1 |
/* |
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vpn_dns.C -- handle the dns tunnel part of the protocol. |
3 |
Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> |
4 |
|
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This file is part of GVPE. |
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|
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GVPE is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with gvpe; if not, write to the Free Software |
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Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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*/ |
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|
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#include "config.h" |
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|
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#if ENABLE_DNS |
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|
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// dns processing is EXTREMELY ugly. For obvious(?) reasons. |
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// it's a hack, use only in emergency situations please. |
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|
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#include <cstring> |
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#include <cassert> |
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|
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#include <sys/types.h> |
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#include <sys/socket.h> |
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#include <sys/wait.h> |
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#include <sys/uio.h> |
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#include <errno.h> |
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#include <time.h> |
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#include <unistd.h> |
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#include <fcntl.h> |
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|
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#include <map> |
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|
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#include <gmp.h> |
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|
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#include "netcompat.h" |
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|
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#include "vpn.h" |
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|
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#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data |
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#define ACTIVITY_INTERVAL 5. |
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|
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#define TIMEOUT_FACTOR 2. |
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|
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#define INITIAL_TIMEOUT 0.1 // retry timeouts |
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#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn |
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|
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#define MIN_SEND_INTERVAL 0.001 // wait at least this time between sending requests |
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#define MAX_SEND_INTERVAL 2. // optimistic? |
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|
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#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate |
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#define MAX_OUTSTANDING 100 // max. outstanding requests |
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#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog |
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#define MAX_BACKLOG (32*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE |
64 |
|
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#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well |
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// 240 leaves about 4 bytes of server reply data |
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// every two request bytes less give room for one reply byte |
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|
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#define SEQNO_MASK 0x0fff |
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#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) |
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|
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#define MAX_LBL_SIZE 63 |
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#define MAX_PKT_SIZE 512 |
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|
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#define RR_TYPE_A 1 |
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#define RR_TYPE_NULL 10 |
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#define RR_TYPE_TXT 16 |
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#define RR_TYPE_ANY 255 |
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|
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#define RR_CLASS_IN 1 |
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|
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#define CMD_IP_1 207 |
