1 | /* |
1 | /* |
2 | vpn_dns.C -- handle the dns tunnel part of the protocol. |
2 | vpn_dns.C -- handle the dns tunnel part of the protocol. |
3 | Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> |
3 | Copyright (C) 2003-2011 Marc Lehmann <gvpe@schmorp.de> |
4 | |
4 | |
5 | This file is part of GVPE. |
5 | This file is part of GVPE. |
6 | |
6 | |
7 | GVPE is free software; you can redistribute it and/or modify |
7 | GVPE is free software; you can redistribute it and/or modify it |
8 | it under the terms of the GNU General Public License as published by |
8 | under the terms of the GNU General Public License as published by the |
9 | the Free Software Foundation; either version 2 of the License, or |
9 | Free Software Foundation; either version 3 of the License, or (at your |
10 | (at your option) any later version. |
10 | option) any later version. |
11 | |
11 | |
12 | This program is distributed in the hope that it will be useful, |
12 | This program is distributed in the hope that it will be useful, but |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General |
15 | GNU General Public License for more details. |
15 | 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 along |
18 | along with gvpe; if not, write to the Free Software |
18 | with this program; if not, see <http://www.gnu.org/licenses/>. |
19 | Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
19 | |
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20 | Additional permission under GNU GPL version 3 section 7 |
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21 | |
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22 | If you modify this Program, or any covered work, by linking or |
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23 | combining it with the OpenSSL project's OpenSSL library (or a modified |
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24 | version of that library), containing parts covered by the terms of the |
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25 | OpenSSL or SSLeay licenses, the licensors of this Program grant you |
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26 | additional permission to convey the resulting work. Corresponding |
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27 | Source for a non-source form of such a combination shall include the |
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28 | source code for the parts of OpenSSL used as well as that of the |
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29 | covered work. |
20 | */ |
30 | */ |
21 | |
31 | |
22 | // TODO: EDNS0 option to increase dns mtu? |
32 | // TODO: EDNS0 option to increase dns mtu? |
23 | // TODO: re-write dns packet parsing/creation using a safe mem-buffer |
33 | // TODO: re-write dns packet parsing/creation using a safe mem-buffer |
24 | // to ensure no buffer overflows or similar problems. |
34 | // to ensure no buffer overflows or similar problems. |
… | |
… | |
49 | |
59 | |
50 | #include "netcompat.h" |
60 | #include "netcompat.h" |
51 | |
61 | |
52 | #include "vpn.h" |
62 | #include "vpn.h" |
53 | |
63 | |
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64 | #define MIN_POLL_INTERVAL 0.1 // poll at most this often when no data received |
54 | #define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data |
65 | #define MAX_POLL_INTERVAL 1. // how often to poll minimally when the server has no data |
55 | #define ACTIVITY_INTERVAL 5. |
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56 | |
66 | |
57 | #define INITIAL_TIMEOUT 0.1 // retry timeouts |
67 | #define INITIAL_TIMEOUT 0.1 // retry timeouts |
58 | #define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn |
68 | #define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn |
59 | |
69 | |
60 | #define MAX_SEND_INTERVAL 2. // optimistic? |
70 | #define MAX_SEND_INTERVAL 2. // optimistic? |
… | |
… | |
73 | #define MAX_PKT_SIZE 512 |
83 | #define MAX_PKT_SIZE 512 |
74 | |
84 | |
75 | #define RR_TYPE_A 1 |
85 | #define RR_TYPE_A 1 |
76 | #define RR_TYPE_NULL 10 |
86 | #define RR_TYPE_NULL 10 |
77 | #define RR_TYPE_TXT 16 |
87 | #define RR_TYPE_TXT 16 |
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88 | #define RR_TYPE_AAAA 28 |
78 | #define RR_TYPE_ANY 255 |
89 | #define RR_TYPE_ANY 255 |
79 | |
90 | |
80 | #define RR_CLASS_IN 1 |
91 | #define RR_CLASS_IN 1 |
81 | |
92 | |
82 | #define CMD_IP_1 207 |
93 | #define CMD_IP_1 207 |
83 | #define CMD_IP_2 46 |
94 | #define CMD_IP_2 46 |
84 | #define CMD_IP_3 236 |
95 | #define CMD_IP_3 236 |
85 | #define CMD_IP_RST 29 |
96 | |
86 | #define CMD_IP_SYN 113 |
97 | #define CMD_IP_RST 29 // some error, reset and retry |
87 | #define CMD_IP_REJ 32 |
98 | #define CMD_IP_REJ 32 // do not want you |
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99 | #define CMD_IP_SYN 113 // connection established |
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100 | #define CMD_IP_CSE 213 // connection established, but likely case mismatch |
