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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 1.42 by pcg, Sat Nov 10 05:14:22 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 <gmp.h>
		48
40	#include "netcompat.h"	49	#include "netcompat.h"
41		50
42	#include "vpn.h"	51	#include "vpn.h"
43		52
44	#define MIN_RETRY 1.	53	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
45	#define MAX_RETRY 60.	54	#define ACTIVITY_INTERVAL 5.
46		55
47	#define MAX_OUTSTANDING 40 // max. outstanding requests	56	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		57	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
		58
		59	#define MAX_SEND_INTERVAL 2. // optimistic?
		60
48	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	61	#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	62	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
51		63
52	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	64	#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	65	// 240 leaves about 4 bytes of server reply data
54	// every two request byte sless give room for one reply byte	66	// every request byte less give room for two reply bytes
55		67
56	#define SEQNO_MASK 0xffff	68	#define SEQNO_MASK 0x3fff
57		69	#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		70
74	#define MAX_LBL_SIZE 63	71	#define MAX_LBL_SIZE 63
75	#define MAX_PKT_SIZE 512	72	#define MAX_PKT_SIZE 512
76		73
		74	#define RR_TYPE_A 1
		75	#define RR_TYPE_NULL 10
77	#define RR_TYPE_TXT 16	76	#define RR_TYPE_TXT 16
78	#define RR_TYPE_ANY 255	77	#define RR_TYPE_ANY 255
		78
79	#define RR_CLASS_IN 1	79	#define RR_CLASS_IN 1
80		80
81	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	81	#define CMD_IP_1 207
82	struct dns64	82	#define CMD_IP_2 46
83	{	83	#define CMD_IP_3 236
84	static const char encode_chars[64 + 1];	84	#define CMD_IP_RST 29
85	static s8 decode_chars[256];	85	#define CMD_IP_SYN 113
		86	#define CMD_IP_REJ 32
86		87
87	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	88	// works for cmaps up to 255 (not 256!)
88	static int decode_len (int bytes) { return (bytes * 6) / 8; }	89	struct charmap
		90	{
		91	enum { INVALID = (u8)255 };
		92
		93	char encode [256]; // index => char
		94	u8 decode [256]; // char => index
		95	unsigned int size;
		96
		97	charmap (const char *cmap);
		98	};
		99
		100	charmap::charmap (const char *cmap)
		101	{
		102	char *enc = encode;
		103	u8 *dec = decode;
		104
		105	memset (enc, (char) 0, 256);
		106	memset (dec, (char)INVALID, 256);
		107
		108	for (size = 0; cmap [size]; size++)
		109	{
		110	enc [size] = cmap [size];
		111	dec [(u8)enc [size]] = size;
		112	}
		113
		114	assert (size < 256);
		115	}
		116
		117	#define MAX_DEC_LEN 500
		118	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		119	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		120
		121	// ugly. minimum base is 16(!)
		122	struct basecoder
		123	{
		124	charmap cmap;
		125	unsigned int enc_len [MAX_DEC_LEN];
		126	unsigned int dec_len [MAX_ENC_LEN];
		127
		128	unsigned int encode_len (unsigned int len);
		129	unsigned int decode_len (unsigned int len);
		130
89	static int encode (char *dst, u8 *src, int len);	131	unsigned int encode (char *dst, u8 *src, unsigned int len);
90	static int decode (u8 *dst, char *src, int len);	132	unsigned int decode (u8 *dst, char *src, unsigned int len);
91		133
92	dns64 ();	134	basecoder (const char *cmap);
93	} dns64;	135	};
94		136
95	const char dns64::encode_chars[64 + 1] = "_4B9dLphHzrqQmGjkTbJt5svlZX8xSaReEYfwKgF1DP2W6NyVOU70IouACcMn3i-";	137	basecoder::basecoder (const char *cmap)
96	s8 dns64::decode_chars[256];	138	: cmap (cmap)
97
98	dns64::dns64 ()
99	{	139	{
100	for (int i = 0; i < 64; i++)	140	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
101	decode_chars [encode_chars [i]] = i + 1;	141	{
102	}	142	u8 src [MAX_DEC_LEN];
		143	u8 dst [MAX_ENC_LEN];
103		144
104	int dns64::encode (char *dst, u8 *src, int len)	145	memset (src, 255, len);
		146
		147	mp_limb_t m [MAX_LIMBS];
		148	mp_size_t n;
		149
		150	n = mpn_set_str (m, src, len, 256);
		151	n = mpn_get_str (dst, this->cmap.size, m, n);
		152
		153	for (int i = 0; !dst [i]; ++i)
		154	n--;
		155
		156	enc_len [len] = n;
		157	dec_len [n] = len;
		158	}
		159	}
		160
		161	unsigned int basecoder::encode_len (unsigned int len)
105	{	162	{
106	// slow, but easy to debug	163	return enc_len [len];
107	char *beg = dst;	164	}
108	unsigned int accum, bits = 0;	165
		166	unsigned int basecoder::decode_len (unsigned int len)
		167	{
		168	while (len && !dec_len [len])
		169	--len;
		170
		171	return dec_len [len];
		172	}
		173
		174	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		175	{
