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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.4 by pcg, Wed Mar 2 05:49:31 2005 UTC vs.
Revision 1.17 by pcg, Sat Mar 5 03:47:05 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.
		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?
46		57
47	#define MAX_OUTSTANDING 10 // 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 1 // requests/s
50	#define MAX_BACKLOG (10*1024) // size of protocol backlog	60	#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		61
52	/*	62	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well
		63	// 240 leaves about 4 bytes of server reply data
		64	// every two request bytes less give room for one reply byte
53		65
54	protocol, in shorthand :)	66	#define SEQNO_MASK 0x3fff
55		67	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
56	client -> server <req> ANY?
57	server -> client <req> TXT <rep>
58
59	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
60	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
61
62	if <client-id> is zero, the connection will be configured:
63
64	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
65
66	*/
67		68
68	#define MAX_LBL_SIZE 63	69	#define MAX_LBL_SIZE 63
69	#define MAX_PKT_SIZE 512	70	#define MAX_PKT_SIZE 512
70		71
		72	#define RR_TYPE_A 1
		73	#define RR_TYPE_NULL 10
71	#define RR_TYPE_TXT 16	74	#define RR_TYPE_TXT 16
72	#define RR_TYPE_ANY 255	75	#define RR_TYPE_ANY 255
		76
73	#define RR_CLASS_IN 1	77	#define RR_CLASS_IN 1
74		78
75	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	79	#define CMD_IP_1 207
76	struct dns64	80	#define CMD_IP_2 46
77	{	81	#define CMD_IP_3 236
78	static const char encode_chars[64 + 1];	82	#define CMD_IP_RST 29
79	static s8 decode_chars[256];	83	#define CMD_IP_SYN 113
		84	#define CMD_IP_REJ 32
80		85
81	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	86	// works for cmaps up to 255 (not 256!)
82	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
83	static int encode (char *dst, u8 *src, int len);	129	unsigned int encode (char *dst, u8 *src, unsigned int len);
84	static int decode (u8 *dst, char *src, int len);	130	unsigned int decode (u8 *dst, char *src, unsigned int len);
85		131
86	dns64 ();	132	basecoder (const char *cmap);
87	} dns64;	133	};
88		134
89	const char dns64::encode_chars[64 + 1] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";	135	basecoder::basecoder (const char *cmap)
90	s8 dns64::decode_chars[256];	136	: cmap (cmap)
91
92	dns64::dns64 ()
93	{	137	{
94	for (int i = 0; i < 64; i++)	138	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
95	decode_chars [encode_chars [i]] = i + 1;	139	{
96	}	140	u8 src [MAX_DEC_LEN];
		141	u8 dst [MAX_ENC_LEN];
97		142
98	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)
99	{	160	{
100	// slow, but easy to debug	161	return enc_len [len];
101	char *beg = dst;	162	}
102	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;
103		208
104	while (len--)	209	while (len--)
105	{	210	{
106	accum <<= 8;	211	u8 val = cmap.decode [(u8)*src++];
107	accum |= *src++;
108	bits += 8;
109		212
110	while (bits >= 6)	213	if (val != charmap::INVALID)
111	{	214	src_ [elen++] = val;
112	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	215	}
113	bits -= 6;	216
114	}	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)
115	}	228	{
		229	memset (dst, 0, dlen - n);
		230	memcpy (dst + dlen - n, dst_, n);
		231	}
		232	else
		233	memcpy (dst, dst_ + n - dlen, dlen);
116		234
117	if (bits)	235	return dlen;
118	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
119
120	return dst - beg;
121	}	236	}
122		237
123	int dns64::decode (u8 *dst, char *src, int len)	238	#if 0
124	{	239	struct test { test (); } test;
125	// slow, but easy to debug
126	u8 *beg = dst;
127	unsigned int accum, bits = 0;
128		240
129	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++)
130	{	250	{
131	s8 chr = decode_chars [(u8)*src++];	251	int elen = cdc.encode (enc, in, i);
		252	int dlen = cdc.decode (dec, enc, elen);
132		253
133	if (!chr)	254	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
134	break;
135
136	accum <<= 6;
137	accum |= chr - 1;
138	bits += 6;
139
140	while (bits >= 8)
141	{
142	*dst++ = accum >> (bits - 8);
143	bits -= 8;
144	}
145	}	255	}
		256	abort ();
		257	}
		258	#endif
146		259
147	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;
148	}	293	}
149		294
150	/////////////////////////////////////////////////////////////////////////////	295	/////////////////////////////////////////////////////////////////////////////
151		296
152	struct byte_stream	297	struct byte_stream
…		…
159	~byte_stream ();	304	~byte_stream ();
