1 | /* |
1 | /* |
2 | vpn_dns.C -- handle the dns tunnel part of the protocol. |
2 | vpn_dns.C -- handle the dns tunnel part of the protocol. |
3 | Copyright (C) 2003-2004 Marc Lehmann <pcg@goof.com> |
3 | Copyright (C) 2003-2005 Marc Lehmann <gvpe@schmorp.de> |
4 | |
4 | |
|
|
5 | This file is part of GVPE. |
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|
6 | |
5 | This program is free software; you can redistribute it and/or modify |
7 | GVPE is free software; you can redistribute it and/or modify |
6 | it under the terms of the GNU General Public License as published by |
8 | it under the terms of the GNU General Public License as published by |
7 | the Free Software Foundation; either version 2 of the License, or |
9 | the Free Software Foundation; either version 2 of the License, or |
8 | (at your option) any later version. |
10 | (at your option) any later version. |
9 | |
11 | |
10 | This program is distributed in the hope that it will be useful, |
12 | This program is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | GNU General Public License for more details. |
15 | GNU General Public License for more details. |
14 | |
16 | |
15 | You should have received a copy of the GNU General Public License |
17 | You should have received a copy of the GNU General Public License |
16 | along with this program; if not, write to the Free Software |
18 | along with gvpe; if not, write to the Free Software |
17 | Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
19 | Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
18 | */ |
20 | */ |
19 | |
21 | |
20 | #include "config.h" |
22 | #include "config.h" |
21 | |
23 | |
… | |
… | |
23 | |
25 | |
24 | // dns processing is EXTREMELY ugly. For obvious(?) reasons. |
26 | // dns processing is EXTREMELY ugly. For obvious(?) reasons. |
25 | // it's a hack, use only in emergency situations please. |
27 | // it's a hack, use only in emergency situations please. |
26 | |
28 | |
27 | #include <cstring> |
29 | #include <cstring> |
|
|
30 | #include <cassert> |
28 | |
31 | |
29 | #include <sys/types.h> |
32 | #include <sys/types.h> |
30 | #include <sys/socket.h> |
33 | #include <sys/socket.h> |
31 | #include <sys/wait.h> |
34 | #include <sys/wait.h> |
32 | #include <sys/uio.h> |
35 | #include <sys/uio.h> |
… | |
… | |
35 | #include <unistd.h> |
38 | #include <unistd.h> |
36 | #include <fcntl.h> |
39 | #include <fcntl.h> |
37 | |
40 | |
38 | #include <map> |
41 | #include <map> |
39 | |
42 | |
|
|
43 | #include <gmp.h> |
|
|
44 | |
40 | #include "netcompat.h" |
45 | #include "netcompat.h" |
41 | |
46 | |
42 | #include "vpn.h" |
47 | #include "vpn.h" |
43 | |
48 | |
44 | #if ENABLE_HTTP_PROXY |
49 | #define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data |
45 | # include "conf.h" |
50 | #define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data |
|
|
51 | #define ACTIVITY_INTERVAL 5. |
|
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52 | |
|
|
53 | #define INITIAL_TIMEOUT 0.1 // retry timeouts |
|
|
54 | #define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn |
|
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55 | |
|
|
56 | #define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests |
|
|
57 | #define MAX_SEND_INTERVAL 0.5 // optimistic? |
|
|
58 | |
|
|
59 | #define MAX_OUTSTANDING 10 // max. outstanding requests |
|
|
60 | #define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog |
|
|
61 | #define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE |
|
|
62 | |
|
|
63 | #define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well |
|
|
64 | // 240 leaves about 4 bytes of server reply data |
|
|
65 | // every two request bytes less give room for one reply byte |
|
|
66 | |
|
|
67 | #define SEQNO_MASK 0x3fff |
|
|
68 | #define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) |
|
|
69 | |
|
|
70 | #define MAX_LBL_SIZE 63 |
|
|
71 | #define MAX_PKT_SIZE 512 |
|
|
72 | |
|
|
73 | #define RR_TYPE_A 1 |
|
|
74 | #define RR_TYPE_NULL 10 |
|
|
75 | #define RR_TYPE_TXT 16 |
|
|
76 | #define RR_TYPE_ANY 255 |
|
|
77 | |
|
|
78 | #define RR_CLASS_IN 1 |
|
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79 | |
|
|
80 | #define CMD_IP_1 207 |
|
|
81 | #define CMD_IP_2 46 |
|
|
82 | #define CMD_IP_3 236 |
|
|
83 | #define CMD_IP_RST 29 |
|
|
84 | #define CMD_IP_SYN 113 |
|
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85 | #define CMD_IP_REJ 32 |
|
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86 | |
|
|
87 | // works for cmaps up to 255 (not 256!) |
|
|
88 | struct charmap |
|
|
89 | { |
|
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90 | enum { INVALID = (u8)255 }; |
|
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91 | |
|
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92 | char encode [256]; // index => char |
|
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93 | u8 decode [256]; // char => index |
|
|
94 | unsigned int size; |
|
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95 | |
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96 | charmap (const char *cmap); |
|
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97 | }; |
|
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98 | |
|
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99 | charmap::charmap (const char *cmap) |
|
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100 | { |
|
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101 | char *enc = encode; |
|
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102 | u8 *dec = decode; |
|
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103 | |
|
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104 | memset (enc, (char) 0, 256); |
|
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105 | memset (dec, (char)INVALID, 256); |
|
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106 | |
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107 | for (size = 0; cmap [size]; size++) |
|
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108 | { |
|
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109 | enc [size] = cmap [size]; |
|
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110 | dec [(u8)enc [size]] = size; |
|
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111 | } |
|
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112 | |
|
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113 | assert (size < 256); |
|
|
114 | } |
|
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115 | |
|
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116 | #define MAX_DEC_LEN 500 |
|
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117 | #define MAX_ENC_LEN (MAX_DEC_LEN * 2) |
|
|
118 | #define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS) |
|
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119 | |
|
|
120 | // ugly. minimum base is 16(!) |
|
