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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.6 by pcg, Thu Mar 3 08:38:32 2005 UTC vs.
Revision 1.29 by pcg, Sun Mar 13 12:40:20 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.
46		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 2. // optimistic?
		58
		59	#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	60	#define MAX_OUTSTANDING 100 // max. outstanding requests
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	61	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
49	#define MAX_RATE 1000 // requests/s
50	#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE	62	#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		63
52	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	64	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
53	// 240 leaves about 4 bytes of server reply data	65	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	66	// every two request bytes less give room for one reply byte
55		67
56	// seqno has 12 bits, but the lower bit is always left as zero
57	// as bind caches ttl=0 records and we have to generate
58	// sequence numbers that always differ case-insensitively
59	#define SEQNO_MASK 0x07ff	68	#define SEQNO_MASK 0x3fff
60		69	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
61	/*
62
63	protocol, in shorthand :)
64
65	client -> server <req> ANY?
66	server -> client <req> TXT <rep>
67
68	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
69	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
70
71	if <client-id> is zero, the connection will be configured:
72
73	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
74
75	*/
76		70
77	#define MAX_LBL_SIZE 63	71	#define MAX_LBL_SIZE 63
78	#define MAX_PKT_SIZE 512	72	#define MAX_PKT_SIZE 512
79		73
		74	#define RR_TYPE_A 1
		75	#define RR_TYPE_NULL 10
80	#define RR_TYPE_TXT 16	76	#define RR_TYPE_TXT 16
81	#define RR_TYPE_ANY 255	77	#define RR_TYPE_ANY 255
		78
82	#define RR_CLASS_IN 1	79	#define RR_CLASS_IN 1
83		80
84	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	81	#define CMD_IP_1 207
85	struct dns64	82	#define CMD_IP_2 46
86	{	83	#define CMD_IP_3 236
87	static const char encode_chars[64 + 1];	84	#define CMD_IP_RST 29
88	static s8 decode_chars[256];	85	#define CMD_IP_SYN 113
		86	#define CMD_IP_REJ 32
89		87
90	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	88	// works for cmaps up to 255 (not 256!)
91	static int decode_len (int bytes) { return (bytes * 6) / 8; }	89	struct charmap
		90	{
		91	enum { INVALID = (u8)255 };
		92
		93	char encode [256]; // index => char
		94	u8 decode [256]; // char => index
		95	unsigned int size;
		96
		97	charmap (const char *cmap);
		98	};
		99
		100	charmap::charmap (const char *cmap)
		101	{
		102	char *enc = encode;
		103	u8 *dec = decode;
		104
		105	memset (enc, (char) 0, 256);
		106	memset (dec, (char)INVALID, 256);
		107
		108	for (size = 0; cmap [size]; size++)
		109	{
		110	enc [size] = cmap [size];
		111	dec [(u8)enc [size]] = size;
		112	}
		113
		114	assert (size < 256);
		115	}
		116
		117	#define MAX_DEC_LEN 500
		118	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		119	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		120
		121	// ugly. minimum base is 16(!)
		122	struct basecoder
		123	{
		124	charmap cmap;
		125	unsigned int enc_len [MAX_DEC_LEN];
		126	unsigned int dec_len [MAX_ENC_LEN];
		127
		128	unsigned int encode_len (unsigned int len);
		129	unsigned int decode_len (unsigned int len);
		130
92	static int encode (char *dst, u8 *src, int len);	131	unsigned int encode (char *dst, u8 *src, unsigned int len);
93	static int decode (u8 *dst, char *src, int len);	132	unsigned int decode (u8 *dst, char *src, unsigned int len);
94		133
95	dns64 ();	134	basecoder (const char *cmap);
96	} dns64;	135	};
97		136
98	// the following sequence has been crafted to	137	basecoder::basecoder (const char *cmap)
99	// a) look somewhat random	138	: cmap (cmap)
100	// b) the even (and odd) indices never share the same character as upper/lowercase
101	const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
102	s8 dns64::decode_chars[256];
103
104	dns64::dns64 ()
105	{	139	{
106	for (int i = 0; i < 64; i++)	140	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
107	decode_chars [encode_chars [i]] = i + 1;	141	{
108	}	142	u8 src [MAX_DEC_LEN];
		143	u8 dst [MAX_ENC_LEN];
109		144
110	int dns64::encode (char *dst, u8 *src, int len)	145	memset (src, 255, len);
		146
		147	mp_limb_t m [MAX_LIMBS];
		148	mp_size_t n;
		149
		150	n = mpn_set_str (m, src, len, 256);
		151	n = mpn_get_str (dst, this->cmap.size, m, n);
		152
		153	for (int i = 0; !dst [i]; ++i)
		154	n--;
		155
		156	enc_len [len] = n;
		157	dec_len [n] = len;
		158	}
		159	}
		160
		161	unsigned int basecoder::encode_len (unsigned int len)
111	{	162	{
112	// slow, but easy to debug	163	return enc_len [len];
113	char *beg = dst;	164	}
114	unsigned int accum, bits = 0;	165
		166	unsigned int basecoder::decode_len (unsigned int len)
		167	{
		168	while (len && !dec_len [len])
		169	--len;
		170
