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mbed-os

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features/netsocket/nsapi_dns.cpp@0:b74591d5ab33, 2017-12-11 (annotated)

Committer:
be_bryan
Date:
Mon Dec 11 17:54:04 2017 +0000
Revision:
0:b74591d5ab33
motor ++

Who changed what in which revision?

UserRevisionLine numberNew contents of line
be_bryan 0:b74591d5ab33 1 /* nsapi_dns.cpp
be_bryan 0:b74591d5ab33 2 * Original work Copyright (c) 2013 Henry Leinen (henry[dot]leinen [at] online [dot] de)
be_bryan 0:b74591d5ab33 3 * Modified work Copyright (c) 2015 ARM Limited
be_bryan 0:b74591d5ab33 4 *
be_bryan 0:b74591d5ab33 5 * Licensed under the Apache License, Version 2.0 (the "License");
be_bryan 0:b74591d5ab33 6 * you may not use this file except in compliance with the License.
be_bryan 0:b74591d5ab33 7 * You may obtain a copy of the License at
be_bryan 0:b74591d5ab33 8 *
be_bryan 0:b74591d5ab33 9 * http://www.apache.org/licenses/LICENSE-2.0
be_bryan 0:b74591d5ab33 10 *
be_bryan 0:b74591d5ab33 11 * Unless required by applicable law or agreed to in writing, software
be_bryan 0:b74591d5ab33 12 * distributed under the License is distributed on an "AS IS" BASIS,
be_bryan 0:b74591d5ab33 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
be_bryan 0:b74591d5ab33 14 * See the License for the specific language governing permissions and
be_bryan 0:b74591d5ab33 15 * limitations under the License.
be_bryan 0:b74591d5ab33 16 */
be_bryan 0:b74591d5ab33 17 #include "nsapi_dns.h"
be_bryan 0:b74591d5ab33 18 #include "netsocket/UDPSocket.h"
be_bryan 0:b74591d5ab33 19 #include <string.h>
be_bryan 0:b74591d5ab33 20 #include <stdlib.h>
be_bryan 0:b74591d5ab33 21 #include <stdio.h>
be_bryan 0:b74591d5ab33 22
be_bryan 0:b74591d5ab33 23 #define CLASS_IN 1
be_bryan 0:b74591d5ab33 24
be_bryan 0:b74591d5ab33 25 #define RR_A 1
be_bryan 0:b74591d5ab33 26 #define RR_AAAA 28
be_bryan 0:b74591d5ab33 27
be_bryan 0:b74591d5ab33 28 // DNS options
be_bryan 0:b74591d5ab33 29 #define DNS_BUFFER_SIZE 512
be_bryan 0:b74591d5ab33 30 #define DNS_TIMEOUT 5000
be_bryan 0:b74591d5ab33 31 #define DNS_SERVERS_SIZE 5
be_bryan 0:b74591d5ab33 32
be_bryan 0:b74591d5ab33 33 nsapi_addr_t dns_servers[DNS_SERVERS_SIZE] = {
be_bryan 0:b74591d5ab33 34 {NSAPI_IPv4, {8, 8, 8, 8}}, // Google
be_bryan 0:b74591d5ab33 35 {NSAPI_IPv4, {209, 244, 0, 3}}, // Level 3
be_bryan 0:b74591d5ab33 36 {NSAPI_IPv4, {84, 200, 69, 80}}, // DNS.WATCH
be_bryan 0:b74591d5ab33 37 {NSAPI_IPv6, {0x20,0x01, 0x48,0x60, 0x48,0x60, 0,0, // Google
be_bryan 0:b74591d5ab33 38 0,0, 0,0, 0,0, 0x88,0x88}},
be_bryan 0:b74591d5ab33 39 {NSAPI_IPv6, {0x20,0x01, 0x16,0x08, 0,0x10, 0,0x25, // DNS.WATCH
be_bryan 0:b74591d5ab33 40 0,0, 0,0, 0x1c,0x04, 0xb1,0x2f}},
