Backend half

SerpentRace_Backend/node_modules/aws-sdk/lib/event-stream/split-message.js

@@ -0,0 +1,70 @@
+var util = require('../core').util;
+var toBuffer = util.buffer.toBuffer;
+
+// All prelude components are unsigned, 32-bit integers
+var PRELUDE_MEMBER_LENGTH = 4;
+// The prelude consists of two components
+var PRELUDE_LENGTH = PRELUDE_MEMBER_LENGTH * 2;
+// Checksums are always CRC32 hashes.
+var CHECKSUM_LENGTH = 4;
+// Messages must include a full prelude, a prelude checksum, and a message checksum
+var MINIMUM_MESSAGE_LENGTH = PRELUDE_LENGTH + CHECKSUM_LENGTH * 2;
+
+/**
+ * @api private
+ *
+ * @param {Buffer} message
+ */
+function splitMessage(message) {
+    if (!util.Buffer.isBuffer(message)) message = toBuffer(message);
+
+    if (message.length < MINIMUM_MESSAGE_LENGTH) {
+        throw new Error('Provided message too short to accommodate event stream message overhead');
+    }
+
+    if (message.length !== message.readUInt32BE(0)) {
+        throw new Error('Reported message length does not match received message length');
+    }
+
+    var expectedPreludeChecksum = message.readUInt32BE(PRELUDE_LENGTH);
+
+    if (
+        expectedPreludeChecksum !== util.crypto.crc32(
+            message.slice(0, PRELUDE_LENGTH)
+        )
+    ) {
+        throw new Error(
+            'The prelude checksum specified in the message (' +
+            expectedPreludeChecksum +
+            ') does not match the calculated CRC32 checksum.'
+        );
+    }
+
+    var expectedMessageChecksum = message.readUInt32BE(message.length - CHECKSUM_LENGTH);
+
+    if (
+        expectedMessageChecksum !== util.crypto.crc32(
+            message.slice(0, message.length - CHECKSUM_LENGTH)
+        )
+    ) {
+        throw new Error(
+            'The message checksum did not match the expected value of ' +
+                expectedMessageChecksum
+        );
+    }
+
+    var headersStart = PRELUDE_LENGTH + CHECKSUM_LENGTH;
+    var headersEnd = headersStart + message.readUInt32BE(PRELUDE_MEMBER_LENGTH);
+
+    return {
+        headers: message.slice(headersStart, headersEnd),
+        body: message.slice(headersEnd, message.length - CHECKSUM_LENGTH),
+    };
+}
+
+/**
+ * @api private
+ */
+module.exports = {
+    splitMessage: splitMessage
+};