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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.6 by pcg, Thu Mar 3 08:38:32 2005 UTC vs.
Revision 1.22 by pcg, Sun Mar 6 21:47:35 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
…		…
23		25
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	27	// it's a hack, use only in emergency situations please.
26		28
27	#include <cstring>	29	#include <cstring>
		30	#include <cassert>
28		31
29	#include <sys/types.h>	32	#include <sys/types.h>
30	#include <sys/socket.h>	33	#include <sys/socket.h>
31	#include <sys/wait.h>	34	#include <sys/wait.h>
32	#include <sys/uio.h>	35	#include <sys/uio.h>
…		…
35	#include <unistd.h>	38	#include <unistd.h>
36	#include <fcntl.h>	39	#include <fcntl.h>
37		40
38	#include <map>	41	#include <map>
39		42
		43	#include <gmp.h>
		44
40	#include "netcompat.h"	45	#include "netcompat.h"
41		46
42	#include "vpn.h"	47	#include "vpn.h"
43		48
44	#define MIN_RETRY 1.	49	#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data
45	#define MAX_RETRY 60.	50	#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data
		51	#define ACTIVITY_INTERVAL 5.
46		52
		53	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		54	#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn
		55
		56	#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
		57	#define MAX_SEND_INTERVAL 0.5 // optimistic?
		58
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	59	#define MAX_OUTSTANDING 10 // max. outstanding requests
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	60	#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	61	#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		62
52	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	63	#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	64	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	65	// every two request bytes less give room for one reply byte
55		66
56	// seqno has 12 bits, but the lower bit is always left as zero
57	// as bind caches ttl=0 records and we have to generate
58	// sequence numbers that always differ case-insensitively
59	#define SEQNO_MASK 0x07ff	67	#define SEQNO_MASK 0x3fff
60		68	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
61	/*
62
63	protocol, in shorthand :)
64
65	client -> server <req> ANY?
66	server -> client <req> TXT <rep>
67
68	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
69	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
70
71	if <client-id> is zero, the connection will be configured:
72
73	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
74
75	*/
76		69
77	#define MAX_LBL_SIZE 63	70	#define MAX_LBL_SIZE 63
78	#define MAX_PKT_SIZE 512	71	#define MAX_PKT_SIZE 512
79		72
		73	#define RR_TYPE_A 1
		74	#define RR_TYPE_NULL 10
80	#define RR_TYPE_TXT 16	75	#define RR_TYPE_TXT 16
81	#define RR_TYPE_ANY 255	76	#define RR_TYPE_ANY 255
		77
82	#define RR_CLASS_IN 1	78	#define RR_CLASS_IN 1
83		79
84	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	80	#define CMD_IP_1 207
85	struct dns64	81	#define CMD_IP_2 46
86	{	82	#define CMD_IP_3 236
87	static const char encode_chars[64 + 1];	83	#define CMD_IP_RST 29
88	static s8 decode_chars[256];	84	#define CMD_IP_SYN 113
		85	#define CMD_IP_REJ 32
89		86
90	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	87	// works for cmaps up to 255 (not 256!)
91	static int decode_len (int bytes) { return (bytes * 6) / 8; }	88	struct charmap
		89	{
		90	enum { INVALID = (u8)255 };
		91
		92	char encode [256]; // index => char
		93	u8 decode [256]; // char => index
		94	unsigned int size;
		95
		96	charmap (const char *cmap);
		97	};
		98
		99	charmap::charmap (const char *cmap)
		100	{
		101	char *enc = encode;
		102	u8 *dec = decode;
		103
		104	memset (enc, (char) 0, 256);
		105	memset (dec, (char)INVALID, 256);
		106
		107	for (size = 0; cmap [size]; size++)
		108	{
		109	enc [size] = cmap [size];
		110	dec [(u8)enc [size]] = size;
		111	}
		112
		113	assert (size < 256);
		114	}
		115
		116	#define MAX_DEC_LEN 500
		117	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		118	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		119
		120	// ugly. minimum base is 16(!)