160		305
161	bool empty () { return !fill; }	306	bool empty () { return !fill; }
162	int size () { return fill; }	307	int size () { return fill; }
163		308
		309	bool put (u8 *data, unsigned int datalen);
164	bool put (vpn_packet *pkt);	310	bool put (vpn_packet *pkt);
165	vpn_packet *get ();	311	vpn_packet *get ();
166		312
167	u8 *begin () { return data; }	313	u8 *begin () { return data; }
168	void remove (int count);	314	void remove (int count);
…		…
180	}	326	}
181		327
182	void byte_stream::remove (int count)	328	void byte_stream::remove (int count)
183	{	329	{
184	if (count > fill)	330	if (count > fill)
185	abort ();	331	assert (count <= fill);
186		332
187	memmove (data, data + count, fill -= count);	333	memmove (data, data + count, fill -= count);
		334	}
		335
		336	bool byte_stream::put (u8 *data, unsigned int datalen)
		337	{
		338	if (maxsize - fill < datalen)
		339	return false;
		340
		341	memcpy (this->data + fill, data, datalen); fill += datalen;
		342
		343	return true;
188	}	344	}
189		345
190	bool byte_stream::put (vpn_packet *pkt)	346	bool byte_stream::put (vpn_packet *pkt)
191	{	347	{
192	if (maxsize - fill < pkt->len + 2)	348	if (maxsize - fill < pkt->len + 2)
193	return false;	349	return false;
194		350
195	data [fill++] = pkt->len >> 8;	351	data [fill++] = pkt->len >> 8;
196	data [fill++] = pkt->len;	352	data [fill++] = pkt->len;
197		353
198	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	354	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
199		355
200	return true;	356	return true;
201	}	357	}
202		358
203	vpn_packet *byte_stream::get ()	359	vpn_packet *byte_stream::get ()
204	{	360	{
205	int len = (data [0] << 8) | data [1];	361	unsigned int len = (data [0] << 8) | data [1];
		362
		363	if (len > MAXSIZE && fill >= 2)
		364	assert (len <= MAXSIZE || fill < 2); // TODO handle this gracefully, connection reset
206		365
207	if (fill < len + 2)	366	if (fill < len + 2)
208	return 0;	367	return 0;
209		368
210	vpn_packet *pkt = new vpn_packet;	369	vpn_packet *pkt = new vpn_packet;
		370
		371	pkt->len = len;
211	memcpy (&((*pkt)[0]), data + 2, len);	372	memcpy (pkt->at (0), data + 2, len);
212	remove (len + 2);	373	remove (len + 2);
213		374
214	return pkt;	375	return pkt;
215	}	376	}
216		377
217	/////////////////////////////////////////////////////////////////////////////	378	/////////////////////////////////////////////////////////////////////////////
218		379
219	#define FLAG_QUERY ( 0 << 15)	380	#define FLAG_QUERY ( 0 << 15)
220	#define FLAG_RESPONSE ( 1 << 15)	381	#define FLAG_RESPONSE ( 1 << 15)
221	#define FLAG_OP_MASK (15 << 14)	382	#define FLAG_OP_MASK (15 << 11)
222	#define FLAG_OP_QUERY ( 0 << 11)	383	#define FLAG_OP_QUERY ( 0 << 11)
223	#define FLAG_AA ( 1 << 10)	384	#define FLAG_AA ( 1 << 10)
224	#define FLAG_TC ( 1 << 9)	385	#define FLAG_TC ( 1 << 9)
225	#define FLAG_RD ( 1 << 8)	386	#define FLAG_RD ( 1 << 8)
226	#define FLAG_RA ( 1 << 7)	387	#define FLAG_RA ( 1 << 7)
		388	#define FLAG_AUTH ( 1 << 5)
227	#define FLAG_RCODE_MASK (15 << 0)	389	#define FLAG_RCODE_MASK (15 << 0)
228	#define FLAG_RCODE_OK ( 0 << 0)	390	#define FLAG_RCODE_OK ( 0 << 0)
229	#define FLAG_RCODE_FORMERR ( 1 << 0)	391	#define FLAG_RCODE_FORMERR ( 1 << 0)
230	#define FLAG_RCODE_SERVFAIL ( 2 << 0)	392	#define FLAG_RCODE_SERVFAIL ( 2 << 0)
231	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)	393	#define FLAG_RCODE_NXDOMAIN ( 3 << 0)
232	#define FLAG_RCODE_REFUSED ( 5 << 0)	394	#define FLAG_RCODE_REFUSED ( 5 << 0)
233		395
234	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	396	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
235	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD)	397	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
		398
		399	struct dns_cfg
		400	{
		401	static int next_uid;
		402
		403	u8 id1, id2, id3, id4;
		404	u8 version;
		405	u8 rrtype;
		406	u8 flags;
		407	u8 def_ttl;
		408	u8 rcv_cdc;
		409	u8 snd_cdc;
		410	u16 max_size;
		411	u16 client;
		412	u16 uid; // to make request unique
		413
		414	u8 reserved[8];
		415
		416	void reset (int clientid);
		417	bool valid ();
		418	};
		419
		420	int dns_cfg::next_uid;
		421
		422	void dns_cfg::reset (int clientid)
		423	{
		424	id1 = 'G';
		425	id2 = 'V';
		426	id3 = 'P';
		427	id4 = 'E';
		428
		429	version = 1;
		430
		431	rrtype = RR_TYPE_TXT;
		432	flags = 0;
		433	def_ttl = 1;
		434	rcv_cdc = 0;
		435	snd_cdc = 62;
		436	max_size = ntohs (MAX_PKT_SIZE);
		437	client = ntohs (clientid);
		438	uid = next_uid++;
		439
		440	memset (reserved, 0, 8);
		441	}
		442
		443	bool dns_cfg::valid ()
		444	{
		445	return id1 == 'G'
