- deraadt@cvs.openbsd.org 2005/03/31 18:39:21

[openssh-git.git] / loginrec.c

/*
 * Copyright (c) 2000 Andre Lucas.  All rights reserved.
 * Portions copyright (c) 1998 Todd C. Miller
 * Portions copyright (c) 1996 Jason Downs
 * Portions copyright (c) 1996 Theo de Raadt
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * The btmp logging code is derived from login.c from util-linux and is under
 * the the following license:
 *
 * Copyright (c) 1980, 1987, 1988 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */


/**
 ** loginrec.c:  platform-independent login recording and lastlog retrieval
 **/

/*
 *  The new login code explained
 *  ============================
 *
 *  This code attempts to provide a common interface to login recording
 *  (utmp and friends) and last login time retrieval.
 *
 *  Its primary means of achieving this is to use 'struct logininfo', a
 *  union of all the useful fields in the various different types of
 *  system login record structures one finds on UNIX variants.
 *
 *  We depend on autoconf to define which recording methods are to be
 *  used, and which fields are contained in the relevant data structures
 *  on the local system. Many C preprocessor symbols affect which code
 *  gets compiled here.
 *
 *  The code is designed to make it easy to modify a particular
 *  recording method, without affecting other methods nor requiring so
 *  many nested conditional compilation blocks as were commonplace in
 *  the old code.
 *
 *  For login recording, we try to use the local system's libraries as
 *  these are clearly most likely to work correctly. For utmp systems
 *  this usually means login() and logout() or setutent() etc., probably
 *  in libutil, along with logwtmp() etc. On these systems, we fall back
 *  to writing the files directly if we have to, though this method
 *  requires very thorough testing so we do not corrupt local auditing
 *  information. These files and their access methods are very system
 *  specific indeed.
 *
 *  For utmpx systems, the corresponding library functions are
 *  setutxent() etc. To the author's knowledge, all utmpx systems have
 *  these library functions and so no direct write is attempted. If such
 *  a system exists and needs support, direct analogues of the [uw]tmp
 *  code should suffice.
 *
 *  Retrieving the time of last login ('lastlog') is in some ways even
 *  more problemmatic than login recording. Some systems provide a
 *  simple table of all users which we seek based on uid and retrieve a
 *  relatively standard structure. Others record the same information in
 *  a directory with a separate file, and others don't record the
 *  information separately at all. For systems in the latter category,
 *  we look backwards in the wtmp or wtmpx file for the last login entry
 *  for our user. Naturally this is slower and on busy systems could
 *  incur a significant performance penalty.
 *
 *  Calling the new code
 *  --------------------
 *
 *  In OpenSSH all login recording and retrieval is performed in
 *  login.c. Here you'll find working examples. Also, in the logintest.c
 *  program there are more examples.
 *
 *  Internal handler calling method
 *  -------------------------------
 *
 *  When a call is made to login_login() or login_logout(), both
 *  routines set a struct logininfo flag defining which action (log in,
 *  or log out) is to be taken. They both then call login_write(), which
 *  calls whichever of the many structure-specific handlers autoconf
 *  selects for the local system.
 *
 *  The handlers themselves handle system data structure specifics. Both
 *  struct utmp and struct utmpx have utility functions (see
 *  construct_utmp*()) to try to make it simpler to add extra systems
 *  that introduce new features to either structure.
 *
 *  While it may seem terribly wasteful to replicate so much similar
 *  code for each method, experience has shown that maintaining code to
 *  write both struct utmp and utmpx in one function, whilst maintaining
 *  support for all systems whether they have library support or not, is
 *  a difficult and time-consuming task.
 *
 *  Lastlog support proceeds similarly. Functions login_get_lastlog()
 *  (and its OpenSSH-tuned friend login_get_lastlog_time()) call
 *  getlast_entry(), which tries one of three methods to find the last
 *  login time. It uses local system lastlog support if it can,
 *  otherwise it tries wtmp or wtmpx before giving up and returning 0,
 *  meaning "tilt".
 *
 *  Maintenance
 *  -----------
 *
 *  In many cases it's possible to tweak autoconf to select the correct
 *  methods for a particular platform, either by improving the detection
 *  code (best), or by presetting DISABLE_<method> or CONF_<method>_FILE
 *  symbols for the platform.
 *
 *  Use logintest to check which symbols are defined before modifying
 *  configure.ac and loginrec.c. (You have to build logintest yourself
 *  with 'make logintest' as it's not built by default.)
 *
 *  Otherwise, patches to the specific method(s) are very helpful!
 */

#include "includes.h"

#include "ssh.h"
#include "xmalloc.h"
#include "loginrec.h"
#include "log.h"
#include "atomicio.h"
#include "packet.h"
#include "canohost.h"
#include "auth.h"
#include "buffer.h"

#ifdef HAVE_UTIL_H
# include <util.h>
#endif

#ifdef HAVE_LIBUTIL_H
# include <libutil.h>
#endif

RCSID("$Id: loginrec.c,v 1.67 2005/02/15 11:19:28 dtucker Exp $");

/**
 ** prototypes for helper functions in this file
 **/

#if HAVE_UTMP_H
void set_utmp_time(struct logininfo *li, struct utmp *ut);
void construct_utmp(struct logininfo *li, struct utmp *ut);
#endif

#ifdef HAVE_UTMPX_H
void set_utmpx_time(struct logininfo *li, struct utmpx *ut);
void construct_utmpx(struct logininfo *li, struct utmpx *ut);
#endif

int utmp_write_entry(struct logininfo *li);
int utmpx_write_entry(struct logininfo *li);
int wtmp_write_entry(struct logininfo *li);
int wtmpx_write_entry(struct logininfo *li);
int lastlog_write_entry(struct logininfo *li);
int syslogin_write_entry(struct logininfo *li);

int getlast_entry(struct logininfo *li);
int lastlog_get_entry(struct logininfo *li);
int wtmp_get_entry(struct logininfo *li);
int wtmpx_get_entry(struct logininfo *li);

extern Buffer loginmsg;

/* pick the shortest string */
#define MIN_SIZEOF(s1,s2) (sizeof(s1) < sizeof(s2) ? sizeof(s1) : sizeof(s2))

