_TYPE_TXT 16
72	#define RR_TYPE_ANY 255	73	#define RR_TYPE_ANY 255
		74
73	#define RR_CLASS_IN 1	75	#define RR_CLASS_IN 1
74		76
75	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	77	#define CMD_IP_1 207
76	struct dns64	78	#define CMD_IP_2 46
77	{	79	#define CMD_IP_3 236
78	static const char encode_chars[64 + 1];	80	#define CMD_IP_RST 29
79	static s8 decode_chars[256];	81	#define CMD_IP_SYN 113
		82	#define CMD_IP_REJ 32
80		83
81	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	84	// works for cmaps up to 255 (not 256!)
82	static int decode_len (int bytes) { return (bytes * 6) / 8; }	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
83	static int encode (char *dst, u8 *src, int len);	127	unsigned int encode (char *dst, u8 *src, unsigned int len);
84	static int decode (u8 *dst, char *src, int len);	128	unsigned int decode (u8 *dst, char *src, unsigned int len);
85		129
86	dns64 ();	130	basecoder (const char *cmap);
87	} dns64;	131	};
88		132
89	const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";	133	basecoder::basecoder (const char *cmap)
90	s8 dns64::decode_chars[256];	134	: cmap (cmap)
91
92	dns64::dns64 ()
93	{	135	{
94	for (int i = 0; i < 64; i++)	136	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95	decode_chars [encode_chars [i]] = i + 1;	137	{
96	}	138	u8 src [MAX_DEC_LEN];
		139	u8 dst [MAX_ENC_LEN];
97		140
98	int dns64::encode (char *dst, u8 *src, int len)	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)
99	{	158	{
100	// slow, but easy to debug	159	return enc_len [len];
101	char *beg = dst;	160	}
102	unsigned int accum, bits = 0;	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;
103		206
104	while (len--)	207	while (len--)
105	{	208	{
106	accum <<= 8;	209	u8 val = cmap.decode [(u8)*src++];
107	accum |= *src++;
108	bits += 8;
109		210
110	while (bits >= 6)	211	if (val != charmap::INVALID)
111	{	212	src_ [elen++] = val;
112	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	213	}
113	bits -= 6;	214
114	}	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)
115	}	226	{
		227	memset (dst, 0, dlen - n);
		228	memcpy (dst + dlen - n, dst_, n);
		229	}
		230	else
		231	memcpy (dst, dst_ + n - dlen, dlen);
116		232
117	if (bits)	233	return dlen;
118	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120	return dst - beg;
121	}	234	}
122		235
123	int dns64::decode (u8 *dst, char *src, int len)	236	#if 0
124	{	237	struct test { test (); } test;
125	// slow, but easy to debug
126	u8 *beg = dst;
127	unsigned int accum, bits = 0;
128		238
129	while (len--)	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++)
130	{	248	{
131	s8 chr = decode_chars [(u8)*src++];	249	int elen = cdc.encode (enc, in, i);
		250	int dlen = cdc.decode (dec, enc, elen);
132		251
133	if (!chr)	252	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
134	break;
135
136	accum <<= 6;
137	accum |= chr - 1;
138	bits += 6;
139
140	while (bits >= 8)
141	{
142	*dst++ = accum >> (bits - 8);
143	bits -= 8;
144	}
145	}	253	}
		254	abort ();
		255	}
		256	#endif
146		257
147	return dst - beg;	258	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		259	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		260	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		261	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		262	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		263
		264	/////////////////////////////////////////////////////////////////////////////
		265
		266	#define HDRSIZE 6
		267
		268	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		269	{
		270	seqno &= SEQNO_MASK;
		271
		272	u8 hdr[3] = {
		273	clientid,
		274	(seqno >> 8) | (retry << 6),
		275	seqno,
		276	};
		277
		278	assert (clientid < 256);
		279
		280	cdc26.encode (data, hdr, 3);
		281	}
		282
		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;
148	}	291	}
149		292
150	/////////////////////////////////////////////////////////////////////////////	293	/////////////////////////////////////////////////////////////////////////////
