| /*** |
| This file is part of systemd. |
| |
| Copyright 2014 Tom Gundersen <teg@jklm.no> |
| |
| systemd is free software; you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, or |
| (at your option) any later version. |
| |
| systemd is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| ***/ |
| |
| #include <resolv.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-resolv-conf.h" |
| #include "string-util.h" |
| #include "strv.h" |
| |
| int manager_read_resolv_conf(Manager *m) { |
| _cleanup_fclose_ FILE *f = NULL; |
| struct stat st, own; |
| char line[LINE_MAX]; |
| usec_t t; |
| 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? */ |
| t = timespec_load(&st.st_mtim); |
| if (t == m->resolv_conf_mtime) |
| return 0; |
| |
| /* Is it symlinked to our own file? */ |
| if (stat("/run/systemd/resolve/resolv.conf", &own) >= 0 && |
| st.st_dev == own.st_dev && |
| st.st_ino == own.st_ino) |
| 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; |
| } |
| |
| 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; |
| |
| l = strstrip(line); |
| if (*l == '#' || *l == ';') |
| continue; |
| |
| a = first_word(l, "nameserver"); |
| if (a) { |
| r = manager_add_dns_server_by_string(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); |
| } |
| } |
| |
| m->resolv_conf_mtime = t; |
| |
| /* 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); |
| |
| 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); |
| |
| (void) dns_server_string(s); |
| |
| if (!s->server_string) { |
| log_warning("Our of memory, or invalid DNS address. Ignoring server."); |
| return; |
| } |
| |
| if (*count == MAXNS) |
| fputs("# Too many DNS servers configured, the following entries may be ignored.\n", f); |
| (*count) ++; |
| |
| fprintf(f, "nameserver %s\n", s->server_string); |
| } |
| |
| static void write_resolv_conf_search( |
| const char *domain, |
| FILE *f, |
| unsigned *count, |
| unsigned *length) { |
| |
| assert(domain); |
| assert(f); |
| assert(length); |
| |
| if (*count >= MAXDNSRCH || |
| *length + strlen(domain) > 256) { |
| if (*count == MAXDNSRCH) |
| fputs(" # Too many search domains configured, remaining ones ignored.", f); |
| if (*length <= 256) |
| fputs(" # Total length of all search domains is too long, remaining ones ignored.", f); |
| |
| return; |
| } |
| |
| (*length) += strlen(domain); |
| (*count) ++; |
| |
| fputc(' ', f); |
| fputs(domain, f); |
| } |
| |
| static int write_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) { |
| Iterator i; |
| |
| fputs("# This file is managed by systemd-resolved(8). Do not edit.\n#\n" |
| "# Third party programs must not access this file directly, but\n" |
| "# only through the symlink at /etc/resolv.conf. To manage\n" |
| "# resolv.conf(5) in a different way, replace the symlink by a\n" |
| "# static file or a different symlink.\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)) { |
| unsigned length = 0, count = 0; |
| char *domain; |
| |
| fputs("search", f); |
| ORDERED_SET_FOREACH(domain, domains, i) |
| write_resolv_conf_search(domain, f, &count, &length); |
| fputs("\n", 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 = NULL; |
| _cleanup_fclose_ FILE *f = NULL; |
| int r; |
| |
| assert(m); |
| |
| /* Read the system /etc/resolv.conf first */ |
| 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 r; |
| |
| r = manager_compile_search_domains(m, &domains); |
| if (r < 0) |
| return r; |
| |
| r = fopen_temporary_label(PRIVATE_RESOLV_CONF, PRIVATE_RESOLV_CONF, &f, &temp_path); |
| if (r < 0) |
| return r; |
| |
| fchmod(fileno(f), 0644); |
| |
| r = write_resolv_conf_contents(f, dns, domains); |
| if (r < 0) |
| goto fail; |
| |
| if (rename(temp_path, PRIVATE_RESOLV_CONF) < 0) { |
| r = -errno; |
| goto fail; |
| } |
| |
| return 0; |
| |
| fail: |
| (void) unlink(PRIVATE_RESOLV_CONF); |
| (void) unlink(temp_path); |
| return r; |
| } |