[ViewVC] Diff of: cvs/gvpe/src/vpn

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 UTC vs.
Revision 1.46 by pcg, Thu Dec 6 00:35:29 2007 UTC

…		…
1	/*	1	/*
2	vpn_dns.C -- handle the dns tunnel part of the protocol.	2	vpn_dns.C -- handle the dns tunnel part of the protocol.
3	Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com>	3	Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de>
4		4
		5	This file is part of GVPE.
		6
5	This program is free software; you can redistribute it and/or modify	7	GVPE is free software; you can redistribute it and/or modify
6	it under the terms of the GNU General Public License as published by	8	it under the terms of the GNU General Public License as published by
7	the Free Software Foundation; either version 2 of the License, or	9	the Free Software Foundation; either version 2 of the License, or
8	(at your option) any later version.	10	(at your option) any later version.
9		11
10	This program is distributed in the hope that it will be useful,	12	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.	15	GNU General Public License for more details.
14		16
15	You should have received a copy of the GNU General Public License	17	You should have received a copy of the GNU General Public License
16	along with this program; if not, write to the Free Software	18	along with gvpe; if not, write to the Free Software
17	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA	19	Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18	*/	20	*/
		21
		22	// TODO: EDNS0 option to increase dns mtu?
		23	// TODO: re-write dns packet parsing/creation using a safe mem-buffer
		24	// to ensure no buffer overflows or similar problems.
19		25
20	#include "config.h"	26	#include "config.h"
21		27
22	#if ENABLE_DNS	28	#if ENABLE_DNS
23		29
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	30	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	31	// it's a hack, use only in emergency situations please.
26		32
27	#include <cstring>	33	#include <cstring>
		34	#include <cassert>
28		35
29	#include <sys/types.h>	36	#include <sys/types.h>
30	#include <sys/socket.h>	37	#include <sys/socket.h>
31	#include <sys/wait.h>	38	#include <sys/wait.h>
32	#include <sys/uio.h>	39	#include <sys/uio.h>
35	#include <unistd.h>	42	#include <unistd.h>
36	#include <fcntl.h>	43	#include <fcntl.h>
37		44
38	#include <map>	45	#include <map>
39		46
		47	#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
		48	#include <gmp.h>
		49
40	#include "netcompat.h"	50	#include "netcompat.h"
41		51
42	#include "vpn.h"	52	#include "vpn.h"
43		53
44	#define MIN_RETRY 1.	54	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	55	#define ACTIVITY_INTERVAL 5.
46		56
47	#define MAX_OUTSTANDING 10 // max. outstanding requests	57	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		58	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
		59
		60	#define MAX_SEND_INTERVAL 2. // optimistic?
		61
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	62	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
49	#define MAX_RATE 1 // requests/s
50	#define MAX_BACKLOG (10*1024) // size of protocol backlog	63	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		64
52	/*	65	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
		66	// 240 leaves about 4 bytes of server reply data
		67	// every request byte less give room for two reply bytes
53		68
54	protocol, in shorthand :)	69	#define SEQNO_MASK 0x3fff
55		70	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
56	client -> server <req> ANY?
57	server -> client <req> TXT <rep>
58
59	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
60	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
61
62	if <client-id> is zero, the connection will be configured:
63
64	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
65
66	*/
67		71
68	#define MAX_LBL_SIZE 63	72	#define MAX_LBL_SIZE 63
69	#define MAX_PKT_SIZE 512	73	#define MAX_PKT_SIZE 512
70		74
		75	#define RR_TYPE_A 1
		76	#define RR_TYPE_NULL 10
71	#define RR_TYPE_TXT 16	77	#define RR_TYPE_TXT 16
72	#define RR_TYPE_ANY 255	78	#define RR_TYPE_ANY 255
		79
73	#define RR_CLASS_IN 1	80	#define RR_CLASS_IN 1
74		81
75	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	82	#define CMD_IP_1 207
76	struct dns64	83	#define CMD_IP_2 46
77	{	84	#define CMD_IP_3 236
78	static const char encode_chars[64 + 1];	85	#define CMD_IP_RST 29
79	static s8 decode_chars[256];	86	#define CMD_IP_SYN 113
		87	#define CMD_IP_REJ 32
80		88
81	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	89	// works for cmaps up to 255 (not 256!)
82	static int decode_len (int bytes) { return (bytes * 6) / 8; }	90	struct charmap
		91	{
		92	enum { INVALID = (u8)255 };
		93
		94	char encode [256]; // index => char
		95	u8 decode [256]; // char => index
		96	unsigned int size;
		97
		98	charmap (const char *cmap);
		99	};
		100
		101	charmap::charmap (const char *cmap)
		102	{
		103	char *enc = encode;
		104	u8 *dec = decode;
		105
		106	memset (enc, (char) 0, 256);
		107	memset (dec, (char)INVALID, 256);
		108
		109	for (size = 0; cmap [size]; size++)
		110	{
		111	enc [size] = cmap [size];
		112	dec [(u8)enc [size]] = size;
		113	}
		114
		115	assert (size < 256);
		116	}
		117
		118	#define MAX_DEC_LEN 500
		119	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		120	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		121
		122	// ugly. minimum base is 16(!)
