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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 1.44 by pcg, Tue Dec 4 14:55:59 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	// 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	69	#define SEQNO_MASK 0x3fff
60		70	#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		71
77	#define MAX_LBL_SIZE 63	72	#define MAX_LBL_SIZE 63
78	#define MAX_PKT_SIZE 512	73	#define MAX_PKT_SIZE 512
79		74
		75	#define RR_TYPE_A 1
		76	#define RR_TYPE_NULL 10
80	#define RR_TYPE_TXT 16	77	#define RR_TYPE_TXT 16
81	#define RR_TYPE_ANY 255	78	#define RR_TYPE_ANY 255
		79
82	#define RR_CLASS_IN 1	80	#define RR_CLASS_IN 1
83		81
84	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	82	#define CMD_IP_1 207
85	struct dns64	83	#define CMD_IP_2 46
86	{	84	#define CMD_IP_3 236
87	static const char encode_chars[64 + 1];	85	#define CMD_IP_RST 29
88	static s8 decode_chars[256];	86	#define CMD_IP_SYN 113
		87	#define CMD_IP_REJ 32
89		88
90	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	89	// works for cmaps up to 255 (not 256!)
91	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
92	static int encode (char *dst, u8 *src, int len);	132	unsigned int encode (char *dst, u8 *src, unsigned int len);
93	static int decode (u8 *dst, char *src, int len);	133	unsigned int decode (u8 *dst, char *src, unsigned int len);
94		134
95	dns64 ();	135	basecoder (const char *cmap);
96	} dns64;	136	};
97		137
98	// the following sequence has been crafted to	138	basecoder::basecoder (const char *cmap)
99	// a) look somewhat random	139	: 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	{	140	{
106	for (int i = 0; i < 64; i++)	141	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
107	decode_chars [encode_chars [i]] = i + 1;	142	{
108	}	143	u8 src [MAX_DEC_LEN];
		144	u8 dst [MAX_ENC_LEN];
109		145
110	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)
111	{	163	{
112	// slow, but easy to debug	164	return enc_len [len];
113	char *beg = dst;	165	}
114	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;
115		211
116	while (len--)	212	while (len--)
117	{	213	{
118	accum <<= 8;	214	u8 val = cmap.decode [(u8)*src++];
119	accum |= *src++;
120	bits += 8;
121		215
122	while (bits >= 6)	216	if (val != charmap::INVALID)
123	{	217	src_ [elen++] = val;
124	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	218	}
125	bits -= 6;	219
126	}	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)
127	}	231	{
		232	memset (dst, 0, dlen - n);
		233	memcpy (dst + dlen - n, dst_, n);
		234	}
		235	else
		236	memcpy (dst, dst_ + n - dlen, dlen);
128		237
129	if (bits)	238	return dlen;
130	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
131
132	return dst - beg;
133	}	239	}
134		240
135	int dns64::decode (u8 *dst, char *src, int len)	241	#if 0
136	{	242	struct test { test (); } test;
137	// slow, but easy to debug
138	u8 *beg = dst;
139	unsigned int accum, bits = 0;
140		243
141	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++)
142	{	253	{
143	s8 chr = decode_chars [(u8)*src++];	254	int elen = cdc.encode (enc, in, i);
		255	int dlen = cdc.decode (dec, enc, elen);
144		256
145	if (!chr)	257	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	}	258	}
		259	abort ();
		260	}
		261	#endif
158		262
159	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;
160	}	296	}
161		297
162	/////////////////////////////////////////////////////////////////////////////	298	/////////////////////////////////////////////////////////////////////////////
163		299
164	struct byte_stream	300	struct byte_stream
…		…
193	}	329	}
194		330
195	void byte_stream::remove (int count)	331	void byte_stream::remove (int count)
196	{	332	{
197	if (count > fill)	333	if (count > fill)
198	abort ();	334	assert (count <= fill);
199		335
200	memmove (data, data + count, fill -= count);	336	memmove (data, data + count, fill -= count);
201	}	337	}
202		338
203	bool byte_stream::put (u8 *data, unsigned int datalen)	339	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
216	return false;	352	return false;
217		353
218	data [fill++] = pkt->len >> 8;	354	data [fill++] = pkt->len >> 8;
