Andrew Boyson / net

A stack which works with or without an Mbed os library. Provides IPv4 or IPv6 with a full 1500 byte buffer.

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udp/dns/dnshdr.cpp@47:73af5c0b0dc2, 2017-10-26 (annotated)

Committer:
andrewboyson
Date:
Thu Oct 26 14:50:24 2017 +0000
Revision:
47:73af5c0b0dc2
Parent:
44:83ce5ace337b
Child:
49:1a6336f2b3f9
Replaced a number of temporary buffers with direct writes to the Log or HTTP.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 13:9cd54f7db57a 1 #include "mbed.h"
andrewboyson 13:9cd54f7db57a 2 #include "dns.h"
andrewboyson 13:9cd54f7db57a 3 #include "net.h"
andrewboyson 13:9cd54f7db57a 4 #include "log.h"
andrewboyson 14:e75a59c1123d 5 #include "net.h"
andrewboyson 14:e75a59c1123d 6 #include "eth.h"
andrewboyson 14:e75a59c1123d 7 #include "ip4.h"
andrewboyson 14:e75a59c1123d 8 #include "ip6.h"
andrewboyson 14:e75a59c1123d 9 #include "udp.h"
andrewboyson 37:793b39683406 10 #include "dnsname.h"
andrewboyson 13:9cd54f7db57a 11
andrewboyson 13:9cd54f7db57a 12 #define HEADER_LENGTH 12
andrewboyson 13:9cd54f7db57a 13
andrewboyson 13:9cd54f7db57a 14 __packed struct header
andrewboyson 13:9cd54f7db57a 15 {
andrewboyson 13:9cd54f7db57a 16 uint16_t id;
andrewboyson 13:9cd54f7db57a 17 uint8_t uflags;
andrewboyson 13:9cd54f7db57a 18 uint8_t lflags;
andrewboyson 13:9cd54f7db57a 19
andrewboyson 13:9cd54f7db57a 20 uint16_t qdcount;
andrewboyson 13:9cd54f7db57a 21 uint16_t ancount;
andrewboyson 13:9cd54f7db57a 22 uint16_t nscount;
andrewboyson 13:9cd54f7db57a 23 uint16_t arcount;
andrewboyson 13:9cd54f7db57a 24 };
andrewboyson 13:9cd54f7db57a 25
andrewboyson 13:9cd54f7db57a 26 uint16_t DnsHdrId;
andrewboyson 13:9cd54f7db57a 27
andrewboyson 13:9cd54f7db57a 28 bool DnsHdrIsReply;
andrewboyson 13:9cd54f7db57a 29 bool DnsHdrIsAuthoritative;
andrewboyson 13:9cd54f7db57a 30 bool DnsHdrIsRecursiveQuery;
andrewboyson 13:9cd54f7db57a 31
andrewboyson 13:9cd54f7db57a 32 uint16_t DnsHdrQdcount;
andrewboyson 13:9cd54f7db57a 33 uint16_t DnsHdrAncount;
andrewboyson 13:9cd54f7db57a 34 uint16_t DnsHdrNscount;
andrewboyson 13:9cd54f7db57a 35 uint16_t DnsHdrArcount;
andrewboyson 13:9cd54f7db57a 36
andrewboyson 13:9cd54f7db57a 37 char* DnsHdrPacket;
andrewboyson 13:9cd54f7db57a 38 char* DnsHdrData;
andrewboyson 13:9cd54f7db57a 39
andrewboyson 13:9cd54f7db57a 40 void DnsHdrSetup(void* pPacket)
andrewboyson 13:9cd54f7db57a 41 {
andrewboyson 13:9cd54f7db57a 42 DnsHdrPacket = (char*)pPacket;
andrewboyson 13:9cd54f7db57a 43 DnsHdrData = DnsHdrPacket + HEADER_LENGTH;
andrewboyson 13:9cd54f7db57a 44 }
andrewboyson 13:9cd54f7db57a 45
andrewboyson 13:9cd54f7db57a 46 void DnsHdrRead()
andrewboyson 13:9cd54f7db57a 47 {
andrewboyson 13:9cd54f7db57a 48 struct header* pHeader = (header*)DnsHdrPacket;
andrewboyson 13:9cd54f7db57a 49
andrewboyson 13:9cd54f7db57a 50 DnsHdrId = NetToHost16(pHeader->id);
andrewboyson 13:9cd54f7db57a 51
andrewboyson 13:9cd54f7db57a 52 uint8_t uflags = pHeader->uflags;
andrewboyson 13:9cd54f7db57a 53 DnsHdrIsReply = uflags & 0x80;
