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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 1.30 by pcg, Mon Mar 14 17:40:01 2005 UTC

1	/*	1	/*
2	vpn_dns.C -- handle the dns tunnel part of the protocol.	2	vpn_dns.C -- handle the dns tunnel part of the protocol.
3	Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com>	3	Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de>
4		4
		5	This file is part of GVPE.
		6
5	This program is free software; you can redistribute it and/or modify	7	GVPE is free software; you can redistribute it and/or modify
6	it under the terms of the GNU General Public License as published by	8	it under the terms of the GNU General Public License as published by
7	the Free Software Foundation; either version 2 of the License, or	9	the Free Software Foundation; either version 2 of the License, or
8	(at your option) any later version.	10	(at your option) any later version.
9		11
10	This program is distributed in the hope that it will be useful,	12	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.	15	GNU General Public License for more details.
14		16
15	You should have received a copy of the GNU General Public License	17	You should have received a copy of the GNU General Public License
16	along with this program; if not, write to the Free Software	18	along with gvpe; if not, write to the Free Software
17	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA	19	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18	*/	20	*/
19		21
20	#include "config.h"	22	#include "config.h"
21		23
…		…
23		25
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	27	// it's a hack, use only in emergency situations please.
26		28
27	#include <cstring>	29	#include <cstring>
		30	#include <cassert>
28		31
29	#include <sys/types.h>	32	#include <sys/types.h>
30	#include <sys/socket.h>	33	#include <sys/socket.h>
31	#include <sys/wait.h>	34	#include <sys/wait.h>
32	#include <sys/uio.h>	35	#include <sys/uio.h>
…		…
35	#include <unistd.h>	38	#include <unistd.h>
36	#include <fcntl.h>	39	#include <fcntl.h>
37		40
38	#include <map>	41	#include <map>
39		42
		43	#include <gmp.h>
		44
40	#include "netcompat.h"	45	#include "netcompat.h"
41		46
42	#include "vpn.h"	47	#include "vpn.h"
43		48
44	#define MIN_RETRY 1.	49	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	50	#define ACTIVITY_INTERVAL 5.
46		51
		52	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		53	#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
		54
		55	#define MIN_SEND_INTERVAL 0.001 // wait at least this time between sending requests
		56	#define MAX_SEND_INTERVAL 2. // optimistic?
		57
		58	#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	59	#define MAX_OUTSTANDING 2 // 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 1000 // requests/s
50	#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE	61	#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		62
52	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	63	#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	64	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	65	// every two request bytes less give room for one reply byte
55		66
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	67	#define SEQNO_MASK 0x3fff
60		68	#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		69
77	#define MAX_LBL_SIZE 63	70	#define MAX_LBL_SIZE 63
78	#define MAX_PKT_SIZE 512	71	#define MAX_PKT_SIZE 512
79		72
		73	#define RR_TYPE_A 1
		74	#define RR_TYPE_NULL 10
80	#define RR_TYPE_TXT 16	75	#define RR_TYPE_TXT 16
81	#define RR_TYPE_ANY 255	76	#define RR_TYPE_ANY 255
		77
82	#define RR_CLASS_IN 1	78	#define RR_CLASS_IN 1
83		79
84	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	80	#define CMD_IP_1 207
85	struct dns64	81	#define CMD_IP_2 46
86	{	82	#define CMD_IP_3 236
87	static const char encode_chars[64 + 1];	83	#define CMD_IP_RST 29
88	static s8 decode_chars[256];	84	#define CMD_IP_SYN 113
		85	#define CMD_IP_REJ 32
89		86
90	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	87	// works for cmaps up to 255 (not 256!)
