JSONRPC-S (jsonrpc server) Module

Daniel-Constantin Mierla

Edited by

Daniel-Constantin Mierla


Table of Contents

1. Admin Guide
1. Overview
2. Limitations
3. Dependencies
3.1. Kamailio Modules
3.2. External Libraries or Applications
4. Parameters
4.1. pretty_format (int)
4.2. transport (int)
4.3. fifo_name (str)
4.4. fifo_mode (int)
4.5. fifo_group (int or str)
4.6. fifo_user (int or str)
4.7. fifo_reply_dir (str)
4.8. dgram_socket (str)
4.9. dgram_workers (str)
4.10. dgram_mode (int)
4.11. dgram_group (int) dgram_group (str)
4.12. dgram_user (int) dgram_group (str)
4.13. dgram_timeout (int)
5. Functions
5.1. jsonrpc_dispatch()
5.2. jsonrpc_exec(cmd)
6. JSONRPC Commands
7. JSONRPC Transports
7.1. JSONRPC Over HTTP
7.2. JSONRPC Over FIFO
7.3. JSONRPC Over DATAGRAM

List of Examples

1.1. Set pretty_format parameter
1.2. Set transport parameter
1.3. Set fifo_name parameter
1.4. Set fifo_mode parameter
1.5. Set fifo_group parameter
1.6. Set fifo_user parameter
1.7. Set fifo_reply_dir parameter
1.8. Set dgram_socket parameter
1.9. Set dgram_workers parameter
1.10. Set dgram_mode parameter
1.11. Set dgram_group parameter
1.12. Set dgram_user parameter
1.13. Set dgram_timeout parameter
1.14. jsonrpc_dispatch usage
1.15. jsonrpc_exec usage
1.16. JSONRPC Commands - Examples
1.17. JSONRPC Over Fifo Command
1.18. JSONRPC Over Fifo Command From Termina

Chapter 1. Admin Guide

1. Overview

This module provides a JSON-RPC v2 server over HTTP implementation, tailored for the needs of Kamailio. It implements the Kamailio RPC interface over JSON-RPC.

The specification for JSON-RPC is available at: http://www.jsonrpc.org/specification.

The JSONRPC-S module uses the xHTTP module to handle HTTP/S requests. Read the documentation of the xHTTP module for more details.

2. Limitations

  • This module does not implement asynchronous RPC commands. It is unlikely that asynchronous RPC commands will be executed from an JSON-RPC over HTTP client.

  • This module does not accept parameters embedded in a structure (see the RPC documentation for more info about how parameters can be passed to RPC).

3. Dependencies

3.1. Kamailio Modules

The following modules must be loaded before this module:

  • xhttp - xHTTP (optional, required when http transport is wanted).

3.2. External Libraries or Applications

The following libraries or applications must be installed before running Kamailio with this module loaded:

  • None

4. Parameters

4.1. pretty_format (int)

Pretty format for JSON-RPC response document.

Default value is '0'.

Example 1.1. Set pretty_format parameter

...
modparam("jsonrpcs", "pretty_format", 1)
...

4.2. transport (int)

Control what transports are enabled. The value can be:

  • 0 - all transports that can be enabled. For http, the xhttp module must be loaded. For FIFO, the fifo_name parameter must be set. For DATAGRAM, the dgram_socket parameter must be set.

  • 1 - only HTTP transport

  • 2 - only FIFO transport

  • 4 - only DATAGRAM transport

The value can be also a combination of specific transports. Make the sum of the desired transports to enable them. For example, enabling FIFO and DATAGRAM can be done setting transport=6.

Default value is '6' (fifo and datagram transport).

Example 1.2. Set transport parameter

...
modparam("jsonrpcs", "transport", 1)
...

4.3. fifo_name (str)

The name of the FIFO file to be created for listening and reading external commands. If the given path is not absolute, the fifo file is created relative to run_dir (global parameter).

Default value is "kamailio_rpc.fifo".