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121 | struct basecoder |
|
|
122 | { |
|
|
123 | charmap cmap; |
|
|
124 | unsigned int enc_len [MAX_DEC_LEN]; |
|
|
125 | unsigned int dec_len [MAX_ENC_LEN]; |
|
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126 | |
|
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127 | unsigned int encode_len (unsigned int len); |
|
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128 | unsigned int decode_len (unsigned int len); |
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129 | |
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130 | unsigned int encode (char *dst, u8 *src, unsigned int len); |
|
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131 | unsigned int decode (u8 *dst, char *src, unsigned int len); |
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132 | |
|
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133 | basecoder (const char *cmap); |
|
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134 | }; |
|
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135 | |
|
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136 | basecoder::basecoder (const char *cmap) |
|
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137 | : cmap (cmap) |
|
|
138 | { |
|
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139 | for (unsigned int len = 0; len < MAX_DEC_LEN; ++len) |
|
|
140 | { |
|
|
141 | u8 src [MAX_DEC_LEN]; |
|
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142 | u8 dst [MAX_ENC_LEN]; |
|
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143 | |
|
|
144 | memset (src, 255, len); |
|
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145 | |
|
|
146 | mp_limb_t m [MAX_LIMBS]; |
|
|
147 | mp_size_t n; |
|
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148 | |
|
|
149 | n = mpn_set_str (m, src, len, 256); |
|
|
150 | n = mpn_get_str (dst, this->cmap.size, m, n); |
|
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151 | |
|
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152 | for (int i = 0; !dst [i]; ++i) |
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153 | n--; |
|
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154 | |
|
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155 | enc_len [len] = n; |
|
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156 | dec_len [n] = len; |
|
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157 | } |
|
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158 | } |
|
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159 | |
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160 | unsigned int basecoder::encode_len (unsigned int len) |
|
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161 | { |
|
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162 | return enc_len [len]; |
|
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163 | } |
|
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164 | |
|
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165 | unsigned int basecoder::decode_len (unsigned int len) |
|
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166 | { |
|
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167 | while (len && !dec_len [len]) |
|
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168 | --len; |
|
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169 | |
|
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170 | return dec_len [len]; |
|
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171 | } |
|
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172 | |
|
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173 | unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) |
|
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174 | { |
|
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175 | if (!len || len > MAX_DEC_LEN) |
|
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176 | return 0; |
|
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177 | |
|
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178 | int elen = encode_len (len); |
|
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179 | |
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180 | mp_limb_t m [MAX_LIMBS]; |
|
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181 | mp_size_t n; |
|
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182 | |
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183 | u8 dst_ [MAX_ENC_LEN]; |
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184 | |
|
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185 | n = mpn_set_str (m, src, len, 256); |
|
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186 | n = mpn_get_str (dst_, cmap.size, m, n); |
|
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187 | |
|
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188 | int plen = elen; // for padding |
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189 | |
|
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190 | while (n < plen) |
|
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191 | { |
|
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192 | *dst++ = cmap.encode [0]; |
|
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193 | plen--; |
|
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194 | } |
|
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195 | |
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196 | for (unsigned int i = n - plen; i < n; ++i) |
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197 | *dst++ = cmap.encode [dst_ [i]]; |
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198 | |
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199 | return elen; |
|
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200 | } |
|
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201 | |
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202 | unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) |
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203 | { |
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204 | if (!len || len > MAX_ENC_LEN) |
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205 | return 0; |
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206 | |
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207 | u8 src_ [MAX_ENC_LEN]; |
|
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208 | unsigned int elen = 0; |
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209 | |
|
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210 | while (len--) |
|
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211 | { |
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212 | u8 val = cmap.decode [(u8)*src++]; |
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213 | |
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214 | if (val != charmap::INVALID) |