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101 | |
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102 | static bool |
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103 | is_uc (char c) |
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104 | { |
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105 | return 'A' <= c && c <= 'Z'; |
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106 | } |
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107 | |
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108 | static bool |
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109 | is_lc (char c) |
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110 | { |
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111 | return 'a' <= c && c <= 'z'; |
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112 | } |
88 | |
113 | |
89 | // works for cmaps up to 255 (not 256!) |
114 | // works for cmaps up to 255 (not 256!) |
90 | struct charmap |
115 | struct charmap |
91 | { |
116 | { |
92 | enum { INVALID = (u8)255 }; |
117 | enum { INVALID = (u8)255 }; |
… | |
… | |
106 | memset (enc, (char) 0, 256); |
131 | memset (enc, (char) 0, 256); |
107 | memset (dec, (char)INVALID, 256); |
132 | memset (dec, (char)INVALID, 256); |
108 | |
133 | |
109 | for (size = 0; cmap [size]; size++) |
134 | for (size = 0; cmap [size]; size++) |
110 | { |
135 | { |
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136 | char c = cmap [size]; |
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137 | |
111 | enc [size] = cmap [size]; |
138 | enc [size] = c; |
112 | dec [(u8)enc [size]] = size; |
139 | dec [(u8)c] = size; |
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140 | |
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141 | // allow lowercase/uppercase aliases if possible |
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142 | if (is_uc (c) && dec [c + ('a' - 'A')] == INVALID) dec [c + ('a' - 'A')] = size; |
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143 | if (is_lc (c) && dec [c - ('a' - 'A')] == INVALID) dec [c - ('a' - 'A')] = size; |
113 | } |
144 | } |
114 | |
145 | |
115 | assert (size < 256); |
146 | assert (size < 256); |
116 | } |
147 | } |
117 | |
148 | |
… | |
… | |
124 | { |
155 | { |
125 | charmap cmap; |
156 | charmap cmap; |
126 | unsigned int enc_len [MAX_DEC_LEN]; |
157 | unsigned int enc_len [MAX_DEC_LEN]; |
127 | unsigned int dec_len [MAX_ENC_LEN]; |
158 | unsigned int dec_len [MAX_ENC_LEN]; |
128 | |
159 | |
129 | unsigned int encode_len (unsigned int len); |
160 | unsigned int encode_len (unsigned int len) const; |
130 | unsigned int decode_len (unsigned int len); |
161 | unsigned int decode_len (unsigned int len) const; |
131 | |
162 | |
132 | unsigned int encode (char *dst, u8 *src, unsigned int len); |
163 | unsigned int encode (char *dst, u8 *src, unsigned int len) const; |
133 | unsigned int decode (u8 *dst, char *src, unsigned int len); |
164 | unsigned int decode (u8 *dst, char *src, unsigned int len) const; |
134 | |
165 | |
135 | basecoder (const char *cmap); |
166 | basecoder (const char *cmap); |
136 | }; |
167 | }; |
137 | |
168 | |
138 | basecoder::basecoder (const char *cmap) |
169 | basecoder::basecoder (const char *cmap) |
… | |
… | |
157 | enc_len [len] = n; |
188 | enc_len [len] = n; |
158 | dec_len [n] = len; |
189 | dec_len [n] = len; |
159 | } |
190 | } |
160 | } |
191 | } |
161 | |
192 | |
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193 | unsigned int |
162 | unsigned int basecoder::encode_len (unsigned int len) |
194 | basecoder::encode_len (unsigned int len) const |
163 | { |
195 | { |
164 | return enc_len [len]; |
196 | return enc_len [len]; |
165 | } |
197 | } |
166 | |
198 | |
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199 | unsigned int |
167 | unsigned int basecoder::decode_len (unsigned int len) |
200 | basecoder::decode_len (unsigned int len) const |
168 | { |
201 | { |
169 | while (len && !dec_len [len]) |
202 | while (len && !dec_len [len]) |
170 | --len; |
203 | --len; |
171 | |
204 | |
172 | return dec_len [len]; |
205 | return dec_len [len]; |
173 | } |
206 | } |
174 | |
207 | |
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208 | unsigned int |
175 | unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) |
209 | basecoder::encode (char *dst, u8 *src, unsigned int len) const |
176 | { |
210 | { |
177 | if (!len || len > MAX_DEC_LEN) |
211 | if (!len || len > MAX_DEC_LEN) |
178 | return 0; |
212 | return 0; |
179 | |
213 | |
180 | int elen = encode_len (len); |
214 | int elen = encode_len (len); |
… | |
… | |
199 | *dst++ = cmap.encode [dst_ [i]]; |
233 | *dst++ = cmap.encode [dst_ [i]]; |
200 | |
234 | |
201 | return elen; |
235 | return elen; |
202 | } |
236 | } |
203 | |
237 | |
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238 | unsigned int |
204 | unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) |
239 | basecoder::decode (u8 *dst, char *src, unsigned int len) const |
205 | { |
