Andrew Boyson / net

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependents:   oldheating gps motorhome heating

udp/dns/dnsserver.c@61:aad055f1b0d1, 2018-01-11 (annotated)

Committer:
andrewboyson
Date:
Thu Jan 11 17:38:21 2018 +0000
Revision:
61:aad055f1b0d1
Parent:
udp/dns/dnsserver.cpp@59:e0e556c8bd46
Child:
128:79052cb4a41c
Removed dependence on Mbed OS

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 61:aad055f1b0d1 1 #include <stdbool.h>
andrewboyson 61:aad055f1b0d1 2 #include <string.h>
andrewboyson 61:aad055f1b0d1 3
andrewboyson 13:9cd54f7db57a 4 #include "dnshdr.h"
andrewboyson 13:9cd54f7db57a 5 #include "dnsname.h"
andrewboyson 13:9cd54f7db57a 6 #include "net.h"
andrewboyson 37:793b39683406 7 #include "action.h"
andrewboyson 13:9cd54f7db57a 8 #include "dns.h"
andrewboyson 13:9cd54f7db57a 9 #include "log.h"
andrewboyson 13:9cd54f7db57a 10 #include "dhcp.h"
andrewboyson 13:9cd54f7db57a 11 #include "slaac.h"
andrewboyson 37:793b39683406 12 #include "ip4.h"
andrewboyson 37:793b39683406 13 #include "ip6.h"
andrewboyson 13:9cd54f7db57a 14
andrewboyson 37:793b39683406 15 bool DnsServerTrace = false;
andrewboyson 37:793b39683406 16
andrewboyson 44:83ce5ace337b 17 #define RECORD_NONE 0
andrewboyson 44:83ce5ace337b 18 #define RECORD_PTR4 1
andrewboyson 44:83ce5ace337b 19 #define RECORD_PTR6_LOCAL 2
andrewboyson 44:83ce5ace337b 20 #define RECORD_PTR6_GLOBAL 3
andrewboyson 44:83ce5ace337b 21 #define RECORD_A 4
andrewboyson 44:83ce5ace337b 22 #define RECORD_AAAA_LOCAL 5
andrewboyson 44:83ce5ace337b 23 #define RECORD_AAAA_GLOBAL 6
andrewboyson 44:83ce5ace337b 24
andrewboyson 44:83ce5ace337b 25 #define MAX_ANSWERS 4
andrewboyson 13:9cd54f7db57a 26
andrewboyson 32:679654f2d023 27 //Set by 'initialise'
andrewboyson 36:900e24b27bfb 28 static char* p; //Position relative to DnsHdrData and is updated while both reading questions and writing answers
andrewboyson 44:83ce5ace337b 29 static char myFullName4[100]; //The name, adjusted to include the domain if needed by the protocol, used when reading and when writing
andrewboyson 44:83ce5ace337b 30 static int myFullName4Length;
andrewboyson 44:83ce5ace337b 31 static char myFullName6[100]; //The name, adjusted to include the domain if needed by the protocol, used when reading and when writing
andrewboyson 44:83ce5ace337b 32 static int myFullName6Length;
andrewboyson 32:679654f2d023 33
andrewboyson 32:679654f2d023 34 //Set by readQuestions and used by answerQuestions
andrewboyson 44:83ce5ace337b 35 static int answers[MAX_ANSWERS];
andrewboyson 44:83ce5ace337b 36 static int answerCount = 0;
andrewboyson 36:900e24b27bfb 37 static bool mdnsUnicastReply;
andrewboyson 32:679654f2d023 38
andrewboyson 32:679654f2d023 39 static int readQuestions()
andrewboyson 32:679654f2d023 40 {
andrewboyson 37:793b39683406 41 p = DnsHdrData;
andrewboyson 32:679654f2d023 42 mdnsUnicastReply = false;
