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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 1.24 by pcg, Mon Mar 7 01:31:26 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 MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data
45	#define MAX_RETRY 60.	50	#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data
		51	#define ACTIVITY_INTERVAL 5.
		52
		53	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		54	#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
		55
		56	#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
		57	#define MAX_SEND_INTERVAL 0.5 // optimistic?
46		58
47	#define MAX_OUTSTANDING 10 // max. outstanding requests	59	#define MAX_OUTSTANDING 10 // max. outstanding requests
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	60	#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	61	#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		62
52	/*	63	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
		64	// 240 leaves about 4 bytes of server reply data
		65	// every two request bytes less give room for one reply byte
53		66
54	protocol, in shorthand :)	67	#define SEQNO_MASK 0x3fff
55		68	#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		69
68	#define MAX_LBL_SIZE 63	70	#define MAX_LBL_SIZE 63
69	#define MAX_PKT_SIZE 512	71	#define MAX_PKT_SIZE 512
70		72
		73	#define RR_TYPE_A 1
		74	#define RR_TYPE_NULL 10
71	#define RR_TYPE_TXT 16	75	#define RR_TYPE_TXT 16
72	#define RR_TYPE_ANY 255	76	#define RR_TYPE_ANY 255
		77
73	#define RR_CLASS_IN 1	78	#define RR_CLASS_IN 1
74		79
75	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	80	#define CMD_IP_1 207
76	struct dns64	81	#define CMD_IP_2 46
77	{	82	#define CMD_IP_3 236
78	static const char encode_chars[64 + 1];	83	#define CMD_IP_RST 29
79	static s8 decode_chars[256];	84	#define CMD_IP_SYN 113
		85	#define CMD_IP_REJ 32
80		86
81	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	87	// works for cmaps up to 255 (not 256!)
82	static int decode_len (int bytes) { return (bytes * 6) / 8; }	88	struct charmap
		89	{
		90	enum { INVALID = (u8)255 };
		91
		92	char encode [256]; // index => char
		93	u8 decode [256]; // char => index
		94	unsigned int size;
		95
		96	charmap (const char *cmap);
		97	};
		98
		99	charmap::charmap (const char *cmap)
		100	{
		101	char *enc = encode;
		102	u8 *dec = decode;
		103
		104	memset (enc, (char) 0, 256);
		105	memset (dec, (char)INVALID, 256);
		106
		107	for (size = 0; cmap [size]; size++)
		108	{
		109	enc [size] = cmap [size];
		110	dec [(u8)enc [size]] = size;
		111	}
		112
		113	assert (size < 256);
		114	}
		115
		116	#define MAX_DEC_LEN 500
		117	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		118	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		119
		120	// ugly. minimum base is 16(!)
		121	struct basecoder
		122	{
		123	charmap cmap;
		124	unsigned int enc_len [MAX_DEC_LEN];
		125	unsigned int dec_len [MAX_ENC_LEN];
		126
		127	unsigned int encode_len (unsigned int len);
		128	unsigned int decode_len (unsigned int len);
		129
83	static int encode (char *dst, u8 *src, int len);	130	unsigned int encode (char *dst, u8 *src, unsigned int len);
84	static int decode (u8 *dst, char *src, int len);	131	unsigned int decode (u8 *dst, char *src, unsigned int len);
85		132
86	dns64 ();	133	basecoder (const char *cmap);
87	} dns64;	134	};
88		135
89	const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";	136	basecoder::basecoder (const char *cmap)
90	s8 dns64::decode_chars[256];	137	: cmap (cmap)
91
92	dns64::dns64 ()
93	{	138	{
94	for (int i = 0; i < 64; i++)	139	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95	decode_chars [encode_chars [i]] = i + 1;	140	{
96	}	141	u8 src [MAX_DEC_LEN];
		142	u8 dst [MAX_ENC_LEN];
97		143
98	int dns64::encode (char *dst, u8 *src, int len)	144	memset (src, 255, len);
		145
		146	mp_limb_t m [MAX_LIMBS];
		147	mp_size_t n;
		148
		149	n = mpn_set_str (m, src, len, 256);
		150	n = mpn_get_str (dst, this->cmap.size, m, n);
		151
		152	for (int i = 0; !dst [i]; ++i)
		153	n--;
		154
		155	enc_len [len] = n;
		156	dec_len [n] = len;
		157	}
		158	}
		159
		160	unsigned int basecoder::encode_len (unsigned int len)
99	{	161	{
100	// slow, but easy to debug	162	return enc_len [len];
101	char *beg = dst;	163	}
102	unsigned int accum, bits = 0;	164
		165	unsigned int basecoder::decode_len (unsigned int len)
		166	{
		167	while (len && !dec_len [len])
		168	--len;
		169
		170	return dec_len [len];
		171	}
		172
		173	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		174	{
		175	if (!len || len > MAX_DEC_LEN)
		176	return 0;
		177
		178	int elen = encode_len (len);
		179
		180	mp_limb_t m [MAX_LIMBS];
		181	mp_size_t n;
		182
		183	u8 dst_ [MAX_ENC_LEN];
		184
		185	n = mpn_set_str (m, src, len, 256);