		176	if (!len || len > MAX_DEC_LEN)
		177	return 0;
		178
		179	int elen = encode_len (len);
		180
		181	mp_limb_t m [MAX_LIMBS];
		182	mp_size_t n;
		183
		184	u8 dst_ [MAX_ENC_LEN];
		185
		186	n = mpn_set_str (m, src, len, 256);
		187	n = mpn_get_str (dst_, cmap.size, m, n);
		188
		189	int plen = elen; // for padding
		190
		191	while (n < plen)
		192	{
		193	*dst++ = cmap.encode [0];
		194	plen--;
		195	}
		196
		197	for (unsigned int i = n - plen; i < n; ++i)
		198	*dst++ = cmap.encode [dst_ [i]];
		199
		200	return elen;
		201	}
		202
		203	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		204	{
		205	if (!len || len > MAX_ENC_LEN)
		206	return 0;
		207
		208	u8 src_ [MAX_ENC_LEN];
		209	unsigned int elen = 0;
109		210
110	while (len--)	211	while (len--)
111	{	212	{
112	accum <<= 8;	213	u8 val = cmap.decode [(u8)*src++];
113	accum |= *src++;
114	bits += 8;
115		214
116	while (bits >= 6)	215	if (val != charmap::INVALID)
117	{	216	src_ [elen++] = val;
118	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	217	}
119	bits -= 6;	218
120	}	219	int dlen = decode_len (elen);
		220
		221	mp_limb_t m [MAX_LIMBS];
		222	mp_size_t n;
		223
		224	u8 dst_ [MAX_DEC_LEN];
		225
		226	n = mpn_set_str (m, src_, elen, cmap.size);
		227	n = mpn_get_str (dst_, 256, m, n);
		228
		229	if (n < dlen)
121	}	230	{
		231	memset (dst, 0, dlen - n);
		232	memcpy (dst + dlen - n, dst_, n);
		233	}
		234	else
		235	memcpy (dst, dst_ + n - dlen, dlen);
122		236
123	if (bits)	237	return dlen;
124	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
125
126	return dst - beg;
127	}	238	}
128		239
129	int dns64::decode (u8 *dst, char *src, int len)	240	#if 0
130	{	241	struct test { test (); } test;
131	// slow, but easy to debug
132	u8 *beg = dst;
133	unsigned int accum, bits = 0;
134		242
135	while (len--)	243	test::test ()
		244	{
		245	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		246
		247	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		248	static char enc[200];
		249	static u8 dec[200];
		250
		251	for (int i = 1; i < 20; i++)
136	{	252	{
137	s8 chr = decode_chars [(u8)*src++];	253	int elen = cdc.encode (enc, in, i);
		254	int dlen = cdc.decode (dec, enc, elen);
138		255
139	if (!chr)	256	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	}	257	}
		258	abort ();
		259	}
		260	#endif
152		261
153	return dst - beg;	262	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		263	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		264	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		265	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		266	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		267
		268	/////////////////////////////////////////////////////////////////////////////
		269
		270	#define HDRSIZE 6
		271
		272	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		273	{
		274	seqno &= SEQNO_MASK;
		275
		276	u8 hdr[3] = {
		277	clientid,
		278	(seqno >> 8) | (retry << 6),
		279	seqno,
		280	};
		281
		282	assert (clientid < 256);
		283
		284	cdc26.encode (data, hdr, 3);
		285	}
		286
		287	inline void decode_header (char *data, int &clientid, int &seqno)
		288	{
		289	u8 hdr[3];
		290
		291	cdc26.decode (hdr, data, HDRSIZE);
		292
		293	clientid = hdr[0];
		294	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
154	}	295	}
155		296
156	/////////////////////////////////////////////////////////////////////////////	297	/////////////////////////////////////////////////////////////////////////////
157		298
158	struct byte_stream	299	struct byte_stream
…		…
187	}	328	}
188		329
189	void byte_stream::remove (int count)	330	void byte_stream::remove (int count)
190	{	331	{
191	if (count > fill)	332	if (count > fill)
192	abort ();	333	assert (count <= fill);
193		334
194	memmove (data, data + count, fill -= count);	335	memmove (data, data + count, fill -= count);
195	}	336	}
196		337
197	bool byte_stream::put (u8 *data, unsigned int datalen)	338	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
210	return false;	351	return false;
211		352
212	data [fill++] = pkt->len >> 8;	353	data [fill++] = pkt->len >> 8;
213	data [fill++] = pkt->len;	354	data [fill++] = pkt->len;
214		355
215	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	356	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
216		357
217	return true;	358	return true;
218	}	359	}
219		360
220	vpn_packet *byte_stream::get ()	361	vpn_packet *byte_stream::get ()
221	{	362	{
		363	unsigned int len;
		364
		365	for (;;)
		366	{
222	int len = (data [0] << 8) | data [1];	367	len = (data [0] << 8) | data [1];
223		368
224	printf ("get len %d, fill %d\n", len, fill);//D
225
