Set WebView proxy to 0.0.0.0 when possible (#2539)

* Set WebView proxy to 0.0.0.0 when possible

* add DcHttpResponse to wrapper

* use new DcHttpResponse to show images in email-html-view

* null-encoding is fine for WebResourceResponse()

---------

Co-authored-by: B. Petersen <r10s@b44t.com>

jni/dc_wrapper.c

@@ -1021,6 +1021,15 @@ JNIEXPORT jlong Java_com_b44t_messenger_DcContext_getProviderFromEmailWithDnsCPt
 }
 
 
+JNIEXPORT jlong Java_com_b44t_messenger_DcContext_getHttpResponseCPtr(JNIEnv *env, jobject obj, jstring url)
+{
+    CHAR_REF(url);
+        jlong ret = (jlong)dc_get_http_response(get_dc_context(env, obj), urlPtr);
+    CHAR_UNREF(url);
+    return ret;
+}
+
+
 /*******************************************************************************
  * DcEventEmitter
  ******************************************************************************/
@@ -2068,3 +2077,63 @@ JNIEXPORT jstring Java_com_b44t_messenger_DcProvider_getOverviewPage(JNIEnv *env
     return ret;
 }
 
+
+/*******************************************************************************
+ * DcHttpResponse
+ ******************************************************************************/
+
+
+static dc_http_response_t* get_dc_http_response(JNIEnv *env, jobject obj)
+{
+    static jfieldID fid = 0;
+    if (fid==0) {
+        jclass cls = (*env)->GetObjectClass(env, obj);
+        fid = (*env)->GetFieldID(env, cls, "httpResponseCPtr", "J" /*Signature, J=long*/);
+    }
+    if (fid) {
+        return (dc_http_response_t*)(*env)->GetLongField(env, obj, fid);
+    }
+    return NULL;
+}
+
+
+JNIEXPORT void Java_com_b44t_messenger_DcHttpResponse_unrefHttpResponseCPtr(JNIEnv *env, jobject obj)
+{
+    dc_http_response_unref(get_dc_http_response(env, obj));
+}
+
+
+JNIEXPORT jstring Java_com_b44t_messenger_DcHttpResponse_getMimetype(JNIEnv *env, jobject obj)
+{
+    char* temp = dc_http_response_get_mimetype(get_dc_http_response(env, obj));
+        jstring ret = NULL;
+        if (temp) {
+            ret = JSTRING_NEW(temp);
+        }
+    dc_str_unref(temp);
+    return ret;
+}
+
+
+JNIEXPORT jstring Java_com_b44t_messenger_DcHttpResponse_getEncoding(JNIEnv *env, jobject obj)
+{
+    char* temp = dc_http_response_get_encoding(get_dc_http_response(env, obj));
+        jstring ret = NULL;
+        if (temp) {
+            ret = JSTRING_NEW(temp);
+        }
+    dc_str_unref(temp);
+    return ret;
+}
+
+
+JNIEXPORT jbyteArray Java_com_b44t_messenger_DcHttpResponse_getBlob(JNIEnv *env, jobject obj)
+{
+    jbyteArray ret = NULL;
+    dc_http_response_t* http_response = get_dc_http_response(env, obj);
+    size_t ptr_size = dc_http_response_get_size(http_response);
+    uint8_t* ptr = dc_http_response_get_blob(http_response);
+        ret = ptr2jbyteArray(env, ptr, ptr_size);
+    dc_str_unref((char*)ptr);
+    return ret;
+}

src/com/b44t/messenger/DcContext.java

@@ -216,6 +216,7 @@ public class DcContext {
     public DcArray             getLocations         (int chat_id, int contact_id, long timestamp_start, long timestamp_end) { return new DcArray(getLocationsCPtr(chat_id, contact_id, timestamp_start, timestamp_end)); }
     public native void         deleteAllLocations   ();
     public DcProvider          getProviderFromEmailWithDns (String email) { long cptr = getProviderFromEmailWithDnsCPtr(email); return cptr!=0 ? new DcProvider(cptr) : null; }
+    public DcHttpResponse      getHttpResponse      (String url) { long cptr = getHttpResponseCPtr(url); return cptr!=0 ? new DcHttpResponse(cptr) : null; }
 
     public String getNameNAddr() {
       String displayname = getConfig("displayname");
@@ -255,4 +256,5 @@ public class DcContext {
     private native long checkQrCPtr      (String qr);
     private native long getProviderFromEmailWithDnsCPtr  (String addr);
     private native long newBackupProviderCPtr();
+    private native long getHttpResponseCPtr(String url);
 }

