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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 1.33 by pcg, Tue Mar 15 19:23:33 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
		52	#define TIMEOUT_FACTOR 8.
		53
		54	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		55	#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
		56
		57	#define MIN_SEND_INTERVAL 0.001 // wait at least this time between sending requests
		58	#define MAX_SEND_INTERVAL 2. // optimistic?
		59
		60	#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
47	#define MAX_OUTSTANDING 10 // max. outstanding requests	61	#define MAX_OUTSTANDING 100 // max. outstanding requests
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	62	#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	63	#define MAX_BACKLOG (32*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		64
52	/*	65	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
		66	// 240 leaves about 4 bytes of server reply data
		67	// every request byte less give room for two reply bytes
53		68
54	protocol, in shorthand :)	69	#define SEQNO_MASK 0x3fff
55		70	#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		71
68	#define MAX_LBL_SIZE 63	72	#define MAX_LBL_SIZE 63
69	#define MAX_PKT_SIZE 512	73	#define MAX_PKT_SIZE 512
70		74
		75	#define RR_TYPE_A 1
		76	#define RR_TYPE_NULL 10
71	#define RR_TYPE_TXT 16	77	#define RR_TYPE_TXT 16
72	#define RR_TYPE_ANY 255	78	#define RR_TYPE_ANY 255
		79
73	#define RR_CLASS_IN 1	80	#define RR_CLASS_IN 1
74		81
75	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	82	#define CMD_IP_1 207
76	struct dns64	83	#define CMD_IP_2 46
77	{	84	#define CMD_IP_3 236
78	static const char encode_chars[64 + 1];	85	#define CMD_IP_RST 29
79	static s8 decode_chars[256];	86	#define CMD_IP_SYN 113
		87	#define CMD_IP_REJ 32
80		88
81	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	89	// works for cmaps up to 255 (not 256!)
82	static int decode_len (int bytes) { return (bytes * 6) / 8; }	90	struct charmap
		91	{
		92	enum { INVALID = (u8)255 };
		93
		94	char encode [256]; // index => char
		95	u8 decode [256]; // char => index
		96	unsigned int size;
		97
		98	charmap (const char *cmap);
		99	};
		100
		101	charmap::charmap (const char *cmap)
		102	{
		103	char *enc = encode;
		104	u8 *dec = decode;
		105
		106	memset (enc, (char) 0, 256);
		107	memset (dec, (char)INVALID, 256);
		108
		109	for (size = 0; cmap [size]; size++)
		110	{
		111	enc [size] = cmap [size];
		112	dec [(u8)enc [size]] = size;
		113	}
		114
		115	assert (size < 256);
		116	}
		117
		118	#define MAX_DEC_LEN 500
		119	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		120	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		121
		122	// ugly. minimum base is 16(!)
		123	struct basecoder
		124	{
		125	charmap cmap;
		126	unsigned int enc_len [MAX_DEC_LEN];
		127	unsigned int dec_len [MAX_ENC_LEN];
		128
		129	unsigned int encode_len (unsigned int len);
		130	unsigned int decode_len (unsigned int len);
		131
83	static int encode (char *dst, u8 *src, int len);	132	unsigned int encode (char *dst, u8 *src, unsigned int len);
84	static int decode (u8 *dst, char *src, int len);	133	unsigned int decode (u8 *dst, char *src, unsigned int len);
85		134
86	dns64 ();	135	basecoder (const char *cmap);
87	} dns64;	136	};
88		137
89	const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";	138	basecoder::basecoder (const char *cmap)
90	s8 dns64::decode_chars[256];	139	: cmap (cmap)
91
92	dns64::dns64 ()
93	{	140	{
94	for (int i = 0; i < 64; i++)	141	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95	decode_chars [encode_chars [i]] = i + 1;	142	{
96	}	143	u8 src [MAX_DEC_LEN];
		144	u8 dst [MAX_ENC_LEN];
97		145
98	int dns64::encode (char *dst, u8 *src, int len)	146	memset (src, 255, len);
		147
		148	mp_limb_t m [MAX_LIMBS];
		149	mp_size_t n;
		150
		151	n = mpn_set_str (m, src, len, 256);
		152	n = mpn_get_str (dst, this->cmap.size, m, n);
		153
		154	for (int i = 0; !dst [i]; ++i)
		155	n--;
		156
		157	enc_len [len] = n;
		158	dec_len [n] = len;
		159	}
		160	}
		161
		162	unsigned int basecoder::encode_len (unsigned int len)
99	{	163	{
100	// slow, but easy to debug	164	return enc_len [len];
101	char *beg = dst;	165	}
102	unsigned int accum, bits = 0;	166
		167	unsigned int basecoder::decode_len (unsigned int len)
		168	{
		169	while (len && !dec_len [len])
		170	--len;
		171
		172	return dec_len [len];
		173	}
		174
		175	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		176	{
		177	if (!len || len > MAX_DEC_LEN)
		178	return 0;
		179
		180	int elen = encode_len (len);
		181
		182	mp_limb_t m [MAX_LIMBS];
		183	mp_size_t n;
		184
		185	u8 dst_ [MAX_ENC_LEN];
		186
		187	n = mpn_set_str (m, src, len, 256);
		188	n = mpn_get_str (dst_, cmap.size, m, n);
		189
