… | |
… | |
39 | |
39 | |
40 | #include "netcompat.h" |
40 | #include "netcompat.h" |
41 | |
41 | |
42 | #include "vpn.h" |
42 | #include "vpn.h" |
43 | |
43 | |
44 | #if ENABLE_HTTP_PROXY |
|
|
45 | # include "conf.h" |
|
|
46 | #endif |
|
|
47 | |
|
|
48 | #define MIN_RETRY 1. |
44 | #define MIN_RETRY 1. |
49 | #define MAX_RETRY 60. |
45 | #define MAX_RETRY 60. |
50 | |
46 | |
51 | #define SERVER conf.dns_port |
47 | #define MAX_OUTSTANDING 10 // max. outstanding requests |
52 | |
48 | |
53 | /* |
49 | /* |
54 | |
50 | |
55 | protocol, in shorthand :) |
51 | protocol, in shorthand :) |
56 | |
52 | |
57 | <cseqno> ANY? poll for more data |
53 | client -> server <req> ANY? |
58 | => TXT <sseqno><data> |
54 | server -> client <req> TXT <rep> |
59 | <cseqno><data> TXT? send more data |
|
|
60 | => TXT <empty> |
|
|
61 | |
55 | |
62 | sequence numbers are 12 bit, 9 bit packet-number and 3 bit fragment id (7 |
56 | <req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>] |
63 | - id, actually) last fragment is sent first, however |
57 | <rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>] |
|
|
58 | |
|
|
59 | if <client-id> is zero, the connection will be configured: |
|
|
60 | |
|
|
61 | <0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16> |
64 | |
62 | |
65 | */ |
63 | */ |
|
|
64 | |
|
|
65 | #define MAX_LBL_SIZE 63 |
|
|
66 | #define MAX_PKT_SIZE 512 |
|
|
67 | |
|
|
68 | #define RR_TYPE_TXT 16 |
|
|
69 | #define RR_TYPE_ANY 255 |
|
|
70 | #define RR_CLASS_IN 1 |
|
|
71 | |
|
|
72 | // the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) |
|
|
73 | struct dns64 |
|
|
74 | { |
|
|
75 | static const char encode_chars[64 + 1]; |
|
|
76 | static s8 decode_chars[256]; |
|
|
77 | |
|
|
78 | static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } |
|
|
79 | static int decode_len (int bytes) { return (bytes * 6) / 8; } |
|
|
80 | static void encode (char *dst, u8 *src, int len); |
|
|
81 | static void decode (u8 *dst, char *src, int len); |
|
|
82 | |
|
|
83 | dns64 (); |
|
|
84 | } dns64; |
|
|
85 | |
|
|
86 | const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ"; |
|
|
87 | s8 dns64::decode_chars[256]; |
|
|
88 | |
|
|
89 | dns64::dns64 () |
|
|
90 | { |
|
|
91 | for (int i = 0; i < 64; i++) |
|
|
92 | decode_chars [encode_chars [i]] = i + 1; |
|
|
93 | } |
|
|
94 | |
|
|
95 | void dns64::encode (char *dst, u8 *src, int len) |
|
|
96 | { |
|
|
97 | // slow, but easy to debug |
|
|
98 | unsigned int accum, bits = 0; |
|
|
99 | |
|
|
100 | while (len--) |
|
|
101 | { |
|
|
102 | accum <<= 8; |
|
|
103 | accum |= *src++; |
|
|
104 | bits += 8; |
|
|
105 | |
|
|
106 | while (bits >= 6) |
|
|
107 | { |
|
|
108 | *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; |
|
|
109 | bits -= 6; |
|
|
110 | } |
|
|
111 | } |
|
|
112 | |
|
|
113 | if (bits) |
|
|
114 | *dst++ = encode_chars [(accum << (6 - bits)) & 63]; |
|
|
115 | } |
|
|
116 | |
|
|
117 | void dns64::decode (u8 *dst, char *src, int len) |
|
|
