handle incomplete MSG_WAITALL during tcp receive

[Kethen]

Addresses #185 by handling incomplete TCP recv despite MSG_WAITALL

Fixes running the launcher inside of wine as well as the rare instances where this happens natively.

       MSG_WAITALL (since Linux 2.2)
              This flag requests that the operation block until the full request is satisfied.
              However, the call may still return less data than requested if a signal is caught,
              an error or disconnect occurs, or the next data to  be  re‐ceived is of a different type
              than that returned.  This flag has no effect for datagram sockets.

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[Kethen]

Added size checks for TCP MSG_WAITALL recv when incoming sizes are known

[Neptnium]

@Kethen Just tested your most recent changes !
With the poc mentioned in #185 it still crashed with the logs:

...
[23/5/2026 20:18:42] [DEBUG] (Proxy) Game Connected!
[23/5/2026 20:18:42] [DEBUG] Starting UDP receive loop
[23/5/2026 20:18:43] [ERROR] zlib uncompress() failed (code: -3, message: data error)
[23/5/2026 20:18:43] [ERROR] Decompression failed

(This was tested on Windows 11)

[Kethen]

@Kethen Just tested your most recent changes ! With the poc mentioned in #185 it still crashed with the logs:

...
[23/5/2026 20:18:42] [DEBUG] (Proxy) Game Connected!
[23/5/2026 20:18:42] [DEBUG] Starting UDP receive loop
[23/5/2026 20:18:43] [ERROR] zlib uncompress() failed (code: -3, message: data error)
[23/5/2026 20:18:43] [ERROR] Decompression failed

(This was tested on Windows 11)

Interesting, that'd suggest unlike in WINE, when Windows sees the message, the data it received is truly invalid data

How did you reproduce the error in your testing? With the POC server plugin?

[Neptnium]

@Kethen exactly, I used the POV server plugin !