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/cvs/gvpe/src/vpn_dns.C

Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.7 by pcg, Thu Mar 3 16:54:34 2005 UTC vs.
Revision 1.37 by pcg, Wed Mar 23 17:03:58 2005 UTC

…		…
25		25
26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.	26	// dns processing is EXTREMELY ugly. For obvious(?) reasons.
27	// it's a hack, use only in emergency situations please.	27	// it's a hack, use only in emergency situations please.
28		28
29	#include <cstring>	29	#include <cstring>
		30	#include <cassert>
30		31
31	#include <sys/types.h>	32	#include <sys/types.h>
32	#include <sys/socket.h>	33	#include <sys/socket.h>
33	#include <sys/wait.h>	34	#include <sys/wait.h>
34	#include <sys/uio.h>	35	#include <sys/uio.h>
…		…
37	#include <unistd.h>	38	#include <unistd.h>
38	#include <fcntl.h>	39	#include <fcntl.h>
39		40
40	#include <map>	41	#include <map>
41		42
		43	#include <gmp.h>
		44
42	#include "netcompat.h"	45	#include "netcompat.h"
43		46
44	#include "vpn.h"	47	#include "vpn.h"
45		48
46	#define MIN_RETRY 1.	49	#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
47	#define MAX_RETRY 60.	50	#define ACTIVITY_INTERVAL 5.
48		51
49	#define MAX_OUTSTANDING 40 // max. outstanding requests	52	#define INITIAL_TIMEOUT 0.1 // retry timeouts
		53	#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
		54
		55	#define MAX_SEND_INTERVAL 2. // optimistic?
		56
50	#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING	57	#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
51	#define MAX_RATE 1000 // requests/s
52	#define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE	58	#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
53		59
54	#define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well	60	#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
55	// 240 leaves about 4 bytes of server reply data	61	// 240 leaves about 4 bytes of server reply data
56	// every two request byte sless give room for one reply byte	62	// every request byte less give room for two reply bytes
57		63
58	// seqno has 12 bits, but the lower bit is always left as zero
59	// as bind caches ttl=0 records and we have to generate
60	// sequence numbers that always differ case-insensitively
61	#define SEQNO_MASK 0x07ff	64	#define SEQNO_MASK 0x3fff
62		65	#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
63	/*
64
65	protocol, in shorthand :)
66
67	client -> server <req> ANY?
68	server -> client <req> TXT <rep>
69
70	<req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>]
71	<rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>]
72
73	if <client-id> is zero, the connection will be configured:
74
75	<0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16>
76
77	*/
78		66
79	#define MAX_LBL_SIZE 63	67	#define MAX_LBL_SIZE 63
80	#define MAX_PKT_SIZE 512	68	#define MAX_PKT_SIZE 512
81		69
		70	#define RR_TYPE_A 1
		71	#define RR_TYPE_NULL 10
82	#define RR_TYPE_TXT 16	72	#define RR_TYPE_TXT 16
83	#define RR_TYPE_ANY 255	73	#define RR_TYPE_ANY 255
		74
84	#define RR_CLASS_IN 1	75	#define RR_CLASS_IN 1
85		76
86	// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative)	77	#define CMD_IP_1 207
87	struct dns64	78	#define CMD_IP_2 46
88	{	79	#define CMD_IP_3 236
89	static const char encode_chars[64 + 1];	80	#define CMD_IP_RST 29
90	static s8 decode_chars[256];	81	#define CMD_IP_SYN 113
		82	#define CMD_IP_REJ 32
91		83
92	static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; }	84	// works for cmaps up to 255 (not 256!)
93	static int decode_len (int bytes) { return (bytes * 6) / 8; }	85	struct charmap
		86	{
		87	enum { INVALID = (u8)255 };
		88
		89	char encode [256]; // index => char
		90	u8 decode [256]; // char => index
		91	unsigned int size;
		92
		93	charmap (const char *cmap);
		94	};
		95
		96	charmap::charmap (const char *cmap)
		97	{
		98	char *enc = encode;
		99	u8 *dec = decode;
		100
		101	memset (enc, (char) 0, 256);
		102	memset (dec, (char)INVALID, 256);
		103
		104	for (size = 0; cmap [size]; size++)
		105	{
		106	enc [size] = cmap [size];
		107	dec [(u8)enc [size]] = size;
		108	}
		109
		110	assert (size < 256);
		111	}
		112
		113	#define MAX_DEC_LEN 500
		114	#define MAX_ENC_LEN (MAX_DEC_LEN * 2)
		115	#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
		116
		117	// ugly. minimum base is 16(!)
