/* Taken from logdaemon-5.0, only minimal changes.  --marekm */

/************************************************************************
* Copyright 1995 by Wietse Venema.  All rights reserved. Individual files
* may be covered by other copyrights (as noted in the file itself.)
*
* This material was originally written and compiled by Wietse Venema at
* Eindhoven University of Technology, The Netherlands, in 1990, 1991,
* 1992, 1993, 1994 and 1995.
*
* Redistribution and use in source and binary forms are permitted
* provided that this entire copyright notice is duplicated in all such
* copies.  
*
* This software is provided "as is" and without any expressed or implied
* warranties, including, without limitation, the implied warranties of
* merchantibility and fitness for any particular purpose.
************************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#ifndef USE_PAM
#ident "$Id$"

#include "prototypes.h"
    /*
     * This module implements a simple but effective form of login access
     * control based on login names and on host (or domain) names, internet
     * addresses (or network numbers), or on terminal line names in case of
     * non-networked logins. Diagnostics are reported through syslog(3).
     * 
     * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
     */
#include <sys/types.h>
#include <stdio.h>
#include <syslog.h>
#include <ctype.h>
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#include <grp.h>
#ifdef PRIMARY_GROUP_MATCH
#include <pwd.h>
#endif
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>		/* for inet_ntoa() */

#if !defined(MAXHOSTNAMELEN) || (MAXHOSTNAMELEN < 64)
#undef MAXHOSTNAMELEN
#define MAXHOSTNAMELEN 256
#endif

 /* Path name of the access control file. */

#ifndef	TABLE
#define TABLE	"/etc/login.access"
#endif

/* Delimiters for fields and for lists of users, ttys or hosts. */
static char fs[] = ":";		/* field separator */
static char sep[] = ", \t";	/* list-element separator */

/* Constants to be used in assignments only, not in comparisons... */
#define YES             1
#define NO              0

static int list_match ();
static int user_match ();
static int from_match ();
static int string_match ();

/* login_access - match username/group and host/tty with access control file */
int login_access (const char *user, const char *from)
{
	FILE *fp;
	char line[BUFSIZ];
	char *perm;		/* becomes permission field */
	char *users;		/* becomes list of login names */
	char *froms;		/* becomes list of terminals or hosts */
	int match = NO;
	int end;
	int lineno = 0;		/* for diagnostics */

	/*
	 * Process the table one line at a time and stop at the first match.
	 * Blank lines and lines that begin with a '#' character are ignored.
	 * Non-comment lines are broken at the ':' character. All fields are
	 * mandatory. The first field should be a "+" or "-" character. A
	 * non-existing table means no access control.
	 */
	if ((fp = fopen (TABLE, "r"))) {
		while (!match && fgets (line, sizeof (line), fp)) {
			lineno++;
			if (line[end = strlen (line) - 1] != '\n') {
				SYSLOG ((LOG_ERR,
					 "%s: line %d: missing newline or line too long",
					 TABLE, lineno));
				continue;
			}
			if (line[0] == '#')
				continue;	/* comment line */
			while (end > 0 && isspace (line[end - 1]))
				end--;
			line[end] = 0;	/* strip trailing whitespace */
			if (line[0] == 0)	/* skip blank lines */
				continue;
			if (!(perm = strtok (line, fs))
			    || !(users = strtok ((char *) 0, fs))
			    || !(froms = strtok ((char *) 0, fs))
			    || strtok ((char *) 0, fs)) {
				SYSLOG ((LOG_ERR,
					 "%s: line %d: bad field count",
					 TABLE, lineno));
				continue;
			}
			if (perm[0] != '+' && perm[0] != '-') {
				SYSLOG ((LOG_ERR,
					 "%s: line %d: bad first field",
					 TABLE, lineno));
				continue;
			}
			match = (list_match (froms, from, from_match)
				 && list_match (users, user, user_match));
		}
		(void) fclose (fp);
	} else if (errno != ENOENT) {
		SYSLOG ((LOG_ERR, "cannot open %s: %m", TABLE));
	}
	return (match == 0 || (line[0] == '+'));
}

/* list_match - match an item against a list of tokens with exceptions */
static int list_match (char *list, const char *item, int (*match_fn) ())
{
	char *tok;
	int match = NO;

	/*
	 * Process tokens one at a time. We have exhausted all possible matches
	 * when we reach an "EXCEPT" token or the end of the list. If we do find
	 * a match, look for an "EXCEPT" list and recurse to determine whether
	 * the match is affected by any exceptions.
	 */
	for (tok = strtok (list, sep); tok != 0; tok = strtok ((char *) 0, sep)) {
		if (strcasecmp (tok, "EXCEPT") == 0)	/* EXCEPT: give up */
			break;
		if ((match = (*match_fn) (tok, item)))	/* YES */
			break;
	}

