Add method to find multipart/encrypted parts

k9mail-library/src/main/java/com/fsck/k9/mail/Message.java

@@ -120,9 +120,6 @@ public abstract class Message implements Part, CompositeBody {
     @Override
     public abstract Body getBody();
 
-    @Override
-    public abstract String getContentType() throws MessagingException;
-
     @Override
     public abstract void addHeader(String name, String value) throws MessagingException;
 

k9mail-library/src/main/java/com/fsck/k9/mail/Part.java

@@ -15,7 +15,7 @@ public interface Part {
 
     Body getBody();
 
-    String getContentType() throws MessagingException;
+    String getContentType();
 
     String getDisposition() throws MessagingException;
 
@@ -25,7 +25,7 @@ public interface Part {
 
     boolean isMimeType(String mimeType) throws MessagingException;
 
-    String getMimeType() throws MessagingException;
+    String getMimeType();
 
     void setBody(Body body);
 

k9mail-library/src/main/java/com/fsck/k9/mail/internet/MimeBodyPart.java

@@ -85,7 +85,7 @@ public class MimeBodyPart extends BodyPart {
     }
 
     @Override
-    public String getContentType() throws MessagingException {
+    public String getContentType() {
         String contentType = getFirstHeader(MimeHeader.HEADER_CONTENT_TYPE);
         return (contentType == null) ? "text/plain" : contentType;
     }
@@ -111,7 +111,7 @@ public class MimeBodyPart extends BodyPart {
     }
 
     @Override
-    public String getMimeType() throws MessagingException {
+    public String getMimeType() {
         return MimeUtility.getHeaderParameter(getContentType(), null);
     }
 

k9mail-library/src/main/java/com/fsck/k9/mail/internet/MimeMessage.java

@@ -163,7 +163,7 @@ public class MimeMessage extends Message {
     }
 
     @Override
-    public String getContentType() throws MessagingException {
+    public String getContentType() {
         String contentType = getFirstHeader(MimeHeader.HEADER_CONTENT_TYPE);
         return (contentType == null) ? "text/plain" : contentType;
     }
@@ -172,12 +172,14 @@ public class MimeMessage extends Message {
     public String getDisposition() throws MessagingException {
         return getFirstHeader(MimeHeader.HEADER_CONTENT_DISPOSITION);
     }
+
     @Override
     public String getContentId() throws MessagingException {
         return null;
     }
+
     @Override
-    public String getMimeType() throws MessagingException {
+    public String getMimeType() {
         return MimeUtility.getHeaderParameter(getContentType(), null);
     }
 

k9mail/src/androidTest/java/com/fsck/k9/crypto/MessageDecryptorTest.java

@@ -0,0 +1,78 @@
+package com.fsck.k9.crypto;
+
+
+import java.util.List;
+
+import android.support.test.runner.AndroidJUnit4;
+
+import com.fsck.k9.mail.Part;
+import com.fsck.k9.mail.internet.MimeBodyPart;
+import com.fsck.k9.mail.internet.MimeMessage;
+import com.fsck.k9.mail.internet.MimeMessageHelper;
+import com.fsck.k9.mail.internet.MimeMultipart;
+import com.fsck.k9.mail.internet.TextBody;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertSame;
+
+
+@RunWith(AndroidJUnit4.class)
+public class MessageDecryptorTest {
+
+    @Test
+    public void findEncryptedPartsShouldReturnEmptyListForEmptyMessage() throws Exception {
+        MimeMessage emptyMessage = new MimeMessage();
+
+        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(emptyMessage);
+        assertEquals(0, encryptedParts.size());
+    }
+
+    @Test
+    public void findEncryptedPartsShouldReturnEmptyListForSimpleMessage() throws Exception {
+        MimeMessage message = new MimeMessage();
+        message.setBody(new TextBody("message text"));
+
+        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        assertEquals(0, encryptedParts.size());
+    }
+
+    @Test
+    public void findEncryptedPartsShouldReturnEmptyEncryptedPart() throws Exception {
+        MimeMessage message = new MimeMessage();
+        MimeMultipart mulitpartEncrypted = new MimeMultipart();
+        mulitpartEncrypted.setSubType("encrypted");
+        MimeMessageHelper.setBody(message, mulitpartEncrypted);
+
+        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        assertEquals(1, encryptedParts.size());
+        assertSame(message, encryptedParts.get(0));
+    }
+
+    @Test
+    public void findEncryptedPartsShouldReturnMultipleEncryptedParts() throws Exception {
+        MimeMessage message = new MimeMessage();
+        MimeMultipart multipartMixed = new MimeMultipart();
+        multipartMixed.setSubType("mixed");
+        MimeMessageHelper.setBody(message, multipartMixed);
+
+        MimeMultipart mulitpartEncryptedOne = new MimeMultipart();
+        mulitpartEncryptedOne.setSubType("encrypted");
+        MimeBodyPart bodyPartOne = new MimeBodyPart(mulitpartEncryptedOne);
+        multipartMixed.addBodyPart(bodyPartOne);
+
+        MimeBodyPart bodyPartTwo = new MimeBodyPart(null, "text/plain");
+        multipartMixed.addBodyPart(bodyPartTwo);
+
+        MimeMultipart mulitpartEncryptedThree = new MimeMultipart();
+        mulitpartEncryptedThree.setSubType("encrypted");
+        MimeBodyPart bodyPartThree = new MimeBodyPart(mulitpartEncryptedThree);
+        multipartMixed.addBodyPart(bodyPartThree);
+
+        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        assertEquals(2, encryptedParts.size());
+        assertSame(bodyPartOne, encryptedParts.get(0));
+        assertSame(bodyPartThree, encryptedParts.get(1));
+    }
+}

k9mail/src/main/java/com/fsck/k9/crypto/MessageDecryptor.java

@@ -0,0 +1,41 @@
+package com.fsck.k9.crypto;
+
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Stack;
+
+import com.fsck.k9.mail.Body;
+import com.fsck.k9.mail.BodyPart;
+import com.fsck.k9.mail.MessagingException;
+import com.fsck.k9.mail.Multipart;
+import com.fsck.k9.mail.Part;
+
+
+public class MessageDecryptor {
+    private static final String MULTIPART_ENCRYPTED = "multipart/encrypted";
+
+    public static List<Part> findEncryptedParts(Part startPart) {
+        List<Part> encryptedParts = new ArrayList<Part>();
+        Stack<Part> partsToCheck = new Stack<Part>();
+        partsToCheck.push(startPart);
+
+        while (!partsToCheck.isEmpty()) {
+            Part part = partsToCheck.pop();
+            String mimeType = part.getMimeType();
+            Body body = part.getBody();
+
+            if (MULTIPART_ENCRYPTED.equals(mimeType)) {
+                encryptedParts.add(part);
+            } else if (body instanceof Multipart) {
+                Multipart multipart = (Multipart) body;
+                for (int i = multipart.getCount() - 1; i >= 0; i--) {
+                    BodyPart bodyPart = multipart.getBodyPart(i);
+                    partsToCheck.push(bodyPart);
+                }
+            }
+        }
+
+        return encryptedParts;
+    }
+}