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 | |
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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> |
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|
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 |
46 | #endif |
51 | #define ACTIVITY_INTERVAL 5. |
47 | |
52 | |
48 | #define MIN_RETRY 1. |
53 | #define INITIAL_TIMEOUT 0.1 // retry timeouts |
49 | #define MAX_RETRY 60. |
54 | #define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn |
50 | |
55 | |
51 | #define SERVER conf.dns_port |
56 | #define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests |
|
|
57 | #define MAX_SEND_INTERVAL 2. // optimistic? |
52 | |
58 | |
53 | /* |
59 | #define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate |
|
|
60 | #define MAX_OUTSTANDING 100 // max. outstanding requests |
|
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61 | #define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog |
|
|
62 | #define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE |
54 | |
63 | |
55 | protocol, in shorthand :) |
64 | #define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well |
|
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65 | // 240 leaves about 4 bytes of server reply data |
|
|
66 | // every two request bytes less give room for one reply byte |
56 | |
67 | |
57 | client -> server <req> ANY? |
68 | #define SEQNO_MASK 0x3fff |
58 | server -> client <req> TXT <rep> |
69 | #define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) |
59 | |
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60 | <req> is dns64-encoded <client-id:12><recv-seqno:10>[<send-seqno:10><data>] |
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61 | <rep> is dns64-encoded <0:12><recv-seqno:10>[<send-seqno:10><data>] |
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62 | |
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63 | if <client-id> is zero, the connection will be configured: |
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64 | |
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65 | <0:12><0:4>client-id:12><default-ttl:8><max-size:16><flags:16> |
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66 | |
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67 | */ |
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68 | |
70 | |
69 | #define MAX_LBL_SIZE 63 |
71 | #define MAX_LBL_SIZE 63 |
70 | #define MAX_PKT_SIZE 512 |
72 | #define MAX_PKT_SIZE 512 |
71 | |
73 | |
|
|
74 | #define RR_TYPE_A 1 |
|
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75 | #define RR_TYPE_NULL 10 |
72 | #define RR_TYPE_TXT 16 |
76 | #define RR_TYPE_TXT 16 |
73 | #define RR_TYPE_ANY 255 |
77 | #define RR_TYPE_ANY 255 |
|
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78 | |
74 | #define RR_CLASS_IN 1 |
79 | #define RR_CLASS_IN 1 |
75 | |
80 | |
76 | // the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) |
81 | #define CMD_IP_1 207 |
77 | struct dns64 |
82 | #define CMD_IP_2 46 |
78 | { |
83 | #define CMD_IP_3 236 |
79 | static const char encode_chars[64 + 1]; |
84 | #define CMD_IP_RST 29 |
80 | static s8 decode_chars[256]; |
85 | #define CMD_IP_SYN 113 |
|
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86 | #define CMD_IP_REJ 32 |
81 | |
87 | |
82 | static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } |
88 | // works for cmaps up to 255 (not 256!) |
83 | static int decode_len (int bytes) { return (bytes * 6) / 8; } |
89 | struct charmap |
|
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90 | { |
|
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91 | enum { INVALID = (u8)255 }; |
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92 | |
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93 | char encode [256]; // index => char |
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94 | u8 decode [256]; // char => index |
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95 | unsigned int size; |
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96 | |
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97 | charmap (const char *cmap); |
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98 | }; |
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99 | |
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100 | charmap::charmap (const char *cmap) |
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101 | { |
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102 | char *enc = encode; |
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103 | u8 *dec = decode; |
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104 | |
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105 | memset (enc, (char) 0, 256); |
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106 | memset (dec, (char)INVALID, 256); |
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107 | |
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108 | for (size = 0; cmap [size]; size++) |
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109 | { |
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110 | enc [size] = cmap [size]; |
|
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111 | dec [(u8)enc [size]] = size; |
|
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112 | } |
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113 | |
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114 | assert (size < 256); |
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115 | } |
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116 | |
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117 | #define MAX_DEC_LEN 500 |
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118 | #define MAX_ENC_LEN (MAX_DEC_LEN * 2) |
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119 | #define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS) |
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120 | |
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121 | // ugly. minimum base is 16(!) |
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122 | struct basecoder |
|
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123 | { |
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124 | charmap cmap; |
|
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125 | unsigned int enc_len [MAX_DEC_LEN]; |
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126 | unsigned int dec_len [MAX_ENC_LEN]; |
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127 | |
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128 | unsigned int encode_len (unsigned int len); |
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129 | unsigned int decode_len (unsigned int len); |
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130 | |
84 | static void encode (char *dst, u8 *src, int len); |
131 | unsigned int encode (char *dst, u8 *src, unsigned int len); |
85 | static void decode (u8 *dst, char *src, int len); |
132 | unsigned int decode (u8 *dst, char *src, unsigned int len); |
86 | |
133 | |
87 | dns64 (); |
134 | basecoder (const char *cmap); |
88 | } dns64; |
135 | }; |
89 | |
136 | |
90 | const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ"; |
137 | basecoder::basecoder (const char *cmap) |