		186	n = mpn_get_str (dst_, cmap.size, m, n);
		187
		188	int plen = elen; // for padding
		189
		190	while (n < plen)
		191	{
		192	*dst++ = cmap.encode [0];
		193	plen--;
		194	}
		195
		196	for (unsigned int i = n - plen; i < n; ++i)
		197	*dst++ = cmap.encode [dst_ [i]];
		198
		199	return elen;
		200	}
		201
		202	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		203	{
		204	if (!len || len > MAX_ENC_LEN)
		205	return 0;
		206
		207	u8 src_ [MAX_ENC_LEN];
		208	unsigned int elen = 0;
103		209
104	while (len--)	210	while (len--)
105	{	211	{
106	accum <<= 8;	212	u8 val = cmap.decode [(u8)*src++];
107	accum |= *src++;
108	bits += 8;
109		213
110	while (bits >= 6)	214	if (val != charmap::INVALID)
111	{	215	src_ [elen++] = val;
112	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	216	}
113	bits -= 6;	217
114	}	218	int dlen = decode_len (elen);
		219
		220	mp_limb_t m [MAX_LIMBS];
		221	mp_size_t n;
		222
		223	u8 dst_ [MAX_DEC_LEN];
		224
		225	n = mpn_set_str (m, src_, elen, cmap.size);
		226	n = mpn_get_str (dst_, 256, m, n);
		227
		228	if (n < dlen)
115	}	229	{
		230	memset (dst, 0, dlen - n);
		231	memcpy (dst + dlen - n, dst_, n);
		232	}
		233	else
		234	memcpy (dst, dst_ + n - dlen, dlen);
116		235
117	if (bits)	236	return dlen;
118	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120	return dst - beg;
121	}	237	}
122		238
123	int dns64::decode (u8 *dst, char *src, int len)	239	#if 0
124	{	240	struct test { test (); } test;
125	// slow, but easy to debug
126	u8 *beg = dst;
127	unsigned int accum, bits = 0;
128		241
129	while (len--)	242	test::test ()
		243	{
		244	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		245
		246	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		247	static char enc[200];
		248	static u8 dec[200];
		249
		250	for (int i = 1; i < 20; i++)
130	{	251	{
131	s8 chr = decode_chars [(u8)*src++];	252	int elen = cdc.encode (enc, in, i);
		253	int dlen = cdc.decode (dec, enc, elen);
132		254
133	if (!chr)	255	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	}	256	}
		257	abort ();
		258	}
		259	#endif
146		260
147	return dst - beg;	261	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		262	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		263	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		264	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		265	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		266
		267	/////////////////////////////////////////////////////////////////////////////
		268
		269	#define HDRSIZE 6
		270
		271	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		272	{
		273	seqno &= SEQNO_MASK;
		274
		275	u8 hdr[3] = {
		276	clientid,
		277	(seqno >> 8) | (retry << 6),
		278	seqno,
		279	};
		280
		281	assert (clientid < 256);
		282
		283	cdc26.encode (data, hdr, 3);
		284	}
		285
		286	inline void decode_header (char *data, int &clientid, int &seqno)
		287	{
		288	u8 hdr[3];
		289
		290	cdc26.decode (hdr, data, HDRSIZE);
		291
		292	clientid = hdr[0];
		293	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
148	}	294	}
149		295
150	/////////////////////////////////////////////////////////////////////////////	296	/////////////////////////////////////////////////////////////////////////////
151		297
152	struct byte_stream	298	struct byte_stream
…		…
159	~byte_stream ();	305	~byte_stream ();
160		306
161	bool empty () { return !fill; }	307	bool empty () { return !fill; }
162	int size () { return fill; }	308	int size () { return fill; }
163		309
		310	bool put (u8 *data, unsigned int datalen);
164	bool put (vpn_packet *pkt);	311	bool put (vpn_packet *pkt);
165	vpn_packet *get ();	312	vpn_packet *get ();
166		313
167	u8 *begin () { return data; }	314	u8 *begin () { return data; }
168	void remove (int count);	315	void remove (int count);
…		…
180	}	327	}
181		328
182	void byte_stream::remove (int count)	329	void byte_stream::remove (int count)
183	{	330	{
184	if (count > fill)	331	if (count > fill)
185	abort ();	332	assert (count <= fill);
186		333
187	memmove (data, data + count, fill -= count);	334	memmove (data, data + count, fill -= count);
		335	}
		336
		337	bool byte_stream::put (u8 *data, unsigned int datalen)
		338	{
		339	if (maxsize - fill < datalen)
		340	return false;
		341
		342	memcpy (this->data + fill, data, datalen); fill += datalen;
		343
		344	return true;
188	}	345	}
189		346
190	bool byte_stream::put (vpn_packet *pkt)	347	bool byte_stream::put (vpn_packet *pkt)
191	{	348	{
192	if (maxsize - fill < pkt->len + 2)	349	if (maxsize - fill < pkt->len + 2)
193	return false;	350	return false;
194		351
195	data [fill++] = pkt->len >> 8;	352	data [fill++] = pkt->len >> 8;
196	data [fill++] = pkt->len;	353	data [fill++] = pkt->len;
197		354
198	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	355	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199		356
