gnutls.c

uclinux 下的vlc播放器源代码

/*****************************************************************************
 * gnutls.c
 *****************************************************************************
 * Copyright (C) 2004-2006 Rémi Denis-Courmont
 * $Id: gnutls.c 19803 2007-04-15 06:46:21Z courmisch $
 *
 * Authors: Rémi Denis-Courmont <rem # videolan.org>
 *
 * 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
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <stdlib.h>
#include <errno.h>
#include <time.h>
#include <vlc/vlc.h>

#include <sys/types.h>
#include <errno.h>
#ifdef HAVE_DIRENT_H
# include <dirent.h>
#endif
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
# ifdef HAVE_UNISTD_H
#  include <unistd.h>
# endif
#endif


#include "vlc_tls.h"
#include "charset.h"

#include <gcrypt.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>

#define DH_BITS             1024
#define CACHE_EXPIRATION    3600
#define CACHE_SIZE          64

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
static int  Open ( vlc_object_t * );
static void Close( vlc_object_t * );

#define DH_BITS_TEXT N_("Diffie-Hellman prime bits")
#define DH_BITS_LONGTEXT N_( \
    "This allows you to modify the Diffie-Hellman prime's number of bits, " \
    "used for TLS or SSL-based server-side encryption. This is generally " \
    "not needed." )

#define CACHE_EXPIRATION_TEXT N_("Expiration time for resumed TLS sessions")
#define CACHE_EXPIRATION_LONGTEXT N_( \
    "It is possible to cache the resumed TLS sessions. This is the expiration "\
    "time of the sessions stored in this cache, in seconds." )

#define CACHE_SIZE_TEXT N_("Number of resumed TLS sessions")
#define CACHE_SIZE_LONGTEXT N_( \
    "This is the maximum number of resumed TLS sessions that " \
    "the cache will hold." )

#define CHECK_CERT_TEXT N_("Check TLS/SSL server certificate validity")
#define CHECK_CERT_LONGTEXT N_( \
    "This ensures that the server certificate is valid " \
    "(i.e. signed by an approved Certification Authority)." )

#define CHECK_HOSTNAME_TEXT N_("Check TLS/SSL server hostname in certificate")
#define CHECK_HOSTNAME_LONGTEXT N_( \
    "This ensures that the server hostname in certificate matches the " \
    "requested host name." )

vlc_module_begin();
    set_shortname( "GnuTLS" );
    set_description( _("GnuTLS TLS encryption layer") );
    set_capability( "tls", 1 );
    set_callbacks( Open, Close );
    set_category( CAT_ADVANCED );
    set_subcategory( SUBCAT_ADVANCED_MISC );

    add_bool( "tls-check-cert", VLC_TRUE, NULL, CHECK_CERT_TEXT,
              CHECK_CERT_LONGTEXT, VLC_FALSE );
    add_bool( "tls-check-hostname", VLC_TRUE, NULL, CHECK_HOSTNAME_TEXT,
              CHECK_HOSTNAME_LONGTEXT, VLC_FALSE );

    add_integer( "gnutls-dh-bits", DH_BITS, NULL, DH_BITS_TEXT,
                 DH_BITS_LONGTEXT, VLC_TRUE );
    add_integer( "gnutls-cache-expiration", CACHE_EXPIRATION, NULL,
                 CACHE_EXPIRATION_TEXT, CACHE_EXPIRATION_LONGTEXT, VLC_TRUE );
    add_integer( "gnutls-cache-size", CACHE_SIZE, NULL, CACHE_SIZE_TEXT,
                 CACHE_SIZE_LONGTEXT, VLC_TRUE );
vlc_module_end();