		121	struct basecoder
		122	{
		123	charmap cmap;
		124	unsigned int enc_len [MAX_DEC_LEN];
		125	unsigned int dec_len [MAX_ENC_LEN];
		126
		127	unsigned int encode_len (unsigned int len);
		128	unsigned int decode_len (unsigned int len);
		129
92	static int encode (char *dst, u8 *src, int len);	130	unsigned int encode (char *dst, u8 *src, unsigned int len);
93	static int decode (u8 *dst, char *src, int len);	131	unsigned int decode (u8 *dst, char *src, unsigned int len);
94		132
95	dns64 ();	133	basecoder (const char *cmap);
96	} dns64;	134	};
97		135
98	// the following sequence has been crafted to	136	basecoder::basecoder (const char *cmap)
99	// a) look somewhat random	137	: cmap (cmap)
100	// b) the even (and odd) indices never share the same character as upper/lowercase
101	const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
102	s8 dns64::decode_chars[256];
103
104	dns64::dns64 ()
105	{	138	{
106	for (int i = 0; i < 64; i++)	139	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
107	decode_chars [encode_chars [i]] = i + 1;	140	{
108	}	141	u8 src [MAX_DEC_LEN];
		142	u8 dst [MAX_ENC_LEN];
109		143
110	int dns64::encode (char *dst, u8 *src, int len)	144	memset (src, 255, len);
		145
		146	mp_limb_t m [MAX_LIMBS];
		147	mp_size_t n;
		148
		149	n = mpn_set_str (m, src, len, 256);
		150	n = mpn_get_str (dst, this->cmap.size, m, n);
		151
		152	for (int i = 0; !dst [i]; ++i)
		153	n--;
		154
		155	enc_len [len] = n;
		156	dec_len [n] = len;
		157	}
		158	}
		159
		160	unsigned int basecoder::encode_len (unsigned int len)
111	{	161	{
112	// slow, but easy to debug	162	return enc_len [len];
113	char *beg = dst;	163	}
114	unsigned int accum, bits = 0;	164
		165	unsigned int basecoder::decode_len (unsigned int len)
		166	{
		167	while (len && !dec_len [len])
		168	--len;
		169
		170	return dec_len [len];
		171	}
		172
		173	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		174	{
		175	if (!len || len > MAX_DEC_LEN)
		176	return 0;
		177
		178	int elen = encode_len (len);
		179
		180	mp_limb_t m [MAX_LIMBS];
		181	mp_size_t n;
		182
		183	u8 dst_ [MAX_ENC_LEN];
		184
		185	n = mpn_set_str (m, src, len, 256);
		186	n = mpn_get_str (dst_, cmap.size, m, n);
		187
		188	int plen = elen; // for padding
		189
		190	while (n < plen)
		191	{
		192	*dst++ = cmap.encode [0];
		193	plen--;
		194	}
		195
		196	for (unsigned int i = n - plen; i < n; ++i)
		197	*dst++ = cmap.encode [dst_ [i]];
		198
		199	return elen;
		200	}
		201
		202	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		203	{
		204	if (!len || len > MAX_ENC_LEN)
		205	return 0;
		206
		207	u8 src_ [MAX_ENC_LEN];
		208	unsigned int elen = 0;
115		209
116	while (len--)	210	while (len--)
117	{	211	{
118	accum <<= 8;	212	u8 val = cmap.decode [(u8)*src++];
119	accum |= *src++;
120	bits += 8;
121		213
122	while (bits >= 6)	214	if (val != charmap::INVALID)
123	{	215	src_ [elen++] = val;
124	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	216	}
125	bits -= 6;	217
126	}	218	int dlen = decode_len (elen);
		219
		220	mp_limb_t m [MAX_LIMBS];
		221	mp_size_t n;
		222
		223	u8 dst_ [MAX_DEC_LEN];
		224
		225	n = mpn_set_str (m, src_, elen, cmap.size);
		226	n = mpn_get_str (dst_, 256, m, n);
		227
		228	if (n < dlen)
127	}	229	{
		230	memset (dst, 0, dlen - n);
		231	memcpy (dst + dlen - n, dst_, n);
		232	}
		233	else
		234	memcpy (dst, dst_ + n - dlen, dlen);
128		235
129	if (bits)	236	return dlen;
130	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
131
132	return dst - beg;
133	}	237	}
134		238
135	int dns64::decode (u8 *dst, char *src, int len)	239	#if 0
136	{	240	struct test { test (); } test;
137	// slow, but easy to debug
138	u8 *beg = dst;
139	unsigned int accum, bits = 0;
140		241
141	while (len--)	242	test::test ()
		243	{
		244	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		245
		246	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		247	static char enc[200];
		248	static u8 dec[200];
		249
		250	for (int i = 1; i < 20; i++)
142	{	251	{
143	s8 chr = decode_chars [(u8)*src++];	252	int elen = cdc.encode (enc, in, i);
		253	int dlen = cdc.decode (dec, enc, elen);
144		254
145	if (!chr)	255	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
146	continue;
147
148	accum <<= 6;
149	accum |= chr - 1;
150	bits += 6;
151
152	while (bits >= 8)
153	{
154	*dst++ = accum >> (bits - 8);
155	bits -= 8;
156	}
157	}	256	}
		257	abort ();
		258	}
		259	#endif
158		260
159	return dst - beg;	261	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		262	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		263	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		264	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		265	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		266
		267	/////////////////////////////////////////////////////////////////////////////
		268
		269	#define HDRSIZE 6
		270
		271	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		272	{
		273	seqno &= SEQNO_MASK;
		274
		275	u8 hdr[3] = {
		276	clientid,
		277	(seqno >> 8) | (retry << 6),
		278	seqno,
		279	};
		280
		281	assert (clientid < 256);
		282
		283	cdc26.encode (data, hdr, 3);
		284	}
		285
		286	inline void decode_header (char *data, int &clientid, int &seqno)
		287	{
		288	u8 hdr[3];
		289
		290	cdc26.decode (hdr, data, HDRSIZE);
		291
		292	clientid = hdr[0];
		293	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
160	}	294	}
161		295
