gnutls.c

VLC Player Source Code

#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;


static int cb_store( void *p_server, gnutls_datum key, gnutls_datum data )
{
    tls_server_sys_t *p_sys = ((tls_server_t *)p_server)->p_sys;

    if( ( p_sys->i_cache_size == 0 )
     || ( key.size > MAX_SESSION_ID )
     || ( data.size > MAX_SESSION_DATA ) )
        return -1;

    vlc_mutex_lock( &p_sys->cache_lock );

    memcpy( p_sys->p_store->id, key.data, key.size);
    memcpy( p_sys->p_store->data, data.data, data.size );
    p_sys->p_store->i_idlen = key.size;
    p_sys->p_store->i_datalen = data.size;

    p_sys->p_store++;
    if( ( p_sys->p_store - p_sys->p_cache ) == p_sys->i_cache_size )
        p_sys->p_store = p_sys->p_cache;

    vlc_mutex_unlock( &p_sys->cache_lock );

    return 0;
}


static gnutls_datum cb_fetch( void *p_server, gnutls_datum key )
{
    static const gnutls_datum_t err_datum = { NULL, 0 };
    tls_server_sys_t *p_sys = ((tls_server_t *)p_server)->p_sys;
    saved_session_t *p_session, *p_end;

    p_session = p_sys->p_cache;
    p_end = p_session + p_sys->i_cache_size;

    vlc_mutex_lock( &p_sys->cache_lock );

    while( p_session < p_end )
    {
        if( ( p_session->i_idlen == key.size )
         && !memcmp( p_session->id, key.data, key.size ) )
        {
            gnutls_datum_t data;

            data.size = p_session->i_datalen;

            data.data = gnutls_malloc( data.size );
            if( data.data == NULL )
            {
                vlc_mutex_unlock( &p_sys->cache_lock );
                return err_datum;
            }

            memcpy( data.data, p_session->data, data.size );
            vlc_mutex_unlock( &p_sys->cache_lock );
            return data;
        }
        p_session++;
    }

    vlc_mutex_unlock( &p_sys->cache_lock );

    return err_datum;
}


static int cb_delete( void *p_server, gnutls_datum key )
{
    tls_server_sys_t *p_sys = ((tls_server_t *)p_server)->p_sys;
    saved_session_t *p_session, *p_end;

    p_session = p_sys->p_cache;
    p_end = p_session + p_sys->i_cache_size;

    vlc_mutex_lock( &p_sys->cache_lock );

    while( p_session < p_end )
    {
        if( ( p_session->i_idlen == key.size )
         && !memcmp( p_session->id, key.data, key.size ) )
        {
            p_session->i_datalen = p_session->i_idlen = 0;
            vlc_mutex_unlock( &p_sys->cache_lock );
            return 0;
        }
        p_session++;
    }

    vlc_mutex_unlock( &p_sys->cache_lock );

    return -1;
}


/**
 * Terminates TLS session and releases session data.
 * You still have to close the socket yourself.
 */
static void
gnutls_SessionClose (tls_server_t *p_server, tls_session_t *p_session)
{
    tls_session_sys_t *p_sys = p_session->p_sys;
    (void)p_server;

    if( p_sys->b_handshaked == true )
        gnutls_bye( p_sys->session, GNUTLS_SHUT_WR );
    gnutls_deinit( p_sys->session );

    vlc_object_detach( p_session );
    vlc_object_release( p_session );

    free( p_sys );
}


/**
 * Initializes a server-side TLS session.
 */
static tls_session_t *
gnutls_ServerSessionPrepare( tls_server_t *p_server )
{
    tls_session_t *p_session;
    tls_server_sys_t *p_server_sys;
    gnutls_session_t session;
    int i_val;

    p_session = vlc_object_create( p_server, sizeof (struct tls_session_t) );
    if( p_session == NULL )
        return NULL;

    p_session->p_sys = malloc( sizeof(struct tls_session_sys_t) );
    if( p_session->p_sys == NULL )
    {
        vlc_object_release( p_session );
        return NULL;
    }

