/*
 * tac_plus.c
 *
 * TACACS_PLUS daemon suitable for using on Un*x systems.
 *
 * October 1994, Lol Grant
 *
 * Copyright (c) 1994-2000 by Cisco systems, Inc.
 *
 * Permission to use, copy, modify, and distribute modified and
 * unmodified copies of this software for any purpose and without fee is
 * hereby granted, provided that (a) this copyright and permission notice
 * appear on all copies of the software and supporting documentation, (b)
 * the name of Cisco Systems, Inc. not be used in advertising or
 * publicity pertaining to distribution of the program without specific
 * prior permission, and (c) notice be given in supporting documentation
 * that use, modification, copying and distribution is by permission of
 * Cisco Systems, Inc.

 * Cisco Systems, Inc. makes no representations about the suitability
 * of this software for any purpose.  THIS SOFTWARE IS PROVIDED ``AS
 * IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.
*/

#include "tac_plus.h"
#include <sys/stat.h>
#ifdef TAC_PLUS_USERNAME
#include <pwd.h>
#endif
#if defined(TAC_PLUS_GROUPID) || defined(TAC_PLUS_GROUPNAME)
#include <unistd.h>
#include <grp.h>
#endif
#include <signal.h>

#if defined(ALIASES) || defined(TTYS)
 #include "own_wtmp.h"
#endif
#include "allow.h"

static int standalone  = 1; /* running standalone (1) or under inetd (0) */
static int inter       = 0; /* do not go to background */
static int initialised = 0; /* data structures have been allocated */
int sendauth_only      = 0; /* don't respond to sendpass requests */
int debug              = 0; /* debugging flags */
int port               = 0; /* port we're listening on */
int console            = 0; /* write all syslog messages to console */
int parse_only         = 0; /* exit after verbose parsing */
int single             = 0; /* single thread (for debugging) */
int wtmpfd	       = 0; /* for wtmp file logging */
char *wtmpfile         = NULL;

struct timeval started_at;

struct session session;     /* session data */

static char pidfilebuf[75]; /* holds current name of the pidfile */

unsigned long bindaddress;
void start_session();

#ifndef REAPCHILD
static RETSIGTYPE reapchild(int s) {
    int status;
    int pid;

    for (;;) {
	pid = wait3(&status, WNOHANG, 0);
	if (pid <= 0) {
#ifdef REARMSIGNAL
	    signal(SIGCHLD, reapchild);
#endif
	    return;
	}
	if (debug & DEBUG_FORK_FLAG)
	    report(LOG_DEBUG, "%d reaped", pid);
    }
}
#endif /* REAPCHILD */

static RETSIGTYPE die(int s) {
    report(LOG_INFO, "Received signal %d, shutting down", s);
#ifdef UTMP
    init_utmp("shutdown");
#endif
    unlink(pidfilebuf);
    tac_exit(0);
}

static void
init()
{
    if (initialised)
	cfg_clean_config();    

    report(LOG_INFO, "Reading config");

    session.acctfile = tac_strdup(TAC_PLUS_ACCTFILE);
    
    if (!session.cfgfile) {
	report(LOG_ERR, "no config file specified");
	tac_exit(1);
    }
    
    /* read the config file */
    if (cfg_read_config(session.cfgfile)) {
	report(LOG_ERR, "Parsing %s", session.cfgfile);
	tac_exit(1);
    }

#ifdef UTMP
    if (init_utmp("reboot")) {
      report(LOG_ERR, "init_utmp(utmp=%s, wtmp=%s, ttys=%s) failed",
	     TAC_PLUS_UTMPFILE, TAC_PLUS_WTMPFILE,
	     TAC_PLUS_TTYSFILE);
      tac_exit(1);
    }
#endif

    initialised++;
    report(LOG_INFO, "Version %s Initialized %d", TAC_VERSION, initialised);

#ifdef REGNAS
    reg_nas_users();
#endif
}

#ifdef UDB
/* static sigset_t nset = sigmask(SIGALRM) | sigmask(SIGUSR1); */
/* FIXME use sigprocmask(SIG_BLOCK, &nset, NULL); instead of signal(...,SIG_IGN)? in handler() too... */
static RETSIGTYPE alarm_hdl(int s) {
  db_checkmt();
  alarm(60);
  /* sigprocmask(SIG_UNBLOCK, &nset, NULL); */
#if defined(REARMSIGNAL)
    signal(SIGALRM, alarm_hdl);
#endif
}
#endif

static RETSIGTYPE handler(int s) {
    report(LOG_INFO, "Received signal %d", s);
    init();
#if defined(REARMSIGNAL)
    signal(SIGUSR1, handler);
    signal(SIGHUP, handler);
#endif
}

