gnutls.c 38 KB
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/* GnuTLS glue for GNU Emacs.
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   Copyright (C) 2010-2011  Free Software Foundation, Inc.
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This file is part of GNU Emacs.

GNU Emacs 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.

GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>
#include <errno.h>
#include <setjmp.h>

#include "lisp.h"
#include "process.h"

#ifdef HAVE_GNUTLS
#include <gnutls/gnutls.h>

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#ifdef WINDOWSNT
#include <windows.h>
#include "w32.h"
#endif

static int
emacs_gnutls_handle_error (gnutls_session_t, int err);

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static Lisp_Object Qgnutls_dll;
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static Lisp_Object Qgnutls_code;
static Lisp_Object Qgnutls_anon, Qgnutls_x509pki;
static Lisp_Object Qgnutls_e_interrupted, Qgnutls_e_again,
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  Qgnutls_e_invalid_session, Qgnutls_e_not_ready_for_handshake;
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static int gnutls_global_initialized;
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/* The following are for the property list of `gnutls-boot'.  */
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static Lisp_Object Qgnutls_bootprop_priority;
static Lisp_Object Qgnutls_bootprop_trustfiles;
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static Lisp_Object Qgnutls_bootprop_keylist;
static Lisp_Object Qgnutls_bootprop_crlfiles;
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static Lisp_Object Qgnutls_bootprop_callbacks;
static Lisp_Object Qgnutls_bootprop_loglevel;
static Lisp_Object Qgnutls_bootprop_hostname;
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static Lisp_Object Qgnutls_bootprop_min_prime_bits;
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static Lisp_Object Qgnutls_bootprop_verify_flags;
static Lisp_Object Qgnutls_bootprop_verify_hostname_error;
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/* Callback keys for `gnutls-boot'.  Unused currently.  */
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static Lisp_Object Qgnutls_bootprop_callbacks_verify;
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static void gnutls_log_function (int, const char *);
static void gnutls_log_function2 (int, const char*, const char*);


#ifdef WINDOWSNT

/* Macro for defining functions that will be loaded from the GnuTLS DLL.  */
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#define DEF_GNUTLS_FN(rettype,func,args) static rettype (FAR CDECL *fn_##func)args
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/* Macro for loading GnuTLS functions from the library.  */
#define LOAD_GNUTLS_FN(lib,func) {					\
    fn_##func = (void *) GetProcAddress (lib, #func);			\
    if (!fn_##func) return 0;						\
  }

DEF_GNUTLS_FN (gnutls_alert_description_t, gnutls_alert_get,
               (gnutls_session_t));
DEF_GNUTLS_FN (const char *, gnutls_alert_get_name,
               (gnutls_alert_description_t));
DEF_GNUTLS_FN (int, gnutls_alert_send_appropriate, (gnutls_session_t, int));
DEF_GNUTLS_FN (int, gnutls_anon_allocate_client_credentials,
               (gnutls_anon_client_credentials_t *));
DEF_GNUTLS_FN (void, gnutls_anon_free_client_credentials,
               (gnutls_anon_client_credentials_t));
DEF_GNUTLS_FN (int, gnutls_bye, (gnutls_session_t, gnutls_close_request_t));
DEF_GNUTLS_FN (int, gnutls_certificate_allocate_credentials,
               (gnutls_certificate_credentials_t *));
DEF_GNUTLS_FN (void, gnutls_certificate_free_credentials,
               (gnutls_certificate_credentials_t));
DEF_GNUTLS_FN (const gnutls_datum_t *, gnutls_certificate_get_peers,
               (gnutls_session_t, unsigned int *));
DEF_GNUTLS_FN (void, gnutls_certificate_set_verify_flags,
               (gnutls_certificate_credentials_t, unsigned int));
DEF_GNUTLS_FN (int, gnutls_certificate_set_x509_crl_file,
               (gnutls_certificate_credentials_t, const char *,
                gnutls_x509_crt_fmt_t));
DEF_GNUTLS_FN (int, gnutls_certificate_set_x509_key_file,
               (gnutls_certificate_credentials_t, const char *, const char *,
                gnutls_x509_crt_fmt_t));
DEF_GNUTLS_FN (int, gnutls_certificate_set_x509_trust_file,
               (gnutls_certificate_credentials_t, const char *,
                gnutls_x509_crt_fmt_t));
DEF_GNUTLS_FN (gnutls_certificate_type_t, gnutls_certificate_type_get,
               (gnutls_session_t));
DEF_GNUTLS_FN (int, gnutls_certificate_verify_peers2,
               (gnutls_session_t, unsigned int *));
DEF_GNUTLS_FN (int, gnutls_credentials_set,
               (gnutls_session_t, gnutls_credentials_type_t, void *));
DEF_GNUTLS_FN (void, gnutls_deinit, (gnutls_session_t));
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DEF_GNUTLS_FN (void, gnutls_dh_set_prime_bits,
               (gnutls_session_t, unsigned int));
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DEF_GNUTLS_FN (int, gnutls_error_is_fatal, (int));
DEF_GNUTLS_FN (int, gnutls_global_init, (void));
DEF_GNUTLS_FN (void, gnutls_global_set_log_function, (gnutls_log_func));
DEF_GNUTLS_FN (void, gnutls_global_set_log_level, (int));
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DEF_GNUTLS_FN (void, gnutls_global_set_mem_functions,
	       (gnutls_alloc_function, gnutls_alloc_function,
		gnutls_is_secure_function, gnutls_realloc_function,
		gnutls_free_function));
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DEF_GNUTLS_FN (int, gnutls_handshake, (gnutls_session_t));
DEF_GNUTLS_FN (int, gnutls_init, (gnutls_session_t *, gnutls_connection_end_t));
DEF_GNUTLS_FN (int, gnutls_priority_set_direct,
               (gnutls_session_t, const char *, const char **));
DEF_GNUTLS_FN (size_t, gnutls_record_check_pending, (gnutls_session_t));
DEF_GNUTLS_FN (ssize_t, gnutls_record_recv, (gnutls_session_t, void *, size_t));
DEF_GNUTLS_FN (ssize_t, gnutls_record_send,
               (gnutls_session_t, const void *, size_t));
DEF_GNUTLS_FN (const char *, gnutls_strerror, (int));
DEF_GNUTLS_FN (void, gnutls_transport_set_errno, (gnutls_session_t, int));
DEF_GNUTLS_FN (void, gnutls_transport_set_lowat, (gnutls_session_t, int));
DEF_GNUTLS_FN (void, gnutls_transport_set_ptr2,
               (gnutls_session_t, gnutls_transport_ptr_t,
                gnutls_transport_ptr_t));
DEF_GNUTLS_FN (void, gnutls_transport_set_pull_function,
               (gnutls_session_t, gnutls_pull_func));
DEF_GNUTLS_FN (void, gnutls_transport_set_push_function,
               (gnutls_session_t, gnutls_push_func));
DEF_GNUTLS_FN (int, gnutls_x509_crt_check_hostname,
               (gnutls_x509_crt_t, const char *));
DEF_GNUTLS_FN (void, gnutls_x509_crt_deinit, (gnutls_x509_crt_t));
DEF_GNUTLS_FN (int, gnutls_x509_crt_import,
               (gnutls_x509_crt_t, const gnutls_datum_t *,
                gnutls_x509_crt_fmt_t));
DEF_GNUTLS_FN (int, gnutls_x509_crt_init, (gnutls_x509_crt_t *));