240 | { |
206 | if (!len || len > MAX_ENC_LEN) |
241 | if (!len || len > MAX_ENC_LEN) |
207 | return 0; |
242 | return 0; |
208 | |
243 | |
209 | u8 src_ [MAX_ENC_LEN]; |
244 | u8 src_ [MAX_ENC_LEN]; |
… | |
… | |
258 | } |
293 | } |
259 | abort (); |
294 | abort (); |
260 | } |
295 | } |
261 | #endif |
296 | #endif |
262 | |
297 | |
263 | //static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-"); |
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264 | //static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
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265 | static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
298 | static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); // a-zA-Z0-9 |
266 | //static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet |
299 | static basecoder cdc36 ("dPhZr06QmJkB34tSvL81xAeF92wGyO57uCnI"); // a-z0-9 for case-changers |
267 | static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); |
300 | static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyOuCnI"); // a-z |
268 | |
301 | |
269 | ///////////////////////////////////////////////////////////////////////////// |
302 | ///////////////////////////////////////////////////////////////////////////// |
270 | |
303 | |
271 | #define HDRSIZE 6 |
304 | #define HDRSIZE 5 |
272 | |
305 | |
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306 | inline void |
273 | inline void encode_header (char *data, int clientid, int seqno, int retry = 0) |
307 | encode_header (char *data, int clientid, int seqno, int retry = 0) |
274 | { |
308 | { |
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309 | assert (clientid < 256); |
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310 | |
275 | seqno &= SEQNO_MASK; |
311 | seqno &= SEQNO_MASK; |
276 | |
312 | |
277 | u8 hdr[3] = { |
313 | u8 hdr[3] = { |
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314 | seqno, |
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315 | (seqno >> 8) | (retry << 6), |
278 | clientid, |
316 | clientid, |
279 | (seqno >> 8) | (retry << 6), |
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280 | seqno, |
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281 | }; |
317 | }; |
282 | |
318 | |
283 | assert (clientid < 256); |
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284 | |
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285 | cdc26.encode (data, hdr, 3); |
319 | cdc36.encode (data, hdr, 3); |
286 | } |
320 | } |
287 | |
321 | |
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322 | inline void |
288 | inline void decode_header (char *data, int &clientid, int &seqno) |
323 | decode_header (char *data, int &clientid, int &seqno) |
289 | { |
324 | { |
290 | u8 hdr[3]; |
325 | u8 hdr[3]; |
291 | |
326 | |
292 | cdc26.decode (hdr, data, HDRSIZE); |
327 | cdc36.decode (hdr, data, HDRSIZE); |
293 | |
328 | |
294 | clientid = hdr[0]; |
329 | clientid = hdr[2]; |
295 | seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK; |
330 | seqno = ((hdr[1] << 8) | hdr[0]) & SEQNO_MASK; |
296 | } |
331 | } |
297 | |
332 | |
298 | ///////////////////////////////////////////////////////////////////////////// |
333 | ///////////////////////////////////////////////////////////////////////////// |
299 | |
334 | |
300 | struct byte_stream |
335 | struct byte_stream |
… | |
… | |
326 | byte_stream::~byte_stream () |
361 | byte_stream::~byte_stream () |
327 | { |
362 | { |
328 | delete data; |
363 | delete data; |
329 | } |
364 | } |
330 | |
365 | |
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366 | void |
331 | void byte_stream::remove (int count) |
367 | byte_stream::remove (int count) |
332 | { |
368 | { |
333 | if (count > fill) |
369 | if (count > fill) |
334 | assert (count <= fill); |
370 | assert (count <= fill); |
335 | |
371 | |
336 | memmove (data, data + count, fill -= count); |
372 | memmove (data, data + count, fill -= count); |
337 | } |
373 | } |
338 | |
374 | |
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375 | bool |
339 | bool byte_stream::put (u8 *data, unsigned int datalen) |
376 | byte_stream::put (u8 *data, unsigned int datalen) |
340 | { |
377 | { |
341 | if (maxsize - fill < datalen) |
378 | if (maxsize - fill < datalen) |
342 | return false; |
379 | return false; |
343 | |
380 | |
344 | memcpy (this->data + fill, data, datalen); fill += datalen; |
381 | memcpy (this->data + fill, data, datalen); fill += datalen; |
345 | |
382 | |
346 | return true; |
383 | return true; |
347 | } |
384 | } |
348 | |
385 | |
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386 | bool |
349 | bool byte_stream::put (vpn_packet *pkt) |
387 | byte_stream::put (vpn_packet *pkt) |
350 | { |
388 | { |
351 | if (maxsize - fill < pkt->len + 2) |
389 | if (maxsize - fill < pkt->len + 2) |
352 | return false; |
390 | return false; |
353 | |
391 | |
354 | data [fill++] = pkt->len >> 8; |
392 | data [fill++] = pkt->len >> 8; |
… | |
… | |
410 | |
448 | |
411 | struct dns_cfg |
449 | struct dns_cfg |