be_bryan 0:b74591d5ab33 41 };
be_bryan 0:b74591d5ab33 42
be_bryan 0:b74591d5ab33 43 // DNS server configuration
be_bryan 0:b74591d5ab33 44 extern "C" nsapi_error_t nsapi_dns_add_server(nsapi_addr_t addr)
be_bryan 0:b74591d5ab33 45 {
be_bryan 0:b74591d5ab33 46 memmove(&dns_servers[1], &dns_servers[0],
be_bryan 0:b74591d5ab33 47 (DNS_SERVERS_SIZE-1)*sizeof(nsapi_addr_t));
be_bryan 0:b74591d5ab33 48
be_bryan 0:b74591d5ab33 49 dns_servers[0] = addr;
be_bryan 0:b74591d5ab33 50 return NSAPI_ERROR_OK;
be_bryan 0:b74591d5ab33 51 }
be_bryan 0:b74591d5ab33 52
be_bryan 0:b74591d5ab33 53
be_bryan 0:b74591d5ab33 54 // DNS packet parsing
be_bryan 0:b74591d5ab33 55 static void dns_append_byte(uint8_t **p, uint8_t byte)
be_bryan 0:b74591d5ab33 56 {
be_bryan 0:b74591d5ab33 57 *(*p)++ = byte;
be_bryan 0:b74591d5ab33 58 }
be_bryan 0:b74591d5ab33 59
be_bryan 0:b74591d5ab33 60 static void dns_append_word(uint8_t **p, uint16_t word)
be_bryan 0:b74591d5ab33 61 {
be_bryan 0:b74591d5ab33 62
be_bryan 0:b74591d5ab33 63 dns_append_byte(p, 0xff & (word >> 8));
be_bryan 0:b74591d5ab33 64 dns_append_byte(p, 0xff & (word >> 0));
be_bryan 0:b74591d5ab33 65 }
be_bryan 0:b74591d5ab33 66
be_bryan 0:b74591d5ab33 67 static void dns_append_name(uint8_t **p, const char *name, uint8_t len)
be_bryan 0:b74591d5ab33 68 {
be_bryan 0:b74591d5ab33 69 dns_append_byte(p, len);
be_bryan 0:b74591d5ab33 70 memcpy(*p, name, len);
be_bryan 0:b74591d5ab33 71 *p += len;
be_bryan 0:b74591d5ab33 72 }
be_bryan 0:b74591d5ab33 73
be_bryan 0:b74591d5ab33 74 static uint8_t dns_scan_byte(const uint8_t **p)
be_bryan 0:b74591d5ab33 75 {
be_bryan 0:b74591d5ab33 76 return *(*p)++;
be_bryan 0:b74591d5ab33 77 }
be_bryan 0:b74591d5ab33 78
be_bryan 0:b74591d5ab33 79 static uint16_t dns_scan_word(const uint8_t **p)
be_bryan 0:b74591d5ab33 80 {
be_bryan 0:b74591d5ab33 81 uint16_t a = dns_scan_byte(p);
be_bryan 0:b74591d5ab33 82 uint16_t b = dns_scan_byte(p);
be_bryan 0:b74591d5ab33 83 return (a << 8) | b;
be_bryan 0:b74591d5ab33 84 }
be_bryan 0:b74591d5ab33 85
be_bryan 0:b74591d5ab33 86
be_bryan 0:b74591d5ab33 87 static void dns_append_question(uint8_t **p, const char *host, nsapi_version_t version)
be_bryan 0:b74591d5ab33 88 {
be_bryan 0:b74591d5ab33 89 // fill the header
be_bryan 0:b74591d5ab33 90 dns_append_word(p, 1); // id = 1
be_bryan 0:b74591d5ab33 91 dns_append_word(p, 0x0100); // flags = recursion required
be_bryan 0:b74591d5ab33 92 dns_append_word(p, 1); // qdcount = 1
be_bryan 0:b74591d5ab33 93 dns_append_word(p, 0); // ancount = 0
be_bryan 0:b74591d5ab33 94 dns_append_word(p, 0); // nscount = 0
be_bryan 0:b74591d5ab33 95 dns_append_word(p, 0); // arcount = 0
be_bryan 0:b74591d5ab33 96