		118	struct basecoder
		119	{
		120	charmap cmap;
		121	unsigned int enc_len [MAX_DEC_LEN];
		122	unsigned int dec_len [MAX_ENC_LEN];
		123
		124	unsigned int encode_len (unsigned int len);
		125	unsigned int decode_len (unsigned int len);
		126
94	static int encode (char *dst, u8 *src, int len);	127	unsigned int encode (char *dst, u8 *src, unsigned int len);
95	static int decode (u8 *dst, char *src, int len);	128	unsigned int decode (u8 *dst, char *src, unsigned int len);
96		129
97	dns64 ();	130	basecoder (const char *cmap);
98	} dns64;	131	};
99		132
100	// the following sequence has been crafted to	133	basecoder::basecoder (const char *cmap)
101	// a) look somewhat random	134	: cmap (cmap)
102	// b) the even (and odd) indices never share the same character as upper/lowercase
103	const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI";
104	s8 dns64::decode_chars[256];
105
106	dns64::dns64 ()
107	{	135	{
108	for (int i = 0; i < 64; i++)	136	for (unsigned int len = 0; len < MAX_DEC_LEN; ++len)
109	decode_chars [encode_chars [i]] = i + 1;	137	{
110	}	138	u8 src [MAX_DEC_LEN];
		139	u8 dst [MAX_ENC_LEN];
111		140
112	int dns64::encode (char *dst, u8 *src, int len)	141	memset (src, 255, len);
		142
		143	mp_limb_t m [MAX_LIMBS];
		144	mp_size_t n;
		145
		146	n = mpn_set_str (m, src, len, 256);
		147	n = mpn_get_str (dst, this->cmap.size, m, n);
		148
		149	for (int i = 0; !dst [i]; ++i)
		150	n--;
		151
		152	enc_len [len] = n;
		153	dec_len [n] = len;
		154	}
		155	}
		156
		157	unsigned int basecoder::encode_len (unsigned int len)
113	{	158	{
114	// slow, but easy to debug	159	return enc_len [len];
115	char *beg = dst;	160	}
116	unsigned int accum, bits = 0;	161
		162	unsigned int basecoder::decode_len (unsigned int len)
		163	{
		164	while (len && !dec_len [len])
		165	--len;
		166
		167	return dec_len [len];
		168	}
		169
		170	unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len)
		171	{
		172	if (!len || len > MAX_DEC_LEN)
		173	return 0;
		174
		175	int elen = encode_len (len);
		176
		177	mp_limb_t m [MAX_LIMBS];
		178	mp_size_t n;
		179
		180	u8 dst_ [MAX_ENC_LEN];
		181
		182	n = mpn_set_str (m, src, len, 256);
		183	n = mpn_get_str (dst_, cmap.size, m, n);
		184
		185	int plen = elen; // for padding
		186
		187	while (n < plen)
		188	{
		189	*dst++ = cmap.encode [0];
		190	plen--;
		191	}
		192
		193	for (unsigned int i = n - plen; i < n; ++i)
		194	*dst++ = cmap.encode [dst_ [i]];
		195
		196	return elen;
		197	}
		198
		199	unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len)
		200	{
		201	if (!len || len > MAX_ENC_LEN)
		202	return 0;
		203
		204	u8 src_ [MAX_ENC_LEN];
		205	unsigned int elen = 0;
117		206
118	while (len--)	207	while (len--)
119	{	208	{
120	accum <<= 8;	209	u8 val = cmap.decode [(u8)*src++];
121	accum |= *src++;
122	bits += 8;
123		210
124	while (bits >= 6)	211	if (val != charmap::INVALID)
125	{	212	src_ [elen++] = val;
126	*dst++ = encode_chars [(accum >> (bits - 6)) & 63];	213	}
127	bits -= 6;	214
128	}	215	int dlen = decode_len (elen);
		216
		217	mp_limb_t m [MAX_LIMBS];
		218	mp_size_t n;
		219
		220	u8 dst_ [MAX_DEC_LEN];
		221
		222	n = mpn_set_str (m, src_, elen, cmap.size);
		223	n = mpn_get_str (dst_, 256, m, n);
		224
		225	if (n < dlen)
129	}	226	{
		227	memset (dst, 0, dlen - n);
		228	memcpy (dst + dlen - n, dst_, n);
		229	}
		230	else
		231	memcpy (dst, dst_ + n - dlen, dlen);
130		232
131	if (bits)	233	return dlen;
132	*dst++ = encode_chars [(accum << (6 - bits)) & 63];
133
134	return dst - beg;
135	}	234	}
136		235
137	int dns64::decode (u8 *dst, char *src, int len)	236	#if 0
138	{	237	struct test { test (); } test;
139	// slow, but easy to debug
140	u8 *beg = dst;
141	unsigned int accum, bits = 0;
142		238
143	while (len--)	239	test::test ()
		240	{
		241	basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz");
		242
		243	u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		244	static char enc[200];
		245	static u8 dec[200];
		246
		247	for (int i = 1; i < 20; i++)
144	{	248	{
145	s8 chr = decode_chars [(u8)*src++];	249	int elen = cdc.encode (enc, in, i);
		250	int dlen = cdc.decode (dec, enc, elen);
146		251
147	if (!chr)	252	printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec);
148	continue;
149
150	accum <<= 6;
151	accum |= chr - 1;
152	bits += 6;
153
154	while (bits >= 8)
155	{
156	*dst++ = accum >> (bits - 8);
157	bits -= 8;
158	}
159	}	253	}
		254	abort ();
		255	}
		256	#endif
160		257
161	return dst - beg;	258	//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-");
		259	//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		260	static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI");
		261	//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet
		262	static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO");
		263
		264	/////////////////////////////////////////////////////////////////////////////
		265
		266	#define HDRSIZE 6
		267
		268	inline void encode_header (char *data, int clientid, int seqno, int retry = 0)
		269	{
		270	seqno &= SEQNO_MASK;
		271
		272	u8 hdr[3] = {
		273	clientid,
		274	(seqno >> 8) | (retry << 6),
		275	seqno,
		276	};
		277
		278	assert (clientid < 256);
		279
		280	cdc26.encode (data, hdr, 3);
		281	}
		282
		283	inline void decode_header (char *data, int &clientid, int &seqno)
		284	{
		285	u8 hdr[3];
		286
		287	cdc26.decode (hdr, data, HDRSIZE);
		288
		289	clientid = hdr[0];
		290	seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK;
162	}	291	}
163		292
164	/////////////////////////////////////////////////////////////////////////////	293	/////////////////////////////////////////////////////////////////////////////
165		294
166	struct byte_stream	295	struct byte_stream
…		…
195	}	324	}
196		325
197	void byte_stream::remove (int count)	326	void byte_stream::remove (int count)
198	{	327	{