200	return true;	357	return true;
201	}	358	}
202		359
203	vpn_packet *byte_stream::get ()	360	vpn_packet *byte_stream::get ()
204	{	361	{
		362	unsigned int len;
		363
		364	for (;;)
		365	{
205	int len = (data [0] << 8) | data [1];	366	len = (data [0] << 8) | data [1];
206		367
		368	if (len <= MAXSIZE || fill < 2)
		369	break;
		370
		371	// TODO: handle this better than skipping, e.g. by reset
		372	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		373	remove (1);
		374	}
		375
207	if (fill < len + 2)	376	if (fill < len + 2)
208	return 0;	377	return 0;
209		378
210	vpn_packet *pkt = new vpn_packet;	379	vpn_packet *pkt = new vpn_packet;
		380
		381	pkt->len = len;
211	memcpy (&((*pkt)[0]), data + 2, len);	382	memcpy (pkt->at (0), data + 2, len);
212	remove (len + 2);	383	remove (len + 2);
213		384
214	return pkt;	385	return pkt;
215	}	386	}
216		387
217	/////////////////////////////////////////////////////////////////////////////	388	/////////////////////////////////////////////////////////////////////////////
218		389
219	#define FLAG_QUERY ( 0 << 15)	390	#define FLAG_QUERY ( 0 << 15)
220	#define FLAG_RESPONSE ( 1 << 15)	391	#define FLAG_RESPONSE ( 1 << 15)
221	#define FLAG_OP_MASK (15 << 14)	392	#define FLAG_OP_MASK (15 << 11)
222	#define FLAG_OP_QUERY ( 0 << 11)	393	#define FLAG_OP_QUERY ( 0 << 11)
223	#define FLAG_AA ( 1 << 10)	394	#define FLAG_AA ( 1 << 10)
224	#define FLAG_TC ( 1 << 9)	395	#define FLAG_TC ( 1 << 9)
225	#define FLAG_RD ( 1 << 8)	396	#define FLAG_RD ( 1 << 8)
226	#define FLAG_RA ( 1 << 7)	397	#define FLAG_RA ( 1 << 7)
		398	#define FLAG_AUTH ( 1 << 5)
227	#define FLAG_RCODE_MASK (15 << 0)	399	#define FLAG_RCODE_MASK (15 << 0)
228	#define FLAG_RCODE_OK ( 0 << 0)	400	#define FLAG_RCODE_OK ( 0 << 0)
229	#define FLAG_RCODE_FORMERR ( 1 << 0)	401	#define FLAG_RCODE_FORMERR ( 1 << 0)
230	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	402	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	403	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232	#define FLAG_RCODE_REFUSED ( 5 << 0)	404	#define FLAG_RCODE_REFUSED ( 5 << 0)
233		405
234	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	406	#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)	407	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
		408
		409	struct dns_cfg
		410	{
		411	static int next_uid;
		412
		413	u8 id1, id2, id3, id4;
		414
		415	u8 version;
		416	u8 flags;
		417	u8 rrtype;
		418	u8 def_ttl;
		419
		420	u16 client;
		421	u16 uid; // to make request unique
		422
		423	u16 max_size;
		424	u8 seq_cdc;
		425	u8 req_cdc;
		426
		427	u8 rep_cdc;
		428	u8 r2, r3, r4;
		429
		430	u8 r5, r6, r7, r8;
		431
		432	void reset (int clientid);
		433	bool valid ();
		434	};
		435
		436	int dns_cfg::next_uid;
		437
		438	void dns_cfg::reset (int clientid)
		439	{
		440	id1 = 'G';
		441	id2 = 'V';
		442	id3 = 'P';
		443	id4 = 'E';
		444
		445	version = 1;
		446
		447	rrtype = RR_TYPE_TXT;
		448	flags = 0;
		449	def_ttl = 0;
		450	seq_cdc = 26;
		451	req_cdc = 62;
		452	rep_cdc = 0;
		453	max_size = ntohs (MAX_PKT_SIZE);
		454	client = ntohs (clientid);
		455	uid = next_uid++;
		456
		457	r2 = r3 = r4 = 0;
		458	r4 = r5 = r6 = r7 = 0;
		459	}
		460
		461	bool dns_cfg::valid ()
		462	{
		463	return id1 == 'G'
		464	&& id2 == 'V'
		465	&& id3 == 'P'
		466	&& id4 == 'E'
		467	&& seq_cdc == 26
		468	&& req_cdc == 62
		469	&& rep_cdc == 0
		470	&& version == 1
		471	&& max_size == ntohs (MAX_PKT_SIZE);
		472	}
236		473
237	struct dns_packet : net_packet	474	struct dns_packet : net_packet
238	{	475	{
239	u16 id;	476	u16 id;
240	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	477	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
241	u16 qdcount, ancount, nscount, arcount;	478	u16 qdcount, ancount, nscount, arcount;
242		479
243	u8 data[MAXSIZE - 6 * 2];	480	u8 data [MAXSIZE - 6 * 2];
244		481
245	int decode_label (char *data, int size, int &offs);	482	int decode_label (char *data, int size, int &offs);
246	};	483	};
247		484
248	int dns_packet::decode_label (char *data, int size, int &offs)	485	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
279	return data - orig;	516	return data - orig;
280	}	517	}
281		518
282	/////////////////////////////////////////////////////////////////////////////	519	/////////////////////////////////////////////////////////////////////////////
283		520
		521	static u16 dns_id = 0; // TODO: should be per-vpn
		522
		523	static u16 next_id ()
		524	{
		525	if (!dns_id)
		526	dns_id = time (0);
		527
		528	// the simplest lsfr with periodicity 65535 i could find
		529	dns_id = (dns_id << 1)
		530	| (((dns_id >> 1)
		531	^ (dns_id >> 2)
		532	^ (dns_id >> 4)
		533	^ (dns_id >> 15)) & 1);
		534
		535	return dns_id;
		536	}