412 | { |
450 | { |
413 | static int next_uid; |
451 | static int next_uid; |
414 | |
452 | |
415 | u8 id1, id2, id3, id4; |
453 | u8 chksum; |
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454 | u8 rrtype; |
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455 | u16 uid; // to make request unique |
416 | |
456 | |
417 | u8 version; |
457 | u8 version; |
418 | u8 flags; |
458 | u8 flags; |
419 | u8 rrtype; |
459 | u16 max_size; |
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460 | |
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461 | u8 id1, id2, id3, id4; |
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462 | |
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463 | u16 client; |
420 | u8 def_ttl; |
464 | u8 def_ttl; |
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465 | u8 r0; |
421 | |
466 | |
422 | u16 client; |
467 | u8 syn_cdc; // cdc en/decoder for syn (A?) requests |
423 | u16 uid; // to make request unique |
468 | u8 hdr_cdc; // cdc en/decoder for regular request headers |
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469 | u8 req_cdc; // cdc en/decoder for regular (ANY?) request data |
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470 | u8 rep_cdc; // cdc en/decoder for regular (TXT) replies, 0 == 8 bit encoding |
424 | |
471 | |
425 | u16 max_size; |
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426 | u8 seq_cdc; |
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427 | u8 req_cdc; |
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428 | |
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429 | u8 rep_cdc; |
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430 | u8 delay; // time in 0.01s units that the server may delay replying packets |
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431 | u8 r3, r4; |
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432 | |
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433 | u8 r5, r6, r7, r8; |
472 | u8 r1, r2, r3, r4; |
434 | |
473 | |
435 | void reset (int clientid); |
474 | void reset (int clientid); |
436 | bool valid (); |
475 | bool valid (); |
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476 | u8 get_chksum (); |
437 | }; |
477 | }; |
438 | |
478 | |
439 | int dns_cfg::next_uid; |
479 | int dns_cfg::next_uid; |
440 | |
480 | |
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481 | void |
441 | void dns_cfg::reset (int clientid) |
482 | dns_cfg::reset (int clientid) |
442 | { |
483 | { |
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484 | // this ID must result in some mixed-case characters in cdc26-encoding |
443 | id1 = 'G'; |
485 | id1 = 'G'; |
444 | id2 = 'V'; |
486 | id2 = 'V'; |
445 | id3 = 'P'; |
487 | id3 = 'P'; |
446 | id4 = 'E'; |
488 | id4 = 'E'; |
447 | |
489 | |
448 | version = 1; |
490 | version = 2; |
449 | |
491 | |
450 | rrtype = RR_TYPE_TXT; |
492 | rrtype = RR_TYPE_TXT; |
451 | flags = 0; |
493 | flags = 0; |
452 | def_ttl = 0; |
494 | def_ttl = 0; |
453 | seq_cdc = 26; |
495 | syn_cdc = 26; |
454 | req_cdc = 62; |
496 | hdr_cdc = 36; |
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497 | req_cdc = conf.dns_case_preserving ? 62 : 36; |
455 | rep_cdc = 0; |
498 | rep_cdc = 0; |
456 | max_size = htons (MAX_PKT_SIZE); |
499 | max_size = htons (MAX_PKT_SIZE); |
457 | client = htons (clientid); |
500 | client = htons (clientid); |
458 | uid = next_uid++; |
501 | uid = ++next_uid; |
459 | delay = 0; |
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460 | |
502 | |
461 | r3 = r4 = 0; |
503 | r0 = r1 = r2 = r3 = r4 = 0; |
462 | r4 = r5 = r6 = r7 = 0; |
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463 | } |
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464 | |
504 | |
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505 | chksum = get_chksum (); |
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506 | } |
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507 | |
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508 | // simple but not trivial chksum |
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509 | u8 |
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510 | dns_cfg::get_chksum () |
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511 | { |
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512 | unsigned int sum = 0xff00; // only 16 bits required |
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513 | |
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514 | u8 old_chksum = chksum; |
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515 | chksum = 0; |
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516 | |
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517 | for (unsigned int i = 0; i < sizeof (*this); ++i) |
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518 | sum += ((u8 *)this)[i] * (i + 1); |
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519 | |
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520 | chksum = old_chksum; |