/**
 ** platform-independent login functions
 **/

/*
 * login_login(struct logininfo *) - Record a login
 *
 * Call with a pointer to a struct logininfo initialised with
 * login_init_entry() or login_alloc_entry()
 *
 * Returns:
 *  >0 if successful
 *  0  on failure (will use OpenSSH's logging facilities for diagnostics)
 */
int
login_login(struct logininfo *li)
{
        li->type = LTYPE_LOGIN;
        return (login_write(li));
}


/*
 * login_logout(struct logininfo *) - Record a logout
 *
 * Call as with login_login()
 *
 * Returns:
 *  >0 if successful
 *  0  on failure (will use OpenSSH's logging facilities for diagnostics)
 */
int
login_logout(struct logininfo *li)
{
        li->type = LTYPE_LOGOUT;
        return (login_write(li));
}

/*
 * login_get_lastlog_time(int) - Retrieve the last login time
 *
 * Retrieve the last login time for the given uid. Will try to use the
 * system lastlog facilities if they are available, but will fall back
 * to looking in wtmp/wtmpx if necessary
 *
 * Returns:
 *   0 on failure, or if user has never logged in
 *   Time in seconds from the epoch if successful
 *
 * Useful preprocessor symbols:
 *   DISABLE_LASTLOG: If set, *never* even try to retrieve lastlog
 *                    info
 *   USE_LASTLOG: If set, indicates the presence of system lastlog
 *                facilities. If this and DISABLE_LASTLOG are not set,
 *                try to retrieve lastlog information from wtmp/wtmpx.
 */
unsigned int
login_get_lastlog_time(const int uid)
{
        struct logininfo li;

        if (login_get_lastlog(&li, uid))
                return (li.tv_sec);
        else
                return (0);
}

/*
 * login_get_lastlog(struct logininfo *, int)   - Retrieve a lastlog entry
 *
 * Retrieve a logininfo structure populated (only partially) with
 * information from the system lastlog data, or from wtmp/wtmpx if no
 * system lastlog information exists.
 *
 * Note this routine must be given a pre-allocated logininfo.
 *
 * Returns:
 *  >0: A pointer to your struct logininfo if successful
 *  0  on failure (will use OpenSSH's logging facilities for diagnostics)
 */
struct logininfo *
login_get_lastlog(struct logininfo *li, const int uid)
{
        struct passwd *pw;

        memset(li, '\0', sizeof(*li));
        li->uid = uid;

        /*
         * If we don't have a 'real' lastlog, we need the username to
         * reliably search wtmp(x) for the last login (see
         * wtmp_get_entry().)
         */
        pw = getpwuid(uid);
        if (pw == NULL)
                fatal("%s: Cannot find account for uid %i", __func__, uid);

        /* No MIN_SIZEOF here - we absolutely *must not* truncate the
         * username (XXX - so check for trunc!) */
        strlcpy(li->username, pw->pw_name, sizeof(li->username));

        if (getlast_entry(li))
                return (li);
        else
                return (NULL);
}


/*
 * login_alloc_entry(int, char*, char*, char*)    - Allocate and initialise
 *                                                  a logininfo structure
 *
 * This function creates a new struct logininfo, a data structure
 * meant to carry the information required to portably record login info.
 *
 * Returns a pointer to a newly created struct logininfo. If memory
 * allocation fails, the program halts.
 */
struct
logininfo *login_alloc_entry(int pid, const char *username,
    const char *hostname, const char *line)
{
        struct logininfo *newli;

        newli = xmalloc(sizeof(*newli));
        login_init_entry(newli, pid, username, hostname, line);
        return (newli);
}


/* login_free_entry(struct logininfo *)    - free struct memory */
void
login_free_entry(struct logininfo *li)
{
        xfree(li);
}


/* login_init_entry(struct logininfo *, int, char*, char*, char*)
 *                                        - initialise a struct logininfo
 *
 * Populates a new struct logininfo, a data structure meant to carry
 * the information required to portably record login info.
 *
 * Returns: 1
 */
int
login_init_entry(struct logininfo *li, int pid, const char *username,
    const char *hostname, const char *line)
{
        struct passwd *pw;

        memset(li, 0, sizeof(*li));

        li->pid = pid;

        /* set the line information */
        if (line)
                line_fullname(li->line, line, sizeof(li->line));

        if (username) {
                strlcpy(li->username, username, sizeof(li->username));
                pw = getpwnam(li->username);
                if (pw == NULL) {
                        fatal("%s: Cannot find user \"%s\"", __func__, 
                            li->username);
                }
                li->uid = pw->pw_uid;
        }

        if (hostname)
                strlcpy(li->hostname, hostname, sizeof(li->hostname));

        return (1);
}

/* 
 * login_set_current_time(struct logininfo *)    - set the current time
 *
 * Set the current time in a logininfo structure. This function is
 * meant to eliminate the need to deal with system dependencies for
 * time handling.
 */
void
login_set_current_time(struct logininfo *li)
{
        struct timeval tv;

        gettimeofday(&tv, NULL);

        li->tv_sec = tv.tv_sec;
        li->tv_usec = tv.tv_usec;
}

/* copy a sockaddr_* into our logininfo */
void
login_set_addr(struct logininfo *li, const struct sockaddr *sa,
    const unsigned int sa_size)
{
        unsigned int bufsize = sa_size;

        /* make sure we don't overrun our union */
        if (sizeof(li->hostaddr) < sa_size)
                bufsize = sizeof(li->hostaddr);

        memcpy(&li->hostaddr.sa, sa, bufsize);
}


/**
 ** login_write: Call low-level recording functions based on autoconf
 ** results
 **/
int
login_write(struct logininfo *li)
{
#ifndef HAVE_CYGWIN
        if (geteuid() != 0) {
                logit("Attempt to write login records by non-root user (aborting)");
                return (1);
        }
#endif