199	if (count > fill)	328	if (count > fill)
200	abort ();	329	assert (count <= fill);
201		330
202	memmove (data, data + count, fill -= count);	331	memmove (data, data + count, fill -= count);
203	}	332	}
204		333
205	bool byte_stream::put (u8 *data, unsigned int datalen)	334	bool byte_stream::put (u8 *data, unsigned int datalen)
…		…
218	return false;	347	return false;
219		348
220	data [fill++] = pkt->len >> 8;	349	data [fill++] = pkt->len >> 8;
221	data [fill++] = pkt->len;	350	data [fill++] = pkt->len;
222		351
223	memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len;	352	memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len;
224		353
225	return true;	354	return true;
226	}	355	}
227		356
228	vpn_packet *byte_stream::get ()	357	vpn_packet *byte_stream::get ()
229	{	358	{
		359	unsigned int len;
		360
		361	for (;;)
		362	{
230	int len = (data [0] << 8) | data [1];	363	len = (data [0] << 8) | data [1];
231		364
232	if (len > MAXSIZE && fill >= 2)	365	if (len <= MAXSIZE || fill < 2)
233	abort (); // TODO handle this gracefully, connection reset	366	break;
234		367
		368	// TODO: handle this better than skipping, e.g. by reset
		369	slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte..."));
		370	remove (1);
		371	}
		372
235	if (fill < len + 2)	373	if (fill < len + 2)
236	return 0;	374	return 0;
237		375
238	vpn_packet *pkt = new vpn_packet;	376	vpn_packet *pkt = new vpn_packet;
239		377
240	pkt->len = len;	378	pkt->len = len;
241	memcpy (&((*pkt)[0]), data + 2, len);	379	memcpy (pkt->at (0), data + 2, len);
242	remove (len + 2);	380	remove (len + 2);
243		381
244	return pkt;	382	return pkt;
245	}	383	}
246		384
247	/////////////////////////////////////////////////////////////////////////////	385	/////////////////////////////////////////////////////////////////////////////
248		386
249	#define FLAG_QUERY ( 0 << 15)	387	#define FLAG_QUERY ( 0 << 15)
250	#define FLAG_RESPONSE ( 1 << 15)	388	#define FLAG_RESPONSE ( 1 << 15)
251	#define FLAG_OP_MASK (15 << 14)	389	#define FLAG_OP_MASK (15 << 11)
252	#define FLAG_OP_QUERY ( 0 << 11)	390	#define FLAG_OP_QUERY ( 0 << 11)
253	#define FLAG_AA ( 1 << 10)	391	#define FLAG_AA ( 1 << 10)
254	#define FLAG_TC ( 1 << 9)	392	#define FLAG_TC ( 1 << 9)
255	#define FLAG_RD ( 1 << 8)	393	#define FLAG_RD ( 1 << 8)
256	#define FLAG_RA ( 1 << 7)	394	#define FLAG_RA ( 1 << 7)
…		…
263	#define FLAG_RCODE_REFUSED ( 5 << 0)	401	#define FLAG_RCODE_REFUSED ( 5 << 0)
264		402
265	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)	403	#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD)
266	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)	404	#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA)
267		405
		406	struct dns_cfg
		407	{
		408	static int next_uid;
		409
		410	u8 id1, id2, id3, id4;
		411
		412	u8 version;
		413	u8 flags;
		414	u8 rrtype;
		415	u8 def_ttl;
		416
		417	u16 client;
		418	u16 uid; // to make request unique
		419
		420	u16 max_size;
		421	u8 seq_cdc;
		422	u8 req_cdc;
		423
		424	u8 rep_cdc;
		425	u8 delay; // time in 0.01s units that the server may delay replying packets
		426	u8 r3, r4;
		427
		428	u8 r5, r6, r7, r8;
		429
		430	void reset (int clientid);
		431	bool valid ();
		432	};
		433
		434	int dns_cfg::next_uid;
		435
		436	void dns_cfg::reset (int clientid)
		437	{
		438	id1 = 'G';
		439	id2 = 'V';
		440	id3 = 'P';
		441	id4 = 'E';
		442
		443	version = 1;
		444
		445	rrtype = RR_TYPE_TXT;
		446	flags = 0;
		447	def_ttl = 0;
		448	seq_cdc = 26;
		449	req_cdc = 62;
		450	rep_cdc = 0;
		451	max_size = htons (MAX_PKT_SIZE);
		452	client = htons (clientid);
		453	uid = next_uid++;
		454	delay = 0;
		455
		456	r3 = r4 = 0;
		457	r4 = r5 = r6 = r7 = 0;
		458	}
		459
		460	bool dns_cfg::valid ()
		461	{
		462	return id1 == 'G'
		463	&& id2 == 'V'
		464	&& id3 == 'P'
		465	&& id4 == 'E'
		466	&& seq_cdc == 26
		467	&& req_cdc == 62
		468	&& rep_cdc == 0
		469	&& version == 1;
		470	}
		471
268	struct dns_packet : net_packet	472	struct dns_packet : net_packet
269	{	473	{
270	u16 id;	474	u16 id;
271	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4	475	u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4
272	u16 qdcount, ancount, nscount, arcount;	476	u16 qdcount, ancount, nscount, arcount;
273		477
274	u8 data[MAXSIZE - 6 * 2];	478	u8 data [MAXSIZE - 6 * 2];
275		479
276	int decode_label (char *data, int size, int &offs);	480	int decode_label (char *data, int size, int &offs);
277	};	481	};
278		482
279	int dns_packet::decode_label (char *data, int size, int &offs)	483	int dns_packet::decode_label (char *data, int size, int &offs)
…		…
310	return data - orig;	514	return data - orig;
311	}	515	}
312		516
313	/////////////////////////////////////////////////////////////////////////////	517	/////////////////////////////////////////////////////////////////////////////
314		518
315	struct dns_req
316	{
317	dns_packet *pkt;
318	tstamp next;
319	int retry;
320	connection *conn;
321	int seqno;
322
323	dns_req (connection *c);
324	void gen_stream_req (int seqno, byte_stream *stream);
325	};
326
327	static u16 dns_id = 12098; // TODO: should be per-vpn	519	static u16 dns_id = 0; // TODO: should be per-vpn
328		520
329	static u16 next_id ()	521	static u16 next_id ()
330	{	522	{
		523	if (!dns_id)
		524	dns_id = time (0);
		525
331	// the simplest lsfr with periodicity 65535 i could find	526	// the simplest lsfr with periodicity 65535 i could find
332	dns_id = (dns_id << 1)	527	dns_id = (dns_id << 1)
333	| (((dns_id >> 1)	528	| (((dns_id >> 1)
334	^ (dns_id >> 2)	529	^ (dns_id >> 2)
335	^ (dns_id >> 4)	530	^ (dns_id >> 4)
336	^ (dns_id >> 15)) & 1);	531	^ (dns_id >> 15)) & 1);
337		532
338	return dns_id;	533	return dns_id;
339	}	534	}
340		535
341	dns_req::dns_req (connection *c)	536	struct dns_rcv;
342	: conn (c)	537	struct dns_snd;
		538
		539	struct dns_connection
343	{	540	{
