1. Added support for specifying Ethereum client versions when working…

… with Infura.

2. Updated network diagram.

src/main/java/org/web3j/protocol/http/HttpService.java

@@ -2,16 +2,20 @@
 
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.CompletableFuture;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.http.Header;
 import org.apache.http.HttpEntity;
 import org.apache.http.client.ClientProtocolException;
 import org.apache.http.client.ResponseHandler;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClients;
+import org.apache.http.message.BasicHeader;
 
 import org.web3j.protocol.Web3jService;
 import org.web3j.protocol.ObjectMapperFactory;
@@ -25,23 +29,26 @@ public class HttpService implements Web3jService {
 
     public static final String DEFAULT_URL = "http://localhost:8545/";
 
-    private CloseableHttpClient httpClient =
-            HttpClients.custom().setConnectionManagerShared(true).build();
+    private CloseableHttpClient httpClient;
 
-    private ObjectMapper objectMapper = ObjectMapperFactory.getObjectMapper();
+    private final ObjectMapper objectMapper = ObjectMapperFactory.getObjectMapper();
 
     private final String url;
 
-    public HttpService() {
-        this.url = DEFAULT_URL;
+    public HttpService(String url, CloseableHttpClient httpClient) {
+        this.url = url;
+        this.httpClient = httpClient;
     }
 
     public HttpService(String url) {
-        this.url = url;
+        this(url, HttpClients.custom().setConnectionManagerShared(true).build());
     }
 
-    public HttpService(String url, CloseableHttpClient httpClient) {
-        this.url = url;
+    public HttpService() {
+        this(DEFAULT_URL);
+    }
+
+    protected void setHttpClient(CloseableHttpClient httpClient) {
         this.httpClient = httpClient;
     }
 
@@ -53,7 +60,8 @@ public <T extends Response> T send(
 
         HttpPost httpPost = new HttpPost(this.url);
         httpPost.setEntity(new ByteArrayEntity(payload));
-        httpPost.setHeader("Content-Type", "application/json; charset=UTF-8");
+        Header[] headers = buildHeaders();
+        httpPost.setHeaders(headers);
 
         ResponseHandler<T> responseHandler = getResponseHandler(responseType);
         try {
@@ -63,6 +71,15 @@ public <T extends Response> T send(
         }
     }
 
+    private Header[] buildHeaders() {
+        List<Header> headers = new ArrayList<>();
+        headers.add(new BasicHeader("Content-Type", "application/json; charset=UTF-8"));
+        addHeaders(headers);
+        return headers.toArray(new Header[0]);
+    }
+
+    protected void addHeaders(List<Header> headers) { }
+
     public <T> ResponseHandler<T> getResponseHandler(Class<T> type) {
         return response -> {
             int status = response.getStatusLine().getStatusCode();

