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public static class HttpRequestMessageExtensions
{
    private const string HttpContext = "MS_HttpContext";
    private const string RemoteEndpointMessage = "System.ServiceModel.Channels.RemoteEndpointMessageProperty";
    private const string OwinContext = "MS_OwinContext";

    public static string GetClientIpAddress(this HttpRequestMessage request)
    {
        //Web-hosting
        if (request.Properties.ContainsKey(HttpContext))
        {
            dynamic ctx = request.Properties[HttpContext];
            if (ctx != null)
            {
                return ctx.Request.UserHostAddress;
            }
        }
        //Self-hosting
        if (request.Properties.ContainsKey(RemoteEndpointMessage))
        {
            dynamic remoteEndpoint = request.Properties[RemoteEndpointMessage];
            if (remoteEndpoint != null)
            {
                return remoteEndpoint.Address;
            }
        }
        //Owin-hosting
        if (request.Properties.ContainsKey(OwinContext))
        {
            dynamic ctx = request.Properties[OwinContext];
            if (ctx != null)
            {
                return ctx.Request.RemoteIpAddress;
            }
        }
        return null;
    }
}