// DSWifi Project - sgIP Internet Protocol Stack Implementation
// Copyright (C) 2005-2006 Stephen Stair - sgstair@akkit.org - http://www.akkit.org
/******************************************************************************
DSWifi Lib and test materials are licenced under the MIT open source licence:
Copyright (c) 2005-2006 Stephen Stair

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/

#include "sgIP_IP.h"
#include "sgIP_TCP.h"
#include "sgIP_UDP.h"
#include "sgIP_ICMP.h"
#include "sgIP_Hub.h"

int idnum_count;

int sgIP_IP_ReceivePacket(sgIP_memblock * mb) {
	sgIP_Header_IP * iphdr;
	unsigned short * chksum_calc;
	int chksum_temp;
	int hdrlen;

	iphdr=(sgIP_Header_IP *)mb->datastart;
	chksum_calc=(unsigned short *)mb->datastart;
	// check that header is valid:
	hdrlen=iphdr->version_ihl&15;
	// check length...
	if(mb->totallength<htons(iphdr->tot_length)) {
		SGIP_DEBUG_MESSAGE(("IP: bad length!"));
		SGIP_DEBUG_MESSAGE(("-%i/%i",mb->totallength,htons(iphdr->tot_length)));
		sgIP_memblock_free(mb);
		return 0; // bad size.
	}
	sgIP_memblock_trimsize(mb,htons(iphdr->tot_length));
	// check version
	if((iphdr->version_ihl>>4)!=4) {
		SGIP_DEBUG_MESSAGE(("IP: bad version!"));
		sgIP_memblock_free(mb);
		return 0; // bad version.
	}

	// check checksum
	chksum_temp=sgIP_memblock_IPChecksum(mb,0,hdrlen*4);
	if(chksum_temp!=0xFFFF) { // bad chksum! kill packet.
		SGIP_DEBUG_MESSAGE(("IP: bad checksum!"));
		sgIP_memblock_free(mb);
		return 0; // bad checksum.
	}
	if(htons(iphdr->fragment_offset)&0x3FFF) { // fragmented! oh noes! We can't deal with this!
		SGIP_DEBUG_MESSAGE(("IP: fragmented!"));
		sgIP_memblock_free(mb);
		return 0; // fragmented.
	}

	sgIP_memblock_exposeheader(mb,-hdrlen*4);
	switch(iphdr->protocol) {
	case PROTOCOL_IP_ICMP: // ICMP
      sgIP_ICMP_ReceivePacket(mb,iphdr->src_address,iphdr->dest_address);
		break;
	case PROTOCOL_IP_TCP: // TCP
		sgIP_TCP_ReceivePacket(mb,iphdr->src_address,iphdr->dest_address);
		break;
	case PROTOCOL_IP_UDP: // UDP
		sgIP_UDP_ReceivePacket(mb,iphdr->src_address,iphdr->dest_address);
		break;
	default:
		sgIP_memblock_free(mb);
	}

	return 0;
}
int sgIP_IP_MaxContentsSize(unsigned long destip) {
	return sgIP_Hub_IPMaxMessageSize(destip)-sgIP_IP_RequiredHeaderSize();
}
int sgIP_IP_RequiredHeaderSize() {
	return 5*4; // we'll not include zeroed options.
}
int sgIP_IP_SendViaIP(sgIP_memblock * mb, int protocol, unsigned long srcip, unsigned long destip) {
	sgIP_Header_IP * iphdr;
	unsigned short * chksum_calc;
	int chksum_temp,i;
	sgIP_memblock_exposeheader(mb,20);
	iphdr=(sgIP_Header_IP *)mb->datastart;
	chksum_calc=(unsigned short *)mb->datastart;
	iphdr->dest_address=destip;
	iphdr->fragment_offset=0;
	iphdr->header_checksum=0;
	iphdr->identification=idnum_count++;
	iphdr->protocol=protocol;
	iphdr->src_address=srcip;
	iphdr->tot_length=htons(mb->totallength);
	iphdr->TTL=SGIP_IP_TTL;
	iphdr->type_of_service=0;
	iphdr->version_ihl=0x45;
	chksum_temp=0;
	for(i=0;i<10;i++) chksum_temp+=chksum_calc[i];
	chksum_temp += chksum_temp>>16;
	chksum_temp &= 0xFFFF;
	chksum_temp = ~chksum_temp;
	if(chksum_temp==0) chksum_temp=0xFFFF;
	iphdr->header_checksum=chksum_temp;
	return sgIP_Hub_SendProtocolPacket(htons(0x0800),mb,destip,srcip);
}
unsigned long sgIP_IP_GetLocalBindAddr(unsigned long srcip, unsigned long destip) {
	if(srcip) return srcip;
	return sgIP_Hub_GetCompatibleIP(destip);
}