91	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
92	static int encode (char *dst, u8 *src, int len);	130	unsigned int encode (char *dst, u8 *src, unsigned int len);
93	static int decode (u8 *dst, char *src, int len);	131	unsigned int decode (u8 *dst, char *src, unsigned int len);
94		132
95	dns64 ();	133	basecoder (const char *cmap);
96	} dns64;	134	};
97		135
98	// the following sequence has been crafted to	136	basecoder::basecoder (const char *cmap)
99	// a) look somewhat random	137	: 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	{	138	{
106	for (int i = 0; i < 64; i++)	139	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
107	decode_chars [encode_chars [i]] = i + 1;	140	{
108	}	141	u8 src [MAX_DEC_LEN];
		142	u8 dst [MAX_ENC_LEN];
109		143
110	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)
111	{	161	{
112	// slow, but easy to debug	162	return enc_len [len];
113	char *beg = dst;	163	}
114	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;
115		209
116	while (len--)	210	while (len--)
117	{	211	{
118	accum <<= 8;	212	u8 val = cmap.decode [(u8)*src++];
119	accum |= *src++;
120	bits += 8;
121		213
122	while (bits >= 6)	214	if (val != charmap::INVALID)
123	{	215	src_ [elen++] = val;
124	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	216	}
125	bits -= 6;	217
126	}	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)
127	}	229	{
		230	memset (dst, 0, dlen - n);
		231	memcpy (dst + dlen - n, dst_, n);
		232	}
		233	else
		234	memcpy (dst, dst_ + n - dlen, dlen);
128		235
129	if (bits)	236	return dlen;
130	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
131
132	return dst - beg;
133	}	237	}
134		238
135	int dns64::decode (u8 *dst, char *src, int len)	239	#if 0
136	{	240	struct test { test (); } test;
137	// slow, but easy to debug
138	u8 *beg = dst;
139	unsigned int accum, bits = 0;
140		241
141	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++)
142	{	251	{
143	s8 chr = decode_chars [(u8)*src++];	252	int elen = cdc.encode (enc, in, i);
		253	int dlen = cdc.decode (dec, enc, elen);
144		254
145	if (!chr)	255	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	}	256	}
		257	abort ();
		258	}
		259	#endif
158		260
159	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;
160	}	294	}
161		295
162	/////////////////////////////////////////////////////////////////////////////	296	/////////////////////////////////////////////////////////////////////////////
163		297
164	struct byte_stream	298	struct byte_stream
…		…
193	}	327	}
194		328
195	void byte_stream::remove (int count)	329	void byte_stream::remove (int count)
196	{	330	{
197	if (count > fill)	331	if (count > fill)
198	abort ();	332	assert (count <= fill);
199		333
200	memmove (data, data + count, fill -= count);	334	memmove (data, data + count, fill -= count);
201	}	335	}
202		336
203	bool byte_stream::put (u8 *data, unsigned int datalen)	337	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
216	return false;	350	return false;
217		351
218	data [fill++] = pkt->len >> 8;	352	data [fill++] = pkt->len >> 8;
219	data [fill++] = pkt->len;	353	data [fill++] = pkt->len;
220		354
221	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	355	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
222		356
223	return true;	357	return true;
224	}	358	}
225		359
226	vpn_packet *byte_stream::get ()	360	vpn_packet *byte_stream::get ()
227	{	361	{
		362	unsigned int len;
		363
		364	for (;;)
		365	{
228	int len = (data [0] << 8) | data [1];	366	len = (data [0] << 8) | data [1];
229		367
230	if (len > MAXSIZE && fill >= 2)	368	if (len <= MAXSIZE || fill < 2)
231	abort (); // TODO handle this gracefully, connection reset	369	break;
232		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
233	if (fill < len + 2)	376	if (fill < len + 2)
234	return 0;	377	return 0;
235		378
236	vpn_packet *pkt = new vpn_packet;	379	vpn_packet *pkt = new vpn_packet;
237		380
238	pkt->len = len;	381	pkt->len = len;
239	memcpy (&((*pkt)[0]), data + 2, len);	382	memcpy (pkt->at (0), data + 2, len);
240	remove (len + 2);	383	remove (len + 2);
241		384
242	return pkt;	385	return pkt;
243	}	386	}
244		387
245	/////////////////////////////////////////////////////////////////////////////	388	/////////////////////////////////////////////////////////////////////////////
246		389
247	#define FLAG_QUERY ( 0 << 15)	390	#define FLAG_QUERY ( 0 << 15)
248	#define FLAG_RESPONSE ( 1 << 15)	391	#define FLAG_RESPONSE ( 1 << 15)
249	#define FLAG_OP_MASK (15 << 14)	392	#define FLAG_OP_MASK (15 << 11)
250	#define FLAG_OP_QUERY ( 0 << 11)	393	#define FLAG_OP_QUERY ( 0 << 11)
251	#define FLAG_AA ( 1 << 10)	394	#define FLAG_AA ( 1 << 10)
252	#define FLAG_TC ( 1 << 9)	395	#define FLAG_TC ( 1 << 9)
253	#define FLAG_RD ( 1 << 8)	396	#define FLAG_RD ( 1 << 8)
254	#define FLAG_RA ( 1 << 7)	397	#define FLAG_RA ( 1 << 7)
