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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 1.24 by pcg, Mon Mar 7 01:31:26 2005 UTC

1	/*	1	/*
2	vpn_dns.C -- handle the dns tunnel part of the protocol.	2	vpn_dns.C -- handle the dns tunnel part of the protocol.
3	Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com>	3	Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de>
4		4
		5	This file is part of GVPE.
		6
5	This program is free software; you can redistribute it and/or modify	7	GVPE is free software; you can redistribute it and/or modify
6	it under the terms of the GNU General Public License as published by	8	it under the terms of the GNU General Public License as published by
7	the Free Software Foundation; either version 2 of the License, or	9	the Free Software Foundation; either version 2 of the License, or
8	(at your option) any later version.	10	(at your option) any later version.
9		11
10	This program is distributed in the hope that it will be useful,	12	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.	15	GNU General Public License for more details.
14		16
15	You should have received a copy of the GNU General Public License	17	You should have received a copy of the GNU General Public License
16	along with this program; if not, write to the Free Software	18	along with gvpe; if not, write to the Free Software
17	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA	19	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18	*/	20	*/
19		21
20	#include "config.h"	22	#include "config.h"
21		23
…		…
23		25
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	27	// it's a hack, use only in emergency situations please.
26		28
27	#include <cstring>	29	#include <cstring>
		30	#include <cassert>
28		31
29	#include <sys/types.h>	32	#include <sys/types.h>
30	#include <sys/socket.h>	33	#include <sys/socket.h>
31	#include <sys/wait.h>	34	#include <sys/wait.h>
32	#include <sys/uio.h>	35	#include <sys/uio.h>
…		…
35	#include <unistd.h>	38	#include <unistd.h>
36	#include <fcntl.h>	39	#include <fcntl.h>
37		40
38	#include <map>	41	#include <map>
39		42
		43	#include <gmp.h>
		44
40	#include "netcompat.h"	45	#include "netcompat.h"
41		46
42	#include "vpn.h"	47	#include "vpn.h"
43		48
44	#define MIN_RETRY 1.	49	#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data
45	#define MAX_RETRY 60.	50	#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data
		51	#define ACTIVITY_INTERVAL 5.
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 0.5 // optimistic?
		58
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	59	#define MAX_OUTSTANDING 10 // max. outstanding requests
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	60	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
49	#define MAX_RATE 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 220 // 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 r2, r3, r4;
		429
		430	u8 r5, r6, r7, r8;
		431
		432	void reset (int clientid);
		433	bool valid ();
		434	};
		435
		436	int dns_cfg::next_uid;
		437
		438	void dns_cfg::reset (int clientid)
		439	{
		440	id1 = 'G';
		441	id2 = 'V';
		442	id3 = 'P';
		443	id4 = 'E';
		444
		445	version = 1;
		446
		447	rrtype = RR_TYPE_TXT;
		448	flags = 0;
		449	def_ttl = 0;
		450	seq_cdc = 26;
		451	req_cdc = 62;
		452	rep_cdc = 0;
		453	max_size = ntohs (MAX_PKT_SIZE);
		454	client = ntohs (clientid);
		455	uid = next_uid++;
		456
		457	r2 = r3 = r4 = 0;
		458	r4 = r5 = r6 = r7 = 0;
		459	}
		460
		461	bool dns_cfg::valid ()
		462	{
		463	return id1 == 'G'
		464	&& id2 == 'V'
		465	&& id3 == 'P'
		466	&& id4 == 'E'
		467	&& seq_cdc == 26
		468	&& req_cdc == 62
		469	&& rep_cdc == 0
		470	&& version == 1
		471	&& max_size == ntohs (MAX_PKT_SIZE);
		472	}
		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 last_latency;
		553	double poll_interval, send_interval;
		554
		555	vector<dns_rcv *> rcvpq;
		556
		557	byte_stream rcvdq; int rcvseq;
		558	byte_stream snddq; int sndseq;
		559
		560	void time_cb (time_watcher &w); time_watcher tw;
		561	void receive_rep (dns_rcv *r);
		562
		563	dns_connection (connection *c);
		564	~dns_connection ();
		565	};
		566
		567	struct dns_snd
		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	last_latency = INITIAL_TIMEOUT;
