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 lis

ten(2). This mechanism is reliable; there is no way for either side to influ

ence the credentials returned to its peer except by calling the appro

priate 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 credentials of the server.

IMPLEMENTATION NOTES

On FreeBSD, getpeereid() is implemented in terms of the LO

CAL_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 indicate
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 in

valid 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