…		…
261	#define FLAG_RCODE_REFUSED ( 5 << 0)	404	#define FLAG_RCODE_REFUSED ( 5 << 0)
262		405
263	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	406	#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)	407	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
265		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 delay; // time in 0.01s units that the server may delay replying packets
		429	u8 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	delay = 0;
		458
		459	r3 = r4 = 0;
		460	r4 = r5 = r6 = r7 = 0;
		461	}
		462
		463	bool dns_cfg::valid ()
		464	{
		465	return id1 == 'G'
		466	&& id2 == 'V'
		467	&& id3 == 'P'
		468	&& id4 == 'E'
		469	&& seq_cdc == 26
		470	&& req_cdc == 62
		471	&& rep_cdc == 0
		472	&& version == 1;
		473	}
		474
266	struct dns_packet : net_packet	475	struct dns_packet : net_packet
267	{	476	{
268	u16 id;	477	u16 id;
269	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	478	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
270	u16 qdcount, ancount, nscount, arcount;	479	u16 qdcount, ancount, nscount, arcount;
271		480
272	u8 data[MAXSIZE - 6 * 2];	481	u8 data [MAXSIZE - 6 * 2];
273		482
274	int decode_label (char *data, int size, int &offs);	483	int decode_label (char *data, int size, int &offs);
275	};	484	};
276		485
277	int dns_packet::decode_label (char *data, int size, int &offs)	486	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
308	return data - orig;	517	return data - orig;
309	}	518	}
310		519
311	/////////////////////////////////////////////////////////////////////////////	520	/////////////////////////////////////////////////////////////////////////////
312		521
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	522	static u16 dns_id = 0; // TODO: should be per-vpn
326		523
327	static u16 next_id ()	524	static u16 next_id ()
328	{	525	{
		526	if (!dns_id)
		527	dns_id = time (0);
		528
329	// the simplest lsfr with periodicity 65535 i could find	529	// the simplest lsfr with periodicity 65535 i could find
330	dns_id = (dns_id << 1)	530	dns_id = (dns_id << 1)
331	| (((dns_id >> 1)	531	| (((dns_id >> 1)
332	^ (dns_id >> 2)	532	^ (dns_id >> 2)
333	^ (dns_id >> 4)	533	^ (dns_id >> 4)
334	^ (dns_id >> 15)) & 1);	534	^ (dns_id >> 15)) & 1);
335		535
336	return dns_id;	536	return dns_id;
337	}	537	}
338		538
339	dns_req::dns_req (connection *c)	539	struct dns_rcv;
340	: conn (c)	540	struct dns_snd;
		541
		542	struct dns_connection
341	{	543	{
342	next = 0;	544	connection *c;
		545	struct vpn *vpn;
		546
		547	dns_cfg cfg;
		548
		549	bool established;
		550
		551	tstamp last_received;
		552	tstamp last_sent;
		553	double min_latency;
		554	double poll_interval, send_interval;
		555
		556	vector<dns_rcv *> rcvpq;
		557
		558	byte_stream rcvdq; int rcvseq;
		559	byte_stream snddq; int sndseq;
		560
		561	void time_cb (time_watcher &w); time_watcher tw;
		562	void receive_rep (dns_rcv *r);
		563
		564	dns_connection (connection *c);
		565	~dns_connection ();
		566	};
		567
		568	struct dns_snd
		569	{
		570	dns_packet *pkt;
		571	tstamp timeout, sent;
		572	int retry;
		573	struct dns_connection *dns;
		574	int seqno;
		575	bool stdhdr;
		576
		577	void gen_stream_req (int seqno, byte_stream &stream);
		578	void gen_syn_req ();
		579
		580	dns_snd (dns_connection *dns);
		581	~dns_snd ();
		582	};
		583
		584	dns_snd::dns_snd (dns_connection *dns)
		585	: dns (dns)
		586	{
		587	timeout = 0;
343	retry = 0;	588	retry = 0;
		589	seqno = 0;
		590	sent = NOW;
		591	stdhdr = false;
344		592
345	pkt = new dns_packet;	593	pkt = new dns_packet;
346		594
347	pkt->id = next_id ();	595	pkt->id = next_id ();
348	}	596	}
349		597
		598	dns_snd::~dns_snd ()
		599	{
		600	delete pkt;
		601	}
		602
		603	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		604	{
		605	// add tunnel domain
		606	for (;;)
		607	{
		608	const char *end = strchr (domain, '.');
		609
		610	if (!end)
		611	end = domain + strlen (domain);
		612
		613	int len = end - domain;
		614
		615	pkt [offs++] = len;
		616	memcpy (pkt.at (offs), domain, len);
		617	offs += len;
		618
		619	if (!*end)
		620	break;
		621
		622	domain = end + 1;
		623	}
		624	}
		625
350	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	626	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
351	{	627	{
		628	stdhdr = true;
352	this->seqno = seqno;	629	this->seqno = seqno;
		630
		631	timeout = NOW + INITIAL_TIMEOUT;
353		632
354	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	633	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
355	pkt->qdcount = htons (1);	634	pkt->qdcount = htons (1);
356		635
357	int offs = 6*2;	636	int offs = 6*2;
358	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	637	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,	638	// 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	639	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
