Transport layer for proxy handshake (#8)

pom.xml

@@ -7,7 +7,7 @@
 
     <groupId>com.microsoft.azure</groupId>
     <artifactId>qpid-proton-j-extensions</artifactId>
-    <version>1.0.0</version>
+    <version>1.1.0</version>
 
     <url>https://github.com/Azure/qpid-proton-j-extensions</url>
 

src/main/java/com/microsoft/azure/proton/transport/proxy/Proxy.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) Microsoft. All rights reserved.
+ * Licensed under the MIT license. See LICENSE file in the project root for full license information.
+ */
+
+package com.microsoft.azure.proton.transport.proxy;
+
+import java.util.Map;
+
+import org.apache.qpid.proton.engine.Transport;
+
+public interface Proxy {
+    enum ProxyState {
+        PN_PROXY_NOT_STARTED,
+        PN_PROXY_CONNECTING,
+        PN_PROXY_CONNECTED,
+        PN_PROXY_FAILED
+    }
+
+    void configure(
+            String host,
+            Map<String, String> headers,
+            ProxyHandler proxyHandler,
+            Transport underlyingTransport);
+}

src/main/java/com/microsoft/azure/proton/transport/proxy/ProxyHandler.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) Microsoft. All rights reserved.
+ * Licensed under the MIT license. See LICENSE file in the project root for full license information.
+ */
+
+package com.microsoft.azure.proton.transport.proxy;
+
+import java.nio.ByteBuffer;
+import java.util.Map;
+
+public interface ProxyHandler {
+
+    class ProxyResponseResult {
+        private Boolean isSuccess;
+        private String error;
+
+        public ProxyResponseResult(final Boolean isSuccess, final String error) {
+            this.isSuccess = isSuccess;
+            this.error = error;
+        }
+
+        public Boolean getIsSuccess() {
+            return isSuccess;
+        }
+
+        public String getError() {
+            return error;
+        }
+    }
+
+    String createProxyRequest(String hostName, Map<String, String> additionalHeaders);
+
+    ProxyResponseResult validateProxyResponse(ByteBuffer buffer);
+
+}

src/main/java/com/microsoft/azure/proton/transport/proxy/impl/ProxyHandlerImpl.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) Microsoft. All rights reserved.
+ * Licensed under the MIT license. See LICENSE file in the project root for full license information.
+ */
+
+package com.microsoft.azure.proton.transport.proxy.impl;
+
+import com.microsoft.azure.proton.transport.proxy.ProxyHandler;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+import java.util.Scanner;
+
+public class ProxyHandlerImpl implements ProxyHandler {
+
+    @Override
+    public String createProxyRequest(String hostName, Map<String, String> additionalHeaders) {
+        final String endOfLine = "\r\n";
+        final StringBuilder connectRequestBuilder = new StringBuilder();
+        connectRequestBuilder.append(
+                String.format(
+                        "CONNECT %1$s HTTP/1.1%2$sHost: %1$s%2$sConnection: Keep-Alive%2$s",
+                        hostName,
+                        endOfLine));
+        if (additionalHeaders != null) {
+            for (Map.Entry<String, String> entry: additionalHeaders.entrySet()) {
+                connectRequestBuilder.append(entry.getKey());
+                connectRequestBuilder.append(": ");
+                connectRequestBuilder.append(entry.getValue());
+                connectRequestBuilder.append(endOfLine);
+            }
+        }
+        connectRequestBuilder.append(endOfLine);
+        return connectRequestBuilder.toString();
+    }
+
+    @Override
+    public ProxyResponseResult validateProxyResponse(ByteBuffer buffer) {
+        int size = buffer.remaining();
+        String response = null;
+
+        if (size > 0) {
+            byte[] responseBytes = new byte[buffer.remaining()];
+            buffer.get(responseBytes);
+            response = new String(responseBytes, StandardCharsets.UTF_8);
+            final Scanner responseScanner = new Scanner(response);
+            if (responseScanner.hasNextLine()) {
+                final String firstLine = responseScanner.nextLine();
+                if (firstLine.toLowerCase().contains("http/1.1")
+                        && firstLine.contains("200")
+                        && firstLine.toLowerCase().contains("connection established")) {
+                    return new ProxyResponseResult(true, null);
+                }
+            }
+        }
+
+        return new ProxyResponseResult(false, response);
+    }
+}