void
sethostent(int stayopen)
{
struct __res_state *_resp = _THREAD_PRIVATE(_res, _res, &_res);
if (_res_init(0) == -1)
return;
if (stayopen)
_resp->options |= RES_STAYOPEN | RES_USEVC;
}
struct hostent *gethostbyaddr(const char *addr, int len, int type)
{
struct res_data *data = _res_init();
if (!data)
return NULL;
if (!data->buf) {
data->buf = malloc(sizeof(struct hostent) + HOST_BUFSIZE);
if (!data->buf) {
errno = 0;
data->errval = NO_RECOVERY;
return NULL;
}
}
return gethostbyaddr_r(addr, len, type, (struct hostent *) data->buf,
data->buf + sizeof(struct hostent), HOST_BUFSIZE,
&data->errval);
}
#if PACKETSZ > 1024
#define MAXPACKET PACKETSZ
#else
#define MAXPACKET 1024
#endif
int res_query(char *name, int class, int type, unsigned char *answer,
int anslen)
{
struct res_data *data;
char buf[MAXPACKET];
int result;
HEADER *hp;
data = _res_init();
if (!data)
return -1;
/* Make the query. */
result = res_mkquery(QUERY, name, class, type, NULL, 0, NULL, buf,
sizeof(buf));
if (result <= 0) {
data->errval = NO_RECOVERY;
return result;
}
result = res_send(buf, result, (char *) answer, anslen);
if (result < 0) {
data->errval = TRY_AGAIN;
return result;
struct hostent *gethostbyaddr_r(const char *addr, int len, int type,
struct hostent *result, char *buf, int bufsize,
int *errval)
{
struct res_data *data;
querybuf qbuf;
char lookups[MAXDNSLUS], addrbuf[MAXDNAME], *abuf;
struct hostent *hp;
int n, i;
/* Default failure condition is not a range error and not recoverable. */
errno = 0;
*errval = NO_RECOVERY;
data = _res_init();
if (!data)
return NULL;
if (type != AF_INET)
return NULL;
sprintf(addrbuf, "%u.%u.%u.%u.in-addr.arpa",
(unsigned)addr[3] & 0xff, (unsigned)addr[2] & 0xff,
(unsigned)addr[1] & 0xff, (unsigned)addr[0] & 0xff);
memcpy(lookups, data->state.lookups, sizeof(lookups));
if (*lookups == 0)
strncpy(lookups, "bf", sizeof(lookups));
hp = NULL;
for (i = 0; i < MAXDNSLUS && hp == NULL && lookups[i]; i++) {
switch (lookups[i]) {
case 'b':
/* Allocate space for a one-item list of addresses. */
abuf = SP(SP(buf, char *, 2), struct in_addr, 1);
if (abuf > buf + bufsize) {
errno = ERANGE;
return NULL;
}
/* Perform and parse the query. */
n = res_query(addrbuf, C_IN, T_PTR, (char *)&qbuf, sizeof(qbuf));
if (n < 0)
break;
hp = _res_parse_answer(&qbuf, n, 1, result, abuf,
bufsize - (abuf - buf), errval);
if (hp == NULL)
break;
/* Fill in our own address list. */
result->h_addrtype = type;
result->h_length = len;
result->h_addr_list = (char **) ALIGN(buf, char *);
result->h_addr_list[0] = ALIGN(&result->h_addr_list[2],
struct in_addr);
result->h_addr_list[1] = NULL;
break;
case 'f':
hp = file_find_addr(addr, len, type, result, buf, bufsize, errval);
break;
}
}
return hp;
}
