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1 | office | 1 | /** |
2 | * @file DHCPIpUdpDecoder.c |
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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 | |||
30 | #include <limits.h> |
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31 | #include <string.h> |
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32 | |||
33 | #include <misc/ipv4_proto.h> |
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34 | #include <misc/udp_proto.h> |
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35 | #include <misc/byteorder.h> |
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36 | |||
37 | #include <dhcpclient/DHCPIpUdpDecoder.h> |
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38 | |||
39 | #define DHCP_SERVER_PORT 67 |
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40 | #define DHCP_CLIENT_PORT 68 |
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41 | |||
42 | #define IPUDP_HEADER_SIZE (sizeof(struct ipv4_header) + sizeof(struct udp_header)) |
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43 | |||
44 | static void input_handler_send (DHCPIpUdpDecoder *o, uint8_t *data, int data_len) |
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45 | { |
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46 | ASSERT(data_len >= 0) |
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47 | DebugObject_Access(&o->d_obj); |
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48 | |||
49 | struct ipv4_header iph; |
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50 | uint8_t *pl; |
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51 | int pl_len; |
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52 | |||
53 | if (!ipv4_check(data, data_len, &iph, &pl, &pl_len)) { |
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54 | goto fail; |
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55 | } |
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56 | |||
57 | if (ntoh8(iph.protocol) != IPV4_PROTOCOL_UDP) { |
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58 | goto fail; |
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59 | } |
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60 | |||
61 | if (pl_len < sizeof(struct udp_header)) { |
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62 | goto fail; |
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63 | } |
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64 | struct udp_header udph; |
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65 | memcpy(&udph, pl, sizeof(udph)); |
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66 | |||
67 | if (ntoh16(udph.source_port) != DHCP_SERVER_PORT) { |
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68 | goto fail; |
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69 | } |
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70 | |||
71 | if (ntoh16(udph.dest_port) != DHCP_CLIENT_PORT) { |
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72 | goto fail; |
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73 | } |
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74 | |||
75 | int udph_length = ntoh16(udph.length); |
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76 | if (udph_length < sizeof(udph)) { |
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77 | goto fail; |
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78 | } |
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79 | if (udph_length > data_len - (pl - data)) { |
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80 | goto fail; |
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81 | } |
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82 | |||
83 | if (ntoh16(udph.checksum) != 0) { |
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84 | uint16_t checksum_in_packet = udph.checksum; |
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85 | udph.checksum = 0; |
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86 | uint16_t checksum_computed = udp_checksum(&udph, pl + sizeof(udph), udph_length - sizeof(udph), iph.source_address, iph.destination_address); |
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87 | if (checksum_in_packet != checksum_computed) { |
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88 | goto fail; |
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89 | } |
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90 | } |
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91 | |||
92 | // pass payload to output |
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93 | PacketPassInterface_Sender_Send(o->output, pl + sizeof(udph), udph_length - sizeof(udph)); |
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94 | |||
95 | return; |
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96 | |||
97 | fail: |
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98 | PacketPassInterface_Done(&o->input); |
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99 | } |
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100 | |||
101 | static void output_handler_done (DHCPIpUdpDecoder *o) |
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102 | { |
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103 | DebugObject_Access(&o->d_obj); |
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104 | |||
105 | PacketPassInterface_Done(&o->input); |
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106 | } |
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107 | |||
108 | void DHCPIpUdpDecoder_Init (DHCPIpUdpDecoder *o, PacketPassInterface *output, BPendingGroup *pg) |
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109 | { |
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110 | ASSERT(PacketPassInterface_GetMTU(output) <= INT_MAX - IPUDP_HEADER_SIZE) |
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111 | |||
112 | // init arguments |
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113 | o->output = output; |
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114 | |||
115 | // init output |
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116 | PacketPassInterface_Sender_Init(o->output, (PacketPassInterface_handler_done)output_handler_done, o); |
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117 | |||
118 | // init input |
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119 | PacketPassInterface_Init(&o->input, IPUDP_HEADER_SIZE + PacketPassInterface_GetMTU(o->output), (PacketPassInterface_handler_send)input_handler_send, o, pg); |
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120 | |||
121 | DebugObject_Init(&o->d_obj); |
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122 | } |
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123 | |||
124 | void DHCPIpUdpDecoder_Free (DHCPIpUdpDecoder *o) |
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125 | { |
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126 | DebugObject_Free(&o->d_obj); |
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127 | |||
128 | // free input |
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129 | PacketPassInterface_Free(&o->input); |
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130 | } |
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131 | |||
132 | PacketPassInterface * DHCPIpUdpDecoder_GetInput (DHCPIpUdpDecoder *o) |
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133 | { |
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134 | DebugObject_Access(&o->d_obj); |
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135 | |||
136 | return &o->input; |
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137 | } |