andrewboyson 13:9cd54f7db57a 54 DnsHdrIsAuthoritative = uflags & 0x04;
andrewboyson 33:714a0345e59b 55 DnsHdrIsRecursiveQuery = uflags & 0x01;
andrewboyson 13:9cd54f7db57a 56
andrewboyson 13:9cd54f7db57a 57 DnsHdrQdcount = NetToHost16(pHeader->qdcount);
andrewboyson 13:9cd54f7db57a 58 DnsHdrAncount = NetToHost16(pHeader->ancount);
andrewboyson 13:9cd54f7db57a 59 DnsHdrNscount = NetToHost16(pHeader->nscount);
andrewboyson 13:9cd54f7db57a 60 DnsHdrArcount = NetToHost16(pHeader->arcount);
andrewboyson 13:9cd54f7db57a 61
andrewboyson 13:9cd54f7db57a 62 }
andrewboyson 13:9cd54f7db57a 63 void DnsHdrWrite()
andrewboyson 13:9cd54f7db57a 64 {
andrewboyson 13:9cd54f7db57a 65 struct header* pHeader = (header*)DnsHdrPacket;
andrewboyson 13:9cd54f7db57a 66
andrewboyson 13:9cd54f7db57a 67 pHeader->id = NetToHost16(DnsHdrId);
andrewboyson 13:9cd54f7db57a 68
andrewboyson 13:9cd54f7db57a 69 uint8_t uflags = 0;
andrewboyson 13:9cd54f7db57a 70 uint8_t lflags = 0;
andrewboyson 13:9cd54f7db57a 71 if (DnsHdrIsReply) uflags |= 0x80;
andrewboyson 13:9cd54f7db57a 72 if (DnsHdrIsAuthoritative) uflags |= 0x04;
andrewboyson 13:9cd54f7db57a 73 if (DnsHdrIsRecursiveQuery) uflags |= 0x01;
andrewboyson 13:9cd54f7db57a 74 pHeader->uflags = uflags;
andrewboyson 13:9cd54f7db57a 75 pHeader->lflags = lflags;
andrewboyson 13:9cd54f7db57a 76
andrewboyson 13:9cd54f7db57a 77 pHeader->qdcount = NetToHost16(DnsHdrQdcount);
andrewboyson 13:9cd54f7db57a 78 pHeader->ancount = NetToHost16(DnsHdrAncount);
andrewboyson 13:9cd54f7db57a 79 pHeader->nscount = NetToHost16(DnsHdrNscount);
andrewboyson 13:9cd54f7db57a 80 pHeader->arcount = NetToHost16(DnsHdrArcount);
andrewboyson 13:9cd54f7db57a 81 }
andrewboyson 37:793b39683406 82 static void logContent()
andrewboyson 37:793b39683406 83 {
andrewboyson 37:793b39683406 84 char* p = DnsHdrData; //Local version of p which does not upset the global p used to build the response
andrewboyson 37:793b39683406 85
andrewboyson 37:793b39683406 86 char iEncodedName;
andrewboyson 37:793b39683406 87
andrewboyson 37:793b39683406 88 //Get the questions
andrewboyson 37:793b39683406 89 for (int q = 0; q < DnsHdrQdcount; q++)
andrewboyson 37:793b39683406 90 {
andrewboyson 37:793b39683406 91 if (p > DnsHdrData + 500)
andrewboyson 37:793b39683406 92 {
andrewboyson 37:793b39683406 93 Log("Questions have overrun the buffer\r\n");
andrewboyson 37:793b39683406 94 return;
andrewboyson 37:793b39683406 95 }
andrewboyson 37:793b39683406 96 iEncodedName = DnsNameIndexFromPointer(p);
andrewboyson 37:793b39683406 97 int nameLength = DnsNameLength(p);
andrewboyson 37:793b39683406 98 if (!nameLength) { LogTimeF("DnsServer-readQuestions namelength is zero\r\n"); return; }
andrewboyson 37:793b39683406 99 p += nameLength; //Skip past the name
andrewboyson 37:793b39683406 100 p++ ; //skip the first byte of the type
andrewboyson 37:793b39683406 101 char recordType = *p++; //read the record type
andrewboyson 37:793b39683406 102 p += 2; //skip the class
andrewboyson 37:793b39683406 103
