Wire up SSL client authentication for OpenSSL/Android through the net/ stack

chrome/android/java/src/org/chromium/chrome/browser/SSLClientCertificateRequest.java

Index: chrome/android/java/src/org/chromium/chrome/browser/SSLClientCertificateRequest.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/SSLClientCertificateRequest.java b/chrome/android/java/src/org/chromium/chrome/browser/SSLClientCertificateRequest.java
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+++ b/chrome/android/java/src/org/chromium/chrome/browser/SSLClientCertificateRequest.java
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+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser;
+
+import java.security.cert.CertificateEncodingException;
+import java.security.cert.X509Certificate;
+import java.security.Principal;
+import java.security.PrivateKey;
+import javax.security.auth.x500.X500Principal;
+
+import android.app.Activity;
+import android.content.Context;
+import android.os.AsyncTask;
+import android.security.KeyChain;
+import android.security.KeyChainAliasCallback;
+import android.security.KeyChainException;
+import android.util.Log;
+
+import org.chromium.base.ActivityStatus;
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import org.chromium.base.ThreadUtils;
+
+@JNINamespace("browser")
+public class SSLClientCertificateRequest extends AsyncTask<Void, Void, Void>
+        implements KeyChainAliasCallback {
+
+    static final String TAG = "SSLClientCertificateRequest";
+
+    // ClientCertRequest models an asynchronous client certificate request
+    // on the Dalvik side. There is a matching C++ ClientCertRequest
+    // class that has _slightly_ different lifecycles (e.g. if a Tab
+    // is closed while an asynchronous request is still pending, the native
+    // C++ class will be deleted, but the Java one must persist until the
+    // system sends its answer to the activity).
+    //
+    // In theory, it is possible to only have one Java class to model
+    // each request, but this makes the native interface more complicated
+    // to use.
+    //
+    // Each request must be started from the UI thread, and the system
+    // will answer the KeyChain.choosePrivateKeyAlias() call with a
+    // private key alias string, which can be used to call
+    // KeyChain.getCertificateChain() and KeyChain.getPrivateKey(),
+    // however these functions are blocking and can't be called on the
+    // UI thread.
+    //
+    // To solve this, start an AsyncTask when an alias is received.
+    // it will retrieve the certificate chain and private key in the
+    // background, then later send the result back to the UI thread.
+    //
+    private final int mNativePtr;
+    private String mAlias;
+    private byte[][] mEncodedChain;
+    private PrivateKey mPrivateKey;
+
+    public SSLClientCertificateRequest(int nativePtr) {
+        mNativePtr = nativePtr;
+        mAlias = null;
+        mEncodedChain = null;
+        mPrivateKey = null;
+    }
+
+    // KeyChainAliasCallback implementation
+    @Override
+    public void alias(String alias) {
+        if (alias == null) {
+            // No certificate was selected.
+            onPostExecute(null);
+        } else {
+            mAlias = alias;
+            // Launch background thread.
+            execute();
+        }
+    }
+
+    @Override
+    protected Void doInBackground(Void... params) {
+        // Executed in a background thread, can call blocking APIs.
+        X509Certificate[] chain = null;
+        PrivateKey key = null;
+        Context context = ActivityStatus.getActivity().getApplicationContext();
+        try {
+            key = KeyChain.getPrivateKey(context, mAlias);
+            chain = KeyChain.getCertificateChain(context, mAlias);
+        } catch (KeyChainException e) {
+            Log.w(TAG, "KeyChainException when looking for '" + mAlias + "' certificate");
+            return null;
+        } catch (InterruptedException e) {
+            Log.w(TAG, "InterruptedException when looking for '" + mAlias + "'certificate");
+            return null;
+        }
+
+        if (key == null || chain == null || chain.length == 0) {
+            Log.w(TAG, "Empty client certificate chain?");
+            return null;
+        }
+
+        // Get the encoded certificate chain.
+        byte[][] encoded_chain = new byte[chain.length][];
+        try {
+            for (int i = 0; i < chain.length; ++i) {
+                encoded_chain[i] = chain[i].getEncoded();
+            }
+        } catch (CertificateEncodingException e) {
+            Log.w(TAG, "Could not retrieve encoded certificate chain: " + e);
+            return null;
+        }
+
+        mEncodedChain = encoded_chain;
+        mPrivateKey = key;
+        return null;
+    }
+
+    @Override
+    protected void onPostExecute(Void result) {
+        // Back to the UI thread.
+        nativeOnRequestCompletion(mNativePtr, mAlias, mEncodedChain, mPrivateKey);
+    }
+
+
+    // Called to pass request results to native side.
+    private native void nativeOnRequestCompletion(int nativeSSLClientCertRequest,
+                                                  String alias,
+                                                  byte[][] certChain,
+                                                  PrivateKey privateKey);
+
+    /**
+     * Create a new asynchronous request to select a client certificate.
+     *
+     * @param request_id The unique numerical id for the request.
+     * @param key_types The list of supported key exchange types.
+     * @param encoded_principals The list of CA DistinguishedNames.
+     * @param host_name The server host name is available (empty otherwise).
+     * @param port The server port if available (0 otherwise).
+     * @return true on success.
+     */
+    @CalledByNative
+    static public boolean selectClientCertificate(int nativePtr,
+                                                  String[] key_types,
+                                                  byte[][] encoded_principals,
+                                                  String host_name,
+                                                  int port,
+                                                  String alias_hint) {
+        ThreadUtils.assertOnUiThread();
+
+        Activity activity = ActivityStatus.getActivity();
+        if (activity == null) {
+            Log.w(TAG, "No active Chromium main activity!?");
+            return false;
+        }
+
+        // Build the list of principals from encoded versions.
+        Principal[] principals = null;
+        if (encoded_principals.length > 0) {
+            principals = new X500Principal[encoded_principals.length];
+            try {
+                for (int n = 0; n < encoded_principals.length; n++) {
+                    principals[n] = new X500Principal(encoded_principals[n]);
+                }
+            } catch (Exception e) {
+                // Bail on error.
+                Log.w(TAG, "Exception while decoding issuers list: " + e);
+                return false;
+            }
+        }
+
+        // All good, create new request, add it to our list and launch
+        // the certificate selection activity.
+        SSLClientCertificateRequest request = new SSLClientCertificateRequest(nativePtr);
+
+        KeyChain.choosePrivateKeyAlias(activity, request, key_types,
+                                      principals, host_name, port,
+                                      alias_hint);
+        return true;
+    }
+
+}