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. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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|
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// TODO: EDNS0 option to increase dns mtu? |
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// TODO: re-write dns packet parsing/creation using a safe mem-buffer |
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// to ensure no buffer overflows or similar problems. |
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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 <cstdio> /* bug in libgmp: gmp.h relies on cstdio being included */ |
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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 INITIAL_TIMEOUT 0.1 // retry timeouts |
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#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn |
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|
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#define MAX_SEND_INTERVAL 2. // optimistic? |
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|
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#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog |
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#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE |
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|
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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 request byte less give room for two reply bytes |
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|
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#define SEQNO_MASK 0x3fff |
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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 }; |
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|
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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; |
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|
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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); |
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unsigned int decode_len (unsigned int len); |
131 |
|
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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); |
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|
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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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} |
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|
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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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} |
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|
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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); |
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|
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mp_limb_t m [MAX_LIMBS]; |
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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); |
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|
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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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} |
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|
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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; |
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} |
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|
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unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) |
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{ |
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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 |
|
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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 |
{ |
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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 |
// although the protocol itself allows for some configurability, |
468 |
// only the following encoding/decoding settings are implemented. |
469 |
return id1 == 'G' |
470 |
&& id2 == 'V' |
471 |
&& id3 == 'P' |
472 |
&& id4 == 'E' |
473 |
&& seq_cdc == 26 |
474 |
&& req_cdc == 62 |
475 |
&& rep_cdc == 0 |
476 |
&& version == 1; |
477 |
} |
478 |
|
479 |
struct dns_packet : net_packet |
480 |
{ |
481 |
u16 id; |
482 |
u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 |
483 |
u16 qdcount, ancount, nscount, arcount; |
484 |
|
485 |
u8 data [MAXSIZE - 6 * 2]; |
486 |
|
487 |
int decode_label (char *data, int size, int &offs); |
488 |
}; |
489 |
|
490 |
int dns_packet::decode_label (char *data, int size, int &offs) |
491 |
{ |
492 |
char *orig = data; |
493 |
|
494 |
memset (data, 0, size); |
495 |
|
496 |
while (offs < size - 1) |
497 |
{ |
498 |
u8 len = (*this)[offs++]; |
499 |
|
500 |
if (!len) |
501 |
break; |
502 |
else if (len < 64) |
503 |
{ |
504 |
if (size < len + 1 || offs + len >= MAXSIZE - 1) |
505 |
break; |
506 |
|
507 |
memcpy (data, &((*this)[offs]), len); |
508 |
|
509 |
data += len; size -= len; offs += len; |
510 |
*data++ = '.'; size--; |
511 |
} |
512 |
else |
513 |
{ |
514 |
int offs2 = ((len & 63) << 8) + (*this)[offs++]; |
515 |
|
516 |
data += decode_label (data, size, offs2); |
517 |
break; |
518 |
} |
519 |
} |
520 |
|
521 |
return data - orig; |
522 |
} |
523 |
|
524 |
///////////////////////////////////////////////////////////////////////////// |
525 |
|
526 |
static u16 dns_id = 0; // TODO: should be per-vpn |
527 |
|
528 |
static u16 next_id () |
529 |
{ |
530 |
if (!dns_id) |
531 |
dns_id = time (0); |
532 |
|
533 |
// the simplest lsfr with periodicity 65535 i could find |
534 |
dns_id = (dns_id << 1) |
535 |
| (((dns_id >> 1) |
536 |
^ (dns_id >> 2) |
537 |
^ (dns_id >> 4) |
538 |
^ (dns_id >> 15)) & 1); |
539 |
|
540 |
return dns_id; |
541 |
} |
542 |
|
543 |
struct dns_rcv; |
544 |
struct dns_snd; |
545 |
|
546 |
struct dns_connection |
547 |
{ |
548 |
connection *c; |
549 |
struct vpn *vpn; |
550 |
|
551 |
dns_cfg cfg; |
552 |
|
553 |
bool established; |
554 |
|
555 |
tstamp last_received; |
556 |
tstamp last_sent; |
557 |
double min_latency; |
558 |
double poll_interval, send_interval; |
559 |
|
560 |
vector<dns_rcv *> rcvpq; |
561 |
|
562 |
byte_stream rcvdq; int rcvseq; int repseq; |
563 |
byte_stream snddq; int sndseq; |
564 |
|
565 |
void time_cb (ev::timer &w, int revents); ev::timer tw; |
566 |
void receive_rep (dns_rcv *r); |
567 |
|
568 |
dns_connection (connection *c); |
569 |
~dns_connection (); |
570 |
}; |
571 |
|
572 |
struct dns_snd |
573 |
{ |
574 |
dns_packet *pkt; |
575 |
tstamp timeout, sent; |
576 |
int retry; |
577 |
struct dns_connection *dns; |
578 |
int seqno; |
579 |
bool stdhdr; |
580 |
|
581 |
void gen_stream_req (int seqno, byte_stream &stream); |
582 |
void gen_syn_req (); |
583 |
|
584 |
dns_snd (dns_connection *dns); |
585 |
~dns_snd (); |
586 |
}; |
587 |
|
588 |
dns_snd::dns_snd (dns_connection *dns) |
589 |
: dns (dns) |
590 |
{ |
591 |
timeout = 0; |
592 |
retry = 0; |
593 |
seqno = 0; |
594 |
sent = ev_now (); |
595 |
stdhdr = false; |
596 |
|
597 |
pkt = new dns_packet; |
598 |
|
599 |
pkt->id = next_id (); |
600 |
} |
601 |
|
602 |
dns_snd::~dns_snd () |
603 |
{ |
604 |
delete pkt; |
605 |
} |
606 |
|
607 |
static void append_domain (dns_packet &pkt, int &offs, const char *domain) |
608 |
{ |
609 |
// add tunnel domain |
610 |
for (;;) |
611 |
{ |
612 |
const char *end = strchr (domain, '.'); |
613 |
|
614 |
if (!end) |
615 |
end = domain + strlen (domain); |
616 |
|
617 |
int len = end - domain; |
618 |
|
619 |
pkt [offs++] = len; |
620 |
memcpy (pkt.at (offs), domain, len); |
621 |
offs += len; |
622 |
|
623 |
if (!*end) |
624 |
break; |
625 |
|
626 |
domain = end + 1; |
