Maximum buffer size on Winsock for sending one block of data over TCP / IP

[CryptoTuke]

I am working on an application where clients who know the IP address of the server and the port number on which it listens connect to the server via TCP / IP. The server provides a chat room service, which means that clients can exchange data with each other. Communication is secured using a cryptographic protocol. This protocol encrypts the data and sends it still in one block send, wheither you send 5kB or 50MB. According to the source code, the protocol should be limited to uint32_t. I'm trying to test it, and when I send 1GB of data, the data is sent fine, but when I try to send data larger than 2 GB, it returns a large negative number and doesn't send. I know that they could be divided into smaller parts and sent sequentially, but the protocol encrypts and sends the data in one block, so I'm adapting.

I want to ask, is the Winsock send buffer limited by any size? If yes? And is it possible to increase the buffer according to your needs? I read some forums or articles, but I couldn't answer my questions specifically.

 

[maybeimaleo]

This is the best answer I have seen:

"The maximum message packet size for a provider can be obtained by calling getsockopt with the optname parameter set to SO_MAX_MSG_SIZE to retrieve the value of socket option."

From here -

https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-send

My thinking is the buffer is set from the network adaptor and winsock is just a means of letting a protocol talk to each end of the connection.