[thirdparty/systemd.git] / src / resolve / resolved-resolv-conf.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  Copyright 2014 Tom Gundersen <teg@jklm.no>
 ***/

#include <resolv.h>
#include <stdio_ext.h>

#include "alloc-util.h"
#include "dns-domain.h"
#include "fd-util.h"
#include "fileio-label.h"
#include "fileio.h"
#include "ordered-set.h"
#include "resolved-conf.h"
#include "resolved-dns-server.h"
#include "resolved-resolv-conf.h"
#include "string-util.h"
#include "strv.h"

/* A resolv.conf file containing the DNS server and domain data we learnt from uplink, i.e. the full uplink data */
#define PRIVATE_UPLINK_RESOLV_CONF "/run/systemd/resolve/resolv.conf"

/* A resolv.conf file containing the domain data we learnt from uplink, but our own DNS server address. */
#define PRIVATE_STUB_RESOLV_CONF "/run/systemd/resolve/stub-resolv.conf"

/* A static resolv.conf file containing no domains, but only our own DNS sever address */
#define PRIVATE_STATIC_RESOLV_CONF ROOTLIBEXECDIR "/resolv.conf"

static bool file_is_our_own(const struct stat *st) {
        const char *path;

        assert(st);

        FOREACH_STRING(path,
                       PRIVATE_UPLINK_RESOLV_CONF,
                       PRIVATE_STUB_RESOLV_CONF,
                       PRIVATE_STATIC_RESOLV_CONF) {

                struct stat own;

                /* Is it symlinked to our own uplink file? */
                if (stat(path, &own) >= 0 &&
                    st->st_dev == own.st_dev &&
                    st->st_ino == own.st_ino)
                        return true;
        }

        return false;
}

int manager_read_resolv_conf(Manager *m) {
        _cleanup_fclose_ FILE *f = NULL;
        struct stat st;
        char line[LINE_MAX];
        unsigned n = 0;
        int r;

        assert(m);

        /* Reads the system /etc/resolv.conf, if it exists and is not
         * symlinked to our own resolv.conf instance */

        if (!m->read_resolv_conf)
                return 0;

        r = stat("/etc/resolv.conf", &st);
        if (r < 0) {
                if (errno == ENOENT)
                        return 0;

                r = log_warning_errno(errno, "Failed to stat /etc/resolv.conf: %m");
                goto clear;
        }

        /* Have we already seen the file? */
        if (timespec_load(&st.st_mtim) == m->resolv_conf_mtime)
                return 0;

        if (file_is_our_own(&st))
                return 0;

        f = fopen("/etc/resolv.conf", "re");
        if (!f) {
                if (errno == ENOENT)
                        return 0;

                r = log_warning_errno(errno, "Failed to open /etc/resolv.conf: %m");
                goto clear;
        }

        if (fstat(fileno(f), &st) < 0) {
                r = log_error_errno(errno, "Failed to stat open file: %m");
                goto clear;
        }

        if (file_is_our_own(&st))
                return 0;

        dns_server_mark_all(m->dns_servers);
        dns_search_domain_mark_all(m->search_domains);

        FOREACH_LINE(line, f, r = -errno; goto clear) {
                const char *a;
                char *l;

                n++;

                l = strstrip(line);
                if (IN_SET(*l, '#', ';', 0))
                        continue;

                a = first_word(l, "nameserver");
                if (a) {
                        r = manager_parse_dns_server_string_and_warn(m, DNS_SERVER_SYSTEM, a);
                        if (r < 0)
                                log_warning_errno(r, "Failed to parse DNS server address '%s', ignoring.", a);

                        continue;
                }

                a = first_word(l, "domain");
                if (!a) /* We treat "domain" lines, and "search" lines as equivalent, and add both to our list. */
                        a = first_word(l, "search");
                if (a) {
                        r = manager_parse_search_domains_and_warn(m, a);
                        if (r < 0)
                                log_warning_errno(r, "Failed to parse search domain string '%s', ignoring.", a);
                }

                log_syntax(NULL, LOG_DEBUG, "/etc/resolv.conf", n, 0, "Ignoring resolv.conf line: %s", l);
        }

        m->resolv_conf_mtime = timespec_load(&st.st_mtim);

