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/opentcp/icmp.c

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/*
 *Copyright (c) 2000-2002 Viola Systems Ltd.
 *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 end-user documentation included with the redistribution, if 
 *any, must include the following acknowledgment:
 *      "This product includes software developed by Viola 
 *      Systems (http://www.violasystems.com/)."
 *
 *Alternately, this acknowledgment may appear in the software itself, 
 *if and wherever such third-party acknowledgments normally appear.
 *
 *4. The names "OpenTCP" and "Viola Systems" must not be used to 
 *endorse or promote products derived from this software without prior 
 *written permission. For written permission, please contact 
 *opentcp@opentcp.org.
 *
 *5. Products derived from this software may not be called "OpenTCP", 
 *nor may "OpenTCP" appear in their name, without prior written 
 *permission of the Viola Systems Ltd.
 *
 *THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED 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 VIOLA SYSTEMS LTD. OR ITS CONTRIBUTORS 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.
 *====================================================================
 *
 *OpenTCP is the unified open source TCP/IP stack available on a series 
 *of 8/16-bit microcontrollers, please see <http://www.opentcp.org>.
 *
 *For more information on how to network-enable your devices, or how to 
 *obtain commercial technical support for OpenTCP, please see 
 *<http://www.violasystems.com/>.
 */

#include <inet/debug.h>
#include <inet/datatypes.h>
#include <inet/ethernet.h>
#include <inet/ip.h>
#include <inet/tcp_ip.h>
#include <inet/system.h>

INT16 process_icmp_in (struct ip_frame* frame, UINT16 len) 
{
        UINT8 type;
        UINT8 code;
        UINT16 checksum;
        UINT16 i;
        
        
        /* Is this ICMP?        */
        
        ICMP_DEBUGOUT("Processing ICMP...\n\r");
        
        if( frame->protocol != IP_ICMP ) {
                ICMP_DEBUGOUT("ERROR: The protocol is not ICMP\n\r");
                return(-1);
        }
        
        /* Calculate checksum for received packet       */

        checksum = 0;
        i = 0;
        
        NETWORK_RECEIVE_INITIALIZE(frame->buf_index);
        
        for(i=0; i < len; i++)
                checksum = ip_checksum(checksum, RECEIVE_NETWORK_B(), (UINT8)i);
        
        checksum = ~ checksum;
        
        if(checksum != IP_GOOD_CS) {
                ICMP_DEBUGOUT("ERROR: ICMP Checksum failed!\n\r");
                return (-1);
        }
        
        ICMP_DEBUGOUT("ICMP Checksum OK\n\r");
        
        /* Start processing the message */
        
        NETWORK_RECEIVE_INITIALIZE(frame->buf_index);
        
        type = RECEIVE_NETWORK_B();
        code = RECEIVE_NETWORK_B();
        
        /* We have already checked the CS, skip it      */
        
        RECEIVE_NETWORK_B();
        RECEIVE_NETWORK_B();

        switch(type) {
                case ICMP_ECHO_REQUEST:
                
                        if(code != 0) {
                                ICMP_DEBUGOUT("ERROR:Misformed ICMP ECHO Request\n\r");
                                return(-1);
                        }
                        
                        ICMP_DEBUGOUT("ICMP ECHO Request received\n\r");
                        
                        /* Is it a packet for setting temporary IP?     */
                        
                        if(len == (ICMP_ECHOREQ_HLEN + ICMP_TEMPIPSET_DATALEN) )
                        {
                                /* Yep, set temporary IP address        */
                                
                                ICMP_DEBUGOUT("PING with 102 bytes of data, getting temp. IP\r\n");                     
                                localmachine.localip = frame->dip;
                                
                        }
                        
                        
                        /* Same IP?             */
                        
                        if(localmachine.localip != frame->dip)
                                return(-1);

                        /* Reply it     */
                        
                        TXBUF[0] = ICMP_ECHO_REPLY;
                        TXBUF[1] = 0;
                        TXBUF[2] = 0;
                        TXBUF[3] = 0;
                        
                        /* Copy with truncate if needed */
                        
                        if(len > NETWORK_TX_BUFFER_SIZE)
                                len = NETWORK_TX_BUFFER_SIZE;

                        /* Calculate Checksum for packet to be sent     AND copy it to buffer*/
                        
                        checksum = ((UINT16)ICMP_ECHO_REPLY)<<8;
                        
                        for(i=4; i<len; i++){
                                checksum = ip_checksum(checksum, TXBUF[i] = RECEIVE_NETWORK_B(), (UINT8)i);
                                }
        
                        checksum = ~ checksum;
                        
                        /* Put the checksum on place    */
                        
                        TXBUF[2] = (UINT8)(checksum>>8);
                        TXBUF[3] = (UINT8)checksum;
                        
                        /* Send it                                              */
                        
                        process_ip_out(frame->sip, IP_ICMP, 0, 100, &TXBUF[0], len);
                        
                        ICMP_DEBUGOUT("ICMP Reply sent\n\r");
                        
                        return(0);
                        
                
                break;
                
                case ICMP_ECHO_REPLY:
                
                break;
        
                default:                                /* Unregognized ICMP message    */
                        
                        ICMP_DEBUGOUT("Unregognized ICMP message\n\r");
                        return(-1); 
        }
        
}

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