162	/////////////////////////////////////////////////////////////////////////////	296	/////////////////////////////////////////////////////////////////////////////
163		297
164	struct byte_stream	298	struct byte_stream
…		…
193	}	327	}
194		328
195	void byte_stream::remove (int count)	329	void byte_stream::remove (int count)
196	{	330	{
197	if (count > fill)	331	if (count > fill)
198	abort ();	332	assert (count <= fill);
199		333
200	memmove (data, data + count, fill -= count);	334	memmove (data, data + count, fill -= count);
201	}	335	}
202		336
203	bool byte_stream::put (u8 *data, unsigned int datalen)	337	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
216	return false;	350	return false;
217		351
218	data [fill++] = pkt->len >> 8;	352	data [fill++] = pkt->len >> 8;
219	data [fill++] = pkt->len;	353	data [fill++] = pkt->len;
220		354
221	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	355	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
222		356
223	return true;	357	return true;
224	}	358	}
225		359
226	vpn_packet *byte_stream::get ()	360	vpn_packet *byte_stream::get ()
227	{	361	{
		362	unsigned int len;
		363
		364	for (;;)
		365	{
228	int len = (data [0] << 8) | data [1];	366	len = (data [0] << 8) | data [1];
229		367
230	if (len > MAXSIZE && fill >= 2)	368	if (len <= MAXSIZE || fill < 2)
231	abort (); // TODO handle this gracefully, connection reset	369	break;
232		370
		371	// TODO: handle this better than skipping, e.g. by reset
		372	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		373	remove (1);
		374	}
		375
233	if (fill < len + 2)	376	if (fill < len + 2)
234	return 0;	377	return 0;
235		378
236	vpn_packet *pkt = new vpn_packet;	379	vpn_packet *pkt = new vpn_packet;
237		380
238	pkt->len = len;	381	pkt->len = len;
239	memcpy (&((*pkt)[0]), data + 2, len);	382	memcpy (pkt->at (0), data + 2, len);
240	remove (len + 2);	383	remove (len + 2);
241		384
242	return pkt;	385	return pkt;
243	}	386	}
244		387
245	/////////////////////////////////////////////////////////////////////////////	388	/////////////////////////////////////////////////////////////////////////////
246		389
247	#define FLAG_QUERY ( 0 << 15)	390	#define FLAG_QUERY ( 0 << 15)
248	#define FLAG_RESPONSE ( 1 << 15)	391	#define FLAG_RESPONSE ( 1 << 15)
249	#define FLAG_OP_MASK (15 << 14)	392	#define FLAG_OP_MASK (15 << 11)
250	#define FLAG_OP_QUERY ( 0 << 11)	393	#define FLAG_OP_QUERY ( 0 << 11)
251	#define FLAG_AA ( 1 << 10)	394	#define FLAG_AA ( 1 << 10)
252	#define FLAG_TC ( 1 << 9)	395	#define FLAG_TC ( 1 << 9)
253	#define FLAG_RD ( 1 << 8)	396	#define FLAG_RD ( 1 << 8)
254	#define FLAG_RA ( 1 << 7)	397	#define FLAG_RA ( 1 << 7)
…		…
261	#define FLAG_RCODE_REFUSED ( 5 << 0)	404	#define FLAG_RCODE_REFUSED ( 5 << 0)
262		405
263	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	406	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
264	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)	407	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
265		408
		409	struct dns_cfg
		410	{
		411	static int next_uid;
		412
		413	u8 id1, id2, id3, id4;
		414	u8 version;
		415	u8 rrtype;
		416	u8 flags;
		417	u8 def_ttl;
		418	u8 rcv_cdc;
		419	u8 snd_cdc;
		420	u16 max_size;
		421	u16 client;
		422	u16 uid; // to make request unique
		423
		424	u8 reserved[8];
		425
		426	void reset (int clientid);
		427	bool valid ();
		428	};
		429
		430	int dns_cfg::next_uid;
		431
		432	void dns_cfg::reset (int clientid)
		433	{
		434	id1 = 'G';
		435	id2 = 'V';
		436	id3 = 'P';
		437	id4 = 'E';
		438
		439	version = 1;
		440
		441	rrtype = RR_TYPE_TXT;
		442	flags = 0;
		443	def_ttl = 1;
		444	rcv_cdc = 0;
		445	snd_cdc = 62;
		446	max_size = ntohs (MAX_PKT_SIZE);
		447	client = ntohs (clientid);
		448	uid = next_uid++;
		449
		450	memset (reserved, 0, 8);
		451	}
		452
		453	bool dns_cfg::valid ()
		454	{
		455	return id1 == 'G'
		456	&& id2 == 'V'
		457	&& id3 == 'P'
		458	&& id4 == 'E'
		459	&& version == 1
		460	&& flags == 0
		461	&& rcv_cdc == 0
		462	&& snd_cdc == 62
		463	&& max_size == ntohs (MAX_PKT_SIZE);
		464	}
		465
266	struct dns_packet : net_packet	466	struct dns_packet : net_packet
267	{	467	{
268	u16 id;	468	u16 id;
269	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	469	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
270	u16 qdcount, ancount, nscount, arcount;	470	u16 qdcount, ancount, nscount, arcount;
…		…
308	return data - orig;	508	return data - orig;
309	}	509	}
310		510
311	/////////////////////////////////////////////////////////////////////////////	511	/////////////////////////////////////////////////////////////////////////////
312		512
313	struct dns_req
314	{
315	dns_packet *pkt;
316	tstamp next;
317	int retry;
318	connection *conn;
319	int seqno;
320
321	dns_req (connection *c);
322	void gen_stream_req (int seqno, byte_stream *stream);
323	};
324
325	static u16 dns_id = 12098; // TODO: should be per-vpn	513	static u16 dns_id = 0; // TODO: should be per-vpn
326		514
327	static u16 next_id ()	515	static u16 next_id ()
328	{	516	{
		517	if (!dns_id)
		518	dns_id = time (0);
		519
329	// the simplest lsfr with periodicity 65535 i could find	520	// the simplest lsfr with periodicity 65535 i could find
330	dns_id = (dns_id << 1)	521	dns_id = (dns_id << 1)
331	| (((dns_id >> 1)	522	| (((dns_id >> 1)
332	^ (dns_id >> 2)	523	^ (dns_id >> 2)
333	^ (dns_id >> 4)	524	^ (dns_id >> 4)
334	^ (dns_id >> 15)) & 1);	525	^ (dns_id >> 15)) & 1);
335		526
336	return dns_id;	527	return dns_id;
337	}	528	}