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#define CMD_IP_2 46 |
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#define CMD_IP_3 236 |
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#define CMD_IP_RST 29 |
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#define CMD_IP_SYN 113 |
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#define CMD_IP_REJ 32 |
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|
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// works for cmaps up to 255 (not 256!) |
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struct charmap |
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{ |
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enum { INVALID = (u8)255 }; |
93 |
|
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char encode [256]; // index => char |
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u8 decode [256]; // char => index |
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unsigned int size; |
97 |
|
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charmap (const char *cmap); |
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}; |
100 |
|
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charmap::charmap (const char *cmap) |
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{ |
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char *enc = encode; |
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u8 *dec = decode; |
105 |
|
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memset (enc, (char) 0, 256); |
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memset (dec, (char)INVALID, 256); |
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|
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for (size = 0; cmap [size]; size++) |
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{ |
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enc [size] = cmap [size]; |
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dec [(u8)enc [size]] = size; |
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} |
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|
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assert (size < 256); |
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} |
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|
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#define MAX_DEC_LEN 500 |
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#define MAX_ENC_LEN (MAX_DEC_LEN * 2) |
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#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS) |
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|
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// ugly. minimum base is 16(!) |
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struct basecoder |
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{ |
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charmap cmap; |
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unsigned int enc_len [MAX_DEC_LEN]; |
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unsigned int dec_len [MAX_ENC_LEN]; |
128 |
|
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unsigned int encode_len (unsigned int len); |
130 |
unsigned int decode_len (unsigned int len); |
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|
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unsigned int encode (char *dst, u8 *src, unsigned int len); |
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unsigned int decode (u8 *dst, char *src, unsigned int len); |
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|
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basecoder (const char *cmap); |
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}; |
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|
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basecoder::basecoder (const char *cmap) |
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: cmap (cmap) |
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{ |
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for (unsigned int len = 0; len < MAX_DEC_LEN; ++len) |
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{ |
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u8 src [MAX_DEC_LEN]; |
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u8 dst [MAX_ENC_LEN]; |
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|
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memset (src, 255, len); |
147 |
|
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mp_limb_t m [MAX_LIMBS]; |
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mp_size_t n; |
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|
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n = mpn_set_str (m, src, len, 256); |
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n = mpn_get_str (dst, this->cmap.size, m, n); |
153 |
|
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for (int i = 0; !dst [i]; ++i) |
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n--; |
156 |
|
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enc_len [len] = n; |
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dec_len [n] = len; |
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} |
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} |
161 |
|
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unsigned int basecoder::encode_len (unsigned int len) |
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{ |
