Add a port-forwarding example. (#232)

* Add a port-forwarding example.

* Address comments.

examples/portforward/PortForward.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Net;
+using System.Net.Sockets;
+using System.Text;
+using System.Threading.Tasks;
+using k8s;
+using k8s.Models;
+
+namespace portforward
+{
+    internal class Portforward
+    {
+        private static async Task Main(string[] args)
+        {
+            var config = KubernetesClientConfiguration.BuildConfigFromConfigFile();
+            IKubernetes client = new Kubernetes(config);
+            Console.WriteLine("Starting port forward!");
+
+            var list = client.ListNamespacedPod("default");
+            var pod = list.Items[0];
+            await Forward(client, pod);
+        }
+
+        private async static Task Forward(IKubernetes client, V1Pod pod) {
+            // Note this is single-threaded, it won't handle concurrent requests well...
+            var webSocket = await client.WebSocketNamespacedPodPortForwardAsync(pod.Metadata.Name, "default", new int[] {80}, "v4.channel.k8s.io");
+            var demux = new StreamDemuxer(webSocket);
+            demux.Start();
+
+            var stream = demux.GetStream((byte?)0, (byte?)0);
+
+            IPAddress ipAddress = IPAddress.Loopback;
+            IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 8080);  
+            Socket listener = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp); 
+            listener.Bind(localEndPoint);  
+            listener.Listen(100);
+
+            Socket handler = null;
+
+            var accept = Task.Run(() => {
+                while (true) {
+                    handler = listener.Accept();
+                    var bytes = new byte[4096];
+                    while (true) {  
+                        int bytesRec = handler.Receive(bytes);
+                        stream.Write(bytes, 0, bytesRec);
+                        if (bytesRec == 0 || Encoding.ASCII.GetString(bytes,0,bytesRec).IndexOf("<EOF>") > -1) {  
+                            break;  
+                        }
+                    }
+                }
+            });
+
+            var copy = Task.Run(() => {
+                var buff = new byte[4096];
+                while (true) {
+                    var read = stream.Read(buff, 0, 4096);
+                    handler.Send(buff, read, 0);
+                }
+            });
+
+            await accept;
+            await copy;
+        }
+    }
+}

examples/portforward/portforward.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\KubernetesClient\KubernetesClient.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <LangVersion>7.1</LangVersion>
+  </PropertyGroup>
+
+</Project>