		171	return dec_len [len];
		172	}
		173
		174	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		175	{
		176	if (!len || len > MAX_DEC_LEN)
		177	return 0;
		178
		179	int elen = encode_len (len);
		180
		181	mp_limb_t m [MAX_LIMBS];
		182	mp_size_t n;
		183
		184	u8 dst_ [MAX_ENC_LEN];
		185
		186	n = mpn_set_str (m, src, len, 256);
		187	n = mpn_get_str (dst_, cmap.size, m, n);
		188
		189	int plen = elen; // for padding
		190
		191	while (n < plen)
		192	{
		193	*dst++ = cmap.encode [0];
		194	plen--;
		195	}
		196
		197	for (unsigned int i = n - plen; i < n; ++i)
		198	*dst++ = cmap.encode [dst_ [i]];
		199
		200	return elen;
		201	}
		202
		203	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		204	{
		205	if (!len || len > MAX_ENC_LEN)
		206	return 0;
		207
		208	u8 src_ [MAX_ENC_LEN];
		209	unsigned int elen = 0;
115		210
116	while (len--)	211	while (len--)
117	{	212	{
118	accum <<= 8;	213	u8 val = cmap.decode [(u8)*src++];
119	accum |= *src++;
120	bits += 8;
121		214
122	while (bits >= 6)	215	if (val != charmap::INVALID)
123	{	216	src_ [elen++] = val;
124	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	217	}
125	bits -= 6;	218
126	}	219	int dlen = decode_len (elen);
		220
		221	mp_limb_t m [MAX_LIMBS];
		222	mp_size_t n;
		223
		224	u8 dst_ [MAX_DEC_LEN];
		225
		226	n = mpn_set_str (m, src_, elen, cmap.size);
		227	n = mpn_get_str (dst_, 256, m, n);
		228
		229	if (n < dlen)
127	}	230	{
		231	memset (dst, 0, dlen - n);
		232	memcpy (dst + dlen - n, dst_, n);
		233	}
		234	else
		235	memcpy (dst, dst_ + n - dlen, dlen);
128		236
129	if (bits)	237	return dlen;
130	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
131
132	return dst - beg;
133	}	238	}
134		239
135	int dns64::decode (u8 *dst, char *src, int len)	240	#if 0
136	{	241	struct test { test (); } test;
137	// slow, but easy to debug
138	u8 *beg = dst;
139	unsigned int accum, bits = 0;
140		242
141	while (len--)	243	test::test ()
		244	{
		245	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		246
		247	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		248	static char enc[200];
		249	static u8 dec[200];
		250
		251	for (int i = 1; i < 20; i++)
142	{	252	{
143	s8 chr = decode_chars [(u8)*src++];	253	int elen = cdc.encode (enc, in, i);
		254	int dlen = cdc.decode (dec, enc, elen);
144		255
145	if (!chr)	256	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
146	continue;
147
148	accum <<= 6;
149	accum |= chr - 1;
150	bits += 6;
151
152	while (bits >= 8)
153	{
154	*dst++ = accum >> (bits - 8);
155	bits -= 8;
156	}
157	}	257	}
		258	abort ();
		259	}
		260	#endif
158		261
159	return dst - beg;	262	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		263	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		264	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		265	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		266	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		267
		268	/////////////////////////////////////////////////////////////////////////////
		269
		270	#define HDRSIZE 6
		271
		272	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		273	{
		274	seqno &= SEQNO_MASK;
		275
		276	u8 hdr[3] = {
		277	clientid,
		278	(seqno >> 8) | (retry << 6),
		279	seqno,
		280	};
		281
		282	assert (clientid < 256);
		283
		284	cdc26.encode (data, hdr, 3);
		285	}
		286
		287	inline void decode_header (char *data, int &clientid, int &seqno)
		288	{
		289	u8 hdr[3];
		290
		291	cdc26.decode (hdr, data, HDRSIZE);
		292
		293	clientid = hdr[0];
		294	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
160	}	295	}
161		296
162	/////////////////////////////////////////////////////////////////////////////	297	/////////////////////////////////////////////////////////////////////////////
163		298
164	struct byte_stream	299	struct byte_stream
…		…
193	}	328	}
194		329
195	void byte_stream::remove (int count)	330	void byte_stream::remove (int count)
196	{	331	{
197	if (count > fill)	332	if (count > fill)
198	abort ();	333	assert (count <= fill);
199		334
200	memmove (data, data + count, fill -= count);	335	memmove (data, data + count, fill -= count);
201	}	336	}
202		337
203	bool byte_stream::put (u8 *data, unsigned int datalen)	338	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
216	return false;	351	return false;
217		352
218	data [fill++] = pkt->len >> 8;	353	data [fill++] = pkt->len >> 8;
219	data [fill++] = pkt->len;	354	data [fill++] = pkt->len;
220		355
221	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	356	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
222		357
223	return true;	358	return true;
224	}	359	}
225		360
226	vpn_packet *byte_stream::get ()	361	vpn_packet *byte_stream::get ()
227	{	362	{
		363	unsigned int len;
		364
		365	for (;;)
		366	{
228	int len = (data [0] << 8) | data [1];	367	len = (data [0] << 8) | data [1];
229		368
230	if (len > MAXSIZE && fill >= 2)	369	if (len <= MAXSIZE || fill < 2)
231	abort (); // TODO handle this gracefully, connection reset	370	break;
232		371
		372	// TODO: handle this better than skipping, e.g. by reset