91 | s8 dns64::decode_chars[256]; |
138 | : cmap (cmap) |
92 | |
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93 | dns64::dns64 () |
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94 | { |
139 | { |
95 | for (int i = 0; i < 64; i++) |
140 | for (unsigned int len = 0; len < MAX_DEC_LEN; ++len) |
96 | decode_chars [encode_chars [i]] = i + 1; |
141 | { |
97 | } |
142 | u8 src [MAX_DEC_LEN]; |
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143 | u8 dst [MAX_ENC_LEN]; |
98 | |
144 | |
99 | void dns64::encode (char *dst, u8 *src, int len) |
145 | memset (src, 255, len); |
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146 | |
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147 | mp_limb_t m [MAX_LIMBS]; |
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148 | mp_size_t n; |
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149 | |
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150 | n = mpn_set_str (m, src, len, 256); |
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151 | n = mpn_get_str (dst, this->cmap.size, m, n); |
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152 | |
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153 | for (int i = 0; !dst [i]; ++i) |
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154 | n--; |
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155 | |
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156 | enc_len [len] = n; |
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157 | dec_len [n] = len; |
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158 | } |
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159 | } |
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160 | |
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161 | unsigned int basecoder::encode_len (unsigned int len) |
100 | { |
162 | { |
101 | // slow, but easy to debug |
163 | return enc_len [len]; |
102 | unsigned int accum, bits = 0; |
164 | } |
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165 | |
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166 | unsigned int basecoder::decode_len (unsigned int len) |
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167 | { |
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168 | while (len && !dec_len [len]) |
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169 | --len; |
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170 | |
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171 | return dec_len [len]; |
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172 | } |
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173 | |
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174 | unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) |
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175 | { |
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176 | if (!len || len > MAX_DEC_LEN) |
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177 | return 0; |
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178 | |
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179 | int elen = encode_len (len); |
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180 | |
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181 | mp_limb_t m [MAX_LIMBS]; |
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182 | mp_size_t n; |
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183 | |
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184 | u8 dst_ [MAX_ENC_LEN]; |
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185 | |
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186 | n = mpn_set_str (m, src, len, 256); |
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187 | n = mpn_get_str (dst_, cmap.size, m, n); |
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188 | |
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189 | int plen = elen; // for padding |
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190 | |
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191 | while (n < plen) |
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192 | { |
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193 | *dst++ = cmap.encode [0]; |
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194 | plen--; |
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195 | } |
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196 | |
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197 | for (unsigned int i = n - plen; i < n; ++i) |
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198 | *dst++ = cmap.encode [dst_ [i]]; |
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199 | |
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200 | return elen; |
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201 | } |
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202 | |
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203 | unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) |
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204 | { |
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205 | if (!len || len > MAX_ENC_LEN) |
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206 | return 0; |
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207 | |
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208 | u8 src_ [MAX_ENC_LEN]; |
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209 | unsigned int elen = 0; |
103 | |
210 | |
104 | while (len--) |
211 | while (len--) |
105 | { |
212 | { |
106 | accum <<= 8; |
213 | u8 val = cmap.decode [(u8)*src++]; |
107 | accum |= *src++; |
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108 | bits += 8; |
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109 | |
214 | |
110 | while (bits >= 6) |
215 | if (val != charmap::INVALID) |
111 | { |
216 | src_ [elen++] = val; |
112 | *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; |
217 | } |
113 | bits -= 6; |
218 | |
114 | } |
219 | int dlen = decode_len (elen); |
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220 | |
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221 | mp_limb_t m [MAX_LIMBS]; |
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222 | mp_size_t n; |
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223 | |
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224 | u8 dst_ [MAX_DEC_LEN]; |
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225 | |
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226 | n = mpn_set_str (m, src_, elen, cmap.size); |
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227 | n = mpn_get_str (dst_, 256, m, n); |
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228 | |
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229 | if (n < dlen) |
115 | } |
230 | { |
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231 | memset (dst, 0, dlen - n); |
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232 | memcpy (dst + dlen - n, dst_, n); |
|
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233 | } |
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234 | else |
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235 | memcpy (dst, dst_ + n - dlen, dlen); |
116 | |
236 | |
117 | if (bits) |
237 | return dlen; |
118 | *dst++ = encode_chars [(accum << (6 - bits)) & 63]; |
