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 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 "cfe.h" 50 51#include "net_ebuf.h" 52#include "net_ether.h" 53 54#include "net_api.h" 55 56/* ********************************************************************* 57 * Macros 58 ********************************************************************* */ 59 60#define ip_addriszero(a) (((a)[0]|(a)[1]|(a)[2]|(a)[3]) == 0) 61 62/* ********************************************************************* 63 * Constants 64 ********************************************************************* */ 65 66#define UDP_PORT_DNS 53 67 68#define DNS_FLG_QUERY 0x0000 69#define DNS_FLG_RESPONSE 0x8000 70#define DNS_OPCODE_QUERY 0x0000 71#define DNS_FLG_AA 0x0400 72#define DNS_FLG_TC 0x0200 73#define DNS_FLG_RD 0x0100 74#define DNS_FLG_RA 0x0080 75#define DNS_RCODE_MASK 0x000F 76#define DNS_RCODE_OK 0x0000 77#define DNS_RCODE_NAMEERR 0x0003 78 79 80#define QTYPE_HOSTADDR 1 81#define QCLASS_INTERNET 1 82 83#define DNS_QUERY_TIMEOUT 1 /* seconds */ 84#define DNS_RETRY_COUNT 8 85 86 87/* ********************************************************************* 88 * dns_dolookup(s,hostname,ipaddr) 89 * 90 * Look up a host name and return its IP address. 91 * 92 * Input parameters: 93 * s - udp socket 94 * server - name server to query 95 * hostname - host name to find 96 * ipaddr - buffer to place IP address 97 * 98 * Return value: 99 * 0 if no responses found 100 * >0 to indicate number of response records (usually 1) 101 * else error code 102 ********************************************************************* */ 103 104static int dns_dolookup(int s,uint8_t *server,char *hostname,uint8_t *ipaddr) 105{ 106 ebuf_t *buf; 107 uint16_t id; 108 uint16_t tmp; 109 char *tok; 110 char *ptr; 111 int64_t timer; 112 int nres = 0; 113 uint16_t nqr,nar,nns,nxr; 114 uint8_t tmpb; 115 int expired; 116 117 118 /* 119 * Use the current time for our request ID 120 */ 121 122 id = (uint16_t) cfe_ticks; 123 124 /* 125 * Get a buffer and fill it in. 126 */ 127 128 buf = udp_alloc(); 129 130 ebuf_append_u16_be(buf,id); 131 ebuf_append_u16_be(buf,(DNS_FLG_QUERY | DNS_OPCODE_QUERY | DNS_FLG_RD)); 132 ebuf_append_u16_be(buf,1); /* one question */ 133 ebuf_append_u16_be(buf,0); /* no answers */ 134 ebuf_append_u16_be(buf,0); /* no server resource records */ 135 ebuf_append_u16_be(buf,0); /* no additional records */ 136 137 /* 138 * Chop up the hostname into pieces, basically replacing 139 * the dots with length indicators. 140 */ 141 142 ptr = hostname; 143 144 while ((tok = strchr(ptr,'.'))) { 145 ebuf_append_u8(buf,(tok-ptr)); 146 ebuf_append_bytes(buf,ptr,(tok-ptr)); 147 ptr = tok + 1; 148 } 149 150 ebuf_append_u8(buf,strlen(ptr)); 151 ebuf_append_bytes(buf,ptr,strlen(ptr)); 152 ebuf_append_u8(buf,0); 153 ebuf_append_u16_be(buf,QTYPE_HOSTADDR); 154 ebuf_append_u16_be(buf,QCLASS_INTERNET); 155 156 /* 157 * Send the request to the name server 158 */ 159 160 udp_send(s,buf,server); 161 162 /* 163 * Set a timer for the response 164 */ 165 166 TIMER_SET(timer,DNS_QUERY_TIMEOUT*CFE_HZ); 167 168 /* 169 * Start waiting... 170 */ 171 172 while (!