219	data [fill++] = pkt->len;	355	data [fill++] = pkt->len;
220		356
221	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	357	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
222		358
223	return true;	359	return true;
224	}	360	}
225		361
226	vpn_packet *byte_stream::get ()	362	vpn_packet *byte_stream::get ()
227	{	363	{
		364	unsigned int len;
		365
		366	for (;;)
		367	{
228	int len = (data [0] << 8) | data [1];	368	len = (data [0] << 8) | data [1];
229		369
230	if (len > MAXSIZE && fill >= 2)	370	if (len <= MAXSIZE || fill < 2)
231	abort (); // TODO handle this gracefully, connection reset	371	break;
232		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
233	if (fill < len + 2)	378	if (fill < len + 2)
234	return 0;	379	return 0;
235		380
236	vpn_packet *pkt = new vpn_packet;	381	vpn_packet *pkt = new vpn_packet;
237		382
238	pkt->len = len;	383	pkt->len = len;
239	memcpy (&((*pkt)[0]), data + 2, len);	384	memcpy (pkt->at (0), data + 2, len);
240	remove (len + 2);	385	remove (len + 2);
241		386
242	return pkt;	387	return pkt;
243	}	388	}
244		389
245	/////////////////////////////////////////////////////////////////////////////	390	/////////////////////////////////////////////////////////////////////////////
246		391
247	#define FLAG_QUERY ( 0 << 15)	392	#define FLAG_QUERY ( 0 << 15)
248	#define FLAG_RESPONSE ( 1 << 15)	393	#define FLAG_RESPONSE ( 1 << 15)
249	#define FLAG_OP_MASK (15 << 14)	394	#define FLAG_OP_MASK (15 << 11)
250	#define FLAG_OP_QUERY ( 0 << 11)	395	#define FLAG_OP_QUERY ( 0 << 11)
251	#define FLAG_AA ( 1 << 10)	396	#define FLAG_AA ( 1 << 10)
252	#define FLAG_TC ( 1 << 9)	397	#define FLAG_TC ( 1 << 9)
253	#define FLAG_RD ( 1 << 8)	398	#define FLAG_RD ( 1 << 8)
254	#define FLAG_RA ( 1 << 7)	399	#define FLAG_RA ( 1 << 7)
…		…
261	#define FLAG_RCODE_REFUSED ( 5 << 0)	406	#define FLAG_RCODE_REFUSED ( 5 << 0)
262		407
263	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	408	#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)	409	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
265		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
266	struct dns_packet : net_packet	479	struct dns_packet : net_packet
267	{	480	{
268	u16 id;	481	u16 id;
269	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
270	u16 qdcount, ancount, nscount, arcount;	483	u16 qdcount, ancount, nscount, arcount;
271		484
272	u8 data[MAXSIZE - 6 * 2];	485	u8 data [MAXSIZE - 6 * 2];
273		486
274	int decode_label (char *data, int size, int &offs);	487	int decode_label (char *data, int size, int &offs);
275	};	488	};
276		489
277	int dns_packet::decode_label (char *data, int size, int &offs)	490	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
308	return data - orig;	521	return data - orig;
309	}	522	}
310		523
311	/////////////////////////////////////////////////////////////////////////////	524	/////////////////////////////////////////////////////////////////////////////
312		525
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	526	static u16 dns_id = 0; // TODO: should be per-vpn
326		527
327	static u16 next_id ()	528	static u16 next_id ()
328	{	529	{
		530	if (!dns_id)
		531	dns_id = time (0);
		532
329	// the simplest lsfr with periodicity 65535 i could find	533	// the simplest lsfr with periodicity 65535 i could find
330	dns_id = (dns_id << 1)	534	dns_id = (dns_id << 1)
331	| (((dns_id >> 1)	535	| (((dns_id >> 1)
332	^ (dns_id >> 2)	536	^ (dns_id >> 2)
333	^ (dns_id >> 4)	537	^ (dns_id >> 4)
334	^ (dns_id >> 15)) & 1);	538	^ (dns_id >> 15)) & 1);
335		539
336	return dns_id;	540	return dns_id;
337	}	541	}
338		542
339	dns_req::dns_req (connection *c)	543	struct dns_rcv;
340	: conn (c)	544	struct dns_snd;
		545
		546	struct dns_connection
341	{	547	{
342	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	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;
343	retry = 0;	592	retry = 0;
		593	seqno = 0;
		594	sent = ev_now ();
		595	stdhdr = false;
344		596
345	pkt = new dns_packet;	597	pkt = new dns_packet;
346		598
347	pkt->id = next_id ();	599	pkt->id = next_id ();
348	}	600	}
349		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