118 | { |
|
|
119 | // slow, but easy to debug |
|
|
120 | unsigned int accum, bits = 0; |
|
|
121 | |
|
|
122 | while (len--) |
|
|
123 | { |
|
|
124 | s8 chr = decode_chars [(u8)*src++]; |
|
|
125 | |
|
|
126 | |
|
|
127 | if (!chr) |
|
|
128 | break; |
|
|
129 | |
|
|
130 | accum <<= 6; |
|
|
131 | accum |= chr - 1; |
|
|
132 | bits += 6; |
|
|
133 | |
|
|
134 | while (bits >= 8) |
|
|
135 | { |
|
|
136 | *dst++ = accum >> (bits - 8); |
|
|
137 | bits -= 8; |
|
|
138 | } |
|
|
139 | } |
|
|
140 | } |
|
|
141 | |
|
|
142 | ///////////////////////////////////////////////////////////////////////////// |
|
|
143 | |
|
|
144 | #define FLAG_QUERY ( 0 << 15) |
|
|
145 | #define FLAG_RESPONSE ( 1 << 15) |
|
|
146 | #define FLAG_OP_MASK (15 << 14) |
|
|
147 | #define FLAG_OP_QUERY ( 0 << 11) |
|
|
148 | #define FLAG_AA ( 1 << 10) |
|
|
149 | #define FLAG_TC ( 1 << 9) |
|
|
150 | #define FLAG_RD ( 1 << 8) |
|
|
151 | #define FLAG_RA ( 1 << 7) |
|
|
152 | #define FLAG_RCODE_MASK (15 << 0) |
|
|
153 | #define FLAG_RCODE_OK ( 0 << 0) |
|
|
154 | #define FLAG_RCODE_FORMERR ( 1 << 0) |
|
|
155 | #define FLAG_RCODE_SERVFAIL ( 2 << 0) |
|
|
156 | #define FLAG_RCODE_NXDOMAIN ( 3 << 0) |
|
|
157 | #define FLAG_RCODE_REFUSED ( 5 << 0) |
|
|
158 | |
|
|
159 | #define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) |
|
|
160 | #define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD) |
|
|
161 | |
|
|
162 | struct dns_packet : net_packet |
|
|
163 | { |
|
|
164 | u16 id; |
|
|
165 | u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 |
|
|
166 | u16 qdcount, ancount, nscount, arcount; |
|
|
167 | |
|
|
168 | u8 data[MAXSIZE - 6 * 2]; |
|
|
169 | |
|
|
170 | int decode_label (char *data, int size, int &offs); |
|
|
171 | }; |
|
|
172 | |
|
|
173 | int dns_packet::decode_label (char *data, int size, int &offs) |
|
|
174 | { |
|
|
175 | char *orig = data; |
|
|
176 | |
|
|
177 | memset (data, 0, size); |
|
|
178 | |
|
|
179 | while (offs < size - 1) |
|
|
180 | { |
|
|
181 | u8 len = (*this)[offs++]; |
|
|
182 | |
|
|
183 | if (!len) |
|
|
184 | break; |
|
|
185 | else if (len < 64) |
|
|
186 | { |
|
|
187 | if (size < len + 1 || offs + len >= MAXSIZE - 1) |
|
|
188 | break; |
|
|
189 | |
|
|
190 | memcpy (data, &((*this)[offs]), len); |
|
|
191 | |
|
|
192 | data += len; size -= len; offs += len; |
|
|
193 | *data++ = '.'; size--; |
|
|
194 | } |
|
|
195 | else |
|
|
196 | { |
|
|
197 | int offs2 = ((len & 63) << 8) + (*this)[offs++]; |
|
|
198 | |
|
|
199 | data += decode_label (data, size, offs2); |
|
|
200 | break; |
|
|
201 | } |
|
|
202 | } |
|
|
203 | |
|
|
204 | return data - orig; |
|
|
205 | } |
|
|
206 | |
|
|
207 | ///////////////////////////////////////////////////////////////////////////// |
|
|
208 | |
|
|
209 | struct dns_req |
|
|
210 | { |
|
|
211 | dns_packet *pkt; |
|
|
212 | tstamp next; |
|
|
213 | int retry; |
|
|
214 | |
|
|
215 | dns_req (connection *c, vpn_packet *p, int &offs); |
|
|
216 | }; |
|
|
217 | |