static int
init_gnutls_functions (Lisp_Object libraries)
{
  HMODULE library;
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  int max_log_level = 1;
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  if (!(library = w32_delayed_load (libraries, Qgnutls_dll)))
    {
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      GNUTLS_LOG (1, max_log_level, "GnuTLS library not found");
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      return 0;
    }

  LOAD_GNUTLS_FN (library, gnutls_alert_get);
  LOAD_GNUTLS_FN (library, gnutls_alert_get_name);
  LOAD_GNUTLS_FN (library, gnutls_alert_send_appropriate);
  LOAD_GNUTLS_FN (library, gnutls_anon_allocate_client_credentials);
  LOAD_GNUTLS_FN (library, gnutls_anon_free_client_credentials);
  LOAD_GNUTLS_FN (library, gnutls_bye);
  LOAD_GNUTLS_FN (library, gnutls_certificate_allocate_credentials);
  LOAD_GNUTLS_FN (library, gnutls_certificate_free_credentials);
  LOAD_GNUTLS_FN (library, gnutls_certificate_get_peers);
  LOAD_GNUTLS_FN (library, gnutls_certificate_set_verify_flags);
  LOAD_GNUTLS_FN (library, gnutls_certificate_set_x509_crl_file);
  LOAD_GNUTLS_FN (library, gnutls_certificate_set_x509_key_file);
  LOAD_GNUTLS_FN (library, gnutls_certificate_set_x509_trust_file);
  LOAD_GNUTLS_FN (library, gnutls_certificate_type_get);
  LOAD_GNUTLS_FN (library, gnutls_certificate_verify_peers2);
  LOAD_GNUTLS_FN (library, gnutls_credentials_set);
  LOAD_GNUTLS_FN (library, gnutls_deinit);
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  LOAD_GNUTLS_FN (library, gnutls_dh_set_prime_bits);
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  LOAD_GNUTLS_FN (library, gnutls_error_is_fatal);
  LOAD_GNUTLS_FN (library, gnutls_global_init);
  LOAD_GNUTLS_FN (library, gnutls_global_set_log_function);
  LOAD_GNUTLS_FN (library, gnutls_global_set_log_level);
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  LOAD_GNUTLS_FN (library, gnutls_global_set_mem_functions);
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  LOAD_GNUTLS_FN (library, gnutls_handshake);
  LOAD_GNUTLS_FN (library, gnutls_init);
  LOAD_GNUTLS_FN (library, gnutls_priority_set_direct);
  LOAD_GNUTLS_FN (library, gnutls_record_check_pending);
  LOAD_GNUTLS_FN (library, gnutls_record_recv);
  LOAD_GNUTLS_FN (library, gnutls_record_send);
  LOAD_GNUTLS_FN (library, gnutls_strerror);
  LOAD_GNUTLS_FN (library, gnutls_transport_set_errno);
  LOAD_GNUTLS_FN (library, gnutls_transport_set_lowat);
  LOAD_GNUTLS_FN (library, gnutls_transport_set_ptr2);
  LOAD_GNUTLS_FN (library, gnutls_transport_set_pull_function);
  LOAD_GNUTLS_FN (library, gnutls_transport_set_push_function);
  LOAD_GNUTLS_FN (library, gnutls_x509_crt_check_hostname);
  LOAD_GNUTLS_FN (library, gnutls_x509_crt_deinit);
  LOAD_GNUTLS_FN (library, gnutls_x509_crt_import);
  LOAD_GNUTLS_FN (library, gnutls_x509_crt_init);

