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![Werner Koch](/assets/img/avatar_default.png)
* tools/wks-receive.c (decrypt_data): Change limit. -- The former limit ~1MiB of was used during development. Signed-off-by: Werner Koch <wk@gnupg.org>
535 lines
14 KiB
C
535 lines
14 KiB
C
/* wks-receive.c - Receive a WKS mail
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* Copyright (C) 2016 g10 Code GmbH
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* Copyright (C) 2016 Bundesamt für Sicherheit in der Informationstechnik
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*
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* This file is part of GnuPG.
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "../common/util.h"
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#include "../common/ccparray.h"
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#include "../common/exectool.h"
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#include "gpg-wks.h"
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#include "rfc822parse.h"
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#include "mime-parser.h"
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/* Limit of acceptable signed data. */
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#define MAX_SIGNEDDATA 10000
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/* Limit of acceptable signature. */
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#define MAX_SIGNATURE 10000
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/* Limit of acceptable encrypted data. */
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#define MAX_ENCRYPTED 100000
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/* Data for a received object. */
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struct receive_ctx_s
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{
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mime_parser_t parser;
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estream_t encrypted;
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estream_t plaintext;
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estream_t signeddata;
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estream_t signature;
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estream_t key_data;
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estream_t wkd_data;
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unsigned int collect_key_data:1;
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unsigned int collect_wkd_data:1;
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unsigned int draft_version_2:1; /* This is a draft version 2 request. */
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unsigned int multipart_mixed_seen:1;
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};
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typedef struct receive_ctx_s *receive_ctx_t;
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static void
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decrypt_data_status_cb (void *opaque, const char *keyword, char *args)
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{
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receive_ctx_t ctx = opaque;
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(void)ctx;
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if (DBG_CRYPTO)
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log_debug ("gpg status: %s %s\n", keyword, args);
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}
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/* Decrypt the collected data. */
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static void
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decrypt_data (receive_ctx_t ctx)
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{
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gpg_error_t err;
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ccparray_t ccp;
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const char **argv;
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int c;
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es_rewind (ctx->encrypted);
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if (!ctx->plaintext)
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ctx->plaintext = es_fopenmem (0, "w+b");
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if (!ctx->plaintext)
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{
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err = gpg_error_from_syserror ();
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log_error ("error allocating space for plaintext: %s\n",
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gpg_strerror (err));
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return;
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}
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ccparray_init (&ccp, 0);
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ccparray_put (&ccp, "--no-options");
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/* We limit the output to 64 KiB to avoid DoS using compression
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* tricks. A regular client will anyway only send a minimal key;
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* that is one w/o key signatures and attribute packets. */
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ccparray_put (&ccp, "--max-output=0x10000");
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ccparray_put (&ccp, "--batch");
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if (opt.verbose)
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ccparray_put (&ccp, "--verbose");
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ccparray_put (&ccp, "--always-trust");
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ccparray_put (&ccp, "--decrypt");
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ccparray_put (&ccp, "--");
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ccparray_put (&ccp, NULL);
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argv = ccparray_get (&ccp, NULL);
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if (!argv)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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err = gnupg_exec_tool_stream (opt.gpg_program, argv, ctx->encrypted,
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NULL, ctx->plaintext,
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decrypt_data_status_cb, ctx);
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if (err)
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{
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log_error ("decryption failed: %s\n", gpg_strerror (err));
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goto leave;
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}
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if (DBG_CRYPTO)
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{
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es_rewind (ctx->plaintext);
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log_debug ("plaintext: '");
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while ((c = es_getc (ctx->plaintext)) != EOF)
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log_printf ("%c", c);
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log_printf ("'\n");
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}
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es_rewind (ctx->plaintext);
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leave:
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xfree (argv);
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}
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static void
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verify_signature_status_cb (void *opaque, const char *keyword, char *args)
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{
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receive_ctx_t ctx = opaque;
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(void)ctx;
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if (DBG_CRYPTO)
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log_debug ("gpg status: %s %s\n", keyword, args);
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}
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/* Verify the signed data. */
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static void
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verify_signature (receive_ctx_t ctx)
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{
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gpg_error_t err;
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ccparray_t ccp;
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const char **argv;
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log_assert (ctx->signeddata);
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log_assert (ctx->signature);
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es_rewind (ctx->signeddata);
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es_rewind (ctx->signature);
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ccparray_init (&ccp, 0);
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ccparray_put (&ccp, "--no-options");
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ccparray_put (&ccp, "--batch");
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if (opt.verbose)
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ccparray_put (&ccp, "--verbose");
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ccparray_put (&ccp, "--enable-special-filenames");
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ccparray_put (&ccp, "--status-fd=2");
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ccparray_put (&ccp, "--always-trust"); /* To avoid trustdb checks. */
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ccparray_put (&ccp, "--verify");
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ccparray_put (&ccp, "--");
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ccparray_put (&ccp, "-&@INEXTRA@");
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ccparray_put (&ccp, "-");
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ccparray_put (&ccp, NULL);
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argv = ccparray_get (&ccp, NULL);
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if (!argv)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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err = gnupg_exec_tool_stream (opt.gpg_program, argv, ctx->signeddata,
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ctx->signature, NULL,
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verify_signature_status_cb, ctx);
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if (err)
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{
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log_error ("verification failed: %s\n", gpg_strerror (err));
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goto leave;
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}
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log_debug ("Fixme: Verification result is not used\n");
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leave:
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xfree (argv);