		737	}
		738
		739	dns_connection::~dns_connection ()
		740	{
		741	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		742	i != rcvpq.end ();
		743	++i)
		744	delete *i;
		745	}
		746
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	if (poll_interval > MAX_POLL_INTERVAL)
		760	poll_interval = MAX_POLL_INTERVAL;
		761	}
		762
456	dns_rcvpq.push_back (r);	763	rcvpq.push_back (r);
457		764
458	redo:	765	redo:
459		766
		767	// find next packet
460	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	768	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461	i != dns_rcvpq.end ();
462	++i)
463	if (dns_rcvseq == (*i)->seqno)	769	if (SEQNO_EQ (rcvseq, (*i)->seqno))
464	{	770	{
		771	// enter the packet into our input stream
465	dns_rcv *r = *i;	772	r = *i;
466		773
		774	// remove the oldest packet, look forward, as it's oldest first
		775	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		776	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		777	{
		778	delete *j;
		779	rcvpq.erase (j);
		780	break;
		781	}
		782
467	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	783	rcvseq = (rcvseq + 1) & SEQNO_MASK;
468		784
469	if (!dns_snddq && !dns_rcvdq)	785	if (!rcvdq.put (r->data, r->datalen))
470	{	786	{
471	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	787	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472	dns_snddq = new byte_stream (MAX_BACKLOG);	788	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	}	789	}
476		790
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 ())	791	while (vpn_packet *pkt = rcvdq.get ())
481	{	792	{
482	sockinfo si;	793	sockinfo si;
483	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	794	si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
484		795
485	vpn->recv_vpn_packet (pkt, si);	796	vpn->recv_vpn_packet (pkt, si);
		797
		798	delete pkt;
486	}	799	}
487	}	800
488	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	801	// 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;	802	goto redo;
495	}	803	}
496	}	804	}
497		805
498	dns_packet *	806	void
499	vpn::dnsv4_server (dns_packet *pkt)	807	vpn::dnsv4_server (dns_packet &pkt)
500	{	808	{
501	u16 flags = ntohs (pkt->flags);	809	u16 flags = ntohs (pkt.flags);
502		810
503	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504	int offs = 6 * 2; // skip header	811	int offs = 6 * 2; // skip header
505		812
506	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	813	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507		814
508	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	815	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509	&& pkt->qdcount == htons (1))	816	&& pkt.qdcount == htons (1))
510	{	817	{
511	char qname[MAXSIZE];	818	char qname [MAXSIZE];
512	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	819	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513		820
514	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	821	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	822	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516		823
517	pkt->qdcount = htons (1);	824	pkt.qdcount = htons (1);
518	pkt->ancount = 0;	825	pkt.ancount = 0;
519	pkt->nscount = 0; // should be self, as other nameservers reply like this	826	pkt.nscount = 0; // should be self, as other nameservers reply like this
520	pkt->arcount = 0; // a record for self, as other nameservers reply like this	827	pkt.arcount = 0; // a record for self, as other nameservers reply like this
521		828
522	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	829	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523		830
524	int dlen = strlen (THISNODE->domain);	831	int dlen = strlen (THISNODE->domain);
525		832
526	if (qclass == RR_CLASS_IN	833	if (qclass == RR_CLASS_IN
527	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528	&& qlen > dlen + 1	834	&& qlen > dlen + 1
529	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	835	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
530	{	836	{
531	// correct class, domain: parse	837	// now generate reply
532	u8 data[MAXSIZE];	838	pkt.ancount = htons (1); // one answer RR
533	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	839	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534		840
