A stack which works with or without an Mbed os library. Provides IPv4 or IPv6 with a full 1500 byte buffer.
Dependents: oldheating gps motorhome heating
udp/dns/dnsreply.cpp@13:9cd54f7db57a, 2017-05-01 (annotated)
- Committer:
- andrewboyson
- Date:
- Mon May 01 18:20:55 2017 +0000
- Revision:
- 13:9cd54f7db57a
- Child:
- 14:e75a59c1123d
Added ability to read DNS queries with encoded IP addresses
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
andrewboyson | 13:9cd54f7db57a | 1 | #include "mbed.h" |
andrewboyson | 13:9cd54f7db57a | 2 | #include "log.h" |
andrewboyson | 13:9cd54f7db57a | 3 | #include "net.h" |
andrewboyson | 13:9cd54f7db57a | 4 | #include "dns.h" |
andrewboyson | 13:9cd54f7db57a | 5 | #include "dnshdr.h" |
andrewboyson | 13:9cd54f7db57a | 6 | #include "dnsname.h" |
andrewboyson | 13:9cd54f7db57a | 7 | #include "ar.h" |
andrewboyson | 13:9cd54f7db57a | 8 | |
andrewboyson | 13:9cd54f7db57a | 9 | #define DEBUG true |
andrewboyson | 13:9cd54f7db57a | 10 | |
andrewboyson | 13:9cd54f7db57a | 11 | char DnsReplyRecordName[256]; |
andrewboyson | 13:9cd54f7db57a | 12 | uint32_t DnsReplyRecordNameAsIp4 = 0; |
andrewboyson | 13:9cd54f7db57a | 13 | char DnsReplyRecordNameAsIp6[16]; |
andrewboyson | 13:9cd54f7db57a | 14 | char DnsReplyName[64]; |
andrewboyson | 13:9cd54f7db57a | 15 | uint32_t DnsReplyIp4 = 0; |
andrewboyson | 13:9cd54f7db57a | 16 | char DnsReplyIp6[16]; |
andrewboyson | 13:9cd54f7db57a | 17 | |
andrewboyson | 13:9cd54f7db57a | 18 | static char *p; |
andrewboyson | 13:9cd54f7db57a | 19 | static int recordNameOffset; |
andrewboyson | 13:9cd54f7db57a | 20 | static int recordType; |
andrewboyson | 13:9cd54f7db57a | 21 | static int recordDataLength; |
andrewboyson | 13:9cd54f7db57a | 22 | static char* pRecordData; |
andrewboyson | 13:9cd54f7db57a | 23 | |
andrewboyson | 13:9cd54f7db57a | 24 | static int scanQuery() |
andrewboyson | 13:9cd54f7db57a | 25 | { |
andrewboyson | 13:9cd54f7db57a | 26 | int recordNameLength = DnsNameLength(p); |
andrewboyson | 13:9cd54f7db57a | 27 | if (!recordNameLength) |
andrewboyson | 13:9cd54f7db57a | 28 | { |
andrewboyson | 13:9cd54f7db57a | 29 | LogTimeF("DnsReply scanRecord name length of zero\r\n"); |
andrewboyson | 13:9cd54f7db57a | 30 | return -1; //failure |
andrewboyson | 13:9cd54f7db57a | 31 | } |
andrewboyson | 13:9cd54f7db57a | 32 | |
andrewboyson | 13:9cd54f7db57a | 33 | recordNameOffset = DnsNameIndexFromPointer(p); |
andrewboyson | 13:9cd54f7db57a | 34 | p += recordNameLength; |
andrewboyson | 13:9cd54f7db57a | 35 | |
andrewboyson | 13:9cd54f7db57a | 36 | p++ ; //skip the first byte of the type |
andrewboyson | 13:9cd54f7db57a | 37 | recordType = *p++; |
andrewboyson | 13:9cd54f7db57a | 38 | |
andrewboyson | 13:9cd54f7db57a | 39 | p += 2; //skip the class |
andrewboyson | 13:9cd54f7db57a | 40 | |
andrewboyson | 13:9cd54f7db57a | 41 | return 0; //success |
andrewboyson | 13:9cd54f7db57a | 42 | } |
andrewboyson | 13:9cd54f7db57a | 43 | |
andrewboyson | 13:9cd54f7db57a | 44 | static int scanAnswer() |