350	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	630	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
351	{	631	{
		632	stdhdr = true;
352	this->seqno = seqno;	633	this->seqno = seqno;
		634
		635	timeout = ev_now () + INITIAL_TIMEOUT;
353		636
354	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	637	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
355	pkt->qdcount = htons (1);	638	pkt->qdcount = htons (1);
356		639
357	int offs = 6*2;	640	int offs = 6*2;
358	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	641	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,	642	// 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	643	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
361		644
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;	645	char enc[256], *encp = enc;
374		646	encode_header (enc, THISNODE->id, seqno);
375	memcpy (data + 3, stream->begin (), datalen);	647
376	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;
377	stream->remove (datalen);	654	stream.remove (datalen);
378		655
379	while (enclen)	656	while (enclen)
380	{	657	{
381	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	658	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
382		659
…		…
387	encp += lbllen;	664	encp += lbllen;
388		665
389	enclen -= lbllen;	666	enclen -= lbllen;
390	}	667	}
391		668
392	const char *suffix = THISNODE->domain;	669	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		670
414	(*pkt)[offs++] = 0;	671	(*pkt)[offs++] = 0;
415	(*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;
416	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	697	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
417		698
418	pkt->len = offs;	699	pkt->len = offs;
419	}	700	}
420		701
…		…
439	{	720	{
440	delete pkt;	721	delete pkt;
441	}	722	}
442		723
443	/////////////////////////////////////////////////////////////////////////////	724	/////////////////////////////////////////////////////////////////////////////
444		725
445	struct dns_cfg	726	dns_connection::dns_connection (connection *c)
		727	: c (c)
		728	, rcvdq (MAX_BACKLOG * 2)
		729	, snddq (MAX_BACKLOG)
		730	, tw (this, &dns_connection::time_cb)
446	{	731	{
447	u8 id1, id2, id3;	732	vpn = c->vpn;
448	u8 def_ttl;
449	u8 unused1;
450	u16 max_size;
451	u8 flags1, flags2;
452	};
453		733
		734	established = false;
		735
		736	rcvseq = repseq = sndseq = 0;
		737
		738	last_sent = last_received = 0;
		739	poll_interval = 0.5; // starting here
		740	send_interval = 0.5; // starting rate
		741	min_latency = INITIAL_TIMEOUT;
		742	}
		743
		744	dns_connection::~dns_connection ()
		745	{
		746	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		747	i != rcvpq.end ();
		748	++i)
		749	delete *i;
		750	}
		751
454	void connection::dnsv4_receive_rep (struct dns_rcv *r)	752	void dns_connection::receive_rep (dns_rcv *r)
455	{	753	{
		754	if (r->datalen)
		755	{
		756	last_received = ev_now ();
		757	tw ();
		758
		759	poll_interval = send_interval;
		760	}
		761	else
		762	{
		763	poll_interval *= 1.5;
		764
		765	if (poll_interval > MAX_POLL_INTERVAL)
		766	poll_interval = MAX_POLL_INTERVAL;
		767	}
		768
456	dns_rcvpq.push_back (r);	769	rcvpq.push_back (r);
457		770
458	redo:	771	redo:
459		772
		773	// find next packet
460	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	774	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
461	i != dns_rcvpq.end ();
462	++i)
463	if (dns_rcvseq == (*i)->seqno)	775	if (SEQNO_EQ (rcvseq, (*i)->seqno))
464	{	776	{
		777	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		778	// enter the packet into our input stream
465	dns_rcv *r = *i;	779	r = *i;
466		780
		781	// remove the oldest packet, look forward, as it's oldest first
		782	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		783	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		784	{
		785	//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
		786	delete *j;
		787	rcvpq.erase (j);
		788	break;
		789	}
		790
467	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	791	rcvseq = (rcvseq + 1) & SEQNO_MASK;
468		792
469	if (!dns_snddq && !dns_rcvdq)	793	if (!rcvdq.put (r->data, r->datalen))
470	{	794	{
