/*-------------------------------------------------------------------------

 *

 * getpeereid.c

 *    get peer userid for UNIX-domain socket connection

 *

 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group

 *

 *

 * IDENTIFICATION

 *    src/port/getpeereid.c

 *

 *-------------------------------------------------------------------------

 */

#include "c.h"

#include <sys/param.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <unistd.h>

#ifdef HAVE_UCRED_H

#include <ucred.h>

#endif

#ifdef HAVE_SYS_UCRED_H

#include <sys/ucred.h>

#endif

/*

 * BSD-style getpeereid() for platforms that lack it.

 */

int

getpeereid(int sock, uid_t *uid, gid_t *gid)

{

#if defined(SO_PEERCRED)

  /* Linux: use getsockopt(SO_PEERCRED) */

  struct ucred peercred;

  socklen_t so_len = sizeof(peercred);

  if (getsockopt(sock, SOL_SOCKET, SO_PEERCRED, &peercred, &so_len) != 0 ||

    so_len != sizeof(peercred))

    return -1;

  *uid = peercred.uid;

  *gid = peercred.gid;

  return 0;

#elif defined(LOCAL_PEERCRED)

  /* Debian with FreeBSD kernel: use getsockopt(LOCAL_PEERCRED) */

  struct xucred peercred;

  socklen_t so_len = sizeof(peercred);

  if (getsockopt(sock, 0, LOCAL_PEERCRED, &peercred, &so_len) != 0 ||

    so_len != sizeof(peercred) ||

    peercred.cr_version != XUCRED_VERSION)

    return -1;

  *uid = peercred.cr_uid;

  *gid = peercred.cr_gid;

  return 0;

#elif defined(HAVE_GETPEERUCRED)

  /* Solaris: use getpeerucred() */

  ucred_t    *ucred;

  ucred = NULL;       /* must be initialized to NULL */

  if (getpeerucred(sock, &ucred) == -1)

    return -1;

  *uid = ucred_geteuid(ucred);

  *gid = ucred_getegid(ucred);

  ucred_free(ucred);

  if (*uid == (uid_t) (-1) || *gid == (gid_t) (-1))

    return -1;

  return 0;

#else

  /* No implementation available on this platform */

  errno = ENOSYS;

  return -1;

#endif

}