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521 | |
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522 | return sum + (sum >> 8); |
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523 | } |
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524 | |
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525 | bool |
465 | bool dns_cfg::valid () |
526 | dns_cfg::valid () |
466 | { |
527 | { |
467 | // although the protocol itself allows for some configurability, |
528 | // although the protocol itself allows for some configurability, |
468 | // only the following encoding/decoding settings are implemented. |
529 | // only the following encoding/decoding settings are implemented. |
469 | return id1 == 'G' |
530 | return id1 == 'G' |
470 | && id2 == 'V' |
531 | && id2 == 'V' |
471 | && id3 == 'P' |
532 | && id3 == 'P' |
472 | && id4 == 'E' |
533 | && id4 == 'E' |
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534 | && version == 2 |
473 | && seq_cdc == 26 |
535 | && syn_cdc == 26 |
474 | && req_cdc == 62 |
536 | && hdr_cdc == 36 |
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537 | && (req_cdc == 36 || req_cdc == 62) |
475 | && rep_cdc == 0 |
538 | && rep_cdc == 0 |
476 | && version == 1; |
539 | && chksum == get_chksum (); |
477 | } |
540 | } |
478 | |
541 | |
479 | struct dns_packet : net_packet |
542 | struct dns_packet : net_packet |
480 | { |
543 | { |
481 | u16 id; |
544 | u16 id; |
… | |
… | |
485 | u8 data [MAXSIZE - 6 * 2]; |
548 | u8 data [MAXSIZE - 6 * 2]; |
486 | |
549 | |
487 | int decode_label (char *data, int size, int &offs); |
550 | int decode_label (char *data, int size, int &offs); |
488 | }; |
551 | }; |
489 | |
552 | |
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553 | int |
490 | int dns_packet::decode_label (char *data, int size, int &offs) |
554 | dns_packet::decode_label (char *data, int size, int &offs) |
491 | { |
555 | { |
492 | char *orig = data; |
556 | char *orig = data; |
493 | |
557 | |
494 | memset (data, 0, size); |
558 | memset (data, 0, size); |
495 | |
559 | |
… | |
… | |
521 | return data - orig; |
585 | return data - orig; |
522 | } |
586 | } |
523 | |
587 | |
524 | ///////////////////////////////////////////////////////////////////////////// |
588 | ///////////////////////////////////////////////////////////////////////////// |
525 | |
589 | |
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590 | static |
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591 | u16 next_id () |
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592 | { |
526 | static u16 dns_id = 0; // TODO: should be per-vpn |
593 | static u16 dns_id = 0; // TODO: should be per-vpn |
527 | |
594 | |
528 | static u16 next_id () |
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529 | { |
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530 | if (!dns_id) |
595 | if (!dns_id) |
531 | dns_id = time (0); |
596 | dns_id = time (0); |
532 | |
597 | |
533 | // the simplest lsfr with periodicity 65535 i could find |
598 | // the simplest lsfr with periodicity 65535 i could find |
534 | dns_id = (dns_id << 1) |
599 | dns_id = (dns_id << 1) |
… | |
… | |
549 | struct vpn *vpn; |
614 | struct vpn *vpn; |
550 | |
615 | |
551 | dns_cfg cfg; |
616 | dns_cfg cfg; |
552 | |
617 | |
553 | bool established; |
618 | bool established; |
|
|
619 | const basecoder *cdc; |
554 | |
620 | |
555 | tstamp last_received; |
621 | tstamp last_received; |
556 | tstamp last_sent; |
622 | tstamp last_sent; |
557 | double min_latency; |
623 | double min_latency; |
558 | double poll_interval, send_interval; |
624 | double poll_interval, send_interval; |
… | |
… | |
560 | vector<dns_rcv *> rcvpq; |
626 | vector<dns_rcv *> rcvpq; |
561 | |
627 | |
562 | byte_stream rcvdq; int rcvseq; int repseq; |
628 | byte_stream rcvdq; int rcvseq; int repseq; |
563 | byte_stream snddq; int sndseq; |
629 | byte_stream snddq; int sndseq; |
564 | |
630 | |
565 | void time_cb (ev::timer &w, int revents); ev::timer tw; |
631 | inline void time_cb (ev::timer &w, int revents); ev::timer tw; |
566 | void receive_rep (dns_rcv *r); |
632 | void receive_rep (dns_rcv *r); |
|
|
633 | |
|
|
634 | void reset (); // quite like tcp RST |
|
|
635 | void set_cfg (); // to be called after any cfg changes |
567 | |
636 | |
568 | dns_connection (connection *c); |
637 | dns_connection (connection *c); |
569 | ~dns_connection (); |
638 | ~dns_connection (); |
570 | }; |
639 | }; |
571 | |
640 | |
… | |
… | |
602 | dns_snd::~dns_snd () |
671 | dns_snd::~dns_snd () |
603 | { |
672 | { |
604 | delete pkt; |
673 | delete pkt; |
605 | } |
674 | } |
606 | |
675 | |
|
|
676 | static void |
607 | static void append_domain (dns_packet &pkt, int &offs, const char *domain) |
677 | append_domain (dns_packet &pkt, int &offs, const char *domain) |
608 | { |
678 | { |
609 | // add tunnel domain |
679 | // add tunnel domain |
610 | for (;;) |
680 | for (;;) |
611 | { |
681 | { |
612 | const char *end = strchr (domain, '.'); |