226	if (len > MAXSIZE && fill >= 2)	369	if (len <= MAXSIZE || fill < 2)
227	abort (); // TODO handle this gracefully, connection reset	370	break;
228		371
		372	// TODO: handle this better than skipping, e.g. by reset
		373	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		374	remove (1);
		375	}
		376
229	if (fill < len + 2)	377	if (fill < len + 2)
230	return 0;	378	return 0;
231		379
232	vpn_packet *pkt = new vpn_packet;	380	vpn_packet *pkt = new vpn_packet;
233		381
234	pkt->len = len;	382	pkt->len = len;
235	memcpy (&((*pkt)[0]), data + 2, len);	383	memcpy (pkt->at (0), data + 2, len);
236	remove (len + 2);	384	remove (len + 2);
237		385
238	return pkt;	386	return pkt;
239	}	387	}
240		388
241	/////////////////////////////////////////////////////////////////////////////	389	/////////////////////////////////////////////////////////////////////////////
242		390
243	#define FLAG_QUERY ( 0 << 15)	391	#define FLAG_QUERY ( 0 << 15)
244	#define FLAG_RESPONSE ( 1 << 15)	392	#define FLAG_RESPONSE ( 1 << 15)
245	#define FLAG_OP_MASK (15 << 14)	393	#define FLAG_OP_MASK (15 << 11)
246	#define FLAG_OP_QUERY ( 0 << 11)	394	#define FLAG_OP_QUERY ( 0 << 11)
247	#define FLAG_AA ( 1 << 10)	395	#define FLAG_AA ( 1 << 10)
248	#define FLAG_TC ( 1 << 9)	396	#define FLAG_TC ( 1 << 9)
249	#define FLAG_RD ( 1 << 8)	397	#define FLAG_RD ( 1 << 8)
250	#define FLAG_RA ( 1 << 7)	398	#define FLAG_RA ( 1 << 7)
…		…
257	#define FLAG_RCODE_REFUSED ( 5 << 0)	405	#define FLAG_RCODE_REFUSED ( 5 << 0)
258		406
259	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	407	#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)	408	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
261		409
		410	struct dns_cfg
		411	{
		412	static int next_uid;
		413
		414	u8 id1, id2, id3, id4;
		415
		416	u8 version;
		417	u8 flags;
		418	u8 rrtype;
		419	u8 def_ttl;
		420
		421	u16 client;
		422	u16 uid; // to make request unique
		423
		424	u16 max_size;
		425	u8 seq_cdc;
		426	u8 req_cdc;
		427
		428	u8 rep_cdc;
		429	u8 delay; // time in 0.01s units that the server may delay replying packets
		430	u8 r3, r4;
		431
		432	u8 r5, r6, r7, r8;
		433
		434	void reset (int clientid);
		435	bool valid ();
		436	};
		437
		438	int dns_cfg::next_uid;
		439
		440	void dns_cfg::reset (int clientid)
		441	{
		442	id1 = 'G';
		443	id2 = 'V';
		444	id3 = 'P';
		445	id4 = 'E';
		446
		447	version = 1;
		448
		449	rrtype = RR_TYPE_TXT;
		450	flags = 0;
		451	def_ttl = 0;
		452	seq_cdc = 26;
		453	req_cdc = 62;
		454	rep_cdc = 0;
		455	max_size = htons (MAX_PKT_SIZE);
		456	client = htons (clientid);
		457	uid = next_uid++;
		458	delay = 0;
		459
		460	r3 = r4 = 0;
		461	r4 = r5 = r6 = r7 = 0;
		462	}
		463
		464	bool dns_cfg::valid ()
		465	{
		466	// although the protocol itself allows for some configurability,
		467	// only the following encoding/decoding settings are implemented.
		468	return id1 == 'G'
		469	&& id2 == 'V'
		470	&& id3 == 'P'
		471	&& id4 == 'E'
		472	&& seq_cdc == 26
		473	&& req_cdc == 62
		474	&& rep_cdc == 0
		475	&& version == 1;
		476	}
		477
262	struct dns_packet : net_packet	478	struct dns_packet : net_packet
263	{	479	{
264	u16 id;	480	u16 id;
265	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	481	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
266	u16 qdcount, ancount, nscount, arcount;	482	u16 qdcount, ancount, nscount, arcount;
267		483
268	u8 data[MAXSIZE - 6 * 2];	484	u8 data [MAXSIZE - 6 * 2];
269		485
270	int decode_label (char *data, int size, int &offs);	486	int decode_label (char *data, int size, int &offs);
271	};	487	};
272		488
273	int dns_packet::decode_label (char *data, int size, int &offs)	489	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
304	return data - orig;	520	return data - orig;
305	}	521	}
306		522
307	/////////////////////////////////////////////////////////////////////////////	523	/////////////////////////////////////////////////////////////////////////////
308		524
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	525	static u16 dns_id = 0; // TODO: should be per-vpn
322		526
323	static u16 next_id ()	527	static u16 next_id ()
324	{	528	{
		529	if (!dns_id)
		530	dns_id = time (0);
		531
325	// the simplest lsfr with periodicity 65535 i could find	532	// the simplest lsfr with periodicity 65535 i could find
326	dns_id = (dns_id << 1)	533	dns_id = (dns_id << 1)
327	| (((dns_id >> 1)	534	| (((dns_id >> 1)
328	^ (dns_id >> 2)	535	^ (dns_id >> 2)
329	^ (dns_id >> 4)	536	^ (dns_id >> 4)
330	^ (dns_id >> 15)) & 1);	537	^ (dns_id >> 15)) & 1);
331		538
332	return dns_id;	539	return dns_id;
333	}	540	}
334		541
335	dns_req::dns_req (connection *c)	542	struct dns_rcv;
