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

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.2 by pcg, Tue Mar 1 04:38:21 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	#if ENABLE_HTTP_PROXY	54	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	# include "conf.h"	55	#define ACTIVITY_INTERVAL 5.
46	#endif
47		56
48	#define MIN_RETRY 1.	57	#define INITIAL_TIMEOUT 0.1 // retry timeouts
49	#define MAX_RETRY 60.	58	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
50		59
51	#define SERVER conf.dns_port	60	#define MAX_SEND_INTERVAL 2. // optimistic?
52		61
53	/*	62	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
		63	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
54		64
55	protocol, in shorthand :)	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
56		68
57	client -> server <req> ANY?	69	#define SEQNO_MASK 0x3fff
58	server -> client <req> TXT <rep>	70	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
59
60	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
61	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
62
63	if <client-id> is zero, the connection will be configured:
64
65	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
66
67	*/
68		71
69	#define MAX_LBL_SIZE 63	72	#define MAX_LBL_SIZE 63
70	#define MAX_PKT_SIZE 512	73	#define MAX_PKT_SIZE 512
71		74
		75	#define RR_TYPE_A 1
		76	#define RR_TYPE_NULL 10
72	#define RR_TYPE_TXT 16	77	#define RR_TYPE_TXT 16
73	#define RR_TYPE_ANY 255	78	#define RR_TYPE_ANY 255
		79
74	#define RR_CLASS_IN 1	80	#define RR_CLASS_IN 1
75		81
76	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	82	#define CMD_IP_1 207
77	struct dns64	83	#define CMD_IP_2 46
78	{	84	#define CMD_IP_3 236
79	static const char encode_chars[64 + 1];	85	#define CMD_IP_RST 29
80	static s8 decode_chars[256];	86	#define CMD_IP_SYN 113
		87	#define CMD_IP_REJ 32
81		88
82	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	89	// works for cmaps up to 255 (not 256!)
83	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
84	static void encode (char dst, u8 src, int len);	132	unsigned int encode (char dst, u8 src, unsigned int len);
85	static void decode (u8 dst, char src, int len);	133	unsigned int decode (u8 dst, char src, unsigned int len);
86		134
87	dns64 ();	135	basecoder (const char *cmap);
88	} dns64;	136	};
89		137
90	const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ";	138	basecoder::basecoder (const char *cmap)
91	s8 dns64::decode_chars[256];	139	: cmap (cmap)
92
93	dns64::dns64 ()
94	{	140	{
95	for (int i = 0; i < 64; i++)	141	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
96	decode_chars [encode_chars [i]] = i + 1;	142	{
97	}	143	u8 src [MAX_DEC_LEN];
		144	u8 dst [MAX_ENC_LEN];
98		145
99	void 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)
100	{	163	{
101	// slow, but easy to debug	164	return enc_len [len];
102	unsigned int accum, bits = 0;	165	}
		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	}	239	}
120		240
121	void dns64::decode (u8 dst, char src, int len)	241	#if 0
122	{	242	struct test { test (); } test;
123	// slow, but easy to debug
124	unsigned int accum, bits = 0;
125		243
126	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++)
127	{	253	{
128	s8 chr = decode_chars [(u8)*src++];	254	int elen = cdc.encode (enc, in, i);
		255	int dlen = cdc.decode (dec, enc, elen);
129		256
		257	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
		258	}
		259	abort ();
		260	}
		261	#endif
130		262
131	if (!chr)	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;
		296	}
		297
		298	/////////////////////////////////////////////////////////////////////////////
		299
		300	struct byte_stream
		301	{
		302	u8 *data;
		303	int maxsize;
		304	int fill;
		305
		306	byte_stream (int maxsize);
		307	~byte_stream ();
		308
		309	bool empty () { return !fill; }
