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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 1.47 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) 2003-2004 Marc Lehmann <pcg@goof.com>	3	Copyright (C) 2003-2008 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 it
6	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
7	the Free Software Foundation; either version 2 of the License, or	9	Free Software Foundation; either version 3 of the License, or (at your
8	(at your option) any later version.	10	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, but
11	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	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 GNU General
13	GNU General Public License for more details.	15	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 along
16	along with this program; if not, write to the Free Software	18	with this program; if not, see <http://www.gnu.org/licenses/>.
17	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.
18	*/	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.
19		35
20	#include "config.h"	36	#include "config.h"
21		37
22	#if ENABLE_DNS	38	#if ENABLE_DNS
23		39
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	40	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	41	// it's a hack, use only in emergency situations please.
26		42
27	#include <cstring>	43	#include <cstring>
		44	#include <cassert>
28		45
29	#include <sys/types.h>	46	#include <sys/types.h>
30	#include <sys/socket.h>	47	#include <sys/socket.h>
31	#include <sys/wait.h>	48	#include <sys/wait.h>
32	#include <sys/uio.h>	49	#include <sys/uio.h>
…		…
35	#include <unistd.h>	52	#include <unistd.h>
36	#include <fcntl.h>	53	#include <fcntl.h>
37		54
38	#include <map>	55	#include <map>
39		56
		57	#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
		58	#include <gmp.h>
		59
40	#include "netcompat.h"	60	#include "netcompat.h"
41		61
42	#include "vpn.h"	62	#include "vpn.h"
43		63
44	#define MIN_RETRY 1.	64	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	65	#define ACTIVITY_INTERVAL 5.
46		66
47	#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
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	72	#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	73	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		74
52	#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
53	// 240 leaves about 4 bytes of server reply data	76	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	77	// every request byte less give room for two reply bytes
55		78
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	79	#define SEQNO_MASK 0x3fff
60		80	#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		81
77	#define MAX_LBL_SIZE 63	82	#define MAX_LBL_SIZE 63
78	#define MAX_PKT_SIZE 512	83	#define MAX_PKT_SIZE 512
79		84
		85	#define RR_TYPE_A 1
		86	#define RR_TYPE_NULL 10
80	#define RR_TYPE_TXT 16	87	#define RR_TYPE_TXT 16
81	#define RR_TYPE_ANY 255	88	#define RR_TYPE_ANY 255
		89
82	#define RR_CLASS_IN 1	90	#define RR_CLASS_IN 1
83		91
84	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	92	#define CMD_IP_1 207
85	struct dns64	93	#define CMD_IP_2 46
86	{	94	#define CMD_IP_3 236
87	static const char encode_chars[64 + 1];	95	#define CMD_IP_RST 29
88	static s8 decode_chars[256];	96	#define CMD_IP_SYN 113
		97	#define CMD_IP_REJ 32
89		98
90	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	99	// works for cmaps up to 255 (not 256!)
91	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
92	static int encode (char *dst, u8 *src, int len);	142	unsigned int encode (char *dst, u8 *src, unsigned int len);
93	static int decode (u8 *dst, char *src, int len);	143	unsigned int decode (u8 *dst, char *src, unsigned int len);
94		144
95	dns64 ();	145	basecoder (const char *cmap);
96	} dns64;	146	};
97		147
98	// the following sequence has been crafted to	148	basecoder::basecoder (const char *cmap)
99	// a) look somewhat random	149	: 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	{	150	{
106	for (int i = 0; i < 64; i++)	151	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
107	decode_chars [encode_chars [i]] = i + 1;	152	{
108	}	153	u8 src [MAX_DEC_LEN];
		154	u8 dst [MAX_ENC_LEN];
109		155
110	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)
111	{	173	{
112	// slow, but easy to debug	174	return enc_len [len];
113	char *beg = dst;	175	}
114	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;
115		221
116	while (len--)	222	while (len--)
117	{	223	{
118	accum <<= 8;	224	u8 val = cmap.decode [(u8)*src++];
119	accum |= *src++;
120	bits += 8;
