options.c

自己精简过的PPPD代码。在嵌入中应用可以更好的发挥。比原先的小了很多

 * readable - check if a file is readable by the real user.
 */
int
readable(fd)
    int fd;
{
    uid_t uid;
    int i;
    struct stat sbuf;

    uid = getuid();
    if (uid == 0)
	return 1;
    if (fstat(fd, &sbuf) != 0)
	return 0;
    if (sbuf.st_uid == uid)
	return sbuf.st_mode & S_IRUSR;
    if (sbuf.st_gid == getgid())
	return sbuf.st_mode & S_IRGRP;
    for (i = 0; i < ngroups; ++i)
	if (sbuf.st_gid == groups[i])
	    return sbuf.st_mode & S_IRGRP;
    return sbuf.st_mode & S_IROTH;
}
#endif

/*
 * Read a word from a file.
 * Words are delimited by white-space or by quotes (" or ').
 * Quotes, white-space and \ may be escaped with \.
 * \<newline> is ignored.
 */
int
getword(f, word, newlinep, filename)
    FILE *f;
    char *word;
    int *newlinep;
    char *filename;
{
    int c, len, escape;
    int quoted, comment;
    int value, digit, got, n;

#define isoctal(c) ((c) >= '0' && (c) < '8')

    *newlinep = 0;
    len = 0;
    escape = 0;
    comment = 0;

    /*
     * First skip white-space and comments.
     */
    for (;;) {
	c = getc(f);
	if (c == EOF)
	    break;

	/*
	 * A newline means the end of a comment; backslash-newline
	 * is ignored.  Note that we cannot have escape && comment.
	 */
	if (c == '\n') {
	    if (!escape) {
		*newlinep = 1;
		comment = 0;
	    } else
		escape = 0;
	    continue;
	}

	/*
	 * Ignore characters other than newline in a comment.
	 */
	if (comment)
	    continue;

	/*
	 * If this character is escaped, we have a word start.
	 */
	if (escape)
	    break;

	/*
	 * If this is the escape character, look at the next character.
	 */
	if (c == '\\') {
	    escape = 1;
	    continue;
	}

	/*
	 * If this is the start of a comment, ignore the rest of the line.
	 */
	if (c == '#') {
	    comment = 1;
	    continue;
	}

	/*
	 * A non-whitespace character is the start of a word.
	 */
	if (!isspace(c))
	    break;
    }

    /*
     * Save the delimiter for quoted strings.
     */
    if (!escape && (c == '"' || c == '\'')) {
        quoted = c;
	c = getc(f);
    } else
        quoted = 0;

    /*
     * Process characters until the end of the word.
     */
    while (c != EOF) {
	if (escape) {
	    /*
	     * This character is escaped: backslash-newline is ignored,
	     * various other characters indicate particular values
	     * as for C backslash-escapes.
	     */
	    escape = 0;
	    if (c == '\n') {
	        c = getc(f);
		continue;
	    }

	    got = 0;
	    switch (c) {
	    case 'a':
		value = '\a';
		break;
	    case 'b':
		value = '\b';
		break;
	    case 'f':
		value = '\f';
		break;
	    case 'n':
		value = '\n';
		break;
	    case 'r':
		value = '\r';
		break;
	    case 's':
		value = ' ';
		break;
	    case 't':
		value = '\t';
		break;

	    default:
		if (isoctal(c)) {
		    /*
		     * \ddd octal sequence
		     */
		    value = 0;
		    for (n = 0; n < 3 && isoctal(c); ++n) {
			value = (value << 3) + (c & 07);
			c = getc(f);
		    }
		    got = 1;
		    break;
		}

		if (c == 'x') {
		    /*
		     * \x<hex_string> sequence
		     */
		    value = 0;
		    c = getc(f);
		    for (n = 0; n < 2 && isxdigit(c); ++n) {
			digit = toupper(c) - '0';
			if (digit > 10)
			    digit += '0' + 10 - 'A';
			value = (value << 4) + digit;
			c = getc (f);
		    }
		    got = 1;
		    break;
		}

		/*
		 * Otherwise the character stands for itself.
		 */
		value = c;
		break;
	    }

