1 | /* -*- Mode: C; tab-width: 4 -*- |
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2 | * |
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3 | * Copyright (c) 2011-2013 Apple Inc. All rights reserved. |
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4 | * |
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5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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6 | * you may not use this file except in compliance with the License. |
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7 | * You may obtain a copy of the License at |
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8 | * |
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9 | * http://www.apache.org/licenses/LICENSE-2.0 |
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10 | * |
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11 | * Unless required by applicable law or agreed to in writing, software |
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12 | * distributed under the License is distributed on an "AS IS" BASIS, |
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13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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14 | * See the License for the specific language governing permissions and |
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15 | * limitations under the License. |
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16 | */ |
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17 | |
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18 | #include "dnsproxy.h" |
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19 | |
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20 | #ifndef UNICAST_DISABLED |
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21 | |
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22 | // Implementation Notes |
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23 | // |
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24 | // DNS Proxy listens on port 53 (UDPv4v6 & TCPv4v6) for DNS queries. It handles only |
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25 | // the "Query" opcode of the DNS protocol described in RFC 1035. For all other opcodes, it returns |
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26 | // "Not Implemented" error. The platform interface mDNSPlatformInitDNSProxySkts |
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27 | // sets up the sockets and whenever it receives a packet, it calls ProxyTCPCallback or ProxyUDPCallback |
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28 | // defined here. For TCP socket, the platform does the "accept" and only sends the received packets |
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29 | // on the newly accepted socket. A single UDP socket (per address family) is used to send/recv |
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30 | // requests/responses from all clients. For TCP, there is one socket per request. Hence, there is some |
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31 | // extra state that needs to be disposed at the end. |
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32 | // |
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33 | // When a DNS request is received, ProxyCallbackCommon checks for malformed packet etc. and also checks |
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34 | // for duplicates, before creating DNSProxyClient state and starting a question with the "core" |
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35 | // (mDNS_StartQuery). When the callback for the question happens, it gathers all the necessary |
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36 | // resource records, constructs a response and sends it back to the client. |
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37 | // |
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38 | // - Question callback is called with only one resource record at a time. We need all the resource |
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39 | // records to construct the response. Hence, we lookup all the records ourselves. |
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40 | // |
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41 | // - The response may not fit the client's buffer size. In that case, we need to set the truncate bit |
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42 | // and the client would retry using TCP. |
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43 | // |
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44 | // - The client may have set the DNSSEC OK bit in the EDNS0 option and that means we also have to |
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45 | // return the RRSIGs or the NSEC records with the RRSIGs in the Additional section. We need to |
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46 | // ask the "core" to fetch the DNSSEC records and do the validation if the CD bit is not set. |
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47 | // |
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48 | // Once the response is sent to the client, the client state is disposed. When there is no response |
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49 | // from the "core", it eventually times out and we will not find any answers in the cache and we send a |
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50 | // "NXDomain" response back. Thus, we don't need any special timers to reap the client state in the case |
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51 | // of errors. |
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52 | |
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53 | typedef struct DNSProxyClient_struct DNSProxyClient; |
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54 | |
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55 | struct DNSProxyClient_struct { |
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56 | |
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57 | DNSProxyClient *next; |
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58 | mDNSAddr addr; // Client's IP address |
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59 | mDNSIPPort port; // Client's port number |
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60 | mDNSOpaque16 msgid; // DNS msg id |
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61 | mDNSInterfaceID interfaceID; // Interface on which we received the request |
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62 | void *socket; // Return socket |
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63 | mDNSBool tcp; // TCP or UDP ? |
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64 | mDNSOpaque16 requestFlags; // second 16 bit word in the DNSMessageHeader of the request |
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65 | mDNSu8 *optRR; // EDNS0 option |
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66 | mDNSu16 optLen; // Total Length of the EDNS0 option |
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67 | mDNSu16 rcvBufSize; // How much can the client receive ? |
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68 | mDNSBool DNSSECOK; // DNSSEC OK ? |
