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

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.3 by pcg, Tue Mar 1 06:27:20 2005 UTC vs.
Revision 1.42 by pcg, Sat Nov 10 05:14:22 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 <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	// although the protocol itself allows for some configurability,
		467	// only the following encoding/decoding settings are implemented.
		468	return id1 == 'G'
		469	&& id2 == 'V'
		470	&& id3 == 'P'
		471	&& id4 == 'E'
		472	&& seq_cdc == 26
		473	&& req_cdc == 62
		474	&& rep_cdc == 0
		475	&& version == 1;
		476	}
161		477
162	struct dns_packet : net_packet	478	struct dns_packet : net_packet
163	{	479	{
164	u16 id;	480	u16 id;
165	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	481	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
166	u16 qdcount, ancount, nscount, arcount;	482	u16 qdcount, ancount, nscount, arcount;
167		483
168	u8 data[MAXSIZE - 6 * 2];	484	u8 data [MAXSIZE - 6 * 2];
169		485
170	int decode_label (char *data, int size, int &offs);	486	int decode_label (char *data, int size, int &offs);
171	};	487	};
172		488
173	int dns_packet::decode_label (char *data, int size, int &offs)	489	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
204	return data - orig;	520	return data - orig;
205	}	521	}
206		522
207	/////////////////////////////////////////////////////////////////////////////	523	/////////////////////////////////////////////////////////////////////////////
208		524
		525	static u16 dns_id = 0; // TODO: should be per-vpn
		526
		527	static u16 next_id ()
		528	{
		529	if (!dns_id)
		530	dns_id = time (0);
		531
		532	// the simplest lsfr with periodicity 65535 i could find
		533	dns_id = (dns_id << 1)
		534	\| (((dns_id >> 1)
		535	^ (dns_id >> 2)
		536	^ (dns_id >> 4)
		537	^ (dns_id >> 15)) & 1);
		538
		539	return dns_id;
		540	}
		541
209	struct dns_req	542	struct dns_rcv;
		543	struct dns_snd;
		544
		545	struct dns_connection
		546	{
		547	connection *c;
		548	struct vpn *vpn;
		549
		550	dns_cfg cfg;
		551
		552	bool established;
		553
		554	tstamp last_received;
		555	tstamp last_sent;
		556	double min_latency;
		557	double poll_interval, send_interval;
		558
		559	vector<dns_rcv *> rcvpq;
		560
		561	byte_stream rcvdq; int rcvseq; int repseq;
		562	byte_stream snddq; int sndseq;
		563
		564	void time_cb (ev::timer &w, int revents); ev::timer tw;
		565	void receive_rep (dns_rcv *r);
		566
		567	dns_connection (connection *c);
		568	~dns_connection ();
		569	};
		570
		571	struct dns_snd
210	{	572	{
211	dns_packet *pkt;	573	dns_packet *pkt;
212	tstamp next;	574	tstamp timeout, sent;
213	int retry;	575	int retry;
		576	struct dns_connection *dns;
		577	int seqno;
		578	bool stdhdr;
214		579
215	dns_req (connection c, vpn_packet p, int &offs);	580	void gen_stream_req (int seqno, byte_stream &stream);
		581	void gen_syn_req ();
		582
		583	dns_snd (dns_connection *dns);
		584	~dns_snd ();
216	};	585	};
217		586
		587	dns_snd::dns_snd (dns_connection *dns)
		588	: dns (dns)
		589	{
		590	timeout = 0;
		591	retry = 0;
		592	seqno = 0;
		593	sent = ev::ev_now ();
		594	stdhdr = false;
		595
		596	pkt = new dns_packet;
		597
		598	pkt->id = next_id ();
		599	}
		600
		601	dns_snd::~dns_snd ()
		602	{
		603	delete pkt;
		604	}
		605
		606	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		607	{
		608	// add tunnel domain
		609	for (;;)
		610	{
		611	const char *end = strchr (domain, '.');
		612
		613	if (!end)
		614	end = domain + strlen (domain);
		615
		616	int len = end - domain;
		617
		618	pkt [offs++] = len;
		619	memcpy (pkt.at (offs), domain, len);
		620	offs += len;
		621
		622	if (!*end)
		623	break;
		624
		625	domain = end + 1;
		626	}
		627	}
		628
		629	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		630	{
		631	stdhdr = true;
		632	this->seqno = seqno;
		633
		634	timeout = ev::ev_now () + INITIAL_TIMEOUT;
		635
		636	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		637	pkt->qdcount = htons (1);
		638
		639	int offs = 6*2;
		640	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
		641	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		642	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		643
