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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.5 by pcg, Thu Mar 3 07:24:57 2005 UTC vs.
Revision 1.46 by pcg, Thu Dec 6 00:35:29 2007 UTC

1	/*	1	/*
2	vpn_dns.C -- handle the dns tunnel part of the protocol.	2	vpn_dns.C -- handle the dns tunnel part of the protocol.
3	Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com>	3	Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de>
4		4
		5	This file is part of GVPE.
		6
5	This program is free software; you can redistribute it and/or modify	7	GVPE is free software; you can redistribute it and/or modify
6	it under the terms of the GNU General Public License as published by	8	it under the terms of the GNU General Public License as published by
7	the Free Software Foundation; either version 2 of the License, or	9	the Free Software Foundation; either version 2 of the License, or
8	(at your option) any later version.	10	(at your option) any later version.
9		11
10	This program is distributed in the hope that it will be useful,	12	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.	15	GNU General Public License for more details.
14		16
15	You should have received a copy of the GNU General Public License	17	You should have received a copy of the GNU General Public License
16	along with this program; if not, write to the Free Software	18	along with gvpe; if not, write to the Free Software
17	Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA	19	Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18	*/	20	*/
		21
		22	// TODO: EDNS0 option to increase dns mtu?
		23	// TODO: re-write dns packet parsing/creation using a safe mem-buffer
		24	// to ensure no buffer overflows or similar problems.
19		25
20	#include "config.h"	26	#include "config.h"
21		27
22	#if ENABLE_DNS	28	#if ENABLE_DNS
23		29
24	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	30	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
25	// it's a hack, use only in emergency situations please.	31	// it's a hack, use only in emergency situations please.
26		32
27	#include <cstring>	33	#include <cstring>
		34	#include <cassert>
28		35
29	#include <sys/types.h>	36	#include <sys/types.h>
30	#include <sys/socket.h>	37	#include <sys/socket.h>
31	#include <sys/wait.h>	38	#include <sys/wait.h>
32	#include <sys/uio.h>	39	#include <sys/uio.h>
…		…
35	#include <unistd.h>	42	#include <unistd.h>
36	#include <fcntl.h>	43	#include <fcntl.h>
37		44
38	#include <map>	45	#include <map>
39		46
		47	#include <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */
		48	#include <gmp.h>
		49
40	#include "netcompat.h"	50	#include "netcompat.h"
41		51
42	#include "vpn.h"	52	#include "vpn.h"
43		53
44	#define MIN_RETRY 1.	54	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	55	#define ACTIVITY_INTERVAL 5.
46		56
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	57	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		58	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
		59
		60	#define MAX_SEND_INTERVAL 2. // optimistic?
		61
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	62	#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	63	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		64
52	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	65	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
53	// 240 leaves about 4 bytes of server reply data	66	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	67	// every request byte less give room for two reply bytes
55		68
56	#define SEQNO_MASK 0xffff	69	#define SEQNO_MASK 0x3fff
57		70	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
58	/*
59
60	protocol, in shorthand :)
61
62	client -> server <req> ANY?
63	server -> client <req> TXT <rep>
64
65	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
66	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
67
68	if <client-id> is zero, the connection will be configured:
69
70	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
71
72	*/
73		71
74	#define MAX_LBL_SIZE 63	72	#define MAX_LBL_SIZE 63
75	#define MAX_PKT_SIZE 512	73	#define MAX_PKT_SIZE 512
76		74
		75	#define RR_TYPE_A 1
		76	#define RR_TYPE_NULL 10
77	#define RR_TYPE_TXT 16	77	#define RR_TYPE_TXT 16
78	#define RR_TYPE_ANY 255	78	#define RR_TYPE_ANY 255
		79
79	#define RR_CLASS_IN 1	80	#define RR_CLASS_IN 1
80		81
81	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	82	#define CMD_IP_1 207
82	struct dns64	83	#define CMD_IP_2 46
83	{	84	#define CMD_IP_3 236
84	static const char encode_chars[64 + 1];	85	#define CMD_IP_RST 29
85	static s8 decode_chars[256];	86	#define CMD_IP_SYN 113
		87	#define CMD_IP_REJ 32
86		88
87	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	89	// works for cmaps up to 255 (not 256!)
88	static int decode_len (int bytes) { return (bytes * 6) / 8; }	90	struct charmap
		91	{
		92	enum { INVALID = (u8)255 };
		93
		94	char encode [256]; // index => char
		95	u8 decode [256]; // char => index
		96	unsigned int size;
		97
		98	charmap (const char *cmap);
		99	};
		100
		101	charmap::charmap (const char *cmap)
		102	{
		103	char *enc = encode;
		104	u8 *dec = decode;
		105
		106	memset (enc, (char) 0, 256);
		107	memset (dec, (char)INVALID, 256);
		108
		109	for (size = 0; cmap [size]; size++)
		110	{
		111	enc [size] = cmap [size];
		112	dec [(u8)enc [size]] = size;
		113	}
		114
		115	assert (size < 256);
		116	}
		117
		118	#define MAX_DEC_LEN 500
		119	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		120	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		121
		122	// ugly. minimum base is 16(!)