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return enc_len [len]; |
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} |
166 |
|
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unsigned int basecoder::decode_len (unsigned int len) |
168 |
{ |
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while (len && !dec_len [len]) |
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--len; |
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|
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return dec_len [len]; |
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} |
174 |
|
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unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) |
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{ |
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if (!len || len > MAX_DEC_LEN) |
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return 0; |
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|
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int elen = encode_len (len); |
181 |
|
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mp_limb_t m [MAX_LIMBS]; |
183 |
mp_size_t n; |
184 |
|
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u8 dst_ [MAX_ENC_LEN]; |
186 |
|
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n = mpn_set_str (m, src, len, 256); |
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n = mpn_get_str (dst_, cmap.size, m, n); |
189 |
|
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int plen = elen; // for padding |
191 |
|
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while (n < plen) |
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{ |
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*dst++ = cmap.encode [0]; |
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plen--; |
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} |
197 |
|
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for (unsigned int i = n - plen; i < n; ++i) |
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*dst++ = cmap.encode [dst_ [i]]; |
200 |
|
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return elen; |
202 |
} |
203 |
|
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unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) |
205 |
{ |
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if (!len || len > MAX_ENC_LEN) |
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return 0; |
208 |
|
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u8 src_ [MAX_ENC_LEN]; |
210 |
unsigned int elen = 0; |
211 |
|
212 |
while (len--) |
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{ |
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u8 val = cmap.decode [(u8)*src++]; |
215 |
|
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if (val != charmap::INVALID) |
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src_ [elen++] = val; |
218 |
} |
219 |
|
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int dlen = decode_len (elen); |
221 |
|
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mp_limb_t m [MAX_LIMBS]; |
223 |
mp_size_t n; |
224 |
|
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u8 dst_ [MAX_DEC_LEN]; |
226 |
|
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n = mpn_set_str (m, src_, elen, cmap.size); |
228 |
n = mpn_get_str (dst_, 256, m, n); |
229 |
|
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if (n < dlen) |
231 |
{ |
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memset (dst, 0, dlen - n); |
233 |
memcpy (dst + dlen - n, dst_, n); |
234 |
} |
235 |
else |
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memcpy (dst, dst_ + n - dlen, dlen); |
237 |
|
238 |
return dlen; |
239 |
} |
240 |
|
241 |
#if 0 |
242 |
struct test { test (); } test; |
243 |
|
244 |
test::test () |
245 |
{ |
246 |
basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz"); |
247 |
|
248 |
u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz"; |
249 |
static char enc[200]; |
250 |
static u8 dec[200]; |
251 |
|
252 |
for (int i = 1; i < 20; i++) |
253 |
{ |
254 |
int elen = cdc.encode (enc, in, i); |
255 |
int dlen = cdc.decode (dec, enc, elen); |
256 |
|
257 |
printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec); |
258 |
} |
259 |
abort (); |
260 |
} |
261 |
#endif |
262 |
|
263 |
//static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-"); |
264 |
//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
265 |
static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
266 |
//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet |
267 |
static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); |
268 |
|
269 |
///////////////////////////////////////////////////////////////////////////// |
270 |
|
271 |
#define HDRSIZE 6 |
272 |
|
273 |
inline void encode_header (char *data, int clientid, int seqno, int retry = 0) |
274 |
{ |
275 |
seqno &= SEQNO_MASK; |
276 |
|
277 |
u8 hdr[3] = { |
278 |
clientid, |
279 |
(seqno >> 8) | (retry << 6), |
280 |
seqno, |
281 |
}; |
282 |
|
283 |
assert (clientid < 256); |
284 |
|
285 |
cdc26.encode (data, hdr, 3); |
286 |
} |
287 |
|
288 |
inline void decode_header (char *data, int &clientid, int &seqno) |
289 |
{ |
290 |
u8 hdr[3]; |
291 |
|
292 |
cdc26.decode (hdr, data, HDRSIZE); |
293 |
|
294 |
clientid = hdr[0]; |
295 |
seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK; |
296 |
} |
297 |
|
298 |
///////////////////////////////////////////////////////////////////////////// |