		310	int size () { return fill; }
		311
		312	bool put (u8 *data, unsigned int datalen);
		313	bool put (vpn_packet *pkt);
		314	vpn_packet *get ();
		315
		316	u8 *begin () { return data; }
		317	void remove (int count);
		318	};
		319
		320	byte_stream::byte_stream (int maxsize)
		321	: maxsize (maxsize), fill (0)
		322	{
		323	data = new u8 [maxsize];
		324	}
		325
		326	byte_stream::~byte_stream ()
		327	{
		328	delete data;
		329	}
		330
		331	void byte_stream::remove (int count)
		332	{
		333	if (count > fill)
		334	assert (count <= fill);
		335
		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;
		347	}
		348
		349	bool byte_stream::put (vpn_packet *pkt)
		350	{
		351	if (maxsize - fill < pkt->len + 2)
		352	return false;
		353
		354	data [fill++] = pkt->len >> 8;
		355	data [fill++] = pkt->len;
		356
		357	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
		358
		359	return true;
		360	}
		361
		362	vpn_packet *byte_stream::get ()
		363	{
		364	unsigned int len;
		365
		366	for (;;)
		367	{
		368	len = (data [0] << 8) \| data [1];
		369
		370	if (len <= MAXSIZE \|\| fill < 2)
132	break;	371	break;
133		372
134	accum <<= 6;	373	// TODO: handle this better than skipping, e.g. by reset
135	accum \|= chr - 1;	374	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
136	bits += 6;	375	remove (1);
137		376	}
138	while (bits >= 8)
139	{	377
140	*dst++ = accum >> (bits - 8);	378	if (fill < len + 2)
141	bits -= 8;	379	return 0;
142	}	380
143	}	381	vpn_packet *pkt = new vpn_packet;
		382
		383	pkt->len = len;
		384	memcpy (pkt->at (0), data + 2, len);
		385	remove (len + 2);
		386
		387	return pkt;
144	}	388	}
		389
		390	/////////////////////////////////////////////////////////////////////////////
145		391
146	#define FLAG_QUERY ( 0 << 15)	392	#define FLAG_QUERY ( 0 << 15)
147	#define FLAG_RESPONSE ( 1 << 15)	393	#define FLAG_RESPONSE ( 1 << 15)
148	#define FLAG_OP_MASK (15 << 14)	394	#define FLAG_OP_MASK (15 << 11)
149	#define FLAG_OP_QUERY ( 0 << 11)	395	#define FLAG_OP_QUERY ( 0 << 11)
150	#define FLAG_AA ( 1 << 10)	396	#define FLAG_AA ( 1 << 10)
151	#define FLAG_TC ( 1 << 9)	397	#define FLAG_TC ( 1 << 9)
152	#define FLAG_RD ( 1 << 8)	398	#define FLAG_RD ( 1 << 8)
153	#define FLAG_RA ( 1 << 7)	399	#define FLAG_RA ( 1 << 7)
		400	#define FLAG_AUTH ( 1 << 5)
154	#define FLAG_RCODE_MASK (15 << 0)	401	#define FLAG_RCODE_MASK (15 << 0)
155	#define FLAG_RCODE_OK ( 0 << 0)	402	#define FLAG_RCODE_OK ( 0 << 0)
156	#define FLAG_RCODE_FORMERR ( 1 << 0)	403	#define FLAG_RCODE_FORMERR ( 1 << 0)
157	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	404	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
158	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	405	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
159	#define FLAG_RCODE_REFUSED ( 5 << 0)	406	#define FLAG_RCODE_REFUSED ( 5 << 0)
160		407
161	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)	408	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY \| FLAG_OP_QUERY \| FLAG_RD)
162	#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	}
163		478
164	struct dns_packet : net_packet	479	struct dns_packet : net_packet
165	{	480	{
166	u16 id;	481	u16 id;
167	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
168	u16 qdcount, ancount, nscount, arcount;	483	u16 qdcount, ancount, nscount, arcount;
169		484
170	u8 data[MAXSIZE - 6 * 2];	485	u8 data [MAXSIZE - 6 * 2];
171		486
172	int decode_label (char *data, int size, int &offs);	487	int decode_label (char *data, int size, int &offs);
173	};	488	};
174		489
175	int dns_packet::decode_label (char *data, int size, int &offs)	490	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
204	}	519	}
205		520
206	return data - orig;	521	return data - orig;
207	}	522	}
208		523