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215 | src_ [elen++] = val; |
|
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216 | } |
|
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217 | |
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218 | int dlen = decode_len (elen); |
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219 | |
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220 | mp_limb_t m [MAX_LIMBS]; |
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221 | mp_size_t n; |
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222 | |
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223 | u8 dst_ [MAX_DEC_LEN]; |
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224 | |
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225 | n = mpn_set_str (m, src_, elen, cmap.size); |
|
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226 | n = mpn_get_str (dst_, 256, m, n); |
|
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227 | |
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228 | if (n < dlen) |
|
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229 | { |
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230 | memset (dst, 0, dlen - n); |
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231 | memcpy (dst + dlen - n, dst_, n); |
|
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232 | } |
|
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233 | else |
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234 | memcpy (dst, dst_ + n - dlen, dlen); |
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235 | |
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236 | return dlen; |
|
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237 | } |
|
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238 | |
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239 | #if 0 |
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240 | struct test { test (); } test; |
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241 | |
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242 | test::test () |
|
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243 | { |
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244 | basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz"); |
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245 | |
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246 | u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz"; |
|
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247 | static char enc[200]; |
|
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248 | static u8 dec[200]; |
|
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249 | |
|
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250 | for (int i = 1; i < 20; i++) |
|
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251 | { |
|
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252 | int elen = cdc.encode (enc, in, i); |
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253 | int dlen = cdc.decode (dec, enc, elen); |
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254 | |
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255 | printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec); |
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256 | } |
|
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257 | abort (); |
|
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258 | } |
46 | #endif |
259 | #endif |
47 | |
260 | |
48 | #define MIN_RETRY 1. |
261 | //static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-"); |
49 | #define MAX_RETRY 60. |
262 | //static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
|
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263 | static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
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264 | //static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet |
|
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265 | static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); |
50 | |
266 | |
51 | #define SERVER conf.dns_port |
267 | ///////////////////////////////////////////////////////////////////////////// |
52 | |
268 | |
53 | /* |
269 | #define HDRSIZE 6 |
54 | |
270 | |
55 | protocol, in shorthand :) |
271 | inline void encode_header (char *data, int clientid, int seqno, int retry = 0) |
|
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272 | { |
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273 | seqno &= SEQNO_MASK; |
56 | |
274 | |
57 | <cseqno> ANY? poll for more data |
275 | u8 hdr[3] = { |
58 | => TXT <sseqno><data> |
276 | clientid, |
59 | <cseqno><data> TXT? send more data |
277 | (seqno >> 8) | (retry << 6), |
60 | => TXT <empty> |
278 | seqno, |
|
|
279 | }; |
61 | |
280 | |
62 | sequence numbers are 12 bit, 9 bit packet-number and 3 bit fragment id (7 |
281 | assert (clientid < 256); |
63 | - id, actually) last fragment is sent first, however |
|
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64 | |
282 | |
65 | */ |
283 | cdc26.encode (data, hdr, 3); |
|
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284 | } |
|
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285 | |
|
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286 | inline void decode_header (char *data, int &clientid, int &seqno) |
|
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287 | { |
|
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288 | u8 hdr[3]; |
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289 | |
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290 | cdc26.decode (hdr, data, HDRSIZE); |
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291 | |
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292 | clientid = hdr[0]; |
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293 | seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK; |
|
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294 | } |
|
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295 | |
|
|
296 | ///////////////////////////////////////////////////////////////////////////// |
|
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297 | |
|
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298 | struct byte_stream |
|
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299 | { |
|
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300 | u8 *data; |
|
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301 | int maxsize; |
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302 | int fill; |
|
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303 | |
|
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304 | byte_stream (int maxsize); |
|
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305 | ~byte_stream (); |
|
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306 | |
|
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307 | bool empty () { return !fill; } |