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}
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static gpg_error_t
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collect_encrypted (void *cookie, const char *data)
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{
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receive_ctx_t ctx = cookie;
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if (!ctx->encrypted)
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if (!(ctx->encrypted = es_fopenmem (MAX_ENCRYPTED, "w+b,samethread")))
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return gpg_error_from_syserror ();
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if (data)
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es_fputs (data, ctx->encrypted);
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if (es_ferror (ctx->encrypted))
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return gpg_error_from_syserror ();
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if (!data)
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{
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decrypt_data (ctx);
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}
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return 0;
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}
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static gpg_error_t
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collect_signeddata (void *cookie, const char *data)
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{
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receive_ctx_t ctx = cookie;
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if (!ctx->signeddata)
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if (!(ctx->signeddata = es_fopenmem (MAX_SIGNEDDATA, "w+b,samethread")))
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return gpg_error_from_syserror ();
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if (data)
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es_fputs (data, ctx->signeddata);
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if (es_ferror (ctx->signeddata))
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return gpg_error_from_syserror ();
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return 0;
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}
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static gpg_error_t
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collect_signature (void *cookie, const char *data)
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{
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receive_ctx_t ctx = cookie;
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if (!ctx->signature)
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if (!(ctx->signature = es_fopenmem (MAX_SIGNATURE, "w+b,samethread")))
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return gpg_error_from_syserror ();
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if (data)
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es_fputs (data, ctx->signature);
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if (es_ferror (ctx->signature))
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return gpg_error_from_syserror ();
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if (!data)
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{
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verify_signature (ctx);
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}
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return 0;
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}
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/* The callback for the transition from header to body. We use it to
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* look at some header values. */
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static gpg_error_t
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t2body (void *cookie, int level)
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{
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receive_ctx_t ctx = cookie;
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rfc822parse_t msg;
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char *value;
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size_t valueoff;
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log_info ("t2body for level %d\n", level);
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if (!level)
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{
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/* This is the outermost header. */
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msg = mime_parser_rfc822parser (ctx->parser);
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if (msg)
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{
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value = rfc822parse_get_field (msg, "Wks-Draft-Version",
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-1, &valueoff);
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if (value)
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{
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if (atoi(value+valueoff) >= 2 )
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ctx->draft_version_2 = 1;
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free (value);
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}
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}
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}
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return 0;
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}
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static gpg_error_t
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new_part (void *cookie, const char *mediatype, const char *mediasubtype)
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{
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receive_ctx_t ctx = cookie;
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gpg_error_t err = 0;
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ctx->collect_key_data = 0;
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ctx->collect_wkd_data = 0;
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if (!strcmp (mediatype, "application")
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&& !strcmp (mediasubtype, "pgp-keys"))
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{
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log_info ("new '%s/%s' message part\n", mediatype, mediasubtype);
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if (ctx->key_data)
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{
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log_error ("we already got a key - ignoring this part\n");
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err = gpg_error (GPG_ERR_FALSE);
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}
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else
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{
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ctx->key_data = es_fopenmem (0, "w+b");
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if (!ctx->key_data)
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{
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err = gpg_error_from_syserror ();
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log_error ("error allocating space for key: %s\n",
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gpg_strerror (err));
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}
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else
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{
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ctx->collect_key_data = 1;
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err = gpg_error (GPG_ERR_TRUE); /* We want the part decoded. */
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}
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}
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}
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else if (!strcmp (mediatype, "application")
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&& !strcmp (mediasubtype, "vnd.gnupg.wks"))
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{
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log_info ("new '%s/%s' message part\n", mediatype, mediasubtype);
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if (ctx->wkd_data)
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{
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log_error ("we already got a wkd part - ignoring this part\n");
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err = gpg_error (GPG_ERR_FALSE);
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}
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else
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{
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ctx->wkd_data = es_fopenmem (0, "w+b");
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if (!ctx->wkd_data)
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{
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err = gpg_error_from_syserror ();
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log_error ("error allocating space for key: %s\n",
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gpg_strerror (err));
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}
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else
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{
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ctx->collect_wkd_data = 1;
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err = gpg_error (GPG_ERR_TRUE); /* We want the part decoded. */
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}
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}
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}
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else if (!strcmp (mediatype, "multipart")
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&& !strcmp (mediasubtype, "mixed"))
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{
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ctx->multipart_mixed_seen = 1;
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}
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else if (!strcmp (mediatype, "text"))
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{
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/* Check that we receive a text part only after a
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* application/mixed. This is actually a too simple test and we
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* should eventually employ a strict MIME structure check. */
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if (!ctx->multipart_mixed_seen)
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err = gpg_error (GPG_ERR_UNEXPECTED_MSG);
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}
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else
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{
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log_error ("unexpected '%s/%s' message part\n", mediatype, mediasubtype);
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err = gpg_error (GPG_ERR_FALSE); /* We do not want the part. */
