auth.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

    /*
     * Count the number of IP addresses given.
     */
    n = wordlist_count(addrs) + wordlist_count(noauth_addrs);
    if (n == 0)
	return;
    ip = (struct permitted_ip *) malloc((n + 1) * sizeof(struct permitted_ip));
    if (ip == 0)
	return;

    /* temporarily append the noauth_addrs list to addrs */
    for (plink = &addrs; *plink != NULL; plink = &(*plink)->next)
	;
    *plink = noauth_addrs;

    n = 0;
    for (ap = addrs; ap != NULL; ap = ap->next) {
	/* "-" means no addresses authorized, "*" means any address allowed */
	ptr_word = ap->word;
	if (strcmp(ptr_word, "-") == 0)
	    break;
	if (strcmp(ptr_word, "*") == 0) {
	    ip[n].permit = 1;
	    ip[n].base = ip[n].mask = 0;
	    ++n;
	    break;
	}

	ip[n].permit = 1;
	if (*ptr_word == '!') {
	    ip[n].permit = 0;
	    ++ptr_word;
	}

	mask = ~ (u_int32_t) 0;
	offset = 0;
	ptr_mask = strchr (ptr_word, '/');
	if (ptr_mask != NULL) {
	    int bit_count;
	    char *endp;

	    bit_count = (int) strtol (ptr_mask+1, &endp, 10);
	    if (bit_count <= 0 || bit_count > 32) {
		warn("invalid address length %v in auth. address list",
		     ptr_mask+1);
		continue;
	    }
	    bit_count = 32 - bit_count;	/* # bits in host part */
	    if (*endp == '+') {
		offset = ifunit + 1;
		++endp;
	    }
	    if (*endp != 0) {
		warn("invalid address length syntax: %v", ptr_mask+1);
		continue;
	    }
	    *ptr_mask = '\0';
	    mask <<= bit_count;
	}

	hp = gethostbyname(ptr_word);
	if (hp != NULL && hp->h_addrtype == AF_INET) {
	    a = *(u_int32_t *)hp->h_addr;
	} else {
	    np = getnetbyname (ptr_word);
	    if (np != NULL && np->n_addrtype == AF_INET) {
		a = htonl ((u_int32_t)np->n_net);
		if (ptr_mask == NULL) {
		    /* calculate appropriate mask for net */
		    ah = ntohl(a);
		    if (IN_CLASSA(ah))
			mask = IN_CLASSA_NET;
		    else if (IN_CLASSB(ah))
			mask = IN_CLASSB_NET;
		    else if (IN_CLASSC(ah))
			mask = IN_CLASSC_NET;
		}
	    } else {
		a = inet_addr (ptr_word);
	    }
	}

	if (ptr_mask != NULL)
	    *ptr_mask = '/';

	if (a == (u_int32_t)-1L) {
	    warn("unknown host %s in auth. address list", ap->word);
	    continue;
	}
	if (offset != 0) {
	    if (offset >= ~mask) {
		warn("interface unit %d too large for subnet %v",
		     ifunit, ptr_word);
		continue;
	    }
	    a = htonl((ntohl(a) & mask) + offset);
	    mask = ~(u_int32_t)0;
	}
	ip[n].mask = htonl(mask);
	ip[n].base = a & ip[n].mask;
	++n;
	if (~mask == 0 && suggested_ip == 0)
	    suggested_ip = a;
    }
    *plink = NULL;

    ip[n].permit = 0;		/* make the last entry forbid all addresses */
    ip[n].base = 0;		/* to terminate the list */
    ip[n].mask = 0;

    addresses[unit] = ip;

    /*
     * If the address given for the peer isn't authorized, or if
     * the user hasn't given one, AND there is an authorized address
     * which is a single host, then use that if we find one.
     */
    if (suggested_ip != 0
	&& (wo->hisaddr == 0 || !auth_ip_addr(unit, wo->hisaddr))) {
	wo->hisaddr = suggested_ip;
	/*
	 * Do we insist on this address?  No, if there are other
	 * addresses authorized than the suggested one.
	 */
	if (n > 1)
	    wo->accept_remote = 1;
    }
}
#endif /* INCLUDE */

/*
 * auth_ip_addr - check whether the peer is authorized to use
 * a given IP address.  Returns 1 if authorized, 0 otherwise.
 */
int
auth_ip_addr(unit, addr)
    int unit;
    u_int32_t addr;
{
    int ok;

