path: root/camel/camel-pgp-mime.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 *  Authors: Jeffrey Stedfast <fejj@ximian.com>
 *
 *  Copyright 2001 Ximian, Inc. (www.ximian.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * 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, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "camel-pgp-mime.h"
#include "camel-mime-message.h"
#include "camel-mime-filter-from.h"
#include "camel-mime-filter-bestenc.h"
#include "camel-mime-filter-crlf.h"
#include "camel-mime-filter-charset.h"
#include "camel-mime-filter-chomp.h"
#include "camel-stream-filter.h"
#include "camel-stream-null.h"
#include "camel-stream-mem.h"
#include "camel-stream-fs.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PGPMIME_DEBUG

#define d(x) x

/** rfc2015/rfc3156 stuff (aka PGP/MIME) *******************************/

gboolean
camel_pgp_mime_is_rfc2015_signed (CamelMimePart *mime_part)
{
    CamelDataWrapper *wrapper;
    CamelMultipart *mp;
    CamelMimePart *part;
    CamelContentType *type;
#ifdef ENABLE_PEDANTIC_PGPMIME
    const char *param, *micalg;
#endif
    int nparts;
    
    /* check that we have a multipart/signed */
    type = camel_mime_part_get_content_type (mime_part);
    if (!header_content_type_is (type, "multipart", "signed"))
        return FALSE;

#ifdef ENABLE_PEDANTIC_PGPMIME
    /* check that we have a protocol param with the value: "application/pgp-signature" */
    param = header_content_type_param (type, "protocol");
    if (!param || g_strcasecmp (param, "application/pgp-signature"))
        return FALSE;
    
    /* check that we have a micalg parameter */
    micalg = header_content_type_param (type, "micalg");
    if (!micalg)
        return FALSE;
#endif /* ENABLE_PEDANTIC_PGPMIME */
    
    /* check that we have exactly 2 subparts */
    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    mp = CAMEL_MULTIPART (wrapper);
    nparts = camel_multipart_get_number (mp);
    if (nparts != 2)
        return FALSE;
    
    /* The first part may be of any type except for 
     * application/pgp-signature - check it. */
    part = camel_multipart_get_part (mp, 0);
    type = camel_mime_part_get_content_type (part);
    if (header_content_type_is (type, "application", "pgp-signature"))
        return FALSE;
    
    /* The second part should be application/pgp-signature. */
    part = camel_multipart_get_part (mp, 1);
    type = camel_mime_part_get_content_type (part);
    if (!header_content_type_is (type, "application", "pgp-signature"))
        return FALSE;
    
    return TRUE;
}

gboolean
camel_pgp_mime_is_rfc2015_encrypted (CamelMimePart *mime_part)
{
    CamelDataWrapper *wrapper;
    CamelMultipart *mp;
    CamelMimePart *part;
    CamelContentType *type;
#ifdef ENABLE_PEDANTIC_PGPMIME
    const char *param;
#endif
    int nparts;
    
    /* check that we have a multipart/encrypted */
    type = camel_mime_part_get_content_type (mime_part);
    if (!header_content_type_is (type, "multipart", "encrypted"))
        return FALSE;

#ifdef ENABLE_PEDANTIC_PGPMIME
    /* check that we have a protocol param with the value: "application/pgp-encrypted" */
    param = header_content_type_param (type, "protocol");
    if (!param || g_strcasecmp (param, "application/pgp-encrypted"))
        return FALSE;
#endif /* ENABLE_PEDANTIC_PGPMIME */
    
    /* check that we have at least 2 subparts */
    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    mp = CAMEL_MULTIPART (wrapper);
    nparts = camel_multipart_get_number (mp);
    if (nparts < 2)
        return FALSE;
    
    /* The first part should be application/pgp-encrypted */
    part = camel_multipart_get_part (mp, 0);
    type = camel_mime_part_get_content_type (part);
    if (!header_content_type_is (type, "application", "pgp-encrypted"))
        return FALSE;
    
