options.c

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/*
 * options.c - handles option processing for PPP.
 *
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#define RCSID	"$Id: options.c,v 1.80 2001/03/12 22:56:12 paulus Exp $"

#include <ctype.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <syslog.h>
#include <string.h>
#include <pwd.h>
#ifdef PLUGIN
#include <dlfcn.h>
#endif
#ifdef PPP_FILTER
#include <pcap.h>
#include <pcap-int.h>	/* XXX: To get struct pcap */
#endif

#include "pppd.h"
#include "pathnames.h"

#if defined(ultrix) || defined(NeXT)
char *strdup __P((char *));
#endif

static const char rcsid[] = RCSID;

struct option_value {
    struct option_value *next;
    const char *source;
    char value[1];
};

/*
 * Option variables and default values.
 */
#ifdef PPP_FILTER
int	dflag = 0;		/* Tell libpcap we want debugging */
#endif
int	debug = 0;		/* Debug flag */
int	kdebugflag = 0;		/* Tell kernel to print debug messages */
int	default_device = 1;	/* Using /dev/tty or equivalent */
char	devnam[MAXPATHLEN];	/* Device name */
bool	nodetach = 0;		/* Don't detach from controlling tty */
bool	updetach = 0;		/* Detach once link is up */
int	maxconnect = 0;		/* Maximum connect time */
char	user[MAXNAMELEN];	/* Username for PAP */
char	passwd[MAXSECRETLEN];	/* Password for PAP */
bool	persist = 0;		/* Reopen link after it goes down */
char	our_name[MAXNAMELEN];	/* Our name for authentication purposes */
bool	demand = 0;		/* do dial-on-demand */
char	*ipparam = NULL;	/* Extra parameter for ip up/down scripts */
int	idle_time_limit = 0;	/* Disconnect if idle for this many seconds */
int	holdoff = 30;		/* # seconds to pause before reconnecting */
bool	holdoff_specified;	/* true if a holdoff value has been given */
int	log_to_fd = 1;		/* send log messages to this fd too */
bool	log_default = 1;	/* log_to_fd is default (stdout) */
int	maxfail = 10;		/* max # of unsuccessful connection attempts */
char	linkname[MAXPATHLEN];	/* logical name for link */
bool	tune_kernel;		/* may alter kernel settings */
int	connect_delay = 1000;	/* wait this many ms after connect script */
int	req_unit = -1;		/* requested interface unit */
bool	multilink = 0;		/* Enable multilink operation */
char	*bundle_name = NULL;	/* bundle name for multilink */
bool	dump_options;		/* print out option values */
bool	dryrun;			/* print out option values and exit */
char	*domain;		/* domain name set by domain option */

extern option_t auth_options[];
extern struct stat devstat;

#ifdef PPP_FILTER
struct	bpf_program pass_filter;/* Filter program for packets to pass */
struct	bpf_program active_filter; /* Filter program for link-active pkts */
pcap_t  pc;			/* Fake struct pcap so we can compile expr */
#endif

char *current_option;		/* the name of the option being parsed */
int  privileged_option;		/* set iff the current option came from root */
char *option_source;		/* string saying where the option came from */
int  option_priority = OPRIO_CFGFILE; /* priority of the current options */
bool devnam_fixed;		/* can no longer change device name */

static int logfile_fd = -1;	/* fd opened for log file */
static char logfile_name[MAXPATHLEN];	/* name of log file */

/*
 * Prototypes
 */
static int setdomain __P((char **));
static int readfile __P((char **));
static int callfile __P((char **));
static int showversion __P((char **));
static int showhelp __P((char **));
static void usage __P((void));
static int setlogfile __P((char **));
#ifdef PLUGIN
static int loadplugin __P((char **));
#endif

#ifdef PPP_FILTER
static int setpassfilter __P((char **));
static int setactivefilter __P((char **));
#endif

static option_t *find_option __P((const char *name));
static int process_option __P((option_t *, char *, char **));
static int n_arguments __P((option_t *));
static int number_option __P((char *, u_int32_t *, int));