299 |
|
300 |
struct byte_stream |
301 |
{ |
302 |
u8 *data; |
303 |
int maxsize; |
304 |
int fill; |
305 |
|
306 |
byte_stream (int maxsize); |
307 |
~byte_stream (); |
308 |
|
309 |
bool empty () { return !fill; } |
310 |
int size () { return fill; } |
311 |
|
312 |
bool put (u8 *data, unsigned int datalen); |
313 |
bool put (vpn_packet *pkt); |
314 |
vpn_packet *get (); |
315 |
|
316 |
u8 *begin () { return data; } |
317 |
void remove (int count); |
318 |
}; |
319 |
|
320 |
byte_stream::byte_stream (int maxsize) |
321 |
: maxsize (maxsize), fill (0) |
322 |
{ |
323 |
data = new u8 [maxsize]; |
324 |
} |
325 |
|
326 |
byte_stream::~byte_stream () |
327 |
{ |
328 |
delete data; |
329 |
} |
330 |
|
331 |
void byte_stream::remove (int count) |
332 |
{ |
333 |
if (count > fill) |
334 |
assert (count <= fill); |
335 |
|
336 |
memmove (data, data + count, fill -= count); |
337 |
} |
338 |
|
339 |
bool byte_stream::put (u8 *data, unsigned int datalen) |
340 |
{ |
341 |
if (maxsize - fill < datalen) |
342 |
return false; |
343 |
|
344 |
memcpy (this->data + fill, data, datalen); fill += datalen; |
345 |
|
346 |
return true; |
347 |
} |
348 |
|
349 |
bool byte_stream::put (vpn_packet *pkt) |
350 |
{ |
351 |
if (maxsize - fill < pkt->len + 2) |
352 |
return false; |
353 |
|
354 |
data [fill++] = pkt->len >> 8; |
355 |
data [fill++] = pkt->len; |
356 |
|
357 |
memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len; |
358 |
|
359 |
return true; |
360 |
} |
361 |
|
362 |
vpn_packet *byte_stream::get () |
363 |
{ |
364 |
unsigned int len; |
365 |
|
366 |
for (;;) |
367 |
{ |
368 |
len = (data [0] << 8) | data [1]; |
369 |
|
370 |
if (len <= MAXSIZE || fill < 2) |
371 |
break; |
372 |
|
373 |
// TODO: handle this better than skipping, e.g. by reset |
374 |
slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte...")); |
375 |
remove (1); |
376 |
} |
377 |
|
378 |
if (fill < len + 2) |
379 |
return 0; |
380 |
|
381 |
vpn_packet *pkt = new vpn_packet; |
382 |
|
383 |
pkt->len = len; |
384 |
memcpy (pkt->at (0), data + 2, len); |
385 |
remove (len + 2); |
386 |
|
387 |
return pkt; |
388 |
} |
389 |
|
390 |
///////////////////////////////////////////////////////////////////////////// |
391 |
|
392 |
#define FLAG_QUERY ( 0 << 15) |
393 |
#define FLAG_RESPONSE ( 1 << 15) |
394 |
#define FLAG_OP_MASK (15 << 11) |
395 |
#define FLAG_OP_QUERY ( 0 << 11) |
396 |
#define FLAG_AA ( 1 << 10) |
397 |
#define FLAG_TC ( 1 << 9) |
398 |
#define FLAG_RD ( 1 << 8) |
399 |
#define FLAG_RA ( 1 << 7) |
400 |
#define FLAG_AUTH ( 1 << 5) |
401 |
#define FLAG_RCODE_MASK (15 << 0) |
402 |
#define FLAG_RCODE_OK ( 0 << 0) |
403 |
#define FLAG_RCODE_FORMERR ( 1 << 0) |
404 |
#define FLAG_RCODE_SERVFAIL ( 2 << 0) |
405 |
#define FLAG_RCODE_NXDOMAIN ( 3 << 0) |
406 |
#define FLAG_RCODE_REFUSED ( 5 << 0) |
407 |
|
408 |
#define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) |
409 |
#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) |
410 |
|
411 |
struct dns_cfg |
412 |
{ |
413 |
static int next_uid; |
414 |
|
415 |
u8 id1, id2, id3, id4; |
416 |
|
417 |
u8 version; |
418 |
u8 flags; |
419 |
u8 rrtype; |
420 |
u8 def_ttl; |
421 |
|
422 |
u16 client; |
423 |
u16 uid; // to make request unique |
424 |
|
425 |
u16 max_size; |
426 |
u8 seq_cdc; |
427 |
u8 req_cdc; |
428 |
|
429 |
u8 rep_cdc; |
430 |
u8 delay; // time in 0.01s units that the server may delay replying packets |
431 |
u8 r3, r4; |
432 |
|
433 |
u8 r5, r6, r7, r8; |
434 |
|
435 |
void reset (int clientid); |
436 |
bool valid (); |
437 |
}; |
438 |
|
439 |
int dns_cfg::next_uid; |
440 |
|
441 |
void dns_cfg::reset (int clientid) |
442 |
{ |
443 |
id1 = 'G'; |
444 |
id2 = 'V'; |
445 |
id3 = 'P'; |
446 |
id4 = 'E'; |
447 |
|
448 |
version = 1; |
449 |
|
450 |
rrtype = RR_TYPE_TXT; |
451 |
flags = 0; |
452 |
def_ttl = 0; |
453 |
seq_cdc = 26; |
454 |
req_cdc = 62; |
455 |
rep_cdc = 0; |
456 |
max_size = htons (MAX_PKT_SIZE); |
457 |
client = htons (clientid); |
458 |
uid = next_uid++; |
459 |
delay = 0; |
460 |
|
461 |
r3 = r4 = 0; |
462 |
r4 = r5 = r6 = r7 = 0; |
463 |
} |
464 |
|
465 |
bool dns_cfg::valid () |
466 |
{ |
467 |
return id1 == 'G' |
468 |
&& id2 == 'V' |
469 |
&& id3 == 'P' |
470 |
&& id4 == 'E' |
471 |
&& seq_cdc == 26 |
472 |
&& req_cdc == 62 |
473 |
&& rep_cdc == 0 |
474 |
&& version == 1; |
475 |
} |
476 |
|
477 |
struct dns_packet : net_packet |
478 |
{ |
479 |
u16 id; |
480 |
u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 |
481 |
u16 qdcount, ancount, nscount, arcount; |
482 |
|
483 |
u8 data [MAXSIZE - 6 * 2]; |
484 |
|
485 |
int decode_label (char *data, int size, int &offs); |
486 |
}; |
487 |
|
488 |
int dns_packet::decode_label (char *data, int size, int &offs) |
489 |
{ |
490 |
char *orig = data; |
491 |
|
492 |
memset (data, 0, size); |
493 |
|
494 |
while (offs < size - 1) |
495 |
{ |
496 |
u8 len = (*this)[offs++]; |
497 |
|
498 |
if (!len) |
499 |
break; |
500 |
else if (len < 64) |
501 |
{ |
502 |
if (size < len + 1 || offs + len >= MAXSIZE - 1) |
503 |
break; |
504 |
|
505 |
memcpy (data, &((*this)[offs]), len); |
506 |
|
507 |
data += len; size -= len; offs += len; |
508 |
*data++ = '.'; size--; |
509 |
} |
510 |
else |
511 |
{ |
512 |
int offs2 = ((len & 63) << 8) + (*this)[offs++]; |
513 |
|
514 |
data += decode_label (data, size, offs2); |
515 |
break; |
516 |
} |
517 |
} |
518 |
|
519 |
return data - orig; |
520 |
} |
521 |
|
522 |
///////////////////////////////////////////////////////////////////////////// |