be_bryan 0:b74591d5ab33 97 // fill out the question names
be_bryan 0:b74591d5ab33 98 while (host[0]) {
be_bryan 0:b74591d5ab33 99 size_t label_len = strcspn(host, ".");
be_bryan 0:b74591d5ab33 100 dns_append_name(p, host, label_len);
be_bryan 0:b74591d5ab33 101 host += label_len + (host[label_len] == '.');
be_bryan 0:b74591d5ab33 102 }
be_bryan 0:b74591d5ab33 103
be_bryan 0:b74591d5ab33 104 dns_append_byte(p, 0);
be_bryan 0:b74591d5ab33 105
be_bryan 0:b74591d5ab33 106 // fill out question footer
be_bryan 0:b74591d5ab33 107 if (version != NSAPI_IPv6) {
be_bryan 0:b74591d5ab33 108 dns_append_word(p, RR_A); // qtype = ipv4
be_bryan 0:b74591d5ab33 109 } else {
be_bryan 0:b74591d5ab33 110 dns_append_word(p, RR_AAAA); // qtype = ipv6
be_bryan 0:b74591d5ab33 111 }
be_bryan 0:b74591d5ab33 112 dns_append_word(p, CLASS_IN);
be_bryan 0:b74591d5ab33 113 }
be_bryan 0:b74591d5ab33 114
be_bryan 0:b74591d5ab33 115 static int dns_scan_response(const uint8_t **p, nsapi_addr_t *addr, unsigned addr_count)
be_bryan 0:b74591d5ab33 116 {
be_bryan 0:b74591d5ab33 117 // scan header
be_bryan 0:b74591d5ab33 118 uint16_t id = dns_scan_word(p);
be_bryan 0:b74591d5ab33 119 uint16_t flags = dns_scan_word(p);
be_bryan 0:b74591d5ab33 120 bool qr = 0x1 & (flags >> 15);
be_bryan 0:b74591d5ab33 121 uint8_t opcode = 0xf & (flags >> 11);
be_bryan 0:b74591d5ab33 122 uint8_t rcode = 0xf & (flags >> 0);
be_bryan 0:b74591d5ab33 123
be_bryan 0:b74591d5ab33 124 uint16_t qdcount = dns_scan_word(p); // qdcount
be_bryan 0:b74591d5ab33 125 uint16_t ancount = dns_scan_word(p); // ancount
be_bryan 0:b74591d5ab33 126 dns_scan_word(p); // nscount
be_bryan 0:b74591d5ab33 127 dns_scan_word(p); // arcount
be_bryan 0:b74591d5ab33 128
be_bryan 0:b74591d5ab33 129 // verify header is response to query
be_bryan 0:b74591d5ab33 130 if (!(id == 1 && qr && opcode == 0 && rcode == 0)) {
be_bryan 0:b74591d5ab33 131 return 0;
be_bryan 0:b74591d5ab33 132 }
be_bryan 0:b74591d5ab33 133
be_bryan 0:b74591d5ab33 134 // skip questions
be_bryan 0:b74591d5ab33 135 for (int i = 0; i < qdcount; i++) {
be_bryan 0:b74591d5ab33 136 while (true) {
be_bryan 0:b74591d5ab33 137 uint8_t len = dns_scan_byte(p);
be_bryan 0:b74591d5ab33 138 if (len == 0) {
be_bryan 0:b74591d5ab33 139 break;
be_bryan 0:b74591d5ab33 140 }
be_bryan 0:b74591d5ab33 141
be_bryan 0:b74591d5ab33 142 *p += len;
be_bryan 0:b74591d5ab33 143 }
be_bryan 0:b74591d5ab33 144
be_bryan 0:b74591d5ab33 145 dns_scan_word(p); // qtype
be_bryan 0:b74591d5ab33 146 dns_scan_word(p); // qclass
be_bryan 0:b74591d5ab33 147 }
be_bryan 0:b74591d5ab33 148
be_bryan 0:b74591d5ab33 149 // scan each response
be_bryan 0:b74591d5ab33 150 unsigned count = 0;
be_bryan 0:b74591d5ab33 151