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69 | void *context; // Platform context to be disposed if non-NULL |
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70 | domainname qname; // q->qname can't be used for duplicate check |
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71 | DNSQuestion q; // as it can change underneath us for CNAMEs |
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72 | }; |
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73 | |
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74 | #define MIN_DNS_MESSAGE_SIZE 512 |
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75 | DNSProxyClient *DNSProxyClients; |
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76 | |
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77 | mDNSlocal void FreeDNSProxyClient(DNSProxyClient *pc) |
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78 | { |
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79 | if (pc->optRR) |
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80 | mDNSPlatformMemFree(pc->optRR); |
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81 | mDNSPlatformMemFree(pc); |
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82 | } |
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83 | |
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84 | mDNSlocal mDNSBool ParseEDNS0(DNSProxyClient *pc, const mDNSu8 *ptr, int length, const mDNSu8 *limit) |
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85 | { |
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86 | if (ptr + length > limit) |
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87 | { |
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88 | LogInfo("ParseEDNS0: Not enough space in the packet"); |
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89 | return mDNSfalse; |
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90 | } |
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91 | // Skip the root label |
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92 | ptr++; |
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93 | mDNSu16 rrtype = (mDNSu16) ((mDNSu16)ptr[0] << 8 | ptr[1]); |
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94 | if (rrtype != kDNSType_OPT) |
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95 | { |
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96 | LogInfo("ParseEDNS0: Not the right type %d", rrtype); |
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97 | return mDNSfalse; |
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98 | } |
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99 | mDNSu16 rrclass = (mDNSu16) ((mDNSu16)ptr[2] << 8 | ptr[3]); |
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100 | #if MDNS_DEBUGMSGS |
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101 | mDNSu8 rcode = ptr[4]; |
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102 | mDNSu8 version = ptr[5]; |
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103 | mDNSu16 flag = (mDNSu16) ((mDNSu16)ptr[6] << 8 | ptr[7]); |
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104 | debugf("rrtype is %s, length is %d, rcode %d, version %d, flag 0x%x", DNSTypeName(rrtype), rrclass, rcode, version, flag); |
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105 | #endif |
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106 | pc->rcvBufSize = rrclass; |
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107 | pc->DNSSECOK = ptr[6] & 0x80; |
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108 | |
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109 | return mDNStrue; |
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110 | } |
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111 | |
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112 | mDNSexport mDNSu8 *DNSProxySetAttributes(DNSQuestion *q, DNSMessageHeader *h, DNSMessage *msg, mDNSu8 *ptr, mDNSu8 *limit) |
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113 | { |
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114 | DNSProxyClient *pc = (DNSProxyClient *)q->QuestionContext; |
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115 | |
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116 | (void) msg; |
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117 | |
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118 | h->flags = pc->requestFlags; |
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119 | if (pc->optRR) |
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120 | { |
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121 | if (ptr + pc->optLen > limit) |
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122 | { |
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123 | LogInfo("DNSProxySetAttributes: Cannot set EDNS0 option start %p, OptLen %d, end %p", ptr, pc->optLen, limit); |
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124 | return ptr; |
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125 | } |
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126 | h->numAdditionals++; |
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127 | mDNSPlatformMemCopy(ptr, pc->optRR, pc->optLen); |
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128 | ptr += pc->optLen; |
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129 | } |
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130 | return ptr; |
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131 | } |
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132 | |
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133 | mDNSlocal mDNSu8 *AddEDNS0Option(mDNS *const m, mDNSu8 *ptr, mDNSu8 *limit) |
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134 | { |
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135 | int len = 4096; |
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136 | |
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137 | if (ptr + 11 > limit) |
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138 | { |
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139 | LogInfo("AddEDNS0Option: not enough space"); |
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140 | return mDNSNULL; |
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141 | } |
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142 | m->omsg.h.numAdditionals++; |
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143 | ptr[0] = 0; |
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144 | ptr[1] = (mDNSu8) (kDNSType_OPT >> 8); |
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145 | ptr[2] = (mDNSu8) (kDNSType_OPT & 0xFF); |
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146 | ptr[3] = (mDNSu8) (len >> 8); |
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147 | ptr[4] = (mDNSu8) (len & 0xFF); |
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148 | ptr[5] = 0; // rcode |
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149 | ptr[6] = 0; // version |
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150 | ptr[7] = 0; |
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151 | ptr[8] = 0; // flags |
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152 | ptr[9] = 0; // rdlength |
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153 | ptr[10] = 0; // rdlength |
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154 | |
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155 | debugf("AddEDNS0 option"); |