523 |
|
524 |
static u16 dns_id = 0; // TODO: should be per-vpn |
525 |
|
526 |
static u16 next_id () |
527 |
{ |
528 |
if (!dns_id) |
529 |
dns_id = time (0); |
530 |
|
531 |
// the simplest lsfr with periodicity 65535 i could find |
532 |
dns_id = (dns_id << 1) |
533 |
| (((dns_id >> 1) |
534 |
^ (dns_id >> 2) |
535 |
^ (dns_id >> 4) |
536 |
^ (dns_id >> 15)) & 1); |
537 |
|
538 |
return dns_id; |
539 |
} |
540 |
|
541 |
struct dns_rcv; |
542 |
struct dns_snd; |
543 |
|
544 |
struct dns_connection |
545 |
{ |
546 |
connection *c; |
547 |
struct vpn *vpn; |
548 |
|
549 |
dns_cfg cfg; |
550 |
|
551 |
bool established; |
552 |
|
553 |
tstamp last_received; |
554 |
tstamp last_sent; |
555 |
double min_latency; |
556 |
double poll_interval, send_interval; |
557 |
|
558 |
vector<dns_rcv *> rcvpq; |
559 |
|
560 |
byte_stream rcvdq; int rcvseq; int repseq; |
561 |
byte_stream snddq; int sndseq; |
562 |
|
563 |
void time_cb (time_watcher &w); time_watcher tw; |
564 |
void receive_rep (dns_rcv *r); |
565 |
|
566 |
dns_connection (connection *c); |
567 |
~dns_connection (); |
568 |
}; |
569 |
|
570 |
struct dns_snd |
571 |
{ |
572 |
dns_packet *pkt; |
573 |
tstamp timeout, sent; |
574 |
int retry; |
575 |
struct dns_connection *dns; |
576 |
int seqno; |
577 |
bool stdhdr; |
578 |
|
579 |
void gen_stream_req (int seqno, byte_stream &stream); |
580 |
void gen_syn_req (); |
581 |
|
582 |
dns_snd (dns_connection *dns); |
583 |
~dns_snd (); |
584 |
}; |
585 |
|
586 |
dns_snd::dns_snd (dns_connection *dns) |
587 |
: dns (dns) |
588 |
{ |
589 |
timeout = 0; |
590 |
retry = 0; |
591 |
seqno = 0; |
592 |
sent = NOW; |
593 |
stdhdr = false; |
594 |
|
595 |
pkt = new dns_packet; |
596 |
|
597 |
pkt->id = next_id (); |
598 |
} |
599 |
|
600 |
dns_snd::~dns_snd () |
601 |
{ |
602 |
delete pkt; |
603 |
} |
604 |
|
605 |
static void append_domain (dns_packet &pkt, int &offs, const char *domain) |
606 |
{ |
607 |
// add tunnel domain |
608 |
for (;;) |
609 |
{ |
610 |
const char *end = strchr (domain, '.'); |
611 |
|
612 |
if (!end) |
613 |
end = domain + strlen (domain); |
614 |
|
615 |
int len = end - domain; |
616 |
|
617 |
pkt [offs++] = len; |
618 |
memcpy (pkt.at (offs), domain, len); |
619 |
offs += len; |
620 |
|
621 |
if (!*end) |
622 |
break; |
623 |
|
624 |
domain = end + 1; |
625 |
} |
626 |
} |
627 |
|
628 |
void dns_snd::gen_stream_req (int seqno, byte_stream &stream) |
629 |
{ |
630 |
stdhdr = true; |
631 |
this->seqno = seqno; |
632 |
|
633 |
timeout = NOW + INITIAL_TIMEOUT; |
634 |
|
635 |
pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
636 |
pkt->qdcount = htons (1); |
637 |
|
638 |
int offs = 6*2; |
639 |
int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2); |
640 |
// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, |
641 |
// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra |
642 |
|
643 |
char enc[256], *encp = enc; |
644 |
encode_header (enc, THISNODE->id, seqno); |
645 |
|
646 |
int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); |
647 |
|
648 |
if (datalen > stream.size ()) |
649 |
datalen = stream.size (); |
650 |
|
651 |
int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; |
652 |
stream.remove (datalen); |
653 |
|
654 |
while (enclen) |
655 |
{ |
656 |
int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; |
657 |
|
658 |
(*pkt)[offs++] = lbllen; |
659 |
memcpy (pkt->at (offs), encp, lbllen); |
660 |
|
661 |
offs += lbllen; |
662 |
encp += lbllen; |
663 |
|
664 |
enclen -= lbllen; |
665 |
} |
666 |
|
667 |
append_domain (*pkt, offs, dns->c->conf->domain); |
668 |
|
669 |
(*pkt)[offs++] = 0; |
670 |
(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; |
671 |
(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
672 |
|
673 |
pkt->len = offs; |
674 |
} |
675 |
|
676 |
void dns_snd::gen_syn_req () |
677 |
{ |
678 |
timeout = NOW + INITIAL_SYN_TIMEOUT; |
679 |
|
680 |
pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
681 |
pkt->qdcount = htons (1); |
682 |
|
683 |
int offs = 6 * 2; |
684 |
|
685 |
int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg)); |
686 |
|
687 |
assert (elen <= MAX_LBL_SIZE); |
688 |
|
689 |
(*pkt)[offs] = elen; |
690 |
offs += elen + 1; |
691 |
append_domain (*pkt, offs, dns->c->conf->domain); |
692 |
|
693 |
(*pkt)[offs++] = 0; |
694 |
(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; |
695 |
(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
696 |
|
697 |
pkt->len = offs; |
698 |
} |
699 |
|
700 |
struct dns_rcv |
701 |
{ |
702 |
int seqno; |
703 |
dns_packet *pkt; // reply packet |
704 |
u8 data [MAXSIZE]; // actually part of the reply packet... |
705 |
int datalen; |
706 |
|
707 |
dns_rcv (int seqno, u8 *data, int datalen); |
708 |
~dns_rcv (); |
709 |
}; |
710 |
|
711 |
dns_rcv::dns_rcv (int seqno, u8 *data, int datalen) |
712 |
: seqno (seqno), pkt (new dns_packet), datalen (datalen) |
713 |
{ |
714 |
memcpy (this->data, data, datalen); |
715 |
} |
716 |
|
717 |
dns_rcv::~dns_rcv () |
718 |
{ |
719 |
delete pkt; |
720 |
} |
721 |
|
722 |
///////////////////////////////////////////////////////////////////////////// |
723 |
|
724 |
dns_connection::dns_connection (connection *c) |
725 |
: c (c) |
726 |
, rcvdq (MAX_BACKLOG * 2) |
727 |
, snddq (MAX_BACKLOG) |
728 |
, tw (this, &dns_connection::time_cb) |
729 |
{ |
730 |
vpn = c->vpn; |
731 |
|
732 |
established = false; |
733 |
|
734 |
rcvseq = repseq = sndseq = 0; |
735 |
|
736 |
last_sent = last_received = 0; |
