Improve handling of missing and invalid attachments.

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentRetrieverIntegrationTest.java

@@ -55,7 +55,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(smallKitten);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -71,7 +71,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(originalKitten);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -87,7 +87,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getUrlInputStream(pngKitten);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -103,7 +103,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(uberGif);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -118,7 +118,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(lottaPixel);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -133,7 +133,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(imageIoCrash);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -148,7 +148,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(gimpCrash);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -163,7 +163,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(optiPngAfl);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -178,7 +178,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(librawError);
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertTrue(item.hasError());
 	}
 
@@ -187,7 +187,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -202,7 +202,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -217,7 +217,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("error_large.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -232,7 +232,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_high.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
@@ -247,7 +247,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_wide.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1920, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreator.java

@@ -98,7 +98,7 @@ public class AttachmentCreator {
 		// get and cache AttachmentItem for ImagePreview
 		try {
 			Attachment a = retriever.getMessageAttachment(h);
-			AttachmentItem item = retriever.getAttachmentItem(h, a, needsSize);
+			AttachmentItem item = retriever.getAttachmentItem(a, needsSize);
 			if (item.hasError()) throw new IOException();
 			AttachmentItemResult itemResult =
 					new AttachmentItemResult(uri, item);

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetriever.java

@@ -9,8 +9,6 @@ import android.webkit.MimeTypeMap;
 
 import com.bumptech.glide.util.MarkEnforcingInputStream;
 
-import org.briarproject.bramble.api.Pair;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
@@ -22,7 +20,6 @@ import org.briarproject.briar.api.messaging.MessagingManager;
 import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -38,9 +35,7 @@ import static android.support.media.ExifInterface.TAG_ORIENTATION;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
 public class AttachmentRetriever {
@@ -93,7 +88,8 @@ public class AttachmentRetriever {
 		});
 	}
 
-	public void cachePut(MessageId messageId, List<AttachmentItem> attachments) {
+	public void cachePut(MessageId messageId,
+			List<AttachmentItem> attachments) {
 		attachmentCache.put(messageId, attachments);
 	}
 
@@ -102,47 +98,17 @@ public class AttachmentRetriever {
 		return attachmentCache.get(messageId);
 	}
 
-	@DatabaseExecutor
-	public List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
-			List<AttachmentHeader> headers) throws DbException {
-		long start = now();
-		List<Pair<AttachmentHeader, Attachment>> attachments =
-				new ArrayList<>(headers.size());
-		for (AttachmentHeader h : headers) {
-			Attachment a = messagingManager.getAttachment(h);
-			attachments.add(new Pair<>(h, a));
-		}
-		logDuration(LOG, "Loading attachments", start);
-		return attachments;
-	}
-
-	Attachment getMessageAttachment(AttachmentHeader h) throws DbException {
+	public Attachment getMessageAttachment(AttachmentHeader h)
+			throws DbException {
 		return messagingManager.getAttachment(h);
 	}
 
-	/**
-	 * Creates {@link AttachmentItem}s from the passed headers and Attachments.
-	 * <p>
-	 * Note: This closes the {@link Attachment}'s {@link InputStream}.
-	 */
-	public List<AttachmentItem> getAttachmentItems(
-			List<Pair<AttachmentHeader, Attachment>> attachments) {
-		boolean needsSize = attachments.size() == 1;
-		List<AttachmentItem> items = new ArrayList<>(attachments.size());
-		for (Pair<AttachmentHeader, Attachment> a : attachments) {
-			AttachmentItem item =
-					getAttachmentItem(a.getFirst(), a.getSecond(), needsSize);
-			items.add(item);
-		}
-		return items;
-	}
-
 	/**
 	 * Creates an {@link AttachmentItem} from the {@link Attachment}'s
 	 * {@link InputStream} which will be closed when this method returns.
 	 */
-	AttachmentItem getAttachmentItem(AttachmentHeader h, Attachment a,
-			boolean needsSize) {
+	public AttachmentItem getAttachmentItem(Attachment a, boolean needsSize) {
+		AttachmentHeader h = a.getHeader();
 		if (!needsSize) {
 			String extension =
 					imageHelper.getExtensionFromMimeType(h.getContentType());