		524	/////////////////////////////////////////////////////////////////////////////
		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
209	struct dns_cfg	543	struct dns_rcv;
		544	struct dns_snd;
		545
		546	struct dns_connection
210	{	547	{
211	u8 id1, id2, id3;	548	connection *c;
212	u8 def_ttl;	549	struct vpn *vpn;
213	u8 unused1;	550
214	u16 max_size;	551	dns_cfg cfg;
215	u8 flags1, flags2;	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 ();
216	};	570	};
217		571
218	// reply to client-poll	572	struct dns_snd
219	void dnsv4_poll (dns_packet *pkt, int &offs)
220	{	573	{
221	int dlen = MAX_PKT_SIZE - offs - 2;	574	dns_packet *pkt;
		575	tstamp timeout, sent;
		576	int retry;
		577	struct dns_connection *dns;
		578	int seqno;
		579	bool stdhdr;
222		580
		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 ();
		586	};
		587
		588	dns_snd::dns_snd (dns_connection *dns)
		589	: dns (dns)
		590	{
		591	timeout = 0;
		592	retry = 0;
		593	seqno = 0;
		594	sent = ev_now ();
		595	stdhdr = false;
		596
		597	pkt = new dns_packet;
		598
		599	pkt->id = next_id ();
		600	}
		601
		602	dns_snd::~dns_snd ()
		603	{
		604	delete pkt;
		605	}
		606
		607	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		608	{
		609	// add tunnel domain
		610	for (;;)
		611	{
		612	const char *end = strchr (domain, '.');
		613
		614	if (!end)
		615	end = domain + strlen (domain);
		616
		617	int len = end - domain;
		618
		619	pkt [offs++] = len;
		620	memcpy (pkt.at (offs), domain, len);
		621	offs += len;
		622
		623	if (!*end)
		624	break;
		625
		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)
		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);
		670
223	(*pkt) [offs++] = 0;	671	(*pkt)[offs++] = 0;
		672	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;
		673	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		674
		675	pkt->len = offs;
		676	}
		677
		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
224	(*pkt) [offs++] = 5;	695	(*pkt)[offs++] = 0;
225	memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5);	696	(pkt)[offs++] = RR_TYPE_A >> 8; (pkt)[offs++] = RR_TYPE_A;
226	offs += 5;	697	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
227		698
228	pkt->ancount = htons (1);	699	pkt->len = offs;
229	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);	700	}
230		701
231	printf ("we have room for %d bytes\n", dlen);	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;
		722	}
		723
		724	/////////////////////////////////////////////////////////////////////////////
		725
		726	dns_connection::dns_connection (connection *c)
		727	: c (c)
		728	, rcvdq (MAX_BACKLOG * 2)
		729	, snddq (MAX_BACKLOG)
		730	{
		731	tw.set<dns_connection, &dns_connection::time_cb> (this);
		732
		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	}
232	}	813	}
233		814
234	void	815	void
		816	vpn::dnsv4_server (dns_packet &pkt)
		817	{
		818	u16 flags = ntohs (pkt.flags);
		819
		820	int offs = 6 * 2; // skip header
		821
		822	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		823
		824	if (0 == (flags & (FLAG_RESPONSE \| FLAG_OP_MASK))
		825	&& pkt.qdcount == htons (1))
		826	{
		827	char qname [MAXSIZE];
		828	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		829
		830	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		831	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		832
		833	pkt.qdcount = htons (1);
		834	pkt.ancount = 0;
		835	pkt.nscount = 0; // should be self, as other nameservers reply like this
		836	pkt.arcount = 0; // a record for self, as other nameservers reply like this
		837
		838	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_SERVFAIL);
		839
		840	int dlen = strlen (THISNODE->domain);
		841
		842	if (qclass == RR_CLASS_IN
		843	&& qlen > dlen + 1
		844	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
		845	{