		644	char enc[256], *encp = enc;
		645	encode_header (enc, THISNODE->id, seqno);
		646
		647	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		648
		649	if (datalen > stream.size ())
		650	datalen = stream.size ();
		651
		652	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		653	stream.remove (datalen);
		654
		655	while (enclen)
		656	{
		657	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		658
		659	(*pkt)[offs++] = lbllen;
		660	memcpy (pkt->at (offs), encp, lbllen);
		661
		662	offs += lbllen;
		663	encp += lbllen;
		664
		665	enclen -= lbllen;
		666	}
		667
		668	append_domain (*pkt, offs, dns->c->conf->domain);
		669
		670	(*pkt)[offs++] = 0;
		671	(pkt)[offs++] = RR_TYPE_ANY >> 8; (pkt)[offs++] = RR_TYPE_ANY;
		672	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		673
		674	pkt->len = offs;
		675	}
		676
		677	void dns_snd::gen_syn_req ()
		678	{
		679	timeout = ev::ev_now () + INITIAL_SYN_TIMEOUT;
		680
		681	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		682	pkt->qdcount = htons (1);
		683
		684	int offs = 6 * 2;
		685
		686	int elen = cdc26.encode ((char )pkt->at (offs + 1), (u8 )&dns->cfg, sizeof (dns_cfg));
		687
		688	assert (elen <= MAX_LBL_SIZE);
		689
		690	(*pkt)[offs] = elen;
		691	offs += elen + 1;
		692	append_domain (*pkt, offs, dns->c->conf->domain);
		693
		694	(*pkt)[offs++] = 0;
		695	(pkt)[offs++] = RR_TYPE_A >> 8; (pkt)[offs++] = RR_TYPE_A;
		696	(pkt)[offs++] = RR_CLASS_IN >> 8; (pkt)[offs++] = RR_CLASS_IN;
		697
		698	pkt->len = offs;
		699	}
		700
218	struct dns_rep	701	struct dns_rcv
219	{	702	{
		703	int seqno;
		704	dns_packet *pkt; // reply packet
		705	u8 data [MAXSIZE]; // actually part of the reply packet...
		706	int datalen;
		707
		708	dns_rcv (int seqno, u8 *data, int datalen);
		709	~dns_rcv ();
220	};	710	};
221		711
222	static u16 dns_id; // TODO: should be per-vpn	712	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
223		713	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
224	dns_req::dns_req (connection c, vpn_packet p, int &offs)
225	{	714	{
226	next = 0;	715	memcpy (this->data, data, datalen);
227	retry = 0;	716	}
228		717
229	pkt = new dns_packet;	718	dns_rcv::~dns_rcv ()
230		719	{
231	pkt->id = dns_id++;	720	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	}	721	}
242		722
243	/////////////////////////////////////////////////////////////////////////////	723	/////////////////////////////////////////////////////////////////////////////
244		724
245	struct dns_cfg	725	dns_connection::dns_connection (connection *c)
		726	: c (c)
		727	, rcvdq (MAX_BACKLOG * 2)
		728	, snddq (MAX_BACKLOG)
		729	, tw (this, &dns_connection::time_cb)
246	{	730	{
247	u8 id1, id2, id3;	731	vpn = c->vpn;
248	u8 def_ttl;
249	u8 unused1;
250	u16 max_size;
251	u8 flags1, flags2;
252	};
253		732
254	// reply to client-poll	733	established = false;
255	void dnsv4_poll (dns_packet *pkt, int &offs)
256	{
257	int dlen = MAX_PKT_SIZE - offs - 2;
258		734
259	(*pkt) [offs++] = 0;	735	rcvseq = repseq = sndseq = 0;
260	(*pkt) [offs++] = 5;
261	memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5);
262	offs += 5;
263		736
264	pkt->ancount = htons (1);	737	last_sent = last_received = 0;
265	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);	738	poll_interval = 0.5; // starting here
		739	send_interval = 0.5; // starting rate
		740	min_latency = INITIAL_TIMEOUT;
		741	}
266		742
267	printf ("we have room for %d bytes\n", dlen);	743	dns_connection::~dns_connection ()
		744	{
		745	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		746	i != rcvpq.end ();
		747	++i)
		748	delete *i;
		749	}
		750
		751	void dns_connection::receive_rep (dns_rcv *r)
		752	{
		753	if (r->datalen)
		754	{
		755	last_received = ev::ev_now ();
		756	tw ();
		757
		758	poll_interval = send_interval;
		759	}
		760	else
		761	{
		762	poll_interval *= 1.5;
		763
		764	if (poll_interval > MAX_POLL_INTERVAL)
		765	poll_interval = MAX_POLL_INTERVAL;
		766	}
		767
		768	rcvpq.push_back (r);
		769
		770	redo:
		771
		772	// find next packet
		773	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		774	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		775	{
