jssip/lib/sanityCheck.js

The Javascript SIP library

"use strict";
const Logger = require('./Logger');
const JsSIP_C = require('./Constants');
const SIPMessage = require('./SIPMessage');
const Utils = require('./Utils');
const logger = new Logger('sanityCheck');
// Checks for requests and responses.
const all = [minimumHeaders];
// Checks for requests.
const requests = [
    rfc3261_8_2_2_1,
    rfc3261_16_3_4,
    rfc3261_18_3_request,
    rfc3261_8_2_2_2,
];
// Checks for responses.
const responses = [rfc3261_8_1_3_3, rfc3261_18_3_response];
// local variables.
let message;
let ua;
let transport;
module.exports = (m, u, t) => {
    message = m;
    ua = u;
    transport = t;
    for (const check of all) {
        if (check() === false) {
            return false;
        }
    }
    if (message instanceof SIPMessage.IncomingRequest) {
        for (const check of requests) {
            if (check() === false) {
                return false;
            }
        }
    }
    else if (message instanceof SIPMessage.IncomingResponse) {
        for (const check of responses) {
            if (check() === false) {
                return false;
            }
        }
    }
    // Everything is OK.
    return true;
};
/*
 * Sanity Check for incoming Messages
 *
 * Requests:
 *  - _rfc3261_8_2_2_1_ Receive a Request with a non supported URI scheme
 *  - _rfc3261_16_3_4_ Receive a Request already sent by us
 *   Does not look at via sent-by but at jssip_id, which is inserted as
 *   a prefix in all initial requests generated by the ua
 *  - _rfc3261_18_3_request_ Body Content-Length
 *  - _rfc3261_8_2_2_2_ Merged Requests
 *
 * Responses:
 *  - _rfc3261_8_1_3_3_ Multiple Via headers
 *  - _rfc3261_18_3_response_ Body Content-Length
 *
 * All:
 *  - Minimum headers in a SIP message
 */
// Sanity Check functions for requests.
function rfc3261_8_2_2_1() {
    if (message.s('to').uri.scheme !== 'sip') {
        reply(416);
        return false;
    }
}
function rfc3261_16_3_4() {
    if (!message.to_tag) {
        if (message.call_id.substr(0, 5) === ua.configuration.jssip_id) {
            reply(482);
            return false;
        }
    }
}
function rfc3261_18_3_request() {
    const len = Utils.str_utf8_length(message.body);
    const contentLength = message.getHeader('content-length');
    if (len < contentLength) {
        reply(400);
        return false;
    }
}
function rfc3261_8_2_2_2() {
    const fromTag = message.from_tag;
    const call_id = message.call_id;
    const cseq = message.cseq;
    let tr;
    // Accept any in-dialog request.
    if (message.to_tag) {
        return;
    }
    // INVITE request.
    if (message.method === JsSIP_C.INVITE) {
        // If the branch matches the key of any IST then assume it is a retransmission
        // and ignore the INVITE.
        // TODO: we should reply the last response.
        if (ua._transactions.ist[message.via_branch]) {
            return false;
        }
        // Otherwise check whether it is a merged request.
        else {
            for (const transaction in ua._transactions.ist) {
                if (Object.prototype.hasOwnProperty.call(ua._transactions.ist, transaction)) {
                    tr = ua._transactions.ist[transaction];
                    if (tr.request.from_tag === fromTag &&
                        tr.request.call_id === call_id &&
                        tr.request.cseq === cseq) {
                        reply(482);
                        return false;
                    }
                }
            }
        }
    }
    // Non INVITE request.
    // If the branch matches the key of any NIST then assume it is a retransmission
    // and ignore the request.
    // TODO: we should reply the last response.
    else if (ua._transactions.nist[message.via_branch]) {
        return false;
    }
    // Otherwise check whether it is a merged request.
    else {
        for (const transaction in ua._transactions.nist) {
            if (Object.prototype.hasOwnProperty.call(ua._transactions.nist, transaction)) {
                tr = ua._transactions.nist[transaction];
                if (tr.request.from_tag === fromTag &&
                    tr.request.call_id === call_id &&
                    tr.request.cseq === cseq) {
                    reply(482);
                    return false;
                }
            }
        }
    }
}
// Sanity Check functions for responses.
function rfc3261_8_1_3_3() {
    if (message.getHeaders('via').length > 1) {
        logger.debug('more than one Via header field present in the response, dropping the response');
        return false;
    }
}
function rfc3261_18_3_response() {
    const len = Utils.str_utf8_length(message.body), contentLength = message.getHeader('content-length');
    if (len < contentLength) {
        logger.debug('message body length is lower than the value in Content-Length header field, dropping the response');
        return false;
    }
}
// Sanity Check functions for requests and responses.
function minimumHeaders() {
    const mandatoryHeaders = ['from', 'to', 'call_id', 'cseq', 'via'];
    for (const header of mandatoryHeaders) {
        if (!message.hasHeader(header)) {
            logger.debug(`missing mandatory header field : ${header}, dropping the response`);
            return false;
        }
    }
}
// Reply.
function reply(status_code) {
    const vias = message.getHeaders('via');
    let to;
    let response = `SIP/2.0 ${status_code} ${JsSIP_C.REASON_PHRASE[status_code]}\r\n`;
    for (const via of vias) {
        response += `Via: ${via}\r\n`;
    }
    to = message.getHeader('To');
    if (!message.to_tag) {
        to += `;tag=${Utils.newTag()}`;
    }
    response += `To: ${to}\r\n`;
    response += `From: ${message.getHeader('From')}\r\n`;
    response += `Call-ID: ${message.call_id}\r\n`;
    response += `CSeq: ${message.cseq} ${message.method}\r\n`;
    response += '\r\n';
    transport.send(response);
}