memcached plugin: Use hostname_g when reading localhost.

Previously, the code would use the value of the "Host" option or
"127.0.0.1" if that option was unset (plus special cases for UNIX
sockets and a legacy mode). Obviously, "127.0.0.1" is a bad default.

This patch emulates the behavior of the MySQL plugin: if the "Host"
option is unset or set to either "localhost" or "127.0.0.1", the global
hostname_g variable is used.

Fixes: #801
Supersedes: #894

diff --git a/src/memcached.c b/src/memcached.c
index e398dd9..02f4203 100644 (file)
--- a/src/memcached.c
+++ b/src/memcached.c
@@ -240,21 +240,24 @@ static int memcached_query_daemon (char *buffer, size_t buffer_size, memcached_t
 
 static void memcached_init_vl (value_list_t *vl, memcached_t const *st)
 {
+  char const *host = st->host;
+
+  /* Set vl->host to hostname_g, if:
+   * - Legacy mode is used.
+   * - "Socket" option is given (doc: "Host option is ignored").
+   * - "Host" option is not provided.
+   * - "Host" option is set to "localhost" or "127.0.0.1". */
+  if ((strcmp (st->name, "__legacy__") == 0)
+      || (st->socket != NULL)
+      || (st->host == NULL)
+      || (strcmp ("127.0.0.1", st->host) == 0)
+      || (strcmp ("localhost", st->host) == 0))
+    host = hostname_g;
+
   sstrncpy (vl->plugin, "memcached", sizeof (vl->plugin));
-  if (strcmp (st->name, "__legacy__") == 0) /* legacy mode */
-  {
-    sstrncpy (vl->host, hostname_g, sizeof (vl->host));
-  }
-  else
-  {
-    if (st->socket != NULL)
-      sstrncpy (vl->host, hostname_g, sizeof (vl->host));
-    else
-      sstrncpy (vl->host,
-          (st->host != NULL) ? st->host : MEMCACHED_DEF_HOST,
-          sizeof (vl->host));
+  sstrncpy (vl->host, host, sizeof (vl->host));
+  if (strcmp (st->name, "__legacy__") != 0)
     sstrncpy (vl->plugin_instance, st->name, sizeof (vl->plugin_instance));
-  }
 }
 
 static void submit_derive (const char *type, const char *type_inst,