		373	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		374	remove (1);
		375	}
		376
233	if (fill < len + 2)	377	if (fill < len + 2)
234	return 0;	378	return 0;
235		379
236	vpn_packet *pkt = new vpn_packet;	380	vpn_packet *pkt = new vpn_packet;
237		381
238	pkt->len = len;	382	pkt->len = len;
239	memcpy (&((*pkt)[0]), data + 2, len);	383	memcpy (pkt->at (0), data + 2, len);
240	remove (len + 2);	384	remove (len + 2);
241		385
242	return pkt;	386	return pkt;
243	}	387	}
244		388
245	/////////////////////////////////////////////////////////////////////////////	389	/////////////////////////////////////////////////////////////////////////////
246		390
247	#define FLAG_QUERY ( 0 << 15)	391	#define FLAG_QUERY ( 0 << 15)
248	#define FLAG_RESPONSE ( 1 << 15)	392	#define FLAG_RESPONSE ( 1 << 15)
249	#define FLAG_OP_MASK (15 << 14)	393	#define FLAG_OP_MASK (15 << 11)
250	#define FLAG_OP_QUERY ( 0 << 11)	394	#define FLAG_OP_QUERY ( 0 << 11)
251	#define FLAG_AA ( 1 << 10)	395	#define FLAG_AA ( 1 << 10)
252	#define FLAG_TC ( 1 << 9)	396	#define FLAG_TC ( 1 << 9)
253	#define FLAG_RD ( 1 << 8)	397	#define FLAG_RD ( 1 << 8)
254	#define FLAG_RA ( 1 << 7)	398	#define FLAG_RA ( 1 << 7)
…		…
261	#define FLAG_RCODE_REFUSED ( 5 << 0)	405	#define FLAG_RCODE_REFUSED ( 5 << 0)
262		406
263	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	407	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
264	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)	408	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
265		409
		410	struct dns_cfg
		411	{
		412	static int next_uid;
		413
		414	u8 id1, id2, id3, id4;
		415
		416	u8 version;
		417	u8 flags;
		418	u8 rrtype;
		419	u8 def_ttl;
		420
		421	u16 client;
		422	u16 uid; // to make request unique
		423
		424	u16 max_size;
		425	u8 seq_cdc;
		426	u8 req_cdc;
		427
		428	u8 rep_cdc;
		429	u8 r2, r3, r4;
		430
		431	u8 r5, r6, r7, r8;
		432
		433	void reset (int clientid);
		434	bool valid ();
		435	};
		436
		437	int dns_cfg::next_uid;
		438
		439	void dns_cfg::reset (int clientid)
		440	{
		441	id1 = 'G';
		442	id2 = 'V';
		443	id3 = 'P';
		444	id4 = 'E';
		445
		446	version = 1;
		447
		448	rrtype = RR_TYPE_TXT;
		449	flags = 0;
		450	def_ttl = 0;
		451	seq_cdc = 26;
		452	req_cdc = 62;
		453	rep_cdc = 0;
		454	max_size = htons (MAX_PKT_SIZE);
		455	client = htons (clientid);
		456	uid = next_uid++;
		457
		458	r2 = r3 = r4 = 0;
		459	r4 = r5 = r6 = r7 = 0;
		460	}
		461
		462	bool dns_cfg::valid ()
		463	{
		464	return id1 == 'G'
		465	&& id2 == 'V'
		466	&& id3 == 'P'
		467	&& id4 == 'E'
		468	&& seq_cdc == 26
		469	&& req_cdc == 62
		470	&& rep_cdc == 0
		471	&& version == 1;
		472	}
		473
266	struct dns_packet : net_packet	474	struct dns_packet : net_packet
267	{	475	{
268	u16 id;	476	u16 id;
269	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
270	u16 qdcount, ancount, nscount, arcount;	478	u16 qdcount, ancount, nscount, arcount;
271		479
272	u8 data[MAXSIZE - 6 * 2];	480	u8 data [MAXSIZE - 6 * 2];
273		481
274	int decode_label (char *data, int size, int &offs);	482	int decode_label (char *data, int size, int &offs);
275	};	483	};
276		484
277	int dns_packet::decode_label (char *data, int size, int &offs)	485	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
308	return data - orig;	516	return data - orig;
309	}	517	}
310		518
311	/////////////////////////////////////////////////////////////////////////////	519	/////////////////////////////////////////////////////////////////////////////
312		520
313	struct dns_req
314	{
315	dns_packet *pkt;
316	tstamp next;
317	int retry;
318	connection *conn;
319	int seqno;
320
321	dns_req (connection *c);
322	void gen_stream_req (int seqno, byte_stream *stream);
323	};
324
325	static u16 dns_id = 12098; // TODO: should be per-vpn	521	static u16 dns_id = 0; // TODO: should be per-vpn
326		522
327	static u16 next_id ()	523	static u16 next_id ()
328	{	524	{
		525	if (!dns_id)
		526	dns_id = time (0);
		527
329	// the simplest lsfr with periodicity 65535 i could find	528	// the simplest lsfr with periodicity 65535 i could find
330	dns_id = (dns_id << 1)	529	dns_id = (dns_id << 1)
331	| (((dns_id >> 1)	530	| (((dns_id >> 1)
332	^ (dns_id >> 2)	531	^ (dns_id >> 2)
333	^ (dns_id >> 4)	532	^ (dns_id >> 4)
334	^ (dns_id >> 15)) & 1);	533	^ (dns_id >> 15)) & 1);
335		534
336	return dns_id;	535	return dns_id;
337	}	536	}
338		537
339	dns_req::dns_req (connection *c)	538	struct dns_rcv;
340	: conn (c)	539	struct dns_snd;
		540
		541	struct dns_connection
341	{	542	{
342	next = 0;	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 min_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
		568	{
		569	dns_packet *pkt;
		570	tstamp timeout, sent;
		571	int retry;
		572	struct dns_connection *dns;
		573	int seqno;
		574	bool stdhdr;
		575
		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 ();
		581	};
		582
		583	dns_snd::dns_snd (dns_connection *dns)
		584	: dns (dns)
		585	{
		586	timeout = 0;
343	retry = 0;	587	retry = 0;
		588	seqno = 0;
		589	sent = NOW;
		590	stdhdr = false;
344		591
345	pkt = new dns_packet;	592	pkt = new dns_packet;