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119 | } |
238 | } |
120 | |
239 | |
121 | void dns64::decode (u8 *dst, char *src, int len) |
240 | #if 0 |
122 | { |
241 | struct test { test (); } test; |
123 | // slow, but easy to debug |
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124 | unsigned int accum, bits = 0; |
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125 | |
242 | |
126 | while (len--) |
243 | test::test () |
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244 | { |
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245 | basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz"); |
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246 | |
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247 | u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz"; |
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248 | static char enc[200]; |
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249 | static u8 dec[200]; |
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250 | |
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251 | for (int i = 1; i < 20; i++) |
127 | { |
252 | { |
128 | s8 chr = decode_chars [(u8)*src++]; |
253 | int elen = cdc.encode (enc, in, i); |
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254 | int dlen = cdc.decode (dec, enc, elen); |
129 | |
255 | |
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256 | printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec); |
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257 | } |
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258 | abort (); |
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259 | } |
|
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260 | #endif |
130 | |
261 | |
131 | if (!chr) |
262 | //static basecoder cdc64 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI-"); |
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263 | //static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
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264 | static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); |
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265 | //static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet |
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266 | static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); |
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267 | |
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268 | ///////////////////////////////////////////////////////////////////////////// |
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269 | |
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270 | #define HDRSIZE 6 |
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271 | |
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272 | inline void encode_header (char *data, int clientid, int seqno, int retry = 0) |
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273 | { |
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274 | seqno &= SEQNO_MASK; |
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275 | |
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276 | u8 hdr[3] = { |
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277 | clientid, |
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278 | (seqno >> 8) | (retry << 6), |
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279 | seqno, |
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280 | }; |
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281 | |
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282 | assert (clientid < 256); |
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283 | |
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284 | cdc26.encode (data, hdr, 3); |
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285 | } |
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286 | |
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287 | inline void decode_header (char *data, int &clientid, int &seqno) |
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288 | { |
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289 | u8 hdr[3]; |
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290 | |
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291 | cdc26.decode (hdr, data, HDRSIZE); |
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292 | |
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293 | clientid = hdr[0]; |
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294 | seqno = ((hdr[1] << 8) | hdr[2]) & SEQNO_MASK; |
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295 | } |
|
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296 | |
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297 | ///////////////////////////////////////////////////////////////////////////// |
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298 | |
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299 | struct byte_stream |
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300 | { |
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301 | u8 *data; |
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302 | int maxsize; |
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303 | int fill; |
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304 | |
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305 | byte_stream (int maxsize); |
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306 | ~byte_stream (); |
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307 | |
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308 | bool empty () { return !fill; } |
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309 | int size () { return fill; } |
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310 | |
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311 | bool put (u8 *data, unsigned int datalen); |
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312 | bool put (vpn_packet *pkt); |
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313 | vpn_packet *get (); |
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314 | |
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315 | u8 *begin () { return data; } |
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316 | void remove (int count); |
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317 | }; |
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318 | |
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319 | byte_stream::byte_stream (int maxsize) |
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320 | : maxsize (maxsize), fill (0) |
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321 | { |
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322 | data = new u8 [maxsize]; |
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323 | } |
|
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324 | |
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325 | byte_stream::~byte_stream () |
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326 | { |
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327 | delete data; |
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328 | } |
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329 | |