		537
284	struct dns_req	538	struct dns_rcv;
		539	struct dns_snd;
		540
		541	struct dns_connection
		542	{
		543	connection *c;
		544	struct vpn *vpn;
		545
		546	dns_cfg cfg;
		547
		548	bool established;
		549
		550	tstamp last_received;
		551	tstamp last_sent;
		552	double last_latency;
		553	double poll_interval, send_interval;
		554
		555	vector<dns_rcv *> rcvpq;
		556
		557	byte_stream rcvdq; int rcvseq;
		558	byte_stream snddq; int sndseq;
		559
		560	void time_cb (time_watcher &w); time_watcher tw;
		561	void receive_rep (dns_rcv *r);
		562
		563	dns_connection (connection *c);
		564	~dns_connection ();
		565	};
		566
		567	struct dns_snd
285	{	568	{
286	dns_packet *pkt;	569	dns_packet *pkt;
287	tstamp next;	570	tstamp timeout, sent;
288	int retry;	571	int retry;
289	connection *conn;	572	struct dns_connection *dns;
		573	int seqno;
		574	bool stdhdr;
290		575
291	dns_req (connection *c, int seqno, byte_stream *stream);	576	void gen_stream_req (int seqno, byte_stream &stream);
		577	void gen_syn_req ();
		578
		579	dns_snd (dns_connection *dns);
		580	~dns_snd ();
292	};	581	};
293		582
294	struct dns_rep	583	dns_snd::dns_snd (dns_connection *dns)
		584	: dns (dns)
295	{	585	{
296	};	586	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;	587	retry = 0;
		588	seqno = 0;
		589	sent = NOW;
		590	stdhdr = false;
305		591
306	pkt = new dns_packet;	592	pkt = new dns_packet;
307		593
308	pkt->id = dns_id++;	594	pkt->id = next_id ();
309	pkt->flags = DEFAULT_CLIENT_FLAGS;	595	}
310	pkt->qdcount = htons (1);
311	pkt->ancount = 0;
312	pkt->nscount = 0;
313	pkt->arcount = 0;
314		596
315	int offs = 6*2;	597	dns_snd::~dns_snd ()
316	int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length	598	{
		599	delete pkt;
		600	}
317		601
318	u8 lbl[64]; //D	602	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
319	char enc[65];	603	{
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	604	// add tunnel domain
356	for (;;)	605	for (;;)
357	{	606	{
358	const char *end = strchr (suffix, '.');	607	const char *end = strchr (domain, '.');
359		608
360	if (!end)	609	if (!end)
361	end = suffix + strlen (suffix);	610	end = domain + strlen (domain);
362		611
363	int len = end - suffix;	612	int len = end - domain;
364		613
365	(*pkt)[offs++] = len;	614	pkt [offs++] = len;
366	memcpy (&((*pkt)[offs]), suffix, len);	615	memcpy (pkt.at (offs), domain, len);
367	offs += len;	616	offs += len;
368		617
369	if (!*end)	618	if (!*end)
370	break;	619	break;
371		620
372	suffix = end + 1;	621	domain = end + 1;
		622	}
		623	}
		624
		625	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		626	{
		627	stdhdr = true;
		628	this->seqno = seqno;
		629
		630	timeout = NOW + INITIAL_TIMEOUT;
		631
		632	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		633	pkt->qdcount = htons (1);
		634
		635	int offs = 6*2;
		636	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
		637	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		638	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		639
		640	char enc[256], *encp = enc;
		641	encode_header (enc, THISNODE->id, seqno);
		642
		643	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		644
		645	if (datalen > stream.size ())
		646	datalen = stream.size ();
		647
		648	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		649	stream.remove (datalen);
		650
		651	while (enclen)
373	}	652	{
		653	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		654
		655	(*pkt)[offs++] = lbllen;
		656	memcpy (pkt->at (offs), encp, lbllen);
		657
		658	offs += lbllen;
		659	encp += lbllen;
		660
		661	enclen -= lbllen;
		662	}
		663
		664	append_domain (*pkt, offs, dns->c->conf->domain);
374		665
375	(*pkt)[offs++] = 0;	666	(*pkt)[offs++] = 0;
376	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	667	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	668	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378		669
379	pkt->len = offs;	670	pkt->len = offs;
		671	}
380		672
381	c->vpn->dns_sndpq.push_back (this);	673	void dns_snd::gen_syn_req ()
		674	{
		675	timeout = NOW + INITIAL_SYN_TIMEOUT;
		676
		677	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		678	pkt->qdcount = htons (1);
		679
		680	int offs = 6 * 2;
		681
		682	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		683
		684	assert (elen <= MAX_LBL_SIZE);
		685
		686	(*pkt)[offs] = elen;
		687	offs += elen + 1;
		688	append_domain (*pkt, offs, dns->c->conf->domain);
		689
		690	(*pkt)[offs++] = 0;
		691	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
		692	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		693
		694	pkt->len = offs;
		695	}
		696
		697	struct dns_rcv
		698	{
		699	int seqno;
		700	dns_packet *pkt; // reply packet
		701	u8 data [MAXSIZE]; // actually part of the reply packet...
