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authorLennart Poettering <lennart@poettering.net>2014-08-12 12:21:10 +0200
committerLennart Poettering <lennart@poettering.net>2014-08-12 13:02:27 +0200
commit87f5a19343acf8ba697acc5a62bdb1a2b8c9eda3 (patch)
treeb10e9c848f9b65d4840c574864fb92a09619910d /src/resolve
parentc2d6bd61ee77b59566116afe6e20513d19945ed4 (diff)
resolved: filter out duplicate DNS servers when writing resolv.conf
Diffstat (limited to 'src/resolve')
-rw-r--r--src/resolve/resolved-dns-server.c23
-rw-r--r--src/resolve/resolved-dns-server.h3
-rw-r--r--src/resolve/resolved-manager.c51
3 files changed, 67 insertions, 10 deletions
diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c
index 30d9c8b34e..043f6b637d 100644
--- a/src/resolve/resolved-dns-server.c
+++ b/src/resolve/resolved-dns-server.c
@@ -19,6 +19,8 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
+#include "siphash24.h"
+
#include "resolved-dns-server.h"
int dns_server_new(
@@ -97,3 +99,24 @@ DnsServer* dns_server_free(DnsServer *s) {
return NULL;
}
+
+unsigned long dns_server_hash_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]) {
+ const DnsServer *s = p;
+ uint64_t u;
+
+ siphash24((uint8_t*) &u, &s->address, FAMILY_ADDRESS_SIZE(s->family), hash_key);
+ u = u * hash_key[0] + u + s->family;
+
+ return u;
+}
+
+int dns_server_compare_func(const void *a, const void *b) {
+ const DnsServer *x = a, *y = b;
+
+ if (x->family < y->family)
+ return -1;
+ if (x->family > y->family)
+ return 1;
+
+ return memcmp(&x->address, &y->address, FAMILY_ADDRESS_SIZE(x->family));
+}
diff --git a/src/resolve/resolved-dns-server.h b/src/resolve/resolved-dns-server.h
index 8a9f5560d5..5178a6be7e 100644
--- a/src/resolve/resolved-dns-server.h
+++ b/src/resolve/resolved-dns-server.h
@@ -59,3 +59,6 @@ int dns_server_new(
const union in_addr_union *address);
DnsServer* dns_server_free(DnsServer *s);
+
+unsigned long dns_server_hash_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]);
+int dns_server_compare_func(const void *a, const void *b);
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 988aa6e3b1..6bb089451f 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -691,7 +691,7 @@ static void write_resolve_conf_server(DnsServer *s, FILE *f, unsigned *count) {
}
if (*count == MAXNS)
- fputs("# Too many DNS servers configured, the following entries may be ignored\n", f);
+ fputs("# Too many DNS servers configured, the following entries may be ignored.\n", f);
fprintf(f, "nameserver %s\n", t);
(*count) ++;
@@ -701,6 +701,7 @@ int manager_write_resolv_conf(Manager *m) {
static const char path[] = "/run/systemd/resolve/resolv.conf";
_cleanup_free_ char *temp_path = NULL;
_cleanup_fclose_ FILE *f = NULL;
+ _cleanup_set_free_ Set *dns = NULL;
unsigned count = 0;
DnsServer *s;
Iterator i;
@@ -712,6 +713,41 @@ int manager_write_resolv_conf(Manager *m) {
/* Read the system /etc/resolv.conf first */
manager_read_resolv_conf(m);
+ /* Add the full list to a set, to filter out duplicates */
+ dns = set_new(dns_server_hash_func, dns_server_compare_func);
+ if (!dns)
+ return -ENOMEM;
+
+ /* First add the system-wide servers */
+ LIST_FOREACH(servers, s, m->dns_servers) {
+ r = set_put(dns, s);
+ if (r == -EEXIST)
+ continue;
+ if (r < 0)
+ return r;
+ }
+
+ /* Then, add the per-link servers */
+ HASHMAP_FOREACH(l, m->links, i)
+ LIST_FOREACH(servers, s, l->dns_servers) {
+ r = set_put(dns, s);
+ if (r == -EEXIST)
+ continue;
+ if (r < 0)
+ return r;
+ }
+
+ /* If we found nothing, add the fallback servers */
+ if (set_isempty(dns)) {
+ LIST_FOREACH(servers, s, m->fallback_dns_servers) {
+ r = set_put(dns, s);
+ if (r == -EEXIST)
+ continue;
+ if (r < 0)
+ return r;
+ }
+ }
+
r = fopen_temporary(path, &f, &temp_path);
if (r < 0)
return r;
@@ -724,15 +760,10 @@ int manager_write_resolv_conf(Manager *m) {
"# resolv.conf(5) in a different way, replace the symlink by a\n"
"# static file or a different symlink.\n\n", f);
- LIST_FOREACH(servers, s, m->dns_servers)
- write_resolve_conf_server(s, f, &count);
-
- HASHMAP_FOREACH(l, m->links, i)
- LIST_FOREACH(servers, s, l->dns_servers)
- write_resolve_conf_server(s, f, &count);
-
- if (count == 0) {
- LIST_FOREACH(servers, s, m->fallback_dns_servers)
+ if (set_isempty(dns))
+ fputs("# No DNS servers known.\n", f);
+ else {
+ SET_FOREACH(s, dns, i)
write_resolve_conf_server(s, f, &count);
}