336	: conn (c)	543	struct dns_snd;
		544
		545	struct dns_connection
337	{	546	{
338	next = 0;	547	connection *c;
		548	struct vpn *vpn;
		549
		550	dns_cfg cfg;
		551
		552	bool established;
		553
		554	tstamp last_received;
		555	tstamp last_sent;
		556	double min_latency;
		557	double poll_interval, send_interval;
		558
		559	vector<dns_rcv *> rcvpq;
		560
		561	byte_stream rcvdq; int rcvseq; int repseq;
		562	byte_stream snddq; int sndseq;
		563
		564	void time_cb (ev::timer &w, int revents); ev::timer tw;
		565	void receive_rep (dns_rcv *r);
		566
		567	dns_connection (connection *c);
		568	~dns_connection ();
		569	};
		570
		571	struct dns_snd
		572	{
		573	dns_packet *pkt;
		574	tstamp timeout, sent;
		575	int retry;
		576	struct dns_connection *dns;
		577	int seqno;
		578	bool stdhdr;
		579
		580	void gen_stream_req (int seqno, byte_stream &stream);
		581	void gen_syn_req ();
		582
		583	dns_snd (dns_connection *dns);
		584	~dns_snd ();
		585	};
		586
		587	dns_snd::dns_snd (dns_connection *dns)
		588	: dns (dns)
		589	{
		590	timeout = 0;
339	retry = 0;	591	retry = 0;
		592	seqno = 0;
		593	sent = ev::ev_now ();
		594	stdhdr = false;
340		595
341	pkt = new dns_packet;	596	pkt = new dns_packet;
342		597
343	pkt->id = next_id ();	598	pkt->id = next_id ();
344	}	599	}
345		600
		601	dns_snd::~dns_snd ()
		602	{
		603	delete pkt;
		604	}
		605
		606	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		607	{
		608	// add tunnel domain
		609	for (;;)
		610	{
		611	const char *end = strchr (domain, '.');
		612
		613	if (!end)
		614	end = domain + strlen (domain);
		615
		616	int len = end - domain;
		617
		618	pkt [offs++] = len;
		619	memcpy (pkt.at (offs), domain, len);
		620	offs += len;
		621
		622	if (!*end)
		623	break;
		624
		625	domain = end + 1;
		626	}
		627	}
		628
346	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	629	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
347	{	630	{
		631	stdhdr = true;
348	this->seqno = seqno;	632	this->seqno = seqno;
		633
		634	timeout = ev::ev_now () + INITIAL_TIMEOUT;
349		635
350	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	636	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
351	pkt->qdcount = htons (1);	637	pkt->qdcount = htons (1);
352		638
353	int offs = 6*2;	639	int offs = 6*2;
354	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	640	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,	641	// 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	642	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
357		643
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;	644	char enc[256], *encp = enc;
370		645	encode_header (enc, THISNODE->id, seqno);
371	memcpy (data + 3, stream->begin (), datalen);	646
372	int enclen = dns64::encode (enc, data, datalen + 3);	647	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		648
		649	if (datalen > stream.size ())
		650	datalen = stream.size ();
		651
		652	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
373	stream->remove (datalen);	653	stream.remove (datalen);
374		654
375	while (enclen)	655	while (enclen)
376	{	656	{
377	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	657	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
378		658
…		…
383	encp += lbllen;	663	encp += lbllen;
384		664
385	enclen -= lbllen;	665	enclen -= lbllen;
386	}	666	}
387		667
388	const char *suffix = THISNODE->domain;	668	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		669
410	(*pkt)[offs++] = 0;	670	(*pkt)[offs++] = 0;
411	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	671	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		672	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		673
		674	pkt->len = offs;
		675	}
		676
		677	void dns_snd::gen_syn_req ()
		678	{
		679	timeout = ev::ev_now () + INITIAL_SYN_TIMEOUT;
		680
		681	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		682	pkt->qdcount = htons (1);
		683
		684	int offs = 6 * 2;
		685
		686	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		687
		688	assert (elen <= MAX_LBL_SIZE);
		689
		690	(*pkt)[offs] = elen;
		691	offs += elen + 1;
		692	append_domain (*pkt, offs, dns->c->conf->domain);
		693
		694	(*pkt)[offs++] = 0;
		695	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
412	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	696	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
413		697
414	pkt->len = offs;	698	pkt->len = offs;
415	}	699	}
416		700
…		…
419	int seqno;	703	int seqno;
420	dns_packet *pkt; // reply packet	704	dns_packet *pkt; // reply packet
421	u8 data [MAXSIZE]; // actually part of the reply packet...	705	u8 data [MAXSIZE]; // actually part of the reply packet...
