ipcp.c

PPPoE协议在Psos中的实现源代码

	    break;
	}
	p = next;
    }

    /* If there is still anything left, this packet is bad. */
    if (len != 0)
	goto bad;

    /*
     * OK, the Nak is good.  Now we can update state.
     */
    if (f->state != OPENED)
	*go = try;

    return 1;

bad:
    IPCPDEBUG((LOG_INFO, "ipcp_nakci: received bad Nak!"));
    return 0;
}


/*
 * ipcp_rejci - Reject some of our CIs.
 */
static int
ipcp_rejci(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    u_char cimaxslotindex, ciflag, cilen;
    u_short cishort;
    u_int32_t cilong;
    ipcp_options try;		/* options to request next time */

    try = *go;
    /*
     * Any Rejected CIs must be in exactly the same order that we sent.
     * Check packet length and CI length at each step.
     * If we find any deviations, then this packet is bad.
     */
#define REJCIADDR(opt, neg, old, val1, val2) \
    if (go->neg && \
	len >= (cilen = old? CILEN_ADDRS: CILEN_ADDR) && \
	p[1] == cilen && \
	p[0] == opt) { \
	u_int32_t l; \
	len -= cilen; \
	INCPTR(2, p); \
	GETLONG(l, p); \
	cilong = htonl(l); \
	/* Check rejected value. */ \
	if (cilong != val1) \
	    goto bad; \
	if (old) { \
	    GETLONG(l, p); \
	    cilong = htonl(l); \
	    /* Check rejected value. */ \
	    if (cilong != val2) \
		goto bad; \
	} \
	try.neg = 0; \
    }

#define REJCIVJ(opt, neg, val, old, maxslot, cflag) \
    if (go->neg && \
	p[1] == (old? CILEN_COMPRESS : CILEN_VJ) && \
	len >= p[1] && \
	p[0] == opt) { \
	len -= p[1]; \
	INCPTR(2, p); \
	GETSHORT(cishort, p); \
	/* Check rejected value. */  \
	if (cishort != val) \
	    goto bad; \
	if (!old) { \
	   GETCHAR(cimaxslotindex, p); \
	   if (cimaxslotindex != maxslot) \
	     goto bad; \
	   GETCHAR(ciflag, p); \
	   if (ciflag != cflag) \
	     goto bad; \
        } \
	try.neg = 0; \
     }

    REJCIADDR((go->old_addrs? CI_ADDRS: CI_ADDR), neg_addr,
	      go->old_addrs, go->ouraddr, go->hisaddr);

    REJCIVJ(CI_COMPRESSTYPE, neg_vj, go->vj_protocol, go->old_vj,
	    go->maxslotindex, go->cflag);

    /*
     * If there are any remaining CIs, then this packet is bad.
     */
    if (len != 0)
	goto bad;
    /*
     * Now we can update state.
     */
    if (f->state != OPENED)
	*go = try;
    return 1;

bad:
    IPCPDEBUG((LOG_INFO, "ipcp_rejci: received bad Reject!"));
    return 0;
}


/*
 * ipcp_reqci - Check the peer's requested CIs and send appropriate response.
 *
 * Returns: CONFACK, CONFNAK or CONFREJ and input packet modified
 * appropriately.  If reject_if_disagree is non-zero, doesn't return
 * CONFNAK; returns CONFREJ if it can't return CONFACK.
 */
static int
ipcp_reqci(f, inp, len, reject_if_disagree)
    fsm *f;
    u_char *inp;		/* Requested CIs */
    int *len;			/* Length of requested CIs */
    int reject_if_disagree;
{
    ipcp_options *wo = &ipcp_wantoptions[f->unit];
    ipcp_options *ho = &ipcp_hisoptions[f->unit];
    ipcp_options *ao = &ipcp_allowoptions[f->unit];
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    u_char *cip, *next;		/* Pointer to current and next CIs */
    u_short cilen, citype;	/* Parsed len, type */
    u_short cishort;		/* Parsed short value */
    u_int32_t tl, ciaddr1, ciaddr2;/* Parsed address values */
    int rc = CONFACK;		/* Final packet return code */
    int orc;			/* Individual option return code */
    u_char *p;			/* Pointer to next char to parse */
    u_char *ucp = inp;		/* Pointer to current output char */
    int l = *len;		/* Length left */
    u_char maxslotindex, cflag;

    /*
     * Reset all his options.
     */
    bzero(ho, sizeof(*ho));
    