		846	// now generate reply
		847	pkt.ancount = htons (1); // one answer RR
		848	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);
		849
		850	if ((qtype == RR_TYPE_ANY
		851	\|\| qtype == RR_TYPE_TXT
		852	\|\| qtype == RR_TYPE_NULL)
		853	&& qlen > dlen + 1 + HDRSIZE)
		854	{
		855	// correct class, domain: parse
		856	int client, seqno;
		857	decode_header (qname, client, seqno);
		858
		859	u8 data[MAXSIZE];
		860	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		861
		862	if (0 < client && client <= conns.size ())
		863	{
		864	connection *c = conns [client - 1];
		865	dns_connection *dns = c->dns;
		866	dns_rcv *rcv;
		867
		868	if (dns)
		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);
		927	offs += txtlen;
		928	dns->snddq.remove (txtlen);
		929
		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);
		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);
		971
		972	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		973
		974	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
		975	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		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	}
		999	}
		1000
		1001	pkt.len = offs;
		1002	}
		1003	}
		1004
		1005	void
		1006	vpn::dnsv4_client (dns_packet &pkt)
		1007	{
		1008	u16 flags = ntohs (pkt.flags);
		1009	int offs = 6 * 2; // skip header
		1010
		1011	pkt.qdcount = ntohs (pkt.qdcount);
		1012	pkt.ancount = ntohs (pkt.ancount);
		1013
		1014	// go through our request list and find the corresponding request
		1015	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
		1016	i != dns_sndpq.end ();
		1017	++i)
		1018	if ((*i)->pkt->id == pkt.id)
		1019	{
		1020	dns_connection dns = (i)->dns;
		1021	connection *c = dns->c;
		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
		1051	delete *i;
		1052	dns_sndpq.erase (i);
		1053
		1054	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
		1055	{
		1056	char qname[MAXSIZE];
		1057
		1058	while (pkt.qdcount-- && offs < MAXSIZE - 4)
		1059	{
		1060	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1061	offs += 4; // skip qtype, qclass
		1062	}
		1063
		1064	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
		1065	{
		1066	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1067
		1068	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		1069	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		1070	u32 ttl = pkt [offs++] << 24;
		1071	ttl \|= pkt [offs++] << 16;
		1072	ttl \|= pkt [offs++] << 8;
		1073	ttl \|= pkt [offs++];
		1074	u16 rdlen = pkt [offs++] << 8; rdlen \|= pkt [offs++];
		1075
		1076	if (qtype == RR_TYPE_NULL \|\| qtype == RR_TYPE_TXT)
		1077	{
		1078	if (rdlen <= MAXSIZE - offs)
		1079	{
		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;
		1150	}
		1151	}
		1152	}
		1153
		1154	// todo: pkt now used
		1155	if (datap)
		1156	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1157
		1158	break;
		1159	}
		1160	}
		1161
		1162	void
235	vpn::dnsv4_ev (io_watcher &w, short revents)	1163	vpn::dnsv4_ev (ev::io &w, int revents)
236	{	1164	{
237	if (revents & EVENT_READ)	1165	if (revents & EV_READ)
238	{	1166	{
239	dns_packet *pkt = new dns_packet;	1167	dns_packet *pkt = new dns_packet;
240	struct sockaddr_in sa;	1168	struct sockaddr_in sa;
241	socklen_t sa_len = sizeof (sa);	1169	socklen_t sa_len = sizeof (sa);
242		1170
243	int 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);
244	pkt->len = len;
245		1172
246	u16 flags = ntohs (pkt->flags);	1173	if (pkt->len > 0)
247
248	if (THISNODE->dns_port)
249	{	1174	{
250	// server	1175	if (ntohs (pkt->flags) & FLAG_RESPONSE)
251	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);	1176	dnsv4_client (*pkt);
252		1177	else
253	int offs = 6 * 2; // skip header
254
255	if (!(flags & (FLAG_RESPONSE \| FLAG_OP_MASK \| FLAG_TC))
256	&& pkt->qdcount == htons (1))
