From: David Bremner <david@tethera.net>
To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>,
Notmuch Mail <notmuch@notmuchmail.org>
Subject: Re: [PATCH v4 2/4] util/repair: identify and repair "Mixed Up" mangled messages
Date: Fri, 13 Sep 2019 22:58:27 -0300 [thread overview]
Message-ID: <871rwj1vwc.fsf@tethera.net> (raw)
In-Reply-To: <20190909032726.8931-3-dkg@fifthhorseman.net>
Daniel Kahn Gillmor <dkg@fifthhorseman.net> writes:
> +/* see
> + * https://tools.ietf.org/html/draft-dkg-openpgp-pgpmime-message-mangling-00#section-4.1.1 */
> +static bool
> +_notmuch_is_mixed_up_mangled (GMimeObject *part)
> +{
> + GMimeMultipart *mpart = NULL;
> + GMimeObject *first, *second, *third = NULL;
> + char *prelude_string = NULL;
> + bool prelude_is_empty;
> +
> + if (! g_mime_content_type_is_type (g_mime_object_get_content_type (part),
> + "multipart", "mixed"))
> + return false;
Can g_mime_object_get_content_type plausibly fail (and return NULL) here?
> + if (! GMIME_IS_MULTIPART (part))
> + return false;
I guess this happens if the mime structure does not match the content
type declaration? Not sure if this needs a comment or if it's clear
enough.
> + mpart = GMIME_MULTIPART (part);
> + if (mpart == NULL)
> + return false;
> + if (g_mime_multipart_get_count (mpart) != 3)
> + return false;
> + first = g_mime_multipart_get_part (mpart, 0);
there's a slight cognitive dissonance for me between the zero and one
based indexing schemes here. part0, part1, and part2? or maybe an
GMimeObject *part[3]
> + if (! g_mime_content_type_is_type (g_mime_object_get_content_type (first),
> + "text", "plain"))
> + return false;
> + if (! GMIME_IS_TEXT_PART (first))
> + return false;
> + second = g_mime_multipart_get_part (mpart, 1);
> + if (! g_mime_content_type_is_type (g_mime_object_get_content_type (second),
> + "application", "pgp-encrypted"))
> + return false;
> + third = g_mime_multipart_get_part (mpart, 2);
> + if (! g_mime_content_type_is_type (g_mime_object_get_content_type (third),
> + "application", "octet-stream"))
> + return false;
> +
> + /* Is first subpart length 0? */
> + prelude_string = g_mime_text_part_get_text (GMIME_TEXT_PART (first));
> + prelude_is_empty = ! (strcmp ("", prelude_string));
> + g_free (prelude_string);
It might make sense to use the EMPTY_STRING macro here, although
currently it's only accesible via notmuch-private.h
> + if (! prelude_is_empty)
> + return false;
> +
> + /* FIXME: after decoding and stripping whitespace, is second
> + * subpart just "Version: 1" ? */
> +
> + /* FIXME: can we determine that third subpart is *only* PGP
> + * encrypted data? I tried g_mime_part_get_openpgp_data () but
> + * found https://github.com/jstedfast/gmime/issues/60 */
> +
> + return true;
> +}
> +
> +
> +/* see
> + * https://tools.ietf.org/html/draft-dkg-openpgp-pgpmime-message-mangling-00#section-4.1.2 */
> +GMimeObject *
> +_notmuch_repair_mixed_up_mangled (GMimeObject *part)
> +{
> + GMimeMultipart *mpart = NULL, *mpart_ret = NULL;
> + GMimeObject *ret = NULL;
> +
> + if (! _notmuch_is_mixed_up_mangled (part))
> + return NULL;
> + mpart = GMIME_MULTIPART (part);
> + ret = GMIME_OBJECT (g_mime_multipart_encrypted_new ());
> + if (ret == NULL)
> + return NULL;
> + mpart_ret = GMIME_MULTIPART (ret);
> + if (mpart_ret == NULL) {
> + g_object_unref (ret);
> + return NULL;
> + }
> + g_mime_object_set_content_type_parameter (ret, "protocol", "application/pgp-encrypted");
> +
> + g_mime_multipart_insert (mpart_ret, 0, g_mime_multipart_get_part (mpart, 1));
> + g_mime_multipart_insert (mpart_ret, 1, g_mime_multipart_get_part (mpart, 2));
> + return ret;
> +}
> diff --git a/util/repair.h b/util/repair.h
> index 9974d693..492f5a20 100644
> --- a/util/repair.h
> +++ b/util/repair.h
> @@ -25,9 +25,19 @@ extern "C" {
> * returned object will only be released when the original part is
> * disposed of.
> */
> +
> GMimeObject *
> _notmuch_repair_crypto_payload_skip_legacy_display (GMimeObject *payload);
>
> +/* Detecting and repairing "Mixed-Up MIME mangling". see
> + * https://tools.ietf.org/html/draft-dkg-openpgp-pgpmime-message-mangling-00#section-4.1
> + * If this returns NULL, the message was probably not "Mixed up". If
> + * it returns non-NULL, then there is a newly-allocated MIME part that
> + * represents the repaired version. The caller is responsible for
> + * ensuring that any returned object is freed with g_object_unref. */
> +GMimeObject *
> +_notmuch_repair_mixed_up_mangled (GMimeObject *part);
> +
> #ifdef __cplusplus
> }
> #endif
> --
> 2.23.0
>
> _______________________________________________
> notmuch mailing list
> notmuch@notmuchmail.org
> https://notmuchmail.org/mailman/listinfo/notmuch
next prev parent reply other threads:[~2019-09-14 2:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 3:27 v4 of repairing Mixed-up mangled MIME messages Daniel Kahn Gillmor
2019-09-09 3:27 ` [PATCH v4 1/4] test: add test for "Mixed-Up Mime" message mangling Daniel Kahn Gillmor
2019-09-09 3:27 ` [PATCH v4 2/4] util/repair: identify and repair "Mixed Up" mangled messages Daniel Kahn Gillmor
2019-09-14 1:58 ` David Bremner [this message]
2019-09-15 7:37 ` Daniel Kahn Gillmor
2019-09-15 7:38 ` [PATCH v5 " Daniel Kahn Gillmor
2019-09-15 20:26 ` Tomi Ollila
2019-09-15 23:09 ` Daniel Kahn Gillmor
2019-09-09 3:27 ` [PATCH v4 3/4] index: repair "Mixed Up" messages before indexing Daniel Kahn Gillmor
2019-09-09 3:27 ` [PATCH v4 4/4] cli/{show, reply}: use repaired form of "Mixed Up" mangled messages Daniel Kahn Gillmor
[not found] ` <87zhj5xcet.fsf@tethera.net>
2019-09-16 10:49 ` David Bremner
2019-09-17 5:59 ` Daniel Kahn Gillmor
2019-09-17 23:36 ` David Bremner
2019-09-14 7:29 ` v4 of repairing Mixed-up mangled MIME messages Jameson Graef Rollins
2019-09-14 11:30 ` David Bremner
2019-09-14 16:08 ` Jameson Graef Rollins
2019-09-14 17:33 ` David Bremner
2019-09-15 3:05 ` Daniel Kahn Gillmor
2019-09-14 17:54 ` Daniel Kahn Gillmor
2019-09-14 23:58 ` Jameson Graef Rollins
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