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156 | |
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157 | return (ptr + 11); |
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158 | } |
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159 | |
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160 | // Currently RD and CD bit should be copied if present in the request or cleared if |
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161 | // not present in the request. RD bit is normally set in the response and hence the |
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162 | // cache reflects the right value. CD bit behaves differently. If the CD bit is set |
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163 | // the first time, the cache retains it, if it is present in response (assuming the |
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164 | // upstream server does it right). Next time through we should not use the cached |
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165 | // value of the CD bit blindly. It depends on whether it was in the request or not. |
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166 | mDNSlocal mDNSOpaque16 SetResponseFlags(DNSProxyClient *pc, const mDNSOpaque16 responseFlags) |
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167 | { |
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168 | mDNSOpaque16 rFlags = responseFlags; |
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169 | |
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170 | if (pc->requestFlags.b[0] & kDNSFlag0_RD) |
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171 | rFlags.b[0] |= kDNSFlag0_RD; |
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172 | else |
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173 | rFlags.b[0] &= ~kDNSFlag0_RD; |
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174 | |
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175 | if (pc->requestFlags.b[1] & kDNSFlag1_CD) |
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176 | rFlags.b[1] |= kDNSFlag1_CD; |
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177 | else |
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178 | rFlags.b[1] &= ~kDNSFlag1_CD; |
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179 | |
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180 | return rFlags; |
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181 | } |
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182 | |
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183 | mDNSlocal mDNSu8 *AddResourceRecords(mDNS *const m, DNSProxyClient *pc, mDNSu8 **prevptr, mStatus *error) |
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184 | { |
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185 | mDNSu32 slot; |
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186 | CacheGroup *cg; |
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187 | CacheRecord *cr; |
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188 | int len = sizeof(DNSMessageHeader); |
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189 | mDNSu8 *orig = m->omsg.data; |
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190 | mDNSBool first = mDNStrue; |
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191 | mDNSu8 *ptr = mDNSNULL; |
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192 | mDNSs32 now; |
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193 | mDNSs32 ttl; |
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194 | CacheRecord *nsec = mDNSNULL; |
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195 | CacheRecord *soa = mDNSNULL; |
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196 | CacheRecord *cname = mDNSNULL; |
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197 | mDNSu8 *limit; |
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198 | domainname tempQName; |
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199 | mDNSu32 tempQNameHash; |
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200 | |
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201 | *error = mStatus_NoError; |
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202 | *prevptr = mDNSNULL; |
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203 | |
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204 | mDNS_Lock(m); |
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205 | now = m->timenow; |
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206 | mDNS_Unlock(m); |
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207 | |
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208 | if (!pc->tcp) |
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209 | { |
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210 | if (!pc->rcvBufSize) |
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211 | { |
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212 | limit = m->omsg.data + MIN_DNS_MESSAGE_SIZE; |
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213 | } |
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214 | else |
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215 | { |
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216 | limit = (pc->rcvBufSize > AbsoluteMaxDNSMessageData ? m->omsg.data + AbsoluteMaxDNSMessageData : m->omsg.data + pc->rcvBufSize); |
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217 | } |
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218 | } |
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219 | else |
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220 | { |
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221 | // For TCP, limit is not determined by EDNS0 but by 16 bit rdlength field and |
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222 | // AbsoluteMaxDNSMessageData is smaller than 64k. |
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223 | limit = m->omsg.data + AbsoluteMaxDNSMessageData; |
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224 | } |
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225 | LogInfo("AddResourceRecords: Limit is %d", limit - m->omsg.data); |
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226 | |
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227 | AssignDomainName(&tempQName, &pc->qname); |
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228 | tempQNameHash = DomainNameHashValue(&tempQName); |
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229 | |
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230 | again: |
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231 | nsec = soa = cname = mDNSNULL; |
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232 | slot = HashSlot(&tempQName); |
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233 | |
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234 | cg = CacheGroupForName(m, slot, tempQNameHash, &tempQName); |
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235 | if (!cg) |
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236 | { |
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237 | LogInfo("AddResourceRecords: CacheGroup not found for %##s", tempQName.c); |
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238 | *error = mStatus_NoSuchRecord; |
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239 | return mDNSNULL; |