		123	struct basecoder
		124	{
		125	charmap cmap;
		126	unsigned int enc_len [MAX_DEC_LEN];
		127	unsigned int dec_len [MAX_ENC_LEN];
		128
		129	unsigned int encode_len (unsigned int len);
		130	unsigned int decode_len (unsigned int len);
		131
89	static int encode (char *dst, u8 *src, int len);	132	unsigned int encode (char *dst, u8 *src, unsigned int len);
90	static int decode (u8 *dst, char *src, int len);	133	unsigned int decode (u8 *dst, char *src, unsigned int len);
91		134
92	dns64 ();	135	basecoder (const char *cmap);
93	} dns64;	136	};
94		137
95	const char dns64::encode_chars[64 + 1] = "_4B9dLphHzrqQmGjkTbJt5svlZX8xSaReEYfwKgF1DP2W6NyVOU70IouACcMn3i-";	138	basecoder::basecoder (const char *cmap)
96	s8 dns64::decode_chars[256];	139	: cmap (cmap)
97
98	dns64::dns64 ()
99	{	140	{
100	for (int i = 0; i < 64; i++)	141	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
101	decode_chars [encode_chars [i]] = i + 1;	142	{
102	}	143	u8 src [MAX_DEC_LEN];
		144	u8 dst [MAX_ENC_LEN];
103		145
104	int dns64::encode (char *dst, u8 *src, int len)	146	memset (src, 255, len);
		147
		148	mp_limb_t m [MAX_LIMBS];
		149	mp_size_t n;
		150
		151	n = mpn_set_str (m, src, len, 256);
		152	n = mpn_get_str (dst, this->cmap.size, m, n);
		153
		154	for (int i = 0; !dst [i]; ++i)
		155	n--;
		156
		157	enc_len [len] = n;
		158	dec_len [n] = len;
		159	}
		160	}
		161
		162	unsigned int basecoder::encode_len (unsigned int len)
105	{	163	{
106	// slow, but easy to debug	164	return enc_len [len];
107	char *beg = dst;	165	}
108	unsigned int accum, bits = 0;	166
		167	unsigned int basecoder::decode_len (unsigned int len)
		168	{
		169	while (len && !dec_len [len])
		170	--len;
		171
		172	return dec_len [len];
		173	}
		174
		175	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		176	{
		177	if (!len || len > MAX_DEC_LEN)
		178	return 0;
		179
		180	int elen = encode_len (len);
		181
		182	mp_limb_t m [MAX_LIMBS];
		183	mp_size_t n;
		184
		185	u8 dst_ [MAX_ENC_LEN];
		186
		187	n = mpn_set_str (m, src, len, 256);
		188	n = mpn_get_str (dst_, cmap.size, m, n);
		189
		190	int plen = elen; // for padding
		191
		192	while (n < plen)
		193	{
		194	*dst++ = cmap.encode [0];
		195	plen--;
		196	}
		197
		198	for (unsigned int i = n - plen; i < n; ++i)
		199	*dst++ = cmap.encode [dst_ [i]];
		200
		201	return elen;
		202	}
		203
		204	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		205	{
		206	if (!len || len > MAX_ENC_LEN)
		207	return 0;
		208
		209	u8 src_ [MAX_ENC_LEN];
		210	unsigned int elen = 0;
109		211
110	while (len--)	212	while (len--)
111	{	213	{
112	accum <<= 8;	214	u8 val = cmap.decode [(u8)*src++];
113	accum |= *src++;
114	bits += 8;
115		215
116	while (bits >= 6)	216	if (val != charmap::INVALID)
117	{	217	src_ [elen++] = val;
118	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	218	}
119	bits -= 6;	219
120	}	220	int dlen = decode_len (elen);
		221
		222	mp_limb_t m [MAX_LIMBS];
		223	mp_size_t n;
		224
		225	u8 dst_ [MAX_DEC_LEN];
		226
		227	n = mpn_set_str (m, src_, elen, cmap.size);
		228	n = mpn_get_str (dst_, 256, m, n);
		229
		230	if (n < dlen)
121	}	231	{
		232	memset (dst, 0, dlen - n);
		233	memcpy (dst + dlen - n, dst_, n);
		234	}
		235	else
		236	memcpy (dst, dst_ + n - dlen, dlen);
122		237
123	if (bits)	238	return dlen;
124	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
125
126	return dst - beg;
127	}	239	}
128		240
129	int dns64::decode (u8 *dst, char *src, int len)	241	#if 0
130	{	242	struct test { test (); } test;
131	// slow, but easy to debug
132	u8 *beg = dst;
133	unsigned int accum, bits = 0;
134		243
135	while (len--)	244	test::test ()
		245	{
		246	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		247
		248	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		249	static char enc[200];
		250	static u8 dec[200];
		251
		252	for (int i = 1; i < 20; i++)
136	{	253	{
137	s8 chr = decode_chars [(u8)*src++];	254	int elen = cdc.encode (enc, in, i);
		255	int dlen = cdc.decode (dec, enc, elen);
138		256
139	if (!chr)	257	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
140	continue;
141
142	accum <<= 6;
143	accum |= chr - 1;
144	bits += 6;
145
146	while (bits >= 8)
147	{
148	*dst++ = accum >> (bits - 8);
149	bits -= 8;
150	}
151	}	258	}
		259	abort ();
		260	}
		261	#endif
152		262
153	return dst - beg;	263	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		264	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		265	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		266	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		267	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		268
		269	/////////////////////////////////////////////////////////////////////////////
		270
		271	#define HDRSIZE 6
		272
		273	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		274	{
		275	seqno &= SEQNO_MASK;
		276
		277	u8 hdr[3] = {
		278	clientid,
		279	(seqno >> 8) | (retry << 6),
		280	seqno,
		281	};
		282
		283	assert (clientid < 256);
		284
		285	cdc26.encode (data, hdr, 3);
		286	}
		287
		288	inline void decode_header (char *data, int &clientid, int &seqno)
		289	{
		290	u8 hdr[3];
		291
		292	cdc26.decode (hdr, data, HDRSIZE);
		293
		294	clientid = hdr[0];
		295	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
154	}	296	}
155		297
156	/////////////////////////////////////////////////////////////////////////////	298	/////////////////////////////////////////////////////////////////////////////
157		299
158	struct byte_stream	300	struct byte_stream
…		…
187	}	329	}
188		330
189	void byte_stream::remove (int count)	331	void byte_stream::remove (int count)
190	{	332	{