338		529
339	dns_req::dns_req (connection *c)	530	struct dns_rcv;
340	: conn (c)	531	struct dns_snd;
		532
		533	struct dns_connection
341	{	534	{
342	next = 0;	535	connection *c;
		536	struct vpn *vpn;
		537
		538	dns_cfg cfg;
		539
		540	bool established;
		541
		542	tstamp last_received;
		543	tstamp last_sent;
		544	double last_latency;
		545	double poll_interval, send_interval;
		546
		547	vector<dns_rcv *> rcvpq;
		548
		549	byte_stream rcvdq; int rcvseq;
		550	byte_stream snddq; int sndseq;
		551
		552	void time_cb (time_watcher &w); time_watcher tw;
		553	void receive_rep (dns_rcv *r);
		554
		555	dns_connection (connection *c);
		556	~dns_connection ();
		557	};
		558
		559	struct dns_snd
		560	{
		561	dns_packet *pkt;
		562	tstamp timeout, sent;
		563	int retry;
		564	struct dns_connection *dns;
		565	int seqno;
		566	bool stdhdr;
		567
		568	void gen_stream_req (int seqno, byte_stream &stream);
		569	void gen_syn_req ();
		570
		571	dns_snd (dns_connection *dns);
		572	~dns_snd ();
		573	};
		574
		575	dns_snd::dns_snd (dns_connection *dns)
		576	: dns (dns)
		577	{
		578	timeout = 0;
343	retry = 0;	579	retry = 0;
		580	seqno = 0;
		581	sent = NOW;
		582	stdhdr = false;
344		583
345	pkt = new dns_packet;	584	pkt = new dns_packet;
346		585
347	pkt->id = next_id ();	586	pkt->id = next_id ();
348	}	587	}
349		588
		589	dns_snd::~dns_snd ()
		590	{
		591	delete pkt;
		592	}
		593
		594	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		595	{
		596	// add tunnel domain
		597	for (;;)
		598	{
		599	const char *end = strchr (domain, '.');
		600
		601	if (!end)
		602	end = domain + strlen (domain);
		603
		604	int len = end - domain;
		605
		606	pkt [offs++] = len;
		607	memcpy (pkt.at (offs), domain, len);
		608	offs += len;
		609
		610	if (!*end)
		611	break;
		612
		613	domain = end + 1;
		614	}
		615	}
		616
350	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	617	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
351	{	618	{
		619	stdhdr = true;
352	this->seqno = seqno;	620	this->seqno = seqno;
		621
		622	timeout = NOW + INITIAL_TIMEOUT;
353		623
354	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	624	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
355	pkt->qdcount = htons (1);	625	pkt->qdcount = htons (1);
356		626
357	int offs = 6*2;	627	int offs = 6*2;
358	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	628	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
359	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,	629	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
360	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra	630	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
361		631
362	u8 data[256]; //TODO
363
364	data[0] = THISNODE->id; //TODO
365	data[1] = seqno >> 7; //TODO
366	data[2] = seqno << 1; //TODO
367
368	int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
369
370	if (datalen > stream->size ())
371	datalen = stream->size ();
372
373	char enc[256], *encp = enc;	632	char enc[256], *encp = enc;
374		633	encode_header (enc, THISNODE->id, seqno);
375	memcpy (data + 3, stream->begin (), datalen);	634
376	int enclen = dns64::encode (enc, data, datalen + 3);	635	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		636
		637	if (datalen > stream.size ())
		638	datalen = stream.size ();
		639
		640	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
377	stream->remove (datalen);	641	stream.remove (datalen);
378		642
379	while (enclen)	643	while (enclen)
380	{	644	{
381	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	645	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
382		646
…		…
387	encp += lbllen;	651	encp += lbllen;
388		652
389	enclen -= lbllen;	653	enclen -= lbllen;
390	}	654	}
391		655
392	const char *suffix = THISNODE->domain;	656	append_domain (*pkt, offs, dns->c->conf->domain);
393
394	// add tunnel domain
395	for (;;)
396	{
397	const char *end = strchr (suffix, '.');
398
399	if (!end)
400	end = suffix + strlen (suffix);
401
402	int len = end - suffix;
403
404	(*pkt)[offs++] = len;
405	memcpy (&((*pkt)[offs]), suffix, len);
406	offs += len;
407
408	if (!*end)
409	break;
410
411	suffix = end + 1;
412	}
413		657
414	(*pkt)[offs++] = 0;	658	(*pkt)[offs++] = 0;
415	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	659	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		660	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		661
		662	pkt->len = offs;
		663	}
		664
		665	void dns_snd::gen_syn_req ()
		666	{
		667	timeout = NOW + INITIAL_SYN_TIMEOUT;
		668
		669	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		670	pkt->qdcount = htons (1);
		671
		672	int offs = 6 * 2;
		673
		674	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		675
		676	assert (elen <= MAX_LBL_SIZE);
		677
		678	(*pkt)[offs] = elen;
		679	offs += elen + 1;
		680	append_domain (*pkt, offs, dns->c->conf->domain);
		681
		682	(*pkt)[offs++] = 0;
		683	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
416	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	684	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
417		685
418	pkt->len = offs;	686	pkt->len = offs;
419	}	687	}
420		688
…		…
439	{	707	{
440	delete pkt;	708	delete pkt;
441	}	709	}
442		710
443	/////////////////////////////////////////////////////////////////////////////	711	/////////////////////////////////////////////////////////////////////////////
444		712
445	struct dns_cfg	713	dns_connection::dns_connection (connection *c)