#define MAX_SESSION_ID    32
#define MAX_SESSION_DATA  1024

typedef struct saved_session_t
{
    char id[MAX_SESSION_ID];
    char data[MAX_SESSION_DATA];

    unsigned i_idlen;
    unsigned i_datalen;
} saved_session_t;


typedef struct tls_server_sys_t
{
    gnutls_certificate_credentials  x509_cred;
    gnutls_dh_params                dh_params;

    struct saved_session_t          *p_cache;
    struct saved_session_t          *p_store;
    int                             i_cache_size;
    vlc_mutex_t                     cache_lock;

    int                             (*pf_handshake2)( tls_session_t * );
} tls_server_sys_t;


typedef struct tls_session_sys_t
{
    gnutls_session  session;
    char            *psz_hostname;
    vlc_bool_t      b_handshaked;
} tls_session_sys_t;


typedef struct tls_client_sys_t
{
    struct tls_session_sys_t       session;
    gnutls_certificate_credentials x509_cred;
} tls_client_sys_t;


static int
_get_Int( vlc_object_t *p_this, const char *var )
{
    vlc_value_t value;

    if( var_Get( p_this, var, &value ) != VLC_SUCCESS )
    {
        var_Create( p_this, var, VLC_VAR_INTEGER | VLC_VAR_DOINHERIT );
        var_Get( p_this, var, &value );
    }

    return value.i_int;
}

static int
_get_Bool( vlc_object_t *p_this, const char *var )
{
    vlc_value_t value;

    if( var_Get( p_this, var, &value ) != VLC_SUCCESS )
    {
        var_Create( p_this, var, VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
        var_Get( p_this, var, &value );
    }

    return value.b_bool;
}

#define get_Int( a, b ) _get_Int( (vlc_object_t *)(a), (b) )
#define get_Bool( a, b ) _get_Bool( (vlc_object_t *)(a), (b) )


static int gnutls_Error (vlc_object_t *obj, int val)
{
    switch (val)
    {
        case GNUTLS_E_AGAIN:
#if defined(WIN32)
            WSASetLastError(WSAEWOULDBLOCK);
#else
            errno = EAGAIN;
#endif
            break;

        case GNUTLS_E_INTERRUPTED:
#if defined(WIN32)
            WSASetLastError(WSAEINTR);
#else
            errno = EINTR;
#endif
            break;

        default:
            msg_Err (obj, "%s", gnutls_strerror (val));
#ifdef DEBUG
            if (!gnutls_error_is_fatal (val))
                msg_Err (obj, "Error above should be handled");
#endif
#if defined(WIN32)
            WSASetLastError(WSAECONNRESET);
#else
            errno = ECONNRESET;
#endif
    }
    return -1;
}


/**
 * Sends data through a TLS session.
 */
static int
gnutls_Send( void *p_session, const void *buf, int i_length )
{
    int val;
    tls_session_sys_t *p_sys;

    p_sys = (tls_session_sys_t *)(((tls_session_t *)p_session)->p_sys);

    val = gnutls_record_send( p_sys->session, buf, i_length );
    return (val < 0) ? gnutls_Error ((vlc_object_t *)p_session, val) : val;
}


/**
 * Receives data through a TLS session.
 */
static int
gnutls_Recv( void *p_session, void *buf, int i_length )
{
    int val;
    tls_session_sys_t *p_sys;

    p_sys = (tls_session_sys_t *)(((tls_session_t *)p_session)->p_sys);

    val = gnutls_record_recv( p_sys->session, buf, i_length );
    return (val < 0) ? gnutls_Error ((vlc_object_t *)p_session, val) : val;
}


/*****************************************************************************
 * tls_Session(Continue)?Handshake:
 *****************************************************************************
 * Establishes TLS session with a peer through socket <fd>.
 * Returns -1 on error (you need not and must not call tls_SessionClose)
 * 0 on succesful handshake completion, 1 if more would-be blocking recv is
 * needed, 2 if more would-be blocking send is required.
 *****************************************************************************/
static int
gnutls_ContinueHandshake( tls_session_t *p_session)
{
    tls_session_sys_t *p_sys;
    int val;

    p_sys = (tls_session_sys_t *)(p_session->p_sys);

     /* TODO: handle fatal error */
#ifdef WIN32
    WSASetLastError( 0 );
#endif
    val = gnutls_handshake( p_sys->session );
    if( ( val == GNUTLS_E_AGAIN ) || ( val == GNUTLS_E_INTERRUPTED ) )
        return 1 + gnutls_record_get_direction( p_sys->session );

    if( val < 0 )
    {
#ifdef WIN32
        msg_Dbg( p_session, "Winsock error %d", WSAGetLastError( ) );
#endif
        msg_Err( p_session, "TLS handshake error: %s",
                 gnutls_strerror( val ) );
        p_session->pf_close( p_session );
        return -1;
    }

    p_sys->b_handshaked = VLC_TRUE;
    return 0;
}

static int
gnutls_VerifyHostname( vlc_object_t *p_this, gnutls_session session,
                       const char *psz_hostname )
{
    const gnutls_datum *p_data;
    gnutls_x509_crt cert;
    unsigned status;
    int val;

