ipcp.c

Unix/Linux NAPT协议解析源码

#ifdef USE_MS_DNS
	/* Handle Microsoft DNS Stuff */
	case CI_MS_DNS1:
	    IPCPDEBUG((LOG_INFO, "ipcp: received DNS Request "));

	    /* If we do not have a DNS address then we cannot send it */
        wo->dnsaddr[0]=dns_addr.s_addr;
        wo->dnsaddr[1]=dns2_addr.s_addr;

	    if (wo->dnsaddr[0] == 0 ||
		cilen != CILEN_ADDR) {	/* Check CI length */
		IPCPDEBUG((LOG_INFO, "DNS failed due to %d, %d, %d", wo->dnsaddr[0], cilen, CILEN_ADDR));
		orc = CONFREJ;		/* Reject CI */
		break;
	    }
	    GETLONG(tl,p);
	    if (htonl(tl) != wo->dnsaddr[0]) {
                DECPTR(sizeof (long),p);
		tl = ntohl(wo->dnsaddr[0]);
		PUTLONG(tl, p);
		orc = CONFNAK;
            }
            break;

	case CI_MS_WINS1:
	    IPCPDEBUG((LOG_INFO, "ipcp: received WINS Request "));

	    /* If we do not have a WINS address then we cannot send it */
	    if (wo->winsaddr[0] == 0 ||
		cilen != CILEN_ADDR) {	/* Check CI length */
		orc = CONFREJ;		/* Reject CI */
		break;
	    }
	    GETLONG(tl,p);
	    if (htonl(tl) != wo->winsaddr[0]) {
                DECPTR(sizeof (long),p);
		tl = ntohl(wo->winsaddr[0]);
		PUTLONG(tl, p);
		orc = CONFNAK;
            }
            break;

	case CI_MS_DNS2:
	    IPCPDEBUG((LOG_INFO, "ipcp: received DNS Request "));

	    /* If we do not have a DNS address then we cannot send it */
	    if (wo->dnsaddr[0] == 0 ||  /* Yes, this is the first one! */
		cilen != CILEN_ADDR) {	/* Check CI length */
		orc = CONFREJ;		/* Reject CI */
		break;
	    }
	    GETLONG(tl,p);
	    if (htonl(tl) != wo->dnsaddr[1]) { /* and this is the 2nd one */
                DECPTR(sizeof (long),p);
		tl = ntohl(wo->dnsaddr[1]);
		PUTLONG(tl, p);
		orc = CONFNAK;
            }
            break;

	case CI_MS_WINS2:
	    IPCPDEBUG((LOG_INFO, "ipcp: received WINS Request "));

	    /* If we do not have a WINS address then we cannot send it */
	    if (wo->winsaddr[0] == 0 ||  /* Yes, this is the first one! */
		cilen != CILEN_ADDR) {	/* Check CI length */
		orc = CONFREJ;		/* Reject CI */
		break;
	    }
	    GETLONG(tl,p);
	    if (htonl(tl) != wo->winsaddr[1]) { /* and this is the 2nd one */
                DECPTR(sizeof (long),p);
		tl = ntohl(wo->winsaddr[1]);
		PUTLONG(tl, p);
		orc = CONFNAK;
            }
            break;
#endif

	case CI_COMPRESSTYPE:
	    IPCPDEBUG((LOG_INFO, "ipcp: received COMPRESSTYPE "));
	    if (!ao->neg_vj ||
		(cilen != CILEN_VJ && cilen != CILEN_COMPRESS)) {
		orc = CONFREJ;
		break;
	    }
	    GETSHORT(cishort, p);
	    IPCPDEBUG((LOG_INFO, "(%d)", cishort));

	    if (!(cishort == IPCP_VJ_COMP ||
		  (cishort == IPCP_VJ_COMP_OLD && cilen == CILEN_COMPRESS))) {
		orc = CONFREJ;
		break;
	    }

	    ho->neg_vj = 1;
	    ho->vj_protocol = cishort;
	    if (cilen == CILEN_VJ) {
		GETCHAR(maxslotindex, p);
		if (maxslotindex > ao->maxslotindex) { 
		    orc = CONFNAK;
		    if (!reject_if_disagree){
			DECPTR(1, p);
			PUTCHAR(ao->maxslotindex, p);
		    }
		}
		GETCHAR(cflag, p);
		if (cflag && !ao->cflag) {
		    orc = CONFNAK;
		    if (!reject_if_disagree){
			DECPTR(1, p);
			PUTCHAR(wo->cflag, p);
		    }
		}
		ho->maxslotindex = maxslotindex;
		ho->cflag = cflag;
	    } else {
		ho->old_vj = 1;
		ho->maxslotindex = MAX_STATES - 1;
		ho->cflag = 1;
	    }
	    break;

