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| | /* notmuch - Not much of an email program, (just index and search)
*
* Copyright © 2019 Daniel Kahn Gillmor
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see https://www.gnu.org/licenses/ .
*
* Authors: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
*/
#include <stdbool.h>
#include "repair.h"
static bool
_notmuch_crypto_payload_has_legacy_display (GMimeObject *payload)
{
GMimeMultipart *mpayload;
const char *protected_header_parameter;
GMimeTextPart *legacy_display;
char *legacy_display_header_text = NULL;
GMimeStream *stream = NULL;
GMimeParser *parser = NULL;
GMimeObject *legacy_header_object = NULL, *first;
GMimeHeaderList *legacy_display_headers = NULL, *protected_headers = NULL;
bool ret = false;
if (! g_mime_content_type_is_type (g_mime_object_get_content_type (payload),
"multipart", "mixed"))
return false;
protected_header_parameter = g_mime_object_get_content_type_parameter (payload, "protected-headers");
if ((! protected_header_parameter) || strcmp (protected_header_parameter, "v1"))
return false;
if (! GMIME_IS_MULTIPART (payload))
return false;
mpayload = GMIME_MULTIPART (payload);
if (mpayload == NULL)
return false;
if (g_mime_multipart_get_count (mpayload) != 2)
return false;
first = g_mime_multipart_get_part (mpayload, 0);
/* Early implementations that generated "Legacy Display" parts used
Content-Type: text/rfc822-headers, but text/plain is more widely
rendered, so it is now the standard choice. We accept either as a
Legacy Display part. */
if (! (g_mime_content_type_is_type (g_mime_object_get_content_type (first),
"text", "plain") ||
g_mime_content_type_is_type (g_mime_object_get_content_type (first),
"text", "rfc822-headers")))
return false;
protected_header_parameter = g_mime_object_get_content_type_parameter (first, "protected-headers");
if ((! protected_header_parameter) || strcmp (protected_header_parameter, "v1"))
return false;
if (! GMIME_IS_TEXT_PART (first))
return false;
/* ensure that the headers in the first part all match the values
* found in the payload's own protected headers! if they don't,
* we should not treat this as a valid "legacy-display" part.
*
* Crafting a GMimeHeaderList object from the content of the
* text/rfc822-headers part is pretty clumsy; we should probably
* push something into GMime that makes this a one-shot
* operation. */
if ((protected_headers = g_mime_object_get_header_list (payload), protected_headers) &&
(legacy_display = GMIME_TEXT_PART (first), legacy_display) &&
(legacy_display_header_text = g_mime_text_part_get_text (legacy_display), legacy_display_header_text) &&
(stream = g_mime_stream_mem_new_with_buffer (legacy_display_header_text, strlen (legacy_display_header_text)), stream) &&
(g_mime_stream_write (stream, "\r\n\r\n", 4) == 4) &&
(g_mime_stream_seek (stream, 0, GMIME_STREAM_SEEK_SET) == 0) &&
(parser = g_mime_parser_new_with_stream (stream), parser) &&
(legacy_header_object = g_mime_parser_construct_part (parser, NULL), legacy_header_object) &&
(legacy_display_headers = g_mime_object_get_header_list (legacy_header_object), legacy_display_headers)) {
/* walk through legacy_display_headers, comparing them against
* their values in the protected_headers: */
ret = true;
for (int i = 0; i < g_mime_header_list_get_count (legacy_display_headers); i++) {
GMimeHeader *dh = g_mime_header_list_get_header_at (legacy_display_headers, i);
if (dh == NULL) {
ret = false;
goto DONE;
}
GMimeHeader *ph = g_mime_header_list_get_header (protected_headers, g_mime_header_get_name (dh));
if (ph == NULL) {
ret = false;
goto DONE;
}
const char *dhv = g_mime_header_get_value (dh);
const char *phv = g_mime_header_get_value (ph);
if (dhv == NULL || phv == NULL || strcmp (dhv, phv)) {
ret = false;
goto DONE;
}
}
}
DONE:
if (legacy_display_header_text)
g_free (legacy_display_header_text);
if (stream)
g_object_unref (stream);
if (parser)
g_object_unref (parser);
if (legacy_header_object)
g_object_unref (legacy_header_object);
return ret;
}
GMimeObject *
_notmuch_repair_crypto_payload_skip_legacy_display (GMimeObject *payload)
{
if (_notmuch_crypto_payload_has_legacy_display (payload)) {
return g_mime_multipart_get_part (GMIME_MULTIPART (payload), 1);
} else {
return payload;
}
}
/* 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 *parts[3] = {NULL, NULL, NULL};
GMimeContentType *type = NULL;
char *prelude_string = NULL;
bool prelude_is_empty;
if (part == NULL)
return false;
type = g_mime_object_get_content_type (part);
if (type == NULL)
return false;
if (! g_mime_content_type_is_type (type, "multipart", "mixed"))
return false;
if (! GMIME_IS_MULTIPART (part)) /* probably impossible */
return false;
mpart = GMIME_MULTIPART (part);
if (mpart == NULL)
return false;
if (g_mime_multipart_get_count (mpart) != 3)
return false;
parts[0] = g_mime_multipart_get_part (mpart, 0);
if (! g_mime_content_type_is_type (g_mime_object_get_content_type (parts[0]),
"text", "plain"))
return false;
if (! GMIME_IS_TEXT_PART (parts[0]))
return false;
parts[1] = g_mime_multipart_get_part (mpart, 1);
if (! g_mime_content_type_is_type (g_mime_object_get_content_type (parts[1]),
"application", "pgp-encrypted"))
return false;
parts[2] = g_mime_multipart_get_part (mpart, 2);
if (! g_mime_content_type_is_type (g_mime_object_get_content_type (parts[2]),
"application", "octet-stream"))
return false;
/* Is parts[0] length 0? */
prelude_string = g_mime_text_part_get_text (GMIME_TEXT_PART (parts[0]));
prelude_is_empty = (prelude_string[0] == '\0');
g_free (prelude_string);
if (! prelude_is_empty)
return false;
/* FIXME: after decoding and stripping whitespace, is parts[1]
* subpart just "Version: 1" ? */
/* FIXME: can we determine that parts[2] 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;
}
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