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240 | } |
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241 | // Set ValidatingResponse so that you can get RRSIGs also matching |
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242 | // the question |
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243 | if (pc->DNSSECOK) |
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244 | pc->q.ValidatingResponse = 1; |
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245 | for (cr = cg->members; cr; cr = cr->next) |
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246 | { |
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247 | if (SameNameRecordAnswersQuestion(&cr->resrec, &pc->q)) |
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248 | { |
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249 | if (first) |
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250 | { |
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251 | // If this is the first time, initialize the header and the question. |
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252 | // This code needs to be here so that we can use the responseFlags from the |
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253 | // cache record |
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254 | mDNSOpaque16 responseFlags = SetResponseFlags(pc, cr->responseFlags); |
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255 | InitializeDNSMessage(&m->omsg.h, pc->msgid, responseFlags); |
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256 | ptr = putQuestion(&m->omsg, m->omsg.data, m->omsg.data + AbsoluteMaxDNSMessageData, &pc->qname, pc->q.qtype, pc->q.qclass); |
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257 | if (!ptr) |
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258 | { |
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259 | LogInfo("AddResourceRecords: putQuestion NULL for %##s (%s)", &pc->qname.c, DNSTypeName(pc->q.qtype)); |
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260 | return mDNSNULL; |
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261 | } |
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262 | first = mDNSfalse; |
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263 | } |
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264 | // - For NegativeAnswers there is nothing to add |
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265 | // - If DNSSECOK is set, we also automatically lookup the RRSIGs which |
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266 | // will also be returned. If the client is explicitly looking up |
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267 | // a DNSSEC record (e.g., DNSKEY, DS) we should return the response. |
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268 | // DNSSECOK bit only influences whether we add the RRSIG or not. |
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269 | if (cr->resrec.RecordType != kDNSRecordTypePacketNegative) |
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270 | { |
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271 | LogInfo("AddResourceRecords: Answering question with %s", CRDisplayString(m, cr)); |
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272 | ttl = cr->resrec.rroriginalttl - (now - cr->TimeRcvd) / mDNSPlatformOneSecond; |
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273 | ptr = PutResourceRecordTTLWithLimit(&m->omsg, ptr, &m->omsg.h.numAnswers, &cr->resrec, ttl, limit); |
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274 | if (!ptr) |
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275 | { |
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276 | *prevptr = orig; |
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277 | return mDNSNULL; |
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278 | } |
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279 | len += (ptr - orig); |
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280 | orig = ptr; |
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281 | } |
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282 | // If we have nsecs (wildcard expanded answer or negative response), add them |
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283 | // in the additional section below if the DNSSECOK bit is set |
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284 | if (pc->DNSSECOK && cr->nsec) |
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285 | { |
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286 | LogInfo("AddResourceRecords: nsec set for %s", CRDisplayString(m ,cr)); |
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287 | nsec = cr->nsec; |
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288 | } |
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289 | if (cr->soa) |
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290 | { |
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291 | LogInfo("AddResourceRecords: soa set for %s", CRDisplayString(m ,cr)); |
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292 | soa = cr->soa; |
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293 | } |
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294 | // If we are using CNAME to answer a question and CNAME is not the type we |
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295 | // are looking for, note down the CNAME record so that we can follow them |
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296 | // later. Before we follow the CNAME, print the RRSIGs and any nsec (wildcard |
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297 | // expanded) if any. |
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298 | if ((pc->q.qtype != cr->resrec.rrtype) && cr->resrec.rrtype == kDNSType_CNAME) |
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299 | { |
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300 | LogInfo("AddResourceRecords: cname set for %s", CRDisplayString(m ,cr)); |
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301 | cname = cr; |
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302 | } |
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303 | } |
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304 | } |
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305 | // Along with the nsec records, we also cache the SOA record. For non-DNSSEC question, we need |
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306 | // to send the SOA back. Normally we either cache the SOA record (non-DNSSEC question) pointed |
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307 | // to by "cr->soa" or the NSEC/SOA records along with their RRSIGs (DNSSEC question) pointed to |
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308 | // by "cr->nsec". Two cases: |
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309 | // |
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310 | // - if we issue a DNSSEC question followed by non-DNSSEC question for the same name, |
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311 | // we only have the nsec records and we need to filter the SOA record alone for the |
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312 | // non-DNSSEC questions. |
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313 | // |