346		593
347	pkt->id = next_id ();	594	pkt->id = next_id ();
348	}	595	}
349		596
		597	dns_snd::~dns_snd ()
		598	{
		599	delete pkt;
		600	}
		601
		602	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		603	{
		604	// add tunnel domain
		605	for (;;)
		606	{
		607	const char *end = strchr (domain, '.');
		608
		609	if (!end)
		610	end = domain + strlen (domain);
		611
		612	int len = end - domain;
		613
		614	pkt [offs++] = len;
		615	memcpy (pkt.at (offs), domain, len);
		616	offs += len;
		617
		618	if (!*end)
		619	break;
		620
		621	domain = end + 1;
		622	}
		623	}
		624
350	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	625	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
351	{	626	{
		627	stdhdr = true;
352	this->seqno = seqno;	628	this->seqno = seqno;
		629
		630	timeout = NOW + INITIAL_TIMEOUT;
353		631
354	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	632	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
355	pkt->qdcount = htons (1);	633	pkt->qdcount = htons (1);
356		634
357	int offs = 6*2;	635	int offs = 6*2;
358	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	636	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
359	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,	637	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
360	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra	638	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
361		639
362	u8 data[256]; //TODO
363
364	data[0] = THISNODE->id; //TODO
365	data[1] = seqno >> 7; //TODO
366	data[2] = seqno << 1; //TODO
367
368	int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
369
370	if (datalen > stream->size ())
371	datalen = stream->size ();
372
373	char enc[256], *encp = enc;	640	char enc[256], *encp = enc;
374		641	encode_header (enc, THISNODE->id, seqno);
375	memcpy (data + 3, stream->begin (), datalen);	642
376	int enclen = dns64::encode (enc, data, datalen + 3);	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;
377	stream->remove (datalen);	649	stream.remove (datalen);
378		650
379	while (enclen)	651	while (enclen)
380	{	652	{
381	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	653	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
382		654
…		…
387	encp += lbllen;	659	encp += lbllen;
388		660
389	enclen -= lbllen;	661	enclen -= lbllen;
390	}	662	}
391		663
392	const char *suffix = THISNODE->domain;	664	append_domain (*pkt, offs, dns->c->conf->domain);
393
394	// add tunnel domain
395	for (;;)
396	{
397	const char *end = strchr (suffix, '.');
398
399	if (!end)
400	end = suffix + strlen (suffix);
401
402	int len = end - suffix;
403
404	(*pkt)[offs++] = len;
405	memcpy (&((*pkt)[offs]), suffix, len);
406	offs += len;
407
408	if (!*end)
409	break;
410
411	suffix = end + 1;
412	}
413		665
414	(*pkt)[offs++] = 0;	666	(*pkt)[offs++] = 0;
415	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	667	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		668	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		669
		670	pkt->len = offs;
		671	}
		672
		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;
416	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	692	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
417		693
418	pkt->len = offs;	694	pkt->len = offs;
419	}	695	}
420		696
…		…
439	{	715	{
440	delete pkt;	716	delete pkt;
441	}	717	}
442		718
443	/////////////////////////////////////////////////////////////////////////////	719	/////////////////////////////////////////////////////////////////////////////
444		720
445	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)
446	{	726	{
447	u8 id1, id2, id3;	727	vpn = c->vpn;
448	u8 def_ttl;
449	u8 unused1;
450	u16 max_size;
451	u8 flags1, flags2;
452	};
453		728
		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	min_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
454	void connection::dnsv4_receive_rep (struct dns_rcv *r)	747	void dns_connection::receive_rep (dns_rcv *r)
455	{	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
		760	if (poll_interval > MAX_POLL_INTERVAL)
		761	poll_interval = MAX_POLL_INTERVAL;
		762	}
		763
456	dns_rcvpq.push_back (r);	764	rcvpq.push_back (r);
457		765
458	redo:	766	redo:
459		767
		768	// find next packet
460	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	769	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461	i != dns_rcvpq.end ();
462	++i)
463	if (dns_rcvseq == (*i)->seqno)	770	if (SEQNO_EQ (rcvseq, (*i)->seqno))
464	{	771	{
		772	// enter the packet into our input stream
465	dns_rcv *r = *i;	773	r = *i;
466		774
		775	// remove the oldest packet, look forward, as it's oldest first
		776	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		777	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		778	{
		779	delete *j;
		780	rcvpq.erase (j);
		781	break;
		782	}
		783
467	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	784	rcvseq = (rcvseq + 1) & SEQNO_MASK;
468		785
469	if (!dns_snddq && !dns_rcvdq)	786	if (!rcvdq.put (r->data, r->datalen))
470	{	787	{