682 | const char *end = strchr (domain, '.'); |
… | |
… | |
625 | |
695 | |
626 | domain = end + 1; |
696 | domain = end + 1; |
627 | } |
697 | } |
628 | } |
698 | } |
629 | |
699 | |
|
|
700 | void |
630 | void dns_snd::gen_stream_req (int seqno, byte_stream &stream) |
701 | dns_snd::gen_stream_req (int seqno, byte_stream &stream) |
631 | { |
702 | { |
632 | stdhdr = true; |
703 | stdhdr = true; |
633 | this->seqno = seqno; |
704 | this->seqno = seqno; |
634 | |
705 | |
635 | timeout = ev_now () + INITIAL_TIMEOUT; |
706 | timeout = ev_now () + INITIAL_TIMEOUT; |
… | |
… | |
643 | // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra |
714 | // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra |
644 | |
715 | |
645 | char enc[256], *encp = enc; |
716 | char enc[256], *encp = enc; |
646 | encode_header (enc, THISNODE->id, seqno); |
717 | encode_header (enc, THISNODE->id, seqno); |
647 | |
718 | |
648 | int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); |
719 | int datalen = dns->cdc->decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); |
649 | |
720 | |
650 | if (datalen > stream.size ()) |
721 | if (datalen > stream.size ()) |
651 | datalen = stream.size (); |
722 | datalen = stream.size (); |
652 | |
723 | |
653 | int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; |
724 | int enclen = dns->cdc->encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; |
654 | stream.remove (datalen); |
725 | stream.remove (datalen); |
655 | |
726 | |
656 | while (enclen) |
727 | while (enclen) |
657 | { |
728 | { |
658 | int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; |
729 | int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; |
… | |
… | |
673 | (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
744 | (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
674 | |
745 | |
675 | pkt->len = offs; |
746 | pkt->len = offs; |
676 | } |
747 | } |
677 | |
748 | |
|
|
749 | void |
678 | void dns_snd::gen_syn_req () |
750 | dns_snd::gen_syn_req () |
679 | { |
751 | { |
680 | timeout = ev_now () + INITIAL_SYN_TIMEOUT; |
752 | timeout = ev_now () + INITIAL_SYN_TIMEOUT; |
681 | |
753 | |
682 | pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
754 | pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
683 | pkt->qdcount = htons (1); |
755 | pkt->qdcount = htons (1); |
… | |
… | |
725 | |
797 | |
726 | dns_connection::dns_connection (connection *c) |
798 | dns_connection::dns_connection (connection *c) |
727 | : c (c) |
799 | : c (c) |
728 | , rcvdq (MAX_BACKLOG * 2) |
800 | , rcvdq (MAX_BACKLOG * 2) |
729 | , snddq (MAX_BACKLOG) |
801 | , snddq (MAX_BACKLOG) |
730 | , tw (this, &dns_connection::time_cb) |
|
|
731 | { |
802 | { |
|
|
803 | tw.set<dns_connection, &dns_connection::time_cb> (this); |
|
|
804 | |
732 | vpn = c->vpn; |
805 | vpn = c->vpn; |
|
|
806 | |
|
|
807 | reset (); |
|
|
808 | } |
|
|
809 | |
|
|
810 | dns_connection::~dns_connection () |
|
|
811 | { |
|
|
812 | reset (); |
|
|
813 | } |
|
|
814 | |
|
|
815 | void |
|
|
816 | dns_connection::reset () |
|
|
817 | { |
|
|
818 | while (!rcvpq.empty ()) |
|
|
819 | { |
|
|
820 | delete rcvpq.back (); |
|
|
821 | rcvpq.pop_back (); |
|
|
822 | } |
|
|
823 | |
|
|
824 | for (int i = vpn->dns_sndpq.size (); i--; ) |
|
|
825 | if (vpn->dns_sndpq [i]->dns == this) |
|
|
826 | { |
|
|
827 | vpn->dns_sndpq [i] = vpn->dns_sndpq.back (); |
|
|
828 | vpn->dns_sndpq.pop_back (); |
|
|
829 | } |
733 | |
830 | |
734 | established = false; |
831 | established = false; |
735 | |
832 | |
736 | rcvseq = repseq = sndseq = 0; |
833 | rcvseq = repseq = sndseq = 0; |
737 | |
834 | |
… | |
… | |
739 | poll_interval = 0.5; // starting here |
836 | poll_interval = 0.5; // starting here |
740 | send_interval = 0.5; // starting rate |
837 | send_interval = 0.5; // starting rate |
741 | min_latency = INITIAL_TIMEOUT; |
838 | min_latency = INITIAL_TIMEOUT; |
742 | } |
839 | } |
743 | |
840 | |
744 | dns_connection::~dns_connection () |
841 | void |
|
|
842 | dns_connection::set_cfg () |
745 | { |
843 | { |
746 | for (vector<dns_rcv *>::iterator i = rcvpq.begin (); |
844 | cdc = cfg.req_cdc == 36 ? &cdc36 : &cdc62; |
747 | i != rcvpq.end (); |
|
|
748 | ++i) |
|
|
749 | delete *i; |
|
|
750 | } |
845 | } |
751 | |
846 | |
|
|
847 | void |
752 | void dns_connection::receive_rep (dns_rcv *r) |
848 | dns_connection::receive_rep (dns_rcv *r) |
753 | { |
849 | { |
754 | if (r->datalen) |
850 | if (r->datalen) |
755 | { |
851 | { |
756 | last_received = ev_now (); |
852 | last_received = ev_now (); |
757 | tw (); |
853 | tw (); |
… | |
… | |
790 | |
886 | |
791 | rcvseq = (rcvseq + 1) & SEQNO_MASK; |
887 | rcvseq = (rcvseq + 1) & SEQNO_MASK; |
792 | |
888 | |
793 | if (!rcvdq.put (r->data, r->datalen)) |
889 | if (!rcvdq.put (r->data, r->datalen)) |
794 | { |
890 | { |
|
|
891 | // MUST never overflow, can be caused by data corruption, TODO |
795 | slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)"); |
892 | slog (L_CRIT, "DNS: !rcvdq.put (r->data, r->datalen)"); |
