/*
    Copyright 2000 (c) by David Schweikert,
    Swiss Federal Institute of Technology,
    Computer Engineering and Networks Laboratory.

    TOPSY -- A Teachable Operating System.
             Implementation of a tiny and simple
             micro kernel for teaching purposes.

    For further information, please visit http://www.tik.ee.ethz.ch/~topsy

    This software is provided under the terms of the GNU General Public 
    Licence. A full copy of the GNU GPL is provided in the file COPYING 
    found in the development root of Topsy.
*/
/*
	
    File:                  $Source: /usr/drwho/vault/cvs/topsy/Topsy/Net/IP/NetIPup.c,v $
    Author(s):             
    Affiliation:           ETH Zuerich, TIK
    Version:               $Revision: 1.1 $
    Creation Date:         
    Last Date of Change:   $Date: 2000/03/31 17:50:37 $      by: $Author: gfa $


    $Log: NetIPup.c,v $
    Revision 1.1  2000/03/31 17:50:37  gfa
    Merged with /Net from several term projects


*/
#include "NetIP.h"
#include "NetIPchecksum.h"

#include <Topsy.h>
#include <Messages.h>
#include <NetDebug.h>
#include <NetBuf.h>
#include <NetAttr.h>
#include <NetConfig.h>
#include <NetIface.h>
#include <NetModules.h>
#include <NetBitFields.h>

static int netipVerify(NetBuf buf);
static int netipForUs(NetBuf buf, NetAttrs attrs);
static void netipSetAttrs(NetBuf buf, NetAttrs attrs);

void netipUp(NetBuf buf, NetAttrs attrs)
{
	NetIPHdr *hdr=(NetIPHdr *) NETBUF_DATA(buf);

	netdbgDisplay(NETDEBUG_IP, "netip : Verifying.\n");

	/* Is the packet ok ? */
	
	if(!netipVerify(buf)) goto discard;

	/* Is the packet for us ? */
	if(!netipForUs(buf,attrs)) {
		netdbgDisplay(NETDEBUG_IP,"netip : Packet not for us.\n");
		goto discard; /* no forwarding at the moment. */
	}

	/* Set remaining attributes not already done */
	netipSetAttrs(buf,attrs);
	
	netdbgDisplay(NETDEBUG_IP, "netip : Verification passed.\n");

 netdbgPrintf(NETDEBUG_GENERIC, "netip: before=%p\n", NETBUF_DATA(buf));
	/* Remove header */
        buf->start += BNIBGET(hdr->bitfield1,1)<<2;
	if(buf->start>buf->end) goto discard;

	netdbgPrintf(NETDEBUG_GENERIC, "netip: after=%p\n", NETBUF_DATA(buf));
	
	/* Send up packet */
	netcfgSendNextUp(NETMODULE_IP, buf, attrs);
	return;
	
discard:
	netdbgDisplay(NETDEBUG_IP, "netip : Discarding upcoming packet.\n");
	netbufFree(buf);
	netbufFree((NetBuf)attrs);
}

static int netipVerify(NetBuf buf)
{
	NetIPHdr *hdr=(NetIPHdr *) NETBUF_DATA(buf);
	int len;
	
	/* check minimal length */
	if(NETBUF_LEN(buf) < sizeof(NetIPHdr)) {
		netdbgDisplay(NETDEBUG_IP, "netip : Packet size smaller than minimal length.\n");
		return 0;
	}

	/* check version */
	/* If version==6, the packet should be sent to the IPv6 module. */
	if(BNIBGET(hdr->bitfield1,0) != 4) {
		netdbgDisplay(NETDEBUG_IP, "netip : IP version not 4.\n");
		return 0;
	}
	
	/* check header length */
	len = BNIBGET(hdr->bitfield1,1) << 2;
	if(NETBUF_LEN(buf) < len) return 0;
	
	/* check checksum */
	if((hdr->checksum = netipChecksum(buf, len))) {
		netdbgDisplay(NETDEBUG_IP, "netip : Wrong checksum. Discarding packet.\n");
		return 0;
	}

	/* check total length */
	len = netbufLen(buf);
	if(len < hdr->tot_len) {
		netdbgPrintf(NETDEBUG_IP,
				"netip : Packet too small (is %d, should be at least %d).\n",
				len, hdr->tot_len);
		return 0;
	}
	if(len > hdr->tot_len) netbufTrim(buf, hdr->tot_len);
	
	return 1;
}

static int netipForUs(NetBuf buf, NetAttrs attrs)
{
	NetIPHdr *hdr=(NetIPHdr *) NETBUF_DATA(buf);
	unsigned short iface,a;	

	if(!netattrGet(attrs,NETATTR_IF_FROM,&iface)) return 0;

	/* Broadcast is not handled yet... */
	
	if(!netifGetAttr(iface,NETATTR_IP_FROM_0,&a)) return 0;
	if(a!=hdr->daddr0) return 0;
	netattrSet(attrs,NETATTR_IP_TO_0,a);

	if(!netifGetAttr(iface,NETATTR_IP_FROM_1,&a)) return 0;
	if(a!=hdr->daddr1) return 0;
	netattrSet(attrs,NETATTR_IP_TO_1,a);

	if(!netifGetAttr(iface,NETATTR_IP_FROM_2,&a)) return 0;
	if(a!=hdr->daddr2) return 0;
	netattrSet(attrs,NETATTR_IP_TO_2,a);

	if(!netifGetAttr(iface,NETATTR_IP_FROM_3,&a)) return 0;
	if(a!=hdr->daddr3) return 0;
	netattrSet(attrs,NETATTR_IP_TO_3,a);

	return 1;
}

static void netipSetAttrs(NetBuf buf, NetAttrs attrs)
{
	NetIPHdr *hdr=(NetIPHdr *) NETBUF_DATA(buf);
	unsigned short tmp;

	/* Source address */
	netattrSet(attrs,NETATTR_IP_FROM_0,(unsigned short) hdr->saddr0);
	netattrSet(attrs,NETATTR_IP_FROM_1,(unsigned short) hdr->saddr1);
	netattrSet(attrs,NETATTR_IP_FROM_2,(unsigned short) hdr->saddr2);
	netattrSet(attrs,NETATTR_IP_FROM_3,(unsigned short) hdr->saddr3);

	/* Protocol */
	tmp = hdr->protocol;
	netattrSet(attrs, NETATTR_IP_PROTOCOL, tmp);
}