		714	: c (c)
		715	, rcvdq (MAX_BACKLOG * 2)
		716	, snddq (MAX_BACKLOG * 2)
		717	, tw (this, &dns_connection::time_cb)
446	{	718	{
447	u8 id1, id2, id3;	719	vpn = c->vpn;
448	u8 def_ttl;
449	u8 unused1;
450	u16 max_size;
451	u8 flags1, flags2;
452	};
453		720
		721	established = false;
		722
		723	rcvseq = sndseq = 0;
		724
		725	last_sent = last_received = 0;
		726	poll_interval = MIN_POLL_INTERVAL;
		727	send_interval = 0.5; // starting rate
		728	last_latency = INITIAL_TIMEOUT;
		729	}
		730
		731	dns_connection::~dns_connection ()
		732	{
		733	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		734	i != rcvpq.end ();
		735	++i)
		736	delete *i;
		737	}
		738
454	void connection::dnsv4_receive_rep (struct dns_rcv *r)	739	void dns_connection::receive_rep (dns_rcv *r)
455	{	740	{
		741	if (r->datalen)
		742	{
		743	last_received = NOW;
		744	tw.trigger ();
		745
		746	poll_interval = send_interval;
		747	}
		748	else
		749	{
		750	poll_interval *= 1.5;
		751	if (poll_interval > MAX_POLL_INTERVAL)
		752	poll_interval = MAX_POLL_INTERVAL;
		753	}
		754
456	dns_rcvpq.push_back (r);	755	rcvpq.push_back (r);
457		756
458	redo:	757	redo:
459		758
		759	// find next packet
460	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	760	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461	i != dns_rcvpq.end ();
462	++i)
463	if (dns_rcvseq == (*i)->seqno)	761	if (SEQNO_EQ (rcvseq, (*i)->seqno))
464	{	762	{
		763	// enter the packet into our input stream
465	dns_rcv *r = *i;	764	r = *i;
466		765
		766	// remove the oldest packet, look forward, as it's oldest first
		767	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		768	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		769	{
		770	delete *j;
		771	rcvpq.erase (j);
		772	break;
		773	}
		774
467	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	775	rcvseq = (rcvseq + 1) & SEQNO_MASK;
468		776
469	if (!dns_snddq && !dns_rcvdq)	777	if (!rcvdq.put (r->data, r->datalen))
470	{	778	{
471	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	779	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472	dns_snddq = new byte_stream (MAX_BACKLOG);	780	abort (); // MUST never overflow, can be caused by data corruption, TODO
473
474	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
475	}	781	}
476		782
477	if (!dns_rcvdq->put (r->data, r->datalen))
478	abort (); // MUST never overflow, can be caused by data corruption, TODO
479
480	while (vpn_packet *pkt = dns_rcvdq->get ())	783	while (vpn_packet *pkt = rcvdq.get ())
481	{	784	{
482	sockinfo si;	785	sockinfo si;
483	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	786	si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4;
484		787
485	vpn->recv_vpn_packet (pkt, si);	788	vpn->recv_vpn_packet (pkt, si);
		789
		790	delete pkt;
486	}	791	}
487	}	792
488	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	793	// check for further packets
489	{
490	//D
491	//abort();
492	printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
493	dns_rcvpq.erase (i);
494	goto redo;	794	goto redo;
495	}	795	}
496	}	796	}
497		797
498	dns_packet *	798	void
499	vpn::dnsv4_server (dns_packet *pkt)	799	vpn::dnsv4_server (dns_packet &pkt)
500	{	800	{
501	u16 flags = ntohs (pkt->flags);	801	u16 flags = ntohs (pkt.flags);
502		802
503	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504	int offs = 6 * 2; // skip header	803	int offs = 6 * 2; // skip header
505		804
506	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	805	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507		806
508	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	807	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509	&& pkt->qdcount == htons (1))	808	&& pkt.qdcount == htons (1))
510	{	809	{
511	char qname[MAXSIZE];	810	char qname[MAXSIZE];
512	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	811	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513		812
514	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	813	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	814	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516		815
517	pkt->qdcount = htons (1);	816	pkt.qdcount = htons (1);
518	pkt->ancount = 0;	817	pkt.ancount = 0;
519	pkt->nscount = 0; // should be self, as other nameservers reply like this	818	pkt.nscount = 0; // should be self, as other nameservers reply like this
520	pkt->arcount = 0; // a record for self, as other nameservers reply like this	819	pkt.arcount = 0; // a record for self, as other nameservers reply like this
521		820
522	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	821	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523		822
524	int dlen = strlen (THISNODE->domain);	823	int dlen = strlen (THISNODE->domain);
525		824
526	if (qclass == RR_CLASS_IN	825	if (qclass == RR_CLASS_IN
527	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528	&& qlen > dlen + 1	826	&& qlen > dlen + 1
529	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	827	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))
530	{	828	{
531	// correct class, domain: parse	829	// now generate reply
532	u8 data[MAXSIZE];	830	pkt.ancount = htons (1); // one answer RR
533	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	831	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534		832
535	int client = data[0];	833	if ((qtype == RR_TYPE_ANY
536	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	834	|| qtype == RR_TYPE_TXT
