getsockopt

Returns the options set on a socket.

Format 

#include  <socket.h>

int getsockopt  (int s, int level, int
                optname, char *optval, int
                *optlen);

Arguments

s
A socket descriptor created by socket.
level
The protocol level for which the socket options are desired. It may have one of the following values:
SOL_SOCKET  Get the options at the socket level. 
p  Any protocol number. Get the options for protocol level p. See the <in.h> file for the various IPPROTO values. 
optname
Is interpreted by the protocol that is specified in the level. Options at each protocol level are documented with the protocol. See setsockopt in this section for socket level options.
optval
Points to a buffer in which the value of the specified option should be placed by getsockopt.
optlen
Points to an integer containing the size of the buffer pointed to by optval. On return, the integer will be modified to contain the actual size of the option value returned.

Description

This routine gets information on socket options. See the appropriate protocol for information on available options at each protocol level.

Return Values
0  Indicates success. 
-1  Indicates an error; errno is set to one of the following:

  • EBADF - The descriptor is invalid.

  • ENOTSOCK - The socket descriptor references a file, not a socket.

  • ENOPROTOOPT - The option is unknown or the protocol is unsupported.
 

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