		776	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		777	// enter the packet into our input stream
		778	r = *i;
		779
		780	// remove the oldest packet, look forward, as it's oldest first
		781	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		782	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		783	{
		784	//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
		785	delete *j;
		786	rcvpq.erase (j);
		787	break;
		788	}
		789
		790	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		791
		792	if (!rcvdq.put (r->data, r->datalen))
		793	{
		794	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		795	abort (); // MUST never overflow, can be caused by data corruption, TODO
		796	}
		797
		798	while (vpn_packet *pkt = rcvdq.get ())
		799	{
		800	sockinfo si;
		801	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
		802
		803	vpn->recv_vpn_packet (pkt, si);
		804
		805	delete pkt;
		806	}
		807
		808	// check for further packets
		809	goto redo;
		810	}
268	}	811	}
269		812
270	void	813	void
		814	vpn::dnsv4_server (dns_packet &pkt)
		815	{
		816	u16 flags = ntohs (pkt.flags);
		817
		818	int offs = 6 * 2; // skip header
		819
		820	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		821
		822	if (0 == (flags & (FLAG_RESPONSE \| FLAG_OP_MASK))
		823	&& pkt.qdcount == htons (1))
		824	{
		825	char qname [MAXSIZE];
		826	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		827
		828	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		829	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		830
		831	pkt.qdcount = htons (1);
		832	pkt.ancount = 0;
		833	pkt.nscount = 0; // should be self, as other nameservers reply like this
		834	pkt.arcount = 0; // a record for self, as other nameservers reply like this
		835
		836	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_SERVFAIL);
		837
		838	int dlen = strlen (THISNODE->domain);
		839
		840	if (qclass == RR_CLASS_IN
		841	&& qlen > dlen + 1
		842	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
		843	{
		844	// now generate reply
		845	pkt.ancount = htons (1); // one answer RR
		846	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_OK);
		847
		848	if ((qtype == RR_TYPE_ANY
		849	\|\| qtype == RR_TYPE_TXT
		850	\|\| qtype == RR_TYPE_NULL)
		851	&& qlen > dlen + 1 + HDRSIZE)
		852	{
		853	// correct class, domain: parse
		854	int client, seqno;
		855	decode_header (qname, client, seqno);
		856
		857	u8 data[MAXSIZE];
		858	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		859
		860	if (0 < client && client <= conns.size ())
		861	{
		862	connection *c = conns [client - 1];
		863	dns_connection *dns = c->dns;
		864	dns_rcv *rcv;
		865
		866	if (dns)
		867	{
		868	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		869	if (SEQNO_EQ ((*i)->seqno, seqno))
		870	{
		871	// already seen that request: simply reply with the cached reply
		872	dns_rcv r = i;
		873
		874	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		875
		876	// refresh header & id, as the retry count could have changed
		877	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		878	r->pkt->id = pkt.id;
		879
		880	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		881
		882	goto duplicate_request;
		883	}
		884
		885	// new packet, queue
		886	rcv = new dns_rcv (seqno, data, datalen);
		887	dns->receive_rep (rcv);
		888	}
		889
		890	{
		891	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		892
		893	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		894	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		895	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		896	pkt [offs++] = 0; pkt [offs++] = 0;
		897	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		898
		899	int rdlen_offs = offs += 2;
		900
		901	if (dns)
		902	{
		903	int dlen = ntohs (dns->cfg.max_size) - offs;
		904
		905	// bind doesn't compress well, so reduce further by one label length
		906	dlen -= qlen;
		907
		908	// only put data into in-order sequence packets, if
		909	// we receive out-of-order packets we generate empty
		910	// replies
		911	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		912	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		913	{