/*
 * Structure to store extra lists of options.
 */
struct option_list {
    option_t *options;
    struct option_list *next;
};

static struct option_list *extra_options = NULL;

/*
 * Valid arguments.
 */
option_t general_options[] = {
    { "debug", o_int, &debug,
      "Increase debugging level", OPT_INC | OPT_NOARG | 1 },
    { "-d", o_int, &debug,
      "Increase debugging level",
      OPT_ALIAS | OPT_INC | OPT_NOARG | 1 },

    { "kdebug", o_int, &kdebugflag,
      "Set kernel driver debug level", OPT_PRIO },

    { "nodetach", o_bool, &nodetach,
      "Don't detach from controlling tty", OPT_PRIO | 1 },
    { "-detach", o_bool, &nodetach,
      "Don't detach from controlling tty", OPT_ALIAS | OPT_PRIOSUB | 1 },
    { "updetach", o_bool, &updetach,
      "Detach from controlling tty once link is up",
      OPT_PRIOSUB | OPT_A2CLR | 1, &nodetach },

    { "holdoff", o_int, &holdoff,
      "Set time in seconds before retrying connection", OPT_PRIO },

    { "idle", o_int, &idle_time_limit,
      "Set time in seconds before disconnecting idle link", OPT_PRIO },

    { "maxconnect", o_int, &maxconnect,
      "Set connection time limit",
      OPT_PRIO | OPT_LLIMIT | OPT_NOINCR | OPT_ZEROINF },

    { "domain", o_special, (void *)setdomain,
      "Add given domain name to hostname",
      OPT_PRIO | OPT_PRIV | OPT_A2STRVAL, &domain },

    { "file", o_special, (void *)readfile,
      "Take options from a file", OPT_NOPRINT },
    { "call", o_special, (void *)callfile,
      "Take options from a privileged file", OPT_NOPRINT },

    { "persist", o_bool, &persist,
      "Keep on reopening connection after close", OPT_PRIO | 1 },
    { "nopersist", o_bool, &persist,
      "Turn off persist option", OPT_PRIOSUB },

    { "demand", o_bool, &demand,
      "Dial on demand", OPT_INITONLY | 1, &persist },

    { "--version", o_special_noarg, (void *)showversion,
      "Show version number" },
    { "--help", o_special_noarg, (void *)showhelp,
      "Show brief listing of options" },
    { "-h", o_special_noarg, (void *)showhelp,
      "Show brief listing of options", OPT_ALIAS },

    { "logfile", o_special, (void *)setlogfile,
      "Append log messages to this file",
      OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, &logfile_name },
    { "logfd", o_int, &log_to_fd,
      "Send log messages to this file descriptor",
      OPT_PRIOSUB | OPT_A2CLR, &log_default },
    { "nolog", o_int, &log_to_fd,
      "Don't send log messages to any file",
      OPT_PRIOSUB | OPT_NOARG | OPT_VAL(-1) },
    { "nologfd", o_int, &log_to_fd,
      "Don't send log messages to any file descriptor",
      OPT_PRIOSUB | OPT_ALIAS | OPT_NOARG | OPT_VAL(-1) },

    { "linkname", o_string, linkname,
      "Set logical name for link",
      OPT_PRIO | OPT_PRIV | OPT_STATIC, NULL, MAXPATHLEN },

    { "maxfail", o_int, &maxfail,
      "Maximum number of unsuccessful connection attempts to allow",
      OPT_PRIO },

    { "ktune", o_bool, &tune_kernel,
      "Alter kernel settings as necessary", OPT_PRIO | 1 },
    { "noktune", o_bool, &tune_kernel,
      "Don't alter kernel settings", OPT_PRIOSUB },

    { "connect-delay", o_int, &connect_delay,
      "Maximum time (in ms) to wait after connect script finishes",
      OPT_PRIO },

    { "unit", o_int, &req_unit,
      "PPP interface unit number to use if possible",
      OPT_PRIO | OPT_LLIMIT, 0, 0 },

