HttpRequestMessage在多IP环境中配置IP

Question

我在一个主机上有几个is，当我从HttpClient与HttpRequestMessage建立连接时，我想选择使用哪一个。如果不使用套接字，自己编写一个简单的http客户端，就能做到这一点吗？

我在寻找bind在connect之前的socket级，但是HttpClient__.或者另一种选择。

Answer 1

因此，如果在Windows机器上使用默认的HttpClient消息处理程序，HttpClient将使用.Net HttpWebRequest来完成其工作。这反过来又依赖于ServicePointManager来提供一个ServicePoint来管理到URI的连接。对于任何域，您都可以连接到它的ServicePoint，以改变它绑定到IPEndPoint的方式。

如果您接受要连接的URI并找到它的ServicePoint

var sp = ServicePointManager.FindServicePoint(uri);

然后你就可以：

var sp = ServicePointManager.FindServicePoint(new Uri("http://www.google.com"));
sp.BindIPEndPointDelegate = (servicePoint, remoteEndPoint, retryCount) => {
    IPAddress adapterIpAddress = //your chosen adapter's IP address
    return new IPEndPoint(adapterIpAddress, 0);
};

如果您想得到真正的jazzy，您可以将其折叠到一个DelegatingHandler中，以便HttpClient为您处理所有事情：

public class RebindingHandler : DelegatingHandler
{
    private BindIPEndPoint bindHandler;
    public RebindingHandler(IEnumerable<IPAddress> adapterAddresses, 
                            HttpMessageHandler innerHandler = null)
        : base(innerHandler ?? new WebRequestHandler())
    {
        var addresses = adapterAddresses.ToList();
        if(!addresses.Any())
        {
            throw new ArgumentException();
        }
        var idx = 0;
        bindHandler = (servicePoint, remoteEndPoint, retryCount) => {
            int i = Interlocked.Increment(ref idx);
            uint i2 = unchecked((uint)i);
            int index = (int)(((long)i2) % addresses.Count);

            IPAddress adapterIpAddress = addresses[index];
            return new IPEndPoint(adapterIpAddress, 0);
        };
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,
        CancellationToken cancellationToken)
    {
        var sp = ServicePointManager.FindServicePoint(request.RequestUri);
        sp.BindIPEndPointDelegate = bindHandler;
        var httpResponseMessage = await base.SendAsync(request, cancellationToken);
        return httpResponseMessage;
    }
}

然后你就可以：

var addresses = new List<IPAddress>(); //this contains your adapter addresses
var client = new HttpClient(new RebindingHandler(addresses));

当您使用client时，内部处理程序将自动注册相关的ServicePoint，以使用围绕一组IPEndPoints旋转的BindIPEndPoint。