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -37,6 +37,7 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -107,6 +108,7 @@ import static android.support.v7.util.SortedList.INVALID_POSITION;
 import static android.view.Gravity.RIGHT;
 import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
 import static java.util.Collections.sort;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
@@ -434,29 +436,36 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
-	private void eagerlyLoadMessageSize(PrivateMessageHeader h)
-			throws DbException {
-		MessageId id = h.getId();
-		// If the message has text, load it
-		if (h.hasText()) {
-			String text = textCache.get(id);
-			if (text == null) {
-				LOG.info("Eagerly loading text for latest message");
-				text = messagingManager.getMessageText(id);
-				textCache.put(id, requireNonNull(text));
+	private void eagerlyLoadMessageSize(PrivateMessageHeader h) {
+		try {
+			MessageId id = h.getId();
+			// If the message has text, load it
+			if (h.hasText()) {
+				String text = textCache.get(id);
+				if (text == null) {
+					LOG.info("Eagerly loading text for latest message");
+					text = messagingManager.getMessageText(id);
+					textCache.put(id, requireNonNull(text));
+				}
 			}
-		}
-		// If the message has a single image, load its size - for multiple
-		// images we use a grid so the size is fixed
-		if (h.getAttachmentHeaders().size() == 1) {
-			List<AttachmentItem> items = attachmentRetriever.cacheGet(id);
-			if (items == null) {
-				LOG.info("Eagerly loading image size for latest message");
-				items = attachmentRetriever.getAttachmentItems(
-						attachmentRetriever.getMessageAttachments(
-								h.getAttachmentHeaders()));
-				attachmentRetriever.cachePut(id, items);
+			// If the message has a single image, load its size - for multiple
+			// images we use a grid so the size is fixed
+			List<AttachmentHeader> headers = h.getAttachmentHeaders();
+			if (headers.size() == 1) {
+				List<AttachmentItem> items = attachmentRetriever.cacheGet(id);
+				if (items == null) {
+					LOG.info("Eagerly loading image size for latest message");
+					Attachment a = attachmentRetriever
+							.getMessageAttachment(headers.get(0));
+					AttachmentItem item =
+							attachmentRetriever.getAttachmentItem(a, true);
+					attachmentRetriever.cachePut(id, singletonList(item));
+				}
 			}
+		} catch (NoSuchMessageException e) {
+			LOG.info("Attachment not received yet");
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
 		}
 	}
 
@@ -536,14 +545,23 @@ public class ConversationActivity extends BriarActivity
 
 	private void loadMessageAttachments(MessageId messageId,
 			List<AttachmentHeader> headers) {
+		// TODO: Use placeholders for missing/invalid attachments
 		runOnDbThread(() -> {
 			try {
-				List<Pair<AttachmentHeader, Attachment>> attachments =
-						attachmentRetriever.getMessageAttachments(headers);
 				// TODO move getting the items off to IoExecutor, if size == 1
-				List<AttachmentItem> items =
-						attachmentRetriever.getAttachmentItems(attachments);
+				boolean needsSize = headers.size() == 1;
+				List<AttachmentItem> items = new ArrayList<>(headers.size());
+				for (AttachmentHeader h : headers) {
+					Attachment a = attachmentRetriever.getMessageAttachment(h);
+					AttachmentItem item =
+							attachmentRetriever.getAttachmentItem(a, needsSize);
+					items.add(item);
+				}
+				// TODO: Don't cache items unless all are present and valid
+				attachmentRetriever.cachePut(messageId, items);
 				displayMessageAttachments(messageId, items);
+			} catch (NoSuchMessageException e) {
+				LOG.info("Attachment not received yet");
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -553,7 +571,6 @@ public class ConversationActivity extends BriarActivity
 	private void displayMessageAttachments(MessageId m,
 			List<AttachmentItem> items) {
 		runOnUiThreadUnlessDestroyed(() -> {
-			attachmentRetriever.cachePut(m, items);
 			Pair<Integer, ConversationMessageItem> pair =
 					adapter.getMessageItem(m);
 			if (pair != null) {
@@ -567,6 +584,7 @@ public class ConversationActivity extends BriarActivity
 