191	if (count > fill)	333	if (count > fill)
192	abort ();	334	assert (count <= fill);
193		335
194	memmove (data, data + count, fill -= count);	336	memmove (data, data + count, fill -= count);
195	}	337	}
196		338
197	bool byte_stream::put (u8 *data, unsigned int datalen)	339	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
210	return false;	352	return false;
211		353
212	data [fill++] = pkt->len >> 8;	354	data [fill++] = pkt->len >> 8;
213	data [fill++] = pkt->len;	355	data [fill++] = pkt->len;
214		356
215	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	357	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
216		358
217	return true;	359	return true;
218	}	360	}
219		361
220	vpn_packet *byte_stream::get ()	362	vpn_packet *byte_stream::get ()
221	{	363	{
		364	unsigned int len;
		365
		366	for (;;)
		367	{
222	int len = (data [0] << 8) | data [1];	368	len = (data [0] << 8) | data [1];
223		369
224	printf ("get len %d, fill %d\n", len, fill);//D
225
226	if (len > MAXSIZE && fill >= 2)	370	if (len <= MAXSIZE || fill < 2)
227	abort (); // TODO handle this gracefully, connection reset	371	break;
228		372
		373	// TODO: handle this better than skipping, e.g. by reset
		374	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		375	remove (1);
		376	}
		377
229	if (fill < len + 2)	378	if (fill < len + 2)
230	return 0;	379	return 0;
231		380
232	vpn_packet *pkt = new vpn_packet;	381	vpn_packet *pkt = new vpn_packet;
233		382
234	pkt->len = len;	383	pkt->len = len;
235	memcpy (&((*pkt)[0]), data + 2, len);	384	memcpy (pkt->at (0), data + 2, len);
236	remove (len + 2);	385	remove (len + 2);
237		386
238	return pkt;	387	return pkt;
239	}	388	}
240		389
241	/////////////////////////////////////////////////////////////////////////////	390	/////////////////////////////////////////////////////////////////////////////
242		391
243	#define FLAG_QUERY ( 0 << 15)	392	#define FLAG_QUERY ( 0 << 15)
244	#define FLAG_RESPONSE ( 1 << 15)	393	#define FLAG_RESPONSE ( 1 << 15)
245	#define FLAG_OP_MASK (15 << 14)	394	#define FLAG_OP_MASK (15 << 11)
246	#define FLAG_OP_QUERY ( 0 << 11)	395	#define FLAG_OP_QUERY ( 0 << 11)
247	#define FLAG_AA ( 1 << 10)	396	#define FLAG_AA ( 1 << 10)
248	#define FLAG_TC ( 1 << 9)	397	#define FLAG_TC ( 1 << 9)
249	#define FLAG_RD ( 1 << 8)	398	#define FLAG_RD ( 1 << 8)
250	#define FLAG_RA ( 1 << 7)	399	#define FLAG_RA ( 1 << 7)
…		…
257	#define FLAG_RCODE_REFUSED ( 5 << 0)	406	#define FLAG_RCODE_REFUSED ( 5 << 0)
258		407
259	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	408	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
260	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)	409	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
261		410
		411	struct dns_cfg
		412	{
		413	static int next_uid;
		414
		415	u8 id1, id2, id3, id4;
		416
		417	u8 version;
		418	u8 flags;
		419	u8 rrtype;
		420	u8 def_ttl;
		421
		422	u16 client;
		423	u16 uid; // to make request unique
		424
		425	u16 max_size;
		426	u8 seq_cdc;
		427	u8 req_cdc;
		428
		429	u8 rep_cdc;
		430	u8 delay; // time in 0.01s units that the server may delay replying packets
		431	u8 r3, r4;
		432
		433	u8 r5, r6, r7, r8;
		434
		435	void reset (int clientid);
		436	bool valid ();
		437	};
		438
		439	int dns_cfg::next_uid;
		440
		441	void dns_cfg::reset (int clientid)
		442	{
		443	id1 = 'G';
		444	id2 = 'V';
		445	id3 = 'P';
		446	id4 = 'E';
		447
		448	version = 1;
		449
		450	rrtype = RR_TYPE_TXT;
		451	flags = 0;
		452	def_ttl = 0;
		453	seq_cdc = 26;
		454	req_cdc = 62;
		455	rep_cdc = 0;
		456	max_size = htons (MAX_PKT_SIZE);
		457	client = htons (clientid);
		458	uid = next_uid++;
		459	delay = 0;
		460
		461	r3 = r4 = 0;
		462	r4 = r5 = r6 = r7 = 0;
		463	}
		464
		465	bool dns_cfg::valid ()
		466	{
		467	// although the protocol itself allows for some configurability,
		468	// only the following encoding/decoding settings are implemented.
		469	return id1 == 'G'
		470	&& id2 == 'V'
		471	&& id3 == 'P'
		472	&& id4 == 'E'
		473	&& seq_cdc == 26
		474	&& req_cdc == 62
		475	&& rep_cdc == 0
		476	&& version == 1;
		477	}
		478
262	struct dns_packet : net_packet	479	struct dns_packet : net_packet
263	{	480	{
264	u16 id;	481	u16 id;
265	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	482	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
266	u16 qdcount, ancount, nscount, arcount;	483	u16 qdcount, ancount, nscount, arcount;
267		484
268	u8 data[MAXSIZE - 6 * 2];	485	u8 data [MAXSIZE - 6 * 2];
269		486
270	int decode_label (char *data, int size, int &offs);	487	int decode_label (char *data, int size, int &offs);
271	};	488	};
272		489
273	int dns_packet::decode_label (char *data, int size, int &offs)	490	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
304	return data - orig;	521	return data - orig;
305	}	522	}
306		523
307	/////////////////////////////////////////////////////////////////////////////	524	/////////////////////////////////////////////////////////////////////////////
308		525
309	struct dns_req
310	{
311	dns_packet *pkt;
312	tstamp next;
313	int retry;
314	connection *conn;
315	int seqno;
316
317	dns_req (connection *c);
318	void gen_stream_req (int seqno, byte_stream *stream);
319	};
320
321	static u16 dns_id = 12098; // TODO: should be per-vpn	526	static u16 dns_id = 0; // TODO: should be per-vpn
322		527
323	static u16 next_id ()	528	static u16 next_id ()
324	{	529	{
		530	if (!dns_id)
		531	dns_id = time (0);
		532
325	// the simplest lsfr with periodicity 65535 i could find	533	// the simplest lsfr with periodicity 65535 i could find
326	dns_id = (dns_id << 1)	534	dns_id = (dns_id << 1)
327	| (((dns_id >> 1)	535	| (((dns_id >> 1)
