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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.3 by pcg, Tue Mar 1 06:27:20 2005 UTC vs.
Revision 1.38 by pcg, Tue Apr 19 04:23:38 2005 UTC

1	/*	1	/*
2	vpn_dns.C -- handle the dns tunnel part of the protocol.	2	vpn_dns.C -- handle the dns tunnel part of the protocol.
3	Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com>	3	Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de>
4		4
		5	This file is part of GVPE.
		6
5	This program is free software; you can redistribute it and/or modify	7	GVPE is free software; you can redistribute it and/or modify
6	it under the terms of the GNU General Public License as published by	8	it under the terms of the GNU General Public License as published by
7	the Free Software Foundation; either version 2 of the License, or	9	the Free Software Foundation; either version 2 of the License, or
8	(at your option) any later version.	10	(at your option) any later version.
9		11
10	This program is distributed in the hope that it will be useful,	12	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.	15	GNU General Public License for more details.
14		16
15	You should have received a copy of the GNU General Public License	17	You should have received a copy of the GNU General Public License
16	along with this program; if not, write to the Free Software	18	along with gvpe; if not, write to the Free Software
17	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA	19	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18	*/	20	*/
19		21
		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.
		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 <gmp.h>
		48
40	#include "netcompat.h"	49	#include "netcompat.h"
41		50
42	#include "vpn.h"	51	#include "vpn.h"
43		52
44	#define MIN_RETRY 1.	53	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	54	#define ACTIVITY_INTERVAL 5.
46		55
47	#define MAX_OUTSTANDING 10 // max. outstanding requests	56	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		57	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
48		58
49	/*	59	#define MAX_SEND_INTERVAL 2. // optimistic?
50		60
51	protocol, in shorthand :)	61	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
		62	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
52		63
53	client -> server <req> ANY?	64	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
54	server -> client <req> TXT <rep>	65	// 240 leaves about 4 bytes of server reply data
		66	// every request byte less give room for two reply bytes
55		67
56	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]	68	#define SEQNO_MASK 0x3fff
57	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]	69	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
58
59	if <client-id> is zero, the connection will be configured:
60
61	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
62
63	*/
64		70
65	#define MAX_LBL_SIZE 63	71	#define MAX_LBL_SIZE 63
66	#define MAX_PKT_SIZE 512	72	#define MAX_PKT_SIZE 512
67		73
		74	#define RR_TYPE_A 1
		75	#define RR_TYPE_NULL 10
68	#define RR_TYPE_TXT 16	76	#define RR_TYPE_TXT 16
69	#define RR_TYPE_ANY 255	77	#define RR_TYPE_ANY 255
		78
70	#define RR_CLASS_IN 1	79	#define RR_CLASS_IN 1
71		80
72	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	81	#define CMD_IP_1 207
73	struct dns64	82	#define CMD_IP_2 46
74	{	83	#define CMD_IP_3 236
75	static const char encode_chars[64 + 1];	84	#define CMD_IP_RST 29
76	static s8 decode_chars[256];	85	#define CMD_IP_SYN 113
		86	#define CMD_IP_REJ 32
77		87
78	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	88	// works for cmaps up to 255 (not 256!)
79	static int decode_len (int bytes) { return (bytes * 6) / 8; }	89	struct charmap
		90	{
		91	enum { INVALID = (u8)255 };
		92
		93	char encode [256]; // index => char
		94	u8 decode [256]; // char => index
		95	unsigned int size;
		96
		97	charmap (const char *cmap);
		98	};
		99
		100	charmap::charmap (const char *cmap)
		101	{
		102	char *enc = encode;
		103	u8 *dec = decode;
		104
		105	memset (enc, (char) 0, 256);
		106	memset (dec, (char)INVALID, 256);
		107
		108	for (size = 0; cmap [size]; size++)
		109	{
		110	enc [size] = cmap [size];
		111	dec [(u8)enc [size]] = size;
		112	}
		113
		114	assert (size < 256);
		115	}
		116
		117	#define MAX_DEC_LEN 500
		118	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		119	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		120
		121	// ugly. minimum base is 16(!)