/*
 * Return a socket bound to an appropriate port number/address. Exits
 * the program on failure */

get_socket()
{
    int s;
    struct sockaddr_in sin;
    struct servent *sp;
#ifdef SO_REUSEADDR
    int on = 1;
#endif

    bzero((char *) &sin, sizeof(sin));

    if (port) {
	sin.sin_port = htons(port);
    } else {
	sp = getservbyname("tacacs", "tcp");
	if (sp)
	    sin.sin_port = sp->s_port;
	else {
	    report(LOG_ERR, "Cannot find socket port");
	    tac_exit(1);
	}
    }

    sin.sin_family = AF_INET;
    sin.sin_addr.s_addr = bindaddress; /* htonl(INADDR_ANY); */

    s = socket(AF_INET, SOCK_STREAM, 0);

    if (s < 0) {
	console++;
	report(LOG_ERR, "get_socket: socket: %s", sys_errlist[errno]);
	tac_exit(1);
    }
#ifdef SO_REUSEADDR
	if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &on,
		       sizeof(on)) < 0)
	    perror("setsockopt - SO_REUSEADDR");
#endif				/* SO_REUSEADDR */

    if (bind(s, (struct sockaddr *) &sin, sizeof(sin)) < 0) {
	console++;
	report(LOG_ERR, "get_socket: bind %d %s",
	       ntohs(sin.sin_port),
	       sys_errlist[errno]);
	tac_exit(1);
    }
    return (s);
}

static void
open_logfile()
{
#ifdef LOG_FACIL
    openlog("tac_plus", LOG_PID, LOG_FACIL);
#else
    openlog("tac_plus", LOG_PID);
#endif
    setlogmask(LOG_UPTO(LOG_DEBUG));
}

/*
 * main
 *
 * We will eventually be called from inetd or via the rc scripts directly
 * Parse arguments and act appropiately.
 */

main(argc, argv)
int argc;
char **argv;
{
    extern char *optarg;
    int childpid;
    int c;
    int s = -1;
    FILE *fp;
#ifdef LOOKUP_NAMES
    int lookup_peer = 0;
#endif
#ifdef TAC_PLUS_USERNAME
    struct passwd *pw;
#ifdef TAC_PLUS_GROUPNAME
    struct group  *gr;
#endif
#endif
#ifdef TAC_PLUS_GROUPID
    gid_t groups[2];
#endif

    debug = 0;			/* no debugging */
    standalone = 1;			/* standalone */
    single = 0;			/* single threaded */
    inter = 0;

    /* initialise global session data */
    bzero(&session, sizeof(session));
    session.peer = tac_strdup("unknown");

#ifdef ALIASES
    session.peeralias = tac_strdup(session.peer);
    session.flags = B_FLAG_INIT;
#endif

    session.cfgfile = tac_strdup(TAC_PLUS_CFGFILE);
    
    open_logfile();

#ifdef TAC_PLUS_PORT
    port = TAC_PLUS_PORT;
#endif

    if (argc <= 1) {
      fprintf(stderr, "Usage: tac_plus -C <configuration file>\n"
	      "\t[ -t ] [ -P ] [ -g ] [ -p <port> ]\n"
	      "\t[ -d <debug level> ] [ -i ] [ -I ] [ -v ] [ -s ]\n"
	      "\t[ -l logfile ]"
#ifdef MAXSESS
	      " [ -w whologfile ]"
#endif
#ifdef LOOKUP_NAMES
	      " [ -L ]"
#endif
	      "\n");
	tac_exit(1);
    }