257	{	1178	{
258	char qname[MAXSIZE];	1179	dnsv4_server (*pkt);
259	int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs);	1180	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
260
261	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len,
262	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
263
264	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];
265	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];
266
267	pkt->qdcount = htons (1);
268	pkt->ancount = 0;
269	pkt->nscount = 0; // should be self, as other nameservers reply like this
270	pkt->arcount = 0; // a record for self, as other nameservers reply like this
271
272	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_NXDOMAIN);
273
274	int dlen = strlen (THISNODE->domain);
275
276	if (qclass == RR_CLASS_IN
277	&& (qtype == RR_TYPE_ANY \|\| qtype == RR_TYPE_TXT)
278	&& qlen > dlen + 1
279	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
280	{
281	// correct class, now generate reply
282	pkt->ancount = htons (1); // one answer RR
283
284	(*pkt) [offs++] = 0xc0;
285	(pkt) [offs++] = 6 2; // same as in query section
286
287	(pkt) [offs++] = RR_TYPE_TXT >> 8; (pkt) [offs++] = RR_TYPE_TXT;
288	(pkt) [offs++] = RR_CLASS_IN >> 8; (pkt) [offs++] = RR_CLASS_IN;
289
290	(pkt) [offs++] = 0; (pkt) [offs++] = 0;
291	(pkt) [offs++] = 0; (pkt) [offs++] = 0; // TTL
292
293	dnsv4_poll (pkt, offs);
294	printf ("correct class\n");
295	}
296	}	1181	}
297		1182
298	sendto (w.fd, &((pkt)[0]), offs, 0, (sockaddr )&sa, sa_len);	1183	delete pkt;
		1184	}
		1185	}
		1186	}
		1187
		1188	bool
		1189	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
		1190	{
		1191	int client = ntohl (si.host);
		1192
		1193	assert (0 < client && client <= conns.size ());
		1194
		1195	connection *c = conns [client - 1];
		1196
		1197	if (!c->dns)
		1198	c->dns = new dns_connection (c);
		1199
		1200	if (c->dns->snddq.put (pkt))
		1201	c->dns->tw ();
		1202
		1203	// always return true even if the buffer overflows
		1204	return true;
		1205	}
		1206
		1207	void
		1208	connection::dnsv4_reset_connection ()
		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
		1222	// check for timeouts and (re)transmit
		1223	tstamp next = ev::now () + poll_interval;
		1224	dns_snd *send = 0;
		1225
		1226	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
		1227	i != vpn->dns_sndpq.end ();
		1228	++i)
		1229	{
		1230	dns_snd r = i;
		1231
		1232	if (r->timeout <= ev_now ())
		1233	{
		1234	if (!send)
		1235	{
		1236	send = r;
		1237
		1238	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);
		1246	}
299	}	1247	}
300	else	1248	else
		1249	NEXT (r->timeout);
		1250	}
		1251
		1252	if (!send)
		1253	{
		1254	// generate a new packet, if wise
		1255
		1256	if (!established)
301	{	1257	{
302	// client	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	}
303	}	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	}
		1292
		1293	if (send)
304	}	1294	{
305	}	1295	last_sent = ev_now ();
		1296	sendto (vpn->dnsv4_fd,
		1297	send->pkt->at (0), send->pkt->len, 0,
		1298	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1299	}
306		1300
307	bool	1301	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
308	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1302	poll_interval, send_interval, next - ev_now (),
309	{	1303	vpn->dns_sndpq.size (), snddq.size (),
310	//return i->send_packet (pkt, tos);	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 ());
311	}	1312	}
312		1313
313	#endif	1314	#endif
314		1315

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Comparing gvpe/src/vpn_dns.C (file contents): Revision 1.2 by pcg, Tue Mar 1 04:38:21 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 1.2 by pcg, Tue Mar 1 04:38:21 2005 UTC vs.
Revision 1.46 by pcg, Thu Dec 6 00:35:29 2007 UTC