328	^ (dns_id >> 2)	536	^ (dns_id >> 2)
329	^ (dns_id >> 4)	537	^ (dns_id >> 4)
330	^ (dns_id >> 15)) & 1);	538	^ (dns_id >> 15)) & 1);
331		539
332	return dns_id;	540	return dns_id;
333	}	541	}
334		542
335	dns_req::dns_req (connection *c)	543	struct dns_rcv;
336	: conn (c)	544	struct dns_snd;
		545
		546	struct dns_connection
337	{	547	{
338	next = 0;	548	connection *c;
		549	struct vpn *vpn;
		550
		551	dns_cfg cfg;
		552
		553	bool established;
		554
		555	tstamp last_received;
		556	tstamp last_sent;
		557	double min_latency;
		558	double poll_interval, send_interval;
		559
		560	vector<dns_rcv *> rcvpq;
		561
		562	byte_stream rcvdq; int rcvseq; int repseq;
		563	byte_stream snddq; int sndseq;
		564
		565	inline void time_cb (ev::timer &w, int revents); ev::timer tw;
		566	void receive_rep (dns_rcv *r);
		567
		568	dns_connection (connection *c);
		569	~dns_connection ();
		570	};
		571
		572	struct dns_snd
		573	{
		574	dns_packet *pkt;
		575	tstamp timeout, sent;
		576	int retry;
		577	struct dns_connection *dns;
		578	int seqno;
		579	bool stdhdr;
		580
		581	void gen_stream_req (int seqno, byte_stream &stream);
		582	void gen_syn_req ();
		583
		584	dns_snd (dns_connection *dns);
		585	~dns_snd ();
		586	};
		587
		588	dns_snd::dns_snd (dns_connection *dns)
		589	: dns (dns)
		590	{
		591	timeout = 0;
339	retry = 0;	592	retry = 0;
		593	seqno = 0;
		594	sent = ev_now ();
		595	stdhdr = false;
340		596
341	pkt = new dns_packet;	597	pkt = new dns_packet;
342		598
343	pkt->id = next_id ();	599	pkt->id = next_id ();
344	}	600	}
345		601
		602	dns_snd::~dns_snd ()
		603	{
		604	delete pkt;
		605	}
		606
		607	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		608	{
		609	// add tunnel domain
		610	for (;;)
		611	{
		612	const char *end = strchr (domain, '.');
		613
		614	if (!end)
		615	end = domain + strlen (domain);
		616
		617	int len = end - domain;
		618
		619	pkt [offs++] = len;
		620	memcpy (pkt.at (offs), domain, len);
		621	offs += len;
		622
		623	if (!*end)
		624	break;
		625
		626	domain = end + 1;
		627	}
		628	}
		629
346	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	630	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
347	{	631	{
		632	stdhdr = true;
348	this->seqno = seqno;	633	this->seqno = seqno;
		634
		635	timeout = ev_now () + INITIAL_TIMEOUT;
349		636
350	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	637	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
351	pkt->qdcount = htons (1);	638	pkt->qdcount = htons (1);
352		639
353	int offs = 6*2;	640	int offs = 6*2;
354	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	641	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
355	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,	642	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
356	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra	643	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
357		644
358	u8 data[256]; //TODO
359
360	data[0] = THISNODE->id; //TODO
361	data[1] = seqno >> 8; //TODO
362	data[2] = seqno; //TODO
363
364	int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
365
366	if (datalen > stream->size ())
367	datalen = stream->size ();
368
369	char enc[256], *encp = enc;	645	char enc[256], *encp = enc;
370		646	encode_header (enc, THISNODE->id, seqno);
371	memcpy (data + 3, stream->begin (), datalen);	647
372	int enclen = dns64::encode (enc, data, datalen + 3);	648	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		649
		650	if (datalen > stream.size ())
		651	datalen = stream.size ();
		652
		653	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
373	stream->remove (datalen);	654	stream.remove (datalen);
374		655
375	while (enclen)	656	while (enclen)
376	{	657	{
377	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	658	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
378		659
…		…
383	encp += lbllen;	664	encp += lbllen;
384		665
385	enclen -= lbllen;	666	enclen -= lbllen;
386	}	667	}
387		668
388	const char *suffix = THISNODE->domain;	669	append_domain (*pkt, offs, dns->c->conf->domain);
389
390	// add tunnel domain
391	for (;;)
392	{
393	const char *end = strchr (suffix, '.');
394
395	if (!end)
396	end = suffix + strlen (suffix);
397
398	int len = end - suffix;
399
400	(*pkt)[offs++] = len;
401	memcpy (&((*pkt)[offs]), suffix, len);
402	offs += len;
403
404	if (!*end)
405	break;
406
407	suffix = end + 1;
408	}
409		670
410	(*pkt)[offs++] = 0;	671	(*pkt)[offs++] = 0;
411	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	672	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		673	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		674
		675	pkt->len = offs;
		676	}
		677
		678	void dns_snd::gen_syn_req ()
		679	{
		680	timeout = ev_now () + INITIAL_SYN_TIMEOUT;
		681
		682	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		683	pkt->qdcount = htons (1);
		684
		685	int offs = 6 * 2;
		686
		687	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		688
		689	assert (elen <= MAX_LBL_SIZE);
		690
		691	(*pkt)[offs] = elen;
		692	offs += elen + 1;
		693	append_domain (*pkt, offs, dns->c->conf->domain);
		694
		695	(*pkt)[offs++] = 0;
		696	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
412	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	697	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
413		698
414	pkt->len = offs;	699	pkt->len = offs;
415	}	700	}
416		701
…		…
419	int seqno;	704	int seqno;
420	dns_packet *pkt; // reply packet	705	dns_packet *pkt; // reply packet
421	u8 data [MAXSIZE]; // actually part of the reply packet...	706	u8 data [MAXSIZE]; // actually part of the reply packet...