		914	dns->repseq = seqno;
		915
		916	while (dlen > 1 && !dns->snddq.empty ())
		917	{
		918	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		919
		920	if (txtlen > dns->snddq.size ())
		921	txtlen = dns->snddq.size ();
		922
		923	pkt[offs++] = txtlen;
		924	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		925	offs += txtlen;
		926	dns->snddq.remove (txtlen);
		927
		928	dlen -= txtlen + 1;
		929	}
		930	}
		931
		932	// avoid completely empty TXT rdata
		933	if (offs == rdlen_offs)
		934	pkt[offs++] = 0;
		935
		936	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		937	}
		938	else
		939	{
		940	// send RST
		941	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		942	pkt [offs++] = CMD_IP_RST;
		943	}
		944
		945	int rdlen = offs - rdlen_offs;
		946
		947	pkt [rdlen_offs - 2] = rdlen >> 8;
		948	pkt [rdlen_offs - 1] = rdlen;
		949
		950	if (dns)
		951	{
		952	// now update dns_rcv copy
		953	rcv->pkt->len = offs;
		954	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		955	}
		956	}
		957
		958	duplicate_request: ;
		959	}
		960	else
		961	pkt.flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);
		962	}
		963	else if (qtype == RR_TYPE_A
		964	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		965	{
		966	dns_cfg cfg;
		967	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		968	int client = ntohs (cfg.client);
		969
		970	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		971
		972	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
		973	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		974	pkt [offs++] = 0; pkt [offs++] = 0;
		975	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		976	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		977
		978	slog (L_INFO, _("DNS: client %d connects"), client);
		979
		980	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		981	pkt [offs++] = CMD_IP_REJ;
		982
		983	if (0 < client && client <= conns.size ())
		984	{
		985	connection *c = conns [client - 1];
		986
		987	if (cfg.valid ())
		988	{
		989	pkt [offs - 1] = CMD_IP_SYN;
		990
		991	delete c->dns;
		992	c->dns = new dns_connection (c);
		993	c->dns->cfg = cfg;
		994	}
		995	}
		996	}
		997	}
		998
		999	pkt.len = offs;
		1000	}
		1001	}
		1002
		1003	void
		1004	vpn::dnsv4_client (dns_packet &pkt)
		1005	{
		1006	u16 flags = ntohs (pkt.flags);
		1007	int offs = 6 * 2; // skip header
		1008
		1009	pkt.qdcount = ntohs (pkt.qdcount);
		1010	pkt.ancount = ntohs (pkt.ancount);
		1011
		1012	// go through our request list and find the corresponding request
		1013	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
		1014	i != dns_sndpq.end ();
		1015	++i)
		1016	if ((*i)->pkt->id == pkt.id)
		1017	{
		1018	dns_connection dns = (i)->dns;
		1019	connection *c = dns->c;
		1020	int seqno = (*i)->seqno;
		1021	u8 data[MAXSIZE], *datap = data;
		1022	//printf ("rcv pkt %x\n", seqno);//D
		1023
		1024	if ((*i)->retry)
		1025	{
		1026	dns->send_interval *= 1.01;
		1027	if (dns->send_interval > MAX_SEND_INTERVAL)
		1028	dns->send_interval = MAX_SEND_INTERVAL;
		1029	}
		1030	else
		1031	{
		1032	#if 0
		1033	dns->send_interval *= 0.999;
		1034	#endif
		1035	// the latency surely puts an upper bound on
		1036	// the minimum send interval
		1037	double latency = ev::ev_now () - (*i)->sent;
		1038
		1039	if (latency < dns->min_latency)
		1040	dns->min_latency = latency;
		1041
		1042	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1043	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1044
		1045	if (dns->send_interval < conf.dns_send_interval)
		1046	dns->send_interval = conf.dns_send_interval;
		1047	}
		1048
		1049	delete *i;
		1050	dns_sndpq.erase (i);
		1051
		1052	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
		1053	{
		1054	char qname[MAXSIZE];
		1055
		1056	while (pkt.qdcount-- && offs < MAXSIZE - 4)
		1057	{
		1058	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1059	offs += 4; // skip qtype, qclass
		1060	}
		1061
		1062	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
		1063	{
		1064	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
		1065
		1066	u16 qtype = pkt [offs++] << 8; qtype \|= pkt [offs++];
