Let snmp_synch_response deal with PDU freeing

When reading from tables, upon errors the PDUs sent are already
freed by snmp_synch_response since they are right after
snmp_send is called.

This commit syncs collectd's approach with other occurences of
snmp_synch_response calls.

There might be a few corner cases where we leak PDUs, but it
is unclear how to check for those since we would need to
have an indication that snmp_send was never called, which
as far as I can tell is not possible.

The potential for failure in snmp_send is rather low and will
be easily spotted though, since when crafting invalid PDUs
snmp send will constantly fail and since valid configurations
can never leak memory.

This fixes #804

diff --git a/src/snmp.c b/src/snmp.c
index 7d6e0a1..6466503 100644 (file)
--- a/src/snmp.c
+++ b/src/snmp.c
@@ -1618,8 +1618,9 @@ static int csnmp_read_table (host_definition_t *host, data_definition_t *data)
     snmp_free_pdu (res);
   res = NULL;
 
-  if (req != NULL)
-    snmp_free_pdu (req);
+  /*
+   * memory is handled by snmp_synch_response
+   */
   req = NULL;
 
   if (status == 0)