		122	struct basecoder
		123	{
		124	charmap cmap;
		125	unsigned int enc_len [MAX_DEC_LEN];
		126	unsigned int dec_len [MAX_ENC_LEN];
		127
		128	unsigned int encode_len (unsigned int len);
		129	unsigned int decode_len (unsigned int len);
		130
80	static void encode (char *dst, u8 *src, int len);	131	unsigned int encode (char *dst, u8 *src, unsigned int len);
81	static void decode (u8 *dst, char *src, int len);	132	unsigned int decode (u8 *dst, char *src, unsigned int len);
82		133
83	dns64 ();	134	basecoder (const char *cmap);
84	} dns64;	135	};
85		136
86	const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ";	137	basecoder::basecoder (const char *cmap)
87	s8 dns64::decode_chars[256];	138	: cmap (cmap)
88
89	dns64::dns64 ()
90	{	139	{
91	for (int i = 0; i < 64; i++)	140	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
92	decode_chars [encode_chars [i]] = i + 1;	141	{
93	}	142	u8 src [MAX_DEC_LEN];
		143	u8 dst [MAX_ENC_LEN];
94		144
95	void dns64::encode (char *dst, u8 *src, int len)	145	memset (src, 255, len);
		146
		147	mp_limb_t m [MAX_LIMBS];
		148	mp_size_t n;
		149
		150	n = mpn_set_str (m, src, len, 256);
		151	n = mpn_get_str (dst, this->cmap.size, m, n);
		152
		153	for (int i = 0; !dst [i]; ++i)
		154	n--;
		155
		156	enc_len [len] = n;
		157	dec_len [n] = len;
		158	}
		159	}
		160
		161	unsigned int basecoder::encode_len (unsigned int len)
96	{	162	{
97	// slow, but easy to debug	163	return enc_len [len];
98	unsigned int accum, bits = 0;	164	}
		165
		166	unsigned int basecoder::decode_len (unsigned int len)
		167	{
		168	while (len && !dec_len [len])
		169	--len;
		170
		171	return dec_len [len];
		172	}
		173
		174	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		175	{
		176	if (!len || len > MAX_DEC_LEN)
		177	return 0;
		178
		179	int elen = encode_len (len);
		180
		181	mp_limb_t m [MAX_LIMBS];
		182	mp_size_t n;
		183
		184	u8 dst_ [MAX_ENC_LEN];
		185
		186	n = mpn_set_str (m, src, len, 256);
		187	n = mpn_get_str (dst_, cmap.size, m, n);
		188
		189	int plen = elen; // for padding
		190
		191	while (n < plen)
		192	{
		193	*dst++ = cmap.encode [0];
		194	plen--;
		195	}
		196
		197	for (unsigned int i = n - plen; i < n; ++i)
		198	*dst++ = cmap.encode [dst_ [i]];
		199
		200	return elen;
		201	}
		202
		203	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		204	{
		205	if (!len || len > MAX_ENC_LEN)
		206	return 0;
		207
		208	u8 src_ [MAX_ENC_LEN];
		209	unsigned int elen = 0;
99		210
100	while (len--)	211	while (len--)
101	{	212	{
102	accum <<= 8;	213	u8 val = cmap.decode [(u8)*src++];
103	accum |= *src++;
104	bits += 8;
105		214
106	while (bits >= 6)	215	if (val != charmap::INVALID)
107	{	216	src_ [elen++] = val;
108	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	217	}
109	bits -= 6;	218
110	}	219	int dlen = decode_len (elen);
		220
		221	mp_limb_t m [MAX_LIMBS];
		222	mp_size_t n;
		223
		224	u8 dst_ [MAX_DEC_LEN];
		225
		226	n = mpn_set_str (m, src_, elen, cmap.size);
		227	n = mpn_get_str (dst_, 256, m, n);
		228
		229	if (n < dlen)
111	}	230	{
		231	memset (dst, 0, dlen - n);
		232	memcpy (dst + dlen - n, dst_, n);
		233	}
		234	else
		235	memcpy (dst, dst_ + n - dlen, dlen);
112		236
113	if (bits)	237	return dlen;
114	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
115	}	238	}
116		239
117	void dns64::decode (u8 *dst, char *src, int len)	240	#if 0
118	{	241	struct test { test (); } test;
119	// slow, but easy to debug
120	unsigned int accum, bits = 0;
121		242
122	while (len--)	243	test::test ()
		244	{
		245	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		246
		247	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		248	static char enc[200];
		249	static u8 dec[200];
		250
		251	for (int i = 1; i < 20; i++)
123	{	252	{
124	s8 chr = decode_chars [(u8)*src++];	253	int elen = cdc.encode (enc, in, i);
		254	int dlen = cdc.decode (dec, enc, elen);
125		255
		256	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
		257	}
		258	abort ();
		259	}
		260	#endif
126		261
127	if (!chr)	262	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		263	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		264	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		265	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		266	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		267
		268	/////////////////////////////////////////////////////////////////////////////
		269
		270	#define HDRSIZE 6
		271
		272	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		273	{
		274	seqno &= SEQNO_MASK;
		275
		276	u8 hdr[3] = {
		277	clientid,
		278	(seqno >> 8) | (retry << 6),
		279	seqno,
		280	};
		281
		282	assert (clientid < 256);
		283
		284	cdc26.encode (data, hdr, 3);
		285	}
		286
		287	inline void decode_header (char *data, int &clientid, int &seqno)
		288	{
		289	u8 hdr[3];
		290
		291	cdc26.decode (hdr, data, HDRSIZE);
		292
		293	clientid = hdr[0];
		294	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
		295	}
		296
		297	/////////////////////////////////////////////////////////////////////////////