		702	int datalen;
		703
		704	dns_rcv (int seqno, u8 *data, int datalen);
		705	~dns_rcv ();
		706	};
		707
		708	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		709	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		710	{
		711	memcpy (this->data, data, datalen);
		712	}
		713
		714	dns_rcv::~dns_rcv ()
		715	{
		716	delete pkt;
382	}	717	}
383		718
384	/////////////////////////////////////////////////////////////////////////////	719	/////////////////////////////////////////////////////////////////////////////
385		720
386	struct dns_cfg	721	dns_connection::dns_connection (connection *c)
		722	: c (c)
		723	, rcvdq (MAX_BACKLOG * 2)
		724	, snddq (MAX_BACKLOG * 2)
		725	, tw (this, &dns_connection::time_cb)
387	{	726	{
388	u8 id1, id2, id3;	727	vpn = c->vpn;
389	u8 def_ttl;
390	u8 unused1;
391	u16 max_size;
392	u8 flags1, flags2;
393	};
394		728
395	dns_packet *	729	established = false;
		730
		731	rcvseq = sndseq = 0;
		732
		733	last_sent = last_received = 0;
		734	poll_interval = MIN_POLL_INTERVAL;
		735	send_interval = 0.5; // starting rate
		736	last_latency = INITIAL_TIMEOUT;
		737	}
		738
		739	dns_connection::~dns_connection ()
		740	{
		741	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		742	i != rcvpq.end ();
		743	++i)
		744	delete *i;
		745	}
		746
		747	void dns_connection::receive_rep (dns_rcv *r)
		748	{
		749	if (r->datalen)
		750	{
		751	last_received = NOW;
		752	tw.trigger ();
		753
		754	poll_interval = send_interval;
		755	}
		756	else
		757	{
		758	poll_interval *= 1.5;
		759	if (poll_interval > MAX_POLL_INTERVAL)
		760	poll_interval = MAX_POLL_INTERVAL;
		761	}
		762
		763	rcvpq.push_back (r);
		764
		765	redo:
		766
		767	// find next packet
		768	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		769	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		770	{
		771	// enter the packet into our input stream
		772	r = *i;
		773
		774	// remove the oldest packet, look forward, as it's oldest first
		775	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		776	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		777	{
		778	delete *j;
		779	rcvpq.erase (j);
		780	break;
		781	}
		782
		783	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		784
		785	if (!rcvdq.put (r->data, r->datalen))
		786	{
		787	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		788	abort (); // MUST never overflow, can be caused by data corruption, TODO
		789	}
		790
		791	while (vpn_packet *pkt = rcvdq.get ())
		792	{
		793	sockinfo si;
		794	si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
		795
		796	vpn->recv_vpn_packet (pkt, si);
		797
		798	delete pkt;
		799	}
		800
		801	// check for further packets
		802	goto redo;
		803	}
		804	}
		805
		806	void
396	vpn::dnsv4_server (dns_packet *pkt)	807	vpn::dnsv4_server (dns_packet &pkt)
397	{	808	{
398	u16 flags = ntohs (pkt->flags);	809	u16 flags = ntohs (pkt.flags);
399		810
400	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401	int offs = 6 * 2; // skip header	811	int offs = 6 * 2; // skip header
402		812
403	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	813	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404		814
405	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	815	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406	&& pkt->qdcount == htons (1))	816	&& pkt.qdcount == htons (1))
407	{	817	{
408	char qname[MAXSIZE];	818	char qname [MAXSIZE];
409	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	819	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410		820
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++];	821	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	822	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416		823
417	pkt->qdcount = htons (1);	824	pkt.qdcount = htons (1);
418	pkt->ancount = 0;	825	pkt.ancount = 0;
419	pkt->nscount = 0; // should be self, as other nameservers reply like this	826	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	827	pkt.arcount = 0; // a record for self, as other nameservers reply like this
421		828
422	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	829	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423		830
424	int dlen = strlen (THISNODE->domain);	831	int dlen = strlen (THISNODE->domain);
425		832
426	if (qclass == RR_CLASS_IN	833	if (qclass == RR_CLASS_IN
427	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428	&& qlen > dlen + 1	834	&& qlen > dlen + 1
429	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	835	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430	{	836	{
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	837	// now generate reply
444	rep->ancount = htons (1); // one answer RR	838	pkt.ancount = htons (1); // one answer RR
445	rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	839	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446		840
447	(*rep) [offs++] = 0xc0;	841	if ((qtype == RR_TYPE_ANY
448	(*rep) [offs++] = 6 * 2; // same as in query section	842	|| qtype == RR_TYPE_TXT