537		835	|| qtype == RR_TYPE_NULL)
538	if (0 < client && client <= conns.size ())	836	&& qlen > dlen + 1 + HDRSIZE)
539	{	837	{
		838	// correct class, domain: parse
		839	int client, seqno;
		840	decode_header (qname, client, seqno);
		841
		842	u8 data[MAXSIZE];
		843	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		844
		845	if (0 < client && client <= conns.size ())
		846	{
540	connection *c = conns [client - 1];	847	connection *c = conns [client - 1];
		848	dns_connection *dns = c->dns;
		849	dns_rcv *rcv;
		850	bool in_seq;
541		851
542	redo:	852	if (dns)
543
544	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545	i != c->dns_rcvpq.end ();
546	++i)	853	{
		854	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547	if ((*i)->seqno == seqno)	855	if (SEQNO_EQ ((*i)->seqno, seqno))
		856	{
		857	// already seen that request: simply reply with the cached reply
		858	dns_rcv *r = *i;
		859
		860	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		861
		862	// refresh header & id, as the retry count could have changed
		863	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		864	r->pkt->id = pkt.id;
		865
		866	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		867
		868	goto duplicate_request;
		869	}
		870
		871	in_seq = dns->rcvseq == seqno;
		872
		873	// new packet, queue
		874	rcv = new dns_rcv (seqno, data, datalen);
		875	dns->receive_rep (rcv);
		876	}
		877
548	{	878	{
549	// already seen that request: simply reply with the cached reply	879	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550	dns_rcv *r = *i;
551		880
552	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	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
553		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	{
		900	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		901
		902	if (txtlen > dns->snddq.size ())
		903	txtlen = dns->snddq.size ();
		904
		905	pkt[offs++] = txtlen;
		906	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		907	offs += txtlen;
		908	dns->snddq.remove (txtlen);
		909
		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
554	offs = r->pkt->len;	934	rcv->pkt->len = offs;
555	memcpy (pkt->at (0), r->pkt->at (0), offs);	935	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556	goto duplicate_request;	936	}
557	}	937	}
558		938
559	// new packet, queue	939	duplicate_request: ;
560	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	940	}
561	c->dnsv4_receive_rep (rcv);	941	else
562
563	// now generate reply
564	pkt->ancount = htons (1); // one answer RR
565	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	942	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		943	}
		944	else if (qtype == RR_TYPE_A
		945	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		946	{
		947	dns_cfg cfg;
		948	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		949	int client = ntohs (cfg.client);
566		950
567	(*pkt) [offs++] = 0xc0;
568	(*pkt) [offs++] = 6 * 2; // same as in query section	951	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569		952
570	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	953	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	954	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	955	pkt [offs++] = 0; pkt [offs++] = 0;
574	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	956	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		957	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
575		958
576	int dlen = MAX_PKT_SIZE - offs - 2;	959	slog (L_INFO, _("DNS: client %d tries to connect"), client);
577		960
578	// bind doesn't compress well, so reduce further by one label length	961	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
579	dlen -= qlen;	962	pkt [offs++] = CMD_IP_REJ;
580		963
581	int rdlen_offs = offs += 2;	964	if (0 < client && client <= conns.size ())
582
583	while (c->dns_snddq
584	&& !c->dns_snddq->empty ()
585	&& dlen > 1)
586	{	965	{
587	int txtlen = dlen <= 255 ? dlen - 1 : 255;	966	connection *c = conns [client - 1];
588		967
589	if (txtlen > c->dns_snddq->size ())	968	if (cfg.valid ())
590	txtlen = c->dns_snddq->size ();	969	{
		970	pkt [offs - 1] = CMD_IP_SYN;
591		971
592	(*pkt)[offs++] = txtlen;	972	delete c->dns;
593	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	973	c->dns = new dns_connection (c);
594	offs += txtlen;	974	c->dns->cfg = cfg;
595	c->dns_snddq->remove (txtlen);	975	}
596
597	dlen -= txtlen + 1;
598	}	976	}
599
600	// avoid empty TXT rdata
601	if (offs == rdlen_offs)
602	(*pkt)[offs++] = 0;
603
604	int rdlen = offs - rdlen_offs;
605
606	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
607	(*pkt) [rdlen_offs - 1] = rdlen;
608
609	// now update dns_rcv copy
610	rcv->pkt->len = offs;
611	memcpy (rcv->pkt->at (0), pkt->at (0), offs);
612
613	duplicate_request: ;
614	}	977	}
615	else
616	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617	}	978	}
618		979
619	pkt->len = offs;	980	pkt.len = offs;
620	}	981	}
621
622	return pkt;
623	}	982	}
624		983
625	void	984	void
626	vpn::dnsv4_client (dns_packet *pkt)	985	vpn::dnsv4_client (dns_packet &pkt)
627	{	986	{
628	u16 flags = ntohs (pkt->flags);	987	u16 flags = ntohs (pkt.flags);
629	int offs = 6 * 2; // skip header	988	int offs = 6 * 2; // skip header
630		989
631	pkt->qdcount = ntohs (pkt->qdcount);	990	pkt.qdcount = ntohs (pkt.qdcount);
632	pkt->ancount = ntohs (pkt->ancount);	991	pkt.ancount = ntohs (pkt.ancount);
633		992