627 |
} |
628 |
} |
629 |
|
630 |
void dns_snd::gen_stream_req (int seqno, byte_stream &stream) |
631 |
{ |
632 |
stdhdr = true; |
633 |
this->seqno = seqno; |
634 |
|
635 |
timeout = ev_now () + INITIAL_TIMEOUT; |
636 |
|
637 |
pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
638 |
pkt->qdcount = htons (1); |
639 |
|
640 |
int offs = 6*2; |
641 |
int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2); |
642 |
// MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, |
643 |
// so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra |
644 |
|
645 |
char enc[256], *encp = enc; |
646 |
encode_header (enc, THISNODE->id, seqno); |
647 |
|
648 |
int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); |
649 |
|
650 |
if (datalen > stream.size ()) |
651 |
datalen = stream.size (); |
652 |
|
653 |
int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; |
654 |
stream.remove (datalen); |
655 |
|
656 |
while (enclen) |
657 |
{ |
658 |
int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; |
659 |
|
660 |
(*pkt)[offs++] = lbllen; |
661 |
memcpy (pkt->at (offs), encp, lbllen); |
662 |
|
663 |
offs += lbllen; |
664 |
encp += lbllen; |
665 |
|
666 |
enclen -= lbllen; |
667 |
} |
668 |
|
669 |
append_domain (*pkt, offs, dns->c->conf->domain); |
670 |
|
671 |
(*pkt)[offs++] = 0; |
672 |
(*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; |
673 |
(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
674 |
|
675 |
pkt->len = offs; |
676 |
} |
677 |
|
678 |
void dns_snd::gen_syn_req () |
679 |
{ |
680 |
timeout = ev_now () + INITIAL_SYN_TIMEOUT; |
681 |
|
682 |
pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
683 |
pkt->qdcount = htons (1); |
684 |
|
685 |
int offs = 6 * 2; |
686 |
|
687 |
int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg)); |
688 |
|
689 |
assert (elen <= MAX_LBL_SIZE); |
690 |
|
691 |
(*pkt)[offs] = elen; |
692 |
offs += elen + 1; |
693 |
append_domain (*pkt, offs, dns->c->conf->domain); |
694 |
|
695 |
(*pkt)[offs++] = 0; |
696 |
(*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; |
697 |
(*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
698 |
|
699 |
pkt->len = offs; |
700 |
} |
701 |
|
702 |
struct dns_rcv |
703 |
{ |
704 |
int seqno; |
705 |
dns_packet *pkt; // reply packet |
706 |
u8 data [MAXSIZE]; // actually part of the reply packet... |
707 |
int datalen; |
708 |
|
709 |
dns_rcv (int seqno, u8 *data, int datalen); |
710 |
~dns_rcv (); |
711 |
}; |
712 |
|
713 |
dns_rcv::dns_rcv (int seqno, u8 *data, int datalen) |
714 |
: seqno (seqno), pkt (new dns_packet), datalen (datalen) |
715 |
{ |
716 |
memcpy (this->data, data, datalen); |
717 |
} |
718 |
|
719 |
dns_rcv::~dns_rcv () |
720 |
{ |
721 |
delete pkt; |
722 |
} |
723 |
|
724 |
///////////////////////////////////////////////////////////////////////////// |
725 |
|
726 |
dns_connection::dns_connection (connection *c) |
727 |
: c (c) |
728 |
, rcvdq (MAX_BACKLOG * 2) |
729 |
, snddq (MAX_BACKLOG) |
730 |
{ |
731 |
tw.set<dns_connection, &dns_connection::time_cb> (this); |
732 |
|
733 |
vpn = c->vpn; |
734 |
|
735 |
established = false; |
736 |
|
737 |
rcvseq = repseq = sndseq = 0; |
738 |
|
739 |
last_sent = last_received = 0; |
740 |
poll_interval = 0.5; // starting here |
741 |
send_interval = 0.5; // starting rate |
742 |
min_latency = INITIAL_TIMEOUT; |
743 |
} |
744 |
|
745 |
dns_connection::~dns_connection () |
746 |
{ |
747 |
for (vector<dns_rcv *>::iterator i = rcvpq.begin (); |
748 |
i != rcvpq.end (); |
749 |
++i) |
750 |
delete *i; |
751 |
} |
752 |
|
753 |
void dns_connection::receive_rep (dns_rcv *r) |
754 |
{ |
755 |
if (r->datalen) |
756 |
{ |
757 |
last_received = ev_now (); |
758 |
tw (); |
759 |
|
760 |
poll_interval = send_interval; |
761 |
} |
762 |
else |
763 |
{ |
764 |
poll_interval *= 1.5; |
765 |
|
766 |
if (poll_interval > MAX_POLL_INTERVAL) |
767 |
poll_interval = MAX_POLL_INTERVAL; |
768 |
} |
769 |
|
770 |
rcvpq.push_back (r); |
771 |
|
772 |
redo: |
773 |
|
774 |
// find next packet |
775 |