		298
		299	struct byte_stream
		300	{
		301	u8 *data;
		302	int maxsize;
		303	int fill;
		304
		305	byte_stream (int maxsize);
		306	~byte_stream ();
		307
		308	bool empty () { return !fill; }
		309	int size () { return fill; }
		310
		311	bool put (u8 *data, unsigned int datalen);
		312	bool put (vpn_packet *pkt);
		313	vpn_packet *get ();
		314
		315	u8 *begin () { return data; }
		316	void remove (int count);
		317	};
		318
		319	byte_stream::byte_stream (int maxsize)
		320	: maxsize (maxsize), fill (0)
		321	{
		322	data = new u8 [maxsize];
		323	}
		324
		325	byte_stream::~byte_stream ()
		326	{
		327	delete data;
		328	}
		329
		330	void byte_stream::remove (int count)
		331	{
		332	if (count > fill)
		333	assert (count <= fill);
		334
		335	memmove (data, data + count, fill -= count);
		336	}
		337
		338	bool byte_stream::put (u8 *data, unsigned int datalen)
		339	{
		340	if (maxsize - fill < datalen)
		341	return false;
		342
		343	memcpy (this->data + fill, data, datalen); fill += datalen;
		344
		345	return true;
		346	}
		347
		348	bool byte_stream::put (vpn_packet *pkt)
		349	{
		350	if (maxsize - fill < pkt->len + 2)
		351	return false;
		352
		353	data [fill++] = pkt->len >> 8;
		354	data [fill++] = pkt->len;
		355
		356	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
		357
		358	return true;
		359	}
		360
		361	vpn_packet *byte_stream::get ()
		362	{
		363	unsigned int len;
		364
		365	for (;;)
		366	{
		367	len = (data [0] << 8) | data [1];
		368
		369	if (len <= MAXSIZE || fill < 2)
128	break;	370	break;
129		371
130	accum <<= 6;	372	// TODO: handle this better than skipping, e.g. by reset
131	accum |= chr - 1;	373	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
132	bits += 6;	374	remove (1);
133		375	}
134	while (bits >= 8)
135	{	376
136	*dst++ = accum >> (bits - 8);	377	if (fill < len + 2)
137	bits -= 8;	378	return 0;
138	}	379
139	}	380	vpn_packet *pkt = new vpn_packet;
		381
		382	pkt->len = len;
		383	memcpy (pkt->at (0), data + 2, len);
		384	remove (len + 2);
		385
		386	return pkt;
140	}	387	}
141		388
142	/////////////////////////////////////////////////////////////////////////////	389	/////////////////////////////////////////////////////////////////////////////
143		390
144	#define FLAG_QUERY ( 0 << 15)	391	#define FLAG_QUERY ( 0 << 15)
145	#define FLAG_RESPONSE ( 1 << 15)	392	#define FLAG_RESPONSE ( 1 << 15)
146	#define FLAG_OP_MASK (15 << 14)	393	#define FLAG_OP_MASK (15 << 11)
147	#define FLAG_OP_QUERY ( 0 << 11)	394	#define FLAG_OP_QUERY ( 0 << 11)
148	#define FLAG_AA ( 1 << 10)	395	#define FLAG_AA ( 1 << 10)
149	#define FLAG_TC ( 1 << 9)	396	#define FLAG_TC ( 1 << 9)
150	#define FLAG_RD ( 1 << 8)	397	#define FLAG_RD ( 1 << 8)
151	#define FLAG_RA ( 1 << 7)	398	#define FLAG_RA ( 1 << 7)
		399	#define FLAG_AUTH ( 1 << 5)
152	#define FLAG_RCODE_MASK (15 << 0)	400	#define FLAG_RCODE_MASK (15 << 0)
153	#define FLAG_RCODE_OK ( 0 << 0)	401	#define FLAG_RCODE_OK ( 0 << 0)
154	#define FLAG_RCODE_FORMERR ( 1 << 0)	402	#define FLAG_RCODE_FORMERR ( 1 << 0)
155	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	403	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
156	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	404	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
157	#define FLAG_RCODE_REFUSED ( 5 << 0)	405	#define FLAG_RCODE_REFUSED ( 5 << 0)
158		406
159	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	407	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
160	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD)	408	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
		409
		410	struct dns_cfg
		411	{
		412	static int next_uid;
		413
		414	u8 id1, id2, id3, id4;
		415
		416	u8 version;
		417	u8 flags;
		418	u8 rrtype;
		419	u8 def_ttl;
		420
		421	u16 client;
		422	u16 uid; // to make request unique
		423
		424	u16 max_size;
		425	u8 seq_cdc;
		426	u8 req_cdc;
		427
		428	u8 rep_cdc;
		429	u8 delay; // time in 0.01s units that the server may delay replying packets
		430	u8 r3, r4;
		431
		432	u8 r5, r6, r7, r8;
		433
		434	void reset (int clientid);
		435	bool valid ();
		436	};
		437
		438	int dns_cfg::next_uid;
		439
		440	void dns_cfg::reset (int clientid)
		441	{
		442	id1 = 'G';
		443	id2 = 'V';
		444	id3 = 'P';
		445	id4 = 'E';
		446
		447	version = 1;
		448
		449	rrtype = RR_TYPE_TXT;
		450	flags = 0;
		451	def_ttl = 0;
		452	seq_cdc = 26;
		453	req_cdc = 62;
		454	rep_cdc = 0;
		455	max_size = htons (MAX_PKT_SIZE);
		456	client = htons (clientid);
		457	uid = next_uid++;
		458	delay = 0;
		459
		460	r3 = r4 = 0;
		461	r4 = r5 = r6 = r7 = 0;
		462	}
		463
		464	bool dns_cfg::valid ()
		465	{
		466	return id1 == 'G'
		467	&& id2 == 'V'
		468	&& id3 == 'P'
		469	&& id4 == 'E'
		470	&& seq_cdc == 26
		471	&& req_cdc == 62
		472	&& rep_cdc == 0
		473	&& version == 1;
		474	}
161		475
162	struct dns_packet : net_packet	476	struct dns_packet : net_packet
163	{	477	{
164	u16 id;	478	u16 id;
165	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	479	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