Example 1.3. Set fifo_name parameter

...
modparam("jsonrpcs", "fifo_name", "/tmp/kamailio_jsonrpc.fifo")
...

4.4. fifo_mode (int)

Permission to be used for creating the listening FIFO file. It follows the UNIX conventions.

Default value is 0660 (rw-rw----).

Example 1.4. Set fifo_mode parameter

...
modparam("jsonrpcs", "fifo_mode", 0600)
...

4.5. fifo_group (int or str)

System Group to be used for creating the listening FIFO file.

Default value is the inherited one (process group).

Example 1.5. Set fifo_group parameter

...
modparam("jsonrpcs", "fifo_group", 0)
modparam("jsonrpcs", "fifo_group", "root")
...

4.6. fifo_user (int or str)

System User to be used for creating the listening FIFO file.

Default value is the inherited one (process user).

Example 1.6. Set fifo_user parameter

...
modparam("jsonrpcs", "fifo_user", 0)
modparam("jsonrpcs", "fifo_user", "root")
...

4.7. fifo_reply_dir (str)

Directory to be used for creating the reply FIFO files.

Default value is /tmp/

Example 1.7. Set fifo_reply_dir parameter

...
modparam("jsonrpcs", "fifo_reply_dir", "/home/kamailio/tmp/")
...

4.8. dgram_socket (str)

The name of a Unix socket file or an IP address. The Unix datagram or UDP socket will be created using this parameter in order to read the external commands. Both IPv4 and IPv6 are supported. If the given path for Unix socket is not absolute, then it is created relative to run_dir (global parameter).

Default value is "kamailio_rpc.sock".

Example 1.8. Set dgram_socket parameter

...
modparam("jsonrpcs", "dgram_socket", "/tmp/kamailio_rpc.sock")
...
modparam("jsonrpcs", "dgram_socket", "udp:1.2.3.4:8090")
...

4.9. dgram_workers (str)

The number of worker processes to be created. Each worker process will be a datagram server.

Default value is 1.

Example 1.9. Set dgram_workers parameter

...
modparam("jsonrpcs", "dgram_workers", 4)
...

4.10. dgram_mode (int)

Permission to be used for creating the listening UNIX datagram socket. Not necessary for a UDP socket. It follows the UNIX conventions.

Default value is 0660 (rw-rw----).

Example 1.10. Set dgram_mode parameter

...
modparam("jsonrpcs", "dgram_mode", 0600)
...

4.11. dgram_group (int) dgram_group (str)

Group to be used for creating the listening UNIX socket.

Default value is the inherited one.

Example 1.11. Set dgram_group parameter

...
modparam("jsonrpcs", "dgram_group", 0)
modparam("jsonrpcs", "dgram_group", "root")
...

4.12. dgram_user (int) dgram_group (str)

User to be used for creating the listening UNIX socket.

Default value is the inherited one.

Example 1.12. Set dgram_user parameter

...
modparam("jsonrpcs", "dgram_user", 0)
modparam("jsonrpcs", "dgram_user", "root")
...

4.13. dgram_timeout (int)

The reply will expire after trying to sent it for socket_timeout miliseconds.

Default value is 2000.

Example 1.13. Set dgram_timeout parameter

...
modparam("jsonrpcs", "dgram_timeout", 2000)
...

5. Functions

5.1.  jsonrpc_dispatch()

Handle the JSONRPC request and generate a response.

Example 1.14. jsonrpc_dispatch usage

...
#!KAMAILIO

memdbg=5
memlog=5

debug=3
log_stderror=yes

fork=yes
children=2

tcp_accept_no_cl=yes

mpath="modules/"

loadmodule "sl.so"
loadmodule "pv.so"
loadmodule "xhttp.so"
loadmodule "jsonrpcs.so"

request_route {
	send_reply("404", "not found");
	exit;
}

event_route[xhttp:request] {
    if(src_ip!=127.0.0.1) {
        xhttp_reply("403", "Forbidden", "text/html",
            "<html><body>Not allowed from $si</body></html>");
        exit;
	}
	if ($hu =~ "^/RPC") {
		jsonrpc_dispatch();
	} else {
        xhttp_reply("200", "OK", "text/html",
            "<html><body>Wrong URL $hu</body></html>");
    }
    return;
}
...