151		294
152	struct byte_stream	295	struct byte_stream
…		…
159	~byte_stream ();	302	~byte_stream ();
160		303
161	bool empty () { return !fill; }	304	bool empty () { return !fill; }
162	int size () { return fill; }	305	int size () { return fill; }
163		306
		307	bool put (u8 *data, unsigned int datalen);
164	bool put (vpn_packet *pkt);	308	bool put (vpn_packet *pkt);
165	vpn_packet *get ();	309	vpn_packet *get ();
166		310
167	u8 *begin () { return data; }	311	u8 *begin () { return data; }
168	void remove (int count);	312	void remove (int count);
…		…
180	}	324	}
181		325
182	void byte_stream::remove (int count)	326	void byte_stream::remove (int count)
183	{	327	{
184	if (count > fill)	328	if (count > fill)
185	abort ();	329	assert (count <= fill);
186		330
187	memmove (data, data + count, fill -= count);	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;
188	}	342	}
189		343
190	bool byte_stream::put (vpn_packet *pkt)	344	bool byte_stream::put (vpn_packet *pkt)
191	{	345	{
192	if (maxsize - fill < pkt->len + 2)	346	if (maxsize - fill < pkt->len + 2)
193	return false;	347	return false;
194		348
195	data [fill++] = pkt->len >> 8;	349	data [fill++] = pkt->len >> 8;
196	data [fill++] = pkt->len;	350	data [fill++] = pkt->len;
197		351
198	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	352	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199		353
200	return true;	354	return true;
201	}	355	}
202		356
203	vpn_packet *byte_stream::get ()	357	vpn_packet *byte_stream::get ()
204	{	358	{
		359	unsigned int len;
		360
		361	for (;;)
		362	{
205	int len = (data [0] << 8) | data [1];	363	len = (data [0] << 8) | data [1];
206		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
207	if (fill < len + 2)	373	if (fill < len + 2)
208	return 0;	374	return 0;
209		375
210	vpn_packet *pkt = new vpn_packet;	376	vpn_packet *pkt = new vpn_packet;
		377
		378	pkt->len = len;
211	memcpy (&((*pkt)[0]), data + 2, len);	379	memcpy (pkt->at (0), data + 2, len);
212	remove (len + 2);	380	remove (len + 2);
213		381
214	return pkt;	382	return pkt;
215	}	383	}
216		384
217	/////////////////////////////////////////////////////////////////////////////	385	/////////////////////////////////////////////////////////////////////////////
218		386
219	#define FLAG_QUERY ( 0 << 15)	387	#define FLAG_QUERY ( 0 << 15)
220	#define FLAG_RESPONSE ( 1 << 15)	388	#define FLAG_RESPONSE ( 1 << 15)
221	#define FLAG_OP_MASK (15 << 14)	389	#define FLAG_OP_MASK (15 << 11)
222	#define FLAG_OP_QUERY ( 0 << 11)	390	#define FLAG_OP_QUERY ( 0 << 11)
223	#define FLAG_AA ( 1 << 10)	391	#define FLAG_AA ( 1 << 10)
224	#define FLAG_TC ( 1 << 9)	392	#define FLAG_TC ( 1 << 9)
225	#define FLAG_RD ( 1 << 8)	393	#define FLAG_RD ( 1 << 8)
226	#define FLAG_RA ( 1 << 7)	394	#define FLAG_RA ( 1 << 7)
		395	#define FLAG_AUTH ( 1 << 5)
227	#define FLAG_RCODE_MASK (15 << 0)	396	#define FLAG_RCODE_MASK (15 << 0)
228	#define FLAG_RCODE_OK ( 0 << 0)	397	#define FLAG_RCODE_OK ( 0 << 0)
229	#define FLAG_RCODE_FORMERR ( 1 << 0)	398	#define FLAG_RCODE_FORMERR ( 1 << 0)
230	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	399	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	400	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232	#define FLAG_RCODE_REFUSED ( 5 << 0)	401	#define FLAG_RCODE_REFUSED ( 5 << 0)
233		402
234	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	403	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
235	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | 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	}
236		471
237	struct dns_packet : net_packet	472	struct dns_packet : net_packet
238	{	473	{
239	u16 id;	474	u16 id;
240	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	475	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
241	u16 qdcount, ancount, nscount, arcount;	476	u16 qdcount, ancount, nscount, arcount;
242		477