		190	int plen = elen; // for padding
		191
		192	while (n < plen)
		193	{
		194	*dst++ = cmap.encode [0];
		195	plen--;
		196	}
		197
		198	for (unsigned int i = n - plen; i < n; ++i)
		199	*dst++ = cmap.encode [dst_ [i]];
		200
		201	return elen;
		202	}
		203
		204	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		205	{
		206	if (!len || len > MAX_ENC_LEN)
		207	return 0;
		208
		209	u8 src_ [MAX_ENC_LEN];
		210	unsigned int elen = 0;
103		211
104	while (len--)	212	while (len--)
105	{	213	{
106	accum <<= 8;	214	u8 val = cmap.decode [(u8)*src++];
107	accum |= *src++;
108	bits += 8;
109		215
110	while (bits >= 6)	216	if (val != charmap::INVALID)
111	{	217	src_ [elen++] = val;
112	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	218	}
113	bits -= 6;	219
114	}	220	int dlen = decode_len (elen);
		221
		222	mp_limb_t m [MAX_LIMBS];
		223	mp_size_t n;
		224
		225	u8 dst_ [MAX_DEC_LEN];
		226
		227	n = mpn_set_str (m, src_, elen, cmap.size);
		228	n = mpn_get_str (dst_, 256, m, n);
		229
		230	if (n < dlen)
115	}	231	{
		232	memset (dst, 0, dlen - n);
		233	memcpy (dst + dlen - n, dst_, n);
		234	}
		235	else
		236	memcpy (dst, dst_ + n - dlen, dlen);
116		237
117	if (bits)	238	return dlen;
118	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120	return dst - beg;
121	}	239	}
122		240
123	int dns64::decode (u8 *dst, char *src, int len)	241	#if 0
124	{	242	struct test { test (); } test;
125	// slow, but easy to debug
126	u8 *beg = dst;
127	unsigned int accum, bits = 0;
128		243
129	while (len--)	244	test::test ()
		245	{
		246	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		247
		248	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		249	static char enc[200];
		250	static u8 dec[200];
		251
		252	for (int i = 1; i < 20; i++)
130	{	253	{
131	s8 chr = decode_chars [(u8)*src++];	254	int elen = cdc.encode (enc, in, i);
		255	int dlen = cdc.decode (dec, enc, elen);
132		256
133	if (!chr)	257	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	}	258	}
		259	abort ();
		260	}
		261	#endif
146		262
147	return dst - beg;	263	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		264	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		265	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		266	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		267	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		268
		269	/////////////////////////////////////////////////////////////////////////////
		270
		271	#define HDRSIZE 6
		272
		273	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		274	{
		275	seqno &= SEQNO_MASK;
		276
		277	u8 hdr[3] = {
		278	clientid,
		279	(seqno >> 8) | (retry << 6),
		280	seqno,
		281	};
		282
		283	assert (clientid < 256);
		284
		285	cdc26.encode (data, hdr, 3);
		286	}
		287
		288	inline void decode_header (char *data, int &clientid, int &seqno)
		289	{
		290	u8 hdr[3];
		291
		292	cdc26.decode (hdr, data, HDRSIZE);
		293
		294	clientid = hdr[0];
		295	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
148	}	296	}
149		297
150	/////////////////////////////////////////////////////////////////////////////	298	/////////////////////////////////////////////////////////////////////////////
151		299
152	struct byte_stream	300	struct byte_stream
…		…
159	~byte_stream ();	307	~byte_stream ();
160		308
161	bool empty () { return !fill; }	309	bool empty () { return !fill; }
162	int size () { return fill; }	310	int size () { return fill; }
163		311
		312	bool put (u8 *data, unsigned int datalen);
164	bool put (vpn_packet *pkt);	313	bool put (vpn_packet *pkt);
165	vpn_packet *get ();	314	vpn_packet *get ();
166		315
167	u8 *begin () { return data; }	316	u8 *begin () { return data; }
168	void remove (int count);	317	void remove (int count);
…		…
180	}	329	}
181		330
182	void byte_stream::remove (int count)	331	void byte_stream::remove (int count)
183	{	332	{
184	if (count > fill)	333	if (count > fill)
185	abort ();	334	assert (count <= fill);
186		335
187	memmove (data, data + count, fill -= count);	336	memmove (data, data + count, fill -= count);
		337	}
		338
		339	bool byte_stream::put (u8 *data, unsigned int datalen)
		340	{
		341	if (maxsize - fill < datalen)
		342	return false;
		343
		344	memcpy (this->data + fill, data, datalen); fill += datalen;
		345
		346	return true;
188	}	347	}
189		348
190	bool byte_stream::put (vpn_packet *pkt)	349	bool byte_stream::put (vpn_packet *pkt)
191	{	350	{
192	if (maxsize - fill < pkt->len + 2)	351	if (maxsize - fill < pkt->len + 2)
193	return false;	352	return false;
194		353
195	data [fill++] = pkt->len >> 8;	354	data [fill++] = pkt->len >> 8;
196	data [fill++] = pkt->len;	355	data [fill++] = pkt->len;
197		356
198	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	357	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199		358
