1/* ********************************************************************* 2 * Broadcom Common Firmware Environment (CFE) 3 * 4 * Domain Name System Resolver File: net_dns.c 5 * 6 * This module provides minimal support for looking up IP addresses 7 * from DNS name servers (RFCxxxx) 8 * 9 * Author: Mitch Lichtenberg (mpl@broadcom.com) 10 * 11 ********************************************************************* 12 * 13 * Copyright 2000,2001,2002,2003 14 * Broadcom Corporation. All rights reserved. 15 * 16 * This software is furnished under license and may be used and 17 * copied only in accordance with the following terms and 18 * conditions. Subject to these conditions, you may download, 19 * copy, install, use, modify and distribute modified or unmodified 20 * copies of this software in source and/or binary form. No title 21 * or ownership is transferred hereby. 22 * 23 * 1) Any source code used, modified or distributed must reproduce 24 * and retain this copyright notice and list of conditions 25 * as they appear in the source file. 26 * 27 * 2) No right is granted to use any trade name, trademark, or 28 * logo of Broadcom Corporation. The "Broadcom Corporation" 29 * name may not be used to endorse or promote products derived 30 * from this software without the prior written permission of 31 * Broadcom Corporation. 32 * 33 * 3) THIS SOFTWARE IS PROVIDED "AS-IS" AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING BUT NOT LIMITED TO, ANY IMPLIED 35 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR 36 * PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED. IN NO EVENT 37 * SHALL BROADCOM BE LIABLE FOR ANY DAMAGES WHATSOEVER, AND IN 38 * PARTICULAR, BROADCOM SHALL NOT BE LIABLE FOR DIRECT, INDIRECT, 39 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 40 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 41 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 42 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 43 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR 44 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE), EVEN IF ADVISED OF 45 * THE POSSIBILITY OF SUCH DAMAGE. 46 ********************************************************************* */ 47 48 49#include "lib_types.h" 50#include "lib_string.h" 51#include "lib_queue.h" 52#include "lib_malloc.h" 53#include "lib_printf.h" 54 55#include "cfe_timer.h" 56#include "cfe_error.h" 57 58#include "net_ebuf.h" 59#include "net_ether.h" 60 61#include "cfe.h" 62 63#include "net_api.h" 64 65/* ********************************************************************* 66 * Macros 67 ********************************************************************* */ 68 69#define ip_addriszero(a) (((a)[0]|(a)[1]|(a)[2]|(a)[3]) == 0) 70 71/* ********************************************************************* 72 * Constants 73 ********************************************************************* */ 74 75#define UDP_PORT_DNS 53 76 77#define DNS_FLG_QUERY 0x0000 78#define DNS_FLG_RESPONSE 0x8000 79#define DNS_OPCODE_QUERY 0x0000 80#define DNS_FLG_AA 0x0400 81#define DNS_FLG_TC 0x0200 82#define DNS_FLG_RD 0x0100 83#define DNS_FLG_RA 0x0080 84#define DNS_RCODE_MASK 0x000F 85#define DNS_RCODE_OK 0x0000 86#define DNS_RCODE_NAMEERR 0x0003 87 88 89#define QTYPE_HOSTADDR 1 90#define QCLASS_INTERNET 1 91 92#define DNS_QUERY_TIMEOUT 1 /* seconds */ 93#define DNS_RETRY_COUNT 8 94 95 96/* ********************************************************************* 97 * dns_dolookup(s,hostname,ipaddr) 98 * 99 * Look up a host name and return its IP address. 100 * 101 * Input parameters: 102 * s - udp socket 103 * server - name server to query 104 * hostname - host name to find 105 * ipaddr - buffer to place IP address 106 * 107 * Return value: 108 * 0 if no responses found 109 * >0 to indicate number of response records (usually 1) 110 * else error code 111 ********************************************************************* */ 112 113static int dns_dolookup(int s,uint8_t *server,char *hostname,uint8_t *ipaddr) 114{ 115 ebuf_t *buf; 116 uint16_t id; 117 uint16_t tmp; 118 char *tok; 119 char *ptr; 120 int64_t timer; 121 int nres = 0; 122 uint16_t nqr,nar,nns,nxr; 123 uint8_t tmpb; 124 int expired; 125 126 127 /* 128 * Use the current time for our request ID 129 */ 130 131 id = (uint16_t) cfe_ticks; 132 133 /* 134 * Get a buffer and fill it in. 135 */ 136 137 buf = udp_alloc(); 138 139 ebuf_append_u16_be(buf,id); 140 ebuf_append_u16_be(buf,(DNS_FLG_QUERY | DNS_OPCODE_QUERY | DNS_FLG_RD)); 141 ebuf_append_u16_be(buf,1); /* one question */ 142 ebuf_append_u16_be(buf,0); /* no answers */ 143 ebuf_append_u16_be(buf,0); /* no server resource records */ 144 ebuf_append_u16_be(buf,0); /* no additional records */ 145 146 /* 147 * Chop up the hostname into pieces, basically replacing 148 * the dots with length indicators. 