	/* Process exceptions to matches. */
	if (match != NO) {
		while ((tok = strtok ((char *) 0, sep))
		       && strcasecmp (tok, "EXCEPT"))
			/* VOID */ ;
		if (tok == 0 || list_match ((char *) 0, item, match_fn) == NO)
			return (match);
	}
	return (NO);
}

/* myhostname - figure out local machine name */
static char *myhostname (void)
{
	static char name[MAXHOSTNAMELEN + 1] = "";

	if (name[0] == 0) {
		gethostname (name, sizeof (name));
		name[MAXHOSTNAMELEN] = 0;
	}
	return (name);
}

#if HAVE_INNETGR
/* netgroup_match - match group against machine or user */
static int
netgroup_match (const char *group, const char *machine, const char *user)
{
	static char *mydomain = 0;

	if (mydomain == 0) {
		static char domain[MAXHOSTNAMELEN + 1];

		getdomainname (domain, MAXHOSTNAMELEN);
		mydomain = domain;
	}

	return innetgr (group, machine, user, mydomain);
}
#endif

/* user_match - match a username against one token */
static int user_match (const char *tok, const char *string)
{
	struct group *group;

#ifdef PRIMARY_GROUP_MATCH
	struct passwd *userinf;
#endif
	int i;
	char *at;

	/*
	 * If a token has the magic value "ALL" the match always succeeds.
	 * Otherwise, return YES if the token fully matches the username, or if
	 * the token is a group that contains the username.
	 */
	if ((at = strchr (tok + 1, '@')) != 0) {	/* split user@host pattern */
		*at = 0;
		return (user_match (tok, string)
			&& from_match (at + 1, myhostname ()));
#if HAVE_INNETGR
	} else if (tok[0] == '@') {	/* netgroup */
		return (netgroup_match (tok + 1, (char *) 0, string));
#endif
	} else if (string_match (tok, string)) {	/* ALL or exact match */
		return (YES);
	} else if ((group = getgrnam (tok))) {	/* try group membership */
		for (i = 0; group->gr_mem[i]; i++)
			if (strcasecmp (string, group->gr_mem[i]) == 0)
				return (YES);
#ifdef PRIMARY_GROUP_MATCH
		/*
		 * If the sting is an user whose initial GID matches the token,
		 * accept it. May avoid excessively long lines in /etc/group.
		 * Radu-Adrian Feurdean <raf@licj.soroscj.ro>
		 *
		 * XXX - disabled by default for now.  Need to verify that
		 * getpwnam() doesn't have some nasty side effects.  --marekm
		 */
		if ((userinf = getpwnam (string)))
			if (userinf->pw_gid == group->gr_gid)
				return (YES);
#endif
	}
	return (NO);
}

static char *resolve_hostname (string)
char *string;
{
	/*
	 * Resolve hostname to numeric IP address, as suggested
	 * by Dave Hagewood <admin@arrowweb.com>.  --marekm
	 */
	struct hostent *hp;

	hp = gethostbyname (string);
	if (hp)
		return inet_ntoa (*((struct in_addr *) *(hp->h_addr_list)));

	SYSLOG ((LOG_ERR, "%s - unknown host", string));
	return string;
}

/* from_match - match a host or tty against a list of tokens */

static int from_match (const char *tok, const char *string)
{
	int tok_len;
	int str_len;

	/*
	 * If a token has the magic value "ALL" the match always succeeds. Return
	 * YES if the token fully matches the string. If the token is a domain
	 * name, return YES if it matches the last fields of the string. If the
	 * token has the magic value "LOCAL", return YES if the string does not
	 * contain a "." character. If the token is a network number, return YES
	 * if it matches the head of the string.
	 */
#if HAVE_INNETGR
	if (tok[0] == '@') {	/* netgroup */
		return (netgroup_match (tok + 1, string, (char *) 0));
	} else
#endif
	if (string_match (tok, string)) {	/* ALL or exact match */
		return (YES);
	} else if (tok[0] == '.') {	/* domain: match last fields */
		if ((str_len = strlen (string)) > (tok_len = strlen (tok))
		    && strcasecmp (tok, string + str_len - tok_len) == 0)
			return (YES);
	} else if (strcasecmp (tok, "LOCAL") == 0) {	/* local: no dots */
		if (strchr (string, '.') == 0)
			return (YES);
	} else if (tok[(tok_len = strlen (tok)) - 1] == '.'	/* network */
		   && strncmp (tok, resolve_hostname (string), tok_len) == 0) {
		return (YES);
	}
	return (NO);
}

/* string_match - match a string against one token */
static int string_match (const char *tok, const char *string)
{

	/*
	 * If the token has the magic value "ALL" the match always succeeds.
	 * Otherwise, return YES if the token fully matches the string.
	 */
	if (strcasecmp (tok, "ALL") == 0) {	/* all: always matches */
		return (YES);
	} else if (strcasecmp (tok, string) == 0) {	/* try exact match */
		return (YES);
	}
	return (NO);
}

#endif				/* !USE_PAM */