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  max_log_level = global_gnutls_log_level;
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  GNUTLS_LOG2 (1, max_log_level, "GnuTLS library loaded:",
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               SDATA (Fget (Qgnutls_dll, QCloaded_from)));
  return 1;
}

#else /* !WINDOWSNT */

#define fn_gnutls_alert_get			gnutls_alert_get
#define fn_gnutls_alert_get_name		gnutls_alert_get_name
#define fn_gnutls_alert_send_appropriate	gnutls_alert_send_appropriate
#define fn_gnutls_anon_allocate_client_credentials gnutls_anon_allocate_client_credentials
#define fn_gnutls_anon_free_client_credentials	gnutls_anon_free_client_credentials
#define fn_gnutls_bye				gnutls_bye
#define fn_gnutls_certificate_allocate_credentials gnutls_certificate_allocate_credentials
#define fn_gnutls_certificate_free_credentials	gnutls_certificate_free_credentials
#define fn_gnutls_certificate_get_peers		gnutls_certificate_get_peers
#define fn_gnutls_certificate_set_verify_flags	gnutls_certificate_set_verify_flags
#define fn_gnutls_certificate_set_x509_crl_file	gnutls_certificate_set_x509_crl_file
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#define fn_gnutls_certificate_set_x509_key_file gnutls_certificate_set_x509_key_file
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#define fn_gnutls_certificate_set_x509_trust_file gnutls_certificate_set_x509_trust_file
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#define fn_gnutls_certificate_type_get		gnutls_certificate_type_get
#define fn_gnutls_certificate_verify_peers2	gnutls_certificate_verify_peers2
#define fn_gnutls_credentials_set		gnutls_credentials_set
#define fn_gnutls_deinit			gnutls_deinit
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#define fn_gnutls_dh_set_prime_bits		gnutls_dh_set_prime_bits
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#define fn_gnutls_error_is_fatal		gnutls_error_is_fatal
#define fn_gnutls_global_init			gnutls_global_init
#define fn_gnutls_global_set_log_function	gnutls_global_set_log_function
#define fn_gnutls_global_set_log_level		gnutls_global_set_log_level
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#define fn_gnutls_global_set_mem_functions	gnutls_global_set_mem_functions
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#define fn_gnutls_handshake			gnutls_handshake
#define fn_gnutls_init				gnutls_init
#define fn_gnutls_priority_set_direct		gnutls_priority_set_direct
#define fn_gnutls_record_check_pending		gnutls_record_check_pending
#define fn_gnutls_record_recv			gnutls_record_recv
#define fn_gnutls_record_send			gnutls_record_send
#define fn_gnutls_strerror			gnutls_strerror
#define fn_gnutls_transport_set_errno		gnutls_transport_set_errno
#define fn_gnutls_transport_set_ptr2		gnutls_transport_set_ptr2
#define fn_gnutls_x509_crt_check_hostname	gnutls_x509_crt_check_hostname
#define fn_gnutls_x509_crt_deinit		gnutls_x509_crt_deinit
#define fn_gnutls_x509_crt_import		gnutls_x509_crt_import
#define fn_gnutls_x509_crt_init			gnutls_x509_crt_init

#endif /* !WINDOWSNT */


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static void
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gnutls_log_function (int level, const char* string)
{
  message ("gnutls.c: [%d] %s", level, string);
}

static void
gnutls_log_function2 (int level, const char* string, const char* extra)
{
  message ("gnutls.c: [%d] %s %s", level, string, extra);
}

static int
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emacs_gnutls_handshake (struct Lisp_Process *proc)
{
  gnutls_session_t state = proc->gnutls_state;
  int ret;

  if (proc->gnutls_initstage < GNUTLS_STAGE_HANDSHAKE_CANDO)
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    return -1;
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  if (proc->gnutls_initstage < GNUTLS_STAGE_TRANSPORT_POINTERS_SET)
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    {
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#ifdef WINDOWSNT
      /* On W32 we cannot transfer socket handles between different runtime
         libraries, so we tell GnuTLS to use our special push/pull
         functions.  */
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      fn_gnutls_transport_set_ptr2 (state,
                                    (gnutls_transport_ptr_t) proc,
                                    (gnutls_transport_ptr_t) proc);
      fn_gnutls_transport_set_push_function (state, &emacs_gnutls_push);
      fn_gnutls_transport_set_pull_function (state, &emacs_gnutls_pull);
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      /* For non blocking sockets or other custom made pull/push
         functions the gnutls_transport_set_lowat must be called, with
         a zero low water mark value. (GnuTLS 2.10.4 documentation)

