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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.5 by pcg, Thu Mar 3 07:24:57 2005 UTC vs.
Revision 1.18 by pcg, Sat Mar 5 19:13:16 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
20	#include "config.h"	22	#include "config.h"
21		23
…		…
35	#include <unistd.h>	37	#include <unistd.h>
36	#include <fcntl.h>	38	#include <fcntl.h>
37		39
38	#include <map>	40	#include <map>
39		41
		42	#include <gmp.h>
		43
40	#include "netcompat.h"	44	#include "netcompat.h"
41		45
42	#include "vpn.h"	46	#include "vpn.h"
43		47
44	#define MIN_RETRY 1.	48	#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data
45	#define MAX_RETRY 60.	49	#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data
		50	#define ACTIVITY_INTERVAL 5.
46		51
		52	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		53	#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
		54
		55	#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
		56	#define MAX_SEND_INTERVAL 0.5 // optimistic?
		57
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	58	#define MAX_OUTSTANDING 10 // max. outstanding requests
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	59	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
49	#define MAX_RATE 1000 // requests/s
50	#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE	60	#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		61
52	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	62	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
53	// 240 leaves about 4 bytes of server reply data	63	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	64	// every two request bytes less give room for one reply byte
55		65
56	#define SEQNO_MASK 0xffff	66	#define SEQNO_MASK 0x3fff
57		67	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
58	/*
59
60	protocol, in shorthand :)
61
62	client -> server <req> ANY?
63	server -> client <req> TXT <rep>
64
65	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
66	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
67
68	if <client-id> is zero, the connection will be configured:
69
70	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
71
72	*/
73		68
74	#define MAX_LBL_SIZE 63	69	#define MAX_LBL_SIZE 63
75	#define MAX_PKT_SIZE 512	70	#define MAX_PKT_SIZE 512
76		71
		72	#define RR_TYPE_A 1
		73	#define RR_TYPE_NULL 10
77	#define RR_TYPE_TXT 16	74	#define RR_TYPE_TXT 16
78	#define RR_TYPE_ANY 255	75	#define RR_TYPE_ANY 255
		76
79	#define RR_CLASS_IN 1	77	#define RR_CLASS_IN 1
80		78
81	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	79	#define CMD_IP_1 207
82	struct dns64	80	#define CMD_IP_2 46
83	{	81	#define CMD_IP_3 236
84	static const char encode_chars[64 + 1];	82	#define CMD_IP_RST 29
85	static s8 decode_chars[256];	83	#define CMD_IP_SYN 113
		84	#define CMD_IP_REJ 32
86		85
87	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	86	// works for cmaps up to 255 (not 256!)
88	static int decode_len (int bytes) { return (bytes * 6) / 8; }	87	struct charmap
		88	{
		89	enum { INVALID = (u8)255 };
		90
		91	char encode [256]; // index => char
		92	u8 decode [256]; // char => index
		93	unsigned int size;
		94
		95	charmap (const char *cmap);
		96	};
		97
		98	charmap::charmap (const char *cmap)
		99	{
		100	char *enc = encode;
		101	u8 *dec = decode;
		102
		103	memset (enc, (char) 0, 256);
		104	memset (dec, (char)INVALID, 256);
		105
		106	for (size = 0; cmap [size]; size++)
		107	{
		108	enc [size] = cmap [size];
		109	dec [(u8)enc [size]] = size;
		110	}
		111
		112	assert (size < 256);
		113	}
		114
		115	#define MAX_DEC_LEN 500
		116	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		117	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		118
		119	// ugly. minimum base is 16(!)
		120	struct basecoder
		121	{
		122	charmap cmap;
		123	unsigned int enc_len [MAX_DEC_LEN];
		124	unsigned int dec_len [MAX_ENC_LEN];
		125
		126	unsigned int encode_len (unsigned int len);
		127	unsigned int decode_len (unsigned int len);
		128
89	static int encode (char *dst, u8 *src, int len);	129	unsigned int encode (char *dst, u8 *src, unsigned int len);
90	static int decode (u8 *dst, char *src, int len);	130	unsigned int decode (u8 *dst, char *src, unsigned int len);
91		131
92	dns64 ();	132	basecoder (const char *cmap);
93	} dns64;	133	};
94		134
95	const char dns64::encode_chars[64 + 1] = "_4B9dLphHzrqQmGjkTbJt5svlZX8xSaReEYfwKgF1DP2W6NyVOU70IouACcMn3i-";	135	basecoder::basecoder (const char *cmap)
96	s8 dns64::decode_chars[256];	136	: cmap (cmap)
97
98	dns64::dns64 ()
99	{	137	{
100	for (int i = 0; i < 64; i++)	138	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
101	decode_chars [encode_chars [i]] = i + 1;	139	{
102	}	140	u8 src [MAX_DEC_LEN];
		141	u8 dst [MAX_ENC_LEN];
103		142
104	int dns64::encode (char *dst, u8 *src, int len)	143	memset (src, 255, len);
		144
		145	mp_limb_t m [MAX_LIMBS];
		146	mp_size_t n;
		147
		148	n = mpn_set_str (m, src, len, 256);
		149	n = mpn_get_str (dst, this->cmap.size, m, n);