	    /*
	     * Store the resulting character for the escape sequence.
	     */
	    if (len < MAXWORDLEN-1)
		word[len] = value;
	    ++len;

	    if (!got)
		c = getc(f);
	    continue;

	}

	/*
	 * Not escaped: see if we've reached the end of the word.
	 */
	if (quoted) {
	    if (c == quoted)
		break;
	} else {
	    if (isspace(c) || c == '#') {
		ungetc (c, f);
		break;
	    }
	}

	/*
	 * Backslash starts an escape sequence.
	 */
	if (c == '\\') {
	    escape = 1;
	    c = getc(f);
	    continue;
	}

	/*
	 * An ordinary character: store it in the word and get another.
	 */
	if (len < MAXWORDLEN-1)
	    word[len] = c;
	++len;

	c = getc(f);
    }

    /*
     * End of the word: check for errors.
     */
    if (c == EOF) {
	if (ferror(f)) {
	    if (errno == 0)
		errno = EIO;
	    option_error("Error reading %s: %m", filename);
	    die(1);
	}
	/*
	 * If len is zero, then we didn't find a word before the
	 * end of the file.
	 */
	if (len == 0)
	    return 0;
    }

    /*
     * Warn if the word was too long, and append a terminating null.
     */
    if (len >= MAXWORDLEN) {
	option_error("warning: word in file %s too long (%.20s...)",
		     filename, word);
	len = MAXWORDLEN - 1;
    }
    word[len] = 0;

    return 1;

#undef isoctal

}

/*
 * number_option - parse an unsigned numeric parameter for an option.
 */
static int
number_option(str, valp, base)
    char *str;
    u_int32_t *valp;
    int base;
{
    char *ptr;

    *valp = strtoul(str, &ptr, base);
    if (ptr == str) {
	option_error("invalid numeric parameter '%s' for %s option",
		     str, current_option);
	return 0;
    }
    return 1;
}


/*
 * int_option - like number_option, but valp is int *,
 * the base is assumed to be 0, and *valp is not changed
 * if there is an error.
 */
int
int_option(str, valp)
    char *str;
    int *valp;
{
    u_int32_t v;

    if (!number_option(str, &v, 0))
	return 0;
    *valp = (int) v;
    return 1;
}


/*
 * The following procedures parse options.
 */

/*
 * readfile - take commands from a file.
 */
static int
readfile(argv)
    char **argv;
{
    return options_from_file(*argv, 1, 1, privileged_option);
}

/*
 * callfile - take commands from /etc/ppp/peers/<name>.
 * Name may not contain /../, start with / or ../, or end in /..
 */
static int
callfile(argv)
    char **argv;
{
    char *fname, *arg, *p;
    int l, ok;

    arg = *argv;
    ok = 1;
    if (arg[0] == '/' || arg[0] == 0)
	ok = 0;
    else {
	for (p = arg; *p != 0; ) {
	    if (p[0] == '.' && p[1] == '.' && (p[2] == '/' || p[2] == 0)) {
		ok = 0;
		break;
	    }
	    while (*p != '/' && *p != 0)
		++p;
	    if (*p == '/')
		++p;
	}
    }
    if (!ok) {
	option_error("call option value may not contain .. or start with /");
	return 0;
    }

    l = strlen(arg) + strlen(_PATH_PEERFILES) + 1;
    if ((fname = (char *) malloc(l)) == NULL)
	novm("call file name");
    slprintf(fname, l, "%s%s", _PATH_PEERFILES, arg);

    ok = options_from_file(fname, 1, 1, 1);

    free(fname);
    return ok;
}

#ifdef PPP_FILTER
/*
 * setpassfilter - Set the pass filter for packets
 */
static int
setpassfilter(argv)
    char **argv;
{
    pcap_t *pc;
    int ret = 1;

    pc = pcap_open_dead(DLT_PPP_PPPD, 65535);
    if (pcap_compile(pc, &pass_filter, *argv, 1, netmask) == -1) {
	option_error("error in pass-filter expression: %s\n",
		     pcap_geterr(pc));
	ret = 0;
    }
    pcap_close(pc);

