NetworkSocketAPI / DnsQuery

Library to resolve text URLs to IP addresses (IPv4)

Dependents:   NetworkSocketAPI NetworkSocketAPI Nucleo-AWS-IoT-mbed

DnsQuery.cpp@3:5705fdae6185, 2015-08-27 (annotated)

Committer:
sarahmarshy
Date:
Thu Aug 27 14:33:07 2015 +0000
Revision:
3:5705fdae6185
Parent:
2:12d08f0f20cf
Child:
4:3749346dcd59
Constructor calls gethostbyname;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sarahmarshy 0:fff4b9055396 1 /* Copyright (c) 2013 Henry Leinen (henry[dot]leinen [at] online [dot] de)
sarahmarshy 0:fff4b9055396 2 *
sarahmarshy 0:fff4b9055396 3 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
sarahmarshy 0:fff4b9055396 4 * and associated documentation files (the "Software"), to deal in the Software without restriction,
sarahmarshy 0:fff4b9055396 5 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
sarahmarshy 0:fff4b9055396 6 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
sarahmarshy 0:fff4b9055396 7 * furnished to do so, subject to the following conditions:
sarahmarshy 0:fff4b9055396 8 *
sarahmarshy 0:fff4b9055396 9 * The above copyright notice and this permission notice shall be included in all copies or
sarahmarshy 0:fff4b9055396 10 * substantial portions of the Software.
sarahmarshy 0:fff4b9055396 11 *
sarahmarshy 0:fff4b9055396 12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
sarahmarshy 0:fff4b9055396 13 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
sarahmarshy 0:fff4b9055396 14 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
sarahmarshy 0:fff4b9055396 15 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
sarahmarshy 0:fff4b9055396 16 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
sarahmarshy 0:fff4b9055396 17 */
sarahmarshy 0:fff4b9055396 18 #include "mbed.h"
sarahmarshy 0:fff4b9055396 19 #include "DnsQuery.h"
sarahmarshy 0:fff4b9055396 20
sarahmarshy 0:fff4b9055396 21 //Debug is disabled by default
sarahmarshy 0:fff4b9055396 22 #if 0
sarahmarshy 0:fff4b9055396 23 #define DBG(x, ...) printf("[DNS : DBG]"x" \t[%s,%d]\r\n", ##__VA_ARGS__,__FILE__,__LINE__);
sarahmarshy 0:fff4b9055396 24 #define WARN(x, ...) printf("[DNS : WARN]"x" \t[%s,%d]\r\n", ##__VA_ARGS__,__FILE__,__LINE__);
sarahmarshy 0:fff4b9055396 25 #define ERR(x, ...) printf("[DNS : ERR]"x" \t[%s,%d]\r\n", ##__VA_ARGS__,__FILE__,__LINE__);
sarahmarshy 0:fff4b9055396 26 #else
sarahmarshy 0:fff4b9055396 27 #define DBG(x, ...) //wait_us(10);
sarahmarshy 0:fff4b9055396 28 #define WARN(x, ...) //wait_us(10);
sarahmarshy 0:fff4b9055396 29 #define ERR(x, ...)
sarahmarshy 0:fff4b9055396 30 #endif
sarahmarshy 0:fff4b9055396 31
sarahmarshy 0:fff4b9055396 32 #if 0
sarahmarshy 0:fff4b9055396 33 #define INFO(x, ...) printf("[DNS : INFO]"x" \t[%s,%d]\r\n", ##__VA_ARGS__,__FILE__,__LINE__);
sarahmarshy 0:fff4b9055396 34 #else
sarahmarshy 0:fff4b9055396 35 #define INFO(x, ...)