src/main/java/org/web3j/protocol/infura/CertificateManager.java

@@ -0,0 +1,150 @@
+package org.web3j.protocol.infura;
+
+import javax.net.ssl.*;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.security.*;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+
+/**
+ * Certificate manager to simplify working with TLS endpoints.
+ */
+public class CertificateManager {
+
+    static File buildKeyStore(String url, char[] keyStorePassword) {
+        KeyStore keyStore;
+        try {
+            keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
+            keyStore.load(null, keyStorePassword);
+
+            CertificateChainTrustManager certificateChainTrustManager =
+                    createCertificateChainTrustManager(keyStore);
+            URI endpoint = new URI(url);
+            SSLSocket sslSocket = createSslSocket(endpoint, certificateChainTrustManager);
+
+            if (!isTrustedEndPoint(sslSocket)) {
+                X509Certificate[] x509Certificates = certificateChainTrustManager.x509Certificates;
+                if (x509Certificates == null) {
+                    throw new RuntimeException("Unable to obtain x509 certificate from server");
+                }
+
+                for (int i = 0; i < x509Certificates.length; i++) {
+                    keyStore.setCertificateEntry(endpoint.getHost() + i, x509Certificates[i]);
+                }
+            }
+
+            SecureRandom random = new SecureRandom();
+            File keyFile = File.createTempFile("web3j-", "" + random.nextLong());
+
+            FileOutputStream fileOutputStream = new FileOutputStream(keyFile);
+            keyStore.store(fileOutputStream, keyStorePassword);
+            fileOutputStream.close();
+
+            deleteFileOnShutdown(keyFile);
+
+            return keyFile;
+
+        } catch (KeyStoreException e) {
+            throw new RuntimeException(e);
+        } catch (CertificateException e) {
+            throw new RuntimeException(e);
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        } catch (KeyManagementException e) {
+            throw new RuntimeException(e);
+        } catch (URISyntaxException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private static CertificateChainTrustManager createCertificateChainTrustManager(
+            KeyStore keyStore) throws NoSuchAlgorithmException, KeyStoreException {
+
+        TrustManagerFactory trustManagerFactory =
+                TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
+        trustManagerFactory.init(keyStore);
+        X509TrustManager defaultTrustManager =
+                (X509TrustManager) trustManagerFactory.getTrustManagers()[0];
+        return new CertificateChainTrustManager(defaultTrustManager);
+    }
+
+    private static SSLSocket createSslSocket(
+            URI endpoint, CertificateChainTrustManager certificateChainTrustManager)
+            throws NoSuchAlgorithmException, KeyManagementException, IOException,
+            URISyntaxException, KeyStoreException {
+
+        SSLContext context = SSLContext.getInstance("TLS");
+        context.init(null, new TrustManager[]{certificateChainTrustManager}, null);
+        SSLSocketFactory factory = context.getSocketFactory();
+
+        SSLSocket sslSocket = (SSLSocket) factory.createSocket(
+                endpoint.getHost(), 443);
+        sslSocket.setSoTimeout(10000);
+
+        return sslSocket;
+    }
+
+    private static boolean isTrustedEndPoint(SSLSocket socket) throws IOException {
+        try {
+            socket.startHandshake();
+            socket.close();
+            return true;
+        } catch (SSLException e) {
+            return false;
+        }
+    }
+
+    private static void deleteFileOnShutdown(File file) {
+        Runtime.getRuntime().addShutdownHook(new Thread() {
+            public void run() {
+                try {
+                    deleteTempFile(file);
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        });
+    }
+
+    private static void deleteTempFile(File file) throws IOException {
+        if (file.exists() && !file.delete()) {
+            throw new RuntimeException("Unable to remove file: " + file.getCanonicalPath());
+        }
+    }
+
+    /**
+     * Based on:
+     * http://blogs.sun.com/andreas/resource/InstallCert.java
+     */
+    private static class CertificateChainTrustManager implements X509TrustManager {
+
+        private final X509TrustManager x509TrustManager;
+        private X509Certificate[] x509Certificates;
+
+        CertificateChainTrustManager(X509TrustManager x509TrustManager) {
+            this.x509TrustManager = x509TrustManager;
+        }
+
+        public X509Certificate[] getAcceptedIssuers() {
+            // Called by Java 7+ see http://infposs.blogspot.kr/2013/06/installcert-and-java-7.html
+            return new X509Certificate[0];
+        }
+
+        public void checkClientTrusted(X509Certificate[] chain, String authType)
+                throws CertificateException {
+            throw new UnsupportedOperationException();
+        }
+
+        public void checkServerTrusted(X509Certificate[] chain, String authType)
+                throws CertificateException {
+            this.x509Certificates = chain;
+            x509TrustManager.checkServerTrusted(chain, authType);
+        }
+    }
+}