634	// go through our request list and find the corresponding request	993	// go through our request list and find the corresponding request
635	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	994	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636	i != dns_sndpq.end ();	995	i != dns_sndpq.end ();
637	++i)	996	++i)
638	if ((*i)->pkt->id == pkt->id)	997	if ((*i)->pkt->id == pkt.id)
639	{	998	{
		999	dns_connection *dns = (*i)->dns;
640	connection *c = (*i)->conn;	1000	connection *c = dns->c;
641	int seqno = (*i)->seqno;	1001	int seqno = (*i)->seqno;
642	u8 data[MAXSIZE], *datap = data;	1002	u8 data[MAXSIZE], *datap = data;
643		1003
		1004	if ((*i)->retry)
		1005	{
		1006	dns->send_interval *= 1.01;
		1007	if (dns->send_interval > MAX_SEND_INTERVAL)
		1008	dns->send_interval = MAX_SEND_INTERVAL;
		1009	}
		1010	else
		1011	{
		1012	#if 1
		1013	dns->send_interval *= 0.999;
		1014	#endif
		1015	if (dns->send_interval < MIN_SEND_INTERVAL)
		1016	dns->send_interval = MIN_SEND_INTERVAL;
		1017
		1018	// the latency surely puts an upper bound on
		1019	// the minimum send interval
		1020	double latency = NOW - (*i)->sent;
		1021	dns->last_latency = latency;
		1022
		1023	if (dns->send_interval > latency)
		1024	dns->send_interval = latency;
		1025	}
		1026
644	delete *i;	1027	delete *i;
645	dns_sndpq.erase (i);	1028	dns_sndpq.erase (i);
646		1029
647	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1030	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648	{	1031	{
649	char qname[MAXSIZE];	1032	char qname[MAXSIZE];
650		1033
651	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1034	while (pkt.qdcount-- && offs < MAXSIZE - 4)
652	{	1035	{
653	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1036	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654	offs += 4; // skip qtype, qclass	1037	offs += 4; // skip qtype, qclass
655	}	1038	}
656		1039
657	while (pkt->ancount-- && offs < MAXSIZE - 10)	1040	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658	{	1041	{
659	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1042	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660		1043
661	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1044	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1045	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663	u32 ttl = (*pkt) [offs++] << 24;	1046	u32 ttl = pkt [offs++] << 24;
664	ttl |= (*pkt) [offs++] << 16;	1047	ttl |= pkt [offs++] << 16;
665	ttl |= (*pkt) [offs++] << 8;	1048	ttl |= pkt [offs++] << 8;
666	ttl |= (*pkt) [offs++];	1049	ttl |= pkt [offs++];
667
668	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1050	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669		1051
670	if (rdlen <= MAXSIZE - offs)	1052	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671	{	1053	{
672	// decode bytes, finally	1054	if (rdlen <= MAXSIZE - offs)
673
674	while (rdlen)
675	{	1055	{
		1056	// decode bytes, finally
		1057
		1058	while (rdlen)
		1059	{
676	int txtlen = (*pkt) [offs++];	1060	int txtlen = pkt [offs++];
677		1061
678	assert (txtlen + offs < MAXSIZE - 1);	1062	assert (txtlen + offs < MAXSIZE - 1);
679		1063
680	memcpy (datap, pkt->at (offs), txtlen);	1064	memcpy (datap, pkt.at (offs), txtlen);
681	datap += txtlen; offs += txtlen;	1065	datap += txtlen; offs += txtlen;
682		1066
683	rdlen -= txtlen + 1;	1067	rdlen -= txtlen + 1;
		1068	}
684	}	1069	}
685
686	}	1070	}
		1071	else if (qtype == RR_TYPE_A)
		1072	{
		1073	u8 ip [4];
687		1074
		1075	ip [0] = pkt [offs++];
		1076	ip [1] = pkt [offs++];
		1077	ip [2] = pkt [offs++];
		1078	ip [3] = pkt [offs++];
		1079
		1080	if (ip [0] == CMD_IP_1
		1081	&& ip [1] == CMD_IP_2
		1082	&& ip [2] == CMD_IP_3)
		1083	{
		1084	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1085
		1086	if (ip [3] == CMD_IP_RST)
		1087	{
		1088	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1089
		1090	delete dns; c->dns = 0;
		1091
		1092	return;
		1093	}
		1094	else if (ip [3] == CMD_IP_SYN)
		1095	{
		1096	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1097	dns->established = true;
		1098	}
		1099	else if (ip [3] == CMD_IP_REJ)
		1100	{
		1101	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1102	abort ();
		1103	}
		1104	else
		1105	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1106	}
		1107	else
		1108	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1109	ip [0], ip [1], ip [2], ip [3]);
		1110
		1111	return;
		1112	}
		1113
		1114	int client, rseqno;
		1115	decode_header (qname, client, rseqno);
		1116
		1117	if (client != THISNODE->id)
		1118	{
		1119	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1120	datap = 0;
		1121	}
		1122	else if (rseqno != seqno)
		1123	{
		1124	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1125	datap = 0;
		1126	}
688	}	1127	}
689	}	1128	}
690		1129
691	// todo: pkt now used	1130	// todo: pkt now used
		1131	if (datap)
692	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1132	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693		1133
694	break;	1134	break;
695	}	1135	}
696
697	delete pkt;
698	}	1136	}
699		1137
700	void	1138	void
701	vpn::dnsv4_ev (io_watcher &w, short revents)	1139	vpn::dnsv4_ev (io_watcher &w, short revents)
702	{	1140	{
…		…
704	{	1142	{
705	dns_packet *pkt = new dns_packet;	1143	dns_packet *pkt = new dns_packet;
706	struct sockaddr_in sa;	1144	struct sockaddr_in sa;
707	socklen_t sa_len = sizeof (sa);	1145	socklen_t sa_len = sizeof (sa);
708		1146