         (Note: this is probably not strictly necessary as the lowat
          value is only used when no custom pull/push functions are
          set.)  */
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      fn_gnutls_transport_set_lowat (state, 0);
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#else
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      /* This is how GnuTLS takes sockets: as file descriptors passed
         in.  For an Emacs process socket, infd and outfd are the
         same but we use this two-argument version for clarity.  */
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      fn_gnutls_transport_set_ptr2 (state,
                                    (gnutls_transport_ptr_t) (long) proc->infd,
                                    (gnutls_transport_ptr_t) (long) proc->outfd);
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#endif
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      proc->gnutls_initstage = GNUTLS_STAGE_TRANSPORT_POINTERS_SET;
    }
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  do
    {
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      ret = fn_gnutls_handshake (state);
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      emacs_gnutls_handle_error (state, ret);
    }
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  while (ret < 0 && fn_gnutls_error_is_fatal (ret) == 0);
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  proc->gnutls_initstage = GNUTLS_STAGE_HANDSHAKE_TRIED;

  if (ret == GNUTLS_E_SUCCESS)
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    {
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      /* Here we're finally done.  */
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      proc->gnutls_initstage = GNUTLS_STAGE_READY;
    }
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  else
    {
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      fn_gnutls_alert_send_appropriate (state, ret);
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    }
  return ret;
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}

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int
emacs_gnutls_record_check_pending (gnutls_session_t state)
{
  return fn_gnutls_record_check_pending (state);
}

void
emacs_gnutls_transport_set_errno (gnutls_session_t state, int err)
{
  fn_gnutls_transport_set_errno (state, err);
}

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EMACS_INT
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emacs_gnutls_write (struct Lisp_Process *proc, const char *buf, EMACS_INT nbyte)
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{
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  ssize_t rtnval = 0;
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  EMACS_INT bytes_written;
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  gnutls_session_t state = proc->gnutls_state;

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  if (proc->gnutls_initstage != GNUTLS_STAGE_READY) {
#ifdef EWOULDBLOCK
    errno = EWOULDBLOCK;
#endif
#ifdef EAGAIN
    errno = EAGAIN;
#endif
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    return 0;
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  }
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  bytes_written = 0;

  while (nbyte > 0)
    {
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      rtnval = fn_gnutls_record_send (state, buf, nbyte);
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      if (rtnval < 0)
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        {
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          if (rtnval == GNUTLS_E_AGAIN || rtnval == GNUTLS_E_INTERRUPTED)
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            continue;
          else
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            break;
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        }

      buf += rtnval;
      nbyte -= rtnval;
      bytes_written += rtnval;
    }

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  emacs_gnutls_handle_error (state, rtnval);
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  return (bytes_written);
}

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EMACS_INT
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emacs_gnutls_read (struct Lisp_Process *proc, char *buf, EMACS_INT nbyte)
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{
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  ssize_t rtnval;
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  gnutls_session_t state = proc->gnutls_state;

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  if (proc->gnutls_initstage != GNUTLS_STAGE_READY)
    {
      emacs_gnutls_handshake (proc);
      return -1;
    }
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  rtnval = fn_gnutls_record_recv (state, buf, nbyte);
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  if (rtnval >= 0)
    return rtnval;
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  else if (rtnval == GNUTLS_E_UNEXPECTED_PACKET_LENGTH)
    /* The peer closed the connection. */
    return 0;
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  else if (emacs_gnutls_handle_error (state, rtnval) == 0)
    /* non-fatal error */
    return -1;
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  else {
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    /* a fatal error occurred */
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    return 0;
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  }
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}

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/* report a GnuTLS error to the user.
   Returns zero if the error code was successfully handled. */
static int
emacs_gnutls_handle_error (gnutls_session_t session, int err)
{
  int max_log_level = 0;

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  int ret;
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  const char *str;

  /* TODO: use a Lisp_Object generated by gnutls_make_error?  */
  if (err >= 0)
    return 0;

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  max_log_level = global_gnutls_log_level;
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  /* TODO: use gnutls-error-fatalp and gnutls-error-string.  */

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  str = fn_gnutls_strerror (err);
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  if (!str)
    str = "unknown";

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  if (fn_gnutls_error_is_fatal (err))
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    {
      ret = err;
      GNUTLS_LOG2 (0, max_log_level, "fatal error:", str);
    }
  else
    {
      ret = 0;
      GNUTLS_LOG2 (1, max_log_level, "non-fatal error:", str);
      /* TODO: EAGAIN AKA Qgnutls_e_again should be level 2.  */
    }

  if (err == GNUTLS_E_WARNING_ALERT_RECEIVED
      || err == GNUTLS_E_FATAL_ALERT_RECEIVED)
    {
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      int alert = fn_gnutls_alert_get (session);
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      int level = (err == GNUTLS_E_FATAL_ALERT_RECEIVED) ? 0 : 1;
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      str = fn_gnutls_alert_get_name (alert);
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      if (!str)
	str = "unknown";