be_bryan 0:b74591d5ab33 152 for (int i = 0; i < ancount && count < addr_count; i++) {
be_bryan 0:b74591d5ab33 153 while (true) {
be_bryan 0:b74591d5ab33 154 uint8_t len = dns_scan_byte(p);
be_bryan 0:b74591d5ab33 155 if (len == 0) {
be_bryan 0:b74591d5ab33 156 break;
be_bryan 0:b74591d5ab33 157 } else if (len & 0xc0) { // this is link
be_bryan 0:b74591d5ab33 158 dns_scan_byte(p);
be_bryan 0:b74591d5ab33 159 break;
be_bryan 0:b74591d5ab33 160 }
be_bryan 0:b74591d5ab33 161
be_bryan 0:b74591d5ab33 162 *p += len;
be_bryan 0:b74591d5ab33 163 }
be_bryan 0:b74591d5ab33 164
be_bryan 0:b74591d5ab33 165 uint16_t rtype = dns_scan_word(p); // rtype
be_bryan 0:b74591d5ab33 166 uint16_t rclass = dns_scan_word(p); // rclass
be_bryan 0:b74591d5ab33 167 *p += 4; // ttl
be_bryan 0:b74591d5ab33 168 uint16_t rdlength = dns_scan_word(p); // rdlength
be_bryan 0:b74591d5ab33 169
be_bryan 0:b74591d5ab33 170 if (rtype == RR_A && rclass == CLASS_IN && rdlength == NSAPI_IPv4_BYTES) {
be_bryan 0:b74591d5ab33 171 // accept A record
be_bryan 0:b74591d5ab33 172 addr->version = NSAPI_IPv4;
be_bryan 0:b74591d5ab33 173 for (int i = 0; i < NSAPI_IPv4_BYTES; i++) {
be_bryan 0:b74591d5ab33 174 addr->bytes[i] = dns_scan_byte(p);
be_bryan 0:b74591d5ab33 175 }
be_bryan 0:b74591d5ab33 176
be_bryan 0:b74591d5ab33 177 addr += 1;
be_bryan 0:b74591d5ab33 178 count += 1;
be_bryan 0:b74591d5ab33 179 } else if (rtype == RR_AAAA && rclass == CLASS_IN && rdlength == NSAPI_IPv6_BYTES) {
be_bryan 0:b74591d5ab33 180 // accept AAAA record
be_bryan 0:b74591d5ab33 181 addr->version = NSAPI_IPv6;
be_bryan 0:b74591d5ab33 182 for (int i = 0; i < NSAPI_IPv6_BYTES; i++) {
be_bryan 0:b74591d5ab33 183 addr->bytes[i] = dns_scan_byte(p);
be_bryan 0:b74591d5ab33 184 }
be_bryan 0:b74591d5ab33 185
be_bryan 0:b74591d5ab33 186 addr += 1;
be_bryan 0:b74591d5ab33 187 count += 1;
be_bryan 0:b74591d5ab33 188 } else {
be_bryan 0:b74591d5ab33 189 // skip unrecognized records
be_bryan 0:b74591d5ab33 190 *p += rdlength;
be_bryan 0:b74591d5ab33 191 }
be_bryan 0:b74591d5ab33 192 }
be_bryan 0:b74591d5ab33 193
be_bryan 0:b74591d5ab33 194 return count;
be_bryan 0:b74591d5ab33 195 }
be_bryan 0:b74591d5ab33 196
be_bryan 0:b74591d5ab33 197 // core query function
be_bryan 0:b74591d5ab33 198 static nsapi_size_or_error_t nsapi_dns_query_multiple(NetworkStack *stack, const char *host,
be_bryan 0:b74591d5ab33 199 nsapi_addr_t *addr, unsigned addr_count, nsapi_version_t version)
be_bryan 0:b74591d5ab33 200 {
be_bryan 0:b74591d5ab33 201 // check for valid host name
be_bryan 0:b74591d5ab33 202 int host_len = host ? strlen(host) : 0;
be_bryan 0:b74591d5ab33 203 if (host_len > 128 || host_len == 0) {
be_bryan 0:b74591d5ab33 204 return NSAPI_ERROR_PARAMETER;
be_bryan 0:b74591d5ab33 205 }
