396 lines
11 KiB
C
396 lines
11 KiB
C
/*
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* RFC 1521 base64 encoding/decoding
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_BASE64_C)
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#include "mbedtls/base64.h"
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#include <stdint.h>
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#if defined(MBEDTLS_SELF_TEST)
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#include <string.h>
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#if defined(MBEDTLS_PLATFORM_C)
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#include "mbedtls/platform.h"
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#else
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#include <stdio.h>
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#define mbedtls_printf printf
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#endif /* MBEDTLS_PLATFORM_C */
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#endif /* MBEDTLS_SELF_TEST */
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static const unsigned char base64_enc_map[64] =
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{
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
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'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
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'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
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'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
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'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
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'8', '9', '+', '/'
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};
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static const unsigned char base64_dec_map[128] =
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{
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127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
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127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
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127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
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127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
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127, 127, 127, 62, 127, 127, 127, 63, 52, 53,
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54, 55, 56, 57, 58, 59, 60, 61, 127, 127,
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127, 64, 127, 127, 127, 0, 1, 2, 3, 4,
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5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
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25, 127, 127, 127, 127, 127, 127, 26, 27, 28,
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29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
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39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
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49, 50, 51, 127, 127, 127, 127, 127
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};
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#define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */
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/*
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* Constant flow conditional assignment to unsigned char
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*/
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static void mbedtls_base64_cond_assign_uchar( unsigned char * dest, const unsigned char * const src,
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unsigned char condition )
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{
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/* MSVC has a warning about unary minus on unsigned integer types,
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* but this is well-defined and precisely what we want to do here. */
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#if defined(_MSC_VER)
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#pragma warning( push )
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#pragma warning( disable : 4146 )
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#endif
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/* Generate bitmask from condition, mask will either be 0xFF or 0 */
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unsigned char mask = ( condition | -condition );
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mask >>= 7;
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mask = -mask;
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#if defined(_MSC_VER)
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#pragma warning( pop )
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#endif
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*dest = ( ( *src ) & mask ) | ( ( *dest ) & ~mask );
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}
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/*
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* Constant flow conditional assignment to uint_32
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*/
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static void mbedtls_base64_cond_assign_uint32( uint32_t * dest, const uint32_t src,
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uint32_t condition )
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{
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/* MSVC has a warning about unary minus on unsigned integer types,
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* but this is well-defined and precisely what we want to do here. */
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#if defined(_MSC_VER)
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#pragma warning( push )
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#pragma warning( disable : 4146 )
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#endif
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/* Generate bitmask from condition, mask will either be 0xFFFFFFFF or 0 */
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uint32_t mask = ( condition | -condition );
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mask >>= 31;
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mask = -mask;
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#if defined(_MSC_VER)
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#pragma warning( pop )
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#endif
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*dest = ( src & mask ) | ( ( *dest ) & ~mask );
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}
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/*
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* Constant flow check for equality
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*/
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static unsigned char mbedtls_base64_eq( size_t in_a, size_t in_b )
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{
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size_t difference = in_a ^ in_b;
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/* MSVC has a warning about unary minus on unsigned integer types,
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* but this is well-defined and precisely what we want to do here. */
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#if defined(_MSC_VER)
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#pragma warning( push )
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#pragma warning( disable : 4146 )
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#endif
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difference |= -difference;
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#if defined(_MSC_VER)
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#pragma warning( pop )
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#endif
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/* cope with the varying size of size_t per platform */
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difference >>= ( sizeof( difference ) * 8 - 1 );
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return (unsigned char) ( 1 ^ difference );
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}
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/*
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* Constant flow lookup into table.
