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create cs file #3322

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204 changes: 204 additions & 0 deletions PACServer.cs
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Original file line number Diff line number Diff line change
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using Shadowsocks.Net;
using Shadowsocks.Utilities;
using Shadowsocks.Net.Crypto;
using Splat;
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Reflection;

namespace Shadowsocks.PAC
{
public class PACServer : StreamService, IEnableLogger
{
public const string RESOURCE_NAME = "pac";

private string PacSecret
{
get
{
if (string.IsNullOrEmpty(_cachedPacSecret))
{
_cachedPacSecret = Base64Url.Encode(RNG.GetBytes(32));
}
return _cachedPacSecret;
}
}
private string _cachedPacSecret = "";
private bool _PACServerEnableSecret;
public string PacUrl { get; private set; } = "";

private PACDaemon _pacDaemon;

public PACServer(PACDaemon pacDaemon, bool PACServerEnableSecret)
{
_pacDaemon = pacDaemon;
_PACServerEnableSecret = PACServerEnableSecret;
}

public void UpdatePACURL(EndPoint localEndPoint)
{
string usedSecret = _PACServerEnableSecret ? $"&secret={PacSecret}" : "";
string contentHash = GetHash(_pacDaemon.GetPACContent());
PacUrl = $"http://{localEndPoint}/{RESOURCE_NAME}?hash={contentHash}{usedSecret}";
this.Log().Debug("Setting PAC URL: {PacUrl}");
}

private static string GetHash(string content)
{

return Base64Url.Encode(CryptoUtils.MD5(Encoding.ASCII.GetBytes(content)));
}

public override bool Handle(CachedNetworkStream stream, object state)
{
byte[] fp = new byte[256];
int len = stream.ReadFirstBlock(fp);
return Handle(fp, len, stream.Socket, state);
}

[Obsolete]
public override bool Handle(byte[] firstPacket, int length, Socket socket, object state)
{
if (socket.ProtocolType != ProtocolType.Tcp)
{
return false;
}

try
{
/*
* RFC 7230
*
GET /hello.txt HTTP/1.1
User-Agent: curl/7.16.3 libcurl/7.16.3 OpenSSL/0.9.7l zlib/1.2.3
Host: www.example.com
Accept-Language: en, mi
*/

string request = Encoding.UTF8.GetString(firstPacket, 0, length);
string[] lines = request.Split('\r', '\n');
bool hostMatch = false, pathMatch = false, useSocks = false;
bool secretMatch = !_PACServerEnableSecret;

if (lines.Length < 2) // need at lease RequestLine + Host
{
return false;
}

// parse request line
string requestLine = lines[0];
// GET /pac?t=yyyyMMddHHmmssfff&secret=foobar HTTP/1.1
string[] requestItems = requestLine.Split(' ');
if (requestItems.Length == 3 && requestItems[0] == "GET")
{
int index = requestItems[1].IndexOf('?');
if (index < 0)
{
index = requestItems[1].Length;
}
string resourceString = requestItems[1].Substring(0, index).Remove(0, 1);
if (string.Equals(resourceString, RESOURCE_NAME, StringComparison.OrdinalIgnoreCase))
{
pathMatch = true;
if (!secretMatch)
{
string queryString = requestItems[1].Substring(index);
if (queryString.Contains(PacSecret))
{
secretMatch = true;
}
}
}
}

// parse request header
for (int i = 1; i < lines.Length; i++)
{
if (string.IsNullOrEmpty(lines[i]))
continue;

string[] kv = lines[i].Split(new char[] { ':' }, 2);
if (kv.Length == 2)
{
if (kv[0] == "Host")
{
if (kv[1].Trim() == (socket.LocalEndPoint as IPEndPoint)?.ToString())
{
hostMatch = true;
}
}
//else if (kv[0] == "User-Agent")
//{
// // we need to drop connections when changing servers
// if (kv[1].IndexOf("Chrome") >= 0)
// {
// useSocks = true;
// }
//}
}
}

if (hostMatch && pathMatch)
{
if (!secretMatch)
{
socket.Close(); // Close immediately
}
else
{
SendResponse(socket, useSocks);
}
return true;
}
return false;
}
catch (ArgumentException)
{
return false;
}
}

public void SendResponse(Socket socket, bool useSocks)
{
try
{
IPEndPoint localEndPoint = socket.LocalEndPoint as IPEndPoint ?? throw new ArgumentException("Invalid socket local endpoint.", nameof(socket));

string proxy = GetPACAddress(localEndPoint, useSocks);

string pacContent = $"var __PROXY__ = '{proxy}';\n" + _pacDaemon.GetPACContent();
string responseHead =
$@"HTTP/1.1 200 OK
Server: ShadowsocksPAC/{Assembly.GetExecutingAssembly().GetName().Version}
Content-Type: application/x-ns-proxy-autoconfig
Content-Length: { Encoding.UTF8.GetBytes(pacContent).Length}
Connection: Close

";
byte[] response = Encoding.UTF8.GetBytes(responseHead + pacContent);
socket.BeginSend(response, 0, response.Length, 0, new AsyncCallback(SendCallback), socket);
}
catch (Exception e)
{
this.Log().Error(e, "");
socket.Close();
}
}

private void SendCallback(IAsyncResult ar)
{
Socket? conn = ar.AsyncState as Socket;
try
{
conn?.Shutdown(SocketShutdown.Send);
}
catch
{
}
}

private string GetPACAddress(IPEndPoint localEndPoint, bool useSocks) => $"{(useSocks ? "SOCKS5" : "PROXY")} {localEndPoint};";
}
}