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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.7 by pcg, Thu Mar 3 16:54:34 2005 UTC vs.
Revision 1.47 by pcg, Thu Aug 7 17:54:27 2008 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) 2003-2005 Marc Lehmann <gvpe@schmorp.de>	3	Copyright (C) 2003-2008 Marc Lehmann <gvpe@schmorp.de>
4		4
5	This file is part of GVPE.	5	This file is part of GVPE.
6		6
7	GVPE is free software; you can redistribute it and/or modify	7	GVPE is free software; you can redistribute it and/or modify it
8	it under the terms of the GNU General Public License as published by	8	under the terms of the GNU General Public License as published by the
9	the Free Software Foundation; either version 2 of the License, or	9	Free Software Foundation; either version 3 of the License, or (at your
10	(at your option) any later version.	10	option) any later version.
11		11
12	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, but
13	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	WITHOUT ANY WARRANTY; without even the implied warranty of
14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
15	GNU General Public License for more details.	15	Public License for more details.
16		16
17	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 along
18	along with gvpe; if not, write to the Free Software	18	with this program; if not, see <http://www.gnu.org/licenses/>.
19	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA	19
		20	Additional permission under GNU GPL version 3 section 7
		21
		22	If you modify this Program, or any covered work, by linking or
		23	combining it with the OpenSSL project's OpenSSL library (or a modified
		24	version of that library), containing parts covered by the terms of the
		25	OpenSSL or SSLeay licenses, the licensors of this Program grant you
		26	additional permission to convey the resulting work. Corresponding
		27	Source for a non-source form of such a combination shall include the
		28	source code for the parts of OpenSSL used as well as that of the
		29	covered work.
20	*/	30	*/
		31
		32	// TODO: EDNS0 option to increase dns mtu?
		33	// TODO: re-write dns packet parsing/creation using a safe mem-buffer
		34	// to ensure no buffer overflows or similar problems.
21		35
22	#include "config.h"	36	#include "config.h"
23		37
24	#if ENABLE_DNS	38	#if ENABLE_DNS
25		39
26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	40	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27	// it's a hack, use only in emergency situations please.	41	// it's a hack, use only in emergency situations please.
28		42
29	#include <cstring>	43	#include <cstring>
		44	#include <cassert>
30		45
31	#include <sys/types.h>	46	#include <sys/types.h>
32	#include <sys/socket.h>	47	#include <sys/socket.h>
33	#include <sys/wait.h>	48	#include <sys/wait.h>
34	#include <sys/uio.h>	49	#include <sys/uio.h>
…		…
37	#include <unistd.h>	52	#include <unistd.h>
38	#include <fcntl.h>	53	#include <fcntl.h>
39		54
40	#include <map>	55	#include <map>
41		56
		57	#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
		58	#include <gmp.h>
		59
42	#include "netcompat.h"	60	#include "netcompat.h"
43		61
44	#include "vpn.h"	62	#include "vpn.h"
45		63
46	#define MIN_RETRY 1.	64	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
47	#define MAX_RETRY 60.	65	#define ACTIVITY_INTERVAL 5.
48		66
49	#define MAX_OUTSTANDING 40 // max. outstanding requests	67	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		68	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
		69
		70	#define MAX_SEND_INTERVAL 2. // optimistic?
		71
50	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	72	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
51	#define MAX_RATE 1000 // requests/s
52	#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE	73	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
53		74
54	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	75	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
55	// 240 leaves about 4 bytes of server reply data	76	// 240 leaves about 4 bytes of server reply data
56	// every two request byte sless give room for one reply byte	77	// every request byte less give room for two reply bytes
57		78
58	// seqno has 12 bits, but the lower bit is always left as zero
59	// as bind caches ttl=0 records and we have to generate
60	// sequence numbers that always differ case-insensitively
61	#define SEQNO_MASK 0x07ff	79	#define SEQNO_MASK 0x3fff
62		80	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
63	/*
64
65	protocol, in shorthand :)
66
67	client -> server <req> ANY?
68	server -> client <req> TXT <rep>
69
70	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
71	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
72
73	if <client-id> is zero, the connection will be configured:
74
75	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
76
77	*/
78		81
79	#define MAX_LBL_SIZE 63	82	#define MAX_LBL_SIZE 63
80	#define MAX_PKT_SIZE 512	83	#define MAX_PKT_SIZE 512
81		84
		85	#define RR_TYPE_A 1
		86	#define RR_TYPE_NULL 10
82	#define RR_TYPE_TXT 16	87	#define RR_TYPE_TXT 16
83	#define RR_TYPE_ANY 255	88	#define RR_TYPE_ANY 255
		89
84	#define RR_CLASS_IN 1	90	#define RR_CLASS_IN 1
85		91
86	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	92	#define CMD_IP_1 207
87	struct dns64	93	#define CMD_IP_2 46
88	{	94	#define CMD_IP_3 236
89	static const char encode_chars[64 + 1];	95	#define CMD_IP_RST 29
90	static s8 decode_chars[256];	96	#define CMD_IP_SYN 113
		97	#define CMD_IP_REJ 32
91		98
92	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	99	// works for cmaps up to 255 (not 256!)
93	static int decode_len (int bytes) { return (bytes * 6) / 8; }	100	struct charmap
		101	{
		102	enum { INVALID = (u8)255 };
		103
		104	char encode [256]; // index => char
		105	u8 decode [256]; // char => index
		106	unsigned int size;
		107
		108	charmap (const char *cmap);
		109	};
		110
		111	charmap::charmap (const char *cmap)
		112	{
		113	char *enc = encode;
		114	u8 *dec = decode;
		115
		116	memset (enc, (char) 0, 256);
		117	memset (dec, (char)INVALID, 256);
		118
		119	for (size = 0; cmap [size]; size++)
		120	{
		121	enc [size] = cmap [size];
		122	dec [(u8)enc [size]] = size;
		123	}
		124
		125	assert (size < 256);
		126	}
		127
		128	#define MAX_DEC_LEN 500
		129	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		130	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		131
		132	// ugly. minimum base is 16(!)