344	next = 0;	541	connection *c;
		542	struct vpn *vpn;
		543
		544	dns_cfg cfg;
		545
		546	bool established;
		547
		548	tstamp last_received;
		549	tstamp last_sent;
		550	double min_latency;
		551	double poll_interval, send_interval;
		552
		553	vector<dns_rcv *> rcvpq;
		554
		555	byte_stream rcvdq; int rcvseq; int repseq;
		556	byte_stream snddq; int sndseq;
		557
		558	void time_cb (time_watcher &w); time_watcher tw;
		559	void receive_rep (dns_rcv *r);
		560
		561	dns_connection (connection *c);
		562	~dns_connection ();
		563	};
		564
		565	struct dns_snd
		566	{
		567	dns_packet *pkt;
		568	tstamp timeout, sent;
		569	int retry;
		570	struct dns_connection *dns;
		571	int seqno;
		572	bool stdhdr;
		573
		574	void gen_stream_req (int seqno, byte_stream &stream);
		575	void gen_syn_req ();
		576
		577	dns_snd (dns_connection *dns);
		578	~dns_snd ();
		579	};
		580
		581	dns_snd::dns_snd (dns_connection *dns)
		582	: dns (dns)
		583	{
		584	timeout = 0;
345	retry = 0;	585	retry = 0;
		586	seqno = 0;
		587	sent = NOW;
		588	stdhdr = false;
346		589
347	pkt = new dns_packet;	590	pkt = new dns_packet;
348		591
349	pkt->id = next_id ();	592	pkt->id = next_id ();
350	}	593	}
351		594
		595	dns_snd::~dns_snd ()
		596	{
		597	delete pkt;
		598	}
		599
		600	static void append_domain (dns_packet &pkt, int &offs, const char *domain)
		601	{
		602	// add tunnel domain
		603	for (;;)
		604	{
		605	const char *end = strchr (domain, '.');
		606
		607	if (!end)
		608	end = domain + strlen (domain);
		609
		610	int len = end - domain;
		611
		612	pkt [offs++] = len;
		613	memcpy (pkt.at (offs), domain, len);
		614	offs += len;
		615
		616	if (!*end)
		617	break;
		618
		619	domain = end + 1;
		620	}
		621	}
		622
352	void dns_req::gen_stream_req (int seqno, byte_stream *stream)	623	void dns_snd::gen_stream_req (int seqno, byte_stream &stream)
353	{	624	{
		625	stdhdr = true;
354	this->seqno = seqno;	626	this->seqno = seqno;
		627
		628	timeout = NOW + INITIAL_TIMEOUT;
355		629
356	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);	630	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
357	pkt->qdcount = htons (1);	631	pkt->qdcount = htons (1);
358		632
359	int offs = 6*2;	633	int offs = 6*2;
360	int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2;	634	int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2);
361	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,	635	// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well,
362	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra	636	// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra
363		637
364	u8 data[256]; //TODO
365
366	data[0] = THISNODE->id; //TODO
367	data[1] = seqno >> 7; //TODO
368	data[2] = seqno << 1; //TODO
369
370	int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3;
371
372	if (datalen > stream->size ())
373	datalen = stream->size ();
374
375	char enc[256], *encp = enc;	638	char enc[256], *encp = enc;
376		639	encode_header (enc, THISNODE->id, seqno);
377	memcpy (data + 3, stream->begin (), datalen);	640
378	int enclen = dns64::encode (enc, data, datalen + 3);	641	int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE);
		642
		643	if (datalen > stream.size ())
		644	datalen = stream.size ();
		645
		646	int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE;
379	stream->remove (datalen);	647	stream.remove (datalen);
380		648
381	while (enclen)	649	while (enclen)
382	{	650	{
383	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;	651	int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE;
384		652
…		…
389	encp += lbllen;	657	encp += lbllen;
390		658
391	enclen -= lbllen;	659	enclen -= lbllen;
392	}	660	}
393		661
394	const char *suffix = THISNODE->domain;	662	append_domain (*pkt, offs, dns->c->conf->domain);
395
396	// add tunnel domain
397	for (;;)
398	{
399	const char *end = strchr (suffix, '.');
400
401	if (!end)
402	end = suffix + strlen (suffix);
403
404	int len = end - suffix;
405
406	(*pkt)[offs++] = len;
407	memcpy (&((*pkt)[offs]), suffix, len);
408	offs += len;
409
410	if (!*end)
411	break;
412
413	suffix = end + 1;
414	}
415		663
416	(*pkt)[offs++] = 0;	664	(*pkt)[offs++] = 0;
417	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;	665	(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY;
		666	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
		667
		668	pkt->len = offs;
		669	}
		670
		671	void dns_snd::gen_syn_req ()
		672	{
		673	timeout = NOW + INITIAL_SYN_TIMEOUT;
		674
		675	pkt->flags = htons (DEFAULT_CLIENT_FLAGS);
		676	pkt->qdcount = htons (1);
		677
		678	int offs = 6 * 2;
		679
		680	int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg));
		681
		682	assert (elen <= MAX_LBL_SIZE);
		683
		684	(*pkt)[offs] = elen;
		685	offs += elen + 1;
		686	append_domain (*pkt, offs, dns->c->conf->domain);
		687
		688	(*pkt)[offs++] = 0;
		689	(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A;
418	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;	690	(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN;
419		691
420	pkt->len = offs;	692	pkt->len = offs;
421	}	693	}
422		694
…		…
441	{	713	{
442	delete pkt;	714	delete pkt;
443	}	715	}
444		716
445	/////////////////////////////////////////////////////////////////////////////	717	/////////////////////////////////////////////////////////////////////////////
446		718
447	struct dns_cfg	719	dns_connection::dns_connection (connection *c)
		720	: c (c)
		721	, rcvdq (MAX_BACKLOG * 2)
		722	, snddq (MAX_BACKLOG)
		723	, tw (this, &dns_connection::time_cb)
448	{	724	{
449	u8 id1, id2, id3;	725	vpn = c->vpn;
450	u8 def_ttl;
451	u8 unused1;
452	u16 max_size;
453	u8 flags1, flags2;
454	};
455		726
		727	established = false;
		728
		729	rcvseq = repseq = sndseq = 0;
		730
		731	last_sent = last_received = 0;
		732	poll_interval = 0.5; // starting here
