update.c

VLC Player Source Code

    }
    return crc & 0xFFFFFFL;
}

/*
 * Transform an armored document in binary format
 * Used on public keys and signatures
 */
static int pgp_unarmor( char *p_ibuf, size_t i_ibuf_len,
                        uint8_t *p_obuf, size_t i_obuf_len )
{
    char *p_ipos = p_ibuf;
    uint8_t *p_opos = p_obuf;
    int i_end = 0;
    int i_header_skipped = 0;

    while( !i_end && p_ipos < p_ibuf + i_ibuf_len && *p_ipos != '=' )
    {
        if( *p_ipos == '\r' || *p_ipos == '\n' )
        {
            p_ipos++;
            continue;
        }

        size_t i_line_len = strcspn( p_ipos, "\r\n" );
        if( i_line_len == 0 )
            continue;

        if( !i_header_skipped )
        {
            if( !strncmp( p_ipos, "-----BEGIN PGP", 14 ) )
                i_header_skipped = 1;

            p_ipos += i_line_len + 1;
            continue;
        }

        if( !strncmp( p_ipos, "Version:", 8 ) )
        {
            p_ipos += i_line_len + 1;
            continue;
        }

        if( p_ipos[i_line_len - 1] == '=' )
        {
            i_end = 1;
            p_ipos[i_line_len - 1] = '\0';
        }
        else
            p_ipos[i_line_len] = '\0';

        p_opos += vlc_b64_decode_binary_to_buffer(  p_opos,
                        p_obuf - p_opos + i_obuf_len, p_ipos );
        p_ipos += i_line_len + 1;
    }

    /* XXX: the CRC is OPTIONAL, really require it ? */
    if( p_ipos + 5 > p_ibuf + i_ibuf_len || *p_ipos++ != '=' )
        return 0;

    uint8_t p_crc[3];
    if( vlc_b64_decode_binary_to_buffer( p_crc, 3, p_ipos ) != 3 )
        return 0;

    long l_crc = crc_octets( p_obuf, p_opos - p_obuf );
    long l_crc2 = ( 0 << 24 ) + ( p_crc[0] << 16 ) + ( p_crc[1] << 8 ) + p_crc[2];

    return l_crc2 == l_crc ? p_opos - p_obuf : 0;
}

/*
 * Download the signature associated to a document or a binary file.
 * We're given the file's url, we just append ".asc" to it and download
 */
static int download_signature(  vlc_object_t *p_this,
                                signature_packet_t *p_sig,
                                const char *psz_url )
{
    char *psz_sig = (char*) malloc( strlen( psz_url ) + 4 + 1 ); /* ".asc" + \0 */
    if( !psz_sig )
        return VLC_ENOMEM;

    strcpy( psz_sig, psz_url );
    strcat( psz_sig, ".asc" );

    stream_t *p_stream = stream_UrlNew( p_this, psz_sig );
    free( psz_sig );

    if( !p_stream )
        return VLC_ENOMEM;

    int64_t i_size = stream_Size( p_stream );

    msg_Dbg( p_this, "Downloading signature (%"PRId64" bytes)", i_size );
    uint8_t *p_buf = (uint8_t*)malloc( i_size );
    if( !p_buf )
    {
        stream_Delete( p_stream );
        return VLC_ENOMEM;
    }

    int i_read = stream_Read( p_stream, p_buf, (int)i_size );

    stream_Delete( p_stream );

    if( i_read != (int)i_size )
    {
        msg_Dbg( p_this,
            "Couldn't download full signature (only %d bytes)", i_read );
        free( p_buf );
        return VLC_EGENERIC;
    }

    if( (uint8_t)*p_buf < 0x80 ) /* ASCII */
    {
        msg_Dbg( p_this, "Unarmoring signature" );

        uint8_t* p_unarmored = (uint8_t*) malloc( ( i_size * 3 ) / 4 + 1 );
        if( !p_unarmored )
        {
            free( p_buf );
            return VLC_EGENERIC;
        }

        int i_bytes = pgp_unarmor( (char*)p_buf, i_size, p_unarmored, i_size );
        free( p_buf );

        p_buf = p_unarmored;
        i_size = i_bytes;

        if( i_bytes < 2 )
        {
            free( p_buf );
            msg_Dbg( p_this, "Unarmoring failed : corrupted signature ?" );
            return VLC_EGENERIC;
        }
    }

    if( packet_type( *p_buf ) != SIGNATURE_PACKET )
    {
        free( p_buf );
        msg_Dbg( p_this, "Not a signature: %d", *p_buf );
        return VLC_EGENERIC;
    }

    size_t i_header_len = packet_header_len( *p_buf );
    if( ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) ||
        i_header_len + 1 > (size_t)i_size )
    {
        free( p_buf );
        msg_Dbg( p_this, "Invalid signature packet header" );
        return VLC_EGENERIC;
    }