		150
		151	for (int i = 0; !dst [i]; ++i)
		152	n--;
		153
		154	enc_len [len] = n;
		155	dec_len [n] = len;
		156	}
		157	}
		158
		159	unsigned int basecoder::encode_len (unsigned int len)
105	{	160	{
106	// slow, but easy to debug	161	return enc_len [len];
107	char *beg = dst;	162	}
108	unsigned int accum, bits = 0;	163
		164	unsigned int basecoder::decode_len (unsigned int len)
		165	{
		166	while (len && !dec_len [len])
		167	--len;
		168
		169	return dec_len [len];
		170	}
		171
		172	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		173	{
		174	if (!len || len > MAX_DEC_LEN)
		175	return 0;
		176
		177	int elen = encode_len (len);
		178
		179	mp_limb_t m [MAX_LIMBS];
		180	mp_size_t n;
		181
		182	u8 dst_ [MAX_ENC_LEN];
		183
		184	n = mpn_set_str (m, src, len, 256);
		185	n = mpn_get_str (dst_, cmap.size, m, n);
		186
		187	int plen = elen; // for padding
		188
		189	while (n < plen)
		190	{
		191	*dst++ = cmap.encode [0];
		192	plen--;
		193	}
		194
		195	for (unsigned int i = n - plen; i < n; ++i)
		196	*dst++ = cmap.encode [dst_ [i]];
		197
		198	return elen;
		199	}
		200
		201	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		202	{
		203	if (!len || len > MAX_ENC_LEN)
		204	return 0;
		205
		206	u8 src_ [MAX_ENC_LEN];
		207	unsigned int elen = 0;
109		208
110	while (len--)	209	while (len--)
111	{	210	{
112	accum <<= 8;	211	u8 val = cmap.decode [(u8)*src++];
113	accum |= *src++;
114	bits += 8;
115		212
116	while (bits >= 6)	213	if (val != charmap::INVALID)
117	{	214	src_ [elen++] = val;
118	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	215	}
119	bits -= 6;	216
120	}	217	int dlen = decode_len (elen);
		218
		219	mp_limb_t m [MAX_LIMBS];
		220	mp_size_t n;
		221
		222	u8 dst_ [MAX_DEC_LEN];
		223
		224	n = mpn_set_str (m, src_, elen, cmap.size);
		225	n = mpn_get_str (dst_, 256, m, n);
		226
		227	if (n < dlen)
121	}	228	{
		229	memset (dst, 0, dlen - n);
		230	memcpy (dst + dlen - n, dst_, n);
		231	}
		232	else
		233	memcpy (dst, dst_ + n - dlen, dlen);
122		234
123	if (bits)	235	return dlen;
124	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
125
126	return dst - beg;
127	}	236	}
128		237
129	int dns64::decode (u8 *dst, char *src, int len)	238	#if 0
130	{	239	struct test { test (); } test;
131	// slow, but easy to debug
132	u8 *beg = dst;
133	unsigned int accum, bits = 0;
134		240
135	while (len--)	241	test::test ()
		242	{
		243	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		244
		245	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		246	static char enc[200];
		247	static u8 dec[200];
		248
		249	for (int i = 1; i < 20; i++)
136	{	250	{
137	s8 chr = decode_chars [(u8)*src++];	251	int elen = cdc.encode (enc, in, i);
		252	int dlen = cdc.decode (dec, enc, elen);
138		253
139	if (!chr)	254	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
140	continue;
141
142	accum <<= 6;
143	accum |= chr - 1;
144	bits += 6;
145
146	while (bits >= 8)
147	{
148	*dst++ = accum >> (bits - 8);
149	bits -= 8;
150	}
151	}	255	}
		256	abort ();
		257	}
		258	#endif
152		259
153	return dst - beg;	260	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		261	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		262	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		263	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		264	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		265
		266	/////////////////////////////////////////////////////////////////////////////
		267
		268	#define HDRSIZE 6
		269
		270	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		271	{
		272	seqno &= SEQNO_MASK;
		273
		274	u8 hdr[3] = {
		275	clientid,
		276	(seqno >> 8) | (retry << 6),
		277	seqno,
		278	};
		279
		280	assert (clientid < 256);
		281
		282	cdc26.encode (data, hdr, 3);
		283	}
		284
		285	inline void decode_header (char *data, int &clientid, int &seqno)
		286	{
		287	u8 hdr[3];
		288
		289	cdc26.decode (hdr, data, HDRSIZE);
		290
		291	clientid = hdr[0];
		292	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
154	}	293	}
155		294
156	/////////////////////////////////////////////////////////////////////////////	295	/////////////////////////////////////////////////////////////////////////////
157		296
158	struct byte_stream	297	struct byte_stream
…		…
187	}	326	}
188		327
189	void byte_stream::remove (int count)	328	void byte_stream::remove (int count)
190	{	329	{
191	if (count > fill)	330	if (count > fill)
192	abort ();	331	assert (count <= fill);
193		332
194	memmove (data, data + count, fill -= count);	333	memmove (data, data + count, fill -= count);
195	}	334	}
196		335
197	bool byte_stream::put (u8 *data, unsigned int datalen)	336	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
210	return false;	349	return false;
211		350
212	data [fill++] = pkt->len >> 8;	351	data [fill++] = pkt->len >> 8;
213	data [fill++] = pkt->len;	352	data [fill++] = pkt->len;
214		353
215	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	354	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
