502 lines
16 KiB
C
502 lines
16 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <net/if.h>
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#include <netdb.h>
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#include <nss.h>
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#include <stdlib.h>
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#include <string.h>
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#include "alloc-util.h"
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#include "errno-util.h"
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#include "hostname-util.h"
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#include "local-addresses.h"
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#include "macro.h"
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#include "nss-util.h"
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#include "signal-util.h"
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#include "string-util.h"
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/* We use 127.0.0.2 as IPv4 address. This has the advantage over
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* 127.0.0.1 that it can be translated back to the local hostname. For
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* IPv6 we use ::1 which unfortunately will not translate back to the
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* hostname but instead something like "localhost" or so. */
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#define LOCALADDRESS_IPV4 (htobe32(0x7F000002))
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#define LOCALADDRESS_IPV6 &in6addr_loopback
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NSS_GETHOSTBYNAME_PROTOTYPES(myhostname);
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NSS_GETHOSTBYADDR_PROTOTYPES(myhostname);
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enum nss_status _nss_myhostname_gethostbyname4_r(
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const char *name,
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struct gaih_addrtuple **pat,
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char *buffer, size_t buflen,
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int *errnop, int *h_errnop,
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int32_t *ttlp) {
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struct gaih_addrtuple *r_tuple, *r_tuple_prev = NULL;
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_cleanup_free_ struct local_address *addresses = NULL;
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_cleanup_free_ char *hn = NULL;
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const char *canonical = NULL;
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int n_addresses = 0;
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uint32_t local_address_ipv4;
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struct local_address *a;
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size_t l, idx, ms;
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char *r_name;
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unsigned n;
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PROTECT_ERRNO;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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assert(name);
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assert(pat);
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assert(buffer);
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assert(errnop);
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assert(h_errnop);
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if (is_localhost(name)) {
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/* We respond to 'localhost', so that /etc/hosts
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* is optional */
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canonical = "localhost";
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local_address_ipv4 = htobe32(INADDR_LOOPBACK);
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} else if (is_gateway_hostname(name)) {
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n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
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if (n_addresses <= 0) {
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*h_errnop = HOST_NOT_FOUND;
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return NSS_STATUS_NOTFOUND;
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}
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canonical = "_gateway";
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} else {
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hn = gethostname_malloc();
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if (!hn) {
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UNPROTECT_ERRNO;
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*errnop = ENOMEM;
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*h_errnop = NO_RECOVERY;
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return NSS_STATUS_TRYAGAIN;
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}
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/* We respond to our local host name, our hostname suffixed with a single dot. */
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if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
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*h_errnop = HOST_NOT_FOUND;
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return NSS_STATUS_NOTFOUND;
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}
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n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
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if (n_addresses < 0)
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n_addresses = 0;
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canonical = hn;
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local_address_ipv4 = LOCALADDRESS_IPV4;
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}
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l = strlen(canonical);
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ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * (n_addresses > 0 ? n_addresses : 2);
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if (buflen < ms) {
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UNPROTECT_ERRNO;
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*errnop = ERANGE;
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*h_errnop = NETDB_INTERNAL;
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return NSS_STATUS_TRYAGAIN;
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}
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/* First, fill in hostname */
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r_name = buffer;
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memcpy(r_name, canonical, l+1);
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idx = ALIGN(l+1);
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assert(n_addresses >= 0);
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if (n_addresses == 0) {
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/* Second, fill in IPv6 tuple */
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r_tuple = (struct gaih_addrtuple*) (buffer + idx);
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r_tuple->next = r_tuple_prev;
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r_tuple->name = r_name;
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r_tuple->family = AF_INET6;
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memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16);
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r_tuple->scopeid = 0;
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idx += ALIGN(sizeof(struct gaih_addrtuple));
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r_tuple_prev = r_tuple;
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/* Third, fill in IPv4 tuple */
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r_tuple = (struct gaih_addrtuple*) (buffer + idx);
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r_tuple->next = r_tuple_prev;
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r_tuple->name = r_name;
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r_tuple->family = AF_INET;
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*(uint32_t*) r_tuple->addr = local_address_ipv4;
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r_tuple->scopeid = 0;
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idx += ALIGN(sizeof(struct gaih_addrtuple));
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r_tuple_prev = r_tuple;
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}
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/* Fourth, fill actual addresses in, but in backwards order */
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for (a = addresses + n_addresses - 1, n = 0; (int) n < n_addresses; n++, a--) {
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r_tuple = (struct gaih_addrtuple*) (buffer + idx);
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r_tuple->next = r_tuple_prev;
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r_tuple->name = r_name;
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r_tuple->family = a->family;
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r_tuple->scopeid = a->family == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&a->address.in6) ? a->ifindex : 0;
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memcpy(r_tuple->addr, &a->address, 16);
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idx += ALIGN(sizeof(struct gaih_addrtuple));
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r_tuple_prev = r_tuple;
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}
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/* Verify the size matches */
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assert(idx == ms);
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/* Nscd expects us to store the first record in **pat. */
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if (*pat)
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**pat = *r_tuple_prev;
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else
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*pat = r_tuple_prev;
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if (ttlp)
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*ttlp = 0;
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/* Explicitly reset both *h_errnop and h_errno to work around