737 |
poll_interval = 0.5; // starting here |
738 |
send_interval = 0.5; // starting rate |
739 |
min_latency = INITIAL_TIMEOUT; |
740 |
} |
741 |
|
742 |
dns_connection::~dns_connection () |
743 |
{ |
744 |
for (vector<dns_rcv *>::iterator i = rcvpq.begin (); |
745 |
i != rcvpq.end (); |
746 |
++i) |
747 |
delete *i; |
748 |
} |
749 |
|
750 |
void dns_connection::receive_rep (dns_rcv *r) |
751 |
{ |
752 |
if (r->datalen) |
753 |
{ |
754 |
last_received = NOW; |
755 |
tw.trigger (); |
756 |
|
757 |
poll_interval = send_interval; |
758 |
} |
759 |
else |
760 |
{ |
761 |
poll_interval *= 1.5; |
762 |
|
763 |
if (poll_interval > MAX_POLL_INTERVAL) |
764 |
poll_interval = MAX_POLL_INTERVAL; |
765 |
} |
766 |
|
767 |
rcvpq.push_back (r); |
768 |
|
769 |
redo: |
770 |
|
771 |
// find next packet |
772 |
for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) |
773 |
if (SEQNO_EQ (rcvseq, (*i)->seqno)) |
774 |
{ |
775 |
// enter the packet into our input stream |
776 |
r = *i; |
777 |
|
778 |
// remove the oldest packet, look forward, as it's oldest first |
779 |
for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) |
780 |
if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) |
781 |
{ |
782 |
delete *j; |
783 |
rcvpq.erase (j); |
784 |
break; |
785 |
} |
786 |
|
787 |
rcvseq = (rcvseq + 1) & SEQNO_MASK; |
788 |
|
789 |
if (!rcvdq.put (r->data, r->datalen)) |
790 |
{ |
791 |
slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)"); |
792 |
abort (); // MUST never overflow, can be caused by data corruption, TODO |
793 |
} |
794 |
|
795 |
while (vpn_packet *pkt = rcvdq.get ()) |
796 |
{ |
797 |
sockinfo si; |
798 |
si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4; |
799 |
|
800 |
vpn->recv_vpn_packet (pkt, si); |
801 |
|
802 |
delete pkt; |
803 |
} |
804 |
|
805 |
// check for further packets |
806 |
goto redo; |
807 |
} |
808 |
} |
809 |
|
810 |
void |
811 |
vpn::dnsv4_server (dns_packet &pkt) |
812 |
{ |
813 |
u16 flags = ntohs (pkt.flags); |
814 |
|
815 |
int offs = 6 * 2; // skip header |
816 |
|
817 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
818 |
|
819 |
if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) |
820 |
&& pkt.qdcount == htons (1)) |
821 |
{ |
822 |
char qname [MAXSIZE]; |
823 |
int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
824 |
|
825 |
u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
826 |
u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
827 |
|
828 |
pkt.qdcount = htons (1); |
829 |
pkt.ancount = 0; |
830 |
pkt.nscount = 0; // should be self, as other nameservers reply like this |
831 |
pkt.arcount = 0; // a record for self, as other nameservers reply like this |
832 |
|
833 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL); |
834 |
|
835 |
int dlen = strlen (THISNODE->domain); |
836 |
|
837 |
if (qclass == RR_CLASS_IN |
838 |
&& qlen > dlen + 1 |
839 |
&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen)) |
840 |
{ |
841 |
// now generate reply |
842 |
pkt.ancount = htons (1); // one answer RR |
843 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); |
844 |
|
845 |
if ((qtype == RR_TYPE_ANY |
846 |
|| qtype == RR_TYPE_TXT |
847 |
|| qtype == RR_TYPE_NULL) |
848 |
&& qlen > dlen + 1 + HDRSIZE) |
849 |
{ |
850 |
// correct class, domain: parse |
851 |
int client, seqno; |
852 |
decode_header (qname, client, seqno); |
853 |
|
854 |
u8 data[MAXSIZE]; |
855 |
int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); |
856 |
|
857 |
if (0 < client && client <= conns.size ()) |
858 |
{ |
859 |
connection *c = conns [client - 1]; |
860 |
dns_connection *dns = c->dns; |
861 |
dns_rcv *rcv; |
862 |
|
863 |
if (dns) |
864 |
{ |
865 |
for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) |
866 |
if (SEQNO_EQ ((*i)->seqno, seqno)) |
867 |
{ |
868 |
// already seen that request: simply reply with the cached reply |
869 |
dns_rcv *r = *i; |
870 |
|
871 |
slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno); |
872 |
|
873 |
// refresh header & id, as the retry count could have changed |
874 |
memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE); |
875 |
r->pkt->id = pkt.id; |
876 |
|
877 |
memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); |
878 |
|
879 |
goto duplicate_request; |
880 |
} |
881 |
|
882 |
// new packet, queue |
883 |
rcv = new dns_rcv (seqno, data, datalen); |
884 |
dns->receive_rep (rcv); |
885 |
} |
886 |
|
887 |
{ |
888 |
pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
889 |
|
890 |
int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; |
891 |
pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type |
892 |
pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
893 |
pkt [offs++] = 0; pkt [offs++] = 0; |
894 |
pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL |
895 |
|
896 |
int rdlen_offs = offs += 2; |
897 |
|
898 |
if (dns) |
899 |
{ |
900 |
int dlen = ntohs (dns->cfg.max_size) - offs; |
901 |
|
902 |
// bind doesn't compress well, so reduce further by one label length |
903 |
dlen -= qlen; |
904 |
|
905 |
// only put data into in-order sequence packets, if |
906 |
// we receive out-of-order packets we generate empty |
907 |
// replies |
908 |
//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D |
909 |
if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW) |
910 |
{ |
911 |
dns->repseq = seqno; |
912 |
|
913 |
while (dlen > 1 && !dns->snddq.empty ()) |
914 |
{ |
915 |
int txtlen = dlen <= 255 ? dlen - 1 : 255; |
916 |
|
917 |