535	int client = data[0];	841	if ((qtype == RR_TYPE_ANY
536	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	842	|| qtype == RR_TYPE_TXT
537		843	|| qtype == RR_TYPE_NULL)
538	if (0 < client && client <= conns.size ())	844	&& qlen > dlen + 1 + HDRSIZE)
539	{	845	{
		846	// correct class, domain: parse
		847	int client, seqno;
		848	decode_header (qname, client, seqno);
		849
		850	u8 data[MAXSIZE];
		851	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		852
		853	if (0 < client && client <= conns.size ())
		854	{
540	connection *c = conns [client - 1];	855	connection *c = conns [client - 1];
		856	dns_connection *dns = c->dns;
		857	dns_rcv *rcv;
		858	bool in_seq;
541		859
542	redo:	860	if (dns)
543
544	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545	i != c->dns_rcvpq.end ();
546	++i)	861	{
		862	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547	if ((*i)->seqno == seqno)	863	if (SEQNO_EQ ((*i)->seqno, seqno))
		864	{
		865	// already seen that request: simply reply with the cached reply
		866	dns_rcv *r = *i;
		867
		868	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		869
		870	// refresh header & id, as the retry count could have changed
		871	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		872	r->pkt->id = pkt.id;
		873
		874	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		875
		876	goto duplicate_request;
		877	}
		878
		879	in_seq = dns->rcvseq == seqno;
		880
		881	// new packet, queue
		882	rcv = new dns_rcv (seqno, data, datalen);
		883	dns->receive_rep (rcv);
		884	}
		885
548	{	886	{
549	// already seen that request: simply reply with the cached reply	887	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550	dns_rcv *r = *i;
551		888
552	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	889	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		890	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		891	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		892	pkt [offs++] = 0; pkt [offs++] = 0;
		893	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
553		894
		895	int rdlen_offs = offs += 2;
		896
		897	int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs;
		898	// bind doesn't compress well, so reduce further by one label length
		899	dlen -= qlen;
		900
		901	if (dns)
		902	{
		903	// only put data into in-order sequence packets, if
		904	// we receive out-of-order packets we generate empty
		905	// replies
		906	while (dlen > 1 && !dns->snddq.empty () && in_seq)
		907	{
		908	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		909
		910	if (txtlen > dns->snddq.size ())
		911	txtlen = dns->snddq.size ();
		912
		913	pkt[offs++] = txtlen;
		914	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		915	offs += txtlen;
		916	dns->snddq.remove (txtlen);
		917
		918	dlen -= txtlen + 1;
		919	}
		920
		921	// avoid empty TXT rdata
		922	if (offs == rdlen_offs)
		923	pkt[offs++] = 0;
		924
		925	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		926	}
		927	else
		928	{
		929	// send RST
		930	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		931	pkt [offs++] = CMD_IP_RST;
		932	}
		933
		934	int rdlen = offs - rdlen_offs;
		935
		936	pkt [rdlen_offs - 2] = rdlen >> 8;
		937	pkt [rdlen_offs - 1] = rdlen;
		938
		939	if (dns)
		940	{
		941	// now update dns_rcv copy
554	offs = r->pkt->len;	942	rcv->pkt->len = offs;
555	memcpy (pkt->at (0), r->pkt->at (0), offs);	943	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556	goto duplicate_request;	944	}
557	}	945	}
558		946
559	// new packet, queue	947	duplicate_request: ;
560	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	948	}
561	c->dnsv4_receive_rep (rcv);	949	else
562
563	// now generate reply
564	pkt->ancount = htons (1); // one answer RR
565	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	950	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		951	}
		952	else if (qtype == RR_TYPE_A
		953	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		954	{
		955	dns_cfg cfg;
		956	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		957	int client = ntohs (cfg.client);
566		958
567	(*pkt) [offs++] = 0xc0;
568	(*pkt) [offs++] = 6 * 2; // same as in query section	959	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569		960