422	int datalen;	707	int datalen;
423		708
424	dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen);	709	dns_rcv (int seqno, u8 *data, int datalen);
425	~dns_rcv ();	710	~dns_rcv ();
426	};	711	};
427		712
428	dns_rcv::dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen)	713	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
429	: seqno (seqno), pkt (new dns_packet), datalen (datalen)	714	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
430	{	715	{
431	memcpy (this->data, data, datalen);	716	memcpy (this->data, data, datalen);
432	pkt->len = req->len;
433	memcpy (pkt->at (0), req->at (0), req->len);
434	}	717	}
435		718
436	dns_rcv::~dns_rcv ()	719	dns_rcv::~dns_rcv ()
437	{	720	{
438	delete pkt;	721	delete pkt;
439	}	722	}
440		723
441	/////////////////////////////////////////////////////////////////////////////	724	/////////////////////////////////////////////////////////////////////////////
442		725
443	struct dns_cfg	726	dns_connection::dns_connection (connection *c)
		727	: c (c)
		728	, rcvdq (MAX_BACKLOG * 2)
		729	, snddq (MAX_BACKLOG)
444	{	730	{
445	u8 id1, id2, id3;	731	tw.set<dns_connection, &dns_connection::time_cb> (this);
446	u8 def_ttl;
447	u8 unused1;
448	u16 max_size;
449	u8 flags1, flags2;
450	};
451		732
		733	vpn = c->vpn;
		734
		735	established = false;
		736
		737	rcvseq = repseq = sndseq = 0;
		738
		739	last_sent = last_received = 0;
		740	poll_interval = 0.5; // starting here
		741	send_interval = 0.5; // starting rate
		742	min_latency = INITIAL_TIMEOUT;
		743	}
		744
		745	dns_connection::~dns_connection ()
		746	{
		747	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		748	i != rcvpq.end ();
		749	++i)
		750	delete *i;
		751	}
		752
452	void connection::dnsv4_receive_rep (struct dns_rcv *r)	753	void dns_connection::receive_rep (dns_rcv *r)
453	{	754	{
		755	if (r->datalen)
		756	{
		757	last_received = ev_now ();
		758	tw ();
		759
		760	poll_interval = send_interval;
		761	}
		762	else
		763	{
		764	poll_interval *= 1.5;
		765
		766	if (poll_interval > MAX_POLL_INTERVAL)
		767	poll_interval = MAX_POLL_INTERVAL;
		768	}
		769
454	dns_rcvpq.push_back (r);	770	rcvpq.push_back (r);
455		771
456	redo:	772	redo:
457		773
		774	// find next packet
458	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	775	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
459	i != dns_rcvpq.end ();
460	++i)
461	if (dns_rcvseq == (*i)->seqno)	776	if (SEQNO_EQ (rcvseq, (*i)->seqno))
462	{	777	{
		778	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		779	// enter the packet into our input stream
463	dns_rcv *r = *i;	780	r = *i;
464		781
		782	// remove the oldest packet, look forward, as it's oldest first
		783	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		784	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		785	{
		786	//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
		787	delete *j;
		788	rcvpq.erase (j);
		789	break;
		790	}
		791
465	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	792	rcvseq = (rcvseq + 1) & SEQNO_MASK;
466		793
467	if (!dns_snddq && !dns_rcvdq)	794	if (!rcvdq.put (r->data, r->datalen))
468	{	795	{
469	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	796	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
470	dns_snddq = new byte_stream (MAX_BACKLOG);	797	abort (); // MUST never overflow, can be caused by data corruption, TODO
471
472	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
473	}	798	}
474		799
475	if (!dns_rcvdq->put (r->data, r->datalen))
476	abort (); // MUST never overflow, can be caused by data corruption, TODO
477
478	while (vpn_packet *pkt = dns_rcvdq->get ())	800	while (vpn_packet *pkt = rcvdq.get ())
479	{	801	{
480	sockinfo si;	802	sockinfo si;
481	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	803	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
482		804
483	vpn->recv_vpn_packet (pkt, si);	805	vpn->recv_vpn_packet (pkt, si);
		806
		807	delete pkt;
484	}	808	}
485	}	809
486	else if ((u32)dns_rcvseq - MAX_WINDOW - (u32)(*i)->seqno < MAX_WINDOW * 2)	810	// check for further packets
487	{
488	dns_rcvpq.erase (i);
489	goto redo;	811	goto redo;
490	}	812	}
491	}	813	}
492		814
493	dns_packet *	815	void
494	vpn::dnsv4_server (dns_packet *pkt)	816	vpn::dnsv4_server (dns_packet &pkt)
495	{	817	{
496	u16 flags = ntohs (pkt->flags);	818	u16 flags = ntohs (pkt.flags);
497		819
498	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
499	int offs = 6 * 2; // skip header	820	int offs = 6 * 2; // skip header
500		821
501	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	822	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
502		823
503	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	824	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
504	&& pkt->qdcount == htons (1))	825	&& pkt.qdcount == htons (1))
505	{	826	{
506	char qname[MAXSIZE];	827	char qname [MAXSIZE];
507	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	828	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
508		829
509	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	830	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
510	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	831	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
511		832
512	pkt->qdcount = htons (1);	833	pkt.qdcount = htons (1);
513	pkt->ancount = 0;	834	pkt.ancount = 0;
514	pkt->nscount = 0; // should be self, as other nameservers reply like this	835	pkt.nscount = 0; // should be self, as other nameservers reply like this
515	pkt->arcount = 0; // a record for self, as other nameservers reply like this	836	pkt.arcount = 0; // a record for self, as other nameservers reply like this
516		837
517	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	838	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
518		839
519	int dlen = strlen (THISNODE->domain);	840	int dlen = strlen (THISNODE->domain);
520		841
521	if (qclass == RR_CLASS_IN	842	if (qclass == RR_CLASS_IN
522	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
523	&& qlen > dlen + 1	843	&& qlen > dlen + 1
524	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	844	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
525	{	845	{