for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) |
776 |
if (SEQNO_EQ (rcvseq, (*i)->seqno)) |
777 |
{ |
778 |
//printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D |
779 |
// enter the packet into our input stream |
780 |
r = *i; |
781 |
|
782 |
// remove the oldest packet, look forward, as it's oldest first |
783 |
for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) |
784 |
if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) |
785 |
{ |
786 |
//printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D |
787 |
delete *j; |
788 |
rcvpq.erase (j); |
789 |
break; |
790 |
} |
791 |
|
792 |
rcvseq = (rcvseq + 1) & SEQNO_MASK; |
793 |
|
794 |
if (!rcvdq.put (r->data, r->datalen)) |
795 |
{ |
796 |
slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)"); |
797 |
abort (); // MUST never overflow, can be caused by data corruption, TODO |
798 |
} |
799 |
|
800 |
while (vpn_packet *pkt = rcvdq.get ()) |
801 |
{ |
802 |
sockinfo si; |
803 |
si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4; |
804 |
|
805 |
vpn->recv_vpn_packet (pkt, si); |
806 |
|
807 |
delete pkt; |
808 |
} |
809 |
|
810 |
// check for further packets |
811 |
goto redo; |
812 |
} |
813 |
} |
814 |
|
815 |
void |
816 |
vpn::dnsv4_server (dns_packet &pkt) |
817 |
{ |
818 |
u16 flags = ntohs (pkt.flags); |
819 |
|
820 |
int offs = 6 * 2; // skip header |
821 |
|
822 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
823 |
|
824 |
if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) |
825 |
&& pkt.qdcount == htons (1)) |
826 |
{ |
827 |
char qname [MAXSIZE]; |
828 |
int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
829 |
|
830 |
u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
831 |
u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
832 |
|
833 |
pkt.qdcount = htons (1); |
834 |
pkt.ancount = 0; |
835 |
pkt.nscount = 0; // should be self, as other nameservers reply like this |
836 |
pkt.arcount = 0; // a record for self, as other nameservers reply like this |
837 |
|
838 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL); |
839 |
|
840 |
int dlen = strlen (THISNODE->domain); |
841 |
|
842 |
if (qclass == RR_CLASS_IN |
843 |
&& qlen > dlen + 1 |
844 |
&& !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen)) |
845 |
{ |
846 |
// now generate reply |
847 |
pkt.ancount = htons (1); // one answer RR |
848 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); |
849 |
|
850 |
if ((qtype == RR_TYPE_ANY |
851 |
|| qtype == RR_TYPE_TXT |
852 |
|| qtype == RR_TYPE_NULL) |
853 |
&& qlen > dlen + 1 + HDRSIZE) |
854 |
{ |
855 |
// correct class, domain: parse |
856 |
int client, seqno; |
857 |
decode_header (qname, client, seqno); |
858 |
|
859 |
u8 data[MAXSIZE]; |
860 |
int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); |
861 |
|
862 |
if (0 < client && client <= conns.size ()) |
863 |
{ |
864 |
connection *c = conns [client - 1]; |
865 |
dns_connection *dns = c->dns; |
866 |
dns_rcv *rcv; |
867 |
|
868 |
if (dns) |
869 |
{ |
870 |
for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) |
871 |
if (SEQNO_EQ ((*i)->seqno, seqno)) |
872 |
{ |
873 |
// already seen that request: simply reply with the cached reply |
874 |
dns_rcv *r = *i; |
875 |
|
876 |
slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno); |
877 |
|
878 |
// refresh header & id, as the retry count could have changed |
879 |
memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE); |
880 |
r->pkt->id = pkt.id; |
881 |
|
882 |
memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); |
883 |
|
884 |
goto duplicate_request; |
885 |
} |
886 |
|
887 |
// new packet, queue |
888 |
rcv = new dns_rcv (seqno, data, datalen); |
889 |
dns->receive_rep (rcv); |
890 |
} |
891 |
|
892 |
{ |
893 |
pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
894 |
|
895 |
int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; |
896 |
pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type |
897 |
pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
898 |