200	return true;	359	return true;
201	}	360	}
202		361
203	vpn_packet *byte_stream::get ()	362	vpn_packet *byte_stream::get ()
204	{	363	{
		364	unsigned int len;
		365
		366	for (;;)
		367	{
205	int len = (data [0] << 8) | data [1];	368	len = (data [0] << 8) | data [1];
206		369
		370	if (len <= MAXSIZE || fill < 2)
		371	break;
		372
		373	// TODO: handle this better than skipping, e.g. by reset
		374	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		375	remove (1);
		376	}
		377
207	if (fill < len + 2)	378	if (fill < len + 2)
208	return 0;	379	return 0;
209		380
210	vpn_packet *pkt = new vpn_packet;	381	vpn_packet *pkt = new vpn_packet;
		382
		383	pkt->len = len;
211	memcpy (&((*pkt)[0]), data + 2, len);	384	memcpy (pkt->at (0), data + 2, len);
212	remove (len + 2);	385	remove (len + 2);
213		386
214	return pkt;	387	return pkt;
215	}	388	}
216		389
217	/////////////////////////////////////////////////////////////////////////////	390	/////////////////////////////////////////////////////////////////////////////
218		391
219	#define FLAG_QUERY ( 0 << 15)	392	#define FLAG_QUERY ( 0 << 15)
220	#define FLAG_RESPONSE ( 1 << 15)	393	#define FLAG_RESPONSE ( 1 << 15)
221	#define FLAG_OP_MASK (15 << 14)	394	#define FLAG_OP_MASK (15 << 11)
222	#define FLAG_OP_QUERY ( 0 << 11)	395	#define FLAG_OP_QUERY ( 0 << 11)
223	#define FLAG_AA ( 1 << 10)	396	#define FLAG_AA ( 1 << 10)
224	#define FLAG_TC ( 1 << 9)	397	#define FLAG_TC ( 1 << 9)
225	#define FLAG_RD ( 1 << 8)	398	#define FLAG_RD ( 1 << 8)
226	#define FLAG_RA ( 1 << 7)	399	#define FLAG_RA ( 1 << 7)
		400	#define FLAG_AUTH ( 1 << 5)
227	#define FLAG_RCODE_MASK (15 << 0)	401	#define FLAG_RCODE_MASK (15 << 0)
228	#define FLAG_RCODE_OK ( 0 << 0)	402	#define FLAG_RCODE_OK ( 0 << 0)
229	#define FLAG_RCODE_FORMERR ( 1 << 0)	403	#define FLAG_RCODE_FORMERR ( 1 << 0)
230	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	404	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	405	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232	#define FLAG_RCODE_REFUSED ( 5 << 0)	406	#define FLAG_RCODE_REFUSED ( 5 << 0)
233		407
234	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	408	#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)	409	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
		410
		411	struct dns_cfg
		412	{
		413	static int next_uid;
		414
		415	u8 id1, id2, id3, id4;
		416
		417	u8 version;
		418	u8 flags;
		419	u8 rrtype;
		420	u8 def_ttl;
		421
		422	u16 client;
		423	u16 uid; // to make request unique
		424
		425	u16 max_size;
		426	u8 seq_cdc;
		427	u8 req_cdc;
		428
		429	u8 rep_cdc;
		430	u8 delay; // time in 0.01s units that the server may delay replying packets
		431	u8 r3, r4;
		432
		433	u8 r5, r6, r7, r8;
		434
		435	void reset (int clientid);
		436	bool valid ();
		437	};
		438
		439	int dns_cfg::next_uid;
		440
		441	void dns_cfg::reset (int clientid)
		442	{
		443	id1 = 'G';
		444	id2 = 'V';
		445	id3 = 'P';
		446	id4 = 'E';
		447
		448	version = 1;
		449
		450	rrtype = RR_TYPE_TXT;
		451	flags = 0;
		452	def_ttl = 0;
		453	seq_cdc = 26;
		454	req_cdc = 62;
		455	rep_cdc = 0;
		456	max_size = htons (MAX_PKT_SIZE);
		457	client = htons (clientid);
		458	uid = next_uid++;
		459	delay = 0;
		460
		461	r3 = r4 = 0;
		462	r4 = r5 = r6 = r7 = 0;
		463	}
		464
		465	bool dns_cfg::valid ()
		466	{
		467	return id1 == 'G'
		468	&& id2 == 'V'
		469	&& id3 == 'P'
		470	&& id4 == 'E'
		471	&& seq_cdc == 26
		472	&& req_cdc == 62
		473	&& rep_cdc == 0
		474	&& version == 1;
		475	}
236		476
237	struct dns_packet : net_packet	477	struct dns_packet : net_packet
238	{	478	{
239	u16 id;	479	u16 id;
240	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	480	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
241	u16 qdcount, ancount, nscount, arcount;	481	u16 qdcount, ancount, nscount, arcount;
242		482
243	u8 data[MAXSIZE - 6 * 2];	483	u8 data [MAXSIZE - 6 * 2];
244		484
245	int decode_label (char *data, int size, int &offs);	485	int decode_label (char *data, int size, int &offs);
246	};	486	};
247		487
248	int dns_packet::decode_label (char *data, int size, int &offs)	488	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
279	return data - orig;	519	return data - orig;
280	}	520	}
281		521
282	/////////////////////////////////////////////////////////////////////////////	522	/////////////////////////////////////////////////////////////////////////////
283		523
		524	static u16 dns_id = 0; // TODO: should be per-vpn
		525
		526	static u16 next_id ()
		527	{
		528	if (!dns_id)
		529	dns_id = time (0);
		530
		531	// the simplest lsfr with periodicity 65535 i could find
		532	dns_id = (dns_id << 1)
		533	| (((dns_id >> 1)
		534	^ (dns_id >> 2)
		535	^ (dns_id >> 4)
		536	^ (dns_id >> 15)) & 1);
		537
		538	return dns_id;
		539	}
		540
