sip-parser

A simple npm package for parsing and stringifying SIP messages.

Install

npm install sip-parser

Features

• Parse raw SIP messages into JavaScript objects.
• Stringify JS objects into SIP messages.
• Distinguishes requests and responses automatically.
• TypeScript typing.

Usage

parse and stringify functions automatically recognize whether the message in question is a request or a response. In the parsed object, requests have a method field while responses have a statusCode field.

Requests

parse()

Use the parse(message) function to parse a raw SIP message into a JavaScript object.

import { parse } from 'sip-parser';

// In a real use case, maybe you get this from a TCP socket.
const messageString =
    'INVITE sip:[email protected] SIP/2.0\r\n' +
    'Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKkjshdyff\r\n' +
    'To: Bob <sip:[email protected]>\r\n' +
    'From: Alice <sip:[email protected]>;tag=88sja8x\r\n' +
    'Max-Forwards: 70\r\n' +
    'Subject: I know you are there\r\n' +
    '         pick up the phone\r\n' +
    '         and answer!\r\n' +
    'Call-ID: 987asjd97y7atg\r\n' +
    'CSeq: 986759 INVITE';

const parsedMessage = parse(messageString);

console.log(JSON.stringify(parsedMessage, null, 4));

This will print:

{
    "method": "INVITE",
    "version": "2.0",
    "requestUri": {
        "user": "bob",
        "host": "biloxi.com"
    },
    "headers": [
        {
            "fieldName": "Via",
            "fieldValue": "SIP/2.0/UDP pc33.atlanta.com",
            "parameters": [
                {
                    "name": "branch",
                    "value": "z9hG4bKkjshdyff"
                }
            ]
        },
        {
            "fieldName": "To",
            "fieldValue": "Bob <sip:[email protected]>"
        },
        {
            "fieldName": "From",
            "fieldValue": "Alice <sip:[email protected]>",
            "parameters": [
                {
                    "name": "tag",
                    "value": "88sja8x"
                }
            ]
        },
        {
            "fieldName": "Max-Forwards",
            "fieldValue": "70"
        },
        {
            "fieldName": "Subject",
            "fieldValue": "I know you are there pick up the phone and answer!"
        },
        {
            "fieldName": "Call-ID",
            "fieldValue": "987asjd97y7atg"
        },
        {
            "fieldName": "CSeq",
            "fieldValue": "986759 INVITE"
        }
    ],
    "content": ""
}

stringify()

Essentially, stringify(messageObject) is an inverse opration of parse. In the following example, we first parse a message and then stringify it back to SIP format. In your application, you most likely want to manipulate the message a bit more or create it from scratch in your application logic.

import { parse, stringify } from 'sip-parser';

const messageString =
    'INVITE sip:[email protected] SIP/2.0\r\n' +
    'Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKkjshdyff\r\n' +
    'To: Bob <sip:[email protected]>\r\n' +
    'From: Alice <sip:[email protected]>;tag=88sja8x\r\n' +
    'Max-Forwards: 70\r\n' +
    'Subject: I know you are there\r\n' +
    '         pick up the phone\r\n' +
    '         and answer!\r\n' +
    'Call-ID: 987asjd97y7atg\r\n' +
    'CSeq: 986759 INVITE';

// In a real use case, you would build the message object in your
// application logic, whatever it might be.
const parsedMessage = parse(messageString);
// See the format of the parsed message in the previous example.
const stringifiedMessage = stringify(parsedMessage)
console.log(stringifiedMessage)

This would print:

INVITE sip:[email protected] SIP/2.0
Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKkjshdyff
To: Bob <sip:[email protected]>
From: Alice <sip:[email protected]>;tag=88sja8x
Max-Forwards: 70
Subject: I know you are there pick up the phone and answer!
Call-ID: 987asjd97y7atg
CSeq: 986759 INVITE

Responses

SIP responses are very similar to requests; they only differ in the start line. Parsed responses have statusCode and reason fields:

import { parse } from './index';

const sipResponse =
    'SIP/2.0 200 OK\r\n' +
    'Via: SIP/2.0/UDP bobspc.biloxi.com:5060;branch=z9hG4bKnashds7\r\n' +
    '     ;received=192.0.2.4\r\n' +
    'To: Bob <sip:[email protected]>;tag=2493k59kd\r\n' +
    'From: Bob <sip:[email protected]>;tag=456248\r\n' +
    'Call-ID: 843817637684230@998sdasdh09\r\n' +
    'CSeq: 1826 REGISTER\r\n' +
    'Contact: <sip:[email protected]>\r\n' +
    'Expires: 7200\r\n' +
    'Content-Length: 0';

const parsedResponse = parse(sipResponse);
console.log(JSON.stringify(parsedResponse, null, 4));

Prints:

{
    "version": "2.0",
    "statusCode": 200,
    "reason": "OK",
    "headers": [
        {
            "fieldName": "Via",
            "fieldValue": "SIP/2.0/UDP bobspc.biloxi.com:5060",
            "parameters": [
                {
                    "name": "branch",
                    "value": "z9hG4bKnashds7"
                },
                {
                    "name": "received",
                    "value": "192.0.2.4"
                }
            ]
        },
        {
            "fieldName": "To",
            "fieldValue": "Bob <sip:[email protected]>",
            "parameters": [
                {
                    "name": "tag",
                    "value": "2493k59kd"
                }
            ]
        },
        {
            "fieldName": "From",
            "fieldValue": "Bob <sip:[email protected]>",
            "parameters": [
                {
                    "name": "tag",
                    "value": "456248"
                }
            ]
        },
        {
            "fieldName": "Call-ID",
            "fieldValue": "843817637684230@998sdasdh09"
        },
        {
            "fieldName": "CSeq",
            "fieldValue": "1826 REGISTER"
        },
        {
            "fieldName": "Contact",
            "fieldValue": "<sip:[email protected]>"
        },
        {
            "fieldName": "Expires",
            "fieldValue": "7200"
        },
        {
            "fieldName": "Content-Length",
            "fieldValue": "0"
        }
    ],
    "content": ""
}

Obviously, stringifying the resulting object returns a valid SIP response string.

Types

You can easily import all types, if you want to use them in the definitions of your own functions and variables:

import { types as SipTypes } from 'sip-parser';

export function getHeader(message: SipTypes.SIPMessage, headerName: string): SipTypes.Header | undefined {
    return message.headers.find(h => h.fieldName.toLocaleLowerCase() === headerName.toLocaleLowerCase());
}