        /* set the timestamp */
        login_set_current_time(li);
#ifdef USE_LOGIN
        syslogin_write_entry(li);
#endif
#ifdef USE_LASTLOG
        if (li->type == LTYPE_LOGIN)
                lastlog_write_entry(li);
#endif
#ifdef USE_UTMP
        utmp_write_entry(li);
#endif
#ifdef USE_WTMP
        wtmp_write_entry(li);
#endif
#ifdef USE_UTMPX
        utmpx_write_entry(li);
#endif
#ifdef USE_WTMPX
        wtmpx_write_entry(li);
#endif
#ifdef CUSTOM_SYS_AUTH_RECORD_LOGIN
        if (li->type == LTYPE_LOGIN && 
           !sys_auth_record_login(li->username,li->hostname,li->line, &loginmsg))
                logit("Writing login record failed for %s", li->username);
#endif
#ifdef SSH_AUDIT_EVENTS
        if (li->type == LTYPE_LOGIN)
                audit_session_open(li->line);
        else if (li->type == LTYPE_LOGOUT)
                audit_session_close(li->line);
#endif
        return (0);
}

#ifdef LOGIN_NEEDS_UTMPX
int
login_utmp_only(struct logininfo *li)
{
        li->type = LTYPE_LOGIN;
        login_set_current_time(li);
# ifdef USE_UTMP
        utmp_write_entry(li);
# endif
# ifdef USE_WTMP
        wtmp_write_entry(li);
# endif
# ifdef USE_UTMPX
        utmpx_write_entry(li);
# endif
# ifdef USE_WTMPX
        wtmpx_write_entry(li);
# endif
        return (0);
}
#endif

/**
 ** getlast_entry: Call low-level functions to retrieve the last login
 **                time.
 **/

/* take the uid in li and return the last login time */
int
getlast_entry(struct logininfo *li)
{
#ifdef USE_LASTLOG
        return(lastlog_get_entry(li));
#else /* !USE_LASTLOG */

#if defined(DISABLE_LASTLOG)
        /* On some systems we shouldn't even try to obtain last login
         * time, e.g. AIX */
        return (0);
# elif defined(USE_WTMP) && \
    (defined(HAVE_TIME_IN_UTMP) || defined(HAVE_TV_IN_UTMP))
        /* retrieve last login time from utmp */
        return (wtmp_get_entry(li));
# elif defined(USE_WTMPX) && \
    (defined(HAVE_TIME_IN_UTMPX) || defined(HAVE_TV_IN_UTMPX))
        /* If wtmp isn't available, try wtmpx */
        return (wtmpx_get_entry(li));
# else
        /* Give up: No means of retrieving last login time */
        return (0);
# endif /* DISABLE_LASTLOG */
#endif /* USE_LASTLOG */
}



/*
 * 'line' string utility functions
 *
 * These functions process the 'line' string into one of three forms:
 *
 * 1. The full filename (including '/dev')
 * 2. The stripped name (excluding '/dev')
 * 3. The abbreviated name (e.g. /dev/ttyp00 -> yp00
 *                               /dev/pts/1  -> ts/1 )
 *
 * Form 3 is used on some systems to identify a .tmp.? entry when
 * attempting to remove it. Typically both addition and removal is
 * performed by one application - say, sshd - so as long as the choice
 * uniquely identifies a terminal it's ok.
 */


/*
 * line_fullname(): add the leading '/dev/' if it doesn't exist make
 * sure dst has enough space, if not just copy src (ugh)
 */
char *
line_fullname(char *dst, const char *src, int dstsize)
{
        memset(dst, '\0', dstsize);
        if ((strncmp(src, "/dev/", 5) == 0) || (dstsize < (strlen(src) + 5)))
                strlcpy(dst, src, dstsize);
        else {
                strlcpy(dst, "/dev/", dstsize);
                strlcat(dst, src, dstsize);
        }
        return (dst);
}

/* line_stripname(): strip the leading '/dev' if it exists, return dst */
char *
line_stripname(char *dst, const char *src, int dstsize)
{
        memset(dst, '\0', dstsize);
        if (strncmp(src, "/dev/", 5) == 0)
                strlcpy(dst, src + 5, dstsize);
        else
                strlcpy(dst, src, dstsize);
        return (dst);
}

/* 
 * line_abbrevname(): Return the abbreviated (usually four-character)
 * form of the line (Just use the last <dstsize> characters of the
 * full name.)
 *
 * NOTE: use strncpy because we do NOT necessarily want zero
 * termination
 */
char *
line_abbrevname(char *dst, const char *src, int dstsize)
{
        size_t len;

        memset(dst, '\0', dstsize);

        /* Always skip prefix if present */
        if (strncmp(src, "/dev/", 5) == 0)
                src += 5;

#ifdef WITH_ABBREV_NO_TTY
        if (strncmp(src, "tty", 3) == 0)
                src += 3;
#endif

        len = strlen(src);

        if (len > 0) {
                if (((int)len - dstsize) > 0)
                        src +=  ((int)len - dstsize);

                /* note: _don't_ change this to strlcpy */
                strncpy(dst, src, (size_t)dstsize);
        }

        return (dst);
}

/**
 ** utmp utility functions
 **
 ** These functions manipulate struct utmp, taking system differences
 ** into account.
 **/

#if defined(USE_UTMP) || defined (USE_WTMP) || defined (USE_LOGIN)

/* build the utmp structure */
void
set_utmp_time(struct logininfo *li, struct utmp *ut)
{
# if defined(HAVE_TV_IN_UTMP)
        ut->ut_tv.tv_sec = li->tv_sec;
        ut->ut_tv.tv_usec = li->tv_usec;
# elif defined(HAVE_TIME_IN_UTMP)
        ut->ut_time = li->tv_sec;
# endif
}

void
construct_utmp(struct logininfo *li,
                    struct utmp *ut)
{
# ifdef HAVE_ADDR_V6_IN_UTMP
        struct sockaddr_in6 *sa6;
# endif

        memset(ut, '\0', sizeof(*ut));

        /* First fill out fields used for both logins and logouts */

# ifdef HAVE_ID_IN_UTMP
        line_abbrevname(ut->ut_id, li->line, sizeof(ut->ut_id));
# endif

# ifdef HAVE_TYPE_IN_UTMP
        /* This is done here to keep utmp constants out of struct logininfo */
        switch (li->type) {
        case LTYPE_LOGIN:
                ut->ut_type = USER_PROCESS;
#ifdef _UNICOS
                cray_set_tmpdir(ut);
#endif
                break;
        case LTYPE_LOGOUT:
                ut->ut_type = DEAD_PROCESS;
#ifdef _UNICOS
                cray_retain_utmp(ut, li->pid);
#endif
                break;
        }
# endif
        set_utmp_time(li, ut);

        line_stripname(ut->ut_line, li->line, sizeof(ut->ut_line));