		446	&& id2 == 'V'
		447	&& id3 == 'P'
		448	&& id4 == 'E'
		449	&& version == 1
		450	&& flags == 0
		451	&& rcv_cdc == 0
		452	&& snd_cdc == 62
		453	&& max_size == ntohs (MAX_PKT_SIZE);
		454	}
236		455
237	struct dns_packet : net_packet	456	struct dns_packet : net_packet
238	{	457	{
239	u16 id;	458	u16 id;
240	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	459	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
…		…
279	return data - orig;	498	return data - orig;
280	}	499	}
281		500
282	/////////////////////////////////////////////////////////////////////////////	501	/////////////////////////////////////////////////////////////////////////////
283		502
284	struct dns_req	503	struct dns_snd
285	{	504	{
286	dns_packet *pkt;	505	dns_packet *pkt;
287	tstamp next;	506	tstamp timeout, sent;
288	int retry;	507	int retry;
289	connection *conn;	508	struct dns_connection *dns;
		509	int seqno;
		510	bool stdhdr;
290		511
291	dns_req (connection *c, int seqno, byte_stream *stream);	512	void gen_stream_req (int seqno, byte_stream &stream);
		513	void gen_syn_req (const dns_cfg &cfg);
		514
		515	dns_snd (dns_connection *dns);
		516	~dns_snd ();
292	};	517	};
293		518
294	struct dns_rep
295	{
296	};
297
298	static u16 dns_id; // TODO: should be per-vpn	519	static u16 dns_id = 12098; // TODO: should be per-vpn
299		520
300	dns_req::dns_req (connection *c, int seqno, byte_stream *stream)	521	static u16 next_id ()
301	: conn (c)
302	{	522	{
303	next = 0;	523	// the simplest lsfr with periodicity 65535 i could find
		524	dns_id = (dns_id << 1)
		525	| (((dns_id >> 1)
		526	^ (dns_id >> 2)
		527	^ (dns_id >> 4)
		528	^ (dns_id >> 15)) & 1);
		529
		530	return dns_id;
		531	}
		532
		533	dns_snd::dns_snd (dns_connection *dns)
		534	: dns (dns)
		535	{
		536	timeout = 0;
304	retry = 0;	537	retry = 0;
		538	seqno = 0;
		539	sent = NOW;
		540	stdhdr = false;
305		541
306	pkt = new dns_packet;	542	pkt = new dns_packet;
307		543
308	pkt->id = dns_id++;	544	pkt->id = next_id ();
309	pkt->flags = DEFAULT_CLIENT_FLAGS;	545	}
310	pkt->qdcount = htons (1);
311	pkt->ancount = 0;
312	pkt->nscount = 0;
313	pkt->arcount = 0;
314		546
315	int offs = 6*2;	547	dns_snd::~dns_snd ()
316	int dlen = 255 - strlen (THISNODE->domain) - 1; // here we always have room for the max. label length	548	{
		549	delete pkt;
		550	}
317		551
318	u8 lbl[64]; //D	552	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
319	char enc[65];	553	{
320	int lbllen = 3;
321	lbl[0] = c->conf->id; //D
322	lbl[1] = seqno >> 8; //D
323	lbl[2] = seqno; //D
324
325	while (dlen > 0)
326	{
327	int sndlen = dlen;
328
329	if (sndlen + lbllen > dns64::decode_len (MAX_LBL_SIZE))
330	sndlen = dns64::decode_len (MAX_LBL_SIZE) - lbllen;
331
332	if (sndlen > stream->size ())
333	sndlen = stream->size ();
334
335	if (sndlen + lbllen == 0)
336	break;
337
338	memcpy (lbl + lbllen, stream->begin (), sndlen);
339	stream->remove (sndlen);
340	lbllen += sndlen;
341
342	dns64::encode (enc, lbl, lbllen);
343
344	int elen = dns64::encode_len (lbllen);
345	(*pkt)[offs++] = elen;
346	memcpy (&((*pkt)[offs]), enc, elen);
347	offs += elen;
348	dlen -= elen + 1;
349
350	lbllen = 0;
351	}
352
353	const char *suffix = THISNODE->domain;
354
355	// add tunnel domain	554	// add tunnel domain
356	for (;;)	555	for (;;)
357	{	556	{
358	const char *end = strchr (suffix, '.');	557	const char *end = strchr (domain, '.');
359		558
360	if (!end)	559	if (!end)
361	end = suffix + strlen (suffix);	560	end = domain + strlen (domain);
362		561
363	int len = end - suffix;	562	int len = end - domain;
364		563
365	(*pkt)[offs++] = len;	564	pkt [offs++] = len;
366	memcpy (&((*pkt)[offs]), suffix, len);	565	memcpy (pkt.at (offs), domain, len);
367	offs += len;	566	offs += len;
368		567
369	if (!*end)	568	if (!*end)
370	break;	569	break;
371		570
372	suffix = end + 1;	571	domain = end + 1;
		572	}
		573	}
		574
		575	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
		576	{
		577	stdhdr = true;
		578	this->seqno = seqno;
		579
		580	timeout = NOW + INITIAL_TIMEOUT;
		581
		582	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		583	pkt->qdcount = htons (1);
		584
		585	int offs = 6*2;
		586	int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2);
		587	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
		588	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
		589
		590	char enc[256], *encp = enc;
		591	encode_header (enc, THISNODE->id, seqno);
		592
		593	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		594
		595	if (datalen > stream.size ())
		596	datalen = stream.size ();
		597
		598	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