422	int datalen;	706	int datalen;
423		707
424	dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen);	708	dns_rcv (int seqno, u8 *data, int datalen);
425	~dns_rcv ();	709	~dns_rcv ();
426	};	710	};
427		711
428	dns_rcv::dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen)	712	dns_rcv::dns_rcv (int seqno, u8 *data, int datalen)
429	: seqno (seqno), pkt (new dns_packet), datalen (datalen)	713	: seqno (seqno), pkt (new dns_packet), datalen (datalen)
430	{	714	{
431	memcpy (this->data, data, datalen);	715	memcpy (this->data, data, datalen);
432	pkt->len = req->len;
433	memcpy (pkt->at (0), req->at (0), req->len);
434	}	716	}
435		717
436	dns_rcv::~dns_rcv ()	718	dns_rcv::~dns_rcv ()
437	{	719	{
438	delete pkt;	720	delete pkt;
439	}	721	}
440		722
441	/////////////////////////////////////////////////////////////////////////////	723	/////////////////////////////////////////////////////////////////////////////
442		724
443	struct dns_cfg	725	dns_connection::dns_connection (connection *c)
		726	: c (c)
		727	, rcvdq (MAX_BACKLOG * 2)
		728	, snddq (MAX_BACKLOG)
		729	, tw (this, &dns_connection::time_cb)
444	{	730	{
445	u8 id1, id2, id3;	731	vpn = c->vpn;
446	u8 def_ttl;
447	u8 unused1;
448	u16 max_size;
449	u8 flags1, flags2;
450	};
451		732
		733	established = false;
		734
		735	rcvseq = repseq = sndseq = 0;
		736
		737	last_sent = last_received = 0;
		738	poll_interval = 0.5; // starting here
		739	send_interval = 0.5; // starting rate
		740	min_latency = INITIAL_TIMEOUT;
		741	}
		742
		743	dns_connection::~dns_connection ()
		744	{
		745	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		746	i != rcvpq.end ();
		747	++i)
		748	delete *i;
		749	}
		750
452	void connection::dnsv4_receive_rep (struct dns_rcv *r)	751	void dns_connection::receive_rep (dns_rcv *r)
453	{	752	{
		753	if (r->datalen)
		754	{
		755	last_received = ev::ev_now ();
		756	tw ();
		757
		758	poll_interval = send_interval;
		759	}
		760	else
		761	{
		762	poll_interval *= 1.5;
		763
		764	if (poll_interval > MAX_POLL_INTERVAL)
		765	poll_interval = MAX_POLL_INTERVAL;
		766	}
		767
454	dns_rcvpq.push_back (r);	768	rcvpq.push_back (r);
455		769
456	redo:	770	redo:
457		771
		772	// find next packet
458	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	773	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
459	i != dns_rcvpq.end ();
460	++i)
461	if (dns_rcvseq == (*i)->seqno)	774	if (SEQNO_EQ (rcvseq, (*i)->seqno))
462	{	775	{
		776	//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
		777	// enter the packet into our input stream
463	dns_rcv *r = *i;	778	r = *i;
464		779
		780	// remove the oldest packet, look forward, as it's oldest first
		781	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		782	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		783	{
		784	//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
		785	delete *j;
		786	rcvpq.erase (j);
		787	break;
		788	}
		789
465	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	790	rcvseq = (rcvseq + 1) & SEQNO_MASK;
466		791
467	if (!dns_snddq && !dns_rcvdq)	792	if (!rcvdq.put (r->data, r->datalen))
468	{	793	{
469	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	794	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
470	dns_snddq = new byte_stream (MAX_BACKLOG);	795	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	}	796	}
474		797
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 ())	798	while (vpn_packet *pkt = rcvdq.get ())
479	{	799	{
480	sockinfo si;	800	sockinfo si;
481	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	801	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
482		802
483	vpn->recv_vpn_packet (pkt, si);	803	vpn->recv_vpn_packet (pkt, si);
		804
		805	delete pkt;
484	}	806	}
485	}	807
486	else if ((u32)dns_rcvseq - MAX_WINDOW - (u32)(*i)->seqno < MAX_WINDOW * 2)	808	// check for further packets
487	{
488	dns_rcvpq.erase (i);
489	goto redo;	809	goto redo;
490	}	810	}
491	}	811	}
492		812
493	dns_packet *	813	void
494	vpn::dnsv4_server (dns_packet *pkt)	814	vpn::dnsv4_server (dns_packet &pkt)
495	{	815	{
496	u16 flags = ntohs (pkt->flags);	816	u16 flags = ntohs (pkt.flags);
497		817
498	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
499	int offs = 6 * 2; // skip header	818	int offs = 6 * 2; // skip header
500		819
501	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	820	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
502		821
503	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	822	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
504	&& pkt->qdcount == htons (1))	823	&& pkt.qdcount == htons (1))
505	{	824	{
506	char qname[MAXSIZE];	825	char qname [MAXSIZE];
507	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	826	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
508		827
509	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	828	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
510	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	829	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
511		830
512	pkt->qdcount = htons (1);	831	pkt.qdcount = htons (1);
513	pkt->ancount = 0;	832	pkt.ancount = 0;
514	pkt->nscount = 0; // should be self, as other nameservers reply like this	833	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	834	pkt.arcount = 0; // a record for self, as other nameservers reply like this
516		835
517	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	836	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
518		837
519	int dlen = strlen (THISNODE->domain);	838	int dlen = strlen (THISNODE->domain);
520		839
521	if (qclass == RR_CLASS_IN	840	if (qclass == RR_CLASS_IN
522	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
523	&& qlen > dlen + 1	841	&& qlen > dlen + 1
524	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	842	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
525	{	843	{
526	// correct class, domain: parse	844	// now generate reply