sarahmarshy 0:fff4b9055396 36 #endif
sarahmarshy 0:fff4b9055396 37
sarahmarshy 0:fff4b9055396 38
sarahmarshy 0:fff4b9055396 39
sarahmarshy 3:5705fdae6185 40 DnsQuery::DnsQuery(SocketInterface *sock,const char* hostname, char* ipaddress)
sarahmarshy 0:fff4b9055396 41 {
sarahmarshy 1:5d978992a518 42 socket = sock;
sarahmarshy 3:5705fdae6185 43 this->getHostByName(hostname, ipaddress);
sarahmarshy 0:fff4b9055396 44 }
sarahmarshy 0:fff4b9055396 45
sarahmarshy 3:5705fdae6185 46 bool DnsQuery::getHostByName(const char* hostname, char* resolvedIp)
sarahmarshy 0:fff4b9055396 47 {
sarahmarshy 2:12d08f0f20cf 48 char * dnsIPs[] = {
sarahmarshy 2:12d08f0f20cf 49 "8.8.8.8",
sarahmarshy 2:12d08f0f20cf 50 "209.244.0.3",
sarahmarshy 2:12d08f0f20cf 51 "84.200.69.80",
sarahmarshy 2:12d08f0f20cf 52 "8.26.56.26",
sarahmarshy 2:12d08f0f20cf 53 "208.67.222.222"
sarahmarshy 2:12d08f0f20cf 54 };
sarahmarshy 0:fff4b9055396 55 for(int i = 0; i<5; i++){
sarahmarshy 2:12d08f0f20cf 56 _dnsip = dnsIPs[i];
sarahmarshy 2:12d08f0f20cf 57 if(this->getIP(hostname, resolvedIp)){
sarahmarshy 0:fff4b9055396 58 return true;
sarahmarshy 0:fff4b9055396 59 }
sarahmarshy 0:fff4b9055396 60
sarahmarshy 0:fff4b9055396 61 }
sarahmarshy 0:fff4b9055396 62 return false;
sarahmarshy 0:fff4b9055396 63
sarahmarshy 0:fff4b9055396 64 }
sarahmarshy 0:fff4b9055396 65
sarahmarshy 2:12d08f0f20cf 66 bool DnsQuery::getIP(const char* hostname, char* ipaddress)
sarahmarshy 0:fff4b9055396 67 {
sarahmarshy 0:fff4b9055396 68 INFO("%s", hostname);
sarahmarshy 0:fff4b9055396 69 int len = 0;
sarahmarshy 0:fff4b9055396 70 if (hostname == NULL)
sarahmarshy 0:fff4b9055396 71 return false;
sarahmarshy 0:fff4b9055396 72 len = strlen(hostname);
sarahmarshy 0:fff4b9055396 73 if ((len >128) || (len == 0))
sarahmarshy 0:fff4b9055396 74 return false;
sarahmarshy 0:fff4b9055396 75
sarahmarshy 0:fff4b9055396 76 int packetlen = /* size of HEADER structure */ 12 + /* size of QUESTION Structure */5 + len + 1;
sarahmarshy 0:fff4b9055396 77 char *packet = new char[packetlen]; /* this is the UDP packet to send to the DNS */
sarahmarshy 0:fff4b9055396 78 if (packet == NULL)
sarahmarshy 0:fff4b9055396 79 return false;
sarahmarshy 0:fff4b9055396 80
sarahmarshy 0:fff4b9055396 81 // Fill the header
sarahmarshy 0:fff4b9055396 82 memset(packet, 0, packetlen);
sarahmarshy 0:fff4b9055396 83 packet[1] = 1; // ID = 1
sarahmarshy 0:fff4b9055396 84 packet[5] = 1; // QDCOUNT = 1 (contains one question)
sarahmarshy 0:fff4b9055396 85 packet[2] = 1; // recursion requested
sarahmarshy 0:fff4b9055396 86
sarahmarshy 0:fff4b9055396 87 int c = 13; // point to NAME element in question section or request
sarahmarshy 0:fff4b9055396 88 int cnt = 12; // points to the counter of
sarahmarshy 0:fff4b9055396 89 packet[cnt] = 0;
sarahmarshy 0:fff4b9055396 90 for (int i = 0 ; i < len ; i++) {
sarahmarshy 0:fff4b9055396 91 if (hostname[i] != '.') {
sarahmarshy 0:fff4b9055396 92 // Copy the character and increment the character counter
sarahmarshy 0:fff4b9055396 93 packet[cnt]++;
sarahmarshy 0:fff4b9055396 94 packet[c++] = hostname[i];
sarahmarshy 0:fff4b9055396 95 } else {
sarahmarshy 0:fff4b9055396 96 // Finished with this part, so go to the next