# ifdef HAVE_PID_IN_UTMP
        ut->ut_pid = li->pid;
# endif

        /* If we're logging out, leave all other fields blank */
        if (li->type == LTYPE_LOGOUT)
                return;

        /*
         * These fields are only used when logging in, and are blank
         * for logouts.
         */

        /* Use strncpy because we don't necessarily want null termination */
        strncpy(ut->ut_name, li->username,
            MIN_SIZEOF(ut->ut_name, li->username));
# ifdef HAVE_HOST_IN_UTMP
        strncpy(ut->ut_host, li->hostname,
            MIN_SIZEOF(ut->ut_host, li->hostname));
# endif
# ifdef HAVE_ADDR_IN_UTMP
        /* this is just a 32-bit IP address */
        if (li->hostaddr.sa.sa_family == AF_INET)
                ut->ut_addr = li->hostaddr.sa_in.sin_addr.s_addr;
# endif
# ifdef HAVE_ADDR_V6_IN_UTMP
        /* this is just a 128-bit IPv6 address */
        if (li->hostaddr.sa.sa_family == AF_INET6) {
                sa6 = ((struct sockaddr_in6 *)&li->hostaddr.sa);
                memcpy(ut->ut_addr_v6, sa6->sin6_addr.s6_addr, 16);
                if (IN6_IS_ADDR_V4MAPPED(&sa6->sin6_addr)) {
                        ut->ut_addr_v6[0] = ut->ut_addr_v6[3];
                        ut->ut_addr_v6[1] = 0;
                        ut->ut_addr_v6[2] = 0;
                        ut->ut_addr_v6[3] = 0;
                }
        }
# endif
}
#endif /* USE_UTMP || USE_WTMP || USE_LOGIN */

/**
 ** utmpx utility functions
 **
 ** These functions manipulate struct utmpx, accounting for system
 ** variations.
 **/

#if defined(USE_UTMPX) || defined (USE_WTMPX)
/* build the utmpx structure */
void
set_utmpx_time(struct logininfo *li, struct utmpx *utx)
{
# if defined(HAVE_TV_IN_UTMPX)
        utx->ut_tv.tv_sec = li->tv_sec;
        utx->ut_tv.tv_usec = li->tv_usec;
# elif defined(HAVE_TIME_IN_UTMPX)
        utx->ut_time = li->tv_sec;
# endif
}

void
construct_utmpx(struct logininfo *li, struct utmpx *utx)
{
# ifdef HAVE_ADDR_V6_IN_UTMP
        struct sockaddr_in6 *sa6;
#  endif
        memset(utx, '\0', sizeof(*utx));

# ifdef HAVE_ID_IN_UTMPX
        line_abbrevname(utx->ut_id, li->line, sizeof(utx->ut_id));
# endif

        /* this is done here to keep utmp constants out of loginrec.h */
        switch (li->type) {
        case LTYPE_LOGIN:
                utx->ut_type = USER_PROCESS;
                break;
        case LTYPE_LOGOUT:
                utx->ut_type = DEAD_PROCESS;
                break;
        }
        line_stripname(utx->ut_line, li->line, sizeof(utx->ut_line));
        set_utmpx_time(li, utx);
        utx->ut_pid = li->pid;

        /* strncpy(): Don't necessarily want null termination */
        strncpy(utx->ut_name, li->username,
            MIN_SIZEOF(utx->ut_name, li->username));

        if (li->type == LTYPE_LOGOUT)
                return;

        /*
         * These fields are only used when logging in, and are blank
         * for logouts.
         */

# ifdef HAVE_HOST_IN_UTMPX
        strncpy(utx->ut_host, li->hostname,
            MIN_SIZEOF(utx->ut_host, li->hostname));
# endif
# ifdef HAVE_ADDR_IN_UTMPX
        /* this is just a 32-bit IP address */
        if (li->hostaddr.sa.sa_family == AF_INET)
                utx->ut_addr = li->hostaddr.sa_in.sin_addr.s_addr;
# endif
# ifdef HAVE_ADDR_V6_IN_UTMP
        /* this is just a 128-bit IPv6 address */
        if (li->hostaddr.sa.sa_family == AF_INET6) {
                sa6 = ((struct sockaddr_in6 *)&li->hostaddr.sa);
                memcpy(ut->ut_addr_v6, sa6->sin6_addr.s6_addr, 16);
                if (IN6_IS_ADDR_V4MAPPED(&sa6->sin6_addr)) {
                        ut->ut_addr_v6[0] = ut->ut_addr_v6[3];
                        ut->ut_addr_v6[1] = 0;
                        ut->ut_addr_v6[2] = 0;
                        ut->ut_addr_v6[3] = 0;
                }
        }
# endif
# ifdef HAVE_SYSLEN_IN_UTMPX
        /* ut_syslen is the length of the utx_host string */
        utx->ut_syslen = MIN(strlen(li->hostname), sizeof(utx->ut_host));
# endif
}
#endif /* USE_UTMPX || USE_WTMPX */

/**
 ** Low-level utmp functions
 **/

/* FIXME: (ATL) utmp_write_direct needs testing */
#ifdef USE_UTMP

/* if we can, use pututline() etc. */
# if !defined(DISABLE_PUTUTLINE) && defined(HAVE_SETUTENT) && \
        defined(HAVE_PUTUTLINE)
#  define UTMP_USE_LIBRARY
# endif


/* write a utmp entry with the system's help (pututline() and pals) */
# ifdef UTMP_USE_LIBRARY
static int
utmp_write_library(struct logininfo *li, struct utmp *ut)
{
        setutent();
        pututline(ut);
#  ifdef HAVE_ENDUTENT
        endutent();
#  endif
        return (1);
}
# else /* UTMP_USE_LIBRARY */

