mirror of https://github.com/gchq/CyberChef.git
131 lines
4.5 KiB
JavaScript
131 lines
4.5 KiB
JavaScript
/**
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* @author n1474335 [n1474335@gmail.com]
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* @copyright Crown Copyright 2016
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* @license Apache-2.0
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*/
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import Operation from "../Operation";
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import Utils from "../Utils";
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import OperationError from "../errors/OperationError";
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import {fromHex, toHex} from "../lib/Hex";
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import {ipv4ToStr, protocolLookup} from "../lib/IP";
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import TCPIPChecksum from "./TCPIPChecksum";
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/**
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* Parse IPv4 header operation
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*/
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class ParseIPv4Header extends Operation {
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/**
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* ParseIPv4Header constructor
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*/
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constructor() {
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super();
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this.name = "Parse IPv4 header";
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this.module = "Default";
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this.description = "Given an IPv4 header, this operations parses and displays each field in an easily readable format.";
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this.infoURL = "https://wikipedia.org/wiki/IPv4#Header";
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this.inputType = "string";
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this.outputType = "html";
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this.args = [
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{
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"name": "Input format",
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"type": "option",
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"value": ["Hex", "Raw"]
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}
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];
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}
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/**
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* @param {string} input
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* @param {Object[]} args
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* @returns {html}
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*/
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run(input, args) {
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const format = args[0];
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let output;
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if (format === "Hex") {
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input = fromHex(input);
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} else if (format === "Raw") {
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input = Utils.strToByteArray(input);
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} else {
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throw new OperationError("Unrecognised input format.");
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}
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let ihl = input[0] & 0x0f;
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const dscp = (input[1] >>> 2) & 0x3f,
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ecn = input[1] & 0x03,
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length = input[2] << 8 | input[3],
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identification = input[4] << 8 | input[5],
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flags = (input[6] >>> 5) & 0x07,
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fragOffset = (input[6] & 0x1f) << 8 | input[7],
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ttl = input[8],
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protocol = input[9],
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checksum = input[10] << 8 | input[11],
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srcIP = input[12] << 24 | input[13] << 16 | input[14] << 8 | input[15],
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dstIP = input[16] << 24 | input[17] << 16 | input[18] << 8 | input[19],
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checksumHeader = input.slice(0, 10).concat([0, 0]).concat(input.slice(12, 20));
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let version = (input[0] >>> 4) & 0x0f,
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options = [];
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// Version
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if (version !== 4) {
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version = version + " (Error: for IPv4 headers, this should always be set to 4)";
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}
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// IHL
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if (ihl < 5) {
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ihl = ihl + " (Error: this should always be at least 5)";
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} else if (ihl > 5) {
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// sort out options...
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const optionsLen = ihl * 4 - 20;
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options = input.slice(20, optionsLen + 20);
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}
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// Protocol
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const protocolInfo = protocolLookup[protocol] || {keyword: "", protocol: ""};
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// Checksum
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const correctChecksum = (new TCPIPChecksum).run(checksumHeader),
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givenChecksum = Utils.hex(checksum);
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let checksumResult;
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if (correctChecksum === givenChecksum) {
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checksumResult = givenChecksum + " (correct)";
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} else {
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checksumResult = givenChecksum + " (incorrect, should be " + correctChecksum + ")";
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}
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output = `<table class='table table-hover table-sm table-bordered table-nonfluid'><tr><th>Field</th><th>Value</th></tr>
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<tr><td>Version</td><td>${version}</td></tr>
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<tr><td>Internet Header Length (IHL)</td><td>${ihl} (${ihl * 4} bytes)</td></tr>
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<tr><td>Differentiated Services Code Point (DSCP)</td><td>${dscp}</td></tr>
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<tr><td>Explicit Congestion Notification (ECN)</td><td>${ecn}</td></tr>
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<tr><td>Total length</td><td>${length} bytes
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IP header: ${ihl * 4} bytes
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Data: ${length - ihl * 4} bytes</td></tr>
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<tr><td>Identification</td><td>0x${Utils.hex(identification)} (${identification})</td></tr>
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<tr><td>Flags</td><td>0x${Utils.hex(flags, 2)}
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Reserved bit:${flags >> 2} (must be 0)
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Don't fragment:${flags >> 1 & 1}
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More fragments:${flags & 1}</td></tr>
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<tr><td>Fragment offset</td><td>${fragOffset}</td></tr>
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<tr><td>Time-To-Live</td><td>${ttl}</td></tr>
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<tr><td>Protocol</td><td>${protocol}, ${protocolInfo.protocol} (${protocolInfo.keyword})</td></tr>
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<tr><td>Header checksum</td><td>${checksumResult}</td></tr>
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<tr><td>Source IP address</td><td>${ipv4ToStr(srcIP)}</td></tr>
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<tr><td>Destination IP address</td><td>${ipv4ToStr(dstIP)}</td></tr>`;
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if (ihl > 5) {
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output += `<tr><td>Options</td><td>${toHex(options)}</td></tr>`;
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}
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return output + "</table>";
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}
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}
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export default ParseIPv4Header;
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