449		843	|| qtype == RR_TYPE_NULL)
450	(*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT;	844	&& 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	{	845	{
470	int sndlen = --dlen;	846	// correct class, domain: parse
		847	int client, seqno;
		848	decode_header (qname, client, seqno);
471		849
472	if (sndlen + txtlen > 255)	850	u8 data[MAXSIZE];
		851	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		852
		853	if (0 < client && client <= conns.size ())
		854	{
		855	connection *c = conns [client - 1];
		856	dns_connection *dns = c->dns;
		857	dns_rcv *rcv;
		858	bool in_seq;
		859
		860	if (dns)
		861	{
		862	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		863	if (SEQNO_EQ ((*i)->seqno, seqno))
		864	{
		865	// already seen that request: simply reply with the cached reply
		866	dns_rcv *r = *i;
		867
		868	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		869
		870	// refresh header & id, as the retry count could have changed
		871	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		872	r->pkt->id = pkt.id;
		873
		874	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		875
		876	goto duplicate_request;
		877	}
		878
		879	in_seq = dns->rcvseq == seqno;
		880
		881	// new packet, queue
		882	rcv = new dns_rcv (seqno, data, datalen);
		883	dns->receive_rep (rcv);
		884	}
		885
		886	{
		887	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		888
		889	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		890	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		891	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		892	pkt [offs++] = 0; pkt [offs++] = 0;
		893	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		894
		895	int rdlen_offs = offs += 2;
		896
		897	int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs;
		898	// bind doesn't compress well, so reduce further by one label length
473	sndlen = 255 - txtlen;	899	dlen -= qlen;
474		900
475	sndlen = 0;	901	if (dns)
		902	{
		903	// only put data into in-order sequence packets, if
		904	// we receive out-of-order packets we generate empty
		905	// replies
		906	while (dlen > 1 && !dns->snddq.empty () && in_seq)
		907	{
		908	int txtlen = dlen <= 255 ? dlen - 1 : 255;
476		909
477	(*rep)[offs++] = sndlen + txtlen;	910	if (txtlen > dns->snddq.size ())
478	memcpy (&((*rep)[offs]), txt, txtlen);	911	txtlen = dns->snddq.size ();
		912
		913	pkt[offs++] = txtlen;
		914	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
479	offs += txtlen;	915	offs += txtlen;
		916	dns->snddq.remove (txtlen);
480		917
481	//if (sndlen + txtlen > dns_snddq.	918	dlen -= txtlen + 1;
		919	}
		920
		921	// avoid empty TXT rdata
		922	if (offs == rdlen_offs)
		923	pkt[offs++] = 0;
		924
		925	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		926	}
		927	else
		928	{
		929	// send RST
		930	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		931	pkt [offs++] = CMD_IP_RST;
		932	}
		933
		934	int rdlen = offs - rdlen_offs;
		935
		936	pkt [rdlen_offs - 2] = rdlen >> 8;
		937	pkt [rdlen_offs - 1] = rdlen;
		938
		939	if (dns)
		940	{
		941	// now update dns_rcv copy
		942	rcv->pkt->len = offs;
		943	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		944	}
		945	}
		946
		947	duplicate_request: ;
		948	}
		949	else
		950	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
482	}	951	}
		952	else if (qtype == RR_TYPE_A
		953	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		954	{
		955	dns_cfg cfg;
		956	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		957	int client = ntohs (cfg.client);
483		958
484	int rdlen = offs - rdlen_offs;	959	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485		960
486	(*rep) [rdlen_offs - 2] = rdlen >> 8;	961	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487	(*rep) [rdlen_offs - 1] = rdlen;	962	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488	#endif	963	pkt [offs++] = 0; pkt [offs++] = 0;
		964	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		965	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		966
		967	slog (L_INFO, _("DNS: client %d connects"), client);
		968
		969	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		970	pkt [offs++] = CMD_IP_REJ;
		971
		972	if (0 < client && client <= conns.size ())
		973	{
		974	connection *c = conns [client - 1];
		975
		976	if (cfg.valid ())
		977	{
		978	pkt [offs - 1] = CMD_IP_SYN;
		979
		980	delete c->dns;
		981	c->dns = new dns_connection (c);
		982	c->dns->cfg = cfg;
		983	}
		984	}
		985	}
489	}	986	}
490	}
491		987
492	pkt->len = offs;	988	pkt.len = offs;
493	return pkt;	989	}
494	}	990	}
495		991
496	void	992	void
497	vpn::dnsv4_client (dns_packet *pkt)	993	vpn::dnsv4_client (dns_packet &pkt)
498	{	994	{
499	u16 flags = ntohs (pkt->flags);	995	u16 flags = ntohs (pkt.flags);
500	int offs = 6 * 2; // skip header	996	int offs = 6 * 2; // skip header
501		997
502	pkt->qdcount = ntohs (pkt->qdcount);	998	pkt.qdcount = ntohs (pkt.qdcount);
503	pkt->ancount = ntohs (pkt->ancount);	999	pkt.ancount = ntohs (pkt.ancount);