166	u16 qdcount, ancount, nscount, arcount;	480	u16 qdcount, ancount, nscount, arcount;
167		481
168	u8 data[MAXSIZE - 6 * 2];	482	u8 data [MAXSIZE - 6 * 2];
169		483
170	int decode_label (char *data, int size, int &offs);	484	int decode_label (char *data, int size, int &offs);
171	};	485	};
172		486
173	int dns_packet::decode_label (char *data, int size, int &offs)	487	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
204	return data - orig;	518	return data - orig;
205	}	519	}
206		520
207	/////////////////////////////////////////////////////////////////////////////	521	/////////////////////////////////////////////////////////////////////////////
208		522
		523	static u16 dns_id = 0; // TODO: should be per-vpn
		524
		525	static u16 next_id ()
		526	{
		527	if (!dns_id)
		528	dns_id = time (0);
		529
		530	// the simplest lsfr with periodicity 65535 i could find
		531	dns_id = (dns_id << 1)
		532	| (((dns_id >> 1)
		533	^ (dns_id >> 2)
		534	^ (dns_id >> 4)
		535	^ (dns_id >> 15)) & 1);
		536
		537	return dns_id;
		538	}
		539
209	struct dns_req	540	struct dns_rcv;
		541	struct dns_snd;
		542
		543	struct dns_connection
		544	{
		545	connection *c;
		546	struct vpn *vpn;
		547
		548	dns_cfg cfg;
		549
		550	bool established;
		551
		552	tstamp last_received;
		553	tstamp last_sent;
		554	double min_latency;
		555	double poll_interval, send_interval;
		556
		557	vector<dns_rcv *> rcvpq;
		558
		559	byte_stream rcvdq; int rcvseq; int repseq;
		560	byte_stream snddq; int sndseq;
		561
		562	void time_cb (time_watcher &w); time_watcher tw;
		563	void receive_rep (dns_rcv *r);
		564
		565	dns_connection (connection *c);
		566	~dns_connection ();
		567	};
		568
		569	struct dns_snd
210	{	570	{
211	dns_packet *pkt;	571	dns_packet *pkt;
212	tstamp next;	572	tstamp timeout, sent;
213	int retry;	573	int retry;
		574	struct dns_connection *dns;
		575	int seqno;
		576	bool stdhdr;
214		577
215	dns_req (connection *c, vpn_packet *p, int &offs);	578	void gen_stream_req (int seqno, byte_stream &stream);
		579	void gen_syn_req ();
		580
		581	dns_snd (dns_connection *dns);
		582	~dns_snd ();
216	};	583	};
217		584
		585	dns_snd::dns_snd (dns_connection *dns)
		586	: dns (dns)
		587	{
		588	timeout = 0;
		589	retry = 0;
		590	seqno = 0;
		591	sent = NOW;
		592	stdhdr = false;
		593
		594	pkt = new dns_packet;
		595
		596	pkt->id = next_id ();
		597	}
		598
		599	dns_snd::~dns_snd ()
		600	{
		601	delete pkt;
		602	}
		603
		604	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		605	{
		606	// add tunnel domain
		607	for (;;)
		608	{
		609	const char *end = strchr (domain, '.');
		610
		611	if (!end)
		612	end = domain + strlen (domain);
		613
		614	int len = end - domain;
		615
		616	pkt [offs++] = len;
		617	memcpy (pkt.at (offs), domain, len);
		618	offs += len;
		619
		620	if (!*end)
		621	break;
		622
		623	domain = end + 1;
		624	}
		625	}
		626
		627	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		628	{
		629	stdhdr = true;
		630	this->seqno = seqno;
		631
		632	timeout = NOW + INITIAL_TIMEOUT;
		633
		634	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		635	pkt->qdcount = htons (1);
		636
		637	int offs = 6*2;
		638	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
		639	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		640	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		641
		642	char enc[256], *encp = enc;
		643	encode_header (enc, THISNODE->id, seqno);
		644
		645	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		646
		647	if (datalen > stream.size ())
		648	datalen = stream.size ();
		649
		650	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		651	stream.remove (datalen);
		652
		653	while (enclen)
		654	{
		655	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		656
		657	(*pkt)[offs++] = lbllen;
		658	memcpy (pkt->at (offs), encp, lbllen);
		659
		660	offs += lbllen;
		661	encp += lbllen;
		662
		663	enclen -= lbllen;
		664	}
		665
		666	append_domain (*pkt, offs, dns->c->conf->domain);
		667
		668	(*pkt)[offs++] = 0;
		669	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		670	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		671
		672	pkt->len = offs;
		673	}
		674
		675	void dns_snd::gen_syn_req ()
		676	{
		677	timeout = NOW + INITIAL_SYN_TIMEOUT;
		678
		679	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		680	pkt->qdcount = htons (1);
		681
		682	int offs = 6 * 2;
		683
		684	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		685
		686	assert (elen <= MAX_LBL_SIZE);
		687
		688	(*pkt)[offs] = elen;
		689	offs += elen + 1;
		690	append_domain (*pkt, offs, dns->c->conf->domain);
		691
		692	(*pkt)[offs++] = 0;
		693	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
		694	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		695
		696	pkt->len = offs;
		697	}
		698
218	struct dns_rep	699	struct dns_rcv
219	{	700	{
		701	int seqno;
		702	dns_packet *pkt; // reply packet
		703	u8 data [MAXSIZE]; // actually part of the reply packet...