		599	stream.remove (datalen);
		600
		601	while (enclen)
373	}	602	{
		603	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
		604
		605	(*pkt)[offs++] = lbllen;
		606	memcpy (pkt->at (offs), encp, lbllen);
		607
		608	offs += lbllen;
		609	encp += lbllen;
		610
		611	enclen -= lbllen;
		612	}
		613
		614	append_domain (*pkt, offs, THISNODE->domain);
374		615
375	(*pkt)[offs++] = 0;	616	(*pkt)[offs++] = 0;
376	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	617	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
377	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	618	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
378		619
379	pkt->len = offs;	620	pkt->len = offs;
		621	}
380		622
381	c->vpn->dns_sndpq.push_back (this);	623	void dns_snd::gen_syn_req (const dns_cfg &cfg)
		624	{
		625	timeout = NOW + INITIAL_SYN_TIMEOUT;
		626
		627	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		628	pkt->qdcount = htons (1);
		629
		630	int offs = 6*2;
		631
		632	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&cfg, sizeof (dns_cfg));
		633
		634	assert (elen <= MAX_LBL_SIZE);
		635
		636	(*pkt)[offs] = elen;
		637	offs += elen + 1;
		638	append_domain (*pkt, offs, THISNODE->domain);
		639
		640	(*pkt)[offs++] = 0;
		641	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
		642	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		643
		644	pkt->len = offs;
		645	}
		646
		647	struct dns_rcv
		648	{
		649	int seqno;
		650	dns_packet *pkt; // reply packet
		651	u8 data [MAXSIZE]; // actually part of the reply packet...
		652	int datalen;
		653
		654	dns_rcv (int seqno, u8 *data, int datalen);
		655	~dns_rcv ();
		656	};
		657
		658	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
		659	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
		660	{
		661	memcpy (this->data, data, datalen);
		662	}
		663
		664	dns_rcv::~dns_rcv ()
		665	{
		666	delete pkt;
382	}	667	}
383		668
384	/////////////////////////////////////////////////////////////////////////////	669	/////////////////////////////////////////////////////////////////////////////
385		670
386	struct dns_cfg	671	struct dns_connection
387	{	672	{
388	u8 id1, id2, id3;	673	connection *c;
389	u8 def_ttl;	674	struct vpn *vpn;
390	u8 unused1;	675
391	u16 max_size;	676	dns_cfg cfg;
392	u8 flags1, flags2;	677
		678	bool established;
		679
		680	tstamp last_received;
		681	tstamp last_sent;
		682	double last_latency;
		683	double poll_interval, send_interval;
		684
		685	vector<dns_rcv *> rcvpq;
		686
		687	byte_stream rcvdq; int rcvseq;
		688	byte_stream snddq; int sndseq;
		689
		690	void time_cb (time_watcher &w); time_watcher tw;
		691	void receive_rep (dns_rcv *r);
		692
		693	dns_connection (connection *c);
		694	~dns_connection ();
393	};	695	};
394		696
395	dns_packet *	697	dns_connection::dns_connection (connection *c)
		698	: c (c)
		699	, rcvdq (MAX_BACKLOG * 2)
		700	, snddq (MAX_BACKLOG * 2)
		701	, tw (this, &dns_connection::time_cb)
		702	{
		703	vpn = c->vpn;
		704
		705	established = false;
		706
		707	rcvseq = sndseq = 0;
		708
		709	last_sent = last_received = 0;
		710	poll_interval = MIN_POLL_INTERVAL;
		711	send_interval = 0.5; // starting rate
		712	last_latency = INITIAL_TIMEOUT;
		713	}
		714
		715	dns_connection::~dns_connection ()
		716	{
		717	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		718	i != rcvpq.end ();
		719	++i)
		720	delete *i;
		721	}
		722
		723	void dns_connection::receive_rep (dns_rcv *r)
		724	{
		725	if (r->datalen)
		726	{
		727	last_received = NOW;
		728	tw.trigger ();
		729
		730	poll_interval = send_interval;
		731	}
		732	else
		733	{
		734	poll_interval *= 1.5;
		735	if (poll_interval > MAX_POLL_INTERVAL)
		736	poll_interval = MAX_POLL_INTERVAL;
		737	}
		738
		739	rcvpq.push_back (r);
		740
		741	redo:
		742
		743	// find next packet
		744	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
		745	if (SEQNO_EQ (rcvseq, (*i)->seqno))
		746	{
		747	// enter the packet into our input stream
		748	r = *i;
		749
		750	// remove the oldest packet, look forward, as it's oldest first
		751	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		752	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		753	{
		754	delete *j;
		755	rcvpq.erase (j);
		756	break;
		757	}
		758
		759	rcvseq = (rcvseq + 1) & SEQNO_MASK;
		760
		761	if (!rcvdq.put (r->data, r->datalen))
		762	{
		763	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
		764	abort (); // MUST never overflow, can be caused by data corruption, TODO
		765	}
		766
		767	while (vpn_packet *pkt = rcvdq.get ())
		768	{
		769	sockinfo si;