andrewboyson 13:9cd54f7db57a 43
andrewboyson 13:9cd54f7db57a 44 //Get the questions
andrewboyson 44:83ce5ace337b 45 answerCount = 0;
andrewboyson 44:83ce5ace337b 46 for (int i = 0; i < DnsHdrQdcount; i++)
andrewboyson 13:9cd54f7db57a 47 {
andrewboyson 44:83ce5ace337b 48 //Bomb out if there are too many answers
andrewboyson 44:83ce5ace337b 49 if (answerCount >= MAX_ANSWERS)
andrewboyson 37:793b39683406 50 {
andrewboyson 44:83ce5ace337b 51 if (DnsServerTrace) LogTimeF("DnsServer-readQuestions - exceeded %d answers\r\n", MAX_ANSWERS);
andrewboyson 37:793b39683406 52 break;
andrewboyson 37:793b39683406 53 }
andrewboyson 37:793b39683406 54
andrewboyson 37:793b39683406 55 //Bomb out if we are tending to overrun the buffer
andrewboyson 61:aad055f1b0d1 56 if (p - DnsHdrData > DnsHdrDataLength)
andrewboyson 37:793b39683406 57 {
andrewboyson 61:aad055f1b0d1 58 if (DnsServerTrace) LogTimeF("DnsServer-readQuestions - overrunning the buffer of %d bytes\r\n", DnsHdrDataLength);
andrewboyson 37:793b39683406 59 return -1;
andrewboyson 37:793b39683406 60 }
andrewboyson 37:793b39683406 61
andrewboyson 37:793b39683406 62 //Node name
andrewboyson 13:9cd54f7db57a 63 int nameLength = DnsNameLength(p);
andrewboyson 37:793b39683406 64 if (!nameLength)
andrewboyson 37:793b39683406 65 {
andrewboyson 37:793b39683406 66 if (DnsServerTrace) LogTimeF("DnsServer-readQuestions namelength is zero\r\n");
andrewboyson 37:793b39683406 67 return -1;
andrewboyson 37:793b39683406 68 }
andrewboyson 44:83ce5ace337b 69 bool nodeIsName4 = DnsNameComparePtr(p, myFullName4);
andrewboyson 44:83ce5ace337b 70 bool nodeIsName6 = DnsNameComparePtr(p, myFullName6);
andrewboyson 44:83ce5ace337b 71 bool nodeIsAddr4 = DnsNameCompareIp4(p, DhcpLocalIp);
andrewboyson 44:83ce5ace337b 72 bool nodeIsLocl6 = DnsNameCompareIp6(p, SlaacLinkLocalIp);
andrewboyson 44:83ce5ace337b 73 bool nodeIsGlob6 = DnsNameCompareIp6(p, SlaacGlobalIp);
andrewboyson 44:83ce5ace337b 74 p += nameLength; //Skip past the name
andrewboyson 44:83ce5ace337b 75
andrewboyson 37:793b39683406 76 //Type
andrewboyson 44:83ce5ace337b 77 p++ ; //skip the first byte of the type
andrewboyson 44:83ce5ace337b 78 char recordType = *p++; //read the record type
andrewboyson 37:793b39683406 79
andrewboyson 37:793b39683406 80 //Class
andrewboyson 44:83ce5ace337b 81 if (*p++ & 0x80) mdnsUnicastReply = true; //check the class 15th bit (UNICAST-RESPONSE)
andrewboyson 44:83ce5ace337b 82 p++; //skip the class
andrewboyson 44:83ce5ace337b 83
andrewboyson 44:83ce5ace337b 84 //Handle the questions
andrewboyson 44:83ce5ace337b 85 if (nodeIsName4 && recordType == DNS_RECORD_A ) answers[answerCount++] = RECORD_A;
andrewboyson 44:83ce5ace337b 86 if (nodeIsName6 && recordType == DNS_RECORD_AAAA) { answers[answerCount++] = RECORD_AAAA_LOCAL; answers[answerCount++] = RECORD_AAAA_GLOBAL; }