		1067	u16 qclass = pkt [offs++] << 8; qclass \|= pkt [offs++];
		1068	u32 ttl = pkt [offs++] << 24;
		1069	ttl \|= pkt [offs++] << 16;
		1070	ttl \|= pkt [offs++] << 8;
		1071	ttl \|= pkt [offs++];
		1072	u16 rdlen = pkt [offs++] << 8; rdlen \|= pkt [offs++];
		1073
		1074	if (qtype == RR_TYPE_NULL \|\| qtype == RR_TYPE_TXT)
		1075	{
		1076	if (rdlen <= MAXSIZE - offs)
		1077	{
		1078	// decode bytes, finally
		1079
		1080	while (rdlen)
		1081	{
		1082	int txtlen = pkt [offs++];
		1083
		1084	assert (txtlen + offs < MAXSIZE - 1);
		1085
		1086	memcpy (datap, pkt.at (offs), txtlen);
		1087	datap += txtlen; offs += txtlen;
		1088
		1089	rdlen -= txtlen + 1;
		1090	}
		1091	}
		1092	}
		1093	else if (qtype == RR_TYPE_A)
		1094	{
		1095	u8 ip [4];
		1096
		1097	ip [0] = pkt [offs++];
		1098	ip [1] = pkt [offs++];
		1099	ip [2] = pkt [offs++];
		1100	ip [3] = pkt [offs++];
		1101
		1102	if (ip [0] == CMD_IP_1
		1103	&& ip [1] == CMD_IP_2
		1104	&& ip [2] == CMD_IP_3)
		1105	{
		1106	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1107
		1108	if (ip [3] == CMD_IP_RST)
		1109	{
		1110	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1111
		1112	delete dns; c->dns = 0;
		1113
		1114	return;
		1115	}
		1116	else if (ip [3] == CMD_IP_SYN)
		1117	{
		1118	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1119	dns->established = true;
		1120	}
		1121	else if (ip [3] == CMD_IP_REJ)
		1122	{
		1123	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1124	abort ();
		1125	}
		1126	else
		1127	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1128	}
		1129	else
		1130	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1131	ip [0], ip [1], ip [2], ip [3]);
		1132
		1133	return;
		1134	}
		1135
		1136	int client, rseqno;
		1137	decode_header (qname, client, rseqno);
		1138
		1139	if (client != THISNODE->id)
		1140	{
		1141	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1142	datap = 0;
		1143	}
		1144	else if (rseqno != seqno)
		1145	{
		1146	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1147	datap = 0;
		1148	}
		1149	}
		1150	}
		1151
		1152	// todo: pkt now used
		1153	if (datap)
		1154	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1155
		1156	break;
		1157	}
		1158	}
		1159
		1160	void
271	vpn::dnsv4_ev (io_watcher &w, short revents)	1161	vpn::dnsv4_ev (ev::io &w, int revents)
272	{	1162	{
273	if (revents & EVENT_READ)	1163	if (revents & EV_READ)
274	{	1164	{
275	dns_packet *pkt = new dns_packet;	1165	dns_packet *pkt = new dns_packet;
276	struct sockaddr_in sa;	1166	struct sockaddr_in sa;
277	socklen_t sa_len = sizeof (sa);	1167	socklen_t sa_len = sizeof (sa);
278		1168
279	int len = recvfrom (w.fd, &((pkt)[0]), MAXSIZE, 0, (sockaddr )&sa, &sa_len);	1169	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
280	pkt->len = len;
281		1170
282	u16 flags = ntohs (pkt->flags);	1171	if (pkt->len > 0)
283
284	if (THISNODE->dns_port)
285	{	1172	{
286	// server	1173	if (ntohs (pkt->flags) & FLAG_RESPONSE)
287	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_FORMERR);	1174	dnsv4_client (*pkt);
288		1175	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	{	1176	{
294	char qname[MAXSIZE];	1177	dnsv4_server (*pkt);
295	int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs);	1178	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
296
297	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len,
298	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
299
300	u16 qtype = (pkt) [offs++] << 8; qtype \|= (pkt) [offs++];
301	u16 qclass = (pkt) [offs++] << 8; qclass \|= (pkt) [offs++];
302
303	pkt->qdcount = htons (1);
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
308	pkt->flags = htons (DEFAULT_SERVER_FLAGS \| FLAG_RCODE_NXDOMAIN);
309
310	int dlen = strlen (THISNODE->domain);
311
312	if (qclass == RR_CLASS_IN
313	&& (qtype == RR_TYPE_ANY \|\| qtype == RR_TYPE_TXT)
314	&& qlen > dlen + 1
315	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
316	{
317	// correct class, now generate reply
318	pkt->ancount = htons (1); // one answer RR
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	}
332	}	1179	}
333		1180