		770	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;
		771
		772	vpn->recv_vpn_packet (pkt, si);
		773
		774	delete pkt;
		775	}
		776
		777	// check for further packets
		778	goto redo;
		779	}
		780	}
		781
		782	void
396	vpn::dnsv4_server (dns_packet *pkt)	783	vpn::dnsv4_server (dns_packet &pkt)
397	{	784	{
398	u16 flags = ntohs (pkt->flags);	785	u16 flags = ntohs (pkt.flags);
399		786
400	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
401	int offs = 6 * 2; // skip header	787	int offs = 6 * 2; // skip header
402		788
403	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	789	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
404		790
405	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	791	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
406	&& pkt->qdcount == htons (1))	792	&& pkt.qdcount == htons (1))
407	{	793	{
408	char qname[MAXSIZE];	794	char qname[MAXSIZE];
409	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	795	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
410		796
411	printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", pkt->len,
412	pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D
413
414	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	797	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
415	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	798	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
416		799
417	pkt->qdcount = htons (1);	800	pkt.qdcount = htons (1);
418	pkt->ancount = 0;	801	pkt.ancount = 0;
419	pkt->nscount = 0; // should be self, as other nameservers reply like this	802	pkt.nscount = 0; // should be self, as other nameservers reply like this
420	pkt->arcount = 0; // a record for self, as other nameservers reply like this	803	pkt.arcount = 0; // a record for self, as other nameservers reply like this
421		804
422	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	805	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
423		806
424	int dlen = strlen (THISNODE->domain);	807	int dlen = strlen (THISNODE->domain);
425		808
426	if (qclass == RR_CLASS_IN	809	if (qclass == RR_CLASS_IN
427	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
428	&& qlen > dlen + 1	810	&& qlen > dlen + 1
429	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	811	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
430	{	812	{
431	// correct class, domain, parse
432	u8 data[MAXSIZE];
433	int datalen = dns64::decode (data, qname, qlen - dlen - 1);
434
435	for (int i = 0; i < datalen; i++)
436	printf ("%02x ", data[i]);
437	printf ("\n");
438
439
440
441
442	#if 0
443	// now generate reply	813	// now generate reply
444	rep->ancount = htons (1); // one answer RR	814	pkt.ancount = htons (1); // one answer RR
445	rep->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	815	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
446		816
447	(*rep) [offs++] = 0xc0;	817	if ((qtype == RR_TYPE_ANY
448	(*rep) [offs++] = 6 * 2; // same as in query section	818	|| qtype == RR_TYPE_TXT
449		819	|| qtype == RR_TYPE_NULL)
450	(*rep) [offs++] = RR_TYPE_TXT >> 8; (*rep) [offs++] = RR_TYPE_TXT;	820	&& qlen > dlen + 1 + HDRSIZE)
451	(*rep) [offs++] = RR_CLASS_IN >> 8; (*rep) [offs++] = RR_CLASS_IN;
452
453	(*rep) [offs++] = 0; (*rep) [offs++] = 0;
454	(*rep) [offs++] = 0; (*rep) [offs++] = 0; // TTL
455
456	int dlen = MAX_PKT_SIZE - offs - 2;
457
458	printf ("we have room for %d bytes\n", dlen);
459
460	int rdlen_offs = offs += 2;
461
462	u8 txt[255];
463	txt[0] = 0;
464	txt[1] = 0;
465
466	int txtlen = 2;
467
468	while (dlen > 1)
469	{	821	{
470	int sndlen = --dlen;	822	// correct class, domain: parse
		823	int client, seqno;
		824	decode_header (qname, client, seqno);
471		825
472	if (sndlen + txtlen > 255)	826	u8 data[MAXSIZE];
473	sndlen = 255 - txtlen;	827	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
474		828
		829	if (0 < client && client <= conns.size ())
		830	{
		831	connection *c = conns [client - 1];
		832	dns_connection *dns = c->dns;
		833	dns_rcv *rcv;
		834	bool in_seq;
		835
		836	if (dns)
		837	{
		838	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
		839	if (SEQNO_EQ ((*i)->seqno, seqno))
		840	{
		841	// already seen that request: simply reply with the cached reply
		842	dns_rcv *r = *i;
		843
		844	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		845
		846	// refresh header & id, as the retry count could have changed
		847	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		848	r->pkt->id = pkt.id;
		849
		850	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		851
		852	goto duplicate_request;
		853	}
		854
		855	in_seq = dns->rcvseq == seqno;
