/// <summary>
/// Reads the unmanaged sockaddr structure returned by a WinAPI function
/// </summary>
/// <param name="pSockaddrStructure">pointer to the unmanaged sockaddr structure</param>
/// <returns>IP address and port number</returns>
private static IPEndPoint ReadSockAddrStorageStructure(SOCKADDR_STORAGE sockAddrStorageStructure)
{
short sAddressFamily = sockAddrStorageStructure.ss_family;
AddressFamily addressFamily = (AddressFamily)sAddressFamily;
int sockAddrSructureSize;
IPEndPoint ipEndPointAny;
switch (addressFamily)
{
case AddressFamily.InterNetwork:
// IP v4 address
sockAddrSructureSize = 8;
var socketAddress = new SocketAddress(AddressFamily.InterNetwork, sockAddrSructureSize);
socketAddress[0] = 2;
socketAddress[1] = 0;
for (int i = 2; i < sockAddrSructureSize; i++)
{
socketAddress[i] = sockAddrStorageStructure.__ss_pad1[i - 2];
}
ipEndPointAny = new IPEndPoint(IPAddress.Any, 0);
return((IPEndPoint)ipEndPointAny.Create(socketAddress));
default:
throw new ArgumentOutOfRangeException(nameof(sockAddrStorageStructure), "Unknown address family");
}
}
//********************************************************************************************
// Function: GetPreferredAddress
//
// Description: This function sorts a list of Ipv4 & Ipv6 addresses, and returns the "best" address that stack determines
//
//********************************************************************************************
static Win32Error GetPreferredAddress(SOCKADDR_IN6[] pAddrList, out SOCKADDR_STORAGE pPreferredAddr)
{
Win32Error dwErr = Win32Error.ERROR_SUCCESS;
pPreferredAddr = default;
// Initialize WinSock
using var wsa = SafeWSA.Initialize();
// create socket
var socketIoctl = WSASocket(ADDRESS_FAMILY.AF_INET6, SOCK.SOCK_DGRAM, 0, IntPtr.Zero, 0, WSA_FLAG.WSA_FLAG_OVERLAPPED);
if (socketIoctl == SOCKET.INVALID_SOCKET)
{
dwErr = WSAGetLastError();
Console.Write("WSASocket failed, (dwErr = {0}).", dwErr);
return(dwErr);
}
var numElement = pAddrList.Length;
var pSockAddrList = Array.ConvertAll(pAddrList, v6 => new SOCKADDR(v6));
var pSocketAddrList = new SOCKET_ADDRESS_LIST {
iAddressCount = numElement, Address = Array.ConvertAll(pSockAddrList, sa => new SOCKET_ADDRESS {
iSockaddrLength = sa.Size, lpSockaddr = sa.DangerousGetHandle()
})
};
// sort addresses
using var ppSocketAddrList = SafeHGlobalHandle.CreateFromStructure(pSocketAddrList);
uint dwSize = 4U + (uint)(Marshal.SizeOf <SOCKET_ADDRESS>() * pSocketAddrList.iAddressCount);
dwErr = WSAIoctl(socketIoctl, WinSockIOControlCode.SIO_ADDRESS_LIST_SORT, ppSocketAddrList, dwSize, ppSocketAddrList, dwSize, out var dwBytes);
pSocketAddrList = ppSocketAddrList.ToStructure <SOCKET_ADDRESS_LIST>();
if (dwErr == SOCKET_ERROR)
{
dwErr = WSAGetLastError();
Console.Write("WSAIoctl sort address failed, (dwErr = {0}).", dwErr);
return(dwErr);
}
var pBestAddress = new IPAddress(pSocketAddrList.Address[0].lpSockaddr.ToArray <byte>(pSocketAddrList.Address[0].iSockaddrLength));
pPreferredAddr = (SOCKADDR_STORAGE)(pBestAddress.IsIPv4MappedToIPv6 ? pBestAddress.MapToIPv4() : pBestAddress);
if (socketIoctl != SOCKET.INVALID_SOCKET)
{
closesocket(socketIoctl);
socketIoctl = SOCKET.INVALID_SOCKET;
}
return(dwErr);
}
//********************************************************************************************
// Function: ConvertStringToSockAddr
//
// Description: Converts destination hostname or URL to IP address
//
//********************************************************************************************
static HRESULT ConvertStringToSockAddr([In] string destIPAddr, out SOCKADDR_STORAGE socketAddress)
{
const int NO_ERROR = 0;
HRESULT hr = HRESULT.S_OK;
socketAddress = default;
//Intialize socket, to use GetAddrInfoW()
using var wsa = SafeWSA.Initialize();
//This do--while(false) loop is used to break in between based on error conditions
do
{
//get Destination IP address from Destination address string hostname or URL
var dwErr = GetAddrInfoW(destIPAddr, default, default, out var result);
private static SOCKADDR_STORAGE CreateSockAddrStorageStructure(int port)
{
var result = new SOCKADDR_STORAGE();
result.ss_family = (short)AddressFamily.InterNetwork;
var ipEndPoint = new IPEndPoint(IPAddress.Any, port);
var socketAddress = ipEndPoint.Serialize();
result.__ss_pad1 = new byte[6];
for (var i = 0; i < result.__ss_pad1.Length; i++)
{
result.__ss_pad1[i] = socketAddress[i + 2];
}
return(result);
}
/// <summary>
/// Reads the unmanaged sockaddr structure returned by a WinAPI function
/// </summary>
/// <param name="pSockaddrStructure">pointer to the unmanaged sockaddr structure</param>
/// <returns>IP address and port number</returns>
private static IPEndPoint ReadSockAddrStorageStructure(SOCKADDR_STORAGE sockAddrStorageStructure)
{
short sAddressFamily = sockAddrStorageStructure.ss_family;
AddressFamily addressFamily = (AddressFamily)sAddressFamily;
int sockAddrSructureSize;
IPEndPoint ipEndPointAny;
switch (addressFamily)
{
case AddressFamily.InterNetwork:
// IP v4 address
sockAddrSructureSize = 8;
var socketAddress = new SocketAddress(AddressFamily.InterNetwork, sockAddrSructureSize);
socketAddress[0] = 2;
socketAddress[1] = 0;
for (int i = 2; i < sockAddrSructureSize; i++)
{
socketAddress[i] = sockAddrStorageStructure.__ss_pad1[i - 2];
}
ipEndPointAny = new IPEndPoint(IPAddress.Any, 0);
return (IPEndPoint)ipEndPointAny.Create(socketAddress);
default:
throw new ArgumentOutOfRangeException(nameof(sockAddrStorageStructure), "Unknown address family");
}
}
private static SOCKADDR_STORAGE CreateSockAddrStorageStructure(int port)
{
var result = new SOCKADDR_STORAGE();
result.ss_family = (short)AddressFamily.InterNetwork;
var ipEndPoint = new IPEndPoint(IPAddress.Any, port);
var socketAddress = ipEndPoint.Serialize();
result.__ss_pad1 = new byte[6];
for (var i = 0; i < result.__ss_pad1.Length; i++)
{
result.__ss_pad1[i] = socketAddress[i + 2];
}
return result;
}