    while ((c = getopt(argc, argv, "td:C:iIp:PgvsLln:w:u:")) != EOF)
	switch (c) {
#ifdef LOOKUP_NAMES
	case 'L':		/* lookup peer names via DNS */
	    lookup_peer++;
	    break;
#endif
	case 'n':		/* do nothing */
	    break;
	case 's':		/* don't respond to sendpass */
	    sendauth_only++;
	    break;
	case 'v':		/* print version and exit */
	    fprintf(stdout, "tac_plus version %s\n", TAC_VERSION);
	    tac_exit(1);
	case 't':
	    console++;		/* log to console too */
	    break;
	case 'P':		/* Parse config file only */
	    parse_only++;
	    break;
	case 'g':		/* single threaded */
	    single++;
	    break;
	case 'p':		/* port */
	    port = atoi(optarg);
	    break;
	case 'd':		/* debug */
	    debug = atoi(optarg);
	    break;
	case 'C':		/* config file name */
	    free(session.cfgfile);
	    session.cfgfile = tac_strdup(optarg);
	    break;
	case 'i':		/* stand-alone */
	    standalone = 0;
	    break;
	case 'I':		/* do not go to background */
	    inter = 1;
	    break;
	case 'l':		/* logfile */
	    logfile = tac_strdup(optarg);
	    break;
#ifdef MAXSESS
	case 'w':		/* wholog file */
	    wholog = tac_strdup(optarg);
	    break;
#endif
	case 'u':
	    wtmpfile = tac_strdup(optarg);
	    break;

	default:
	    fprintf(stderr, "%s: bad switch %c\n", argv[0], c);
	    tac_exit(1);
	}

    if (geteuid() != 0)
	fprintf(stderr, "Warning, not running as uid 0\n"
		"Tac_plus is usually run as root\n");

#ifdef DXS1
    {
      extern regex_t dxs1_re;
      regcomp(&dxs1_re, "dsx1\\(slot/unit/channel\\)=([0-9/]*),", REG_EXTENDED);
    }
#endif
#ifdef REGNAS
    {
      extern regex_t rship_re;
      regcomp(&rship_re, "Line is running PPP for address ([0-9.]+)\\.", REG_EXTENDED);
    }
#endif

    parser_init();

    init();

#ifdef UDB
    signal(SIGALRM, alarm_hdl);
#endif
    signal(SIGUSR1, handler);
    signal(SIGHUP, handler);
    signal(SIGTERM, die);
    signal(SIGPIPE, SIG_IGN);

    if (parse_only)
	tac_exit(0);

#ifdef UDB
    alarm(50);
#endif

    if (debug)
	report(LOG_DEBUG, "tac_plus server %s starting", TAC_VERSION);

    if (!standalone) {
	/* running under inetd */
	struct sockaddr_in name;
	size_t name_len;
#ifdef FIONBIO
	int on = 1;
#endif

	name_len = sizeof(name);

	session.sock = 0;
	if (getpeername(session.sock, (struct sockaddr *) &name, &name_len)) {
	    report(LOG_ERR, "getpeername failure %s", sys_errlist[errno]);
	} else {
#ifdef LOOKUP_NAMES
	    struct hostent *hp;
	    hp = gethostbyaddr((char *) &name.sin_addr.s_addr,
			       sizeof(name.sin_addr.s_addr), AF_INET);
#endif
	    if (session.peer) {
		free(session.peer);
	    }
	    session.peer = tac_strdup(
#ifdef LOOKUP_NAMES
         	                      hp ? hp->h_name :
#endif
				           (char *) inet_ntoa(name.sin_addr)
				     );

#ifdef ALIASES
	    if (session.peeralias) {
		free(session.peeralias);
	    }
	    session.peeralias = get_peer_alias(session.peer, &session.flags);
#endif
	    session.nasaddr.s_addr = name.sin_addr.s_addr;
	}
#ifdef FIONBIO
	if (ioctl(session.sock, FIONBIO, &on) < 0) {
	    report(LOG_ERR, "ioctl(FIONBIO) %s", sys_errlist[errno]);
	    tac_exit(1);
	}
#endif
	start_session();
	tac_exit(0);
    }

    if (!single) {
	/* Running standalone. Background ourselves, let go of controlling tty */

#ifdef SIGTTOU
	signal(SIGTTOU, SIG_IGN);
#endif
#ifdef SIGTTIN
	signal(SIGTTIN, SIG_IGN);
#endif
#ifdef SIGTSTP
	signal(SIGTSTP, SIG_IGN);
#endif
	
	signal(SIGHUP, SIG_IGN);

      if (!inter) {
	if ((childpid = fork()) < 0)
	    report(LOG_ERR, "Can't fork first child");
	else if (childpid > 0)
	    exit(0);		/* parent */

	if (debug)
	    report(LOG_DEBUG, "Backgrounded");

	if (setsid() < 0)
	  report(LOG_ERR, "Can't change process group: %s", strerror(errno));