|
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308 | int size () { return fill; } |
|
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309 | |
|
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310 | bool put (u8 *data, unsigned int datalen); |
|
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311 | bool put (vpn_packet *pkt); |
|
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312 | vpn_packet *get (); |
|
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313 | |
|
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314 | u8 *begin () { return data; } |
|
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315 | void remove (int count); |
|
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316 | }; |
|
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317 | |
|
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318 | byte_stream::byte_stream (int maxsize) |
|
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319 | : maxsize (maxsize), fill (0) |
|
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320 | { |
|
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321 | data = new u8 [maxsize]; |
|
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322 | } |
|
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323 | |
|
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324 | byte_stream::~byte_stream () |
|
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325 | { |
|
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326 | delete data; |
|
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327 | } |
|
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328 | |
|
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329 | void byte_stream::remove (int count) |
|
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330 | { |
|
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331 | if (count > fill) |
|
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332 | assert (count <= fill); |
|
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333 | |
|
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334 | memmove (data, data + count, fill -= count); |
|
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335 | } |
|
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336 | |
|
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337 | bool byte_stream::put (u8 *data, unsigned int datalen) |
|
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338 | { |
|
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339 | if (maxsize - fill < datalen) |
|
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340 | return false; |
|
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341 | |
|
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342 | memcpy (this->data + fill, data, datalen); fill += datalen; |
|
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343 | |
|
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344 | return true; |
|
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345 | } |
|
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346 | |
|
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347 | bool byte_stream::put (vpn_packet *pkt) |
|
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348 | { |
|
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349 | if (maxsize - fill < pkt->len + 2) |
|
|
350 | return false; |
|
|
351 | |
|
|
352 | data [fill++] = pkt->len >> 8; |
|
|
353 | data [fill++] = pkt->len; |
|
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354 | |
|
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355 | memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len; |
|
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356 | |
|
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357 | return true; |
|
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358 | } |
|
|
359 | |
|
|
360 | vpn_packet *byte_stream::get () |
|
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361 | { |
|
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362 | unsigned int len; |
|
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363 | |
|
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364 | for (;;) |
|
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365 | { |
|
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366 | len = (data [0] << 8) | data [1]; |
|
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367 | |
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368 | if (len <= MAXSIZE || fill < 2) |
|
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369 | break; |
|
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370 | |
|
|
371 | // TODO: handle this better than skipping, e.g. by reset |
|
|
372 | slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte...")); |
|
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373 | remove (1); |
|
|
374 | } |
|
|
375 | |
|
|
376 | if (fill < len + 2) |
|
|
377 | return 0; |
|
|
378 | |
|
|
379 | vpn_packet *pkt = new vpn_packet; |
|
|
380 | |
|
|
381 | pkt->len = len; |
|
|
382 | memcpy (pkt->at (0), data + 2, len); |
|
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383 | remove (len + 2); |
|
|
384 | |
|
|
385 | return pkt; |
|
|
386 | } |
|
|
387 | |
|
|
388 | ///////////////////////////////////////////////////////////////////////////// |
|
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389 | |
|
|
390 | #define FLAG_QUERY ( 0 << 15) |
|
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391 | #define FLAG_RESPONSE ( 1 << 15) |
|
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392 | #define FLAG_OP_MASK (15 << 11) |
|
|
393 | #define FLAG_OP_QUERY ( 0 << 11) |
|
|
394 | #define FLAG_AA ( 1 << 10) |
|
|
395 | #define FLAG_TC ( 1 << 9) |
|
|
396 | #define FLAG_RD ( 1 << 8) |
|
|
397 | #define FLAG_RA ( 1 << 7) |
|
|
398 | #define FLAG_AUTH ( 1 << 5) |
|
|
399 | #define FLAG_RCODE_MASK (15 << 0) |
|
|
400 | #define FLAG_RCODE_OK ( 0 << 0) |
|
|
401 | #define FLAG_RCODE_FORMERR ( 1 << 0) |
|
|
402 | #define FLAG_RCODE_SERVFAIL ( 2 << 0) |
|
|
403 | #define FLAG_RCODE_NXDOMAIN ( 3 << 0) |
|
|
404 | #define FLAG_RCODE_REFUSED ( 5 << 0) |
|
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405 | |
|
|
406 | #define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) |
|
|
407 | #define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) |
|
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408 | |
|
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409 | struct dns_cfg |
|
|
410 | { |
|
|
411 | static int next_uid; |
|
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412 | |
|
|
413 | u8 id1, id2, id3, id4; |
|
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414 | u8 version; |
|
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415 | u8 rrtype; |
|
|
416 | u8 flags; |
|
|
417 | u8 def_ttl; |