/* 
 * Write a utmp entry direct to the file
 * This is a slightly modification of code in OpenBSD's login.c
 */
static int
utmp_write_direct(struct logininfo *li, struct utmp *ut)
{
        struct utmp old_ut;
        register int fd;
        int tty;

        /* FIXME: (ATL) ttyslot() needs local implementation */

#if defined(HAVE_GETTTYENT)
        struct ttyent *ty;

        tty=0;
        setttyent();
        while (NULL != (ty = getttyent())) {
                tty++;
                if (!strncmp(ty->ty_name, ut->ut_line, sizeof(ut->ut_line)))
                        break;
        }
        endttyent();

        if (NULL == ty) {
                logit("%s: tty not found", __func__);
                return (0);
        }
#else /* FIXME */

        tty = ttyslot(); /* seems only to work for /dev/ttyp? style names */

#endif /* HAVE_GETTTYENT */

        if (tty > 0 && (fd = open(UTMP_FILE, O_RDWR|O_CREAT, 0644)) >= 0) {
                off_t pos, ret;

                pos = (off_t)tty * sizeof(struct utmp);
                if ((ret = lseek(fd, pos, SEEK_SET)) == -1) {
                        logit("%s: lseek: %s", __func__, strerror(errno));
                        return (0);
                }
                if (ret != pos) {
                        logit("%s: Couldn't seek to tty %d slot in %s", 
                            __func__, tty, UTMP_FILE);
                        return (0);
                }
                /*
                 * Prevent luser from zero'ing out ut_host.
                 * If the new ut_line is empty but the old one is not
                 * and ut_line and ut_name match, preserve the old ut_line.
                 */
                if (atomicio(read, fd, &old_ut, sizeof(old_ut)) == sizeof(old_ut) &&
                    (ut->ut_host[0] == '\0') && (old_ut.ut_host[0] != '\0') &&
                    (strncmp(old_ut.ut_line, ut->ut_line, sizeof(ut->ut_line)) == 0) &&
                    (strncmp(old_ut.ut_name, ut->ut_name, sizeof(ut->ut_name)) == 0))
                        memcpy(ut->ut_host, old_ut.ut_host, sizeof(ut->ut_host));

                if ((ret = lseek(fd, pos, SEEK_SET)) == -1) {
                        logit("%s: lseek: %s", __func__, strerror(errno));
                        return (0);
                }
                if (ret != pos) {
                        logit("%s: Couldn't seek to tty %d slot in %s",
                            __func__, tty, UTMP_FILE);
                        return (0);
                }
                if (atomicio(vwrite, fd, ut, sizeof(*ut)) != sizeof(*ut)) {
                        logit("%s: error writing %s: %s", __func__,
                            UTMP_FILE, strerror(errno));
                }

                close(fd);
                return (1);
        } else {
                return (0);
        }
}
# endif /* UTMP_USE_LIBRARY */

static int
utmp_perform_login(struct logininfo *li)
{
        struct utmp ut;

        construct_utmp(li, &ut);
# ifdef UTMP_USE_LIBRARY
        if (!utmp_write_library(li, &ut)) {
                logit("%s: utmp_write_library() failed", __func__);
                return (0);
        }
# else
        if (!utmp_write_direct(li, &ut)) {
                logit("%s: utmp_write_direct() failed", __func__);
                return (0);
        }
# endif
        return (1);
}


static int
utmp_perform_logout(struct logininfo *li)
{
        struct utmp ut;

        construct_utmp(li, &ut);
# ifdef UTMP_USE_LIBRARY
        if (!utmp_write_library(li, &ut)) {
                logit("%s: utmp_write_library() failed", __func__);
                return (0);
        }
# else
        if (!utmp_write_direct(li, &ut)) {
                logit("%s: utmp_write_direct() failed", __func__);
                return (0);
        }
# endif
        return (1);
}


int
utmp_write_entry(struct logininfo *li)
{
        switch(li->type) {
        case LTYPE_LOGIN:
                return (utmp_perform_login(li));

        case LTYPE_LOGOUT:
                return (utmp_perform_logout(li));

        default:
                logit("%s: invalid type field", __func__);
                return (0);
        }
}
#endif /* USE_UTMP */


/**
 ** Low-level utmpx functions
 **/

/* not much point if we don't want utmpx entries */
#ifdef USE_UTMPX

/* if we have the wherewithall, use pututxline etc. */
# if !defined(DISABLE_PUTUTXLINE) && defined(HAVE_SETUTXENT) && \
        defined(HAVE_PUTUTXLINE)
#  define UTMPX_USE_LIBRARY
# endif


/* write a utmpx entry with the system's help (pututxline() and pals) */
# ifdef UTMPX_USE_LIBRARY
static int
utmpx_write_library(struct logininfo *li, struct utmpx *utx)
{
        setutxent();
        pututxline(utx);

#  ifdef HAVE_ENDUTXENT
        endutxent();
#  endif
        return (1);
}

# else /* UTMPX_USE_LIBRARY */

/* write a utmp entry direct to the file */
static int
utmpx_write_direct(struct logininfo *li, struct utmpx *utx)
{
        logit("%s: not implemented!", __func__);
        return (0);
}
# endif /* UTMPX_USE_LIBRARY */

static int
utmpx_perform_login(struct logininfo *li)
{
        struct utmpx utx;

        construct_utmpx(li, &utx);
# ifdef UTMPX_USE_LIBRARY
        if (!utmpx_write_library(li, &utx)) {
                logit("%s: utmp_write_library() failed", __func__);
                return (0);
        }
# else
        if (!utmpx_write_direct(li, &ut)) {
                logit("%s: utmp_write_direct() failed", __func__);
                return (0);
        }
# endif
        return (1);
}


static int
utmpx_perform_logout(struct logininfo *li)
{
        struct utmpx utx;

        construct_utmpx(li, &utx);
# ifdef HAVE_ID_IN_UTMPX
        line_abbrevname(utx.ut_id, li->line, sizeof(utx.ut_id));
# endif
# ifdef HAVE_TYPE_IN_UTMPX
        utx.ut_type = DEAD_PROCESS;
# endif