|
|
218 | struct dns_rep |
|
|
219 | { |
|
|
220 | }; |
|
|
221 | |
|
|
222 | static u16 dns_id; // TODO: should be per-vpn |
|
|
223 | |
|
|
224 | dns_req::dns_req (connection *c, vpn_packet *p, int &offs) |
|
|
225 | { |
|
|
226 | next = 0; |
|
|
227 | retry = 0; |
|
|
228 | |
|
|
229 | pkt = new dns_packet; |
|
|
230 | |
|
|
231 | pkt->id = dns_id++; |
|
|
232 | pkt->flags = DEFAULT_CLIENT_FLAGS; |
|
|
233 | pkt->qdcount = htons (1 * 0); |
|
|
234 | pkt->ancount = 0; |
|
|
235 | pkt->nscount = 0; |
|
|
236 | pkt->arcount = 0; |
|
|
237 | |
|
|
238 | offs += 10000; |
|
|
239 | |
|
|
240 | c->dns_sndq.push_back (this); |
|
|
241 | } |
|
|
242 | |
|
|
243 | ///////////////////////////////////////////////////////////////////////////// |
|
|
244 | |
|
|
245 | struct dns_cfg |
|
|
246 | { |
|
|
247 | u8 id1, id2, id3; |
|
|
248 | u8 def_ttl; |
|
|
249 | u8 unused1; |
|
|
250 | u16 max_size; |
|
|
251 | u8 flags1, flags2; |
|
|
252 | }; |
|
|
253 | |
|
|
254 | // reply to client-poll |
|
|
255 | void dnsv4_poll (dns_packet *pkt, int &offs) |
|
|
256 | { |
|
|
257 | int dlen = MAX_PKT_SIZE - offs - 2; |
|
|
258 | |
|
|
259 | (*pkt) [offs++] = 0; |
|
|
260 | (*pkt) [offs++] = 5; |
|
|
261 | memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5); |
|
|
262 | offs += 5; |
|
|
263 | |
|
|
264 | pkt->ancount = htons (1); |
|
|
265 | pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); |
|
|
266 | |
|
|
267 | printf ("we have room for %d bytes\n", dlen); |
|
|
268 | } |
66 | |
269 | |
67 | void |
270 | void |
68 | vpn::dnsv4_ev (io_watcher &w, short revents) |
271 | vpn::dnsv4_ev (io_watcher &w, short revents) |
69 | { |
272 | { |
70 | if (revents & EVENT_READ) |
273 | if (revents & EVENT_READ) |
71 | { |
274 | { |
|
|
275 | dns_packet *pkt = new dns_packet; |
72 | struct sockaddr_in sa; |
276 | struct sockaddr_in sa; |
73 | socklen_t sa_len = sizeof (sa); |
277 | socklen_t sa_len = sizeof (sa); |
74 | int len; |
278 | |
|
|
279 | int len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); |
|
|
280 | pkt->len = len; |
|
|
281 | |
|
|
282 | u16 flags = ntohs (pkt->flags); |
|
|
283 | |
|
|
284 | if (THISNODE->dns_port) |
|
|
285 | { |
|
|
286 | // server |
|
|
287 | pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
|
|
288 | |
|
|
289 | int offs = 6 * 2; // skip header |
|
|
290 | |
|
|
291 | if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) |
|
|
292 | && pkt->qdcount == htons (1)) |
|
|
293 | { |
|
|
294 | char qname[MAXSIZE]; |
|
|
295 | int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs); |
|
|
296 | |
|
|
297 | printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len, |
|
|
298 | pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D |
|
|
299 | |
|
|
300 | u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; |
|
|
301 | u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; |
|
|
302 | |
|
|
303 | pkt->qdcount = htons (1); |
|
|
304 | pkt->ancount = 0; |
|
|
