eliasson / pieces Goto Github PK

As documented, the client sometimes freezes upon startup; I tried to debug this and managed to root out the cause.

In a nutshell, we're running into an infinite loop trying to parse the handshake response:

  async def _handshake(self):
        """
        Send the initial handshake to the remote peer and wait for the peer
        to respond with its handshake.
        """
        self.writer.write(Handshake(self.info_hash, self.peer_id).encode())
        await self.writer.drain()

        buf = b''
        while len(buf) < Handshake.length:
            buf = await self.reader.read(PeerStreamIterator.CHUNK_SIZE)

When debugging, I noticed that the len(buf) stays at 0 at all times during the occasional freeze, thus creating the infinite loop. I'm not entirely surely if it's a problem with our parsing methods, or if the handshake from that one peer was indeed invalid.

That said, I think we can easily mitigate this issue by hardcoding a retry limit. I've attempted a fix in #2 in conjunction with main feature in that PR, and things seemed to work fine (i.e, we can download a torrent without freezing).

Dear eliasson:

I have recently been learning how to implement a P2P client through your blog and GitHub repo. However, I encountered numerous network issues when testing the downloads. I have browsed through many answers on Stack Overflow and even used ChatGPT, but none of them resolved the issue. So, I cloned your code and attempted to download the 'ubuntu' file in the 'tests' directory. Unfortunately, I faced the same problems. During the file download process, I encountered the following error messages:

1. ConnectionError: Unable to connect to tracker: status code 502
2. ConnectionError: Unable to connect to tracker: d14:failure reason63:Requested download is not authorized for use with this tracker.e
3. OSError: [WinError 121] The timeout for the semaphore has expired.
4. async for message in PeerStreamIterator(self.reader, buffer):
    TypeError: 'async for' received an object from __aiter__ that does not implement __anext__: coroutine

Have you encountered such an issue while implementing it? If you have, how did you resolve it? I would greatly appreciate any insights you can provide.

English is not my native language, if there is any offsen,please forgive me.