        /* Flush out all servers and search domains that are still
         * marked. Those are then ones that didn't appear in the new
         * /etc/resolv.conf */
        dns_server_unlink_marked(m->dns_servers);
        dns_search_domain_unlink_marked(m->search_domains);

        /* Whenever /etc/resolv.conf changes, start using the first
         * DNS server of it. This is useful to deal with broken
         * network managing implementations (like NetworkManager),
         * that when connecting to a VPN place both the VPN DNS
         * servers and the local ones in /etc/resolv.conf. Without
         * resetting the DNS server to use back to the first entry we
         * will continue to use the local one thus being unable to
         * resolve VPN domains. */
        manager_set_dns_server(m, m->dns_servers);

        /* Unconditionally flush the cache when /etc/resolv.conf is
         * modified, even if the data it contained was completely
         * identical to the previous version we used. We do this
         * because altering /etc/resolv.conf is typically done when
         * the network configuration changes, and that should be
         * enough to flush the global unicast DNS cache. */
        if (m->unicast_scope)
                dns_cache_flush(&m->unicast_scope->cache);

        /* If /etc/resolv.conf changed, make sure to forget everything we learned about the DNS servers. After all we
         * might now talk to a very different DNS server that just happens to have the same IP address as an old one
         * (think 192.168.1.1). */
        dns_server_reset_features_all(m->dns_servers);

        return 0;

clear:
        dns_server_unlink_all(m->dns_servers);
        dns_search_domain_unlink_all(m->search_domains);
        return r;
}

static void write_resolv_conf_server(DnsServer *s, FILE *f, unsigned *count) {
        assert(s);
        assert(f);
        assert(count);

        if (!dns_server_string(s)) {
                log_warning("Out of memory, or invalid DNS address. Ignoring server.");
                return;
        }

        /* Check if the DNS server is limited to particular domains;
         * resolv.conf does not have a syntax to express that, so it must not
         * appear as a global name server to avoid routing unrelated domains to
         * it (which is a privacy violation, will most probably fail anyway,
         * and adds unnecessary load) */
        if (dns_server_limited_domains(s)) {
                log_debug("DNS server %s has route-only domains, not using as global name server", dns_server_string(s));
                return;
        }

        if (*count == MAXNS)
                fputs("# Too many DNS servers configured, the following entries may be ignored.\n", f);
        (*count)++;

        fprintf(f, "nameserver %s\n", dns_server_string(s));
}

static void write_resolv_conf_search(
                OrderedSet *domains,
                FILE *f) {
        unsigned length = 0, count = 0;
        Iterator i;
        char *domain;

        assert(domains);
        assert(f);

        fputs("search", f);

        ORDERED_SET_FOREACH(domain, domains, i) {
                if (++count > MAXDNSRCH) {
                        fputs("\n# Too many search domains configured, remaining ones ignored.", f);
                        break;
                }
                length += strlen(domain) + 1;
                if (length > 256) {
                        fputs("\n# Total length of all search domains is too long, remaining ones ignored.", f);
                        break;
                }
                fputc(' ', f);
                fputs(domain, f);
        }

        fputs("\n", f);
}

static int write_uplink_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
        Iterator i;

        fputs("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
              "#\n"
              "# This is a dynamic resolv.conf file for connecting local clients directly to\n"
              "# all known uplink DNS servers. This file lists all configured search domains.\n"
              "#\n"
              "# Third party programs must not access this file directly, but only through the\n"
              "# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,\n"
              "# replace this symlink by a static file or a different symlink.\n"
              "#\n"
              "# See man:systemd-resolved.service(8) for details about the supported modes of\n"
              "# operation for /etc/resolv.conf.\n"
              "\n", f);

        if (ordered_set_isempty(dns))
                fputs("# No DNS servers known.\n", f);
        else {
                unsigned count = 0;
                DnsServer *s;

