gnuserv.c

linux 操作系统下对系统资源监控程序的编写

/* -*-C-*-
 * Server code for handling requests from clients and forwarding them
 * on to the GNU Emacs process.
 * 
 * This file is part of GNU Emacs.
 * 
 * Copying is permitted under those conditions described by the GNU
 * General Public License.
 * 
 * Copyright (C) 1989 Free Software Foundation, Inc.
 * 
 * Author: Andy Norman ([e-mail]), based on 'etc/server.c'
 * from the 18.52 GNU Emacs distribution.
 * 
 * Please mail bugs and suggestions to the author at the above address.
 */

/* HISTORY 
 * 11-Nov-1990                bristor@simba   
 *    Added EOT stuff.
 */

/*
 * This file incorporates new features added by Bob Weiner <[e-mail]>,
 * Darrell Kindred <[e-mail]> and Arup Mukherjee <[e-mail]>.
 * Please see the note at the end of the README file for details.
 *
 * (If gnuserv came bundled with your emacs, the README file is probably
 * ../etc/gnuserv.README relative to the directory containing this file)
 */

#include <config.h>

#include "libgtop-i18n.h"
#include <glibtop.h>
#include <glibtop/open.h>
#include <glibtop/close.h>
#include <glibtop/command.h>


#include <glibtop/parameter.h>

#include "server_config.h"

#include <glibtop/gnuserv.h>

#include <errno.h>
#include <popt.h>

#include "daemon.h"

#ifdef AIX
#include <sys/select.h>
#endif

#ifdef NEED_DECLARATION_PROGRAM_INVOCATION_NAME
extern char *program_invocation_name, *program_invocation_short_name;
#endif

#ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
char *program_invocation_short_name;
#endif

#ifndef HAVE_PROGRAM_INVOCATION_NAME
char *program_invocation_name;
#endif

void handle_parent_connection (int s);
void handle_slave_connection (int input, int output);

#if !defined(INTERNET_DOMAIN_SOCKETS)
#error "Internet Domain sockets are required"
#endif

#ifdef AUTH_MAGIC_COOKIE
#include <X11/X.h>
#include <X11/Xauth.h>

static Xauth *server_xauth = NULL;

#endif /* AUTH_MAGIC_COOKIE */

int enable_debug = 0;
int verbose_output = 0;
static int no_daemon = 0;
static int invoked_from_inetd = 0;
static int changed_uid = 0;

void
syslog_message (int priority, char *format, ...)
{
    va_list ap;
    char buffer [BUFSIZ];

    va_start (ap, format);
    vsnprintf (buffer, BUFSIZ-1, format, ap);
    va_end (ap);

    syslog (priority, "%s", buffer);
}

void
syslog_io_message (int priority, char *format, ...)
{
    va_list ap;
    char buffer [BUFSIZ];
    char buffer2 [BUFSIZ];

    va_start (ap, format);
    vsnprintf (buffer, BUFSIZ-1, format, ap);
    va_end (ap);

    snprintf (buffer2, BUFSIZ-1, "%s: %s", buffer, strerror (errno));
    syslog (priority, "%s", buffer2);
}

/*
 * timed_read - Read with timeout.
 */

static int
timed_read (int fd, char *buf, int max, int timeout, int one_line)
{
    fd_set rmask;
    struct timeval tv;	/* = {timeout, 0}; */
    char c = 0;
    int nbytes = 0;
    int r;

    tv.tv_sec = timeout;
    tv.tv_usec = 0;

    FD_ZERO (&rmask);
    FD_SET (fd, &rmask);

    do {
	r = select (fd + 1, &rmask, NULL, NULL, &tv);

	if (r > 0) {
	    if (read (fd, &c, 1) == 1) {
		*buf++ = c;
		++nbytes;
	    } else {
		syslog_io_message (LOG_WARNING, "read error on socket");
		return -1;
	    }
	} else if (r == 0) {
	    syslog_io_message (LOG_WARNING, "read timed out");
	    return -1;
	} else {
	    syslog_io_message (LOG_WARNING, "error in select");
	    return -1;
	}
    } while ((nbytes < max) && !(one_line && (c == '\n')));

    --buf;
    if (one_line && *buf == '\n') {
	*buf = 0;
    }
    return nbytes;
}


/*
 * permitted -- return whether a given host is allowed to connect to the server.
 */

static int
permitted (u_long host_addr, int fd)
{
    int i;

    char auth_protocol[128];
    char buf[1024];
    int auth_data_len;