    /* certificate (host)name verification */
    p_data = gnutls_certificate_get_peers( session, &status );
    if( p_data == NULL )
    {
        msg_Err( p_this, "TLS peer certificate not available" );
        return -1;
    }

    val = gnutls_x509_crt_init( &cert );
    if( val )
    {
        msg_Err( p_this, "x509 fatal error: %s", gnutls_strerror( val ) );
        return -1;
    }

    val = gnutls_x509_crt_import( cert, p_data, GNUTLS_X509_FMT_DER );
    if( val )
    {
        msg_Err( p_this, "x509 certificate import error: %s",
                gnutls_strerror( val ) );
        gnutls_x509_crt_deinit( cert );
        return -1;
    }

    if( gnutls_x509_crt_check_hostname( cert, psz_hostname ) == 0 )
    {
        msg_Err( p_this, "x509 certificate does not match \"%s\"",
                psz_hostname );
        gnutls_x509_crt_deinit( cert );
        return -1;
    }

    gnutls_x509_crt_deinit( cert );
    msg_Dbg( p_this, "x509 hostname matches %s", psz_hostname );
    return 0;
}


typedef struct
{
    int flag;
    const char *msg;
} error_msg_t;

static const error_msg_t cert_errors[] =
{
    { GNUTLS_CERT_INVALID,
        "Certificate could not be verified" },
    { GNUTLS_CERT_REVOKED,
        "Certificate was revoked" },
    { GNUTLS_CERT_SIGNER_NOT_FOUND,
        "Certificate's signer was not found" },
    { GNUTLS_CERT_SIGNER_NOT_CA,
        "Certificate's signer is not a CA" },
    { GNUTLS_CERT_INSECURE_ALGORITHM,
        "Insecure certificate signature algorithm" },
    { 0, NULL }
};


static int
gnutls_HandshakeAndValidate( tls_session_t *session )
{
    int val = gnutls_ContinueHandshake( session );
    if( val )
        return val;

    tls_session_sys_t *p_sys = (tls_session_sys_t *)(session->p_sys);

    /* certificates chain verification */
    unsigned status;
    val = gnutls_certificate_verify_peers2( p_sys->session, &status );

    if( val )
    {
        msg_Err( session, "Certificate verification failed: %s",
                 gnutls_strerror( val ) );
        goto error;
    }

    if( status )
    {
        const error_msg_t *e;
        msg_Err( session, "TLS session: access denied" );
        for( e = cert_errors; e->flag; e++ )
        {
            if( status & e->flag )
            {
                msg_Err( session, e->msg );
                status &= ~e->flag;
            }
        }

        if( status )
            msg_Err( session,
                     "unknown certificate error (you found a bug in VLC)" );

        goto error;
    }

    /* certificate (host)name verification */
    const gnutls_datum *data = gnutls_certificate_get_peers( p_sys->session,
                                                             &(size_t){ 0 } );
    if( data == NULL )
    {
        msg_Err( session, "Peer certificate not available" );
        goto error;
    }

    gnutls_x509_crt cert;
    val = gnutls_x509_crt_init( &cert );
    if( val )
    {
        msg_Err( session, "x509 fatal error: %s", gnutls_strerror( val ) );
        goto error;
    }

    val = gnutls_x509_crt_import( cert, data, GNUTLS_X509_FMT_DER );
    if( val )
    {
        msg_Err( session, "Certificate import error: %s",
                 gnutls_strerror( val ) );
        goto crt_error;
    }

    if( p_sys->psz_hostname != NULL )
    {
        if ( !gnutls_x509_crt_check_hostname( cert, p_sys->psz_hostname ) )
        {
            msg_Err( session, "Certificate does not match \"%s\"",
                     p_sys->psz_hostname );
            goto crt_error;
        }
    }
    else
        msg_Warn( session, "Certificate and hostname were not verified" );

    if( gnutls_x509_crt_get_expiration_time( cert ) < time( NULL ) )