570	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	961	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	962	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	963	pkt [offs++] = 0; pkt [offs++] = 0;
574	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	964	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		965	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
575		966
576	int dlen = MAX_PKT_SIZE - offs - 2;	967	slog (L_INFO, _("DNS: client %d connects"), client);
577		968
578	// bind doesn't compress well, so reduce further by one label length	969	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
579	dlen -= qlen;	970	pkt [offs++] = CMD_IP_REJ;
580		971
581	int rdlen_offs = offs += 2;	972	if (0 < client && client <= conns.size ())
582
583	while (c->dns_snddq
584	&& !c->dns_snddq->empty ()
585	&& dlen > 1)
586	{	973	{
587	int txtlen = dlen <= 255 ? dlen - 1 : 255;	974	connection *c = conns [client - 1];
588		975
589	if (txtlen > c->dns_snddq->size ())	976	if (cfg.valid ())
590	txtlen = c->dns_snddq->size ();	977	{
		978	pkt [offs - 1] = CMD_IP_SYN;
591		979
592	(*pkt)[offs++] = txtlen;	980	delete c->dns;
593	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	981	c->dns = new dns_connection (c);
594	offs += txtlen;	982	c->dns->cfg = cfg;
595	c->dns_snddq->remove (txtlen);	983	}
596
597	dlen -= txtlen + 1;
598	}	984	}
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	}	985	}
615	else
616	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617	}	986	}
618		987
619	pkt->len = offs;	988	pkt.len = offs;
620	}	989	}
621
622	return pkt;
623	}	990	}
624		991
625	void	992	void
626	vpn::dnsv4_client (dns_packet *pkt)	993	vpn::dnsv4_client (dns_packet &pkt)
627	{	994	{
628	u16 flags = ntohs (pkt->flags);	995	u16 flags = ntohs (pkt.flags);
629	int offs = 6 * 2; // skip header	996	int offs = 6 * 2; // skip header
630		997
631	pkt->qdcount = ntohs (pkt->qdcount);	998	pkt.qdcount = ntohs (pkt.qdcount);
632	pkt->ancount = ntohs (pkt->ancount);	999	pkt.ancount = ntohs (pkt.ancount);
633		1000
634	// go through our request list and find the corresponding request	1001	// go through our request list and find the corresponding request
635	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1002	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636	i != dns_sndpq.end ();	1003	i != dns_sndpq.end ();
637	++i)	1004	++i)
638	if ((*i)->pkt->id == pkt->id)	1005	if ((*i)->pkt->id == pkt.id)
639	{	1006	{
		1007	dns_connection *dns = (*i)->dns;
640	connection *c = (*i)->conn;	1008	connection *c = dns->c;
641	int seqno = (*i)->seqno;	1009	int seqno = (*i)->seqno;
642	u8 data[MAXSIZE], *datap = data;	1010	u8 data[MAXSIZE], *datap = data;
643		1011
		1012	if ((*i)->retry)
		1013	{
		1014	dns->send_interval *= 1.01;
		1015	if (dns->send_interval > MAX_SEND_INTERVAL)
		1016	dns->send_interval = MAX_SEND_INTERVAL;
		1017	}
		1018	else
		1019	{
		1020	#if 1
		1021	dns->send_interval *= 0.999;
		1022	#endif
		1023	if (dns->send_interval < MIN_SEND_INTERVAL)
		1024	dns->send_interval = MIN_SEND_INTERVAL;
		1025
		1026	// the latency surely puts an upper bound on
		1027	// the minimum send interval
		1028	double latency = NOW - (*i)->sent;
		1029	dns->last_latency = latency;
		1030
		1031	if (dns->send_interval > latency)
		1032	dns->send_interval = latency;
		1033	}
		1034
644	delete *i;	1035	delete *i;
645	dns_sndpq.erase (i);	1036	dns_sndpq.erase (i);
646		1037
647	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1038	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648	{	1039	{
649	char qname[MAXSIZE];	1040	char qname[MAXSIZE];
650		1041
651	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1042	while (pkt.qdcount-- && offs < MAXSIZE - 4)
652	{	1043	{
653	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1044	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654	offs += 4; // skip qtype, qclass	1045	offs += 4; // skip qtype, qclass
655	}	1046	}
656		1047
657	while (pkt->ancount-- && offs < MAXSIZE - 10)	1048	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658	{	1049	{
659	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1050	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660		1051
