Proxy,Tests: add TorProxy

This commit adds a helper class that provides an HTTP proxy for
easy usage of NOnion alongside things like HttpClient that don't
support communicating over custom streams.

NOnion.Tests/TorProxyTests.cs

@@ -0,0 +1,115 @@
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+using Newtonsoft.Json;
+using NUnit.Framework;
+
+using NOnion.Proxy;
+
+namespace NOnion.Tests
+{
+    internal class TorProxyTests
+    {
+        private const int MaximumRetry = 3;
+
+        private class TorProjectCheckResult
+        {
+            [JsonProperty("IsTor")]
+            internal bool IsTor { get; set; }
+
+            [JsonProperty("IP")]
+            internal string IP { get; set; }
+        }
+
+        [Test]
+        [Retry(MaximumRetry)]
+        public void CanProxyTorProjectExitNodeCheck()
+        {
+            Assert.DoesNotThrowAsync(ProxyTorProjectExitNodeCheck);
+        }
+
+        private async Task ProxyTorProjectExitNodeCheck()
+        {
+            using (await TorProxy.StartAsync(IPAddress.Loopback, 20000))
+            {
+                var handler = new HttpClientHandler
+                {
+                    Proxy = new WebProxy("http://localhost:20000")
+                };
+
+                var client = new HttpClient(handler);
+                var resultStr = await client.GetStringAsync("https://check.torproject.org/api/ip");
+                var result = JsonConvert.DeserializeObject<TorProjectCheckResult>(resultStr);
+                Assert.IsTrue(result.IsTor);
+            }
+        }
+
+        [Test]
+        [Retry(MaximumRetry)]
+        public void CanProxyHttps()
+        {
+            Assert.DoesNotThrowAsync(ProxyHttps);
+        }
+
+        private async Task ProxyHttps()
+        {
+            using (await TorProxy.StartAsync(IPAddress.Loopback, 20000))
+            {
+                var handler = new HttpClientHandler
+                {
+                    Proxy = new WebProxy("http://localhost:20000")
+                };
+
+                var client = new HttpClient(handler);
+                var googleResponse = await client.GetAsync("https://google.com");
+                Assert.That(googleResponse.StatusCode > 0);
+            }
+        }
+
+        [Test]
+        [Retry(MaximumRetry)]
+        public void CanProxyHttp()
+        {
+            Assert.DoesNotThrowAsync(ProxyHttp);
+        }
+
+        private async Task ProxyHttp()
+        {
+            using (await TorProxy.StartAsync(IPAddress.Loopback, 20000))
+            {
+                var handler = new HttpClientHandler
+                {
+                    Proxy = new WebProxy("http://localhost:20000")
+                };
+
+                var client = new HttpClient(handler);
+                var googleResponse = await client.GetAsync("http://google.com/search?q=Http+Test");
+                Assert.That(googleResponse.StatusCode > 0);
+            }
+        }
+
+        [Test]
+        [Retry(MaximumRetry)]
+        public void CanProxyHiddenService()
+        {
+            Assert.DoesNotThrowAsync(ProxyHiddenService);
+        }
+
+        private async Task ProxyHiddenService()
+        {
+            using (await TorProxy.StartAsync(IPAddress.Loopback, 20000))
+            {
+                var handler = new HttpClientHandler
+                {
+                    Proxy = new WebProxy("http://localhost:20000"),
+                    ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) => true
+                };
+
+                var client = new HttpClient(handler);
+                var facebookResponse = await client.GetAsync("https://facebookwkhpilnemxj7asaniu7vnjjbiltxjqhye3mhbshg7kx5tfyd.onion");
+                Assert.That(facebookResponse.StatusCode > 0);
+            }
+        }
+    }
+}

NOnion/NOnion.fsproj

@@ -89,6 +89,7 @@
     <Compile Include="Client\TorClient.fs" />
     <Compile Include="Services\TorServiceHost.fs" />
     <Compile Include="Services\TorServiceClient.fs" />
+    <Compile Include="Proxy\TorProxy.fs" />
   </ItemGroup>
 
   <ItemGroup>

NOnion/Network/TorCircuit.fs

@@ -1072,6 +1072,13 @@ and TorCircuit
             failwith
                 "Should not happen: can't get circuitId for non-initialized circuit."
 