 	@Override
 	public void eventOccurred(Event e) {
+		// TODO: Load missing attachments when they arrive
 		if (e instanceof ContactRemovedEvent) {
 			ContactRemovedEvent c = (ContactRemovedEvent) e;
 			if (c.getContactId().equals(contactId)) {

briar-android/src/test/java/org/briarproject/briar/android/attachment/AttachmentRetrieverTest.java

@@ -9,14 +9,11 @@ import org.briarproject.briar.api.messaging.MessagingManager;
 import org.jmock.Expectations;
 import org.junit.Test;
 
-import java.io.BufferedInputStream;
 import java.io.ByteArrayInputStream;
 import java.io.InputStream;
 
 import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
-import static org.briarproject.bramble.util.StringUtils.getRandomString;
-import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_CONTENT_TYPE_BYTES;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
@@ -27,35 +24,26 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			100, 50, 200, 75, 300
 	);
 	private final MessageId msgId = new MessageId(getRandomId());
-	private final String mimeType = getRandomString(MAX_CONTENT_TYPE_BYTES);
-	private final AttachmentHeader header =
-			new AttachmentHeader(msgId, mimeType);
-	private final Attachment attachment = new Attachment(header,
-			new BufferedInputStream(
-					new ByteArrayInputStream(getRandomBytes(42))));
-
 	private final MessagingManager messagingManager =
 			context.mock(MessagingManager.class);
 	private final ImageHelper imageHelper = context.mock(ImageHelper.class);
-	private final AttachmentRetriever controller =
-			new AttachmentRetriever(
-					messagingManager,
-					dimensions,
-					imageHelper
-			);
+	private final AttachmentRetriever retriever = new AttachmentRetriever(
+			messagingManager,
+			dimensions,
+			imageHelper
+	);
 
 	@Test
 	public void testNoSize() {
 		String mimeType = "image/jpeg";
-		AttachmentHeader h = getAttachmentHeader(mimeType);
+		Attachment attachment = getAttachment(mimeType);
 
 		context.checking(new Expectations() {{
 			oneOf(imageHelper).getExtensionFromMimeType(mimeType);
 			will(returnValue("jpg"));
 		}});
 
-		AttachmentItem item =
-				controller.getAttachmentItem(h, attachment, false);
+		AttachmentItem item = retriever.getAttachmentItem(attachment, false);
 		assertEquals(mimeType, item.getMimeType());
 		assertEquals("jpg", item.getExtension());
 		assertFalse(item.hasError());
@@ -64,22 +52,21 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 	@Test
 	public void testNoSizeWrongMimeTypeProducesError() {
 		String mimeType = "application/octet-stream";
-		AttachmentHeader h = getAttachmentHeader(mimeType);
+		Attachment attachment = getAttachment(mimeType);
 
 		context.checking(new Expectations() {{
 			oneOf(imageHelper).getExtensionFromMimeType(mimeType);
 			will(returnValue(null));
 		}});
 
-		AttachmentItem item =
-				controller.getAttachmentItem(h, attachment, false);
+		AttachmentItem item = retriever.getAttachmentItem(attachment, false);
 		assertTrue(item.hasError());
 	}
 
 	@Test
 	public void testSmallJpegImage() {
 		String mimeType = "image/jpeg";
-		AttachmentHeader h = getAttachmentHeader(mimeType);
+		Attachment attachment = getAttachment(mimeType);
 
 		context.checking(new Expectations() {{
 			oneOf(imageHelper).decodeStream(with(any(InputStream.class)));
@@ -88,7 +75,7 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue("jpg"));
 		}});
 