      GNUTLS_LOG2 (level, max_log_level, "Received alert: ", str);
    }
  return ret;
}

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/* convert an integer error to a Lisp_Object; it will be either a
   known symbol like `gnutls_e_interrupted' and `gnutls_e_again' or
   simply the integer value of the error.  GNUTLS_E_SUCCESS is mapped
   to Qt.  */
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static Lisp_Object
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gnutls_make_error (int err)
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{
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  switch (err)
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    {
    case GNUTLS_E_SUCCESS:
      return Qt;
    case GNUTLS_E_AGAIN:
      return Qgnutls_e_again;
    case GNUTLS_E_INTERRUPTED:
      return Qgnutls_e_interrupted;
    case GNUTLS_E_INVALID_SESSION:
      return Qgnutls_e_invalid_session;
    }
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  return make_number (err);
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}

DEFUN ("gnutls-get-initstage", Fgnutls_get_initstage, Sgnutls_get_initstage, 1, 1, 0,
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       doc: /* Return the GnuTLS init stage of process PROC.
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See also `gnutls-boot'.  */)
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  (Lisp_Object proc)
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{
  CHECK_PROCESS (proc);

  return make_number (GNUTLS_INITSTAGE (proc));
}

DEFUN ("gnutls-errorp", Fgnutls_errorp, Sgnutls_errorp, 1, 1, 0,
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       doc: /* Return t if ERROR indicates a GnuTLS problem.
ERROR is an integer or a symbol with an integer `gnutls-code' property.
usage: (gnutls-errorp ERROR)  */)
  (Lisp_Object err)
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{
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  if (EQ (err, Qt)) return Qnil;
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  return Qt;
}

DEFUN ("gnutls-error-fatalp", Fgnutls_error_fatalp, Sgnutls_error_fatalp, 1, 1, 0,
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       doc: /* Check if ERROR is fatal.
ERROR is an integer or a symbol with an integer `gnutls-code' property.
usage: (gnutls-error-fatalp ERROR)  */)
  (Lisp_Object err)
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{
  Lisp_Object code;

  if (EQ (err, Qt)) return Qnil;

  if (SYMBOLP (err))
    {
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      code = Fget (err, Qgnutls_code);
      if (NUMBERP (code))
	{
	  err = code;
	}
      else
	{
	  error ("Symbol has no numeric gnutls-code property");
	}
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    }

  if (!NUMBERP (err))
    error ("Not an error symbol or code");

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  if (0 == fn_gnutls_error_is_fatal (XINT (err)))
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    return Qnil;

  return Qt;
}

DEFUN ("gnutls-error-string", Fgnutls_error_string, Sgnutls_error_string, 1, 1, 0,
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       doc: /* Return a description of ERROR.
ERROR is an integer or a symbol with an integer `gnutls-code' property.
usage: (gnutls-error-string ERROR)  */)
  (Lisp_Object err)
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{
  Lisp_Object code;

  if (EQ (err, Qt)) return build_string ("Not an error");

  if (SYMBOLP (err))
    {
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      code = Fget (err, Qgnutls_code);
      if (NUMBERP (code))
	{
	  err = code;
	}
      else
	{
	  return build_string ("Symbol has no numeric gnutls-code property");
	}
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    }

  if (!NUMBERP (err))
    return build_string ("Not an error symbol or code");

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  return build_string (fn_gnutls_strerror (XINT (err)));
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}

DEFUN ("gnutls-deinit", Fgnutls_deinit, Sgnutls_deinit, 1, 1, 0,
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       doc: /* Deallocate GnuTLS resources associated with process PROC.
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See also `gnutls-init'.  */)
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  (Lisp_Object proc)
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{
  gnutls_session_t state;

  CHECK_PROCESS (proc);
  state = XPROCESS (proc)->gnutls_state;

  if (GNUTLS_INITSTAGE (proc) >= GNUTLS_STAGE_INIT)
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    {
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      fn_gnutls_deinit (state);
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      GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_INIT - 1;
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    }
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  return Qt;
}

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DEFUN ("gnutls-available-p", Fgnutls_available_p, Sgnutls_available_p, 0, 0, 0,
       doc: /* Return t if GnuTLS is available in this instance of Emacs.  */)
     (void)
{
#ifdef WINDOWSNT
  Lisp_Object found = Fassq (Qgnutls_dll, Vlibrary_cache);
  if (CONSP (found))
    return XCDR (found);
  else
    {
      Lisp_Object status;
      status = init_gnutls_functions (Vdynamic_library_alist) ? Qt : Qnil;
      Vlibrary_cache = Fcons (Fcons (Qgnutls_dll, status), Vlibrary_cache);
      return status;
    }
#else
  return Qt;
#endif
}


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/* Initializes global GnuTLS state to defaults.
Call `gnutls-global-deinit' when GnuTLS usage is no longer needed.
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Returns zero on success.  */
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static Lisp_Object
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emacs_gnutls_global_init (void)
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{
  int ret = GNUTLS_E_SUCCESS;