527	u8 data[MAXSIZE];	845	pkt.ancount = htons (1); // one answer RR
528	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	846	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
529		847
530	int client = data[0];	848	if ((qtype == RR_TYPE_ANY
531	int seqno = ((data[1] << 8) | data[2]) & SEQNO_MASK;	849	|| qtype == RR_TYPE_TXT
532		850	|| qtype == RR_TYPE_NULL)
533	if (0 < client && client <= conns.size ())	851	&& qlen > dlen + 1 + HDRSIZE)
534	{	852	{
		853	// correct class, domain: parse
		854	int client, seqno;
		855	decode_header (qname, client, seqno);
		856
		857	u8 data[MAXSIZE];
		858	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		859
		860	if (0 < client && client <= conns.size ())
		861	{
535	connection *c = conns [client - 1];	862	connection *c = conns [client - 1];
		863	dns_connection *dns = c->dns;
		864	dns_rcv *rcv;
536		865
537	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();	866	if (dns)
538	i != c->dns_rcvpq.end ();
539	++i)	867	{
		868	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
540	if ((*i)->seqno == seqno)	869	if (SEQNO_EQ ((*i)->seqno, seqno))
		870	{
		871	// already seen that request: simply reply with the cached reply
		872	dns_rcv *r = *i;
		873
		874	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		875
		876	// refresh header & id, as the retry count could have changed
		877	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		878	r->pkt->id = pkt.id;
		879
		880	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		881
		882	goto duplicate_request;
		883	}
		884
		885	// new packet, queue
		886	rcv = new dns_rcv (seqno, data, datalen);
		887	dns->receive_rep (rcv);
		888	}
		889
541	{	890	{
542	// already seen that request, just reply with the original reply	891	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
543	dns_rcv *r = *i;
544		892
		893	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		894	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		895	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		896	pkt [offs++] = 0; pkt [offs++] = 0;
		897	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
		898
		899	int rdlen_offs = offs += 2;
		900
		901	if (dns)
		902	{
		903	int dlen = ntohs (dns->cfg.max_size) - offs;
		904
		905	// bind doesn't compress well, so reduce further by one label length
		906	dlen -= qlen;
		907
		908	// only put data into in-order sequence packets, if
		909	// we receive out-of-order packets we generate empty
		910	// replies
		911	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		912	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		913	{
		914	dns->repseq = seqno;
		915
		916	while (dlen > 1 && !dns->snddq.empty ())
		917	{
		918	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		919
		920	if (txtlen > dns->snddq.size ())
		921	txtlen = dns->snddq.size ();
		922
		923	pkt[offs++] = txtlen;
		924	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		925	offs += txtlen;
		926	dns->snddq.remove (txtlen);
		927
		928	dlen -= txtlen + 1;
		929	}
		930	}
		931
		932	// avoid completely empty TXT rdata
		933	if (offs == rdlen_offs)
		934	pkt[offs++] = 0;
		935
		936	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		937	}
		938	else
		939	{
		940	// send RST
		941	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		942	pkt [offs++] = CMD_IP_RST;
		943	}
		944
		945	int rdlen = offs - rdlen_offs;
		946
		947	pkt [rdlen_offs - 2] = rdlen >> 8;
		948	pkt [rdlen_offs - 1] = rdlen;
		949
		950	if (dns)
		951	{
		952	// now update dns_rcv copy
545	offs = r->pkt->len;	953	rcv->pkt->len = offs;
546	memcpy (pkt->at (0), r->pkt->at (0), offs);	954	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
547	goto duplicate_request;	955	}
548	}	956	}
549		957
550	// new packet, queue	958	duplicate_request: ;
551	c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data + 3, datalen - 3));	959	}
552		960	else
553	// now generate reply
554	pkt->ancount = htons (1); // one answer RR
555	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	961	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		962	}
		963	else if (qtype == RR_TYPE_A
		964	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		965	{
		966	dns_cfg cfg;
		967	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		968	int client = ntohs (cfg.client);
556		969
557	(*pkt) [offs++] = 0xc0;
558	(*pkt) [offs++] = 6 * 2; // same as in query section	970	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
559		971
560	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	972	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
561	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	973	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
562
563	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	974	pkt [offs++] = 0; pkt [offs++] = 0;
564	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	975	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		976	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
565		977
566	int dlen = MAX_PKT_SIZE - offs - 2;	978	slog (L_INFO, _("DNS: client %d connects"), client);
567		979
568	// bind doesn't compress well, so reduce further by one label length	980	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
569	dlen -= qlen;	981	pkt [offs++] = CMD_IP_REJ;
570		982
571	int rdlen_offs = offs += 2;	983	if (0 < client && client <= conns.size ())
572
573	while (c->dns_snddq
574	&& !c->dns_snddq->empty ()
575	&& dlen > 1)
576	{	984	{
577	int txtlen = dlen <= 255 ? dlen - 1 : 255;	985	connection *c = conns [client - 1];
578		986
579	if (txtlen > c->dns_snddq->size ())	987	if (cfg.valid ())
580	txtlen = c->dns_snddq->size ();	988	{
		989	pkt [offs - 1] = CMD_IP_SYN;
581		990
582	(*pkt)[offs++] = txtlen;	991	delete c->dns;
583	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	992	c->dns = new dns_connection (c);
584	offs += txtlen;	993	c->dns->cfg = cfg;
585	c->dns_snddq->remove (txtlen);	994	}
586
587	dlen -= txtlen + 1;
588	}	995	}