if (txtlen > dns->snddq.size ()) |
918 |
txtlen = dns->snddq.size (); |
919 |
|
920 |
pkt[offs++] = txtlen; |
921 |
memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); |
922 |
offs += txtlen; |
923 |
dns->snddq.remove (txtlen); |
924 |
|
925 |
dlen -= txtlen + 1; |
926 |
} |
927 |
} |
928 |
|
929 |
// avoid completely empty TXT rdata |
930 |
if (offs == rdlen_offs) |
931 |
pkt[offs++] = 0; |
932 |
|
933 |
slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ()); |
934 |
} |
935 |
else |
936 |
{ |
937 |
// send RST |
938 |
pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
939 |
pkt [offs++] = CMD_IP_RST; |
940 |
} |
941 |
|
942 |
int rdlen = offs - rdlen_offs; |
943 |
|
944 |
pkt [rdlen_offs - 2] = rdlen >> 8; |
945 |
pkt [rdlen_offs - 1] = rdlen; |
946 |
|
947 |
if (dns) |
948 |
{ |
949 |
// now update dns_rcv copy |
950 |
rcv->pkt->len = offs; |
951 |
memcpy (rcv->pkt->at (0), pkt.at (0), offs); |
952 |
} |
953 |
} |
954 |
|
955 |
duplicate_request: ; |
956 |
} |
957 |
else |
958 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
959 |
} |
960 |
else if (qtype == RR_TYPE_A |
961 |
&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg))) |
962 |
{ |
963 |
dns_cfg cfg; |
964 |
cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg))); |
965 |
int client = ntohs (cfg.client); |
966 |
|
967 |
pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
968 |
|
969 |
pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type |
970 |
pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
971 |
pkt [offs++] = 0; pkt [offs++] = 0; |
972 |
pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL |
973 |
pkt [offs++] = 0; pkt [offs++] = 4; // rdlength |
974 |
|
975 |
slog (L_INFO, _("DNS: client %d connects"), client); |
976 |
|
977 |
pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
978 |
pkt [offs++] = CMD_IP_REJ; |
979 |
|
980 |
if (0 < client && client <= conns.size ()) |
981 |
{ |
982 |
connection *c = conns [client - 1]; |
983 |
|
984 |
if (cfg.valid ()) |
985 |
{ |
986 |
pkt [offs - 1] = CMD_IP_SYN; |
987 |
|
988 |
delete c->dns; |
989 |
c->dns = new dns_connection (c); |
990 |
c->dns->cfg = cfg; |
991 |
} |
992 |
} |
993 |
} |
994 |
} |
995 |
|
996 |
pkt.len = offs; |
997 |
} |
998 |
} |
999 |
|
1000 |
void |
1001 |
vpn::dnsv4_client (dns_packet &pkt) |
1002 |
{ |
1003 |
u16 flags = ntohs (pkt.flags); |
1004 |
int offs = 6 * 2; // skip header |
1005 |
|
1006 |
pkt.qdcount = ntohs (pkt.qdcount); |
1007 |
pkt.ancount = ntohs (pkt.ancount); |
1008 |
|
1009 |
// go through our request list and find the corresponding request |
1010 |
for (vector<dns_snd *>::iterator i = dns_sndpq.begin (); |
1011 |
i != dns_sndpq.end (); |
1012 |
++i) |
1013 |
if ((*i)->pkt->id == pkt.id) |
1014 |
{ |
1015 |
dns_connection *dns = (*i)->dns; |
1016 |
connection *c = dns->c; |
1017 |
int seqno = (*i)->seqno; |
1018 |
u8 data[MAXSIZE], *datap = data; |
1019 |
|
1020 |
if ((*i)->retry) |
1021 |
{ |
1022 |
dns->send_interval *= 1.01; |
1023 |
if (dns->send_interval > MAX_SEND_INTERVAL) |
1024 |
dns->send_interval = MAX_SEND_INTERVAL; |
1025 |
} |
1026 |
else |
1027 |
{ |
1028 |
#if 0 |
1029 |
dns->send_interval *= 0.999; |
1030 |
#endif |
1031 |
// the latency surely puts an upper bound on |
1032 |
// the minimum send interval |
1033 |
double latency = NOW - (*i)->sent; |
1034 |
|
1035 |
if (latency < dns->min_latency) |
1036 |
dns->min_latency = latency; |
1037 |
|
1038 |
if (dns->send_interval > dns->min_latency * LATENCY_FACTOR) |
1039 |
dns->send_interval = dns->min_latency * LATENCY_FACTOR; |
1040 |
|
1041 |
if (dns->send_interval < MIN_SEND_INTERVAL) |
1042 |
dns->send_interval = MIN_SEND_INTERVAL; |
1043 |
} |
1044 |
|
1045 |
delete *i; |
1046 |
dns_sndpq.erase (i); |
1047 |
|
1048 |
if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK)) |
1049 |
{ |
1050 |
char qname[MAXSIZE]; |
1051 |
|
1052 |
while (pkt.qdcount-- && offs < MAXSIZE - 4) |
1053 |
{ |
1054 |
int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
1055 |
offs += 4; // skip qtype, qclass |
1056 |
} |
1057 |
|
1058 |
while (pkt.ancount-- && offs < MAXSIZE - 10 && datap) |
1059 |
{ |
1060 |
int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
1061 |
|
1062 |
u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
1063 |
u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
1064 |
u32 ttl = pkt [offs++] << 24; |
1065 |
ttl |= pkt [offs++] << 16; |
1066 |
ttl |= pkt [offs++] << 8; |
1067 |
ttl |= pkt [offs++]; |
1068 |
u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; |
1069 |
|
1070 |
if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) |
1071 |
{ |
1072 |
if (rdlen <= MAXSIZE - offs) |
1073 |
{ |
1074 |
// decode bytes, finally |
1075 |
|
1076 |
while (rdlen) |
1077 |
{ |
1078 |
int txtlen = pkt [offs++]; |
1079 |
|
1080 |
assert (txtlen + offs < MAXSIZE - 1); |
1081 |
|
1082 |
memcpy (datap, pkt.at (offs), txtlen); |
1083 |
datap += txtlen; offs += txtlen; |
1084 |
|
1085 |
rdlen -= txtlen + 1; |
1086 |
} |
1087 |
} |
1088 |
} |
1089 |
else if (qtype == RR_TYPE_A) |
1090 |
{ |
1091 |
u8 ip [4]; |
1092 |
|
1093 |
ip [0] = pkt [offs++]; |
1094 |
ip [1] = pkt [offs++]; |
1095 |
ip [2] = pkt [offs++]; |
1096 |
ip [3] = pkt [offs++]; |
1097 |
|
1098 |
if (ip [0] == CMD_IP_1 |
1099 |
&& ip [1] == CMD_IP_2 |
1100 |
&& ip [2] == CMD_IP_3) |
1101 |
{ |
1102 |
slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); |
1103 |
|
1104 |
if (ip [3] == CMD_IP_RST) |
1105 |
{ |
1106 |
slog (L_DEBUG, _("DNS: got tunnel RST request")); |