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  if (!gnutls_global_initialized)
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    {
      fn_gnutls_global_set_mem_functions (xmalloc, xmalloc, NULL,
					  xrealloc, xfree);
      ret = fn_gnutls_global_init ();
    }
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  gnutls_global_initialized = 1;
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  return gnutls_make_error (ret);
}

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#if 0
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/* Deinitializes global GnuTLS state.
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See also `gnutls-global-init'.  */
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static Lisp_Object
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emacs_gnutls_global_deinit (void)
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{
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  if (gnutls_global_initialized)
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    gnutls_global_deinit ();

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  gnutls_global_initialized = 0;
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  return gnutls_make_error (GNUTLS_E_SUCCESS);
}
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#endif
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DEFUN ("gnutls-boot", Fgnutls_boot, Sgnutls_boot, 3, 3, 0,
       doc: /* Initialize GnuTLS client for process PROC with TYPE+PROPLIST.
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Currently only client mode is supported.  Returns a success/failure
value you can check with `gnutls-errorp'.

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TYPE is a symbol, either `gnutls-anon' or `gnutls-x509pki'.
PROPLIST is a property list with the following keys:

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:hostname is a string naming the remote host.

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:priority is a GnuTLS priority string, defaults to "NORMAL".
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:trustfiles is a list of PEM-encoded trust files for `gnutls-x509pki'.
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:crlfiles is a list of PEM-encoded CRL lists for `gnutls-x509pki'.

:keylist is an alist of PEM-encoded key files and PEM-encoded
certificates for `gnutls-x509pki'.
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:callbacks is an alist of callback functions, see below.

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:loglevel is the debug level requested from GnuTLS, try 4.
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:verify-flags is a bitset as per GnuTLS'
gnutls_certificate_set_verify_flags.

:verify-hostname-error, if non-nil, makes a hostname mismatch an
error.  Otherwise it will be just a warning.

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:min-prime-bits is the minimum accepted number of bits the client will
accept in Diffie-Hellman key exchange.

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The debug level will be set for this process AND globally for GnuTLS.
So if you set it higher or lower at any point, it affects global
debugging.
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Note that the priority is set on the client.  The server does not use
the protocols's priority except for disabling protocols that were not
specified.

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Processes must be initialized with this function before other GnuTLS
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functions are used.  This function allocates resources which can only
be deallocated by calling `gnutls-deinit' or by calling it again.

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The callbacks alist can have a `verify' key, associated with a
verification function (UNUSED).

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Each authentication type may need additional information in order to
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work.  For X.509 PKI (`gnutls-x509pki'), you probably need at least
one trustfile (usually a CA bundle).  */)
  (Lisp_Object proc, Lisp_Object type, Lisp_Object proplist)
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{
  int ret = GNUTLS_E_SUCCESS;

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  int max_log_level = 0;

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  /* TODO: GNUTLS_X509_FMT_DER is also an option.  */
  int file_format = GNUTLS_X509_FMT_PEM;

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  unsigned int gnutls_verify_flags = GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT;
  gnutls_x509_crt_t gnutls_verify_cert;
  unsigned int gnutls_verify_cert_list_size;
  const gnutls_datum_t *gnutls_verify_cert_list;

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  gnutls_session_t state;
  gnutls_certificate_credentials_t x509_cred;
  gnutls_anon_client_credentials_t anon_cred;
  Lisp_Object global_init;
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  char const *priority_string_ptr = "NORMAL"; /* default priority string.  */
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  Lisp_Object tail;
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  unsigned int peer_verification;
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  char* c_hostname;
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  /* Placeholders for the property list elements.  */
  Lisp_Object priority_string;
  Lisp_Object trustfiles;
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  Lisp_Object crlfiles;
  Lisp_Object keylist;
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  /* Lisp_Object callbacks; */
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  Lisp_Object loglevel;
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  Lisp_Object hostname;
  Lisp_Object verify_flags;
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  /* Lisp_Object verify_error; */
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  Lisp_Object verify_hostname_error;
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  Lisp_Object prime_bits;
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  CHECK_PROCESS (proc);
  CHECK_SYMBOL (type);
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  CHECK_LIST (proplist);

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  if (NILP (Fgnutls_available_p ()))
    {
      error ("GnuTLS not available");
      return gnutls_make_error (GNUTLS_EMACS_ERROR_NOT_LOADED);
    }