    /*
     * Process all his options.
     */
    next = inp;
    while (l) {
	orc = CONFACK;			/* Assume success */
	cip = p = next;			/* Remember begining of CI */
	if (l < 2 ||			/* Not enough data for CI header or */
	    p[1] < 2 ||			/*  CI length too small or */
	    p[1] > l) {			/*  CI length too big? */
	    IPCPDEBUG((LOG_INFO, "ipcp_reqci: bad CI length!"));
	    orc = CONFREJ;		/* Reject bad CI */
	    cilen = l;			/* Reject till end of packet */
	    l = 0;			/* Don't loop again */
	    goto endswitch;
	}
	GETCHAR(citype, p);		/* Parse CI type */
	GETCHAR(cilen, p);		/* Parse CI length */
	l -= cilen;			/* Adjust remaining length */
	next += cilen;			/* Step to next CI */

	switch (citype) {		/* Check CI type */
	case CI_ADDRS:
	    IPCPDEBUG((LOG_INFO, "ipcp: received ADDRS "));
	    if (!ao->neg_addr ||
		cilen != CILEN_ADDRS) {	/* Check CI length */
		orc = CONFREJ;		/* Reject CI */
		break;
	    }

	    /*
	     * If he has no address, or if we both have his address but
	     * disagree about it, then NAK it with our idea.
	     * In particular, if we don't know his address, but he does,
	     * then accept it.
	     */
	    GETLONG(tl, p);		/* Parse source address (his) */
	    ciaddr1 = htonl(tl);
	    IPCPDEBUG((LOG_INFO, "(%s:", ip_ntoa(ciaddr1)));
	    if (ciaddr1 != wo->hisaddr
		&& (ciaddr1 == 0 || !wo->accept_remote)) {
		orc = CONFNAK;
		if (!reject_if_disagree) {
		    DECPTR(sizeof(u_int32_t), p);
		    tl = ntohl(wo->hisaddr);
		    PUTLONG(tl, p);
		}
	    } else if (ciaddr1 == 0 && wo->hisaddr == 0) {
		/*
		 * If neither we nor he knows his address, reject the option.
		 */
		orc = CONFREJ;
		wo->req_addr = 0;	/* don't NAK with 0.0.0.0 later */
		break;
	    }

	    /*
	     * If he doesn't know our address, or if we both have our address
	     * but disagree about it, then NAK it with our idea.
	     */
	    GETLONG(tl, p);		/* Parse desination address (ours) */
	    ciaddr2 = htonl(tl);
	    IPCPDEBUG((LOG_INFO, "%s)", ip_ntoa(ciaddr2)));
	    if (ciaddr2 != wo->ouraddr) {
		if (ciaddr2 == 0 || !wo->accept_local) {
		    orc = CONFNAK;
		    if (!reject_if_disagree) {
			DECPTR(sizeof(u_int32_t), p);
			tl = ntohl(wo->ouraddr);
			PUTLONG(tl, p);
		    }
		} else {
		    go->ouraddr = ciaddr2;	/* accept peer's idea */
		}
	    }

	    ho->neg_addr = 1;
	    ho->old_addrs = 1;
	    ho->hisaddr = ciaddr1;
	    ho->ouraddr = ciaddr2;
	    break;

	case CI_ADDR:
	    IPCPDEBUG((LOG_INFO, "ipcp: received ADDR "));

	    if (!ao->neg_addr ||
		cilen != CILEN_ADDR) {	/* Check CI length */
		orc = CONFREJ;		/* Reject CI */
		break;
	    }

	    /*
	     * If he has no address, or if we both have his address but
	     * disagree about it, then NAK it with our idea.
	     * In particular, if we don't know his address, but he does,
	     * then accept it.
	     */
	    GETLONG(tl, p);	/* Parse source address (his) */
	    ciaddr1 = htonl(tl);
	    IPCPDEBUG((LOG_INFO, "(%s)", ip_ntoa(ciaddr1)));
	    if (ciaddr1 != wo->hisaddr
		&& (ciaddr1 == 0 || !wo->accept_remote)) {
		orc = CONFNAK;
		if (!reject_if_disagree) {
		    DECPTR(sizeof(u_int32_t), p);
		    tl = ntohl(wo->hisaddr);
		    PUTLONG(tl, p);
		}
	    } else if (ciaddr1 == 0 && wo->hisaddr == 0) {
		/*
		 * Don't ACK an address of 0.0.0.0 - reject it instead.
		 */
		orc = CONFREJ;
		wo->req_addr = 0;	/* don't NAK with 0.0.0.0 later */
		break;
	    }
	
	    ho->neg_addr = 1;
	    ho->hisaddr = ciaddr1;
	    break;
	
	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 wasnt? */
	    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, (size_t) 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) {
	syslog(LOG_ERR, "Could not determine remote IP address");
	ipcp_close(f->unit);
	return;
    }
    if (go->ouraddr == 0) {
	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)) {
	syslog(LOG_ERR, "Peer is not authorized to use remote address %s",
	       ip_ntoa(ho->hisaddr));
	ipcp_close(f->unit);
	return;
    }

    syslog(LOG_NOTICE, "local  IP address %s", ip_ntoa(go->ouraddr));
    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;

}


/*
 * 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);

}


/*
 * 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) __P((void *, char *, ...));
    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((u_int32_t)htonl(cilong)));
		    GETLONG(cilong, p);
		    printer(arg, " %s", ip_ntoa((u_int32_t)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((u_int32_t)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);
    }

    printer(arg, "\n");
    return p - pstart;
}