                ORDERED_SET_FOREACH(s, dns, i)
                        write_resolv_conf_server(s, f, &count);
        }

        if (!ordered_set_isempty(domains))
                write_resolv_conf_search(domains, f);

        return fflush_and_check(f);
}

static int write_stub_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
        fputs_unlocked("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
                       "#\n"
                       "# This is a dynamic resolv.conf file for connecting local clients to the\n"
                       "# internal DNS stub resolver of systemd-resolved. This file lists all\n"
                       "# configured search domains.\n"
                       "#\n"
                       "# Run \"resolvectl status\" to see details about the uplink DNS servers\n"
                       "# currently in use.\n"
                       "#\n"
                       "# Third party programs must not access this file directly, but only through the\n"
                       "# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,\n"
                       "# replace this symlink by a static file or a different symlink.\n"
                       "#\n"
                       "# See man:systemd-resolved.service(8) for details about the supported modes of\n"
                       "# operation for /etc/resolv.conf.\n"
                       "\n"
                       "nameserver 127.0.0.53\n", f);

        if (!ordered_set_isempty(domains))
                write_resolv_conf_search(domains, f);

        return fflush_and_check(f);
}

int manager_write_resolv_conf(Manager *m) {

        _cleanup_ordered_set_free_ OrderedSet *dns = NULL, *domains = NULL;
        _cleanup_free_ char *temp_path_uplink = NULL, *temp_path_stub = NULL;
        _cleanup_fclose_ FILE *f_uplink = NULL, *f_stub = NULL;
        int r;

        assert(m);

        /* Read the system /etc/resolv.conf first */
        (void) manager_read_resolv_conf(m);

        /* Add the full list to a set, to filter out duplicates */
        r = manager_compile_dns_servers(m, &dns);
        if (r < 0)
                return log_warning_errno(r, "Failed to compile list of DNS servers: %m");

        r = manager_compile_search_domains(m, &domains, false);
        if (r < 0)
                return log_warning_errno(r, "Failed to compile list of search domains: %m");

        r = fopen_temporary_label(PRIVATE_UPLINK_RESOLV_CONF, PRIVATE_UPLINK_RESOLV_CONF, &f_uplink, &temp_path_uplink);
        if (r < 0)
                return log_warning_errno(r, "Failed to open private resolv.conf file for writing: %m");

        (void) __fsetlocking(f_uplink, FSETLOCKING_BYCALLER);
        (void) fchmod(fileno(f_uplink), 0644);

        r = fopen_temporary_label(PRIVATE_STUB_RESOLV_CONF, PRIVATE_STUB_RESOLV_CONF, &f_stub, &temp_path_stub);
        if (r < 0)
                return log_warning_errno(r, "Failed to open private stub-resolv.conf file for writing: %m");

        (void) __fsetlocking(f_stub, FSETLOCKING_BYCALLER);
        (void) fchmod(fileno(f_stub), 0644);

        r = write_uplink_resolv_conf_contents(f_uplink, dns, domains);
        if (r < 0) {
                log_error_errno(r, "Failed to write private resolv.conf contents: %m");
                goto fail;
        }

        if (rename(temp_path_uplink, PRIVATE_UPLINK_RESOLV_CONF) < 0) {
                r = log_error_errno(errno, "Failed to move private resolv.conf file into place: %m");
                goto fail;
        }

        r = write_stub_resolv_conf_contents(f_stub, dns, domains);
        if (r < 0) {
                log_error_errno(r, "Failed to write private stub-resolv.conf contents: %m");
                goto fail;
        }

        if (rename(temp_path_stub, PRIVATE_STUB_RESOLV_CONF) < 0) {
                r = log_error_errno(errno, "Failed to move private stub-resolv.conf file into place: %m");
                goto fail;
        }

        return 0;

fail:
        (void) unlink(PRIVATE_UPLINK_RESOLV_CONF);
        (void) unlink(temp_path_uplink);
        (void) unlink(PRIVATE_STUB_RESOLV_CONF);
        (void) unlink(temp_path_stub);