796 | abort (); // MUST never overflow, can be caused by data corruption, TODO |
893 | reset (); |
|
|
894 | return; |
797 | } |
895 | } |
798 | |
896 | |
799 | while (vpn_packet *pkt = rcvdq.get ()) |
897 | while (vpn_packet *pkt = rcvdq.get ()) |
800 | { |
898 | { |
801 | sockinfo si; |
899 | sockinfo si; |
802 | si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4; |
900 | si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4; |
803 | |
901 | |
804 | vpn->recv_vpn_packet (pkt, si); |
902 | vpn->recv_vpn_packet (pkt, si); |
805 | |
|
|
806 | delete pkt; |
903 | delete pkt; |
807 | } |
904 | } |
808 | |
905 | |
809 | // check for further packets |
906 | // check for further packets |
810 | goto redo; |
907 | goto redo; |
… | |
… | |
853 | { |
950 | { |
854 | // correct class, domain: parse |
951 | // correct class, domain: parse |
855 | int client, seqno; |
952 | int client, seqno; |
856 | decode_header (qname, client, seqno); |
953 | decode_header (qname, client, seqno); |
857 | |
954 | |
858 | u8 data[MAXSIZE]; |
|
|
859 | int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); |
|
|
860 | |
|
|
861 | if (0 < client && client <= conns.size ()) |
955 | if (0 < client && client <= conns.size ()) |
862 | { |
956 | { |
863 | connection *c = conns [client - 1]; |
957 | connection *c = conns [client - 1]; |
864 | dns_connection *dns = c->dns; |
958 | dns_connection *dns = c->dns; |
865 | dns_rcv *rcv; |
959 | dns_rcv *rcv; |
866 | |
960 | |
867 | if (dns) |
961 | if (dns) |
868 | { |
962 | { |
|
|
963 | u8 data[MAXSIZE]; |
|
|
964 | int datalen = dns->cdc->decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); |
|
|
965 | |
869 | for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) |
966 | for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) |
870 | if (SEQNO_EQ ((*i)->seqno, seqno)) |
967 | if (SEQNO_EQ ((*i)->seqno, seqno)) |
871 | { |
968 | { |
872 | // already seen that request: simply reply with the cached reply |
969 | // already seen that request: simply reply with the cached reply |
873 | dns_rcv *r = *i; |
970 | dns_rcv *r = *i; |
… | |
… | |
974 | pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
1071 | pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
975 | pkt [offs++] = 0; pkt [offs++] = 0; |
1072 | pkt [offs++] = 0; pkt [offs++] = 0; |
976 | pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL |
1073 | pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL |
977 | pkt [offs++] = 0; pkt [offs++] = 4; // rdlength |
1074 | pkt [offs++] = 0; pkt [offs++] = 4; // rdlength |
978 | |
1075 | |
979 | slog (L_INFO, _("DNS: client %d connects"), client); |
|
|
980 | |
|
|
981 | pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
1076 | pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
982 | pkt [offs++] = CMD_IP_REJ; |
1077 | pkt [offs++] = CMD_IP_REJ; |
983 | |
1078 | |
984 | if (0 < client && client <= conns.size ()) |
1079 | if (0 < client && client <= conns.size ()) |
985 | { |
1080 | { |
986 | connection *c = conns [client - 1]; |
1081 | connection *c = conns [client - 1]; |
987 | |
1082 | |
988 | if (cfg.valid ()) |
1083 | if (cfg.valid ()) |
989 | { |
1084 | { |
990 | pkt [offs - 1] = CMD_IP_SYN; |
1085 | slog (L_INFO, _("DNS: client %d connects (version %d, req_cdc %d)"), client, cfg.version, cfg.req_cdc); |
|
|
1086 | |
|
|
1087 | // check for any encoding mismatches - hints at a case problem |
|
|
1088 | char qname2 [MAX_ENC_LEN]; |
|
|
1089 | cdc26.encode (qname2, (u8 *)&cfg, sizeof (dns_cfg)); |
991 | |
1090 | |
992 | delete c->dns; |
1091 | delete c->dns; |
|
|
1092 | |
|
|
1093 | pkt [offs - 1] = memcmp (qname, qname2, cdc26.encode_len (sizeof (dns_cfg))) |
|
|
1094 | ? CMD_IP_CSE : CMD_IP_SYN; |
|
|
1095 | |
993 | c->dns = new dns_connection (c); |
1096 | c->dns = new dns_connection (c); |
994 | c->dns->cfg = cfg; |
1097 | c->dns->cfg = cfg; |
|
|
1098 | c->dns->set_cfg (); |
995 | } |
1099 | } |
996 | } |
1100 | } |
997 | } |
1101 | } |
998 | } |
1102 | } |
999 | |
1103 | |
… | |
… | |
1019 | dns_connection *dns = (*i)->dns; |
1123 | dns_connection *dns = (*i)->dns; |
1020 | connection *c = dns->c; |
1124 | connection *c = dns->c; |
1021 | int seqno = (*i)->seqno; |
1125 | int seqno = (*i)->seqno; |
1022 | u8 data[MAXSIZE], *datap = data; |
1126 | u8 data[MAXSIZE], *datap = data; |
1023 | //printf ("rcv pkt %x\n", seqno);//D |
1127 | //printf ("rcv pkt %x\n", seqno);//D |
|
|
1128 | bool back_off = (*i)->retry; |
1024 | |
1129 | |
1025 | if ((*i)->retry) |
1130 | if (back_off) |
1026 | { |
1131 | { |
1027 | dns->send_interval *= 1.01; |
1132 | dns->send_interval *= 1.01; |
1028 | if (dns->send_interval > MAX_SEND_INTERVAL) |
1133 | if (dns->send_interval > MAX_SEND_INTERVAL) |
1029 | dns->send_interval = MAX_SEND_INTERVAL; |
1134 | dns->send_interval = MAX_SEND_INTERVAL; |
1030 | } |
1135 | } |
… | |
… | |
1070 | ttl |= pkt [offs++] << 16; |
1175 | ttl |= pkt [offs++] << 16; |
1071 | ttl |= pkt [offs++] << 8; |
1176 | ttl |= pkt [offs++] << 8; |