# ifdef UTMPX_USE_LIBRARY
        utmpx_write_library(li, &utx);
# else
        utmpx_write_direct(li, &utx);
# endif
        return (1);
}

int
utmpx_write_entry(struct logininfo *li)
{
        switch(li->type) {
        case LTYPE_LOGIN:
                return (utmpx_perform_login(li));
        case LTYPE_LOGOUT:
                return (utmpx_perform_logout(li));
        default:
                logit("%s: invalid type field", __func__);
                return (0);
        }
}
#endif /* USE_UTMPX */


/**
 ** Low-level wtmp functions
 **/

#ifdef USE_WTMP

/* 
 * Write a wtmp entry direct to the end of the file
 * This is a slight modification of code in OpenBSD's logwtmp.c
 */
static int
wtmp_write(struct logininfo *li, struct utmp *ut)
{
        struct stat buf;
        int fd, ret = 1;

        if ((fd = open(WTMP_FILE, O_WRONLY|O_APPEND, 0)) < 0) {
                logit("%s: problem writing %s: %s", __func__,
                    WTMP_FILE, strerror(errno));
                return (0);
        }
        if (fstat(fd, &buf) == 0)
                if (atomicio(vwrite, fd, ut, sizeof(*ut)) != sizeof(*ut)) {
                        ftruncate(fd, buf.st_size);
                        logit("%s: problem writing %s: %s", __func__,
                            WTMP_FILE, strerror(errno));
                        ret = 0;
                }
        close(fd);
        return (ret);
}

static int
wtmp_perform_login(struct logininfo *li)
{
        struct utmp ut;

        construct_utmp(li, &ut);
        return (wtmp_write(li, &ut));
}


static int
wtmp_perform_logout(struct logininfo *li)
{
        struct utmp ut;

        construct_utmp(li, &ut);
        return (wtmp_write(li, &ut));
}


int
wtmp_write_entry(struct logininfo *li)
{
        switch(li->type) {
        case LTYPE_LOGIN:
                return (wtmp_perform_login(li));
        case LTYPE_LOGOUT:
                return (wtmp_perform_logout(li));
        default:
                logit("%s: invalid type field", __func__);
                return (0);
        }
}


/* 
 * Notes on fetching login data from wtmp/wtmpx
 *
 * Logouts are usually recorded with (amongst other things) a blank
 * username on a given tty line.  However, some systems (HP-UX is one)
 * leave all fields set, but change the ut_type field to DEAD_PROCESS.
 *
 * Since we're only looking for logins here, we know that the username
 * must be set correctly. On systems that leave it in, we check for
 * ut_type==USER_PROCESS (indicating a login.)
 *
 * Portability: Some systems may set something other than USER_PROCESS
 * to indicate a login process. I don't know of any as I write. Also,
 * it's possible that some systems may both leave the username in
 * place and not have ut_type.
 */

/* return true if this wtmp entry indicates a login */
static int
wtmp_islogin(struct logininfo *li, struct utmp *ut)
{
        if (strncmp(li->username, ut->ut_name,
            MIN_SIZEOF(li->username, ut->ut_name)) == 0) {
# ifdef HAVE_TYPE_IN_UTMP
                if (ut->ut_type & USER_PROCESS)
                        return (1);
# else
                return (1);
# endif
        }
        return (0);
}

int
wtmp_get_entry(struct logininfo *li)
{
        struct stat st;
        struct utmp ut;
        int fd, found = 0;

        /* Clear the time entries in our logininfo */
        li->tv_sec = li->tv_usec = 0;

        if ((fd = open(WTMP_FILE, O_RDONLY)) < 0) {
                logit("%s: problem opening %s: %s", __func__, 
                    WTMP_FILE, strerror(errno));
                return (0);
        }
        if (fstat(fd, &st) != 0) {
                logit("%s: couldn't stat %s: %s", __func__, 
                    WTMP_FILE, strerror(errno));
                close(fd);
                return (0);
        }

        /* Seek to the start of the last struct utmp */
        if (lseek(fd, -(off_t)sizeof(struct utmp), SEEK_END) == -1) {
                /* Looks like we've got a fresh wtmp file */
                close(fd);
                return (0);
        }

        while (!found) {
                if (atomicio(read, fd, &ut, sizeof(ut)) != sizeof(ut)) {
                        logit("%s: read of %s failed: %s", __func__, 
                            WTMP_FILE, strerror(errno));
                        close (fd);
                        return (0);
                }
                if ( wtmp_islogin(li, &ut) ) {
                        found = 1;
                        /*
                         * We've already checked for a time in struct
                         * utmp, in login_getlast()
                         */
# ifdef HAVE_TIME_IN_UTMP
                        li->tv_sec = ut.ut_time;
# else
#  if HAVE_TV_IN_UTMP
                        li->tv_sec = ut.ut_tv.tv_sec;
#  endif
# endif
                        line_fullname(li->line, ut.ut_line,
                            MIN_SIZEOF(li->line, ut.ut_line));
# ifdef HAVE_HOST_IN_UTMP
                        strlcpy(li->hostname, ut.ut_host,
                            MIN_SIZEOF(li->hostname, ut.ut_host));
# endif
                        continue;
                }
                /* Seek back 2 x struct utmp */
                if (lseek(fd, -(off_t)(2 * sizeof(struct utmp)), SEEK_CUR) == -1) {
                        /* We've found the start of the file, so quit */
                        close(fd);
                        return (0);
                }
        }

        /* We found an entry. Tidy up and return */
        close(fd);
        return (1);
}
# endif /* USE_WTMP */