-		AttachmentItem item = controller.getAttachmentItem(h, attachment, true);
+		AttachmentItem item = retriever.getAttachmentItem(attachment, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -102,7 +89,7 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 	@Test
 	public void testBigJpegImage() {
 		String mimeType = "image/jpeg";
-		AttachmentHeader h = getAttachmentHeader(mimeType);
+		Attachment attachment = getAttachment(mimeType);
 
 		context.checking(new Expectations() {{
 			oneOf(imageHelper).decodeStream(with(any(InputStream.class)));
@@ -111,7 +98,7 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue("jpg"));
 		}});
 
-		AttachmentItem item = controller.getAttachmentItem(h, attachment, true);
+		AttachmentItem item = retriever.getAttachmentItem(attachment, true);
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -121,7 +108,7 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 
 	@Test
 	public void testMalformedError() {
-		AttachmentHeader h = getAttachmentHeader("image/jpeg");
+		Attachment attachment = getAttachment("image/jpeg");
 
 		context.checking(new Expectations() {{
 			oneOf(imageHelper).decodeStream(with(any(InputStream.class)));
@@ -130,12 +117,13 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue(null));
 		}});
 
-		AttachmentItem item = controller.getAttachmentItem(h, attachment, true);
+		AttachmentItem item = retriever.getAttachmentItem(attachment, true);
 		assertTrue(item.hasError());
 	}
 
-	private AttachmentHeader getAttachmentHeader(String contentType) {
-		return new AttachmentHeader(msgId, contentType);
+	private Attachment getAttachment(String contentType) {
+		AttachmentHeader header = new AttachmentHeader(msgId, contentType);
+		InputStream in = new ByteArrayInputStream(getRandomBytes(42));
+		return new Attachment(header, in);
 	}
-
 }

briar-api/src/main/java/org/briarproject/briar/api/messaging/InvalidAttachmentException.java

@@ -0,0 +1,14 @@
+package org.briarproject.briar.api.messaging;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * An exception that is thrown when an {@link AttachmentHeader} is used to
+ * load an {@link Attachment}, and the header refers to a message that is not
+ * an attachment, or to an attachment that does not have the expected content
+ * type.
+ */
+@NotNullByDefault
+public class InvalidAttachmentException extends DbException {
+}

briar-api/src/main/java/org/briarproject/briar/api/messaging/MessagingManager.java

@@ -69,6 +69,10 @@ public interface MessagingManager extends ConversationClient {
 
 	/**
 	 * Returns the attachment with the given message ID and content type.
+	 *
+	 * @throws InvalidAttachmentException If the header refers to a message
+	 * that is not an attachment, or to an attachment that does not have the
+	 * expected content type
 	 */
 	Attachment getAttachment(AttachmentHeader h) throws DbException;
 

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -32,6 +32,7 @@ import org.briarproject.briar.api.conversation.ConversationMessageHeader;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.FileTooBigException;
+import org.briarproject.briar.api.messaging.InvalidAttachmentException;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
@@ -380,6 +381,12 @@ class MessagingManagerImpl implements MessagingManager, IncomingMessageHook,
 		byte[] body = clientHelper.getMessage(m).getBody();
 		try {
 			BdfDictionary meta = clientHelper.getMessageMetadataAsDictionary(m);
+			Long messageType = meta.getOptionalLong(MSG_KEY_MSG_TYPE);
+			if (messageType == null || messageType != ATTACHMENT)
+				throw new InvalidAttachmentException();
+			String contentType = meta.getString(MSG_KEY_CONTENT_TYPE);
+			if (!contentType.equals(h.getContentType()))
+				throw new InvalidAttachmentException();
 			int offset = meta.getLong(MSG_KEY_DESCRIPTOR_LENGTH).intValue();
 			return new Attachment(h, new ByteArrayInputStream(body, offset,
 					body.length - offset));