    size_t i_len = scalar_number( p_buf+1, i_header_len );
    if( i_len + i_header_len + 1 != (size_t)i_size )
    {
        free( p_buf );
        msg_Dbg( p_this, "Invalid signature packet" );
        return VLC_EGENERIC;
    }

    int i_ret = parse_signature_packet( p_sig, p_buf+1+i_header_len, i_len );
    free( p_buf );
    if( i_ret != VLC_SUCCESS )
    {
        msg_Dbg( p_this, "Couldn't parse signature" );
        return i_ret;
    }

    if( p_sig->type != BINARY_SIGNATURE && p_sig->type != TEXT_SIGNATURE )
    {
        msg_Dbg( p_this, "Invalid signature type: %d", p_sig->type );
        if( p_sig->version == 4 )
        {
            free( p_sig->specific.v4.hashed_data );
            free( p_sig->specific.v4.unhashed_data );
        }
        return VLC_EGENERIC;
    }

    return VLC_SUCCESS;
}

/*
 * Verify an OpenPGP signature made on some SHA-1 hash, with some DSA public key
 */
static int verify_signature( uint8_t *p_r, uint8_t *p_s,
        public_key_packet_t *p_key, uint8_t *p_hash )
{
    /* the data to be verified (a SHA-1 hash) */
    const char *hash_sexp_s = "(data(flags raw)(value %m))";
    /* the public key */
    const char *key_sexp_s = "(public-key(dsa(p %m)(q %m)(g %m)(y %m)))";
    /* the signature */
    const char *sig_sexp_s = "(sig-val(dsa(r %m )(s %m )))";

    size_t erroff;
    gcry_mpi_t p, q, g, y, r, s, hash;
    p = q = g = y = r = s = hash = NULL;
    gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
    key_sexp = hash_sexp = sig_sexp = NULL;

    int i_p_len = mpi_len( p_key->p );
    int i_q_len = mpi_len( p_key->q );
    int i_g_len = mpi_len( p_key->g );
    int i_y_len = mpi_len( p_key->y );
    if( gcry_mpi_scan( &p, GCRYMPI_FMT_USG, p_key->p + 2, i_p_len, NULL ) ||
        gcry_mpi_scan( &q, GCRYMPI_FMT_USG, p_key->q + 2, i_q_len, NULL ) ||
        gcry_mpi_scan( &g, GCRYMPI_FMT_USG, p_key->g + 2, i_g_len, NULL ) ||
        gcry_mpi_scan( &y, GCRYMPI_FMT_USG, p_key->y + 2, i_y_len, NULL ) ||
        gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
        goto problem;

    int i_r_len = mpi_len( p_r );
    int i_s_len = mpi_len( p_s );
    if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
        gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
        gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
        goto problem;

    int i_hash_len = 20;
    if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
        gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
        goto problem;

    if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
        goto problem;

    return VLC_SUCCESS;

problem:
    if( p ) gcry_mpi_release( p );
    if( q ) gcry_mpi_release( q );
    if( g ) gcry_mpi_release( g );
    if( y ) gcry_mpi_release( y );
    if( r ) gcry_mpi_release( r );
    if( s ) gcry_mpi_release( s );
    if( hash ) gcry_mpi_release( hash );
    if( key_sexp ) gcry_sexp_release( key_sexp );
    if( sig_sexp ) gcry_sexp_release( sig_sexp );
    if( hash_sexp ) gcry_sexp_release( hash_sexp );
    return VLC_EGENERIC;
}

/*
 * fill a public_key_t with public key data, including:
 *   * public key packet
 *   * signature packet issued by key which long id is p_sig_issuer
 *   * user id packet
 */
static int parse_public_key( const uint8_t *p_key_data, size_t i_key_len,
                             public_key_t *p_key, const uint8_t *p_sig_issuer )
{
    uint8_t *pos = (uint8_t*) p_key_data;
    uint8_t *max_pos = pos + i_key_len;

    int i_status = 0;
#define PUBLIC_KEY_FOUND    0x01
#define USER_ID_FOUND       0x02
#define SIGNATURE_FOUND     0X04

    uint8_t *p_key_unarmored = NULL;

    p_key->psz_username = NULL;
    p_key->sig.specific.v4.hashed_data = NULL;
    p_key->sig.specific.v4.unhashed_data = NULL;

    if( !( *pos & 0x80 ) )
    {   /* first byte is ASCII, unarmoring */
        p_key_unarmored = (uint8_t*)malloc( i_key_len );
        if( !p_key_unarmored )
            return VLC_ENOMEM;
        int i_len = pgp_unarmor( (char*)p_key_data, i_key_len,
                                 p_key_unarmored, i_key_len );

        if( i_len == 0 )
            goto error;

        pos = p_key_unarmored;
        max_pos = pos + i_len;
    }

    while( pos < max_pos )
    {
        if( !(*pos & 0x80) || *pos & 0x40 )
            goto error;

        int i_type = packet_type( *pos );

        int i_header_len = packet_header_len( *pos++ );
        if( pos + i_header_len > max_pos ||
            ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) )
            goto error;