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330 | void byte_stream::remove (int count) |
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331 | { |
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332 | if (count > fill) |
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333 | assert (count <= fill); |
|
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334 | |
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335 | memmove (data, data + count, fill -= count); |
|
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336 | } |
|
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337 | |
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338 | bool byte_stream::put (u8 *data, unsigned int datalen) |
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339 | { |
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340 | if (maxsize - fill < datalen) |
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341 | return false; |
|
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342 | |
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343 | memcpy (this->data + fill, data, datalen); fill += datalen; |
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344 | |
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345 | return true; |
|
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346 | } |
|
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347 | |
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348 | bool byte_stream::put (vpn_packet *pkt) |
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349 | { |
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350 | if (maxsize - fill < pkt->len + 2) |
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351 | return false; |
|
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352 | |
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353 | data [fill++] = pkt->len >> 8; |
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354 | data [fill++] = pkt->len; |
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355 | |
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356 | memcpy (data + fill, pkt->at (0), pkt->len); fill += pkt->len; |
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357 | |
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358 | return true; |
|
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359 | } |
|
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360 | |
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361 | vpn_packet *byte_stream::get () |
|
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362 | { |
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363 | unsigned int len; |
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364 | |
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365 | for (;;) |
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366 | { |
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367 | len = (data [0] << 8) | data [1]; |
|
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368 | |
|
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369 | if (len <= MAXSIZE || fill < 2) |
132 | break; |
370 | break; |
133 | |
371 | |
134 | accum <<= 6; |
372 | // TODO: handle this better than skipping, e.g. by reset |
135 | accum |= chr - 1; |
373 | slog (L_DEBUG, _("DNS: corrupted packet stream skipping a byte...")); |
136 | bits += 6; |
374 | remove (1); |
137 | |
375 | } |
138 | while (bits >= 8) |
|
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139 | { |
376 | |
140 | *dst++ = accum >> (bits - 8); |
377 | if (fill < len + 2) |
141 | bits -= 8; |
378 | return 0; |
142 | } |
379 | |
143 | } |
380 | vpn_packet *pkt = new vpn_packet; |
|
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381 | |
|
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382 | pkt->len = len; |
|
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383 | memcpy (pkt->at (0), data + 2, len); |
|
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384 | remove (len + 2); |
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385 | |
|
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386 | return pkt; |
144 | } |
387 | } |
|
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388 | |
|
|
389 | ///////////////////////////////////////////////////////////////////////////// |
145 | |
390 | |
146 | #define FLAG_QUERY ( 0 << 15) |
391 | #define FLAG_QUERY ( 0 << 15) |
147 | #define FLAG_RESPONSE ( 1 << 15) |
392 | #define FLAG_RESPONSE ( 1 << 15) |
148 | #define FLAG_OP_MASK (15 << 14) |
393 | #define FLAG_OP_MASK (15 << 11) |
149 | #define FLAG_OP_QUERY ( 0 << 11) |
394 | #define FLAG_OP_QUERY ( 0 << 11) |
150 | #define FLAG_AA ( 1 << 10) |
395 | #define FLAG_AA ( 1 << 10) |
151 | #define FLAG_TC ( 1 << 9) |
396 | #define FLAG_TC ( 1 << 9) |
152 | #define FLAG_RD ( 1 << 8) |
397 | #define FLAG_RD ( 1 << 8) |
153 | #define FLAG_RA ( 1 << 7) |
398 | #define FLAG_RA ( 1 << 7) |
|
|
399 | #define FLAG_AUTH ( 1 << 5) |
154 | #define FLAG_RCODE_MASK (15 << 0) |
400 | #define FLAG_RCODE_MASK (15 << 0) |
155 | #define FLAG_RCODE_OK ( 0 << 0) |
401 | #define FLAG_RCODE_OK ( 0 << 0) |
156 | #define FLAG_RCODE_FORMERR ( 1 << 0) |
402 | #define FLAG_RCODE_FORMERR ( 1 << 0) |
157 | #define FLAG_RCODE_SERVFAIL ( 2 << 0) |
403 | #define FLAG_RCODE_SERVFAIL ( 2 << 0) |
158 | #define FLAG_RCODE_NXDOMAIN ( 3 << 0) |
404 | #define FLAG_RCODE_NXDOMAIN ( 3 << 0) |
159 | #define FLAG_RCODE_REFUSED ( 5 << 0) |
405 | #define FLAG_RCODE_REFUSED ( 5 << 0) |
160 | |
406 | |
161 | #define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) |
407 | #define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) |
162 | #define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD) |
408 | #define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) |
|
|
409 | |
|
|
410 | struct dns_cfg |
|
|
411 | { |
|
|
412 | static int next_uid; |
|
|
413 | |
|
|
414 | u8 id1, id2, id3, id4; |
|
|
415 | |
|
|
416 | u8 version; |
|
|
417 | u8 flags; |
|
|
418 | u8 rrtype; |
|
|
419 | u8 def_ttl; |
|
|
420 | |
|
|
421 | u16 client; |
|
|
422 | u16 uid; // to make request unique |
|
|
423 | |
|
|
424 | u16 max_size; |
|
|
425 | u8 seq_cdc; |
|
|
426 | u8 req_cdc; |
|
|
427 | |
|
|
428 | u8 rep_cdc; |
|
|
429 | u8 r2, r3, r4; |
|
|
430 | |
|
|
431 | u8 r5, r6, r7, r8; |
|
|
432 | |
|
|
433 | void reset (int clientid); |
|
|
434 | bool valid (); |
|
|
435 | }; |
|
|
436 | |
|
|
437 | int dns_cfg::next_uid; |
|
|
438 | |
|
|
439 | void dns_cfg::reset (int clientid) |
|
|
440 | { |
|
|
441 | id1 = 'G'; |
|
|
442 | id2 = 'V'; |
|
|
443 | id3 = 'P'; |
|
|
444 | id4 = 'E'; |
|
|
445 | |
|
|
446 | version = 1; |
|
|
447 | |
|
|
448 | rrtype = RR_TYPE_TXT; |
|
|
449 | flags = 0; |
|
|
450 | def_ttl = 0; |
|
|
451 | seq_cdc = 26; |
|
|
452 | req_cdc = 62; |
|
|
453 | rep_cdc = 0; |
|
|
454 | max_size = htons (MAX_PKT_SIZE); |
|
|
455 | client = htons (clientid); |
|
|
456 | uid = next_uid++; |
|
|
457 | |
|
|
458 | r2 = r3 = r4 = 0; |
|
|
459 | r4 = r5 = r6 = r7 = 0; |
|
|
460 | } |
|
|
461 | |
|
|
462 | bool dns_cfg::valid () |
|
|
463 | { |
|
|
464 | return id1 == 'G' |
|
|
465 | && id2 == 'V' |
|
|
466 | && id3 == 'P' |
|
|
467 | && id4 == 'E' |
|
|
468 | && seq_cdc == 26 |
|
|
469 | && req_cdc == 62 |
|
|
470 | && rep_cdc == 0 |
|
|