andrewboyson 47:73af5c0b0dc2 104 LogF(" Query ");
andrewboyson 47:73af5c0b0dc2 105 DnsRecordTypeLog(recordType);
andrewboyson 47:73af5c0b0dc2 106 Log(" type record of ");
andrewboyson 47:73af5c0b0dc2 107 DnsNameLogPtr(iEncodedName);
andrewboyson 47:73af5c0b0dc2 108 Log("\r\n");
andrewboyson 37:793b39683406 109 }
andrewboyson 37:793b39683406 110
andrewboyson 37:793b39683406 111 //Get the answers
andrewboyson 37:793b39683406 112 for (int a = 0; a < DnsHdrAncount; a++)
andrewboyson 37:793b39683406 113 {
andrewboyson 43:bc028d5a6424 114 if (p > DnsHdrData + 500) { Log(" Answers have overrun the buffer\r\n"); return; }
andrewboyson 37:793b39683406 115
andrewboyson 37:793b39683406 116 iEncodedName = DnsNameIndexFromPointer(p);
andrewboyson 37:793b39683406 117 int nameLength = DnsNameLength(p);
andrewboyson 43:bc028d5a6424 118 if (!nameLength) { Log(" Answer name length is zero\r\n"); return; }
andrewboyson 37:793b39683406 119 p += nameLength; //Skip past the name
andrewboyson 37:793b39683406 120
andrewboyson 37:793b39683406 121 p++; //Skip the high byte of the record type
andrewboyson 37:793b39683406 122 int recordType = *p++; //Record type
andrewboyson 37:793b39683406 123
andrewboyson 37:793b39683406 124 p++; //Skip the high byte of the class type
andrewboyson 37:793b39683406 125 int classType = *p++; //Class type
andrewboyson 37:793b39683406 126
andrewboyson 37:793b39683406 127 int ttl = *p++; //32bit TTL
andrewboyson 37:793b39683406 128 ttl <<= 8; ttl += *p++;
andrewboyson 37:793b39683406 129 ttl <<= 8; ttl += *p++;
andrewboyson 37:793b39683406 130 ttl <<= 8; ttl += *p++;
andrewboyson 37:793b39683406 131
andrewboyson 37:793b39683406 132 int len = *p++; //16bit length
andrewboyson 37:793b39683406 133 len <<= 8; len += *p++;
andrewboyson 37:793b39683406 134
andrewboyson 43:bc028d5a6424 135 Log(" Answer ");
andrewboyson 47:73af5c0b0dc2 136 DnsRecordTypeLog(recordType);
andrewboyson 43:bc028d5a6424 137 Log(" type record of ");
andrewboyson 47:73af5c0b0dc2 138 DnsNameLogPtr(iEncodedName);
andrewboyson 43:bc028d5a6424 139 Log(" ==> ");
andrewboyson 37:793b39683406 140
andrewboyson 37:793b39683406 141 switch (recordType) //Log the payload if its type is known
andrewboyson 37:793b39683406 142 {
andrewboyson 37:793b39683406 143 case DNS_RECORD_A:
andrewboyson 43:bc028d5a6424 144 if (len == 4)
andrewboyson 43:bc028d5a6424 145 {
andrewboyson 47:73af5c0b0dc2 146 Ip4AddressLog(*(uint32_t*)p);
andrewboyson 43:bc028d5a6424 147 }
andrewboyson 43:bc028d5a6424 148 else
andrewboyson 43:bc028d5a6424 149 {
andrewboyson 43:bc028d5a6424 150 LogF("expected 4 bytes but had %d", len);
andrewboyson 43:bc028d5a6424 151 }
andrewboyson 37:793b39683406 152 break;
andrewboyson 37:793b39683406 153
andrewboyson 37:793b39683406 154 case DNS_RECORD_AAAA:
andrewboyson 43:bc028d5a6424 155 if (len == 16)
andrewboyson 43:bc028d5a6424 156 {
andrewboyson 47:73af5c0b0dc2 157 Ip6AddressLog(p);
andrewboyson 43:bc028d5a6424 158 }
andrewboyson 43:bc028d5a6424 159 else
andrewboyson 43:bc028d5a6424 160 {