1072 | ttl |= pkt [offs++]; |
1177 | ttl |= pkt [offs++]; |
1073 | u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; |
1178 | u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; |
1074 | |
1179 | |
1075 | if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) |
1180 | if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT || qtype == dns->cfg.rrtype) |
1076 | { |
1181 | { |
1077 | if (rdlen <= MAXSIZE - offs) |
1182 | if (rdlen <= MAXSIZE - offs) |
1078 | { |
1183 | { |
1079 | // decode bytes, finally |
1184 | // decode bytes, finally |
1080 | |
1185 | |
… | |
… | |
1106 | { |
1211 | { |
1107 | slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); |
1212 | slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); |
1108 | |
1213 | |
1109 | if (ip [3] == CMD_IP_RST) |
1214 | if (ip [3] == CMD_IP_RST) |
1110 | { |
1215 | { |
1111 | slog (L_DEBUG, _("DNS: got tunnel RST request")); |
1216 | slog (L_DEBUG, _("DNS: got tunnel RST request.")); |
1112 | |
1217 | |
1113 | delete dns; c->dns = 0; |
1218 | dns->reset (); |
1114 | |
|
|
1115 | return; |
1219 | return; |
1116 | } |
1220 | } |
1117 | else if (ip [3] == CMD_IP_SYN) |
1221 | else if (ip [3] == CMD_IP_SYN) |
1118 | { |
1222 | { |
1119 | slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); |
1223 | slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); |
1120 | dns->established = true; |
1224 | dns->established = true; |
1121 | } |
1225 | } |
|
|
1226 | else if (ip [3] == CMD_IP_CSE) |
|
|
1227 | { |
|
|
1228 | if (conf.dns_case_preserving) |
|
|
1229 | { |
|
|
1230 | slog (L_INFO, _("DNS: got tunnel CSE reply, globally downgrading to case-insensitive protocol.")); |
|
|
1231 | conf.dns_case_preserving = false; |
|
|
1232 | dns->reset (); |
|
|
1233 | return; |
|
|
1234 | } |
|
|
1235 | else |
|
|
1236 | { |
|
|
1237 | slog (L_DEBUG, _("DNS: got tunnel CSE reply, server likes us.")); |
|
|
1238 | dns->established = true; |
|
|
1239 | } |
|
|
1240 | } |
1122 | else if (ip [3] == CMD_IP_REJ) |
1241 | else if (ip [3] == CMD_IP_REJ) |
1123 | { |
1242 | { |
1124 | slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting.")); |
1243 | slog (L_ERR, _("DNS: got tunnel REJ reply, server does not like us.")); |
1125 | abort (); |
1244 | dns->tw.start (60.); |
1126 | } |
1245 | } |
1127 | else |
1246 | else |
|
|
1247 | { |
1128 | slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); |
1248 | slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); |
|
|
1249 | dns->tw.start (60.); |
|
|
1250 | } |
1129 | } |
1251 | } |
1130 | else |
1252 | else |
1131 | slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), |
1253 | slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), |
1132 | ip [0], ip [1], ip [2], ip [3]); |
1254 | ip [0], ip [1], ip [2], ip [3]); |
1133 | |
1255 | |
… | |
… | |
1151 | } |
1273 | } |
1152 | |
1274 | |
1153 | // todo: pkt now used |
1275 | // todo: pkt now used |
1154 | if (datap) |
1276 | if (datap) |
1155 | dns->receive_rep (new dns_rcv (seqno, data, datap - data)); |
1277 | dns->receive_rep (new dns_rcv (seqno, data, datap - data)); |
|
|
1278 | else if (dns_sndpq.empty ()) // no data received, and nothing to send - idle |
|
|
1279 | { |
|
|
1280 | dns->send_interval *= 1.1; |
|
|
1281 | |
|
|
1282 | if (dns->send_interval < MIN_POLL_INTERVAL) |
|
|
1283 | dns->send_interval = MIN_POLL_INTERVAL; |
|
|
1284 | |
|
|
1285 | if (dns->send_interval > MAX_POLL_INTERVAL && !back_off) |
|
|
1286 | dns->send_interval = MAX_POLL_INTERVAL; |
|
|
1287 | } |
1156 | |
1288 | |
1157 | break; |
1289 | break; |
1158 | } |
1290 | } |
1159 | } |
1291 | } |
1160 | |
1292 | |
… | |
… | |
1201 | |
1333 | |
1202 | // always return true even if the buffer overflows |
1334 | // always return true even if the buffer overflows |
1203 | return true; |
1335 | return true; |
1204 | } |
1336 | } |
1205 | |
1337 | |
1206 | void |
|
|
1207 | connection::dnsv4_reset_connection () |
|
|
1208 | { |
|
|
1209 | //delete dns; dns = 0; //TODO |
|
|
1210 | } |
|
|
1211 | |
|
|
1212 | #define NEXT(w) do { if (next > (w)) next = w; } while (0) |
1338 | #define NEXT(w) do { if (next > (w)) next = w; } while (0) |
1213 | |
1339 | |
1214 | void |
1340 | void |
1215 | dns_connection::time_cb (ev::timer &w, int revents) |
1341 | dns_connection::time_cb (ev::timer &w, int revents) |
1216 | { |
1342 | { |
… | |
… | |
1257 | if (vpn->dns_sndpq.empty ()) |
1383 | if (vpn->dns_sndpq.empty ()) |
1258 | { |
1384 | { |
1259 | send = new dns_snd (this); |
1385 | send = new dns_snd (this); |
1260 | |
1386 | |
1261 | cfg.reset (THISNODE->id); |
1387 | cfg.reset (THISNODE->id); |
|
|
1388 | set_cfg (); |
1262 | send->gen_syn_req (); |
1389 | send->gen_syn_req (); |
1263 | } |
1390 | } |
1264 | } |
1391 | } |
1265 | else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding |
1392 | else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding |
1266 | && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) |
1393 | && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) |