BadVPN – Blame information for rev 1
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1 | office | 1 | /** |
2 | * @file udp_proto.h |
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3 | * @author Ambroz Bizjak <ambrop7@gmail.com> |
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4 | * |
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5 | * @section LICENSE |
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6 | * |
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7 | * Redistribution and use in source and binary forms, with or without |
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8 | * modification, are permitted provided that the following conditions are met: |
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9 | * 1. Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * 2. Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * 3. Neither the name of the author nor the |
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15 | * names of its contributors may be used to endorse or promote products |
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16 | * derived from this software without specific prior written permission. |
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17 | * |
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18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND |
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19 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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20 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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21 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
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22 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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23 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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24 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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25 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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27 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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28 | * |
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29 | * @section DESCRIPTION |
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30 | * |
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31 | * Definitions for the UDP protocol. |
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32 | */ |
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33 | |||
34 | #ifndef BADVPN_MISC_UDP_PROTO_H |
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35 | #define BADVPN_MISC_UDP_PROTO_H |
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36 | |||
37 | #include <stdint.h> |
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38 | |||
39 | #include <misc/debug.h> |
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40 | #include <misc/byteorder.h> |
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41 | #include <misc/ipv4_proto.h> |
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42 | #include <misc/ipv6_proto.h> |
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43 | #include <misc/read_write_int.h> |
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44 | |||
45 | B_START_PACKED |
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46 | struct udp_header { |
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47 | uint16_t source_port; |
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48 | uint16_t dest_port; |
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49 | uint16_t length; |
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50 | uint16_t checksum; |
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51 | } B_PACKED; |
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52 | B_END_PACKED |
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53 | |||
54 | static uint32_t udp_checksum_summer (const char *data, uint16_t len) |
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55 | { |
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56 | ASSERT(len % 2 == 0) |
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57 | |||
58 | uint32_t t = 0; |
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59 | |||
60 | for (uint16_t i = 0; i < len / 2; i++) { |
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61 | t += badvpn_read_be16(data + 2 * i); |
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62 | } |
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63 | |||
64 | return t; |
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65 | } |
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66 | |||
67 | static uint16_t udp_checksum (const struct udp_header *header, const uint8_t *payload, uint16_t payload_len, uint32_t source_addr, uint32_t dest_addr) |
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68 | { |
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69 | uint32_t t = 0; |
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70 | |||
71 | t += udp_checksum_summer((char *)&source_addr, sizeof(source_addr)); |
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72 | t += udp_checksum_summer((char *)&dest_addr, sizeof(dest_addr)); |
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73 | |||
74 | uint16_t x; |
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75 | x = hton16(IPV4_PROTOCOL_UDP); |
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76 | t += udp_checksum_summer((char *)&x, sizeof(x)); |
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77 | x = hton16(sizeof(*header) + payload_len); |
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78 | t += udp_checksum_summer((char *)&x, sizeof(x)); |
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79 | |||
80 | t += udp_checksum_summer((const char *)header, sizeof(*header)); |
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81 | |||
82 | if (payload_len % 2 == 0) { |
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83 | t += udp_checksum_summer((const char *)payload, payload_len); |
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84 | } else { |
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85 | t += udp_checksum_summer((const char *)payload, payload_len - 1); |
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86 | |||
87 | x = hton16(((uint16_t)payload[payload_len - 1]) << 8); |
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88 | t += udp_checksum_summer((char *)&x, sizeof(x)); |
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89 | } |
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90 | |||
91 | while (t >> 16) { |
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92 | t = (t & 0xFFFF) + (t >> 16); |
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93 | } |
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94 | |||
95 | t = ~t; |
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96 | |||
97 | if (t == 0) { |
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98 | t = UINT16_MAX; |
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99 | } |
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100 | |||
101 | return hton16(t); |
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102 | } |
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103 | |||
104 | static uint16_t udp_ip6_checksum (const struct udp_header *header, const uint8_t *payload, uint16_t payload_len, const uint8_t *source_addr, const uint8_t *dest_addr) |
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105 | { |
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106 | uint32_t t = 0; |
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107 | |||
108 | t += udp_checksum_summer((const char *)source_addr, 16); |
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109 | t += udp_checksum_summer((const char *)dest_addr, 16); |
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110 | |||
111 | uint32_t x; |
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112 | x = hton32(sizeof(*header) + payload_len); |
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113 | t += udp_checksum_summer((char *)&x, sizeof(x)); |
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114 | x = hton32(IPV6_NEXT_UDP); |
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115 | t += udp_checksum_summer((char *)&x, sizeof(x)); |
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116 | |||
117 | t += udp_checksum_summer((const char *)header, sizeof(*header)); |
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118 | |||
119 | if (payload_len % 2 == 0) { |
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120 | t += udp_checksum_summer((const char *)payload, payload_len); |
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121 | } else { |
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122 | t += udp_checksum_summer((const char *)payload, payload_len - 1); |
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123 | |||
124 | uint16_t y; |
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125 | y = hton16(((uint16_t)payload[payload_len - 1]) << 8); |
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126 | t += udp_checksum_summer((char *)&y, sizeof(y)); |
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127 | } |
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128 | |||
129 | while (t >> 16) { |
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130 | t = (t & 0xFFFF) + (t >> 16); |
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131 | } |
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132 | |||
133 | t = ~t; |
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134 | |||
135 | if (t == 0) { |
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136 | t = UINT16_MAX; |
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137 | } |
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138 | |||
139 | return hton16(t); |
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140 | } |
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141 | |||
142 | static int udp_check (const uint8_t *data, int data_len, struct udp_header *out_header, uint8_t **out_payload, int *out_payload_len) |
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143 | { |
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144 | ASSERT(data_len >= 0) |
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145 | ASSERT(out_header) |
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146 | ASSERT(out_payload) |
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147 | ASSERT(out_payload_len) |
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148 | |||
149 | // parse UDP header |
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150 | if (data_len < sizeof(struct udp_header)) { |
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151 | return 0; |
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152 | } |
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153 | memcpy(out_header, data, sizeof(*out_header)); |
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154 | data += sizeof(*out_header); |
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155 | data_len -= sizeof(*out_header); |
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156 | |||
157 | // verify UDP payload |
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158 | int udp_length = ntoh16(out_header->length); |
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159 | if (udp_length < sizeof(*out_header)) { |
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160 | return 0; |
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161 | } |
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162 | if (udp_length > sizeof(*out_header) + data_len) { |
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163 | return 0; |
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164 | } |
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165 | |||
166 | // ignore stray data |
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167 | data_len = udp_length - sizeof(*out_header); |
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168 | |||
169 | *out_payload = (uint8_t *)data; |
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170 | *out_payload_len = data_len; |
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171 | return 1; |
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172 | } |
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173 | |||
174 | #endif |