options.c

基于TCP-WRAP原理的系统监控的c语言实现代码

/* linger_option - set the socket linger time (Marc Boucher <[e-mail]>) */

/* ARGSUSED */

static void linger_option(value, request)
char   *value;
struct request_info *request;
{
    struct linger linger;
    char    junk;

    if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
	|| linger.l_linger < 0)
	tcpd_jump("bad linger value: \"%s\"", value);
    if (dry_run == 0) {
	linger.l_onoff = (linger.l_linger != 0);
	if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
		       sizeof(linger)) < 0)
	    tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
    }
}

/* keepalive_option - set the socket keepalive option */

/* ARGSUSED */

static void keepalive_option(value, request)
char   *value;
struct request_info *request;
{
    static int on = 1;

    if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
				   (char *) &on, sizeof(on)) < 0)
	tcpd_warn("setsockopt SO_KEEPALIVE: %m");
}

/* nice_option - set nice value */

/* ARGSUSED */

static void nice_option(value, request)
char   *value;
struct request_info *request;
{
    int     niceval = 10;
    char    junk;

    if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
	tcpd_jump("bad nice value: \"%s\"", value);
    if (dry_run == 0 && nice(niceval) < 0)
	tcpd_warn("nice(%d): %m", niceval);
}

/* twist_option - replace process by shell command */

static void twist_option(value, request)
char   *value;
struct request_info *request;
{
    char   *error;

    if (dry_run != 0) {
	dry_run = 0;
    } else {
	if (resident > 0)
	    tcpd_jump("twist option in resident process");

	syslog(deny_severity, "twist %s to %s", eval_client(request), value);

	/* Before switching to the shell, set up stdin, stdout and stderr. */

#define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))

	if (maybe_dup2(request->fd, 0) != 0 ||
	    maybe_dup2(request->fd, 1) != 1 ||
	    maybe_dup2(request->fd, 2) != 2) {
	    error = "twist_option: dup: %m";
	} else {
	    if (request->fd > 2)
		close(request->fd);
	    (void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
	    error = "twist_option: /bin/sh: %m";
	}

	/* Something went wrong: we MUST terminate the process. */

	tcpd_warn(error);
	clean_exit(request);
    }
}

/* rfc931_option - look up remote user name */

static void rfc931_option(value, request)
char   *value;
struct request_info *request;
{
    int     timeout;
    char    junk;

    if (value != 0) {
	if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
	    tcpd_jump("bad rfc931 timeout: \"%s\"", value);
	rfc931_timeout = timeout;
    }
    (void) eval_user(request);
}

/* setenv_option - set environment variable */

/* ARGSUSED */

static void setenv_option(value, request)
char   *value;
struct request_info *request;
{
    char   *var_value;

    if (*(var_value = value + strcspn(value, whitespace)))
	*var_value++ = 0;
    if (setenv(chop_string(value), chop_string(var_value), 1))
	tcpd_jump("memory allocation failure");
}

 /*
  * The severity option goes last because it comes with a huge amount of ugly
  * #ifdefs and tables.
  */

struct syslog_names {
    char   *name;
    int     value;
};

static struct syslog_names log_fac[] = {
#ifdef LOG_KERN
    "kern", LOG_KERN,
#endif
#ifdef LOG_USER
    "user", LOG_USER,
#endif
#ifdef LOG_MAIL
    "mail", LOG_MAIL,
#endif
#ifdef LOG_DAEMON
    "daemon", LOG_DAEMON,
#endif
#ifdef LOG_AUTH
    "auth", LOG_AUTH,
#endif
#ifdef LOG_LPR
    "lpr", LOG_LPR,
#endif
#ifdef LOG_NEWS
    "news", LOG_NEWS,
#endif
#ifdef LOG_UUCP
    "uucp", LOG_UUCP,
#endif
#ifdef LOG_CRON
    "cron", LOG_CRON,
#endif
#ifdef LOG_LOCAL0
    "local0", LOG_LOCAL0,
#endif
#ifdef LOG_LOCAL1
    "local1", LOG_LOCAL1,
#endif
#ifdef LOG_LOCAL2
    "local2", LOG_LOCAL2,
#endif
#ifdef LOG_LOCAL3
    "local3", LOG_LOCAL3,
#endif
#ifdef LOG_LOCAL4
    "local4", LOG_LOCAL4,
#endif
#ifdef LOG_LOCAL5
    "local5", LOG_LOCAL5,
#endif
#ifdef LOG_LOCAL6
    "local6", LOG_LOCAL6,
#endif
#ifdef LOG_LOCAL7
    "local7", LOG_LOCAL7,
#endif
    0,
};

static struct syslog_names log_sev[] = {
#ifdef LOG_EMERG
    "emerg", LOG_EMERG,
#endif
#ifdef LOG_ALERT
    "alert", LOG_ALERT,
#endif
#ifdef LOG_CRIT
    "crit", LOG_CRIT,
#endif
#ifdef LOG_ERR
    "err", LOG_ERR,
#endif
#ifdef LOG_WARNING
    "warning", LOG_WARNING,
#endif
#ifdef LOG_NOTICE
    "notice", LOG_NOTICE,
#endif
#ifdef LOG_INFO
    "info", LOG_INFO,
#endif
#ifdef LOG_DEBUG
    "debug", LOG_DEBUG,
#endif
    0,
};

/* severity_map - lookup facility or severity value */

static int severity_map(table, name)
struct syslog_names *table;
char   *name;
{
    struct syslog_names *t;

    for (t = table; t->name; t++)
	if (STR_EQ(t->name, name))
	    return (t->value);
    tcpd_jump("bad syslog facility or severity: \"%s\"", name);
    /* NOTREACHED */
}

/* severity_option - change logging severity for this event (Dave Mitchell) */

/* ARGSUSED */

static void severity_option(value, request)
char   *value;
struct request_info *request;
{
    char   *level = split_at(value, '.');

    allow_severity = deny_severity = level ?
	severity_map(log_fac, value) | severity_map(log_sev, level) :
	severity_map(log_sev, value);
}

/* get_field - return pointer to next field in string */

static char *get_field(string)
char   *string;
{
    static char *last = "";
    char   *src;
    char   *dst;
    char   *ret;
    int     ch;

    /*
     * This function returns pointers to successive fields within a given
     * string. ":" is the field separator; warn if the rule ends in one. It
     * replaces a "\:" sequence by ":", without treating the result of
     * substitution as field terminator. A null argument means resume search
     * where the previous call terminated. This function destroys its
     * argument.
     * 
     * Work from explicit source or from memory. While processing \: we
     * overwrite the input. This way we do not have to maintain buffers for
     * copies of input fields.
     */

    src = dst = ret = (string ? string : last);
    if (src[0] == 0)
	return (0);

    while (ch = *src) {
	if (ch == ':') {
	    if (*++src == 0)
		tcpd_warn("rule ends in \":\"");
	    break;
	}
	if (ch == '\\' && src[1] == ':')
	    src++;
	*dst++ = *src++;
    }
    last = src;
    *dst = 0;
    return (ret);
}

/* chop_string - strip leading and trailing blanks from string */

static char *chop_string(string)
register char *string;
{
    char   *start = 0;
    char   *end;
    char   *cp;

    for (cp = string; *cp; cp++) {
	if (!isspace(*cp)) {
	    if (start == 0)
		start = cp;
	    end = cp;
	}
    }
    return (start ? (end[1] = 0, start) : cp);
}