		123	struct basecoder
		124	{
		125	charmap cmap;
		126	unsigned int enc_len [MAX_DEC_LEN];
		127	unsigned int dec_len [MAX_ENC_LEN];
		128
		129	unsigned int encode_len (unsigned int len);
		130	unsigned int decode_len (unsigned int len);
		131
83	static int encode (char dst, u8 src, int len);	132	unsigned int encode (char dst, u8 src, unsigned int len);
84	static int decode (u8 dst, char src, int len);	133	unsigned int decode (u8 dst, char src, unsigned int len);
85		134
86	dns64 ();	135	basecoder (const char *cmap);
87	} dns64;	136	};
88		137
89	const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";	138	basecoder::basecoder (const char *cmap)
90	s8 dns64::decode_chars[256];	139	: cmap (cmap)
91
92	dns64::dns64 ()
93	{	140	{
94	for (int i = 0; i < 64; i++)	141	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95	decode_chars [encode_chars [i]] = i + 1;	142	{
96	}	143	u8 src [MAX_DEC_LEN];
		144	u8 dst [MAX_ENC_LEN];
97		145
98	int dns64::encode (char dst, u8 src, int len)	146	memset (src, 255, len);
		147
		148	mp_limb_t m [MAX_LIMBS];
		149	mp_size_t n;
		150
		151	n = mpn_set_str (m, src, len, 256);
		152	n = mpn_get_str (dst, this->cmap.size, m, n);
		153
		154	for (int i = 0; !dst [i]; ++i)
		155	n--;
		156
		157	enc_len [len] = n;
		158	dec_len [n] = len;
		159	}
		160	}
		161
		162	unsigned int basecoder::encode_len (unsigned int len)
99	{	163	{
100	// slow, but easy to debug	164	return enc_len [len];
101	char *beg = dst;	165	}
102	unsigned int accum, bits = 0;	166
		167	unsigned int basecoder::decode_len (unsigned int len)
		168	{
		169	while (len && !dec_len [len])
		170	--len;
		171
		172	return dec_len [len];
		173	}
		174
		175	unsigned int basecoder::encode (char dst, u8 src, unsigned int len)
		176	{
		177	if (!len \|\| len > MAX_DEC_LEN)
		178	return 0;
		179
		180	int elen = encode_len (len);
		181
		182	mp_limb_t m [MAX_LIMBS];
		183	mp_size_t n;
		184
		185	u8 dst_ [MAX_ENC_LEN];
		186
		187	n = mpn_set_str (m, src, len, 256);
		188	n = mpn_get_str (dst_, cmap.size, m, n);
		189
		190	int plen = elen; // for padding
		191
		192	while (n < plen)
		193	{
		194	*dst++ = cmap.encode [0];
		195	plen--;
		196	}
		197
		198	for (unsigned int i = n - plen; i < n; ++i)
		199	*dst++ = cmap.encode [dst_ [i]];
		200
		201	return elen;
		202	}
		203
		204	unsigned int basecoder::decode (u8 dst, char src, unsigned int len)
		205	{
		206	if (!len \|\| len > MAX_ENC_LEN)
		207	return 0;
		208
		209	u8 src_ [MAX_ENC_LEN];
		210	unsigned int elen = 0;
103		211
104	while (len--)	212	while (len--)
105	{	213	{
106	accum <<= 8;	214	u8 val = cmap.decode [(u8)*src++];
107	accum \|= *src++;
108	bits += 8;
109		215
110	while (bits >= 6)	216	if (val != charmap::INVALID)
111	{	217	src_ [elen++] = val;
112	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	218	}
113	bits -= 6;	219
114	}	220	int dlen = decode_len (elen);
		221
		222	mp_limb_t m [MAX_LIMBS];
		223	mp_size_t n;
		224
		225	u8 dst_ [MAX_DEC_LEN];
		226
		227	n = mpn_set_str (m, src_, elen, cmap.size);
		228	n = mpn_get_str (dst_, 256, m, n);
		229
		230	if (n < dlen)
115	}	231	{
		232	memset (dst, 0, dlen - n);
		233	memcpy (dst + dlen - n, dst_, n);
		234	}
		235	else
		236	memcpy (dst, dst_ + n - dlen, dlen);
116		237
117	if (bits)	238	return dlen;
118	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120	return dst - beg;
121	}	239	}
122		240
123	int dns64::decode (u8 dst, char src, int len)	241	#if 0
124	{	242	struct test { test (); } test;
125	// slow, but easy to debug
126	u8 *beg = dst;
127	unsigned int accum, bits = 0;
128		243
129	while (len--)	244	test::test ()
		245	{
		246	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		247
		248	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		249	static char enc[200];
		250	static u8 dec[200];
		251
		252	for (int i = 1; i < 20; i++)
130	{	253	{
131	s8 chr = decode_chars [(u8)*src++];	254	int elen = cdc.encode (enc, in, i);
		255	int dlen = cdc.decode (dec, enc, elen);
132		256
133	if (!chr)	257	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
134	break;
135
136	accum <<= 6;
137	accum \|= chr - 1;
138	bits += 6;
139
140	while (bits >= 8)
141	{
142	*dst++ = accum >> (bits - 8);
143	bits -= 8;
144	}
145	}	258	}
		259	abort ();
		260	}
		261	#endif
146		262
147	return dst - beg;	263	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		264	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		265	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		266	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		267	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		268
		269	/////////////////////////////////////////////////////////////////////////////
		270
		271	#define HDRSIZE 6
		272
		273	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		274	{
		275	seqno &= SEQNO_MASK;
		276
		277	u8 hdr[3] = {
		278	clientid,
		279	(seqno >> 8) \| (retry << 6),
		280	seqno,
		281	};
		282
		283	assert (clientid < 256);
		284
		285	cdc26.encode (data, hdr, 3);
		286	}
		287
		288	inline void decode_header (char *data, int &clientid, int &seqno)
		289	{
		290	u8 hdr[3];
		291
		292	cdc26.decode (hdr, data, HDRSIZE);
		293
		294	clientid = hdr[0];
		295	seqno = ((hdr[1] << 8) \| hdr[2]) & SEQNO_MASK;
148	}	296	}
149		297