    /* Read auth protocol name */

    if (timed_read (fd, auth_protocol, AUTH_NAMESZ, AUTH_TIMEOUT, 1) <= 0)
	return FALSE;

    if (enable_debug)
	syslog_message (LOG_DEBUG,
			"Client sent authenticatin protocol '%s'.",
			auth_protocol);

    if (strcmp (auth_protocol, DEFAUTH_NAME) &&
	strcmp (auth_protocol, MCOOKIE_NAME)) {
	syslog_message (LOG_WARNING,
			"Invalid authentication protocol "
			"'%s' from client",
			auth_protocol);
	return FALSE;
    }
	
    if (!strcmp (auth_protocol, MCOOKIE_NAME)) {
	/* 
	 * doing magic cookie auth
	 */
			
	if (timed_read (fd, buf, 10, AUTH_TIMEOUT, 1) <= 0)
	    return FALSE;

	auth_data_len = atoi (buf);
	
	if (auth_data_len < 1 || auth_data_len > sizeof(buf)) {
	    syslog_message(LOG_WARNING, "Invalid data length supplied by client");
	    return FALSE;
	}

	if (timed_read (fd, buf, auth_data_len, AUTH_TIMEOUT, 0) != auth_data_len)
	    return FALSE;

#ifdef AUTH_MAGIC_COOKIE
	if (!invoked_from_inetd && server_xauth && server_xauth->data &&
	    !memcmp (buf, server_xauth->data, auth_data_len)) {
	    return TRUE;
	}
#else
	syslog_message (LOG_WARNING,
			"Client tried Xauth, but server is "
			"not compiled with Xauth");
#endif

	/* 
	 * auth failed, but allow this to fall through to the
	 * GNU_SECURE protocol....
	 */

	if (verbose_output) {
	    if (changed_uid || invoked_from_inetd)
		syslog_message (LOG_WARNING,
				"Xauth authentication not allowed, "
				"trying GNU_SECURE ...");
	    else
		syslog_message (LOG_WARNING,
				"Xauth authentication failed, "
				"trying GNU_SECURE auth...");
	}
    }
    
    /* Other auth protocols go here, and should execute only if
     * the * auth_protocol name matches. */

    /* Now, try the old GNU_SECURE stuff... */
	
    if (enable_debug)
	syslog_message (LOG_DEBUG, "Doing GNU_SECURE auth ...");

    /* Now check the chain for that hash key */
    for (i = 0; i < HOST_TABLE_ENTRIES; i++) {
	if (enable_debug)
	    syslog_message (LOG_DEBUG, "Trying %lx - %lx",
			    host_addr, permitted_hosts [i]);
	if (permitted_hosts [i] == 0L)
	    return (FALSE);
	if (host_addr == permitted_hosts [i])
	    return (TRUE);
    }
	
    return (FALSE);
}


/*
 * setup_table -- initialise the table of hosts allowed to contact the server,
 * by reading from the file specified by the GNU_SECURE
 * environment variable
 * Put in the local machine, and, if a security file is specifed,
 * add each host that is named in the file.
 * Return the number of hosts added.
 */

static int
setup_table (void)
{
    char hostname [HOSTNAMSZ], screen [BUFSIZ];
    long host_addr;
    int i, hosts = 0;

    /* Make sure every entry is null */
    for (i = 0; i < HOST_TABLE_ENTRIES; i++)
	permitted_hosts [i] = 0;

    gethostname (hostname, HOSTNAMSZ);

    if ((host_addr = glibtop_internet_addr (hostname)) == -1) {
	syslog_io_message (LOG_ERR, "Can't resolve '%s'", hostname);
	exit (1);
    }

#ifdef AUTH_MAGIC_COOKIE

    sprintf (screen, "%d", SERVER_PORT);

    server_xauth = XauGetAuthByAddr
	(FamilyInternet,
	 sizeof (host_addr), (char *) &host_addr,
	 strlen (screen), screen,
	 strlen (MCOOKIE_X_NAME), MCOOKIE_X_NAME);
    hosts++;

#endif /* AUTH_MAGIC_COOKIE */

    /* Resolv host names from permitted_host_names []. */

    for (i = 0; i < HOST_TABLE_ENTRIES; i++) {
	if (!permitted_host_names [i])
	    continue;
	if (enable_debug)
	    syslog_message (LOG_DEBUG, "Resolving %s ...",
			    permitted_host_names [i]);
	permitted_hosts [i] =
	    glibtop_internet_addr (permitted_host_names [i]);
	if ((long) permitted_hosts [i] == -1) {
	    syslog_io_message (LOG_ERR, "Can't resolve '%s'",
			       permitted_host_names [i]);
	    exit (1);
	}
    }

    if (enable_debug)
	for (i = 0; i < HOST_TABLE_ENTRIES; i++)
	    syslog_message (LOG_DEBUG, "Host %s - %lx",