284	struct dns_req	541	struct dns_rcv;
		542	struct dns_snd;
		543
		544	struct dns_connection
		545	{
		546	connection *c;
		547	struct vpn *vpn;
		548
		549	dns_cfg cfg;
		550
		551	bool established;
		552
		553	tstamp last_received;
		554	tstamp last_sent;
		555	double min_latency;
		556	double poll_interval, send_interval;
		557
		558	vector<dns_rcv *> rcvpq;
		559
		560	byte_stream rcvdq; int rcvseq; int repseq;
		561	byte_stream snddq; int sndseq;
		562
		563	void time_cb (time_watcher &w); time_watcher tw;
		564	void receive_rep (dns_rcv *r);
		565
		566	dns_connection (connection *c);
		567	~dns_connection ();
		568	};
		569
		570	struct dns_snd
285	{	571	{
286	dns_packet *pkt;	572	dns_packet *pkt;
287	tstamp next;	573	tstamp timeout, sent;
288	int retry;	574	int retry;
289	connection *conn;	575	struct dns_connection *dns;
		576	int seqno;
		577	bool stdhdr;
290		578
291	dns_req (connection *c, int seqno, byte_stream *stream);	579	void gen_stream_req (int seqno, byte_stream &stream);
		580	void gen_syn_req ();
		581
		582	dns_snd (dns_connection *dns);
		583	~dns_snd ();
292	};	584	};
293		585
294	struct dns_rep	586	dns_snd::dns_snd (dns_connection *dns)
		587	: dns (dns)
295	{	588	{
296	};	589	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;	590	retry = 0;
		591	seqno = 0;
		592	sent = NOW;
		593	stdhdr = false;
305		594
306	pkt = new dns_packet;	595	pkt = new dns_packet;
307		596
308	pkt->id = dns_id++;	597	pkt->id = next_id ();
309	pkt->flags = DEFAULT_CLIENT_FLAGS;	598	}
310	pkt->qdcount = htons (1);
311	pkt->ancount = 0;
312	pkt->nscount = 0;
313	pkt->arcount = 0;
314		599
315	int offs = 6*2;	600	dns_snd::~dns_snd ()
316	int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length	601	{
		602	delete pkt;
		603	}
317		604
318	u8 lbl[64]; //D	605	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
319	char enc[65];	606	{
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	607	// add tunnel domain
356	for (;;)	608	for (;;)
357	{	609	{
358	const char *end = strchr (suffix, '.');	610	const char *end = strchr (domain, '.');
359		611
360	if (!end)	612	if (!end)
361	end = suffix + strlen (suffix);	613	end = domain + strlen (domain);
362		614
363	int len = end - suffix;	615	int len = end - domain;
364		616
365	(*pkt)[offs++] = len;	617	pkt [offs++] = len;
366	memcpy (&((*pkt)[offs]), suffix, len);	618	memcpy (pkt.at (offs), domain, len);
367	offs += len;	619	offs += len;
368		620
369	if (!*end)	621	if (!*end)
370	break;	622	break;
371		623
372	suffix = end + 1;	624	domain = end + 1;
		625	}
		626	}
		627
		628	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		629	{
		630	stdhdr = true;
		631	this->seqno = seqno;
		632
		633	timeout = NOW + INITIAL_TIMEOUT;
		634
		635	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		636	pkt->qdcount = htons (1);
		637
		638	int offs = 6*2;
		639	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
		640	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		641	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		642
		643	char enc[256], *encp = enc;
		644	encode_header (enc, THISNODE->id, seqno);
		645
		646	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		647
		648	if (datalen > stream.size ())
		649	datalen = stream.size ();
		650
		651	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		652	stream.remove (datalen);
		653
		654	while (enclen)
373	}	655	{
		656	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		657
		658	(*pkt)[offs++] = lbllen;
		659	memcpy (pkt->at (offs), encp, lbllen);
		660
		661	offs += lbllen;
		662	encp += lbllen;
		663
		664	enclen -= lbllen;
		665	}
		666
		667	append_domain (*pkt, offs, dns->c->conf->domain);
374		668
375	(*pkt)[offs++] = 0;	669	(*pkt)[offs++] = 0;
376	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	670	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	671	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378		672
379	pkt->len = offs;	673	pkt->len = offs;
		674	}
380		675
381	c->vpn->dns_sndpq.push_back (this);	676	void dns_snd::gen_syn_req ()
		677	{
		678	timeout = NOW + INITIAL_SYN_TIMEOUT;
		679
		680	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		681	pkt->qdcount = htons (1);
		682
		683	int offs = 6 * 2;
		684
		685	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		686
		687	assert (elen <= MAX_LBL_SIZE);
		688
		689	(*pkt)[offs] = elen;
		690	offs += elen + 1;
		691	append_domain (*pkt, offs, dns->c->conf->domain);
		692
		693	(*pkt)[offs++] = 0;
		694	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
		695	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		696
		697	pkt->len = offs;
		698	}
		699
		700	struct dns_rcv
		701	{
		702	int seqno;
		703	dns_packet *pkt; // reply packet
		704	u8 data [MAXSIZE]; // actually part of the reply packet...