504		1000
		1001	// go through our request list and find the corresponding request
505	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1002	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506	i != dns_sndpq.end ();	1003	i != dns_sndpq.end ();
507	++i)	1004	++i)
508	if ((*i)->pkt->id == pkt->id)	1005	if ((*i)->pkt->id == pkt.id)
509	{	1006	{
		1007	dns_connection *dns = (*i)->dns;
510	connection *c = (*i)->conn;	1008	connection *c = dns->c;
511	printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D	1009	int seqno = (*i)->seqno;
		1010	u8 data[MAXSIZE], *datap = data;
		1011
		1012	if ((*i)->retry)
		1013	{
		1014	dns->send_interval *= 1.01;
		1015	if (dns->send_interval > MAX_SEND_INTERVAL)
		1016	dns->send_interval = MAX_SEND_INTERVAL;
		1017	}
		1018	else
		1019	{
		1020	#if 1
		1021	dns->send_interval *= 0.999;
		1022	#endif
		1023	if (dns->send_interval < MIN_SEND_INTERVAL)
		1024	dns->send_interval = MIN_SEND_INTERVAL;
		1025
		1026	// the latency surely puts an upper bound on
		1027	// the minimum send interval
		1028	double latency = NOW - (*i)->sent;
		1029	dns->last_latency = latency;
		1030
		1031	if (dns->send_interval > latency)
		1032	dns->send_interval = latency;
		1033	}
		1034
512	delete *i;	1035	delete *i;
513	dns_sndpq.erase (i);	1036	dns_sndpq.erase (i);
514		1037
515	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1038	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516	{	1039	{
517	char qname[MAXSIZE];	1040	char qname[MAXSIZE];
518		1041
519	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1042	while (pkt.qdcount-- && offs < MAXSIZE - 4)
520	{	1043	{
521	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1044	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522	offs += 4; // skip qtype, qclass	1045	offs += 4; // skip qtype, qclass
523	}	1046	}
524		1047
525	while (pkt->ancount-- && offs < MAXSIZE - 10)	1048	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526	{	1049	{
527	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1050	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528		1051
529	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1052	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1053	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531	u32 ttl = (*pkt) [offs++] << 24;	1054	u32 ttl = pkt [offs++] << 24;
532	ttl |= (*pkt) [offs++] << 16;	1055	ttl |= pkt [offs++] << 16;
533	ttl |= (*pkt) [offs++] << 8;	1056	ttl |= pkt [offs++] << 8;
534	ttl |= (*pkt) [offs++];	1057	ttl |= pkt [offs++];
535
536	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1058	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537		1059
538	printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen);	1060	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
539
540	offs += rdlen;
541
542	if (MAXSIZE - offs < rdlen)
543	{	1061	{
		1062	if (rdlen <= MAXSIZE - offs)
		1063	{
544	// decode bytes, finally	1064	// decode bytes, finally
		1065
		1066	while (rdlen)
		1067	{
		1068	int txtlen = pkt [offs++];
		1069
		1070	assert (txtlen + offs < MAXSIZE - 1);
		1071
		1072	memcpy (datap, pkt.at (offs), txtlen);
		1073	datap += txtlen; offs += txtlen;
		1074
		1075	rdlen -= txtlen + 1;
		1076	}
		1077	}
		1078	}
		1079	else if (qtype == RR_TYPE_A)
		1080	{
		1081	u8 ip [4];
		1082
		1083	ip [0] = pkt [offs++];
		1084	ip [1] = pkt [offs++];
		1085	ip [2] = pkt [offs++];
		1086	ip [3] = pkt [offs++];
		1087
		1088	if (ip [0] == CMD_IP_1
		1089	&& ip [1] == CMD_IP_2
		1090	&& ip [2] == CMD_IP_3)
		1091	{
		1092	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1093
		1094	if (ip [3] == CMD_IP_RST)
		1095	{
		1096	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1097
		1098	delete dns; c->dns = 0;
		1099
		1100	return;
		1101	}
		1102	else if (ip [3] == CMD_IP_SYN)
		1103	{
		1104	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1105	dns->established = true;
		1106	}
		1107	else if (ip [3] == CMD_IP_REJ)
		1108	{
		1109	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1110	abort ();
		1111	}
		1112	else
		1113	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1114	}
		1115	else
		1116	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1117	ip [0], ip [1], ip [2], ip [3]);
		1118
		1119	return;
		1120	}
		1121
		1122	int client, rseqno;
		1123	decode_header (qname, client, rseqno);
		1124
		1125	if (client != THISNODE->id)
		1126	{
		1127	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1128	datap = 0;
		1129	}
		1130	else if (rseqno != seqno)
		1131	{
		1132	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1133	datap = 0;
545	}	1134	}
546	}	1135	}
547	}	1136	}
548		1137
		1138	// todo: pkt now used
		1139	if (datap)
		1140	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1141
549	break;	1142	break;
550	}	1143	}
551	}	1144	}
552		1145
553	void	1146	void
…		…
557	{	1150	{
558	dns_packet *pkt = new dns_packet;	1151	dns_packet *pkt = new dns_packet;
559	struct sockaddr_in sa;	1152	struct sockaddr_in sa;
560	socklen_t sa_len = sizeof (sa);	1153	socklen_t sa_len = sizeof (sa);