#ifndef REAPCHILD
	
	c = open("/dev/tty", O_RDWR);
	if (c >= 0) {
	    ioctl(c, TIOCNOTTY, (char *) 0);
	    (void) close(c);
	}

#else /* REAPCHILD */

	if ((childpid = fork()) < 0)
	    report(LOG_ERR, "Can't fork second child");
	else if (childpid > 0)
	    exit(0);
    
	if (debug & DEBUG_FORK_FLAG)
	    report(LOG_DEBUG, "Forked grandchild");

#endif /* REAPCHILD */
      }

#ifndef REAPCHILD
	signal(SIGCHLD, reapchild);
#else
	signal(SIGCHLD, SIG_IGN);
#endif

	closelog(); /* some systems require this */

	for (c = 0; c < getdtablesize(); c++)
#ifdef UDB
	    if (!db_inuse(c))
#endif
	    (void) close(c);

	/* make sure we can still log to syslog now we've closed everything */
	open_logfile();

    } /* ! single threaded */
    
    ostream = NULL;
    /* chdir("/"); */
    umask(077);
    errno = 0;

    s = get_socket();

#ifdef RAD_ROAMING
    buffer_server(); /* Start the buffer server */
#endif

#ifndef SOMAXCONN
#define SOMAXCONN 5
#endif

    if (listen(s, SOMAXCONN) < 0) {
	console++;
	report(LOG_ERR, "listen: %s", sys_errlist[errno]);
	tac_exit(1);
    }

    if (port == TAC_PLUS_PORT) {
	strcpy(pidfilebuf, TAC_PLUS_PIDFILE);
    } else {
	sprintf(pidfilebuf, "%s.%d", TAC_PLUS_PIDFILE, port);
    }

    /* write process id to pidfile */
    if ((fp = fopen(pidfilebuf, "w")) != NULL) {
	fprintf(fp, "%d\n", getpid());
	fclose(fp);
    } else 
	report(LOG_ERR, "Cannot write pid to %s %s", 
	       pidfilebuf, sys_errlist[errno]);

#ifdef TAC_PLUS_GROUPID
    if (setgid(TAC_PLUS_GROUPID))
	report(LOG_ERR, "Cannot set group id to %d %s", 
	       TAC_PLUS_GROUPID, sys_errlist[errno]);
#endif

#ifdef TAC_PLUS_USERID
    if (setuid(TAC_PLUS_USERID)) 
	report(LOG_ERR, "Cannot set user id to %d %s", 
	       TAC_PLUS_USERID, sys_errlist[errno]);
#endif

#ifdef TAC_PLUS_GROUPNAME
    if (!(gr = getgrnam(TAC_PLUS_GROUPNAME)))
      report(LOG_ERR, "Cannot obtain group information for %s",
	     TAC_PLUS_GROUPNAME);
    else if (setgid(gr->gr_gid))
      report(LOG_ERR, "Cannot set group id to %d %s",
	     gr->gr_gid, sys_errlist[errno]);
#endif
#ifdef TAC_PLUS_USERNAME
    if (!(pw = getpwnam(TAC_PLUS_USERNAME)))
      report(LOG_ERR, "Cannot obtain user information for %s",
	     TAC_PLUS_USERNAME);
    else {
#ifndef TAC_PLUS_GROUPNAME
      if (setgid(pw->pw_gid))
	report(LOG_ERR, "Cannot set group id to %d %s",
	       pw->pw_gid, sys_errlist[errno]);
#endif
      if (setuid(pw->pw_uid))
	report(LOG_ERR, "Cannot set user id to %d %s",
	       pw->pw_uid, sys_errlist[errno]);
    }
#endif