150	/////////////////////////////////////////////////////////////////////////////	298	/////////////////////////////////////////////////////////////////////////////
151		299
152	struct byte_stream	300	struct byte_stream
…		…
159	~byte_stream ();	307	~byte_stream ();
160		308
161	bool empty () { return !fill; }	309	bool empty () { return !fill; }
162	int size () { return fill; }	310	int size () { return fill; }
163		311
		312	bool put (u8 *data, unsigned int datalen);
164	bool put (vpn_packet *pkt);	313	bool put (vpn_packet *pkt);
165	vpn_packet *get ();	314	vpn_packet *get ();
166		315
167	u8 *begin () { return data; }	316	u8 *begin () { return data; }
168	void remove (int count);	317	void remove (int count);
…		…
180	}	329	}
181		330
182	void byte_stream::remove (int count)	331	void byte_stream::remove (int count)
183	{	332	{
184	if (count > fill)	333	if (count > fill)
185	abort ();	334	assert (count <= fill);
186		335
187	memmove (data, data + count, fill -= count);	336	memmove (data, data + count, fill -= count);
		337	}
		338
		339	bool byte_stream::put (u8 *data, unsigned int datalen)
		340	{
		341	if (maxsize - fill < datalen)
		342	return false;
		343
		344	memcpy (this->data + fill, data, datalen); fill += datalen;
		345
		346	return true;
188	}	347	}
189		348
190	bool byte_stream::put (vpn_packet *pkt)	349	bool byte_stream::put (vpn_packet *pkt)
191	{	350	{
192	if (maxsize - fill < pkt->len + 2)	351	if (maxsize - fill < pkt->len + 2)
193	return false;	352	return false;
194		353
195	data [fill++] = pkt->len >> 8;	354	data [fill++] = pkt->len >> 8;
196	data [fill++] = pkt->len;	355	data [fill++] = pkt->len;
197		356
198	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	357	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199		358
200	return true;	359	return true;
201	}	360	}
202		361
203	vpn_packet *byte_stream::get ()	362	vpn_packet *byte_stream::get ()
204	{	363	{
		364	unsigned int len;
		365
		366	for (;;)
		367	{
205	int len = (data [0] << 8) \| data [1];	368	len = (data [0] << 8) \| data [1];
206		369
		370	if (len <= MAXSIZE \|\| fill < 2)
		371	break;
		372
		373	// TODO: handle this better than skipping, e.g. by reset
		374	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		375	remove (1);
		376	}
		377
207	if (fill < len + 2)	378	if (fill < len + 2)
208	return 0;	379	return 0;
209		380
210	vpn_packet *pkt = new vpn_packet;	381	vpn_packet *pkt = new vpn_packet;
		382
		383	pkt->len = len;
211	memcpy (&((*pkt)[0]), data + 2, len);	384	memcpy (pkt->at (0), data + 2, len);
212	remove (len + 2);	385	remove (len + 2);
213		386
214	return pkt;	387	return pkt;
215	}	388	}
216		389
217	/////////////////////////////////////////////////////////////////////////////	390	/////////////////////////////////////////////////////////////////////////////
218		391
219	#define FLAG_QUERY ( 0 << 15)	392	#define FLAG_QUERY ( 0 << 15)
220	#define FLAG_RESPONSE ( 1 << 15)	393	#define FLAG_RESPONSE ( 1 << 15)
221	#define FLAG_OP_MASK (15 << 14)	394	#define FLAG_OP_MASK (15 << 11)
222	#define FLAG_OP_QUERY ( 0 << 11)	395	#define FLAG_OP_QUERY ( 0 << 11)
223	#define FLAG_AA ( 1 << 10)	396	#define FLAG_AA ( 1 << 10)
224	#define FLAG_TC ( 1 << 9)	397	#define FLAG_TC ( 1 << 9)
225	#define FLAG_RD ( 1 << 8)	398	#define FLAG_RD ( 1 << 8)
226	#define FLAG_RA ( 1 << 7)	399	#define FLAG_RA ( 1 << 7)
		400	#define FLAG_AUTH ( 1 << 5)
227	#define FLAG_RCODE_MASK (15 << 0)	401	#define FLAG_RCODE_MASK (15 << 0)
228	#define FLAG_RCODE_OK ( 0 << 0)	402	#define FLAG_RCODE_OK ( 0 << 0)
229	#define FLAG_RCODE_FORMERR ( 1 << 0)	403	#define FLAG_RCODE_FORMERR ( 1 << 0)
230	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	404	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	405	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232	#define FLAG_RCODE_REFUSED ( 5 << 0)	406	#define FLAG_RCODE_REFUSED ( 5 << 0)
233		407
234	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)	408	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)
235	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE \| FLAG_OP_QUERY \| FLAG_AA \| FLAG_RD)	409	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE \| FLAG_OP_QUERY \| FLAG_AA \| FLAG_RD \| FLAG_RA)
		410
		411	struct dns_cfg
		412	{
		413	static int next_uid;
		414
		415	u8 id1, id2, id3, id4;
		416
		417	u8 version;
		418	u8 flags;
		419	u8 rrtype;
		420	u8 def_ttl;
		421
		422	u16 client;
		423	u16 uid; // to make request unique
		424
		425	u16 max_size;
		426	u8 seq_cdc;
		427	u8 req_cdc;
		428
		429	u8 rep_cdc;
		430	u8 delay; // time in 0.01s units that the server may delay replying packets
		431	u8 r3, r4;
		432
		433	u8 r5, r6, r7, r8;
		434
		435	void reset (int clientid);
		436	bool valid ();
		437	};
		438
		439	int dns_cfg::next_uid;
		440
		441	void dns_cfg::reset (int clientid)
		442	{
		443	id1 = 'G';
		444	id2 = 'V';
		445	id3 = 'P';
		446	id4 = 'E';
		447
		448	version = 1;
		449
		450	rrtype = RR_TYPE_TXT;
		451	flags = 0;
		452	def_ttl = 0;
		453	seq_cdc = 26;
		454	req_cdc = 62;
		455	rep_cdc = 0;
		456	max_size = htons (MAX_PKT_SIZE);
		457	client = htons (clientid);
		458	uid = next_uid++;
		459	delay = 0;
		460
		461	r3 = r4 = 0;
		462	r4 = r5 = r6 = r7 = 0;
		463	}
		464
		465	bool dns_cfg::valid ()
		466	{
		467	// although the protocol itself allows for some configurability,
		468	// only the following encoding/decoding settings are implemented.