pkt [offs++] = 0; pkt [offs++] = 0; |
899 |
pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL |
900 |
|
901 |
int rdlen_offs = offs += 2; |
902 |
|
903 |
if (dns) |
904 |
{ |
905 |
int dlen = ntohs (dns->cfg.max_size) - offs; |
906 |
|
907 |
// bind doesn't compress well, so reduce further by one label length |
908 |
dlen -= qlen; |
909 |
|
910 |
// only put data into in-order sequence packets, if |
911 |
// we receive out-of-order packets we generate empty |
912 |
// replies |
913 |
//printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D |
914 |
if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW) |
915 |
{ |
916 |
dns->repseq = seqno; |
917 |
|
918 |
while (dlen > 1 && !dns->snddq.empty ()) |
919 |
{ |
920 |
int txtlen = dlen <= 255 ? dlen - 1 : 255; |
921 |
|
922 |
if (txtlen > dns->snddq.size ()) |
923 |
txtlen = dns->snddq.size (); |
924 |
|
925 |
pkt[offs++] = txtlen; |
926 |
memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); |
927 |
offs += txtlen; |
928 |
dns->snddq.remove (txtlen); |
929 |
|
930 |
dlen -= txtlen + 1; |
931 |
} |
932 |
} |
933 |
|
934 |
// avoid completely empty TXT rdata |
935 |
if (offs == rdlen_offs) |
936 |
pkt[offs++] = 0; |
937 |
|
938 |
slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ()); |
939 |
} |
940 |
else |
941 |
{ |
942 |
// send RST |
943 |
pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
944 |
pkt [offs++] = CMD_IP_RST; |
945 |
} |
946 |
|
947 |
int rdlen = offs - rdlen_offs; |
948 |
|
949 |
pkt [rdlen_offs - 2] = rdlen >> 8; |
950 |
pkt [rdlen_offs - 1] = rdlen; |
951 |
|
952 |
if (dns) |
953 |
{ |
954 |
// now update dns_rcv copy |
955 |
rcv->pkt->len = offs; |
956 |
memcpy (rcv->pkt->at (0), pkt.at (0), offs); |
957 |
} |
958 |
} |
959 |
|
960 |
duplicate_request: ; |
961 |
} |
962 |
else |
963 |
pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
964 |
} |
965 |
else if (qtype == RR_TYPE_A |
966 |
&& qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg))) |
967 |
{ |
968 |
dns_cfg cfg; |
969 |
cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg))); |
970 |
int client = ntohs (cfg.client); |
971 |
|
972 |
pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
973 |
|
974 |
pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type |
975 |
pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
976 |
pkt [offs++] = 0; pkt [offs++] = 0; |
977 |
pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL |
978 |
pkt [offs++] = 0; pkt [offs++] = 4; // rdlength |
979 |
|
980 |
slog (L_INFO, _("DNS: client %d connects"), client); |
981 |
|
982 |
pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
983 |
pkt [offs++] = CMD_IP_REJ; |
984 |
|
985 |
if (0 < client && client <= conns.size ()) |
986 |
{ |
987 |
connection *c = conns [client - 1]; |
988 |
|
989 |
if (cfg.valid ()) |
990 |
{ |
991 |
pkt [offs - 1] = CMD_IP_SYN; |
992 |
|
993 |
delete c->dns; |
994 |
c->dns = new dns_connection (c); |
995 |
c->dns->cfg = cfg; |
996 |
} |
997 |
} |
998 |
} |
999 |
} |
1000 |
|
1001 |
pkt.len = offs; |
1002 |
} |
1003 |
} |
1004 |
|
1005 |
void |
1006 |
vpn::dnsv4_client (dns_packet &pkt) |
1007 |
{ |
1008 |
u16 flags = ntohs (pkt.flags); |
1009 |
int offs = 6 * 2; // skip header |
1010 |
|
1011 |
pkt.qdcount = ntohs (pkt.qdcount); |
1012 |
pkt.ancount = ntohs (pkt.ancount); |
1013 |
|
1014 |
// go through our request list and find the corresponding request |
1015 |
for (vector<dns_snd *>::iterator i = dns_sndpq.begin (); |
1016 |
i != dns_sndpq.end (); |
1017 |
++i) |
1018 |
if ((*i)->pkt->id == pkt.id) |
1019 |
{ |
1020 |
dns_connection *dns = (*i)->dns; |
1021 |
connection *c = dns->c; |
1022 |
int seqno = (*i)->seqno; |
1023 |
u8 data[MAXSIZE], *datap = data; |
1024 |
//printf ("rcv pkt %x\n", seqno);//D |
1025 |
|
1026 |
if ((*i)->retry) |
1027 |
{ |
1028 |
dns->send_interval *= 1.01; |
1029 |
if (dns->send_interval > MAX_SEND_INTERVAL) |
1030 |
dns->send_interval = MAX_SEND_INTERVAL; |
1031 |
} |
1032 |
else |
1033 |
{ |
1034 |
#if 0 |
1035 |
dns->send_interval *= 0.999; |
