[PATCH v2 09/16] index encrypted parts when asked.

[Daniel Kahn Gillmor <dkg@fifthhorseman.net>]

If we see index options that ask us to decrypt when indexing a
message, and we encounter an encrypted part, we'll try to descend into
it.

If we can decrypt, we tag the message with index-decrypted.

If we can't decrypt (or recognize the encrypted type of mail), we tag
with decryption-failed.

Note that a single message may be tagged with "encrypted" and
"index-decrypted" and "decryption-failed".  For example, consider a
message that includes multiple layers of encryption.  It is
automatically tagged with "encrypted".  If we decrypt the outer layer
("index-decrypted"), but fail on the inner layer
("decryption-failed").
---
 lib/database.cc       |  3 ++-
 lib/index.cc          | 64 ++++++++++++++++++++++++++++++++++++++++++++++++---
 lib/notmuch-private.h |  1 +
 3 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/lib/database.cc b/lib/database.cc
index 0d4dc9b..7d88f69 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -2402,6 +2402,7 @@ notmuch_database_add_message (notmuch_database_t *notmuch,
     notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS, ret2;
     notmuch_private_status_t private_status;
     notmuch_bool_t is_ghost = false;
+    notmuch_indexopts_t *indexopts = NULL;
 
     const char *date, *header;
     const char *from, *to, *subject;
@@ -2514,7 +2515,7 @@ notmuch_database_add_message (notmuch_database_t *notmuch,
 	    date = _notmuch_message_file_get_header (message_file, "date");
 	    _notmuch_message_set_header_values (message, date, from, subject);
 
-	    ret = _notmuch_message_index_file (message, message_file);
+	    ret = _notmuch_message_index_file (message, indexopts, message_file);
 	    if (ret)
 		goto DONE;
 	} else {
diff --git a/lib/index.cc b/lib/index.cc
index ab0fd78..eb406d2 100644
--- a/lib/index.cc
+++ b/lib/index.cc
@@ -300,9 +300,14 @@ _index_address_list (notmuch_message_t *message,
     }
 }
 
+static void
+_index_encrypted_mime_part (notmuch_message_t *message, notmuch_indexopts_t *indexopts,
+			    GMimeContentType *content_type, GMimeMultipartEncrypted *part);
+
 /* Callback to generate terms for each mime part of a message. */
 static void
 _index_mime_part (notmuch_message_t *message,
+		  notmuch_indexopts_t *indexopts,
 		  GMimeObject *part)
 {
     GMimeStream *stream, *filter;
@@ -340,17 +345,19 @@ _index_mime_part (notmuch_message_t *message,
 	    /* FIXME: is it always just the first part that is signed in
 	     all multipart/signed messages?*/
 	    _index_mime_part (message,
+			      indexopts,
 			      g_mime_multipart_get_part (multipart, 0));
 	    
 	    if (g_mime_multipart_get_count (multipart) > 2)
 		_notmuch_database_log (_notmuch_message_database (message),
 				       "Warning: Unexpected extra parts of multipart/signed. Indexing anyway.\n");
 	} else if (GMIME_IS_MULTIPART_ENCRYPTED (multipart)) {
-	    /* Don't index encrypted parts */
 	    _notmuch_message_add_term (message, "tag", "encrypted");
+	    _index_encrypted_mime_part(message, indexopts, content_type, GMIME_MULTIPART_ENCRYPTED (part));
 	} else {
 	    for (i = 0; i < g_mime_multipart_get_count (multipart); i++) {
 		_index_mime_part (message,
+				  indexopts,
 				  g_mime_multipart_get_part (multipart, i));
 	    }
 	}
@@ -362,7 +369,7 @@ _index_mime_part (notmuch_message_t *message,
 
 	mime_message = g_mime_message_part_get_message (GMIME_MESSAGE_PART (part));
 
-	_index_mime_part (message, g_mime_message_get_mime_part (mime_message));
+	_index_mime_part (message, indexopts, g_mime_message_get_mime_part (mime_message));
 
 	return;
     }
@@ -432,8 +439,59 @@ _index_mime_part (notmuch_message_t *message,
     }
 }
 
+/* descend (if desired) into the cleartext part of an encrypted MIME
+ * part while indexing. */
+static void
+_index_encrypted_mime_part (notmuch_message_t *message,
+			    notmuch_indexopts_t *indexopts,
+			    GMimeContentType *content_type,
+			    GMimeMultipartEncrypted *encrypted_data)
+{
+    notmuch_status_t status;
+    GMimeCryptoContext* crypto_ctx = NULL;
+    const char *protocol = NULL;
+    GError *err = NULL;
+    notmuch_database_t * notmuch = NULL;
+    GMimeObject *clear = NULL;
+
+    if (!indexopts || !notmuch_indexopts_get_try_decrypt (indexopts))
+	return;
+
+    protocol = g_mime_content_type_get_parameter (content_type, "protocol");
+    notmuch = _notmuch_message_database (message);
+    
+    status = _notmuch_crypto_get_gmime_ctx_for_protocol (&(indexopts->crypto),
+							 protocol, &crypto_ctx);
+    if (status) {
+	_notmuch_database_log (notmuch, "Warning: setup failed for decrypting "
+			       "during indexing. (%d)\n", status);
+	_notmuch_message_add_term (message, "tag", "index-decryption-failed");
+	return;
+    }
+
+    /* we don't need the GMimeDecryptResult, because we're not looking
+     * at validating signatures, and we don't care about indexing who
+     * the message was ostensibly encrypted to.
+     */
+    clear = g_mime_multipart_encrypted_decrypt(encrypted_data, crypto_ctx,
+					       NULL, &err);
+    if (err) {
+	_notmuch_database_log (notmuch, "Failed to decrypt during indexing. (%d:%d) [%s]\n",
+			       err->domain, err->code, err->message);
+	g_error_free(err);
+	/* Indicate that we failed to decrypt during indexing */
+	_notmuch_message_add_term (message, "tag", "index-decryption-failed");
+	return;
+    }
+    _index_mime_part (message, indexopts, clear);
+    g_object_unref (clear);
+    
+    _notmuch_message_add_term (message, "tag", "index-decrypted");
+}
+
 notmuch_status_t
 _notmuch_message_index_file (notmuch_message_t *message,
+			     notmuch_indexopts_t *indexopts,
 			     notmuch_message_file_t *message_file)
 {
     GMimeMessage *mime_message;
@@ -463,7 +521,7 @@ _notmuch_message_index_file (notmuch_message_t *message,
     subject = g_mime_message_get_subject (mime_message);
     _notmuch_message_gen_terms (message, "subject", subject);
 
-    _index_mime_part (message, g_mime_message_get_mime_part (mime_message));
+    _index_mime_part (message, indexopts, g_mime_message_get_mime_part (mime_message));
 
     return NOTMUCH_STATUS_SUCCESS;
 }
diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h
index e9c1e8a..9bd4f33 100644
--- a/lib/notmuch-private.h
+++ b/lib/notmuch-private.h
@@ -425,6 +425,7 @@ _notmuch_message_file_get_header (notmuch_message_file_t *message,
 
 notmuch_status_t
 _notmuch_message_index_file (notmuch_message_t *message,
+			     notmuch_indexopts_t *indexopts,
 			     notmuch_message_file_t *message_file);
 
 /* messages.c */
-- 
2.7.0.rc3