ESM: Tidied up IP operations

src/core/operations/ParseIPv4Header.mjs

@@ -0,0 +1,129 @@
+/**
+ * @author n1474335 [n1474335@gmail.com]
+ * @copyright Crown Copyright 2016
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import Utils from "../Utils";
+import OperationError from "../errors/OperationError";
+import {fromHex, toHex} from "../lib/Hex";
+import {ipv4ToStr, protocolLookup} from "../lib/IP";
+import TCPIPChecksum from "./TCPIPChecksum";
+
+/**
+ * Parse IPv4 header operation
+ */
+class ParseIPv4Header extends Operation {
+
+    /**
+     * ParseIPv4Header constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Parse IPv4 header";
+        this.module = "JSBN";
+        this.description = "Given an IPv4 header, this operations parses and displays each field in an easily readable format.";
+        this.inputType = "string";
+        this.outputType = "html";
+        this.args = [
+            {
+                "name": "Input format",
+                "type": "option",
+                "value": ["Hex", "Raw"]
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {html}
+     */
+    run(input, args) {
+        const format = args[0];
+        let output;
+
+        if (format === "Hex") {
+            input = fromHex(input);
+        } else if (format === "Raw") {
+            input = Utils.strToByteArray(input);
+        } else {
+            throw new OperationError("Unrecognised input format.");
+        }
+
+        let ihl = input[0] & 0x0f;
+        const dscp = (input[1] >>> 2) & 0x3f,
+            ecn = input[1] & 0x03,
+            length = input[2] << 8 | input[3],
+            identification = input[4] << 8 | input[5],
+            flags = (input[6] >>> 5) & 0x07,
+            fragOffset = (input[6] & 0x1f) << 8 | input[7],
+            ttl = input[8],
+            protocol = input[9],
+            checksum = input[10] << 8 | input[11],
+            srcIP = input[12] << 24 | input[13] << 16 | input[14] << 8 | input[15],
+            dstIP = input[16] << 24 | input[17] << 16 | input[18] << 8 | input[19],
+            checksumHeader = input.slice(0, 10).concat([0, 0]).concat(input.slice(12, 20));
+        let version = (input[0] >>> 4) & 0x0f,
+            options = [];
+
+
+        // Version
+        if (version !== 4) {
+            version = version + " (Error: for IPv4 headers, this should always be set to 4)";
+        }
+
+        // IHL
+        if (ihl < 5) {
+            ihl = ihl + " (Error: this should always be at least 5)";
+        } else if (ihl > 5) {
+            // sort out options...
+            const optionsLen = ihl * 4 - 20;
+            options = input.slice(20, optionsLen + 20);
+        }
+
+        // Protocol
+        const protocolInfo = protocolLookup[protocol] || {keyword: "", protocol: ""};
+
+        // Checksum
+        const correctChecksum = (new TCPIPChecksum).run(checksumHeader),
+            givenChecksum = Utils.hex(checksum);
+        let checksumResult;
+        if (correctChecksum === givenChecksum) {
+            checksumResult = givenChecksum + " (correct)";
+        } else {
+            checksumResult = givenChecksum + " (incorrect, should be " + correctChecksum + ")";
+        }
+
+        output = `<table class='table table-hover table-condensed table-bordered table-nonfluid'><tr><th>Field</th><th>Value</th></tr>
+<tr><td>Version</td><td>${version}</td></tr>
+<tr><td>Internet Header Length (IHL)</td><td>${ihl} (${ihl * 4} bytes)</td></tr>
+<tr><td>Differentiated Services Code Point (DSCP)</td><td>${dscp}</td></tr>
+<tr><td>Explicit Congestion Notification (ECN)</td><td>${ecn}</td></tr>
+<tr><td>Total length</td><td>${length} bytes
+  IP header: ${ihl * 4} bytes
+  Data: ${length - ihl * 4} bytes</td></tr>
+<tr><td>Identification</td><td>0x${Utils.hex(identification)} (${identification})</td></tr>
+<tr><td>Flags</td><td>0x${Utils.hex(flags, 2)}
+  Reserved bit:${flags >> 2} (must be 0)
+  Don't fragment:${flags >> 1 & 1}
+  More fragments:${flags & 1}</td></tr>
+<tr><td>Fragment offset</td><td>${fragOffset}</td></tr>
+<tr><td>Time-To-Live</td><td>${ttl}</td></tr>
+<tr><td>Protocol</td><td>${protocol}, ${protocolInfo.protocol} (${protocolInfo.keyword})</td></tr>
+<tr><td>Header checksum</td><td>${checksumResult}</td></tr>
+<tr><td>Source IP address</td><td>${ipv4ToStr(srcIP)}</td></tr>
+<tr><td>Destination IP address</td><td>${ipv4ToStr(dstIP)}</td></tr>`;
+
+        if (ihl > 5) {
+            output += `<tr><td>Options</td><td>${toHex(options)}</td></tr>`;
+        }
+
+        return output + "</table>";
+    }
+
+}
+
+export default ParseIPv4Header;