proto_ws Module

OpenSIPS Project

Edited by

Razvan Crainea

   Copyright © 2015 OpenSIPS Project
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Dependencies

              1.2.1. OpenSIPS Modules
              1.2.2. External Libraries or Applications

        1.3. Exported Parameters

              1.3.1. ws_port (integer)
              1.3.2. ws_send_timeout (integer)
              1.3.3. ws_max_msg_chunks (integer)
              1.3.4. trace_destination (string)
              1.3.5. trace_on (int)
              1.3.6. trace_filter_route (string)

        1.4. Exported MI Functions

              1.4.1. ws_trace

   2. Frequently Asked Questions

   List of Examples

   1.1. Set ws_port parameter
   1.2. Set ws_send_timeout parameter
   1.3. Set ws_max_msg_chunks parameter
   1.4. Set trace_destination parameter
   1.5. Set trace_on parameter
   1.6. Set trace_filter_route parameter

Chapter 1. Admin Guide

1.1. Overview

   The WebSocket protocol (RFC 6455) provides an end-to-end
   full-duplex communication channel between two web-based
   applications. This allows WebSocket enabled browsers to connect
   to a WebSocket server and exchange any type of data. RFC 7118
   provides the specifications for transporting SIP messages over
   the WebSocket protocol.

   The proto_ws module is transport module that provides
   communication over the WebSocket protocol. This module is fully
   compliant with the RFC 7118, thus allowing browsers to act as
   SIP clients for the OpenSIPS proxy.

   The current implementation acts both as WebSocket server and
   client, thus it can accept connections from WebSocket clients
   and can also initiate connections to another WebSocket server.
   After the connection is established, messages can flow in both
   directions.

   OpenSIPS supports the following WebSocket operations:
     * text and binary - can both send and receive WebSocket
       messages that contain text or binary body
     * close - messages used to safely close the WebSocket
       communication using a 2-messages handshake
     * ping - responds with pong messages. There is no mechanism
       to trigger ping messages.
     * pong - sent when a ping message is received. OpenSIPS,
       absorbes the pong messages received.

   Once loaded, you will be able to define WebSocket listeners in
   your script. To add a listener, you have to add its IP, and
   optionally the listening port, after the mpath parameter,
   similar to this example:

...
mpath=/path/to/modules
...
listen=ws:127.0.0.1             # change with the listening IP
listen=ws:127.0.0.1:5060        # change with the listening IP and port
...

1.2. Dependencies

1.2.1. OpenSIPS Modules

   The following modules must be loaded before this module:
     * None.

1.2.2. External Libraries or Applications

   The following libraries or applications must be installed
   before running OpenSIPS with this module loaded:
     * None.

1.3. Exported Parameters

1.3.1. ws_port (integer)

   The default port to be used for all WS related operation. Be
   careful as the default port impacts both the SIP listening part
   (if no port is defined in the WS listeners) and the SIP sending
   part (if the destination WS URI has no explicit port).

   If you want to change only the listening port for WS, use the
   port option in the SIP listener defintion.

   Default value is 80.

   Example 1.1. Set ws_port parameter
...
modparam("proto_ws", "ws_port", 8080)
...

1.3.2. ws_send_timeout (integer)

   Time in milliseconds after a WebSocket connection will be
   closed if it is not available for blocking writing in this
   interval (and OpenSIPS wants to send something on it).

   Default value is 100 ms.

   Example 1.2. Set ws_send_timeout parameter
...
modparam("proto_ws", "ws_send_timeout", 200)
...

1.3.3. ws_max_msg_chunks (integer)

   The maximum number of chunks in which a SIP message is expected
   to arrive via WebSocket. If a received packet is more
   fragmented than this, the connection is dropped (either the
   connection is very overloaded and this leads to high
   fragmentation - or we are the victim of an ongoing attack where
   the attacker is sending very fragmented traffic in order to
   decrease server performance).

   Default value is 4.

   Example 1.3. Set ws_max_msg_chunks parameter
...
modparam("proto_ws", "ws_max_msg_chunks", 8)
...

1.3.4. trace_destination (string)

   Trace destination as defined in the tracing module. Currently
   the only tracing module is proto_hep. Network events such as
   connect, accept and connection closed events shall be traced
   along with errors that could appear in the process. For each
   connection that is created an event containing information
   about http request and reply belonging to web socket protocol
   handshake and network layer information shall be sent.

   WARNING: A tracing module must be loaded in order for this
   parameter to work. (for example proto_hep).

   Default value is none(not defined).

   Example 1.4. Set trace_destination parameter
...
modparam("proto_hep", "trace_destination", "[hep_dest]10.0.0.2;transport
=tcp;version=3")

modparam("proto_ws", "trace_destination", "hep_dest")
...

1.3.5. trace_on (int)

   This controls whether tracing for ws is on or not. You still
   need to define Section 1.3.4, “trace_destination (string)”in
   order to work, but this value will be controlled using mi
   function Section 1.4.1, “ ws_trace ”.
   Default value is 0(tracing inactive).

   Example 1.5. Set trace_on parameter
...
modparam("proto_ws", "trace_on", 1)
...

1.3.6. trace_filter_route (string)

   Define the name of a route in which you can filter which
   connections will be trace and which connections won't be. In
   this route you will have information regarding source and
   destination ips and ports for the current connection. To
   disable tracing for a specific connection the last call in this
   route must be drop, any other exit mode resulting in tracing
   the current connection ( of course you still have to define a
   Section 1.3.4, “trace_destination (string)” and trace must be
   on at the time this connection is opened.

   IMPORTANT Filtering on ip addresses and ports can be made using
   $si and $sp for matching either the entity that is connecting
   to OpenSIPS or the entity to which OpenSIPS is connecting. The
   name might be misleading ( $si meaning the source ip if you
   read the docs) but in reality it is simply the socket other
   than the OpenSIPS socket. In order to match OpenSIPS interface
   (either the one that accepted the connection or the one that
   initiated a connection) $Ri (ip) and $Rp (port) can be used.

   WARNING: IF Section 1.3.5, “trace_on (int)” is set to 0 or
   tracing is deactived via the mi command Section 1.4.1, “
   ws_trace ” this route won't be called.
   Default value is none(no route is set).

   Example 1.6. Set trace_filter_route parameter
...
modparam("proto_ws", "trace_filter_route", "ws_filter")
...
/* all ws connections will go through this route if tracing is activated
 * and a trace destination is defined */
route[ws_filter] {
        ...
        /* all connections opened from/by ip 1.1.1.1:8000 will be traced
           on interface 1.1.1.10:5060(opensips listener)
           all the other connections won't be */
         if ( $si == "1.1.1.1" && $sp == 8000 &&
                $Ri == "1.1.1.10"  && $Rp == 5060)
                exit;
        else
                drop;
}
...

1.4. Exported MI Functions

1.4.1.  ws_trace

   Name: ws_trace

   Parameters:
     * trace_mode(optional): set ws tracing on and off. This
       parameter can be missing and the command will show the
       current tracing status for this module( on or off );
       Possible values:
          + on
          + off

   MI FIFO Command Format:
                        :ws_trace:_reply_fifo_file_
                        trace_mode
                        _empty_line_

Chapter 2. Frequently Asked Questions

   2.1.

   Can OpenSIPS act as a WebSocket client?

   Yes, starting with OpenSIPS 2.2, it can act as a WebSocket
   client.

   2.2.

   Does OpenSIPS support WebSocket message fragmentation?

   No, WebSocket fragmentation mechanism is not supported.