		133	struct basecoder
		134	{
		135	charmap cmap;
		136	unsigned int enc_len [MAX_DEC_LEN];
		137	unsigned int dec_len [MAX_ENC_LEN];
		138
		139	unsigned int encode_len (unsigned int len);
		140	unsigned int decode_len (unsigned int len);
		141
94	static int encode (char *dst, u8 *src, int len);	142	unsigned int encode (char *dst, u8 *src, unsigned int len);
95	static int decode (u8 *dst, char *src, int len);	143	unsigned int decode (u8 *dst, char *src, unsigned int len);
96		144
97	dns64 ();	145	basecoder (const char *cmap);
98	} dns64;	146	};
99		147
100	// the following sequence has been crafted to	148	basecoder::basecoder (const char *cmap)
101	// a) look somewhat random	149	: cmap (cmap)
102	// b) the even (and odd) indices never share the same character as upper/lowercase
103	const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
104	s8 dns64::decode_chars[256];
105
106	dns64::dns64 ()
107	{	150	{
108	for (int i = 0; i < 64; i++)	151	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
109	decode_chars [encode_chars [i]] = i + 1;	152	{
110	}	153	u8 src [MAX_DEC_LEN];
		154	u8 dst [MAX_ENC_LEN];
111		155
112	int dns64::encode (char *dst, u8 *src, int len)	156	memset (src, 255, len);
		157
		158	mp_limb_t m [MAX_LIMBS];
		159	mp_size_t n;
		160
		161	n = mpn_set_str (m, src, len, 256);
		162	n = mpn_get_str (dst, this->cmap.size, m, n);
		163
		164	for (int i = 0; !dst [i]; ++i)
		165	n--;
		166
		167	enc_len [len] = n;
		168	dec_len [n] = len;
		169	}
		170	}
		171
		172	unsigned int basecoder::encode_len (unsigned int len)
113	{	173	{
114	// slow, but easy to debug	174	return enc_len [len];
115	char *beg = dst;	175	}
116	unsigned int accum, bits = 0;	176
		177	unsigned int basecoder::decode_len (unsigned int len)
		178	{
		179	while (len && !dec_len [len])
		180	--len;
		181
		182	return dec_len [len];
		183	}
		184
		185	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		186	{
		187	if (!len || len > MAX_DEC_LEN)
		188	return 0;
		189
		190	int elen = encode_len (len);
		191
		192	mp_limb_t m [MAX_LIMBS];
		193	mp_size_t n;
		194
		195	u8 dst_ [MAX_ENC_LEN];
		196
		197	n = mpn_set_str (m, src, len, 256);
		198	n = mpn_get_str (dst_, cmap.size, m, n);
		199
		200	int plen = elen; // for padding
		201
		202	while (n < plen)
		203	{
		204	*dst++ = cmap.encode [0];
		205	plen--;
		206	}
		207
		208	for (unsigned int i = n - plen; i < n; ++i)
		209	*dst++ = cmap.encode [dst_ [i]];
		210
		211	return elen;
		212	}
		213
		214	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		215	{
		216	if (!len || len > MAX_ENC_LEN)
		217	return 0;
		218
		219	u8 src_ [MAX_ENC_LEN];
		220	unsigned int elen = 0;
117		221
118	while (len--)	222	while (len--)
119	{	223	{
120	accum <<= 8;	224	u8 val = cmap.decode [(u8)*src++];
121	accum |= *src++;
122	bits += 8;
123		225
124	while (bits >= 6)	226	if (val != charmap::INVALID)
125	{	227	src_ [elen++] = val;
126	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	228	}
127	bits -= 6;	229
128	}	230	int dlen = decode_len (elen);
		231
		232	mp_limb_t m [MAX_LIMBS];
		233	mp_size_t n;
		234
		235	u8 dst_ [MAX_DEC_LEN];
		236
		237	n = mpn_set_str (m, src_, elen, cmap.size);
		238	n = mpn_get_str (dst_, 256, m, n);
		239
		240	if (n < dlen)
129	}	241	{
		242	memset (dst, 0, dlen - n);
		243	memcpy (dst + dlen - n, dst_, n);
		244	}
		245	else
		246	memcpy (dst, dst_ + n - dlen, dlen);
130		247
131	if (bits)	248	return dlen;
132	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
133
134	return dst - beg;
135	}	249	}
136		250
137	int dns64::decode (u8 *dst, char *src, int len)	251	#if 0
138	{	252	struct test { test (); } test;
139	// slow, but easy to debug
140	u8 *beg = dst;
141	unsigned int accum, bits = 0;
142		253
143	while (len--)	254	test::test ()
		255	{
		256	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		257
		258	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		259	static char enc[200];
		260	static u8 dec[200];
		261
		262	for (int i = 1; i < 20; i++)
144	{	263	{
145	s8 chr = decode_chars [(u8)*src++];	264	int elen = cdc.encode (enc, in, i);
		265	int dlen = cdc.decode (dec, enc, elen);
146		266
147	if (!chr)	267	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
148	continue;
149
150	accum <<= 6;
151	accum |= chr - 1;
152	bits += 6;
153
154	while (bits >= 8)
155	{
156	*dst++ = accum >> (bits - 8);
157	bits -= 8;
158	}
159	}	268	}
		269	abort ();
		270	}
		271	#endif
160		272
161	return dst - beg;	273	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		274	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		275	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		276	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		277	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		278
		279	/////////////////////////////////////////////////////////////////////////////