121		225
122	while (bits >= 6)	226	if (val != charmap::INVALID)
123	{	227	src_ [elen++] = val;
124	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	228	}
125	bits -= 6;	229
126	}	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)
127	}	241	{
		242	memset (dst, 0, dlen - n);
		243	memcpy (dst + dlen - n, dst_, n);
		244	}
		245	else
		246	memcpy (dst, dst_ + n - dlen, dlen);
128		247
129	if (bits)	248	return dlen;
130	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
131
132	return dst - beg;
133	}	249	}
134		250
135	int dns64::decode (u8 *dst, char *src, int len)	251	#if 0
136	{	252	struct test { test (); } test;
137	// slow, but easy to debug
138	u8 *beg = dst;
139	unsigned int accum, bits = 0;
140		253
141	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++)
142	{	263	{
143	s8 chr = decode_chars [(u8)*src++];	264	int elen = cdc.encode (enc, in, i);
		265	int dlen = cdc.decode (dec, enc, elen);
144		266
145	if (!chr)	267	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	}	268	}
		269	abort ();
		270	}
		271	#endif
158		272
159	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;
160	}	306	}
161		307
162	/////////////////////////////////////////////////////////////////////////////	308	/////////////////////////////////////////////////////////////////////////////
163		309
164	struct byte_stream	310	struct byte_stream
…		…
193	}	339	}
194		340
195	void byte_stream::remove (int count)	341	void byte_stream::remove (int count)
196	{	342	{
197	if (count > fill)	343	if (count > fill)
198	abort ();	344	assert (count <= fill);
199		345
200	memmove (data, data + count, fill -= count);	346	memmove (data, data + count, fill -= count);
201	}	347	}
202		348
203	bool byte_stream::put (u8 *data, unsigned int datalen)	349	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
216	return false;	362	return false;
217		363
218	data [fill++] = pkt->len >> 8;	364	data [fill++] = pkt->len >> 8;
219	data [fill++] = pkt->len;	365	data [fill++] = pkt->len;
220		366
221	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	367	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
222		368
223	return true;	369	return true;
224	}	370	}
225		371
226	vpn_packet *byte_stream::get ()	372	vpn_packet *byte_stream::get ()
227	{	373	{
		374	unsigned int len;
		375
		376	for (;;)
		377	{
228	int len = (data [0] << 8) | data [1];	378	len = (data [0] << 8) | data [1];
229		379
230	if (len > MAXSIZE && fill >= 2)	380	if (len <= MAXSIZE || fill < 2)
231	abort (); // TODO handle this gracefully, connection reset	381	break;
232		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
233	if (fill < len + 2)	388	if (fill < len + 2)
234	return 0;	389	return 0;
235		390
236	vpn_packet *pkt = new vpn_packet;	391	vpn_packet *pkt = new vpn_packet;
237		392
238	pkt->len = len;	393	pkt->len = len;
239	memcpy (&((*pkt)[0]), data + 2, len);	394	memcpy (pkt->at (0), data + 2, len);
240	remove (len + 2);	395	remove (len + 2);
241		396
242	return pkt;	397	return pkt;
243	}	398	}
244		399
245	/////////////////////////////////////////////////////////////////////////////	400	/////////////////////////////////////////////////////////////////////////////
246		401
247	#define FLAG_QUERY ( 0 << 15)	402	#define FLAG_QUERY ( 0 << 15)
248	#define FLAG_RESPONSE ( 1 << 15)	403	#define FLAG_RESPONSE ( 1 << 15)
249	#define FLAG_OP_MASK (15 << 14)	404	#define FLAG_OP_MASK (15 << 11)
250	#define FLAG_OP_QUERY ( 0 << 11)	405	#define FLAG_OP_QUERY ( 0 << 11)
251	#define FLAG_AA ( 1 << 10)	406	#define FLAG_AA ( 1 << 10)
252	#define FLAG_TC ( 1 << 9)	407	#define FLAG_TC ( 1 << 9)
253	#define FLAG_RD ( 1 << 8)	408	#define FLAG_RD ( 1 << 8)
254	#define FLAG_RA ( 1 << 7)	409	#define FLAG_RA ( 1 << 7)
…		…
261	#define FLAG_RCODE_REFUSED ( 5 << 0)	416	#define FLAG_RCODE_REFUSED ( 5 << 0)
262		417
263	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	418	#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)	419	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
265		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
266	struct dns_packet : net_packet	489	struct dns_packet : net_packet
267	{	490	{
268	u16 id;	491	u16 id;
269	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
270	u16 qdcount, ancount, nscount, arcount;	493	u16 qdcount, ancount, nscount, arcount;
271		494
272	u8 data[MAXSIZE - 6 * 2];	495	u8 data [MAXSIZE - 6 * 2];
273		496
274	int decode_label (char *data, int size, int &offs);	497	int decode_label (char *data, int size, int &offs);
275	};	498	};
276		499
277	int dns_packet::decode_label (char *data, int size, int &offs)	500	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
