2026-04-21 13:16:36 +08:00

353 lines
9.7 KiB
JavaScript

/*
* Copyright (c) 2013 Antoine Martin <antoine@xpra.org>
*
* Licensed under MPL 2.0
*
* xpra wire protocol for WebTransport
*
*/
/*
The main Xpra wire protocol
*/
class XpraWebTransportProtocol {
constructor() {
this.verify_connected_timer = 0;
this.packet_handler = null;
this.webtransport = null;
this.stream = null;
this.writer = null;
this.raw_packets = [];
this.rQ = []; // Receive queue
this.sQ = []; // Send queue
this.header = [];
//Queue processing via intervals
this.process_interval = 0; //milliseconds
}
cancel_connected_timer() {
if (this.verify_connected_timer) {
clearTimeout(this.verify_connected_timer);
this.verify_connected_timer = 0;
}
}
async open(uri) {
const me = this;
// (re-)init
this.raw_packets = [];
this.rQ = [];
this.sQ = [];
this.header = [];
this.webtransport = null;
this.stream = null;
function handle(packet) {
me.packet_handler(packet);
}
this.verify_connected_timer = setTimeout(
() => handle(["error", "connection timed out", 0]),
CONNECT_TIMEOUT
);
// connect the socket
try {
// console.log("opening WebTransport connection to " + uri);
this.webtransport = new WebTransport(uri);
} catch (error) {
handle(["error", `${error}`, 0]);
return;
}
try {
// console.log("waiting for connection");
await this.webtransport.ready;
this.cancel_connected_timer();
} catch (e) {
console.error("connection failed: " + e);
handle(["error", e.toString()]);
this.cancel_connected_timer();
return;
}
this.webtransport.closed.then(() => {
handle(["close", "transport closed"])
})
.catch((e) => {
console.error("error closing WebTransport: " + e);
handle(["close", "error", e.toString()])
});
// console.log("creating stream");
this.stream = await this.webtransport.createBidirectionalStream();
// console.log("starting read loop with stream=" + this.stream);
this.read_loop().then(() => {
// console.log("read loop ended, closing");
handle(["close", "read loop ended"])
})
.catch((e) => {
console.error("error in read loop: " + e);
handle(["close", "read loop error", e.toString()])
});
this.writer = this.stream.writable.getWriter();
handle(["open"]);
// console.log("async open end");
}
async read_loop() {
const reader = this.stream.readable.getReader();
const me = this;
while (true) {
const {
value,
done
} = await reader.read();
if (done) {
break;
}
this.rQ.push(value);
setTimeout(() => me.process_receive_queue(), this.process_interval);
}
}
protocol_error(message) {
this.packet_handler(["error", message]);
console.error("protocol error: " + message);
this.close();
}
close() {
this.cancel_connected_timer();
const wt = this.webtransport;
if (wt) {
wt.closed.then(() => {
// console.log("closed WebTransport connection");
handle(["close", "WebTransport closed"])
})
.catch((e) => {
// console.log("error closing WebTransport connection: " + e);
handle(["close", "error closing WebTransport connection", e.toString()])
});
}
this.webtransport = null;
}
process_receive_queue() {
while (this.webtransport && this.do_process_receive_queue());
}
do_process_receive_queue() {
if (this.header.length < 8 && this.rQ.length > 0) {
//add from receive queue data to header until we get the 8 bytes we need:
while (this.header.length < 8 && this.rQ.length > 0) {
const slice = this.rQ[0];
const needed = 8 - this.header.length;
const n = Math.min(needed, slice.length);
this.header.push(...slice.subarray(0, n));
if (slice.length > needed) {
//replace the slice with what is left over:
this.rQ[0] = slice.subarray(n);
} else {
//this slice has been fully consumed already:
this.rQ.shift();
}
}
//verify the header format:
if (this.header[0] !== 80) {
let message = `invalid packet header format: ${this.header[0]}`;
if (this.header.length > 1) {
let hex = "";
for (let p of this.header) {
const v = p.toString(16);
hex += v.length < 2 ? `0${v}` : v;
}
message += `: 0x${hex}`;
}
this.protocol_error(message);
return false;
}
}
if (this.header.length < 8) {
//we need more data to continue
return false;
}
let proto_flags = this.header[1];
const proto_crypto = proto_flags & 0x2;
if (proto_crypto) {