243	u8 data[MAXSIZE - 6 * 2];	478	u8 data [MAXSIZE - 6 * 2];
244		479
245	int decode_label (char *data, int size, int &offs);	480	int decode_label (char *data, int size, int &offs);
246	};	481	};
247		482
248	int dns_packet::decode_label (char *data, int size, int &offs)	483	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
279	return data - orig;	514	return data - orig;
280	}	515	}
281		516
282	/////////////////////////////////////////////////////////////////////////////	517	/////////////////////////////////////////////////////////////////////////////
283		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
284	struct dns_req	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
285	{	566	{
286	dns_packet *pkt;	567	dns_packet *pkt;
287	tstamp next;	568	tstamp timeout, sent;
288	int retry;	569	int retry;
289	connection *conn;	570	struct dns_connection *dns;
		571	int seqno;
		572	bool stdhdr;
290		573
291	dns_req (connection *c, int seqno, byte_stream *stream);	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 ();
292	};	579	};
293		580
294	struct dns_rep	581	dns_snd::dns_snd (dns_connection *dns)
		582	: dns (dns)
295	{	583	{
296	};	584	timeout = 0;
297
298	static u16 dns_id; // TODO: should be per-vpn
299
300	dns_req::dns_req (connection *c, int seqno, byte_stream *stream)
301	: conn (c)
302	{
303	next = 0;
304	retry = 0;	585	retry = 0;
		586	seqno = 0;
		587	sent = NOW;
		588	stdhdr = false;
305		589
306	pkt = new dns_packet;	590	pkt = new dns_packet;
307		591
308	pkt->id = dns_id++;	592	pkt->id = next_id ();
309	pkt->flags = DEFAULT_CLIENT_FLAGS;	593	}
310	pkt->qdcount = htons (1);
311	pkt->ancount = 0;
312	pkt->nscount = 0;
313	pkt->arcount = 0;
314		594
315	int offs = 6*2;	595	dns_snd::~dns_snd ()
316	int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length	596	{
		597	delete pkt;
		598	}
317		599
318	u8 lbl[64]; //D	600	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
319	char enc[65];	601	{
320	int lbllen = 3;
321	lbl[0] = c->conf->id; //D
322	lbl[1] = seqno >> 8; //D
323	lbl[2] = seqno; //D
324
325	while (dlen > 0)
326	{
327	int sndlen = dlen;
328
329	if (sndlen + lbllen > dns64::decode_len (MAX_LBL_SIZE))
330	sndlen = dns64::decode_len (MAX_LBL_SIZE) - lbllen;
331
332	if (sndlen > stream->size ())
333	sndlen = stream->size ();
334
335	if (sndlen + lbllen == 0)
336	break;
337
338	memcpy (lbl + lbllen, stream->begin (), sndlen);
339	stream->remove (sndlen);
340	lbllen += sndlen;
341
342	dns64::encode (enc, lbl, lbllen);
343
344	int elen = dns64::encode_len (lbllen);
345	(*pkt)[offs++] = elen;
346	memcpy (&((*pkt)[offs]), enc, elen);
347	offs += elen;
348	dlen -= elen + 1;
349
350	lbllen = 0;
351	}
352
353	const char *suffix = THISNODE->domain;
354
355	// add tunnel domain	602	// add tunnel domain
356	for (;;)	603	for (;;)
357	{	604	{
358	const char *end = strchr (suffix, '.');	605	const char *end = strchr (domain, '.');
359		606
360	if (!end)	607	if (!end)
361	end = suffix + strlen (suffix);	608	end = domain + strlen (domain);
362		609
363	int len = end - suffix;	610	int len = end - domain;
364		611
365	(*pkt)[offs++] = len;	612	pkt [offs++] = len;
366	memcpy (&((*pkt)[offs]), suffix, len);	613	memcpy (pkt.at (offs), domain, len);
367	offs += len;	614	offs += len;
368		615
369	if (!*end)	616	if (!*end)
370	break;	617	break;
371		618
372	suffix = end + 1;	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)
373	}	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);
374		663
375	(*pkt)[offs++] = 0;	664	(*pkt)[offs++] = 0;
376	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	665	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	666	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378		667
379	pkt->len = offs;	668	pkt->len = offs;
		669	}
380		670
381	c->vpn->dns_sndpq.push_back (this);	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;
382	}	715	}
383		716