		280
		281	#define HDRSIZE 6
		282
		283	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		284	{
		285	seqno &= SEQNO_MASK;
		286
		287	u8 hdr[3] = {
		288	clientid,
		289	(seqno >> 8) | (retry << 6),
		290	seqno,
		291	};
		292
		293	assert (clientid < 256);
		294
		295	cdc26.encode (data, hdr, 3);
		296	}
		297
		298	inline void decode_header (char *data, int &clientid, int &seqno)
		299	{
		300	u8 hdr[3];
		301
		302	cdc26.decode (hdr, data, HDRSIZE);
		303
		304	clientid = hdr[0];
		305	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
162	}	306	}
163		307
164	/////////////////////////////////////////////////////////////////////////////	308	/////////////////////////////////////////////////////////////////////////////
165		309
166	struct byte_stream	310	struct byte_stream
…		…
195	}	339	}
196		340
197	void byte_stream::remove (int count)	341	void byte_stream::remove (int count)
198	{	342	{
199	if (count > fill)	343	if (count > fill)
200	abort ();	344	assert (count <= fill);
201		345
202	memmove (data, data + count, fill -= count);	346	memmove (data, data + count, fill -= count);
203	}	347	}
204		348
205	bool byte_stream::put (u8 *data, unsigned int datalen)	349	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
218	return false;	362	return false;
219		363
220	data [fill++] = pkt->len >> 8;	364	data [fill++] = pkt->len >> 8;
221	data [fill++] = pkt->len;	365	data [fill++] = pkt->len;
222		366
223	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	367	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
224		368
225	return true;	369	return true;
226	}	370	}
227		371
228	vpn_packet *byte_stream::get ()	372	vpn_packet *byte_stream::get ()
229	{	373	{
		374	unsigned int len;
		375
		376	for (;;)
		377	{
230	int len = (data [0] << 8) | data [1];	378	len = (data [0] << 8) | data [1];
231		379
232	if (len > MAXSIZE && fill >= 2)	380	if (len <= MAXSIZE || fill < 2)
233	abort (); // TODO handle this gracefully, connection reset	381	break;
234		382
		383	// TODO: handle this better than skipping, e.g. by reset
		384	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		385	remove (1);
		386	}
		387
235	if (fill < len + 2)	388	if (fill < len + 2)
236	return 0;	389	return 0;
237		390
238	vpn_packet *pkt = new vpn_packet;	391	vpn_packet *pkt = new vpn_packet;
239		392
240	pkt->len = len;	393	pkt->len = len;
241	memcpy (&((*pkt)[0]), data + 2, len);	394	memcpy (pkt->at (0), data + 2, len);
242	remove (len + 2);	395	remove (len + 2);
243		396
244	return pkt;	397	return pkt;
245	}	398	}
246		399
247	/////////////////////////////////////////////////////////////////////////////	400	/////////////////////////////////////////////////////////////////////////////
248		401
249	#define FLAG_QUERY ( 0 << 15)	402	#define FLAG_QUERY ( 0 << 15)
250	#define FLAG_RESPONSE ( 1 << 15)	403	#define FLAG_RESPONSE ( 1 << 15)
251	#define FLAG_OP_MASK (15 << 14)	404	#define FLAG_OP_MASK (15 << 11)
252	#define FLAG_OP_QUERY ( 0 << 11)	405	#define FLAG_OP_QUERY ( 0 << 11)
253	#define FLAG_AA ( 1 << 10)	406	#define FLAG_AA ( 1 << 10)
254	#define FLAG_TC ( 1 << 9)	407	#define FLAG_TC ( 1 << 9)
255	#define FLAG_RD ( 1 << 8)	408	#define FLAG_RD ( 1 << 8)
256	#define FLAG_RA ( 1 << 7)	409	#define FLAG_RA ( 1 << 7)
…		…
263	#define FLAG_RCODE_REFUSED ( 5 << 0)	416	#define FLAG_RCODE_REFUSED ( 5 << 0)
264		417
265	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	418	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
266	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)	419	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
267		420
		421	struct dns_cfg
		422	{
		423	static int next_uid;
		424
		425	u8 id1, id2, id3, id4;
		426
		427	u8 version;
		428	u8 flags;
		429	u8 rrtype;
		430	u8 def_ttl;
		431
		432	u16 client;
		433	u16 uid; // to make request unique
		434
		435	u16 max_size;
		436	u8 seq_cdc;
		437	u8 req_cdc;
		438
		439	u8 rep_cdc;
		440	u8 delay; // time in 0.01s units that the server may delay replying packets
		441	u8 r3, r4;
		442
		443	u8 r5, r6, r7, r8;
		444
		445	void reset (int clientid);
		446	bool valid ();
		447	};
		448
		449	int dns_cfg::next_uid;
		450
		451	void dns_cfg::reset (int clientid)
		452	{
		453	id1 = 'G';
		454	id2 = 'V';
		455	id3 = 'P';
		456	id4 = 'E';
		457
		458	version = 1;
		459
		460	rrtype = RR_TYPE_TXT;
		461	flags = 0;
		462	def_ttl = 0;
		463	seq_cdc = 26;
		464	req_cdc = 62;
		465	rep_cdc = 0;
		466	max_size = htons (MAX_PKT_SIZE);
		467	client = htons (clientid);
		468	uid = next_uid++;
		469	delay = 0;
		470
		471	r3 = r4 = 0;
		472	r4 = r5 = r6 = r7 = 0;
		473	}
		474
		475	bool dns_cfg::valid ()
		476	{
		477	// although the protocol itself allows for some configurability,
		478	// only the following encoding/decoding settings are implemented.
