auth.c

《嵌入式网络系统设计-基于Atmel ARM7 系列》这个本书的光盘资料

/*
 * auth_reset - called when LCP is starting negotiations to recheck
 * authentication options, i.e. whether we have appropriate secrets
 * to use for authenticating ourselves and/or the peer.
 */
void auth_reset(int unit)
{
    lcp_options *go = &lcp_gotoptions[unit];
    lcp_options *ao = &lcp_allowoptions[0];
    ipcp_options *ipwo = &ipcp_wantoptions[0];
    u32_t remote;
    
    AUTHDEBUG((LOG_INFO, "auth_reset: %d\n", unit));
    ao->neg_upap = !ppp_settings.refuse_pap && (ppp_settings.passwd[0] != 0 || get_pap_passwd(unit, NULL, NULL));
    ao->neg_chap = !ppp_settings.refuse_chap && ppp_settings.passwd[0] != 0 /*have_chap_secret(ppp_settings.user, ppp_settings.remote_name, (u32_t)0)*/;
    
    if (go->neg_upap && !have_pap_secret())
        go->neg_upap = 0;
    if (go->neg_chap) {
        remote = ipwo->accept_remote? 0: ipwo->hisaddr;
        if (!have_chap_secret(ppp_settings.remote_name, ppp_settings.our_name, remote))
            go->neg_chap = 0;
    }
}


#if PAP_SUPPORT > 0
/*
 * check_passwd - Check the user name and passwd against the PAP secrets
 * file.  If requested, also check against the system password database,
 * and login the user if OK.
 *
 * returns:
 *  UPAP_AUTHNAK: Authentication failed.
 *  UPAP_AUTHACK: Authentication succeeded.
 * In either case, msg points to an appropriate message.
 */
int check_passwd(
	int unit,
	char *auser,
	int userlen,
	char *apasswd,
	int passwdlen,
	char **msg,
	int *msglen
)
{
#if 1
	*msg = (char *) 0;
	return UPAP_AUTHACK;     /* XXX Assume all entries OK. */
#else
    int ret = 0;
    struct wordlist *addrs = NULL;
    char passwd[256], user[256];
    char secret[MAXWORDLEN];
    static u_short attempts = 0;
    
    /*
     * Make copies of apasswd and auser, then null-terminate them.
     */
    BCOPY(apasswd, passwd, passwdlen);
    passwd[passwdlen] = '\0';
    BCOPY(auser, user, userlen);
    user[userlen] = '\0';
    *msg = (char *) 0;

    /* XXX Validate user name and password. */
    ret = UPAP_AUTHACK;     /* XXX Assume all entries OK. */
        
    if (ret == UPAP_AUTHNAK) {
        if (*msg == (char *) 0)
            *msg = "Login incorrect";
        *msglen = strlen(*msg);
        /*
         * Frustrate passwd stealer programs.
         * Allow 10 tries, but start backing off after 3 (stolen from login).
         * On 10'th, drop the connection.
         */
        if (attempts++ >= 10) {
            AUTHDEBUG((LOG_WARNING, "%d LOGIN FAILURES BY %s\n", attempts, user));
            /*ppp_panic("Excess Bad Logins");*/
        }
        if (attempts > 3) {
            sys_msleep((attempts - 3) * 5);
        }
        if (addrs != NULL) {
            free_wordlist(addrs);
        }
    } else {
        attempts = 0;           /* Reset count */
        if (*msg == (char *) 0)
            *msg = "Login ok";
        *msglen = strlen(*msg);
        set_allowed_addrs(unit, addrs);
    }
    
    BZERO(passwd, sizeof(passwd));
    BZERO(secret, sizeof(secret));
    
    return ret;
#endif
}
#endif


/*
 * 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(int unit, u32_t addr)
{
    return ip_addr_check(addr, addresses[unit]);
}

/*
 * 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(u32_t addr)
{
    addr = ntohl(addr);
    return (addr >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET
        || IN_MULTICAST(addr) || IN_BADCLASS(addr);
}