    /* don't allow loopback or multicast address */
    if (bad_ip_adrs(addr))
	return 0;

    if (allowed_address_hook) {
	ok = allowed_address_hook(addr);
	if (ok >= 0) return ok;
    }

    if (addresses[unit] != NULL) {
	ok = ip_addr_check(addr, addresses[unit]);
	if (ok >= 0)
	    return ok;
    }

    if (auth_required)
	return 0;		/* no addresses authorized */
    return allow_any_ip || privileged || !have_route_to(addr);
}

static int
ip_addr_check(addr, addrs)
    u_int32_t addr;
    struct permitted_ip *addrs;
{
    for (; ; ++addrs)
	if ((addr & addrs->mask) == addrs->base)
	    return addrs->permit;
}

/*
 * bad_ip_adrs - return 1 if the IP address is one we don't want
 * to use, such as an address in the loopback net or a multicast address.
 * addr is in network byte order.
 */
int
bad_ip_adrs(addr)
    u_int32_t addr;
{
    addr = ntohl(addr);
    return (addr >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET
	|| IN_MULTICAST(addr) || IN_BADCLASS(addr);
}

/*
 * some_ip_ok - check a wordlist to see if it authorizes any
 * IP address(es).
 */
static int
some_ip_ok(addrs)
    struct wordlist *addrs;
{
    for (; addrs != 0; addrs = addrs->next) {
	if (addrs->word[0] == '-')
	    break;
	if (addrs->word[0] != '!')
	    return 1;		/* some IP address is allowed */
    }
    return 0;
}

/*
 * auth_number - check whether the remote number is allowed to connect.
 * Returns 1 if authorized, 0 otherwise.
 */
int
auth_number()
{
    struct wordlist *wp = permitted_numbers;
    int l;

    /* Allow all if no authorization list. */
    if (!wp)
	return 1;

    /* Allow if we have a match in the authorization list. */
    while (wp) {
	/* trailing '*' wildcard */
	l = strlen(wp->word);
	if ((wp->word)[l - 1] == '*')
	    l--;
	if (!strncasecmp(wp->word, remote_number, l))
	    return 1;
	wp = wp->next;
    }

    return 0;
}

#ifdef INCLUDE
/*
 * check_access - complain if a secret file has too-liberal permissions.
 */
static void
check_access(f, filename)
    FILE *f;
    char *filename;
{
    struct stat sbuf;

    if (fstat(fileno(f), &sbuf) < 0) {
	warn("cannot stat secret file %s: %m", filename);
    } else if ((sbuf.st_mode & (S_IRWXG | S_IRWXO)) != 0) {
	warn("Warning - secret file %s has world and/or group access",
	     filename);
    }
}


/*
 * scan_authfile - Scan an authorization file for a secret suitable
 * for authenticating `client' on `server'.  The return value is -1
 * if no secret is found, otherwise >= 0.  The return value has
 * NONWILD_CLIENT set if the secret didn't have "*" for the client, and
 * NONWILD_SERVER set if the secret didn't have "*" for the server.
 * Any following words on the line up to a "--" (i.e. address authorization
 * info) are placed in a wordlist and returned in *addrs.  Any
 * following words (extra options) are placed in a wordlist and
 * returned in *opts.
 * We assume secret is NULL or points to MAXWORDLEN bytes of space.
 * Flags are non-zero if we need two colons in the secret in order to
 * match.
 */

static int
scan_authfile(f, client, server, secret, addrs, opts, filename, flags)
    FILE *f;
    char *client;
    char *server;
    char *secret;
    struct wordlist **addrs;
    struct wordlist **opts;
    char *filename;
    int flags;
{
    int newline, xxx;
    int got_flag, best_flag;
    FILE *sf;
    struct wordlist *ap, *addr_list, *alist, **app;
    char word[MAXWORDLEN];
    char atfile[MAXWORDLEN];
    char lsecret[MAXWORDLEN];
    char *cp;

    if (addrs != NULL)
	*addrs = NULL;
    if (opts != NULL)
	*opts = NULL;
    addr_list = NULL;
    /*/if (!getword(f, word, &newline, filename))
	return -1;*/		/* file is empty??? */
    newline = 1;
    best_flag = -1;
    for (;;) {
	/*
	 * Skip until we find a word at the start of a line.
	 */
	/*/while (!newline && getword(f, word, &newline, filename))
	    ;*/
	if (!newline)
	    break;		/* got to end of file */

	/*
	 * Got a client - check if it's a match or a wildcard.
	 */
	got_flag = 0;
	if (client != NULL && strcmp(word, client) != 0 && !ISWILD(word)) {
	    newline = 0;
	    continue;
	}
	if (!ISWILD(word))
	    got_flag = NONWILD_CLIENT;

	/*
	 * Now get a server and check if it matches.
	 */
	/*/if (!getword(f, word, &newline, filename))
	    break;*/
	if (newline)
	    continue;
	if (!ISWILD(word)) {
	    if (server != NULL && strcmp(word, server) != 0)
		continue;
	    got_flag |= NONWILD_SERVER;
	}