216		355
217	return true;	356	return true;
218	}	357	}
219		358
220	vpn_packet *byte_stream::get ()	359	vpn_packet *byte_stream::get ()
221	{	360	{
		361	unsigned int len;
		362
		363	for (;;)
		364	{
222	int len = (data [0] << 8) | data [1];	365	len = (data [0] << 8) | data [1];
223		366
224	printf ("get len %d, fill %d\n", len, fill);//D
225
226	if (len > MAXSIZE && fill >= 2)	367	if (len <= MAXSIZE || fill < 2)
227	abort (); // TODO handle this gracefully, connection reset	368	break;
228		369
		370	// TODO: handle this better than skipping, e.g. by reset
		371	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		372	remove (1);
		373	}
		374
229	if (fill < len + 2)	375	if (fill < len + 2)
230	return 0;	376	return 0;
231		377
232	vpn_packet *pkt = new vpn_packet;	378	vpn_packet *pkt = new vpn_packet;
233		379
234	pkt->len = len;	380	pkt->len = len;
235	memcpy (&((*pkt)[0]), data + 2, len);	381	memcpy (pkt->at (0), data + 2, len);
236	remove (len + 2);	382	remove (len + 2);
237		383
238	return pkt;	384	return pkt;
239	}	385	}
240		386
241	/////////////////////////////////////////////////////////////////////////////	387	/////////////////////////////////////////////////////////////////////////////
242		388
243	#define FLAG_QUERY ( 0 << 15)	389	#define FLAG_QUERY ( 0 << 15)
244	#define FLAG_RESPONSE ( 1 << 15)	390	#define FLAG_RESPONSE ( 1 << 15)
245	#define FLAG_OP_MASK (15 << 14)	391	#define FLAG_OP_MASK (15 << 11)
246	#define FLAG_OP_QUERY ( 0 << 11)	392	#define FLAG_OP_QUERY ( 0 << 11)
247	#define FLAG_AA ( 1 << 10)	393	#define FLAG_AA ( 1 << 10)
248	#define FLAG_TC ( 1 << 9)	394	#define FLAG_TC ( 1 << 9)
249	#define FLAG_RD ( 1 << 8)	395	#define FLAG_RD ( 1 << 8)
250	#define FLAG_RA ( 1 << 7)	396	#define FLAG_RA ( 1 << 7)
…		…
257	#define FLAG_RCODE_REFUSED ( 5 << 0)	403	#define FLAG_RCODE_REFUSED ( 5 << 0)
258		404
259	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	405	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
260	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)	406	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
261		407
		408	struct dns_cfg
		409	{
		410	static int next_uid;
		411
		412	u8 id1, id2, id3, id4;
		413	u8 version;
		414	u8 rrtype;
		415	u8 flags;
		416	u8 def_ttl;
		417	u8 rcv_cdc;
		418	u8 snd_cdc;
		419	u16 max_size;
		420	u16 client;
		421	u16 uid; // to make request unique
		422
		423	u8 reserved[8];
		424
		425	void reset (int clientid);
		426	bool valid ();
		427	};
		428
		429	int dns_cfg::next_uid;
		430
		431	void dns_cfg::reset (int clientid)
		432	{
		433	id1 = 'G';
		434	id2 = 'V';
		435	id3 = 'P';
		436	id4 = 'E';
		437
		438	version = 1;
		439
		440	rrtype = RR_TYPE_TXT;
		441	flags = 0;
		442	def_ttl = 1;
		443	rcv_cdc = 0;
		444	snd_cdc = 62;
		445	max_size = ntohs (MAX_PKT_SIZE);
		446	client = ntohs (clientid);
		447	uid = next_uid++;
		448
		449	memset (reserved, 0, 8);
		450	}
		451
		452	bool dns_cfg::valid ()
		453	{
		454	return id1 == 'G'
		455	&& id2 == 'V'
		456	&& id3 == 'P'
		457	&& id4 == 'E'
		458	&& version == 1
		459	&& flags == 0
		460	&& rcv_cdc == 0
		461	&& snd_cdc == 62
		462	&& max_size == ntohs (MAX_PKT_SIZE);
		463	}
		464
262	struct dns_packet : net_packet	465	struct dns_packet : net_packet
263	{	466	{
264	u16 id;	467	u16 id;
265	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	468	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
266	u16 qdcount, ancount, nscount, arcount;	469	u16 qdcount, ancount, nscount, arcount;
…		…
304	return data - orig;	507	return data - orig;
305	}	508	}
306		509
307	/////////////////////////////////////////////////////////////////////////////	510	/////////////////////////////////////////////////////////////////////////////
308		511
309	struct dns_req
310	{
311	dns_packet *pkt;
312	tstamp next;
313	int retry;
314	connection *conn;
315	int seqno;
316
317	dns_req (connection *c);
318	void gen_stream_req (int seqno, byte_stream *stream);
319	};
320
321	static u16 dns_id = 12098; // TODO: should be per-vpn	512	static u16 dns_id = 0; // TODO: should be per-vpn
322		513
323	static u16 next_id ()	514	static u16 next_id ()
324	{	515	{
		516	if (!dns_id)
		517	dns_id = time (0);
		518
325	// the simplest lsfr with periodicity 65535 i could find	519	// the simplest lsfr with periodicity 65535 i could find
326	dns_id = (dns_id << 1)	520	dns_id = (dns_id << 1)
327	| (((dns_id >> 1)	521	| (((dns_id >> 1)
328	^ (dns_id >> 2)	522	^ (dns_id >> 2)
329	^ (dns_id >> 4)	523	^ (dns_id >> 4)
330	^ (dns_id >> 15)) & 1);	524	^ (dns_id >> 15)) & 1);
331		525
332	return dns_id;	526	return dns_id;
333	}	527	}
334		528
335	dns_req::dns_req (connection *c)	529	struct dns_rcv;
336	: conn (c)	530	struct dns_snd;
		531
		532	struct dns_connection
337	{	533	{
338	next = 0;	534	connection *c;
		535	struct vpn *vpn;
		536
		537	dns_cfg cfg;
		538
		539	bool established;
		540
		541	tstamp last_received;
		542	tstamp last_sent;
		543	double last_latency;
		544	double poll_interval, send_interval;
		545
		546	vector<dns_rcv *> rcvpq;
