Found some bugs in the socketfiles code

[puellanivis]

When, I started up an allcat tcp listener with: allcat tcp://:8080 I got a log message: redirected: //[::]:8080. Looking at the code, I missed a Scheme: "tcp" in the tcpreader.go code.

When I went to fix that, I found a few other issues:

• there were some dial misspellings as dail.
• Open("tcp://:8080") will not properly cancel listening on a context cancel
• setForWriter and setForReader were poorly designed.
• How I was building url.URLs for filenames was kind of wonky.
• Putting packet_size as a parameter accepted for tcp: but unused, removes a special case for UDP
• setInt was not a useful helper function. It is a one-line function-call to a one-line function.
• getInt and getSize do not need to return a bool, none of them accept 0 as a valid value.
• don’t embed ipSocket instead, make it a named field. (There are weird receiver method exposure with these)
• for local addresses, use net.ResolveProtoAddr("proto", net.JoinHostPort(…)) rather than a flimsy self-implementation
• reuse the internal buffer as much as possible when setting packet sizes
• reuse the time.Ticker in throttling code, which also requires better channel draining hygiene.
• automatically call updateDelay when updating bitrate on throttler, rather than requiring the caller to call it themselves (it was always being called anyways)
• We don’t actually need to fully wrap the UDPConn in udpReader, we don’t do anything but redirect the calls, so they could just be done directly with embedding. It’s not our type, and we already leak receiver method implementations for local files, so this fits well.

[puellanivis]

After extensive testing, I think this is safe to commit. This will follow up with a PR on allcat to support an buffer-size and packet-size argument so that copying, so that you can set buffer to a multiple of a packet-size to ensure that a UDP stream does not get chunked wrong.

I’m thinking I should inpart reimplement files.Copy so that UDP streams are not inherently broken, and thus require setting a proper buffer size. We simply shouldn’t be dropping some parts of packets.