471	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	788	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472	dns_snddq = new byte_stream (MAX_BACKLOG);	789	abort (); // MUST never overflow, can be caused by data corruption, TODO
473
474	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
475	}	790	}
476		791
477	if (!dns_rcvdq->put (r->data, r->datalen))
478	abort (); // MUST never overflow, can be caused by data corruption, TODO
479
480	while (vpn_packet *pkt = dns_rcvdq->get ())	792	while (vpn_packet *pkt = rcvdq.get ())
481	{	793	{
482	sockinfo si;	794	sockinfo si;
483	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	795	si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
484		796
485	vpn->recv_vpn_packet (pkt, si);	797	vpn->recv_vpn_packet (pkt, si);
		798
		799	delete pkt;
486	}	800	}
487	}	801
488	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	802	// check for further packets
489	{
490	//D
491	//abort();
492	printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
493	dns_rcvpq.erase (i);
494	goto redo;	803	goto redo;
495	}	804	}
496	}	805	}
497		806
498	dns_packet *	807	void
499	vpn::dnsv4_server (dns_packet *pkt)	808	vpn::dnsv4_server (dns_packet &pkt)
500	{	809	{
501	u16 flags = ntohs (pkt->flags);	810	u16 flags = ntohs (pkt.flags);
502		811
503	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504	int offs = 6 * 2; // skip header	812	int offs = 6 * 2; // skip header
505		813
506	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	814	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507		815
508	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	816	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509	&& pkt->qdcount == htons (1))	817	&& pkt.qdcount == htons (1))
510	{	818	{
511	char qname[MAXSIZE];	819	char qname [MAXSIZE];
512	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	820	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513		821
514	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	822	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	823	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516		824
517	pkt->qdcount = htons (1);	825	pkt.qdcount = htons (1);
518	pkt->ancount = 0;	826	pkt.ancount = 0;
519	pkt->nscount = 0; // should be self, as other nameservers reply like this	827	pkt.nscount = 0; // should be self, as other nameservers reply like this
520	pkt->arcount = 0; // a record for self, as other nameservers reply like this	828	pkt.arcount = 0; // a record for self, as other nameservers reply like this
521		829
522	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	830	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523		831
524	int dlen = strlen (THISNODE->domain);	832	int dlen = strlen (THISNODE->domain);
525		833
526	if (qclass == RR_CLASS_IN	834	if (qclass == RR_CLASS_IN
527	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528	&& qlen > dlen + 1	835	&& qlen > dlen + 1
529	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	836	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
530	{	837	{
531	// correct class, domain: parse	838	// now generate reply
532	u8 data[MAXSIZE];	839	pkt.ancount = htons (1); // one answer RR
533	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	840	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534		841
535	int client = data[0];	842	if ((qtype == RR_TYPE_ANY
536	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	843	|| qtype == RR_TYPE_TXT
537		844	|| qtype == RR_TYPE_NULL)
538	if (0 < client && client <= conns.size ())	845	&& qlen > dlen + 1 + HDRSIZE)
539	{	846	{
		847	// correct class, domain: parse
		848	int client, seqno;
		849	decode_header (qname, client, seqno);
		850
		851	u8 data[MAXSIZE];
		852	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		853
		854	if (0 < client && client <= conns.size ())
		855	{
540	connection *c = conns [client - 1];	856	connection *c = conns [client - 1];
		857	dns_connection *dns = c->dns;
		858	dns_rcv *rcv;
		859	bool in_seq;
541		860
542	redo:	861	if (dns)
543
544	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545	i != c->dns_rcvpq.end ();
546	++i)	862	{
		863	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547	if ((*i)->seqno == seqno)	864	if (SEQNO_EQ ((*i)->seqno, seqno))
		865	{
		866	// already seen that request: simply reply with the cached reply
		867	dns_rcv *r = *i;
		868
		869	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		870
		871	// refresh header & id, as the retry count could have changed
		872	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		873	r->pkt->id = pkt.id;
		874
		875	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		876
		877	goto duplicate_request;
		878	}
		879
		880	in_seq = dns->rcvseq == seqno;
		881
		882	// new packet, queue
		883	rcv = new dns_rcv (seqno, data, datalen);
		884	dns->receive_rep (rcv);
		885	}
		886
548	{	887	{
549	// already seen that request: simply reply with the cached reply	888	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550	dns_rcv *r = *i;
551		889
552	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	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