		705	int datalen;
		706
		707	dns_rcv (int seqno, u8 *data, int datalen);
		708	~dns_rcv ();
		709	};
		710
		711	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		712	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		713	{
		714	memcpy (this->data, data, datalen);
		715	}
		716
		717	dns_rcv::~dns_rcv ()
		718	{
		719	delete pkt;
382	}	720	}
383		721
384	/////////////////////////////////////////////////////////////////////////////	722	/////////////////////////////////////////////////////////////////////////////
385		723
386	struct dns_cfg	724	dns_connection::dns_connection (connection *c)
		725	: c (c)
		726	, rcvdq (MAX_BACKLOG * 2)
		727	, snddq (MAX_BACKLOG)
		728	, tw (this, &dns_connection::time_cb)
387	{	729	{
388	u8 id1, id2, id3;	730	vpn = c->vpn;
389	u8 def_ttl;
390	u8 unused1;
391	u16 max_size;
392	u8 flags1, flags2;
393	};
394		731
395	dns_packet *	732	established = false;
		733
		734	rcvseq = repseq = sndseq = 0;
		735
		736	last_sent = last_received = 0;
		737	poll_interval = 0.5; // starting here
		738	send_interval = 0.5; // starting rate
		739	min_latency = INITIAL_TIMEOUT;
		740	}
		741
		742	dns_connection::~dns_connection ()
		743	{
		744	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		745	i != rcvpq.end ();
		746	++i)
		747	delete *i;
		748	}
		749
		750	void dns_connection::receive_rep (dns_rcv *r)
		751	{
		752	if (r->datalen)
		753	{
		754	last_received = NOW;
		755	tw.trigger ();
		756
		757	poll_interval = send_interval;
		758	}
		759	else
		760	{
		761	poll_interval *= 1.5;
		762
		763	if (poll_interval > MAX_POLL_INTERVAL)
		764	poll_interval = MAX_POLL_INTERVAL;
		765	}
		766
		767	rcvpq.push_back (r);
		768
		769	redo:
		770
		771	// find next packet
		772	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		773	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		774	{
		775	// enter the packet into our input stream
		776	r = *i;
		777
		778	// remove the oldest packet, look forward, as it's oldest first
		779	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		780	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		781	{
		782	delete *j;
		783	rcvpq.erase (j);
		784	break;
		785	}
		786
		787	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		788
		789	if (!rcvdq.put (r->data, r->datalen))
		790	{
		791	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		792	abort (); // MUST never overflow, can be caused by data corruption, TODO
		793	}
		794
		795	while (vpn_packet *pkt = rcvdq.get ())
		796	{
		797	sockinfo si;
		798	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
		799
		800	vpn->recv_vpn_packet (pkt, si);
		801
		802	delete pkt;
		803	}
		804
		805	// check for further packets
		806	goto redo;
		807	}
		808	}
		809
		810	void
396	vpn::dnsv4_server (dns_packet *pkt)	811	vpn::dnsv4_server (dns_packet &pkt)
397	{	812	{
398	u16 flags = ntohs (pkt->flags);	813	u16 flags = ntohs (pkt.flags);
399		814
400	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401	int offs = 6 * 2; // skip header	815	int offs = 6 * 2; // skip header
402		816
403	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	817	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404		818
405	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	819	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406	&& pkt->qdcount == htons (1))	820	&& pkt.qdcount == htons (1))
407	{	821	{
408	char qname[MAXSIZE];	822	char qname [MAXSIZE];
409	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	823	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410		824
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++];	825	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	826	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416		827
417	pkt->qdcount = htons (1);	828	pkt.qdcount = htons (1);
418	pkt->ancount = 0;	829	pkt.ancount = 0;
419	pkt->nscount = 0; // should be self, as other nameservers reply like this	830	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	831	pkt.arcount = 0; // a record for self, as other nameservers reply like this
421		832
422	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	833	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423		834
424	int dlen = strlen (THISNODE->domain);	835	int dlen = strlen (THISNODE->domain);
425		836
426	if (qclass == RR_CLASS_IN	837	if (qclass == RR_CLASS_IN
427	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428	&& qlen > dlen + 1	838	&& qlen > dlen + 1
429	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	839	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430	{	840	{
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	841	// now generate reply
444	rep->ancount = htons (1); // one answer RR	842	pkt.ancount = htons (1); // one answer RR
445	rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	843	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446		844
447	(*rep) [offs++] = 0xc0;	845	if ((qtype == RR_TYPE_ANY
448	(*rep) [offs++] = 6 * 2; // same as in query section	846	|| qtype == RR_TYPE_TXT
449		847	|| qtype == RR_TYPE_NULL)