|
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418 | u8 rcv_cdc; |
|
|
419 | u8 snd_cdc; |
|
|
420 | u16 max_size; |
|
|
421 | u16 client; |
|
|
422 | u16 uid; // to make request unique |
|
|
423 | |
|
|
424 | u8 reserved[8]; |
|
|
425 | |
|
|
426 | void reset (int clientid); |
|
|
427 | bool valid (); |
|
|
428 | }; |
|
|
429 | |
|
|
430 | int dns_cfg::next_uid; |
|
|
431 | |
|
|
432 | void dns_cfg::reset (int clientid) |
|
|
433 | { |
|
|
434 | id1 = 'G'; |
|
|
435 | id2 = 'V'; |
|
|
436 | id3 = 'P'; |
|
|
437 | id4 = 'E'; |
|
|
438 | |
|
|
439 | version = 1; |
|
|
440 | |
|
|
441 | rrtype = RR_TYPE_TXT; |
|
|
442 | flags = 0; |
|
|
443 | def_ttl = 1; |
|
|
444 | rcv_cdc = 0; |
|
|
445 | snd_cdc = 62; |
|
|
446 | max_size = ntohs (MAX_PKT_SIZE); |
|
|
447 | client = ntohs (clientid); |
|
|
448 | uid = next_uid++; |
|
|
449 | |
|
|
450 | memset (reserved, 0, 8); |
|
|
451 | } |
|
|
452 | |
|
|
453 | bool dns_cfg::valid () |
|
|
454 | { |
|
|
455 | return id1 == 'G' |
|
|
456 | && id2 == 'V' |
|
|
457 | && id3 == 'P' |
|
|
458 | && id4 == 'E' |
|
|
459 | && version == 1 |
|
|
460 | && flags == 0 |
|
|
461 | && rcv_cdc == 0 |
|
|
462 | && snd_cdc == 62 |
|
|
463 | && max_size == ntohs (MAX_PKT_SIZE); |
|
|
464 | } |
|
|
465 | |
|
|
466 | struct dns_packet : net_packet |
|
|
467 | { |
|
|
468 | u16 id; |
|
|
469 | u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 |
|
|
470 | u16 qdcount, ancount, nscount, arcount; |
|
|
471 | |
|
|
472 | u8 data[MAXSIZE - 6 * 2]; |
|
|
473 | |
|
|
474 | int decode_label (char *data, int size, int &offs); |
|
|
475 | }; |
|
|
476 | |
|
|
477 | int dns_packet::decode_label (char *data, int size, int &offs) |
|
|
478 | { |
|
|
479 | char *orig = data; |
|
|
480 | |
|
|
481 | memset (data, 0, size); |
|
|
482 | |
|
|
483 | while (offs < size - 1) |
|
|
484 | { |
|
|
485 | u8 len = (*this)[offs++]; |
|
|
486 | |
|
|
487 | if (!len) |
|
|
488 | break; |
|
|
489 | else if (len < 64) |
|
|
490 | { |
|
|
491 | if (size < len + 1 || offs + len >= MAXSIZE - 1) |
|
|
492 | break; |
|
|
493 | |
|
|
494 | memcpy (data, &((*this)[offs]), len); |
|
|
495 | |
|
|
496 | data += len; size -= len; offs += len; |
|
|
497 | *data++ = '.'; size--; |
|
|
498 | } |
|
|
499 | else |
|
|
500 | { |
|
|
501 | int offs2 = ((len & 63) << 8) + (*this)[offs++]; |
|
|
502 | |
|
|
503 | data += decode_label (data, size, offs2); |
|
|
504 | break; |
|
|
505 | } |
|
|
506 | } |
|
|
507 | |
|
|
508 | return data - orig; |
|
|
509 | } |
|
|
510 | |
|
|
511 | ///////////////////////////////////////////////////////////////////////////// |
|
|
512 | |
|
|
513 | static u16 dns_id = 0; // TODO: should be per-vpn |
|
|
514 | |
|
|
515 | static u16 next_id () |
|
|
516 | { |
|
|
517 | if (!dns_id) |
|
|
518 | dns_id = time (0); |
|
|
519 | |
|
|
520 | // the simplest lsfr with periodicity 65535 i could find |
|
|
521 | dns_id = (dns_id << 1) |
|
|
522 | | (((dns_id >> 1) |
|
|
523 | ^ (dns_id >> 2) |
|
|
524 | ^ (dns_id >> 4) |
|
|
525 | ^ (dns_id >> 15)) & 1); |
|
|
526 | |
|
|
527 | return dns_id; |
|
|
528 | } |
|
|
529 | |
|
|
530 | struct dns_rcv; |
|
|
531 | struct dns_snd; |
|
|
532 | |
|
|
533 | struct dns_connection |
|
|
534 | { |
|
|
535 | connection *c; |
|
|
536 | struct vpn *vpn; |
|
|
537 | |
|
|
538 | dns_cfg cfg; |
|
|
539 | |
|
|
540 | bool established; |
|
|
541 | |
|
|
542 | tstamp last_received; |
|
|
543 | tstamp last_sent; |
|
|
544 | double last_latency; |
|
|
545 | double poll_interval, send_interval; |
|
|
546 | |
|
|
547 | vector<dns_rcv *> rcvpq; |
|
|
548 | |
|
|
549 | byte_stream rcvdq; int rcvseq; |
|
|
550 | byte_stream snddq; int sndseq; |
|
|
551 | |
|
|
552 | void time_cb (time_watcher &w); time_watcher tw; |
|
|
553 | void receive_rep (dns_rcv *r); |
|
|
554 | |
|
|
555 | dns_connection (connection *c); |
|
|
556 | ~dns_connection (); |
|
|
557 | }; |
|
|
558 | |
|
|
559 | struct dns_snd |
|
|
560 | { |
|
|
561 | dns_packet *pkt; |
|
|
562 | tstamp timeout, sent; |
|
|
563 | int retry; |
|
|
564 | struct dns_connection *dns; |
|
|
565 | int seqno; |
|
|
566 | bool stdhdr; |
|
|
567 | |
|
|
568 | void gen_stream_req (int seqno, byte_stream &stream); |
|
|
569 | void gen_syn_req (); |
|
|
570 | |
|
|
571 | dns_snd (dns_connection *dns); |
|
|
572 | ~dns_snd (); |
|
|
573 | }; |
|
|
574 | |
|
|
575 | dns_snd::dns_snd (dns_connection *dns) |
|
|
576 | : dns (dns) |
|
|
577 | { |
|
|
578 | timeout = 0; |
|
|
579 | retry = 0; |
|
|
580 | seqno = 0; |
|
|
581 | sent = NOW; |
|
|
582 | stdhdr = false; |
|
|
583 | |
|
|
584 | pkt = new dns_packet; |
|
|
585 | |
|
|
586 | pkt->id = next_id (); |
|
|
587 | } |
|
|
588 | |
|
|
589 | dns_snd::~dns_snd () |
|
|
590 | { |
|
|
591 | delete pkt; |
|
|
592 | } |
|
|
593 | |
|
|
594 | static void append_domain (dns_packet &pkt, int &offs, const char *domain) |
|
|
595 | { |
|
|
596 | // add tunnel domain |
|
|
597 | for (;;) |
|
|
598 | { |
|
|
599 | const char *end = strchr (domain, '.'); |
|
|
600 | |
|
|
601 | if (!end) |
|
|
602 | end = domain + strlen (domain); |
|
|
603 | |
|
|
604 | int len = end - domain; |
|
|
605 | |
|
|
606 | pkt [offs++] = len; |
|
|
607 | memcpy (pkt.at (offs), domain, len); |
|
|
608 | offs += len; |
|
|
609 | |
|
|
610 | if (!*end) |
|
|
611 | break; |
|
|
612 | |
|
|
613 | domain = end + 1; |
|
|
614 | } |
|
|
615 | } |
|
|
616 | |
|
|
617 | void dns_snd::gen_stream_req (int seqno, byte_stream &stream) |
|
|
618 | { |
|
|
619 | stdhdr = true; |
|
|
620 | this->seqno = seqno; |
|
|
621 | |
|
|
622 | timeout = NOW + INITIAL_TIMEOUT; |
|
|
623 | |
|
|
624 | pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
|
|
625 | pkt->qdcount = htons (1); |
|
|
626 | |
|
|
627 | int offs = 6*2; |
|
|
628 | int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2); |
|
|
629 | // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, |
|
|
630 | // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra |
|
|
631 | |
|
|
632 | char enc[256], *encp = enc; |
|
|
633 | encode_header (enc, THISNODE->id, seqno); |
|
|
634 | |
|
|
635 | int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); |
|
|
636 | |
|
|
637 | if (datalen > stream.size ()) |
|
|
638 | datalen = stream.size (); |
|
|
639 | |
|
|
640 | int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; |
|
|
641 | stream.remove (datalen); |
|
|
642 | |
|
|
643 | while (enclen) |
|
|
644 | { |
|
|
645 | int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; |
|
|
646 | |
|
|
647 | (*pkt)[offs++] = lbllen; |
|
|
648 | memcpy (pkt->at (offs), encp, lbllen); |
|
|
649 | |
|
|
650 | offs += lbllen; |
|
|
651 | encp += lbllen; |
|
|
652 | |
|
|
653 | enclen -= lbllen; |
|
|
654 | } |
|
|
655 | |
|
|
656 | append_domain (*pkt, offs, dns->c->conf->domain); |
|
|
657 | |
|
|
658 | (*pkt)[offs++] = 0; |
|
|
659 | (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; |
|
|
660 | (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
