No recvfrom in socket.jl

[jech]

It looks like there's no binding to recvfrom in the socket library, which makes it impossible to write UDP servers.

[ihnorton]

@jech there is no binding to recvfrom because all networking is done via libuv's UDP API. Here is a minimal server example:

@async begin
           s = UDPSocket()
           bind(s, ip"0.0.0.0", 10000)
           while true
               b = recv(s)
               print(bytestring(b))
           end
       end

(tested with echo "hello" | nc -4u -w0 127.0.0.1 10000)

[ihnorton]

Small clarification: on 0.3, use UdpSocket instead (note lowercase).

[ihnorton]

Documentation added in 1d8e162. Closing for now but if something is missing, leave a comment and we'll reopen.

[jech]

I must be missing something.

In order to write a UDP server, you need to know the address from which the packet was sent in order to send a reply. That's usually done with recvfrom.

How do you send a reply back to the client in Julia?

[ihnorton]

You are not missing anything - I was being dense, so thanks for explaining.

The source address is provided in the callback from libuv (see _uv_hook_recv in socket.jl and the on_read example in the libuv UDP section). We currently don't do anything with the address, but I will implement and propose an update.

[racinmat]

Hi, is there any way to send a reply back to the client in Julia?
I can't find anything for Julia 1.5.
The recvfrom is implemented, but you can't use that if the client does not have public IP, right?