        int i_packet_len = scalar_number( pos, i_header_len );
        pos += i_header_len;

        if( pos + i_packet_len > max_pos )
            goto error;

        switch( i_type )
        {
            case PUBLIC_KEY_PACKET:
                i_status |= PUBLIC_KEY_FOUND;
                if( parse_public_key_packet( &p_key->key, pos, i_packet_len ) != VLC_SUCCESS )
                    goto error;
                break;

            case SIGNATURE_PACKET: /* we accept only v4 signatures here */
                if( i_status & SIGNATURE_FOUND || !p_sig_issuer )
                    break;
                int i_ret = parse_signature_packet( &p_key->sig, pos,
                                                    i_packet_len );
                if( i_ret == VLC_SUCCESS )
                {
                    if( p_key->sig.version != 4 )
                        break;
                    if( memcmp( p_key->sig.issuer_longid, p_sig_issuer, 8 ) )
                    {
                        free( p_key->sig.specific.v4.hashed_data );
                        free( p_key->sig.specific.v4.unhashed_data );
                        p_key->sig.specific.v4.hashed_data = NULL;
                        p_key->sig.specific.v4.unhashed_data = NULL;
                        break;
                    }
                    i_status |= SIGNATURE_FOUND;
                }
                break;

            case USER_ID_PACKET:
                if( p_key->psz_username ) /* save only the first User ID */
                    break;
                i_status |= USER_ID_FOUND;
                p_key->psz_username = (uint8_t*)malloc( i_packet_len + 1);
                if( !p_key->psz_username )
                    goto error;

                memcpy( p_key->psz_username, pos, i_packet_len );
                p_key->psz_username[i_packet_len] = '\0';
                break;

            default:
                break;
        }
        pos += i_packet_len;
    }
    free( p_key_unarmored );

    if( !( i_status & ( PUBLIC_KEY_FOUND | USER_ID_FOUND ) ) )
        return VLC_EGENERIC;

    if( p_sig_issuer && !( i_status & SIGNATURE_FOUND ) )
        return VLC_EGENERIC;

    return VLC_SUCCESS;

error:
    if( p_key->sig.version == 4 )
    {
        free( p_key->sig.specific.v4.hashed_data );
        free( p_key->sig.specific.v4.unhashed_data );
    }
    free( p_key->psz_username );
    free( p_key_unarmored );
    return VLC_EGENERIC;
}

/*
 * return a sha1 hash of a file
 */
static uint8_t *hash_sha1_from_file( const char *psz_file,
                            signature_packet_t *p_sig )
{
    if( p_sig->type != BINARY_SIGNATURE && p_sig->type != TEXT_SIGNATURE )
        return NULL;

    FILE *f = utf8_fopen( psz_file, "r" );
    if( !f )
        return NULL;

    uint8_t buffer[4096];

    gcry_md_hd_t hd;
    if( gcry_md_open( &hd, GCRY_MD_SHA1, 0 ) )
    {
        fclose( f );
        return NULL;
    }

    size_t i_read;
    while( ( i_read = fread( buffer, 1, sizeof(buffer), f ) ) > 0 )
        gcry_md_write( hd, buffer, i_read );

    if( p_sig->version == 3 )
    {
        gcry_md_putc( hd, p_sig->type );
        gcry_md_write( hd, &p_sig->specific.v3.timestamp, 4 );
    }
    else if( p_sig->version == 4 )
    {
        gcry_md_putc( hd, p_sig->version );
        gcry_md_putc( hd, p_sig->type );
        gcry_md_putc( hd, p_sig->public_key_algo );
        gcry_md_putc( hd, p_sig->digest_algo );
        gcry_md_write( hd, p_sig->specific.v4.hashed_data_len, 2 );
        size_t i_len = scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
        gcry_md_write( hd, p_sig->specific.v4.hashed_data, i_len );
    }
    else
    {   /* RFC 4880 only tells about versions 3 and 4 */
        gcry_md_close( hd );
        return NULL;
    }

    fclose( f );
    gcry_md_final( hd );

    uint8_t *p_tmp = (uint8_t*) gcry_md_read( hd, GCRY_MD_SHA1);
    uint8_t *p_hash = malloc( 20 );
    if( p_hash )
        memcpy( p_hash, p_tmp, 20 );
    gcry_md_close( hd );
    return p_hash;
}

/*
 * download a public key (the last one) from videolan server, and parse it
 */
static public_key_t *download_key( vlc_object_t *p_this,
                    const uint8_t *p_longid, const uint8_t *p_signature_issuer )
{
    char *psz_url;
    if( asprintf( &psz_url, "http://download.videolan.org/pub/keys/%.2X%.2X%.2X%.2X%.2X%.2X%.2X%.2X.asc",
                    p_longid[0], p_longid[1], p_longid[2], p_longid[3],
                    p_longid[4], p_longid[5], p_longid[6], p_longid[7] ) == -1 )
        return NULL;

    stream_t *p_stream = stream_UrlNew( p_this, psz_url );