661	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1052	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1053	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663	u32 ttl = (*pkt) [offs++] << 24;	1054	u32 ttl = pkt [offs++] << 24;
664	ttl |= (*pkt) [offs++] << 16;	1055	ttl |= pkt [offs++] << 16;
665	ttl |= (*pkt) [offs++] << 8;	1056	ttl |= pkt [offs++] << 8;
666	ttl |= (*pkt) [offs++];	1057	ttl |= pkt [offs++];
667
668	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1058	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669		1059
670	if (rdlen <= MAXSIZE - offs)	1060	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671	{	1061	{
672	// decode bytes, finally	1062	if (rdlen <= MAXSIZE - offs)
673
674	while (rdlen)
675	{	1063	{
		1064	// decode bytes, finally
		1065
		1066	while (rdlen)
		1067	{
676	int txtlen = (*pkt) [offs++];	1068	int txtlen = pkt [offs++];
677		1069
678	assert (txtlen + offs < MAXSIZE - 1);	1070	assert (txtlen + offs < MAXSIZE - 1);
679		1071
680	memcpy (datap, pkt->at (offs), txtlen);	1072	memcpy (datap, pkt.at (offs), txtlen);
681	datap += txtlen; offs += txtlen;	1073	datap += txtlen; offs += txtlen;
682		1074
683	rdlen -= txtlen + 1;	1075	rdlen -= txtlen + 1;
		1076	}
684	}	1077	}
685
686	}	1078	}
		1079	else if (qtype == RR_TYPE_A)
		1080	{
		1081	u8 ip [4];
687		1082
		1083	ip [0] = pkt [offs++];
		1084	ip [1] = pkt [offs++];
		1085	ip [2] = pkt [offs++];
		1086	ip [3] = pkt [offs++];
		1087
		1088	if (ip [0] == CMD_IP_1
		1089	&& ip [1] == CMD_IP_2
		1090	&& ip [2] == CMD_IP_3)
		1091	{
		1092	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1093
		1094	if (ip [3] == CMD_IP_RST)
		1095	{
		1096	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1097
		1098	delete dns; c->dns = 0;
		1099
		1100	return;
		1101	}
		1102	else if (ip [3] == CMD_IP_SYN)
		1103	{
		1104	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1105	dns->established = true;
		1106	}
		1107	else if (ip [3] == CMD_IP_REJ)
		1108	{
		1109	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1110	abort ();
		1111	}
		1112	else
		1113	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1114	}
		1115	else
		1116	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1117	ip [0], ip [1], ip [2], ip [3]);
		1118
		1119	return;
		1120	}
		1121
		1122	int client, rseqno;
		1123	decode_header (qname, client, rseqno);
		1124
		1125	if (client != THISNODE->id)
		1126	{
		1127	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1128	datap = 0;
		1129	}
		1130	else if (rseqno != seqno)
		1131	{
		1132	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1133	datap = 0;
		1134	}
688	}	1135	}
689	}	1136	}
690		1137
691	// todo: pkt now used	1138	// todo: pkt now used
		1139	if (datap)
692	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1140	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693		1141
694	break;	1142	break;
695	}	1143	}
696
697	delete pkt;
698	}	1144	}
699		1145
700	void	1146	void
701	vpn::dnsv4_ev (io_watcher &w, short revents)	1147	vpn::dnsv4_ev (io_watcher &w, short revents)
702	{	1148	{
…		…
704	{	1150	{
705	dns_packet *pkt = new dns_packet;	1151	dns_packet *pkt = new dns_packet;
706	struct sockaddr_in sa;	1152	struct sockaddr_in sa;
707	socklen_t sa_len = sizeof (sa);	1153	socklen_t sa_len = sizeof (sa);
708		1154
709	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1155	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
710		1156
711	if (pkt->len > 0)	1157	if (pkt->len > 0)
712	{	1158	{
713	if (pkt->flags & htons (FLAG_TC))	1159	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1160	dnsv4_client (*pkt);
		1161	else
714	{	1162	{
715	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1163	dnsv4_server (*pkt);
716	//TODO connection reset	1164	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}	1165	}
718		1166
719	if (THISNODE->dns_port)	1167	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	}	1168	}
727	}	1169	}
728	}	1170	}
729		1171
730	bool	1172	bool
731	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1173	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
732	{	1174	{
733	// never initialized	1175	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		1176
739	//dns_rcvseq = dns_sndseq = 0;	1177	assert (0 < client && client <= conns.size ());
740		1178