    return ret;
}

/*
 * setactivefilter - Set the active filter for packets
 */
static int
setactivefilter(argv)
    char **argv;
{
    pcap_t *pc;
    int ret = 1;

    pc = pcap_open_dead(DLT_PPP_PPPD, 65535);
    if (pcap_compile(pc, &active_filter, *argv, 1, netmask) == -1) {
	option_error("error in active-filter expression: %s\n",
		     pcap_geterr(pc));
	ret = 0;
    }
    pcap_close(pc);

    return ret;
}
#endif

/*
 * setdomain - Set domain name to append to hostname 
 */
static int
setdomain(argv)
    char **argv;
{
    gethostname(hostname, MAXNAMELEN);
    if (**argv != 0) {
	if (**argv != '.')
	    strncat(hostname, ".", MAXNAMELEN - strlen(hostname));
	domain = hostname + strlen(hostname);
	strncat(hostname, *argv, MAXNAMELEN - strlen(hostname));
    }
    hostname[MAXNAMELEN-1] = 0;
    return (1);
}

static int
setlogfile(argv)
    char **argv;
{
    int fd, err;
    uid_t euid;

    euid = geteuid();
    if (!privileged_option && seteuid(getuid()) == -1) {
	option_error("unable to drop permissions to open %s: %m", *argv);
	return 0;
    }
    fd = open(*argv, O_WRONLY | O_APPEND | O_CREAT | O_EXCL, 0644);
    if (fd < 0 && errno == EEXIST)
	fd = open(*argv, O_WRONLY | O_APPEND);
    err = errno;
    if (!privileged_option && seteuid(euid) == -1)
	fatal("unable to regain privileges: %m");
    if (fd < 0) {
	errno = err;
	option_error("Can't open log file %s: %m", *argv);
	return 0;
    }
    strlcpy(logfile_name, *argv, sizeof(logfile_name));
    if (logfile_fd >= 0)
	close(logfile_fd);
    logfile_fd = fd;
    log_to_fd = fd;
    log_default = 0;
    return 1;
}

#ifdef MAXOCTETS
static int
setmodir(argv)
    char **argv;
{
    if(*argv == NULL)
	return 0;
    if(!strcmp(*argv,"in")) {
        maxoctets_dir = PPP_OCTETS_DIRECTION_IN;
    } else if (!strcmp(*argv,"out")) {
        maxoctets_dir = PPP_OCTETS_DIRECTION_OUT;
    } else if (!strcmp(*argv,"max")) {
        maxoctets_dir = PPP_OCTETS_DIRECTION_MAXOVERAL;
    } else {
        maxoctets_dir = PPP_OCTETS_DIRECTION_SUM;
    }
    return 1;
}
#endif

#ifdef PLUGIN
static int
loadplugin(argv)
    char **argv;
{
    char *arg = *argv;
    void *handle;
    const char *err;
    void (*init) __P((void));
    char *path = arg;
    const char *vers;

    if (strchr(arg, '/') == 0) {
	const char *base = _PATH_PLUGIN;
	int l = strlen(base) + strlen(arg) + 2;
	path = malloc(l);
	if (path == 0)
	    novm("plugin file path");
	strlcpy(path, base, l);
	strlcat(path, "/", l);
	strlcat(path, arg, l);
    }
    handle = dlopen(path, RTLD_GLOBAL | RTLD_NOW);
    if (handle == 0) {
	err = dlerror();
	if (err != 0)
	    option_error("%s", err);
	option_error("Couldn't load plugin %s", arg);
	goto err;
    }
    init = (void (*)(void))dlsym(handle, "plugin_init");
    if (init == 0) {
	option_error("%s has no initialization entry point", arg);
	goto errclose;
    }
    vers = (const char *) dlsym(handle, "pppd_version");
    if (vers == 0) {
	warn("Warning: plugin %s has no version information", arg);
    } else if (strcmp(vers, VERSION) != 0) {
	option_error("Plugin %s is for pppd version %s, this is %s",
		     arg, vers, VERSION);
	goto errclose;
    }
    info("Plugin %s loaded.", arg);
    (*init)();
    return 1;

 errclose:
    dlclose(handle);
 err:
    if (path != arg)
	free(path);
    return 0;
}
#endif /* PLUGIN */