		479	return id1 == 'G'
		480	&& id2 == 'V'
		481	&& id3 == 'P'
		482	&& id4 == 'E'
		483	&& seq_cdc == 26
		484	&& req_cdc == 62
		485	&& rep_cdc == 0
		486	&& version == 1;
		487	}
		488
268	struct dns_packet : net_packet	489	struct dns_packet : net_packet
269	{	490	{
270	u16 id;	491	u16 id;
271	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	492	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
272	u16 qdcount, ancount, nscount, arcount;	493	u16 qdcount, ancount, nscount, arcount;
273		494
274	u8 data[MAXSIZE - 6 * 2];	495	u8 data [MAXSIZE - 6 * 2];
275		496
276	int decode_label (char *data, int size, int &offs);	497	int decode_label (char *data, int size, int &offs);
277	};	498	};
278		499
279	int dns_packet::decode_label (char *data, int size, int &offs)	500	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
310	return data - orig;	531	return data - orig;
311	}	532	}
312		533
313	/////////////////////////////////////////////////////////////////////////////	534	/////////////////////////////////////////////////////////////////////////////
314		535
315	struct dns_req
316	{
317	dns_packet *pkt;
318	tstamp next;
319	int retry;
320	connection *conn;
321	int seqno;
322
323	dns_req (connection *c);
324	void gen_stream_req (int seqno, byte_stream *stream);
325	};
326
327	static u16 dns_id = 12098; // TODO: should be per-vpn	536	static u16 dns_id = 0; // TODO: should be per-vpn
328		537
329	static u16 next_id ()	538	static u16 next_id ()
330	{	539	{
		540	if (!dns_id)
		541	dns_id = time (0);
		542
331	// the simplest lsfr with periodicity 65535 i could find	543	// the simplest lsfr with periodicity 65535 i could find
332	dns_id = (dns_id << 1)	544	dns_id = (dns_id << 1)
333	| (((dns_id >> 1)	545	| (((dns_id >> 1)
334	^ (dns_id >> 2)	546	^ (dns_id >> 2)
335	^ (dns_id >> 4)	547	^ (dns_id >> 4)
336	^ (dns_id >> 15)) & 1);	548	^ (dns_id >> 15)) & 1);
337		549
338	return dns_id;	550	return dns_id;
339	}	551	}
340		552
341	dns_req::dns_req (connection *c)	553	struct dns_rcv;
342	: conn (c)	554	struct dns_snd;
		555
		556	struct dns_connection
343	{	557	{
344	next = 0;	558	connection *c;
		559	struct vpn *vpn;
		560
		561	dns_cfg cfg;
		562
		563	bool established;
		564
		565	tstamp last_received;
		566	tstamp last_sent;
		567	double min_latency;
		568	double poll_interval, send_interval;
		569
		570	vector<dns_rcv *> rcvpq;
		571
		572	byte_stream rcvdq; int rcvseq; int repseq;
		573	byte_stream snddq; int sndseq;
		574
		575	inline void time_cb (ev::timer &w, int revents); ev::timer tw;
		576	void receive_rep (dns_rcv *r);
		577
		578	dns_connection (connection *c);
		579	~dns_connection ();
		580	};
		581
		582	struct dns_snd
		583	{
		584	dns_packet *pkt;
		585	tstamp timeout, sent;
		586	int retry;
		587	struct dns_connection *dns;
		588	int seqno;
		589	bool stdhdr;
		590
		591	void gen_stream_req (int seqno, byte_stream &stream);
		592	void gen_syn_req ();
		593
		594	dns_snd (dns_connection *dns);
		595	~dns_snd ();
		596	};
		597
		598	dns_snd::dns_snd (dns_connection *dns)
		599	: dns (dns)
		600	{
		601	timeout = 0;
345	retry = 0;	602	retry = 0;
		603	seqno = 0;
		604	sent = ev_now ();
		605	stdhdr = false;
346		606
347	pkt = new dns_packet;	607	pkt = new dns_packet;
348		608
349	pkt->id = next_id ();	609	pkt->id = next_id ();
350	}	610	}
351		611
		612	dns_snd::~dns_snd ()
		613	{
		614	delete pkt;
		615	}
		616
		617	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		618	{
		619	// add tunnel domain
		620	for (;;)
		621	{
		622	const char *end = strchr (domain, '.');
		623
		624	if (!end)
		625	end = domain + strlen (domain);
		626
		627	int len = end - domain;
		628
		629	pkt [offs++] = len;
		630	memcpy (pkt.at (offs), domain, len);
		631	offs += len;
		632
		633	if (!*end)
		634	break;
		635
		636	domain = end + 1;
		637	}
		638	}
		639
352	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	640	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
353	{	641	{
		642	stdhdr = true;
354	this->seqno = seqno;	643	this->seqno = seqno;
		644
		645	timeout = ev_now () + INITIAL_TIMEOUT;
355		646
356	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	647	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
357	pkt->qdcount = htons (1);	648	pkt->qdcount = htons (1);
358		649
359	int offs = 6*2;	650	int offs = 6*2;
360	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	651	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
361	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,	652	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
362	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra	653	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
363		654
364	u8 data[256]; //TODO
365
366	data[0] = THISNODE->id; //TODO
367	data[1] = seqno >> 7; //TODO
368	data[2] = seqno << 1; //TODO
369
370	int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
371
372	if (datalen > stream->size ())
373	datalen = stream->size ();
374
375	char enc[256], *encp = enc;	655	char enc[256], *encp = enc;
376		656	encode_header (enc, THISNODE->id, seqno);
377	memcpy (data + 3, stream->begin (), datalen);	657
378	int enclen = dns64::encode (enc, data, datalen + 3);	658	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		659
		660	if (datalen > stream.size ())
		661	datalen = stream.size ();
		662
		663	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
379	stream->remove (datalen);	664	stream.remove (datalen);
380		665
381	while (enclen)	666	while (enclen)
382	{	667	{
383	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	668	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
384		669
…		…
389	encp += lbllen;	674	encp += lbllen;
390		675
391	enclen -= lbllen;	676	enclen -= lbllen;
392	}	677	}
393		678
394	const char *suffix = THISNODE->domain;	679	append_domain (*pkt, offs, dns->c->conf->domain);
395
396	// add tunnel domain
397	for (;;)
398	{
399	const char *end = strchr (suffix, '.');
400
401	if (!end)
402	end = suffix + strlen (suffix);
403
404	int len = end - suffix;
405
406	(*pkt)[offs++] = len;
407	memcpy (&((*pkt)[offs]), suffix, len);
408	offs += len;
409
410	if (!*end)
411	break;
412
413	suffix = end + 1;
414	}
415		680
416	(*pkt)[offs++] = 0;	681	(*pkt)[offs++] = 0;