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* https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
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*h_errnop = NETDB_SUCCESS;
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h_errno = 0;
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return NSS_STATUS_SUCCESS;
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}
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static enum nss_status fill_in_hostent(
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const char *canonical, const char *additional,
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int af,
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struct local_address *addresses, unsigned n_addresses,
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uint32_t local_address_ipv4,
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struct hostent *result,
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char *buffer, size_t buflen,
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int *errnop, int *h_errnop,
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int32_t *ttlp,
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char **canonp) {
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size_t l_canonical, l_additional, idx, ms, alen;
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char *r_addr, *r_name, *r_aliases, *r_alias = NULL, *r_addr_list;
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struct local_address *a;
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unsigned n, c;
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assert(canonical);
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assert(result);
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assert(buffer);
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assert(errnop);
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assert(h_errnop);
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PROTECT_ERRNO;
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alen = FAMILY_ADDRESS_SIZE(af);
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for (a = addresses, n = 0, c = 0; n < n_addresses; a++, n++)
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if (af == a->family)
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c++;
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l_canonical = strlen(canonical);
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l_additional = strlen_ptr(additional);
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ms = ALIGN(l_canonical+1)+
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(additional ? ALIGN(l_additional+1) : 0) +
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sizeof(char*) +
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(additional ? sizeof(char*) : 0) +
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(c > 0 ? c : 1) * ALIGN(alen) +
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(c > 0 ? c+1 : 2) * sizeof(char*);
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if (buflen < ms) {
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UNPROTECT_ERRNO;
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*errnop = ERANGE;
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*h_errnop = NETDB_INTERNAL;
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return NSS_STATUS_TRYAGAIN;
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}
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/* First, fill in hostnames */
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r_name = buffer;
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memcpy(r_name, canonical, l_canonical+1);
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idx = ALIGN(l_canonical+1);
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if (additional) {
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r_alias = buffer + idx;
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memcpy(r_alias, additional, l_additional+1);
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idx += ALIGN(l_additional+1);
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}
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/* Second, create aliases array */
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r_aliases = buffer + idx;
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if (additional) {
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((char**) r_aliases)[0] = r_alias;
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((char**) r_aliases)[1] = NULL;
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idx += 2*sizeof(char*);
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} else {
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((char**) r_aliases)[0] = NULL;
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idx += sizeof(char*);
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}
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/* Third, add addresses */
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r_addr = buffer + idx;
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if (c > 0) {
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unsigned i = 0;
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for (a = addresses, n = 0; n < n_addresses; a++, n++) {
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if (af != a->family)
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continue;
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memcpy(r_addr + i*ALIGN(alen), &a->address, alen);
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i++;
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}
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assert(i == c);
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idx += c*ALIGN(alen);
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} else {
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if (af == AF_INET)
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*(uint32_t*) r_addr = local_address_ipv4;
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else
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memcpy(r_addr, LOCALADDRESS_IPV6, 16);
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idx += ALIGN(alen);
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}
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/* Fourth, add address pointer array */
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r_addr_list = buffer + idx;
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if (c > 0) {
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unsigned i;
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for (i = 0; i < c; i++)
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((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen);
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((char**) r_addr_list)[i] = NULL;
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idx += (c+1) * sizeof(char*);
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} else {
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((char**) r_addr_list)[0] = r_addr;
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((char**) r_addr_list)[1] = NULL;
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idx += 2 * sizeof(char*);
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}
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/* Verify the size matches */
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assert(idx == ms);
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result->h_name = r_name;
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result->h_aliases = (char**) r_aliases;
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result->h_addrtype = af;
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result->h_length = alen;
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result->h_addr_list = (char**) r_addr_list;
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if (ttlp)
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*ttlp = 0;
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if (canonp)
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*canonp = r_name;
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/* Explicitly reset both *h_errnop and h_errno to work around
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* https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
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*h_errnop = NETDB_SUCCESS;
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h_errno = 0;
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return NSS_STATUS_SUCCESS;
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}
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enum nss_status _nss_myhostname_gethostbyname3_r(
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const char *name,
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int af,
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struct hostent *host,
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char *buffer, size_t buflen,
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int *errnop, int *h_errnop,
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int32_t *ttlp,
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char **canonp) {
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_cleanup_free_ struct local_address *addresses = NULL;
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const char *canonical, *additional = NULL;
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_cleanup_free_ char *hn = NULL;
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uint32_t local_address_ipv4 = 0;
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int n_addresses = 0;
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PROTECT_ERRNO;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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assert(name);
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assert(host);
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assert(buffer);
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assert(errnop);
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assert(h_errnop);
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if (af == AF_UNSPEC)
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af = AF_INET;
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if (!IN_SET(af, AF_INET, AF_INET6)) {
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UNPROTECT_ERRNO;
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*errnop = EAFNOSUPPORT;
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*h_errnop = NO_DATA;