		733	send_interval = 0.5; // starting rate
		734	min_latency = INITIAL_TIMEOUT;
		735	}
		736
		737	dns_connection::~dns_connection ()
		738	{
		739	for (vector<dns_rcv *>::iterator i = rcvpq.begin ();
		740	i != rcvpq.end ();
		741	++i)
		742	delete *i;
		743	}
		744
456	void connection::dnsv4_receive_rep (struct dns_rcv *r)	745	void dns_connection::receive_rep (dns_rcv *r)
457	{	746	{
		747	if (r->datalen)
		748	{
		749	last_received = NOW;
		750	tw.trigger ();
		751
		752	poll_interval = send_interval;
		753	}
		754	else
		755	{
		756	poll_interval *= 1.5;
		757
		758	if (poll_interval > MAX_POLL_INTERVAL)
		759	poll_interval = MAX_POLL_INTERVAL;
		760	}
		761
458	dns_rcvpq.push_back (r);	762	rcvpq.push_back (r);
459		763
460	redo:	764	redo:
461		765
		766	// find next packet
462	for (vector<dns_rcv *>::iterator i = dns_rcvpq.begin ();	767	for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
463	i != dns_rcvpq.end ();
464	++i)
465	if (dns_rcvseq == (*i)->seqno)	768	if (SEQNO_EQ (rcvseq, (*i)->seqno))
466	{	769	{
		770	// enter the packet into our input stream
467	dns_rcv *r = *i;	771	r = *i;
468		772
		773	// remove the oldest packet, look forward, as it's oldest first
		774	for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
		775	if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
		776	{
		777	delete *j;
		778	rcvpq.erase (j);
		779	break;
		780	}
		781
469	dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK;	782	rcvseq = (rcvseq + 1) & SEQNO_MASK;
470		783
471	if (!dns_snddq && !dns_rcvdq)	784	if (!rcvdq.put (r->data, r->datalen))
472	{	785	{
473	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);	786	slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)");
474	dns_snddq = new byte_stream (MAX_BACKLOG);	787	abort (); // MUST never overflow, can be caused by data corruption, TODO
475
476	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);
477	}	788	}
478		789
479	if (!dns_rcvdq->put (r->data, r->datalen))
480	abort (); // MUST never overflow, can be caused by data corruption, TODO
481
482	while (vpn_packet *pkt = dns_rcvdq->get ())	790	while (vpn_packet *pkt = rcvdq.get ())
483	{	791	{
484	sockinfo si;	792	sockinfo si;
485	si.host = 0; si.port = 0; si.prot = PROT_DNSv4;	793	si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
486		794
487	vpn->recv_vpn_packet (pkt, si);	795	vpn->recv_vpn_packet (pkt, si);
		796
		797	delete pkt;
488	}	798	}
489	}	799
490	else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2)	800	// check for further packets
491	{
492	//D
493	//abort();
494	printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq);
495	dns_rcvpq.erase (i);
496	goto redo;	801	goto redo;
497	}	802	}
498	}	803	}
499		804
500	dns_packet *	805	void
501	vpn::dnsv4_server (dns_packet *pkt)	806	vpn::dnsv4_server (dns_packet &pkt)
502	{	807	{
503	u16 flags = ntohs (pkt->flags);	808	u16 flags = ntohs (pkt.flags);
504		809
505	//memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len);
506	int offs = 6 * 2; // skip header	810	int offs = 6 * 2; // skip header
507		811
508	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);	812	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
509		813
510	if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	814	if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK))
511	&& pkt->qdcount == htons (1))	815	&& pkt.qdcount == htons (1))
512	{	816	{
513	char qname[MAXSIZE];	817	char qname [MAXSIZE];
514	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	818	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
515		819
516	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	820	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
517	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	821	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
518		822
519	pkt->qdcount = htons (1);	823	pkt.qdcount = htons (1);
520	pkt->ancount = 0;	824	pkt.ancount = 0;
521	pkt->nscount = 0; // should be self, as other nameservers reply like this	825	pkt.nscount = 0; // should be self, as other nameservers reply like this
522	pkt->arcount = 0; // a record for self, as other nameservers reply like this	826	pkt.arcount = 0; // a record for self, as other nameservers reply like this
523		827
524	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN);	828	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL);
525		829
526	int dlen = strlen (THISNODE->domain);	830	int dlen = strlen (THISNODE->domain);
527		831
528	if (qclass == RR_CLASS_IN	832	if (qclass == RR_CLASS_IN
529	&& (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT)
530	&& qlen > dlen + 1	833	&& qlen > dlen + 1
531	&& !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen))	834	&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen))
532	{	835	{
533	// correct class, domain: parse	836	// now generate reply
534	u8 data[MAXSIZE];	837	pkt.ancount = htons (1); // one answer RR
535	int datalen = dns64::decode (data, qname, qlen - dlen - 1);	838	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);
536		839
537	int client = data[0];	840	if ((qtype == RR_TYPE_ANY
538	int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK;	841	|| qtype == RR_TYPE_TXT
539		842	|| qtype == RR_TYPE_NULL)
540	if (0 < client && client <= conns.size ())	843	&& qlen > dlen + 1 + HDRSIZE)
541	{	844	{
		845	// correct class, domain: parse
		846	int client, seqno;
		847	decode_header (qname, client, seqno);
		848
		849	u8 data[MAXSIZE];
		850	int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE));
		851
		852	if (0 < client && client <= conns.size ())
		853	{
542	connection *c = conns [client - 1];	854	connection *c = conns [client - 1];
		855	dns_connection *dns = c->dns;
		856	dns_rcv *rcv;
543		857
544	redo:	858	if (dns)
545
546	for (vector<dns_rcv *>::iterator i = c->dns_rcvpq.begin ();
547	i != c->dns_rcvpq.end ();
548	++i)	859	{
