source: lib/ssl_gnutls.c @ 57b4525

  /********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2004 Wilmer van der Gaast and others                *
  \********************************************************************/

/* SSL module - GnuTLS version                                          */

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#include <gnutls/gnutls.h>
#include <gcrypt.h>
#include <fcntl.h>
#include <unistd.h>
#include "proxy.h"
#include "ssl_client.h"
#include "sock.h"
#include "stdlib.h"

int ssl_errno = 0;

static gboolean initialized = FALSE;

#include <limits.h>

#if defined(ULONG_MAX) && ULONG_MAX > 4294967295UL
#define GNUTLS_STUPID_CAST (long)
#else
#define GNUTLS_STUPID_CAST (int)
#endif

struct scd
{
        ssl_input_function func;
        gpointer data;
        int fd;
        gboolean established;
        int inpa;
        
        gnutls_session session;
        gnutls_certificate_credentials xcred;
};

static gboolean ssl_connected( gpointer data, gint source, b_input_condition cond );
static gboolean ssl_starttls_real( gpointer data, gint source, b_input_condition cond );
static gboolean ssl_handshake( gpointer data, gint source, b_input_condition cond );


void ssl_init( void )
{
        if( initialized )
                return;
        
        gnutls_global_init();
        initialized = TRUE;
        atexit( gnutls_global_deinit );
}

void *ssl_connect( char *host, int port, ssl_input_function func, gpointer data )
{
        struct scd *conn = g_new0( struct scd, 1 );
        
        conn->fd = proxy_connect( host, port, ssl_connected, conn );
        conn->func = func;
        conn->data = data;
        conn->inpa = -1;
        
        if( conn->fd < 0 )
        {
                g_free( conn );
                return NULL;
        }
        
        return conn;
}

void *ssl_starttls( int fd, ssl_input_function func, gpointer data )
{
        struct scd *conn = g_new0( struct scd, 1 );
        
        conn->fd = fd;
        conn->func = func;
        conn->data = data;
        conn->inpa = -1;
        
        /* This function should be called via a (short) timeout instead of
           directly from here, because these SSL calls are *supposed* to be
           *completely* asynchronous and not ready yet when this function
           (or *_connect, for examle) returns. Also, errors are reported via
           the callback function, not via this function's return value.
           
           In short, doing things like this makes the rest of the code a lot
           simpler. */
        
        b_timeout_add( 1, ssl_starttls_real, conn );
        
        return conn;
}

static gboolean ssl_starttls_real( gpointer data, gint source, b_input_condition cond )
{
        struct scd *conn = data;
        
        return ssl_connected( conn, conn->fd, B_EV_IO_WRITE );
}

static gboolean ssl_connected( gpointer data, gint source, b_input_condition cond )
{
        struct scd *conn = data;
        
        if( source == -1 )
        {
                conn->func( conn->data, NULL, cond );
                g_free( conn );
                return FALSE;
        }
        
        ssl_init();
        
        gnutls_certificate_allocate_credentials( &conn->xcred );
        gnutls_init( &conn->session, GNUTLS_CLIENT );
        gnutls_transport_set_lowat( conn->session, 1 ); 
        gnutls_set_default_priority( conn->session );
        gnutls_credentials_set( conn->session, GNUTLS_CRD_CERTIFICATE, conn->xcred );
        
        sock_make_nonblocking( conn->fd );
        gnutls_transport_set_ptr( conn->session, (gnutls_transport_ptr) GNUTLS_STUPID_CAST conn->fd );
        
        return ssl_handshake( data, source, cond );
}

static gboolean ssl_handshake( gpointer data, gint source, b_input_condition cond )
{
        struct scd *conn = data;
        int st;
        
        if( ( st = gnutls_handshake( conn->session ) ) < 0 )
        {
                if( st == GNUTLS_E_AGAIN || st == GNUTLS_E_INTERRUPTED )
                {
                        conn->inpa = b_input_add( conn->fd, ssl_getdirection( conn ),
                                                  ssl_handshake, data );
                }
                else
                {
                        conn->func( conn->data, NULL, cond );
                        
                        gnutls_deinit( conn->session );
                        gnutls_certificate_free_credentials( conn->xcred );
                        closesocket( conn->fd );
                        
                        g_free( conn );
                }
        }
        else
        {
                /* For now we can't handle non-blocking perfectly everywhere... */
                sock_make_blocking( conn->fd );
                
                conn->established = TRUE;
                conn->func( conn->data, conn, cond );
        }
        
        return FALSE;
}

int ssl_read( void *conn, char *buf, int len )
{
        int st;
        
        if( !((struct scd*)conn)->established )
        {
                ssl_errno = SSL_NOHANDSHAKE;
                return( -1 );
        }
        
        st = gnutls_record_recv( ((struct scd*)conn)->session, buf, len );
        
        ssl_errno = SSL_OK;
        if( st == GNUTLS_E_AGAIN || st == GNUTLS_E_INTERRUPTED )
                ssl_errno = SSL_AGAIN;
        
        if( 0 && getenv( "BITLBEE_DEBUG" ) && st > 0 ) len = write( 1, buf, st );
        
        return st;
}

int ssl_write( void *conn, const char *buf, int len )
{
        int st;
        
        if( !((struct scd*)conn)->established )
        {
                ssl_errno = SSL_NOHANDSHAKE;
                return( -1 );
        }
        
        st = gnutls_record_send( ((struct scd*)conn)->session, buf, len );
        
        ssl_errno = SSL_OK;
        if( st == GNUTLS_E_AGAIN || st == GNUTLS_E_INTERRUPTED )
                ssl_errno = SSL_AGAIN;
        
        if( 0 && getenv( "BITLBEE_DEBUG" ) && st > 0 ) len = write( 1, buf, st );
        
        return st;
}

/* See ssl_openssl.c for an explanation. */
int ssl_pending( void *conn )
{
        return 0;
}

void ssl_disconnect( void *conn_ )
{
        struct scd *conn = conn_;
        
        if( conn->inpa != -1 )
                b_event_remove( conn->inpa );
        
        if( conn->established )
                gnutls_bye( conn->session, GNUTLS_SHUT_WR );
        
        closesocket( conn->fd );
        
        if( conn->session )
                gnutls_deinit( conn->session );
        if( conn->xcred )
                gnutls_certificate_free_credentials( conn->xcred );
        g_free( conn );
}

int ssl_getfd( void *conn )
{
        return( ((struct scd*)conn)->fd );
}

b_input_condition ssl_getdirection( void *conn )
{
        return( gnutls_record_get_direction( ((struct scd*)conn)->session ) ?
                B_EV_IO_WRITE : B_EV_IO_READ );
}

size_t ssl_des3_encrypt( const unsigned char *key, size_t key_len, const unsigned char *input,
                         size_t input_len, const unsigned char *iv, unsigned char **res )
{
        gcry_cipher_hd_t gcr;
        gcry_error_t st;
        
        ssl_init();
        
        *res = g_malloc( input_len  );
        st = gcry_cipher_open( &gcr, GCRY_CIPHER_3DES, GCRY_CIPHER_MODE_CBC, 0 ) ||
             gcry_cipher_setkey( gcr, key, key_len ) ||
             gcry_cipher_setiv( gcr, iv, 8 ) ||
             gcry_cipher_encrypt( gcr, *res, input_len, input, input_len );
        
        gcry_cipher_close( gcr );
        
        if( st == 0 )
                return input_len;
        
        g_free( *res );
        return 0;
}