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resolved: split out function to determine the local llmnr hostname

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This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2021-03-26 14:08:03 +01:00
parent 20e994b392
commit 75c9d6b5cf
4 changed files with 99 additions and 64 deletions
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2
src/resolve/meson.build
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@ -13,6 +13,8 @@ basic_dns_sources = files('''
resolved-dns-answer.h
resolved-dns-question.c
resolved-dns-question.h
resolved-util.c
resolved-util.h
dns-type.c
dns-type.h
'''.split())

73
src/resolve/resolved-manager.c
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@ -33,6 +33,7 @@
#include "resolved-manager.h"
#include "resolved-mdns.h"
#include "resolved-resolv-conf.h"
#include "resolved-util.h"
#include "resolved-varlink.h"
#include "socket-util.h"
#include "string-table.h"
@ -362,75 +363,17 @@ static int manager_clock_change_listen(Manager *m) {
return 0;
}
static int determine_hostname(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
static int determine_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
_cleanup_free_ char *h = NULL, *n = NULL;
#if HAVE_LIBIDN2
_cleanup_free_ char *utf8 = NULL;
#elif HAVE_LIBIDN
int k;
#endif
char label[DNS_LABEL_MAX];
const char *p, *decoded;
int r;
assert(full_hostname);
assert(llmnr_hostname);
assert(mdns_hostname);
/* Extract and normalize the first label of the locally configured hostname, and check it's not "localhost". */
r = gethostname_strict(&h);
r = resolve_system_hostname(&h, &n);
if (r < 0)
return log_debug_errno(r, "Can't determine system hostname: %m");
p = h;
r = dns_label_unescape(&p, label, sizeof label, 0);
if (r < 0)
return log_error_errno(r, "Failed to unescape hostname: %m");
if (r == 0)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Couldn't find a single label in hostname.");
#if HAVE_LIBIDN || HAVE_LIBIDN2
r = dlopen_idn();
if (r < 0) {
log_debug_errno(r, "Failed to initialize IDN support, ignoring: %m");
decoded = label; /* no decoding */
} else
#endif
{
#if HAVE_LIBIDN2
r = sym_idn2_to_unicode_8z8z(label, &utf8, 0);
if (r != IDN2_OK)
return log_error_errno(SYNTHETIC_ERRNO(EUCLEAN),
"Failed to undo IDNA: %s", sym_idn2_strerror(r));
assert(utf8_is_valid(utf8));
r = strlen(utf8);
decoded = utf8;
#elif HAVE_LIBIDN
k = dns_label_undo_idna(label, r, label, sizeof label);
if (k < 0)
return log_error_errno(k, "Failed to undo IDNA: %m");
if (k > 0)
r = k;
if (!utf8_is_valid(label))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"System hostname is not UTF-8 clean.");
decoded = label;
#else
decoded = label; /* no decoding */
#endif
}
r = dns_label_escape_new(decoded, r, &n);
if (r < 0)
return log_error_errno(r, "Failed to escape hostname: %m");
if (is_localhost(n))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"System hostname is 'localhost', ignoring.");
return r;
r = dns_name_concat(n, "local", 0, mdns_hostname);
if (r < 0)
@ -501,9 +444,11 @@ static int on_hostname_change(sd_event_source *es, int fd, uint32_t revents, voi
assert(m);
r = determine_hostname(&full_hostname, &llmnr_hostname, &mdns_hostname);
if (r < 0)
r = determine_hostnames(&full_hostname, &llmnr_hostname, &mdns_hostname);
if (r < 0) {
log_warning_errno(r, "Failed to determine the local hostname and LLMNR/mDNS names, ignoring: %m");
return 0; /* ignore invalid hostnames */
}
llmnr_hostname_changed = !streq(llmnr_hostname, m->llmnr_hostname);
if (streq(full_hostname, m->full_hostname) &&
@ -546,7 +491,7 @@ static int manager_watch_hostname(Manager *m) {
(void) sd_event_source_set_description(m->hostname_event_source, "hostname");
r = determine_hostname(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
r = determine_hostnames(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
if (r < 0) {
_cleanup_free_ char *d = NULL;

84
src/resolve/resolved-util.c Normal file
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@ -0,0 +1,84 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "dns-def.h"
#include "dns-domain.h"
#include "hostname-util.h"
#include "idn-util.h"
#include "resolved-util.h"
#include "utf8.h"
int resolve_system_hostname(char **full_hostname, char **first_label) {
_cleanup_free_ char *h = NULL, *n = NULL;
#if HAVE_LIBIDN2
_cleanup_free_ char *utf8 = NULL;
#elif HAVE_LIBIDN
int k;
#endif
char label[DNS_LABEL_MAX];
const char *p, *decoded;
int r;
/* Return the full hostname in *full_hostname, if nonnull.
*
* Extract and normalize the first label of the locally configured hostname, check it's not
* "localhost", and return it in *first_label, if nonnull. */
r = gethostname_strict(&h);
if (r < 0)
return log_debug_errno(r, "Can't determine system hostname: %m");
p = h;
r = dns_label_unescape(&p, label, sizeof label, 0);
if (r < 0)
return log_debug_errno(r, "Failed to unescape hostname: %m");
if (r == 0)
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"Couldn't find a single label in hostname.");
#if HAVE_LIBIDN || HAVE_LIBIDN2
r = dlopen_idn();
if (r < 0) {
log_debug_errno(r, "Failed to initialize IDN support, ignoring: %m");
decoded = label; /* no decoding */
} else
#endif
{
#if HAVE_LIBIDN2
r = sym_idn2_to_unicode_8z8z(label, &utf8, 0);
if (r != IDN2_OK)
return log_debug_errno(SYNTHETIC_ERRNO(EUCLEAN),
"Failed to undo IDNA: %s", sym_idn2_strerror(r));
assert(utf8_is_valid(utf8));
r = strlen(utf8);
decoded = utf8;
#elif HAVE_LIBIDN
k = dns_label_undo_idna(label, r, label, sizeof label);
if (k < 0)
return log_debug_errno(k, "Failed to undo IDNA: %m");
if (k > 0)
r = k;
if (!utf8_is_valid(label))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"System hostname is not UTF-8 clean.");
decoded = label;
#else
decoded = label; /* no decoding */
#endif
}
r = dns_label_escape_new(decoded, r, &n);
if (r < 0)
return log_debug_errno(r, "Failed to escape hostname: %m");
if (is_localhost(n))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"System hostname is 'localhost', ignoring.");
if (full_hostname)
*full_hostname = TAKE_PTR(h);
if (first_label)
*first_label = TAKE_PTR(n);
return 0;
}

4
src/resolve/resolved-util.h Normal file
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@ -0,0 +1,4 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
int resolve_system_hostname(char **full_hostname, char **first_label);