384	/////////////////////////////////////////////////////////////////////////////	717	/////////////////////////////////////////////////////////////////////////////
385		718
386	struct dns_cfg	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)
387	{	724	{
388	u8 id1, id2, id3;	725	vpn = c->vpn;
389	u8 def_ttl;
390	u8 unused1;
391	u16 max_size;
392	u8 flags1, flags2;
393	};
394		726
395	dns_packet *	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
396	vpn::dnsv4_server (dns_packet *pkt)	806	vpn::dnsv4_server (dns_packet &pkt)
397	{	807	{
398	u16 flags = ntohs (pkt->flags);	808	u16 flags = ntohs (pkt.flags);
399		809
400	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401	int offs = 6 * 2; // skip header	810	int offs = 6 * 2; // skip header
402		811
403	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	812	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404		813
405	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	814	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406	&& pkt->qdcount == htons (1))	815	&& pkt.qdcount == htons (1))
407	{	816	{
408	char qname[MAXSIZE];	817	char qname [MAXSIZE];
409	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	818	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410		819
411	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", pkt->len,
412	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
413
414	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	820	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	821	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416		822
417	pkt->qdcount = htons (1);	823	pkt.qdcount = htons (1);
418	pkt->ancount = 0;	824	pkt.ancount = 0;
419	pkt->nscount = 0; // should be self, as other nameservers reply like this	825	pkt.nscount = 0; // should be self, as other nameservers reply like this
420	pkt->arcount = 0; // a record for self, as other nameservers reply like this	826	pkt.arcount = 0; // a record for self, as other nameservers reply like this
421		827
422	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	828	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423		829
424	int dlen = strlen (THISNODE->domain);	830	int dlen = strlen (THISNODE->domain);
425		831
426	if (qclass == RR_CLASS_IN	832	if (qclass == RR_CLASS_IN
427	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428	&& qlen > dlen + 1	833	&& qlen > dlen + 1
429	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	834	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430	{	835	{
431	// correct class, domain, parse
432	u8 data[MAXSIZE];
433	int datalen = dns64::decode (data, qname, qlen - dlen - 1);
434
435	for (int i = 0; i < datalen; i++)
436	printf ("%02x ", data[i]);
437	printf ("\n");
438
439
440
441
442	#if 0
443	// now generate reply	836	// now generate reply
444	rep->ancount = htons (1); // one answer RR	837	pkt.ancount = htons (1); // one answer RR
445	rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	838	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446		839
447	(*rep) [offs++] = 0xc0;	840	if ((qtype == RR_TYPE_ANY
448	(*rep) [offs++] = 6 * 2; // same as in query section	841	|| qtype == RR_TYPE_TXT
449		842	|| qtype == RR_TYPE_NULL)
450	(*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT;	843	&& qlen > dlen + 1 + HDRSIZE)
451	(*rep) [offs++] = RR_CLASS_IN >> 8; (*rep) [offs++] = RR_CLASS_IN;
452
453	(*rep) [offs++] = 0; (*rep) [offs++] = 0;
454	(*rep) [offs++] = 0; (*rep) [offs++] = 0; // TTL
455
456	int dlen = MAX_PKT_SIZE - offs - 2;
457
458	printf ("we have room for %d bytes\n", dlen);
459
460	int rdlen_offs = offs += 2;
461
462	u8 txt[255];
463	txt[0] = 0;
464	txt[1] = 0;
465
466	int txtlen = 2;
467
468	while (dlen > 1)
469	{	844	{
470	int sndlen = --dlen;	845	// correct class, domain: parse
		846	int client, seqno;
		847	decode_header (qname, client, seqno);
471		848
472	if (sndlen + txtlen > 255)	849	u8 data[MAXSIZE];
473	sndlen = 255 - txtlen;	850	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
474		851
