static int ipv6cp_reqci()

in net/ip/lwip_base/src/netif/ppp/ipv6cp.c [887:1061]

• 135 lines of code
• 36 McCabe index (conditional complexity)

static int ipv6cp_reqci(fsm *f, u_char *inp, int *len, int reject_if_disagree) {
    ppp_pcb *pcb = f->pcb;
    ipv6cp_options *wo = &pcb->ipv6cp_wantoptions;
    ipv6cp_options *ho = &pcb->ipv6cp_hisoptions;
    ipv6cp_options *ao = &pcb->ipv6cp_allowoptions;
    ipv6cp_options *go = &pcb->ipv6cp_gotoptions;
    u_char *cip, *next;		/* Pointer to current and next CIs */
    u_short cilen, citype;	/* Parsed len, type */
#ifdef IPV6CP_COMP
    u_short cishort;		/* Parsed short value */
#endif /* IPV6CP_COMP */
    eui64_t ifaceid;		/* Parsed interface identifier */
    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 */

    /*
     * 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? */
	    IPV6CPDEBUG(("ipv6cp_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_IFACEID:
	    IPV6CPDEBUG(("ipv6cp: received interface identifier "));

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

	    /*
	     * If he has no interface identifier, or if we both have same 
	     * identifier then NAK it with new idea.
	     * In particular, if we don't know his identifier, but he does,
	     * then accept it.
	     */
	    eui64_get(ifaceid, p);
	    IPV6CPDEBUG(("(%s)", llv6_ntoa(ifaceid)));
	    if (eui64_iszero(ifaceid) && eui64_iszero(go->ourid)) {
		orc = CONFREJ;		/* Reject CI */
		break;
	    }
	    if (!eui64_iszero(wo->hisid) && 
		!eui64_equals(ifaceid, wo->hisid) && 
		eui64_iszero(go->hisid)) {
		    
		orc = CONFNAK;
		ifaceid = wo->hisid;
		go->hisid = ifaceid;
		DECPTR(sizeof(ifaceid), p);
		eui64_put(ifaceid, p);
	    } else
	    if (eui64_iszero(ifaceid) || eui64_equals(ifaceid, go->ourid)) {
		orc = CONFNAK;
		if (eui64_iszero(go->hisid))	/* first time, try option */
		    ifaceid = wo->hisid;
		while (eui64_iszero(ifaceid) || 
		       eui64_equals(ifaceid, go->ourid)) /* bad luck */
		    eui64_magic(ifaceid);
		go->hisid = ifaceid;
		DECPTR(sizeof(ifaceid), p);
		eui64_put(ifaceid, p);
	    }

	    ho->neg_ifaceid = 1;
	    ho->hisid = ifaceid;
	    break;

#ifdef IPV6CP_COMP
	case CI_COMPRESSTYPE:
	    IPV6CPDEBUG(("ipv6cp: received COMPRESSTYPE "));
	    if (!ao->neg_vj ||
		(cilen != CILEN_COMPRESS)) {
		orc = CONFREJ;
		break;
	    }
	    GETSHORT(cishort, p);
	    IPV6CPDEBUG(("(%d)", cishort));

	    if (!(cishort == IPV6CP_COMP)) {
		orc = CONFREJ;
		break;
	    }

	    ho->neg_vj = 1;
	    ho->vj_protocol = cishort;
	    break;
#endif /* IPV6CP_COMP */

	default:
	    orc = CONFREJ;
	    break;
	}

endswitch:
	IPV6CPDEBUG((" (%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)
	    MEMCPY(ucp, cip, cilen);	/* Move it */

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

    /*
     * If we aren't rejecting this packet, and we want to negotiate
     * their identifier and they didn't send their identifier, then we
     * send a NAK with a CI_IFACEID option appended.  We assume the
     * input buffer is long enough that we can append the extra
     * option safely.
     */
    if (rc != CONFREJ && !ho->neg_ifaceid &&
	wo->req_ifaceid && !reject_if_disagree) {
	if (rc == CONFACK) {
	    rc = CONFNAK;
	    ucp = inp;				/* reset pointer */
	    wo->req_ifaceid = 0;		/* don't ask again */
	}
	PUTCHAR(CI_IFACEID, ucp);
	PUTCHAR(CILEN_IFACEID, ucp);
	eui64_put(wo->hisid, ucp);
    }

    *len = ucp - inp;			/* Compute output length */
    IPV6CPDEBUG(("ipv6cp: returning Configure-%s", CODENAME(rc)));
    return (rc);			/* Return final code */
}