GETPEEREID(3)						   BSD Library Functions Manual 					     GETPEEREID(3)

NAME

     getpeereid -- get the effective credentials of a UNIX-domain peer

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/types.h>
     #include <unistd.h>

     int
     getpeereid(int s, uid_t *euid, gid_t *egid);

DESCRIPTION

     The getpeereid() function returns the effective user and group IDs of the peer connected to a UNIX-domain socket.	The argument s must be a
     UNIX-domain socket (unix(4)) of type SOCK_STREAM on which either connect(2) or listen(2) have been called.  The effective used ID is placed
     in euid, and the effective group ID in egid.

     The credentials returned to the listen(2) caller are those of its peer at the time it called connect(2); the credentials returned to the
     connect(2) caller are those of its peer at the time it called listen(2).  This mechanism is reliable; there is no way for either side to
     influence the credentials returned to its peer except by calling the appropriate system call (i.e., either connect(2) or listen(2)) under
     different effective credentials.

     One common use of this routine is for a UNIX-domain server to verify the credentials of its client.  Likewise, the client can verify the cre-
     dentials of the server.

IMPLEMENTATION NOTES

     On FreeBSD, getpeereid() is implemented in terms of the LOCAL_PEERCRED unix(4) socket option.

RETURN VALUES

     The getpeereid() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indi-
     cate the error.

ERRORS

     The getpeereid() function fails if:

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

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

     [ENOTCONN] 	The argument s does not refer to a socket on which connect(2) or listen(2) have been called.

     [EINVAL]		The argument s does not refer to a socket of type SOCK_STREAM, or the kernel returned invalid data.

SEE ALSO

     connect(2), getpeername(2), getsockname(2), getsockopt(2), listen(2), unix(4)

HISTORY

     The getpeereid() function appeared in FreeBSD 4.6.

BSD
								   July 15, 2001							       BSD