471 | && version == 1; |
|
|
472 | } |
163 | |
473 | |
164 | struct dns_packet : net_packet |
474 | struct dns_packet : net_packet |
165 | { |
475 | { |
166 | u16 id; |
476 | u16 id; |
167 | u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 |
477 | u16 flags; // QR:1 Opcode:4 AA:1 TC:1 RD:1 RA:1 Z:3 RCODE:4 |
168 | u16 qdcount, ancount, nscount, arcount; |
478 | u16 qdcount, ancount, nscount, arcount; |
169 | |
479 | |
170 | u8 data[MAXSIZE - 6 * 2]; |
480 | u8 data [MAXSIZE - 6 * 2]; |
171 | |
481 | |
172 | int decode_label (char *data, int size, int &offs); |
482 | int decode_label (char *data, int size, int &offs); |
173 | }; |
483 | }; |
174 | |
484 | |
175 | int dns_packet::decode_label (char *data, int size, int &offs) |
485 | int dns_packet::decode_label (char *data, int size, int &offs) |
… | |
… | |
204 | } |
514 | } |
205 | |
515 | |
206 | return data - orig; |
516 | return data - orig; |
207 | } |
517 | } |
208 | |
518 | |
|
|
519 | ///////////////////////////////////////////////////////////////////////////// |
|
|
520 | |
|
|
521 | static u16 dns_id = 0; // TODO: should be per-vpn |
|
|
522 | |
|
|
523 | static u16 next_id () |
|
|
524 | { |
|
|
525 | if (!dns_id) |
|
|
526 | dns_id = time (0); |
|
|
527 | |
|
|
528 | // the simplest lsfr with periodicity 65535 i could find |
|
|
529 | dns_id = (dns_id << 1) |
|
|
530 | | (((dns_id >> 1) |
|
|
531 | ^ (dns_id >> 2) |
|
|
532 | ^ (dns_id >> 4) |
|
|
533 | ^ (dns_id >> 15)) & 1); |
|
|
534 | |
|
|
535 | return dns_id; |
|
|
536 | } |
|
|
537 | |
209 | struct dns_cfg |
538 | struct dns_rcv; |
|
|
539 | struct dns_snd; |
|
|
540 | |
|
|
541 | struct dns_connection |
210 | { |
542 | { |
211 | u8 id1, id2, id3; |
543 | connection *c; |
212 | u8 def_ttl; |
544 | struct vpn *vpn; |
213 | u8 unused1; |
545 | |
214 | u16 max_size; |
546 | dns_cfg cfg; |
215 | u8 flags1, flags2; |
547 | |
|
|
548 | bool established; |
|
|
549 | |
|
|
550 | tstamp last_received; |
|
|
551 | tstamp last_sent; |
|
|
552 | double min_latency; |
|
|
553 | double poll_interval, send_interval; |
|
|
554 | |
|
|
555 | vector<dns_rcv *> rcvpq; |
|
|
556 | |
|
|
557 | byte_stream rcvdq; int rcvseq; |
|
|
558 | byte_stream snddq; int sndseq; |
|
|
559 | |
|
|
560 | void time_cb (time_watcher &w); time_watcher tw; |
|
|
561 | void receive_rep (dns_rcv *r); |
|
|
562 | |
|
|
563 | dns_connection (connection *c); |
|
|
564 | ~dns_connection (); |
216 | }; |
565 | }; |
217 | |
566 | |
218 | // reply to client-poll |
567 | struct dns_snd |
219 | void dnsv4_poll (dns_packet *pkt, int &offs) |
|
|
220 | { |
568 | { |
221 | int dlen = MAX_PKT_SIZE - offs - 2; |
569 | dns_packet *pkt; |
|
|
570 | tstamp timeout, sent; |
|
|
571 | int retry; |
|
|
572 | struct dns_connection *dns; |
|
|
573 | int seqno; |
|
|
574 | bool stdhdr; |
222 | |
575 | |
|
|
576 | void gen_stream_req (int seqno, byte_stream &stream); |
|
|
577 | void gen_syn_req (); |
|
|
578 | |
|
|
579 | dns_snd (dns_connection *dns); |
|
|
580 | ~dns_snd (); |
|
|
581 | }; |
|
|
582 | |
|
|
583 | dns_snd::dns_snd (dns_connection *dns) |
|
|
584 | : dns (dns) |
|
|
585 | { |
|
|
586 | timeout = 0; |
|
|
587 | retry = 0; |
|
|
588 | seqno = 0; |
|
|
589 | sent = NOW; |
|
|
590 | stdhdr = false; |
|
|
591 | |
|
|
592 | pkt = new dns_packet; |
|
|
593 | |
|
|
594 | pkt->id = next_id (); |
|
|
595 | } |
|
|
596 | |
|
|
597 | dns_snd::~dns_snd () |
|
|
598 | { |
|
|
599 | delete pkt; |
|
|
600 | } |
|
|
601 | |
|
|
602 | static void append_domain (dns_packet &pkt, int &offs, const char *domain) |
|
|
603 | { |
|
|
604 | // add tunnel domain |
|
|
605 | for (;;) |
|
|
606 | { |
|
|
607 | const char *end = strchr (domain, '.'); |
|
|
608 | |
|
|
609 | if (!end) |
|
|
610 | end = domain + strlen (domain); |
|
|
611 | |
|
|
612 | int len = end - domain; |
|
|
613 | |
|
|
614 | pkt [offs++] = len; |
|
|
615 | memcpy (pkt.at (offs), domain, len); |
|
|
616 | offs += len; |
|
|
617 | |
|
|
618 | if (!*end) |
|
|
619 | break; |
|
|
620 | |
|
|
621 | domain = end + 1; |
|
|
622 | } |
|
|
623 | } |
|
|
624 | |
|
|
625 | void dns_snd::gen_stream_req (int seqno, byte_stream &stream) |
|
|
626 | { |
|
|
627 | stdhdr = true; |
|
|
628 | this->seqno = seqno; |
|
|
629 | |
|
|
630 | timeout = NOW + INITIAL_TIMEOUT; |
|
|
631 | |
|
|
632 | pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
|
|
633 | pkt->qdcount = htons (1); |
|
|
634 | |
|
|
635 | int offs = 6*2; |
|
|
636 | int dlen = MAX_DOMAIN_SIZE - (strlen (dns->c->conf->domain) + 2); |
|
|
637 | // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, |
|
|
638 | // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra |
|
|
639 | |
|
|
640 | char enc[256], *encp = enc; |
|
|
641 | encode_header (enc, THISNODE->id, seqno); |
|
|
642 | |
|
|
643 | int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); |
|
|
644 | |
|
|
645 | if (datalen > stream.size ()) |
|
|
646 | datalen = stream.size (); |
|
|
647 | |
|
|
648 | int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; |
|
|
649 | stream.remove (datalen); |
|
|
650 | |
|
|
651 | while (enclen) |
|
|
652 | { |
|
|
653 | int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; |
|
|
654 | |
|
|
655 | (*pkt)[offs++] = lbllen; |
|
|
656 | memcpy (pkt->at (offs), encp, lbllen); |
|
|
657 | |
|
|
658 | offs += lbllen; |
|
|
659 | encp += lbllen; |
|
|
660 | |
|
|
661 | enclen -= lbllen; |
|
|
662 | } |
|
|
663 | |
|
|
664 | append_domain (*pkt, offs, dns->c->conf->domain); |
|
|
665 | |
223 | (*pkt) [offs++] = 0; |
666 | (*pkt)[offs++] = 0; |
|
|
667 | (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; |
|
|
668 | (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
|
|
669 | |
|
|
670 | pkt->len = offs; |
|
|
671 | } |
|
|
672 | |
|
|
673 | void dns_snd::gen_syn_req () |
|
|
674 | { |
|
|
675 | timeout = NOW + INITIAL_SYN_TIMEOUT; |
|
|
676 | |
|
|
677 | pkt->flags = htons (DEFAULT_CLIENT_FLAGS); |
|
|
678 | pkt->qdcount = htons (1); |
|
|
679 | |
|
|
680 | int offs = 6 * 2; |
|
|
681 | |
|
|
682 | int elen = cdc26.encode ((char *)pkt->at (offs + 1), (u8 *)&dns->cfg, sizeof (dns_cfg)); |
|
|
683 | |
|
|
684 | assert (elen <= MAX_LBL_SIZE); |
|
|
685 | |
|
|
686 | (*pkt)[offs] = elen; |
|
|
687 | offs += elen + 1; |
|
|
688 | append_domain (*pkt, offs, dns->c->conf->domain); |
|
|
689 | |
224 | (*pkt) [offs++] = 5; |
690 | (*pkt)[offs++] = 0; |
225 | memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5); |
691 | (*pkt)[offs++] = RR_TYPE_A >> 8; (*pkt)[offs++] = RR_TYPE_A; |
226 | offs += 5; |
692 | (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; |
227 | |
693 | |
228 | pkt->ancount = htons (1); |
694 | pkt->len = offs; |
|
|
695 | } |
|
|
696 | |
|
|
697 | struct dns_rcv |
|
|
698 | { |
|
|
699 | int seqno; |
|
|
700 | dns_packet *pkt; // reply packet |
|
|
701 | u8 data [MAXSIZE]; // actually part of the reply packet... |
|
|
702 | int datalen; |
|
|
703 | |
|
|
704 | dns_rcv (int seqno, u8 *data, int datalen); |
|
|
705 | ~dns_rcv (); |
|
|
706 | }; |
|
|
707 | |
|
|
708 | dns_rcv::dns_rcv (int seqno, u8 *data, int datalen) |
|
|
709 | : seqno (seqno), pkt (new dns_packet), datalen (datalen) |
|
|
710 | { |
|
|
711 | memcpy (this->data, data, datalen); |
|
|
712 | } |
|
|
713 | |
|
|
714 | dns_rcv::~dns_rcv () |
|
|
715 | { |
|
|
716 | delete pkt; |