|
|
661 | |
|
|
662 | pkt->len = offs; |
|
|
663 | } |
|
|
664 | |
|
|
665 | void dns_snd::gen_syn_req () |
|
|
666 | { |
|
|
667 | timeout = NOW + INITIAL_SYN_TIMEOUT; |
|
|
668 | |
|
|
669 | pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
|
|
670 | pkt->qdcount = htons (1); |
|
|
671 | |
|
|
672 | int offs = 6 * 2; |
|
|
673 | |
|
|
674 | int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg)); |
|
|
675 | |
|
|
676 | assert (elen <= MAX_LBL_SIZE); |
|
|
677 | |
|
|
678 | (*pkt)[offs] = elen; |
|
|
679 | offs += elen + 1; |
|
|
680 | append_domain (*pkt, offs, dns->c->conf->domain); |
|
|
681 | |
|
|
682 | (*pkt)[offs++] = 0; |
|
|
683 | (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; |
|
|
684 | (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
|
|
685 | |
|
|
686 | pkt->len = offs; |
|
|
687 | } |
|
|
688 | |
|
|
689 | struct dns_rcv |
|
|
690 | { |
|
|
691 | int seqno; |
|
|
692 | dns_packet *pkt; // reply packet |
|
|
693 | u8 data [MAXSIZE]; // actually part of the reply packet... |
|
|
694 | int datalen; |
|
|
695 | |
|
|
696 | dns_rcv (int seqno, u8 *data, int datalen); |
|
|
697 | ~dns_rcv (); |
|
|
698 | }; |
|
|
699 | |
|
|
700 | dns_rcv::dns_rcv (int seqno, u8 *data, int datalen) |
|
|
701 | : seqno (seqno), pkt (new dns_packet), datalen (datalen) |
|
|
702 | { |
|
|
703 | memcpy (this->data, data, datalen); |
|
|
704 | } |
|
|
705 | |
|
|
706 | dns_rcv::~dns_rcv () |
|
|
707 | { |
|
|
708 | delete pkt; |
|
|
709 | } |
|
|
710 | |
|
|
711 | ///////////////////////////////////////////////////////////////////////////// |
|
|
712 | |
|
|
713 | dns_connection::dns_connection (connection *c) |
|
|
714 | : c (c) |
|
|
715 | , rcvdq (MAX_BACKLOG * 2) |
|
|
716 | , snddq (MAX_BACKLOG * 2) |
|
|
717 | , tw (this, &dns_connection::time_cb) |
|
|
718 | { |
|
|
719 | vpn = c->vpn; |
|
|
720 | |
|
|
721 | established = false; |
|
|
722 | |
|
|
723 | rcvseq = sndseq = 0; |
|
|
724 | |
|
|
725 | last_sent = last_received = 0; |
|
|
726 | poll_interval = MIN_POLL_INTERVAL; |
|
|
727 | send_interval = 0.5; // starting rate |
|
|
728 | last_latency = INITIAL_TIMEOUT; |
|
|
729 | } |
|
|
730 | |
|
|
731 | dns_connection::~dns_connection () |
|
|
732 | { |
|
|
733 | for (vector<dns_rcv *>::iterator i = rcvpq.begin (); |
|
|
734 | i != rcvpq.end (); |
|
|
735 | ++i) |
|
|
736 | delete *i; |
|
|
737 | } |
|
|
738 | |
|
|
739 | void dns_connection::receive_rep (dns_rcv *r) |
|
|
740 | { |
|
|
741 | if (r->datalen) |
|
|
742 | { |
|
|
743 | last_received = NOW; |
|
|
744 | tw.trigger (); |
|
|
745 | |
|
|
746 | poll_interval = send_interval; |
|
|
747 | } |
|
|
748 | else |
|
|
749 | { |
|
|
750 | poll_interval *= 1.5; |
|
|
751 | if (poll_interval > MAX_POLL_INTERVAL) |
|
|
752 | poll_interval = MAX_POLL_INTERVAL; |
|
|
753 | } |
|
|
754 | |
|
|
755 | rcvpq.push_back (r); |
|
|
756 | |
|
|
757 | redo: |
|
|
758 | |
|
|
759 | // find next packet |
|
|
760 | for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) |
|
|
761 | if (SEQNO_EQ (rcvseq, (*i)->seqno)) |
|
|
762 | { |
|
|
763 | // enter the packet into our input stream |
|
|
764 | r = *i; |
|
|
765 | |
|
|
766 | // remove the oldest packet, look forward, as it's oldest first |
|
|
767 | for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) |
|
|
768 | if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) |
|
|
769 | { |
|
|
770 | delete *j; |
|
|
771 | rcvpq.erase (j); |
|
|
772 | break; |
|
|
773 | } |
|
|
774 | |
|
|
775 | rcvseq = (rcvseq + 1) & SEQNO_MASK; |
|
|
776 | |
|
|
777 | if (!rcvdq.put (r->data, r->datalen)) |
|
|
778 | { |
|
|
779 | slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)"); |
|
|
780 | abort (); // MUST never overflow, can be caused by data corruption, TODO |
|
|
781 | } |
|
|
782 | |
|
|
783 | while (vpn_packet *pkt = rcvdq.get ()) |
|
|
784 | { |
|
|
785 | sockinfo si; |
|
|
786 | si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4; |
|
|
787 | |
|
|
788 | vpn->recv_vpn_packet (pkt, si); |
|
|
789 | |
|
|
790 | delete pkt; |
|
|
791 | } |
|
|
792 | |
|
|
793 | // check for further packets |
|
|
794 | goto redo; |
|
|
795 | } |
|
|
796 | } |
|
|
797 | |
|
|
798 | void |
|
|
799 | vpn::dnsv4_server (dns_packet &pkt) |
|
|
800 | { |
|
|
801 | u16 flags = ntohs (pkt.flags); |
|
|
802 | |
|
|
803 | int offs = 6 * 2; // skip header |
|
|
804 | |
|
|
805 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
|
|
806 | |
|
|
807 | if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) |
|
|
808 | && pkt.qdcount == htons (1)) |
|
|
809 | { |
|
|
810 | char qname[MAXSIZE]; |
|
|
811 | int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
|
|
812 | |
|
|
813 | u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
|
|
814 | u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
|
|
815 | |
|
|
816 | pkt.qdcount = htons (1); |
|
|
817 | pkt.ancount = 0; |
|
|
818 | pkt.nscount = 0; // should be self, as other nameservers reply like this |
|
|
819 | pkt.arcount = 0; // a record for self, as other nameservers reply like this |
|
|
820 | |
|
|
821 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL); |
|
|
822 | |
|
|
823 | int dlen = strlen (THISNODE->domain); |
|
|
824 | |
|
|
825 | if (qclass == RR_CLASS_IN |
|
|
826 | && qlen > dlen + 1 |
|
|
827 | && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) |
|
|
828 | { |
|
|
829 | // now generate reply |
|
|
830 | pkt.ancount = htons (1); // one answer RR |
|
|
831 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); |
|
|
832 | |
|
|
833 | if ((qtype == RR_TYPE_ANY |
|
|
834 | || qtype == RR_TYPE_TXT |
|
|
835 | || qtype == RR_TYPE_NULL) |
|
|
836 | && qlen > dlen + 1 + HDRSIZE) |
|
|
837 | { |
|
|
838 | // correct class, domain: parse |
|
|
839 | int client, seqno; |
|
|
840 | decode_header (qname, client, seqno); |
|
|
841 | |
|
|
842 | u8 data[MAXSIZE]; |
|
|
843 | int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); |
|
|
844 | |
|
|
845 | if (0 < client && client <= conns.size ()) |
|
|
846 | { |
|
|
847 | connection *c = conns [client - 1]; |
|
|
848 | dns_connection *dns = c->dns; |
|
|
849 | dns_rcv *rcv; |
|
|
850 | bool in_seq; |
|
|
851 | |
|
|
852 | if (dns) |
|
|
853 | { |
|
|
854 | for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) |
|
|
855 | if (SEQNO_EQ ((*i)->seqno, seqno)) |
|
|
856 | { |
|
|
857 | // already seen that request: simply reply with the cached reply |
|
|
858 | dns_rcv *r = *i; |
|
|
859 | |
|
|
860 | slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno); |
|
|
861 | |
|
|
862 | // refresh header & id, as the retry count could have changed |
|
|
863 | memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE); |
|
|
864 | r->pkt->id = pkt.id; |
|
|
865 | |
|
|
866 | memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); |
|
|
867 | |
|
|
868 | goto duplicate_request; |
|
|
869 | } |
|
|
870 | |
|
|