		856
		857	// new packet, queue
		858	rcv = new dns_rcv (seqno, data, datalen);
		859	dns->receive_rep (rcv);
		860	}
		861
		862	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
		863
		864	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		865	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		866	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		867	pkt [offs++] = 0; pkt [offs++] = 0;
		868	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		869
		870	int rdlen_offs = offs += 2;
		871
		872	int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs;
		873	// bind doesn't compress well, so reduce further by one label length
475	sndlen = 0;	874	dlen -= qlen;
476		875
477	(*rep)[offs++] = sndlen + txtlen;	876	if (dns)
478	memcpy (&((*rep)[offs]), txt, txtlen);	877	{
		878	// only put data into in-order sequence packets, if
		879	// we receive out-of-order packets we generate empty
		880	// replies
		881	while (dlen > 1 && !dns->snddq.empty () && in_seq)
		882	{
		883	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		884
		885	if (txtlen > dns->snddq.size ())
		886	txtlen = dns->snddq.size ();
		887
		888	pkt[offs++] = txtlen;
		889	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
479	offs += txtlen;	890	offs += txtlen;
		891	dns->snddq.remove (txtlen);
480		892
481	//if (sndlen + txtlen > dns_snddq.	893	dlen -= txtlen + 1;
		894	}
		895
		896	// avoid empty TXT rdata
		897	if (offs == rdlen_offs)
		898	pkt[offs++] = 0;
		899
		900	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		901	}
		902	else
		903	{
		904	// send RST
		905	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		906	pkt [offs++] = CMD_IP_RST;
		907	}
		908
		909	int rdlen = offs - rdlen_offs;
		910
		911	pkt [rdlen_offs - 2] = rdlen >> 8;
		912	pkt [rdlen_offs - 1] = rdlen;
		913
		914	if (dns)
		915	{
		916	// now update dns_rcv copy
		917	rcv->pkt->len = offs;
		918	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
		919	}
		920
		921	duplicate_request: ;
		922	}
		923	else
		924	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
482	}	925	}
		926	else if (qtype == RR_TYPE_A
		927	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		928	{
		929	dns_cfg cfg;
		930	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		931	int client = ntohs (cfg.client);
483		932
484	int rdlen = offs - rdlen_offs;	933	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
485		934
486	(*rep) [rdlen_offs - 2] = rdlen >> 8;	935	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
487	(*rep) [rdlen_offs - 1] = rdlen;	936	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
488	#endif	937	pkt [offs++] = 0; pkt [offs++] = 0;
		938	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		939	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
		940
		941	slog (L_INFO, _("DNS: client %d tries to connect"), client);
		942
		943	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		944	pkt [offs++] = CMD_IP_REJ;
		945
		946	if (0 < client && client <= conns.size ())
		947	{
		948	connection *c = conns [client - 1];
		949
		950	if (cfg.valid ())
		951	{
		952	pkt [offs - 1] = CMD_IP_SYN;
		953
		954	delete c->dns;
		955	c->dns = new dns_connection (c);
		956	c->dns->cfg = cfg;
		957	}
		958	}
		959	}
489	}	960	}
490	}
491		961
492	pkt->len = offs;	962	pkt.len = offs;
493	return pkt;	963	}
494	}	964	}
495		965
496	void	966	void
497	vpn::dnsv4_client (dns_packet *pkt)	967	vpn::dnsv4_client (dns_packet &pkt)
498	{	968	{
499	u16 flags = ntohs (pkt->flags);	969	u16 flags = ntohs (pkt.flags);
500	int offs = 6 * 2; // skip header	970	int offs = 6 * 2; // skip header
501		971
502	pkt->qdcount = ntohs (pkt->qdcount);	972	pkt.qdcount = ntohs (pkt.qdcount);
503	pkt->ancount = ntohs (pkt->ancount);	973	pkt.ancount = ntohs (pkt.ancount);
504		974
		975	// go through our request list and find the corresponding request
505	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	976	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
506	i != dns_sndpq.end ();	977	i != dns_sndpq.end ();
507	++i)	978	++i)
508	if ((*i)->pkt->id == pkt->id)	979	if ((*i)->pkt->id == pkt.id)
509	{	980	{
		981	dns_connection *dns = (*i)->dns;
510	connection *c = (*i)->conn;	982	connection *c = dns->c;
511	printf ("GOT RESPONSE id %x %p\n", pkt->id, c);//D	983	int seqno = (*i)->seqno;
		984	u8 data[MAXSIZE], *datap = data;
		985
		986	if ((*i)->retry)
		987	{
		988	dns->send_interval *= 1.01;
		989	if (dns->send_interval > MAX_SEND_INTERVAL)
		990	dns->send_interval = MAX_SEND_INTERVAL;
		991	}
		992	else
		993	{
		994	#if 1
		995	dns->send_interval *= 0.999;
		996	#endif