        return r;
}
Commit	Line	Data
53e1b683	1	/* SPDX-License-Identifier: LGPL-2.1+ */
f8dc7e34	2	/***
f8dc7e34	3	Copyright 2014 Tom Gundersen <teg@jklm.no>
f8dc7e34 LP	4	***/
	5
	6	#include <resolv.h>
0d536673	7	#include <stdio_ext.h>
f8dc7e34 LP	8
	9	#include "alloc-util.h"
	10	#include "dns-domain.h"
	11	#include "fd-util.h"
	12	#include "fileio-label.h"
	13	#include "fileio.h"
	14	#include "ordered-set.h"
	15	#include "resolved-conf.h"
59c0fd0e	16	#include "resolved-dns-server.h"
f8dc7e34 LP	17	#include "resolved-resolv-conf.h"
	18	#include "string-util.h"
	19	#include "strv.h"
	20
b6de578d	21	/* A resolv.conf file containing the DNS server and domain data we learnt from uplink, i.e. the full uplink data */
a50d7910	22	#define PRIVATE_UPLINK_RESOLV_CONF "/run/systemd/resolve/resolv.conf"
b6de578d LP	23
b6de578d LP	24	/* A resolv.conf file containing the domain data we learnt from uplink, but our own DNS server address. */
a50d7910 LP	25	#define PRIVATE_STUB_RESOLV_CONF "/run/systemd/resolve/stub-resolv.conf"
a50d7910 LP	26
b6de578d LP	27	/* A static resolv.conf file containing no domains, but only our own DNS sever address */
	28	#define PRIVATE_STATIC_RESOLV_CONF ROOTLIBEXECDIR "/resolv.conf"
	29
043d3928	30	static bool file_is_our_own(const struct stat *st) {
b6de578d	31	const char *path;
043d3928 LP	32
	33	assert(st);
	34
b6de578d LP	35	FOREACH_STRING(path,
	36	PRIVATE_UPLINK_RESOLV_CONF,
	37	PRIVATE_STUB_RESOLV_CONF,
	38	PRIVATE_STATIC_RESOLV_CONF) {
	39
	40	struct stat own;
	41
	42	/* Is it symlinked to our own uplink file? */
	43	if (stat(path, &own) >= 0 &&
	44	st->st_dev == own.st_dev &&
	45	st->st_ino == own.st_ino)
	46	return true;
	47	}
043d3928 LP	48
	49	return false;
	50	}
	51
f8dc7e34 LP	52	int manager_read_resolv_conf(Manager *m) {
f8dc7e34 LP	53	_cleanup_fclose_ FILE *f = NULL;
043d3928	54	struct stat st;
f8dc7e34	55	char line[LINE_MAX];
b351c300	56	unsigned n = 0;
f8dc7e34 LP	57	int r;
	58
	59	assert(m);
	60
	61	/* Reads the system /etc/resolv.conf, if it exists and is not
	62	* symlinked to our own resolv.conf instance */
	63
	64	if (!m->read_resolv_conf)
	65	return 0;
	66
	67	r = stat("/etc/resolv.conf", &st);
	68	if (r < 0) {
	69	if (errno == ENOENT)
bf7fabd6 LP	70	return 0;
	71
	72	r = log_warning_errno(errno, "Failed to stat /etc/resolv.conf: %m");
f8dc7e34 LP	73	goto clear;
	74	}
	75
	76	/* Have we already seen the file? */
ace68cd7	77	if (timespec_load(&st.st_mtim) == m->resolv_conf_mtime)
f8dc7e34 LP	78	return 0;
f8dc7e34 LP	79
043d3928	80	if (file_is_our_own(&st))
bf7fabd6	81	return 0;
f8dc7e34 LP	82
	83	f = fopen("/etc/resolv.conf", "re");
	84	if (!f) {
	85	if (errno == ENOENT)
bf7fabd6 LP	86	return 0;
	87
	88	r = log_warning_errno(errno, "Failed to open /etc/resolv.conf: %m");
f8dc7e34 LP	89	goto clear;
	90	}
	91
	92	if (fstat(fileno(f), &st) < 0) {
	93	r = log_error_errno(errno, "Failed to stat open file: %m");
	94	goto clear;
	95	}
	96
043d3928 LP	97	if (file_is_our_own(&st))
	98	return 0;
	99
4b95f179	100	dns_server_mark_all(m->dns_servers);
a51c1048	101	dns_search_domain_mark_all(m->search_domains);
f8dc7e34 LP	102
f8dc7e34 LP	103	FOREACH_LINE(line, f, r = -errno; goto clear) {
f8dc7e34 LP	104	const char *a;
	105	char *l;
	106
b351c300 LP	107	n++;
b351c300 LP	108
f8dc7e34	109	l = strstrip(line);