1036 |
#endif |
1037 |
// the latency surely puts an upper bound on |
1038 |
// the minimum send interval |
1039 |
double latency = ev_now () - (*i)->sent; |
1040 |
|
1041 |
if (latency < dns->min_latency) |
1042 |
dns->min_latency = latency; |
1043 |
|
1044 |
if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor) |
1045 |
dns->send_interval = dns->min_latency * conf.dns_overlap_factor; |
1046 |
|
1047 |
if (dns->send_interval < conf.dns_send_interval) |
1048 |
dns->send_interval = conf.dns_send_interval; |
1049 |
} |
1050 |
|
1051 |
delete *i; |
1052 |
dns_sndpq.erase (i); |
1053 |
|
1054 |
if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK)) |
1055 |
{ |
1056 |
char qname[MAXSIZE]; |
1057 |
|
1058 |
while (pkt.qdcount-- && offs < MAXSIZE - 4) |
1059 |
{ |
1060 |
int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
1061 |
offs += 4; // skip qtype, qclass |
1062 |
} |
1063 |
|
1064 |
while (pkt.ancount-- && offs < MAXSIZE - 10 && datap) |
1065 |
{ |
1066 |
int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
1067 |
|
1068 |
u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
1069 |
u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
1070 |
u32 ttl = pkt [offs++] << 24; |
1071 |
ttl |= pkt [offs++] << 16; |
1072 |
ttl |= pkt [offs++] << 8; |
1073 |
ttl |= pkt [offs++]; |
1074 |
u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; |
1075 |
|
1076 |
if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) |
1077 |
{ |
1078 |
if (rdlen <= MAXSIZE - offs) |
1079 |
{ |
1080 |
// decode bytes, finally |
1081 |
|
1082 |
while (rdlen) |
1083 |
{ |
1084 |
int txtlen = pkt [offs++]; |
1085 |
|
1086 |
assert (txtlen + offs < MAXSIZE - 1); |
1087 |
|
1088 |
memcpy (datap, pkt.at (offs), txtlen); |
1089 |
datap += txtlen; offs += txtlen; |
1090 |
|
1091 |
rdlen -= txtlen + 1; |
1092 |
} |
1093 |
} |
1094 |
} |
1095 |
else if (qtype == RR_TYPE_A) |
1096 |
{ |
1097 |
u8 ip [4]; |
1098 |
|
1099 |
ip [0] = pkt [offs++]; |
1100 |
ip [1] = pkt [offs++]; |
1101 |
ip [2] = pkt [offs++]; |
1102 |
ip [3] = pkt [offs++]; |
1103 |
|
1104 |
if (ip [0] == CMD_IP_1 |
1105 |
&& ip [1] == CMD_IP_2 |
1106 |
&& ip [2] == CMD_IP_3) |
1107 |
{ |
1108 |
slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); |
1109 |
|
1110 |
if (ip [3] == CMD_IP_RST) |
1111 |
{ |
1112 |
slog (L_DEBUG, _("DNS: got tunnel RST request")); |
1113 |
|
1114 |
delete dns; c->dns = 0; |
1115 |
|
1116 |
return; |
1117 |
} |
1118 |
else if (ip [3] == CMD_IP_SYN) |
1119 |
{ |
1120 |
slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); |
1121 |
dns->established = true; |
1122 |
} |
1123 |
else if (ip [3] == CMD_IP_REJ) |
1124 |
{ |
1125 |
slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting.")); |
1126 |
abort (); |
1127 |
} |
1128 |
else |
1129 |
slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); |
1130 |
} |
1131 |
else |
1132 |
slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), |
1133 |
ip [0], ip [1], ip [2], ip [3]); |
1134 |
|
1135 |
return; |
1136 |
} |
1137 |
|
1138 |
int client, rseqno; |
1139 |
decode_header (qname, client, rseqno); |
1140 |
|
1141 |
if (client != THISNODE->id) |
1142 |
{ |
1143 |
slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring")); |
1144 |
datap = 0; |
1145 |
} |
1146 |
else if (rseqno != seqno) |
1147 |
{ |
1148 |
slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?")); |
1149 |
datap = 0; |
1150 |
} |
1151 |
} |
1152 |
} |
1153 |
|
1154 |
// todo: pkt now used |
1155 |
if (datap) |
1156 |
dns->receive_rep (new dns_rcv (seqno, data, datap - data)); |
1157 |
|
1158 |
break; |
1159 |
} |
1160 |
} |
1161 |
|
1162 |
void |
1163 |
vpn::dnsv4_ev (ev::io &w, int revents) |
1164 |
{ |
1165 |
if (revents & EV_READ) |
1166 |
{ |
1167 |
dns_packet *pkt = new dns_packet; |
1168 |
struct sockaddr_in sa; |
1169 |
socklen_t sa_len = sizeof (sa); |
1170 |
|
1171 |
pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); |
1172 |
|
1173 |
if (pkt->len > 0) |
1174 |
{ |
1175 |
if (ntohs (pkt->flags) & FLAG_RESPONSE) |
1176 |