5.2.  jsonrpc_exec(cmd)

Execute a JSON-RPC command given as a parameter.

The parameter has to be a valid full JSON-RPC document. It can be a dynamic string with variables. The result of the command can be accessed via $jsonrpl(key) pseudo variables.

Example 1.15. jsonrpc_exec usage

...
jsonrpc_exec('{"jsonrpc": "2.0", "method": "dispatcher.reload", "id": 1}');
...

6. JSONRPC Commands

Here are some examples of RPC commands with the equivalent of running them with kamcmd and the corresponding JSON document for them. It is important to be aware that the name of the parameters doesn't matter, only the order of the values must be the one expected by Kamailio RPC command.

Example 1.16. JSONRPC Commands - Examples

...
# kamcmd core.psx

{
 "jsonrpc": "2.0",
  "method": "core.psx",
  "id": 1
}
...
## - prototype: kamcmd dispatcher.set_state _state_ _group_ _address_
# kamcmd dispatcher.set_state ip 2 sip:127.0.0.1:5080

{
  "jsonrpc": "2.0",
  "method": "dispatcher.set_state",
  "params": ["ip", 2, "sip:127.0.0.1:5080"],
  "id": 1
}

## - or:

{
  "jsonrpc": "2.0",
  "method": "dispatcher.set_state",
  "params": {
    "state": "ip",
    "grpup": 2,
    "address": "sip:127.0.0.1:5080"
  },
  "id": 1
}
...

7. JSONRPC Transports

JSONRPC specifications do not enforce a specific transport to carry the JSON documents. Very common is JSONRPC over HTTP or HTTPS, and they are supported by Kamailio. In addition, Kamailio supports receiving JSON documents via a local FIFO file.

7.1. JSONRPC Over HTTP

It requires that XHTTP module is loaded. HTTPS can be used if you enable TLS for Kamailio. The JSONRPC requests have to be sent to the TCP or TLS ports of Kamailio.

The 'transport' parameter has to be 0 or 1.

The format of the JSON document must follow the JSONRPC specifications.

7.2. JSONRPC Over FIFO

This module can retrive JSONRPC requests via a local FIFO file. To enable this feature, 'fifo_name' parameter must be set and 'transport' parameter has to be 0 or 2.

The format of the JSON document must follow the JSONRPC specifications plus an additional field named 'reply_name'. The value for this field must be the name of the FIFO file were to write the JSONRPC response. The reply FIFO file is created in the folder specified by 'fifo_reply_dir'. Next is an example showing a JSONRPC command to be sent via FIFO transport.

Example 1.17. JSONRPC Over Fifo Command

...
{
 "jsonrpc": "2.0",
  "method": "core.psx",
  "reply_name": "kamailio_jsonrpc_reply_fifo",
  "id": 1
}
...

Next is an example of how to test it from a terminal, assuming that the parameter 'fifo_name' is set to '/tmp/kamailio_jsonrpc_fifo'.

Example 1.18. JSONRPC Over Fifo Command From Termina

...
mkfifo /tmp/kamailio_jsonrpc_reply_fifo
cat /tmp/kamailio_jsonrpc_reply_fifo &
echo '{"jsonrpc": "2.0", "method": "core.psx", \
          "reply_name": "kamailio_jsonrpc_reply_fifo", "id": 1}' \
     > /tmp/kamailio_jsonrpc_fifo
rm /tmp/kamailio_jsonrpc_reply_fifo

7.3. JSONRPC Over DATAGRAM

This module can retrive JSONRPC requests via a UNIX socket file or UDP IPv4/IPv6 socket. To enable this feature, 'dgram_socket' parameter must be set and 'transport' parameter has to be 0 or 4.

The 'transport' parameter has to be 0 or 4.

The format of the JSON document must follow the JSONRPC specifications.