src/main/java/org/web3j/protocol/infura/InfuraHttpService.java

@@ -0,0 +1,100 @@
+package org.web3j.protocol.infura;
+
+import javax.net.ssl.*;
+import java.io.File;
+import java.io.IOException;
+import java.security.*;
+import java.security.cert.CertificateException;
+import java.util.List;
+
+import org.apache.http.Header;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClients;
+import org.apache.http.message.BasicHeader;
+import org.apache.http.ssl.SSLContexts;
+
+import org.web3j.protocol.http.HttpService;
+
+/**
+ * HttpService for working with <a href="https://infura.io/">Infura</a> clients.
+ */
+public class InfuraHttpService extends HttpService {
+
+    private static final String INFURA_ETHEREUM_PREFERRED_CLIENT =
+            "Infura-Ethereum-Preferred-Client";
+
+    private static final char[] TEMP_KEY_STORE_PASSWORD = "web3j runtime cert store".toCharArray();
+
+    private final Header clientVersionHeader;
+
+    public InfuraHttpService(String url, String clientVersion, boolean required) {
+        super(url);
+        setHttpClient(createTrustTlsHttpClient(url));
+        clientVersionHeader = buildHeader(clientVersion, required);
+    }
+
+    public InfuraHttpService(String url, String clientVersion) {
+        this(url, clientVersion, true);
+    }
+
+    @Override
+    protected void addHeaders(List<Header> headers) {
+        if (clientVersionHeader != null) {
+            headers.add(clientVersionHeader);
+        }
+    }
+
+    static Header buildHeader(String clientVersion, boolean required) {
+        if (clientVersion == null || clientVersion.equals("")) {
+            return null;
+        }
+
+        if (required) {
+            return new BasicHeader(INFURA_ETHEREUM_PREFERRED_CLIENT, clientVersion);
+        } else {
+            return new BasicHeader(
+                    INFURA_ETHEREUM_PREFERRED_CLIENT, clientVersion + "; required=false");
+        }
+    }
+
+    /**
+     * Create an {@link InfuraHttpService} instance with a local keystore that implicitly trusts
+     * the provided endpoint.
+     *
+     * This is achieved by creating a local temporary keystore file which we add the certificate
+     * of the endpoint to upon application startup.
+     *
+     * @param url we wish to connect to
+     * @return the file containing the keystore
+     * @throws UnrecoverableKeyException if keystore file cannot be loaded
+     * @throws NoSuchAlgorithmException if keystore file cannot be loaded
+     * @throws KeyStoreException if keystore file cannot be loaded
+     * @throws KeyManagementException if keystore file cannot be loaded
+     */
+    private static CloseableHttpClient createTrustTlsHttpClient(String url) {
+
+        File keyFile = CertificateManager.buildKeyStore(url, TEMP_KEY_STORE_PASSWORD);
+
+        SSLContext sslContext;
+        try {
+            sslContext = SSLContexts.custom()
+                    .loadTrustMaterial(keyFile, TEMP_KEY_STORE_PASSWORD)
+                    .build();
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        } catch (KeyManagementException e) {
+            throw new RuntimeException(e);
+        } catch (KeyStoreException e) {
+            throw new RuntimeException(e);
+        } catch (CertificateException e) {
+            throw new RuntimeException(e);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        return HttpClients.custom()
+                .setConnectionManagerShared(true)
+                .setSSLContext(sslContext)
+                .build();
+    }
+}

src/test/java/org/web3j/protocol/infura/InfuraHttpServiceTest.java

@@ -0,0 +1,29 @@
+package org.web3j.protocol.infura;
+
+
+import org.apache.http.message.BasicHeader;
+import org.junit.Test;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
+import static org.web3j.protocol.infura.InfuraHttpService.buildHeader;
+
+public class InfuraHttpServiceTest {
+
+    @Test
+    public void testBuildHeader() {
+        assertNull(buildHeader("", false));
+        assertNull(buildHeader(null, false));
+
+        assertThat(buildHeader("geth 1.4.19", true).toString(),
+                is(new BasicHeader(
+                        "Infura-Ethereum-Preferred-Client",
+                        "geth 1.4.19").toString()));
+
+        assertThat(buildHeader("geth 1.4.19", false).toString(),
+                is(new BasicHeader(
+                        "Infura-Ethereum-Preferred-Client",
+                        "geth 1.4.19; required=false").toString()));
+    }
+}