		704	int datalen;
		705
		706	dns_rcv (int seqno, u8 *data, int datalen);
		707	~dns_rcv ();
220	};	708	};
221		709
222	static u16 dns_id; // TODO: should be per-vpn	710	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
223		711	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
224	dns_req::dns_req (connection *c, vpn_packet *p, int &offs)
225	{	712	{
226	next = 0;	713	memcpy (this->data, data, datalen);
227	retry = 0;	714	}
228		715
229	pkt = new dns_packet;	716	dns_rcv::~dns_rcv ()
230		717	{
231	pkt->id = dns_id++;	718	delete pkt;
232	pkt->flags = DEFAULT_CLIENT_FLAGS;
233	pkt->qdcount = htons (1 * 0);
234	pkt->ancount = 0;
235	pkt->nscount = 0;
236	pkt->arcount = 0;
237
238	offs += 10000;
239
240	c->dns_sndq.push_back (this);
241	}	719	}
242		720
243	/////////////////////////////////////////////////////////////////////////////	721	/////////////////////////////////////////////////////////////////////////////
244		722
245	struct dns_cfg	723	dns_connection::dns_connection (connection *c)
		724	: c (c)
		725	, rcvdq (MAX_BACKLOG * 2)
		726	, snddq (MAX_BACKLOG)
		727	, tw (this, &dns_connection::time_cb)
246	{	728	{
247	u8 id1, id2, id3;	729	vpn = c->vpn;
248	u8 def_ttl;
249	u8 unused1;
250	u16 max_size;
251	u8 flags1, flags2;
252	};
253		730
254	// reply to client-poll	731	established = false;
255	void dnsv4_poll (dns_packet *pkt, int &offs)
256	{
257	int dlen = MAX_PKT_SIZE - offs - 2;
258		732
259	(*pkt) [offs++] = 0;	733	rcvseq = repseq = sndseq = 0;
260	(*pkt) [offs++] = 5;
261	memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5);
262	offs += 5;
263		734
264	pkt->ancount = htons (1);	735	last_sent = last_received = 0;
		736	poll_interval = 0.5; // starting here
		737	send_interval = 0.5; // starting rate
		738	min_latency = INITIAL_TIMEOUT;
		739	}
		740
		741	dns_connection::~dns_connection ()
		742	{
		743	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		744	i != rcvpq.end ();
		745	++i)
		746	delete *i;
		747	}
		748
		749	void dns_connection::receive_rep (dns_rcv *r)
		750	{
		751	if (r->datalen)
		752	{
		753	last_received = NOW;
		754	tw.trigger ();
		755
		756	poll_interval = send_interval;
		757	}
		758	else
		759	{
		760	poll_interval *= 1.5;
		761
		762	if (poll_interval > MAX_POLL_INTERVAL)
		763	poll_interval = MAX_POLL_INTERVAL;
		764	}
		765
		766	rcvpq.push_back (r);
		767
		768	redo:
		769
		770	// find next packet
		771	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		772	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		773	{
		774	// enter the packet into our input stream
		775	r = *i;
		776
		777	// remove the oldest packet, look forward, as it's oldest first
		778	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		779	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		780	{
		781	delete *j;
		782	rcvpq.erase (j);
		783	break;
		784	}
		785
		786	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		787
		788	if (!rcvdq.put (r->data, r->datalen))
		789	{
		790	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		791	abort (); // MUST never overflow, can be caused by data corruption, TODO
		792	}
		793
		794	while (vpn_packet *pkt = rcvdq.get ())
		795	{
		796	sockinfo si;
		797	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
		798
		799	vpn->recv_vpn_packet (pkt, si);
		800
		801	delete pkt;
		802	}
		803
		804	// check for further packets
		805	goto redo;
		806	}
		807	}
		808
		809	void
		810	vpn::dnsv4_server (dns_packet &pkt)
		811	{
		812	u16 flags = ntohs (pkt.flags);
		813
		814	int offs = 6 * 2; // skip header
		815
265	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	816	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
266		817
267	printf ("we have room for %d bytes\n", dlen);	818	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
		819	&& pkt.qdcount == htons (1))
		820	{
		821	char qname [MAXSIZE];
		822	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		823
		824	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
		825	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
		826
		827	pkt.qdcount = htons (1);
		828	pkt.ancount = 0;
		829	pkt.nscount = 0; // should be self, as other nameservers reply like this
		830	pkt.arcount = 0; // a record for self, as other nameservers reply like this
		831
		832	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
		833
		834	int dlen = strlen (THISNODE->domain);
		835
		836	if (qclass == RR_CLASS_IN
		837	&& qlen > dlen + 1
		838	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
		839	{
		840	// now generate reply
		841	pkt.ancount = htons (1); // one answer RR
		842	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
		843
		844	if ((qtype == RR_TYPE_ANY
		845	|| qtype == RR_TYPE_TXT
		846	|| qtype == RR_TYPE_NULL)
		847	&& qlen > dlen + 1 + HDRSIZE)
		848	{
		849	// correct class, domain: parse
		850	int client, seqno;
		851	decode_header (qname, client, seqno);
		852
		853	u8 data[MAXSIZE];