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	}	996	}
601	else
602	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
603	}	997	}
604	}
605	else
606	offs = pkt->len;
607		998
608	pkt->len = offs;	999	pkt.len = offs;
609	return pkt;	1000	}
610	}	1001	}
611		1002
612	void	1003	void
613	vpn::dnsv4_client (dns_packet *pkt)	1004	vpn::dnsv4_client (dns_packet &pkt)
614	{	1005	{
615	u16 flags = ntohs (pkt->flags);	1006	u16 flags = ntohs (pkt.flags);
616	int offs = 6 * 2; // skip header	1007	int offs = 6 * 2; // skip header
617		1008
618	pkt->qdcount = ntohs (pkt->qdcount);	1009	pkt.qdcount = ntohs (pkt.qdcount);
619	pkt->ancount = ntohs (pkt->ancount);	1010	pkt.ancount = ntohs (pkt.ancount);
620		1011
621	// go through our request list and find the corresponding request	1012	// go through our request list and find the corresponding request
622	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1013	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
623	i != dns_sndpq.end ();	1014	i != dns_sndpq.end ();
624	++i)	1015	++i)
625	if ((*i)->pkt->id == pkt->id)	1016	if ((*i)->pkt->id == pkt.id)
626	{	1017	{
		1018	dns_connection *dns = (*i)->dns;
627	connection *c = (*i)->conn;	1019	connection *c = dns->c;
628	int seqno = (*i)->seqno;	1020	int seqno = (*i)->seqno;
629	u8 data[MAXSIZE], *datap = data;	1021	u8 data[MAXSIZE], *datap = data;
		1022	//printf ("rcv pkt %x\n", seqno);//D
		1023
		1024	if ((*i)->retry)
		1025	{
		1026	dns->send_interval *= 1.01;
		1027	if (dns->send_interval > MAX_SEND_INTERVAL)
		1028	dns->send_interval = MAX_SEND_INTERVAL;
		1029	}
		1030	else
		1031	{
		1032	#if 0
		1033	dns->send_interval *= 0.999;
		1034	#endif
		1035	// the latency surely puts an upper bound on
		1036	// the minimum send interval
		1037	double latency = ev::ev_now () - (*i)->sent;
		1038
		1039	if (latency < dns->min_latency)
		1040	dns->min_latency = latency;
		1041
		1042	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1043	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1044
		1045	if (dns->send_interval < conf.dns_send_interval)
		1046	dns->send_interval = conf.dns_send_interval;
		1047	}
630		1048
631	delete *i;	1049	delete *i;
632	dns_sndpq.erase (i);	1050	dns_sndpq.erase (i);
633		1051
634	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1052	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
635	{	1053	{
636	char qname[MAXSIZE];	1054	char qname[MAXSIZE];
637		1055
638	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1056	while (pkt.qdcount-- && offs < MAXSIZE - 4)
639	{	1057	{
640	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1058	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
641	offs += 4; // skip qtype, qclass	1059	offs += 4; // skip qtype, qclass
642	}	1060	}
643		1061
644	while (pkt->ancount-- && offs < MAXSIZE - 10)	1062	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
645	{	1063	{
646	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1064	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
647		1065
648	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1066	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
649	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1067	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
650	u32 ttl = (*pkt) [offs++] << 24;	1068	u32 ttl = pkt [offs++] << 24;
651	ttl |= (*pkt) [offs++] << 16;	1069	ttl |= pkt [offs++] << 16;
652	ttl |= (*pkt) [offs++] << 8;	1070	ttl |= pkt [offs++] << 8;
653	ttl |= (*pkt) [offs++];	1071	ttl |= pkt [offs++];
654
655	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1072	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
656		1073
657	if (rdlen <= MAXSIZE - offs)	1074	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
658	{	1075	{
659	// decode bytes, finally	1076	if (rdlen <= MAXSIZE - offs)
660
661	while (rdlen)
662	{	1077	{
		1078	// decode bytes, finally
		1079
		1080	while (rdlen)
		1081	{
663	int txtlen = (*pkt) [offs++];	1082	int txtlen = pkt [offs++];
664		1083
665	assert (txtlen + offs < MAXSIZE - 1);	1084	assert (txtlen + offs < MAXSIZE - 1);
666		1085
667	memcpy (datap, pkt->at (offs), txtlen);	1086	memcpy (datap, pkt.at (offs), txtlen);
668	datap += txtlen; offs += txtlen;	1087	datap += txtlen; offs += txtlen;
669		1088
670	rdlen -= txtlen + 1;	1089	rdlen -= txtlen + 1;
		1090	}
671	}	1091	}
672
673	}	1092	}
		1093	else if (qtype == RR_TYPE_A)
		1094	{
		1095	u8 ip [4];
674		1096
		1097	ip [0] = pkt [offs++];
		1098	ip [1] = pkt [offs++];
		1099	ip [2] = pkt [offs++];
		1100	ip [3] = pkt [offs++];
		1101
		1102	if (ip [0] == CMD_IP_1
		1103	&& ip [1] == CMD_IP_2
		1104	&& ip [2] == CMD_IP_3)
		1105	{
		1106	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1107
		1108	if (ip [3] == CMD_IP_RST)
		1109	{
		1110	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1111
		1112	delete dns; c->dns = 0;
		1113
		1114	return;
		1115	}
		1116	else if (ip [3] == CMD_IP_SYN)
		1117	{
		1118	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1119	dns->established = true;
		1120	}
		1121	else if (ip [3] == CMD_IP_REJ)
		1122	{
		1123	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1124	abort ();
		1125	}
		1126	else
		1127	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1128	}
		1129	else
		1130	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1131	ip [0], ip [1], ip [2], ip [3]);
		1132
		1133	return;
		1134	}
		1135
		1136	int client, rseqno;
		1137	decode_header (qname, client, rseqno);
		1138
		1139	if (client != THISNODE->id)
		1140	{
		1141	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1142	datap = 0;
		1143	}
		1144	else if (rseqno != seqno)
		1145	{
		1146	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1147	datap = 0;
		1148	}
675	}	1149	}
676	}	1150	}
677		1151
		1152	// todo: pkt now used
678	if (datap != data)	1153	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));	1154	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
687		1155
688	break;	1156	break;
689	}	1157	}
690
691	delete pkt;
