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godot/thirdparty/mbedtls/patches/pr4819-faster-base64.patch

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mbedtls: Backport PR 4819 to fix certs parsing speed Fixes engine startup time regression described here: https://github.com/godotengine/godot/issues/43351#issuecomment-847466783
2021-10-25 15:59:47 +00:00
diff --git a/library/base64.c b/library/base64.c
index 692e11e3fae..b89313062b6 100644
--- a/library/base64.c
+++ b/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 );
}
}