149 */ 150 151 ptr = hostname; 152 153 while ((tok = strchr(ptr,'.'))) { 154 ebuf_append_u8(buf,(tok-ptr)); 155 ebuf_append_bytes(buf,ptr,(tok-ptr)); 156 ptr = tok + 1; 157 } 158 159 ebuf_append_u8(buf,strlen(ptr)); 160 ebuf_append_bytes(buf,ptr,strlen(ptr)); 161 ebuf_append_u8(buf,0); 162 ebuf_append_u16_be(buf,QTYPE_HOSTADDR); 163 ebuf_append_u16_be(buf,QCLASS_INTERNET); 164 165 /* 166 * Send the request to the name server 167 */ 168 169 udp_send(s,buf,server); 170 171 /* 172 * Set a timer for the response 173 */ 174 175 TIMER_SET(timer,DNS_QUERY_TIMEOUT*CFE_HZ); 176 177 /* 178 * Start waiting... 179 */ 180 181 while (!(expired = TIMER_EXPIRED(timer))) { 182 POLL(); 183 184 buf = udp_recv(s); 185 if (!buf) continue; 186 187 /* IDs must match */ 188 189 ebuf_get_u16_be(buf,tmp); 190 if (id != tmp) goto drop; 191 192 /* It must be a response */ 193 194 ebuf_get_u16_be(buf,tmp); 195 196 if ((tmp & DNS_FLG_RESPONSE) == 0) goto drop; 197 198 if ((tmp & DNS_RCODE_MASK) != DNS_RCODE_OK) { 199 udp_free(buf); 200 /* name error */ 201 break; 202 } 203 204 ebuf_get_u16_be(buf,nqr); 205 ebuf_get_u16_be(buf,nar); 206 ebuf_get_u16_be(buf,nns); 207 ebuf_get_u16_be(buf,nxr); 208 209 if (nar == 0) { 210 goto drop; 211 } 212 213 while (nqr > 0) { 214 if (ebuf_length(buf) <= 0) { 215 goto drop; 216 } 217 for (;;) { 218 ebuf_get_u8(buf,tmpb); 219 if (tmpb == 0) break; 220 ebuf_skip(buf,tmpb); 221 if (ebuf_length(buf) <= 0) { 222 goto drop; 223 } 224 } 225 ebuf_skip(buf,2); /* skip QTYPE */ 226 ebuf_skip(buf,2); /* skip QCLASS */ 227 nqr--; /* next question record */ 228 } 229 230 /* 231 * Loop through the answer records to find 232 * a HOSTADDR record. Ignore any other records 233 * we find. 234 */ 235 236 while (nar > 0) { 237 uint16_t rname,rtype,rclass,dlen; 238 239 ebuf_get_u16_be(buf,rname); /* resource name */ 240 241 ebuf_get_u16_be(buf,rtype); /* resource type */ 242 243 ebuf_get_u16_be(buf,rclass); /* resource class */ 244 245 ebuf_skip(buf,4); /* time to live */ 246 247 ebuf_get_u16_be(buf,dlen); /* length of data */ 248 249 if (rtype != QTYPE_HOSTADDR) { 250 ebuf_skip(buf,dlen); 251 nar--; 252 continue; 253 } 254 if (rclass != QCLASS_INTERNET) { 255 ebuf_skip(buf,dlen); 256 nar--; 257 continue; 258 } 259 260 if (dlen != IP_ADDR_LEN) { 261 ebuf_skip(buf,dlen); 262 nar--; 263 continue; 264 } 265 266 ebuf_get_bytes(buf,ipaddr,IP_ADDR_LEN); 267 break; 268 } 269 270 if (nar == 0) goto drop; 271 272 udp_free(buf); 273 nres++; 274 break; 275 276 drop: 277 udp_free(buf); 278 } 279 280 if (expired) return CFE_ERR_TIMEOUT; 281 if (nres == 0) return CFE_ERR_HOSTUNKNOWN; 282 return nres; 283} 284 285 286/* ********************************************************************* 287 * dns_lookup(hostname,ipaddr) 288 * 289 * Look up a host name and return its IP address. 290 * 291 * Input parameters: 292 * hostname - host name to find 293 * ipaddr - buffer to place IP address 294 * 295 * Return value: 296 * 0 if no responses found 297 * >0 to indicate number of response records (usually 1) 298 * else error code 299 ********************************************************************* */ 300 301int dns_lookup(char *hostname,uint8_t *ipaddr) 302{ 303 int s; 304 int nres = 0; 305 int retries; 306 char temphostname[100]; 307 uint8_t *server; 308 char *tok; 309 310 /* 311 * If it's a valid IP address, don't look it up. 312 */ 313 314 if (parseipaddr(hostname,ipaddr) == 0) return 1; 315 316 /* 317 * Add default domain if no domain was specified 318 */ 319 320 if (strchr(hostname,'.') == NULL) { 321 tok = net_getparam(NET_DOMAIN); 322 if (tok) { 323 xsprintf(temphostname,"%s.%s",hostname,tok); 324 hostname = temphostname; 325 } 326 } 327 328 /* 329 * Figure out who the name server is 330 */ 331 332 server = net_getparam(NET_NAMESERVER); 333 334 if (!server) return CFE_ERR_NETDOWN; 335 if (ip_addriszero(server)) return CFE_ERR_NONAMESERVER; 336 337 /* 338 * Go do the name server lookup 339 */ 340 341 s = udp_socket(UDP_PORT_DNS); 342 if (s < 0) return CFE_ERR_NOHANDLES; 343 344 for (retries = 0; retries < DNS_RETRY_COUNT; retries++) { 345 nres = dns_dolookup(s,server,hostname,ipaddr); 346 if (nres == CFE_ERR_TIMEOUT) continue; 347 if (nres >= 0) break; 348 } 349 350 udp_close(s); 351 352 return nres; 353 354} 355