be_bryan 0:b74591d5ab33 206
be_bryan 0:b74591d5ab33 207 // create a udp socket
be_bryan 0:b74591d5ab33 208 UDPSocket socket;
be_bryan 0:b74591d5ab33 209 int err = socket.open(stack);
be_bryan 0:b74591d5ab33 210 if (err) {
be_bryan 0:b74591d5ab33 211 return err;
be_bryan 0:b74591d5ab33 212 }
be_bryan 0:b74591d5ab33 213
be_bryan 0:b74591d5ab33 214 socket.set_timeout(DNS_TIMEOUT);
be_bryan 0:b74591d5ab33 215
be_bryan 0:b74591d5ab33 216 // create network packet
be_bryan 0:b74591d5ab33 217 uint8_t *packet = (uint8_t *)malloc(DNS_BUFFER_SIZE);
be_bryan 0:b74591d5ab33 218 if (!packet) {
be_bryan 0:b74591d5ab33 219 return NSAPI_ERROR_NO_MEMORY;
be_bryan 0:b74591d5ab33 220 }
be_bryan 0:b74591d5ab33 221
be_bryan 0:b74591d5ab33 222 nsapi_size_or_error_t result = NSAPI_ERROR_DNS_FAILURE;
be_bryan 0:b74591d5ab33 223
be_bryan 0:b74591d5ab33 224 // check against each dns server
be_bryan 0:b74591d5ab33 225 for (unsigned i = 0; i < DNS_SERVERS_SIZE; i++) {
be_bryan 0:b74591d5ab33 226 // send the question
be_bryan 0:b74591d5ab33 227 uint8_t *question = packet;
be_bryan 0:b74591d5ab33 228 dns_append_question(&question, host, version);
be_bryan 0:b74591d5ab33 229
be_bryan 0:b74591d5ab33 230 err = socket.sendto(SocketAddress(dns_servers[i], 53), packet, question - packet);
be_bryan 0:b74591d5ab33 231 // send may fail for various reasons, including wrong address type - move on
be_bryan 0:b74591d5ab33 232 if (err < 0) {
be_bryan 0:b74591d5ab33 233 continue;
be_bryan 0:b74591d5ab33 234 }
be_bryan 0:b74591d5ab33 235
be_bryan 0:b74591d5ab33 236 // recv the response
be_bryan 0:b74591d5ab33 237 err = socket.recvfrom(NULL, packet, DNS_BUFFER_SIZE);
be_bryan 0:b74591d5ab33 238 if (err == NSAPI_ERROR_WOULD_BLOCK) {
be_bryan 0:b74591d5ab33 239 continue;
be_bryan 0:b74591d5ab33 240 } else if (err < 0) {
be_bryan 0:b74591d5ab33 241 result = err;
be_bryan 0:b74591d5ab33 242 break;
be_bryan 0:b74591d5ab33 243 }
be_bryan 0:b74591d5ab33 244
be_bryan 0:b74591d5ab33 245 const uint8_t *response = packet;
be_bryan 0:b74591d5ab33 246 if (dns_scan_response(&response, addr, addr_count) > 0) {
be_bryan 0:b74591d5ab33 247 result = NSAPI_ERROR_OK;
be_bryan 0:b74591d5ab33 248 }
be_bryan 0:b74591d5ab33 249
be_bryan 0:b74591d5ab33 250 /* The DNS response is final, no need to check other servers */
be_bryan 0:b74591d5ab33 251 break;
be_bryan 0:b74591d5ab33 252 }
be_bryan 0:b74591d5ab33 253
be_bryan 0:b74591d5ab33 254 // clean up packet
be_bryan 0:b74591d5ab33 255 free(packet);
be_bryan 0:b74591d5ab33 256
be_bryan 0:b74591d5ab33 257 // clean up udp
be_bryan 0:b74591d5ab33 258 err = socket.close();
be_bryan 0:b74591d5ab33 259 if (err) {
be_bryan 0:b74591d5ab33 260 return err;
be_bryan 0:b74591d5ab33 261 }
