Support additional connect parameters in PostgreSQL database wrapper (#6071)

Most notably this change enables you to specify whether or with what
priority a secure SSL TCP/IP connection will be negotiated with the
database server.

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Support additional connect parameters in PostgreSQL database wrapper
 - Use UI dialogs instead of confirm() and alert() where possible
 - Display value of the SMTP message size limit in the error message (#6032)
 - Skip redundant INSERT query on successful logon when using PHP7

program/lib/Roundcube/rcube_db_pgsql.php

@@ -28,6 +28,9 @@ class rcube_db_pgsql extends rcube_db
 {
     public $db_provider = 'postgres';
 
+    // See https://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-PARAMKEYWORDS
+    private static $libpq_connect_params = array("application_name", "sslmode", "sslcert", "sslkey", "sslrootcert", "sslcrl", "sslcompression", "service");
+
     /**
      * Object constructor
      *
@@ -256,6 +259,12 @@ class rcube_db_pgsql extends rcube_db
             $params[] = 'dbname=' . $dsn['database'];
         }
 
+        foreach (self::$libpq_connect_params as $param) {
+            if ($dsn[$param]) {
+                $params[] = $param . '=' . $dsn[$param];
+            }
+        }
+
         if (!empty($params)) {
             $result .= implode(';', $params);
         }