471	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	795	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
472	dns_snddq = new byte_stream (MAX_BACKLOG);	796	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	}	797	}
476		798
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 ())	799	while (vpn_packet *pkt = rcvdq.get ())
481	{	800	{
482	sockinfo si;	801	sockinfo si;
483	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	802	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
484		803
485	vpn->recv_vpn_packet (pkt, si);	804	vpn->recv_vpn_packet (pkt, si);
		805
		806	delete pkt;
486	}	807	}
487	}	808
488	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	809	// 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;	810	goto redo;
495	}	811	}
496	}	812	}
497		813
498	dns_packet *	814	void
499	vpn::dnsv4_server (dns_packet *pkt)	815	vpn::dnsv4_server (dns_packet &pkt)
500	{	816	{
501	u16 flags = ntohs (pkt->flags);	817	u16 flags = ntohs (pkt.flags);
502		818
503	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
504	int offs = 6 * 2; // skip header	819	int offs = 6 * 2; // skip header
505		820
506	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	821	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
507		822
508	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	823	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
509	&& pkt->qdcount == htons (1))	824	&& pkt.qdcount == htons (1))
510	{	825	{
511	char qname[MAXSIZE];	826	char qname [MAXSIZE];
512	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	827	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
513		828
514	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	829	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
515	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	830	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
516		831
517	pkt->qdcount = htons (1);	832	pkt.qdcount = htons (1);
518	pkt->ancount = 0;	833	pkt.ancount = 0;
519	pkt->nscount = 0; // should be self, as other nameservers reply like this	834	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	835	pkt.arcount = 0; // a record for self, as other nameservers reply like this
521		836
522	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	837	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
523		838
524	int dlen = strlen (THISNODE->domain);	839	int dlen = strlen (THISNODE->domain);
525		840
526	if (qclass == RR_CLASS_IN	841	if (qclass == RR_CLASS_IN
527	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
528	&& qlen > dlen + 1	842	&& qlen > dlen + 1
529	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	843	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
530	{	844	{
531	// correct class, domain: parse	845	// now generate reply
532	u8 data[MAXSIZE];	846	pkt.ancount = htons (1); // one answer RR
533	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	847	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
534		848
535	int client = data[0];	849	if ((qtype == RR_TYPE_ANY
536	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	850	|| qtype == RR_TYPE_TXT
537		851	|| qtype == RR_TYPE_NULL)
538	if (0 < client && client <= conns.size ())	852	&& qlen > dlen + 1 + HDRSIZE)
539	{	853	{
		854	// correct class, domain: parse
		855	int client, seqno;
		856	decode_header (qname, client, seqno);
		857
		858	u8 data[MAXSIZE];
		859	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		860
		861	if (0 < client && client <= conns.size ())
		862	{
540	connection *c = conns [client - 1];	863	connection *c = conns [client - 1];
		864	dns_connection *dns = c->dns;
		865	dns_rcv *rcv;
541		866
542	redo:	867	if (dns)
543
544	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
545	i != c->dns_rcvpq.end ();
546	++i)	868	{
		869	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
547	if ((*i)->seqno == seqno)	870	if (SEQNO_EQ ((*i)->seqno, seqno))
		871	{
		872	// already seen that request: simply reply with the cached reply
		873	dns_rcv *r = *i;
		874
		875	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		876
		877	// refresh header & id, as the retry count could have changed
		878	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		879	r->pkt->id = pkt.id;