		854	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		855
		856	if (0 < client && client <= conns.size ())
		857	{
		858	connection *c = conns [client - 1];
		859	dns_connection *dns = c->dns;
		860	dns_rcv *rcv;
		861
		862	if (dns)
		863	{
		864	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		865	if (SEQNO_EQ ((*i)->seqno, seqno))
		866	{
		867	// already seen that request: simply reply with the cached reply
		868	dns_rcv *r = *i;
		869
		870	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		871
		872	// refresh header & id, as the retry count could have changed
		873	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		874	r->pkt->id = pkt.id;
		875
		876	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		877
		878	goto duplicate_request;
		879	}
		880
		881	// new packet, queue
		882	rcv = new dns_rcv (seqno, data, datalen);
		883	dns->receive_rep (rcv);
		884	}
		885
		886	{
		887	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		888
		889	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		890	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		891	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		892	pkt [offs++] = 0; pkt [offs++] = 0;
		893	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		894
		895	int rdlen_offs = offs += 2;
		896
		897	if (dns)
		898	{
		899	int dlen = ntohs (dns->cfg.max_size) - offs;
		900
		901	// bind doesn't compress well, so reduce further by one label length
		902	dlen -= qlen;
		903
		904	// only put data into in-order sequence packets, if
		905	// we receive out-of-order packets we generate empty
		906	// replies
		907	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		908	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		909	{
		910	dns->repseq = seqno;
		911
		912	while (dlen > 1 && !dns->snddq.empty ())
		913	{
		914	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		915
		916	if (txtlen > dns->snddq.size ())
		917	txtlen = dns->snddq.size ();
		918
		919	pkt[offs++] = txtlen;
		920	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		921	offs += txtlen;
		922	dns->snddq.remove (txtlen);
		923
		924	dlen -= txtlen + 1;
		925	}
		926	}
		927
		928	// avoid completely empty TXT rdata
		929	if (offs == rdlen_offs)
		930	pkt[offs++] = 0;
		931
		932	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		933	}
		934	else
		935	{
		936	// send RST
		937	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		938	pkt [offs++] = CMD_IP_RST;
		939	}
		940
		941	int rdlen = offs - rdlen_offs;
		942
		943	pkt [rdlen_offs - 2] = rdlen >> 8;
		944	pkt [rdlen_offs - 1] = rdlen;
		945
		946	if (dns)
		947	{
		948	// now update dns_rcv copy
		949	rcv->pkt->len = offs;
		950	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		951	}
		952	}
		953
		954	duplicate_request: ;
		955	}
		956	else
		957	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		958	}
		959	else if (qtype == RR_TYPE_A
		960	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		961	{
		962	dns_cfg cfg;
		963	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		964	int client = ntohs (cfg.client);
		965
		966	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		967
		968	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
		969	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		970	pkt [offs++] = 0; pkt [offs++] = 0;
		971	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		972	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		973
		974	slog (L_INFO, _("DNS: client %d connects"), client);
		975
		976	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		977	pkt [offs++] = CMD_IP_REJ;
		978
		979	if (0 < client && client <= conns.size ())
		980	{
		981	connection *c = conns [client - 1];
		982
		983	if (cfg.valid ())
		984	{
		985	pkt [offs - 1] = CMD_IP_SYN;
		986
		987	delete c->dns;
		988	c->dns = new dns_connection (c);
		989	c->dns->cfg = cfg;
		990	}
		991	}
		992	}
		993	}
		994
		995	pkt.len = offs;
		996	}
		997	}
		998
		999	void
		1000	vpn::dnsv4_client (dns_packet &pkt)
		1001	{
		1002	u16 flags = ntohs (pkt.flags);
		1003	int offs = 6 * 2; // skip header
		1004
		1005	pkt.qdcount = ntohs (pkt.qdcount);
		1006	pkt.ancount = ntohs (pkt.ancount);
		1007
		1008	// go through our request list and find the corresponding request
		1009	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
		1010	i != dns_sndpq.end ();
		1011	++i)
		1012	if ((*i)->pkt->id == pkt.id)
		1013	{
		1014	dns_connection *dns = (*i)->dns;
		1015	connection *c = dns->c;
		1016	int seqno = (*i)->seqno;
		1017	u8 data[MAXSIZE], *datap = data;
		1018
		1019	if ((*i)->retry)
		1020	{
		1021	dns->send_interval *= 1.01;
		1022	if (dns->send_interval > MAX_SEND_INTERVAL)
		1023	dns->send_interval = MAX_SEND_INTERVAL;
		1024	}
		1025	else
		1026	{
		1027	#if 0
		1028	dns->send_interval *= 0.999;
		1029	#endif
		1030	// the latency surely puts an upper bound on
		1031	// the minimum send interval
		1032	double latency = NOW - (*i)->sent;
