diff options
Diffstat (limited to 'thirdparty/mbedtls/library/base64.c')
| -rw-r--r-- | thirdparty/mbedtls/library/base64.c | 255 |
1 files changed, 96 insertions, 159 deletions
diff --git a/thirdparty/mbedtls/library/base64.c b/thirdparty/mbedtls/library/base64.c index 692e11e3fa..b89313062b 100644 --- a/thirdparty/mbedtls/library/base64.c +++ b/thirdparty/mbedtls/library/base64.c @@ -66,127 +66,38 @@ #endif /* MBEDTLS_PLATFORM_C */ #endif /* MBEDTLS_SELF_TEST */ -static const unsigned char base64_enc_map[64] = -{ - 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', - 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', - 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', - 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', - 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', - 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', - '8', '9', '+', '/' -}; - -static const unsigned char base64_dec_map[128] = -{ - 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, - 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, - 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, - 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, - 127, 127, 127, 62, 127, 127, 127, 63, 52, 53, - 54, 55, 56, 57, 58, 59, 60, 61, 127, 127, - 127, 64, 127, 127, 127, 0, 1, 2, 3, 4, - 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, - 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, - 25, 127, 127, 127, 127, 127, 127, 26, 27, 28, - 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, - 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, - 49, 50, 51, 127, 127, 127, 127, 127 -}; - #define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */ -/* - * Constant flow conditional assignment to unsigned char - */ -static void mbedtls_base64_cond_assign_uchar( unsigned char * dest, const unsigned char * const src, - unsigned char condition ) -{ - /* MSVC has a warning about unary minus on unsigned integer types, - * but this is well-defined and precisely what we want to do here. */ -#if defined(_MSC_VER) -#pragma warning( push ) -#pragma warning( disable : 4146 ) -#endif - - /* Generate bitmask from condition, mask will either be 0xFF or 0 */ - unsigned char mask = ( condition | -condition ); - mask >>= 7; - mask = -mask; - -#if defined(_MSC_VER) -#pragma warning( pop ) -#endif - - *dest = ( ( *src ) & mask ) | ( ( *dest ) & ~mask ); -} - -/* - * Constant flow conditional assignment to uint_32 - */ -static void mbedtls_base64_cond_assign_uint32( uint32_t * dest, const uint32_t src, - uint32_t condition ) -{ - /* MSVC has a warning about unary minus on unsigned integer types, - * but this is well-defined and precisely what we want to do here. */ -#if defined(_MSC_VER) -#pragma warning( push ) -#pragma warning( disable : 4146 ) -#endif - - /* Generate bitmask from condition, mask will either be 0xFFFFFFFF or 0 */ - uint32_t mask = ( condition | -condition ); - mask >>= 31; - mask = -mask; - -#if defined(_MSC_VER) -#pragma warning( pop ) -#endif - - *dest = ( src & mask ) | ( ( *dest ) & ~mask ); -} - -/* - * Constant flow check for equality +/* Return 0xff if low <= c <= high, 0 otherwise. + * + * Constant flow with respect to c. */ -static unsigned char mbedtls_base64_eq( size_t in_a, size_t in_b ) +static unsigned char mask_of_range( unsigned char low, unsigned char high, + unsigned char c ) { - size_t difference = in_a ^ in_b; - - /* MSVC has a warning about unary minus on unsigned integer types, - * but this is well-defined and precisely what we want to do here. */ -#if defined(_MSC_VER) -#pragma warning( push ) -#pragma warning( disable : 4146 ) -#endif - - difference |= -difference; - -#if defined(_MSC_VER) -#pragma warning( pop ) -#endif - - /* cope with the varying size of size_t per platform */ - difference >>= ( sizeof( difference ) * 8 - 1 ); - - return (unsigned char) ( 1 ^ difference ); + /* low_mask is: 0 if low <= c, 0x...ff if low > c */ + unsigned low_mask = ( (unsigned) c - low ) >> 8; + /* high_mask is: 0 if c <= high, 0x...ff if high > c */ + unsigned high_mask = ( (unsigned) high - c ) >> 8; + return( ~( low_mask | high_mask ) & 0xff ); } -/* - * Constant flow lookup into table. +/* Given a value in the range 0..63, return the corresponding Base64 digit. + * The implementation assumes that letters are consecutive (e.g. ASCII + * but not EBCDIC). */ -static unsigned char mbedtls_base64_table_lookup( const unsigned char * const table, - const size_t table_size, const size_t table_index ) +static unsigned char enc_char( unsigned char val ) { - size_t i; - unsigned char result = 0; - - for( i = 0; i < table_size; ++i ) - { - mbedtls_base64_cond_assign_uchar( &result, &table[i], mbedtls_base64_eq( i, table_index ) ); - } - - return result; + unsigned char digit = 0; + /* For each range of values, if val is in that range, mask digit with + * the corresponding value. Since val can only be in a single range, + * only at most one masking will change digit. */ + digit |= mask_of_range( 0, 25, val ) & ( 'A' + val ); + digit |= mask_of_range( 26, 51, val ) & ( 'a' + val - 26 ); + digit |= mask_of_range( 52, 61, val ) & ( '0' + val - 52 ); + digit |= mask_of_range( 62, 62, val ) & '+'; + digit |= mask_of_range( 63, 63, val ) & '/'; + return( digit ); } /* @@ -229,17 +140,10 @@ int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen, C2 = *src++; C3 = *src++; - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( ( C1 >> 2 ) & 0x3F ) ); - - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ) ); - - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( ( ( ( C2 & 15 ) << 2 ) + ( C3 >> 6 ) ) & 0x3F ) ); - - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( C3 & 0x3F ) ); + *p++ = enc_char( ( C1 >> 2 ) & 0x3F ); + *p++ = enc_char( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ); + *p++ = enc_char( ( ( ( C2 & 15 ) << 2 ) + ( C3 >> 6 ) ) & 0x3F ); + *p++ = enc_char( C3 & 0x3F ); } if( i < slen ) @@ -247,15 +151,11 @@ int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen, C1 = *src++; C2 = ( ( i + 1 ) < slen ) ? *src++ : 0; - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( ( C1 >> 2 ) & 0x3F ) ); - - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ) ); + *p++ = enc_char( ( C1 >> 2 ) & 0x3F ); + *p++ = enc_char( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ); if( ( i + 1 ) < slen ) - *p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ), - ( ( ( C2 & 15 ) << 2 ) & 0x3F ) ); + *p++ = enc_char( ( ( C2 & 15 ) << 2 ) & 0x3F ); else *p++ = '='; *p++ = '='; @@ -267,26 +167,57 @@ int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen, return( 0 ); } +/* Given a Base64 digit, return its value. + * If c is not a Base64 digit ('A'..'Z', 'a'..'z', '0'..'9', '+' or '/'), + * return -1. + * + * The implementation assumes that letters are consecutive (e.g. ASCII + * but not EBCDIC). + * + * The implementation is constant-flow (no branch or memory access depending + * on the value of c) unless the compiler inlines and optimizes a specific + * access. + */ +static signed char dec_value( unsigned char c ) +{ + unsigned char val = 0; + /* For each range of digits, if c is in that range, mask val with + * the corresponding value. Since c can only be in a single range, + * only at most one masking will change val. Set val to one plus + * the desired value so that it stays 0 if c is in none of the ranges. */ + val |= mask_of_range( 'A', 'Z', c ) & ( c - 'A' + 0 + 1 ); + val |= mask_of_range( 'a', 'z', c ) & ( c - 'a' + 26 + 1 ); + val |= mask_of_range( '0', '9', c ) & ( c - '0' + 52 + 1 ); + val |= mask_of_range( '+', '+', c ) & ( c - '+' + 62 + 1 ); + val |= mask_of_range( '/', '/', c ) & ( c - '/' + 63 + 1 ); + /* At this point, val is 0 if c is an invalid digit and v+1 if c is + * a digit with the value v. */ + return( val - 1 ); +} + /* * Decode a base64-formatted buffer */ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen, const unsigned char *src, size_t slen ) { - size_t i, n; - uint32_t j, x; + size_t i; /* index in source */ + size_t n; /* number of digits or trailing = in source */ + uint32_t x; /* value accumulator */ + unsigned accumulated_digits = 0; + unsigned equals = 0; + int spaces_present = 0; unsigned char *p; - unsigned char dec_map_lookup; /* First pass: check for validity and get output length */ - for( i = n = j = 0; i < slen; i++ ) + for( i = n = 0; i < slen; i++ ) { /* Skip spaces before checking for EOL */ - x = 0; + spaces_present = 0; while( i < slen && src[i] == ' ' ) { ++i; - ++x; + spaces_present = 1; } /* Spaces at end of buffer are OK */ @@ -301,20 +232,24 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen, continue; /* Space inside a line is an error */ - if( x != 0 ) + if( spaces_present ) return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); - if( src[i] == '=' && ++j > 2 ) - return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); - - dec_map_lookup = mbedtls_base64_table_lookup( base64_dec_map, sizeof( base64_dec_map ), src[i] ); - - if( src[i] > 127 || dec_map_lookup == 127 ) - return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); - - if( dec_map_lookup < 64 && j != 0 ) + if( src[i] > 127 ) return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); + if( src[i] == '=' ) + { + if( ++equals > 2 ) + return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); + } + else + { + if( equals != 0 ) + return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); + if( dec_value( src[i] ) < 0 ) + return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER ); + } n++; } @@ -329,7 +264,7 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen, * n = ( ( n * 6 ) + 7 ) >> 3; */ n = ( 6 * ( n >> 3 ) ) + ( ( 6 * ( n & 0x7 ) + 7 ) >> 3 ); - n -= j; + n -= equals; if( dst == NULL || dlen < n ) { @@ -337,22 +272,24 @@ int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen, return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL ); } - for( j = 3, n = x = 0, p = dst; i > 0; i--, src++ ) - { + equals = 0; + for( x = 0, p = dst; i > 0; i--, src++ ) + { if( *src == '\r' || *src == '\n' || *src == ' ' ) continue; - dec_map_lookup = mbedtls_base64_table_lookup( base64_dec_map, sizeof( base64_dec_map ), *src ); - - mbedtls_base64_cond_assign_uint32( &j, j - 1, mbedtls_base64_eq( dec_map_lookup, 64 ) ); - x = ( x << 6 ) | ( dec_map_lookup & 0x3F ); + x = x << 6; + if( *src == '=' ) + ++equals; + else + x |= dec_value( *src ); - if( ++n == 4 ) + if( ++accumulated_digits == 4 ) { - n = 0; - if( j > 0 ) *p++ = (unsigned char)( x >> 16 ); - if( j > 1 ) *p++ = (unsigned char)( x >> 8 ); - if( j > 2 ) *p++ = (unsigned char)( x ); + accumulated_digits = 0; + *p++ = (unsigned char)( x >> 16 ); + if( equals <= 1 ) *p++ = (unsigned char)( x >> 8 ); + if( equals <= 0 ) *p++ = (unsigned char)( x ); } } |