sarahmarshy 0:fff4b9055396 97 cnt = c++;
sarahmarshy 0:fff4b9055396 98 packet[cnt] = 0;
sarahmarshy 0:fff4b9055396 99 }
sarahmarshy 0:fff4b9055396 100 }
sarahmarshy 0:fff4b9055396 101
sarahmarshy 0:fff4b9055396 102 // Terminate this domain name with a zero entry
sarahmarshy 0:fff4b9055396 103 packet[c++] = 0;
sarahmarshy 0:fff4b9055396 104
sarahmarshy 0:fff4b9055396 105 // Set QTYPE
sarahmarshy 0:fff4b9055396 106 packet[c++] = 0;
sarahmarshy 0:fff4b9055396 107 packet[c++] = 1;
sarahmarshy 0:fff4b9055396 108 // Set QCLASS
sarahmarshy 0:fff4b9055396 109 packet[c++] = 0;
sarahmarshy 0:fff4b9055396 110 packet[c++] = 1;
sarahmarshy 0:fff4b9055396 111
sarahmarshy 0:fff4b9055396 112
sarahmarshy 0:fff4b9055396 113 // Ready to send to DNS
sarahmarshy 2:12d08f0f20cf 114 socket->setAddressPort(_dnsip, 53);
sarahmarshy 1:5d978992a518 115 socket->open();
sarahmarshy 0:fff4b9055396 116
sarahmarshy 1:5d978992a518 117 INFO("Sending packet of length %d",packetlen);
sarahmarshy 1:5d978992a518 118 /*
sarahmarshy 1:5d978992a518 119 for( int i = 0 ; i < c ; i++) {
sarahmarshy 1:5d978992a518 120 printf("%02x ", packet[i]);
sarahmarshy 1:5d978992a518 121 }
sarahmarshy 1:5d978992a518 122 */
sarahmarshy 1:5d978992a518 123 if (socket->send(packet, packetlen) < 0) {
sarahmarshy 0:fff4b9055396 124 delete packet;
sarahmarshy 0:fff4b9055396 125 return false;
sarahmarshy 0:fff4b9055396 126 }
sarahmarshy 0:fff4b9055396 127 delete packet;
sarahmarshy 0:fff4b9055396 128
sarahmarshy 0:fff4b9055396 129 packet = new char [1024];
sarahmarshy 0:fff4b9055396 130
sarahmarshy 0:fff4b9055396 131 // Receive the answer from DNS
sarahmarshy 0:fff4b9055396 132 int response_length = 0;
sarahmarshy 2:12d08f0f20cf 133 INFO("Recieving");
sarahmarshy 2:12d08f0f20cf 134 response_length = socket->recv(packet, 1024);
sarahmarshy 1:5d978992a518 135 /*
sarahmarshy 1:5d978992a518 136 for( int i = 0 ; i < 1024; i++) {
sarahmarshy 1:5d978992a518 137 printf("%02x ", packet[i]);
sarahmarshy 1:5d978992a518 138 }
sarahmarshy 1:5d978992a518 139 */
sarahmarshy 2:12d08f0f20cf 140 if (response_length > 0 ) {
sarahmarshy 2:12d08f0f20cf 141 if (!resolve(packet, ipaddress)) {
sarahmarshy 2:12d08f0f20cf 142 socket->close();
sarahmarshy 0:fff4b9055396 143 delete packet;
sarahmarshy 2:12d08f0f20cf 144 ERR("NO IP FOUND\n");
sarahmarshy 2:12d08f0f20cf 145 return false;
sarahmarshy 0:fff4b9055396 146 }
sarahmarshy 2:12d08f0f20cf 147
sarahmarshy 2:12d08f0f20cf 148 // cleanup and return
sarahmarshy 2:12d08f0f20cf 149 delete packet;
sarahmarshy 2:12d08f0f20cf 150 socket->close();
sarahmarshy 2:12d08f0f20cf 151 return true;
sarahmarshy 2:12d08f0f20cf 152 } else {
sarahmarshy 2:12d08f0f20cf 153 ERR("SocketRecvFrom returned %d !", response_length);
sarahmarshy 2:12d08f0f20cf 154 }
sarahmarshy 1:5d978992a518 155 socket->close();
sarahmarshy 0:fff4b9055396 156 delete packet;
sarahmarshy 0:fff4b9055396 157 ERR("NO IP FOUND\n");
sarahmarshy 0:fff4b9055396 158 return false;
sarahmarshy 0:fff4b9055396 159 }
sarahmarshy 0:fff4b9055396 160
sarahmarshy 0:fff4b9055396 161
sarahmarshy 2:12d08f0f20cf 162 bool DnsQuery::resolve(char* resp, char* ipaddress)