308	return data - orig;	531	return data - orig;
309	}	532	}
310		533
311	/////////////////////////////////////////////////////////////////////////////	534	/////////////////////////////////////////////////////////////////////////////
312		535
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	536	static u16 dns_id = 0; // TODO: should be per-vpn
326		537
327	static u16 next_id ()	538	static u16 next_id ()
328	{	539	{
		540	if (!dns_id)
		541	dns_id = time (0);
		542
329	// the simplest lsfr with periodicity 65535 i could find	543	// the simplest lsfr with periodicity 65535 i could find
330	dns_id = (dns_id << 1)	544	dns_id = (dns_id << 1)
331	| (((dns_id >> 1)	545	| (((dns_id >> 1)
332	^ (dns_id >> 2)	546	^ (dns_id >> 2)
333	^ (dns_id >> 4)	547	^ (dns_id >> 4)
334	^ (dns_id >> 15)) & 1);	548	^ (dns_id >> 15)) & 1);
335		549
336	return dns_id;	550	return dns_id;
337	}	551	}
338		552
339	dns_req::dns_req (connection *c)	553	struct dns_rcv;
340	: conn (c)	554	struct dns_snd;
		555
		556	struct dns_connection
341	{	557	{
342	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;
343	retry = 0;	602	retry = 0;
		603	seqno = 0;
		604	sent = ev_now ();
		605	stdhdr = false;
344		606
345	pkt = new dns_packet;	607	pkt = new dns_packet;
346		608
347	pkt->id = next_id ();	609	pkt->id = next_id ();
348	}	610	}
349		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
350	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	640	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
351	{	641	{
		642	stdhdr = true;
352	this->seqno = seqno;	643	this->seqno = seqno;
		644
		645	timeout = ev_now () + INITIAL_TIMEOUT;
353		646
354	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	647	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
355	pkt->qdcount = htons (1);	648	pkt->qdcount = htons (1);
356		649
357	int offs = 6*2;	650	int offs = 6*2;
358	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	651	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,	652	// 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	653	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
361		654
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;	655	char enc[256], *encp = enc;
374		656	encode_header (enc, THISNODE->id, seqno);
375	memcpy (data + 3, stream->begin (), datalen);	657
376	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;
377	stream->remove (datalen);	664	stream.remove (datalen);
378		665
379	while (enclen)	666	while (enclen)
380	{	667	{
381	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	668	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
382		669
…		…
387	encp += lbllen;	674	encp += lbllen;
388		675
389	enclen -= lbllen;	676	enclen -= lbllen;
390	}	677	}
391		678
392	const char *suffix = THISNODE->domain;	679	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		680
414	(*pkt)[offs++] = 0;	681	(*pkt)[offs++] = 0;
415	(*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;
416	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	707	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
417		708
418	pkt->len = offs;	709	pkt->len = offs;
419	}	710	}
420		711
…		…
439	{	730	{
440	delete pkt;	731	delete pkt;
441	}	732	}
442		733
443	/////////////////////////////////////////////////////////////////////////////	734	/////////////////////////////////////////////////////////////////////////////
444		735
445	struct dns_cfg	736	dns_connection::dns_connection (connection *c)
		737	: c (c)
		738	, rcvdq (MAX_BACKLOG * 2)
		739	, snddq (MAX_BACKLOG)
446	{	740	{
447	u8 id1, id2, id3;	741	tw.set<dns_connection, &dns_connection::time_cb> (this);
448	u8 def_ttl;
449	u8 unused1;
450	u16 max_size;
451	u8 flags1, flags2;
452	};
453		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
454	void connection::dnsv4_receive_rep (struct dns_rcv *r)	763	void dns_connection::receive_rep (dns_rcv *r)
455	{	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
456	dns_rcvpq.push_back (r);	780	rcvpq.push_back (r);
457		781
458	redo:	782	redo:
459		783
		784	// find next packet
460	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	785	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461	i != dns_rcvpq.end ();
462	++i)
463	if (dns_rcvseq == (*i)->seqno)	786	if (SEQNO_EQ (rcvseq, (*i)->seqno))
464	{	787	{
		788	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		789	// enter the packet into our input stream
465	dns_rcv *r = *i;	790	r = *i;
466		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
467	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	802	rcvseq = (rcvseq + 1) & SEQNO_MASK;