305 | pkt->nscount = 0; // should be self, as other nameservers reply like this |
|
|
306 | pkt->arcount = 0; // a record for self, as other nameservers reply like this |
|
|
307 | |
|
|
308 | pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); |
|
|
309 | |
|
|
310 | int dlen = strlen (THISNODE->domain); |
|
|
311 | |
|
|
312 | if (qclass == RR_CLASS_IN |
|
|
313 | && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT) |
|
|
314 | && qlen > dlen + 1 |
|
|
315 | && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) |
|
|
316 | { |
|
|
317 | // correct class, now generate reply |
|
|
318 | pkt->ancount = htons (1); // one answer RR |
|
|
319 | |
|
|
320 | (*pkt) [offs++] = 0xc0; |
|
|
321 | (*pkt) [offs++] = 6 * 2; // same as in query section |
|
|
322 | |
|
|
323 | (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; |
|
|
324 | (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; |
|
|
325 | |
|
|
326 | (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; |
|
|
327 | (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL |
|
|
328 | |
|
|
329 | dnsv4_poll (pkt, offs); |
|
|
330 | printf ("correct class\n"); |
|
|
331 | } |
|
|
332 | } |
|
|
333 | |
|
|
334 | sendto (w.fd, &((*pkt)[0]), offs, 0, (sockaddr *)&sa, sa_len); |
|
|
335 | } |
|
|
336 | else |
|
|
337 | { |
|
|
338 | // client |
|
|
339 | } |
75 | } |
340 | } |
76 | } |
341 | } |
77 | |
342 | |
78 | bool |
343 | bool |
79 | vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
344 | connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
80 | { |
345 | { |
81 | //return i->send_packet (pkt, tos); |
346 | if (dns_sndq.size () >= MAX_OUTSTANDING) |
|
|
347 | return false; |
|
|
348 | |
|
|
349 | // split vpn packet into dns packets, add to sndq |
|
|
350 | for (int offs = 0; offs < pkt->len; ) |
|
|
351 | new dns_req (this, pkt, offs); |
|
|
352 | |
|
|
353 | // force transmit |
|
|
354 | dnsv4_cb (dnsv4_tw); |
|
|
355 | |
|
|
356 | return true; |
|
|
357 | } |
|
|
358 | |
|
|
359 | void |
|
|
360 | connection::dnsv4_cb (time_watcher &w) |
|
|
361 | { |
|
|
362 | // check for timeouts and (re)transmit |
|
|
363 | tstamp next = NOW + 60; |
|
|
364 | |
|
|
365 | slog (L_NOISE, _("dnsv4, %d packets in send queue\n"), dns_sndq.size ()); |
|
|
366 | |
|
|
367 | if (dns_sndq.empty ()) |
|
|
368 | { |
|
|
369 | next = NOW + 1; |
|
|
370 | // push poll packet |
|
|
371 | } |
|
|
372 | |
|
|
373 | for (vector<dns_req *>::iterator i = dns_sndq.begin (); |
|
|
374 | i != dns_sndq.end (); |
|
|
375 | ++i) |
|
|
376 | { |
|
|
377 | dns_req *r = *i; |
|
|
378 | |
|
|
379 | if (r->next <= NOW) |
|
|
380 | { |
|
|
381 | slog (L_NOISE, _("dnsv4, send req %d\n"), r->pkt->id); |
|
|
382 | r->retry++; |
|
|
383 | r->next = NOW + r->retry; |
|
|
384 | } |
|
|
385 | |
|
|
386 | if (r->next < next) |
|
|
387 | next = r->next; |
|
|
388 | } |
|
|
389 | |
|
|
390 | printf ("%f next\n", next); |
|
|
391 | w.start (next); |
82 | } |
392 | } |
83 | |
393 | |
84 | #endif |
394 | #endif |
85 | |
395 | |