index: avoid indexing legacy-display parts

When we notice a legacy-display part during indexing, it makes more
sense to avoid indexing it as part of the message body.

Given that the protected subject will already be indexed, there is no
need to index this part at all, so we skip over it.

If this happens during indexing, we set a property on the message:
index.repaired=skip-protected-headers-legacy-display

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>

3 files changed, 22 insertions, 6 deletions

diff --git a/doc/man7/notmuch-properties.rst b/doc/man7/notmuch-properties.rst
index 2e610683..e2db2ef5 100644
--- a/doc/man7/notmuch-properties.rst
+++ b/doc/man7/notmuch-properties.rst
@@ -121,6 +121,12 @@ of its normal activity.
     ``index.repaired`` property to note the type of repair(s) it
     performed.
 
+    ``index.repaired=skip-protected-headers-legacy-display`` indicates
+    that when indexing the cleartext of an encrypted message, notmuch
+    skipped over a "legacy-display" text/rfc822-headers part that it
+    found in that message, since it was able to index the built-in
+    protected headers directly.
+
 SEE ALSO
 ========
 
diff --git a/lib/index.cc b/lib/index.cc
index 08cc84e2..1301d78a 100644
--- a/lib/index.cc
+++ b/lib/index.cc
@@ -435,8 +435,14 @@ _index_mime_part (notmuch_message_t *message,
 		continue;
 	    }
 	    child = g_mime_multipart_get_part (multipart, i);
-	    (void) _notmuch_message_crypto_potential_payload (msg_crypto, child, part, i);
-	    _index_mime_part (message, indexopts, child, msg_crypto);
+	    GMimeObject *toindex = child;
+	    if (_notmuch_message_crypto_potential_payload (msg_crypto, child, part, i) &&
+		msg_crypto->decryption_status == NOTMUCH_MESSAGE_DECRYPTED_FULL) {
+		toindex = _notmuch_repair_crypto_payload_skip_legacy_display (child);
+		if (toindex != child)
+		    notmuch_message_add_property (message, "index.repaired", "skip-protected-headers-legacy-display");
+	    }
+	    _index_mime_part (message, indexopts, toindex, msg_crypto);
 	}
 	return;
     }
@@ -573,8 +579,14 @@ _index_encrypted_mime_part (notmuch_message_t *message,
 	}
 	g_object_unref (decrypt_result);
     }
-    _notmuch_message_crypto_potential_payload (msg_crypto, clear, GMIME_OBJECT (encrypted_data), GMIME_MULTIPART_ENCRYPTED_CONTENT);
-    _index_mime_part (message, indexopts, clear, msg_crypto);
+    GMimeObject *toindex = clear;
+    if (_notmuch_message_crypto_potential_payload (msg_crypto, clear, GMIME_OBJECT (encrypted_data), GMIME_MULTIPART_ENCRYPTED_CONTENT) &&
+	msg_crypto->decryption_status == NOTMUCH_MESSAGE_DECRYPTED_FULL) {
+	toindex = _notmuch_repair_crypto_payload_skip_legacy_display (clear);
+	if (toindex != clear)
+	    notmuch_message_add_property (message, "index.repaired", "skip-protected-headers-legacy-display");
+    }
+    _index_mime_part (message, indexopts, toindex, msg_crypto);
     g_object_unref (clear);
 
     status = notmuch_message_add_property (message, "index.decryption", "success");
diff --git a/test/T356-protected-headers.sh b/test/T356-protected-headers.sh
index 867b8722..925805df 100755
--- a/test/T356-protected-headers.sh
+++ b/test/T356-protected-headers.sh
@@ -148,12 +148,10 @@ test_json_nodes <<<"$output" \
                 'no_legacy_display:["original"]["body"][0]["content"][1]["content-type"]="text/plain"'
 
 test_begin_subtest "do not treat legacy-display part as body when indexing"
-test_subtest_known_broken
 output=$(notmuch search --output=messages body:interrupting)
 test_expect_equal "$output" ''
 
 test_begin_subtest "identify message that had a legacy display part skipped during indexing"
-test_subtest_known_broken
 output=$(notmuch search --output=messages property:index.repaired=skip-protected-headers-legacy-display)
 test_expect_equal "$output" id:protected-with-legacy-display@crypto.notmuchmail.org