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(PRIVATE_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 (IN_SET(*l, '#', ';'))
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);
}
}
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);
/* 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;
}
void link_allocate_scopes(Link *l) {
bool unicast_relevant;
int r;
assert(l);
/* If a link that used to be relevant is no longer, or a link that did not use to be relevant now becomes
* relevant, let's reinit the learnt global DNS server information, since we might talk to different servers
* now, even if they have the same addresses as before. */
unicast_relevant = link_relevant(l, AF_UNSPEC, false);
if (unicast_relevant != l->unicast_relevant) {
l->unicast_relevant = unicast_relevant;
dns_server_reset_features_all(l->manager->fallback_dns_servers);
dns_server_reset_features_all(l->manager->dns_servers);
}
/* And now, allocate all scopes that makes sense now if we didn't have them yet, and drop those which we don't
* need anymore */
if (unicast_relevant && l->dns_servers) {
if (!l->unicast_scope) {
dns_server_reset_features_all(l->dns_servers);
r = dns_scope_new(l->manager, &l->unicast_scope, l, DNS_PROTOCOL_DNS, AF_UNSPEC);
if (r < 0)
log_warning_errno(r, "Failed to allocate DNS scope: %m");
}
} else
l->unicast_scope = dns_scope_free(l->unicast_scope);
if (link_relevant(l, AF_INET, true) &&
l->llmnr_support != RESOLVE_SUPPORT_NO &&
l->manager->llmnr_support != RESOLVE_SUPPORT_NO) {
if (!l->llmnr_ipv4_scope) {
r = dns_scope_new(l->manager, &l->llmnr_ipv4_scope, l, DNS_PROTOCOL_LLMNR, AF_INET);
if (r < 0)
log_warning_errno(r, "Failed to allocate LLMNR IPv4 scope: %m");
}
} else
l->llmnr_ipv4_scope = dns_scope_free(l->llmnr_ipv4_scope);
if (link_relevant(l, AF_INET6, true) &&
l->llmnr_support != RESOLVE_SUPPORT_NO &&
l->manager->llmnr_support != RESOLVE_SUPPORT_NO &&
socket_ipv6_is_supported()) {
if (!l->llmnr_ipv6_scope) {
r = dns_scope_new(l->manager, &l->llmnr_ipv6_scope, l, DNS_PROTOCOL_LLMNR, AF_INET6);
if (r < 0)
log_warning_errno(r, "Failed to allocate LLMNR IPv6 scope: %m");
}
} else
l->llmnr_ipv6_scope = dns_scope_free(l->llmnr_ipv6_scope);
if (link_relevant(l, AF_INET, true) &&
l->mdns_support != RESOLVE_SUPPORT_NO &&
l->manager->mdns_support != RESOLVE_SUPPORT_NO) {
if (!l->mdns_ipv4_scope) {
r = dns_scope_new(l->manager, &l->mdns_ipv4_scope, l, DNS_PROTOCOL_MDNS, AF_INET);
if (r < 0)
log_warning_errno(r, "Failed to allocate mDNS IPv4 scope: %m");
}
} else
l->mdns_ipv4_scope = dns_scope_free(l->mdns_ipv4_scope);
if (link_relevant(l, AF_INET6, true) &&
l->mdns_support != RESOLVE_SUPPORT_NO &&
l->manager->mdns_support != RESOLVE_SUPPORT_NO) {
if (!l->mdns_ipv6_scope) {
r = dns_scope_new(l->manager, &l->mdns_ipv6_scope, l, DNS_PROTOCOL_MDNS, AF_INET6);
if (r < 0)
log_warning_errno(r, "Failed to allocate mDNS IPv6 scope: %m");
}
} else
l->mdns_ipv6_scope = dns_scope_free(l->mdns_ipv6_scope);
}