|
|
717 | } |
|
|
718 | |
|
|
719 | ///////////////////////////////////////////////////////////////////////////// |
|
|
720 | |
|
|
721 | dns_connection::dns_connection (connection *c) |
|
|
722 | : c (c) |
|
|
723 | , rcvdq (MAX_BACKLOG * 2) |
|
|
724 | , snddq (MAX_BACKLOG * 2) |
|
|
725 | , tw (this, &dns_connection::time_cb) |
|
|
726 | { |
|
|
727 | vpn = c->vpn; |
|
|
728 | |
|
|
729 | established = false; |
|
|
730 | |
|
|
731 | rcvseq = sndseq = 0; |
|
|
732 | |
|
|
733 | last_sent = last_received = 0; |
|
|
734 | poll_interval = MIN_POLL_INTERVAL; |
|
|
735 | send_interval = 0.5; // starting rate |
|
|
736 | min_latency = INITIAL_TIMEOUT; |
|
|
737 | } |
|
|
738 | |
|
|
739 | dns_connection::~dns_connection () |
|
|
740 | { |
|
|
741 | for (vector<dns_rcv *>::iterator i = rcvpq.begin (); |
|
|
742 | i != rcvpq.end (); |
|
|
743 | ++i) |
|
|
744 | delete *i; |
|
|
745 | } |
|
|
746 | |
|
|
747 | void dns_connection::receive_rep (dns_rcv *r) |
|
|
748 | { |
|
|
749 | if (r->datalen) |
|
|
750 | { |
|
|
751 | last_received = NOW; |
|
|
752 | tw.trigger (); |
|
|
753 | |
|
|
754 | poll_interval = send_interval; |
|
|
755 | } |
|
|
756 | else |
|
|
757 | { |
|
|
758 | poll_interval *= 1.5; |
|
|
759 | |
|
|
760 | if (poll_interval > MAX_POLL_INTERVAL) |
|
|
761 | poll_interval = MAX_POLL_INTERVAL; |
|
|
762 | } |
|
|
763 | |
|
|
764 | rcvpq.push_back (r); |
|
|
765 | |
|
|
766 | redo: |
|
|
767 | |
|
|
768 | // find next packet |
|
|
769 | for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) |
|
|
770 | if (SEQNO_EQ (rcvseq, (*i)->seqno)) |
|
|
771 | { |
|
|
772 | // enter the packet into our input stream |
|
|
773 | r = *i; |
|
|
774 | |
|
|
775 | // remove the oldest packet, look forward, as it's oldest first |
|
|
776 | for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) |
|
|
777 | if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) |
|
|
778 | { |
|
|
779 | delete *j; |
|
|
780 | rcvpq.erase (j); |
|
|
781 | break; |
|
|
782 | } |
|
|
783 | |
|
|
784 | rcvseq = (rcvseq + 1) & SEQNO_MASK; |
|
|
785 | |
|
|
786 | if (!rcvdq.put (r->data, r->datalen)) |
|
|
787 | { |
|
|
788 | slog (L_ERR, "DNS: !rcvdq.put (r->data, r->datalen)"); |
|
|
789 | abort (); // MUST never overflow, can be caused by data corruption, TODO |
|
|
790 | } |
|
|
791 | |
|
|
792 | while (vpn_packet *pkt = rcvdq.get ()) |
|
|
793 | { |
|
|
794 | sockinfo si; |
|
|
795 | si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4; |
|
|
796 | |
|
|
797 | vpn->recv_vpn_packet (pkt, si); |
|
|
798 | |
|
|
799 | delete pkt; |
|
|
800 | } |
|
|
801 | |
|
|
802 | // check for further packets |
|
|
803 | goto redo; |
|
|
804 | } |
|
|
805 | } |
|
|
806 | |
|
|
807 | void |
|
|
808 | vpn::dnsv4_server (dns_packet &pkt) |
|
|
809 | { |
|
|
810 | u16 flags = ntohs (pkt.flags); |
|
|
811 | |
|
|
812 | int offs = 6 * 2; // skip header |
|
|
813 | |
229 | pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); |
814 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
230 | |
815 | |
231 | printf ("we have room for %d bytes\n", dlen); |
816 | if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK)) |
|
|
817 | && pkt.qdcount == htons (1)) |
|
|
818 | { |
|
|
819 | char qname [MAXSIZE]; |
|
|
820 | int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
|
|
821 | |
|
|
822 | u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
|
|
823 | u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
|
|
824 | |
|
|
825 | pkt.qdcount = htons (1); |
|
|
826 | pkt.ancount = 0; |
|
|
827 | pkt.nscount = 0; // should be self, as other nameservers reply like this |
|
|
828 | pkt.arcount = 0; // a record for self, as other nameservers reply like this |
|
|
829 | |
|
|
830 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_SERVFAIL); |
|
|
831 | |
|
|
832 | int dlen = strlen (THISNODE->domain); |
|
|
833 | |
|
|
834 | if (qclass == RR_CLASS_IN |
|
|
835 | && qlen > dlen + 1 |
|
|
836 | && !memcmp (qname + qlen - (dlen + 1), THISNODE->domain, dlen)) |
|
|
837 | { |
|
|
838 | // now generate reply |
|
|
839 | pkt.ancount = htons (1); // one answer RR |
|
|
840 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); |
|
|
841 | |
|
|
842 | if ((qtype == RR_TYPE_ANY |
|
|
843 | || qtype == RR_TYPE_TXT |
|
|
844 | || qtype == RR_TYPE_NULL) |
|
|
845 | && qlen > dlen + 1 + HDRSIZE) |
|
|
846 | { |
|
|
847 | // correct class, domain: parse |
|
|
848 | int client, seqno; |
|
|
849 | decode_header (qname, client, seqno); |
|
|
850 | |
|
|
851 | u8 data[MAXSIZE]; |
|
|
852 | int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); |
|
|
853 | |
|
|
854 | if (0 < client && client <= conns.size ()) |
|
|
855 | { |
|
|
856 | connection *c = conns [client - 1]; |
|
|
857 | dns_connection *dns = c->dns; |
|
|
858 | dns_rcv *rcv; |
|
|
859 | bool in_seq; |
|
|
860 | |
|
|
861 | if (dns) |
|
|
862 | { |
|
|
863 | for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) |
|
|
864 | if (SEQNO_EQ ((*i)->seqno, seqno)) |
|
|
865 | { |
|
|
866 | // already seen that request: simply reply with the cached reply |
|
|
867 | dns_rcv *r = *i; |
|
|
868 | |
|
|
869 | slog (L_DEBUG, "DNS: duplicate packet received ID %d, SEQ %d", htons (r->pkt->id), seqno); |
|
|
870 | |
|
|
871 | // refresh header & id, as the retry count could have changed |
|
|
872 | memcpy (r->pkt->at (6 * 2 + 1), pkt.at (6 * 2 + 1), HDRSIZE); |
|
|
873 | r->pkt->id = pkt.id; |
|
|
874 | |
|
|
875 | memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); |
|
|
876 | |
|
|
877 | goto duplicate_request; |
|
|
878 | } |
|
|
879 | |
|
|
880 | in_seq = dns->rcvseq == seqno; |
|
|
881 | |
|
|
882 | // new packet, queue |
|
|
883 | rcv = new dns_rcv (seqno, data, datalen); |
|
|
884 | dns->receive_rep (rcv); |
|
|
885 | } |
|
|
886 | |
|
|
887 | { |
|
|
888 | pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
|
|
889 | |
|
|
890 | int rtype = dns ? dns->cfg.rrtype : RR_TYPE_A; |
|
|
891 | pkt [offs++] = rtype >> 8; pkt [offs++] = rtype; // type |
|
|
892 | pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
|
|
893 | pkt [offs++] = 0; pkt [offs++] = 0; |
|
|
894 | pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL |
|
|
895 | |
|
|
896 | int rdlen_offs = offs += 2; |
|
|
897 | |
|
|
898 | if (dns) |
|
|
899 | { |
|
|
900 | int dlen = ntohs (dns->cfg.max_size) - offs; |
|
|
901 | |
|
|
902 | // bind doesn't compress well, so reduce further by one label length |
|
|
903 | dlen -= qlen; |
|
|
904 | |
|
|
905 | // only put data into in-order sequence packets, if |
|
|
906 | // we receive out-of-order packets we generate empty |
|
|
907 | // replies |
|
|
908 | while (dlen > 1 && !dns->snddq.empty () && in_seq) |
|
|
909 | { |
|
|
910 | int txtlen = dlen <= 255 ? dlen - 1 : 255; |
|
|
911 | |
|
|
912 | if (txtlen > dns->snddq.size ()) |
|
|
913 | txtlen = dns->snddq.size (); |
|
|
914 | |
|
|
915 | pkt[offs++] = txtlen; |
|
|
916 | memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); |
|
|
917 | offs += txtlen; |
|
|
918 | dns->snddq.remove (txtlen); |
|
|
919 | |
|
|
920 | dlen -= txtlen + 1; |
|
|
921 | } |
|
|
922 | |
|
|
923 | // avoid empty TXT rdata |
|
|
924 | if (offs == rdlen_offs) |
|
|
925 | pkt[offs++] = 0; |
|
|
926 | |
|
|
927 | slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ()); |
|