    /* The second part should be application/octet-stream - this
           is the one we care most about */
    part = camel_multipart_get_part (mp, 1);
    type = camel_mime_part_get_content_type (part);
    if (!header_content_type_is (type, "application", "octet-stream"))
        return FALSE;
    
    return TRUE;
}


static void
pgp_mime_part_sign_restore_part (CamelMimePart *mime_part, GSList **encodings)
{
    CamelDataWrapper *wrapper;
    
    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    if (!wrapper)
        return;
    
    if (CAMEL_IS_MULTIPART (wrapper)) {
        int parts, i;
        
        parts = camel_multipart_get_number (CAMEL_MULTIPART (wrapper));
        for (i = 0; i < parts; i++) {
            CamelMimePart *part = camel_multipart_get_part (CAMEL_MULTIPART (wrapper), i);
            
            pgp_mime_part_sign_restore_part (part, encodings);
        }
    } else {
        CamelMimePartEncodingType encoding;
        
        if (CAMEL_IS_MIME_MESSAGE (wrapper)) {
            /* restore the message parts' subparts */
            pgp_mime_part_sign_restore_part (CAMEL_MIME_PART (wrapper), encodings);
        } else {
            encoding = GPOINTER_TO_INT ((*encodings)->data);
            
            camel_mime_part_set_encoding (mime_part, encoding);
            
            *encodings = (*encodings)->next;
        }
    }
}

static void
pgp_mime_part_sign_prepare_part (CamelMimePart *mime_part, GSList **encodings)
{
    CamelDataWrapper *wrapper;
    int parts, i;
    
    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    if (!wrapper)
        return;
    
    if (CAMEL_IS_MULTIPART (wrapper)) {
        parts = camel_multipart_get_number (CAMEL_MULTIPART (wrapper));
        for (i = 0; i < parts; i++) {
            CamelMimePart *part = camel_multipart_get_part (CAMEL_MULTIPART (wrapper), i);
            
            pgp_mime_part_sign_prepare_part (part, encodings);
        }
    } else {
        CamelMimePartEncodingType encoding, best;
        CamelStream *stream, *filtered_stream;
        CamelMimeFilterBestenc *bestenc;
        guint32 flags;
        
        if (CAMEL_IS_MIME_MESSAGE (wrapper)) {
            /* prepare the message parts' subparts */
            pgp_mime_part_sign_prepare_part (CAMEL_MIME_PART (wrapper), encodings);
        } else {
            encoding = camel_mime_part_get_encoding (mime_part);
            
            if (encoding != CAMEL_MIME_PART_ENCODING_BASE64) {
                flags = CAMEL_BESTENC_GET_ENCODING;
                
                stream = camel_stream_null_new ();
                filtered_stream = (CamelStream *) camel_stream_filter_new_with_stream (stream);
                camel_object_unref (CAMEL_OBJECT (stream));
                bestenc = camel_mime_filter_bestenc_new (flags);
                camel_stream_filter_add (CAMEL_STREAM_FILTER (filtered_stream),
                             CAMEL_MIME_FILTER (bestenc));
                
                camel_data_wrapper_write_to_stream (wrapper, filtered_stream);
                
                best = camel_mime_filter_bestenc_get_best_encoding (bestenc, CAMEL_BESTENC_7BIT);
                
                camel_object_unref (CAMEL_OBJECT (filtered_stream));
                camel_object_unref (CAMEL_OBJECT (bestenc));
                
                if (encoding != best) {
                    camel_mime_part_set_encoding (mime_part, best);
                    
                    *encodings = g_slist_append (*encodings, GINT_TO_POINTER (encoding));
                }
            }
        }
    }
}


