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56 lines
1.7 KiB
JavaScript

import { ERROR_PACKET, PACKET_TYPES_REVERSE, } from "./commons.js";
export const decodePacket = (encodedPacket, binaryType) => {
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if (typeof encodedPacket !== "string") {
return {
type: "message",
data: mapBinary(encodedPacket, binaryType),
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};
}
const type = encodedPacket.charAt(0);
if (type === "b") {
const buffer = Buffer.from(encodedPacket.substring(1), "base64");
return {
type: "message",
data: mapBinary(buffer, binaryType),
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};
}
if (!PACKET_TYPES_REVERSE[type]) {
return ERROR_PACKET;
}
return encodedPacket.length > 1
? {
type: PACKET_TYPES_REVERSE[type],
data: encodedPacket.substring(1),
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}
: {
type: PACKET_TYPES_REVERSE[type],
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};
};
const mapBinary = (data, binaryType) => {
switch (binaryType) {
case "arraybuffer":
if (data instanceof ArrayBuffer) {
// from WebSocket & binaryType "arraybuffer"
return data;
}
else if (Buffer.isBuffer(data)) {
// from HTTP long-polling
return data.buffer.slice(data.byteOffset, data.byteOffset + data.byteLength);
}
else {
// from WebTransport (Uint8Array)
return data.buffer;
}
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case "nodebuffer":
default:
if (Buffer.isBuffer(data)) {
// from HTTP long-polling or WebSocket & binaryType "nodebuffer" (default)
return data;
}
else {
// from WebTransport (Uint8Array)
return Buffer.from(data);
}
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}
};