iparp.cpp

编程对ARP协议的理解

/*---------------------------------------------------------------------------
    Copyright (c) 1998  Microsoft Corporation
    Module Name: IpArp.exe    
    File       : IpArp.cpp
    Description: This file demonstrates the use of IP Helper APIs to
                 manipulate ARP cache.
    Author:
    Frank Li           April 16, 1998

    
    Revision History:
    Who         When        What
    --------    --------    ----------------------------------
    Frank Li    04-16-98    created   
---------------------------------------------------------------------------*/

#include "IpArp.h"


void Usage(char * pszProgramName)
{
    printf("%s -s inet_addr eth_addr [if_addr]\n", pszProgramName);
    printf("%s -d inet_addr [if_addr]\n", pszProgramName);
    printf("%s -a\n", pszProgramName);

    printf("-a            Displays current ARP entries by interrogating the current\n");
    printf("              protocol data.\n");
    printf("-d            Deletes the host specified by inet_addr.\n");
    printf("-s            Adds the host and associates the Internet address inet_addr\n");
    printf("              with the Physical address eth_addr.  The Physical address is\n");
    printf("              given as 6 hexadecimal bytes separated by hyphens. The entry\n");
    printf("              is permanent.\n");
    printf("eth_addr      Specifies a physical address.\n");
    printf("if_addr       If present, this specifies the Internet address of the\n");
    printf("              interface whose address translation table should be modified.\n");
    printf("              If not present, the first applicable interface will be used.\n");
    printf("Example:\n");
    printf("   >IpArp -s 157.55.85.212   00-aa-bb-cc-dd-ee 0x2000003 .... Add a static\n");
    printf("                                  arp entry on interface number 0x2000003.\n");
    printf("   >IpArp -a                                    ....Displays the arp table.\n");
    printf("   >IpArp -d 157.55.85.212                      ....Delete an entry.\n");
    WSACleanup();
    exit(1);
}


void _cdecl main(int argc, char **argv)
{
    WORD wVersionRequested = MAKEWORD(1,1);
    WSADATA wsaData;
    int nRet;

    nRet = WSAStartup(wVersionRequested, &wsaData);
    if (wsaData.wVersion != wVersionRequested)
    {    
        fprintf(stderr,"\n Wrong version\n");
        return;
    }


    if ((argc < 2) || (argv[1][0] != '-'))        
        Usage("IpArp");
    if (strlen(argv[1]) > 2)     
        Usage("IpArp");  

    switch(argv[1][1]) 
    {    
    case 'a':
        // Print arp table
        DoGetIpNetTable();
        break;     
    case 's':      
        //Update or add an ARP Internet/Ethernet Address entry 
        if (argc == 4)
            DoSetIpNetEntry(argv[2], argv[3]);
        else if (argc == 5)
            DoSetIpNetEntry(argv[2], argv[3], argv[4]);
        else
            Usage("IpArp");
        break;    
    case 'd':     
        //Delete an Internet/Ethernet Address pair from the ARP table 
        if (argc == 3)
            DoDeleteIpNetEntry(argv[2]);
        else if (argc == 4)
            DoDeleteIpNetEntry(argv[2], argv[3]);
        else
            Usage("IpArp");                
        break;  
    default:    
        // help
        Usage("IpArp");        
        break;    
    }
    WSACleanup();
}


void DoGetIpNetTable()
{
    DWORD dwStatus;
    PMIB_IPNETTABLE pIpArpTab = NULL;


    if ( (dwStatus = MyGetIpNetTable(pIpArpTab, TRUE)) == NO_ERROR)
    {
        PrintIpNetTable(pIpArpTab);
        free(pIpArpTab);
        return;
    }
    else if ( dwStatus == ERROR_NO_DATA)
    {
        printf("No entries in arp cache.\n");
        if (pIpArpTab)
            free (pIpArpTab);
        return;
    }
    else
    {
        if (pIpArpTab)
            free (pIpArpTab);
        printf("IpArp returned 0x%x\n", dwStatus);
        return;
    }

}

//----------------------------------------------------------------------------
// Add an arp entry with ip dotted decimal address of "pszDottedInetAddr" and
// physical address of "pszPhysAddr" in 00-aa-bb-cc-dd-ee format on interface 
// index of "pszInterface" in hex form.
//----------------------------------------------------------------------------
void DoSetIpNetEntry(char* pszDottedInetAddr, char* pszPhysAddr, char* pszInterface)
{
    DWORD dwInetAddr = 0; // ip address
    DWORD dwStatus;
    BYTE bPhysAddr[MAXLEN_PHYSADDR]; 

    if (pszDottedInetAddr == NULL || pszPhysAddr == NULL)
    {
        printf("IpArp: Bad Argument\n");
        return;
    }