		860	for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
549	if ((*i)->seqno == seqno)	861	if (SEQNO_EQ ((*i)->seqno, seqno))
		862	{
		863	// already seen that request: simply reply with the cached reply
		864	dns_rcv *r = *i;
		865
		866	slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno);
		867
		868	// refresh header & id, as the retry count could have changed
		869	memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE);
		870	r->pkt->id = pkt.id;
		871
		872	memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
		873
		874	goto duplicate_request;
		875	}
		876
		877	// new packet, queue
		878	rcv = new dns_rcv (seqno, data, datalen);
		879	dns->receive_rep (rcv);
		880	}
		881
550	{	882	{
551	// already seen that request: simply reply with the cached reply	883	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
552	dns_rcv *r = *i;
553		884
554	printf ("DUPLICATE %d\n", htons (r->pkt->id));//D	885	int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A;
		886	pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type
		887	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
		888	pkt [offs++] = 0; pkt [offs++] = 0;
		889	pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
555		890
		891	int rdlen_offs = offs += 2;
		892
		893	if (dns)
		894	{
		895	int dlen = ntohs (dns->cfg.max_size) - offs;
		896
		897	// bind doesn't compress well, so reduce further by one label length
		898	dlen -= qlen;
		899
		900	// only put data into in-order sequence packets, if
		901	// we receive out-of-order packets we generate empty
		902	// replies
		903	//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
		904	if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
		905	{
		906	dns->repseq = seqno;
		907
		908	while (dlen > 1 && !dns->snddq.empty ())
		909	{
		910	int txtlen = dlen <= 255 ? dlen - 1 : 255;
		911
		912	if (txtlen > dns->snddq.size ())
		913	txtlen = dns->snddq.size ();
		914
		915	pkt[offs++] = txtlen;
		916	memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
		917	offs += txtlen;
		918	dns->snddq.remove (txtlen);
		919
		920	dlen -= txtlen + 1;
		921	}
		922	}
		923
		924	// avoid completely empty TXT rdata
		925	if (offs == rdlen_offs)
		926	pkt[offs++] = 0;
		927
		928	slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
		929	}
		930	else
		931	{
		932	// send RST
		933	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
		934	pkt [offs++] = CMD_IP_RST;
		935	}
		936
		937	int rdlen = offs - rdlen_offs;
		938
		939	pkt [rdlen_offs - 2] = rdlen >> 8;
		940	pkt [rdlen_offs - 1] = rdlen;
		941
		942	if (dns)
		943	{
		944	// now update dns_rcv copy
556	offs = r->pkt->len;	945	rcv->pkt->len = offs;
557	memcpy (pkt->at (0), r->pkt->at (0), offs);	946	memcpy (rcv->pkt->at (0), pkt.at (0), offs);
558	goto duplicate_request;	947	}
559	}	948	}
560		949
561	// new packet, queue	950	duplicate_request: ;
562	dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3);	951	}
563	c->dnsv4_receive_rep (rcv);	952	else
564
565	// now generate reply
566	pkt->ancount = htons (1); // one answer RR
567	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK);	953	pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
		954	}
		955	else if (qtype == RR_TYPE_A
		956	&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg)))
		957	{
		958	dns_cfg cfg;
		959	cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg)));
		960	int client = ntohs (cfg.client);
568		961
569	(*pkt) [offs++] = 0xc0;
570	(*pkt) [offs++] = 6 * 2; // same as in query section	962	pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section
571		963
572	(*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT;	964	pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type
573	(*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN;	965	pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class
574
575	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0;	966	pkt [offs++] = 0; pkt [offs++] = 0;
576	(*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL	967	pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL
		968	pkt [offs++] = 0; pkt [offs++] = 4; // rdlength
577		969
578	int dlen = MAX_PKT_SIZE - offs - 2;	970	slog (L_INFO, _("DNS: client %d connects"), client);
579		971
580	// bind doesn't compress well, so reduce further by one label length	972	pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3;
581	dlen -= qlen;	973	pkt [offs++] = CMD_IP_REJ;
582		974
583	int rdlen_offs = offs += 2;	975	if (0 < client && client <= conns.size ())
584
585	while (c->dns_snddq
586	&& !c->dns_snddq->empty ()
587	&& dlen > 1)
588	{	976	{
589	int txtlen = dlen <= 255 ? dlen - 1 : 255;	977	connection *c = conns [client - 1];
590		978
591	if (txtlen > c->dns_snddq->size ())	979	if (cfg.valid ())
592	txtlen = c->dns_snddq->size ();	980	{
		981	pkt [offs - 1] = CMD_IP_SYN;
593		982
594	(*pkt)[offs++] = txtlen;	983	delete c->dns;
595	memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen);	984	c->dns = new dns_connection (c);
596	offs += txtlen;	985	c->dns->cfg = cfg;
597	c->dns_snddq->remove (txtlen);	986	}
598
599	dlen -= txtlen + 1;
600	}	987	}
601
602	// avoid empty TXT rdata
603	if (offs == rdlen_offs)
604	(*pkt)[offs++] = 0;
605
606	int rdlen = offs - rdlen_offs;
607
608	(*pkt) [rdlen_offs - 2] = rdlen >> 8;
609	(*pkt) [rdlen_offs - 1] = rdlen;
610
611	// now update dns_rcv copy
612	rcv->pkt->len = offs;
613	memcpy (rcv->pkt->at (0), pkt->at (0), offs);
614
615	duplicate_request: ;
616	}	988	}
617	else
618	pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR);
619	}	989	}
620		990
621	pkt->len = offs;	991	pkt.len = offs;
622	}	992	}
623
624	return pkt;
625	}	993	}
626		994
627	void	995	void
628	vpn::dnsv4_client (dns_packet *pkt)	996	vpn::dnsv4_client (dns_packet &pkt)
629	{	997	{
630	u16 flags = ntohs (pkt->flags);	998	u16 flags = ntohs (pkt.flags);