b351c300	110	if (IN_SET(*l, '#', ';', 0))
f8dc7e34 LP	111	continue;
	112
	113	a = first_word(l, "nameserver");
	114	if (a) {
2817157b	115	r = manager_parse_dns_server_string_and_warn(m, DNS_SERVER_SYSTEM, a);
f8dc7e34 LP	116	if (r < 0)
	117	log_warning_errno(r, "Failed to parse DNS server address '%s', ignoring.", a);
	118
	119	continue;
	120	}
a51c1048 LP	121
	122	a = first_word(l, "domain");
	123	if (!a) /* We treat "domain" lines, and "search" lines as equivalent, and add both to our list. */
	124	a = first_word(l, "search");
	125	if (a) {
	126	r = manager_parse_search_domains_and_warn(m, a);
	127	if (r < 0)
	128	log_warning_errno(r, "Failed to parse search domain string '%s', ignoring.", a);
	129	}
b351c300 LP	130
b351c300 LP	131	log_syntax(NULL, LOG_DEBUG, "/etc/resolv.conf", n, 0, "Ignoring resolv.conf line: %s", l);
f8dc7e34 LP	132	}
f8dc7e34 LP	133
ace68cd7	134	m->resolv_conf_mtime = timespec_load(&st.st_mtim);
bf7fabd6	135
a51c1048 LP	136	/* Flush out all servers and search domains that are still
	137	* marked. Those are then ones that didn't appear in the new
	138	* /etc/resolv.conf */
4b95f179	139	dns_server_unlink_marked(m->dns_servers);
a51c1048	140	dns_search_domain_unlink_marked(m->search_domains);
f8dc7e34 LP	141
	142	/* Whenever /etc/resolv.conf changes, start using the first
	143	* DNS server of it. This is useful to deal with broken
	144	* network managing implementations (like NetworkManager),
	145	* that when connecting to a VPN place both the VPN DNS
	146	* servers and the local ones in /etc/resolv.conf. Without
	147	* resetting the DNS server to use back to the first entry we
	148	* will continue to use the local one thus being unable to
	149	* resolve VPN domains. */
	150	manager_set_dns_server(m, m->dns_servers);
	151
452b4e32 LP	152	/* Unconditionally flush the cache when /etc/resolv.conf is
	153	* modified, even if the data it contained was completely
	154	* identical to the previous version we used. We do this
	155	* because altering /etc/resolv.conf is typically done when
	156	* the network configuration changes, and that should be
	157	* enough to flush the global unicast DNS cache. */
	158	if (m->unicast_scope)
	159	dns_cache_flush(&m->unicast_scope->cache);
	160
59c0fd0e LP	161	/* If /etc/resolv.conf changed, make sure to forget everything we learned about the DNS servers. After all we
	162	* might now talk to a very different DNS server that just happens to have the same IP address as an old one
	163	* (think 192.168.1.1). */
	164	dns_server_reset_features_all(m->dns_servers);
	165
f8dc7e34 LP	166	return 0;
	167
	168	clear:
4b95f179	169	dns_server_unlink_all(m->dns_servers);
a51c1048	170	dns_search_domain_unlink_all(m->search_domains);
f8dc7e34 LP	171	return r;
	172	}
	173
	174	static void write_resolv_conf_server(DnsServer s, FILE f, unsigned *count) {
f8dc7e34 LP	175	assert(s);
	176	assert(f);
	177	assert(count);
	178
2817157b	179	if (!dns_server_string(s)) {
be4bf266	180	log_warning("Out of memory, or invalid DNS address. Ignoring server.");
f8dc7e34 LP	181	return;
	182	}
	183
b9fe94ca MP	184	/* Check if the DNS server is limited to particular domains;
	185	* resolv.conf does not have a syntax to express that, so it must not
	186	* appear as a global name server to avoid routing unrelated domains to