dnsv4_client (*pkt); |
1177 |
else |
1178 |
{ |
1179 |
dnsv4_server (*pkt); |
1180 |
sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); |
1181 |
} |
1182 |
|
1183 |
delete pkt; |
1184 |
} |
1185 |
} |
1186 |
} |
1187 |
|
1188 |
bool |
1189 |
vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
1190 |
{ |
1191 |
int client = ntohl (si.host); |
1192 |
|
1193 |
assert (0 < client && client <= conns.size ()); |
1194 |
|
1195 |
connection *c = conns [client - 1]; |
1196 |
|
1197 |
if (!c->dns) |
1198 |
c->dns = new dns_connection (c); |
1199 |
|
1200 |
if (c->dns->snddq.put (pkt)) |
1201 |
c->dns->tw (); |
1202 |
|
1203 |
// always return true even if the buffer overflows |
1204 |
return true; |
1205 |
} |
1206 |
|
1207 |
void |
1208 |
connection::dnsv4_reset_connection () |
1209 |
{ |
1210 |
//delete dns; dns = 0; //TODO |
1211 |
} |
1212 |
|
1213 |
#define NEXT(w) do { if (next > (w)) next = w; } while (0) |
1214 |
|
1215 |
void |
1216 |
dns_connection::time_cb (ev::timer &w, int revents) |
1217 |
{ |
1218 |
// servers have to be polled |
1219 |
if (THISNODE->dns_port) |
1220 |
return; |
1221 |
|
1222 |
// check for timeouts and (re)transmit |
1223 |
tstamp next = ev::now () + poll_interval; |
1224 |
dns_snd *send = 0; |
1225 |
|
1226 |
for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); |
1227 |
i != vpn->dns_sndpq.end (); |
1228 |
++i) |
1229 |
{ |
1230 |
dns_snd *r = *i; |
1231 |
|
1232 |
if (r->timeout <= ev_now ()) |
1233 |
{ |
1234 |
if (!send) |
1235 |
{ |
1236 |
send = r; |
1237 |
|
1238 |
r->retry++; |
1239 |
r->timeout = ev_now () + (r->retry * min_latency * conf.dns_timeout_factor); |
1240 |
//printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - ev_now ());//D |
1241 |
|
1242 |
// the following code changes the query section a bit, forcing |
1243 |
// the forwarder to generate a new request |
1244 |
if (r->stdhdr) |
1245 |
encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry); |
1246 |
} |
1247 |
} |
1248 |
else |
1249 |
NEXT (r->timeout); |
1250 |
} |
1251 |
|
1252 |
if (!send) |
1253 |
{ |
1254 |
// generate a new packet, if wise |
1255 |
|
1256 |
if (!established) |
1257 |
{ |
1258 |
if (vpn->dns_sndpq.empty ()) |
1259 |
{ |
1260 |
send = new dns_snd (this); |
1261 |
|
1262 |
cfg.reset (THISNODE->id); |
1263 |
send->gen_syn_req (); |
1264 |
} |
1265 |
} |
1266 |
else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding |
1267 |
&& !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) |
1268 |
{ |
1269 |
if (last_sent + send_interval <= ev_now ()) |
1270 |
{ |
1271 |
//printf ("sending data request etc.\n"); //D |
1272 |
if (!snddq.empty () || last_received + 1. > ev_now ()) |
1273 |
{ |
1274 |
poll_interval = send_interval; |
1275 |
NEXT (ev_now () + send_interval); |
1276 |
} |
1277 |
|
1278 |
send = new dns_snd (this); |
1279 |
send->gen_stream_req (sndseq, snddq); |
1280 |
send->timeout = ev_now () + min_latency * conf.dns_timeout_factor; |
1281 |
//printf ("SEND %x (%f)\n", send->seqno, send->timeout - ev_now (), min_latency, conf.dns_timeout_factor);//D |
1282 |
|
1283 |
sndseq = (sndseq + 1) & SEQNO_MASK; |
1284 |
} |
1285 |
else |
1286 |
NEXT (last_sent + send_interval); |
1287 |
} |
1288 |
|
1289 |
if (send) |
1290 |
vpn->dns_sndpq.push_back (send); |
1291 |
} |
1292 |
|
1293 |
if (send) |
1294 |
{ |
1295 |
last_sent = ev_now (); |
1296 |
sendto (vpn->dnsv4_fd, |
1297 |
send->pkt->at (0), send->pkt->len, 0, |
1298 |
vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); |
1299 |
} |
1300 |
|
1301 |
slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)", |
1302 |
poll_interval, send_interval, next - ev_now (), |
1303 |
vpn->dns_sndpq.size (), snddq.size (), |
1304 |
rcvpq.size ()); |
1305 |
|
1306 |
// TODO: no idea when this happens, but when next < ev_now (), we have a problem |
1307 |
// doesn't seem to happen anymore |
1308 |
if (next < ev_now () + 0.001) |
1309 |
next = ev_now () + 0.1; |
1310 |
|
1311 |
w.start (next - ev_now ()); |
1312 |
} |
1313 |
|
1314 |
#endif |
1315 |
|