#include "asterisk.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <unistd.h>
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/dns.h"
#include "asterisk/endian.h"
Go to the source code of this file.
Data Structures | |
struct | dn_answer |
struct | dns_HEADER |
Defines | |
#define | MAX_SIZE 4096 |
Functions | |
int | ast_search_dns (void *context, const char *dname, int class, int type, int(*callback)(void *context, unsigned char *answer, int len, unsigned char *fullanswer)) |
Perform DNS lookup (used by DNS, enum and SRV lookups). | |
static int | dns_parse_answer (void *context, int class, int type, unsigned char *answer, int len, int(*callback)(void *context, unsigned char *answer, int len, unsigned char *fullanswer)) |
Parse DNS lookup result, call callback. | |
static int | skip_name (unsigned char *s, int len) |
Definition in file dns.c.
#define MAX_SIZE 4096 |
int ast_search_dns | ( | void * | context, | |
const char * | dname, | |||
int | class, | |||
int | type, | |||
int(*)(void *context, unsigned char *answer, int len, unsigned char *fullanswer) | callback | |||
) |
Perform DNS lookup (used by DNS, enum and SRV lookups).
Definition at line 247 of file dns.c.
References ast_log(), ast_mutex_lock(), ast_mutex_unlock(), dns_parse_answer(), LOG_DEBUG, LOG_WARNING, and MAX_SIZE.
Referenced by ast_get_enum(), ast_get_srv(), and ast_get_txt().
00250 { 00251 #ifdef HAVE_RES_NINIT 00252 struct __res_state dnsstate; 00253 #endif 00254 unsigned char answer[MAX_SIZE]; 00255 int res, ret = -1; 00256 00257 #ifdef HAVE_RES_NINIT 00258 memset(&dnsstate, 0, sizeof(dnsstate)); 00259 res_ninit(&dnsstate); 00260 res = res_nsearch(&dnsstate, dname, class, type, answer, sizeof(answer)); 00261 #else 00262 ast_mutex_lock(&res_lock); 00263 res_init(); 00264 res = res_search(dname, class, type, answer, sizeof(answer)); 00265 #endif 00266 if (res > 0) { 00267 if ((res = dns_parse_answer(context, class, type, answer, res, callback)) < 0) { 00268 ast_log(LOG_WARNING, "DNS Parse error for %s\n", dname); 00269 ret = -1; 00270 } 00271 else if (res == 0) { 00272 ast_log(LOG_DEBUG, "No matches found in DNS for %s\n", dname); 00273 ret = 0; 00274 } 00275 else 00276 ret = 1; 00277 } 00278 #ifdef HAVE_RES_NINIT 00279 #ifdef HAVE_RES_NDESTROY 00280 res_ndestroy(&dnsstate); 00281 #else 00282 res_nclose(&dnsstate); 00283 #endif 00284 #else 00285 #ifndef __APPLE__ 00286 res_close(); 00287 #endif 00288 ast_mutex_unlock(&res_lock); 00289 #endif 00290 00291 return ret; 00292 }
static int dns_parse_answer | ( | void * | context, | |
int | class, | |||
int | type, | |||
unsigned char * | answer, | |||
int | len, | |||
int(*)(void *context, unsigned char *answer, int len, unsigned char *fullanswer) | callback | |||
) | [static] |
Parse DNS lookup result, call callback.
Definition at line 177 of file dns.c.
References dns_HEADER::ancount, ast_log(), dn_answer::class, LOG_WARNING, dns_HEADER::qdcount, dn_answer::rtype, dn_answer::size, and skip_name().
Referenced by ast_search_dns().
00180 { 00181 unsigned char *fullanswer = answer; 00182 struct dn_answer *ans; 00183 dns_HEADER *h; 00184 int res; 00185 int x; 00186 00187 h = (dns_HEADER *)answer; 00188 answer += sizeof(dns_HEADER); 00189 len -= sizeof(dns_HEADER); 00190 00191 for (x = 0; x < ntohs(h->qdcount); x++) { 00192 if ((res = skip_name(answer, len)) < 0) { 00193 ast_log(LOG_WARNING, "Couldn't skip over name\n"); 00194 return -1; 00195 } 00196 answer += res + 4; /* Skip name and QCODE / QCLASS */ 00197 len -= res + 4; 00198 if (len < 0) { 00199 ast_log(LOG_WARNING, "Strange query size\n"); 00200 return -1; 00201 } 00202 } 00203 00204 for (x = 0; x < ntohs(h->ancount); x++) { 00205 if ((res = skip_name(answer, len)) < 0) { 00206 ast_log(LOG_WARNING, "Failed skipping name\n"); 00207 return -1; 00208 } 00209 answer += res; 00210 len -= res; 00211 ans = (struct dn_answer *)answer; 00212 answer += sizeof(struct dn_answer); 00213 len -= sizeof(struct dn_answer); 00214 if (len < 0) { 00215 ast_log(LOG_WARNING, "Strange result size\n"); 00216 return -1; 00217 } 00218 if (len < 0) { 00219 ast_log(LOG_WARNING, "Length exceeds frame\n"); 00220 return -1; 00221 } 00222 00223 if (ntohs(ans->class) == class && ntohs(ans->rtype) == type) { 00224 if (callback) { 00225 if ((res = callback(context, answer, ntohs(ans->size), fullanswer)) < 0) { 00226 ast_log(LOG_WARNING, "Failed to parse result\n"); 00227 return -1; 00228 } 00229 if (res > 0) 00230 return 1; 00231 } 00232 } 00233 answer += ntohs(ans->size); 00234 len -= ntohs(ans->size); 00235 } 00236 return 0; 00237 }
static int skip_name | ( | unsigned char * | s, | |
int | len | |||
) | [static] |
Definition at line 153 of file dns.c.
Referenced by dns_parse_answer().
00154 { 00155 int x = 0; 00156 00157 while (x < len) { 00158 if (*s == '\0') { 00159 s++; 00160 x++; 00161 break; 00162 } 00163 if ((*s & 0xc0) == 0xc0) { 00164 s += 2; 00165 x += 2; 00166 break; 00167 } 00168 x += *s + 1; 00169 s += *s + 1; 00170 } 00171 if (x >= len) 00172 return -1; 00173 return x; 00174 }