	187	* it (which is a privacy violation, will most probably fail anyway,
	188	* and adds unnecessary load) */
	189	if (dns_server_limited_domains(s)) {
	190	log_debug("DNS server %s has route-only domains, not using as global name server", dns_server_string(s));
	191	return;
	192	}
	193
f8dc7e34	194	if (*count == MAXNS)
0d536673	195	fputs("# Too many DNS servers configured, the following entries may be ignored.\n", f);
313cefa1	196	(*count)++;
f8dc7e34	197
2817157b	198	fprintf(f, "nameserver %s\n", dns_server_string(s));
f8dc7e34 LP	199	}
	200
	201	static void write_resolv_conf_search(
d2bc1251 MP	202	OrderedSet *domains,
	203	FILE *f) {
	204	unsigned length = 0, count = 0;
	205	Iterator i;
	206	char *domain;
f8dc7e34	207
d2bc1251	208	assert(domains);
f8dc7e34	209	assert(f);
f8dc7e34	210
0d536673	211	fputs("search", f);
f8dc7e34	212
d2bc1251 MP	213	ORDERED_SET_FOREACH(domain, domains, i) {
d2bc1251 MP	214	if (++count > MAXDNSRCH) {
0d536673	215	fputs("\n# Too many search domains configured, remaining ones ignored.", f);
d2bc1251 MP	216	break;
	217	}
	218	length += strlen(domain) + 1;
	219	if (length > 256) {
0d536673	220	fputs("\n# Total length of all search domains is too long, remaining ones ignored.", f);
d2bc1251 MP	221	break;
d2bc1251 MP	222	}
0d536673 LP	223	fputc(' ', f);
0d536673 LP	224	fputs(domain, f);
f8dc7e34 LP	225	}
f8dc7e34 LP	226
0d536673	227	fputs("\n", f);
f8dc7e34 LP	228	}
f8dc7e34 LP	229
e6b2d948	230	static int write_uplink_resolv_conf_contents(FILE f, OrderedSet dns, OrderedSet *domains) {
f8dc7e34 LP	231	Iterator i;
f8dc7e34 LP	232
0d536673 LP	233	fputs("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
	234	"#\n"
	235	"# This is a dynamic resolv.conf file for connecting local clients directly to\n"
	236	"# all known uplink DNS servers. This file lists all configured search domains.\n"
	237	"#\n"
	238	"# Third party programs must not access this file directly, but only through the\n"
	239	"# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,\n"
	240	"# replace this symlink by a static file or a different symlink.\n"
	241	"#\n"
	242	"# See man:systemd-resolved.service(8) for details about the supported modes of\n"
	243	"# operation for /etc/resolv.conf.\n"
	244	"\n", f);
f8dc7e34 LP	245
f8dc7e34 LP	246	if (ordered_set_isempty(dns))
0d536673	247	fputs("# No DNS servers known.\n", f);
f8dc7e34 LP	248	else {
	249	unsigned count = 0;
	250	DnsServer *s;
	251
	252	ORDERED_SET_FOREACH(s, dns, i)
	253	write_resolv_conf_server(s, f, &count);
	254	}
	255
d2bc1251 MP	256	if (!ordered_set_isempty(domains))
d2bc1251 MP	257	write_resolv_conf_search(domains, f);
f8dc7e34 LP	258
	259	return fflush_and_check(f);
	260	}
	261
e6b2d948	262	static int write_stub_resolv_conf_contents(FILE f, OrderedSet dns, OrderedSet *domains) {
d937ef74 LP	263	fputs_unlocked("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
	264	"#\n"
	265	"# This is a dynamic resolv.conf file for connecting local clients to the\n"
	266	"# internal DNS stub resolver of systemd-resolved. This file lists all\n"
	267	"# configured search domains.\n"
	268	"#\n"
5bc53fee	269	"# Run \"resolvectl status\" to see details about the uplink DNS servers\n"
d937ef74 LP	270	"# currently in use.\n"
	271	"#\n"
	272	"# Third party programs must not access this file directly, but only through the\n"
