109 lines
3.4 KiB
TypeScript
109 lines
3.4 KiB
TypeScript
import type { ServerChannel } from "ssh2";
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const pullRate = process.env.KEYBOARD_PULLING_RATE
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? parseInt(process.env.KEYBOARD_PULLING_RATE)
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: 5;
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const leftEscape = "\x1B[D";
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const rightEscape = "\x1B[C";
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const ourBackspace = "\u0008";
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const clientBackspace = "\x7F";
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export async function readFromKeyboard(
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stream: ServerChannel,
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disableEcho: boolean = false,
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): Promise<string> {
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let promise: (value: string | PromiseLike<string>) => void;
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let line = "";
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let lineIndex = 0;
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async function eventLoop(): Promise<any> {
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const readStreamDataBuf = stream.read();
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if (readStreamDataBuf == null) return setTimeout(eventLoop, pullRate);
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const readStreamData = readStreamDataBuf.toString();
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// Fixes several bugs (incl. potential social eng. exploits, ssh-copy-id being broken, etc)
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for (const character of readStreamData.split("")) {
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if (character == "\x03") {
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stream.write("^C");
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return promise("");
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} else if (character == "\r" || character == "\n") {
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return promise(line.replace("\r", ""));
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} else if (character == clientBackspace) {
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if (line.length == 0) return setTimeout(eventLoop, pullRate); // Here because if we do it in the parent if statement, shit breaks
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line = line.substring(0, lineIndex - 1) + line.substring(lineIndex);
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if (!disableEcho) {
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const deltaCursor = line.length - lineIndex;
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if (deltaCursor == line.length)
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return setTimeout(eventLoop, pullRate);
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if (deltaCursor < 0) {
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// Use old technique if the delta is < 0, as the new one is tailored to the start + 1 to end - 1
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stream.write(ourBackspace + " " + ourBackspace);
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} else {
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// Jump forward to the front, and remove the last character
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stream.write(rightEscape.repeat(deltaCursor) + " " + ourBackspace);
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// Go backwards & rerender text & go backwards again (wtf?)
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stream.write(
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leftEscape.repeat(deltaCursor + 1) +
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line.substring(lineIndex - 1) +
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leftEscape.repeat(deltaCursor + 1),
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);
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}
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lineIndex -= 1;
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}
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} else if (character == "\x1B") {
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if (character == rightEscape) {
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if (lineIndex + 1 > line.length)
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return setTimeout(eventLoop, pullRate);
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lineIndex += 1;
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} else if (character == leftEscape) {
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if (lineIndex - 1 < 0) return setTimeout(eventLoop, pullRate);
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lineIndex -= 1;
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} else {
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return setTimeout(eventLoop, pullRate);
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}
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if (!disableEcho) stream.write(character);
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} else {
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lineIndex += 1;
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// There isn't a splice method for String prototypes. So, ugh:
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line =
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line.substring(0, lineIndex - 1) +
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character +
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line.substring(lineIndex - 1);
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if (!disableEcho) {
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let deltaCursor = line.length - lineIndex;
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// wtf?
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if (deltaCursor < 0) {
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console.log(
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"FIXME: somehow, our deltaCursor value is negative! please investigate me",
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);
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deltaCursor = 0;
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}
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stream.write(
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line.substring(lineIndex - 1) + leftEscape.repeat(deltaCursor),
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);
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}
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}
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}
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setTimeout(eventLoop, pullRate);
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}
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return new Promise(resolve => {
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setTimeout(eventLoop, pullRate);
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promise = resolve;
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});
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}
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