I have a C++ application with GUI that runs (on PC 1) just like a network game, and receives data packets from another computer (2) via WiFi (ad-hoc, so it’s quite reliable) at fairly regular intervals (like 40ms), once per loop on program (2). I use send/read.
Here is the problem:
– Packets are not always fully sent (but apparently you can simply keep send()ing the remaining data until all is sent, and thats works well)
– More importantly, packets are stacked in the socket during (1)’s loop until the read() occurs, and then there is no way to distinguish packets in the big stream of data, or know if you were already in the middle of a packet.
I tried to fix this with ID headers (you find an ID as first bytes and you know the length of the packet), but I often get lost (unknown ID : we are not at the beginning of the packet) and am forced to ignore all the remaining data.
So my question is:
Why do packets stack? (generally I have 400B of data whereas my packets are <100B long and fps (1) and (2) are not very different)
How can I have a more reliable way to receive actual packets, say, 80% of packets (discarding packet loss, it’s not a question of UDP/TCP)?
Would a separate thread for receiving packets work? (on (1), the server)
How do real-time network games to that (including multiple client management)?
Thanks in advance.
(Sorry I do not have the code here, but I tried to be as clear as I could)
Well:
1) UDP transfers MESSAGES, but is unreliable.
2) TCP transfers BYTE STREAMS, and is reliable.
UDP cannot reliably transfer messages. Anything more reliable requires a protocol on top of UDP.
TCP cannot transfer messages unless they are one byte long. Anything more complex requires a protocol on top of TCP.