417	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	682	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		683	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		684
		685	pkt->len = offs;
		686	}
		687
		688	void dns_snd::gen_syn_req ()
		689	{
		690	timeout = ev_now () + INITIAL_SYN_TIMEOUT;
		691
		692	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		693	pkt->qdcount = htons (1);
		694
		695	int offs = 6 * 2;
		696
		697	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		698
		699	assert (elen <= MAX_LBL_SIZE);
		700
		701	(*pkt)[offs] = elen;
		702	offs += elen + 1;
		703	append_domain (*pkt, offs, dns->c->conf->domain);
		704
		705	(*pkt)[offs++] = 0;
		706	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
418	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	707	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
419		708
420	pkt->len = offs;	709	pkt->len = offs;
421	}	710	}
422		711
…		…
441	{	730	{
442	delete pkt;	731	delete pkt;
443	}	732	}
444		733
445	/////////////////////////////////////////////////////////////////////////////	734	/////////////////////////////////////////////////////////////////////////////
446		735
447	struct dns_cfg	736	dns_connection::dns_connection (connection *c)
		737	: c (c)
		738	, rcvdq (MAX_BACKLOG * 2)
		739	, snddq (MAX_BACKLOG)
448	{	740	{
449	u8 id1, id2, id3;	741	tw.set<dns_connection, &dns_connection::time_cb> (this);
450	u8 def_ttl;
451	u8 unused1;
452	u16 max_size;
453	u8 flags1, flags2;
454	};
455		742
		743	vpn = c->vpn;
		744
		745	established = false;
		746
		747	rcvseq = repseq = sndseq = 0;
		748
		749	last_sent = last_received = 0;
		750	poll_interval = 0.5; // starting here
		751	send_interval = 0.5; // starting rate
		752	min_latency = INITIAL_TIMEOUT;
		753	}
		754
		755	dns_connection::~dns_connection ()
		756	{
		757	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		758	i != rcvpq.end ();
		759	++i)
		760	delete *i;
		761	}
		762
456	void connection::dnsv4_receive_rep (struct dns_rcv *r)	763	void dns_connection::receive_rep (dns_rcv *r)
457	{	764	{
		765	if (r->datalen)
		766	{
		767	last_received = ev_now ();
		768	tw ();
		769
		770	poll_interval = send_interval;
		771	}
		772	else
		773	{
		774	poll_interval *= 1.5;
		775
		776	if (poll_interval > MAX_POLL_INTERVAL)
		777	poll_interval = MAX_POLL_INTERVAL;
		778	}
		779
458	dns_rcvpq.push_back (r);	780	rcvpq.push_back (r);
459		781
460	redo:	782	redo:
461		783
		784	// find next packet
462	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	785	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
463	i != dns_rcvpq.end ();
464	++i)
465	if (dns_rcvseq == (*i)->seqno)	786	if (SEQNO_EQ (rcvseq, (*i)->seqno))
466	{	787	{
		788	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		789	// enter the packet into our input stream
467	dns_rcv *r = *i;	790	r = *i;
468		791
		792	// remove the oldest packet, look forward, as it's oldest first
		793	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		794	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		795	{
		796	//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
		797	delete *j;
		798	rcvpq.erase (j);
		799	break;
		800	}
		801
469	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	802	rcvseq = (rcvseq + 1) & SEQNO_MASK;
470		803
471	if (!dns_snddq && !dns_rcvdq)	804	if (!rcvdq.put (r->data, r->datalen))
472	{	805	{
473	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	806	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
474	dns_snddq = new byte_stream (MAX_BACKLOG);	807	abort (); // MUST never overflow, can be caused by data corruption, TODO
475
476	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
477	}	808	}
478		809
479	if (!dns_rcvdq->put (r->data, r->datalen))
480	abort (); // MUST never overflow, can be caused by data corruption, TODO
481
482	while (vpn_packet *pkt = dns_rcvdq->get ())	810	while (vpn_packet *pkt = rcvdq.get ())
483	{	811	{
484	sockinfo si;	812	sockinfo si;
485	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	813	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
486		814
487	vpn->recv_vpn_packet (pkt, si);	815	vpn->recv_vpn_packet (pkt, si);
		816
		817	delete pkt;
488	}	818	}
489	}	819
490	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	820	// check for further packets
491	{
492	//D
493	//abort();
494	printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
495	dns_rcvpq.erase (i);
496	goto redo;	821	goto redo;
497	}	822	}
498	}	823	}
499		824
500	dns_packet *	825	void
501	vpn::dnsv4_server (dns_packet *pkt)	826	vpn::dnsv4_server (dns_packet &pkt)
502	{	827	{
503	u16 flags = ntohs (pkt->flags);	828	u16 flags = ntohs (pkt.flags);
504		829
505	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
506	int offs = 6 * 2; // skip header	830	int offs = 6 * 2; // skip header
507		831
508	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	832	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
509		833
510	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	834	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
511	&& pkt->qdcount == htons (1))	835	&& pkt.qdcount == htons (1))
512	{	836	{
513	char qname[MAXSIZE];	837	char qname [MAXSIZE];
514	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	838	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
515		839
516	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	840	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
517	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	841	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
518		842
519	pkt->qdcount = htons (1);	843	pkt.qdcount = htons (1);
520	pkt->ancount = 0;	844	pkt.ancount = 0;
521	pkt->nscount = 0; // should be self, as other nameservers reply like this	845	pkt.nscount = 0; // should be self, as other nameservers reply like this
522	pkt->arcount = 0; // a record for self, as other nameservers reply like this	846	pkt.arcount = 0; // a record for self, as other nameservers reply like this
523		847
524	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	848	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
525		849
526	int dlen = strlen (THISNODE->domain);	850	int dlen = strlen (THISNODE->domain);
527		851
528	if (qclass == RR_CLASS_IN	852	if (qclass == RR_CLASS_IN
529	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