631	int offs = 6 * 2; // skip header	999	int offs = 6 * 2; // skip header
632		1000
633	pkt->qdcount = ntohs (pkt->qdcount);	1001	pkt.qdcount = ntohs (pkt.qdcount);
634	pkt->ancount = ntohs (pkt->ancount);	1002	pkt.ancount = ntohs (pkt.ancount);
635		1003
636	// go through our request list and find the corresponding request	1004	// go through our request list and find the corresponding request
637	for (vector<dns_req *>::iterator i = dns_sndpq.begin ();	1005	for (vector<dns_snd *>::iterator i = dns_sndpq.begin ();
638	i != dns_sndpq.end ();	1006	i != dns_sndpq.end ();
639	++i)	1007	++i)
640	if ((*i)->pkt->id == pkt->id)	1008	if ((*i)->pkt->id == pkt.id)
641	{	1009	{
		1010	dns_connection *dns = (*i)->dns;
642	connection *c = (*i)->conn;	1011	connection *c = dns->c;
643	int seqno = (*i)->seqno;	1012	int seqno = (*i)->seqno;
644	u8 data[MAXSIZE], *datap = data;	1013	u8 data[MAXSIZE], *datap = data;
645		1014
		1015	if ((*i)->retry)
		1016	{
		1017	dns->send_interval *= 1.01;
		1018	if (dns->send_interval > MAX_SEND_INTERVAL)
		1019	dns->send_interval = MAX_SEND_INTERVAL;
		1020	}
		1021	else
		1022	{
		1023	#if 0
		1024	dns->send_interval *= 0.999;
		1025	#endif
		1026	// the latency surely puts an upper bound on
		1027	// the minimum send interval
		1028	double latency = NOW - (*i)->sent;
		1029
		1030	if (latency < dns->min_latency)
		1031	dns->min_latency = latency;
		1032
		1033	if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
		1034	dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
		1035
		1036	if (dns->send_interval < conf.dns_send_interval)
		1037	dns->send_interval = conf.dns_send_interval;
		1038	}
		1039
646	delete *i;	1040	delete *i;
647	dns_sndpq.erase (i);	1041	dns_sndpq.erase (i);
648		1042
649	if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC))	1043	if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK))
650	{	1044	{
651	char qname[MAXSIZE];	1045	char qname[MAXSIZE];
652		1046
653	while (pkt->qdcount-- && offs < MAXSIZE - 4)	1047	while (pkt.qdcount-- && offs < MAXSIZE - 4)
654	{	1048	{
655	int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1049	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
656	offs += 4; // skip qtype, qclass	1050	offs += 4; // skip qtype, qclass
657	}	1051	}
658		1052
659	while (pkt->ancount-- && offs < MAXSIZE - 10)	1053	while (pkt.ancount-- && offs < MAXSIZE - 10 && datap)
660	{	1054	{
661	pkt->decode_label ((char *)qname, MAXSIZE - offs, offs);	1055	int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs);
662		1056
663	u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++];	1057	u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++];
664	u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++];	1058	u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++];
665	u32 ttl = (*pkt) [offs++] << 24;	1059	u32 ttl = pkt [offs++] << 24;
666	ttl |= (*pkt) [offs++] << 16;	1060	ttl |= pkt [offs++] << 16;
667	ttl |= (*pkt) [offs++] << 8;	1061	ttl |= pkt [offs++] << 8;
668	ttl |= (*pkt) [offs++];	1062	ttl |= pkt [offs++];
669
670	u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++];	1063	u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++];
671		1064
672	if (rdlen <= MAXSIZE - offs)	1065	if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT)
673	{	1066	{
674	// decode bytes, finally	1067	if (rdlen <= MAXSIZE - offs)
675
676	while (rdlen)
677	{	1068	{
		1069	// decode bytes, finally
		1070
		1071	while (rdlen)
		1072	{
678	int txtlen = (*pkt) [offs++];	1073	int txtlen = pkt [offs++];
679		1074
680	assert (txtlen + offs < MAXSIZE - 1);	1075	assert (txtlen + offs < MAXSIZE - 1);
681		1076
682	memcpy (datap, pkt->at (offs), txtlen);	1077	memcpy (datap, pkt.at (offs), txtlen);
683	datap += txtlen; offs += txtlen;	1078	datap += txtlen; offs += txtlen;
684		1079
685	rdlen -= txtlen + 1;	1080	rdlen -= txtlen + 1;
		1081	}
686	}	1082	}
687
688	}	1083	}
		1084	else if (qtype == RR_TYPE_A)
		1085	{
		1086	u8 ip [4];
689		1087
		1088	ip [0] = pkt [offs++];
		1089	ip [1] = pkt [offs++];
		1090	ip [2] = pkt [offs++];
		1091	ip [3] = pkt [offs++];
		1092
		1093	if (ip [0] == CMD_IP_1
		1094	&& ip [1] == CMD_IP_2
		1095	&& ip [2] == CMD_IP_3)
		1096	{
		1097	slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]);
		1098
		1099	if (ip [3] == CMD_IP_RST)
		1100	{
		1101	slog (L_DEBUG, _("DNS: got tunnel RST request"));
		1102
		1103	delete dns; c->dns = 0;
		1104
		1105	return;
		1106	}
		1107	else if (ip [3] == CMD_IP_SYN)
		1108	{
		1109	slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us."));
		1110	dns->established = true;
		1111	}
		1112	else if (ip [3] == CMD_IP_REJ)
		1113	{
		1114	slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting."));
		1115	abort ();
		1116	}
		1117	else
		1118	slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]);
		1119	}
		1120	else
		1121	slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"),
		1122	ip [0], ip [1], ip [2], ip [3]);
		1123
		1124	return;
		1125	}
		1126
		1127	int client, rseqno;
		1128	decode_header (qname, client, rseqno);
		1129
		1130	if (client != THISNODE->id)
		1131	{
		1132	slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring"));
		1133	datap = 0;
		1134	}
		1135	else if (rseqno != seqno)
		1136	{
		1137	slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?"));
		1138	datap = 0;
		1139	}
690	}	1140	}
691	}	1141	}
692		1142
693	// todo: pkt now used	1143	// todo: pkt now used
		1144	if (datap)
694	c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data));	1145	dns->receive_rep (new dns_rcv (seqno, data, datap - data));
695		1146
696	break;	1147	break;
697	}	1148	}
698
699	delete pkt;
700	}	1149	}
701		1150
702	void	1151	void
703	vpn::dnsv4_ev (io_watcher &w, short revents)	1152	vpn::dnsv4_ev (io_watcher &w, short revents)
704	{	1153	{
…		…
706	{	1155	{
707	dns_packet *pkt = new dns_packet;	1156	dns_packet *pkt = new dns_packet;
