ip.c

本代码是本人毕设所做的GPRS数传系统的软件部分

/*/////////////////////////////////////////////////////////////////////////////
File Name : IP.C
Author : Rene Trenado
Location : Motorola Applications Lab, Baja California
Date Created : September 2000
Current Revision : 0.0
Notes : This file contains the Internet Protocol variables & support routines
/////////////////////////////////////////////////////////////////////////////*/
#include "ip.h"
#include "ppp.h"
extern BYTE InBuffer [PPP_BUFFER_SIZE + 1]; // Input Buffer for PPP data
extern BYTE OutBuffer[PPP_BUFFER_SIZE + 1];
BYTE IPAddress[4] = {220, 1, 141, 149}; // Default IP Address
static volatile char IPAdapter = PPP; // Default interface for IP output
IPDatagram *ip_in; // A pointer to received IP datagrams
IPDatagram *ip_out; // Global buffer for IP packet output
/***********************************************************************
Function : IPInit
Parameters : None
Date : September 2000
Desc : Initializes the IP module pointers***********************************************************************/
void IPInit (void) {
ip_in = (IPDatagram *)&InBuffer [4];
ip_out = (IPDatagram *)&OutBuffer [4];
}
/***********************************************************************
Function : Bind adapter
Parameters : Interface: A Byte ID
Date : September 2000
Desc : Selects the output format of an IP packet
***********************************************************************/
void IPBindAdapter (INTERFACE Interface) {
IPAdapter = Interface; // switch to different output interface
}
/***********************************************************************
Function : IPNetSend
Parameters : ip: A pointer to a IP datagram to transmit
Date : November 2000
Desc : Sends a IP datagram over the interface specified
***********************************************************************/
void IPNetSend (IPDatagram* ip) {
static WORD Id = 0xF0; // ID to be used in IP datagrams
ip_out->Version_HLen = 0x45; // Header Forma=IPv4, Length = 5
ip_out->Service = 0; // Always zero
ip_out->LengthUpper = 0; // High byte of datagram Length
ip_out->ID = htons(Id++); // Merge IP ID
ip_out->Frag = 0; // No flags nor enable fragmentation
ip_out->TTL = 0x80; // Time to live set to default
ip_out->Checksum = 0; // Clear checksum to avoid
// miscalculations
// Get checksum of entire datagram
ip_out->Checksum = htons(IPCheckSum ((BYTE *)ip_out, 10));
switch (IPAdapter) { // Select the adapter to output the IP datagram
case PPP: // Output through PPP adapter
OutBuffer [0] = 0xff; // Frame PPP packet
OutBuffer [1] = 0x03;
OutBuffer [2] = 0x00; // This is a IP datagram, set
// protocol type
OutBuffer [3] = 0x21;ProcPPPSend (OutBuffer, OutBuffer [7] + 6);
break;
//case SLIP: // Output through SLIP interface
//ProcSLIPSend ((BYTE *)ip_out, ip_out->Length);
//break;
case ETHERNET: // Send datagram over ethernet
break;
default:
break;
}
}
/***********************************************************************
Function : IPCompare
Parameters : Ip: A pointer to a IP address to compare
Date : November 2000
Desc : Compares an IP address to the default IP address defined
in this module
***********************************************************************/
BYTE IPCompare (BYTE *IPOne) {
if (IPOne [0] != IPAddress[0]) return (BYTE)0x00;
if (IPOne [1] != IPAddress[1]) return (BYTE)0x00;
if (IPOne [2] != IPAddress[2]) return (BYTE)0x00;
if (IPOne [3] != IPAddress[3]) return (BYTE)0x00;
return (BYTE) 0x01;
}
/***********************************************************************
Function : IPChecksum
Parameters : Data: A pointer to an array of Words
Size: Size of the array
Date : August 2000
Desc : Obtains the IP checksum of an array of 16-bit words of size "Size"
***********************************************************************/
DWORD IPCheckSum (BYTE* Data, WORD Size) {
unsigned long Sum = 0;
while (Size-->0) {
Sum += ((unsigned long)((*Data << 8) + *(Data+1)) & 0xFFFF);Data+=2;
}
Sum = (Sum >> 16) + (Sum & 0xFFFF);
Sum += (Sum >> 16);
return (WORD) ~Sum;
}