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}
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return err;
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}
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static gpg_error_t
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part_data (void *cookie, const void *data, size_t datalen)
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{
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receive_ctx_t ctx = cookie;
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if (data)
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{
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if (DBG_MIME)
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log_debug ("part_data: '%.*s'\n", (int)datalen, (const char*)data);
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if (ctx->collect_key_data)
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{
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if (es_write (ctx->key_data, data, datalen, NULL)
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|| es_fputs ("\n", ctx->key_data))
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return gpg_error_from_syserror ();
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}
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if (ctx->collect_wkd_data)
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{
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if (es_write (ctx->wkd_data, data, datalen, NULL)
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|| es_fputs ("\n", ctx->wkd_data))
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return gpg_error_from_syserror ();
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}
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}
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else
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{
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if (DBG_MIME)
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log_debug ("part_data: finished\n");
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ctx->collect_key_data = 0;
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ctx->collect_wkd_data = 0;
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}
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return 0;
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}
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/* Receive a WKS mail from FP and process it accordingly. On success
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* the RESULT_CB is called with the mediatype and a stream with the
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* decrypted data. */
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gpg_error_t
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wks_receive (estream_t fp,
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gpg_error_t (*result_cb)(void *opaque,
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const char *mediatype,
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estream_t data,
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unsigned int flags),
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void *cb_data)
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{
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gpg_error_t err;
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receive_ctx_t ctx;
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mime_parser_t parser;
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estream_t plaintext = NULL;
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int c;
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unsigned int flags = 0;
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ctx = xtrycalloc (1, sizeof *ctx);
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if (!ctx)
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return gpg_error_from_syserror ();
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err = mime_parser_new (&parser, ctx);
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if (err)
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goto leave;
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if (DBG_PARSER)
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mime_parser_set_verbose (parser, 1);
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mime_parser_set_t2body (parser, t2body);
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mime_parser_set_new_part (parser, new_part);
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mime_parser_set_part_data (parser, part_data);
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mime_parser_set_collect_encrypted (parser, collect_encrypted);
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mime_parser_set_collect_signeddata (parser, collect_signeddata);
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mime_parser_set_collect_signature (parser, collect_signature);
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ctx->parser = parser;
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err = mime_parser_parse (parser, fp);
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if (err)
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goto leave;
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if (ctx->key_data)
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log_info ("key data found\n");
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if (ctx->wkd_data)
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log_info ("wkd data found\n");
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if (ctx->draft_version_2)
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{
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log_info ("draft version 2 requested\n");
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flags |= WKS_RECEIVE_DRAFT2;
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}
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if (ctx->plaintext)
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{
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if (opt.verbose)
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log_info ("parsing decrypted message\n");
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plaintext = ctx->plaintext;
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ctx->plaintext = NULL;
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if (ctx->encrypted)
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es_rewind (ctx->encrypted);
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if (ctx->signeddata)
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es_rewind (ctx->signeddata);
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if (ctx->signature)
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es_rewind (ctx->signature);
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err = mime_parser_parse (parser, plaintext);
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if (err)
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return err;
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}
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if (!ctx->key_data && !ctx->wkd_data)
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{
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log_error ("no suitable data found in the message\n");
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err = gpg_error (GPG_ERR_NO_DATA);
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goto leave;
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}
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if (ctx->key_data)
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{
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if (DBG_MIME)
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{
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es_rewind (ctx->key_data);
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log_debug ("Key: '");
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log_printf ("\n");
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while ((c = es_getc (ctx->key_data)) != EOF)
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log_printf ("%c", c);
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log_printf ("'\n");
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}
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if (result_cb)
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{
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es_rewind (ctx->key_data);
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err = result_cb (cb_data, "application/pgp-keys",
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ctx->key_data, flags);
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if (err)
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goto leave;
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}
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}
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if (ctx->wkd_data)
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{
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if (DBG_MIME)
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{
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es_rewind (ctx->wkd_data);
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log_debug ("WKD: '");
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log_printf ("\n");
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while ((c = es_getc (ctx->wkd_data)) != EOF)
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log_printf ("%c", c);
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log_printf ("'\n");
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}
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if (result_cb)
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{
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es_rewind (ctx->wkd_data);
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err = result_cb (cb_data, "application/vnd.gnupg.wks",
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ctx->wkd_data, flags);
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if (err)
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goto leave;
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}
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}
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leave:
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es_fclose (plaintext);
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mime_parser_release (parser);
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ctx->parser = NULL;
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es_fclose (ctx->encrypted);
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es_fclose (ctx->plaintext);
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es_fclose (ctx->signeddata);
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es_fclose (ctx->signature);
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es_fclose (ctx->key_data);
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es_fclose (ctx->wkd_data);
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xfree (ctx);
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return err;
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}
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