sarahmarshy 0:fff4b9055396 163 {
sarahmarshy 0:fff4b9055396 164
sarahmarshy 0:fff4b9055396 165 int ID = (((int)resp[0]) <<8) + resp[1];
sarahmarshy 0:fff4b9055396 166 int QR = resp[2] >>7;
sarahmarshy 0:fff4b9055396 167 int Opcode = (resp[2]>>3) & 0x0F;
sarahmarshy 0:fff4b9055396 168 int RCODE = (resp[3] & 0x0F);
sarahmarshy 0:fff4b9055396 169 int ANCOUNT = (((int)resp[6])<<8)+ resp[7];
sarahmarshy 0:fff4b9055396 170
sarahmarshy 0:fff4b9055396 171 INFO("Resolving response : ID = %d, QR = %d, Opcode = %d, RCODE = %d", ID, QR, Opcode, RCODE);
sarahmarshy 0:fff4b9055396 172 if ((ID != 1) || (QR != 1) || (Opcode != 0) || (RCODE != 0)) {
sarahmarshy 0:fff4b9055396 173 ERR("Received non matching response from DNS !");
sarahmarshy 0:fff4b9055396 174 return false;
sarahmarshy 0:fff4b9055396 175 }
sarahmarshy 0:fff4b9055396 176
sarahmarshy 0:fff4b9055396 177 int c = 12;
sarahmarshy 0:fff4b9055396 178 int d;
sarahmarshy 0:fff4b9055396 179 // Skip domain question
sarahmarshy 0:fff4b9055396 180 while( (d=resp[c++]) != 0) {
sarahmarshy 0:fff4b9055396 181 c+=d;
sarahmarshy 0:fff4b9055396 182 }
sarahmarshy 0:fff4b9055396 183 c+= 4; // skip QTYPE and QCLASS
sarahmarshy 0:fff4b9055396 184
sarahmarshy 0:fff4b9055396 185 // Here comes the resource record
sarahmarshy 0:fff4b9055396 186 for (int ans = 0 ; ans < ANCOUNT; ans++) {
sarahmarshy 0:fff4b9055396 187 if (parseRR(resp, c, ipaddress)) {
sarahmarshy 0:fff4b9055396 188 return true;
sarahmarshy 0:fff4b9055396 189 }
sarahmarshy 0:fff4b9055396 190 }
sarahmarshy 0:fff4b9055396 191
sarahmarshy 0:fff4b9055396 192 return false;
sarahmarshy 0:fff4b9055396 193 }
sarahmarshy 0:fff4b9055396 194
sarahmarshy 2:12d08f0f20cf 195 bool DnsQuery::parseRR(char *resp, int& c, char* adr )
sarahmarshy 0:fff4b9055396 196 {
sarahmarshy 0:fff4b9055396 197 int n = 0;
sarahmarshy 0:fff4b9055396 198 while( (n=resp[c++]) != 0) {
sarahmarshy 0:fff4b9055396 199 if ((n & 0xc0) != 0) {
sarahmarshy 0:fff4b9055396 200 // This is a link
sarahmarshy 0:fff4b9055396 201 c++;
sarahmarshy 0:fff4b9055396 202 break;
sarahmarshy 0:fff4b9055396 203 } else {
sarahmarshy 0:fff4b9055396 204 c+= n; // skip this segment, not interested in string domain names
sarahmarshy 0:fff4b9055396 205 }
sarahmarshy 0:fff4b9055396 206 }
sarahmarshy 0:fff4b9055396 207
sarahmarshy 0:fff4b9055396 208 int TYPE = (((int)resp[c])<<8) + resp[c+1];
sarahmarshy 0:fff4b9055396 209 int CLASS = (((int)resp[c+2])<<8) + resp[c+3];
sarahmarshy 0:fff4b9055396 210 int RDLENGTH = (((int)resp[c+8])<<8) + resp[c+9];
sarahmarshy 0:fff4b9055396 211
sarahmarshy 0:fff4b9055396 212 INFO("Record of TYPE=%d and CLASS=%d detected !", TYPE, CLASS);
sarahmarshy 0:fff4b9055396 213 c+= 10;
sarahmarshy 0:fff4b9055396 214 if ((CLASS == 1) && (TYPE == 1)) {
sarahmarshy 2:12d08f0f20cf 215 sprintf(adr,"%d.%d.%d.%d", resp[c], resp[c+1], resp[c+2], resp[c+3]);
sarahmarshy 0:fff4b9055396 216 c+= RDLENGTH;
sarahmarshy 0:fff4b9055396 217 return true;
sarahmarshy 0:fff4b9055396 218 } else {
sarahmarshy 0:fff4b9055396 219 }
sarahmarshy 0:fff4b9055396 220 c+= RDLENGTH;
sarahmarshy 0:fff4b9055396 221
sarahmarshy 0:fff4b9055396 222 return false;
sarahmarshy 0:fff4b9055396 223 }