| GETPEEREID(3) | Library Functions Manual | GETPEEREID(3) | 
getpeereid —
#include <sys/types.h>
#include <unistd.h>
int
  
  getpeereid(int
    s, uid_t *euid,
    gid_t *egid);
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) has been called, or
  one returned from accept(2)
  after bind(2) and
  listen(2) have been called. If
  non-NULL, the effective used ID is placed in euid, and
  the effective group ID in egid.
The credentials returned to the accept(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 bind(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 bind(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.
getpeereid() is
  implemented in terms of the LOCAL_PEEREID
  unix(4) socket option.
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.
getpeereid() function fails if:
EBADF]ENOTSOCK]ENOTCONN]EINVAL]SOCK_STREAM, or the kernel returned invalid
    data.getpeereid() function appeared in
  NetBSD 5.0.
| August 8, 2007 | NetBSD 10.0 |