andrewboyson 44:83ce5ace337b 87 if (nodeIsAddr4 && recordType == DNS_RECORD_PTR ) answers[answerCount++] = RECORD_PTR4;
andrewboyson 44:83ce5ace337b 88 if (nodeIsLocl6 && recordType == DNS_RECORD_PTR ) answers[answerCount++] = RECORD_PTR6_LOCAL;
andrewboyson 44:83ce5ace337b 89 if (nodeIsGlob6 && recordType == DNS_RECORD_PTR ) answers[answerCount++] = RECORD_PTR6_GLOBAL;
andrewboyson 13:9cd54f7db57a 90 }
andrewboyson 32:679654f2d023 91 return 0;
andrewboyson 32:679654f2d023 92 }
andrewboyson 32:679654f2d023 93 static int addAnswers(int dnsProtocol)
andrewboyson 59:e0e556c8bd46 94 {
andrewboyson 44:83ce5ace337b 95 //Go through each answer
andrewboyson 33:714a0345e59b 96 DnsHdrAncount = 0;
andrewboyson 44:83ce5ace337b 97 for (int i = 0; i < answerCount; i++)
andrewboyson 44:83ce5ace337b 98 {
andrewboyson 37:793b39683406 99 //Bomb out if we are tending to overrun the buffer
andrewboyson 61:aad055f1b0d1 100 if (p - DnsHdrData > DnsHdrDataLength)
andrewboyson 32:679654f2d023 101 {
andrewboyson 37:793b39683406 102 if (DnsServerTrace) LogTimeF("DnsServer-addAnswers - reply is getting too big\r\n");
andrewboyson 32:679654f2d023 103 return -1;
andrewboyson 32:679654f2d023 104 }
andrewboyson 43:bc028d5a6424 105
andrewboyson 37:793b39683406 106 //Encode the node name
andrewboyson 44:83ce5ace337b 107 switch (answers[i])
andrewboyson 32:679654f2d023 108 {
andrewboyson 44:83ce5ace337b 109 case RECORD_A: DnsNameEncodePtr(myFullName4, &p); break;
andrewboyson 44:83ce5ace337b 110 case RECORD_AAAA_LOCAL: DnsNameEncodePtr(myFullName6, &p); break;
andrewboyson 44:83ce5ace337b 111 case RECORD_AAAA_GLOBAL: DnsNameEncodePtr(myFullName6, &p); break;
andrewboyson 44:83ce5ace337b 112 case RECORD_PTR4: DnsNameEncodeIp4(DhcpLocalIp, &p); break;
andrewboyson 44:83ce5ace337b 113 case RECORD_PTR6_LOCAL: DnsNameEncodeIp6(SlaacLinkLocalIp, &p); break;
andrewboyson 44:83ce5ace337b 114 case RECORD_PTR6_GLOBAL: DnsNameEncodeIp6(SlaacGlobalIp, &p); break;
andrewboyson 13:9cd54f7db57a 115 }
andrewboyson 37:793b39683406 116
andrewboyson 44:83ce5ace337b 117 //Add the 16 bit type
andrewboyson 44:83ce5ace337b 118 *p++ = 0;
andrewboyson 44:83ce5ace337b 119 switch (answers[i])
andrewboyson 44:83ce5ace337b 120 {
andrewboyson 44:83ce5ace337b 121 case RECORD_A: *p++ = DNS_RECORD_A; break;
andrewboyson 44:83ce5ace337b 122 case RECORD_AAAA_LOCAL: *p++ = DNS_RECORD_AAAA; break;
andrewboyson 44:83ce5ace337b 123 case RECORD_AAAA_GLOBAL: *p++ = DNS_RECORD_AAAA; break;
andrewboyson 44:83ce5ace337b 124 case RECORD_PTR4: *p++ = DNS_RECORD_PTR; break;
andrewboyson 44:83ce5ace337b 125 case RECORD_PTR6_LOCAL: *p++ = DNS_RECORD_PTR; break;
andrewboyson 44:83ce5ace337b 126 case RECORD_PTR6_GLOBAL: *p++ = DNS_RECORD_PTR; break;
andrewboyson 44:83ce5ace337b 127 }
andrewboyson 37:793b39683406 128
andrewboyson 37:793b39683406 129 //Add the class
andrewboyson 37:793b39683406 130 char mdns = dnsProtocol == DNS_PROTOCOL_MDNS ? 0x80 : 0; //Set the 15th bit (CACHE_FLUSH) of the class to 1 if MDNS