530	&& qlen > dlen + 1	853	&& qlen > dlen + 1
531	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	854	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
532	{	855	{
533	// correct class, domain: parse	856	// now generate reply
534	u8 data[MAXSIZE];	857	pkt.ancount = htons (1); // one answer RR
535	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	858	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
536		859
537	int client = data[0];	860	if ((qtype == RR_TYPE_ANY
538	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	861	|| qtype == RR_TYPE_TXT
539		862	|| qtype == RR_TYPE_NULL)
540	if (0 < client && client <= conns.size ())	863	&& qlen > dlen + 1 + HDRSIZE)
541	{	864	{
		865	// correct class, domain: parse
		866	int client, seqno;
		867	decode_header (qname, client, seqno);
		868
		869	u8 data[MAXSIZE];
		870	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		871
		872	if (0 < client && client <= conns.size ())
		873	{
542	connection *c = conns [client - 1];	874	connection *c = conns [client - 1];
		875	dns_connection *dns = c->dns;
		876	dns_rcv *rcv;
543		877
544	redo:	878	if (dns)
545
546	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
547	i != c->dns_rcvpq.end ();
548	++i)	879	{
		880	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
549	if ((*i)->seqno == seqno)	881	if (SEQNO_EQ ((*i)->seqno, seqno))
		882	{
		883	// already seen that request: simply reply with the cached reply
		884	dns_rcv *r = *i;
		885
		886	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		887
		888	// refresh header & id, as the retry count could have changed
		889	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		890	r->pkt->id = pkt.id;
		891
		892	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		893
		894	goto duplicate_request;
		895	}
		896
		897	// new packet, queue
		898	rcv = new dns_rcv (seqno, data, datalen);
		899	dns->receive_rep (rcv);
		900	}
		901
550	{	902	{
551	// already seen that request: simply reply with the cached reply	903	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
552	dns_rcv *r = *i;
553		904
554	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	905	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		906	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		907	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		908	pkt [offs++] = 0; pkt [offs++] = 0;
		909	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
555		910
		911	int rdlen_offs = offs += 2;
		912
		913	if (dns)
		914	{
		915	int dlen = ntohs (dns->cfg.max_size) - offs;
		916
		917	// bind doesn't compress well, so reduce further by one label length
		918	dlen -= qlen;
		919
		920	// only put data into in-order sequence packets, if
		921	// we receive out-of-order packets we generate empty
		922	// replies
		923	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		924	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		925	{
		926	dns->repseq = seqno;
		927
		928	while (dlen > 1 && !dns->snddq.empty ())
		929	{
		930	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		931
		932	if (txtlen > dns->snddq.size ())
		933	txtlen = dns->snddq.size ();
		934
		935	pkt[offs++] = txtlen;
		936	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		937	offs += txtlen;
		938	dns->snddq.remove (txtlen);
		939
		940	dlen -= txtlen + 1;
		941	}
		942	}
		943
		944	// avoid completely empty TXT rdata
		945	if (offs == rdlen_offs)
		946	pkt[offs++] = 0;
		947
		948	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		949	}
		950	else
		951	{
		952	// send RST
		953	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		954	pkt [offs++] = CMD_IP_RST;
		955	}
		956
		957	int rdlen = offs - rdlen_offs;
		958
		959	pkt [rdlen_offs - 2] = rdlen >> 8;
		960	pkt [rdlen_offs - 1] = rdlen;
		961
		962	if (dns)
		963	{
		964	// now update dns_rcv copy
556	offs = r->pkt->len;	965	rcv->pkt->len = offs;
557	memcpy (pkt->at (0), r->pkt->at (0), offs);	966	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
558	goto duplicate_request;	967	}
559	}	968	}
560		969
561	// new packet, queue	970	duplicate_request: ;
562	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	971	}
563	c->dnsv4_receive_rep (rcv);	972	else
564
565	// now generate reply
566	pkt->ancount = htons (1); // one answer RR
567	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	973	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		974	}
		975	else if (qtype == RR_TYPE_A
		976	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		977	{
		978	dns_cfg cfg;
		979	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		980	int client = ntohs (cfg.client);
568		981
569	(*pkt) [offs++] = 0xc0;
570	(*pkt) [offs++] = 6 * 2; // same as in query section	982	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
571		983
572	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	984	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
573	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	985	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
574
575	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	986	pkt [offs++] = 0; pkt [offs++] = 0;
576	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	987	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		988	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
577		989
578	int dlen = MAX_PKT_SIZE - offs - 2;	990	slog (L_INFO, _("DNS: client %d connects"), client);
579		991
580	// bind doesn't compress well, so reduce further by one label length	992	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
581	dlen -= qlen;	993	pkt [offs++] = CMD_IP_REJ;
582		994
583	int rdlen_offs = offs += 2;	995	if (0 < client && client <= conns.size ())
584
585	while (c->dns_snddq
586	&& !c->dns_snddq->empty ()
587	&& dlen > 1)
588	{	996	{
589	int txtlen = dlen <= 255 ? dlen - 1 : 255;	997	connection *c = conns [client - 1];
590		998
591	if (txtlen > c->dns_snddq->size ())	999	if (cfg.valid ())
592	txtlen = c->dns_snddq->size ();	1000	{
		1001	pkt [offs - 1] = CMD_IP_SYN;
593		1002
594	(*pkt)[offs++] = txtlen;	1003	delete c->dns;
595	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	1004	c->dns = new dns_connection (c);
596	offs += txtlen;	1005	c->dns->cfg = cfg;
597	c->dns_snddq->remove (txtlen);	1006	}
