Christian Heimes
e28ec76898
FreeIPA's Python and C code used different approaches to get the FQDN of the host. Some places assumed that gethostname() returns a FQDN. Other code paths used glibc's resolver to resolve the current node name to a FQDN. Python code now uses the ipalib.constants.FQDN where a fully qualified domain name is expected. The variable is initialized only once and avoids potential DNS lookups. C code uses a new helper function ipa_gethostfqdn() in util package. The function implements similar logic as gethostfqdn() except it uses more modern getaddrinfo(). The result is cached as well. Fixes: https://pagure.io/freeipa/issue/8501 Signed-off-by: Christian Heimes <cheimes@redhat.com> Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>
112 lines
2.4 KiB
C
112 lines
2.4 KiB
C
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/*
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* Copyright (C) 2020 FreeIPA Contributors see COPYING for license
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*/
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#ifndef _GNU_SOURCE
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#define _GNU_SOURCE
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#endif
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#include <netdb.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include "ipa_hostname.h"
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int
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ipa_gethostname(char *name)
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{
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int ret;
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ret = gethostname(name, IPA_HOST_NAME_LEN - 1);
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/* Make double sure it is terminated */
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name[IPA_HOST_NAME_LEN - 1] = '\0';
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return ret;
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}
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static int
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_get_fqdn(char *fqdn)
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{
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char hostname[IPA_HOST_NAME_LEN];
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char *canonname = NULL;
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struct addrinfo hints;
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struct addrinfo *ai = NULL;
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int r;
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r = ipa_gethostname(hostname);
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if (r != 0) {
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goto error;
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}
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memset(&hints, 0, sizeof(struct addrinfo));
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/* use IPv4 or IPv6 */
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hints.ai_family = AF_UNSPEC;
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/* optimize, RAW and STREAM return same kind of information */
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hints.ai_socktype = SOCK_DGRAM;
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/* any protocol */
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hints.ai_protocol = 0;
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/* get canonical name
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* only use IPv4/6 when at least one interface for proto is configured */
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hints.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
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r = getaddrinfo(hostname, NULL, &hints, &ai);
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if (r != 0) {
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/* getaddrinfo() for gethostname() should never fail. The
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* nss-myhostname provider should always add a positive match. */
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errno = ENOENT;
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goto error;
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}
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/* only the first addrinfo struct holds a canonical name value */
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canonname = ai->ai_canonname;
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/* check that canon name is filled and not too long */
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if (!canonname) {
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errno = ENOENT;
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goto error;
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}
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if (strlen(canonname) >= IPA_HOST_NAME_LEN) {
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errno = ENAMETOOLONG;
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goto error;
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}
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#if 0
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/* refuse non-qualified short names and localhost */
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if ((strchr(canonname, '.') == NULL) ||
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(strcasecmp(canonname, "localhost.localdomain") == 0)) {
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errno = EINVAL;
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goto error;
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}
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#endif
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strcpy(fqdn, canonname);
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/* Make double sure it is terminated */
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fqdn[IPA_HOST_NAME_LEN - 1] = '\0';
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freeaddrinfo(ai);
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return 0;
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error:
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fqdn[0] = '\0';
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if (ai != NULL) {
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freeaddrinfo(ai);
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}
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return -1;
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}
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int ipa_gethostfqdn(char *name)
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{
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static char cached_fqdn[IPA_HOST_NAME_LEN] = {0};
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if (!cached_fqdn) {
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int res = _get_fqdn(cached_fqdn);
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if (res != 0) {
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return -1;
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}
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}
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strcpy(name, cached_fqdn);
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return 0;
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}
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