[PATCH v3 4/4] cli/{show, reply}: use repaired form of "Mixed Up" mangled messages

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

When showing or replying to a message that has been mangled in transit
by an MTA in the "Mixed up" way, notmuch should instead use the
repaired form of the message.

Tracking the repaired GMimeObject for the lifetime of the mime_node so
that it is cleaned up properly is probably the trickiest part of this
patch, but the choices here are based on the idea that the
mime_node_context is the memory manager for the whole mime_node tree
in the first place, so new GMimeObject tree created on-the-fly during
message parsing should be disposed of in the same place.

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
---
 mime-node.c                   | 21 +++++++++++++++++++++
 test/T351-pgpmime-mangling.sh |  2 --
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/mime-node.c b/mime-node.c
index 0be03de7..559028cc 100644
--- a/mime-node.c
+++ b/mime-node.c
@@ -36,6 +36,9 @@ typedef struct mime_node_context {
     GMimeMessage *mime_message;
     _notmuch_message_crypto_t *msg_crypto;
 
+    /* repaired/unmangled parts that will need to be cleaned up */
+    GSList *repaired_parts;
+
     /* Context provided by the caller. */
     _notmuch_crypto_t *crypto;
 } mime_node_context_t;
@@ -52,9 +55,20 @@ _mime_node_context_free (mime_node_context_t *res)
     if (res->stream)
 	g_object_unref (res->stream);
 
+    if (res->repaired_parts)
+	g_slist_free_full (res->repaired_parts, g_object_unref);
+
     return 0;
 }
 
+/* keep track of objects that need to be destroyed when the mime node
+   context goes away. */
+static void
+_mime_node_context_track_repaired_part (mime_node_context_t *ctx, GMimeObject *part) {
+    if (part)
+	ctx->repaired_parts = g_slist_prepend (ctx->repaired_parts, part);
+}
+
 const _notmuch_message_crypto_t*
 mime_node_get_message_crypto_status (mime_node_t *node)
 {
@@ -299,6 +313,13 @@ _mime_node_set_up_part (mime_node_t *node, GMimeObject *part, int numchild) {
 	node->part = part;
 	node->nchildren = 0;
     } else if (GMIME_IS_MULTIPART (part)) {
+	GMimeObject *repaired_part = _notmuch_repair_mixed_up_mangled (part);
+	if (repaired_part) {
+	    /* This was likely "Mixed Up" in transit!  We replace it
+	     * with the more likely-to-be-correct variant. */
+	    _mime_node_context_track_repaired_part (node->ctx, repaired_part);
+	    part = repaired_part;
+	}
 	node->part = part;
 	node->nchildren = g_mime_multipart_get_count (GMIME_MULTIPART (part));
     } else if (GMIME_IS_MESSAGE_PART (part)) {
diff --git a/test/T351-pgpmime-mangling.sh b/test/T351-pgpmime-mangling.sh
index 4555f937..71a68c05 100755
--- a/test/T351-pgpmime-mangling.sh
+++ b/test/T351-pgpmime-mangling.sh
@@ -9,13 +9,11 @@ add_email_corpus mangling
 bodytext='["body"][0]["content"][1]["content"]="The password is \"abcd1234!\", please do not tell anyone.\n"'
 
 test_begin_subtest "show 'Mixed-Up' mangled PGP/MIME message correctly"
-test_subtest_known_broken
 output=$(notmuch show --format=json --decrypt=true id:mixed-up@mangling.notmuchmail.org)
 test_json_nodes <<<"$output" \
                 'body:[0][0][0]'"$bodytext"
 
 test_begin_subtest "reply to 'Mixed-Up' mangled PGP/MIME message correctly"
-test_subtest_known_broken
 output=$(notmuch reply --format=json --decrypt=true id:mixed-up@mangling.notmuchmail.org)
 test_json_nodes <<<"$output" \
                 'body:["original"]'"$bodytext"
-- 
2.20.1