		997	if (dns->send_interval < MIN_SEND_INTERVAL)
		998	dns->send_interval = MIN_SEND_INTERVAL;
		999
		1000	// the latency surely puts an upper bound on
		1001	// the minimum send interval
		1002	double latency = NOW - (*i)->sent;
		1003	dns->last_latency = latency;
		1004
		1005	if (dns->send_interval > latency)
		1006	dns->send_interval = latency;
		1007	}
		1008
512	delete *i;	1009	delete *i;
513	dns_sndpq.erase (i);	1010	dns_sndpq.erase (i);
514		1011
515	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1012	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
516	{	1013	{
517	char qname[MAXSIZE];	1014	char qname[MAXSIZE];
518		1015
519	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1016	while (pkt.qdcount-- && offs < MAXSIZE - 4)
520	{	1017	{
521	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1018	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
522	offs += 4; // skip qtype, qclass	1019	offs += 4; // skip qtype, qclass
523	}	1020	}
524		1021
525	while (pkt->ancount-- && offs < MAXSIZE - 10)	1022	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
526	{	1023	{
527	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1024	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
528		1025
529	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1026	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
530	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1027	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
531	u32 ttl = (*pkt) [offs++] << 24;	1028	u32 ttl = pkt [offs++] << 24;
532	ttl |= (*pkt) [offs++] << 16;	1029	ttl |= pkt [offs++] << 16;
533	ttl |= (*pkt) [offs++] << 8;	1030	ttl |= pkt [offs++] << 8;
534	ttl |= (*pkt) [offs++];	1031	ttl |= pkt [offs++];
535
536	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1032	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
537		1033
538	printf ("REPLY %d:%d TTL %d RD %d\n", qtype, qclass, ttl, rdlen);	1034	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
539
540	offs += rdlen;
541
542	if (MAXSIZE - offs < rdlen)
543	{	1035	{
		1036	if (rdlen <= MAXSIZE - offs)
		1037	{
544	// decode bytes, finally	1038	// decode bytes, finally
		1039
		1040	while (rdlen)
		1041	{
		1042	int txtlen = pkt [offs++];
		1043
		1044	assert (txtlen + offs < MAXSIZE - 1);
		1045
		1046	memcpy (datap, pkt.at (offs), txtlen);
		1047	datap += txtlen; offs += txtlen;
		1048
		1049	rdlen -= txtlen + 1;
		1050	}
		1051	}
		1052	}
		1053	else if (qtype == RR_TYPE_A)
		1054	{
		1055	u8 ip [4];
		1056
		1057	ip [0] = pkt [offs++];
		1058	ip [1] = pkt [offs++];
		1059	ip [2] = pkt [offs++];
		1060	ip [3] = pkt [offs++];
		1061
		1062	if (ip [0] == CMD_IP_1
		1063	&& ip [1] == CMD_IP_2
		1064	&& ip [2] == CMD_IP_3)
		1065	{
		1066	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1067
		1068	if (ip [3] == CMD_IP_RST)
		1069	{
		1070	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1071
		1072	delete dns; c->dns = 0;
		1073
		1074	return;
		1075	}
		1076	else if (ip [3] == CMD_IP_SYN)
		1077	{
		1078	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1079	dns->established = true;
		1080	}
		1081	else if (ip [3] == CMD_IP_REJ)
		1082	{
		1083	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1084	abort ();
		1085	}
		1086	else
		1087	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1088	}
		1089	else
		1090	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1091	ip [0], ip [1], ip [2], ip [3]);
		1092
		1093	return;
		1094	}
		1095
		1096	int client, rseqno;
		1097	decode_header (qname, client, rseqno);
		1098
		1099	if (client != THISNODE->id)
		1100	{
		1101	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1102	datap = 0;
		1103	}
		1104	else if (rseqno != seqno)
		1105	{
		1106	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1107	datap = 0;
545	}	1108	}
546	}	1109	}
547	}	1110	}
548		1111
		1112	// todo: pkt now used
		1113	if (datap)
		1114	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
		1115
549	break;	1116	break;
550	}	1117	}
551	}	1118	}
552		1119
553	void	1120	void
…		…
557	{	1124	{
558	dns_packet *pkt = new dns_packet;	1125	dns_packet *pkt = new dns_packet;
559	struct sockaddr_in sa;	1126	struct sockaddr_in sa;
560	socklen_t sa_len = sizeof (sa);	1127	socklen_t sa_len = sizeof (sa);
561		1128
562	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1129	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
563		1130
564	if (pkt->len > 0)	1131	if (pkt->len > 0)
		1132	{
565	if (THISNODE->dns_port)	1133	if (THISNODE->dns_port)
566	{	1134	{
567	pkt = dnsv4_server (pkt);	1135	dnsv4_server (*pkt);
568	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);	1136	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