/**
 ** Low-level wtmpx functions
 **/

#ifdef USE_WTMPX
/*
 * Write a wtmpx entry direct to the end of the file
 * This is a slight modification of code in OpenBSD's logwtmp.c
 */
static int
wtmpx_write(struct logininfo *li, struct utmpx *utx)
{
#ifndef HAVE_UPDWTMPX
        struct stat buf;
        int fd, ret = 1;

        if ((fd = open(WTMPX_FILE, O_WRONLY|O_APPEND, 0)) < 0) {
                logit("%s: problem opening %s: %s", __func__, 
                    WTMPX_FILE, strerror(errno));
                return (0);
        }

        if (fstat(fd, &buf) == 0)
                if (atomicio(vwrite, fd, utx, sizeof(*utx)) != sizeof(*utx)) {
                        ftruncate(fd, buf.st_size);
                        logit("%s: problem writing %s: %s", __func__,
                            WTMPX_FILE, strerror(errno));
                        ret = 0;
                }
        close(fd);

        return (ret);
#else
        updwtmpx(WTMPX_FILE, utx);
        return (1);
#endif
}


static int
wtmpx_perform_login(struct logininfo *li)
{
        struct utmpx utx;

        construct_utmpx(li, &utx);
        return (wtmpx_write(li, &utx));
}


static int
wtmpx_perform_logout(struct logininfo *li)
{
        struct utmpx utx;

        construct_utmpx(li, &utx);
        return (wtmpx_write(li, &utx));
}


int
wtmpx_write_entry(struct logininfo *li)
{
        switch(li->type) {
        case LTYPE_LOGIN:
                return (wtmpx_perform_login(li));
        case LTYPE_LOGOUT:
                return (wtmpx_perform_logout(li));
        default:
                logit("%s: invalid type field", __func__);
                return (0);
        }
}

/* Please see the notes above wtmp_islogin() for information about the
   next two functions */

/* Return true if this wtmpx entry indicates a login */
static int
wtmpx_islogin(struct logininfo *li, struct utmpx *utx)
{
        if (strncmp(li->username, utx->ut_name,
            MIN_SIZEOF(li->username, utx->ut_name)) == 0 ) {
# ifdef HAVE_TYPE_IN_UTMPX
                if (utx->ut_type == USER_PROCESS)
                        return (1);
# else
                return (1);
# endif
        }
        return (0);
}


int
wtmpx_get_entry(struct logininfo *li)
{
        struct stat st;
        struct utmpx utx;
        int fd, found=0;

        /* Clear the time entries */
        li->tv_sec = li->tv_usec = 0;

        if ((fd = open(WTMPX_FILE, O_RDONLY)) < 0) {
                logit("%s: problem opening %s: %s", __func__, 
                    WTMPX_FILE, strerror(errno));
                return (0);
        }
        if (fstat(fd, &st) != 0) {
                logit("%s: couldn't stat %s: %s", __func__, 
                    WTMPX_FILE, strerror(errno));
                close(fd);
                return (0);
        }

        /* Seek to the start of the last struct utmpx */
        if (lseek(fd, -(off_t)sizeof(struct utmpx), SEEK_END) == -1 ) {
                /* probably a newly rotated wtmpx file */
                close(fd);
                return (0);
        }

        while (!found) {
                if (atomicio(read, fd, &utx, sizeof(utx)) != sizeof(utx)) {
                        logit("%s: read of %s failed: %s", __func__, 
                            WTMPX_FILE, strerror(errno));
                        close (fd);
                        return (0);
                }
                /*
                 * Logouts are recorded as a blank username on a particular 
                 * line. So, we just need to find the username in struct utmpx
                 */
                if (wtmpx_islogin(li, &utx)) {
                        found = 1;
# if defined(HAVE_TV_IN_UTMPX)
                        li->tv_sec = utx.ut_tv.tv_sec;
# elif defined(HAVE_TIME_IN_UTMPX)
                        li->tv_sec = utx.ut_time;
# endif
                        line_fullname(li->line, utx.ut_line, sizeof(li->line));
# if defined(HAVE_HOST_IN_UTMPX)
                        strlcpy(li->hostname, utx.ut_host,
                            MIN_SIZEOF(li->hostname, utx.ut_host));
# endif
                        continue;
                }
                if (lseek(fd, -(off_t)(2 * sizeof(struct utmpx)), SEEK_CUR) == -1) {
                        close(fd);
                        return (0);
                }
        }

        close(fd);
        return (1);
}
#endif /* USE_WTMPX */

/**
 ** Low-level libutil login() functions
 **/

#ifdef USE_LOGIN
static int
syslogin_perform_login(struct logininfo *li)
{
        struct utmp *ut;

        ut = xmalloc(sizeof(*ut));
        construct_utmp(li, ut);
        login(ut);
        free(ut);

        return (1);
}

static int
syslogin_perform_logout(struct logininfo *li)
{
# ifdef HAVE_LOGOUT
        char line[UT_LINESIZE];

        (void)line_stripname(line, li->line, sizeof(line));

        if (!logout(line))
                logit("%s: logout() returned an error", __func__);
#  ifdef HAVE_LOGWTMP
        else
                logwtmp(line, "", "");
#  endif
        /* FIXME: (ATL - if the need arises) What to do if we have
         * login, but no logout?  what if logout but no logwtmp? All
         * routines are in libutil so they should all be there,
         * but... */
# endif
        return (1);
}

int
syslogin_write_entry(struct logininfo *li)
{
        switch (li->type) {
        case LTYPE_LOGIN:
                return (syslogin_perform_login(li));
        case LTYPE_LOGOUT:
                return (syslogin_perform_logout(li));
        default:
                logit("%s: Invalid type field", __func__);
                return (0);
        }
}
#endif /* USE_LOGIN */

/* end of file log-syslogin.c */

/**
 ** Low-level lastlog functions
 **/

#ifdef USE_LASTLOG
#define LL_FILE 1
#define LL_DIR 2
#define LL_OTHER 3

static void
lastlog_construct(struct logininfo *li, struct lastlog *last)
{
        /* clear the structure */
        memset(last, '\0', sizeof(*last));

        line_stripname(last->ll_line, li->line, sizeof(last->ll_line));
        strlcpy(last->ll_host, li->hostname,
                MIN_SIZEOF(last->ll_host, li->hostname));
        last->ll_time = li->tv_sec;
}

static int
lastlog_filetype(char *filename)
{
        struct stat st;

        if (stat(LASTLOG_FILE, &st) != 0) {
                logit("%s: Couldn't stat %s: %s", __func__,
                    LASTLOG_FILE, strerror(errno));
                return (0);
        }
        if (S_ISDIR(st.st_mode))
                return (LL_DIR);
        else if (S_ISREG(st.st_mode))
                return (LL_FILE);
        else
                return (LL_OTHER);
}