|
928 | } |
|
|
929 | else |
|
|
930 | { |
|
|
931 | // send RST |
|
|
932 | pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
|
|
933 | pkt [offs++] = CMD_IP_RST; |
|
|
934 | } |
|
|
935 | |
|
|
936 | int rdlen = offs - rdlen_offs; |
|
|
937 | |
|
|
938 | pkt [rdlen_offs - 2] = rdlen >> 8; |
|
|
939 | pkt [rdlen_offs - 1] = rdlen; |
|
|
940 | |
|
|
941 | if (dns) |
|
|
942 | { |
|
|
943 | // now update dns_rcv copy |
|
|
944 | rcv->pkt->len = offs; |
|
|
945 | memcpy (rcv->pkt->at (0), pkt.at (0), offs); |
|
|
946 | } |
|
|
947 | } |
|
|
948 | |
|
|
949 | duplicate_request: ; |
|
|
950 | } |
|
|
951 | else |
|
|
952 | pkt.flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
|
|
953 | } |
|
|
954 | else if (qtype == RR_TYPE_A |
|
|
955 | && qlen > dlen + 1 + cdc26.encode_len (sizeof (dns_cfg))) |
|
|
956 | { |
|
|
957 | dns_cfg cfg; |
|
|
958 | cdc26.decode ((u8 *)&cfg, qname, cdc26.encode_len (sizeof (dns_cfg))); |
|
|
959 | int client = ntohs (cfg.client); |
|
|
960 | |
|
|
961 | pkt [offs++] = 0xc0; pkt [offs++] = 6 * 2; // refer to name in query section |
|
|
962 | |
|
|
963 | pkt [offs++] = RR_TYPE_A >> 8; pkt [offs++] = RR_TYPE_A; // type |
|
|
964 | pkt [offs++] = RR_CLASS_IN >> 8; pkt [offs++] = RR_CLASS_IN; // class |
|
|
965 | pkt [offs++] = 0; pkt [offs++] = 0; |
|
|
966 | pkt [offs++] = 0; pkt [offs++] = cfg.def_ttl; // TTL |
|
|
967 | pkt [offs++] = 0; pkt [offs++] = 4; // rdlength |
|
|
968 | |
|
|
969 | slog (L_INFO, _("DNS: client %d connects"), client); |
|
|
970 | |
|
|
971 | pkt [offs++] = CMD_IP_1; pkt [offs++] = CMD_IP_2; pkt [offs++] = CMD_IP_3; |
|
|
972 | pkt [offs++] = CMD_IP_REJ; |
|
|
973 | |
|
|
974 | if (0 < client && client <= conns.size ()) |
|
|
975 | { |
|
|
976 | connection *c = conns [client - 1]; |
|
|
977 | |
|
|
978 | if (cfg.valid ()) |
|
|
979 | { |
|
|
980 | pkt [offs - 1] = CMD_IP_SYN; |
|
|
981 | |
|
|
982 | delete c->dns; |
|
|
983 | c->dns = new dns_connection (c); |
|
|
984 | c->dns->cfg = cfg; |
|
|
985 | } |
|
|
986 | } |
|
|
987 | } |
|
|
988 | } |
|
|
989 | |
|
|
990 | pkt.len = offs; |
|
|
991 | } |
|
|
992 | } |
|
|
993 | |
|
|
994 | void |
|
|
995 | vpn::dnsv4_client (dns_packet &pkt) |
|
|
996 | { |
|
|
997 | u16 flags = ntohs (pkt.flags); |
|
|
998 | int offs = 6 * 2; // skip header |
|
|
999 | |
|
|
1000 | pkt.qdcount = ntohs (pkt.qdcount); |
|
|
1001 | pkt.ancount = ntohs (pkt.ancount); |
|
|
1002 | |
|
|
1003 | // go through our request list and find the corresponding request |
|
|
1004 | for (vector<dns_snd *>::iterator i = dns_sndpq.begin (); |
|
|
1005 | i != dns_sndpq.end (); |
|
|
1006 | ++i) |
|
|
1007 | if ((*i)->pkt->id == pkt.id) |
|
|
1008 | { |
|
|
1009 | dns_connection *dns = (*i)->dns; |
|
|
1010 | connection *c = dns->c; |
|
|
1011 | int seqno = (*i)->seqno; |
|
|
1012 | u8 data[MAXSIZE], *datap = data; |
|
|
1013 | |
|
|
1014 | if ((*i)->retry) |
|
|
1015 | { |
|
|
1016 | dns->send_interval *= 1.01; |
|
|
1017 | if (dns->send_interval > MAX_SEND_INTERVAL) |
|
|
1018 | dns->send_interval = MAX_SEND_INTERVAL; |
|
|
1019 | } |
|
|
1020 | else |
|
|
1021 | { |
|
|
1022 | #if 0 |
|
|
1023 | dns->send_interval *= 0.999; |
|
|
1024 | #endif |
|
|
1025 | // the latency surely puts an upper bound on |
|
|
1026 | // the minimum send interval |
|
|
1027 | double latency = NOW - (*i)->sent; |
|
|
1028 | |
|
|
1029 | if (latency < dns->min_latency) |
|
|
1030 | dns->min_latency = latency; |
|
|
1031 | |
|
|
1032 | if (dns->send_interval > dns->min_latency * LATENCY_FACTOR) |
|
|
1033 | dns->send_interval = dns->min_latency * LATENCY_FACTOR; |
|
|
1034 | |
|
|
1035 | if (dns->send_interval < MIN_SEND_INTERVAL) |
|
|
1036 | dns->send_interval = MIN_SEND_INTERVAL; |
|
|
1037 | } |
|
|
1038 | |
|
|
1039 | delete *i; |
|
|
1040 | dns_sndpq.erase (i); |
|
|
1041 | |
|
|
1042 | if (flags & FLAG_RESPONSE && !(flags & FLAG_OP_MASK)) |
|
|
1043 | { |
|
|
1044 | char qname[MAXSIZE]; |
|
|
1045 | |
|
|
1046 | while (pkt.qdcount-- && offs < MAXSIZE - 4) |
|
|
1047 | { |
|
|
1048 | int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
|
|
1049 | offs += 4; // skip qtype, qclass |
|
|
1050 | } |
|
|
1051 | |
|
|
1052 | while (pkt.ancount-- && offs < MAXSIZE - 10 && datap) |
|
|
1053 | { |
|
|
1054 | int qlen = pkt.decode_label ((char *)qname, MAXSIZE - offs, offs); |
|
|
1055 | |
|
|
1056 | u16 qtype = pkt [offs++] << 8; qtype |= pkt [offs++]; |
|
|
1057 | u16 qclass = pkt [offs++] << 8; qclass |= pkt [offs++]; |
|
|
1058 | u32 ttl = pkt [offs++] << 24; |
|
|
1059 | ttl |= pkt [offs++] << 16; |
|
|
1060 | ttl |= pkt [offs++] << 8; |
|
|
1061 | ttl |= pkt [offs++]; |
|
|
1062 | u16 rdlen = pkt [offs++] << 8; rdlen |= pkt [offs++]; |
|
|
1063 | |
|
|
1064 | if (qtype == RR_TYPE_NULL || qtype == RR_TYPE_TXT) |
|
|
1065 | { |
|
|
1066 | if (rdlen <= MAXSIZE - offs) |
|
|
1067 | { |
|
|
1068 | // decode bytes, finally |
|
|
1069 | |
|
|
1070 | while (rdlen) |
|
|
1071 | { |
|
|
1072 | int txtlen = pkt [offs++]; |
|
|
1073 | |
|
|
1074 | assert (txtlen + offs < MAXSIZE - 1); |
|
|
1075 | |
|
|
1076 | memcpy (datap, pkt.at (offs), txtlen); |
|
|
1077 | datap += txtlen; offs += txtlen; |
|
|
1078 | |
|
|
1079 | rdlen -= txtlen + 1; |
|
|
1080 | } |
|
|
1081 | } |
|
|
1082 | } |
|
|
1083 | else if (qtype == RR_TYPE_A) |
|
|
1084 | { |
|
|
1085 | u8 ip [4]; |
|
|
1086 | |
|
|
1087 | ip [0] = pkt [offs++]; |
|
|
1088 | ip [1] = pkt [offs++]; |
|
|
1089 | ip [2] = pkt [offs++]; |
|
|
1090 | ip [3] = pkt [offs++]; |
|
|
1091 | |
|
|
1092 | if (ip [0] == CMD_IP_1 |
|
|
1093 | && ip [1] == CMD_IP_2 |
|
|
1094 | && ip [2] == CMD_IP_3) |
|
|
1095 | { |
|
|
1096 | slog (L_TRACE, _("DNS: got tunnel meta command %02x"), ip [3]); |
|
|
1097 | |
|
|
1098 | if (ip [3] == CMD_IP_RST) |
|
|
1099 | { |
|
|
1100 | slog (L_DEBUG, _("DNS: got tunnel RST request")); |
|
|
1101 | |
|
|
1102 | delete dns; c->dns = 0; |
|
|
1103 | |
|
|
1104 | return; |
|
|
1105 | } |
|
|
1106 | else if (ip [3] == CMD_IP_SYN) |
|
|
1107 | { |
|
|
1108 | slog (L_DEBUG, _("DNS: got tunnel SYN reply, server likes us.")); |
|
|
1109 | dns->established = true; |
|
|
1110 | } |
|
|
1111 | else if (ip [3] == CMD_IP_REJ) |
|
|
1112 | { |
|
|
1113 | slog (L_DEBUG, _("DNS: got tunnel REJ reply, server does not like us, aborting.")); |
|
|
1114 | abort (); |
|
|
1115 | } |
|
|
1116 | else |
|
|
1117 | slog (L_INFO, _("DNS: got unknown meta command %02x"), ip [3]); |
|
|
1118 | } |
|
|
1119 | else |
|
|
1120 | slog (L_INFO, _("DNS: got spurious a record %d.%d.%d.%d"), |
|
|
1121 | ip [0], ip [1], ip [2], ip [3]); |
|
|
1122 | |
|
|
1123 | return; |
|
|
1124 | } |
|
|
1125 | |
|
|
1126 | int client, rseqno; |
|
|
1127 | decode_header (qname, client, rseqno); |
|
|
1128 | |
|
|
1129 | if (client != THISNODE->id) |
|
|
1130 | { |
|
|
1131 | slog (L_INFO, _("DNS: got dns tunnel response with wrong clientid, ignoring")); |
|
|
1132 | datap = 0; |
|
|
1133 | } |
|
|
1134 | else if (rseqno != seqno) |
|
|
1135 | { |
|
|
1136 | slog (L_DEBUG, _("DNS: got dns tunnel response with wrong seqno, badly caching nameserver?")); |
|
|
1137 | datap = 0; |
|
|
1138 | } |
|
|
1139 | } |
|
|
1140 | } |
|
|
1141 | |
|
|
1142 | // todo: pkt now used |
|
|
1143 | if (datap) |
|
|
1144 | dns->receive_rep (new dns_rcv (seqno, data, datap - data)); |
|
|
1145 | |