andrewboyson 32:679654f2d023 131 *p++ = mdns; *p++ = 1; //16 bit Class LSB QCLASS_IN = 1 - internet
andrewboyson 37:793b39683406 132
andrewboyson 37:793b39683406 133 //Add the TTL
andrewboyson 32:679654f2d023 134 *p++ = 0; *p++ = 0; *p++ = 4; *p++ = 0; //32 bit TTL seconds - 1024
andrewboyson 37:793b39683406 135
andrewboyson 37:793b39683406 136
andrewboyson 37:793b39683406 137 //Add the 16 bit payload length
andrewboyson 44:83ce5ace337b 138 *p++ = 0;
andrewboyson 44:83ce5ace337b 139 switch (answers[i])
andrewboyson 37:793b39683406 140 {
andrewboyson 44:83ce5ace337b 141 case RECORD_A: *p++ = 4; break;
andrewboyson 44:83ce5ace337b 142 case RECORD_AAAA_LOCAL: *p++ = 16; break;
andrewboyson 44:83ce5ace337b 143 case RECORD_AAAA_GLOBAL: *p++ = 16; break;
andrewboyson 44:83ce5ace337b 144 case RECORD_PTR4: *p++ = myFullName4Length + 2; break; //add a byte for the initial length and another for the terminating zero length
andrewboyson 44:83ce5ace337b 145 case RECORD_PTR6_LOCAL: *p++ = myFullName6Length + 2; break;
andrewboyson 44:83ce5ace337b 146 case RECORD_PTR6_GLOBAL: *p++ = myFullName6Length + 2; break;
andrewboyson 37:793b39683406 147 }
andrewboyson 37:793b39683406 148
andrewboyson 37:793b39683406 149 //Add the payload
andrewboyson 44:83ce5ace337b 150 switch (answers[i])
andrewboyson 37:793b39683406 151 {
andrewboyson 44:83ce5ace337b 152 case RECORD_A: memcpy(p, &DhcpLocalIp, 4); p += 4; break;
andrewboyson 44:83ce5ace337b 153 case RECORD_AAAA_LOCAL: memcpy(p, SlaacLinkLocalIp, 16); p += 16; break;
andrewboyson 44:83ce5ace337b 154 case RECORD_AAAA_GLOBAL: memcpy(p, SlaacGlobalIp, 16); p += 16; break;
andrewboyson 44:83ce5ace337b 155 case RECORD_PTR4: DnsNameEncodePtr(myFullName4, &p); break;
andrewboyson 44:83ce5ace337b 156 case RECORD_PTR6_LOCAL: DnsNameEncodePtr(myFullName6, &p); break;
andrewboyson 44:83ce5ace337b 157 case RECORD_PTR6_GLOBAL: DnsNameEncodePtr(myFullName6, &p); break;
andrewboyson 37:793b39683406 158 }
andrewboyson 44:83ce5ace337b 159 //Increment the number of good answers to send
andrewboyson 44:83ce5ace337b 160 DnsHdrAncount++;
andrewboyson 13:9cd54f7db57a 161 }
andrewboyson 32:679654f2d023 162 return 0;
andrewboyson 32:679654f2d023 163 }
andrewboyson 32:679654f2d023 164
andrewboyson 59:e0e556c8bd46 165 int DnsServerHandleQuery(void (*traceback)(void), int dnsProtocol, void* pPacketTx, int *pSizeTx) //Received an mdns or llmnr query on port 5353 or 5355
andrewboyson 59:e0e556c8bd46 166 {
andrewboyson 44:83ce5ace337b 167 myFullName4Length = DnsMakeFullNameFromName(dnsProtocol, NetName4, sizeof(myFullName4), myFullName4);
andrewboyson 44:83ce5ace337b 168 myFullName6Length = DnsMakeFullNameFromName(dnsProtocol, NetName6, sizeof(myFullName6), myFullName6);
andrewboyson 32:679654f2d023 169
andrewboyson 37:793b39683406 170 if (readQuestions()) return DO_NOTHING;