    { "dump", o_bool, &dump_options,
      "Print out option values after parsing all options", 1 },
    { "dryrun", o_bool, &dryrun,
      "Stop after parsing, printing, and checking options", 1 },

#ifdef HAVE_MULTILINK
    { "multilink", o_bool, &multilink,
      "Enable multilink operation", OPT_PRIO | 1 },
    { "mp", o_bool, &multilink,
      "Enable multilink operation", OPT_PRIOSUB | OPT_ALIAS | 1 },
    { "nomultilink", o_bool, &multilink,
      "Disable multilink operation", OPT_PRIOSUB | 0 },
    { "nomp", o_bool, &multilink,
      "Disable multilink operation", OPT_PRIOSUB | OPT_ALIAS | 0 },

    { "bundle", o_string, &bundle_name,
      "Bundle name for multilink", OPT_PRIO },
#endif /* HAVE_MULTILINK */

#ifdef PLUGIN
    { "plugin", o_special, (void *)loadplugin,
      "Load a plug-in module into pppd", OPT_PRIV | OPT_A2LIST },
#endif

#ifdef PPP_FILTER
    { "pdebug", o_int, &dflag,
      "libpcap debugging", OPT_PRIO },

    { "pass-filter", 1, setpassfilter,
      "set filter for packets to pass", OPT_PRIO },

    { "active-filter", 1, setactivefilter,
      "set filter for active pkts", OPT_PRIO },
#endif

    { NULL }
};

#ifndef IMPLEMENTATION
#define IMPLEMENTATION ""
#endif

static char *usage_string = "\
pppd version %s\n\
Usage: %s [ options ], where options are:\n\
	<device>	Communicate over the named device\n\
	<speed>		Set the baud rate to <speed>\n\
	<loc>:<rem>	Set the local and/or remote interface IP\n\
			addresses.  Either one may be omitted.\n\
	asyncmap <n>	Set the desired async map to hex <n>\n\
	auth		Require authentication from peer\n\
        connect <p>     Invoke shell command <p> to set up the serial line\n\
	crtscts		Use hardware RTS/CTS flow control\n\
	defaultroute	Add default route through interface\n\
	file <f>	Take options from file <f>\n\
	modem		Use modem control lines\n\
	mru <n>		Set MRU value to <n> for negotiation\n\
See pppd(8) for more options.\n\
";

/*
 * parse_args - parse a string of arguments from the command line.
 */
int
parse_args(argc, argv)
    int argc;
    char **argv;
{
    char *arg;
    option_t *opt;
    int n;
    privileged_option = privileged;
    option_source = "command line";
    option_priority = OPRIO_CMDLINE;
    while (argc > 0) {
	arg = *argv++;
	--argc;
	opt = find_option(arg);
	if (opt == NULL) {
	    option_error("unrecognized option '%s'", arg);
	    usage();
	    return 0;
	}
	n = n_arguments(opt);
	if (argc < n) {
	    option_error("too few parameters for option %s", arg);
	    return 0;
	}
	if (!process_option(opt, arg, argv))
	    return 0;
	argc -= n;
	argv += n;
    }
    return 1;
}

/*
 * options_from_file - Read a string of options from a file,
 * and interpret them.
 */
int
options_from_file(filename, must_exist, check_prot, priv)
    char *filename;
    int must_exist;
    int check_prot;
    int priv;
{
    FILE *f;
    int i, newline, ret, err;
    option_t *opt;
    int oldpriv, n;
    char *oldsource;
    char *argv[MAXARGS];
    char args[MAXARGS][MAXWORDLEN];
    char cmd[MAXWORDLEN];

    if (check_prot)
	seteuid(getuid());
    f = fopen(filename, "r");
    err = errno;
    if (check_prot)
	seteuid(0);
    if (f == NULL) {
	errno = err;
	if (!must_exist) {
	    if (err != ENOENT && err != ENOTDIR)
		warn("Warning: can't open options file %s: %m", filename);
	    return 1;
	}
	option_error("Can't open options file %s: %m", filename);
	return 0;
    }

