Asp.Net Core Get Request IpAddress

aspnet-core-get-user-ipaddress.cs

public static string GetIpAddress(this HttpContext _context, bool tryUseXForwardHeader = true)
{
    string ip = string.Empty;

    /*-----------------------------------------------------------------------------------
    |   Todo support new "Forwarded" header (2014) 
    |   https://en.wikipedia.org/wiki/X-Forwarded-For
    |
    |   X-Forwarded-For (csv list):  Using the First entry in the list seems to work
    |   for 99% of cases however it has been suggested that a better (although tedious)
    |   approach might be to read each IP from right to left and use the first public IP.
    |
    |   http://stackoverflow.com/a/43554000/538763
    |
    |------------------------------------------------------------------------------------*/
    if (tryUseXForwardHeader)
        ip = _context.GetHeaderValueAs<string>("X-Forwarded-For").SplitCsv().FirstOrDefault();

    // RemoteIpAddress is always null in DNX RC1 Update1 (bug).
    if (!ip.IsValid() && _context?.Connection?.RemoteIpAddress != null)
        ip = _context.Connection.RemoteIpAddress.ToString();

    if (!ip.IsValid())
        ip = _context.GetHeaderValueAs<string>("REMOTE_ADDR");

    if (!ip.IsValid())
        throw new Exception("Unable to determine caller's IP.");

    if (ip.StartsWith("::ffff:"))
        ip = ip.Replace("::ffff:", string.Empty);

    return ip.Trim();
}

// Usage In Controller
protected string RequestIPAddress => HttpContext.GetIpAddress();