		469	return id1 == 'G'
		470	&& id2 == 'V'
		471	&& id3 == 'P'
		472	&& id4 == 'E'
		473	&& seq_cdc == 26
		474	&& req_cdc == 62
		475	&& rep_cdc == 0
		476	&& version == 1;
		477	}
236		478
237	struct dns_packet : net_packet	479	struct dns_packet : net_packet
238	{	480	{
239	u16 id;	481	u16 id;
240	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	482	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
241	u16 qdcount, ancount, nscount, arcount;	483	u16 qdcount, ancount, nscount, arcount;
242		484
243	u8 data[MAXSIZE - 6 * 2];	485	u8 data [MAXSIZE - 6 * 2];
244		486
245	int decode_label (char *data, int size, int &offs);	487	int decode_label (char *data, int size, int &offs);
246	};	488	};
247		489
248	int dns_packet::decode_label (char *data, int size, int &offs)	490	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
279	return data - orig;	521	return data - orig;
280	}	522	}
281		523
282	/////////////////////////////////////////////////////////////////////////////	524	/////////////////////////////////////////////////////////////////////////////
283		525
		526	static u16 dns_id = 0; // TODO: should be per-vpn
		527
		528	static u16 next_id ()
		529	{
		530	if (!dns_id)
		531	dns_id = time (0);
		532
		533	// the simplest lsfr with periodicity 65535 i could find
		534	dns_id = (dns_id << 1)
		535	\| (((dns_id >> 1)
		536	^ (dns_id >> 2)
		537	^ (dns_id >> 4)
		538	^ (dns_id >> 15)) & 1);
		539
		540	return dns_id;
		541	}
		542
284	struct dns_req	543	struct dns_rcv;
		544	struct dns_snd;
		545
		546	struct dns_connection
		547	{
		548	connection *c;
		549	struct vpn *vpn;
		550
		551	dns_cfg cfg;
		552
		553	bool established;
		554
		555	tstamp last_received;
		556	tstamp last_sent;
		557	double min_latency;
		558	double poll_interval, send_interval;
		559
		560	vector<dns_rcv *> rcvpq;
		561
		562	byte_stream rcvdq; int rcvseq; int repseq;
		563	byte_stream snddq; int sndseq;
		564
		565	inline void time_cb (ev::timer &w, int revents); ev::timer tw;
		566	void receive_rep (dns_rcv *r);
		567
		568	dns_connection (connection *c);
		569	~dns_connection ();
		570	};
		571
		572	struct dns_snd
285	{	573	{
286	dns_packet *pkt;	574	dns_packet *pkt;
287	tstamp next;	575	tstamp timeout, sent;
288	int retry;	576	int retry;
289	connection *conn;	577	struct dns_connection *dns;
		578	int seqno;
		579	bool stdhdr;
290		580
291	dns_req (connection c, int seqno, byte_stream stream);	581	void gen_stream_req (int seqno, byte_stream &stream);
		582	void gen_syn_req ();
		583
		584	dns_snd (dns_connection *dns);
		585	~dns_snd ();
292	};	586	};
293		587
294	struct dns_rep	588	dns_snd::dns_snd (dns_connection *dns)
		589	: dns (dns)
295	{	590	{
296	};	591	timeout = 0;
297
298	static u16 dns_id; // TODO: should be per-vpn
299
300	dns_req::dns_req (connection c, int seqno, byte_stream stream)
301	: conn (c)
302	{
303	next = 0;
304	retry = 0;	592	retry = 0;
		593	seqno = 0;
		594	sent = ev_now ();
		595	stdhdr = false;
305		596
306	pkt = new dns_packet;	597	pkt = new dns_packet;
307		598
308	pkt->id = dns_id++;	599	pkt->id = next_id ();
309	pkt->flags = DEFAULT_CLIENT_FLAGS;	600	}
310	pkt->qdcount = htons (1);
311	pkt->ancount = 0;
312	pkt->nscount = 0;
313	pkt->arcount = 0;
314		601
315	int offs = 6*2;	602	dns_snd::~dns_snd ()
316	int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length	603	{
		604	delete pkt;
		605	}
317		606
318	u8 lbl[64]; //D	607	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
319	char enc[65];	608	{
320	int lbllen = 3;
321	lbl[0] = c->conf->id; //D
322	lbl[1] = seqno >> 8; //D
323	lbl[2] = seqno; //D
324
325	while (dlen > 0)
326	{
327	int sndlen = dlen;
328
329	if (sndlen + lbllen > dns64::decode_len (MAX_LBL_SIZE))
330	sndlen = dns64::decode_len (MAX_LBL_SIZE) - lbllen;
331
332	if (sndlen > stream->size ())
333	sndlen = stream->size ();
334
335	if (sndlen + lbllen == 0)
336	break;
337
338	memcpy (lbl + lbllen, stream->begin (), sndlen);
339	stream->remove (sndlen);
340	lbllen += sndlen;
341
342	dns64::encode (enc, lbl, lbllen);
343
344	int elen = dns64::encode_len (lbllen);
345	(*pkt)[offs++] = elen;
346	memcpy (&((*pkt)[offs]), enc, elen);
347	offs += elen;
348	dlen -= elen + 1;
349
350	lbllen = 0;
351	}
352
353	const char *suffix = THISNODE->domain;
354
355	// add tunnel domain	609	// add tunnel domain
356	for (;;)	610	for (;;)
357	{	611	{
358	const char *end = strchr (suffix, '.');	612	const char *end = strchr (domain, '.');
359		613
360	if (!end)	614	if (!end)
361	end = suffix + strlen (suffix);	615	end = domain + strlen (domain);
362		616
363	int len = end - suffix;	617	int len = end - domain;
364		618
365	(*pkt)[offs++] = len;	619	pkt [offs++] = len;
366	memcpy (&((*pkt)[offs]), suffix, len);	620	memcpy (pkt.at (offs), domain, len);
367	offs += len;	621	offs += len;
368		622
369	if (!*end)	623	if (!*end)
370	break;	624	break;
371		625
372	suffix = end + 1;	626	domain = end + 1;
		627	}
		628	}
		629
		630	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		631	{
		632	stdhdr = true;
		633	this->seqno = seqno;
		634
		635	timeout = ev_now () + INITIAL_TIMEOUT;
		636
		637	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		638	pkt->qdcount = htons (1);
		639
		640	int offs = 6*2;
		641	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
		642	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		643	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		644
		645	char enc[256], *encp = enc;
		646	encode_header (enc, THISNODE->id, seqno);
		647
		648	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		649
		650	if (datalen > stream.size ())
		651	datalen = stream.size ();
		652
		653	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		654	stream.remove (datalen);
		655
		656	while (enclen)
373	}	657	{
		658	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		659
		660	(*pkt)[offs++] = lbllen;
		661	memcpy (pkt->at (offs), encp, lbllen);
		662
		663	offs += lbllen;
		664	encp += lbllen;
		665
		666	enclen -= lbllen;
		667	}
		668
		669	append_domain (*pkt, offs, dns->c->conf->domain);
374		670
375	(*pkt)[offs++] = 0;	671	(*pkt)[offs++] = 0;
376	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;	672	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;
377	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;	673	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
378		674
379	pkt->len = offs;	675	pkt->len = offs;
		676	}
380		677
381	c->vpn->dns_sndpq.push_back (this);	678	void dns_snd::gen_syn_req ()
		679	{
		680	timeout = ev_now () + INITIAL_SYN_TIMEOUT;
		681
		682	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		683	pkt->qdcount = htons (1);
		684
		685	int offs = 6 * 2;
		686
		687	int elen = cdc26.encode ((char )pkt->at (offs + 1), (u8 )&dns->cfg, sizeof (dns_cfg));
		688
		689	assert (elen <= MAX_LBL_SIZE);
		690
		691	(*pkt)[offs] = elen;
		692	offs += elen + 1;
		693	append_domain (*pkt, offs, dns->c->conf->domain);
		694
		695	(*pkt)[offs++] = 0;
		696	(pkt)[offs++] = RR_TYPE_A >> 8; (pkt)[offs++] = RR_TYPE_A;
		697	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		698
		699	pkt->len = offs;
		700	}
		701
		702	struct dns_rcv
		703	{
		704	int seqno;
		705	dns_packet *pkt; // reply packet
		706	u8 data [MAXSIZE]; // actually part of the reply packet...