    p_server_sys = p_server->p_sys;
    p_session->sock.p_sys = p_session;
    p_session->sock.pf_send = gnutls_Send;
    p_session->sock.pf_recv = gnutls_Recv;
    p_session->pf_set_fd = gnutls_SetFD;
    p_session->pf_handshake = p_server_sys->pf_handshake;

    p_session->p_sys->b_handshaked = false;
    p_session->p_sys->psz_hostname = NULL;

    i_val = gnutls_init( &session, GNUTLS_SERVER );
    if( i_val != 0 )
    {
        msg_Err( p_server, "cannot initialize TLS session: %s",
                 gnutls_strerror( i_val ) );
        goto error;
    }

    p_session->p_sys->session = session;

    if (gnutls_SessionPrioritize (VLC_OBJECT (p_session), session))
    {
        gnutls_deinit( session );
        goto error;
    }

    i_val = gnutls_credentials_set( session, GNUTLS_CRD_CERTIFICATE,
                                    p_server_sys->x509_cred );
    if( i_val < 0 )
    {
        msg_Err( p_server, "cannot set TLS session credentials: %s",
                 gnutls_strerror( i_val ) );
        gnutls_deinit( session );
        goto error;
    }

    if (p_session->pf_handshake == gnutls_HandshakeAndValidate)
        gnutls_certificate_server_set_request (session, GNUTLS_CERT_REQUIRE);

    /* Session resumption support */
    i_val = config_GetInt (p_server, "gnutls-cache-timeout");
    gnutls_db_set_cache_expiration (session, i_val);
    gnutls_db_set_retrieve_function( session, cb_fetch );
    gnutls_db_set_remove_function( session, cb_delete );
    gnutls_db_set_store_function( session, cb_store );
    gnutls_db_set_ptr( session, p_server );

    return p_session;

error:
    free( p_session->p_sys );
    vlc_object_detach( p_session );
    vlc_object_release( p_session );
    return NULL;
}


/**
 * Adds one or more certificate authorities.
 *
 * @param psz_ca_path (Unicode) path to an x509 certificates list.
 *
 * @return -1 on error, 0 on success.
 */
static int
gnutls_ServerAddCA( tls_server_t *p_server, const char *psz_ca_path )
{
    tls_server_sys_t *p_sys;
    char *psz_local_path;
    int val;

    p_sys = (tls_server_sys_t *)(p_server->p_sys);

    psz_local_path = ToLocale( psz_ca_path );
    val = gnutls_certificate_set_x509_trust_file( p_sys->x509_cred,
                                                  psz_local_path,
                                                  GNUTLS_X509_FMT_PEM );
    LocaleFree( psz_local_path );
    if( val < 0 )
    {
        msg_Err( p_server, "cannot add trusted CA (%s): %s", psz_ca_path,
                 gnutls_strerror( val ) );
        return VLC_EGENERIC;
    }
    msg_Dbg( p_server, " %d trusted CA added (%s)", val, psz_ca_path );

    /* enables peer's certificate verification */
    p_sys->pf_handshake = gnutls_HandshakeAndValidate;

    return VLC_SUCCESS;
}


/**
 * Adds a certificates revocation list to be sent to TLS clients.
 *
 * @param psz_crl_path (Unicode) path of the CRL file.
 *
 * @return -1 on error, 0 on success.
 */
static int
gnutls_ServerAddCRL( tls_server_t *p_server, const char *psz_crl_path )
{
    int val;
    char *psz_local_path = ToLocale( psz_crl_path );

    val = gnutls_certificate_set_x509_crl_file( ((tls_server_sys_t *)
                                                (p_server->p_sys))->x509_cred,
                                                psz_local_path,
                                                GNUTLS_X509_FMT_PEM );
    LocaleFree( psz_crl_path );
    if( val < 0 )
    {
        msg_Err( p_server, "cannot add CRL (%s): %s", psz_crl_path,
                 gnutls_strerror( val ) );
        return VLC_EGENERIC;
    }
    msg_Dbg( p_server, "%d CRL added (%s)", val, psz_crl_path );
    return VLC_SUCCESS;
}