andrewboyson 43:bc028d5a6424 161 LogF("expected 16 bytes but had %d", len);
andrewboyson 43:bc028d5a6424 162 }
andrewboyson 37:793b39683406 163 break;
andrewboyson 37:793b39683406 164
andrewboyson 37:793b39683406 165 case DNS_RECORD_PTR:
andrewboyson 43:bc028d5a6424 166 if (len <= DNS_MAX_LABEL_LENGTH)
andrewboyson 43:bc028d5a6424 167 {
andrewboyson 43:bc028d5a6424 168 iEncodedName = DnsNameIndexFromPointer(p);
andrewboyson 47:73af5c0b0dc2 169 DnsNameLogPtr(iEncodedName);
andrewboyson 43:bc028d5a6424 170 }
andrewboyson 43:bc028d5a6424 171 else
andrewboyson 43:bc028d5a6424 172 {
andrewboyson 43:bc028d5a6424 173 LogF("length %d is greater than max DNS label length of %d\r\n", len, DNS_MAX_LABEL_LENGTH);
andrewboyson 43:bc028d5a6424 174 }
andrewboyson 37:793b39683406 175 break;
andrewboyson 37:793b39683406 176
andrewboyson 37:793b39683406 177 case DNS_RECORD_TXT:
andrewboyson 43:bc028d5a6424 178 case DNS_RECORD_SRV:
andrewboyson 43:bc028d5a6424 179 LogF("'%.*s'", len, p);
andrewboyson 43:bc028d5a6424 180 break;
andrewboyson 43:bc028d5a6424 181
andrewboyson 43:bc028d5a6424 182 default:
andrewboyson 43:bc028d5a6424 183 LogF(" %d characters", len);
andrewboyson 37:793b39683406 184 break;
andrewboyson 37:793b39683406 185 }
andrewboyson 43:bc028d5a6424 186 Log("\r\n");
andrewboyson 37:793b39683406 187 p += len; //Adjust the pointer to the next character after the payload
andrewboyson 37:793b39683406 188
andrewboyson 37:793b39683406 189 }
andrewboyson 37:793b39683406 190 }
andrewboyson 37:793b39683406 191
andrewboyson 37:793b39683406 192 void DnsHdrLog(int protocol)
andrewboyson 13:9cd54f7db57a 193 {
andrewboyson 43:bc028d5a6424 194 if (NetTraceVerbose)
andrewboyson 15:6ca6778168b1 195 {
andrewboyson 47:73af5c0b0dc2 196 DnsProtocolLog(protocol);
andrewboyson 47:73af5c0b0dc2 197 Log(" header\r\n");
andrewboyson 43:bc028d5a6424 198 LogF(" Ident %hd\r\n", DnsHdrId);
andrewboyson 43:bc028d5a6424 199 if (DnsHdrIsReply)
andrewboyson 43:bc028d5a6424 200 {
andrewboyson 43:bc028d5a6424 201 if (DnsHdrIsAuthoritative) LogF(" Authoritative reply\r\n");
andrewboyson 43:bc028d5a6424 202 else LogF(" Non authoritative reply\r\n");
andrewboyson 43:bc028d5a6424 203 }
andrewboyson 43:bc028d5a6424 204 else
andrewboyson 43:bc028d5a6424 205 {
andrewboyson 43:bc028d5a6424 206 if (DnsHdrIsRecursiveQuery) LogF(" Recursive query\r\n");
andrewboyson 43:bc028d5a6424 207 else LogF(" Non recursive query\r\n");
andrewboyson 43:bc028d5a6424 208 }
andrewboyson 43:bc028d5a6424 209 LogF(" qd, an, ns, ar %hu, %hu, %hu, %hu\r\n", DnsHdrQdcount, DnsHdrAncount, DnsHdrNscount, DnsHdrArcount);
andrewboyson 15:6ca6778168b1 210 }
andrewboyson 15:6ca6778168b1 211 else
andrewboyson 15:6ca6778168b1 212 {
andrewboyson 47:73af5c0b0dc2 213 DnsProtocolLog(protocol);
andrewboyson 47:73af5c0b0dc2 214 LogF(" header qd, an, ns, ar %hu, %hu, %hu, %hu\r\n", DnsHdrQdcount, DnsHdrAncount, DnsHdrNscount, DnsHdrArcount);
andrewboyson 15:6ca6778168b1 215 }
andrewboyson 37:793b39683406 216 logContent();
andrewboyson 13:9cd54f7db57a 217 }
andrewboyson 13:9cd54f7db57a 218