[ofw] question resolving IP addresses

[Tzachi Dar]

Here is a part of a code that I once wrote, I hope this can help.

Thanks
Tzachi

    HRESULT hr = S_OK;
    WspConnectIn ConnectIn;
    WspConnectOut ConnectOut;
    DWORD BytesReturned = 0;
    MIB_IPFORWARDROW BestRoute;
    char temp[10000];
    ULONG size = sizeof temp;
    PMIB_IPADDRTABLE pIp = (PMIB_IPADDRTABLE) temp;   
    unsigned int i;

    struct sockaddr_in *addr = (struct sockaddr_in *)name;
    // Verify input paramters
    if( namelen != sizeof(struct sockaddr_in) ) {
        hr = E_INVALIDARG;
        *lpErrno = WSAEFAULT;
        goto Cleanup;
    }
   
    if( addr->sin_family != AF_INET ) {
        hr = E_INVALIDARG;
        *lpErrno = WSAEFAULT;
        goto Cleanup;
    }

    if( addr->sin_addr.S_un.S_addr == INADDR_ANY ) {
        hr = E_INVALIDARG;
        *lpErrno = WSAEFAULT;
        goto Cleanup;
    }

    // Parameters were verified, lets pass the request down.
    // We translate this params to be in host format
       
    ConnectIn.DestIP = ntohl(addr->sin_addr.S_un.S_addr);
    ConnectIn.DestPort = ntohs(addr->sin_port);
    ConnectIn.pSocket = KernelHandle;
    ConnectIn.ForceMTU1024 = m_ForceMTU1024;

    // Let's get the source IP (Based on GetBestRoute)
    DWORD dwRet = GetBestRoute(
            addr->sin_addr.S_un.S_addr,
            0,
            &BestRoute);

    if (dwRet != NO_ERROR) {
        hr = HRESULT_FROM_WIN32(dwRet);
        *lpErrno = WSAENETUNREACH;
        goto Cleanup;
    }
    dwRet = GetIpAddrTable((PMIB_IPADDRTABLE) temp, &size, FALSE);
    if (dwRet != NO_ERROR) {
        SDPDLL_PRINT(TRACE_LEVEL_ERROR ,SDPDLL_SDPLIB ,("GetIpAddrTable
failed error = 0x%x", dwRet));
        hr = HRESULT_FROM_WIN32(dwRet);
        *lpErrno = WSAENETUNREACH;
        goto Cleanup;
    }

    ConnectIn.SrcIP = 0;
    for ( i=0;i<pIp->dwNumEntries ; i++) {
        if (pIp->table[i].dwIndex == BestRoute.dwForwardIfIndex) {
            // We have found the interface that we want
            ConnectIn.SrcIP = ntohl(pIp->table[i].dwAddr);
        }
    }
    if (ConnectIn.SrcIP == 0) {
        // We couldn't find the local addresses
        hr = E_INVALIDARG;
        *lpErrno = WSAENETUNREACH;
        goto Cleanup;       
    }

    // Now do the arp of the local addresses
    ULONG pMacAddr[2], PhyAddrLen ;
    PhyAddrLen = sizeof(pMacAddr);
    const int MaxArp = 13;

    for (int i = 0 ; i < MaxArp; i++) {
        PhyAddrLen = sizeof(pMacAddr);
        dwRet = SendARP(addr->sin_addr.S_un.S_addr ,0 ,pMacAddr,
&PhyAddrLen );
        if (dwRet == ERROR_GEN_FAILURE) {
            // This seems to be a BUG in windows when some threads call
ARP togeater
            int sevirity;
            if (i < MaxArp-1) {
                sevirity = TRACE_LEVEL_INFORMATION;
            } else {
                sevirity = TRACE_LEVEL_ERROR;
            }
            Sleep(rand() * 10*i*i / RAND_MAX + 10 * i);
           
        } else {
            // Everyting is fine
            break;
        }
    }
     if (dwRet != NO_ERROR) {
       
            hr = HRESULT_FROM_WIN32(dwRet);
            *lpErrno = WSAENETUNREACH;
            goto Cleanup;
       
        }
    memcpy(ConnectIn.DestMac, pMacAddr, MAC_ADDR_SIZE);

> -----Original Message-----
> From: ofw-bounces at lists.openfabrics.org
> [mailto:ofw-bounces at lists.openfabrics.org] On Behalf Of Sean Hefty
> Sent: Thursday, December 11, 2008 12:38 AM
> To: ofw at lists.openfabrics.org
> Subject: [ofw] question resolving IP addresses
>
> Does anyone know of sample code or what APIs to invoke to
> find what source IP address to use to reach a given
> destination IP address?  I need APIs that work on 2003 and 2008
>
> _______________________________________________
> ofw mailing list
> ofw at lists.openfabrics.org
> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ofw
> 

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