569	}	1137	}
570	else	1138	else
571	dnsv4_client (pkt);	1139	dnsv4_client (*pkt);
		1140
		1141	delete pkt;
		1142	}
572	}	1143	}
573	}	1144	}
574		1145
575	bool	1146	bool
576	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1147	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
577	{	1148	{
578	// never initialized	1149	if (!dns)
579	if (!dns_snddq && !dns_rcvdq)	1150	dns = new dns_connection (this);
580	{
581	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
582	dns_snddq = new byte_stream (MAX_BACKLOG);
583
584	dns_rcvseq = dns_sndseq = 0;
585
586	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
587	}
588		1151
589	if (!dns_snddq->put (pkt))	1152	if (!dns->snddq.put (pkt))
590	return false;	1153	return false;
591		1154
592	// start timer if neccessary	1155	dns->tw.trigger ();
593	if (!dnsv4_tw.active)
594	dnsv4_cb (dnsv4_tw);
595		1156
596	return true;	1157	return true;
597	}	1158	}
598		1159
599	void	1160	void
		1161	connection::dnsv4_reset_connection ()
		1162	{
		1163	//delete dns; dns = 0; //TODO
		1164	}
		1165
		1166	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1167
		1168	void
600	connection::dnsv4_cb (time_watcher &w)	1169	dns_connection::time_cb (time_watcher &w)
601	{	1170	{
		1171	// servers have to be polled
		1172	if (THISNODE->dns_port)
		1173	return;
		1174
602	// check for timeouts and (re)transmit	1175	// check for timeouts and (re)transmit
603	tstamp next = NOW + 60;	1176	tstamp next = NOW + poll_interval;
604	dns_req *send = 0;	1177	dns_snd *send = 0;
605		1178
606	slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), vpn->dns_sndpq.size ());
607
608	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1179	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
609	i != vpn->dns_sndpq.end ();	1180	i != vpn->dns_sndpq.end ();
610	++i)	1181	++i)
611	{	1182	{
612	dns_req *r = *i;	1183	dns_snd *r = *i;
613		1184
614	if (r->next <= NOW)	1185	if (r->timeout <= NOW)
615	{	1186	{
616	if (!send)	1187	if (!send)
617	{	1188	{
618	send = r;	1189	send = r;
619		1190
620	slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id);
621	r->retry++;	1191	r->retry++;
622	r->next = NOW + r->retry;	1192	r->timeout = NOW + (r->retry * last_latency * 8.);
		1193
		1194	// the following code changes the query section a bit, forcing
		1195	// the forwarder to generate a new request
		1196	if (r->stdhdr)
		1197	{
		1198	//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);
		1199	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1200	}
623	}	1201	}
624	}	1202	}
		1203	else
		1204	NEXT (r->timeout);
		1205	}
625		1206
626	if (r->next < next)	1207	if (last_sent + send_interval <= NOW)
627	next = r->next;
628	}	1208	{
629
630	if (!send	1209	if (!send)
		1210	{
		1211	// generate a new packet, if wise
		1212
		1213	if (!established)
		1214	{
		1215	if (vpn->dns_sndpq.empty ())
		1216	{
		1217	send = new dns_snd (this);
		1218
		1219	cfg.reset (THISNODE->id);
		1220	send->gen_syn_req (cfg);
		1221	}
		1222	}
631	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1223	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
632	send = new dns_req (this, dns_sndseq++, dns_snddq);	1224	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1225	{
		1226	if (!snddq.empty ())
		1227	{
		1228	poll_interval = send_interval;
		1229	NEXT (NOW + send_interval);
		1230	}
633		1231
634	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);	1232	send = new dns_snd (this);
		1233	send->gen_stream_req (sndseq, snddq);
		1234	send->timeout = NOW + last_latency * 8.;
635		1235
		1236	sndseq = (sndseq + 1) & SEQNO_MASK;
		1237	}
		1238
		1239	if (send)
		1240	vpn->dns_sndpq.push_back (send);
		1241	}
		1242
636	if (send)	1243	if (send)
		1244	{
		1245	last_sent = NOW;
		1246	sendto (vpn->dnsv4_fd,
		1247	send->pkt->at (0), send->pkt->len, 0,
		1248	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1249	}
637	{	1250	}
638	dns_packet *pkt = send->pkt;	1251	else
		1252	NEXT (last_sent + send_interval);
639		1253
640	next = min_next;	1254	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)",
		1255	poll_interval, send_interval, next - NOW,
		1256	vpn->dns_sndpq.size (), snddq.size ());
641		1257
642	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());	1258	// TODO: no idea when this happens, but when next < NOW, we have a problem
643	}	1259	if (next < NOW + 0.0001)
644	else if (next < min_next)	1260	next = NOW + 0.1;
645	next = min_next;
646		1261
647	w.start (next);	1262	w.start (next);
648	}	1263	}
649		1264
650	#endif	1265	#endif

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