resolved: when there's already somebody listening on the LLMNR ports, simple disable...

This allows us to run resolved inside an nspawn container that shares
the network namespace with the host, if there's already an instance
running.

diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 1b6dc8a4a3a685c7de188a0113a3d4f609db9faf..5061d39c4630b6ac9f1994adc492e708182eef53 100644 (file)
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -392,6 +392,63 @@ static int manager_watch_hostname(Manager *m) {
         return 0;
 }
 
+static void manager_llmnr_stop(Manager *m) {
+        assert(m);
+
+        m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
+        m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
+
+        m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
+        m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
+
+        m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
+        m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
+
+        m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
+        m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
+}
+
+static int manager_llmnr_start(Manager *m) {
+        int r;
+
+        assert(m);
+
+        if (m->llmnr_support == SUPPORT_NO)
+                return 0;
+
+        r = manager_llmnr_ipv4_udp_fd(m);
+        if (r == -EADDRINUSE)
+                goto eaddrinuse;
+        if (r < 0)
+                return r;
+
+        r = manager_llmnr_ipv6_udp_fd(m);
+        if (r == -EADDRINUSE)
+                goto eaddrinuse;
+        if (r < 0)
+                return r;
+
+        r = manager_llmnr_ipv4_tcp_fd(m);
+        if (r == -EADDRINUSE)
+                goto eaddrinuse;
+        if (r < 0)
+                return r;
+
+        r = manager_llmnr_ipv6_tcp_fd(m);
+        if (r == -EADDRINUSE)
+                goto eaddrinuse;
+        if (r < 0)
+                return r;
+
+        return 0;
+
+eaddrinuse:
+        log_warning("There appears to be another LLMNR respondering running. Turning off LLMNR support.");
+        m->llmnr_support = SUPPORT_NO;
+        manager_llmnr_stop(m);
+        return 0;
+}
+
 int manager_new(Manager **ret) {
         _cleanup_(manager_freep) Manager *m = NULL;
         int r;
@@ -443,25 +500,24 @@ int manager_new(Manager **ret) {
         if (r < 0)
                 return r;
 
-        r = manager_llmnr_ipv4_udp_fd(m);
-        if (r < 0)
-                return r;
-        r = manager_llmnr_ipv6_udp_fd(m);
-        if (r < 0)
-                return r;
-        r = manager_llmnr_ipv4_tcp_fd(m);
-        if (r < 0)
-                return r;
-        r = manager_llmnr_ipv6_tcp_fd(m);
-        if (r < 0)
-                return r;
-
         *ret = m;
         m = NULL;
 
         return 0;
 }
 
+int manager_start(Manager *m) {
+        int r;
+
+        assert(m);
+
+        r = manager_llmnr_start(m);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
 Manager *manager_free(Manager *m) {
         Link *l;
 
@@ -492,15 +548,7 @@ Manager *manager_free(Manager *m) {
         safe_close(m->dns_ipv4_fd);
         safe_close(m->dns_ipv6_fd);
 
-        sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
-        sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
-        safe_close(m->llmnr_ipv4_udp_fd);
-        safe_close(m->llmnr_ipv6_udp_fd);
-
-        sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
-        sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
-        safe_close(m->llmnr_ipv4_tcp_fd);
-        safe_close(m->llmnr_ipv6_tcp_fd);
+        manager_llmnr_stop(m);
 
         sd_event_source_unref(m->bus_retry_event_source);
         sd_bus_unref(m->bus);

diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h
index 31d670da44e9804f301d6224e130c0e6abb76dff..1fd4be41a4459069bdc85be9de1ffe8533d78c84 100644 (file)
--- a/src/resolve/resolved-manager.h
+++ b/src/resolve/resolved-manager.h
@@ -114,6 +114,7 @@ struct Manager {
 int manager_new(Manager **ret);
 Manager* manager_free(Manager *m);
 
+int manager_start(Manager *m);
 int manager_read_resolv_conf(Manager *m);
 int manager_write_resolv_conf(Manager *m);
 

diff --git a/src/resolve/resolved.c b/src/resolve/resolved.c
index 900a36d8f062d633ac6351f16a5ae16596a03174..892bb51386d8f27b97323085f6002415db458c86 100644 (file)
--- a/src/resolve/resolved.c
+++ b/src/resolve/resolved.c
@@ -75,6 +75,12 @@ int main(int argc, char *argv[]) {
         if (r < 0)
                 log_warning("Failed to parse configuration file: %s", strerror(-r));
 
+        r = manager_start(m);
+        if (r < 0) {
+                log_error("Failed to start manager: %s", strerror(-r));
+                goto finish;
+        }
+
         /* Write finish default resolv.conf to avoid a dangling
          * symlink */
         r = manager_write_resolv_conf(m);