553		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	while (dlen > 1 && !dns->snddq.empty () && in_seq)
		909	{
		910	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		911
		912	if (txtlen > dns->snddq.size ())
		913	txtlen = dns->snddq.size ();
		914
		915	pkt[offs++] = txtlen;
		916	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		917	offs += txtlen;
		918	dns->snddq.remove (txtlen);
		919
		920	dlen -= txtlen + 1;
		921	}
		922
		923	// avoid empty TXT rdata
		924	if (offs == rdlen_offs)
		925	pkt[offs++] = 0;
		926
		927	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		928	}
		929	else
		930	{
		931	// send RST
		932	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		933	pkt [offs++] = CMD_IP_RST;
		934	}
		935
		936	int rdlen = offs - rdlen_offs;
		937
		938	pkt [rdlen_offs - 2] = rdlen >> 8;
		939	pkt [rdlen_offs - 1] = rdlen;
		940
		941	if (dns)
		942	{
		943	// now update dns_rcv copy
554	offs = r->pkt->len;	944	rcv->pkt->len = offs;
555	memcpy (pkt->at (0), r->pkt->at (0), offs);	945	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556	goto duplicate_request;	946	}
557	}	947	}
558		948
559	// new packet, queue	949	duplicate_request: ;
560	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	950	}
561	c->dnsv4_receive_rep (rcv);	951	else
562
563	// now generate reply
564	pkt->ancount = htons (1); // one answer RR
565	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	952	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		953	}
		954	else if (qtype == RR_TYPE_A
		955	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		956	{
		957	dns_cfg cfg;
		958	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		959	int client = ntohs (cfg.client);
566		960
567	(*pkt) [offs++] = 0xc0;
568	(*pkt) [offs++] = 6 * 2; // same as in query section	961	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569		962
570	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	963	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	964	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	965	pkt [offs++] = 0; pkt [offs++] = 0;
574	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	966	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		967	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
575		968
576	int dlen = MAX_PKT_SIZE - offs - 2;	969	slog (L_INFO, _("DNS: client %d connects"), client);
577		970
578	// bind doesn't compress well, so reduce further by one label length	971	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
579	dlen -= qlen;	972	pkt [offs++] = CMD_IP_REJ;
580		973
581	int rdlen_offs = offs += 2;	974	if (0 < client && client <= conns.size ())
582
583	while (c->dns_snddq
584	&& !c->dns_snddq->empty ()
585	&& dlen > 1)
586	{	975	{
587	int txtlen = dlen <= 255 ? dlen - 1 : 255;	976	connection *c = conns [client - 1];
588		977
589	if (txtlen > c->dns_snddq->size ())	978	if (cfg.valid ())
590	txtlen = c->dns_snddq->size ();	979	{
		980	pkt [offs - 1] = CMD_IP_SYN;
591		981
592	(*pkt)[offs++] = txtlen;	982	delete c->dns;
593	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	983	c->dns = new dns_connection (c);
594	offs += txtlen;	984	c->dns->cfg = cfg;
595	c->dns_snddq->remove (txtlen);	985	}
596
597	dlen -= txtlen + 1;
598	}	986	}
599
600	// avoid empty TXT rdata
601	if (offs == rdlen_offs)
602	(*pkt)[offs++] = 0;
603
604	int rdlen = offs - rdlen_offs;
605
606	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
607	(*pkt) [rdlen_offs - 1] = rdlen;
608
609	// now update dns_rcv copy
610	rcv->pkt->len = offs;
611	memcpy (rcv->pkt->at (0), pkt->at (0), offs);
612
613	duplicate_request: ;
614	}	987	}
615	else
616	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617	}	988	}
618		989
619	pkt->len = offs;	990	pkt.len = offs;
620	}	991	}
621
622	return pkt;
623	}	992	}
624		993
625	void	994	void
626	vpn::dnsv4_client (dns_packet *pkt)	995	vpn::dnsv4_client (dns_packet &pkt)
627	{	996	{
628	u16 flags = ntohs (pkt->flags);	997	u16 flags = ntohs (pkt.flags);
629	int offs = 6 * 2; // skip header	998	int offs = 6 * 2; // skip header
630		999
631	pkt->qdcount = ntohs (pkt->qdcount);	1000	pkt.qdcount = ntohs (pkt.qdcount);
632	pkt->ancount = ntohs (pkt->ancount);	1001	pkt.ancount = ntohs (pkt.ancount);
633		1002
634	// go through our request list and find the corresponding request	1003	// go through our request list and find the corresponding request
635	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1004	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636	i != dns_sndpq.end ();	1005	i != dns_sndpq.end ();
637	++i)	1006	++i)
638	if ((*i)->pkt->id == pkt->id)	1007	if ((*i)->pkt->id == pkt.id)
639	{	1008	{
		1009	dns_connection *dns = (*i)->dns;
640	connection *c = (*i)->conn;	1010	connection *c = dns->c;
641	int seqno = (*i)->seqno;	1011	int seqno = (*i)->seqno;
642	u8 data[MAXSIZE], *datap = data;	1012	u8 data[MAXSIZE], *datap = data;
643		1013
		1014	if ((*i)->retry)
		1015	{
		1016	dns->send_interval *= 1.01;
		1017	if (dns->send_interval > MAX_SEND_INTERVAL)
		1018	dns->send_interval = MAX_SEND_INTERVAL;
		1019	}
		1020	else
		1021	{