+    member __.IsActive =
+        match circuitState with
+        | Ready _
+        | ReadyAsIntroductionPoint _
+        | ReadyAsRendezvousPoint _ -> true
+        | _ -> false
+
     member __.GetLastNode() =
         async {
             let! lastNodeResult =

NOnion/Proxy/TorProxy.fs

@@ -0,0 +1,246 @@
+namespace NOnion.Proxy
+
+open FSharpx.Collections
+open System
+open System.IO
+open System.Net
+open System.Net.Sockets
+open System.Text
+open System.Threading
+
+open NOnion
+open NOnion.Client
+open NOnion.Network
+open NOnion.Services
+
+type TorProxy private (listener: TcpListener, torClient: TorClient) =
+    let mutable lastActiveCircuitOpt: Option<TorCircuit> = None
+
+    let handleConnection(client: TcpClient) =
+        async {
+            let! cancelToken = Async.CancellationToken
+            cancelToken.ThrowIfCancellationRequested()
+
+            let stream = client.GetStream()
+
+            let readHeaders() =
+                async {
+                    let stringBuilder = StringBuilder()
+                    // minimum request 16 bytes: GET / HTTP/1.1\r\n\r\n
+                    let preReadLen = 18
+                    let! buffer = stream.AsyncRead preReadLen
+
+                    buffer
+                    |> Encoding.ASCII.GetString
+                    |> stringBuilder.Append
+                    |> ignore<StringBuilder>
+
+                    let rec innerReadRest() =
+                        async {
+                            if stringBuilder.ToString().EndsWith("\r\n\r\n") then
+                                return ()
+                            else
+                                let! newByte = stream.AsyncRead 1
+
+                                newByte
+                                |> Encoding.ASCII.GetString
+                                |> stringBuilder.Append
+                                |> ignore<StringBuilder>
+
+                                return! innerReadRest()
+                        }
+
+                    do! innerReadRest()
+
+                    return stringBuilder.ToString()
+                }
+
+            let! headers = readHeaders()
+
+            let headerLines =
+                headers.Split(
+                    [| "\r\n" |],
+                    StringSplitOptions.RemoveEmptyEntries
+                )
+
+            match Seq.tryHeadTail headerLines with
+            | Some(firstLine, restOfHeaders) ->
+                let firstLineParts = firstLine.Split(' ')
+
+                let method = firstLineParts.[0]
+                let url = firstLineParts.[1]
+                let protocolVersion = firstLineParts.[2]
+
+                if protocolVersion <> "HTTP/1.1" then
+                    return failwith "TorProxy: protocol version mismatch"
+
+                let rec copySourceToDestination
+                    (source: Stream)
+                    (dest: Stream)
+                    =
+                    async {
+                        do! source.CopyToAsync dest |> Async.AwaitTask
+
+                        // CopyToAsync returns when source is closed so we can close dest
+                        dest.Close()
+                    }
+
+                let createStreamToDestination(parsedUrl: Uri) =
+                    async {
+                        if parsedUrl.DnsSafeHost.EndsWith(".onion") then
+                            let! client =
+                                TorServiceClient.Connect
+                                    torClient
+                                    (sprintf
+                                        "%s:%i"
+                                        parsedUrl.DnsSafeHost
+                                        parsedUrl.Port)
+
+                            return! client.GetStream()
+                        else
+                            let! circuit =
+                                match lastActiveCircuitOpt with
+                                | Some lastActiveCircuit when
+                                    lastActiveCircuit.IsActive
+                                    ->
+                                    async {
+                                        TorLogger.Log
+                                            "TorProxy: we had active circuit, no need to recreate"
+
+                                        return lastActiveCircuit
+                                    }
+                                | _ ->
+                                    async {
+                                        TorLogger.Log
+                                            "TorProxy: we didn't have an active circuit, recreating..."
+
+                                        let! circuit =