450	(*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT;	848	&& 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	{	849	{
470	int sndlen = --dlen;	850	// correct class, domain: parse
		851	int client, seqno;
		852	decode_header (qname, client, seqno);
471		853
472	if (sndlen + txtlen > 255)	854	u8 data[MAXSIZE];
473	sndlen = 255 - txtlen;	855	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
474		856
475	sndlen = 0;	857	if (0 < client && client <= conns.size ())
		858	{
		859	connection *c = conns [client - 1];
		860	dns_connection *dns = c->dns;
		861	dns_rcv *rcv;
476		862
477	(*rep)[offs++] = sndlen + txtlen;	863	if (dns)
478	memcpy (&((*rep)[offs]), txt, txtlen);	864	{
		865	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		866	if (SEQNO_EQ ((*i)->seqno, seqno))
		867	{
		868	// already seen that request: simply reply with the cached reply
		869	dns_rcv *r = *i;
		870
		871	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		872
		873	// refresh header & id, as the retry count could have changed
		874	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		875	r->pkt->id = pkt.id;
		876
		877	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		878
		879	goto duplicate_request;
		880	}
		881
		882	// new packet, queue
		883	rcv = new dns_rcv (seqno, data, datalen);
		884	dns->receive_rep (rcv);
		885	}
		886
		887	{
		888	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		889
		890	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		891	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		892	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		893	pkt [offs++] = 0; pkt [offs++] = 0;
		894	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		895
		896	int rdlen_offs = offs += 2;
		897
		898	if (dns)
		899	{
		900	int dlen = ntohs (dns->cfg.max_size) - offs;
		901
		902	// bind doesn't compress well, so reduce further by one label length
		903	dlen -= qlen;
		904
		905	// only put data into in-order sequence packets, if
		906	// we receive out-of-order packets we generate empty
		907	// replies
		908	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		909	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		910	{
		911	dns->repseq = seqno;
		912
		913	while (dlen > 1 && !dns->snddq.empty ())
		914	{
		915	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		916
		917	if (txtlen > dns->snddq.size ())
		918	txtlen = dns->snddq.size ();
		919
		920	pkt[offs++] = txtlen;
		921	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
479	offs += txtlen;	922	offs += txtlen;
		923	dns->snddq.remove (txtlen);
480		924
481	//if (sndlen + txtlen > dns_snddq.	925	dlen -= txtlen + 1;
		926	}
		927	}
		928
		929	// avoid completely empty TXT rdata
		930	if (offs == rdlen_offs)
		931	pkt[offs++] = 0;
		932
		933	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		934	}
		935	else
		936	{
		937	// send RST
		938	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		939	pkt [offs++] = CMD_IP_RST;
		940	}
		941
		942	int rdlen = offs - rdlen_offs;
		943
		944	pkt [rdlen_offs - 2] = rdlen >> 8;
		945	pkt [rdlen_offs - 1] = rdlen;
		946
		947	if (dns)
		948	{
		949	// now update dns_rcv copy
		950	rcv->pkt->len = offs;
		951	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		952	}
		953	}
		954
		955	duplicate_request: ;
		956	}
		957	else
		958	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
482	}	959	}
		960	else if (qtype == RR_TYPE_A
		961	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		962	{
		963	dns_cfg cfg;
		964	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		965	int client = ntohs (cfg.client);
483		966
484	int rdlen = offs - rdlen_offs;	967	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485		968
486	(*rep) [rdlen_offs - 2] = rdlen >> 8;	969	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487	(*rep) [rdlen_offs - 1] = rdlen;	970	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488	#endif	971	pkt [offs++] = 0; pkt [offs++] = 0;
		972	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		973	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		974
		975	slog (L_INFO, _("DNS: client %d connects"), client);
		976
		977	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		978	pkt [offs++] = CMD_IP_REJ;
		979
		980	if (0 < client && client <= conns.size ())
		981	{
		982	connection *c = conns [client - 1];
		983
		984	if (cfg.valid ())
		985	{
		986	pkt [offs - 1] = CMD_IP_SYN;
		987
		988	delete c->dns;
		989	c->dns = new dns_connection (c);
		990	c->dns->cfg = cfg;
		991	}
		992	}
		993	}
489	}	994	}
490	}
491		995
492	pkt->len = offs;	996	pkt.len = offs;
493	return pkt;	997	}
494	}	998	}
495		999
496	void	1000	void
497	vpn::dnsv4_client (dns_packet *pkt)	1001	vpn::dnsv4_client (dns_packet &pkt)
498	{	1002	{
499	u16 flags = ntohs (pkt->flags);	1003	u16 flags = ntohs (pkt.flags);
500	int offs = 6 * 2; // skip header	1004	int offs = 6 * 2; // skip header
501		1005
502	pkt->qdcount = ntohs (pkt->qdcount);	1006	pkt.qdcount = ntohs (pkt.qdcount);
503	pkt->ancount = ntohs (pkt->ancount);	1007	pkt.ancount = ntohs (pkt.ancount);