andrewboyson | 13:9cd54f7db57a | 45 | { |
andrewboyson | 13:9cd54f7db57a | 46 | int recordNameLength = DnsNameLength(p); |
andrewboyson | 13:9cd54f7db57a | 47 | if (!recordNameLength) |
andrewboyson | 13:9cd54f7db57a | 48 | { |
andrewboyson | 13:9cd54f7db57a | 49 | LogTimeF("DnsReply scanRecord name length of zero\r\n"); |
andrewboyson | 13:9cd54f7db57a | 50 | return -1; //failure |
andrewboyson | 13:9cd54f7db57a | 51 | } |
andrewboyson | 13:9cd54f7db57a | 52 | |
andrewboyson | 13:9cd54f7db57a | 53 | recordNameOffset = DnsNameIndexFromPointer(p); |
andrewboyson | 13:9cd54f7db57a | 54 | p += recordNameLength; |
andrewboyson | 13:9cd54f7db57a | 55 | |
andrewboyson | 13:9cd54f7db57a | 56 | p++ ; //skip the first byte of the type |
andrewboyson | 13:9cd54f7db57a | 57 | recordType = *p++; |
andrewboyson | 13:9cd54f7db57a | 58 | |
andrewboyson | 13:9cd54f7db57a | 59 | p += 6; //skip the class, TTL |
andrewboyson | 13:9cd54f7db57a | 60 | recordDataLength = 0; |
andrewboyson | 13:9cd54f7db57a | 61 | recordDataLength |= *p++ << 8; |
andrewboyson | 13:9cd54f7db57a | 62 | recordDataLength |= *p++; |
andrewboyson | 13:9cd54f7db57a | 63 | |
andrewboyson | 13:9cd54f7db57a | 64 | pRecordData = p; //record the start of the data |
andrewboyson | 13:9cd54f7db57a | 65 | |
andrewboyson | 13:9cd54f7db57a | 66 | p += recordDataLength; //Move to the start of the next record |
andrewboyson | 13:9cd54f7db57a | 67 | |
andrewboyson | 13:9cd54f7db57a | 68 | return 0; //success |
andrewboyson | 13:9cd54f7db57a | 69 | } |
andrewboyson | 13:9cd54f7db57a | 70 | static void readAnswer() |
andrewboyson | 13:9cd54f7db57a | 71 | { |
andrewboyson | 13:9cd54f7db57a | 72 | DnsReplyRecordName[0] = 0; |
andrewboyson | 13:9cd54f7db57a | 73 | DnsReplyRecordNameAsIp4 = 0; |
andrewboyson | 13:9cd54f7db57a | 74 | DnsReplyRecordNameAsIp6[0] = 0; |
andrewboyson | 13:9cd54f7db57a | 75 | DnsReplyName[0] = 0; |
andrewboyson | 13:9cd54f7db57a | 76 | DnsReplyIp4 = 0; |
andrewboyson | 13:9cd54f7db57a | 77 | DnsReplyIp6[0] = 0; |
andrewboyson | 13:9cd54f7db57a | 78 | |
andrewboyson | 13:9cd54f7db57a | 79 | switch (recordType) |
andrewboyson | 13:9cd54f7db57a | 80 | { |
andrewboyson | 13:9cd54f7db57a | 81 | case DNS_RECORD_A: |
andrewboyson | 13:9cd54f7db57a | 82 | case DNS_RECORD_AAAA: |
andrewboyson | 13:9cd54f7db57a | 83 | case DNS_RECORD_PTR: |
andrewboyson | 13:9cd54f7db57a | 84 | break; |
andrewboyson | 13:9cd54f7db57a | 85 | default: |
andrewboyson | 13:9cd54f7db57a | 86 | LogTimeF("DnsReply readAnswer unrecognised record type %d\r\n", recordType); |
andrewboyson | 13:9cd54f7db57a | 87 | return; } |
andrewboyson | 13:9cd54f7db57a | 88 | |
andrewboyson | 13:9cd54f7db57a | 89 | DnsNameDecode (recordNameOffset, sizeof(DnsReplyRecordName), DnsReplyRecordName); |
andrewboyson | 13:9cd54f7db57a | 90 | DnsNameDecodeIp4(recordNameOffset, &DnsReplyRecordNameAsIp4); |
andrewboyson | 13:9cd54f7db57a | 91 | DnsNameDecodeIp6(recordNameOffset, DnsReplyRecordNameAsIp6); |
andrewboyson | 13:9cd54f7db57a | 92 | if (DEBUG) |