    dwInetAddr = inet_addr(pszDottedInetAddr); // convert dotted ip addr. to ip addr.
    if (dwInetAddr == INADDR_NONE)
    {
        printf("IpArp: Bad Argument %s\n", pszDottedInetAddr);
        return;
    }

    if (StringToPhysAddr(pszPhysAddr, (char*)bPhysAddr ) != 0)
    {
        printf("IpArp: Bad Argument %s\n", pszPhysAddr);
        return;
    }
    MIB_IPNETROW arpEntry; // an arp entry
    if (pszInterface)
    {
        // User provides a interface index number
        sscanf(pszInterface, "%X",&(arpEntry.dwIndex));
    }
    else
    {
        // add this to the first available interface
        PMIB_IPADDRTABLE pIpAddrTable = NULL;
        if ( (dwStatus = MyGetIpAddrTable(pIpAddrTable)) != NO_ERROR)
        {
            printf("IpArp: Couldn't find a interface number to add your arp entry\n");
            return;
        }
        arpEntry.dwIndex = pIpAddrTable->table[0].dwIndex;
        free(pIpAddrTable);
    }
    arpEntry.dwPhysAddrLen = 6;
    memcpy(arpEntry.bPhysAddr, bPhysAddr, 6);
    arpEntry.dwAddr = dwInetAddr;
    arpEntry.dwType = MIB_IPNET_TYPE_STATIC; //static arp entry
    dwStatus = SetIpNetEntry(&arpEntry);
    if (dwStatus != NO_ERROR)
    {
        printf("IpArp: couldn't add (%s, %s), dwStatus = %lu.\n",
                    pszDottedInetAddr, pszPhysAddr, dwStatus);
    }
}
//----------------------------------------------------------------------------
// Delete an arp entry with ip dotted decimal address of "pszDottedInetAddr" 
// and interface index of "pszInterface" in hex form.
//----------------------------------------------------------------------------
void DoDeleteIpNetEntry(char* pszDottedInetAddr, char* pszInterface)
{
    DWORD dwInetAddr = 0; // ip address
    DWORD dwStatus;

    if (pszDottedInetAddr == NULL)
    {
        printf("IpArp: Bad Argument\n");
        return;
    }
    dwInetAddr = inet_addr(pszDottedInetAddr); // convert dotted ip addr. to ip addr.
    if (dwInetAddr == INADDR_NONE)
    {
        printf("IpArp: Bad Argument %s\n", pszDottedInetAddr);
        return;
    }

    MIB_IPNETROW arpEntry; // an arp entry
    if (pszInterface)
    {
        // User provides a interface index number
        sscanf(pszInterface, "%X",&(arpEntry.dwIndex));
    }
    else
    {
        // try to delete this from first available interface
        PMIB_IPADDRTABLE pIpAddrTable = NULL;
        if ( (dwStatus = MyGetIpAddrTable(pIpAddrTable)) != NO_ERROR)
        {
            printf("IpArp: Couldn't find a interface number to add your arp entry\n");
            return;
        }
        arpEntry.dwIndex = pIpAddrTable->table[0].dwIndex;
        free(pIpAddrTable);
    }
    
    arpEntry.dwAddr = dwInetAddr;
    dwStatus = DeleteIpNetEntry(&arpEntry);
    if (dwStatus != NO_ERROR)
    {
        printf("IpArp: couldn't delete (%s), dwStatus = %lu.\n",
                    pszDottedInetAddr, dwStatus);
    }


}
//----------------------------------------------------------------------------
// Inputs: pIpAddrTable is the IP address table
//         dwIndex is the Interface Number
// Output: If it returns TRUE, str contains the ip address of the interface
//----------------------------------------------------------------------------
bool InterfaceIdxToInterfaceIp(PMIB_IPADDRTABLE pIpAddrTable, DWORD dwIndex, char str[])
{
    struct in_addr inadTmp;
    char* szIpAddr;

    if (pIpAddrTable == NULL ||  str == NULL)
        return FALSE;
    str[0] = '\0';
    for (DWORD dwIdx = 0; dwIdx < pIpAddrTable->dwNumEntries; dwIdx++)
    {
        if (dwIndex == pIpAddrTable->table[dwIdx].dwIndex)
        {
            inadTmp.s_addr = pIpAddrTable->table[dwIdx].dwAddr;
            szIpAddr = inet_ntoa(inadTmp);
            if (szIpAddr)
            {
                strcpy(str, szIpAddr);
                return TRUE;
            }
            else
                return FALSE;
        }
    }
    return FALSE;

}

//-------------------------------------------------------------------------
// Input: str points to an ethernet address of the form 00-aa-bb-cc-dd-ee
// If it returns 0, ret contains the 6 bytes ethernet address.
//-------------------------------------------------------------------------