361		640
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;	641	char enc[256], *encp = enc;
374		642	encode_header (enc, THISNODE->id, seqno);
375	memcpy (data + 3, stream->begin (), datalen);	643
376	int enclen = dns64::encode (enc, data, datalen + 3);	644	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		645
		646	if (datalen > stream.size ())
		647	datalen = stream.size ();
		648
		649	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
377	stream->remove (datalen);	650	stream.remove (datalen);
378		651
379	while (enclen)	652	while (enclen)
380	{	653	{
381	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	654	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
382		655
…		…
387	encp += lbllen;	660	encp += lbllen;
388		661
389	enclen -= lbllen;	662	enclen -= lbllen;
390	}	663	}
391		664
392	const char *suffix = THISNODE->domain;	665	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		666
414	(*pkt)[offs++] = 0;	667	(*pkt)[offs++] = 0;
415	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	668	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		669	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		670
		671	pkt->len = offs;
		672	}
		673
		674	void dns_snd::gen_syn_req ()
		675	{
		676	timeout = NOW + INITIAL_SYN_TIMEOUT;
		677
		678	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		679	pkt->qdcount = htons (1);
		680
		681	int offs = 6 * 2;
		682
		683	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		684
		685	assert (elen <= MAX_LBL_SIZE);
		686
		687	(*pkt)[offs] = elen;
		688	offs += elen + 1;
		689	append_domain (*pkt, offs, dns->c->conf->domain);
		690
		691	(*pkt)[offs++] = 0;
		692	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
416	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	693	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
417		694
418	pkt->len = offs;	695	pkt->len = offs;
419	}	696	}
420		697
…		…
439	{	716	{
440	delete pkt;	717	delete pkt;
441	}	718	}
442		719
443	/////////////////////////////////////////////////////////////////////////////	720	/////////////////////////////////////////////////////////////////////////////
444		721
445	struct dns_cfg	722	dns_connection::dns_connection (connection *c)
		723	: c (c)
		724	, rcvdq (MAX_BACKLOG * 2)
		725	, snddq (MAX_BACKLOG * 2)
		726	, tw (this, &dns_connection::time_cb)
446	{	727	{
447	u8 id1, id2, id3;	728	vpn = c->vpn;
448	u8 def_ttl;
449	u8 unused1;
450	u16 max_size;
451	u8 flags1, flags2;
452	};
453		729
		730	established = false;
		731
		732	rcvseq = sndseq = 0;
		733
		734	last_sent = last_received = 0;
		735	poll_interval = 0.5; // starting here
		736	send_interval = 0.5; // starting rate
		737	min_latency = INITIAL_TIMEOUT;
		738	}
		739
		740	dns_connection::~dns_connection ()
		741	{
		742	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		743	i != rcvpq.end ();
		744	++i)
		745	delete *i;
		746	}
		747
454	void connection::dnsv4_receive_rep (struct dns_rcv *r)	748	void dns_connection::receive_rep (dns_rcv *r)
455	{	749	{
		750	if (r->datalen)
		751	{
		752	last_received = NOW;
		753	tw.trigger ();
		754
		755	poll_interval = send_interval;
		756	}
		757	else
		758	{
		759	poll_interval *= 1.5;
		760
		761	if (poll_interval > MAX_POLL_INTERVAL)
		762	poll_interval = MAX_POLL_INTERVAL;
		763	}
		764
456	dns_rcvpq.push_back (r);	765	rcvpq.push_back (r);
457		766
458	redo:	767	redo:
459		768
		769	// find next packet
460	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	770	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461	i != dns_rcvpq.end ();
462	++i)
463	if (dns_rcvseq == (*i)->seqno)	771	if (SEQNO_EQ (rcvseq, (*i)->seqno))
464	{	772	{
		773	// enter the packet into our input stream
465	dns_rcv *r = *i;	774	r = *i;
466		775
		776	// remove the oldest packet, look forward, as it's oldest first
		777	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		778	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		779	{
		780	delete *j;
		781	rcvpq.erase (j);
		782	break;
		783	}
		784
467	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	785	rcvseq = (rcvseq + 1) & SEQNO_MASK;
468		786
469	if (!dns_snddq && !dns_rcvdq)	787	if (!rcvdq.put (r->data, r->datalen))
470	{	788	{
471	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	789	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472	dns_snddq = new byte_stream (MAX_BACKLOG);	790	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	}	791	}
476		792
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 ())	793	while (vpn_packet *pkt = rcvdq.get ())
481	{	794	{
482	sockinfo si;	795	sockinfo si;
483	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	796	si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
484		797
485	vpn->recv_vpn_packet (pkt, si);	798	vpn->recv_vpn_packet (pkt, si);
		799