		547
		548	byte_stream rcvdq; int rcvseq;
		549	byte_stream snddq; int sndseq;
		550
		551	void time_cb (time_watcher &w); time_watcher tw;
		552	void receive_rep (dns_rcv *r);
		553
		554	dns_connection (connection *c);
		555	~dns_connection ();
		556	};
		557
		558	struct dns_snd
		559	{
		560	dns_packet *pkt;
		561	tstamp timeout, sent;
		562	int retry;
		563	struct dns_connection *dns;
		564	int seqno;
		565	bool stdhdr;
		566
		567	void gen_stream_req (int seqno, byte_stream &stream);
		568	void gen_syn_req ();
		569
		570	dns_snd (dns_connection *dns);
		571	~dns_snd ();
		572	};
		573
		574	dns_snd::dns_snd (dns_connection *dns)
		575	: dns (dns)
		576	{
		577	timeout = 0;
339	retry = 0;	578	retry = 0;
		579	seqno = 0;
		580	sent = NOW;
		581	stdhdr = false;
340		582
341	pkt = new dns_packet;	583	pkt = new dns_packet;
342		584
343	pkt->id = next_id ();	585	pkt->id = next_id ();
344	}	586	}
345		587
		588	dns_snd::~dns_snd ()
		589	{
		590	delete pkt;
		591	}
		592
		593	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		594	{
		595	// add tunnel domain
		596	for (;;)
		597	{
		598	const char *end = strchr (domain, '.');
		599
		600	if (!end)
		601	end = domain + strlen (domain);
		602
		603	int len = end - domain;
		604
		605	pkt [offs++] = len;
		606	memcpy (pkt.at (offs), domain, len);
		607	offs += len;
		608
		609	if (!*end)
		610	break;
		611
		612	domain = end + 1;
		613	}
		614	}
		615
346	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	616	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
347	{	617	{
		618	stdhdr = true;
348	this->seqno = seqno;	619	this->seqno = seqno;
		620
		621	timeout = NOW + INITIAL_TIMEOUT;
349		622
350	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	623	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
351	pkt->qdcount = htons (1);	624	pkt->qdcount = htons (1);
352		625
353	int offs = 6*2;	626	int offs = 6*2;
354	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	627	int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2);
355	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,	628	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
356	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra	629	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
357		630
358	u8 data[256]; //TODO
359
360	data[0] = THISNODE->id; //TODO
361	data[1] = seqno >> 8; //TODO
362	data[2] = seqno; //TODO
363
364	int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
365
366	if (datalen > stream->size ())
367	datalen = stream->size ();
368
369	char enc[256], *encp = enc;	631	char enc[256], *encp = enc;
370		632	encode_header (enc, THISNODE->id, seqno);
371	memcpy (data + 3, stream->begin (), datalen);	633
372	int enclen = dns64::encode (enc, data, datalen + 3);	634	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		635
		636	if (datalen > stream.size ())
		637	datalen = stream.size ();
		638
		639	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
373	stream->remove (datalen);	640	stream.remove (datalen);
374		641
375	while (enclen)	642	while (enclen)
376	{	643	{
377	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	644	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
378		645
…		…
383	encp += lbllen;	650	encp += lbllen;
384		651
385	enclen -= lbllen;	652	enclen -= lbllen;
386	}	653	}
387		654
388	const char *suffix = THISNODE->domain;	655	append_domain (*pkt, offs, THISNODE->domain);
389
390	// add tunnel domain
391	for (;;)
392	{
393	const char *end = strchr (suffix, '.');
394
395	if (!end)
396	end = suffix + strlen (suffix);
397
398	int len = end - suffix;
399
400	(*pkt)[offs++] = len;
401	memcpy (&((*pkt)[offs]), suffix, len);
402	offs += len;
403
404	if (!*end)
405	break;
406
407	suffix = end + 1;
408	}
409		656
410	(*pkt)[offs++] = 0;	657	(*pkt)[offs++] = 0;
411	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	658	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		659	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		660
		661	pkt->len = offs;
		662	}
		663
		664	void dns_snd::gen_syn_req ()
		665	{
		666	timeout = NOW + INITIAL_SYN_TIMEOUT;
		667
		668	printf ("send syn\n");//D
		669
		670	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		671	pkt->qdcount = htons (1);
		672
		673	int offs = 6 * 2;
		674
		675	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		676
		677	assert (elen <= MAX_LBL_SIZE);
		678
		679	(*pkt)[offs] = elen;
		680	offs += elen + 1;
		681	append_domain (*pkt, offs, THISNODE->domain);
		682
		683	(*pkt)[offs++] = 0;
		684	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
412	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	685	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
413		686
414	pkt->len = offs;	687	pkt->len = offs;
415	}	688	}
416		689
…		…
419	int seqno;	692	int seqno;
420	dns_packet *pkt; // reply packet	693	dns_packet *pkt; // reply packet
421	u8 data [MAXSIZE]; // actually part of the reply packet...	694	u8 data [MAXSIZE]; // actually part of the reply packet...