		1022	#if 0
		1023	dns->send_interval *= 0.999;
		1024	#endif
		1025	// the latency surely puts an upper bound on
		1026	// the minimum send interval
		1027	double latency = NOW - (*i)->sent;
		1028
		1029	if (latency < dns->min_latency)
		1030	dns->min_latency = latency;
		1031
		1032	if (dns->send_interval > dns->min_latency * LATENCY_FACTOR)
		1033	dns->send_interval = dns->min_latency * LATENCY_FACTOR;
		1034
		1035	if (dns->send_interval < MIN_SEND_INTERVAL)
		1036	dns->send_interval = MIN_SEND_INTERVAL;
		1037	}
		1038
644	delete *i;	1039	delete *i;
645	dns_sndpq.erase (i);	1040	dns_sndpq.erase (i);
646		1041
647	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1042	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648	{	1043	{
649	char qname[MAXSIZE];	1044	char qname[MAXSIZE];
650		1045
651	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1046	while (pkt.qdcount-- && offs < MAXSIZE - 4)
652	{	1047	{
653	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1048	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654	offs += 4; // skip qtype, qclass	1049	offs += 4; // skip qtype, qclass
655	}	1050	}
656		1051
657	while (pkt->ancount-- && offs < MAXSIZE - 10)	1052	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658	{	1053	{
659	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1054	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660		1055
661	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1056	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1057	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663	u32 ttl = (*pkt) [offs++] << 24;	1058	u32 ttl = pkt [offs++] << 24;
664	ttl |= (*pkt) [offs++] << 16;	1059	ttl |= pkt [offs++] << 16;
665	ttl |= (*pkt) [offs++] << 8;	1060	ttl |= pkt [offs++] << 8;
666	ttl |= (*pkt) [offs++];	1061	ttl |= pkt [offs++];
667
668	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1062	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669		1063
670	if (rdlen <= MAXSIZE - offs)	1064	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671	{	1065	{
672	// decode bytes, finally	1066	if (rdlen <= MAXSIZE - offs)
673
674	while (rdlen)
675	{	1067	{
		1068	// decode bytes, finally
		1069
		1070	while (rdlen)
		1071	{
676	int txtlen = (*pkt) [offs++];	1072	int txtlen = pkt [offs++];
677		1073
678	assert (txtlen + offs < MAXSIZE - 1);	1074	assert (txtlen + offs < MAXSIZE - 1);
679		1075
680	memcpy (datap, pkt->at (offs), txtlen);	1076	memcpy (datap, pkt.at (offs), txtlen);
681	datap += txtlen; offs += txtlen;	1077	datap += txtlen; offs += txtlen;
682		1078
683	rdlen -= txtlen + 1;	1079	rdlen -= txtlen + 1;
		1080	}
684	}	1081	}
685
686	}	1082	}
		1083	else if (qtype == RR_TYPE_A)
		1084	{
		1085	u8 ip [4];
687		1086
		1087	ip [0] = pkt [offs++];
		1088	ip [1] = pkt [offs++];
		1089	ip [2] = pkt [offs++];
		1090	ip [3] = pkt [offs++];
		1091
		1092	if (ip [0] == CMD_IP_1
		1093	&& ip [1] == CMD_IP_2
		1094	&& ip [2] == CMD_IP_3)
		1095	{
		1096	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1097
		1098	if (ip [3] == CMD_IP_RST)
		1099	{
		1100	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1101
		1102	delete dns; c->dns = 0;
		1103
		1104	return;
		1105	}
		1106	else if (ip [3] == CMD_IP_SYN)
		1107	{
		1108	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1109	dns->established = true;
		1110	}
		1111	else if (ip [3] == CMD_IP_REJ)
		1112	{
		1113	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1114	abort ();
		1115	}
		1116	else
		1117	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1118	}
		1119	else
		1120	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1121	ip [0], ip [1], ip [2], ip [3]);
		1122
		1123	return;
		1124	}
		1125
		1126	int client, rseqno;
		1127	decode_header (qname, client, rseqno);
		1128
		1129	if (client != THISNODE->id)
		1130	{
		1131	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1132	datap = 0;
		1133	}
		1134	else if (rseqno != seqno)
		1135	{
		1136	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1137	datap = 0;
		1138	}
688	}	1139	}
689	}	1140	}
690		1141
691	// todo: pkt now used	1142	// todo: pkt now used
		1143	if (datap)
692	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1144	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693		1145
694	break;	1146	break;
695	}	1147	}
696
697	delete pkt;
698	}	1148	}
699		1149
700	void	1150	void
701	vpn::dnsv4_ev (io_watcher &w, short revents)	1151	vpn::dnsv4_ev (io_watcher &w, short revents)
702	{	1152	{
…		…
704	{	1154	{
705	dns_packet *pkt = new dns_packet;	1155	dns_packet *pkt = new dns_packet;
706	struct sockaddr_in sa;	1156	struct sockaddr_in sa;
707	socklen_t sa_len = sizeof (sa);	1157	socklen_t sa_len = sizeof (sa);
708		1158
709	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1159	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
710		1160
711	if (pkt->len > 0)	1161	if (pkt->len > 0)
712	{	1162	{
713	if (pkt->flags & htons (FLAG_TC))	1163	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1164	dnsv4_client (*pkt);
		1165	else
714	{	1166	{
715	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1167	dnsv4_server (*pkt);