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314 | // - if we issue a non-DNSSEC question followed by DNSSEC question for the same name, |
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315 | // the "core" flushes the cache entry and re-issue the question with EDNS0/DOK bit and |
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316 | // in this case we return all the DNSSEC records we have. |
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317 | for (; nsec; nsec = nsec->next) |
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318 | { |
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319 | if (!pc->DNSSECOK && DNSSECRecordType(nsec->resrec.rrtype)) |
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320 | continue; |
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321 | LogInfo("AddResourceRecords:NSEC Answering question with %s", CRDisplayString(m, nsec)); |
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322 | ttl = nsec->resrec.rroriginalttl - (now - nsec->TimeRcvd) / mDNSPlatformOneSecond; |
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323 | ptr = PutResourceRecordTTLWithLimit(&m->omsg, ptr, &m->omsg.h.numAuthorities, &nsec->resrec, ttl, limit); |
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324 | if (!ptr) |
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325 | { |
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326 | *prevptr = orig; |
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327 | return mDNSNULL; |
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328 | } |
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329 | len += (ptr - orig); |
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330 | orig = ptr; |
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331 | } |
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332 | if (soa) |
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333 | { |
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334 | LogInfo("AddResourceRecords: SOA Answering question with %s", CRDisplayString(m, soa)); |
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335 | ptr = PutResourceRecordTTLWithLimit(&m->omsg, ptr, &m->omsg.h.numAuthorities, &soa->resrec, soa->resrec.rroriginalttl, limit); |
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336 | if (!ptr) |
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337 | { |
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338 | *prevptr = orig; |
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339 | return mDNSNULL; |
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340 | } |
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341 | len += (ptr - orig); |
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342 | orig = ptr; |
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343 | } |
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344 | if (cname) |
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345 | { |
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346 | AssignDomainName(&tempQName, &cname->resrec.rdata->u.name); |
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347 | tempQNameHash = DomainNameHashValue(&tempQName); |
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348 | goto again; |
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349 | } |
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350 | if (!ptr) |
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351 | { |
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352 | LogInfo("AddResourceRecords: Did not find any valid ResourceRecords"); |
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353 | *error = mStatus_NoSuchRecord; |
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354 | return mDNSNULL; |
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355 | } |
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356 | if (pc->rcvBufSize) |
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357 | { |
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358 | ptr = AddEDNS0Option(m, ptr, limit); |
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359 | if (!ptr) |
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360 | { |
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361 | *prevptr = orig; |
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362 | return mDNSNULL; |
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363 | } |
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364 | len += (ptr - orig); |
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365 | // orig = ptr; Commented out to avoid âvalue never readâ error message |
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366 | } |
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367 | LogInfo("AddResourceRecord: Added %d bytes to the packet", len); |
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368 | return ptr; |
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369 | } |
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370 | |
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371 | mDNSlocal void ProxyClientCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord) |
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372 | { |
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373 | DNSProxyClient *pc = question->QuestionContext; |
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374 | DNSProxyClient **ppc = &DNSProxyClients; |
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375 | mDNSu8 *ptr; |
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376 | mDNSu8 *prevptr; |
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377 | mStatus error; |
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378 | |
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379 | if (!AddRecord) |
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380 | return; |
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381 | |
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382 | LogInfo("ProxyClientCallback: ResourceRecord %s", RRDisplayString(m, answer)); |
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383 | |
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384 | // We asked for validation and not timed out yet, then wait for the DNSSEC result. |
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385 | // We have to set the AD bit in the response if it is secure which can't be done |
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386 | // till we get the DNSSEC result back (indicated by QC_dnssec). |
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387 | if (question->ValidationRequired) |
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388 | { |
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389 | mDNSs32 now; |
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390 | |
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391 | mDNS_Lock(m); |
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392 | now = m->timenow; |
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393 | mDNS_Unlock(m); |
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394 | if (((now - question->StopTime) < 0) && AddRecord != QC_dnssec) |
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395 | { |
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396 | LogInfo("ProxyClientCallback: No DNSSEC answer yet for Question %##s (%s), AddRecord %d, answer %s", question->qname.c, |