/**
 * camel_pgp_mime_part_sign:
 * @context: PGP Context
 * @mime_part: a MIME part that will be replaced by a pgp signed part
 * @userid: userid to sign with
 * @hash: one of CAMEL_PGP_HASH_TYPE_MD5 or CAMEL_PGP_HASH_TYPE_SHA1
 * @ex: exception which will be set if there are any errors.
 *
 * Constructs a PGP/MIME multipart in compliance with rfc2015 and
 * replaces @part with the generated multipart/signed. On failure,
 * @ex will be set and #part will remain untouched.
 **/
void
camel_pgp_mime_part_sign (CamelPgpContext *context, CamelMimePart **mime_part, const char *userid,
              CamelCipherHash hash, CamelException *ex)
{
    CamelMimePart *part, *signed_part;
    CamelMultipart *multipart;
    CamelContentType *mime_type;
    CamelStreamFilter *filtered_stream;
    CamelMimeFilter *crlf_filter, *from_filter, *chomp_filter;
    CamelStream *stream, *sigstream;
    GSList *encodings = NULL;
    char *hash_type = NULL;
    
    g_return_if_fail (*mime_part != NULL);
    g_return_if_fail (CAMEL_IS_MIME_PART (*mime_part));
    g_return_if_fail (userid != NULL);
    
    part = *mime_part;
    
    /* Prepare all the parts for signing... */
    pgp_mime_part_sign_prepare_part (part, &encodings);
    
    /* get the cleartext */
    stream = camel_stream_mem_new ();
    filtered_stream = camel_stream_filter_new_with_stream (stream);
    
    /* Note: see rfc3156, section 3 - second note */
    from_filter = CAMEL_MIME_FILTER (camel_mime_filter_from_new ());
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (from_filter));
    camel_object_unref (CAMEL_OBJECT (from_filter));
    
    /* Note: see rfc3156, section 5.4 (this is the big thing that changed between rfc2015 and rfc3156) */
    chomp_filter = camel_mime_filter_chomp_new ();
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (chomp_filter));
    camel_object_unref (CAMEL_OBJECT (chomp_filter));
    
    /* Note: see rfc2015 or rfc3156, section 5.1 */
    crlf_filter = camel_mime_filter_crlf_new (CAMEL_MIME_FILTER_CRLF_ENCODE,
                          CAMEL_MIME_FILTER_CRLF_MODE_CRLF_ONLY);
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (crlf_filter));
    camel_object_unref (CAMEL_OBJECT (crlf_filter));
    
    camel_data_wrapper_write_to_stream (CAMEL_DATA_WRAPPER (part), CAMEL_STREAM (filtered_stream));
    camel_stream_flush (CAMEL_STREAM (filtered_stream));
    camel_object_unref (CAMEL_OBJECT (filtered_stream));
    
    /* reset the stream */
    camel_stream_reset (stream);
    
    printf ("attempting to sign data:\n----- BEGIN SIGNED PART -----\n%.*s----- END SIGNED PART -----\n",
        CAMEL_STREAM_MEM (stream)->buffer->len, CAMEL_STREAM_MEM (stream)->buffer->data);
    
    /* construct the signature stream */
    sigstream = camel_stream_mem_new ();
    
    switch (hash) {
    case CAMEL_CIPHER_HASH_MD2:
        /* this is a new addition with rfc3156 */
        hash_type = "pgp-md2";
        break;
    case CAMEL_CIPHER_HASH_MD5:
        hash_type = "pgp-md5";
        break;
    case CAMEL_CIPHER_HASH_SHA1:
        hash_type = "pgp-sha1";
        break;
    case CAMEL_CIPHER_HASH_RIPEMD160:
        hash_type = "pgp-ripemd160";
        break;
    default:
        /* set a reasonable default */
        hash = CAMEL_CIPHER_HASH_SHA1;
        hash_type = "pgp-sha1";
        break;
    }
    
    /* get the signature */
    if (camel_pgp_sign (context, userid, hash, stream, sigstream, ex) == -1) {
        GSList *list;
        
        camel_object_unref (CAMEL_OBJECT (stream));
        camel_object_unref (CAMEL_OBJECT (sigstream));
        
        /* restore the original encoding */
        list = encodings;
        pgp_mime_part_sign_restore_part (part, &list);
        g_slist_free (encodings);
        return;
    }
    
    camel_object_unref (CAMEL_OBJECT (stream));
    camel_stream_reset (sigstream);
    
    /* we don't need these anymore... */
    g_slist_free (encodings);
    