526	// correct class, domain: parse	846	// now generate reply
527	u8 data[MAXSIZE];	847	pkt.ancount = htons (1); // one answer RR
528	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	848	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
529		849
530	int client = data[0];	850	if ((qtype == RR_TYPE_ANY
531	int seqno = ((data[1] << 8) | data[2]) & SEQNO_MASK;	851	|| qtype == RR_TYPE_TXT
532		852	|| qtype == RR_TYPE_NULL)
533	if (0 < client && client <= conns.size ())	853	&& qlen > dlen + 1 + HDRSIZE)
534	{	854	{
		855	// correct class, domain: parse
		856	int client, seqno;
		857	decode_header (qname, client, seqno);
		858
		859	u8 data[MAXSIZE];
		860	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		861
		862	if (0 < client && client <= conns.size ())
		863	{
535	connection *c = conns [client - 1];	864	connection *c = conns [client - 1];
		865	dns_connection *dns = c->dns;
		866	dns_rcv *rcv;
536		867
537	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();	868	if (dns)
538	i != c->dns_rcvpq.end ();
539	++i)	869	{
		870	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
540	if ((*i)->seqno == seqno)	871	if (SEQNO_EQ ((*i)->seqno, seqno))
		872	{
		873	// already seen that request: simply reply with the cached reply
		874	dns_rcv *r = *i;
		875
		876	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		877
		878	// refresh header & id, as the retry count could have changed
		879	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		880	r->pkt->id = pkt.id;
		881
		882	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		883
		884	goto duplicate_request;
		885	}
		886
		887	// new packet, queue
		888	rcv = new dns_rcv (seqno, data, datalen);
		889	dns->receive_rep (rcv);
		890	}
		891
541	{	892	{
542	// already seen that request, just reply with the original reply	893	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
543	dns_rcv *r = *i;
544		894
		895	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		896	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		897	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		898	pkt [offs++] = 0; pkt [offs++] = 0;
		899	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		900
		901	int rdlen_offs = offs += 2;
		902
		903	if (dns)
		904	{
		905	int dlen = ntohs (dns->cfg.max_size) - offs;
		906
		907	// bind doesn't compress well, so reduce further by one label length
		908	dlen -= qlen;
		909
		910	// only put data into in-order sequence packets, if
		911	// we receive out-of-order packets we generate empty
		912	// replies
		913	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		914	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		915	{
		916	dns->repseq = seqno;
		917
		918	while (dlen > 1 && !dns->snddq.empty ())
		919	{
		920	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		921
		922	if (txtlen > dns->snddq.size ())
		923	txtlen = dns->snddq.size ();
		924
		925	pkt[offs++] = txtlen;
		926	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		927	offs += txtlen;
		928	dns->snddq.remove (txtlen);
		929
		930	dlen -= txtlen + 1;
		931	}
		932	}
		933
		934	// avoid completely empty TXT rdata
		935	if (offs == rdlen_offs)
		936	pkt[offs++] = 0;
		937
		938	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		939	}
		940	else
		941	{
		942	// send RST
		943	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		944	pkt [offs++] = CMD_IP_RST;
		945	}
		946
		947	int rdlen = offs - rdlen_offs;
		948
		949	pkt [rdlen_offs - 2] = rdlen >> 8;
		950	pkt [rdlen_offs - 1] = rdlen;
		951
		952	if (dns)
		953	{
		954	// now update dns_rcv copy
545	offs = r->pkt->len;	955	rcv->pkt->len = offs;
546	memcpy (pkt->at (0), r->pkt->at (0), offs);	956	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
547	goto duplicate_request;	957	}
548	}	958	}
549		959
550	// new packet, queue	960	duplicate_request: ;
551	c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data + 3, datalen - 3));	961	}
552		962	else
553	// now generate reply
554	pkt->ancount = htons (1); // one answer RR
555	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	963	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		964	}
		965	else if (qtype == RR_TYPE_A
		966	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		967	{
		968	dns_cfg cfg;
		969	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		970	int client = ntohs (cfg.client);
556		971
557	(*pkt) [offs++] = 0xc0;
558	(*pkt) [offs++] = 6 * 2; // same as in query section	972	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
559		973
560	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	974	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
561	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	975	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
562
563	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	976	pkt [offs++] = 0; pkt [offs++] = 0;
564	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	977	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		978	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
565		979
566	int dlen = MAX_PKT_SIZE - offs - 2;	980	slog (L_INFO, _("DNS: client %d connects"), client);
567		981
568	// bind doesn't compress well, so reduce further by one label length	982	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
569	dlen -= qlen;	983	pkt [offs++] = CMD_IP_REJ;
570		984
571	int rdlen_offs = offs += 2;	985	if (0 < client && client <= conns.size ())
572
573	while (c->dns_snddq
574	&& !c->dns_snddq->empty ()
575	&& dlen > 1)
576	{	986	{
577	int txtlen = dlen <= 255 ? dlen - 1 : 255;	987	connection *c = conns [client - 1];
578		988
579	if (txtlen > c->dns_snddq->size ())	989	if (cfg.valid ())
580	txtlen = c->dns_snddq->size ();	990	{
		991	pkt [offs - 1] = CMD_IP_SYN;
581		992
582	(*pkt)[offs++] = txtlen;	993	delete c->dns;
583	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	994	c->dns = new dns_connection (c);
584	offs += txtlen;	995	c->dns->cfg = cfg;
585	c->dns_snddq->remove (txtlen);	996	}
586
587	dlen -= txtlen + 1;
588	}	997	}
589
590	// avoid empty TXT rdata
591	if (offs == rdlen_offs)
592	(*pkt)[offs++] = 0;
593
594	int rdlen = offs - rdlen_offs;
595
596	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