andrewboyson | 13:9cd54f7db57a | 93 | { |
andrewboyson | 13:9cd54f7db57a | 94 | LogF(" record name as string %s\r\n", DnsReplyRecordName); |
andrewboyson | 13:9cd54f7db57a | 95 | char text[100]; |
andrewboyson | 13:9cd54f7db57a | 96 | if (DnsReplyRecordNameAsIp4) |
andrewboyson | 13:9cd54f7db57a | 97 | { |
andrewboyson | 13:9cd54f7db57a | 98 | NetIp4AddressToString(DnsReplyRecordNameAsIp4, sizeof(text), text); |
andrewboyson | 13:9cd54f7db57a | 99 | LogF(" record name as ip4 %s\r\n", text); |
andrewboyson | 13:9cd54f7db57a | 100 | } |
andrewboyson | 13:9cd54f7db57a | 101 | if (DnsReplyRecordNameAsIp6[0]) |
andrewboyson | 13:9cd54f7db57a | 102 | { |
andrewboyson | 13:9cd54f7db57a | 103 | NetIp6AddressToString(DnsReplyRecordNameAsIp6, sizeof(text), text); |
andrewboyson | 13:9cd54f7db57a | 104 | LogF(" record name as ip6 %s\r\n", text); |
andrewboyson | 13:9cd54f7db57a | 105 | } |
andrewboyson | 13:9cd54f7db57a | 106 | DnsRecordTypeToString(recordType, sizeof(text), text); |
andrewboyson | 13:9cd54f7db57a | 107 | LogF(" record type %s\r\n", text); |
andrewboyson | 13:9cd54f7db57a | 108 | LogF(" record data length %d bytes\r\n", recordDataLength); |
andrewboyson | 13:9cd54f7db57a | 109 | } |
andrewboyson | 13:9cd54f7db57a | 110 | |
andrewboyson | 13:9cd54f7db57a | 111 | switch (recordType) |
andrewboyson | 13:9cd54f7db57a | 112 | { |
andrewboyson | 13:9cd54f7db57a | 113 | case DNS_RECORD_A: |
andrewboyson | 13:9cd54f7db57a | 114 | if (recordDataLength != 4) |
andrewboyson | 13:9cd54f7db57a | 115 | { |
andrewboyson | 13:9cd54f7db57a | 116 | LogTimeF("DnsReply A type length of %d\r\n", recordDataLength); |
andrewboyson | 13:9cd54f7db57a | 117 | return; |
andrewboyson | 13:9cd54f7db57a | 118 | } |
andrewboyson | 13:9cd54f7db57a | 119 | memcpy(&DnsReplyIp4, pRecordData, 4); |
andrewboyson | 13:9cd54f7db57a | 120 | break; |
andrewboyson | 13:9cd54f7db57a | 121 | case DNS_RECORD_AAAA: |
andrewboyson | 13:9cd54f7db57a | 122 | if (recordDataLength != 16) |
andrewboyson | 13:9cd54f7db57a | 123 | { |
andrewboyson | 13:9cd54f7db57a | 124 | LogTimeF("DnsReply AAAA type length of %d\r\n", recordDataLength); |
andrewboyson | 13:9cd54f7db57a | 125 | return; |
andrewboyson | 13:9cd54f7db57a | 126 | } |
andrewboyson | 13:9cd54f7db57a | 127 | memcpy(DnsReplyIp6, pRecordData, 16); |
andrewboyson | 13:9cd54f7db57a | 128 | break; |
andrewboyson | 13:9cd54f7db57a | 129 | case DNS_RECORD_PTR: |
andrewboyson | 13:9cd54f7db57a | 130 | if (recordDataLength > 63) |
andrewboyson | 13:9cd54f7db57a | 131 | { |
andrewboyson | 13:9cd54f7db57a | 132 | LogTimeF("DnsReply PTR type length of %d\r\n", recordDataLength); |
andrewboyson | 13:9cd54f7db57a | 133 | return; |
andrewboyson | 13:9cd54f7db57a | 134 | } |
andrewboyson | 13:9cd54f7db57a | 135 | DnsNameDecode(DnsNameIndexFromPointer(pRecordData), sizeof(DnsReplyName), DnsReplyName); |
andrewboyson | 13:9cd54f7db57a | 136 | break; |
andrewboyson | 13:9cd54f7db57a | 137 | } |
andrewboyson | 13:9cd54f7db57a | 138 | if (DEBUG) |
andrewboyson | 13:9cd54f7db57a | 139 | { |
