www.pudn.com > zlIP-8051-rtl8019as.zip > icmp.c

/* 
 * Copyright (c) 2003 Electric Application Laboratory of NAN KAI University 
 * All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met: 
 * 
 * 1. Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright notice, 
 *    this list of conditions and the following disclaimer in the documentation 
 *    and/or other materials provided with the distribution. 
 * 3. The name of the author may not be used to endorse or promote products 
 *    derived from this software without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
 * OF SUCH DAMAGE. 
 * 
 * Author: Li Zhanglin  
 * 
 */ 
 
#include "..\GloblDef\GloblDef.h" 
#include "..\TCPIP\TCPIPmem.h" 
#include "..\TCPIP\IP.h" 
#include "..\TCPIP\icmp.h" 
 
#if ICMP_EN 
/* MemHead->pStart is point to ICMP head */ 
void ICMPInput(struct SMemHead DT_XDATA *MemHead)	REENTRANT_MUL 
{ 
	IP_ADDR ipaddr; 
	struct SIPHead DT_XDATA *pIPHead; 
 
	/* which type of icmp */ 
	switch(((struct SICMPEchoHead DT_XDATA *)(MemHead->pStart))->type) 
	{ 
	case ICMP_TYPE_QUERY: 
		 
		/* chage type */ 
		((struct SICMPEchoHead DT_XDATA *)(MemHead->pStart))->type = ICMP_TYPE_REPLY; 
 
		/* adjust checksum. refer to lwip: if change type from 8 to 0, 
		for checksum, that is increasing 0x8000 and add flowed hight bit  
		to bit 0.*/ 
		if (((struct SICMPEchoHead DT_XDATA *)(MemHead->pStart))->CheckSum >= htons(0xffff - (((WORD)ICMP_TYPE_QUERY) << 8)))  
			((struct SICMPEchoHead DT_XDATA *)(MemHead->pStart))->CheckSum += htons(((WORD)ICMP_TYPE_QUERY) << 8) + 1; 
		else 
			((struct SICMPEchoHead DT_XDATA *)(MemHead->pStart))->CheckSum += htons(((WORD)ICMP_TYPE_QUERY) << 8); 
 
		/* 
		 *send this packet back, first fill some of IPHead field  
		 */ 
 
		/* dec pStart and get ip head */ 
		pIPHead = (struct SIPHead DT_XDATA *)(MemHead->pStart -= IP_HEAD_MIN_LEN); 
 
		/* exchange ipdest and ipscr */ 
		ipaddr = pIPHead->IPDest; 
		pIPHead->IPDest = pIPHead->IPScr; 
		pIPHead->IPScr  = ipaddr; 
 
		/* ip total length not change */ 
 
		/* protocol */ 
		pIPHead->Protocol = IP_PROTOCOL_ICMP; 
 
		IPOutput(MemHead); 
 
		/* whether send success or not free this packet */ 
		MemFree(MemHead); 
		 
		break; 
	default: 
		MemFree(MemHead); 
	} 
} 
 
#endif