    /* construct the pgp-signature mime part */
    signed_part = camel_mime_part_new ();
    camel_mime_part_set_content (signed_part, CAMEL_STREAM_MEM (sigstream)->buffer->data,
                     CAMEL_STREAM_MEM (sigstream)->buffer->len,
                     "application/pgp-signature; name=signature.asc");
    camel_mime_part_set_description (signed_part, _("This is a digitally signed message part"));
    camel_object_unref (CAMEL_OBJECT (sigstream));
    
    /* construct the container multipart/signed */
    multipart = camel_multipart_new ();
    
    mime_type = header_content_type_new ("multipart", "signed");
    header_content_type_set_param (mime_type, "micalg", hash_type);
    header_content_type_set_param (mime_type, "protocol", "application/pgp-signature");
    camel_data_wrapper_set_mime_type_field (CAMEL_DATA_WRAPPER (multipart), mime_type);
    header_content_type_unref (mime_type);
    
    camel_multipart_set_boundary (multipart, NULL);
    
    /* add the parts to the multipart */
    camel_multipart_add_part (multipart, part);
    camel_object_unref (CAMEL_OBJECT (part));
    camel_multipart_add_part (multipart, signed_part);
    camel_object_unref (CAMEL_OBJECT (signed_part));
    
    /* replace the input part with the output part */
    *mime_part = camel_mime_part_new ();
    camel_medium_set_content_object (CAMEL_MEDIUM (*mime_part),
                     CAMEL_DATA_WRAPPER (multipart));
    camel_object_unref (CAMEL_OBJECT (multipart));
}


/**
 * camel_pgp_mime_part_verify:
 * @context: PGP Context
 * @mime_part: a multipart/signed MIME Part
 * @ex: exception
 *
 * Returns a CamelCipherValidity on success or NULL on fail.
 **/
CamelCipherValidity *
camel_pgp_mime_part_verify (CamelPgpContext *context, CamelMimePart *mime_part, CamelException *ex)
{
    CamelDataWrapper *wrapper;
    CamelMultipart *multipart;
    CamelMimePart *part, *sigpart;
    CamelStreamFilter *filtered_stream;
    CamelMimeFilter *crlf_filter, *chomp_filter;
    CamelStream *stream, *sigstream;
    CamelCipherValidity *valid;
    
    g_return_val_if_fail (mime_part != NULL, NULL);
    g_return_val_if_fail (CAMEL_IS_MIME_PART (mime_part), NULL);
    
    if (!camel_pgp_mime_is_rfc2015_signed (mime_part))
        return NULL;
    
    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    multipart = CAMEL_MULTIPART (wrapper);
    
    /* get the plain part */
    part = camel_multipart_get_part (multipart, 0);
    stream = camel_stream_mem_new ();
    filtered_stream = camel_stream_filter_new_with_stream (stream);
    
    /* Note: see rfc3156, section 5.4 (this is the big thing that changed between rfc2015 and rfc3156) */
    chomp_filter = camel_mime_filter_chomp_new ();
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (chomp_filter));
    camel_object_unref (CAMEL_OBJECT (chomp_filter));
    
    /* Note: see rfc2015 or rfc3156, section 5.1 */
    crlf_filter = camel_mime_filter_crlf_new (CAMEL_MIME_FILTER_CRLF_ENCODE,
                          CAMEL_MIME_FILTER_CRLF_MODE_CRLF_ONLY);
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (crlf_filter));
    camel_object_unref (CAMEL_OBJECT (crlf_filter));
    
    wrapper = CAMEL_DATA_WRAPPER (part);
    camel_data_wrapper_write_to_stream (wrapper, CAMEL_STREAM (filtered_stream));
    camel_stream_flush (CAMEL_STREAM (filtered_stream));
    camel_object_unref (CAMEL_OBJECT (filtered_stream));
    camel_stream_reset (stream);
    