871 | in_seq = dns->rcvseq == seqno; |
|
|
872 | |
|
|
873 | // new packet, queue |
|
|
874 | rcv = new dns_rcv (seqno, data, datalen); |
|
|
875 | dns->receive_rep (rcv); |
|
|
876 | } |
|
|
877 | |
|
|
878 | { |
|
|
879 | pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
|
|
880 | |
|
|
881 | int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; |
|
|
882 | pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type |
|
|
883 | pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
|
|
884 | pkt [offs++] = 0; pkt [offs++] = 0; |
|
|
885 | pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL |
|
|
886 | |
|
|
887 | int rdlen_offs = offs += 2; |
|
|
888 | |
|
|
889 | int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs; |
|
|
890 | // bind doesn't compress well, so reduce further by one label length |
|
|
891 | dlen -= qlen; |
|
|
892 | |
|
|
893 | if (dns) |
|
|
894 | { |
|
|
895 | // only put data into in-order sequence packets, if |
|
|
896 | // we receive out-of-order packets we generate empty |
|
|
897 | // replies |
|
|
898 | while (dlen > 1 && !dns->snddq.empty () && in_seq) |
|
|
899 | { |
|
|
900 | int txtlen = dlen <= 255 ? dlen - 1 : 255; |
|
|
901 | |
|
|
902 | if (txtlen > dns->snddq.size ()) |
|
|
903 | txtlen = dns->snddq.size (); |
|
|
904 | |
|
|
905 | pkt[offs++] = txtlen; |
|
|
906 | memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); |
|
|
907 | offs += txtlen; |
|
|
908 | dns->snddq.remove (txtlen); |
|
|
909 | |
|
|
910 | dlen -= txtlen + 1; |
|
|
911 | } |
|
|
912 | |
|
|
913 | // avoid empty TXT rdata |
|
|
914 | if (offs == rdlen_offs) |
|
|
915 | pkt[offs++] = 0; |
|
|
916 | |
|
|
917 | slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ()); |
|
|
918 | } |
|
|
919 | else |
|
|
920 | { |
|
|
921 | // send RST |
|
|
922 | pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
|
|
923 | pkt [offs++] = CMD_IP_RST; |
|
|
924 | } |
|
|
925 | |
|
|
926 | int rdlen = offs - rdlen_offs; |
|
|
927 | |
|
|
928 | pkt [rdlen_offs - 2] = rdlen >> 8; |
|
|
929 | pkt [rdlen_offs - 1] = rdlen; |
|
|
930 | |
|
|
931 | if (dns) |
|
|
932 | { |
|
|
933 | // now update dns_rcv copy |
|
|
934 | rcv->pkt->len = offs; |
|
|
935 | memcpy (rcv->pkt->at (0), pkt.at (0), offs); |
|
|
936 | } |
|
|
937 | } |
|
|
938 | |
|
|
939 | duplicate_request: ; |
|
|
940 | } |
|
|
941 | else |
|
|
942 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
|
|
943 | } |
|
|
944 | else if (qtype == RR_TYPE_A |
|
|
945 | && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg))) |
|
|
946 | { |
|
|
947 | dns_cfg cfg; |
|
|
948 | cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg))); |
|
|
949 | int client = ntohs (cfg.client); |
|
|
950 | |
|
|
951 | pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
|
|
952 | |
|
|
953 | pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type |
|
|
954 | pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
|
|
955 | pkt [offs++] = 0; pkt [offs++] = 0; |
|
|
956 | pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL |
|
|
957 | pkt [offs++] = 0; pkt [offs++] = 4; // rdlength |
|
|
958 | |
|
|
959 | slog (L_INFO, _("DNS: client %d tries to connect"), client); |
|
|
960 | |
|
|
961 | pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
|
|
962 | pkt [offs++] = CMD_IP_REJ; |
|
|
963 | |
|
|
964 | if (0 < client && client <= conns.size ()) |
|
|
965 | { |
|
|
966 | connection *c = conns [client - 1]; |
|
|
967 | |
|
|
968 | if (cfg.valid ()) |
|
|
969 | { |
|
|
970 | pkt [offs - 1] = CMD_IP_SYN; |
|
|
971 | |
|
|
972 | delete c->dns; |
|
|
973 | c->dns = new dns_connection (c); |
|
|
974 | c->dns->cfg = cfg; |
|
|
975 | } |
|
|
976 | } |
|
|
977 | } |
|
|
978 | } |
|
|
979 | |
|
|
980 | pkt.len = offs; |
|
|
981 | } |
|
|
982 | } |
|
|
983 | |
|
|
984 | void |
|
|
985 | vpn::dnsv4_client (dns_packet &pkt) |
|
|
986 | { |
|
|
987 | u16 flags = ntohs (pkt.flags); |
|
|
988 | int offs = 6 * 2; // skip header |
|
|
989 | |
|
|
990 | pkt.qdcount = ntohs (pkt.qdcount); |
|
|
991 | pkt.ancount = ntohs (pkt.ancount); |
|
|
992 | |
|
|
993 | // go through our request list and find the corresponding request |
|
|
994 | for (vector<dns_snd *>::iterator i = dns_sndpq.begin (); |
|
|
995 | i != dns_sndpq.end (); |
|
|
996 | ++i) |
|
|
997 | if ((*i)->pkt->id == pkt.id) |
|
|
998 | { |
|
|
999 | dns_connection *dns = (*i)->dns; |
|
|
1000 | connection *c = dns->c; |
|
|
1001 | int seqno = (*i)->seqno; |
|
|
1002 | u8 data[MAXSIZE], *datap = data; |
|
|
1003 | |
|
|
1004 | if ((*i)->retry) |
|
|
1005 | { |
|
|
1006 | dns->send_interval *= 1.01; |
|
|
1007 | if (dns->send_interval > MAX_SEND_INTERVAL) |
|
|
1008 | dns->send_interval = MAX_SEND_INTERVAL; |
|
|
1009 | } |
|
|
1010 | else |
|
|
1011 | { |
|
|
1012 | #if 1 |
|
|
1013 | dns->send_interval *= 0.999; |
|
|
1014 | #endif |
|
|
1015 | if (dns->send_interval < MIN_SEND_INTERVAL) |
|
|
1016 | dns->send_interval = MIN_SEND_INTERVAL; |
|
|
1017 | |
|
|
1018 | // the latency surely puts an upper bound on |
|
|
1019 | // the minimum send interval |
|
|
1020 | double latency = NOW - (*i)->sent; |
|
|
1021 | dns->last_latency = latency; |
|
|
1022 | |
|
|
1023 | if (dns->send_interval > latency) |
|
|
1024 | dns->send_interval = latency; |
|
|
1025 | } |
|
|
1026 | |
|
|
1027 | delete *i; |
|
|
1028 | dns_sndpq.erase (i); |
|
|
1029 | |
|
|
1030 | if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK)) |
|
|
1031 | { |
|
|
1032 | char qname[MAXSIZE]; |
|
|
1033 | |
|
|
1034 | while (pkt.qdcount-- && offs < MAXSIZE - 4) |
|
|
1035 | { |
|
|
1036 | int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
|
|
1037 | offs += 4; // skip qtype, qclass |
|
|
1038 | } |
|
|
1039 | |
|
|
1040 | while (pkt.ancount-- && offs < MAXSIZE - 10 && datap) |
|
|
1041 | { |
|
|
1042 | int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
|
|
1043 | |
|
|
1044 | u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
|
|
1045 | u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
|
|
1046 | u32 ttl = pkt [offs++] << 24; |
|
|
1047 | ttl |= pkt [offs++] << 16; |
|
|
1048 | ttl |= pkt [offs++] << 8; |
|
|
1049 | ttl |= pkt [offs++]; |
|
|
1050 | u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; |
|
|
1051 | |
|
|
1052 | if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) |
|
|
1053 | { |
|
|
1054 | if (rdlen <= MAXSIZE - offs) |
|
|
1055 | { |
|
|
1056 | // decode bytes, finally |
|
|
1057 | |
|
|
1058 | while (rdlen) |
|
|
1059 | { |
|
|
1060 | int txtlen = pkt [offs++]; |
|
|
1061 | |
|
|
1062 | assert (txtlen + offs < MAXSIZE - 1); |
|
|
1063 | |
|
|
1064 | memcpy (datap, pkt.at (offs), txtlen); |
|
|
1065 | datap += txtlen; offs += txtlen; |
|
|
1066 | |
|
|
1067 | rdlen -= txtlen + 1; |
|
|
1068 | } |
|
|
1069 | } |
|
|
1070 | } |
|
|
1071 | else if (qtype == RR_TYPE_A) |
|
|
1072 | { |
|
|
1073 | u8 ip [4]; |
|
|
1074 | |
|
|
1075 | ip [0] = pkt [offs++]; |