	273	"# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,\n"
	274	"# replace this symlink by a static file or a different symlink.\n"
	275	"#\n"
	276	"# See man:systemd-resolved.service(8) for details about the supported modes of\n"
	277	"# operation for /etc/resolv.conf.\n"
	278	"\n"
	279	"nameserver 127.0.0.53\n", f);
e6b2d948 DJL	280
	281	if (!ordered_set_isempty(domains))
	282	write_resolv_conf_search(domains, f);
	283
	284	return fflush_and_check(f);
	285	}
	286
f8dc7e34	287	int manager_write_resolv_conf(Manager *m) {
9176a57c	288
9176a57c	289	_cleanup_ordered_set_free_ OrderedSet dns = NULL, domains = NULL;
0d536673 LP	290	_cleanup_free_ char temp_path_uplink = NULL, temp_path_stub = NULL;
0d536673 LP	291	_cleanup_fclose_ FILE f_uplink = NULL, f_stub = NULL;
f8dc7e34 LP	292	int r;
	293
	294	assert(m);
	295
	296	/* Read the system /etc/resolv.conf first */
7207052d	297	(void) manager_read_resolv_conf(m);
f8dc7e34 LP	298
f8dc7e34 LP	299	/* Add the full list to a set, to filter out duplicates */
9176a57c LP	300	r = manager_compile_dns_servers(m, &dns);
9176a57c LP	301	if (r < 0)
7207052d	302	return log_warning_errno(r, "Failed to compile list of DNS servers: %m");
f8dc7e34	303
6f7da49d	304	r = manager_compile_search_domains(m, &domains, false);
9176a57c	305	if (r < 0)
7207052d	306	return log_warning_errno(r, "Failed to compile list of search domains: %m");
f8dc7e34	307
e6b2d948	308	r = fopen_temporary_label(PRIVATE_UPLINK_RESOLV_CONF, PRIVATE_UPLINK_RESOLV_CONF, &f_uplink, &temp_path_uplink);
f8dc7e34	309	if (r < 0)
7207052d	310	return log_warning_errno(r, "Failed to open private resolv.conf file for writing: %m");
0d536673 LP	311
	312	(void) __fsetlocking(f_uplink, FSETLOCKING_BYCALLER);
	313	(void) fchmod(fileno(f_uplink), 0644);
	314
e6b2d948 DJL	315	r = fopen_temporary_label(PRIVATE_STUB_RESOLV_CONF, PRIVATE_STUB_RESOLV_CONF, &f_stub, &temp_path_stub);
	316	if (r < 0)
	317	return log_warning_errno(r, "Failed to open private stub-resolv.conf file for writing: %m");
0d536673 LP	318
0d536673 LP	319	(void) __fsetlocking(f_stub, FSETLOCKING_BYCALLER);
e6b2d948	320	(void) fchmod(fileno(f_stub), 0644);
f8dc7e34	321
e6b2d948	322	r = write_uplink_resolv_conf_contents(f_uplink, dns, domains);
7207052d LP	323	if (r < 0) {
7207052d LP	324	log_error_errno(r, "Failed to write private resolv.conf contents: %m");
f8dc7e34	325	goto fail;
7207052d	326	}
f8dc7e34	327
e6b2d948	328	if (rename(temp_path_uplink, PRIVATE_UPLINK_RESOLV_CONF) < 0) {
7207052d	329	r = log_error_errno(errno, "Failed to move private resolv.conf file into place: %m");
f8dc7e34 LP	330	goto fail;
	331	}
	332
e6b2d948 DJL	333	r = write_stub_resolv_conf_contents(f_stub, dns, domains);
	334	if (r < 0) {
	335	log_error_errno(r, "Failed to write private stub-resolv.conf contents: %m");
	336	goto fail;
	337	}
	338
	339	if (rename(temp_path_stub, PRIVATE_STUB_RESOLV_CONF) < 0) {
	340	r = log_error_errno(errno, "Failed to move private stub-resolv.conf file into place: %m");
	341	goto fail;
	342	}
	343
f8dc7e34 LP	344	return 0;
	345
	346	fail:
e6b2d948 DJL	347	(void) unlink(PRIVATE_UPLINK_RESOLV_CONF);
	348	(void) unlink(temp_path_uplink);
	349	(void) unlink(PRIVATE_STUB_RESOLV_CONF);
	350	(void) unlink(temp_path_stub);
7207052d	351
f8dc7e34 LP	352	return r;
f8dc7e34 LP	353	}