/**
 * Allocates a whole server's TLS credentials.
 */
static int OpenServer (vlc_object_t *obj)
{
    tls_server_t *p_server = (tls_server_t *)obj;
    tls_server_sys_t *p_sys;
    int val;

    if (gnutls_Init (obj))
        return VLC_EGENERIC;

    msg_Dbg (obj, "creating TLS server");

    p_sys = (tls_server_sys_t *)malloc( sizeof(struct tls_server_sys_t) );
    if( p_sys == NULL )
        return VLC_ENOMEM;

    p_sys->i_cache_size = config_GetInt (obj, "gnutls-cache-size");
    p_sys->p_cache = calloc (p_sys->i_cache_size,
                             sizeof (struct saved_session_t));
    if (p_sys->p_cache == NULL)
    {
        free (p_sys);
        return VLC_ENOMEM;
    }

    p_sys->p_store = p_sys->p_cache;
    p_server->p_sys = p_sys;
    p_server->pf_add_CA  = gnutls_ServerAddCA;
    p_server->pf_add_CRL = gnutls_ServerAddCRL;
    p_server->pf_open    = gnutls_ServerSessionPrepare;
    p_server->pf_close   = gnutls_SessionClose;

    /* No certificate validation by default */
    p_sys->pf_handshake  = gnutls_ContinueHandshake;

    vlc_mutex_init( &p_sys->cache_lock );

    /* Sets server's credentials */
    val = gnutls_certificate_allocate_credentials( &p_sys->x509_cred );
    if( val != 0 )
    {
        msg_Err( p_server, "cannot allocate X509 credentials: %s",
                 gnutls_strerror( val ) );
        goto error;
    }

    char *psz_cert_path = var_GetNonEmptyString (obj, "tls-x509-cert");
    char *psz_key_path = var_GetNonEmptyString (obj, "tls-x509-key");
    const char *psz_local_cert = ToLocale (psz_cert_path);
    const char *psz_local_key = ToLocale (psz_key_path);
    val = gnutls_certificate_set_x509_key_file (p_sys->x509_cred,
                                                psz_local_cert, psz_local_key,
                                                GNUTLS_X509_FMT_PEM );
    LocaleFree (psz_local_key);
    free (psz_key_path);
    LocaleFree (psz_local_cert);
    free (psz_cert_path);

    if( val < 0 )
    {
        msg_Err( p_server, "cannot set certificate chain or private key: %s",
                 gnutls_strerror( val ) );
        gnutls_certificate_free_credentials( p_sys->x509_cred );
        goto error;
    }

    /* FIXME:
     * - support other ciper suites
     */
    val = gnutls_dh_params_init (&p_sys->dh_params);
    if (val >= 0)
    {
        const gnutls_datum_t data = {
            .data = (unsigned char *)dh_params,
            .size = sizeof (dh_params) - 1,
        };

        val = gnutls_dh_params_import_pkcs3 (p_sys->dh_params, &data,
                                             GNUTLS_X509_FMT_PEM);
        if (val == 0)
            gnutls_certificate_set_dh_params (p_sys->x509_cred,
                                              p_sys->dh_params);
    }
    if (val < 0)
    {
        msg_Err (p_server, "cannot initialize DHE cipher suites: %s",
                 gnutls_strerror (val));
    }

    return VLC_SUCCESS;

error:
    vlc_mutex_destroy (&p_sys->cache_lock);
    free (p_sys->p_cache);
    free (p_sys);
    return VLC_EGENERIC;
}

/**
 * Destroys a TLS server object.
 */
static void CloseServer (vlc_object_t *p_server)
{
    tls_server_sys_t *p_sys = ((tls_server_t *)p_server)->p_sys;

    vlc_mutex_destroy (&p_sys->cache_lock);
    free (p_sys->p_cache);

    /* all sessions depending on the server are now deinitialized */
    gnutls_certificate_free_credentials (p_sys->x509_cred);
    gnutls_dh_params_deinit (p_sys->dh_params);
    free (p_sys);

    gnutls_Deinit (p_server);
}