598
599	dlen -= txtlen + 1;
600	}	1007	}
601
602	// avoid empty TXT rdata
603	if (offs == rdlen_offs)
604	(*pkt)[offs++] = 0;
605
606	int rdlen = offs - rdlen_offs;
607
608	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
609	(*pkt) [rdlen_offs - 1] = rdlen;
610
611	// now update dns_rcv copy
612	rcv->pkt->len = offs;
613	memcpy (rcv->pkt->at (0), pkt->at (0), offs);
614
615	duplicate_request: ;
616	}	1008	}
617	else
618	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
619	}	1009	}
620		1010
621	pkt->len = offs;	1011	pkt.len = offs;
622	}	1012	}
623
624	return pkt;
625	}	1013	}
626		1014
627	void	1015	void
628	vpn::dnsv4_client (dns_packet *pkt)	1016	vpn::dnsv4_client (dns_packet &pkt)
629	{	1017	{
630	u16 flags = ntohs (pkt->flags);	1018	u16 flags = ntohs (pkt.flags);
631	int offs = 6 * 2; // skip header	1019	int offs = 6 * 2; // skip header
632		1020
633	pkt->qdcount = ntohs (pkt->qdcount);	1021	pkt.qdcount = ntohs (pkt.qdcount);
634	pkt->ancount = ntohs (pkt->ancount);	1022	pkt.ancount = ntohs (pkt.ancount);
635		1023
636	// go through our request list and find the corresponding request	1024	// go through our request list and find the corresponding request
637	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1025	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
638	i != dns_sndpq.end ();	1026	i != dns_sndpq.end ();
639	++i)	1027	++i)
640	if ((*i)->pkt->id == pkt->id)	1028	if ((*i)->pkt->id == pkt.id)
641	{	1029	{
		1030	dns_connection *dns = (*i)->dns;
642	connection *c = (*i)->conn;	1031	connection *c = dns->c;
643	int seqno = (*i)->seqno;	1032	int seqno = (*i)->seqno;
644	u8 data[MAXSIZE], *datap = data;	1033	u8 data[MAXSIZE], *datap = data;
		1034	//printf ("rcv pkt %x\n", seqno);//D
		1035
		1036	if ((*i)->retry)
		1037	{
		1038	dns->send_interval *= 1.01;
		1039	if (dns->send_interval > MAX_SEND_INTERVAL)
		1040	dns->send_interval = MAX_SEND_INTERVAL;
		1041	}
		1042	else
		1043	{
		1044	#if 0
		1045	dns->send_interval *= 0.999;
		1046	#endif
		1047	// the latency surely puts an upper bound on
		1048	// the minimum send interval
		1049	double latency = ev_now () - (*i)->sent;
		1050
		1051	if (latency < dns->min_latency)
		1052	dns->min_latency = latency;
		1053
		1054	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1055	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1056
		1057	if (dns->send_interval < conf.dns_send_interval)
		1058	dns->send_interval = conf.dns_send_interval;
		1059	}
645		1060
646	delete *i;	1061	delete *i;
647	dns_sndpq.erase (i);	1062	dns_sndpq.erase (i);
648		1063
649	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1064	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
650	{	1065	{
651	char qname[MAXSIZE];	1066	char qname[MAXSIZE];
652		1067
653	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1068	while (pkt.qdcount-- && offs < MAXSIZE - 4)
654	{	1069	{
655	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1070	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
656	offs += 4; // skip qtype, qclass	1071	offs += 4; // skip qtype, qclass
657	}	1072	}
658		1073
659	while (pkt->ancount-- && offs < MAXSIZE - 10)	1074	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
660	{	1075	{
661	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1076	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
662		1077
663	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1078	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
664	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1079	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
665	u32 ttl = (*pkt) [offs++] << 24;	1080	u32 ttl = pkt [offs++] << 24;
666	ttl |= (*pkt) [offs++] << 16;	1081	ttl |= pkt [offs++] << 16;
667	ttl |= (*pkt) [offs++] << 8;	1082	ttl |= pkt [offs++] << 8;
668	ttl |= (*pkt) [offs++];	1083	ttl |= pkt [offs++];
669
670	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1084	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
671		1085
672	if (rdlen <= MAXSIZE - offs)	1086	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
673	{	1087	{
674	// decode bytes, finally	1088	if (rdlen <= MAXSIZE - offs)
675
676	while (rdlen)
677	{	1089	{
		1090	// decode bytes, finally
		1091
		1092	while (rdlen)
		1093	{
678	int txtlen = (*pkt) [offs++];	1094	int txtlen = pkt [offs++];
679		1095
680	assert (txtlen + offs < MAXSIZE - 1);	1096	assert (txtlen + offs < MAXSIZE - 1);
681		1097
682	memcpy (datap, pkt->at (offs), txtlen);	1098	memcpy (datap, pkt.at (offs), txtlen);
683	datap += txtlen; offs += txtlen;	1099	datap += txtlen; offs += txtlen;
684		1100
685	rdlen -= txtlen + 1;	1101	rdlen -= txtlen + 1;
		1102	}
686	}	1103	}
687
688	}	1104	}
		1105	else if (qtype == RR_TYPE_A)
		1106	{
		1107	u8 ip [4];
689		1108
		1109	ip [0] = pkt [offs++];
		1110	ip [1] = pkt [offs++];
		1111	ip [2] = pkt [offs++];
		1112	ip [3] = pkt [offs++];
		1113
		1114	if (ip [0] == CMD_IP_1
		1115	&& ip [1] == CMD_IP_2
		1116	&& ip [2] == CMD_IP_3)
		1117	{
		1118	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1119
		1120	if (ip [3] == CMD_IP_RST)
		1121	{
		1122	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1123
		1124	delete dns; c->dns = 0;
		1125
		1126	return;
		1127	}
		1128	else if (ip [3] == CMD_IP_SYN)
		1129	{
		1130	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1131	dns->established = true;
		1132	}
		1133	else if (ip [3] == CMD_IP_REJ)
		1134	{
		1135	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1136	abort ();
		1137	}
		1138	else
		1139	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1140	}
		1141	else
		1142	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1143	ip [0], ip [1], ip [2], ip [3]);
		1144
		1145	return;
		1146	}
		1147
		1148	int client, rseqno;
		1149	decode_header (qname, client, rseqno);
		1150
		1151	if (client != THISNODE->id)
		1152	{
		1153	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1154	datap = 0;
		1155	}
		1156	else if (rseqno != seqno)
		1157	{
		1158	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1159	datap = 0;
		1160	}
690	}	1161	}
691	}	1162	}
692		1163
693	// todo: pkt now used	1164	// todo: pkt now used
		1165	if (datap)
694	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1166	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
