UDPSocket()

General Usage
1

I have severe problems to listen to a port on which an UDP-Socket server sends packages.
I see the packages in Wireshark and my Python-Script can see the packages as well.
But I struggle to achieve the same in Julia.
Here a short snippet, that does not work. The process stucks in line data, addr = recvfrom(sock).

using Sockets

sock = Sockets.UDPSocket()
Base.bind(sock, ip"0.0.0.0", 59000)
println("Socket bound. Waiting for packet (blocking)...")

addr, data = Sockets.recvfrom(sock)   # direct, synchron, no async

println("✅ Received $(length(data)) bytes from $addr")
println("   Data: $(String(copy(data)))")
Base.close(sock)

Any ideas?

2

It works fine for me locally (same host). I sent the test packet with
echo -n "hello" | nc -u -w1 127.0.0.1 59000

Also from remote:
echo -n "hello" | nc -u -w1 dell.local 59000

3

both commands do not work for me.
And what would be the purpose?

4

This was in Ubuntu, are you using Windows or Mac if nc is not available? Someone using them could comment.

5

The following works :slight_smile: (AI Proton Lumo with my strong choaching :wink: )

using Sockets

ch = Channel{Tuple{Union{Nothing, Sockets.InetAddr}, Union{Nothing, Vector{UInt8}}}}(1)
udp_sock = Sockets.UDPSocket()
Base.bind(udp_sock, ip"0.0.0.0", 59000; reuseaddr=true)

# Voll qualifiziert: Base.Threads.@spawn
recv_task = Base.Threads.@spawn begin
    try
        addr, data = recvfrom(udp_sock)
        put!(ch, (addr, data))
    catch
        put!(ch, (nothing, nothing))
    end
end
println(ch)
addr, data = take!(ch)
close(ch)
println(data)

Base.close(udp_sock)
@info "done"

P.S.:
There exist an alternative to encapsulate the troublemaker: addr, data = recvfrom(udp_sock):

recv_task = Base.Threads.@async while running[]
# ...
end

Any arguments to decide which of them is the best, to enable a sound handling of InterruptException?