    /* get the signed part */
    sigpart = camel_multipart_get_part (multipart, 1);
    sigstream = camel_stream_mem_new ();
    camel_data_wrapper_write_to_stream (camel_medium_get_content_object (CAMEL_MEDIUM (sigpart)),
                        sigstream);
    camel_stream_reset (sigstream);
    
    /* verify */
    valid = camel_pgp_verify (context, stream, sigstream, ex);
    
    printf ("attempted to verify data:\n----- BEGIN SIGNED PART -----\n%.*s----- END SIGNED PART -----\n",
        CAMEL_STREAM_MEM (stream)->buffer->len, CAMEL_STREAM_MEM (stream)->buffer->data);
    
    camel_object_unref (CAMEL_OBJECT (sigstream));
    camel_object_unref (CAMEL_OBJECT (stream));
    
    return valid;
}


/**
 * camel_pgp_mime_part_encrypt:
 * @context: PGP Context
 * @mime_part: a MIME part that will be replaced by a pgp encrypted part
 * @recipients: list of recipient PGP Key IDs
 * @ex: exception which will be set if there are any errors.
 *
 * Constructs a PGP/MIME multipart in compliance with rfc2015 and
 * replaces #mime_part with the generated multipart/signed. On failure,
 * #ex will be set and #part will remain untouched.
 **/
void
camel_pgp_mime_part_encrypt (CamelPgpContext *context, CamelMimePart **mime_part,
                 GPtrArray *recipients, CamelException *ex)
{
    CamelMultipart *multipart;
    CamelMimePart *part, *version_part, *encrypted_part;
    CamelContentType *mime_type;
    CamelStreamFilter *filtered_stream;
    CamelMimeFilter *crlf_filter;
    CamelStream *stream, *ciphertext;
    
    g_return_if_fail (*mime_part != NULL);
    g_return_if_fail (CAMEL_IS_MIME_PART (*mime_part));
    g_return_if_fail (recipients != NULL);
    
    part = *mime_part;
    
    /* get the contents */
    stream = camel_stream_mem_new ();
    crlf_filter = camel_mime_filter_crlf_new (CAMEL_MIME_FILTER_CRLF_ENCODE,
                          CAMEL_MIME_FILTER_CRLF_MODE_CRLF_ONLY);
    filtered_stream = camel_stream_filter_new_with_stream (stream);
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (crlf_filter));
    camel_object_unref (CAMEL_OBJECT (crlf_filter));
    camel_data_wrapper_write_to_stream (CAMEL_DATA_WRAPPER (part), CAMEL_STREAM (filtered_stream));
    camel_object_unref (CAMEL_OBJECT (filtered_stream));
    camel_stream_reset (stream);
    
    /* pgp encrypt */
    ciphertext = camel_stream_mem_new ();
    if (camel_pgp_encrypt (context, FALSE, NULL, recipients, stream, ciphertext, ex) == -1) {
        camel_object_unref (CAMEL_OBJECT (stream));
        camel_object_unref (CAMEL_OBJECT (ciphertext));
        return;
    }
    
    camel_object_unref (CAMEL_OBJECT (stream));
    camel_stream_reset (ciphertext);
    
    /* construct the version part */
    version_part = camel_mime_part_new ();
    camel_mime_part_set_encoding (version_part, CAMEL_MIME_PART_ENCODING_7BIT);
    camel_mime_part_set_content (version_part, "Version: 1", strlen ("Version: 1"),
                     "application/pgp-encrypted");
    
    /* construct the pgp-encrypted mime part */
    encrypted_part = camel_mime_part_new ();
    camel_mime_part_set_content (encrypted_part, CAMEL_STREAM_MEM (ciphertext)->buffer->data,
                     CAMEL_STREAM_MEM (ciphertext)->buffer->len,
                     "application/octet-stream; name=encrypted.asc");
    camel_object_unref (CAMEL_OBJECT (ciphertext));
    camel_mime_part_set_encoding (encrypted_part, CAMEL_MIME_PART_ENCODING_7BIT);
    