		1033
		1034	if (latency < dns->min_latency)
		1035	dns->min_latency = latency;
		1036
		1037	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1038	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1039
		1040	if (dns->send_interval < conf.dns_send_interval)
		1041	dns->send_interval = conf.dns_send_interval;
		1042	}
		1043
		1044	delete *i;
		1045	dns_sndpq.erase (i);
		1046
		1047	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
		1048	{
		1049	char qname[MAXSIZE];
		1050
		1051	while (pkt.qdcount-- && offs < MAXSIZE - 4)
		1052	{
		1053	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1054	offs += 4; // skip qtype, qclass
		1055	}
		1056
		1057	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
		1058	{
		1059	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1060
		1061	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
		1062	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
		1063	u32 ttl = pkt [offs++] << 24;
		1064	ttl |= pkt [offs++] << 16;
		1065	ttl |= pkt [offs++] << 8;
		1066	ttl |= pkt [offs++];
		1067	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
		1068
		1069	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
		1070	{
		1071	if (rdlen <= MAXSIZE - offs)
		1072	{
		1073	// decode bytes, finally
		1074
		1075	while (rdlen)
		1076	{
		1077	int txtlen = pkt [offs++];
		1078
		1079	assert (txtlen + offs < MAXSIZE - 1);
		1080
		1081	memcpy (datap, pkt.at (offs), txtlen);
		1082	datap += txtlen; offs += txtlen;
		1083
		1084	rdlen -= txtlen + 1;
		1085	}
		1086	}
		1087	}
		1088	else if (qtype == RR_TYPE_A)
		1089	{
		1090	u8 ip [4];
		1091
		1092	ip [0] = pkt [offs++];
		1093	ip [1] = pkt [offs++];
		1094	ip [2] = pkt [offs++];
		1095	ip [3] = pkt [offs++];
		1096
		1097	if (ip [0] == CMD_IP_1
		1098	&& ip [1] == CMD_IP_2
		1099	&& ip [2] == CMD_IP_3)
		1100	{
		1101	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1102
		1103	if (ip [3] == CMD_IP_RST)
		1104	{
		1105	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1106
		1107	delete dns; c->dns = 0;
		1108
		1109	return;
		1110	}
		1111	else if (ip [3] == CMD_IP_SYN)
		1112	{
		1113	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1114	dns->established = true;
		1115	}
		1116	else if (ip [3] == CMD_IP_REJ)
		1117	{
		1118	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1119	abort ();
		1120	}
		1121	else
		1122	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1123	}
		1124	else
		1125	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1126	ip [0], ip [1], ip [2], ip [3]);
		1127
		1128	return;
		1129	}
		1130
		1131	int client, rseqno;
		1132	decode_header (qname, client, rseqno);
		1133
		1134	if (client != THISNODE->id)
		1135	{
		1136	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1137	datap = 0;
		1138	}
		1139	else if (rseqno != seqno)
		1140	{
		1141	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1142	datap = 0;
		1143	}
		1144	}
		1145	}
		1146
		1147	// todo: pkt now used
		1148	if (datap)
		1149	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1150
		1151	break;
		1152	}
268	}	1153	}
269		1154
270	void	1155	void
271	vpn::dnsv4_ev (io_watcher &w, short revents)	1156	vpn::dnsv4_ev (io_watcher &w, short revents)
272	{	1157	{
…		…
274	{	1159	{
275	dns_packet *pkt = new dns_packet;	1160	dns_packet *pkt = new dns_packet;
276	struct sockaddr_in sa;	1161	struct sockaddr_in sa;
277	socklen_t sa_len = sizeof (sa);	1162	socklen_t sa_len = sizeof (sa);
278		1163
279	int len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1164	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
280	pkt->len = len;
281		1165
282	u16 flags = ntohs (pkt->flags);	1166	if (pkt->len > 0)
283
284	if (THISNODE->dns_port)
285	{	1167	{
286	// server	1168	if (ntohs (pkt->flags) & FLAG_RESPONSE)
287	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	1169	dnsv4_client (*pkt);
288		1170	else
289	int offs = 6 * 2; // skip header
290
291	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))
292	&& pkt->qdcount == htons (1))
293	{	1171	{
294	char qname[MAXSIZE];	1172	dnsv4_server (*pkt);
295	int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs);	1173	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
		1174	}
296		1175
297	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len,	1176	delete pkt;
298	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D	1177	}
		1178	}
		1179	}
299		1180
300	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1181	bool
301	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1182	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
		1183	{
		1184	int client = ntohl (si.host);
302		1185
303	pkt->qdcount = htons (1);	1186	assert (0 < client && client <= conns.size ());
304	pkt->ancount = 0;
305	pkt->nscount = 0; // should be self, as other nameservers reply like this
306	pkt->arcount = 0; // a record for self, as other nameservers reply like this
307		1187
308	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	1188	connection *c = conns [client - 1];