#if CHAP_SUPPORT > 0
/*
 * get_secret - open the CHAP secret file and return the secret
 * for authenticating the given client on the given server.
 * (We could be either client or server).
 */
int get_secret(
    int unit,
    char *client,
    char *server,
    char *secret,
    int *secret_len,
    int save_addrs
)
{
#if 1
    int len;
    struct wordlist *addrs;
    
    addrs = NULL;

    if(!client || !client[0] || strcmp(client, ppp_settings.user)) {
	return 0;
    }

    len = strlen(ppp_settings.passwd);
    if (len > MAXSECRETLEN) {
        AUTHDEBUG((LOG_ERR, "Secret for %s on %s is too long\n", client, server));
        len = MAXSECRETLEN;
    }
    BCOPY(ppp_settings.passwd, secret, len);
    *secret_len = len;
    
    return 1;
#else
    int ret = 0, len;
    struct wordlist *addrs;
    char secbuf[MAXWORDLEN];
    
    addrs = NULL;
    secbuf[0] = 0;

    /* XXX Find secret. */  
    if (ret < 0)
        return 0;
    
    if (save_addrs)
        set_allowed_addrs(unit, addrs);
    
    len = strlen(secbuf);
    if (len > MAXSECRETLEN) {
        AUTHDEBUG((LOG_ERR, "Secret for %s on %s is too long\n", client, server));
        len = MAXSECRETLEN;
    }
    BCOPY(secbuf, secret, len);
    BZERO(secbuf, sizeof(secbuf));
    *secret_len = len;
    
    return 1;
#endif
}
#endif


#if 0 /* UNUSED */
/*
 * auth_check_options - called to check authentication options.
 */
void auth_check_options(void)
{
    lcp_options *wo = &lcp_wantoptions[0];
    int can_auth;
    ipcp_options *ipwo = &ipcp_wantoptions[0];
    u32_t remote;
    
    /* Default our_name to hostname, and user to our_name */
    if (ppp_settings.our_name[0] == 0 || ppp_settings.usehostname)
        strcpy(ppp_settings.our_name, ppp_settings.hostname);
    if (ppp_settings.user[0] == 0)
        strcpy(ppp_settings.user, ppp_settings.our_name);
    
    /* If authentication is required, ask peer for CHAP or PAP. */
    if (ppp_settings.auth_required && !wo->neg_chap && !wo->neg_upap) {
        wo->neg_chap = 1;
        wo->neg_upap = 1;
    }
    
    /*
     * Check whether we have appropriate secrets to use
     * to authenticate the peer.
     */
    can_auth = wo->neg_upap && have_pap_secret();
    if (!can_auth && wo->neg_chap) {
        remote = ipwo->accept_remote? 0: ipwo->hisaddr;
        can_auth = have_chap_secret(ppp_settings.remote_name, ppp_settings.our_name, remote);
    }
    
    if (ppp_settings.auth_required && !can_auth) {
        ppp_panic("No auth secret");
    }
}
#endif


/**********************************/
/*** LOCAL FUNCTION DEFINITIONS ***/
/**********************************/
/*
 * Proceed to the network phase.
 */
static void network_phase(int unit)
{
    int i;
    struct protent *protp;
    lcp_options *go = &lcp_gotoptions[unit];
    
    /*
     * If the peer had to authenticate, run the auth-up script now.
     */
    if ((go->neg_chap || go->neg_upap) && !did_authup) {
        /* XXX Do setup for peer authentication. */
        did_authup = 1;
    }
    
#if CBCP_SUPPORT > 0
    /*
     * If we negotiated callback, do it now.
     */
    if (go->neg_cbcp) {
        lcp_phase[unit] = PHASE_CALLBACK;
        (*cbcp_protent.open)(unit);
        return;
    }
#endif
    
    lcp_phase[unit] = PHASE_NETWORK;
    for (i = 0; (protp = ppp_protocols[i]) != NULL; ++i)
        if (protp->protocol < 0xC000 && protp->enabled_flag
                && protp->open != NULL) {
            (*protp->open)(unit);
            if (protp->protocol != PPP_CCP)
                ++num_np_open;
        }
    
    if (num_np_open == 0)
        /* nothing to do */
        lcp_close(0, "No network protocols running");
}

/*
 * check_idle - check whether the link has been idle for long
 * enough that we can shut it down.
 */
static void check_idle(void *arg)
{
    struct ppp_idle idle;
    u_short itime;
    
	(void)arg;
    if (!get_idle_time(0, &idle))
        return;
    itime = LWIP_MIN(idle.xmit_idle, idle.recv_idle);
    if (itime >= ppp_settings.idle_time_limit) {
        /* link is idle: shut it down. */
        AUTHDEBUG((LOG_INFO, "Terminating connection due to lack of activity.\n"));
        lcp_close(0, "Link inactive");
    } else {
        TIMEOUT(check_idle, NULL, ppp_settings.idle_time_limit - itime);
    }
}