/* open the file (using filemode) and seek to the login entry */
static int
lastlog_openseek(struct logininfo *li, int *fd, int filemode)
{
        off_t offset;
        int type;
        char lastlog_file[1024];

        type = lastlog_filetype(LASTLOG_FILE);
        switch (type) {
        case LL_FILE:
                strlcpy(lastlog_file, LASTLOG_FILE,
                    sizeof(lastlog_file));
                break;
        case LL_DIR:
                snprintf(lastlog_file, sizeof(lastlog_file), "%s/%s",
                    LASTLOG_FILE, li->username);
                break;
        default:
                logit("%s: %.100s is not a file or directory!", __func__,
                    LASTLOG_FILE);
                return (0);
        }

        *fd = open(lastlog_file, filemode, 0600);
        if (*fd < 0) {
                debug("%s: Couldn't open %s: %s", __func__,
                    lastlog_file, strerror(errno));
                return (0);
        }

        if (type == LL_FILE) {
                /* find this uid's offset in the lastlog file */
                offset = (off_t) ((long)li->uid * sizeof(struct lastlog));

                if (lseek(*fd, offset, SEEK_SET) != offset) {
                        logit("%s: %s->lseek(): %s", __func__,
                            lastlog_file, strerror(errno));
                        return (0);
                }
        }

        return (1);
}

static int
lastlog_perform_login(struct logininfo *li)
{
        struct lastlog last;
        int fd;

        /* create our struct lastlog */
        lastlog_construct(li, &last);

        if (!lastlog_openseek(li, &fd, O_RDWR|O_CREAT))
                return (0);

        /* write the entry */
        if (atomicio(vwrite, fd, &last, sizeof(last)) != sizeof(last)) {
                close(fd);
                logit("%s: Error writing to %s: %s", __func__,
                    LASTLOG_FILE, strerror(errno));
                return (0);
        }

        close(fd);
        return (1);
}

int
lastlog_write_entry(struct logininfo *li)
{
        switch(li->type) {
        case LTYPE_LOGIN:
                return (lastlog_perform_login(li));
        default:
                logit("%s: Invalid type field", __func__);
                return (0);
        }
}

static void
lastlog_populate_entry(struct logininfo *li, struct lastlog *last)
{
        line_fullname(li->line, last->ll_line, sizeof(li->line));
        strlcpy(li->hostname, last->ll_host,
            MIN_SIZEOF(li->hostname, last->ll_host));
        li->tv_sec = last->ll_time;
}

int
lastlog_get_entry(struct logininfo *li)
{
        struct lastlog last;
        int fd, ret;

        if (!lastlog_openseek(li, &fd, O_RDONLY))
                return (0);

        ret = atomicio(read, fd, &last, sizeof(last));
        close(fd);

        switch (ret) {
        case 0:
                memset(&last, '\0', sizeof(last));
                /* FALLTHRU */
        case sizeof(last):
                lastlog_populate_entry(li, &last);
                return (1);
        case -1:
                error("%s: Error reading from %s: %s", __func__,
                    LASTLOG_FILE, strerror(errno));
                return (0);
        default:
                error("%s: Error reading from %s: Expecting %d, got %d",
                    __func__, LASTLOG_FILE, sizeof(last), ret);
                return (0);
        }

        /* NOTREACHED */
        return (0);
}
#endif /* USE_LASTLOG */

#ifdef USE_BTMP
  /*
   * Logs failed login attempts in _PATH_BTMP if that exists.
   * The most common login failure is to give password instead of username.
   * So the _PATH_BTMP file checked for the correct permission, so that
   * only root can read it.
   */

void
record_failed_login(const char *username, const char *hostname,
    const char *ttyn)
{
        int fd;
        struct utmp ut;
        struct sockaddr_storage from;
        size_t fromlen = sizeof(from);
        struct sockaddr_in *a4;
        struct sockaddr_in6 *a6;
        time_t t;
        struct stat fst;

        if (geteuid() != 0)
                return;
        if ((fd = open(_PATH_BTMP, O_WRONLY | O_APPEND)) < 0) {
                debug("Unable to open the btmp file %s: %s", _PATH_BTMP,
                    strerror(errno));
                return;
        }
        if (fstat(fd, &fst) < 0) {
                logit("%s: fstat of %s failed: %s", __func__, _PATH_BTMP,
                    strerror(errno));
                goto out;
        }
        if((fst.st_mode & (S_IRWXG | S_IRWXO)) || (fst.st_uid != 0)){
                logit("Excess permission or bad ownership on file %s",
                    _PATH_BTMP);
                goto out;
        }

        memset(&ut, 0, sizeof(ut));
        /* strncpy because we don't necessarily want nul termination */
        strncpy(ut.ut_user, username, sizeof(ut.ut_user));
        strlcpy(ut.ut_line, "ssh:notty", sizeof(ut.ut_line));

        time(&t);
        ut.ut_time = t;     /* ut_time is not always a time_t */
        ut.ut_type = LOGIN_PROCESS;
        ut.ut_pid = getpid();

        /* strncpy because we don't necessarily want nul termination */
        strncpy(ut.ut_host, hostname, sizeof(ut.ut_host));

        if (packet_connection_is_on_socket() &&
            getpeername(packet_get_connection_in(),
            (struct sockaddr *)&from, &fromlen) == 0) {
                ipv64_normalise_mapped(&from, &fromlen);
                if (from.ss_family == AF_INET) {
                        a4 = (struct sockaddr_in *)&from;
                        memcpy(&ut.ut_addr, &(a4->sin_addr),
                            MIN_SIZEOF(ut.ut_addr, a4->sin_addr));
                }
#ifdef HAVE_ADDR_V6_IN_UTMP
                if (from.ss_family == AF_INET6) {
                        a6 = (struct sockaddr_in6 *)&from;
                        memcpy(&ut.ut_addr_v6, &(a6->sin6_addr),
                            MIN_SIZEOF(ut.ut_addr_v6, a6->sin6_addr));
                }
#endif
        }

        if (atomicio(vwrite, fd, &ut, sizeof(ut)) != sizeof(ut))
                error("Failed to write to %s: %s", _PATH_BTMP,
                    strerror(errno));

out:
        close(fd);
}
#endif  /* USE_BTMP */