From b0a53d78d69bd5565a3f3a084ef96eeb6ba5c761 Mon Sep 17 00:00:00 2001
From: Andre Klang <andre.klang@hiq.se>
Date: Sat, 2 Dec 2023 14:45:18 +0100
Subject: [PATCH] Minor refactor in socket-reader, and fixing issue when there
 are no bytes to read

---
 src/SimConnectSocket.ts | 89 +++++++++++++++++++++++------------------
 1 file changed, 49 insertions(+), 40 deletions(-)

diff --git a/src/SimConnectSocket.ts b/src/SimConnectSocket.ts
index 6dfce62..a9b7801 100644
--- a/src/SimConnectSocket.ts
+++ b/src/SimConnectSocket.ts
@@ -102,60 +102,69 @@ class SimConnectSocket extends Duplex {
     _onReadable() {
         while (!this._readingPaused) {
             // Are there bytes remaining on a pending message
-            if (this._pendingBodyLengthRemaining && this._appendPending()) {
-                return;
+            if (this._pendingBodyLengthRemaining) {
+                this._appendPending();
             }
 
-            let body: Buffer;
-            if (this._pendingBody.length) {
-                // Read message from the pending body
-                body = this._pendingBody;
+            // If there's no bytes remaining on a pending message, but there are in the pendingBody
+            if (!this._pendingBodyLengthRemaining && this._pendingBody.length) {
+                // Read message from the pending body, and send it
+                this._pushMessage(this._pendingBody);
                 this._pendingBody = Buffer.from([]);
-            } else {
-                // Read message length header
-                const lenBuf = this._socket.read(HEADER_LENGTH);
-                if (!lenBuf) return;
-                const bodyLength = lenBuf.readInt32LE() - HEADER_LENGTH;
-
-                // If expected body is longer than readable buffer
-                if (bodyLength > this._socket.readableLength) {
-                    this._pendingBodyLengthRemaining = bodyLength;
-                    this._appendPending();
-                    return; // wait for another _onReadable
-                }
-
-                // Read message body
-                body = this._socket.read(bodyLength);
-
-                if (!body) {
-                    // Put header back in read buffer
-                    this._socket.unshift(lenBuf);
-                    return;
-                }
+                return;
             }
 
-            const message: SimConnectMessage = {
-                // Mandatory fields
-                protocolVersion: body.readInt32LE(0),
-                packetTypeId: body.readInt32LE(4),
-                data: new RawBuffer(body.slice(8)),
-            };
+            // Read message length header
+            const lenBuf = this._socket.read(HEADER_LENGTH);
+            if (!lenBuf) return;
+            const bodyLength = lenBuf.readInt32LE() - HEADER_LENGTH;
+
+            // If expected body is longer than readable buffer
+            if (bodyLength > this._socket.readableLength) {
+                this._pendingBodyLengthRemaining = bodyLength;
+                this._appendPending();
+                return; // wait for another _onReadable
+            }
 
-            // Add object to read buffer
-            const pushOk = this.push(message);
+            // Read message body
+            const body = this._socket.read(bodyLength);
+
+            if (!body) {
+                // Put header back in read buffer
+                this._socket.unshift(lenBuf);
+                return;
+            }
 
-            // Pause reading if consumer is slow
-            if (!pushOk) this._readingPaused = true;
+            this._pushMessage(body);
         }
     }
 
     _appendPending() {
         const readLength = Math.min(this._pendingBodyLengthRemaining, this._socket.readableLength);
-        this._pendingBody = Buffer.concat([this._pendingBody, this._socket.read(readLength)]);
+
+        if (!readLength) return;
+
+        const appendBuf = this._socket.read(readLength);
+
+        if (!appendBuf) return;
+
+        this._pendingBody = Buffer.concat([this._pendingBody, appendBuf]);
         this._pendingBodyLengthRemaining -= readLength;
+    }
+
+    _pushMessage(body: Buffer) {
+        const message: SimConnectMessage = {
+            // Mandatory fields
+            protocolVersion: body.readInt32LE(0),
+            packetTypeId: body.readInt32LE(4),
+            data: new RawBuffer(body.slice(8)),
+        };
+
+        // Add object to read buffer
+        const pushOk = this.push(message);
 
-        // If there are still more to read, wait for another _onReadable
-        return !!this._pendingBodyLengthRemaining;
+        // Pause reading if consumer is slow
+        if (!pushOk) this._readingPaused = true;
     }
 
     _read() {