有没有办法通过WebClient 使用 socks 代理？特别是它提供的DownloadString 方法？
我不想使用任何第三方的东西，比如 privoxy、freecap 等等，我不能使用像 Chilkat 那样的商业库。我尝试使用来自 http://www.mentalis.org/ 的东西，实际上我使用了他们的 WebRequest 实现，但它们似乎没有类似的 WebClient 功能。
【问题讨论】：
标签： c# .net webclient socks webclient-download
WebRequest/WebResponse 类和扩展的 WebClient 类不直接支持SOCKS（它依赖于WebRequest 来完成其工作）。
确实不能，因为它在传输层 (TCP/IP) 上工作，而不是通过简单的重定向到转发 HTTP 请求的服务器（这是 WebRequest/WebResponse 类工作的级别开）。
您可以创建一个specialized derivation of WebRequest/WebResponse（它使用ProxySocket 来处理低级握手，然后），然后创建一个专门的WebClient class 覆盖GetWebRequest 和GetWebResponse 方法。
一旦你用那个类代替了你的 WebClient 实例，它应该可以正常工作（但你可能必须在每次使用它的情况下设置代理）。
【讨论】：
这是我最终的做法，谢谢 casperOne 的回答
public class SocksWebClient : WebClient
{
public IProxyDetails ProxyDetails { get; set; }
public string UserAgent { get; set; }
protected override WebRequest GetWebRequest(Uri address)
{
WebRequest result = null;
if (ProxyDetails != null)
{
if (ProxyDetails.ProxyType == ProxyType.Proxy)
{
result = (HttpWebRequest)WebRequest.Create(address);
result.Proxy = new WebProxy(ProxyDetails.FullProxyAddress);
if (!string.IsNullOrEmpty(UserAgent))
((HttpWebRequest)result).UserAgent = UserAgent;
}
else if (ProxyDetails.ProxyType == ProxyType.Socks)
{
result = SocksHttpWebRequest.Create(address);
result.Proxy = new WebProxy(ProxyDetails.FullProxyAddress);
//TODO: implement user and password
}
else if (ProxyDetails.ProxyType == ProxyType.None)
{
result = (HttpWebRequest)WebRequest.Create(address);
if (!string.IsNullOrEmpty(UserAgent))
((HttpWebRequest)result).UserAgent = UserAgent;
}
}
else
{
result = (HttpWebRequest)WebRequest.Create(address);
if (!string.IsNullOrEmpty(UserAgent))
((HttpWebRequest)result).UserAgent = UserAgent;
}
return result;
}
}
SocksHttpWebRequest类取自@casperOne所链接的blog，其代码如下：
using System;
using System.Collections.Specialized;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using Org.Mentalis.Network.ProxySocket;
namespace Ditrans
{
public class SocksHttpWebRequest : WebRequest
{
#region Member Variables
private readonly Uri _requestUri;
private WebHeaderCollection _requestHeaders;
private string _method;
private SocksHttpWebResponse _response;
private string _requestMessage;
private byte[] _requestContentBuffer;
// darn MS for making everything internal (yeah, I'm talking about you, System.net.KnownHttpVerb)
static readonly StringCollection validHttpVerbs =
new StringCollection { "GET", "HEAD", "POST", "PUT", "DELETE", "TRACE", "OPTIONS" };
#endregion
#region Constructor
private SocksHttpWebRequest(Uri requestUri)
{
_requestUri = requestUri;
}
#endregion
#region WebRequest Members
public override WebResponse GetResponse()
{
if (Proxy == null)
{
throw new InvalidOperationException("Proxy property cannot be null.");
}
if (String.IsNullOrEmpty(Method))
{
throw new InvalidOperationException("Method has not been set.");
}
if (RequestSubmitted)
{
return _response;
}
_response = InternalGetResponse();
RequestSubmitted = true;
return _response;
}
public override Uri RequestUri
{
get { return _requestUri; }
}
public override IWebProxy Proxy { get; set; }
public override WebHeaderCollection Headers
{
get
{
if (_requestHeaders == null)
{
_requestHeaders = new WebHeaderCollection();
}
return _requestHeaders;
}
set
{
if (RequestSubmitted)
{
throw new InvalidOperationException("This operation cannot be performed after the request has been submitted.");
}
_requestHeaders = value;
}
}
public bool RequestSubmitted { get; private set; }
public override string Method
{
get
{
return _method ?? "GET";
}
set
{
if (validHttpVerbs.Contains(value))
{
_method = value;
}
else
{
throw new ArgumentOutOfRangeException("value", string.Format("'{0}' is not a known HTTP verb.", value));
}
}
}
public override long ContentLength { get; set; }
public override string ContentType { get; set; }
public override Stream GetRequestStream()
{
if (RequestSubmitted)
{
throw new InvalidOperationException("This operation cannot be performed after the request has been submitted.");
}
if (_requestContentBuffer == null)
{
_requestContentBuffer = new byte[ContentLength];
}
else if (ContentLength == default(long))
{
