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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
"use strict";
const {
delimitedRead,
const CryptoHash = Components.Constructor(
"@mozilla.org/security/hash;1",
"nsICryptoHash",
"initWithString"
);
const threadManager = Cc["@mozilla.org/thread-manager;1"].getService();
// Limit the header size to put an upper bound on allocated memory
const HEADER_MAX_LEN = 8000;
/**
* Read a line from async input stream and return promise that resolves to the line once
* it has been read. If the line is longer than HEADER_MAX_LEN, will throw error.
*/
function readLine(input) {
return new Promise((resolve, reject) => {
let line = "";
const wait = () => {
input.asyncWait(
() => {
try {
const amountToRead = HEADER_MAX_LEN - line.length;
line += delimitedRead(input, "\n", amountToRead);
if (line.endsWith("\n")) {
resolve(line.trimRight());
return;
}
if (line.length >= HEADER_MAX_LEN) {
throw new Error(
`Failed to read HTTP header longer than ${HEADER_MAX_LEN} bytes`
);
}
wait();
} catch (ex) {
reject(ex);
}
},
0,
0,
threadManager.currentThread
);
};
wait();
});
}
/**
* Write a string of bytes to async output stream and return promise that resolves once
* all data has been written. Doesn't do any utf-16/utf-8 conversion - the string is
* treated as an array of bytes.
*/
function writeString(output, data) {
return new Promise((resolve, reject) => {
const wait = () => {
if (data.length === 0) {
resolve();
return;
}
output.asyncWait(
() => {
try {
const written = output.write(data, data.length);
data = data.slice(written);
wait();
} catch (ex) {
reject(ex);
}
},
0,
0,
threadManager.currentThread
);
};
wait();
});
}
/**
* Read HTTP request from async input stream.
* @return Request line (string) and Map of header names and values.
*/
const readHttpRequest = async function (input) {
let requestLine = "";
const headers = new Map();
while (true) {
const line = await readLine(input);
if (!line.length) {
break;
}
if (!requestLine) {
requestLine = line;
} else {
const colon = line.indexOf(":");
if (colon == -1) {
throw new Error(`Malformed HTTP header: ${line}`);
}
const name = line.slice(0, colon).toLowerCase();
const value = line.slice(colon + 1).trim();
headers.set(name, value);
}
}
return { requestLine, headers };
};
/**
* Write HTTP response (array of strings) to async output stream.
*/
function writeHttpResponse(output, response) {
const responseString = response.join("\r\n") + "\r\n\r\n";
return writeString(output, responseString);
}
/**
* Process the WebSocket handshake headers and return the key to be sent in
* Sec-WebSocket-Accept response header.
*/
function processRequest({ requestLine, headers }) {
const [method, path] = requestLine.split(" ");
if (method !== "GET") {
throw new Error("The handshake request must use GET method");
}
if (path !== "/") {
throw new Error("The handshake request has unknown path");
}
const upgrade = headers.get("upgrade");
if (!upgrade || upgrade !== "websocket") {
throw new Error("The handshake request has incorrect Upgrade header");
}
const connection = headers.get("connection");
if (
!connection ||
!connection
.split(",")
.map(t => t.trim())
.includes("Upgrade")
) {
throw new Error("The handshake request has incorrect Connection header");
}
const version = headers.get("sec-websocket-version");
if (!version || version !== "13") {
throw new Error(
"The handshake request must have Sec-WebSocket-Version: 13"
);
}
// Compute the accept key
const key = headers.get("sec-websocket-key");
if (!key) {
throw new Error(
"The handshake request must have a Sec-WebSocket-Key header"
);
}
return { acceptKey: computeKey(key) };
}
function computeKey(key) {
const str = key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
const data = Array.from(str, ch => ch.charCodeAt(0));
const hash = new CryptoHash("sha1");
hash.update(data, data.length);
return hash.finish(true);
}
/**
* Perform the server part of a WebSocket opening handshake on an incoming connection.
*/
const serverHandshake = async function (input, output) {
// Read the request
const request = await readHttpRequest(input);
try {
// Check and extract info from the request
const { acceptKey } = processRequest(request);
// Send response headers
await writeHttpResponse(output, [
"HTTP/1.1 101 Switching Protocols",
"Upgrade: websocket",
"Connection: Upgrade",
`Sec-WebSocket-Accept: ${acceptKey}`,
]);
} catch (error) {
// Send error response in case of error
await writeHttpResponse(output, ["HTTP/1.1 400 Bad Request"]);
throw error;
}
};
/**
* Accept an incoming WebSocket server connection.
* Takes an established nsISocketTransport in the parameters.
* Performs the WebSocket handshake and waits for the WebSocket to open.
* Returns Promise with a WebSocket ready to send and receive messages.
*/
const accept = async function (transport, input, output) {
await serverHandshake(input, output);
const transportProvider = {
setListener(upgradeListener) {
// The onTransportAvailable callback shouldn't be called synchronously.
executeSoon(() => {
upgradeListener.onTransportAvailable(transport, input, output);
});
},
};
return new Promise((resolve, reject) => {
const socket = WebSocket.createServerWebSocket(
null,
[],
transportProvider,
""
);
socket.addEventListener("close", () => {
input.close();
output.close();
});
socket.onopen = () => resolve(socket);
socket.onerror = err => reject(err);
});
};
exports.accept = accept;