708	struct sockaddr_in sa;	1157	struct sockaddr_in sa;
709	socklen_t sa_len = sizeof (sa);	1158	socklen_t sa_len = sizeof (sa);
710		1159
711	pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);	1160	pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len);
712		1161
713	if (pkt->len > 0)	1162	if (pkt->len > 0)
714	{	1163	{
715	if (pkt->flags & htons (FLAG_TC))	1164	if (ntohs (pkt->flags) & FLAG_RESPONSE)
		1165	dnsv4_client (*pkt);
		1166	else
716	{	1167	{
717	slog (L_WARN, _("DNS request/response truncated, check protocol settings."));	1168	dnsv4_server (*pkt);
718	//TODO connection reset	1169	sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len);
719	}	1170	}
720		1171
721	if (THISNODE->dns_port)	1172	delete pkt;
722	{
723	pkt = dnsv4_server (pkt);
724	sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len);
725	}
726	else
727	dnsv4_client (pkt);
728	}	1173	}
729	}	1174	}
730	}	1175	}
731		1176
732	bool	1177	bool
733	connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)	1178	vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
734	{	1179	{
735	// never initialized	1180	int client = ntohl (si.host);
736	if (!dns_snddq && !dns_rcvdq)
737	{
738	dns_rcvdq = new byte_stream (MAX_BACKLOG * 2);
739	dns_snddq = new byte_stream (MAX_BACKLOG);
740		1181
741	//dns_rcvseq = dns_sndseq = 0;	1182	assert (0 < client && client <= conns.size ());
742		1183
743	dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4);	1184	connection *c = conns [client - 1];
744	}	1185
		1186	if (!c->dns)
		1187	c->dns = new dns_connection (c);
745		1188
746	if (!dns_snddq->put (pkt))	1189	if (c->dns->snddq.put (pkt))
747	return false;	1190	c->dns->tw.trigger ();
748		1191
749	// start timer if neccessary	1192	// always return true even if the buffer overflows
750	if (!THISNODE->dns_port && !dnsv4_tw.active)
751	dnsv4_cb (dnsv4_tw);
752
753	return true;	1193	return true;
754	}	1194	}
755		1195
756	void	1196	void
		1197	connection::dnsv4_reset_connection ()
		1198	{
		1199	//delete dns; dns = 0; //TODO
		1200	}
		1201
		1202	#define NEXT(w) do { if (next > (w)) next = w; } while (0)
		1203
		1204	void
757	connection::dnsv4_cb (time_watcher &w)	1205	dns_connection::time_cb (time_watcher &w)
758	{	1206	{
		1207	// servers have to be polled
		1208	if (THISNODE->dns_port)
		1209	return;
		1210
759	// check for timeouts and (re)transmit	1211	// check for timeouts and (re)transmit
760	tstamp next = NOW + 60;	1212	tstamp next = NOW + poll_interval;
761	dns_req *send = 0;	1213	dns_snd *send = 0;
762		1214
763	for (vector<dns_req *>::iterator i = vpn->dns_sndpq.begin ();	1215	for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin ();
764	i != vpn->dns_sndpq.end ();	1216	i != vpn->dns_sndpq.end ();
765	++i)	1217	++i)
766	{	1218	{
767	dns_req *r = *i;	1219	dns_snd *r = *i;
768		1220
769	if (r->next <= NOW)	1221	if (r->timeout <= NOW)
770	{	1222	{
771	if (!send)	1223	if (!send)
772	{	1224	{
773	send = r;	1225	send = r;
774		1226
775	if (r->retry)//D
776	printf ("req %d, retry %d\n", r->pkt->id, r->retry);
777	r->retry++;	1227	r->retry++;
778	r->next = NOW + r->retry;	1228	r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
		1229
		1230	// the following code changes the query section a bit, forcing
		1231	// the forwarder to generate a new request
		1232	if (r->stdhdr)
		1233	{
		1234	//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
		1235	//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
		1236	}
779	}	1237	}
780	}	1238	}
781		1239	else
782	if (r->next < next)	1240	NEXT (r->timeout);
783	next = r->next;
784	}	1241	}
785		1242
786	if (!send	1243	if (!send)
787	&& vpn->dns_sndpq.size () < MAX_OUTSTANDING)
788	{	1244	{
		1245	// generate a new packet, if wise
		1246
		1247	if (!established)
		1248	{
		1249	if (vpn->dns_sndpq.empty ())
		1250	{
789	send = new dns_req (this);	1251	send = new dns_snd (this);
		1252
		1253	cfg.reset (THISNODE->id);
		1254	send->gen_syn_req ();
		1255	}
		1256	}
		1257	else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
		1258	&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
		1259	{
		1260	if (last_sent + send_interval <= NOW)
		1261	{
		1262	//printf ("sending data request etc.\n"); //D
		1263	if (!snddq.empty () || last_received + 1. > NOW)
		1264	{
		1265	poll_interval = send_interval;
		1266	NEXT (NOW + send_interval);
		1267	}
		1268
		1269	send = new dns_snd (this);
790	send->gen_stream_req (dns_sndseq, dns_snddq);	1270	send->gen_stream_req (sndseq, snddq);
		1271	send->timeout = NOW + min_latency * conf.dns_timeout_factor;
		1272
		1273	sndseq = (sndseq + 1) & SEQNO_MASK;
		1274	}
		1275	else
		1276	NEXT (last_sent + send_interval);
		1277	}
		1278
		1279	if (send)
791	vpn->dns_sndpq.push_back (send);	1280	vpn->dns_sndpq.push_back (send);
792
793	dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK;
794	}	1281	}
795
796	tstamp min_next = NOW + (1. / (tstamp)MAX_RATE);
797		1282
798	if (send)	1283	if (send)
799	{	1284	{
800	dns_packet *pkt = send->pkt;	1285	last_sent = NOW;
801		1286	sendto (vpn->dnsv4_fd,
802	next = min_next;	1287	send->pkt->at (0), send->pkt->len, 0,
803		1288	vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
804	sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ());
805	}	1289	}
806	else if (next < min_next)	1290
807	next = min_next;	1291	slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
		1292	poll_interval, send_interval, next - NOW,
		1293	vpn->dns_sndpq.size (), snddq.size (),
		1294	rcvpq.size ());
		1295
		1296	// TODO: no idea when this happens, but when next < NOW, we have a problem
		1297	// doesn't seem to happen anymore
		1298	if (next < NOW + 0.001)
		1299	next = NOW + 0.1;
808		1300
809	w.start (next);	1301	w.start (next);
810	}	1302	}
811		1303
812	#endif	1304	#endif

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