		880
		881	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		882
		883	goto duplicate_request;
		884	}
		885
		886	// new packet, queue
		887	rcv = new dns_rcv (seqno, data, datalen);
		888	dns->receive_rep (rcv);
		889	}
		890
548	{	891	{
549	// already seen that request: simply reply with the cached reply	892	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
550	dns_rcv *r = *i;
551		893
552	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	894	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		895	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		896	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		897	pkt [offs++] = 0; pkt [offs++] = 0;
		898	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
553		899
		900	int rdlen_offs = offs += 2;
		901
		902	if (dns)
		903	{
		904	int dlen = ntohs (dns->cfg.max_size) - offs;
		905
		906	// bind doesn't compress well, so reduce further by one label length
		907	dlen -= qlen;
		908
		909	// only put data into in-order sequence packets, if
		910	// we receive out-of-order packets we generate empty
		911	// replies
		912	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		913	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		914	{
		915	dns->repseq = seqno;
		916
		917	while (dlen > 1 && !dns->snddq.empty ())
		918	{
		919	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		920
		921	if (txtlen > dns->snddq.size ())
		922	txtlen = dns->snddq.size ();
		923
		924	pkt[offs++] = txtlen;
		925	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		926	offs += txtlen;
		927	dns->snddq.remove (txtlen);
		928
		929	dlen -= txtlen + 1;
		930	}
		931	}
		932
		933	// avoid completely empty TXT rdata
		934	if (offs == rdlen_offs)
		935	pkt[offs++] = 0;
		936
		937	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		938	}
		939	else
		940	{
		941	// send RST
		942	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		943	pkt [offs++] = CMD_IP_RST;
		944	}
		945
		946	int rdlen = offs - rdlen_offs;
		947
		948	pkt [rdlen_offs - 2] = rdlen >> 8;
		949	pkt [rdlen_offs - 1] = rdlen;
		950
		951	if (dns)
		952	{
		953	// now update dns_rcv copy
554	offs = r->pkt->len;	954	rcv->pkt->len = offs;
555	memcpy (pkt->at (0), r->pkt->at (0), offs);	955	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
556	goto duplicate_request;	956	}
557	}	957	}
558		958
559	// new packet, queue	959	duplicate_request: ;
560	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	960	}
561	c->dnsv4_receive_rep (rcv);	961	else
562
563	// now generate reply
564	pkt->ancount = htons (1); // one answer RR
565	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	962	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		963	}
		964	else if (qtype == RR_TYPE_A
		965	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		966	{
		967	dns_cfg cfg;
		968	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		969	int client = ntohs (cfg.client);
566		970
567	(*pkt) [offs++] = 0xc0;
568	(*pkt) [offs++] = 6 * 2; // same as in query section	971	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
569		972
570	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	973	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
571	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	974	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
572
573	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	975	pkt [offs++] = 0; pkt [offs++] = 0;
574	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	976	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		977	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
575		978
576	int dlen = MAX_PKT_SIZE - offs - 2;	979	slog (L_INFO, _("DNS: client %d connects"), client);
577		980
578	// bind doesn't compress well, so reduce further by one label length	981	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
579	dlen -= qlen;	982	pkt [offs++] = CMD_IP_REJ;
580		983
581	int rdlen_offs = offs += 2;	984	if (0 < client && client <= conns.size ())
582
583	while (c->dns_snddq
584	&& !c->dns_snddq->empty ()
585	&& dlen > 1)
586	{	985	{
587	int txtlen = dlen <= 255 ? dlen - 1 : 255;	986	connection *c = conns [client - 1];