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return NSS_STATUS_UNAVAIL;
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}
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if (is_localhost(name)) {
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canonical = "localhost";
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local_address_ipv4 = htobe32(INADDR_LOOPBACK);
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} else if (is_gateway_hostname(name)) {
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n_addresses = local_gateways(NULL, 0, af, &addresses);
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if (n_addresses <= 0) {
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*h_errnop = HOST_NOT_FOUND;
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return NSS_STATUS_NOTFOUND;
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}
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canonical = "_gateway";
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} else {
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hn = gethostname_malloc();
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if (!hn) {
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UNPROTECT_ERRNO;
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*errnop = ENOMEM;
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*h_errnop = NO_RECOVERY;
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return NSS_STATUS_TRYAGAIN;
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}
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if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
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*h_errnop = HOST_NOT_FOUND;
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return NSS_STATUS_NOTFOUND;
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}
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n_addresses = local_addresses(NULL, 0, af, &addresses);
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if (n_addresses < 0)
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n_addresses = 0;
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canonical = hn;
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additional = n_addresses <= 0 && af == AF_INET6 ? "localhost" : NULL;
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local_address_ipv4 = LOCALADDRESS_IPV4;
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}
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UNPROTECT_ERRNO;
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return fill_in_hostent(
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canonical, additional,
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af,
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addresses, n_addresses,
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local_address_ipv4,
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host,
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buffer, buflen,
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errnop, h_errnop,
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ttlp,
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canonp);
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}
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enum nss_status _nss_myhostname_gethostbyaddr2_r(
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const void* addr, socklen_t len,
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int af,
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struct hostent *host,
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char *buffer, size_t buflen,
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int *errnop, int *h_errnop,
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int32_t *ttlp) {
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const char *canonical = NULL, *additional = NULL;
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uint32_t local_address_ipv4 = LOCALADDRESS_IPV4;
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_cleanup_free_ struct local_address *addresses = NULL;
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_cleanup_free_ char *hn = NULL;
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int n_addresses = 0;
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struct local_address *a;
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bool additional_from_hostname = false;
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unsigned n;
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PROTECT_ERRNO;
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BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
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assert(addr);
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assert(host);
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assert(buffer);
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assert(errnop);
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assert(h_errnop);
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if (!IN_SET(af, AF_INET, AF_INET6)) {
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UNPROTECT_ERRNO;
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*errnop = EAFNOSUPPORT;
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*h_errnop = NO_DATA;
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return NSS_STATUS_UNAVAIL;
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}
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if (len != FAMILY_ADDRESS_SIZE(af)) {
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UNPROTECT_ERRNO;
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*errnop = EINVAL;
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*h_errnop = NO_RECOVERY;
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return NSS_STATUS_UNAVAIL;
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}
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if (af == AF_INET) {
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if ((*(uint32_t*) addr) == LOCALADDRESS_IPV4)
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goto found;
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if ((*(uint32_t*) addr) == htobe32(INADDR_LOOPBACK)) {
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canonical = "localhost";
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local_address_ipv4 = htobe32(INADDR_LOOPBACK);
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goto found;
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}
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} else {
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assert(af == AF_INET6);
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if (memcmp(addr, LOCALADDRESS_IPV6, 16) == 0) {
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canonical = "localhost";
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additional_from_hostname = true;
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goto found;
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}
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}
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n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
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for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
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if (af != a->family)
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continue;
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if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0)
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goto found;
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}
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addresses = mfree(addresses);
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n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
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for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
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if (af != a->family)
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continue;
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if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
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canonical = "_gateway";
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goto found;
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}
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}
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*h_errnop = HOST_NOT_FOUND;
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return NSS_STATUS_NOTFOUND;
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found:
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if (!canonical || additional_from_hostname) {
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hn = gethostname_malloc();
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if (!hn) {
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UNPROTECT_ERRNO;
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*errnop = ENOMEM;
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*h_errnop = NO_RECOVERY;
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return NSS_STATUS_TRYAGAIN;
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}
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if (!canonical)
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canonical = hn;
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else
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additional = hn;
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}
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UNPROTECT_ERRNO;
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return fill_in_hostent(
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canonical, additional,
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af,
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addresses, n_addresses,
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local_address_ipv4,
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host,
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buffer, buflen,
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errnop, h_errnop,
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ttlp,
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NULL);
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}
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NSS_GETHOSTBYNAME_FALLBACKS(myhostname);
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NSS_GETHOSTBYADDR_FALLBACKS(myhostname);
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