1107 |
|
1108 |
delete dns; c->dns = 0; |
1109 |
|
1110 |
return; |
1111 |
} |
1112 |
else if (ip [3] == CMD_IP_SYN) |
1113 |
{ |
1114 |
slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); |
1115 |
dns->established = true; |
1116 |
} |
1117 |
else if (ip [3] == CMD_IP_REJ) |
1118 |
{ |
1119 |
slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting.")); |
1120 |
abort (); |
1121 |
} |
1122 |
else |
1123 |
slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); |
1124 |
} |
1125 |
else |
1126 |
slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), |
1127 |
ip [0], ip [1], ip [2], ip [3]); |
1128 |
|
1129 |
return; |
1130 |
} |
1131 |
|
1132 |
int client, rseqno; |
1133 |
decode_header (qname, client, rseqno); |
1134 |
|
1135 |
if (client != THISNODE->id) |
1136 |
{ |
1137 |
slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring")); |
1138 |
datap = 0; |
1139 |
} |
1140 |
else if (rseqno != seqno) |
1141 |
{ |
1142 |
slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?")); |
1143 |
datap = 0; |
1144 |
} |
1145 |
} |
1146 |
} |
1147 |
|
1148 |
// todo: pkt now used |
1149 |
if (datap) |
1150 |
dns->receive_rep (new dns_rcv (seqno, data, datap - data)); |
1151 |
|
1152 |
break; |
1153 |
} |
1154 |
} |
1155 |
|
1156 |
void |
1157 |
vpn::dnsv4_ev (io_watcher &w, short revents) |
1158 |
{ |
1159 |
if (revents & EVENT_READ) |
1160 |
{ |
1161 |
dns_packet *pkt = new dns_packet; |
1162 |
struct sockaddr_in sa; |
1163 |
socklen_t sa_len = sizeof (sa); |
1164 |
|
1165 |
pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); |
1166 |
|
1167 |
if (pkt->len > 0) |
1168 |
{ |
1169 |
if (ntohs (pkt->flags) & FLAG_RESPONSE) |
1170 |
dnsv4_client (*pkt); |
1171 |
else |
1172 |
{ |
1173 |
dnsv4_server (*pkt); |
1174 |
sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); |
1175 |
} |
1176 |
|
1177 |
delete pkt; |
1178 |
} |
1179 |
} |
1180 |
} |
1181 |
|
1182 |
bool |
1183 |
vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
1184 |
{ |
1185 |
int client = ntohs (si.port); |
1186 |
|
1187 |
assert (0 < client && client <= conns.size ()); |
1188 |
|
1189 |
connection *c = conns [client - 1]; |
1190 |
|
1191 |
if (!c->dns) |
1192 |
c->dns = new dns_connection (c); |
1193 |
|
1194 |
if (c->dns->snddq.put (pkt)) |
1195 |
c->dns->tw.trigger (); |
1196 |
|
1197 |
// always return true even if the buffer overflows |
1198 |
return true; |
1199 |
} |
1200 |
|
1201 |
void |
1202 |
connection::dnsv4_reset_connection () |
1203 |
{ |
1204 |
//delete dns; dns = 0; //TODO |
1205 |
} |
1206 |
|
1207 |
#define NEXT(w) do { if (next > (w)) next = w; } while (0) |
1208 |
|
1209 |
void |
1210 |
dns_connection::time_cb (time_watcher &w) |
1211 |
{ |
1212 |
// servers have to be polled |
1213 |
if (THISNODE->dns_port) |
1214 |
return; |
1215 |
|
1216 |
// check for timeouts and (re)transmit |
1217 |
tstamp next = NOW + poll_interval; |
1218 |
dns_snd *send = 0; |
1219 |
|
1220 |
for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); |
1221 |
i != vpn->dns_sndpq.end (); |
1222 |
++i) |
1223 |
{ |
1224 |
dns_snd *r = *i; |
1225 |
|
1226 |
if (r->timeout <= NOW) |
1227 |
{ |
1228 |
if (!send) |
1229 |
{ |
1230 |
send = r; |
1231 |
|
1232 |
r->retry++; |
1233 |
r->timeout = NOW + (r->retry * min_latency * TIMEOUT_FACTOR); |
1234 |
|
1235 |
// the following code changes the query section a bit, forcing |
1236 |
// the forwarder to generate a new request |
1237 |
if (r->stdhdr) |
1238 |
{ |
1239 |
//printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry); |
1240 |
//encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry); |
1241 |
} |
1242 |
} |
1243 |
} |
1244 |
else |
1245 |
NEXT (r->timeout); |
1246 |
} |
1247 |
|
1248 |
if (!send) |
1249 |
{ |
1250 |
// generate a new packet, if wise |
1251 |
|
1252 |
if (!established) |
1253 |
{ |
1254 |
if (vpn->dns_sndpq.empty ()) |
1255 |
{ |
1256 |
send = new dns_snd (this); |
1257 |
|
1258 |
cfg.reset (THISNODE->id); |
1259 |
send->gen_syn_req (); |
1260 |
} |
1261 |
} |
1262 |
else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING |
1263 |
&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) |
1264 |
{ |
1265 |
if (last_sent + send_interval <= NOW) |
1266 |
{ |
1267 |
//printf ("sending data request etc.\n"); //D |
1268 |
if (!snddq.empty () || last_received + 1. > NOW) |
1269 |
{ |
1270 |
poll_interval = send_interval; |
1271 |
NEXT (NOW + send_interval); |
1272 |
} |
1273 |
|
1274 |
send = new dns_snd (this); |
1275 |
send->gen_stream_req (sndseq, snddq); |
1276 |
send->timeout = NOW + min_latency * TIMEOUT_FACTOR; |
1277 |
|
1278 |
sndseq = (sndseq + 1) & SEQNO_MASK; |
1279 |
} |
1280 |
else |
1281 |
NEXT (last_sent + send_interval); |
1282 |
} |
1283 |
|
1284 |
if (send) |
1285 |
vpn->dns_sndpq.push_back (send); |
1286 |
} |
1287 |
|
1288 |
if (send) |
1289 |
{ |
1290 |
last_sent = NOW; |
1291 |
if (rand () & 15 != 0)//D |
1292 |
sendto (vpn->dnsv4_fd, |
1293 |
send->pkt->at (0), send->pkt->len, 0, |
1294 |
vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); |
1295 |
} |
1296 |
|
1297 |
slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)", |
1298 |
poll_interval, send_interval, next - NOW, |
1299 |
vpn->dns_sndpq.size (), snddq.size (), |
1300 |
rcvpq.size ()); |
1301 |
|
1302 |
// TODO: no idea when this happens, but when next < NOW, we have a problem |
1303 |
if (next < NOW + 0.001) |
1304 |
next = NOW + 0.1; |
1305 |
|
1306 |
w.start (next); |
1307 |
} |
1308 |
|
1309 |
#endif |
1310 |
|