468		803
469	if (!dns_snddq && !dns_rcvdq)	804	if (!rcvdq.put (r->data, r->datalen))
470	{	805	{
471	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	806	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472	dns_snddq = new byte_stream (MAX_BACKLOG);	807	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	}	808	}
476		809
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 ())	810	while (vpn_packet *pkt = rcvdq.get ())
481	{	811	{
482	sockinfo si;	812	sockinfo si;
483	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	813	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
484		814
485	vpn->recv_vpn_packet (pkt, si);	815	vpn->recv_vpn_packet (pkt, si);
		816
		817	delete pkt;
486	}	818	}
487	}	819
488	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	820	// 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;	821	goto redo;
495	}	822	}
496	}	823	}
497		824
498	dns_packet *	825	void
499	vpn::dnsv4_server (dns_packet *pkt)	826	vpn::dnsv4_server (dns_packet &pkt)
500	{	827	{
501	u16 flags = ntohs (pkt->flags);	828	u16 flags = ntohs (pkt.flags);
502		829
503	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504	int offs = 6 * 2; // skip header	830	int offs = 6 * 2; // skip header
505		831
506	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	832	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507		833
508	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	834	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509	&& pkt->qdcount == htons (1))	835	&& pkt.qdcount == htons (1))
510	{	836	{
511	char qname[MAXSIZE];	837	char qname [MAXSIZE];
512	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	838	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513		839
514	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	840	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	841	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516		842
517	pkt->qdcount = htons (1);	843	pkt.qdcount = htons (1);
518	pkt->ancount = 0;	844	pkt.ancount = 0;
519	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
520	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
521		847
522	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	848	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523		849
524	int dlen = strlen (THISNODE->domain);	850	int dlen = strlen (THISNODE->domain);
525		851
526	if (qclass == RR_CLASS_IN	852	if (qclass == RR_CLASS_IN
527	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528	&& qlen > dlen + 1	853	&& qlen > dlen + 1
529	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	854	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
530	{	855	{
531	// correct class, domain: parse	856	// now generate reply
532	u8 data[MAXSIZE];	857	pkt.ancount = htons (1); // one answer RR
533	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	858	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534		859
535	int client = data[0];	860	if ((qtype == RR_TYPE_ANY
536	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	861	|| qtype == RR_TYPE_TXT
537		862	|| qtype == RR_TYPE_NULL)
538	if (0 < client && client <= conns.size ())	863	&& qlen > dlen + 1 + HDRSIZE)
539	{	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	{
540	connection *c = conns [client - 1];	874	connection *c = conns [client - 1];
		875	dns_connection *dns = c->dns;
		876	dns_rcv *rcv;
541		877
542	redo:	878	if (dns)
543
544	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545	i != c->dns_rcvpq.end ();
546	++i)	879	{
		880	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547	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
548	{	902	{
549	// already seen that request: simply reply with the cached reply	903	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550	dns_rcv *r = *i;
551		904
552	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
553		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
554	offs = r->pkt->len;	965	rcv->pkt->len = offs;
555	memcpy (pkt->at (0), r->pkt->at (0), offs);	966	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556	goto duplicate_request;	967	}
557	}	968	}
558		969
559	// new packet, queue	970	duplicate_request: ;
560	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	971	}
561	c->dnsv4_receive_rep (rcv);	972	else
562
563	// now generate reply
564	pkt->ancount = htons (1); // one answer RR
565	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);
566		981
567	(*pkt) [offs++] = 0xc0;
568	(*pkt) [offs++] = 6 * 2; // same as in query section	982	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569		983