		707	int datalen;
		708
		709	dns_rcv (int seqno, u8 *data, int datalen);
		710	~dns_rcv ();
		711	};
		712
		713	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		714	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		715	{
		716	memcpy (this->data, data, datalen);
		717	}
		718
		719	dns_rcv::~dns_rcv ()
		720	{
		721	delete pkt;
382	}	722	}
383		723
384	/////////////////////////////////////////////////////////////////////////////	724	/////////////////////////////////////////////////////////////////////////////
385		725
386	struct dns_cfg	726	dns_connection::dns_connection (connection *c)
		727	: c (c)
		728	, rcvdq (MAX_BACKLOG * 2)
		729	, snddq (MAX_BACKLOG)
387	{	730	{
388	u8 id1, id2, id3;	731	tw.set<dns_connection, &dns_connection::time_cb> (this);
389	u8 def_ttl;
390	u8 unused1;
391	u16 max_size;
392	u8 flags1, flags2;
393	};
394		732
395	dns_packet *	733	vpn = c->vpn;
		734
		735	established = false;
		736
		737	rcvseq = repseq = sndseq = 0;
		738
		739	last_sent = last_received = 0;
		740	poll_interval = 0.5; // starting here
		741	send_interval = 0.5; // starting rate
		742	min_latency = INITIAL_TIMEOUT;
		743	}
		744
		745	dns_connection::~dns_connection ()
		746	{
		747	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		748	i != rcvpq.end ();
		749	++i)
		750	delete *i;
		751	}
		752
		753	void dns_connection::receive_rep (dns_rcv *r)
		754	{
		755	if (r->datalen)
		756	{
		757	last_received = ev_now ();
		758	tw ();
		759
		760	poll_interval = send_interval;
		761	}
		762	else
		763	{
		764	poll_interval *= 1.5;
		765
		766	if (poll_interval > MAX_POLL_INTERVAL)
		767	poll_interval = MAX_POLL_INTERVAL;
		768	}
		769
		770	rcvpq.push_back (r);
		771
		772	redo:
		773
		774	// find next packet
		775	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		776	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		777	{
		778	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		779	// enter the packet into our input stream
		780	r = *i;
		781
		782	// remove the oldest packet, look forward, as it's oldest first
		783	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		784	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		785	{
		786	//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
		787	delete *j;
		788	rcvpq.erase (j);
		789	break;
		790	}
		791
		792	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		793
		794	if (!rcvdq.put (r->data, r->datalen))
		795	{
		796	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		797	abort (); // MUST never overflow, can be caused by data corruption, TODO
		798	}
		799
		800	while (vpn_packet *pkt = rcvdq.get ())
		801	{
		802	sockinfo si;
		803	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
		804
		805	vpn->recv_vpn_packet (pkt, si);
		806
		807	delete pkt;
		808	}
		809
		810	// check for further packets
		811	goto redo;
		812	}
		813	}
		814
		815	void
396	vpn::dnsv4_server (dns_packet *pkt)	816	vpn::dnsv4_server (dns_packet &pkt)
397	{	817	{
398	u16 flags = ntohs (pkt->flags);	818	u16 flags = ntohs (pkt.flags);
399		819
400	//memcpy (&((rep)[0]), &((pkt)[0]), pkt->len);
401	int offs = 6 * 2; // skip header	820	int offs = 6 * 2; // skip header
402		821
403	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);	822	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
404		823
405	if (!(flags & (FLAG_RESPONSE \| FLAG_OP_MASK \| FLAG_TC))	824	if (0 == (flags & (FLAG_RESPONSE \| FLAG_OP_MASK))
406	&& pkt->qdcount == htons (1))	825	&& pkt.qdcount == htons (1))
407	{	826	{
408	char qname[MAXSIZE];	827	char qname [MAXSIZE];
409	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	828	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410		829
411	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", pkt->len,
412	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
413
414	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];	830	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
415	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];	831	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
416		832
417	pkt->qdcount = htons (1);	833	pkt.qdcount = htons (1);
418	pkt->ancount = 0;	834	pkt.ancount = 0;
419	pkt->nscount = 0; // should be self, as other nameservers reply like this	835	pkt.nscount = 0; // should be self, as other nameservers reply like this
420	pkt->arcount = 0; // a record for self, as other nameservers reply like this	836	pkt.arcount = 0; // a record for self, as other nameservers reply like this
421		837
422	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_NXDOMAIN);	838	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_SERVFAIL);
423		839
424	int dlen = strlen (THISNODE->domain);	840	int dlen = strlen (THISNODE->domain);
425		841
426	if (qclass == RR_CLASS_IN	842	if (qclass == RR_CLASS_IN
427	&& (qtype == RR_TYPE_ANY \|\| qtype == RR_TYPE_TXT)
428	&& qlen > dlen + 1	843	&& qlen > dlen + 1
429	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	844	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
430	{	845	{
431	// correct class, domain, parse
432	u8 data[MAXSIZE];
433	int datalen = dns64::decode (data, qname, qlen - dlen - 1);
434
435	for (int i = 0; i < datalen; i++)
436	printf ("%02x ", data[i]);
437	printf ("\n");
438
439
440
441
442	#if 0
443	// now generate reply	846	// now generate reply
444	rep->ancount = htons (1); // one answer RR	847	pkt.ancount = htons (1); // one answer RR
445	rep->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);	848	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);
446		849
447	(*rep) [offs++] = 0xc0;	850	if ((qtype == RR_TYPE_ANY