src/com/b44t/messenger/DcHttpResponse.java

@@ -0,0 +1,22 @@
+package com.b44t.messenger;
+
+public class DcHttpResponse {
+
+    public DcHttpResponse(long httpResponseCPtr) {
+        this.httpResponseCPtr = httpResponseCPtr;
+    }
+
+    @Override protected void finalize() throws Throwable {
+        super.finalize();
+        unrefHttpResponseCPtr();
+        httpResponseCPtr = 0;
+    }
+
+    public native String    getMimetype     ();
+    public native String    getEncoding     ();
+    public native byte[]    getBlob         ();
+
+    // working with raw c-data
+    private long        httpResponseCPtr;    // CAVE: the name is referenced in the JNI
+    private native void unrefHttpResponseCPtr();
+}

src/org/thoughtcrime/securesms/FullMsgActivity.java

@@ -3,17 +3,20 @@ package org.thoughtcrime.securesms;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
+import android.webkit.WebResourceResponse;
 import android.webkit.WebSettings;
 
 import androidx.appcompat.app.AlertDialog;
 
 import com.b44t.messenger.DcContext;
+import com.b44t.messenger.DcHttpResponse;
 
 import org.thoughtcrime.securesms.connect.DcHelper;
 import org.thoughtcrime.securesms.util.DynamicTheme;
 import org.thoughtcrime.securesms.util.Prefs;
 import org.thoughtcrime.securesms.util.Util;
 
+import java.io.ByteArrayInputStream;
 import java.lang.ref.WeakReference;
 
 public class FullMsgActivity extends WebViewActivity
@@ -164,4 +167,27 @@ public class FullMsgActivity extends WebViewActivity
     webView.getSettings().setBlockNetworkLoads(!this.loadRemoteContent);
     webView.reload();
   }
+
+  @Override
+  protected WebResourceResponse interceptRequest(String url) {
+    WebResourceResponse res = null;
+    try {
+      if (url == null) {
+        throw new Exception("no url specified");
+      }
+      DcHttpResponse httpResponse = dcContext.getHttpResponse(url);
+      if (httpResponse == null) {
+        throw new Exception(dcContext.getLastError());
+      }
+      String mimeType = httpResponse.getMimetype();
+      if (mimeType == null) {
+        mimeType = "application/octet-stream";
+      }
+      res = new WebResourceResponse(mimeType, httpResponse.getEncoding(), new ByteArrayInputStream(httpResponse.getBlob()));
+    } catch (Exception e) {
+      e.printStackTrace();
+      res = new WebResourceResponse("text/plain", "UTF-8", new ByteArrayInputStream(("Error: " + e.getMessage()).getBytes()));
+    }
+    return res;
+  }
 }

src/org/thoughtcrime/securesms/WebViewActivity.java

@@ -21,10 +21,14 @@ import androidx.annotation.RequiresApi;
 import androidx.appcompat.widget.SearchView;
 import androidx.webkit.WebSettingsCompat;
 import androidx.webkit.WebViewFeature;
+import androidx.webkit.ProxyController;
+import androidx.webkit.ProxyConfig;
 
 import org.thoughtcrime.securesms.util.DynamicLanguage;
 import org.thoughtcrime.securesms.util.DynamicTheme;
 
+import java.util.concurrent.Executor;
+
 public class WebViewActivity extends PassphraseRequiredActionBarActivity
                                implements SearchView.OnQueryTextListener,
                                           WebView.FindListener
@@ -39,6 +43,29 @@ public class WebViewActivity extends PassphraseRequiredActionBarActivity
   protected void onPreCreate() {
     dynamicTheme.onCreate(this);
     dynamicLanguage.onCreate(this);
+
+    if (WebViewFeature.isFeatureSupported(WebViewFeature.PROXY_OVERRIDE)) {
+      // Set proxy to non-routable address.
+      ProxyConfig proxyConfig = new ProxyConfig.Builder()
+          .removeImplicitRules()
+          .addProxyRule("0.0.0.0")
+          .build();
+      Executor executor = new Executor() {
+        @Override
+        public void execute(Runnable command) {
+          command.run();
+        }
+      };
+      Runnable listener = new Runnable() {
+        @Override
+        public void run() {
+          Log.i(TAG, "Successfully set WebView proxy.");
+        }
+      };
+      ProxyController.getInstance().setProxyOverride(proxyConfig, executor, listener);
+    } else {
+      Log.w(TAG, "Cannot set WebView proxy.");
+    }
   }
 
   @Override