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Replace <sys/param.h> with <limits.h> and other less dirty headers where
possible.  Annotate <sys/param.h> lines with their current reasons.  Switch
to PATH_MAX, NGROUPS_MAX, HOST_NAME_MAX+1, LOGIN_NAME_MAX, etc.  Change
MIN() and MAX() to local definitions of MINIMUM() and MAXIMUM() where
sensible to avoid pulling in the pollution.  These are the files confirmed
through binary verification.
ok guenther, millert, doug (helped with the verification protocol)

/* $OpenBSD: sshlogin.c,v 1.30 2015/01/16 06:40:12 deraadt Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * This file performs some of the things login(1) normally does.  We cannot
 * easily use something like login -p -h host -f user, because there are
 * several different logins around, and it is hard to determined what kind of
 * login the current system has.  Also, we want to be able to execute commands
 * on a tty.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
 * Copyright (c) 1999 Markus Friedl.  All rights reserved.
 *
 * 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.
 */

#include <sys/types.h>
#include <sys/param.h>	/* MAXHOSTNAMELEN */
#include <sys/socket.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <util.h>
#include <utmp.h>
#include <stdarg.h>

#include "sshlogin.h"
#include "log.h"
#include "buffer.h"
#include "misc.h"
#include "servconf.h"

extern Buffer loginmsg;
extern ServerOptions options;

/*
 * Returns the time when the user last logged in.  Returns 0 if the
 * information is not available.  This must be called before record_login.
 * The host the user logged in from will be returned in buf.
 */
time_t
get_last_login_time(uid_t uid, const char *logname,
    char *buf, size_t bufsize)
{
	struct lastlog ll;
	char *lastlog;
	int fd;
	off_t pos, r;

	lastlog = _PATH_LASTLOG;
	buf[0] = '\0';

	fd = open(lastlog, O_RDONLY);
	if (fd < 0)
		return 0;

	pos = (long) uid * sizeof(ll);
	r = lseek(fd, pos, SEEK_SET);
	if (r == -1) {
		error("%s: lseek: %s", __func__, strerror(errno));
		close(fd);
		return (0);
	}
	if (r != pos) {
		debug("%s: truncated lastlog", __func__);
		close(fd);
		return (0);
	}
	if (read(fd, &ll, sizeof(ll)) != sizeof(ll)) {
		close(fd);
		return 0;
	}
	close(fd);
	if (bufsize > sizeof(ll.ll_host) + 1)
		bufsize = sizeof(ll.ll_host) + 1;
	strncpy(buf, ll.ll_host, bufsize - 1);
	buf[bufsize - 1] = '\0';
	return (time_t)ll.ll_time;
}

/*
 * Generate and store last login message.  This must be done before
 * login_login() is called and lastlog is updated.
 */
static void
store_lastlog_message(const char *user, uid_t uid)
{
	char *time_string, hostname[MAXHOSTNAMELEN] = "", buf[512];
	time_t last_login_time;

	if (!options.print_lastlog)
		return;

	last_login_time = get_last_login_time(uid, user, hostname,
	    sizeof(hostname));

	if (last_login_time != 0) {
		time_string = ctime(&last_login_time);
		time_string[strcspn(time_string, "\n")] = '\0';
		if (strcmp(hostname, "") == 0)
			snprintf(buf, sizeof(buf), "Last login: %s\r\n",
			    time_string);
		else
			snprintf(buf, sizeof(buf), "Last login: %s from %s\r\n",
			    time_string, hostname);
		buffer_append(&loginmsg, buf, strlen(buf));
	}
}

/*
 * Records that the user has logged in.  I wish these parts of operating
 * systems were more standardized.
 */
void
record_login(pid_t pid, const char *tty, const char *user, uid_t uid,
    const char *host, struct sockaddr *addr, socklen_t addrlen)
{
	int fd;
	struct lastlog ll;
	char *lastlog;
	struct utmp u;

	/* save previous login details before writing new */
	store_lastlog_message(user, uid);

	/* Construct an utmp/wtmp entry. */
	memset(&u, 0, sizeof(u));
	strncpy(u.ut_line, tty + 5, sizeof(u.ut_line));
	u.ut_time = time(NULL);
	strncpy(u.ut_name, user, sizeof(u.ut_name));
	strncpy(u.ut_host, host, sizeof(u.ut_host));

	login(&u);
	lastlog = _PATH_LASTLOG;

	/* Update lastlog unless actually recording a logout. */
	if (strcmp(user, "") != 0) {
		/*
		 * It is safer to memset the lastlog structure first because
		 * some systems might have some extra fields in it (e.g. SGI)
		 */
		memset(&ll, 0, sizeof(ll));

		/* Update lastlog. */
		ll.ll_time = time(NULL);
		strncpy(ll.ll_line, tty + 5, sizeof(ll.ll_line));
		strncpy(ll.ll_host, host, sizeof(ll.ll_host));
		fd = open(lastlog, O_RDWR);
		if (fd >= 0) {
			lseek(fd, (off_t) ((long) uid * sizeof(ll)), SEEK_SET);
			if (write(fd, &ll, sizeof(ll)) != sizeof(ll))
				logit("Could not write %.100s: %.100s", lastlog, strerror(errno));
			close(fd);
		}
	}
}

/* Records that the user has logged out. */
void
record_logout(pid_t pid, const char *tty)
{
	const char *line = tty + 5;	/* /dev/ttyq8 -> ttyq8 */
	if (logout(line))
		logwtmp(line, "", "");
}