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  hostname              = Fplist_get (proplist, Qgnutls_bootprop_hostname);
  priority_string       = Fplist_get (proplist, Qgnutls_bootprop_priority);
  trustfiles            = Fplist_get (proplist, Qgnutls_bootprop_trustfiles);
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  keylist               = Fplist_get (proplist, Qgnutls_bootprop_keylist);
  crlfiles              = Fplist_get (proplist, Qgnutls_bootprop_crlfiles);
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  /* callbacks          = Fplist_get (proplist, Qgnutls_bootprop_callbacks); */
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  loglevel              = Fplist_get (proplist, Qgnutls_bootprop_loglevel);
  verify_flags          = Fplist_get (proplist, Qgnutls_bootprop_verify_flags);
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  /* verify_error       = Fplist_get (proplist, Qgnutls_bootprop_verify_error); */
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  verify_hostname_error = Fplist_get (proplist, Qgnutls_bootprop_verify_hostname_error);
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  prime_bits            = Fplist_get (proplist, Qgnutls_bootprop_min_prime_bits);
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  if (!STRINGP (hostname))
    error ("gnutls-boot: invalid :hostname parameter");

  c_hostname = SSDATA (hostname);
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  state = XPROCESS (proc)->gnutls_state;
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  XPROCESS (proc)->gnutls_p = 1;
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  if (NUMBERP (loglevel))
    {
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      fn_gnutls_global_set_log_function (gnutls_log_function);
      fn_gnutls_global_set_log_level (XINT (loglevel));
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      max_log_level = XINT (loglevel);
      XPROCESS (proc)->gnutls_log_level = max_log_level;
    }
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  /* always initialize globals.  */
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  global_init = emacs_gnutls_global_init ();
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  if (! NILP (Fgnutls_errorp (global_init)))
    return global_init;

  /* deinit and free resources.  */
  if (GNUTLS_INITSTAGE (proc) >= GNUTLS_STAGE_CRED_ALLOC)
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    {
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      GNUTLS_LOG (1, max_log_level, "deallocating credentials");

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      if (EQ (type, Qgnutls_x509pki))
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	{
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          GNUTLS_LOG (2, max_log_level, "deallocating x509 credentials");
          x509_cred = XPROCESS (proc)->gnutls_x509_cred;
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          fn_gnutls_certificate_free_credentials (x509_cred);
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	}
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      else if (EQ (type, Qgnutls_anon))
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	{
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          GNUTLS_LOG (2, max_log_level, "deallocating anon credentials");
          anon_cred = XPROCESS (proc)->gnutls_anon_cred;
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          fn_gnutls_anon_free_client_credentials (anon_cred);
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	}
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      else
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	{
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          error ("unknown credential type");
          ret = GNUTLS_EMACS_ERROR_INVALID_TYPE;
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	}
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      if (GNUTLS_INITSTAGE (proc) >= GNUTLS_STAGE_INIT)
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	{
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          GNUTLS_LOG (1, max_log_level, "deallocating x509 credentials");
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          Fgnutls_deinit (proc);
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	}
    }
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  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_EMPTY;

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  GNUTLS_LOG (1, max_log_level, "allocating credentials");

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  if (EQ (type, Qgnutls_x509pki))
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    {
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      GNUTLS_LOG (2, max_log_level, "allocating x509 credentials");
      x509_cred = XPROCESS (proc)->gnutls_x509_cred;
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      fn_gnutls_certificate_allocate_credentials (&x509_cred);
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      if (NUMBERP (verify_flags))
        {
          gnutls_verify_flags = XINT (verify_flags);
          GNUTLS_LOG (2, max_log_level, "setting verification flags");
        }
      else if (NILP (verify_flags))
        {
          /* The default is already GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT.  */
          GNUTLS_LOG (2, max_log_level, "using default verification flags");
        }
      else
        {
          /* The default is already GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT.  */
          GNUTLS_LOG (2, max_log_level, "ignoring invalid verify-flags");
        }
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      fn_gnutls_certificate_set_verify_flags (x509_cred, gnutls_verify_flags);
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    }
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  else if (EQ (type, Qgnutls_anon))
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    {
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      GNUTLS_LOG (2, max_log_level, "allocating anon credentials");
      anon_cred = XPROCESS (proc)->gnutls_anon_cred;
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      fn_gnutls_anon_allocate_client_credentials (&anon_cred);
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    }
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  else
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    {
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      error ("unknown credential type");
      ret = GNUTLS_EMACS_ERROR_INVALID_TYPE;
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    }
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  if (ret < GNUTLS_E_SUCCESS)
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    return gnutls_make_error (ret);
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  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_CRED_ALLOC;

  if (EQ (type, Qgnutls_x509pki))
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    {
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      for (tail = trustfiles; !NILP (tail); tail = Fcdr (tail))
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	{
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	  Lisp_Object trustfile = Fcar (tail);
          if (STRINGP (trustfile))
            {
              GNUTLS_LOG2 (1, max_log_level, "setting the trustfile: ",
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                           SSDATA (trustfile));
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              ret = fn_gnutls_certificate_set_x509_trust_file
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                (x509_cred,
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                 SSDATA (trustfile),
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                 file_format);
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              if (ret < GNUTLS_E_SUCCESS)
                return gnutls_make_error (ret);
            }
          else
            {
              error ("Sorry, GnuTLS can't use non-string trustfile %s",
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                     SDATA (trustfile));
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            }
        }
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      for (tail = crlfiles; !NILP (tail); tail = Fcdr (tail))
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	{
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	  Lisp_Object crlfile = Fcar (tail);
          if (STRINGP (crlfile))
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            {
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              GNUTLS_LOG2 (1, max_log_level, "setting the CRL file: ",
                           SSDATA (crlfile));
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              ret = fn_gnutls_certificate_set_x509_crl_file
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                (x509_cred,
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                 SSDATA (crlfile),
                 file_format);