597	(*pkt) [rdlen_offs - 1] = rdlen;
598
599	duplicate_request: ;
600	}	998	}
601	else
602	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
603	}	999	}
604	}
605	else
606	offs = pkt->len;
607		1000
608	pkt->len = offs;	1001	pkt.len = offs;
609	return pkt;	1002	}
610	}	1003	}
611		1004
612	void	1005	void
613	vpn::dnsv4_client (dns_packet *pkt)	1006	vpn::dnsv4_client (dns_packet &pkt)
614	{	1007	{
615	u16 flags = ntohs (pkt->flags);	1008	u16 flags = ntohs (pkt.flags);
616	int offs = 6 * 2; // skip header	1009	int offs = 6 * 2; // skip header
617		1010
618	pkt->qdcount = ntohs (pkt->qdcount);	1011	pkt.qdcount = ntohs (pkt.qdcount);
619	pkt->ancount = ntohs (pkt->ancount);	1012	pkt.ancount = ntohs (pkt.ancount);
620		1013
621	// go through our request list and find the corresponding request	1014	// go through our request list and find the corresponding request
622	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1015	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
623	i != dns_sndpq.end ();	1016	i != dns_sndpq.end ();
624	++i)	1017	++i)
625	if ((*i)->pkt->id == pkt->id)	1018	if ((*i)->pkt->id == pkt.id)
626	{	1019	{
		1020	dns_connection *dns = (*i)->dns;
627	connection *c = (*i)->conn;	1021	connection *c = dns->c;
628	int seqno = (*i)->seqno;	1022	int seqno = (*i)->seqno;
629	u8 data[MAXSIZE], *datap = data;	1023	u8 data[MAXSIZE], *datap = data;
		1024	//printf ("rcv pkt %x\n", seqno);//D
		1025
		1026	if ((*i)->retry)
		1027	{
		1028	dns->send_interval *= 1.01;
		1029	if (dns->send_interval > MAX_SEND_INTERVAL)
		1030	dns->send_interval = MAX_SEND_INTERVAL;
		1031	}
		1032	else
		1033	{
		1034	#if 0
		1035	dns->send_interval *= 0.999;
		1036	#endif
		1037	// the latency surely puts an upper bound on
		1038	// the minimum send interval
		1039	double latency = ev_now () - (*i)->sent;
		1040
		1041	if (latency < dns->min_latency)
		1042	dns->min_latency = latency;
		1043
		1044	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1045	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1046
		1047	if (dns->send_interval < conf.dns_send_interval)
		1048	dns->send_interval = conf.dns_send_interval;
		1049	}
630		1050
631	delete *i;	1051	delete *i;
632	dns_sndpq.erase (i);	1052	dns_sndpq.erase (i);
633		1053
634	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1054	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
635	{	1055	{
636	char qname[MAXSIZE];	1056	char qname[MAXSIZE];
637		1057
638	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1058	while (pkt.qdcount-- && offs < MAXSIZE - 4)
639	{	1059	{
640	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1060	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
641	offs += 4; // skip qtype, qclass	1061	offs += 4; // skip qtype, qclass
642	}	1062	}
643		1063
644	while (pkt->ancount-- && offs < MAXSIZE - 10)	1064	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
645	{	1065	{
646	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1066	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
647		1067
648	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1068	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
649	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1069	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
650	u32 ttl = (*pkt) [offs++] << 24;	1070	u32 ttl = pkt [offs++] << 24;
651	ttl |= (*pkt) [offs++] << 16;	1071	ttl |= pkt [offs++] << 16;
652	ttl |= (*pkt) [offs++] << 8;	1072	ttl |= pkt [offs++] << 8;
653	ttl |= (*pkt) [offs++];	1073	ttl |= pkt [offs++];
654
655	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1074	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
656		1075
657	if (rdlen <= MAXSIZE - offs)	1076	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
658	{	1077	{
659	// decode bytes, finally	1078	if (rdlen <= MAXSIZE - offs)
660
661	while (rdlen)
662	{	1079	{
		1080	// decode bytes, finally
		1081
		1082	while (rdlen)
		1083	{
663	int txtlen = (*pkt) [offs++];	1084	int txtlen = pkt [offs++];
664		1085
665	assert (txtlen + offs < MAXSIZE - 1);	1086	assert (txtlen + offs < MAXSIZE - 1);
666		1087
667	memcpy (datap, pkt->at (offs), txtlen);	1088	memcpy (datap, pkt.at (offs), txtlen);
668	datap += txtlen; offs += txtlen;	1089	datap += txtlen; offs += txtlen;
669		1090
670	rdlen -= txtlen + 1;	1091	rdlen -= txtlen + 1;
		1092	}
671	}	1093	}
672
673	}	1094	}
		1095	else if (qtype == RR_TYPE_A)
		1096	{
		1097	u8 ip [4];
674		1098
		1099	ip [0] = pkt [offs++];
		1100	ip [1] = pkt [offs++];
		1101	ip [2] = pkt [offs++];
		1102	ip [3] = pkt [offs++];
		1103
		1104	if (ip [0] == CMD_IP_1
		1105	&& ip [1] == CMD_IP_2
		1106	&& ip [2] == CMD_IP_3)
		1107	{
		1108	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1109
		1110	if (ip [3] == CMD_IP_RST)
		1111	{
		1112	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1113
		1114	delete dns; c->dns = 0;
		1115
		1116	return;
		1117	}
		1118	else if (ip [3] == CMD_IP_SYN)
		1119	{
		1120	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1121	dns->established = true;
		1122	}
		1123	else if (ip [3] == CMD_IP_REJ)
		1124	{
		1125	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1126	abort ();
		1127	}
		1128	else
		1129	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1130	}
		1131	else
		1132	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1133	ip [0], ip [1], ip [2], ip [3]);
		1134
		1135	return;
		1136	}
		1137
		1138	int client, rseqno;
		1139	decode_header (qname, client, rseqno);
		1140
		1141	if (client != THISNODE->id)
		1142	{
		1143	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1144	datap = 0;
		1145	}
		1146	else if (rseqno != seqno)
		1147	{
		1148	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1149	datap = 0;
		1150	}
675	}	1151	}
676	}	1152	}
677		1153
		1154	// todo: pkt now used
678	if (datap != data)	1155	if (datap)
679	printf ("%02x %02x %02x %02x\n",
680	data[0],
681	data[1],
682	data[2],
683	data[3]);
684
685	printf ("recv %d,%d\n", pkt->id, seqno, datap - data);//D
686	c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data, datap - data));	1156	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
687		1157
688	break;	1158	break;
689	}	1159	}