709	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1147	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
710		1148
711	if (pkt->len > 0)	1149	if (pkt->len > 0)
712	{	1150	{
713	if (pkt->flags & htons (FLAG_TC))
714	{
715	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));
716	//TODO connection reset
717	}
718
719	if (THISNODE->dns_port)	1151	if (THISNODE->dns_port)
720	{	1152	{
721	pkt = dnsv4_server (pkt);	1153	dnsv4_server (*pkt);
722	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);	1154	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
723	}	1155	}
724	else	1156	else
725	dnsv4_client (pkt);	1157	dnsv4_client (*pkt);
		1158
		1159	delete pkt;
726	}	1160	}
727	}	1161	}
728	}	1162	}
729		1163
730	bool	1164	bool
731	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1165	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
732	{	1166	{
733	// never initialized	1167	int client = ntohs (si.port);
734	if (!dns_snddq && !dns_rcvdq)
735	{
736	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
737	dns_snddq = new byte_stream (MAX_BACKLOG);
738		1168
739	//dns_rcvseq = dns_sndseq = 0;	1169	assert (0 < client && client <= conns.size ());
740		1170
741	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1171	connection *c = conns [client - 1];
742	}	1172
		1173	if (!c->dns)
		1174	c->dns = new dns_connection (c);
743		1175
744	if (!dns_snddq->put (pkt))	1176	if (!c->dns->snddq.put (pkt))
745	return false;	1177	return false;
746		1178
747	// start timer if neccessary	1179	c->dns->tw.trigger ();
748	if (!THISNODE->dns_port && !dnsv4_tw.active)
749	dnsv4_cb (dnsv4_tw);
750		1180
751	return true;	1181	return true;
752	}	1182	}
753		1183
754	void	1184	void
		1185	connection::dnsv4_reset_connection ()
		1186	{
		1187	//delete dns; dns = 0; //TODO
		1188	}
		1189
		1190	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1191
		1192	void
755	connection::dnsv4_cb (time_watcher &w)	1193	dns_connection::time_cb (time_watcher &w)
756	{	1194	{
		1195	// servers have to be polled
		1196	if (THISNODE->dns_port)
		1197	return;
		1198
757	// check for timeouts and (re)transmit	1199	// check for timeouts and (re)transmit
758	tstamp next = NOW + 60;	1200	tstamp next = NOW + poll_interval;
759	dns_req *send = 0;	1201	dns_snd *send = 0;
760		1202
761	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1203	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762	i != vpn->dns_sndpq.end ();	1204	i != vpn->dns_sndpq.end ();
763	++i)	1205	++i)
764	{	1206	{
765	dns_req *r = *i;	1207	dns_snd *r = *i;
766		1208
767	if (r->next <= NOW)	1209	if (r->timeout <= NOW)
768	{	1210	{
769	if (!send)	1211	if (!send)
770	{	1212	{
771	send = r;	1213	send = r;
772		1214
773	if (r->retry)//D
774	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775	r->retry++;	1215	r->retry++;
776	r->next = NOW + r->retry;	1216	r->timeout = NOW + (r->retry * last_latency * 8.);
		1217
		1218	// the following code changes the query section a bit, forcing
		1219	// the forwarder to generate a new request
		1220	if (r->stdhdr)
		1221	{
		1222	//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);
		1223	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1224	}
777	}	1225	}
778	}	1226	}
		1227	else
		1228	NEXT (r->timeout);
		1229	}
779		1230
780	if (r->next < next)	1231	if (last_sent + send_interval <= NOW)
781	next = r->next;
782	}	1232	{
783
784	if (!send	1233	if (!send)
		1234	{
		1235	// generate a new packet, if wise
		1236
		1237	if (!established)
		1238	{
		1239	if (vpn->dns_sndpq.empty ())
		1240	{
		1241	send = new dns_snd (this);
		1242
		1243	printf ("new conn %p %d\n", this, c->conf->id);//D
		1244	cfg.reset (THISNODE->id);
		1245	send->gen_syn_req ();
		1246	}
		1247	}
785	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)	1248	else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING
786	{	1249	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1250	{
		1251	//printf ("sending data request etc.\n"); //D
		1252	if (!snddq.empty ())
		1253	{
		1254	poll_interval = send_interval;
		1255	NEXT (NOW + send_interval);
		1256	}
		1257
787	send = new dns_req (this);	1258	send = new dns_snd (this);
788	send->gen_stream_req (dns_sndseq, dns_snddq);	1259	send->gen_stream_req (sndseq, snddq);
		1260	send->timeout = NOW + last_latency * 8.;
		1261
		1262	sndseq = (sndseq + 1) & SEQNO_MASK;
		1263	}
		1264
		1265	if (send)
789	vpn->dns_sndpq.push_back (send);	1266	vpn->dns_sndpq.push_back (send);
		1267	}
790		1268
791	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792	}
793
794	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795
796	if (send)	1269	if (send)
		1270	{
		1271	last_sent = NOW;
		1272	sendto (vpn->dnsv4_fd,
		1273	send->pkt->at (0), send->pkt->len, 0,
		1274	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
		1275	}
797	{	1276	}
798	dns_packet *pkt = send->pkt;	1277	else
		1278	NEXT (last_sent + send_interval);
799		1279
800	next = min_next;	1280	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)",
		1281	poll_interval, send_interval, next - NOW,
		1282	vpn->dns_sndpq.size (), snddq.size ());
801		1283
802	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());	1284	// TODO: no idea when this happens, but when next < NOW, we have a problem
803	}	1285	if (next < NOW + 0.0001)
804	else if (next < min_next)	1286	next = NOW + 0.1;
805	next = min_next;
806		1287
807	w.start (next);	1288	w.start (next);
808	}	1289	}
809		1290
810	#endif	1291	#endif

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