422	int datalen;	695	int datalen;
423		696
424	dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen);	697	dns_rcv (int seqno, u8 *data, int datalen);
425	~dns_rcv ();	698	~dns_rcv ();
426	};	699	};
427		700
428	dns_rcv::dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen)	701	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
429	: seqno (seqno), pkt (new dns_packet), datalen (datalen)	702	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
430	{	703	{
431	memcpy (this->data, data, datalen);	704	memcpy (this->data, data, datalen);
432	pkt->len = req->len;
433	memcpy (pkt->at (0), req->at (0), req->len);
434	}	705	}
435		706
436	dns_rcv::~dns_rcv ()	707	dns_rcv::~dns_rcv ()
437	{	708	{
438	delete pkt;	709	delete pkt;
439	}	710	}
440		711
441	/////////////////////////////////////////////////////////////////////////////	712	/////////////////////////////////////////////////////////////////////////////
442		713
443	struct dns_cfg	714	dns_connection::dns_connection (connection *c)
		715	: c (c)
		716	, rcvdq (MAX_BACKLOG * 2)
		717	, snddq (MAX_BACKLOG * 2)
		718	, tw (this, &dns_connection::time_cb)
444	{	719	{
445	u8 id1, id2, id3;	720	vpn = c->vpn;
446	u8 def_ttl;
447	u8 unused1;
448	u16 max_size;
449	u8 flags1, flags2;
450	};
451		721
		722	established = false;
		723
		724	rcvseq = sndseq = 0;
		725
		726	last_sent = last_received = 0;
		727	poll_interval = MIN_POLL_INTERVAL;
		728	send_interval = 0.5; // starting rate
		729	last_latency = INITIAL_TIMEOUT;
		730	}
		731
		732	dns_connection::~dns_connection ()
		733	{
		734	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		735	i != rcvpq.end ();
		736	++i)
		737	delete *i;
		738	}
		739
452	void connection::dnsv4_receive_rep (struct dns_rcv *r)	740	void dns_connection::receive_rep (dns_rcv *r)
453	{	741	{
		742	if (r->datalen)
		743	{
		744	last_received = NOW;
		745	tw.trigger ();
		746
		747	poll_interval = send_interval;
		748	}
		749	else
		750	{
		751	poll_interval *= 1.5;
		752	if (poll_interval > MAX_POLL_INTERVAL)
		753	poll_interval = MAX_POLL_INTERVAL;
		754	}
		755
454	dns_rcvpq.push_back (r);	756	rcvpq.push_back (r);
455		757
456	redo:	758	redo:
457		759
		760	// find next packet
458	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	761	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
459	i != dns_rcvpq.end ();
460	++i)
461	if (dns_rcvseq == (*i)->seqno)	762	if (SEQNO_EQ (rcvseq, (*i)->seqno))
462	{	763	{
		764	// enter the packet into our input stream
463	dns_rcv *r = *i;	765	r = *i;
464		766
		767	// remove the oldest packet, look forward, as it's oldest first
		768	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		769	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		770	{
		771	delete *j;
		772	rcvpq.erase (j);
		773	break;
		774	}
		775
465	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	776	rcvseq = (rcvseq + 1) & SEQNO_MASK;
466		777
467	if (!dns_snddq && !dns_rcvdq)	778	if (!rcvdq.put (r->data, r->datalen))
468	{	779	{
469	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	780	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
470	dns_snddq = new byte_stream (MAX_BACKLOG);	781	abort (); // MUST never overflow, can be caused by data corruption, TODO
471
472	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
473	}	782	}
474		783
475	if (!dns_rcvdq->put (r->data, r->datalen))
476	abort (); // MUST never overflow, can be caused by data corruption, TODO
477
478	while (vpn_packet *pkt = dns_rcvdq->get ())	784	while (vpn_packet *pkt = rcvdq.get ())
479	{	785	{
480	sockinfo si;	786	sockinfo si;
481	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	787	si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
482		788
483	vpn->recv_vpn_packet (pkt, si);	789	vpn->recv_vpn_packet (pkt, si);
		790
		791	delete pkt;
484	}	792	}
485	}	793
486	else if ((u32)dns_rcvseq - MAX_WINDOW - (u32)(*i)->seqno < MAX_WINDOW * 2)	794	// check for further packets
487	{
488	dns_rcvpq.erase (i);
489	goto redo;	795	goto redo;
490	}	796	}
491	}	797	}
492		798
493	dns_packet *	799	void
494	vpn::dnsv4_server (dns_packet *pkt)	800	vpn::dnsv4_server (dns_packet &pkt)
495	{	801	{
496	u16 flags = ntohs (pkt->flags);	802	u16 flags = ntohs (pkt.flags);
497		803
498	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
499	int offs = 6 * 2; // skip header	804	int offs = 6 * 2; // skip header
500		805
501	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	806	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
502		807
503	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	808	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
504	&& pkt->qdcount == htons (1))	809	&& pkt.qdcount == htons (1))
505	{	810	{
506	char qname[MAXSIZE];	811	char qname[MAXSIZE];
507	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	812	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
508		813
509	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	814	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
510	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	815	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
511		816
512	pkt->qdcount = htons (1);	817	pkt.qdcount = htons (1);
513	pkt->ancount = 0;	818	pkt.ancount = 0;
514	pkt->nscount = 0; // should be self, as other nameservers reply like this	819	pkt.nscount = 0; // should be self, as other nameservers reply like this
515	pkt->arcount = 0; // a record for self, as other nameservers reply like this	820	pkt.arcount = 0; // a record for self, as other nameservers reply like this
516		821
517	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	822	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
518		823
519	int dlen = strlen (THISNODE->domain);	824	int dlen = strlen (THISNODE->domain);
520		825
521	if (qclass == RR_CLASS_IN	826	if (qclass == RR_CLASS_IN
522	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
523	&& qlen > dlen + 1	827	&& qlen > dlen + 1
524	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	828	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
