fix: writing byte one at a time

src/__tests__/__snapshots__/stream-impersonator.test.ts.snap

@@ -47,6 +47,17 @@ impersonate-user: johndoe
 
BarÄö"
 `;
 
+exports[`StreamImpersonator handles binary data in body one byte at a time 1`] = `
+"POST / HTTP/1.1
+accept: application/json
+content-type: application/octet-stream
+content-length: 4
+authorization: Bearer service-account-token
+impersonate-user: johndoe
+
+Äö"
+`;
+
 exports[`StreamImpersonator handles body separator splitted to separate chunks 1`] = `
 "GET / HTTP/1.1
 accept: application/json

src/__tests__/stream-impersonator.test.ts

@@ -213,6 +213,43 @@ MwIDAQAB
     expect(destination.buffer.includes(Buffer.from([0x01, 0x02, 0x03, 0x42, 0x61, 0x72, 0xC3, 0x84, 0xC3, 0xB6]))).toBe(true);
   });
 
+  it("handles binary data in body one byte at a time", async () => {
+    parser.boredServer = boredServer;
+    parser.publicKey = jwtPublicKey;
+
+    const token = jwt.sign(
+      {
+        exp: Math.floor(Date.now() / 1000) + 60 * 60,
+        sub: "johndoe",
+        aud: [boredServer],
+      },
+      jwtPrivateKey,
+      { algorithm: "RS256" }
+    );
+
+    stream.pipe(parser).pipe(destination);
+
+    // Writing the headers as text
+    stream.write("POST / HTTP/1.1\r\n");
+    stream.write("Accept: application/json\r\n");
+    stream.write(`Authorization: Bearer ${token}\r\n`);
+    stream.write("Content-Type: application/octet-stream\r\nContent-Length: 4\r\n\r\n");
+
+    // Writing binary data as four Buffer chunks
+    // UTF8: Äö
+    stream.write(Buffer.from([0xC3]));
+    await delay(1);
+    stream.write(Buffer.from([0x84]));
+    await delay(1);
+    stream.write(Buffer.from([0xC3]));
+    await delay(1);
+    stream.write(Buffer.from([0xB6]));
+
+    expect(destination.buffer.toString()).toMatchSnapshot();
+    expect(destination.buffer.toString()).toContain("Äö");
+    expect(destination.buffer.includes(Buffer.from([0xC3, 0x84, 0xC3, 0xB6]))).toBe(true);
+  });
+
   it ("handles headers in one chunk, body in another", () => {
     parser.boredServer = boredServer;
     parser.publicKey = jwtPublicKey;

src/stream-impersonator.ts

@@ -23,7 +23,7 @@ export class StreamImpersonator extends Transform {
   private httpParser: HTTPParserJS;
   private upgrade = false;
   private getSaToken: GetSaToken;
-  private partialMessage: string = "";
+  private partialMessage: Buffer[] = [];
 
   constructor(getSaToken: GetSaToken) {
     super();
@@ -103,32 +103,34 @@ export class StreamImpersonator extends Transform {
     encoding: BufferEncoding,
     callback: TransformCallback,
   ): void {
-    const chunkStr = chunk.toString();
-
     if (this.upgrade) {
       this.push(chunk);
 
       return callback();
     }
 
-    this.partialMessage += chunkStr;
+    this.partialMessage.push(chunk);
 
     const handleError = (err: Error) => {
-      this.partialMessage = "";
+      this.partialMessage = [];
       logger.error("[IMPERSONATOR] Error parsing HTTP data: %s", String(err));
       throw err;
     };
 
     try {
-      const bytesParsed = this.httpParser.execute(
-        Buffer.from(this.partialMessage),
-      );
+      const bufferToParse = Buffer.concat(this.partialMessage);
+      const bytesParsed = this.httpParser.execute(bufferToParse);
+
+      if (bytesParsed !== bufferToParse.length) {
+        logger.warn("Only " + bytesParsed + "/" + bufferToParse.length + " bytes parsed of the chunk");
+      }
 
       if (bytesParsed instanceof Error) {
         return handleError(bytesParsed);
       }
 
-      this.partialMessage = this.partialMessage.slice(bytesParsed);
+      // TODO: We assume the whole chunk is always parsed
+      this.partialMessage.pop();
     } catch (err) {
       return handleError(err as Error);
     }