mplex stream numbers

[richardschneider]

According to https://github.com/libp2p/mplex#opening-a-new-stream

To open a new stream, first allocate a new unique stream ID; the session initiator allocates odd IDs and the session receiver allocates even IDs.

But it seems that js-ipfs is using even IDs when opening a new stream.

Here's the debug output when sending the Bitswap want list. Note that js-ipfs was told to connect to QmTp1fwYnJxc5rUEVM2xowcDiyR61J7yvmBRUQzT4g8MHs , so it is the initiator.

  libp2p:switch:dial dialing QmTp1fwYnJxc5rUEVM2xowcDiyR61J7yvmBRUQzT4g8MHs +12ms
  mplex:main:44875 createStream: 2 2 { halfOpen: true, initiator: true } +54s
  mplex:channel:2 open, halfOpen: true +0ms
  mplex:main:44875 _addChannel 2 +3ms
  mplex:channel:2 open: 2 +2ms
  mplex:main:44875 _send 16 0 +3ms
  mss:dialer     (10sse5) dialer handle conn +0ms
  mss:dialer     (10sse5) writing multicodec: /multistream/1.0.0 +4ms
  mplex:channel:2 write:  20 +20ms
  mplex:main:44875 _send 18 20 +18ms
  ipfs:mfs:lock read operation callback invoked +50ms
  ipfs:mfs:lock Finished read operation +1ms
  mplex:main:44875 _write 22 +8ms
  mplex:main:44875 _push 20 +1ms
  mss:dialer     (10sse5) received ack: /multistream/1.0.0 +15ms
  mss:dialer     (10sse5) handshake success +0ms
  mss:dialer     (10sse5) dialer select /ipfs/bitswap/1.1.0 +1ms
  mss:dialer     (10sse5) writing multicodec: /ipfs/bitswap/1.1.0 +7ms
  mplex:channel:2 write:  21 +20ms
  mplex:main:44875 _send 18 21 +10ms
  mplex:main:44875 _write 23 +17ms
  mplex:main:44875 _push 21 +1ms
  mss:dialer     (10sse5) received ack: /ipfs/bitswap/1.1.0 +19ms
  mplex:channel:2 write:  51 +20ms
  mplex:main:44875 _send 18 51 +2ms
  mplex:main:44875 _send 20 0 +3ms

[richardschneider]

@diasdavid I seem to remember this issue be mentioned months ago, but I can't find any reference to it.

[daviddias]

it might be due to incomplete work, see https://github.com/libp2p/js-libp2p-mplex/pulls //cc @jacobheun @vasco-santos

[jacobheun]

It looks like the initiator base id is just flipped. https://github.com/libp2p/js-libp2p-mplex/blob/v0.8.0/src/internals/index.js#L83. The base id is set to 0 instead of 1 and then the stream id is incremented by 2, which is why we're seeing 2 2 in the logs mplex:main:44875 createStream: 2 2 for the first stream.

Edit: After reviewing the flags, they are correct between both versions, the id on the js side looks to be the only issue.

[jacobheun]

There was an intended change to the mplex spec that never got merged, libp2p/mplex#3. It was just merged in a little while ago.

The js implementation does match the intended spec.