309		1189
310	int dlen = strlen (THISNODE->domain);	1190	if (!c->dns)
		1191	c->dns = new dns_connection (c);
		1192
		1193	if (c->dns->snddq.put (pkt))
		1194	c->dns->tw.trigger ();
311		1195
312	if (qclass == RR_CLASS_IN	1196	// always return true even if the buffer overflows
313	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)	1197	return true;
314	&& qlen > dlen + 1	1198	}
315	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	1199
		1200	void
		1201	connection::dnsv4_reset_connection ()
		1202	{
		1203	//delete dns; dns = 0; //TODO
		1204	}
		1205
		1206	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1207
		1208	void
		1209	dns_connection::time_cb (time_watcher &w)
		1210	{
		1211	// servers have to be polled
		1212	if (THISNODE->dns_port)
		1213	return;
		1214
		1215	// check for timeouts and (re)transmit
		1216	tstamp next = NOW + poll_interval;
		1217	dns_snd *send = 0;
		1218
		1219	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
		1220	i != vpn->dns_sndpq.end ();
		1221	++i)
		1222	{
		1223	dns_snd *r = *i;
		1224
		1225	if (r->timeout <= NOW)
		1226	{
		1227	if (!send)
		1228	{
		1229	send = r;
		1230
		1231	r->retry++;
		1232	r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
		1233
		1234	// the following code changes the query section a bit, forcing
		1235	// the forwarder to generate a new request
		1236	if (r->stdhdr)
316	{	1237	{
317	// correct class, now generate reply	1238	//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
318	pkt->ancount = htons (1); // one answer RR	1239	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
319
320	(*pkt) [offs++] = 0xc0;
321	(*pkt) [offs++] = 6 * 2; // same as in query section
322
323	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;
324	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;
325
326	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;
327	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL
328
329	dnsv4_poll (pkt, offs);
330	printf ("correct class\n");
331	}	1240	}
332	}	1241	}
333
334	sendto (w.fd, &((*pkt)[0]), offs, 0, (sockaddr *)&sa, sa_len);
335	}	1242	}
336	else	1243	else
		1244	NEXT (r->timeout);
		1245	}
		1246
		1247	if (!send)
		1248	{
		1249	// generate a new packet, if wise
		1250
		1251	if (!established)
337	{	1252	{
338	// client	1253	if (vpn->dns_sndpq.empty ())
		1254	{
		1255	send = new dns_snd (this);
		1256
		1257	cfg.reset (THISNODE->id);
		1258	send->gen_syn_req ();
		1259	}
339	}	1260	}
340	}	1261	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
341	}	1262	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
342
343	bool
344	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
345	{
346	if (dns_sndq.size () >= MAX_OUTSTANDING)
347	return false;
348
349	// split vpn packet into dns packets, add to sndq
350	for (int offs = 0; offs < pkt->len; )
351	new dns_req (this, pkt, offs);
352
353	// force transmit
354	dnsv4_cb (dnsv4_tw);
355
356	return true;
357	}
358
359	void
360	connection::dnsv4_cb (time_watcher &w)
361	{
362	// check for timeouts and (re)transmit
363	tstamp next = NOW + 60;
364
365	slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), dns_sndq.size ());
366
367	if (dns_sndq.empty ())
368	{
369	next = NOW + 1;
370	// push poll packet
371	}
372
373	for (vector<dns_req *>::iterator i = dns_sndq.begin ();
374	i != dns_sndq.end ();
375	++i)
376	{
377	dns_req *r = *i;
378
379	if (r->next <= NOW)
380	{	1263	{
381	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);	1264	if (last_sent + send_interval <= NOW)
382	r->retry++;	1265	{
383	r->next = NOW + r->retry;	1266	//printf ("sending data request etc.\n"); //D
		1267	if (!snddq.empty () || last_received + 1. > NOW)
		1268	{
		1269	poll_interval = send_interval;
		1270	NEXT (NOW + send_interval);
		1271	}
		1272
		1273	send = new dns_snd (this);
		1274	send->gen_stream_req (sndseq, snddq);
		1275	send->timeout = NOW + min_latency * conf.dns_timeout_factor;
		1276
		1277	sndseq = (sndseq + 1) & SEQNO_MASK;
		1278	}
		1279	else
		1280	NEXT (last_sent + send_interval);
384	}	1281	}
385		1282
386	if (r->next < next)	1283	if (send)
387	next = r->next;	1284	vpn->dns_sndpq.push_back (send);
		1285	}
		1286
		1287	if (send)
388	}	1288	{
		1289	last_sent = NOW;
		1290	sendto (vpn->dnsv4_fd,
		1291	send->pkt->at (0), send->pkt->len, 0,
		1292	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1293	}
389		1294
390	printf ("%f next\n", next);	1295	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1296	poll_interval, send_interval, next - NOW,
		1297	vpn->dns_sndpq.size (), snddq.size (),
		1298	rcvpq.size ());
		1299
		1300	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1301	// doesn't seem to happen anymore
		1302	if (next < NOW + 0.001)
		1303	next = NOW + 0.1;
		1304
391	w.start (next);	1305	w.start (next);
392	}	1306	}
393		1307
394	#endif	1308	#endif
395		1309

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