How do C++ functions handle socket options in network programming?

C provides socket option processing functions for network programming, and obtains and sets these options through functions. To get options use getsockopt() and to set options use setsockopt(). In practice, the keep-alive option SO_KEEPALIVE can be used to keep the client connection active. Other common options include SO_REUSEADDR to allow local address reuse, SO_BROADCAST to send broadcast packets, SO_LINGER to control the behavior of closing the socket, and SO_RCVBUF and SO_SNDBUF to set the receive and send buffer sizes.

C functions to handle socket options in network programming

In network programming, socket options allow developers Configure socket behavior. C provides a number of functions to get and set these options.

Get socket options

• getsockopt(): Gets a specific option value on a given socket .

  int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen);

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• level: The level of the option (e.g.SOL_SOCKET).
• optname: The name of the option (e.g.SO_KEEPALIVE).
• optval: Buffer of option value.
• optlen: Pointer to the length of the option value.

Set socket options

• ##setsockopt(): Sets the socket options on the given socket Specific option value.

  int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen);

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• sockfd: Socket descriptor.
• level: The level of the option.
• optname: The name of the option.
• optval: Buffer of option value.
• optlen: Option value length.

Practical case

SO_KEEPALIVEoption to enable the keepalive mechanism:

int setsockopt(server_sockfd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof(keepalive));

server_sockfdis the server socket descriptor andkeepaliveis an integer , representing the time in seconds to wait before sending a keepalive probe.

Other common options

• SO_REUSEADDR: Allows immediate reuse of local addresses.
• SO_BROADCAST: Allows the socket to send broadcast packets.
• SO_LINGER: Controls the behavior when closing the socket.
• SO_RCVBUF: Set the size of the socket receive buffer.
• SO_SNDBUF: Set the size of the socket send buffer.

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