	/*
	 * Got some sort of a match - see if it's better than what
	 * we have already.
	 */
	if (got_flag <= best_flag)
	    continue;

	/*
	 * Get the secret.
	 */
	/*/if (!getword(f, word, &newline, filename))
	    break;*/
	if (newline)
	    continue;

	/*
	 * SRP-SHA1 authenticator should never be reading secrets from
	 * a file.  (Authenticatee may, though.)
	 */
	if (flags && ((cp = strchr(word, ':')) == NULL ||
	    strchr(cp + 1, ':') == NULL))
	    continue;

	if (secret != NULL) {
	    /*
	     * Special syntax: @/pathname means read secret from file.
	     */
	    if (word[0] == '@' && word[1] == '/') {
		strlcpy(atfile, word+1, sizeof(atfile));
		if ((sf = fopen(atfile, "r")) == NULL) {
		    warn("can't open indirect secret file %s", atfile);
		    continue;
		}
		check_access(sf, atfile);
		if (!getword(sf, word, &xxx, atfile)) {
		    warn("no secret in indirect secret file %s", atfile);
		    fclose(sf);
		    continue;
		}
		fclose(sf);
	    }
	    strlcpy(lsecret, word, sizeof(lsecret));
	}

	/*
	 * Now read address authorization info and make a wordlist.
	 */
	app = &alist;
	for (;;) {
	    if (!getword(f, word, &newline, filename) || newline)
		break;
	    ap = (struct wordlist *)
		    malloc(sizeof(struct wordlist) + strlen(word) + 1);
	    if (ap == NULL)
		novm("authorized addresses");
	    ap->word = (char *) (ap + 1);
	    strcpy(ap->word, word);
	    *app = ap;
	    app = &ap->next;
	}
	*app = NULL;

	/*
	 * This is the best so far; remember it.
	 */
	best_flag = got_flag;
	if (addr_list)
	    free_wordlist(addr_list);
	addr_list = alist;
	if (secret != NULL)
	    strlcpy(secret, lsecret, MAXWORDLEN);

	if (!newline)
	    break;
    }

    /* scan for a -- word indicating the start of options */
    for (app = &addr_list; (ap = *app) != NULL; app = &ap->next)
	if (strcmp(ap->word, "--") == 0)
	    break;
    /* ap = start of options */
    if (ap != NULL) {
	ap = ap->next;		/* first option */
	free(*app);			/* free the "--" word */
	*app = NULL;		/* terminate addr list */
    }
    if (opts != NULL)
	*opts = ap;
    else if (ap != NULL)
	free_wordlist(ap);
    if (addrs != NULL)
	*addrs = addr_list;
    else if (addr_list != NULL)
	free_wordlist(addr_list);

    return best_flag;
}

/*
 * wordlist_count - return the number of items in a wordlist
 */
static int
wordlist_count(wp)
    struct wordlist *wp;
{
    int n;

    for (n = 0; wp != NULL; wp = wp->next)
	++n;
    return n;
}

/*
 * free_wordlist - release memory allocated for a wordlist.
 */
static void
free_wordlist(wp)
    struct wordlist *wp;
{
    struct wordlist *next;

    while (wp != NULL) {
	next = wp->next;
	free(wp);
	wp = next;
    }
}
#endif /* INCLUDE */
/*
 * auth_script_done - called when the auth-up or auth-down script
 * has finished.
 */
static void
auth_script_done(arg)
    void *arg;
{
    auth_script_pid = 0;
    switch (auth_script_state) {
    case s_up:
	if (auth_state == s_down) {
	    auth_script_state = s_down;
	    auth_script(_PATH_AUTHDOWN);
	}
	break;
    case s_down:
	if (auth_state == s_up) {
	    auth_script_state = s_up;
	    auth_script(_PATH_AUTHUP);
	}
	break;
    }
}

/*
 * auth_script - execute a script with arguments
 * interface-name peer-name real-user tty speed
 */
static void
auth_script(script)
    char *script;
{
    char strspeed[32];
    struct passwd *pw;
    char struid[32];
    char *user_name;
    char *argv[8];

    if ((pw = getpwuid(getuid())) != NULL && pw->pw_name != NULL)
	user_name = pw->pw_name;
    else {
	slprintf(struid, sizeof(struid), "%d", getuid());
	user_name = struid;
    }
    slprintf(strspeed, sizeof(strspeed), "%d", baud_rate);

    argv[0] = script;
    argv[1] = ifname;
    argv[2] = peer_authname;
    argv[3] = user_name;
    argv[4] = devnam;
    argv[5] = strspeed;
    argv[6] = NULL;

    auth_script_pid = run_program(script, argv, 0, auth_script_done, NULL, 0);
}