525	{	829	{
526	// correct class, domain: parse	830	// now generate reply
527	u8 data[MAXSIZE];	831	pkt.ancount = htons (1); // one answer RR
528	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	832	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
529		833
530	int client = data[0];	834	if ((qtype == RR_TYPE_ANY
531	int seqno = ((data[1] << 8) | data[2]) & SEQNO_MASK;	835	|| qtype == RR_TYPE_TXT
532		836	|| qtype == RR_TYPE_NULL)
533	if (0 < client && client <= conns.size ())	837	&& qlen > dlen + 1 + HDRSIZE)
534	{	838	{
535	connection *c = conns [client - 1];	839	// correct class, domain: parse
		840	int client, seqno;
		841	decode_header (qname, client, seqno);
536		842
537	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();	843	u8 data[MAXSIZE];
538	i != c->dns_rcvpq.end ();	844	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
539	++i)
540	if ((*i)->seqno == seqno)
541	{
542	// already seen that request, just reply with the original reply
543	dns_rcv *r = *i;
544		845
545	offs = r->pkt->len;	846	if (0 < client && client <= conns.size ())
546	memcpy (pkt->at (0), r->pkt->at (0), offs);
547	goto duplicate_request;
548	}
549
550	// new packet, queue
551	c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data + 3, datalen - 3));
552
553	// now generate reply
554	pkt->ancount = htons (1); // one answer RR
555	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
556
557	(*pkt) [offs++] = 0xc0;
558	(*pkt) [offs++] = 6 * 2; // same as in query section
559
560	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;
561	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;
562
563	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;
564	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL
565
566	int dlen = MAX_PKT_SIZE - offs - 2;
567
568	// bind doesn't compress well, so reduce further by one label length
569	dlen -= qlen;
570
571	int rdlen_offs = offs += 2;
572
573	while (c->dns_snddq
574	&& !c->dns_snddq->empty ()
575	&& dlen > 1)
576	{	847	{
		848	connection *c = conns [client - 1];
		849	dns_connection *dns = c->dns;
		850	dns_rcv *rcv;
		851	bool in_seq;
		852
		853	if (dns)
		854	{
		855	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		856	if (SEQNO_EQ ((*i)->seqno, seqno))
		857	{
		858	// already seen that request: simply reply with the cached reply
		859	dns_rcv *r = *i;
		860
		861	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		862
		863	// refresh header & id, as the retry count could have changed
		864	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		865	r->pkt->id = pkt.id;
		866
		867	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		868
		869	goto duplicate_request;
		870	}
		871
		872	in_seq = dns->rcvseq == seqno;
		873
		874	// new packet, queue
		875	rcv = new dns_rcv (seqno, data, datalen);
		876	dns->receive_rep (rcv);
		877	}
		878
		879	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		880
		881	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		882	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		883	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		884	pkt [offs++] = 0; pkt [offs++] = 0;
		885	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		886
		887	int rdlen_offs = offs += 2;
		888
		889	int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs;
		890	// bind doesn't compress well, so reduce further by one label length
		891	dlen -= qlen;
		892
		893	if (dns)
		894	{
		895	// only put data into in-order sequence packets, if
		896	// we receive out-of-order packets we generate empty
		897	// replies
		898	while (dlen > 1 && !dns->snddq.empty () && in_seq)
		899	{
577	int txtlen = dlen <= 255 ? dlen - 1 : 255;	900	int txtlen = dlen <= 255 ? dlen - 1 : 255;
578		901
579	if (txtlen > c->dns_snddq->size ())	902	if (txtlen > dns->snddq.size ())
580	txtlen = c->dns_snddq->size ();	903	txtlen = dns->snddq.size ();
581		904
582	(*pkt)[offs++] = txtlen;	905	pkt[offs++] = txtlen;
583	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	906	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
584	offs += txtlen;	907	offs += txtlen;
585	c->dns_snddq->remove (txtlen);	908	dns->snddq.remove (txtlen);
586		909
587	dlen -= txtlen + 1;	910	dlen -= txtlen + 1;
		911	}
		912
		913	// avoid empty TXT rdata
		914	if (offs == rdlen_offs)
		915	pkt[offs++] = 0;
		916
		917	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		918	}
		919	else
		920	{
		921	// send RST
		922	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		923	pkt [offs++] = CMD_IP_RST;
		924	}
		925
		926	int rdlen = offs - rdlen_offs;
		927
		928	pkt [rdlen_offs - 2] = rdlen >> 8;
		929	pkt [rdlen_offs - 1] = rdlen;
		930
		931	if (dns)
		932	{
		933	// now update dns_rcv copy
		934	rcv->pkt->len = offs;
		935	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		936	}
		937
		938	duplicate_request: ;
588	}	939	}
589		940	else
590	// avoid empty TXT rdata	941	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
591	if (offs == rdlen_offs)
592	(*pkt)[offs++] = 0;
593
594	int rdlen = offs - rdlen_offs;
595
596	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
597	(*pkt) [rdlen_offs - 1] = rdlen;
598
599	duplicate_request: ;
600	}	942	}
601	else	943	else if (qtype == RR_TYPE_A
602	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	944	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		945	{
		946	dns_cfg cfg;
		947	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		948	int client = ntohs (cfg.client);
		949
		950	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		951
		952	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
		953	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		954	pkt [offs++] = 0; pkt [offs++] = 0;
		955	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		956	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		957
		958	slog (L_INFO, _("DNS: client %d tries to connect"), client);
		959
		960	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		961	pkt [offs++] = CMD_IP_REJ;
		962