    oldpriv = privileged_option;
    privileged_option = priv;
    oldsource = option_source;
    option_source = strdup(filename);
    if (option_source == NULL)
	option_source = "file";
    ret = 0;
    while (getword(f, cmd, &newline, filename)) {
	opt = find_option(cmd);
	if (opt == NULL) {
	    option_error("In file %s: unrecognized option '%s'",
			 filename, cmd);
	    goto err;
	}
	n = n_arguments(opt);
	for (i = 0; i < n; ++i) {
	    if (!getword(f, args[i], &newline, filename)) {
		option_error(
			"In file %s: too few parameters for option '%s'",
			filename, cmd);
		goto err;
	    }
	    argv[i] = args[i];
	}
	if (!process_option(opt, cmd, argv))
	    goto err;
    }
    ret = 1;

err:
    fclose(f);
    privileged_option = oldpriv;
    option_source = oldsource;
    return ret;
}

/*
 * options_from_user - See if the use has a ~/.ppprc file,
 * and if so, interpret options from it.
 */
int
options_from_user()
{
    char *user, *path, *file;
    int ret;
    struct passwd *pw;
    size_t pl;

    pw = getpwuid(getuid());
    if (pw == NULL || (user = pw->pw_dir) == NULL || user[0] == 0)
	return 1;
    file = _PATH_USEROPT;
    pl = strlen(user) + strlen(file) + 2;
    path = malloc(pl);
    if (path == NULL)
	novm("init file name");
    slprintf(path, pl, "%s/%s", user, file);
    option_priority = OPRIO_CFGFILE;
    ret = options_from_file(path, 0, 1, privileged);
    free(path);
    return ret;
}

/*
 * options_for_tty - See if an options file exists for the serial
 * device, and if so, interpret options from it.
 * We only allow the per-tty options file to override anything from
 * the command line if it is something that the user can't override
 * once it has been set by root; this is done by giving configuration
 * files a lower priority than the command line.
 */
int
options_for_tty()
{
    char *dev, *path, *p;
    int ret;
    size_t pl;

    dev = devnam;
    if (strncmp(dev, "/dev/", 5) == 0)
	dev += 5;
    if (dev[0] == 0 || strcmp(dev, "tty") == 0)
	return 1;		/* don't look for /etc/ppp/options.tty */
    pl = strlen(_PATH_TTYOPT) + strlen(dev) + 1;
    path = malloc(pl);
    if (path == NULL)
	novm("tty init file name");
    slprintf(path, pl, "%s%s", _PATH_TTYOPT, dev);
    /* Turn slashes into dots, for Solaris case (e.g. /dev/term/a) */
    for (p = path + strlen(_PATH_TTYOPT); *p != 0; ++p)
	if (*p == '/')
	    *p = '.';
    option_priority = OPRIO_CFGFILE;
    ret = options_from_file(path, 0, 0, 1);
    free(path);
    return ret;
}

/*
 * options_from_list - process a string of options in a wordlist.
 */
int
options_from_list(w, priv)
    struct wordlist *w;
    int priv;
{
    char *argv[MAXARGS];
    option_t *opt;
    int i, n, ret = 0;
    struct wordlist *w0;

    privileged_option = priv;
    option_source = "secrets file";
    option_priority = OPRIO_SECFILE;

    while (w != NULL) {
	opt = find_option(w->word);
	if (opt == NULL) {
	    option_error("In secrets file: unrecognized option '%s'",
			 w->word);
	    goto err;
	}
	n = n_arguments(opt);
	w0 = w;
	for (i = 0; i < n; ++i) {
	    w = w->next;
	    if (w == NULL) {
		option_error(
			"In secrets file: too few parameters for option '%s'",
			w0->word);
		goto err;
	    }
	    argv[i] = w->word;
	}
	if (!process_option(opt, w0->word, argv))
	    goto err;
	w = w->next;
    }
    ret = 1;

err:
    return ret;
}