|
|
1146 | break; |
|
|
1147 | } |
232 | } |
1148 | } |
233 | |
1149 | |
234 | void |
1150 | void |
235 | vpn::dnsv4_ev (io_watcher &w, short revents) |
1151 | vpn::dnsv4_ev (io_watcher &w, short revents) |
236 | { |
1152 | { |
… | |
… | |
238 | { |
1154 | { |
239 | dns_packet *pkt = new dns_packet; |
1155 | dns_packet *pkt = new dns_packet; |
240 | struct sockaddr_in sa; |
1156 | struct sockaddr_in sa; |
241 | socklen_t sa_len = sizeof (sa); |
1157 | socklen_t sa_len = sizeof (sa); |
242 | |
1158 | |
243 | int len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); |
1159 | pkt->len = recvfrom (w.fd, pkt->at (0), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); |
244 | pkt->len = len; |
|
|
245 | |
1160 | |
246 | u16 flags = ntohs (pkt->flags); |
1161 | if (pkt->len > 0) |
247 | |
|
|
248 | if (THISNODE->dns_port) |
|
|
249 | { |
1162 | { |
250 | // server |
1163 | if (ntohs (pkt->flags) & FLAG_RESPONSE) |
251 | pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); |
1164 | dnsv4_client (*pkt); |
252 | |
1165 | else |
253 | int offs = 6 * 2; // skip header |
|
|
254 | |
|
|
255 | if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) |
|
|
256 | && pkt->qdcount == htons (1)) |
|
|
257 | { |
1166 | { |
258 | char qname[MAXSIZE]; |
1167 | dnsv4_server (*pkt); |
259 | int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs); |
1168 | sendto (w.fd, pkt->at (0), pkt->len, 0, (sockaddr *)&sa, sa_len); |
|
|
1169 | } |
260 | |
1170 | |
261 | printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len, |
1171 | delete pkt; |
262 | pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D |
1172 | } |
|
|
1173 | } |
|
|
1174 | } |
263 | |
1175 | |
264 | u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; |
1176 | bool |
265 | u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; |
1177 | vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
|
|
1178 | { |
|
|
1179 | int client = ntohs (si.port); |
266 | |
1180 | |
267 | pkt->qdcount = htons (1); |
1181 | assert (0 < client && client <= conns.size ()); |
268 | pkt->ancount = 0; |
|
|
269 | pkt->nscount = 0; // should be self, as other nameservers reply like this |
|
|
270 | pkt->arcount = 0; // a record for self, as other nameservers reply like this |
|
|
271 | |
1182 | |
272 | pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); |
1183 | connection *c = conns [client - 1]; |
273 | |
1184 | |
274 | int dlen = strlen (THISNODE->domain); |
1185 | if (!c->dns) |
|
|
1186 | c->dns = new dns_connection (c); |
|
|
1187 | |
|
|
1188 | if (!c->dns->snddq.put (pkt)) |
|
|
1189 | return false; |
275 | |
1190 | |
276 | if (qclass == RR_CLASS_IN |
1191 | c->dns->tw.trigger (); |
277 | && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT) |
1192 | |
278 | && qlen > dlen + 1 |
1193 | return true; |
279 | && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) |
1194 | } |
|
|
1195 | |
|
|
1196 | void |
|
|
1197 | connection::dnsv4_reset_connection () |
|
|
1198 | { |
|
|
1199 | //delete dns; dns = 0; //TODO |
|
|
1200 | } |
|
|
1201 | |
|
|
1202 | #define NEXT(w) do { if (next > (w)) next = w; } while (0) |
|
|
1203 | |
|
|
1204 | void |
|
|
1205 | dns_connection::time_cb (time_watcher &w) |
|
|
1206 | { |
|
|
1207 | // servers have to be polled |
|
|
1208 | if (THISNODE->dns_port) |
|
|
1209 | return; |
|
|
1210 | |
|
|
1211 | // check for timeouts and (re)transmit |
|
|
1212 | tstamp next = NOW + poll_interval; |
|
|
1213 | dns_snd *send = 0; |
|
|
1214 | |
|
|
1215 | for (vector<dns_snd *>::iterator i = vpn->dns_sndpq.begin (); |
|
|
1216 | i != vpn->dns_sndpq.end (); |
|
|
1217 | ++i) |
|
|
1218 | { |
|
|
1219 | dns_snd *r = *i; |
|
|
1220 | |
|
|
1221 | if (r->timeout <= NOW) |
|
|
1222 | { |
|
|
1223 | if (!send) |
|
|
1224 | { |
|
|
1225 | send = r; |
|
|
1226 | |
|
|
1227 | r->retry++; |
|
|
1228 | r->timeout = NOW + (r->retry * min_latency * 8.); |
|
|
1229 | |
|
|
1230 | // the following code changes the query section a bit, forcing |
|
|
1231 | // the forwarder to generate a new request |
|
|
1232 | if (r->stdhdr) |
280 | { |
1233 | { |
281 | // correct class, now generate reply |
1234 | //printf ("reencoded header for ID %d retry %d:%d:%d (%p)\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry); |
282 | pkt->ancount = htons (1); // one answer RR |
1235 | //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry); |
283 | |
|
|
284 | (*pkt) [offs++] = 0xc0; |
|
|
285 | (*pkt) [offs++] = 6 * 2; // same as in query section |
|
|
286 | |
|
|
287 | (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; |
|
|
288 | (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; |
|
|
289 | |
|
|
290 | (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; |
|
|
291 | (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL |
|
|
292 | |
|
|
293 | dnsv4_poll (pkt, offs); |
|
|
294 | printf ("correct class\n"); |
|
|
295 | } |
1236 | } |
296 | } |
1237 | } |
297 | |
|
|
298 | sendto (w.fd, &((*pkt)[0]), offs, 0, (sockaddr *)&sa, sa_len); |
|
|
299 | } |
1238 | } |
300 | else |
1239 | else |
|
|
1240 | NEXT (r->timeout); |
|
|
1241 | } |
|
|
1242 | |
|
|
1243 | if (!send) |
|
|
1244 | { |
|
|
1245 | if (last_sent + send_interval <= NOW) |
301 | { |
1246 | { |
302 | // client |
1247 | // generate a new packet, if wise |
|
|
1248 | |
|
|
1249 | if (!established) |
|
|
1250 | { |
|
|
1251 | if (vpn->dns_sndpq.empty ()) |
|
|
1252 | { |
|
|
1253 | send = new dns_snd (this); |
|
|
1254 | |
|
|
1255 | cfg.reset (THISNODE->id); |
|
|
1256 | send->gen_syn_req (); |
|
|
1257 | } |
|
|
1258 | } |
|
|
1259 | else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING |
|
|
1260 | && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) |
|
|
1261 | { |
|
|
1262 | //printf ("sending data request etc.\n"); //D |
|
|
1263 | if (!snddq.empty () || last_received + 1. > NOW) |
|
|
1264 | { |
|
|
1265 | poll_interval = send_interval; |
|
|
1266 | NEXT (NOW + send_interval); |
|
|
1267 | } |
|
|
1268 | |
|
|
1269 | send = new dns_snd (this); |
|
|
1270 | send->gen_stream_req (sndseq, snddq); |
|
|
1271 | send->timeout = NOW + min_latency * 8.; |
|
|
1272 | |
|
|
1273 | sndseq = (sndseq + 1) & SEQNO_MASK; |
|
|
1274 | } |
|
|
1275 | |
|
|
1276 | if (send) |
|
|
1277 | vpn->dns_sndpq.push_back (send); |
303 | } |
1278 | } |
|
|
1279 | else |
|
|
1280 | NEXT (last_sent + send_interval); |
|
|
1281 | } |
|
|
1282 | |
|
|
1283 | if (send) |
304 | } |
1284 | { |
305 | } |
1285 | last_sent = NOW; |
|
|
1286 | sendto (vpn->dnsv4_fd, |
|
|
1287 | send->pkt->at (0), send->pkt->len, 0, |
|
|
1288 | vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); |
|
|
1289 | } |
306 | |
1290 | |
307 | bool |
1291 | slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)", |
308 | vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
1292 | poll_interval, send_interval, next - NOW, |
309 | { |
1293 | vpn->dns_sndpq.size (), snddq.size (), |
310 | //return i->send_packet (pkt, tos); |
1294 | rcvpq.size ()); |
|
|
1295 | |
|
|
1296 | // TODO: no idea when this happens, but when next < NOW, we have a problem |
|
|
1297 | if (next < NOW + 0.0001) |
|
|
1298 | next = NOW + 0.1; |
|
|
1299 | |
|
|
1300 | w.start (next); |
311 | } |
1301 | } |
312 | |
1302 | |
313 | #endif |
1303 | #endif |
314 | |
1304 | |