695		1167
696	break;	1168	break;
697	}	1169	}
698
699	delete pkt;
700	}	1170	}
701		1171
702	void	1172	void
703	vpn::dnsv4_ev (io_watcher &w, short revents)	1173	vpn::dnsv4_ev (ev::io &w, int revents)
704	{	1174	{
705	if (revents & EVENT_READ)	1175	if (revents & EV_READ)
706	{	1176	{
707	dns_packet *pkt = new dns_packet;	1177	dns_packet *pkt = new dns_packet;
708	struct sockaddr_in sa;	1178	struct sockaddr_in sa;
709	socklen_t sa_len = sizeof (sa);	1179	socklen_t sa_len = sizeof (sa);
710		1180
711	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1181	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
712		1182
713	if (pkt->len > 0)	1183	if (pkt->len > 0)
714	{	1184	{
715	if (pkt->flags & htons (FLAG_TC))	1185	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1186	dnsv4_client (*pkt);
		1187	else
716	{	1188	{
717	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1189	dnsv4_server (*pkt);
718	//TODO connection reset	1190	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
719	}	1191	}
720		1192
721	if (THISNODE->dns_port)	1193	delete pkt;
722	{
723	pkt = dnsv4_server (pkt);
724	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
725	}
726	else
727	dnsv4_client (pkt);
728	}	1194	}
729	}	1195	}
730	}	1196	}
731		1197
732	bool	1198	bool
733	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1199	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
734	{	1200	{
735	// never initialized	1201	int client = ntohl (si.host);
736	if (!dns_snddq && !dns_rcvdq)
737	{
738	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
739	dns_snddq = new byte_stream (MAX_BACKLOG);
740		1202
741	//dns_rcvseq = dns_sndseq = 0;	1203	assert (0 < client && client <= conns.size ());
742		1204
743	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1205	connection *c = conns [client - 1];
744	}	1206
		1207	if (!c->dns)
		1208	c->dns = new dns_connection (c);
745		1209
746	if (!dns_snddq->put (pkt))	1210	if (c->dns->snddq.put (pkt))
747	return false;	1211	c->dns->tw ();
748		1212
749	// start timer if neccessary	1213	// always return true even if the buffer overflows
750	if (!THISNODE->dns_port && !dnsv4_tw.active)
751	dnsv4_cb (dnsv4_tw);
752
753	return true;	1214	return true;
754	}	1215	}
755		1216
756	void	1217	void
757	connection::dnsv4_cb (time_watcher &w)	1218	connection::dnsv4_reset_connection ()
758	{	1219	{
		1220	//delete dns; dns = 0; //TODO
		1221	}
		1222
		1223	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1224
		1225	void
		1226	dns_connection::time_cb (ev::timer &w, int revents)
		1227	{
		1228	// servers have to be polled
		1229	if (THISNODE->dns_port)
		1230	return;
		1231
759	// check for timeouts and (re)transmit	1232	// check for timeouts and (re)transmit
760	tstamp next = NOW + 60;	1233	tstamp next = ev::now () + poll_interval;
761	dns_req *send = 0;	1234	dns_snd *send = 0;
762		1235
763	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1236	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
764	i != vpn->dns_sndpq.end ();	1237	i != vpn->dns_sndpq.end ();
765	++i)	1238	++i)
766	{	1239	{
767	dns_req *r = *i;	1240	dns_snd *r = *i;
768		1241
769	if (r->next <= NOW)	1242	if (r->timeout <= ev_now ())
770	{	1243	{
771	if (!send)	1244	if (!send)
772	{	1245	{
773	send = r;	1246	send = r;
774		1247
775	if (r->retry)//D
776	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
777	r->retry++;	1248	r->retry++;
778	r->next = NOW + r->retry;	1249	r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
		1250	//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
		1251
		1252	// the following code changes the query section a bit, forcing
		1253	// the forwarder to generate a new request
		1254	if (r->stdhdr)
		1255	encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
779	}	1256	}
780	}	1257	}
781		1258	else
782	if (r->next < next)	1259	NEXT (r->timeout);
783	next = r->next;
784	}	1260	}
785		1261
786	if (!send	1262	if (!send)
787	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
788	{	1263	{
		1264	// generate a new packet, if wise
		1265
		1266	if (!established)
		1267	{
		1268	if (vpn->dns_sndpq.empty ())
		1269	{
789	send = new dns_req (this);	1270	send = new dns_snd (this);
		1271
		1272	cfg.reset (THISNODE->id);
		1273	send->gen_syn_req ();
		1274	}
		1275	}
		1276	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1277	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1278	{
		1279	if (last_sent + send_interval <= ev_now ())
		1280	{
		1281	//printf ("sending data request etc.\n"); //D
		1282	if (!snddq.empty () || last_received + 1. > ev_now ())
		1283	{
		1284	poll_interval = send_interval;
		1285	NEXT (ev_now () + send_interval);
		1286	}
		1287
		1288	send = new dns_snd (this);
790	send->gen_stream_req (dns_sndseq, dns_snddq);	1289	send->gen_stream_req (sndseq, snddq);
		1290	send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
		1291	//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
		1292
		1293	sndseq = (sndseq + 1) & SEQNO_MASK;
		1294	}
		1295	else
		1296	NEXT (last_sent + send_interval);
		1297	}
		1298
		1299	if (send)
791	vpn->dns_sndpq.push_back (send);	1300	vpn->dns_sndpq.push_back (send);
792
793	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
794	}	1301	}
795
796	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
797		1302
798	if (send)	1303	if (send)
799	{	1304	{
800	dns_packet *pkt = send->pkt;	1305	last_sent = ev_now ();
801		1306	sendto (vpn->dnsv4_fd,
802	next = min_next;	1307	send->pkt->at (0), send->pkt->len, 0,
803		1308	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
804	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
805	}	1309	}
806	else if (next < min_next)
807	next = min_next;
808		1310
809	w.start (next);	1311	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1312	poll_interval, send_interval, next - ev_now (),
		1313	vpn->dns_sndpq.size (), snddq.size (),
		1314	rcvpq.size ());
		1315
		1316	// TODO: no idea when this happens, but when next < ev_now (), we have a problem
		1317	// doesn't seem to happen anymore
		1318	if (next < ev_now () + 0.001)
		1319	next = ev_now () + 0.1;
		1320
		1321	w.start (next - ev_now ());
810	}	1322	}
811		1323
812	#endif	1324	#endif
813		1325

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