		800	delete pkt;
486	}	801	}
487	}	802
488	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	803	// 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;	804	goto redo;
495	}	805	}
496	}	806	}
497		807
498	dns_packet *	808	void
499	vpn::dnsv4_server (dns_packet *pkt)	809	vpn::dnsv4_server (dns_packet &pkt)
500	{	810	{
501	u16 flags = ntohs (pkt->flags);	811	u16 flags = ntohs (pkt.flags);
502		812
503	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504	int offs = 6 * 2; // skip header	813	int offs = 6 * 2; // skip header
505		814
506	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	815	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507		816
508	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	817	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509	&& pkt->qdcount == htons (1))	818	&& pkt.qdcount == htons (1))
510	{	819	{
511	char qname[MAXSIZE];	820	char qname [MAXSIZE];
512	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	821	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513		822
514	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	823	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	824	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516		825
517	pkt->qdcount = htons (1);	826	pkt.qdcount = htons (1);
518	pkt->ancount = 0;	827	pkt.ancount = 0;
519	pkt->nscount = 0; // should be self, as other nameservers reply like this	828	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	829	pkt.arcount = 0; // a record for self, as other nameservers reply like this
521		830
522	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	831	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523		832
524	int dlen = strlen (THISNODE->domain);	833	int dlen = strlen (THISNODE->domain);
525		834
526	if (qclass == RR_CLASS_IN	835	if (qclass == RR_CLASS_IN
527	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528	&& qlen > dlen + 1	836	&& qlen > dlen + 1
529	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	837	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
530	{	838	{
531	// correct class, domain: parse	839	// now generate reply
532	u8 data[MAXSIZE];	840	pkt.ancount = htons (1); // one answer RR
533	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	841	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534		842
535	int client = data[0];	843	if ((qtype == RR_TYPE_ANY
536	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	844	|| qtype == RR_TYPE_TXT
537		845	|| qtype == RR_TYPE_NULL)
538	if (0 < client && client <= conns.size ())	846	&& qlen > dlen + 1 + HDRSIZE)
539	{	847	{
		848	// correct class, domain: parse
		849	int client, seqno;
		850	decode_header (qname, client, seqno);
		851
		852	u8 data[MAXSIZE];
		853	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		854
		855	if (0 < client && client <= conns.size ())
		856	{
540	connection *c = conns [client - 1];	857	connection *c = conns [client - 1];
		858	dns_connection *dns = c->dns;
		859	dns_rcv *rcv;
		860	bool in_seq;
541		861
542	redo:	862	if (dns)
543
544	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545	i != c->dns_rcvpq.end ();
546	++i)	863	{
		864	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547	if ((*i)->seqno == seqno)	865	if (SEQNO_EQ ((*i)->seqno, seqno))
		866	{
		867	// already seen that request: simply reply with the cached reply
		868	dns_rcv *r = *i;
		869
		870	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		871
		872	// refresh header & id, as the retry count could have changed
		873	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		874	r->pkt->id = pkt.id;
		875
		876	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		877
		878	goto duplicate_request;
		879	}
		880
		881	in_seq = dns->rcvseq == seqno;
		882
		883	// new packet, queue
		884	rcv = new dns_rcv (seqno, data, datalen);
		885	dns->receive_rep (rcv);
		886	}
		887
548	{	888	{
549	// already seen that request: simply reply with the cached reply	889	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550	dns_rcv *r = *i;
551		890
552	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	891	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		892	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		893	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		894	pkt [offs++] = 0; pkt [offs++] = 0;
		895	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
553		896
		897	int rdlen_offs = offs += 2;
		898
		899	if (dns)
		900	{
		901	int dlen = ntohs (dns->cfg.max_size) - offs;
		902
		903	// bind doesn't compress well, so reduce further by one label length
		904	dlen -= qlen;
		905
		906	// only put data into in-order sequence packets, if
		907	// we receive out-of-order packets we generate empty
		908	// replies
		909	while (dlen > 1 && !dns->snddq.empty () && in_seq)
		910	{
		911	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		912