be_bryan 0:b74591d5ab33 262
be_bryan 0:b74591d5ab33 263 // return result
be_bryan 0:b74591d5ab33 264 return result;
be_bryan 0:b74591d5ab33 265 }
be_bryan 0:b74591d5ab33 266
be_bryan 0:b74591d5ab33 267 // convenience functions for other forms of queries
be_bryan 0:b74591d5ab33 268 extern "C" nsapi_size_or_error_t nsapi_dns_query_multiple(nsapi_stack_t *stack, const char *host,
be_bryan 0:b74591d5ab33 269 nsapi_addr_t *addr, nsapi_size_t addr_count, nsapi_version_t version)
be_bryan 0:b74591d5ab33 270 {
be_bryan 0:b74591d5ab33 271 NetworkStack *nstack = nsapi_create_stack(stack);
be_bryan 0:b74591d5ab33 272 return nsapi_dns_query_multiple(nstack, host, addr, addr_count, version);
be_bryan 0:b74591d5ab33 273 }
be_bryan 0:b74591d5ab33 274
be_bryan 0:b74591d5ab33 275 nsapi_size_or_error_t nsapi_dns_query_multiple(NetworkStack *stack, const char *host,
be_bryan 0:b74591d5ab33 276 SocketAddress *addresses, nsapi_size_t addr_count, nsapi_version_t version)
be_bryan 0:b74591d5ab33 277 {
be_bryan 0:b74591d5ab33 278 nsapi_addr_t *addrs = new nsapi_addr_t[addr_count];
be_bryan 0:b74591d5ab33 279 nsapi_size_or_error_t result = nsapi_dns_query_multiple(stack, host, addrs, addr_count, version);
be_bryan 0:b74591d5ab33 280
be_bryan 0:b74591d5ab33 281 if (result > 0) {
be_bryan 0:b74591d5ab33 282 for (int i = 0; i < result; i++) {
be_bryan 0:b74591d5ab33 283 addresses[i].set_addr(addrs[i]);
be_bryan 0:b74591d5ab33 284 }
be_bryan 0:b74591d5ab33 285 }
be_bryan 0:b74591d5ab33 286
be_bryan 0:b74591d5ab33 287 delete[] addrs;
be_bryan 0:b74591d5ab33 288 return result;
be_bryan 0:b74591d5ab33 289 }
be_bryan 0:b74591d5ab33 290
be_bryan 0:b74591d5ab33 291 extern "C" nsapi_error_t nsapi_dns_query(nsapi_stack_t *stack, const char *host,
be_bryan 0:b74591d5ab33 292 nsapi_addr_t *addr, nsapi_version_t version)
be_bryan 0:b74591d5ab33 293 {
be_bryan 0:b74591d5ab33 294 NetworkStack *nstack = nsapi_create_stack(stack);
be_bryan 0:b74591d5ab33 295 nsapi_size_or_error_t result = nsapi_dns_query_multiple(nstack, host, addr, 1, version);
be_bryan 0:b74591d5ab33 296 return (nsapi_error_t)((result > 0) ? 0 : result);
be_bryan 0:b74591d5ab33 297 }
be_bryan 0:b74591d5ab33 298
be_bryan 0:b74591d5ab33 299 nsapi_error_t nsapi_dns_query(NetworkStack *stack, const char *host,
be_bryan 0:b74591d5ab33 300 SocketAddress *address, nsapi_version_t version)
be_bryan 0:b74591d5ab33 301 {
be_bryan 0:b74591d5ab33 302 nsapi_addr_t addr;
be_bryan 0:b74591d5ab33 303 nsapi_size_or_error_t result = nsapi_dns_query_multiple(stack, host, &addr, 1, version);
be_bryan 0:b74591d5ab33 304 address->set_addr(addr);
be_bryan 0:b74591d5ab33 305 return (nsapi_error_t)((result > 0) ? 0 : result);
be_bryan 0:b74591d5ab33 306 }