588		987
589	if (txtlen > c->dns_snddq->size ())	988	if (cfg.valid ())
590	txtlen = c->dns_snddq->size ();	989	{
		990	pkt [offs - 1] = CMD_IP_SYN;
591		991
592	(*pkt)[offs++] = txtlen;	992	delete c->dns;
593	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	993	c->dns = new dns_connection (c);
594	offs += txtlen;	994	c->dns->cfg = cfg;
595	c->dns_snddq->remove (txtlen);	995	}
596
597	dlen -= txtlen + 1;
598	}	996	}
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	}	997	}
615	else
616	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
617	}	998	}
618		999
619	pkt->len = offs;	1000	pkt.len = offs;
620	}	1001	}
621
622	return pkt;
623	}	1002	}
624		1003
625	void	1004	void
626	vpn::dnsv4_client (dns_packet *pkt)	1005	vpn::dnsv4_client (dns_packet &pkt)
627	{	1006	{
628	u16 flags = ntohs (pkt->flags);	1007	u16 flags = ntohs (pkt.flags);
629	int offs = 6 * 2; // skip header	1008	int offs = 6 * 2; // skip header
630		1009
631	pkt->qdcount = ntohs (pkt->qdcount);	1010	pkt.qdcount = ntohs (pkt.qdcount);
632	pkt->ancount = ntohs (pkt->ancount);	1011	pkt.ancount = ntohs (pkt.ancount);
633		1012
634	// go through our request list and find the corresponding request	1013	// go through our request list and find the corresponding request
635	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1014	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
636	i != dns_sndpq.end ();	1015	i != dns_sndpq.end ();
637	++i)	1016	++i)
638	if ((*i)->pkt->id == pkt->id)	1017	if ((*i)->pkt->id == pkt.id)
639	{	1018	{
		1019	dns_connection *dns = (*i)->dns;
640	connection *c = (*i)->conn;	1020	connection *c = dns->c;
641	int seqno = (*i)->seqno;	1021	int seqno = (*i)->seqno;
642	u8 data[MAXSIZE], *datap = data;	1022	u8 data[MAXSIZE], *datap = data;
		1023	//printf ("rcv pkt %x\n", seqno);//D
		1024
		1025	if ((*i)->retry)
		1026	{
		1027	dns->send_interval *= 1.01;
		1028	if (dns->send_interval > MAX_SEND_INTERVAL)
		1029	dns->send_interval = MAX_SEND_INTERVAL;
		1030	}
		1031	else
		1032	{
		1033	#if 0
		1034	dns->send_interval *= 0.999;
		1035	#endif
		1036	// the latency surely puts an upper bound on
		1037	// the minimum send interval
		1038	double latency = ev_now () - (*i)->sent;
		1039
		1040	if (latency < dns->min_latency)
		1041	dns->min_latency = latency;
		1042
		1043	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1044	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1045
		1046	if (dns->send_interval < conf.dns_send_interval)
		1047	dns->send_interval = conf.dns_send_interval;
		1048	}
643		1049
644	delete *i;	1050	delete *i;
645	dns_sndpq.erase (i);	1051	dns_sndpq.erase (i);
646		1052
647	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1053	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
648	{	1054	{
649	char qname[MAXSIZE];	1055	char qname[MAXSIZE];
650		1056
651	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1057	while (pkt.qdcount-- && offs < MAXSIZE - 4)
652	{	1058	{
653	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1059	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
654	offs += 4; // skip qtype, qclass	1060	offs += 4; // skip qtype, qclass
655	}	1061	}
656		1062
657	while (pkt->ancount-- && offs < MAXSIZE - 10)	1063	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
658	{	1064	{
659	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1065	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
660		1066
661	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1067	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
662	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1068	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
663	u32 ttl = (*pkt) [offs++] << 24;	1069	u32 ttl = pkt [offs++] << 24;
664	ttl |= (*pkt) [offs++] << 16;	1070	ttl |= pkt [offs++] << 16;
665	ttl |= (*pkt) [offs++] << 8;	1071	ttl |= pkt [offs++] << 8;
666	ttl |= (*pkt) [offs++];	1072	ttl |= pkt [offs++];
667
668	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1073	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
669		1074
670	if (rdlen <= MAXSIZE - offs)	1075	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
671	{	1076	{