	default:
	    orc = CONFREJ;
	    break;
	}

endswitch:
	IPCPDEBUG((LOG_INFO, " (%s)\n", CODENAME(orc)));

	if (orc == CONFACK &&		/* Good CI */
	    rc != CONFACK)		/*  but prior CI wasn't? */
	    continue;			/* Don't send this one */

	if (orc == CONFNAK) {		/* Nak this CI? */
	    if (reject_if_disagree)	/* Getting fed up with sending NAKs? */
		orc = CONFREJ;		/* Get tough if so */
	    else {
		if (rc == CONFREJ)	/* Rejecting prior CI? */
		    continue;		/* Don't send this one */
		if (rc == CONFACK) {	/* Ack'd all prior CIs? */
		    rc = CONFNAK;	/* Not anymore... */
		    ucp = inp;		/* Backup */
		}
	    }
	}

	if (orc == CONFREJ &&		/* Reject this CI */
	    rc != CONFREJ) {		/*  but no prior ones? */
	    rc = CONFREJ;
	    ucp = inp;			/* Backup */
	}

	/* Need to move CI? */
	if (ucp != cip)
	    BCOPY(cip, ucp, cilen);	/* Move it */

	/* Update output pointer */
	INCPTR(cilen, ucp);
    }

    /*
     * If we aren't rejecting this packet, and we want to negotiate
     * their address, and they didn't send their address, then we
     * send a NAK with a CI_ADDR option appended.  We assume the
     * input buffer is long enough that we can append the extra
     * option safely.
     */
    if (rc != CONFREJ && !ho->neg_addr &&
	wo->req_addr && !reject_if_disagree) {
	if (rc == CONFACK) {
	    rc = CONFNAK;
	    ucp = inp;			/* reset pointer */
	    wo->req_addr = 0;		/* don't ask again */
	}
	PUTCHAR(CI_ADDR, ucp);
	PUTCHAR(CILEN_ADDR, ucp);
	tl = ntohl(wo->hisaddr);
	PUTLONG(tl, ucp);
    }

    *len = ucp - inp;			/* Compute output length */
    IPCPDEBUG((LOG_INFO, "ipcp: returning Configure-%s", CODENAME(rc)));
    return (rc);			/* Return final code */
}


/*
 * ipcp_up - IPCP has come UP.
 *
 * Configure the IP network interface appropriately and bring it up.
 */
static void
ipcp_up(f)
    fsm *f;
{
    u_int32_t mask;
    ipcp_options *ho = &ipcp_hisoptions[f->unit];
    ipcp_options *go = &ipcp_gotoptions[f->unit];

    IPCPDEBUG((LOG_INFO, "ipcp: up"));
    go->default_route = 0;
    go->proxy_arp = 0;

    /*
     * We must have a non-zero IP address for both ends of the link.
     */
    if (!ho->neg_addr)
	ho->hisaddr = ipcp_wantoptions[f->unit].hisaddr;

    if (ho->hisaddr == 0) {
	do_syslog(LOG_ERR, "Could not determine remote IP address");
	ipcp_close(f->unit);
	return;
    }
    if (go->ouraddr == 0) {
	do_syslog(LOG_ERR, "Could not determine local IP address");
	ipcp_close(f->unit);
	return;
    }

    /*
     * Check that the peer is allowed to use the IP address it wants.
     */
    if (!auth_ip_addr(f->unit, ho->hisaddr)) {
	do_syslog(LOG_ERR, "Peer is not authorized to use remote address %s",
	       ip_ntoa(ho->hisaddr));
	ipcp_close(f->unit);
	return;
    }

    do_syslog(LOG_NOTICE, "local  IP address %s", ip_ntoa(go->ouraddr));
    do_syslog(LOG_NOTICE, "remote IP address %s", ip_ntoa(ho->hisaddr));

    /*
     * Set IP addresses and (if specified) netmask.
     */
    mask = GetMask(go->ouraddr);
    if (!sifaddr(f->unit, go->ouraddr, ho->hisaddr, mask)) {
	IPCPDEBUG((LOG_WARNING, "sifaddr failed"));
	ipcp_close(f->unit);
	return;
    }

    /* set tcp compression */
    sifvjcomp(f->unit, ho->neg_vj, ho->cflag, ho->maxslotindex);

    /* bring the interface up for IP */
    if (!sifup(f->unit)) {
	IPCPDEBUG((LOG_WARNING, "sifup failed"));
	ipcp_close(f->unit);
	return;
    }

    /* assign a default route through the interface if required */
    if (ipcp_wantoptions[f->unit].default_route) 
	if (sifdefaultroute(f->unit, ho->hisaddr))
	    go->default_route = 1;

    /* Make a proxy ARP entry if requested. */
    if (ipcp_wantoptions[f->unit].proxy_arp)
	if (sifproxyarp(f->unit, ho->hisaddr))
	    go->proxy_arp = 1;