448	(rep) [offs++] = 6 2; // same as in query section	851	\|\| qtype == RR_TYPE_TXT
449		852	\|\| qtype == RR_TYPE_NULL)
450	(rep) [offs++] = RR_TYPE_TXT >> 8; (rep) [offs++] = RR_TYPE_TXT;	853	&& qlen > dlen + 1 + HDRSIZE)
451	(rep) [offs++] = RR_CLASS_IN >> 8; (rep) [offs++] = RR_CLASS_IN;
452
453	(rep) [offs++] = 0; (rep) [offs++] = 0;
454	(rep) [offs++] = 0; (rep) [offs++] = 0; // TTL
455
456	int dlen = MAX_PKT_SIZE - offs - 2;
457
458	printf ("we have room for %d bytes\n", dlen);
459
460	int rdlen_offs = offs += 2;
461
462	u8 txt[255];
463	txt[0] = 0;
464	txt[1] = 0;
465
466	int txtlen = 2;
467
468	while (dlen > 1)
469	{	854	{
470	int sndlen = --dlen;	855	// correct class, domain: parse
		856	int client, seqno;
		857	decode_header (qname, client, seqno);
471		858
472	if (sndlen + txtlen > 255)	859	u8 data[MAXSIZE];
473	sndlen = 255 - txtlen;	860	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
474		861
475	sndlen = 0;	862	if (0 < client && client <= conns.size ())
		863	{
		864	connection *c = conns [client - 1];
		865	dns_connection *dns = c->dns;
		866	dns_rcv *rcv;
476		867
477	(*rep)[offs++] = sndlen + txtlen;	868	if (dns)
478	memcpy (&((*rep)[offs]), txt, txtlen);	869	{
		870	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		871	if (SEQNO_EQ ((*i)->seqno, seqno))
		872	{
		873	// already seen that request: simply reply with the cached reply
		874	dns_rcv r = i;
		875
		876	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		877
		878	// refresh header & id, as the retry count could have changed
		879	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		880	r->pkt->id = pkt.id;
		881
		882	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		883
		884	goto duplicate_request;
		885	}
		886
		887	// new packet, queue
		888	rcv = new dns_rcv (seqno, data, datalen);
		889	dns->receive_rep (rcv);
		890	}
		891
		892	{
		893	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		894
		895	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		896	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		897	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		898	pkt [offs++] = 0; pkt [offs++] = 0;
		899	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		900
		901	int rdlen_offs = offs += 2;
		902
		903	if (dns)
		904	{
		905	int dlen = ntohs (dns->cfg.max_size) - offs;
		906
		907	// bind doesn't compress well, so reduce further by one label length
		908	dlen -= qlen;
		909
		910	// only put data into in-order sequence packets, if
		911	// we receive out-of-order packets we generate empty
		912	// replies
		913	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		914	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		915	{
		916	dns->repseq = seqno;
		917
		918	while (dlen > 1 && !dns->snddq.empty ())
		919	{
		920	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		921
		922	if (txtlen > dns->snddq.size ())
		923	txtlen = dns->snddq.size ();
		924
		925	pkt[offs++] = txtlen;
		926	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
479	offs += txtlen;	927	offs += txtlen;
		928	dns->snddq.remove (txtlen);
480		929
481	//if (sndlen + txtlen > dns_snddq.	930	dlen -= txtlen + 1;
		931	}
		932	}
		933
		934	// avoid completely empty TXT rdata
		935	if (offs == rdlen_offs)
		936	pkt[offs++] = 0;
		937
		938	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		939	}
		940	else
		941	{
		942	// send RST
		943	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		944	pkt [offs++] = CMD_IP_RST;
		945	}
		946
		947	int rdlen = offs - rdlen_offs;
		948
		949	pkt [rdlen_offs - 2] = rdlen >> 8;
		950	pkt [rdlen_offs - 1] = rdlen;
		951
		952	if (dns)
		953	{
		954	// now update dns_rcv copy
		955	rcv->pkt->len = offs;
		956	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		957	}
		958	}
		959
		960	duplicate_request: ;
		961	}
		962	else
		963	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
482	}	964	}
		965	else if (qtype == RR_TYPE_A
		966	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		967	{
		968	dns_cfg cfg;
		969	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		970	int client = ntohs (cfg.client);
483		971
484	int rdlen = offs - rdlen_offs;	972	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485		973
486	(*rep) [rdlen_offs - 2] = rdlen >> 8;	974	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487	(*rep) [rdlen_offs - 1] = rdlen;	975	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488	#endif	976	pkt [offs++] = 0; pkt [offs++] = 0;
		977	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		978	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		979
		980	slog (L_INFO, _("DNS: client %d connects"), client);
		981
		982	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		983	pkt [offs++] = CMD_IP_REJ;
		984
		985	if (0 < client && client <= conns.size ())
		986	{
		987	connection *c = conns [client - 1];
		988
		989	if (cfg.valid ())
		990	{
		991	pkt [offs - 1] = CMD_IP_SYN;
		992
		993	delete c->dns;
		994	c->dns = new dns_connection (c);
		995	c->dns->cfg = cfg;
		996	}
		997	}
		998	}
489	}	999	}
490	}
491		1000
492	pkt->len = offs;	1001	pkt.len = offs;
493	return pkt;	1002	}
494	}	1003	}
495		1004
496	void	1005	void
497	vpn::dnsv4_client (dns_packet *pkt)	1006	vpn::dnsv4_client (dns_packet &pkt)
498	{	1007	{
499	u16 flags = ntohs (pkt->flags);	1008	u16 flags = ntohs (pkt.flags);
500	int offs = 6 * 2; // skip header	1009	int offs = 6 * 2; // skip header
501		1010
502	pkt->qdcount = ntohs (pkt->qdcount);	1011	pkt.qdcount = ntohs (pkt.qdcount);
503	pkt->ancount = ntohs (pkt->ancount);	1012	pkt.ancount = ntohs (pkt.ancount);
504		1013
		1014	// go through our request list and find the corresponding request