		963	if (0 < client && client <= conns.size ())
		964	{
		965	connection *c = conns [client - 1];
		966
		967	if (cfg.valid ())
		968	{
		969	pkt [offs - 1] = CMD_IP_SYN;
		970
		971	delete c->dns;
		972	c->dns = new dns_connection (c);
		973	c->dns->cfg = cfg;
		974	}
		975	}
		976	}
603	}	977	}
604	}
605	else
606	offs = pkt->len;
607		978
608	pkt->len = offs;	979	pkt.len = offs;
609	return pkt;	980	}
610	}	981	}
611		982
612	void	983	void
613	vpn::dnsv4_client (dns_packet *pkt)	984	vpn::dnsv4_client (dns_packet &pkt)
614	{	985	{
615	u16 flags = ntohs (pkt->flags);	986	u16 flags = ntohs (pkt.flags);
616	int offs = 6 * 2; // skip header	987	int offs = 6 * 2; // skip header
617		988
618	pkt->qdcount = ntohs (pkt->qdcount);	989	pkt.qdcount = ntohs (pkt.qdcount);
619	pkt->ancount = ntohs (pkt->ancount);	990	pkt.ancount = ntohs (pkt.ancount);
620		991
621	// go through our request list and find the corresponding request	992	// go through our request list and find the corresponding request
622	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	993	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
623	i != dns_sndpq.end ();	994	i != dns_sndpq.end ();
624	++i)	995	++i)
625	if ((*i)->pkt->id == pkt->id)	996	if ((*i)->pkt->id == pkt.id)
626	{	997	{
		998	dns_connection *dns = (*i)->dns;
627	connection *c = (*i)->conn;	999	connection *c = dns->c;
628	int seqno = (*i)->seqno;	1000	int seqno = (*i)->seqno;
629	u8 data[MAXSIZE], *datap = data;	1001	u8 data[MAXSIZE], *datap = data;
630		1002
		1003	if ((*i)->retry)
		1004	{
		1005	dns->send_interval *= 1.01;
		1006	if (dns->send_interval > MAX_SEND_INTERVAL)
		1007	dns->send_interval = MAX_SEND_INTERVAL;
		1008	}
		1009	else
		1010	{
		1011	#if 1
		1012	dns->send_interval *= 0.999;
		1013	#endif
		1014	if (dns->send_interval < MIN_SEND_INTERVAL)
		1015	dns->send_interval = MIN_SEND_INTERVAL;
		1016
		1017	// the latency surely puts an upper bound on
		1018	// the minimum send interval
		1019	double latency = NOW - (*i)->sent;
		1020	dns->last_latency = latency;
		1021
		1022	if (dns->send_interval > latency)
		1023	dns->send_interval = latency;
		1024	}
		1025
631	delete *i;	1026	delete *i;
632	dns_sndpq.erase (i);	1027	dns_sndpq.erase (i);
633		1028
634	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1029	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
635	{	1030	{
636	char qname[MAXSIZE];	1031	char qname[MAXSIZE];
637		1032
638	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1033	while (pkt.qdcount-- && offs < MAXSIZE - 4)
639	{	1034	{
640	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1035	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
641	offs += 4; // skip qtype, qclass	1036	offs += 4; // skip qtype, qclass
642	}	1037	}
643		1038
644	while (pkt->ancount-- && offs < MAXSIZE - 10)	1039	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
645	{	1040	{
646	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1041	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
647		1042
648	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1043	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
649	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1044	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
650	u32 ttl = (*pkt) [offs++] << 24;	1045	u32 ttl = pkt [offs++] << 24;
651	ttl |= (*pkt) [offs++] << 16;	1046	ttl |= pkt [offs++] << 16;
652	ttl |= (*pkt) [offs++] << 8;	1047	ttl |= pkt [offs++] << 8;
653	ttl |= (*pkt) [offs++];	1048	ttl |= pkt [offs++];
654
655	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1049	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
656		1050
657	if (rdlen <= MAXSIZE - offs)	1051	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
658	{	1052	{
659	// decode bytes, finally	1053	if (rdlen <= MAXSIZE - offs)
660
661	while (rdlen)
662	{	1054	{
		1055	// decode bytes, finally
		1056
		1057	while (rdlen)
		1058	{
663	int txtlen = (*pkt) [offs++];	1059	int txtlen = pkt [offs++];
664		1060
665	assert (txtlen + offs < MAXSIZE - 1);	1061	assert (txtlen + offs < MAXSIZE - 1);
666		1062
667	memcpy (datap, pkt->at (offs), txtlen);	1063	memcpy (datap, pkt.at (offs), txtlen);
668	datap += txtlen; offs += txtlen;	1064	datap += txtlen; offs += txtlen;
669		1065
670	rdlen -= txtlen + 1;	1066	rdlen -= txtlen + 1;
		1067	}
671	}	1068	}
672
673	}	1069	}
		1070	else if (qtype == RR_TYPE_A)
		1071	{
		1072	u8 ip [4];
674		1073
		1074	ip [0] = pkt [offs++];
		1075	ip [1] = pkt [offs++];
		1076	ip [2] = pkt [offs++];
		1077	ip [3] = pkt [offs++];
		1078
		1079	if (ip [0] == CMD_IP_1
		1080	&& ip [1] == CMD_IP_2
		1081	&& ip [2] == CMD_IP_3)
		1082	{
		1083	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1084
		1085	if (ip [3] == CMD_IP_RST)
		1086	{
		1087	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1088
		1089	delete dns; c->dns = 0;
		1090
		1091	return;
		1092	}
		1093	else if (ip [3] == CMD_IP_SYN)
		1094	{
		1095	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1096	dns->established = true;
		1097	}
		1098	else if (ip [3] == CMD_IP_REJ)
		1099	{
		1100	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1101	abort ();
		1102	}
		1103	else
		1104	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1105	}
		1106	else
		1107	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1108	ip [0], ip [1], ip [2], ip [3]);
		1109
		1110	return;
		1111	}
		1112
		1113	int client, rseqno;
		1114	decode_header (qname, client, rseqno);
		1115
		1116	if (client != THISNODE->id)
		1117	{
		1118	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1119	datap = 0;
		1120	}
		1121	else if (rseqno != seqno)
		1122	{
		1123	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1124	datap = 0;
		1125	}
675	}	1126	}
676	}	1127	}
677		1128
		1129	// todo: pkt now used
678	if (datap != data)	1130	if (datap)
679	printf ("%02x %02x %02x %02x\n",
680	data[0],
681	data[1],
682	data[2],
683	data[3]);
684
685	printf ("recv %d,%d\n", pkt->id, seqno, datap - data);//D
686	c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data, datap - data));	1131	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