_requestContentBuffer = new byte[int.MaxValue];
}
else if (_requestContentBuffer.Length != ContentLength)
{
Array.Resize(ref _requestContentBuffer, (int) ContentLength);
}
return new MemoryStream(_requestContentBuffer);
}
#endregion
#region Methods
public static new WebRequest Create(string requestUri)
{
return new SocksHttpWebRequest(new Uri(requestUri));
}
public static new WebRequest Create(Uri requestUri)
{
return new SocksHttpWebRequest(requestUri);
}
private string BuildHttpRequestMessage()
{
if (RequestSubmitted)
{
throw new InvalidOperationException("This operation cannot be performed after the request has been submitted.");
}
var message = new StringBuilder();
message.AppendFormat("{0} {1} HTTP/1.0\r\nHost: {2}\r\n", Method, RequestUri.PathAndQuery, RequestUri.Host);
// add the headers
foreach (var key in Headers.Keys)
{
message.AppendFormat("{0}: {1}\r\n", key, Headers[key.ToString()]);
}
if (!string.IsNullOrEmpty(ContentType))
{
message.AppendFormat("Content-Type: {0}\r\n", ContentType);
}
if (ContentLength > 0)
{
message.AppendFormat("Content-Length: {0}\r\n", ContentLength);
}
// add a blank line to indicate the end of the headers
message.Append("\r\n");
// add content
if(_requestContentBuffer != null && _requestContentBuffer.Length > 0)
{
using (var stream = new MemoryStream(_requestContentBuffer, false))
{
using (var reader = new StreamReader(stream))
{
message.Append(reader.ReadToEnd());
}
}
}
return message.ToString();
}
private SocksHttpWebResponse InternalGetResponse()
{
var response = new StringBuilder();
using (var _socksConnection =
new ProxySocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
{
var proxyUri = Proxy.GetProxy(RequestUri);
var ipAddress = GetProxyIpAddress(proxyUri);
_socksConnection.ProxyEndPoint = new IPEndPoint(ipAddress, proxyUri.Port);
_socksConnection.ProxyType = ProxyTypes.Socks5;
// open connection
_socksConnection.Connect(RequestUri.Host, 80);
// send an HTTP request
_socksConnection.Send(Encoding.ASCII.GetBytes(RequestMessage));
// read the HTTP reply
var buffer = new byte[1024];
var bytesReceived = _socksConnection.Receive(buffer);
while (bytesReceived > 0)
{
response.Append(Encoding.ASCII.GetString(buffer, 0, bytesReceived));
bytesReceived = _socksConnection.Receive(buffer);
}
}
return new SocksHttpWebResponse(response.ToString());
}
private static IPAddress GetProxyIpAddress(Uri proxyUri)
{
IPAddress ipAddress;
if (!IPAddress.TryParse(proxyUri.Host, out ipAddress))
{
try
{
return Dns.GetHostEntry(proxyUri.Host).AddressList[0];
}
catch (Exception e)
{
throw new InvalidOperationException(
string.Format("Unable to resolve proxy hostname '{0}' to a valid IP address.", proxyUri.Host), e);
}
}
return ipAddress;
}
#endregion
#region Properties
public string RequestMessage
{
get
{
if (string.IsNullOrEmpty(_requestMessage))
{
_requestMessage = BuildHttpRequestMessage();
}
return _requestMessage;
}
}
#endregion
}
}
请注意，正如 @casperOne 所指出的，这使用了一个名为 ProxySocket 的（免费）第三方库。
【讨论】：
我也遇到了这个，发现了不错的BetterHttpClient
它派生自 WebClient 并允许您指定 socks 代理：
BetterHttpClient.HttpClient client = new BetterHttpClient.HttpClient(new BetterHttpClient.Proxy("IP address", port, BetterHttpClient.ProxyTypeEnum.Socks));
【讨论】：
为了做到这一点，我一直在寻找图书馆。最后我找到了MihaZupan/HttpToSocks5Proxy，它是真正的救星。就像这样你可以使用它：
using MihaZupan;
var proxy = new HttpToSocks5Proxy("127.0.0.1", 1080,
"username", "password" // optional
);
var handler = new HttpClientHandler { Proxy = proxy };
HttpClient httpClient = new HttpClient(handler, true);
var result = await httpClient.SendAsync(
new HttpRequestMessage(HttpMethod.Get, "https://httpbin.org/ip"));
Console.WriteLine("HTTPS GET: " + await result.Content.ReadAsStringAsync());
如果您想要更方便的WebClient-esque API 来读取内容，您可以将 response-read 调用包装到扩展方法中：
public static class ExtensionMethods
{
public static async Task<string> DownloadStringAsync(this HttpClient client, string url)
{
var response = await client.SendAsync(new HttpRequestMessage(
HttpMethod.Get, url));
return await response.Content.ReadAsStringAsync();
}
}
【讨论】：
对于未来的读者： 从 .NET 6 开始，socks 代理是 supported 原生的 HttpClient。
在撰写此答案时，WebClient 被视为已过时。应该改用HttpClient。
【讨论】：