505	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1015	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506	i != dns_sndpq.end ();	1016	i != dns_sndpq.end ();
507	++i)	1017	++i)
508	if ((*i)->pkt->id == pkt->id)	1018	if ((*i)->pkt->id == pkt.id)
509	{	1019	{
		1020	dns_connection dns = (i)->dns;
510	connection c = (i)->conn;	1021	connection *c = dns->c;
511	printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D	1022	int seqno = (*i)->seqno;
		1023	u8 data[MAXSIZE], *datap = data;
		1024	//printf ("rcv pkt %x\n", seqno);//D
		1025
		1026	if ((*i)->retry)
		1027	{
		1028	dns->send_interval *= 1.01;
		1029	if (dns->send_interval > MAX_SEND_INTERVAL)
		1030	dns->send_interval = MAX_SEND_INTERVAL;
		1031	}
		1032	else
		1033	{
		1034	#if 0
		1035	dns->send_interval *= 0.999;
		1036	#endif
		1037	// the latency surely puts an upper bound on
		1038	// the minimum send interval
		1039	double latency = ev_now () - (*i)->sent;
		1040
		1041	if (latency < dns->min_latency)
		1042	dns->min_latency = latency;
		1043
		1044	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1045	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1046
		1047	if (dns->send_interval < conf.dns_send_interval)
		1048	dns->send_interval = conf.dns_send_interval;
		1049	}
		1050
512	delete *i;	1051	delete *i;
513	dns_sndpq.erase (i);	1052	dns_sndpq.erase (i);
514		1053
515	if (flags & (FLAG_RESPONSE \| FLAG_OP_MASK \| FLAG_TC))	1054	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516	{	1055	{
517	char qname[MAXSIZE];	1056	char qname[MAXSIZE];
518		1057
519	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1058	while (pkt.qdcount-- && offs < MAXSIZE - 4)
520	{	1059	{
521	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1060	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522	offs += 4; // skip qtype, qclass	1061	offs += 4; // skip qtype, qclass
523	}	1062	}
524		1063
525	while (pkt->ancount-- && offs < MAXSIZE - 10)	1064	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526	{	1065	{
527	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1066	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528		1067
529	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];	1068	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
530	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];	1069	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
531	u32 ttl = (*pkt) [offs++] << 24;	1070	u32 ttl = pkt [offs++] << 24;
532	ttl \|= (*pkt) [offs++] << 16;	1071	ttl \|= pkt [offs++] << 16;
533	ttl \|= (*pkt) [offs++] << 8;	1072	ttl \|= pkt [offs++] << 8;
534	ttl \|= (*pkt) [offs++];	1073	ttl \|= pkt [offs++];
535
536	u16 rdlen = (pkt) [offs++] << 8; rdlen \|= (pkt) [offs++];	1074	u16 rdlen = pkt [offs++] << 8; rdlen \|= pkt [offs++];
537		1075
538	printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen);	1076	if (qtype == RR_TYPE_NULL \|\| qtype == RR_TYPE_TXT)
539
540	offs += rdlen;
541
542	if (MAXSIZE - offs < rdlen)
543	{	1077	{
		1078	if (rdlen <= MAXSIZE - offs)
		1079	{
544	// decode bytes, finally	1080	// decode bytes, finally
		1081
		1082	while (rdlen)
		1083	{
		1084	int txtlen = pkt [offs++];
		1085
		1086	assert (txtlen + offs < MAXSIZE - 1);
		1087
		1088	memcpy (datap, pkt.at (offs), txtlen);
		1089	datap += txtlen; offs += txtlen;
		1090
		1091	rdlen -= txtlen + 1;
		1092	}
		1093	}
		1094	}
		1095	else if (qtype == RR_TYPE_A)
		1096	{
		1097	u8 ip [4];
		1098
		1099	ip [0] = pkt [offs++];
		1100	ip [1] = pkt [offs++];
		1101	ip [2] = pkt [offs++];
		1102	ip [3] = pkt [offs++];
		1103
		1104	if (ip [0] == CMD_IP_1
		1105	&& ip [1] == CMD_IP_2
		1106	&& ip [2] == CMD_IP_3)
		1107	{
		1108	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1109
		1110	if (ip [3] == CMD_IP_RST)
		1111	{
		1112	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1113
		1114	delete dns; c->dns = 0;
		1115
		1116	return;
		1117	}
		1118	else if (ip [3] == CMD_IP_SYN)
		1119	{
		1120	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1121	dns->established = true;
		1122	}
		1123	else if (ip [3] == CMD_IP_REJ)
		1124	{
		1125	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1126	abort ();
		1127	}
		1128	else
		1129	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1130	}
		1131	else
		1132	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1133	ip [0], ip [1], ip [2], ip [3]);
		1134
		1135	return;
		1136	}
		1137
		1138	int client, rseqno;
		1139	decode_header (qname, client, rseqno);
		1140
		1141	if (client != THISNODE->id)
		1142	{
		1143	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1144	datap = 0;
		1145	}
		1146	else if (rseqno != seqno)
		1147	{
		1148	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1149	datap = 0;
545	}	1150	}
546	}	1151	}
547	}	1152	}
548		1153
		1154	// todo: pkt now used
		1155	if (datap)
		1156	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1157
549	break;	1158	break;
550	}	1159	}
551	}	1160	}
552		1161
553	void	1162	void
554	vpn::dnsv4_ev (io_watcher &w, short revents)	1163	vpn::dnsv4_ev (ev::io &w, int revents)
555	{	1164	{
556	if (revents & EVENT_READ)	1165	if (revents & EV_READ)
557	{	1166	{
558	dns_packet *pkt = new dns_packet;	1167	dns_packet *pkt = new dns_packet;
559	struct sockaddr_in sa;	1168	struct sockaddr_in sa;
560	socklen_t sa_len = sizeof (sa);	1169	socklen_t sa_len = sizeof (sa);
561		1170
562	pkt->len = recvfrom (w.fd, &((pkt)[0]), MAXSIZE, 0, (sockaddr )&sa, &sa_len);	1171	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563		1172
564	if (pkt->len > 0)	1173	if (pkt->len > 0)
565	if (THISNODE->dns_port)
566	{	1174	{
