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/*********************************************************************
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*
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* PIC IP Module for Microchip TCP/IP Stack
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*
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*********************************************************************
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* FileName: IP.C
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* Dependencies: string.h
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* StackTsk.h
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* Helpers.h
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* IP.h
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* Processor: PIC18
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* Complier: MCC18 v1.00.50 or higher
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* HITECH PICC-18 V8.10PL1 or higher
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* Company: Microchip Technology, Inc.
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*
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* Software License Agreement
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*
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* The software supplied herewith by Microchip Technology Incorporated
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* (the “Company”) for its PICmicro® Microcontroller is intended and
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* supplied to you, the Company’s customer, for use solely and
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* exclusively on Microchip PICmicro Microcontroller products. The
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* software is owned by the Company and/or its supplier, and is
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* protected under applicable copyright laws. All rights are reserved.
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* Any use in violation of the foregoing restrictions may subject the
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* user to criminal sanctions under applicable laws, as well as to
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* civil liability for the breach of the terms and conditions of this
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* license.
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*
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* THIS SOFTWARE IS PROVIDED IN AN “AS IS” CONDITION. NO WARRANTIES,
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* WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED
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* TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT,
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* IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR
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* CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
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*
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* HiTech PICC18 Compiler Options excluding device selection:
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* -FAKELOCAL -G -O -Zg -E -C
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*
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*
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*
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*
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* Author Date Comment
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*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* Nilesh Rajbharti 4/27/01 Original (Rev 1.0)
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* Nilesh Rajbharti 2/9/02 Cleanup
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* Nilesh Rajbharti 5/22/02 Rev 2.0 (See version.log for detail)
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********************************************************************/
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#include <string.h>
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#include "stacktsk.h"
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#include "helpers.h"
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#include "mac.h"
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#include "ip.h"
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// This is left shifted by 4. Actual value is 0x04.
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#define IPv4 (0x40)
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#define IP_VERSION IPv4
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/*
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* IHL (Internet Header Length) is # of DWORDs in a header.
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* Since, we do not support options, our IP header length will be
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* minimum i.e. 20 bytes : IHL = 20 / 4 = 5.
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*/
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#define IP_IHL (0x05)
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#define IP_SERVICE_NW_CTRL (0x07)
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#define IP_SERVICE_IN_CTRL (0x06)
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#define IP_SERVICE_ECP (0x05)
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#define IP_SERVICE_OVR (0x04)
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#define IP_SERVICE_FLASH (0x03)
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#define IP_SERVICE_IMM (0x02)
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#define IP_SERVICE_PRIOR (0x01)
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#define IP_SERVICE_ROUTINE (0x00)
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#define IP_SERVICE_N_DELAY (0x00)
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#define IP_SERCICE_L_DELAY (0x08)
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#define IP_SERVICE_N_THRPT (0x00)
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#define IP_SERVICE_H_THRPT (0x10)
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#define IP_SERVICE_N_RELIB (0x00)
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#define IP_SERVICE_H_RELIB (0x20)
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#define IP_SERVICE (IP_SERVICE_ROUTINE | IP_SERVICE_N_DELAY)
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#define MY_IP_TTL (100) /* Time-To-Live in Seconds */
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static WORD _Identifier = 0;
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static void SwapIPHeader(IP_HEADER* h);
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/*********************************************************************
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* Function: BOOL IPGetHeader( IP_ADDR *localIP,
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* NODE_INFO *remote,
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* BYTE *Protocol,
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* WORD *len)
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*
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* PreCondition: MACGetHeader() == TRUE
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*
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* Input: localIP - Local node IP Address as received
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* in current IP header.
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* If this information is not required
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* caller may pass NULL value.
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* remote - Remote node info
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* Protocol - Current packet protocol
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* len - Current packet data length
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*
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* Output: TRUE, if valid packet was received
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* FALSE otherwise
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*
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* Side Effects: None
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*
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* Note: Only one IP message can be received.
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* Caller may not transmit and receive a message
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* at the same time.
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*
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********************************************************************/
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BOOL IPGetHeader(IP_ADDR *localIP,
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NODE_INFO *remote,
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BYTE *protocol,
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WORD *len)
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{
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WORD_VAL ReceivedChecksum;
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WORD_VAL CalcChecksum;
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WORD checksums[2];
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IP_HEADER header;
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BYTE optionsLen;
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#define MAX_OPTIONS_LEN (20) // As per RFC 791.