741	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1179	connection *c = conns [client - 1];
742	}	1180
		1181	if (!c->dns)
		1182	c->dns = new dns_connection (c);
743		1183
744	if (!dns_snddq->put (pkt))	1184	if (!c->dns->snddq.put (pkt))
745	return false;	1185	return false;
746		1186
747	// start timer if neccessary	1187	c->dns->tw.trigger ();
748	if (!THISNODE->dns_port && !dnsv4_tw.active)
749	dnsv4_cb (dnsv4_tw);
750		1188
751	return true;	1189	return true;
752	}	1190	}
753		1191
754	void	1192	void
		1193	connection::dnsv4_reset_connection ()
		1194	{
		1195	//delete dns; dns = 0; //TODO
		1196	}
		1197
		1198	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1199
		1200	void
755	connection::dnsv4_cb (time_watcher &w)	1201	dns_connection::time_cb (time_watcher &w)
756	{	1202	{
		1203	// servers have to be polled
		1204	if (THISNODE->dns_port)
		1205	return;
		1206
757	// check for timeouts and (re)transmit	1207	// check for timeouts and (re)transmit
758	tstamp next = NOW + 60;	1208	tstamp next = NOW + poll_interval;
759	dns_req *send = 0;	1209	dns_snd *send = 0;
760		1210
761	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1211	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762	i != vpn->dns_sndpq.end ();	1212	i != vpn->dns_sndpq.end ();
763	++i)	1213	++i)
764	{	1214	{
765	dns_req *r = *i;	1215	dns_snd *r = *i;
766		1216
767	if (r->next <= NOW)	1217	if (r->timeout <= NOW)
768	{	1218	{
769	if (!send)	1219	if (!send)
770	{	1220	{
771	send = r;	1221	send = r;
772		1222
773	if (r->retry)//D
774	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775	r->retry++;	1223	r->retry++;
776	r->next = NOW + r->retry;	1224	r->timeout = NOW + (r->retry * last_latency * 8.);
		1225
		1226	// the following code changes the query section a bit, forcing
		1227	// the forwarder to generate a new request
		1228	if (r->stdhdr)
		1229	{
		1230	//printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1231	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1232	}
777	}	1233	}
778	}	1234	}
		1235	else
		1236	NEXT (r->timeout);
		1237	}
779		1238
780	if (r->next < next)	1239	if (last_sent + send_interval <= NOW)
781	next = r->next;
782	}	1240	{
783
784	if (!send	1241	if (!send)
		1242	{
		1243	// generate a new packet, if wise
		1244
		1245	if (!established)
		1246	{
		1247	if (vpn->dns_sndpq.empty ())
		1248	{
		1249	send = new dns_snd (this);
		1250
		1251	cfg.reset (THISNODE->id);
		1252	send->gen_syn_req ();
		1253	}
		1254	}
785	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1255	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
786	{	1256	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1257	{
		1258	//printf ("sending data request etc.\n"); //D
		1259	if (!snddq.empty ())
		1260	{
		1261	poll_interval = send_interval;
		1262	NEXT (NOW + send_interval);
		1263	}
		1264
787	send = new dns_req (this);	1265	send = new dns_snd (this);
788	send->gen_stream_req (dns_sndseq, dns_snddq);	1266	send->gen_stream_req (sndseq, snddq);
		1267	send->timeout = NOW + last_latency * 8.;
		1268
		1269	sndseq = (sndseq + 1) & SEQNO_MASK;
		1270	}
		1271
		1272	if (send)
789	vpn->dns_sndpq.push_back (send);	1273	vpn->dns_sndpq.push_back (send);
		1274	}
790		1275
791	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792	}
793
794	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795
796	if (send)	1276	if (send)
		1277	{
		1278	last_sent = NOW;
		1279	sendto (vpn->dnsv4_fd,
		1280	send->pkt->at (0), send->pkt->len, 0,
		1281	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1282	}
797	{	1283	}
798	dns_packet *pkt = send->pkt;	1284	else
		1285	NEXT (last_sent + send_interval);
799		1286
800	next = min_next;	1287	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)",
		1288	poll_interval, send_interval, next - NOW,
		1289	vpn->dns_sndpq.size (), snddq.size ());
801		1290
802	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());	1291	// TODO: no idea when this happens, but when next < NOW, we have a problem
803	}	1292	if (next < NOW + 0.0001)
804	else if (next < min_next)	1293	next = NOW + 0.1;
805	next = min_next;
806		1294
807	w.start (next);	1295	w.start (next);
808	}	1296	}
809		1297
810	#endif	1298	#endif

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