567	pkt = dnsv4_server (pkt);	1175	if (ntohs (pkt->flags) & FLAG_RESPONSE)
568	sendto (w.fd, &((pkt)[0]), pkt->len, 0, (sockaddr )&sa, sa_len);
569	}
570	else
571	dnsv4_client (pkt);	1176	dnsv4_client (*pkt);
		1177	else
		1178	{
		1179	dnsv4_server (*pkt);
		1180	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
		1181	}
		1182
		1183	delete pkt;
		1184	}
572	}	1185	}
573	}	1186	}
574		1187
575	bool	1188	bool
576	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1189	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577	{	1190	{
578	// never initialized	1191	int client = ntohl (si.host);
579	if (!dns_snddq && !dns_rcvdq)
580	{
581	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
582	dns_snddq = new byte_stream (MAX_BACKLOG);
583		1192
584	dns_rcvseq = dns_sndseq = 0;	1193	assert (0 < client && client <= conns.size ());
585		1194
586	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1195	connection *c = conns [client - 1];
587	}	1196
		1197	if (!c->dns)
		1198	c->dns = new dns_connection (c);
588		1199
589	if (!dns_snddq->put (pkt))	1200	if (c->dns->snddq.put (pkt))
590	return false;	1201	c->dns->tw ();
591		1202
592	// start timer if neccessary	1203	// always return true even if the buffer overflows
593	if (!dnsv4_tw.active)
594	dnsv4_cb (dnsv4_tw);
595
596	return true;	1204	return true;
597	}	1205	}
598		1206
599	void	1207	void
600	connection::dnsv4_cb (time_watcher &w)	1208	connection::dnsv4_reset_connection ()
601	{	1209	{
		1210	//delete dns; dns = 0; //TODO
		1211	}
		1212
		1213	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1214
		1215	void
		1216	dns_connection::time_cb (ev::timer &w, int revents)
		1217	{
		1218	// servers have to be polled
		1219	if (THISNODE->dns_port)
		1220	return;
		1221
602	// check for timeouts and (re)transmit	1222	// check for timeouts and (re)transmit
603	tstamp next = NOW + 60;	1223	tstamp next = ev::now () + poll_interval;
604	dns_req *send = 0;	1224	dns_snd *send = 0;
605		1225
606	slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), vpn->dns_sndpq.size ());
607
608	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1226	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609	i != vpn->dns_sndpq.end ();	1227	i != vpn->dns_sndpq.end ();
610	++i)	1228	++i)
611	{	1229	{
612	dns_req r = i;	1230	dns_snd r = i;
613		1231
614	if (r->next <= NOW)	1232	if (r->timeout <= ev_now ())
615	{	1233	{
616	if (!send)	1234	if (!send)
617	{	1235	{
618	send = r;	1236	send = r;
619		1237
620	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621	r->retry++;	1238	r->retry++;
622	r->next = NOW + r->retry;	1239	r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
		1240	//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
		1241
		1242	// the following code changes the query section a bit, forcing
		1243	// the forwarder to generate a new request
		1244	if (r->stdhdr)
		1245	encode_header ((char )r->pkt->at (6 2 + 1), THISNODE->id, r->seqno, r->retry);
623	}	1246	}
624	}	1247	}
625		1248	else
626	if (r->next < next)	1249	NEXT (r->timeout);
627	next = r->next;
628	}	1250	}
629		1251
630	if (!send	1252	if (!send)
631	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1253	{
632	send = new dns_req (this, dns_sndseq++, dns_snddq);	1254	// generate a new packet, if wise
633		1255
634	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);	1256	if (!established)
		1257	{
		1258	if (vpn->dns_sndpq.empty ())
		1259	{
		1260	send = new dns_snd (this);
		1261
		1262	cfg.reset (THISNODE->id);
		1263	send->gen_syn_req ();
		1264	}
		1265	}
		1266	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1267	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1268	{
		1269	if (last_sent + send_interval <= ev_now ())
		1270	{
		1271	//printf ("sending data request etc.\n"); //D
		1272	if (!snddq.empty () \|\| last_received + 1. > ev_now ())
		1273	{
		1274	poll_interval = send_interval;
		1275	NEXT (ev_now () + send_interval);
		1276	}
		1277
		1278	send = new dns_snd (this);
		1279	send->gen_stream_req (sndseq, snddq);
		1280	send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
		1281	//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
		1282
		1283	sndseq = (sndseq + 1) & SEQNO_MASK;
		1284	}
		1285	else
		1286	NEXT (last_sent + send_interval);
		1287	}
		1288
		1289	if (send)
		1290	vpn->dns_sndpq.push_back (send);
		1291	}
635		1292
636	if (send)	1293	if (send)
637	{	1294	{
638	dns_packet *pkt = send->pkt;	1295	last_sent = ev_now ();
639		1296	sendto (vpn->dnsv4_fd,
640	next = min_next;	1297	send->pkt->at (0), send->pkt->len, 0,
641		1298	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
642	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
643	}	1299	}
644	else if (next < min_next)
645	next = min_next;
646		1300
647	w.start (next);	1301	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1302	poll_interval, send_interval, next - ev_now (),
		1303	vpn->dns_sndpq.size (), snddq.size (),
		1304	rcvpq.size ());
		1305
		1306	// TODO: no idea when this happens, but when next < ev_now (), we have a problem
		1307	// doesn't seem to happen anymore
		1308	if (next < ev_now () + 0.001)
		1309	next = ev_now () + 0.1;
		1310
		1311	w.start (next - ev_now ());
648	}	1312	}
649		1313
650	#endif	1314	#endif
651		1315

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Comparing gvpe/src/vpn_dns.C (file contents): Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 UTC vs. Revision 1.46 by pcg, Thu Dec 6 00:35:29 2007 UTC

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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 UTC vs.
Revision 1.46 by pcg, Thu Dec 6 00:35:29 2007 UTC