690
691	delete pkt;
692	}	1160	}
693		1161
694	void	1162	void
695	vpn::dnsv4_ev (io_watcher &w, short revents)	1163	vpn::dnsv4_ev (ev::io &w, int revents)
696	{	1164	{
697	if (revents & EVENT_READ)	1165	if (revents & EV_READ)
698	{	1166	{
699	dns_packet *pkt = new dns_packet;	1167	dns_packet *pkt = new dns_packet;
700	struct sockaddr_in sa;	1168	struct sockaddr_in sa;
701	socklen_t sa_len = sizeof (sa);	1169	socklen_t sa_len = sizeof (sa);
702		1170
703	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1171	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
704		1172
705	if (pkt->len > 0)	1173	if (pkt->len > 0)
706	{	1174	{
707	if (pkt->flags & htons (FLAG_TC))	1175	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1176	dnsv4_client (*pkt);
		1177	else
708	{	1178	{
709	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1179	dnsv4_server (*pkt);
710	//TODO connection reset	1180	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
711	}	1181	}
712		1182
713	if (THISNODE->dns_port)	1183	delete pkt;
714	{
715	pkt = dnsv4_server (pkt);
716	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}
718	else
719	dnsv4_client (pkt);
720	}	1184	}
721	}	1185	}
722	}	1186	}
723		1187
724	bool	1188	bool
725	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1189	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
726	{	1190	{
727	// never initialized	1191	int client = ntohl (si.host);
728	if (!dns_snddq && !dns_rcvdq)
729	{
730	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
731	dns_snddq = new byte_stream (MAX_BACKLOG);
732		1192
733	//dns_rcvseq = dns_sndseq = 0;	1193	assert (0 < client && client <= conns.size ());
734		1194
735	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1195	connection *c = conns [client - 1];
736	}	1196
		1197	if (!c->dns)
		1198	c->dns = new dns_connection (c);
737		1199
738	if (!dns_snddq->put (pkt))	1200	if (c->dns->snddq.put (pkt))
739	return false;	1201	c->dns->tw ();
740		1202
741	// start timer if neccessary	1203	// always return true even if the buffer overflows
742	if (!THISNODE->dns_port && !dnsv4_tw.active)
743	dnsv4_cb (dnsv4_tw);
744
745	return true;	1204	return true;
746	}	1205	}
747		1206
748	void	1207	void
749	connection::dnsv4_cb (time_watcher &w)	1208	connection::dnsv4_reset_connection ()
750	{	1209	{
		1210	//delete dns; dns = 0; //TODO
		1211	}
		1212
		1213	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1214
		1215	void
		1216	dns_connection::time_cb (ev::timer &w, int revents)
		1217	{
		1218	// servers have to be polled
		1219	if (THISNODE->dns_port)
		1220	return;
		1221
751	// check for timeouts and (re)transmit	1222	// check for timeouts and (re)transmit
752	tstamp next = NOW + 60;	1223	tstamp next = ev::now () + poll_interval;
753	dns_req *send = 0;	1224	dns_snd *send = 0;
754		1225
755	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1226	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
756	i != vpn->dns_sndpq.end ();	1227	i != vpn->dns_sndpq.end ();
757	++i)	1228	++i)
758	{	1229	{
759	dns_req *r = *i;	1230	dns_snd *r = *i;
760		1231
761	if (r->next <= NOW)	1232	if (r->timeout <= ev_now ())
762	{	1233	{
763	if (!send)	1234	if (!send)
764	{	1235	{
765	send = r;	1236	send = r;
766		1237
767	if (r->retry)//D
768	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
769	r->retry++;	1238	r->retry++;
770	r->next = NOW + r->retry;	1239	r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
		1240	//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
		1241
		1242	// the following code changes the query section a bit, forcing
		1243	// the forwarder to generate a new request
		1244	if (r->stdhdr)
		1245	encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
771	}	1246	}
772	}	1247	}
773		1248	else
774	if (r->next < next)	1249	NEXT (r->timeout);
775	next = r->next;
776	}	1250	}
777		1251
778	if (!send	1252	if (!send)
779	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
780	{	1253	{
		1254	// generate a new packet, if wise
		1255
		1256	if (!established)
		1257	{
		1258	if (vpn->dns_sndpq.empty ())
		1259	{
781	send = new dns_req (this);	1260	send = new dns_snd (this);
		1261
		1262	cfg.reset (THISNODE->id);
		1263	send->gen_syn_req ();
		1264	}
		1265	}
		1266	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1267	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1268	{
		1269	if (last_sent + send_interval <= ev_now ())
		1270	{
		1271	//printf ("sending data request etc.\n"); //D
		1272	if (!snddq.empty () || last_received + 1. > ev_now ())
		1273	{
		1274	poll_interval = send_interval;
		1275	NEXT (ev_now () + send_interval);
		1276	}
		1277
		1278	send = new dns_snd (this);
782	send->gen_stream_req (dns_sndseq, dns_snddq);	1279	send->gen_stream_req (sndseq, snddq);
		1280	send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
		1281	//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
		1282
		1283	sndseq = (sndseq + 1) & SEQNO_MASK;
		1284	}
		1285	else
		1286	NEXT (last_sent + send_interval);
		1287	}
		1288
		1289	if (send)
783	vpn->dns_sndpq.push_back (send);	1290	vpn->dns_sndpq.push_back (send);
784
785	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
786	}	1291	}
787
788	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
789		1292
790	if (send)	1293	if (send)
791	{	1294	{
792	dns_packet *pkt = send->pkt;	1295	last_sent = ev_now ();
793		1296	sendto (vpn->dnsv4_fd,
794	next = min_next;	1297	send->pkt->at (0), send->pkt->len, 0,
795		1298	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
796	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
797	}	1299	}
798	else if (next < min_next)
799	next = min_next;
800		1300
801	w.start (next);	1301	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1302	poll_interval, send_interval, next - ev_now (),
		1303	vpn->dns_sndpq.size (), snddq.size (),
		1304	rcvpq.size ());
		1305
		1306	// TODO: no idea when this happens, but when next < ev_now (), we have a problem
		1307	// doesn't seem to happen anymore
		1308	if (next < ev_now () + 0.001)
		1309	next = ev_now () + 0.1;
		1310
		1311	w.start (next - ev_now ());
802	}	1312	}
803		1313
804	#endif	1314	#endif
805		1315

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