672	// decode bytes, finally	1077	if (rdlen <= MAXSIZE - offs)
673
674	while (rdlen)
675	{	1078	{
		1079	// decode bytes, finally
		1080
		1081	while (rdlen)
		1082	{
676	int txtlen = (*pkt) [offs++];	1083	int txtlen = pkt [offs++];
677		1084
678	assert (txtlen + offs < MAXSIZE - 1);	1085	assert (txtlen + offs < MAXSIZE - 1);
679		1086
680	memcpy (datap, pkt->at (offs), txtlen);	1087	memcpy (datap, pkt.at (offs), txtlen);
681	datap += txtlen; offs += txtlen;	1088	datap += txtlen; offs += txtlen;
682		1089
683	rdlen -= txtlen + 1;	1090	rdlen -= txtlen + 1;
		1091	}
684	}	1092	}
685
686	}	1093	}
		1094	else if (qtype == RR_TYPE_A)
		1095	{
		1096	u8 ip [4];
687		1097
		1098	ip [0] = pkt [offs++];
		1099	ip [1] = pkt [offs++];
		1100	ip [2] = pkt [offs++];
		1101	ip [3] = pkt [offs++];
		1102
		1103	if (ip [0] == CMD_IP_1
		1104	&& ip [1] == CMD_IP_2
		1105	&& ip [2] == CMD_IP_3)
		1106	{
		1107	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1108
		1109	if (ip [3] == CMD_IP_RST)
		1110	{
		1111	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1112
		1113	delete dns; c->dns = 0;
		1114
		1115	return;
		1116	}
		1117	else if (ip [3] == CMD_IP_SYN)
		1118	{
		1119	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1120	dns->established = true;
		1121	}
		1122	else if (ip [3] == CMD_IP_REJ)
		1123	{
		1124	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1125	abort ();
		1126	}
		1127	else
		1128	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1129	}
		1130	else
		1131	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1132	ip [0], ip [1], ip [2], ip [3]);
		1133
		1134	return;
		1135	}
		1136
		1137	int client, rseqno;
		1138	decode_header (qname, client, rseqno);
		1139
		1140	if (client != THISNODE->id)
		1141	{
		1142	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1143	datap = 0;
		1144	}
		1145	else if (rseqno != seqno)
		1146	{
		1147	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1148	datap = 0;
		1149	}
688	}	1150	}
689	}	1151	}
690		1152
691	// todo: pkt now used	1153	// todo: pkt now used
		1154	if (datap)
692	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1155	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
693		1156
694	break;	1157	break;
695	}	1158	}
696
697	delete pkt;
698	}	1159	}
699		1160
700	void	1161	void
701	vpn::dnsv4_ev (io_watcher &w, short revents)	1162	vpn::dnsv4_ev (ev::io &w, int revents)
702	{	1163	{
703	if (revents & EVENT_READ)	1164	if (revents & EV_READ)
704	{	1165	{
705	dns_packet *pkt = new dns_packet;	1166	dns_packet *pkt = new dns_packet;
706	struct sockaddr_in sa;	1167	struct sockaddr_in sa;
707	socklen_t sa_len = sizeof (sa);	1168	socklen_t sa_len = sizeof (sa);
708		1169
709	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1170	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
710		1171
711	if (pkt->len > 0)	1172	if (pkt->len > 0)
712	{	1173	{
713	if (pkt->flags & htons (FLAG_TC))	1174	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1175	dnsv4_client (*pkt);
		1176	else
714	{	1177	{
715	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1178	dnsv4_server (*pkt);
716	//TODO connection reset	1179	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
717	}	1180	}
718		1181
719	if (THISNODE->dns_port)	1182	delete pkt;
720	{
721	pkt = dnsv4_server (pkt);
722	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
723	}
724	else
725	dnsv4_client (pkt);
726	}	1183	}
727	}	1184	}
728	}	1185	}
729		1186
730	bool	1187	bool
731	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1188	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
732	{	1189	{
733	// never initialized	1190	int client = ntohl (si.host);
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		1191
739	//dns_rcvseq = dns_sndseq = 0;	1192	assert (0 < client && client <= conns.size ());
740		1193
741	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1194	connection *c = conns [client - 1];
742	}	1195
		1196	if (!c->dns)
		1197	c->dns = new dns_connection (c);
743		1198
744	if (!dns_snddq->put (pkt))	1199	if (c->dns->snddq.put (pkt))
745	return false;	1200	c->dns->tw ();
746		1201
747	// start timer if neccessary	1202	// always return true even if the buffer overflows