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397 | DNSTypeName(question->qtype), AddRecord, RRDisplayString(m, answer)); |
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398 | return; |
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399 | } |
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400 | } |
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401 | |
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402 | if (answer->RecordType != kDNSRecordTypePacketNegative) |
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403 | { |
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404 | if (answer->rrtype != question->qtype) |
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405 | { |
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406 | // Wait till we get called for the real response |
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407 | LogInfo("ProxyClientCallback: Received %s, not answering yet", RRDisplayString(m, answer)); |
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408 | return; |
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409 | } |
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410 | } |
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411 | ptr = AddResourceRecords(m, pc, &prevptr, &error); |
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412 | if (!ptr) |
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413 | { |
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414 | LogInfo("ProxyClientCallback: AddResourceRecords NULL for %##s (%s)", &pc->qname.c, DNSTypeName(pc->q.qtype)); |
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415 | if (error == mStatus_NoError && prevptr) |
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416 | { |
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417 | // No space to add the record. Set the Truncate bit for UDP. |
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418 | // |
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419 | // TBD: For TCP, we need to send the rest of the data. But finding out what is left |
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420 | // is harder. We should allocate enough buffer in the first place to send all |
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421 | // of the data. |
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422 | if (!pc->tcp) |
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423 | { |
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424 | m->omsg.h.flags.b[0] |= kDNSFlag0_TC; |
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425 | ptr = prevptr; |
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426 | } |
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427 | else |
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428 | { |
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429 | LogInfo("ProxyClientCallback: ERROR!! Not enough space to return in TCP for %##s (%s)", &pc->qname.c, DNSTypeName(pc->q.qtype)); |
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430 | ptr = prevptr; |
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431 | } |
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432 | } |
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433 | else |
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434 | { |
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435 | mDNSOpaque16 flags = { { kDNSFlag0_QR_Response | kDNSFlag0_OP_StdQuery, kDNSFlag1_RC_ServFail } }; |
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436 | // We could not find the record for some reason. Return a response, so that the client |
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437 | // is not waiting forever. |
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438 | LogInfo("ProxyClientCallback: No response"); |
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439 | if (!mDNSOpaque16IsZero(pc->q.responseFlags)) |
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440 | flags = pc->q.responseFlags; |
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441 | InitializeDNSMessage(&m->omsg.h, pc->msgid, flags); |
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442 | ptr = putQuestion(&m->omsg, m->omsg.data, m->omsg.data + AbsoluteMaxDNSMessageData, &pc->qname, pc->q.qtype, pc->q.qclass); |
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443 | if (!ptr) |
---|
444 | { |
---|
445 | LogInfo("ProxyClientCallback: putQuestion NULL for %##s (%s)", &pc->qname.c, DNSTypeName(pc->q.qtype)); |
---|
446 | goto done; |
---|
447 | } |
---|
448 | } |
---|
449 | } |
---|
450 | if (question->ValidationRequired) |
---|
451 | { |
---|
452 | if (question->ValidationState == DNSSECValDone && question->ValidationStatus == DNSSEC_Secure) |
---|
453 | { |
---|
454 | LogInfo("ProxyClientCallback: Setting AD bit for Question %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); |
---|
455 | m->omsg.h.flags.b[1] |= kDNSFlag1_AD; |
---|
456 | } |
---|
457 | else |
---|
458 | { |
---|
459 | // If some external resolver sets the AD bit and we did not validate the response securely, don't set |
---|
460 | // the AD bit. It is possible that we did not see all the records that the upstream resolver saw or |
---|
461 | // a buggy implementation somewhere. |
---|
462 | if (m->omsg.h.flags.b[1] & kDNSFlag1_AD) |
---|
463 | { |
---|
464 | LogInfo("ProxyClientCallback: AD bit set in the response for response that was not validated locally %##s (%s)", |
---|
465 | question->qname.c, DNSTypeName(question->qtype)); |
---|
466 | m->omsg.h.flags.b[1] &= ~kDNSFlag1_AD; |
---|
467 | } |
---|
468 | } |
---|
469 | } |
---|
470 | |
---|
471 | debugf("ProxyClientCallback: InterfaceID is %p for response to client", pc->interfaceID); |
---|
472 | |
---|
473 | if (!pc->tcp) |
---|
474 | { |
---|
475 | mDNSSendDNSMessage(m, &m->omsg, ptr, pc->interfaceID, (UDPSocket *)pc->socket, &pc->addr, pc->port, mDNSNULL, mDNSNULL, mDNSfalse); |
---|
476 | } |
---|
477 | else |
---|
478 | { |
---|
479 | mDNSSendDNSMessage(m, &m->omsg, ptr, pc->interfaceID, mDNSNULL, &pc->addr, pc->port, (TCPSocket *)pc->socket, mDNSNULL, mDNSfalse); |
---|
480 | } |
---|
481 | |
---|
482 | done: |
---|
483 | mDNS_StopQuery(m, question); |
---|
484 | |
---|
485 | while (*ppc && *ppc != pc) |
---|
486 | ppc=&(*ppc)->next; |
---|
487 | if (!*ppc) |
---|
488 | { |
---|
489 | LogMsg("ProxyClientCallback: question %##s (%s) not found", question->qname.c, DNSTypeName(question->qtype)); |
---|
490 | return; |
---|
491 | } |
---|
492 | *ppc = pc->next; |
---|
493 | mDNSPlatformDisposeProxyContext(pc->context); |
---|
494 | FreeDNSProxyClient(pc); |
---|
495 | } |
---|
496 | |
---|
497 | mDNSlocal void SendError(mDNS *const m, void *socket, DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *dstaddr, |
---|
498 | const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID, mDNSBool tcp, void *context, mDNSu8 rcode) |
---|
499 | { |
---|
500 | int pktlen = (int)(end - (mDNSu8 *)msg); |
---|
501 | |
---|
502 | // RFC 1035 requires that we copy the question back and RFC 2136 is okay with sending nothing |
---|
503 | // in the body or send back whatever we get for updates. It is easy to return whatever we get |
---|
504 | // in the question back to the responder. We return as much as we can fit in our standard |
---|
505 | // output packet. |
---|