570	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	984	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	985	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	986	pkt [offs++] = 0; pkt [offs++] = 0;
574	(*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
575		989
576	int dlen = MAX_PKT_SIZE - offs - 2;	990	slog (L_INFO, _("DNS: client %d connects"), client);
577		991
578	// 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;
579	dlen -= qlen;	993	pkt [offs++] = CMD_IP_REJ;
580		994
581	int rdlen_offs = offs += 2;	995	if (0 < client && client <= conns.size ())
582
583	while (c->dns_snddq
584	&& !c->dns_snddq->empty ()
585	&& dlen > 1)
586	{	996	{
587	int txtlen = dlen <= 255 ? dlen - 1 : 255;	997	connection *c = conns [client - 1];
588		998
589	if (txtlen > c->dns_snddq->size ())	999	if (cfg.valid ())
590	txtlen = c->dns_snddq->size ();	1000	{
		1001	pkt [offs - 1] = CMD_IP_SYN;
591		1002
592	(*pkt)[offs++] = txtlen;	1003	delete c->dns;
593	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	1004	c->dns = new dns_connection (c);
594	offs += txtlen;	1005	c->dns->cfg = cfg;
595	c->dns_snddq->remove (txtlen);	1006	}
596
597	dlen -= txtlen + 1;
598	}	1007	}
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	}	1008	}
615	else
616	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617	}	1009	}
618		1010
619	pkt->len = offs;	1011	pkt.len = offs;
620	}	1012	}
621
622	return pkt;
623	}	1013	}
624		1014
625	void	1015	void
626	vpn::dnsv4_client (dns_packet *pkt)	1016	vpn::dnsv4_client (dns_packet &pkt)
627	{	1017	{
628	u16 flags = ntohs (pkt->flags);	1018	u16 flags = ntohs (pkt.flags);
629	int offs = 6 * 2; // skip header	1019	int offs = 6 * 2; // skip header
630		1020
631	pkt->qdcount = ntohs (pkt->qdcount);	1021	pkt.qdcount = ntohs (pkt.qdcount);
632	pkt->ancount = ntohs (pkt->ancount);	1022	pkt.ancount = ntohs (pkt.ancount);
633		1023
634	// go through our request list and find the corresponding request	1024	// go through our request list and find the corresponding request
635	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1025	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636	i != dns_sndpq.end ();	1026	i != dns_sndpq.end ();
637	++i)	1027	++i)
638	if ((*i)->pkt->id == pkt->id)	1028	if ((*i)->pkt->id == pkt.id)
639	{	1029	{
		1030	dns_connection *dns = (*i)->dns;
640	connection *c = (*i)->conn;	1031	connection *c = dns->c;
641	int seqno = (*i)->seqno;	1032	int seqno = (*i)->seqno;
642	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	}
643		1060
644	delete *i;	1061	delete *i;
645	dns_sndpq.erase (i);	1062	dns_sndpq.erase (i);
646		1063
647	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1064	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648	{	1065	{
649	char qname[MAXSIZE];	1066	char qname[MAXSIZE];
650		1067
651	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1068	while (pkt.qdcount-- && offs < MAXSIZE - 4)
652	{	1069	{
653	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1070	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654	offs += 4; // skip qtype, qclass	1071	offs += 4; // skip qtype, qclass
655	}	1072	}
656		1073
657	while (pkt->ancount-- && offs < MAXSIZE - 10)	1074	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658	{	1075	{
659	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1076	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660		1077
661	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1078	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1079	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663	u32 ttl = (*pkt) [offs++] << 24;	1080	u32 ttl = pkt [offs++] << 24;
664	ttl |= (*pkt) [offs++] << 16;	1081	ttl |= pkt [offs++] << 16;
665	ttl |= (*pkt) [offs++] << 8;	1082	ttl |= pkt [offs++] << 8;
666	ttl |= (*pkt) [offs++];	1083	ttl |= pkt [offs++];
667
668	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1084	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669		1085
670	if (rdlen <= MAXSIZE - offs)	1086	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671	{	1087	{
672	// decode bytes, finally	1088	if (rdlen <= MAXSIZE - offs)
673
674	while (rdlen)
675	{	1089	{
		1090	// decode bytes, finally
		1091
		1092	while (rdlen)
		1093	{
676	int txtlen = (*pkt) [offs++];	1094	int txtlen = pkt [offs++];
677		1095
678	assert (txtlen + offs < MAXSIZE - 1);	1096	assert (txtlen + offs < MAXSIZE - 1);
679		1097
680	memcpy (datap, pkt->at (offs), txtlen);	1098	memcpy (datap, pkt.at (offs), txtlen);
681	datap += txtlen; offs += txtlen;	1099	datap += txtlen; offs += txtlen;
682		1100