748	if (!THISNODE->dns_port && !dnsv4_tw.active)
749	dnsv4_cb (dnsv4_tw);
750
751	return true;	1203	return true;
752	}	1204	}
753		1205
754	void	1206	void
755	connection::dnsv4_cb (time_watcher &w)	1207	connection::dnsv4_reset_connection ()
756	{	1208	{
		1209	//delete dns; dns = 0; //TODO
		1210	}
		1211
		1212	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1213
		1214	void
		1215	dns_connection::time_cb (ev::timer &w, int revents)
		1216	{
		1217	// servers have to be polled
		1218	if (THISNODE->dns_port)
		1219	return;
		1220
757	// check for timeouts and (re)transmit	1221	// check for timeouts and (re)transmit
758	tstamp next = NOW + 60;	1222	tstamp next = ev::now () + poll_interval;
759	dns_req *send = 0;	1223	dns_snd *send = 0;
760		1224
761	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1225	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
762	i != vpn->dns_sndpq.end ();	1226	i != vpn->dns_sndpq.end ();
763	++i)	1227	++i)
764	{	1228	{
765	dns_req *r = *i;	1229	dns_snd *r = *i;
766		1230
767	if (r->next <= NOW)	1231	if (r->timeout <= ev_now ())
768	{	1232	{
769	if (!send)	1233	if (!send)
770	{	1234	{
771	send = r;	1235	send = r;
772		1236
773	if (r->retry)//D
774	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
775	r->retry++;	1237	r->retry++;
776	r->next = NOW + r->retry;	1238	r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
		1239	//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D
		1240
		1241	// the following code changes the query section a bit, forcing
		1242	// the forwarder to generate a new request
		1243	if (r->stdhdr)
		1244	encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
777	}	1245	}
778	}	1246	}
779		1247	else
780	if (r->next < next)	1248	NEXT (r->timeout);
781	next = r->next;
782	}	1249	}
783		1250
784	if (!send	1251	if (!send)
785	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
786	{	1252	{
		1253	// generate a new packet, if wise
		1254
		1255	if (!established)
		1256	{
		1257	if (vpn->dns_sndpq.empty ())
		1258	{
787	send = new dns_req (this);	1259	send = new dns_snd (this);
		1260
		1261	cfg.reset (THISNODE->id);
		1262	send->gen_syn_req ();
		1263	}
		1264	}
		1265	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1266	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1267	{
		1268	if (last_sent + send_interval <= ev_now ())
		1269	{
		1270	//printf ("sending data request etc.\n"); //D
		1271	if (!snddq.empty () || last_received + 1. > ev_now ())
		1272	{
		1273	poll_interval = send_interval;
		1274	NEXT (ev_now () + send_interval);
		1275	}
		1276
		1277	send = new dns_snd (this);
788	send->gen_stream_req (dns_sndseq, dns_snddq);	1278	send->gen_stream_req (sndseq, snddq);
		1279	send->timeout = ev_now () + min_latency * conf.dns_timeout_factor;
		1280	//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D
		1281
		1282	sndseq = (sndseq + 1) & SEQNO_MASK;
		1283	}
		1284	else
		1285	NEXT (last_sent + send_interval);
		1286	}
		1287
		1288	if (send)
789	vpn->dns_sndpq.push_back (send);	1289	vpn->dns_sndpq.push_back (send);
790
791	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
792	}	1290	}
793
794	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
795		1291
796	if (send)	1292	if (send)
797	{	1293	{
798	dns_packet *pkt = send->pkt;	1294	last_sent = ev_now ();
799		1295	sendto (vpn->dnsv4_fd,
800	next = min_next;	1296	send->pkt->at (0), send->pkt->len, 0,
801		1297	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
802	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
803	}	1298	}
804	else if (next < min_next)
805	next = min_next;
806		1299
807	w.start (next);	1300	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1301	poll_interval, send_interval, next - ev_now (),
		1302	vpn->dns_sndpq.size (), snddq.size (),
		1303	rcvpq.size ());
		1304
		1305	// TODO: no idea when this happens, but when next < ev_now (), we have a problem
		1306	// doesn't seem to happen anymore
		1307	if (next < ev_now () + 0.001)
		1308	next = ev_now () + 0.1;
		1309
		1310	w.start (next - ev_now ());
808	}	1311	}
809		1312
810	#endif	1313	#endif
811		1314

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