506 | if (pktlen > AbsoluteMaxDNSMessageData) |
---|
507 | pktlen = AbsoluteMaxDNSMessageData; |
---|
508 | |
---|
509 | mDNSPlatformMemCopy(&m->omsg.h, &msg->h, sizeof(DNSMessageHeader)); |
---|
510 | m->omsg.h.flags.b[0] |= kDNSFlag0_QR_Response; |
---|
511 | m->omsg.h.flags.b[1] = rcode; |
---|
512 | mDNSPlatformMemCopy(m->omsg.data, (mDNSu8 *)&msg->h.numQuestions, pktlen); |
---|
513 | if (!tcp) |
---|
514 | { |
---|
515 | mDNSSendDNSMessage(m, &m->omsg, (mDNSu8 *)&m->omsg + pktlen, InterfaceID, socket, dstaddr, dstport, mDNSNULL, mDNSNULL, |
---|
516 | mDNSfalse); |
---|
517 | } |
---|
518 | else |
---|
519 | { |
---|
520 | mDNSSendDNSMessage(m, &m->omsg, (mDNSu8 *)&m->omsg + pktlen, InterfaceID, mDNSNULL, dstaddr, dstport, (TCPSocket *)socket, |
---|
521 | mDNSNULL, mDNSfalse); |
---|
522 | } |
---|
523 | mDNSPlatformDisposeProxyContext(context); |
---|
524 | } |
---|
525 | |
---|
526 | mDNSlocal DNSQuestion *IsDuplicateClient(const mDNS *const m, const mDNSAddr *const addr, const mDNSIPPort port, const mDNSOpaque16 id, |
---|
527 | const DNSQuestion *const question) |
---|
528 | { |
---|
529 | DNSProxyClient *pc; |
---|
530 | |
---|
531 | (void) m; // unused |
---|
532 | |
---|
533 | for (pc = DNSProxyClients; pc; pc = pc->next) |
---|
534 | { |
---|
535 | if (mDNSSameAddress(&pc->addr, addr) && |
---|
536 | mDNSSameIPPort(pc->port, port) && |
---|
537 | mDNSSameOpaque16(pc->msgid, id) && |
---|
538 | pc->q.qtype == question->qtype && |
---|
539 | pc->q.qclass == question->qclass && |
---|
540 | SameDomainName(&pc->qname, &question->qname)) |
---|
541 | { |
---|
542 | LogInfo("IsDuplicateClient: Found a duplicate client in the list"); |
---|
543 | return(&pc->q); |
---|
544 | } |
---|
545 | } |
---|
546 | return(mDNSNULL); |
---|
547 | } |
---|
548 | |
---|
549 | mDNSlocal mDNSBool CheckDNSProxyIpIntf(const mDNS *const m, mDNSInterfaceID InterfaceID) |
---|
550 | { |
---|
551 | int i; |
---|
552 | mDNSu32 ip_ifindex = (mDNSu32)(unsigned long)InterfaceID; |
---|
553 | |
---|
554 | LogInfo("CheckDNSProxyIpIntf: Check for ifindex[%d] in stored input interface list: [%d] [%d] [%d] [%d] [%d]", |
---|
555 | ip_ifindex, m->dp_ipintf[0], m->dp_ipintf[1], m->dp_ipintf[2], m->dp_ipintf[3], m->dp_ipintf[4]); |
---|
556 | |
---|
557 | if (ip_ifindex > 0) |
---|
558 | { |
---|
559 | for (i = 0; i < MaxIp; i++) |
---|
560 | { |
---|
561 | if (ip_ifindex == m->dp_ipintf[i]) |
---|
562 | return mDNStrue; |
---|
563 | } |
---|
564 | } |
---|
565 | |
---|
566 | LogMsg("CheckDNSProxyIpIntf: ifindex[%d] not in stored input interface list: [%d] [%d] [%d] [%d] [%d]", |
---|
567 | ip_ifindex, m->dp_ipintf[0], m->dp_ipintf[1], m->dp_ipintf[2], m->dp_ipintf[3], m->dp_ipintf[4]); |
---|
568 | |
---|
569 | return mDNSfalse; |
---|
570 | |
---|
571 | } |
---|
572 | |
---|
573 | mDNSlocal void ProxyCallbackCommon(mDNS *const m, void *socket, DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *const srcaddr, |
---|
574 | const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID, mDNSBool tcp, void *context) |
---|
575 | { |
---|
576 | mDNSu8 QR_OP; |
---|
577 | const mDNSu8 *ptr; |
---|
578 | DNSQuestion q, *qptr; |
---|
579 | DNSProxyClient *pc; |
---|
580 | const mDNSu8 *optRR = mDNSNULL; |
---|
581 | int optLen = 0; |
---|
582 | DNSProxyClient **ppc = &DNSProxyClients; |
---|
583 | |
---|
584 | (void) dstaddr; |
---|
585 | (void) dstport; |
---|
586 | |
---|
587 | debugf("ProxyCallbackCommon: DNS Query coming from InterfaceID %p", InterfaceID); |
---|
588 | // Ignore if the DNS Query is not from a Valid Input InterfaceID |
---|
589 | if (!CheckDNSProxyIpIntf(m, InterfaceID)) |
---|
590 | { |
---|
591 | LogMsg("ProxyCallbackCommon: Rejecting DNS Query coming from InterfaceID %p", InterfaceID); |
---|
592 | return; |
---|
593 | } |
---|
594 | |
---|
595 | if ((unsigned)(end - (mDNSu8 *)msg) < sizeof(DNSMessageHeader)) |
---|
596 | { |
---|
597 | debugf("ProxyCallbackCommon: DNS Message from %#a:%d to %#a:%d length %d too short", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), (int)(end - (mDNSu8 *)msg)); |
---|
598 | return; |
---|
599 | } |
---|
600 | |
---|
601 | QR_OP = (mDNSu8)(msg->h.flags.b[0] & kDNSFlag0_QROP_Mask); |
---|
602 | if (QR_OP != kDNSFlag0_QR_Query) |
---|
603 | { |
---|
604 | LogInfo("ProxyCallbackCommon: Not a query(%d) for pkt from %#a:%d", QR_OP, srcaddr, mDNSVal16(srcport)); |
---|
605 | SendError(m, socket, msg, end, srcaddr, srcport, InterfaceID, tcp, context, kDNSFlag1_RC_NotImpl); |
---|
606 | return; |
---|
607 | } |
---|
608 | |
---|
609 | // Read the integer parts which are in IETF byte-order (MSB first, LSB second) |
---|
610 | ptr = (mDNSu8 *)&msg->h.numQuestions; |
---|
611 | msg->h.numQuestions = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]); |
---|
612 | msg->h.numAnswers = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]); |
---|
613 | msg->h.numAuthorities = (mDNSu16)((mDNSu16)ptr[4] << 8 | ptr[5]); |
---|
614 | msg->h.numAdditionals = (mDNSu16)((mDNSu16)ptr[6] << 8 | ptr[7]); |
---|
615 | |
---|
616 | if (msg->h.numQuestions != 1 || msg->h.numAnswers || msg->h.numAuthorities) |
---|
617 | { |
---|
618 | LogInfo("ProxyCallbackCommon: Malformed pkt from %#a:%d, Q:%d, An:%d, Au:%d", srcaddr, mDNSVal16(srcport), |
---|
619 | msg->h.numQuestions, msg->h.numAnswers, msg->h.numAuthorities); |
---|
620 | SendError(m, socket, msg, end, srcaddr, srcport, InterfaceID, tcp, context, kDNSFlag1_RC_FormErr); |
---|
621 | return; |
---|
622 | } |
---|
623 | ptr = msg->data; |
---|
624 | ptr = getQuestion(msg, ptr, end, InterfaceID, &q); |
---|
625 | if (!ptr) |
---|
626 | { |
---|
627 | LogInfo("ProxyCallbackCommon: Question cannot be parsed for pkt from %#a:%d", srcaddr, mDNSVal16(srcport)); |
---|
628 | SendError(m, socket, msg, end, srcaddr, srcport, InterfaceID, tcp, context, kDNSFlag1_RC_FormErr); |
---|
629 | return; |
---|
630 | } |
---|
631 | else |
---|
632 | { |
---|
633 | LogInfo("ProxyCallbackCommon: Question %##s (%s)", q.qname.c, DNSTypeName(q.qtype)); |
---|
634 | } |
---|
635 | ptr = LocateOptRR(msg, end, 0); |
---|
636 | if (ptr) |
---|
637 | { |
---|
638 | optRR = ptr; |
---|
639 | ptr = skipResourceRecord(msg, ptr, end); |
---|
640 | // Be liberal and ignore the EDNS0 option if we can't parse it properly |
---|
641 | if (!ptr) |
---|
642 | { |
---|
643 | LogInfo("ProxyCallbackCommon: EDNS0 cannot be parsed for pkt from %#a:%d, ignoring", srcaddr, mDNSVal16(srcport)); |
---|
644 | } |
---|
645 | else |
---|
646 | { |
---|
647 | optLen = ptr - optRR; |
---|
648 | LogInfo("ProxyCallbackCommon: EDNS0 opt length %d present in Question %##s (%s)", optLen, q.qname.c, DNSTypeName(q.qtype)); |
---|
649 | } |
---|
650 | } |
---|
651 | else |
---|
652 | { |
---|
653 | LogInfo("ProxyCallbackCommon: EDNS0 opt not present in Question %##s (%s), ptr %p", q.qname.c, DNSTypeName(q.qtype), ptr); |
---|
654 | } |
---|
655 | |
---|
656 | qptr = IsDuplicateClient(m, srcaddr, srcport, msg->h.id, &q); |
---|
657 | if (qptr) |
---|
658 | { |
---|
659 | LogInfo("ProxyCallbackCommon: Found a duplicate for pkt from %#a:%d, ignoring this", srcaddr, mDNSVal16(srcport)); |
---|
660 | return; |
---|
661 | } |
---|
662 | pc = mDNSPlatformMemAllocate(sizeof(DNSProxyClient)); |
---|
663 | if (!pc) |
---|
664 | { |
---|
665 | LogMsg("ProxyCallbackCommon: Memory failure for pkt from %#a:%d, ignoring this", srcaddr, mDNSVal16(srcport)); |
---|
666 | return; |
---|