              if (ret < GNUTLS_E_SUCCESS)
                return gnutls_make_error (ret);
            }
          else
            {
              error ("Sorry, GnuTLS can't use non-string CRL file %s",
                     SDATA (crlfile));
            }
        }

      for (tail = keylist; !NILP (tail); tail = Fcdr (tail))
	{
	  Lisp_Object keyfile = Fcar (Fcar (tail));
	  Lisp_Object certfile = Fcar (Fcdr (tail));
          if (STRINGP (keyfile) && STRINGP (certfile))
            {
              GNUTLS_LOG2 (1, max_log_level, "setting the client key file: ",
                           SSDATA (keyfile));
              GNUTLS_LOG2 (1, max_log_level, "setting the client cert file: ",
                           SSDATA (certfile));
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              ret = fn_gnutls_certificate_set_x509_key_file
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                (x509_cred,
                 SSDATA (certfile),
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                 SSDATA (keyfile),
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                 file_format);
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              if (ret < GNUTLS_E_SUCCESS)
                return gnutls_make_error (ret);
            }
          else
            {
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              if (STRINGP (keyfile))
                error ("Sorry, GnuTLS can't use non-string client cert file %s",
                       SDATA (certfile));
              else
                error ("Sorry, GnuTLS can't use non-string client key file %s",
                       SDATA (keyfile));
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            }
        }
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    }
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  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_FILES;

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  GNUTLS_LOG (1, max_log_level, "gnutls callbacks");

  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_CALLBACKS;

#ifdef HAVE_GNUTLS_CALLBACK_CERTIFICATE_VERIFY
#else
#endif

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  GNUTLS_LOG (1, max_log_level, "gnutls_init");

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  ret = fn_gnutls_init (&state, GNUTLS_CLIENT);
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  if (ret < GNUTLS_E_SUCCESS)
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    return gnutls_make_error (ret);
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  XPROCESS (proc)->gnutls_state = state;

  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_INIT;

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  if (STRINGP (priority_string))
    {
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      priority_string_ptr = SSDATA (priority_string);
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      GNUTLS_LOG2 (1, max_log_level, "got non-default priority string:",
                   priority_string_ptr);
    }
  else
    {
      GNUTLS_LOG2 (1, max_log_level, "using default priority string:",
                   priority_string_ptr);
    }
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  GNUTLS_LOG (1, max_log_level, "setting the priority string");

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  ret = fn_gnutls_priority_set_direct (state,
                                       priority_string_ptr,
                                       NULL);
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  if (ret < GNUTLS_E_SUCCESS)
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    return gnutls_make_error (ret);
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  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_PRIORITY;

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  if (!EQ (prime_bits, Qnil))
    {
      fn_gnutls_dh_set_prime_bits (state, XUINT (prime_bits));
    }

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  if (EQ (type, Qgnutls_x509pki))
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    {
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      ret = fn_gnutls_credentials_set (state, GNUTLS_CRD_CERTIFICATE, x509_cred);
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    }
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  else if (EQ (type, Qgnutls_anon))
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    {
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      ret = fn_gnutls_credentials_set (state, GNUTLS_CRD_ANON, anon_cred);
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    }
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  else
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    {
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      error ("unknown credential type");
      ret = GNUTLS_EMACS_ERROR_INVALID_TYPE;
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    }
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  if (ret < GNUTLS_E_SUCCESS)
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    return gnutls_make_error (ret);
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  XPROCESS (proc)->gnutls_anon_cred = anon_cred;
  XPROCESS (proc)->gnutls_x509_cred = x509_cred;
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  XPROCESS (proc)->gnutls_cred_type = type;

  GNUTLS_INITSTAGE (proc) = GNUTLS_STAGE_CRED_SET;

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  ret = emacs_gnutls_handshake (XPROCESS (proc));
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  if (ret < GNUTLS_E_SUCCESS)
    return gnutls_make_error (ret);

  /* Now verify the peer, following
     http://www.gnu.org/software/gnutls/manual/html_node/Verifying-peer_0027s-certificate.html.
     The peer should present at least one certificate in the chain; do a
     check of the certificate's hostname with
     gnutls_x509_crt_check_hostname() against :hostname.  */

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  ret = fn_gnutls_certificate_verify_peers2 (state, &peer_verification);
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  if (ret < GNUTLS_E_SUCCESS)
    return gnutls_make_error (ret);
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  if (XINT (loglevel) > 0 && peer_verification & GNUTLS_CERT_INVALID)
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    message ("%s certificate could not be verified.",
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             c_hostname);
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 if (peer_verification & GNUTLS_CERT_REVOKED)
   GNUTLS_LOG2 (1, max_log_level, "certificate was revoked (CRL):",
                c_hostname);
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 if (peer_verification & GNUTLS_CERT_SIGNER_NOT_FOUND)
   GNUTLS_LOG2 (1, max_log_level, "certificate signer was not found:",
                c_hostname);