		913	if (txtlen > dns->snddq.size ())
		914	txtlen = dns->snddq.size ();
		915
		916	pkt[offs++] = txtlen;
		917	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		918	offs += txtlen;
		919	dns->snddq.remove (txtlen);
		920
		921	dlen -= txtlen + 1;
		922	}
		923
		924	// avoid empty TXT rdata
		925	if (offs == rdlen_offs)
		926	pkt[offs++] = 0;
		927
		928	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		929	}
		930	else
		931	{
		932	// send RST
		933	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		934	pkt [offs++] = CMD_IP_RST;
		935	}
		936
		937	int rdlen = offs - rdlen_offs;
		938
		939	pkt [rdlen_offs - 2] = rdlen >> 8;
		940	pkt [rdlen_offs - 1] = rdlen;
		941
		942	if (dns)
		943	{
		944	// now update dns_rcv copy
554	offs = r->pkt->len;	945	rcv->pkt->len = offs;
555	memcpy (pkt->at (0), r->pkt->at (0), offs);	946	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556	goto duplicate_request;	947	}
557	}	948	}
558		949
559	// new packet, queue	950	duplicate_request: ;
560	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	951	}
561	c->dnsv4_receive_rep (rcv);	952	else
562
563	// now generate reply
564	pkt->ancount = htons (1); // one answer RR
565	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	953	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		954	}
		955	else if (qtype == RR_TYPE_A
		956	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		957	{
		958	dns_cfg cfg;
		959	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		960	int client = ntohs (cfg.client);
566		961
567	(*pkt) [offs++] = 0xc0;
568	(*pkt) [offs++] = 6 * 2; // same as in query section	962	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569		963
570	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	964	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	965	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	966	pkt [offs++] = 0; pkt [offs++] = 0;
574	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	967	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		968	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
575		969
576	int dlen = MAX_PKT_SIZE - offs - 2;	970	slog (L_INFO, _("DNS: client %d connects"), client);
577		971
578	// bind doesn't compress well, so reduce further by one label length	972	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
579	dlen -= qlen;	973	pkt [offs++] = CMD_IP_REJ;
580		974
581	int rdlen_offs = offs += 2;	975	if (0 < client && client <= conns.size ())
582
583	while (c->dns_snddq
584	&& !c->dns_snddq->empty ()
585	&& dlen > 1)
586	{	976	{
587	int txtlen = dlen <= 255 ? dlen - 1 : 255;	977	connection *c = conns [client - 1];
588		978
589	if (txtlen > c->dns_snddq->size ())	979	if (cfg.valid ())
590	txtlen = c->dns_snddq->size ();	980	{
		981	pkt [offs - 1] = CMD_IP_SYN;
591		982
592	(*pkt)[offs++] = txtlen;	983	delete c->dns;
593	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	984	c->dns = new dns_connection (c);
594	offs += txtlen;	985	c->dns->cfg = cfg;
595	c->dns_snddq->remove (txtlen);	986	}
596
597	dlen -= txtlen + 1;
598	}	987	}
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	}	988	}
615	else
616	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617	}	989	}
618		990
619	pkt->len = offs;	991	pkt.len = offs;
620	}	992	}
621
622	return pkt;
623	}	993	}
624		994
625	void	995	void
626	vpn::dnsv4_client (dns_packet *pkt)	996	vpn::dnsv4_client (dns_packet &pkt)
627	{	997	{
628	u16 flags = ntohs (pkt->flags);	998	u16 flags = ntohs (pkt.flags);
629	int offs = 6 * 2; // skip header	999	int offs = 6 * 2; // skip header
630		1000
631	pkt->qdcount = ntohs (pkt->qdcount);	1001	pkt.qdcount = ntohs (pkt.qdcount);
632	pkt->ancount = ntohs (pkt->ancount);	1002	pkt.ancount = ntohs (pkt.ancount);
633		1003
634	// go through our request list and find the corresponding request	1004	// go through our request list and find the corresponding request
635	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1005	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636	i != dns_sndpq.end ();	1006	i != dns_sndpq.end ();
637	++i)	1007	++i)
638	if ((*i)->pkt->id == pkt->id)	1008	if ((*i)->pkt->id == pkt.id)
639	{	1009	{
		1010	dns_connection *dns = (*i)->dns;
640	connection *c = (*i)->conn;	1011	connection *c = dns->c;
641	int seqno = (*i)->seqno;	1012	int seqno = (*i)->seqno;
642	u8 data[MAXSIZE], *datap = data;	1013	u8 data[MAXSIZE], *datap = data;
643		1014
		1015	if ((*i)->retry)
		1016	{
		1017	dns->send_interval *= 1.01;
		1018	if (dns->send_interval > MAX_SEND_INTERVAL)
		1019	dns->send_interval = MAX_SEND_INTERVAL;
		1020	}
		1021	else
		1022	{
		1023	#if 0
		1024	dns->send_interval *= 0.999;
		1025	#endif
		1026	// the latency surely puts an upper bound on
		1027	// the minimum send interval
		1028	double latency = NOW - (*i)->sent;
		1029