/*
 * connect_time_expired - log a message and close the connection.
 */
static void connect_time_expired(void *arg)
{
	(void)arg;

    AUTHDEBUG((LOG_INFO, "Connect time expired\n"));
    lcp_close(0, "Connect time expired");   /* Close connection */
}

#if 0
/*
 * login - Check the user name and password against the system
 * password database, and login the user if OK.
 *
 * returns:
 *  UPAP_AUTHNAK: Login failed.
 *  UPAP_AUTHACK: Login succeeded.
 * In either case, msg points to an appropriate message.
 */
static int login(char *user, char *passwd, char **msg, int *msglen)
{
    /* XXX Fail until we decide that we want to support logins. */
    return (UPAP_AUTHNAK);
}
#endif

/*
 * logout - Logout the user.
 */
static void logout(void)
{
    logged_in = 0;
}


/*
 * null_login - Check if a username of "" and a password of "" are
 * acceptable, and iff so, set the list of acceptable IP addresses
 * and return 1.
 */
static int null_login(int unit)
{
	(void)unit;
    /* XXX Fail until we decide that we want to support logins. */
    return 0;
}


/*
 * get_pap_passwd - get a password for authenticating ourselves with
 * our peer using PAP.  Returns 1 on success, 0 if no suitable password
 * could be found.
 */
static int get_pap_passwd(int unit, char *user, char *passwd)
{
/* normally we would reject PAP if no password is provided,
   but this causes problems with some providers (like CHT in Taiwan)
   who incorrectly request PAP and expect a bogus/empty password, so
   always provide a default user/passwd of "none"/"none"
*/
    if(user)
    	strcpy(user,   "none");
    if(passwd)
    	strcpy(passwd, "none");

    return 1;
}


/*
 * have_pap_secret - check whether we have a PAP file with any
 * secrets that we could possibly use for authenticating the peer.
 */
static int have_pap_secret(void)
{
    /* XXX Fail until we set up our passwords. */
    return 0;
}


/*
 * have_chap_secret - check whether we have a CHAP file with a
 * secret that we could possibly use for authenticating `client'
 * on `server'.  Either can be the null string, meaning we don't
 * know the identity yet.
 */
static int have_chap_secret(char *client, char *server, u32_t remote)
{
	(void)client;
	(void)server;
	(void)remote;
    /* XXX Fail until we set up our passwords. */
    return 0;
}


#if 0 /* PAP_SUPPORT > 0 || CHAP_SUPPORT > 0 */
/*
 * set_allowed_addrs() - set the list of allowed addresses.
 */
static void set_allowed_addrs(int unit, struct wordlist *addrs)
{
    if (addresses[unit] != NULL)
        free_wordlist(addresses[unit]);
    addresses[unit] = addrs;

#if 0
    /*
     * If there's only one authorized address we might as well
     * ask our peer for that one right away
     */
    if (addrs != NULL && addrs->next == NULL) {
        char *p = addrs->word;
        struct ipcp_options *wo = &ipcp_wantoptions[unit];
        u32_t a;
        struct hostent *hp;
        
        if (wo->hisaddr == 0 && *p != '!' && *p != '-'
                && strchr(p, '/') == NULL) {
            hp = gethostbyname(p);
            if (hp != NULL && hp->h_addrtype == AF_INET)
                a = *(u32_t *)hp->h_addr;
            else
                a = inet_addr(p);
            if (a != (u32_t) -1)
                wo->hisaddr = a;
        }
    }
#endif
}
#endif

static int ip_addr_check(u32_t addr, struct wordlist *addrs)
{
    
    /* don't allow loopback or multicast address */
    if (bad_ip_adrs(addr))
        return 0;
    
    if (addrs == NULL)
        return !ppp_settings.auth_required;      /* no addresses authorized */
    
    /* XXX All other addresses allowed. */
    return 1;
}

#if 0 /* PAP_SUPPORT > 0 || CHAP_SUPPORT */
/*
 * free_wordlist - release memory allocated for a wordlist.
 */
static void free_wordlist(struct wordlist *wp)
{
    struct wordlist *next;
    
    while (wp != NULL) {
        next = wp->next;
        free(wp);
        wp = next;
    }
}
#endif

#endif /* PPP_SUPPORT */