667 | } |
---|
668 | mDNSPlatformMemZero(pc, sizeof(DNSProxyClient)); |
---|
669 | pc->addr = *srcaddr; |
---|
670 | pc->port = srcport; |
---|
671 | pc->msgid = msg->h.id; |
---|
672 | pc->interfaceID = InterfaceID; // input interface |
---|
673 | pc->socket = socket; |
---|
674 | pc->tcp = tcp; |
---|
675 | pc->requestFlags = msg->h.flags; |
---|
676 | pc->context = context; |
---|
677 | AssignDomainName(&pc->qname, &q.qname); |
---|
678 | if (optRR) |
---|
679 | { |
---|
680 | if (!ParseEDNS0(pc, optRR, optLen, end)) |
---|
681 | { |
---|
682 | LogInfo("ProxyCallbackCommon: Invalid EDNS0 option for pkt from %#a:%d, ignoring this", srcaddr, mDNSVal16(srcport)); |
---|
683 | } |
---|
684 | else |
---|
685 | { |
---|
686 | pc->optRR = mDNSPlatformMemAllocate(optLen); |
---|
687 | if (!pc->optRR) |
---|
688 | { |
---|
689 | LogMsg("ProxyCallbackCommon: Memory failure for pkt from %#a:%d, ignoring this", srcaddr, mDNSVal16(srcport)); |
---|
690 | FreeDNSProxyClient(pc); |
---|
691 | return; |
---|
692 | } |
---|
693 | mDNSPlatformMemCopy(pc->optRR, optRR, optLen); |
---|
694 | pc->optLen = optLen; |
---|
695 | } |
---|
696 | } |
---|
697 | |
---|
698 | debugf("ProxyCallbackCommon: DNS Query forwarding to interface index %d", m->dp_opintf); |
---|
699 | mDNS_SetupQuestion(&pc->q, (mDNSInterfaceID)(unsigned long)m->dp_opintf, &q.qname, q.qtype, ProxyClientCallback, pc); |
---|
700 | pc->q.TimeoutQuestion = 1; |
---|
701 | // Set ReturnIntermed so that we get the negative responses |
---|
702 | pc->q.ReturnIntermed = mDNStrue; |
---|
703 | pc->q.ProxyQuestion = mDNStrue; |
---|
704 | pc->q.ProxyDNSSECOK = pc->DNSSECOK; |
---|
705 | pc->q.responseFlags = zeroID; |
---|
706 | if (pc->DNSSECOK) |
---|
707 | { |
---|
708 | if (!(msg->h.flags.b[1] & kDNSFlag1_CD) && pc->q.qtype != kDNSType_RRSIG && pc->q.qtype != kDNSQType_ANY) |
---|
709 | { |
---|
710 | LogInfo("ProxyCallbackCommon: Setting Validation required bit for %#a:%d, validating %##s (%s)", srcaddr, mDNSVal16(srcport), |
---|
711 | q.qname.c, DNSTypeName(q.qtype)); |
---|
712 | pc->q.ValidationRequired = DNSSEC_VALIDATION_SECURE; |
---|
713 | } |
---|
714 | else |
---|
715 | { |
---|
716 | LogInfo("ProxyCallbackCommon: CD bit not set OR not a valid type for %#a:%d, not validating %##s (%s)", srcaddr, mDNSVal16(srcport), |
---|
717 | q.qname.c, DNSTypeName(q.qtype)); |
---|
718 | } |
---|
719 | } |
---|
720 | else |
---|
721 | { |
---|
722 | LogInfo("ProxyCallbackCommon: DNSSEC OK bit not set for %#a:%d, not validating %##s (%s)", srcaddr, mDNSVal16(srcport), |
---|
723 | q.qname.c, DNSTypeName(q.qtype)); |
---|
724 | } |
---|
725 | |
---|
726 | while (*ppc) |
---|
727 | ppc = &((*ppc)->next); |
---|
728 | *ppc = pc; |
---|
729 | |
---|
730 | mDNS_StartQuery(m, &pc->q); |
---|
731 | } |
---|
732 | |
---|
733 | mDNSexport void ProxyUDPCallback(mDNS *const m, void *socket, DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *const srcaddr, |
---|
734 | const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID, void *context) |
---|
735 | { |
---|
736 | LogInfo("ProxyUDPCallback: DNS Message from %#a:%d to %#a:%d length %d", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), (int)(end - (mDNSu8 *)msg)); |
---|
737 | ProxyCallbackCommon(m, socket, msg, end, srcaddr, srcport, dstaddr, dstport, InterfaceID, mDNSfalse, context); |
---|
738 | } |
---|
739 | |
---|
740 | mDNSexport void ProxyTCPCallback(mDNS *const m, void *socket, DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *const srcaddr, |
---|
741 | const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID, void *context) |
---|
742 | { |
---|
743 | LogInfo("ProxyTCPCallback: DNS Message from %#a:%d to %#a:%d length %d", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), (int)(end - (mDNSu8 *)msg)); |
---|
744 | |
---|
745 | // If the connection was closed from the other side or incoming packet does not match stored input interface list, locate the client |
---|
746 | // state and free it. |
---|
747 | if (((end - (mDNSu8 *)msg) == 0) || (!CheckDNSProxyIpIntf(m, InterfaceID))) |
---|
748 | { |
---|
749 | DNSProxyClient **ppc = &DNSProxyClients; |
---|
750 | DNSProxyClient **prevpc; |
---|
751 | |
---|
752 | prevpc = ppc; |
---|
753 | while (*ppc && (*ppc)->socket != socket) |
---|
754 | { |
---|
755 | prevpc = ppc; |
---|
756 | ppc=&(*ppc)->next; |
---|
757 | } |
---|
758 | if (!*ppc) |
---|
759 | { |
---|
760 | mDNSPlatformDisposeProxyContext(socket); |
---|
761 | LogMsg("ProxyTCPCallback: socket cannot be found"); |
---|
762 | return; |
---|
763 | } |
---|
764 | *prevpc = (*ppc)->next; |
---|
765 | LogInfo("ProxyTCPCallback: free"); |
---|
766 | mDNSPlatformDisposeProxyContext(socket); |
---|
767 | FreeDNSProxyClient(*ppc); |
---|
768 | return; |
---|
769 | } |
---|
770 | ProxyCallbackCommon(m, socket, msg, end, srcaddr, srcport, dstaddr, dstport, InterfaceID, mDNStrue, context); |
---|
771 | } |
---|
772 | |
---|
773 | mDNSexport void DNSProxyInit(mDNS *const m, mDNSu32 IpIfArr[MaxIp], mDNSu32 OpIf) |
---|
774 | { |
---|
775 | int i; |
---|
776 | |
---|
777 | // Store DNSProxy Interface fields in mDNS struct |
---|
778 | for (i = 0; i < MaxIp; i++) |
---|
779 | m->dp_ipintf[i] = IpIfArr[i]; |
---|
780 | m->dp_opintf = OpIf; |
---|
781 | |
---|
782 | LogInfo("DNSProxyInit Storing interface list: Input [%d, %d, %d, %d, %d] Output [%d]", m->dp_ipintf[0], |
---|
783 | m->dp_ipintf[1], m->dp_ipintf[2], m->dp_ipintf[3], m->dp_ipintf[4], m->dp_opintf); |
---|
784 | } |
---|
785 | |
---|
786 | mDNSexport void DNSProxyTerminate(mDNS *const m) |
---|
787 | { |
---|
788 | int i; |
---|
789 | |
---|
790 | // Clear DNSProxy Interface fields from mDNS struct |
---|
791 | for (i = 0; i < MaxIp; i++) |
---|
792 | m->dp_ipintf[i] = 0; |
---|
793 | m->dp_opintf = 0; |
---|
794 | |
---|
795 | LogInfo("DNSProxyTerminate Cleared interface list: Input [%d, %d, %d, %d, %d] Output [%d]", m->dp_ipintf[0], |
---|
796 | m->dp_ipintf[1], m->dp_ipintf[2], m->dp_ipintf[3], m->dp_ipintf[4], m->dp_opintf); |
---|
797 | } |
---|
798 | #else // UNICAST_DISABLED |
---|
799 | |
---|
800 | mDNSexport void ProxyUDPCallback(mDNS *const m, void *socket, DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID, void *context) |
---|
801 | { |
---|
802 | (void) m; |
---|
803 | (void) socket; |
---|
804 | (void) msg; |
---|
805 | (void) end; |
---|
806 | (void) srcaddr; |
---|
807 | (void) srcport; |
---|
808 | (void) dstaddr; |
---|
809 | (void) dstport; |
---|
810 | (void) InterfaceID; |
---|
811 | (void) context; |
---|
812 | } |
---|
813 | |
---|
814 | mDNSexport void ProxyTCPCallback(mDNS *const m, void *socket, DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID, void *context) |
---|
815 | { |
---|
816 | (void) m; |
---|
817 | (void) socket; |
---|
818 | (void) msg; |
---|
819 | (void) end; |
---|
820 | (void) srcaddr; |
---|
821 | (void) srcport; |
---|
822 | (void) dstaddr; |
---|
823 | (void) dstport; |
---|
824 | (void) InterfaceID; |
---|
825 | (void) context; |
---|
826 | } |
---|
827 | |
---|
828 | mDNSexport void DNSProxyInit(mDNS *const m, mDNSu32 IpIfArr[MaxIp], mDNSu32 OpIf) |
---|
829 | { |
---|
830 | (void) m; |
---|
831 | (void) IpIfArr; |
---|
832 | (void) OpIf; |
---|
833 | } |
---|
834 | extern void DNSProxyTerminate(mDNS *const m) |
---|
835 | { |
---|
836 | (void) m; |
---|
837 | } |
---|
838 | |
---|
839 | |
---|
840 | #endif // UNICAST_DISABLED |
---|