(expired = TIMER_EXPIRED(timer))) { 173 POLL(); 174 175 buf = udp_recv(s); 176 if (!buf) continue; 177 178 /* IDs must match */ 179 180 ebuf_get_u16_be(buf,tmp); 181 if (id != tmp) goto drop; 182 183 /* It must be a response */ 184 185 ebuf_get_u16_be(buf,tmp); 186 187 if ((tmp & DNS_FLG_RESPONSE) == 0) goto drop; 188 189 if ((tmp & DNS_RCODE_MASK) != DNS_RCODE_OK) { 190 udp_free(buf); 191 /* name error */ 192 break; 193 } 194 195 ebuf_get_u16_be(buf,nqr); 196 ebuf_get_u16_be(buf,nar); 197 ebuf_get_u16_be(buf,nns); 198 ebuf_get_u16_be(buf,nxr); 199 200 if (nar == 0) { 201 goto drop; 202 } 203 204 while (nqr > 0) { 205 if (ebuf_length(buf) <= 0) { 206 goto drop; 207 } 208 for (;;) { 209 ebuf_get_u8(buf,tmpb); 210 if (tmpb == 0) break; 211 ebuf_skip(buf,tmpb); 212 if (ebuf_length(buf) <= 0) { 213 goto drop; 214 } 215 } 216 ebuf_skip(buf,2); /* skip QTYPE */ 217 ebuf_skip(buf,2); /* skip QCLASS */ 218 nqr--; /* next question record */ 219 } 220 221 /* 222 * Loop through the answer records to find 223 * a HOSTADDR record. Ignore any other records 224 * we find. 225 */ 226 227 while (nar > 0) { 228 uint16_t rname,rtype,rclass,dlen; 229 230 ebuf_get_u16_be(buf,rname); /* resource name */ 231 232 ebuf_get_u16_be(buf,rtype); /* resource type */ 233 234 ebuf_get_u16_be(buf,rclass); /* resource class */ 235 236 ebuf_skip(buf,4); /* time to live */ 237 238 ebuf_get_u16_be(buf,dlen); /* length of data */ 239 240 if (rtype != QTYPE_HOSTADDR) { 241 ebuf_skip(buf,dlen); 242 nar--; 243 continue; 244 } 245 if (rclass != QCLASS_INTERNET) { 246 ebuf_skip(buf,dlen); 247 nar--; 248 continue; 249 } 250 251 if (dlen != IP_ADDR_LEN) { 252 ebuf_skip(buf,dlen); 253 nar--; 254 continue; 255 } 256 257 ebuf_get_bytes(buf,ipaddr,IP_ADDR_LEN); 258 break; 259 } 260 261 if (nar == 0) goto drop; 262 263 udp_free(buf); 264 nres++; 265 break; 266 267 drop: 268 udp_free(buf); 269 } 270 271 if (expired) return CFE_ERR_TIMEOUT; 272 if (nres == 0) return CFE_ERR_HOSTUNKNOWN; 273 return nres; 274} 275 276 277/* ********************************************************************* 278 * dns_lookup(hostname,ipaddr) 279 * 280 * Look up a host name and return its IP address. 281 * 282 * Input parameters: 283 * hostname - host name to find 284 * ipaddr - buffer to place IP address 285 * 286 * Return value: 287 * 0 if no responses found 288 * >0 to indicate number of response records (usually 1) 289 * else error code 290 ********************************************************************* */ 291 292int dns_lookup(char *hostname,uint8_t *ipaddr) 293{ 294 int s; 295 int nres = 0; 296 int retries; 297 char temphostname[100]; 298 uint8_t *server; 299 char *tok; 300 301 /* 302 * If it's a valid IP address, don't look it up. 303 */ 304 305 if (parseipaddr(hostname,ipaddr) == 0) return 1; 306 307 /* 308 * Add default domain if no domain was specified 309 */ 310 311 if (strchr(hostname,'.') == NULL) { 312 tok = (char *)net_getparam(NET_DOMAIN); 313 if (tok) { 314 xsprintf(temphostname,"%s.%s",hostname,tok); 315 hostname = temphostname; 316 } 317 } 318 319 /* 320 * Figure out who the name server is 321 */ 322 323 server = net_getparam(NET_NAMESERVER); 324 325 if (!server) return CFE_ERR_NETDOWN; 326 if (ip_addriszero(server)) return CFE_ERR_NONAMESERVER; 327 328 /* 329 * Go do the name server lookup 330 */ 331 332 s = udp_socket(UDP_PORT_DNS); 333 if (s < 0) return CFE_ERR_NOHANDLES; 334 335 for (retries = 0; retries < DNS_RETRY_COUNT; retries++) { 336 nres = dns_dolookup(s,server,hostname,ipaddr); 337 if (nres == CFE_ERR_TIMEOUT) continue; 338 if (nres >= 0) break; 339 } 340 341 udp_close(s); 342 343 return nres; 344 345} 346