475	sndlen = 0;	852	if (0 < client && client <= conns.size ())
		853	{
		854	connection *c = conns [client - 1];
		855	dns_connection *dns = c->dns;
		856	dns_rcv *rcv;
476		857
477	(*rep)[offs++] = sndlen + txtlen;	858	if (dns)
478	memcpy (&((*rep)[offs]), txt, txtlen);	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);
479	offs += txtlen;	917	offs += txtlen;
		918	dns->snddq.remove (txtlen);
480		919
481	//if (sndlen + txtlen > dns_snddq.	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);
482	}	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);
483		961
484	int rdlen = offs - rdlen_offs;	962	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485		963
486	(*rep) [rdlen_offs - 2] = rdlen >> 8;	964	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487	(*rep) [rdlen_offs - 1] = rdlen;	965	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488	#endif	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	}
489	}	989	}
490	}
491		990
492	pkt->len = offs;	991	pkt.len = offs;
493	return pkt;	992	}
494	}	993	}
495		994
496	void	995	void
497	vpn::dnsv4_client (dns_packet *pkt)	996	vpn::dnsv4_client (dns_packet &pkt)
498	{	997	{
499	u16 flags = ntohs (pkt->flags);	998	u16 flags = ntohs (pkt.flags);
500	int offs = 6 * 2; // skip header	999	int offs = 6 * 2; // skip header
501		1000
502	pkt->qdcount = ntohs (pkt->qdcount);	1001	pkt.qdcount = ntohs (pkt.qdcount);
503	pkt->ancount = ntohs (pkt->ancount);	1002	pkt.ancount = ntohs (pkt.ancount);
504		1003
		1004	// go through our request list and find the corresponding request
505	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1005	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506	i != dns_sndpq.end ();	1006	i != dns_sndpq.end ();
507	++i)	1007	++i)
508	if ((*i)->pkt->id == pkt->id)	1008	if ((*i)->pkt->id == pkt.id)
509	{	1009	{
		1010	dns_connection *dns = (*i)->dns;
510	connection *c = (*i)->conn;	1011	connection *c = dns->c;
511	printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D	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
512	delete *i;	1040	delete *i;
513	dns_sndpq.erase (i);	1041	dns_sndpq.erase (i);
514		1042
515	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1043	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516	{	1044	{
517	char qname[MAXSIZE];	1045	char qname[MAXSIZE];
518		1046
519	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1047	while (pkt.qdcount-- && offs < MAXSIZE - 4)
520	{	1048	{
521	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1049	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522	offs += 4; // skip qtype, qclass	1050	offs += 4; // skip qtype, qclass
523	}	1051	}
524		1052
525	while (pkt->ancount-- && offs < MAXSIZE - 10)	1053	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526	{	1054	{
527	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1055	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528		1056
529	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1057	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1058	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531	u32 ttl = (*pkt) [offs++] << 24;	1059	u32 ttl = pkt [offs++] << 24;
532	ttl |= (*pkt) [offs++] << 16;	1060	ttl |= pkt [offs++] << 16;
533	ttl |= (*pkt) [offs++] << 8;	1061	ttl |= pkt [offs++] << 8;
534	ttl |= (*pkt) [offs++];	1062	ttl |= pkt [offs++];
535
536	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1063	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537		1064
538	printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen);	1065	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
539
540	offs += rdlen;
541
542	if (MAXSIZE - offs < rdlen)
543	{	1066	{
		1067	if (rdlen <= MAXSIZE - offs)
		1068	{
544	// decode bytes, finally	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;
545	}	1139	}
546	}	1140	}
547	}	1141	}
548		1142
		1143	// todo: pkt now used
		1144	if (datap)
		1145	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1146
