Use whitelist to pass valid connection parameters to PGConn.

All the valids parameters for libpq are used.

See http://www.postgresql.org/docs/9.1/static/libpq-connect.html for the
full list

Fixes #8784

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -17,22 +17,25 @@
 
 module ActiveRecord
   module ConnectionHandling
+    VALID_CONN_PARAMS = [:host, :hostaddr, :port, :dbname, :user, :password, :connect_timeout,
+                         :client_encoding, :options, :application_name, :fallback_application_name,
+                         :keepalives, :keepalives_idle, :keepalives_interval, :keepalives_count,
+                         :tty, :sslmode, :requiressl, :sslcert, :sslkey, :sslrootcert, :sslcrl,
+                         :requirepeer, :krbsrvname, :gsslib, :service]
+
     # Establishes a connection to the database that's used by all Active Record objects
     def postgresql_connection(config) # :nodoc:
       conn_params = config.symbolize_keys
 
-      # Forward any unused config params to PGconn.connect.
-      [:statement_limit, :encoding, :min_messages, :schema_search_path,
-       :schema_order, :adapter, :pool, :checkout_timeout, :template,
-       :prepared_statements, :reaping_frequency, :insert_returning, :variables].each do |key|
-        conn_params.delete key
-      end
-      conn_params.delete_if { |k,v| v.nil? }
+      conn_params.delete_if { |_, v| v.nil? }
 
       # Map ActiveRecords param names to PGs.
       conn_params[:user] = conn_params.delete(:username) if conn_params[:username]
       conn_params[:dbname] = conn_params.delete(:database) if conn_params[:database]
 
+      # Forward only valid config params to PGconn.connect.
+      conn_params.keep_if { |k, _| VALID_CONN_PARAMS.include?(k) }
+
       # The postgres drivers don't allow the creation of an unconnected PGconn object,
       # so just pass a nil connection object for the time being.
       ConnectionAdapters::PostgreSQLAdapter.new(nil, logger, conn_params, config)