#ifdef MAXSESS
    maxsess_loginit();
#endif /* MAXSESS */

    report(LOG_DEBUG, "uid=%d euid=%d gid=%d egid=%d s=%d",
	   getuid(), geteuid(), getgid(), getegid(), s);

    for (;;) {
	int pid;
	struct sockaddr_in from;
	size_t from_len;
	int newsockfd = -1;
#ifdef LOOKUP_NAMES
	struct hostent *hp = NULL;
#endif

	bzero((char *) &from, sizeof(from));
	from_len = sizeof(from);

	newsockfd = accept(s, (struct sockaddr *) &from, &from_len);

	if (newsockfd < 0) {
	    if (errno == EINTR)
		continue;

	    report(LOG_ERR, "accept: %s", sys_errlist[errno]);
	    continue;
	}

	if (!allowaddr(from.sin_addr.s_addr)) {
		report(LOG_WARNING, "Unauthorized call from %s",
			inet_ntoa(from.sin_addr));
		close(newsockfd);
	    if (errno == EINTR)
		continue;
	}

	session.key = defaultkey;
	for (nas_new = nas_list; nas_new; nas_new = nas_new->next)
	  if (nas_new->addr.s_addr == from.sin_addr.s_addr) {
	    if (nas_new->key) session.key = nas_new->key;
	    session.nas = nas_new;
	  }

#ifdef LOOKUP_NAMES
	if (lookup_peer) {
	    hp = gethostbyaddr((char *) &from.sin_addr.s_addr,
			       sizeof(from.sin_addr.s_addr), AF_INET);
	}
#endif

	if (session.peer) {
	    free(session.peer);
	}
	session.peer = tac_strdup(
#ifdef LOOKUP_NAMES
	                          hp ? hp->h_name :
#endif
				         (char *) inet_ntoa(from.sin_addr)
				 );

#ifdef ALIASES
	if (session.peeralias) {
	    free(session.peeralias);
	}
	session.peeralias = get_peer_alias(session.peer, &session.flags);
#endif
	session.nasaddr.s_addr = from.sin_addr.s_addr;

	if (debug & DEBUG_PACKET_FLAG)
	    report(LOG_DEBUG, "session request from %s sock=%d", 
		   session.peer, newsockfd);

	if (!single) {
	    pid = fork();

	    if (pid < 0) {
		report(LOG_ERR, "fork error: %s", sys_errlist[errno]);
		tac_exit(1);
	    }
	} else {
	    pid = 0;
	}

	if (pid == 0) {
	    /* child */
	    if (!single)
		close(s);
	    session.sock = newsockfd;
	    start_session();
	    shutdown(session.sock, 2);
	    close(session.sock);
	    if (!single)
		tac_exit(0);
	} else {
	    if (debug & DEBUG_FORK_FLAG)
		report(LOG_DEBUG, "forked %d", pid);
	    /* parent */
	    close(newsockfd);
	}
    }
}

#ifndef HAVE_GETDTABLESIZE
int 
getdtablesize()
{
    return(_NFILE);
}
#endif /* HAVE_GETDTABLESIZE */

/* Make sure version number is kosher. Return 0 if it is */
int
bad_version_check(pak)
u_char *pak;
{
    HDR *hdr = (HDR *) pak;
    
    switch (hdr->type) {
    case TAC_PLUS_AUTHEN:
	/* 
	 * Let authen routines take care of more sophisticated version
	 * checking as its now a bit involved. 
	 */
	return(0);

    case TAC_PLUS_AUTHOR:
    case TAC_PLUS_ACCT:
	if (hdr->version != TAC_PLUS_VER_0) {
	    send_error_reply(hdr->type, "Illegal packet version");
	    return(1);
	}
	return(0);

    default:
	return(1);
    }
}

/*
 * Determine the packet type, read the rest of the packet data,
 * decrypt it and call the appropriate service routine.
 *
 */

void
start_session()
{
    u_char *pak, *read_packet();
    HDR *hdr;
    void authen();

    session.seq_no = 0;
    session.aborted = 0;
    session.version = 0;

    pak = read_packet();
    if (!pak) {
	return;
    }

    if (debug & DEBUG_PACKET_FLAG) {
	report(LOG_DEBUG, "validation request from %s", session.peer);
	dump_nas_pak(pak);
    }
    hdr = (HDR *) pak;

    session.session_id = ntohl(hdr->session_id);

    /* Do some version checking */
    if (bad_version_check(pak)) {
	free(pak);
	return;
    }

    switch (hdr->type) {
    case TAC_PLUS_AUTHEN:
	authen(pak);
	free(pak);
	return;

    case TAC_PLUS_AUTHOR:
	author(pak);
	free(pak);
	return;

    case TAC_PLUS_ACCT:
	accounting(pak);
	return;

    default:
	/* Note: can't send error reply if type is unknown */
	report(LOG_ERR, "Illegal type %d in received packet", hdr->type);
	free(pak);
	return;
    }
}