Fix writableHighWaterMark==0 breaking on Node 20

Fixes #128

config.js

@@ -21,8 +21,6 @@ servers: [
 
 			// SSL options
 			rejectUnauthorized: true,
-
-			highWaterMark: 0, // disable node's internal bufferring to improve our timings (we always send full chunks, so bufferring by node isn't needed)
 		},
 		secure: false, // set to true to use SSL
 		user: '',

lib/nntp.js

@@ -84,21 +84,22 @@ function NNTP(opts, rawSpeedTracker) {
 	this.dataLength = 0;
 	this._connectRetries = opts.connectRetries;
 
-	var connectOpts = opts.connect;
+	var connectOpts = util.extend({
+		port: opts.secure ? 563 : 119,
+		readableHighWaterMark: 0, // disable buffering
+		writableHighWaterMark: 1 // Node 20 seems to go wonky with a value of 0, so use 1 instead
+	}, opts.connect);
 	// although the feature was added in node 12.10.0, it's crashy on Linux until 13.13.0 / 12.16.3
 	// reported as unstable on 15.7.0, so we'll disable it everywhere until we get more info on it: https://github.com/animetosho/Nyuu/issues/87
 	var supportsOnread = false;
-	if(supportsOnread || !opts.connect.port) {
-		connectOpts = util.extend({}, opts.connect);
-		this.opts = util.extend({}, this.opts, {connect: connectOpts});
-		if(!opts.connect.port)
-			connectOpts.port = opts.secure ? 563 : 119;
-		if(supportsOnread)
-			connectOpts.onread = this.opts.useThreads ? true : {
-				buffer: Buffer.allocUnsafe(4096),
-				callback: this._onDataStatic.bind(this)
-			};
-	}
+	if(supportsOnread)
+		connectOpts.onread = this.opts.useThreads ? true : {
+			buffer: Buffer.allocUnsafe(4096),
+			callback: this._onDataStatic.bind(this)
+		};
+	if(+process.version.replace(/\.\d+$/, '').replace(/^v/, '') < 8.4) // Node < 8.4.0
+		connectOpts.highWaterMark = 0;
+
 
 	this.postMethod = (opts.postMethod || '').toUpperCase();
 	if(!(this.postMethod in VALID_POST_CODES))