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# getpeername

    GETPEERNAME(2)                System Calls Manual               GETPEERNAME(2)

    NAME
         getpeername - get name of connected peer

    SYNOPSIS
         #include <sys/types.h>
         #include <sys/socket.h>

         int
         getpeername(int s, struct sockaddr *name, socklen_t *namelen);

    DESCRIPTION
         getpeername() returns the address information of the peer connected to
         socket s.  One common use occurs when a process inherits an open socket,
         such as TCP servers forked from inetd(8).  In this scenario,
         getpeername() is used to determine the connecting client's IP address.

         getpeername() takes three parameters:

         s Contains the file descriptor of the socket whose peer should be looked
         up.

         name Points to a sockaddr structure that will hold the address informa-
         tion for the connected peer.  Normal use requires one to use a structure
         specific to the protocol family in use, such as sockaddr_in (IPv4) or
         sockaddr_in6 (IPv6), cast to a (struct sockaddr *).

         For greater portability, especially with the newer protocol families, the
         new struct sockaddr_storage should be used.  sockaddr_storage is large
         enough to hold any of the other sockaddr_* variants.  On return, it can
         be cast to the correct sockaddr type, based the protocol family contained
         in its ss_family field.

         namelen Indicates the amount of space pointed to by name, in bytes.

         If address information for the local end of the socket is required, the
         getsockname(2) function should be used instead.

         If name does not point to enough space to hold the entire socket address,
         the result will be truncated to namelen bytes.

    RETURN VALUES
         If the call succeeds, a 0 is returned and namelen is set to the actual
         size of the socket address returned in name.  Otherwise, errno is set and
         a value of -1 is returned.

    ERRORS
         On failure, errno is set to one of the following:

         [EBADF]            The argument s is not a valid descriptor.

         [ENOTSOCK]         The argument s is a file, not a socket.

         [ENOTCONN]         The socket is not connected.

         [ENOBUFS]          Insufficient resources were available in the system to
                            perform the operation.

         [EFAULT]           The name parameter points to memory not in a valid
                            part of the process address space.

    SEE ALSO
         accept(2), bind(2), getsockname(2), getpeereid(2), socket(2)

    HISTORY
         The getpeername() function call appeared in 4.2BSD.

    BSD                              July 17, 1999                             BSD

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