		1030	if (latency < dns->min_latency)
		1031	dns->min_latency = latency;
		1032
		1033	if (dns->send_interval > dns->min_latency * LATENCY_FACTOR)
		1034	dns->send_interval = dns->min_latency * LATENCY_FACTOR;
		1035
		1036	if (dns->send_interval < MIN_SEND_INTERVAL)
		1037	dns->send_interval = MIN_SEND_INTERVAL;
		1038	}
		1039
644	delete *i;	1040	delete *i;
645	dns_sndpq.erase (i);	1041	dns_sndpq.erase (i);
646		1042
647	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1043	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648	{	1044	{
649	char qname[MAXSIZE];	1045	char qname[MAXSIZE];
650		1046
651	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1047	while (pkt.qdcount-- && offs < MAXSIZE - 4)
652	{	1048	{
653	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1049	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654	offs += 4; // skip qtype, qclass	1050	offs += 4; // skip qtype, qclass
655	}	1051	}
656		1052
657	while (pkt->ancount-- && offs < MAXSIZE - 10)	1053	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658	{	1054	{
659	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1055	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660		1056
661	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1057	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1058	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663	u32 ttl = (*pkt) [offs++] << 24;	1059	u32 ttl = pkt [offs++] << 24;
664	ttl |= (*pkt) [offs++] << 16;	1060	ttl |= pkt [offs++] << 16;
665	ttl |= (*pkt) [offs++] << 8;	1061	ttl |= pkt [offs++] << 8;
666	ttl |= (*pkt) [offs++];	1062	ttl |= pkt [offs++];
667
668	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1063	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669		1064
670	if (rdlen <= MAXSIZE - offs)	1065	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671	{	1066	{
672	// decode bytes, finally	1067	if (rdlen <= MAXSIZE - offs)
673
674	while (rdlen)
675	{	1068	{
		1069	// decode bytes, finally
		1070
		1071	while (rdlen)
		1072	{
676	int txtlen = (*pkt) [offs++];	1073	int txtlen = pkt [offs++];
677		1074
678	assert (txtlen + offs < MAXSIZE - 1);	1075	assert (txtlen + offs < MAXSIZE - 1);
679		1076
680	memcpy (datap, pkt->at (offs), txtlen);	1077	memcpy (datap, pkt.at (offs), txtlen);
681	datap += txtlen; offs += txtlen;	1078	datap += txtlen; offs += txtlen;
682		1079
683	rdlen -= txtlen + 1;	1080	rdlen -= txtlen + 1;
		1081	}
684	}	1082	}
685
686	}	1083	}
		1084	else if (qtype == RR_TYPE_A)
		1085	{
		1086	u8 ip [4];
687		1087
		1088	ip [0] = pkt [offs++];
		1089	ip [1] = pkt [offs++];
		1090	ip [2] = pkt [offs++];
		1091	ip [3] = pkt [offs++];
		1092
		1093	if (ip [0] == CMD_IP_1
		1094	&& ip [1] == CMD_IP_2
		1095	&& ip [2] == CMD_IP_3)
		1096	{
		1097	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1098
		1099	if (ip [3] == CMD_IP_RST)
		1100	{
		1101	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1102
		1103	delete dns; c->dns = 0;
		1104
		1105	return;
		1106	}
		1107	else if (ip [3] == CMD_IP_SYN)
		1108	{
		1109	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1110	dns->established = true;
		1111	}
		1112	else if (ip [3] == CMD_IP_REJ)
		1113	{
		1114	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1115	abort ();
		1116	}
		1117	else
		1118	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1119	}
		1120	else
		1121	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1122	ip [0], ip [1], ip [2], ip [3]);
		1123
		1124	return;
		1125	}
		1126
		1127	int client, rseqno;
		1128	decode_header (qname, client, rseqno);
		1129
		1130	if (client != THISNODE->id)
		1131	{
		1132	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1133	datap = 0;
		1134	}
		1135	else if (rseqno != seqno)
		1136	{
		1137	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1138	datap = 0;
		1139	}
688	}	1140	}
689	}	1141	}
690		1142
691	// todo: pkt now used	1143	// todo: pkt now used
		1144	if (datap)
692	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1145	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693		1146
694	break;	1147	break;
695	}	1148	}
696
697	delete pkt;
698	}	1149	}
699		1150
700	void	1151	void
701	vpn::dnsv4_ev (io_watcher &w, short revents)	1152	vpn::dnsv4_ev (io_watcher &w, short revents)
702	{	1153	{
…		…
704	{	1155	{
705	dns_packet *pkt = new dns_packet;	1156	dns_packet *pkt = new dns_packet;
706	struct sockaddr_in sa;	1157	struct sockaddr_in sa;
707	socklen_t sa_len = sizeof (sa);	1158	socklen_t sa_len = sizeof (sa);
708		1159
709	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1160	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
710		1161
711	if (pkt->len > 0)	1162	if (pkt->len > 0)
712	{	1163	{
713	if (pkt->flags & htons (FLAG_TC))	1164	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1165	dnsv4_client (*pkt);
		1166	else
714	{	1167	{