|
|
1076 | ip [1] = pkt [offs++]; |
|
|
1077 | ip [2] = pkt [offs++]; |
|
|
1078 | ip [3] = pkt [offs++]; |
|
|
1079 | |
|
|
1080 | if (ip [0] == CMD_IP_1 |
|
|
1081 | && ip [1] == CMD_IP_2 |
|
|
1082 | && ip [2] == CMD_IP_3) |
|
|
1083 | { |
|
|
1084 | slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); |
|
|
1085 | |
|
|
1086 | if (ip [3] == CMD_IP_RST) |
|
|
1087 | { |
|
|
1088 | slog (L_DEBUG, _("DNS: got tunnel RST request")); |
|
|
1089 | |
|
|
1090 | delete dns; c->dns = 0; |
|
|
1091 | |
|
|
1092 | return; |
|
|
1093 | } |
|
|
1094 | else if (ip [3] == CMD_IP_SYN) |
|
|
1095 | { |
|
|
1096 | slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); |
|
|
1097 | dns->established = true; |
|
|
1098 | } |
|
|
1099 | else if (ip [3] == CMD_IP_REJ) |
|
|
1100 | { |
|
|
1101 | slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting.")); |
|
|
1102 | abort (); |
|
|
1103 | } |
|
|
1104 | else |
|
|
1105 | slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); |
|
|
1106 | } |
|
|
1107 | else |
|
|
1108 | slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), |
|
|
1109 | ip [0], ip [1], ip [2], ip [3]); |
|
|
1110 | |
|
|
1111 | return; |
|
|
1112 | } |
|
|
1113 | |
|
|
1114 | int client, rseqno; |
|
|
1115 | decode_header (qname, client, rseqno); |
|
|
1116 | |
|
|
1117 | if (client != THISNODE->id) |
|
|
1118 | { |
|
|
1119 | slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring")); |
|
|
1120 | datap = 0; |
|
|
1121 | } |
|
|
1122 | else if (rseqno != seqno) |
|
|
1123 | { |
|
|
1124 | slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?")); |
|
|
1125 | datap = 0; |
|
|
1126 | } |
|
|
1127 | } |
|
|
1128 | } |
|
|
1129 | |
|
|
1130 | // todo: pkt now used |
|
|
1131 | if (datap) |
|
|
1132 | dns->receive_rep (new dns_rcv (seqno, data, datap - data)); |
|
|
1133 | |
|
|
1134 | break; |
|
|
1135 | } |
|
|
1136 | } |
66 | |
1137 | |
67 | void |
1138 | void |
68 | vpn::dnsv4_ev (io_watcher &w, short revents) |
1139 | vpn::dnsv4_ev (io_watcher &w, short revents) |
69 | { |
1140 | { |
70 | if (revents & EVENT_READ) |
1141 | if (revents & EVENT_READ) |
71 | { |
1142 | { |
|
|
1143 | dns_packet *pkt = new dns_packet; |
72 | struct sockaddr_in sa; |
1144 | struct sockaddr_in sa; |
73 | socklen_t sa_len = sizeof (sa); |
1145 | socklen_t sa_len = sizeof (sa); |
74 | int len; |
1146 | |
|
|
1147 | pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); |
|
|
1148 | |
|
|
1149 | if (pkt->len > 0) |
|
|
1150 | { |
|
|
1151 | if (THISNODE->dns_port) |
|
|
1152 | { |
|
|
1153 | dnsv4_server (*pkt); |
|
|
1154 | sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); |
|
|
1155 | } |
|
|
1156 | else |
|
|
1157 | dnsv4_client (*pkt); |
|
|
1158 | |
|
|
1159 | delete pkt; |
|
|
1160 | } |
75 | } |
1161 | } |
76 | } |
1162 | } |
77 | |
1163 | |
78 | bool |
1164 | bool |
79 | vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
1165 | vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
80 | { |
1166 | { |
81 | //return i->send_packet (pkt, tos); |
1167 | int client = ntohs (si.port); |
|
|
1168 | |
|
|
1169 | assert (0 < client && client <= conns.size ()); |
|
|
1170 | |
|
|
1171 | connection *c = conns [client - 1]; |
|
|
1172 | |
|
|
1173 | if (!c->dns) |
|
|
1174 | c->dns = new dns_connection (c); |
|
|
1175 | |
|
|
1176 | if (!c->dns->snddq.put (pkt)) |
|
|
1177 | return false; |
|
|
1178 | |
|
|
1179 | c->dns->tw.trigger (); |
|
|
1180 | |
|
|
1181 | return true; |
|
|
1182 | } |
|
|
1183 | |
|
|
1184 | void |
|
|
1185 | connection::dnsv4_reset_connection () |
|
|
1186 | { |
|
|
1187 | //delete dns; dns = 0; //TODO |
|
|
1188 | } |
|
|
1189 | |
|
|
1190 | #define NEXT(w) do { if (next > (w)) next = w; } while (0) |
|
|
1191 | |
|
|
1192 | void |
|
|
1193 | dns_connection::time_cb (time_watcher &w) |
|
|
1194 | { |
|
|
1195 | // servers have to be polled |
|
|
1196 | if (THISNODE->dns_port) |
|
|
1197 | return; |
|
|
1198 | |
|
|
1199 | // check for timeouts and (re)transmit |
|
|
1200 | tstamp next = NOW + poll_interval; |
|
|
1201 | dns_snd *send = 0; |
|
|
1202 | |
|
|
1203 | for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); |
|
|
1204 | i != vpn->dns_sndpq.end (); |
|
|
1205 | ++i) |
|
|
1206 | { |
|
|
1207 | dns_snd *r = *i; |
|
|
1208 | |
|
|
1209 | if (r->timeout <= NOW) |
|
|
1210 | { |
|
|
1211 | if (!send) |
|
|
1212 | { |
|
|
1213 | send = r; |
|
|
1214 | |
|
|
1215 | r->retry++; |
|
|
1216 | r->timeout = NOW + (r->retry * last_latency * 8.); |
|
|
1217 | |
|
|
1218 | // the following code changes the query section a bit, forcing |
|
|
1219 | // the forwarder to generate a new request |
|
|
1220 | if (r->stdhdr) |
|
|
1221 | { |
|
|
1222 | //printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry); |
|
|
1223 | //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry); |
|
|
1224 | } |
|
|
1225 | } |
|
|
1226 | } |
|
|
1227 | else |
|
|
1228 | NEXT (r->timeout); |
|
|
1229 | } |
|
|
1230 | |
|
|
1231 | if (last_sent + send_interval <= NOW) |
|
|
1232 | { |
|
|
1233 | if (!send) |
|
|
1234 | { |
|
|
1235 | // generate a new packet, if wise |
|
|
1236 | |
|
|
1237 | if (!established) |
|
|
1238 | { |
|
|
1239 | if (vpn->dns_sndpq.empty ()) |
|
|
1240 | { |
|
|
1241 | send = new dns_snd (this); |
|
|
1242 | |
|
|
1243 | cfg.reset (THISNODE->id); |
|
|
1244 | send->gen_syn_req (); |
|
|
1245 | } |
|
|
1246 | } |
|
|
1247 | else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING |
|
|
1248 | && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) |
|
|
1249 | { |
|
|
1250 | //printf ("sending data request etc.\n"); //D |
|
|
1251 | if (!snddq.empty ()) |
|
|
1252 | { |
|
|
1253 | poll_interval = send_interval; |
|
|
1254 | NEXT (NOW + send_interval); |
|
|
1255 | } |
|
|
1256 | |
|
|
1257 | send = new dns_snd (this); |
|
|
1258 | send->gen_stream_req (sndseq, snddq); |
|
|
1259 | send->timeout = NOW + last_latency * 8.; |
|
|
1260 | |
|
|
1261 | sndseq = (sndseq + 1) & SEQNO_MASK; |
|
|
1262 | } |
|
|
1263 | |
|
|
1264 | if (send) |
|
|
1265 | vpn->dns_sndpq.push_back (send); |
|
|
1266 | } |
|
|
1267 | |
|
|
1268 | if (send) |
|
|
1269 | { |
|
|
1270 | last_sent = NOW; |
|
|
1271 | sendto (vpn->dnsv4_fd, |
|
|
1272 | send->pkt->at (0), send->pkt->len, 0, |
|
|
1273 | vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); |
|
|
1274 | } |
|
|
1275 | } |
|
|
1276 | else |
|
|
1277 | NEXT (last_sent + send_interval); |
|
|
1278 | |
|
|
1279 | slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)", |
|
|
1280 | poll_interval, send_interval, next - NOW, |
|
|
1281 | vpn->dns_sndpq.size (), snddq.size ()); |
|
|
1282 | |
|
|
1283 | // TODO: no idea when this happens, but when next < NOW, we have a problem |
|
|
1284 | if (next < NOW + 0.0001) |
|
|
1285 | next = NOW + 0.1; |
|
|
1286 | |
|
|
1287 | w.start (next); |
82 | } |
1288 | } |
83 | |
1289 | |
84 | #endif |
1290 | #endif |
85 | |
1291 | |