throw "crypto packets not supported";
}
if (proto_flags & 0x8) {
//this flag is unused client-side, so just ignore it:
proto_flags = proto_flags & ~0x8;
}
if (proto_flags > 1 && proto_flags !== 0x10) {
this.protocol_error(`we can't handle this protocol flag yet: ${proto_flags}`);
return;
}
const level = this.header[2];
if (level & 0x20) {
this.protocol_error("lzo compression is not supported");
return false;
}
const index = this.header[3];
if (index >= 20) {
this.protocol_error(`invalid packet index: ${index}`);
return false;
}
let packet_size = [4, 5, 6, 7].reduce(
(accumulator, value) => accumulator * 0x1_00 + this.header[value],
0
);
// verify that we have enough data for the full payload:
let rsize = this.rQ.reduce(
(accumulator, value) => accumulator + value.length,
0
);
if (rsize < packet_size) {
return false;
}
// done parsing the header, the next packet will need a new one:
this.header = [];
let packet_data;
if (this.rQ[0].length === packet_size) {
//exact match: the payload is in a buffer already:
packet_data = this.rQ.shift();
} else {
//aggregate all the buffers into "packet_data" until we get exactly "packet_size" bytes:
packet_data = new Uint8Array(packet_size);
rsize = 0;
while (rsize < packet_size) {
const slice = this.rQ[0];
const needed = packet_size - rsize;
if (slice.length > needed) {
//add part of this slice:
packet_data.set(slice.subarray(0, needed), rsize);
rsize += needed;
this.rQ[0] = slice.subarray(needed);
} else {
//add this slice in full:
packet_data.set(slice, rsize);
rsize += slice.length;
this.rQ.shift();
}
}
}
//decompress it if needed:
if (level !== 0) {
let inflated;
if (level & 0x10) {
inflated = lz4.decode(packet_data);
} else if (level & 0x40) {
inflated = new Uint8Array(BrotliDecode(packet_data));
} else {
throw "zlib is no longer supported";
}
packet_data = inflated;
}
//save it for later? (partial raw packet)
if (index > 0) {
this.raw_packets[index] = packet_data;
if (this.raw_packets.length >= 4) {
this.protocol_error(`too many raw packets: ${this.raw_packets.length}`);
return false;
}
} else {
//decode raw packet string into objects:
let packet = null;
try {
if (proto_flags === 0x10) {
packet = rdecode(packet_data);
} else if (proto_flags === 0x1) {
throw `rencode legacy mode is not supported, protocol flag: ${proto_flags}`;
} else {
throw `invalid packet encoder flags ${proto_flags}`;
}
for (const index in this.raw_packets) {
packet[index] = this.raw_packets[index];
}
this.raw_packets = {};
} catch (error) {
//FIXME: maybe we should error out and disconnect here?
console.error("error decoding packet", error);
console.error(`packet=${packet_data}`);
console.error(`protocol flags=${proto_flags}`);
this.raw_packets = [];
return this.rQ.length > 0;
}
try {
// pass to our packet handler
this.packet_handler(packet);
} catch (error) {
//FIXME: maybe we should error out and disconnect here?
console.error(`error processing packet ${packet[0]}: ${error}`);
console.error(` packet data: ${packet_data}`)
}
}
return this.rQ.length > 0;
}
process_send_queue() {
while (this.sQ.length > 0 && this.webtransport) {
const packet = this.sQ.shift();
if (!packet) {
return;
}
let proto_flags = 0x10;
let bdata = null;
try {
bdata = rencode(packet);
} catch (error) {
console.error("Error: failed to encode packet:", packet);
console.error(error);
continue;
}
const payload_size = bdata.length;
const packet_data = new Uint8Array(payload_size + 8);
const level = 0;
//header:
packet_data[0] = "P".charCodeAt(0);
packet_data[1] = proto_flags;
packet_data[2] = level;
packet_data[3] = 0;
//size header:
for (let index = 0; index < 4; index++) {
packet_data[7 - index] = (payload_size >> (8 * index)) & 0xff;
}
packet_data.set(bdata, 8);
if (this.stream) {
this.writer.write(new Uint8Array(packet_data).buffer);
}
}
}
send(packet) {
this.sQ[this.sQ.length] = packet;
setTimeout(() => this.process_send_queue(), this.process_interval);
}
set_packet_handler(callback) {
this.packet_handler = callback;
}
set_cipher_in(caps, key) {
throw "not supported with WebTransport";
}
set_cipher_out(caps, key) {
throw "not supported with WebTransport";
}
}