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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.7 by pcg, Thu Mar 3 16:54:34 2005 UTC vs.
Revision 1.39 by pcg, Tue Apr 26 00:55:56 2005 UTC

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

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