549	break;	1147	break;
550	}	1148	}
551	}	1149	}
552		1150
553	void	1151	void
…		…
557	{	1155	{
558	dns_packet *pkt = new dns_packet;	1156	dns_packet *pkt = new dns_packet;
559	struct sockaddr_in sa;	1157	struct sockaddr_in sa;
560	socklen_t sa_len = sizeof (sa);	1158	socklen_t sa_len = sizeof (sa);
561		1159
562	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1160	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563		1161
564	if (pkt->len > 0)	1162	if (pkt->len > 0)
565	if (THISNODE->dns_port)
566	{	1163	{
567	pkt = dnsv4_server (pkt);	1164	if (ntohs (pkt->flags) & FLAG_RESPONSE)
568	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
569	}
570	else
571	dnsv4_client (pkt);	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	}
572	}	1174	}
573	}	1175	}
574		1176
575	bool	1177	bool
576	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1178	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577	{	1179	{
578	// never initialized	1180	int client = ntohl (si.host);
579	if (!dns_snddq && !dns_rcvdq)
580	{
581	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
582	dns_snddq = new byte_stream (MAX_BACKLOG);
583		1181
584	dns_rcvseq = dns_sndseq = 0;	1182	assert (0 < client && client <= conns.size ());
585		1183
586	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1184	connection *c = conns [client - 1];
587	}	1185
		1186	if (!c->dns)
		1187	c->dns = new dns_connection (c);
588		1188
589	if (!dns_snddq->put (pkt))	1189	if (c->dns->snddq.put (pkt))
590	return false;	1190	c->dns->tw.trigger ();
591		1191
592	// start timer if neccessary	1192	// always return true even if the buffer overflows
593	if (!dnsv4_tw.active)
594	dnsv4_cb (dnsv4_tw);
595
596	return true;	1193	return true;
597	}	1194	}
598		1195
599	void	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
600	connection::dnsv4_cb (time_watcher &w)	1205	dns_connection::time_cb (time_watcher &w)
601	{	1206	{
		1207	// servers have to be polled
		1208	if (THISNODE->dns_port)
		1209	return;
		1210
602	// check for timeouts and (re)transmit	1211	// check for timeouts and (re)transmit
603	tstamp next = NOW + 60;	1212	tstamp next = NOW + poll_interval;
604	dns_req *send = 0;	1213	dns_snd *send = 0;
605		1214
606	slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), vpn->dns_sndpq.size ());
607
608	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1215	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609	i != vpn->dns_sndpq.end ();	1216	i != vpn->dns_sndpq.end ();
610	++i)	1217	++i)
611	{	1218	{
612	dns_req *r = *i;	1219	dns_snd *r = *i;
613		1220
614	if (r->next <= NOW)	1221	if (r->timeout <= NOW)
615	{	1222	{
616	if (!send)	1223	if (!send)
617	{	1224	{
618	send = r;	1225	send = r;
619		1226
620	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621	r->retry++;	1227	r->retry++;
622	r->next = NOW + 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	}
623	}	1237	}
624	}	1238	}
625		1239	else
626	if (r->next < next)	1240	NEXT (r->timeout);
627	next = r->next;
628	}	1241	}
629		1242
630	if (!send	1243	if (!send)
631	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1244	{
632	send = new dns_req (this, dns_sndseq++, dns_snddq);	1245	// generate a new packet, if wise
633		1246
634	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);	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	}
635		1282
636	if (send)	1283	if (send)
637	{	1284	{
638	dns_packet *pkt = send->pkt;	1285	last_sent = NOW;
639		1286	sendto (vpn->dnsv4_fd,
640	next = min_next;	1287	send->pkt->at (0), send->pkt->len, 0,
641		1288	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
642	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
643	}	1289	}
644	else if (next < min_next)	1290
645	next = min_next;	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;
646		1300
647	w.start (next);	1301	w.start (next);
648	}	1302	}
649		1303
650	#endif	1304	#endif

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