    /*
     * Execute the ip-up script, like this:
     *	/etc/ppp/ip-up interface tty speed local-IP remote-IP
     */
    ipcp_script(f, _PATH_IPUP);

}


/*
 * ipcp_down - IPCP has gone DOWN.
 *
 * Take the IP network interface down, clear its addresses
 * and delete routes through it.
 */
static void
ipcp_down(f)
    fsm *f;
{
    u_int32_t ouraddr, hisaddr;

    IPCPDEBUG((LOG_INFO, "ipcp: down"));

    ouraddr = ipcp_gotoptions[f->unit].ouraddr;
    hisaddr = ipcp_hisoptions[f->unit].hisaddr;
    if (ipcp_gotoptions[f->unit].proxy_arp)
	cifproxyarp(f->unit, hisaddr);
    if (ipcp_gotoptions[f->unit].default_route) 
	cifdefaultroute(f->unit, hisaddr);
    sifdown(f->unit);
    cifaddr(f->unit, ouraddr, hisaddr);

    /* Execute the ip-down script */
    ipcp_script(f, _PATH_IPDOWN);
}


/*
 * ipcp_script - Execute a script with arguments
 * interface-name tty-name speed local-IP remote-IP.
 */
static void
ipcp_script(f, script)
    fsm *f;
    char *script;
{
    char strspeed[32], strlocal[32], strremote[32];
    char *argv[8];

    snprintf(strspeed, sizeof(strspeed), "%d", baud_rate);
    strncpy2(strlocal, ip_ntoa(ipcp_gotoptions[f->unit].ouraddr), sizeof(strlocal));
    strncpy2(strremote, ip_ntoa(ipcp_hisoptions[f->unit].hisaddr), sizeof(strremote));

    argv[0] = script;
    argv[1] = ifname;
    argv[2] = devnam;
    argv[3] = strspeed;
    argv[4] = strlocal;
    argv[5] = strremote;
    argv[6] = ipparam;
    argv[7] = NULL;
    run_program(script, argv, 0);
}

/*
 * ipcp_printpkt - print the contents of an IPCP packet.
 */
char *ipcp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",
    "TermReq", "TermAck", "CodeRej"
};

int
ipcp_printpkt(p, plen, printer, arg)
    u_char *p;
    int plen;
    void (*printer)();
    void *arg;
{
    int code, id, len, olen;
    u_char *pstart, *optend;
    u_short cishort;
    u_int32_t cilong;

    if (plen < HEADERLEN)
	return 0;
    pstart = p;
    GETCHAR(code, p);
    GETCHAR(id, p);
    GETSHORT(len, p);
    if (len < HEADERLEN || len > plen)
	return 0;

    if (code >= 1 && code <= sizeof(ipcp_codenames) / sizeof(char *))
	printer(arg, " %s", ipcp_codenames[code-1]);
    else
	printer(arg, " code=0x%x", code);
    printer(arg, " id=0x%x", id);
    len -= HEADERLEN;
    switch (code) {
    case CONFREQ:
    case CONFACK:
    case CONFNAK:
    case CONFREJ:
	/* print option list */
	while (len >= 2) {
	    GETCHAR(code, p);
	    GETCHAR(olen, p);
	    p -= 2;
	    if (olen < 2 || olen > len) {
		break;
	    }
	    printer(arg, " <");
	    len -= olen;
	    optend = p + olen;
	    switch (code) {
	    case CI_ADDRS:
		if (olen == CILEN_ADDRS) {
		    p += 2;
		    GETLONG(cilong, p);
		    printer(arg, "addrs %s", ip_ntoa(htonl(cilong)));
		    GETLONG(cilong, p);
		    printer(arg, " %s", ip_ntoa(htonl(cilong)));
		}
		break;
	    case CI_COMPRESSTYPE:
		if (olen >= CILEN_COMPRESS) {
		    p += 2;
		    GETSHORT(cishort, p);
		    printer(arg, "compress ");
		    switch (cishort) {
		    case IPCP_VJ_COMP:
			printer(arg, "VJ");
			break;
		    case IPCP_VJ_COMP_OLD:
			printer(arg, "old-VJ");
			break;
		    default:
			printer(arg, "0x%x", cishort);
		    }
		}
		break;
	    case CI_ADDR:
		if (olen == CILEN_ADDR) {
		    p += 2;
		    GETLONG(cilong, p);
		    printer(arg, "addr %s", ip_ntoa(htonl(cilong)));
		}
		break;
	    }
	    while (p < optend) {
		GETCHAR(code, p);
		printer(arg, " %.2x", code);
	    }
	    printer(arg, ">");
	}
	break;
    }

    /* print the rest of the bytes in the packet */
    for (; len > 0; --len) {
	GETCHAR(code, p);
	printer(arg, " %.2x", code);
    }

    return p - pstart;
}