687		1132
688	break;	1133	break;
689	}	1134	}
690
691	delete pkt;
692	}	1135	}
693		1136
694	void	1137	void
695	vpn::dnsv4_ev (io_watcher &w, short revents)	1138	vpn::dnsv4_ev (io_watcher &w, short revents)
696	{	1139	{
…		…
698	{	1141	{
699	dns_packet *pkt = new dns_packet;	1142	dns_packet *pkt = new dns_packet;
700	struct sockaddr_in sa;	1143	struct sockaddr_in sa;
701	socklen_t sa_len = sizeof (sa);	1144	socklen_t sa_len = sizeof (sa);
702		1145
703	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1146	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
704		1147
705	if (pkt->len > 0)	1148	if (pkt->len > 0)
706	{	1149	{
707	if (pkt->flags & htons (FLAG_TC))
708	{
709	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));
710	//TODO connection reset
711	}
712
713	if (THISNODE->dns_port)	1150	if (THISNODE->dns_port)
714	{	1151	{
715	pkt = dnsv4_server (pkt);	1152	dnsv4_server (*pkt);
716	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);	1153	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}	1154	}
718	else	1155	else
719	dnsv4_client (pkt);	1156	dnsv4_client (*pkt);
		1157
		1158	delete pkt;
720	}	1159	}
721	}	1160	}
722	}	1161	}
723		1162
724	bool	1163	bool
725	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1164	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
726	{	1165	{
727	// never initialized	1166	int client = ntohs (si.port);
728	if (!dns_snddq && !dns_rcvdq)
729	{
730	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
731	dns_snddq = new byte_stream (MAX_BACKLOG);
732		1167
733	//dns_rcvseq = dns_sndseq = 0;	1168	assert (0 < client && client <= conns.size ());
734		1169
735	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1170	connection *c = conns [client - 1];
736	}	1171
		1172	if (!c->dns)
		1173	c->dns = new dns_connection (c);
737		1174
738	if (!dns_snddq->put (pkt))	1175	if (!c->dns->snddq.put (pkt))
739	return false;	1176	return false;
740		1177
741	// start timer if neccessary	1178	c->dns->tw.trigger ();
742	if (!THISNODE->dns_port && !dnsv4_tw.active)
743	dnsv4_cb (dnsv4_tw);
744		1179
745	return true;	1180	return true;
746	}	1181	}
747		1182
748	void	1183	void
		1184	connection::dnsv4_reset_connection ()
		1185	{
		1186	//delete dns; dns = 0; //TODO
		1187	}
		1188
		1189	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1190
		1191	void
749	connection::dnsv4_cb (time_watcher &w)	1192	dns_connection::time_cb (time_watcher &w)
750	{	1193	{
		1194	// servers have to be polled
		1195	if (THISNODE->dns_port)
		1196	return;
		1197
751	// check for timeouts and (re)transmit	1198	// check for timeouts and (re)transmit
752	tstamp next = NOW + 60;	1199	tstamp next = NOW + poll_interval;
753	dns_req *send = 0;	1200	dns_snd *send = 0;
754		1201
755	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1202	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
756	i != vpn->dns_sndpq.end ();	1203	i != vpn->dns_sndpq.end ();
757	++i)	1204	++i)
758	{	1205	{
759	dns_req *r = *i;	1206	dns_snd *r = *i;
760		1207
761	if (r->next <= NOW)	1208	if (r->timeout <= NOW)
762	{	1209	{
763	if (!send)	1210	if (!send)
764	{	1211	{
765	send = r;	1212	send = r;
766		1213
767	if (r->retry)//D
768	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
769	r->retry++;	1214	r->retry++;
770	r->next = NOW + r->retry;	1215	r->timeout = NOW + (r->retry * last_latency * 8.);
		1216
		1217	// the following code changes the query section a bit, forcing
		1218	// the forwarder to generate a new request
		1219	if (r->stdhdr)
		1220	{
		1221	//printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1222	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1223	}
771	}	1224	}
772	}	1225	}
		1226	else
		1227	NEXT (r->timeout);
		1228	}
773		1229
774	if (r->next < next)	1230	if (last_sent + send_interval <= NOW)
775	next = r->next;
776	}	1231	{
777
778	if (!send	1232	if (!send)
		1233	{
		1234	// generate a new packet, if wise
		1235
		1236	if (!established)
		1237	{
		1238	if (vpn->dns_sndpq.empty ())
		1239	{
		1240	send = new dns_snd (this);
		1241
		1242	printf ("new conn %p %d\n", this, c->conf->id);//D
		1243	cfg.reset (THISNODE->id);
		1244	send->gen_syn_req ();
		1245	}
		1246	}
779	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1247	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
780	{	1248	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1249	{
		1250	//printf ("sending data request etc.\n"); //D
		1251	if (!snddq.empty ())
		1252	{
		1253	poll_interval = send_interval;
		1254	NEXT (NOW + send_interval);
		1255	}
		1256
781	send = new dns_req (this);	1257	send = new dns_snd (this);
782	send->gen_stream_req (dns_sndseq, dns_snddq);	1258	send->gen_stream_req (sndseq, snddq);
		1259	send->timeout = NOW + last_latency * 8.;
		1260
		1261	sndseq = (sndseq + 1) & SEQNO_MASK;
		1262	}
		1263
		1264	if (send)
783	vpn->dns_sndpq.push_back (send);	1265	vpn->dns_sndpq.push_back (send);
		1266	}
784		1267
785	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
786	}
787
788	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
789
790	if (send)	1268	if (send)
		1269	{
		1270	last_sent = NOW;
		1271	sendto (vpn->dnsv4_fd,
		1272	send->pkt->at (0), send->pkt->len, 0,
		1273	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1274	}
791	{	1275	}
792	dns_packet *pkt = send->pkt;	1276	else
		1277	NEXT (last_sent + send_interval);
793		1278
794	next = min_next;	1279	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)",
		1280	poll_interval, send_interval, next - NOW,
		1281	vpn->dns_sndpq.size (), snddq.size ());
795		1282
796	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());	1283	// TODO: no idea when this happens, but when next < NOW, we have a problem
797	}	1284	if (next < NOW + 0.0001)
798	else if (next < min_next)	1285	next = NOW + 0.1;
799	next = min_next;
800		1286
801	w.start (next);	1287	w.start (next);
802	}	1288	}
803		1289
804	#endif	1290	#endif

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