andrewboyson 44:83ce5ace337b 171 if (!answerCount) return DO_NOTHING;
andrewboyson 37:793b39683406 172
andrewboyson 57:e0fb648acf48 173 if (DnsServerTrace || NetTraceHostGetMatched())
andrewboyson 37:793b39683406 174 {
andrewboyson 43:bc028d5a6424 175 if (NetTraceNewLine) Log("\r\n");
andrewboyson 37:793b39683406 176 LogTimeF("DnsServer received query\r\n");
andrewboyson 43:bc028d5a6424 177 if (NetTraceStack) traceback();
andrewboyson 37:793b39683406 178 DnsHdrLog(dnsProtocol);
andrewboyson 37:793b39683406 179 }
andrewboyson 37:793b39683406 180
andrewboyson 59:e0e556c8bd46 181 char* pRx = DnsHdrData;
andrewboyson 59:e0e556c8bd46 182 char* pEndRx = p;
andrewboyson 59:e0e556c8bd46 183 int qdcount = DnsHdrQdcount;
andrewboyson 59:e0e556c8bd46 184 int nscount = DnsHdrNscount;
andrewboyson 59:e0e556c8bd46 185 int arcount = DnsHdrArcount;
andrewboyson 59:e0e556c8bd46 186
andrewboyson 59:e0e556c8bd46 187 DnsHdrSetup(pPacketTx, *pSizeTx);
andrewboyson 59:e0e556c8bd46 188 p = DnsHdrData;
andrewboyson 59:e0e556c8bd46 189
andrewboyson 59:e0e556c8bd46 190 //Add the questions if this is not MDNS
andrewboyson 59:e0e556c8bd46 191 if (dnsProtocol == DNS_PROTOCOL_MDNS)
andrewboyson 59:e0e556c8bd46 192 {
andrewboyson 59:e0e556c8bd46 193 DnsHdrQdcount = 0;
andrewboyson 59:e0e556c8bd46 194 DnsHdrNscount = 0;
andrewboyson 59:e0e556c8bd46 195 DnsHdrArcount = 0;
andrewboyson 59:e0e556c8bd46 196 }
andrewboyson 59:e0e556c8bd46 197 else
andrewboyson 59:e0e556c8bd46 198 {
andrewboyson 59:e0e556c8bd46 199 DnsHdrQdcount = qdcount;
andrewboyson 59:e0e556c8bd46 200 DnsHdrNscount = nscount;
andrewboyson 59:e0e556c8bd46 201 DnsHdrArcount = arcount;
andrewboyson 59:e0e556c8bd46 202 while (pRx < pEndRx) *p++ = *pRx++;
andrewboyson 59:e0e556c8bd46 203 }
andrewboyson 59:e0e556c8bd46 204
andrewboyson 59:e0e556c8bd46 205
andrewboyson 37:793b39683406 206 if (addAnswers(dnsProtocol)) return DO_NOTHING;
andrewboyson 13:9cd54f7db57a 207
andrewboyson 59:e0e556c8bd46 208 DnsHdrIsReply = true;
andrewboyson 59:e0e556c8bd46 209 DnsHdrIsAuthoritative = false;
andrewboyson 59:e0e556c8bd46 210 DnsHdrIsRecursiveQuery = false;
andrewboyson 59:e0e556c8bd46 211
andrewboyson 13:9cd54f7db57a 212 DnsHdrWrite();
andrewboyson 13:9cd54f7db57a 213
andrewboyson 59:e0e556c8bd46 214 *pSizeTx = p - DnsHdrPacket;
andrewboyson 13:9cd54f7db57a 215
andrewboyson 57:e0fb648acf48 216 if (DnsServerTrace || NetTraceHostGetMatched()) DnsHdrLog(dnsProtocol);
andrewboyson 13:9cd54f7db57a 217
andrewboyson 37:793b39683406 218 int dest;
andrewboyson 37:793b39683406 219 if (dnsProtocol == DNS_PROTOCOL_MDNS && !mdnsUnicastReply) dest = MULTICAST_MDNS;
andrewboyson 37:793b39683406 220 else dest = UNICAST;
andrewboyson 37:793b39683406 221
andrewboyson 57:e0fb648acf48 222 return ActionMakeFromDestAndTrace(dest, NetTraceStack && DnsServerTrace || NetTraceHostGetMatched());
andrewboyson 13:9cd54f7db57a 223 }