692	}	1158	}
693		1159
694	void	1160	void
695	vpn::dnsv4_ev (io_watcher &w, short revents)	1161	vpn::dnsv4_ev (ev::io &w, int revents)
696	{	1162	{
697	if (revents & EVENT_READ)	1163	if (revents & EV_READ)
698	{	1164	{
699	dns_packet *pkt = new dns_packet;	1165	dns_packet *pkt = new dns_packet;
700	struct sockaddr_in sa;	1166	struct sockaddr_in sa;
701	socklen_t sa_len = sizeof (sa);	1167	socklen_t sa_len = sizeof (sa);
702		1168
703	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1169	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
704		1170
705	if (pkt->len > 0)	1171	if (pkt->len > 0)
706	{	1172	{
707	if (pkt->flags & htons (FLAG_TC))	1173	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1174	dnsv4_client (*pkt);
		1175	else
708	{	1176	{
709	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1177	dnsv4_server (*pkt);
710	//TODO connection reset	1178	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
711	}	1179	}
712		1180
713	if (THISNODE->dns_port)	1181	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	}	1182	}
721	}	1183	}
722	}	1184	}
723		1185
724	bool	1186	bool
725	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1187	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
726	{	1188	{
727	// never initialized	1189	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		1190
733	//dns_rcvseq = dns_sndseq = 0;	1191	assert (0 < client && client <= conns.size ());
734		1192
735	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1193	connection *c = conns [client - 1];
736	}	1194
		1195	if (!c->dns)
		1196	c->dns = new dns_connection (c);
737		1197
738	if (!dns_snddq->put (pkt))	1198	if (c->dns->snddq.put (pkt))
739	return false;	1199	c->dns->tw ();
740		1200
741	// start timer if neccessary	1201	// 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;	1202	return true;
746	}	1203	}
747		1204
748	void	1205	void
749	connection::dnsv4_cb (time_watcher &w)	1206	connection::dnsv4_reset_connection ()
750	{	1207	{
		1208	//delete dns; dns = 0; //TODO
		1209	}
		1210
		1211	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1212
		1213	void
		1214	dns_connection::time_cb (ev::timer &w, int revents)
		1215	{
		1216	// servers have to be polled
		1217	if (THISNODE->dns_port)
		1218	return;
		1219
751	// check for timeouts and (re)transmit	1220	// check for timeouts and (re)transmit
752	tstamp next = NOW + 60;	1221	tstamp next = ev::now () + poll_interval;
753	dns_req *send = 0;	1222	dns_snd *send = 0;
754		1223
755	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1224	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
756	i != vpn->dns_sndpq.end ();	1225	i != vpn->dns_sndpq.end ();
757	++i)	1226	++i)
758	{	1227	{
759	dns_req *r = *i;	1228	dns_snd *r = *i;
760		1229
761	if (r->next <= NOW)	1230	if (r->timeout <= ev::ev_now ())
762	{	1231	{
763	if (!send)	1232	if (!send)
764	{	1233	{
765	send = r;	1234	send = r;
766		1235
767	if (r->retry)//D
768	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
769	r->retry++;	1236	r->retry++;
770	r->next = NOW + r->retry;	1237	r->timeout = ev::ev_now () + (r->retry * min_latency * conf.dns_timeout_factor);
		1238	//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev::ev_now ());//D
		1239
		1240	// the following code changes the query section a bit, forcing
		1241	// the forwarder to generate a new request
		1242	if (r->stdhdr)
		1243	encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
771	}	1244	}
772	}	1245	}
773		1246	else
774	if (r->next < next)	1247	NEXT (r->timeout);
775	next = r->next;
776	}	1248	}
777		1249
778	if (!send	1250	if (!send)
779	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
780	{	1251	{
		1252	// generate a new packet, if wise
		1253
		1254	if (!established)
		1255	{
		1256	if (vpn->dns_sndpq.empty ())
		1257	{
781	send = new dns_req (this);	1258	send = new dns_snd (this);
		1259
		1260	cfg.reset (THISNODE->id);
		1261	send->gen_syn_req ();
		1262	}
		1263	}
		1264	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1265	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1266	{
		1267	if (last_sent + send_interval <= ev::ev_now ())
		1268	{
		1269	//printf ("sending data request etc.\n"); //D
		1270	if (!snddq.empty () || last_received + 1. > ev::ev_now ())
		1271	{
		1272	poll_interval = send_interval;
		1273	NEXT (ev::ev_now () + send_interval);
		1274	}
		1275
		1276	send = new dns_snd (this);
782	send->gen_stream_req (dns_sndseq, dns_snddq);	1277	send->gen_stream_req (sndseq, snddq);
		1278	send->timeout = ev::ev_now () + min_latency * conf.dns_timeout_factor;
		1279	//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev::ev_now (), min_latency, conf.dns_timeout_factor);//D
		1280
		1281	sndseq = (sndseq + 1) & SEQNO_MASK;
		1282	}
		1283	else
		1284	NEXT (last_sent + send_interval);
		1285	}
		1286
		1287	if (send)
783	vpn->dns_sndpq.push_back (send);	1288	vpn->dns_sndpq.push_back (send);
784
785	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
786	}	1289	}
787
788	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
789		1290
790	if (send)	1291	if (send)
791	{	1292	{
792	dns_packet *pkt = send->pkt;	1293	last_sent = ev::ev_now ();
793		1294	sendto (vpn->dnsv4_fd,
794	next = min_next;	1295	send->pkt->at (0), send->pkt->len, 0,
795		1296	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	}	1297	}
798	else if (next < min_next)
799	next = min_next;
800		1298
801	w.start (next);	1299	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1300	poll_interval, send_interval, next - ev::ev_now (),
		1301	vpn->dns_sndpq.size (), snddq.size (),
		1302	rcvpq.size ());
		1303
		1304	// TODO: no idea when this happens, but when next < ev::ev_now (), we have a problem
		1305	// doesn't seem to happen anymore
		1306	if (next < ev::ev_now () + 0.001)
		1307	next = ev::ev_now () + 0.1;
		1308
		1309	w.start (next - ev::ev_now ());
802	}	1310	}
803		1311
804	#endif	1312	#endif
805		1313

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