    /* construct the container multipart/encrypted */
    multipart = camel_multipart_new ();
    
    mime_type = header_content_type_new ("multipart", "encrypted");
    header_content_type_set_param (mime_type, "protocol", "application/pgp-encrypted");
    camel_data_wrapper_set_mime_type_field (CAMEL_DATA_WRAPPER (multipart), mime_type);
    header_content_type_unref (mime_type);
    
    camel_multipart_set_boundary (multipart, NULL);
    
    /* add the parts to the multipart */
    camel_multipart_add_part (multipart, version_part);
    camel_object_unref (CAMEL_OBJECT (version_part));
    camel_multipart_add_part (multipart, encrypted_part);
    camel_object_unref (CAMEL_OBJECT (encrypted_part));
    
    /* replace the input part with the output part */
    camel_object_unref (CAMEL_OBJECT (*mime_part));
    *mime_part = camel_mime_part_new ();
    camel_medium_set_content_object (CAMEL_MEDIUM (*mime_part),
                     CAMEL_DATA_WRAPPER (multipart));
    camel_object_unref (CAMEL_OBJECT (multipart));
}


/**
 * camel_pgp_mime_part_decrypt:
 * @context: PGP Context
 * @mime_part: a multipart/encrypted MIME Part
 * @ex: exception
 *
 * Returns the decrypted MIME Part on success or NULL on fail.
 **/
CamelMimePart *
camel_pgp_mime_part_decrypt (CamelPgpContext *context, CamelMimePart *mime_part, CamelException *ex)
{
    CamelDataWrapper *wrapper;
    CamelMultipart *multipart;
    CamelMimePart *encrypted_part, *part;
    CamelContentType *mime_type;
    CamelStream *stream, *ciphertext;
    CamelStreamFilter *filtered_stream;
    CamelMimeFilter *crlf_filter;
    
    g_return_val_if_fail (mime_part != NULL, NULL);
    g_return_val_if_fail (CAMEL_IS_MIME_PART (mime_part), NULL);
    
    /* make sure the mime part is a multipart/encrypted */
    if (!camel_pgp_mime_is_rfc2015_encrypted (mime_part))
        return NULL;
    
    wrapper = camel_medium_get_content_object (CAMEL_MEDIUM (mime_part));
    multipart = CAMEL_MULTIPART (wrapper);
    
    /* get the encrypted part (second part) */
    encrypted_part = camel_multipart_get_part (multipart, 1 /* second part starting at 0 */);
    mime_type = camel_mime_part_get_content_type (encrypted_part);
    if (!header_content_type_is (mime_type, "application", "octet-stream"))
        return NULL;
    
    /* get the ciphertext */
    ciphertext = camel_stream_mem_new ();
    camel_data_wrapper_write_to_stream (CAMEL_DATA_WRAPPER (encrypted_part), ciphertext);
    camel_stream_reset (ciphertext);
    
    /* get the cleartext */
    stream = camel_stream_mem_new ();
    if (camel_pgp_decrypt (context, ciphertext, stream, ex) == -1) {
        camel_object_unref (CAMEL_OBJECT (ciphertext));
        camel_object_unref (CAMEL_OBJECT (stream));
        return NULL;
    }
    
    camel_object_unref (CAMEL_OBJECT (ciphertext));
    camel_stream_reset (stream);
    
    /* construct the new decrypted mime part from the stream */
    part = camel_mime_part_new ();
    
    crlf_filter = camel_mime_filter_crlf_new (CAMEL_MIME_FILTER_CRLF_DECODE,
                          CAMEL_MIME_FILTER_CRLF_MODE_CRLF_ONLY);
    filtered_stream = camel_stream_filter_new_with_stream (stream);
    camel_object_unref (CAMEL_OBJECT (stream));
    camel_stream_filter_add (filtered_stream, CAMEL_MIME_FILTER (crlf_filter));
    camel_object_unref (CAMEL_OBJECT (crlf_filter));
    
    camel_data_wrapper_construct_from_stream (CAMEL_DATA_WRAPPER (part), CAMEL_STREAM (filtered_stream));
    
    camel_object_unref (CAMEL_OBJECT (filtered_stream));
    
    return part;
}