683	rdlen -= txtlen + 1;	1101	rdlen -= txtlen + 1;
		1102	}
684	}	1103	}
685
686	}	1104	}
		1105	else if (qtype == RR_TYPE_A)
		1106	{
		1107	u8 ip [4];
687		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	}
688	}	1161	}
689	}	1162	}
690		1163
691	// todo: pkt now used	1164	// todo: pkt now used
		1165	if (datap)
692	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1166	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693		1167
694	break;	1168	break;
695	}	1169	}
696
697	delete pkt;
698	}	1170	}
699		1171
700	void	1172	void
701	vpn::dnsv4_ev (io_watcher &w, short revents)	1173	vpn::dnsv4_ev (ev::io &w, int revents)
702	{	1174	{
703	if (revents & EVENT_READ)	1175	if (revents & EV_READ)
704	{	1176	{
705	dns_packet *pkt = new dns_packet;	1177	dns_packet *pkt = new dns_packet;
706	struct sockaddr_in sa;	1178	struct sockaddr_in sa;
707	socklen_t sa_len = sizeof (sa);	1179	socklen_t sa_len = sizeof (sa);
708		1180
709	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);
710		1182
711	if (pkt->len > 0)	1183	if (pkt->len > 0)
712	{	1184	{
713	if (pkt->flags & htons (FLAG_TC))	1185	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1186	dnsv4_client (*pkt);
		1187	else
714	{	1188	{
715	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1189	dnsv4_server (*pkt);
716	//TODO connection reset	1190	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}	1191	}
718		1192
719	if (THISNODE->dns_port)	1193	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	}	1194	}
727	}	1195	}
728	}	1196	}
729		1197
730	bool	1198	bool
731	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)
732	{	1200	{
733	// never initialized	1201	int client = ntohl (si.host);
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		1202
739	//dns_rcvseq = dns_sndseq = 0;	1203	assert (0 < client && client <= conns.size ());
740		1204
741	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1205	connection *c = conns [client - 1];
742	}	1206
		1207	if (!c->dns)
		1208	c->dns = new dns_connection (c);
743		1209
744	if (!dns_snddq->put (pkt))	1210	if (c->dns->snddq.put (pkt))
745	return false;	1211	c->dns->tw ();
746		1212
747	// start timer if neccessary	1213	// always return true even if the buffer overflows
748	if (!THISNODE->dns_port && !dnsv4_tw.active)
749	dnsv4_cb (dnsv4_tw);
750
751	return true;	1214	return true;
752	}	1215	}
753		1216
754	void	1217	void
755	connection::dnsv4_cb (time_watcher &w)	1218	connection::dnsv4_reset_connection ()
756	{	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
757	// check for timeouts and (re)transmit	1232	// check for timeouts and (re)transmit
758	tstamp next = NOW + 60;	1233	tstamp next = ev::now () + poll_interval;
759	dns_req *send = 0;	1234	dns_snd *send = 0;
760		1235
761	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1236	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762	i != vpn->dns_sndpq.end ();	1237	i != vpn->dns_sndpq.end ();
763	++i)	1238	++i)
764	{	1239	{
765	dns_req *r = *i;	1240	dns_snd *r = *i;
766		1241
767	if (r->next <= NOW)	1242	if (r->timeout <= ev_now ())
768	{	1243	{
769	if (!send)	1244	if (!send)
770	{	1245	{
771	send = r;	1246	send = r;
772		1247
773	if (r->retry)//D
774	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775	r->retry++;	1248	r->retry++;
776	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);
777	}	1256	}
778	}	1257	}
779		1258	else
780	if (r->next < next)	1259	NEXT (r->timeout);
781	next = r->next;
782	}	1260	}
783		1261
784	if (!send	1262	if (!send)
785	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
786	{	1263	{
		1264	// generate a new packet, if wise
		1265
		1266	if (!established)
		1267	{
		1268	if (vpn->dns_sndpq.empty ())
		1269	{
787	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);
788	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)
789	vpn->dns_sndpq.push_back (send);	1300	vpn->dns_sndpq.push_back (send);
790
791	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792	}	1301	}
793
794	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795		1302
796	if (send)	1303	if (send)
797	{	1304	{
798	dns_packet *pkt = send->pkt;	1305	last_sent = ev_now ();
799		1306	sendto (vpn->dnsv4_fd,
800	next = min_next;	1307	send->pkt->at (0), send->pkt->len, 0,
801		1308	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
802	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
803	}	1309	}
804	else if (next < min_next)
805	next = min_next;
806		1310
807	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 ());
808	}	1322	}
809		1323
810	#endif	1324	#endif
811		1325

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