716	//TODO connection reset	1168	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}	1169	}
718		1170
719	if (THISNODE->dns_port)	1171	delete pkt;
720	{
721	pkt = dnsv4_server (pkt);
722	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
723	}
724	else
725	dnsv4_client (pkt);
726	}	1172	}
727	}	1173	}
728	}	1174	}
729		1175
730	bool	1176	bool
731	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1177	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
732	{	1178	{
733	// never initialized	1179	int client = ntohs (si.port);
734	if (!dns_snddq && !dns_rcvdq)
735	{
736	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
737	dns_snddq = new byte_stream (MAX_BACKLOG);
738		1180
739	//dns_rcvseq = dns_sndseq = 0;	1181	assert (0 < client && client <= conns.size ());
740		1182
741	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1183	connection *c = conns [client - 1];
742	}	1184
		1185	if (!c->dns)
		1186	c->dns = new dns_connection (c);
743		1187
744	if (!dns_snddq->put (pkt))	1188	if (!c->dns->snddq.put (pkt))
745	return false;	1189	return false;
746		1190
747	// start timer if neccessary	1191	c->dns->tw.trigger ();
748	if (!THISNODE->dns_port && !dnsv4_tw.active)
749	dnsv4_cb (dnsv4_tw);
750		1192
751	return true;	1193	return true;
752	}	1194	}
753		1195
754	void	1196	void
		1197	connection::dnsv4_reset_connection ()
		1198	{
		1199	//delete dns; dns = 0; //TODO
		1200	}
		1201
		1202	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1203
		1204	void
755	connection::dnsv4_cb (time_watcher &w)	1205	dns_connection::time_cb (time_watcher &w)
756	{	1206	{
		1207	// servers have to be polled
		1208	if (THISNODE->dns_port)
		1209	return;
		1210
757	// check for timeouts and (re)transmit	1211	// check for timeouts and (re)transmit
758	tstamp next = NOW + 60;	1212	tstamp next = NOW + poll_interval;
759	dns_req *send = 0;	1213	dns_snd *send = 0;
760		1214
761	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1215	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762	i != vpn->dns_sndpq.end ();	1216	i != vpn->dns_sndpq.end ();
763	++i)	1217	++i)
764	{	1218	{
765	dns_req *r = *i;	1219	dns_snd *r = *i;
766		1220
767	if (r->next <= NOW)	1221	if (r->timeout <= NOW)
768	{	1222	{
769	if (!send)	1223	if (!send)
770	{	1224	{
771	send = r;	1225	send = r;
772		1226
773	if (r->retry)//D
774	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775	r->retry++;	1227	r->retry++;
776	r->next = NOW + r->retry;	1228	r->timeout = NOW + (r->retry * min_latency * 8.);
		1229
		1230	// the following code changes the query section a bit, forcing
		1231	// the forwarder to generate a new request
		1232	if (r->stdhdr)
		1233	{
		1234	//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1235	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1236	}
777	}	1237	}
778	}	1238	}
779		1239	else
780	if (r->next < next)	1240	NEXT (r->timeout);
781	next = r->next;
782	}	1241	}
783		1242
784	if (!send	1243	if (!send)
		1244	{
		1245	// generate a new packet, if wise
		1246
		1247	if (!established)
		1248	{
		1249	if (vpn->dns_sndpq.empty ())
		1250	{
		1251	send = new dns_snd (this);
		1252
		1253	cfg.reset (THISNODE->id);
		1254	send->gen_syn_req ();
		1255	}
		1256	}
785	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1257	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
786	{	1258	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1259	{
		1260	if (last_sent + send_interval <= NOW)
		1261	{
		1262	//printf ("sending data request etc.\n"); //D
		1263	if (!snddq.empty () || last_received + 1. > NOW)
		1264	{
		1265	poll_interval = send_interval;
		1266	NEXT (NOW + send_interval);
		1267	}
		1268
787	send = new dns_req (this);	1269	send = new dns_snd (this);
788	send->gen_stream_req (dns_sndseq, dns_snddq);	1270	send->gen_stream_req (sndseq, snddq);
		1271	send->timeout = NOW + min_latency * 8.;
		1272
		1273	sndseq = (sndseq + 1) & SEQNO_MASK;
		1274	}
		1275	else
		1276	NEXT (last_sent + send_interval);
		1277	}
		1278
		1279	if (send)
789	vpn->dns_sndpq.push_back (send);	1280	vpn->dns_sndpq.push_back (send);
790
791	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792	}	1281	}
793
794	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795		1282
796	if (send)	1283	if (send)
797	{	1284	{
798	dns_packet *pkt = send->pkt;	1285	last_sent = NOW;
799		1286	sendto (vpn->dnsv4_fd,
800	next = min_next;	1287	send->pkt->at (0), send->pkt->len, 0,
801		1288	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
802	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
803	}	1289	}
804	else if (next < min_next)	1290
805	next = min_next;	1291	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1292	poll_interval, send_interval, next - NOW,
		1293	vpn->dns_sndpq.size (), snddq.size (),
		1294	rcvpq.size ());
		1295
		1296	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1297	if (next < NOW + 0.001)
		1298	next = NOW + 0.1;
806		1299
807	w.start (next);	1300	w.start (next);
808	}	1301	}
809		1302
810	#endif	1303	#endif

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