504		1008
		1009	// go through our request list and find the corresponding request
505	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1010	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506	i != dns_sndpq.end ();	1011	i != dns_sndpq.end ();
507	++i)	1012	++i)
508	if ((*i)->pkt->id == pkt->id)	1013	if ((*i)->pkt->id == pkt.id)
509	{	1014	{
		1015	dns_connection *dns = (*i)->dns;
510	connection *c = (*i)->conn;	1016	connection *c = dns->c;
511	printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D	1017	int seqno = (*i)->seqno;
		1018	u8 data[MAXSIZE], *datap = data;
		1019
		1020	if ((*i)->retry)
		1021	{
		1022	dns->send_interval *= 1.01;
		1023	if (dns->send_interval > MAX_SEND_INTERVAL)
		1024	dns->send_interval = MAX_SEND_INTERVAL;
		1025	}
		1026	else
		1027	{
		1028	#if 0
		1029	dns->send_interval *= 0.999;
		1030	#endif
		1031	// the latency surely puts an upper bound on
		1032	// the minimum send interval
		1033	double latency = NOW - (*i)->sent;
		1034
		1035	if (latency < dns->min_latency)
		1036	dns->min_latency = latency;
		1037
		1038	if (dns->send_interval > dns->min_latency * LATENCY_FACTOR)
		1039	dns->send_interval = dns->min_latency * LATENCY_FACTOR;
		1040
		1041	if (dns->send_interval < MIN_SEND_INTERVAL)
		1042	dns->send_interval = MIN_SEND_INTERVAL;
		1043	}
		1044
512	delete *i;	1045	delete *i;
513	dns_sndpq.erase (i);	1046	dns_sndpq.erase (i);
514		1047
515	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1048	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516	{	1049	{
517	char qname[MAXSIZE];	1050	char qname[MAXSIZE];
518		1051
519	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1052	while (pkt.qdcount-- && offs < MAXSIZE - 4)
520	{	1053	{
521	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1054	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522	offs += 4; // skip qtype, qclass	1055	offs += 4; // skip qtype, qclass
523	}	1056	}
524		1057
525	while (pkt->ancount-- && offs < MAXSIZE - 10)	1058	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526	{	1059	{
527	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1060	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528		1061
529	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1062	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1063	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531	u32 ttl = (*pkt) [offs++] << 24;	1064	u32 ttl = pkt [offs++] << 24;
532	ttl |= (*pkt) [offs++] << 16;	1065	ttl |= pkt [offs++] << 16;
533	ttl |= (*pkt) [offs++] << 8;	1066	ttl |= pkt [offs++] << 8;
534	ttl |= (*pkt) [offs++];	1067	ttl |= pkt [offs++];
535
536	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1068	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537		1069
538	printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen);	1070	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
539
540	offs += rdlen;
541
542	if (MAXSIZE - offs < rdlen)
543	{	1071	{
		1072	if (rdlen <= MAXSIZE - offs)
		1073	{
544	// decode bytes, finally	1074	// decode bytes, finally
		1075
		1076	while (rdlen)
		1077	{
		1078	int txtlen = pkt [offs++];
		1079
		1080	assert (txtlen + offs < MAXSIZE - 1);
		1081
		1082	memcpy (datap, pkt.at (offs), txtlen);
		1083	datap += txtlen; offs += txtlen;
		1084
		1085	rdlen -= txtlen + 1;
		1086	}
		1087	}
		1088	}
		1089	else if (qtype == RR_TYPE_A)
		1090	{
		1091	u8 ip [4];
		1092
		1093	ip [0] = pkt [offs++];
		1094	ip [1] = pkt [offs++];
		1095	ip [2] = pkt [offs++];
		1096	ip [3] = pkt [offs++];
		1097
		1098	if (ip [0] == CMD_IP_1
		1099	&& ip [1] == CMD_IP_2
		1100	&& ip [2] == CMD_IP_3)
		1101	{
		1102	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1103
		1104	if (ip [3] == CMD_IP_RST)
		1105	{
		1106	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1107
		1108	delete dns; c->dns = 0;
		1109
		1110	return;
		1111	}
		1112	else if (ip [3] == CMD_IP_SYN)
		1113	{
		1114	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1115	dns->established = true;
		1116	}
		1117	else if (ip [3] == CMD_IP_REJ)
		1118	{
		1119	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1120	abort ();
		1121	}
		1122	else
		1123	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1124	}
		1125	else
		1126	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1127	ip [0], ip [1], ip [2], ip [3]);
		1128
		1129	return;
		1130	}
		1131
		1132	int client, rseqno;
		1133	decode_header (qname, client, rseqno);
		1134
		1135	if (client != THISNODE->id)
		1136	{
		1137	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1138	datap = 0;
		1139	}
		1140	else if (rseqno != seqno)
		1141	{
		1142	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1143	datap = 0;
545	}	1144	}
546	}	1145	}
547	}	1146	}
548		1147
		1148	// todo: pkt now used
		1149	if (datap)
		1150	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1151
549	break;	1152	break;
550	}	1153	}
551	}	1154	}
552		1155
553	void	1156	void
…		…
557	{	1160	{
558	dns_packet *pkt = new dns_packet;	1161	dns_packet *pkt = new dns_packet;
559	struct sockaddr_in sa;	1162	struct sockaddr_in sa;