andrewboyson | 13:9cd54f7db57a | 140 | char text[100]; |
andrewboyson | 13:9cd54f7db57a | 141 | switch (recordType) |
andrewboyson | 13:9cd54f7db57a | 142 | { |
andrewboyson | 13:9cd54f7db57a | 143 | case DNS_RECORD_A: |
andrewboyson | 13:9cd54f7db57a | 144 | NetIp4AddressToString(DnsReplyIp4, sizeof(text), text); |
andrewboyson | 13:9cd54f7db57a | 145 | LogF(" ip4 %s\r\n", text); |
andrewboyson | 13:9cd54f7db57a | 146 | break; |
andrewboyson | 13:9cd54f7db57a | 147 | case DNS_RECORD_AAAA: |
andrewboyson | 13:9cd54f7db57a | 148 | NetIp6AddressToString(DnsReplyIp6, sizeof(text), text); |
andrewboyson | 13:9cd54f7db57a | 149 | LogF(" ip6 %s\r\n", text); |
andrewboyson | 13:9cd54f7db57a | 150 | break; |
andrewboyson | 13:9cd54f7db57a | 151 | case DNS_RECORD_PTR: |
andrewboyson | 13:9cd54f7db57a | 152 | LogF(" ptr %s\r\n", DnsReplyName); |
andrewboyson | 13:9cd54f7db57a | 153 | break; |
andrewboyson | 13:9cd54f7db57a | 154 | } |
andrewboyson | 13:9cd54f7db57a | 155 | } |
andrewboyson | 13:9cd54f7db57a | 156 | } |
andrewboyson | 13:9cd54f7db57a | 157 | |
andrewboyson | 13:9cd54f7db57a | 158 | static void sendToAr(int dnsProtocol) |
andrewboyson | 13:9cd54f7db57a | 159 | { |
andrewboyson | 13:9cd54f7db57a | 160 | if (DnsReplyIp4 && DnsReplyRecordName[0]) ArAddName4(DnsReplyIp4, DnsReplyRecordName, dnsProtocol); |
andrewboyson | 13:9cd54f7db57a | 161 | if (DnsReplyIp6[0] && DnsReplyRecordName[0]) ArAddName6(DnsReplyIp6, DnsReplyRecordName, dnsProtocol); |
andrewboyson | 13:9cd54f7db57a | 162 | if (DnsReplyRecordNameAsIp4 && DnsReplyName[0] ) ArAddName4(DnsReplyRecordNameAsIp4, DnsReplyName, dnsProtocol); |
andrewboyson | 13:9cd54f7db57a | 163 | if (DnsReplyRecordNameAsIp6[0] && DnsReplyName[0] ) ArAddName6(DnsReplyRecordNameAsIp6, DnsReplyName, dnsProtocol); |
andrewboyson | 13:9cd54f7db57a | 164 | } |
andrewboyson | 13:9cd54f7db57a | 165 | int DnsReplyHandle(int dnsProtocol, int *pSize) |
andrewboyson | 13:9cd54f7db57a | 166 | { |
andrewboyson | 13:9cd54f7db57a | 167 | if (!DnsHdrAncount) return DO_NOTHING; |
andrewboyson | 13:9cd54f7db57a | 168 | if (DEBUG) DnsHdrLog("received reply", dnsProtocol); |
andrewboyson | 13:9cd54f7db57a | 169 | |
andrewboyson | 13:9cd54f7db57a | 170 | p = DnsHdrData; |
andrewboyson | 13:9cd54f7db57a | 171 | |
andrewboyson | 13:9cd54f7db57a | 172 | for (int q = 0; q < DnsHdrQdcount; q++) |
andrewboyson | 13:9cd54f7db57a | 173 | { |
andrewboyson | 13:9cd54f7db57a | 174 | if (scanQuery()) return DO_NOTHING; |
andrewboyson | 13:9cd54f7db57a | 175 | } |
andrewboyson | 13:9cd54f7db57a | 176 | for (int a = 0; a < DnsHdrAncount; a++) |
andrewboyson | 13:9cd54f7db57a | 177 | { |
andrewboyson | 13:9cd54f7db57a | 178 | if (scanAnswer()) return DO_NOTHING; |
andrewboyson | 13:9cd54f7db57a | 179 | readAnswer(); |
andrewboyson | 13:9cd54f7db57a | 180 | sendToAr(dnsProtocol); |
andrewboyson | 13:9cd54f7db57a | 181 | } |
andrewboyson | 13:9cd54f7db57a | 182 | |
andrewboyson | 13:9cd54f7db57a | 183 | return DO_NOTHING; |
andrewboyson | 13:9cd54f7db57a | 184 | } |