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BYTE options[MAX_OPTIONS_LEN];
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// Read IP header.
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MACGetArray((BYTE*)&header, sizeof(header));
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// Make sure that this IPv4 packet.
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if ( (header.VersionIHL & 0xf0) != IP_VERSION )
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{
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goto IPGetHeader_Discard;
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}
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/*
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* Calculate options length in this header, if there is any.
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* IHL is in terms of numbers of 32-bit DWORDs; i.e. actual
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* length is 4 times IHL.
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*/
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optionsLen = ((header.VersionIHL & 0x0f) << 2) - sizeof(header);
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/*
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* If there is any option(s), read it so that we can include them
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* in checksum calculation.
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*/
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if ( optionsLen > MAX_OPTIONS_LEN )
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{
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goto IPGetHeader_Discard;
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}
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if ( optionsLen > 0 )
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MACGetArray(options, optionsLen);
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// Save header checksum; clear it and recalculate it ourselves.
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ReceivedChecksum.Val = header.HeaderChecksum;
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header.HeaderChecksum = 0;
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// Calculate checksum of header including options bytes.
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checksums[0] = ~CalcIPChecksum((BYTE*)&header, sizeof(header));
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// Calculate Options checksum too, if they are present.
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if ( optionsLen > 0 )
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checksums[1] = ~CalcIPChecksum((BYTE*)options, optionsLen);
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else
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checksums[1] = 0;
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CalcChecksum.Val = CalcIPChecksum((BYTE*)checksums,
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2 * sizeof(WORD));
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// Network to host conversion.
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SwapIPHeader(&header);
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// Make sure that checksum is correct and IP version is supported.
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if ( ReceivedChecksum.Val != CalcChecksum.Val ||
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(header.VersionIHL & 0xf0) != IP_VERSION )
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{
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// Bad/Unknown packet. Discard it.
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goto IPGetHeader_Discard;
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}
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/*
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* If caller is intrested, return destination IP address
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* as seen in this IP header.
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*/
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if ( localIP )
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localIP->Val = header.DestAddress.Val;
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remote->IPAddr.Val = header.SourceAddress.Val;
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*protocol = header.Protocol;
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*len = header.TotalLength - optionsLen -
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sizeof(header);
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return TRUE;
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IPGetHeader_Discard:
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MACDiscardRx();
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return FALSE;
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}
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/*********************************************************************
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* Function: WORD IPPutHeader( IP_ADDR *Dest,
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* BYTE Protocol,
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* WORD Identifier,
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* WORD DataLen)
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*
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* PreCondition: IPIsTxReady() == TRUE
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*
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* Input: Src - Destination node address
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* Protocol - Current packet protocol
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* Identifier - Current packet identifier
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* DataLen - Current packet data length
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*
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* Output: Handle to current packet - For use by
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* IPSendByte() function.
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*
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* Side Effects: None
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*
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* Note: Only one IP message can be transmitted at any
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* time.
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* Caller may not transmit and receive a message
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* at the same time.
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*
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********************************************************************/
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WORD IPPutHeader(NODE_INFO *remote,
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BYTE protocol,
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WORD len)
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{
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IP_HEADER header;
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header.VersionIHL = IP_VERSION | IP_IHL;
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header.TypeOfService = IP_SERVICE;
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header.TotalLength = sizeof(header) + len;
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header.Identification = ++_Identifier;
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header.FragmentInfo = 0;
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header.TimeToLive = MY_IP_TTL;
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header.Protocol = protocol;
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header.HeaderChecksum = 0;
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header.SourceAddress.v[0] = MY_IP_BYTE1;
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header.SourceAddress.v[1] = MY_IP_BYTE2;
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header.SourceAddress.v[2] = MY_IP_BYTE3;
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header.SourceAddress.v[3] = MY_IP_BYTE4;
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header.DestAddress.Val = remote->IPAddr.Val;
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SwapIPHeader(&header);
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header.HeaderChecksum = CalcIPChecksum((BYTE*)&header,
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sizeof(header));
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MACPutHeader(&remote->MACAddr, MAC_IP, (sizeof(header)+len));
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MACPutArray((BYTE*)&header, sizeof(header));
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return 0x0;
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}
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static void SwapIPHeader(IP_HEADER* h)
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{
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h->TotalLength = swaps(h->TotalLength);
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h->Identification = swaps(h->Identification);
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h->HeaderChecksum = swaps(h->HeaderChecksum);
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}
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