334	sendto (w.fd, &((pkt)[0]), offs, 0, (sockaddr )&sa, sa_len);	1181	delete pkt;
		1182	}
		1183	}
		1184	}
		1185
		1186	bool
		1187	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
		1188	{
		1189	int client = ntohl (si.host);
		1190
		1191	assert (0 < client && client <= conns.size ());
		1192
		1193	connection *c = conns [client - 1];
		1194
		1195	if (!c->dns)
		1196	c->dns = new dns_connection (c);
		1197
		1198	if (c->dns->snddq.put (pkt))
		1199	c->dns->tw ();
		1200
		1201	// always return true even if the buffer overflows
		1202	return true;
		1203	}
		1204
		1205	void
		1206	connection::dnsv4_reset_connection ()
		1207	{
		1208	//delete dns; dns = 0; //TODO
		1209	}
		1210
		1211	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1212
		1213	void
		1214	dns_connection::time_cb (ev::timer &w, int revents)
		1215	{
		1216	// servers have to be polled
		1217	if (THISNODE->dns_port)
		1218	return;
		1219
		1220	// check for timeouts and (re)transmit
		1221	tstamp next = ev::now () + poll_interval;
		1222	dns_snd *send = 0;
		1223
		1224	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
		1225	i != vpn->dns_sndpq.end ();
		1226	++i)
		1227	{
		1228	dns_snd r = i;
		1229
		1230	if (r->timeout <= ev::ev_now ())
		1231	{
		1232	if (!send)
		1233	{
		1234	send = r;
		1235
		1236	r->retry++;
		1237	r->timeout = ev::ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
		1238	//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev::ev_now ());//D
		1239
		1240	// the following code changes the query section a bit, forcing
		1241	// the forwarder to generate a new request
		1242	if (r->stdhdr)
		1243	encode_header ((char )r->pkt->at (6 2 + 1), THISNODE->id, r->seqno, r->retry);
		1244	}
335	}	1245	}
336	else	1246	else
		1247	NEXT (r->timeout);
		1248	}
		1249
		1250	if (!send)
		1251	{
		1252	// generate a new packet, if wise
		1253
		1254	if (!established)
337	{	1255	{
338	// client	1256	if (vpn->dns_sndpq.empty ())
		1257	{
		1258	send = new dns_snd (this);
		1259
		1260	cfg.reset (THISNODE->id);
		1261	send->gen_syn_req ();
		1262	}
339	}	1263	}
340	}	1264	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
341	}	1265	&& !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	{	1266	{
381	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);	1267	if (last_sent + send_interval <= ev::ev_now ())
382	r->retry++;	1268	{
383	r->next = NOW + r->retry;	1269	//printf ("sending data request etc.\n"); //D
		1270	if (!snddq.empty () \|\| last_received + 1. > ev::ev_now ())
		1271	{
		1272	poll_interval = send_interval;
		1273	NEXT (ev::ev_now () + send_interval);
		1274	}
		1275
		1276	send = new dns_snd (this);
		1277	send->gen_stream_req (sndseq, snddq);
		1278	send->timeout = ev::ev_now () + min_latency * conf.dns_timeout_factor;
		1279	//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev::ev_now (), min_latency, conf.dns_timeout_factor);//D
		1280
		1281	sndseq = (sndseq + 1) & SEQNO_MASK;
		1282	}
		1283	else
		1284	NEXT (last_sent + send_interval);
384	}	1285	}
385		1286
386	if (r->next < next)	1287	if (send)
387	next = r->next;	1288	vpn->dns_sndpq.push_back (send);
		1289	}
		1290
		1291	if (send)
388	}	1292	{
		1293	last_sent = ev::ev_now ();
		1294	sendto (vpn->dnsv4_fd,
		1295	send->pkt->at (0), send->pkt->len, 0,
		1296	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1297	}
389		1298
390	printf ("%f next\n", next);	1299	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
391	w.start (next);	1300	poll_interval, send_interval, next - ev::ev_now (),
		1301	vpn->dns_sndpq.size (), snddq.size (),
		1302	rcvpq.size ());
		1303
		1304	// TODO: no idea when this happens, but when next < ev::ev_now (), we have a problem
		1305	// doesn't seem to happen anymore
		1306	if (next < ev::ev_now () + 0.001)
		1307	next = ev::ev_now () + 0.1;
		1308
		1309	w.start (next - ev::ev_now ());
392	}	1310	}
393		1311
394	#endif	1312	#endif
395		1313

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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 1.42 by pcg, Sat Nov 10 05:14:22 2007 UTC

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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 1.42 by pcg, Sat Nov 10 05:14:22 2007 UTC