560	socklen_t sa_len = sizeof (sa);	1163	socklen_t sa_len = sizeof (sa);
561		1164
562	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1165	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563		1166
564	if (pkt->len > 0)	1167	if (pkt->len > 0)
565	if (THISNODE->dns_port)
566	{	1168	{
567	pkt = dnsv4_server (pkt);	1169	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);	1170	dnsv4_client (*pkt);
		1171	else
		1172	{
		1173	dnsv4_server (*pkt);
		1174	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
		1175	}
		1176
		1177	delete pkt;
		1178	}
572	}	1179	}
573	}	1180	}
574		1181
575	bool	1182	bool
576	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1183	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577	{	1184	{
578	// never initialized	1185	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		1186
584	dns_rcvseq = dns_sndseq = 0;	1187	assert (0 < client && client <= conns.size ());
585		1188
586	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1189	connection *c = conns [client - 1];
587	}	1190
		1191	if (!c->dns)
		1192	c->dns = new dns_connection (c);
588		1193
589	if (!dns_snddq->put (pkt))	1194	if (c->dns->snddq.put (pkt))
590	return false;	1195	c->dns->tw.trigger ();
591		1196
592	// start timer if neccessary	1197	// always return true even if the buffer overflows
593	if (!dnsv4_tw.active)
594	dnsv4_cb (dnsv4_tw);
595
596	return true;	1198	return true;
597	}	1199	}
598		1200
599	void	1201	void
		1202	connection::dnsv4_reset_connection ()
		1203	{
		1204	//delete dns; dns = 0; //TODO
		1205	}
		1206
		1207	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1208
		1209	void
600	connection::dnsv4_cb (time_watcher &w)	1210	dns_connection::time_cb (time_watcher &w)
601	{	1211	{
		1212	// servers have to be polled
		1213	if (THISNODE->dns_port)
		1214	return;
		1215
602	// check for timeouts and (re)transmit	1216	// check for timeouts and (re)transmit
603	tstamp next = NOW + 60;	1217	tstamp next = NOW + poll_interval;
604	dns_req *send = 0;	1218	dns_snd *send = 0;
605		1219
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 ();	1220	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609	i != vpn->dns_sndpq.end ();	1221	i != vpn->dns_sndpq.end ();
610	++i)	1222	++i)
611	{	1223	{
612	dns_req *r = *i;	1224	dns_snd *r = *i;
613		1225
614	if (r->next <= NOW)	1226	if (r->timeout <= NOW)
615	{	1227	{
616	if (!send)	1228	if (!send)
617	{	1229	{
618	send = r;	1230	send = r;
619		1231
620	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621	r->retry++;	1232	r->retry++;
622	r->next = NOW + r->retry;	1233	r->timeout = NOW + (r->retry * min_latency * TIMEOUT_FACTOR);
		1234	printf ("TO %d %f\n", r->retry, r->timeout - NOW);//D
		1235
		1236	// the following code changes the query section a bit, forcing
		1237	// the forwarder to generate a new request
		1238	if (r->stdhdr)
		1239	{
		1240	//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1241	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1242	}
623	}	1243	}
624	}	1244	}
625		1245	else
626	if (r->next < next)	1246	NEXT (r->timeout);
627	next = r->next;
628	}	1247	}
629		1248
630	if (!send	1249	if (!send)
		1250	{
		1251	// generate a new packet, if wise
		1252
		1253	if (!established)
		1254	{
		1255	if (vpn->dns_sndpq.empty ())
		1256	{
		1257	send = new dns_snd (this);
		1258
		1259	cfg.reset (THISNODE->id);
		1260	send->gen_syn_req ();
		1261	}
		1262	}
631	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1263	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
632	send = new dns_req (this, dns_sndseq++, dns_snddq);	1264	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1265	{
		1266	if (last_sent + send_interval <= NOW)
		1267	{
		1268	//printf ("sending data request etc.\n"); //D
		1269	if (!snddq.empty () || last_received + 1. > NOW)
		1270	{
		1271	poll_interval = send_interval;
		1272	NEXT (NOW + send_interval);
		1273	}
633		1274
634	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);	1275	send = new dns_snd (this);
		1276	send->gen_stream_req (sndseq, snddq);
		1277	send->timeout = NOW + min_latency * TIMEOUT_FACTOR;
		1278
		1279	sndseq = (sndseq + 1) & SEQNO_MASK;
		1280	}
		1281	else
		1282	NEXT (last_sent + send_interval);
		1283	}
		1284
		1285	if (send)
		1286	vpn->dns_sndpq.push_back (send);
		1287	}
635		1288
636	if (send)	1289	if (send)
637	{	1290	{
638	dns_packet *pkt = send->pkt;	1291	last_sent = NOW;
639		1292	sendto (vpn->dnsv4_fd,
640	next = min_next;	1293	send->pkt->at (0), send->pkt->len, 0,
641		1294	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	}	1295	}
644	else if (next < min_next)	1296
645	next = min_next;	1297	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1298	poll_interval, send_interval, next - NOW,
		1299	vpn->dns_sndpq.size (), snddq.size (),
		1300	rcvpq.size ());
		1301
		1302	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1303	if (next < NOW + 0.001)
		1304	next = NOW + 0.1;
646		1305
647	w.start (next);	1306	w.start (next);
648	}	1307	}
649		1308
650	#endif	1309	#endif

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