715	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1168	dnsv4_server (*pkt);
716	//TODO connection reset	1169	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}	1170	}
718		1171
719	if (THISNODE->dns_port)	1172	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	}	1173	}
727	}	1174	}
728	}	1175	}
729		1176
730	bool	1177	bool
731	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1178	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
732	{	1179	{
733	// never initialized	1180	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		1181
739	//dns_rcvseq = dns_sndseq = 0;	1182	assert (0 < client && client <= conns.size ());
740		1183
741	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1184	connection *c = conns [client - 1];
742	}	1185
		1186	if (!c->dns)
		1187	c->dns = new dns_connection (c);
743		1188
744	if (!dns_snddq->put (pkt))	1189	if (!c->dns->snddq.put (pkt))
745	return false;	1190	return false;
746		1191
747	// start timer if neccessary	1192	c->dns->tw.trigger ();
748	if (!THISNODE->dns_port && !dnsv4_tw.active)
749	dnsv4_cb (dnsv4_tw);
750		1193
751	return true;	1194	return true;
752	}	1195	}
753		1196
754	void	1197	void
		1198	connection::dnsv4_reset_connection ()
		1199	{
		1200	//delete dns; dns = 0; //TODO
		1201	}
		1202
		1203	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1204
		1205	void
755	connection::dnsv4_cb (time_watcher &w)	1206	dns_connection::time_cb (time_watcher &w)
756	{	1207	{
		1208	// servers have to be polled
		1209	if (THISNODE->dns_port)
		1210	return;
		1211
757	// check for timeouts and (re)transmit	1212	// check for timeouts and (re)transmit
758	tstamp next = NOW + 60;	1213	tstamp next = NOW + poll_interval;
759	dns_req *send = 0;	1214	dns_snd *send = 0;
760		1215
761	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1216	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762	i != vpn->dns_sndpq.end ();	1217	i != vpn->dns_sndpq.end ();
763	++i)	1218	++i)
764	{	1219	{
765	dns_req *r = *i;	1220	dns_snd *r = *i;
766		1221
767	if (r->next <= NOW)	1222	if (r->timeout <= NOW)
768	{	1223	{
769	if (!send)	1224	if (!send)
770	{	1225	{
771	send = r;	1226	send = r;
772		1227
773	if (r->retry)//D
774	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775	r->retry++;	1228	r->retry++;
776	r->next = NOW + r->retry;	1229	r->timeout = NOW + (r->retry * min_latency * 8.);
		1230
		1231	// the following code changes the query section a bit, forcing
		1232	// the forwarder to generate a new request
		1233	if (r->stdhdr)
		1234	{
		1235	//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1236	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1237	}
777	}	1238	}
778	}	1239	}
779		1240	else
780	if (r->next < next)	1241	NEXT (r->timeout);
781	next = r->next;
782	}	1242	}
783		1243
784	if (!send	1244	if (!send)
		1245	{
		1246	// generate a new packet, if wise
		1247
		1248	if (!established)
		1249	{
		1250	if (vpn->dns_sndpq.empty ())
		1251	{
		1252	send = new dns_snd (this);
		1253
		1254	cfg.reset (THISNODE->id);
		1255	send->gen_syn_req ();
		1256	}
		1257	}
785	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1258	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
786	{	1259	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1260	{
		1261	if (last_sent + send_interval <= NOW)
		1262	{
		1263	//printf ("sending data request etc.\n"); //D
		1264	if (!snddq.empty () || last_received + 1. > NOW)
		1265	{
		1266	poll_interval = send_interval;
		1267	NEXT (NOW + send_interval);
		1268	}
		1269
787	send = new dns_req (this);	1270	send = new dns_snd (this);
788	send->gen_stream_req (dns_sndseq, dns_snddq);	1271	send->gen_stream_req (sndseq, snddq);
		1272	send->timeout = NOW + min_latency * 8.;
		1273
		1274	sndseq = (sndseq + 1) & SEQNO_MASK;
		1275	}
		1276	else
		1277	NEXT (last_sent + send_interval);
		1278	}
		1279
		1280	if (send)
789	vpn->dns_sndpq.push_back (send);	1281	vpn->dns_sndpq.push_back (send);
790
791	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792	}	1282	}
793
794	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795		1283
796	if (send)	1284	if (send)
797	{	1285	{
798	dns_packet *pkt = send->pkt;	1286	last_sent = NOW;
799		1287	sendto (vpn->dnsv4_fd,
800	next = min_next;	1288	send->pkt->at (0), send->pkt->len, 0,
801		1289	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	}	1290	}
804	else if (next < min_next)	1291
805	next = min_next;	1292	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1293	poll_interval, send_interval, next - NOW,
		1294	vpn->dns_sndpq.size (), snddq.size (),
		1295	rcvpq.size ());
		1296
		1297	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1298	if (next < NOW + 0.001)
		1299	next = NOW + 0.1;
806		1300
807	w.start (next);	1301	w.start (next);
808	}	1302	}
809		1303
810	#endif	1304	#endif

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