fix: len(buf) => cap(buf)

[BaiZe1998]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update
• Go Version Update
• Dependency Update

Description

len(buf) must equal to 0 for AvailableBuffer()

// AvailableBuffer returns an empty buffer with b.Available() capacity.
// This buffer is intended to be appended to and
// passed to an immediately succeeding [Writer.Write] call.
// The buffer is only valid until the next write operation on b.
func (b *Writer) AvailableBuffer() []byte {
	return b.buf[b.n:][:0]
}

i think the len(buf) may switch to cap(buf) ?

https://github.com/gorilla/websocket/blob/main/server.go#L208

buf := brw.Writer.AvailableBuffer()

var writeBuf []byte
if u.WriteBufferPool == nil && u.WriteBufferSize == 0 && len(buf) >= maxFrameHeaderSize+256 {
    // Reuse hijacked write buffer as connection buffer.
    writeBuf = buf
}

Related Tickets & Documents

• Related Issue #
• Closes #

Added/updated tests?

• Yes
• No, and this is why: please replace this line with details on why tests
  have not been included
• I need help with writing tests

Run verifications and test

• make verify is passing
• make test is passing