561		1154
562	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1155	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563		1156
564	if (pkt->len > 0)	1157	if (pkt->len > 0)
565	if (THISNODE->dns_port)
566	{	1158	{
567	pkt = dnsv4_server (pkt);	1159	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);	1160	dnsv4_client (*pkt);
		1161	else
		1162	{
		1163	dnsv4_server (*pkt);
		1164	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
		1165	}
		1166
		1167	delete pkt;
		1168	}
572	}	1169	}
573	}	1170	}
574		1171
575	bool	1172	bool
576	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1173	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577	{	1174	{
578	// never initialized	1175	int client = ntohs (si.port);
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		1176
584	dns_rcvseq = dns_sndseq = 0;	1177	assert (0 < client && client <= conns.size ());
585		1178
586	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1179	connection *c = conns [client - 1];
587	}	1180
		1181	if (!c->dns)
		1182	c->dns = new dns_connection (c);
588		1183
589	if (!dns_snddq->put (pkt))	1184	if (!c->dns->snddq.put (pkt))
590	return false;	1185	return false;
591		1186
592	// start timer if neccessary	1187	c->dns->tw.trigger ();
593	if (!dnsv4_tw.active)
594	dnsv4_cb (dnsv4_tw);
595		1188
596	return true;	1189	return true;
597	}	1190	}
598		1191
599	void	1192	void
		1193	connection::dnsv4_reset_connection ()
		1194	{
		1195	//delete dns; dns = 0; //TODO
		1196	}
		1197
		1198	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1199
		1200	void
600	connection::dnsv4_cb (time_watcher &w)	1201	dns_connection::time_cb (time_watcher &w)
601	{	1202	{
		1203	// servers have to be polled
		1204	if (THISNODE->dns_port)
		1205	return;
		1206
602	// check for timeouts and (re)transmit	1207	// check for timeouts and (re)transmit
603	tstamp next = NOW + 60;	1208	tstamp next = NOW + poll_interval;
604	dns_req *send = 0;	1209	dns_snd *send = 0;
605		1210
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 ();	1211	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609	i != vpn->dns_sndpq.end ();	1212	i != vpn->dns_sndpq.end ();
610	++i)	1213	++i)
611	{	1214	{
612	dns_req *r = *i;	1215	dns_snd *r = *i;
613		1216
614	if (r->next <= NOW)	1217	if (r->timeout <= NOW)
615	{	1218	{
616	if (!send)	1219	if (!send)
617	{	1220	{
618	send = r;	1221	send = r;
619		1222
620	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621	r->retry++;	1223	r->retry++;
622	r->next = NOW + r->retry;	1224	r->timeout = NOW + (r->retry * last_latency * 8.);
		1225
		1226	// the following code changes the query section a bit, forcing
		1227	// the forwarder to generate a new request
		1228	if (r->stdhdr)
		1229	{
		1230	//printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1231	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1232	}
623	}	1233	}
624	}	1234	}
		1235	else
		1236	NEXT (r->timeout);
		1237	}
625		1238
626	if (r->next < next)	1239	if (last_sent + send_interval <= NOW)
627	next = r->next;
628	}	1240	{
629
630	if (!send	1241	if (!send)
		1242	{
		1243	// generate a new packet, if wise
		1244
		1245	if (!established)
		1246	{
		1247	if (vpn->dns_sndpq.empty ())
		1248	{
		1249	send = new dns_snd (this);
		1250
		1251	cfg.reset (THISNODE->id);
		1252	send->gen_syn_req ();
		1253	}
		1254	}
631	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1255	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
632	send = new dns_req (this, dns_sndseq++, dns_snddq);	1256	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1257	{
		1258	//printf ("sending data request etc.\n"); //D
		1259	if (!snddq.empty ())
		1260	{
		1261	poll_interval = send_interval;
		1262	NEXT (NOW + send_interval);
		1263	}
633		1264
634	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);	1265	send = new dns_snd (this);
		1266	send->gen_stream_req (sndseq, snddq);
		1267	send->timeout = NOW + last_latency * 8.;
635		1268
		1269	sndseq = (sndseq + 1) & SEQNO_MASK;
		1270	}
		1271
		1272	if (send)
		1273	vpn->dns_sndpq.push_back (send);
		1274	}
		1275
636	if (send)	1276	if (send)
		1277	{
		1278	last_sent = NOW;
		1279	sendto (vpn->dnsv4_fd,
		1280	send->pkt->at (0), send->pkt->len, 0,
		1281	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1282	}
637	{	1283	}
638	dns_packet *pkt = send->pkt;	1284	else
		1285	NEXT (last_sent + send_interval);
639		1286
640	next = min_next;	1287	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)",
		1288	poll_interval, send_interval, next - NOW,
		1289	vpn->dns_sndpq.size (), snddq.size ());
641		1290
642	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());	1291	// TODO: no idea when this happens, but when next < NOW, we have a problem
643	}	1292	if (next < NOW + 0.0001)
644	else if (next < min_next)	1293	next = NOW + 0.1;
645	next = min_next;
646		1294
647	w.start (next);	1295	w.start (next);
648	}	1296	}
649		1297
650	#endif	1298	#endif

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