+                                            torClient.AsyncCreateCircuit
+                                                3
+                                                CircuitPurpose.Exit
+                                                None
+
+                                        lastActiveCircuitOpt <- Some circuit
+                                        return circuit
+                                    }
+
+                            let torStream = new TorStream(circuit)
+
+                            do!
+                                torStream.ConnectToOutside
+                                    parsedUrl.DnsSafeHost
+                                    parsedUrl.Port
+                                |> Async.Ignore
+
+                            return torStream
+                    }
+
+                if method <> "CONNECT" then
+                    let parsedUrl = Uri url
+
+                    use! torStream = createStreamToDestination parsedUrl
+
+                    let firstLineToRetransmit =
+                        sprintf
+                            "%s %s HTTP/1.1\r\n"
+                            method
+                            parsedUrl.PathAndQuery
+
+                    let headersToForwardLines =
+                        restOfHeaders
+                        |> Seq.filter(fun header ->
+                            not(header.StartsWith "Proxy-")
+                        )
+                        |> Seq.map(fun header -> sprintf "%s\r\n" header)
+
+                    let headersToForward =
+                        String.Join(String.Empty, headersToForwardLines)
+
+                    do!
+                        Encoding.ASCII.GetBytes firstLineToRetransmit
+                        |> torStream.AsyncWrite
+
+                    do!
+                        Encoding.ASCII.GetBytes headersToForward
+                        |> torStream.AsyncWrite
+
+                    do! Encoding.ASCII.GetBytes "\r\n" |> torStream.AsyncWrite
+
+                    return!
+                        [
+                            copySourceToDestination torStream stream
+                            copySourceToDestination stream torStream
+                        ]
+                        |> Async.Parallel
+                        |> Async.Ignore
+                else
+                    let parsedUrl = Uri <| sprintf "http://%s" url
+
+                    use! torStream = createStreamToDestination parsedUrl
+
+                    let connectResponse =
+                        "HTTP/1.1 200 Connection Established\r\nConnection: close\r\n\r\n"
+
+                    do!
+                        Encoding.ASCII.GetBytes connectResponse
+                        |> stream.AsyncWrite
+
+                    return!
+                        [
+                            copySourceToDestination torStream stream
+                            copySourceToDestination stream torStream
+                        ]
+                        |> Async.Parallel
+                        |> Async.Ignore
+            | None ->
+                return failwith "TorProxy: incomplete http header detected"
+
+        }
+
+    let rec acceptConnections() =
+        async {
+            let! cancelToken = Async.CancellationToken
+            cancelToken.ThrowIfCancellationRequested()
+
+            let! client = listener.AcceptTcpClientAsync() |> Async.AwaitTask
+
+            Async.Start(handleConnection client, cancelToken)
+
+            return! acceptConnections()
+        }
+
+    let shutdownToken = new CancellationTokenSource()
+
+    static member Start (localAddress: IPAddress) (port: int) =
+        async {
+            let! client = TorClient.AsyncBootstrapWithEmbeddedList None
+            let listener = TcpListener(localAddress, port)
+            let proxy = new TorProxy(listener, client)
+            proxy.StartListening()
+            return proxy
+        }
+
+    static member StartAsync(localAddress: IPAddress, port: int) =
+        TorProxy.Start localAddress port |> Async.StartAsTask
+
+    member private self.StartListening() =
+        listener.Start()
+
+        Async.Start(acceptConnections(), shutdownToken.Token)
+
+    member __.GetNewIdentity() =
+        async {
+            let! newCircuit =
+                torClient.AsyncCreateCircuit 3 CircuitPurpose.Exit None
+
+            lastActiveCircuitOpt <- Some newCircuit
+        }
+
+    member self.GetNewIdentityAsync() =
+        self.GetNewIdentity() |> Async.StartAsTask
+
+    interface IDisposable with
+        member __.Dispose() =
+            shutdownToken.Cancel()
+            listener.Stop()
+            (torClient :> IDisposable).Dispose()