Windows: cannot connect while other clients are timing out

[Freeeaky]

It seems like it's not possible to connect to the server while other clients are timing out. Similarly, when clients send messages at this time, they are only received after a significant delay (>3 seconds).

Steps to reproduce:

• Clone repo, build demo applications
• Start server
• Start 3 clients and wait for them to connect
• Exit all 3 clients (=> causing them to timeout)
• Start another client

I have tested this on my machine & on an AWS-hosted server with similar results.

[gafferongames]

Does each client above have a unique port number, or are you reusing a port number shared with a timing out client?

[Freeeaky]

@gafferongames every client has a unique port number.

Looks like I found the issue, only needed to doubt Windows.. Apparently Windows is emitting ICMP packets about the connection failure - even though we are using UDP here. Here is a source code code snippet for netcode_socket_create:

#define SIO_UDP_CONNRESET _WSAIOW(IOC_VENDOR, 12)

#if NETCODE_PLATFORM == NETCODE_PLATFORM_WINDOWS
    BOOL bNewBehavior = FALSE;
    DWORD dwBytesReturned = 0;
    WSAIoctl(s->handle, SIO_UDP_CONNRESET, &bNewBehavior, sizeof bNewBehavior, NULL, 0, &dwBytesReturned, NULL, NULL);
#endif

With the fix in place, the issue mentioned above is solved.

Reading material, including the source of the fix:

• https://stackoverflow.com/questions/30749423/is-winsock-error-10054-wsaeconnreset-normal-with-udp-to-from-localhost
• https://stackoverflow.com/questions/34242622/windows-udp-sockets-recvfrom-fails-with-error-10054?rq=1

[gafferongames]

Very interesting

[gafferongames]

A similar fix has been applied to netcode, and will be merged shortly. Closing.