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*/
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static unsigned char mbedtls_base64_table_lookup( const unsigned char * const table,
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const size_t table_size, const size_t table_index )
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{
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size_t i;
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unsigned char result = 0;
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for( i = 0; i < table_size; ++i )
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{
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mbedtls_base64_cond_assign_uchar( &result, &table[i], mbedtls_base64_eq( i, table_index ) );
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}
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return result;
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}
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/*
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* Encode a buffer into base64 format
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*/
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int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
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const unsigned char *src, size_t slen )
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{
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size_t i, n;
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int C1, C2, C3;
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unsigned char *p;
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if( slen == 0 )
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{
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*olen = 0;
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return( 0 );
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}
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n = slen / 3 + ( slen % 3 != 0 );
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if( n > ( BASE64_SIZE_T_MAX - 1 ) / 4 )
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{
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*olen = BASE64_SIZE_T_MAX;
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return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
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}
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n *= 4;
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if( ( dlen < n + 1 ) || ( NULL == dst ) )
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{
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*olen = n + 1;
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return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
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}
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n = ( slen / 3 ) * 3;
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for( i = 0, p = dst; i < n; i += 3 )
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{
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C1 = *src++;
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C2 = *src++;
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C3 = *src++;
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( C1 >> 2 ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( ( C2 & 15 ) << 2 ) + ( C3 >> 6 ) ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( C3 & 0x3F ) );
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}
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if( i < slen )
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{
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C1 = *src++;
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C2 = ( ( i + 1 ) < slen ) ? *src++ : 0;
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( C1 >> 2 ) & 0x3F ) );
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( ( C1 & 3 ) << 4 ) + ( C2 >> 4 ) ) & 0x3F ) );
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if( ( i + 1 ) < slen )
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*p++ = mbedtls_base64_table_lookup( base64_enc_map, sizeof( base64_enc_map ),
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( ( ( C2 & 15 ) << 2 ) & 0x3F ) );
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else *p++ = '=';
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*p++ = '=';
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}
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*olen = p - dst;
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*p = 0;
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return( 0 );
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}
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/*
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* Decode a base64-formatted buffer
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*/
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int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
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const unsigned char *src, size_t slen )
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{
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size_t i, n;
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uint32_t j, x;
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unsigned char *p;
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unsigned char dec_map_lookup;
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/* First pass: check for validity and get output length */
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for( i = n = j = 0; i < slen; i++ )
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{
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/* Skip spaces before checking for EOL */
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x = 0;
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while( i < slen && src[i] == ' ' )
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{
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++i;
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++x;
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}
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/* Spaces at end of buffer are OK */
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if( i == slen )
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break;
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if( ( slen - i ) >= 2 &&
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src[i] == '\r' && src[i + 1] == '\n' )
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continue;
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if( src[i] == '\n' )
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continue;
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/* Space inside a line is an error */
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if( x != 0 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( src[i] == '=' && ++j > 2 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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dec_map_lookup = mbedtls_base64_table_lookup( base64_dec_map, sizeof( base64_dec_map ), src[i] );
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if( src[i] > 127 || dec_map_lookup == 127 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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if( dec_map_lookup < 64 && j != 0 )
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return( MBEDTLS_ERR_BASE64_INVALID_CHARACTER );
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n++;
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}
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if( n == 0 )
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{
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*olen = 0;
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return( 0 );
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}
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/* The following expression is to calculate the following formula without
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* risk of integer overflow in n:
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* n = ( ( n * 6 ) + 7 ) >> 3;
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*/
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n = ( 6 * ( n >> 3 ) ) + ( ( 6 * ( n & 0x7 ) + 7 ) >> 3 );
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n -= j;
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if( dst == NULL || dlen < n )
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{
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*olen = n;
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return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
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}
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for( j = 3, n = x = 0, p = dst; i > 0; i--, src++ )
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{
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if( *src == '\r' || *src == '\n' || *src == ' ' )
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continue;
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dec_map_lookup = mbedtls_base64_table_lookup( base64_dec_map, sizeof( base64_dec_map ), *src );
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mbedtls_base64_cond_assign_uint32( &j, j - 1, mbedtls_base64_eq( dec_map_lookup, 64 ) );
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x = ( x << 6 ) | ( dec_map_lookup & 0x3F );
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if( ++n == 4 )
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{
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n = 0;
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if( j > 0 ) *p++ = (unsigned char)( x >> 16 );
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if( j > 1 ) *p++ = (unsigned char)( x >> 8 );
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if( j > 2 ) *p++ = (unsigned char)( x );
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}
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}
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*olen = p - dst;
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return( 0 );
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}
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#if defined(MBEDTLS_SELF_TEST)
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static const unsigned char base64_test_dec[64] =
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{
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0x24, 0x48, 0x6E, 0x56, 0x87, 0x62, 0x5A, 0xBD,
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0xBF, 0x17, 0xD9, 0xA2, 0xC4, 0x17, 0x1A, 0x01,
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0x94, 0xED, 0x8F, 0x1E, 0x11, 0xB3, 0xD7, 0x09,
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0x0C, 0xB6, 0xE9, 0x10, 0x6F, 0x22, 0xEE, 0x13,
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0xCA, 0xB3, 0x07, 0x05, 0x76, 0xC9, 0xFA, 0x31,
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0x6C, 0x08, 0x34, 0xFF, 0x8D, 0xC2, 0x6C, 0x38,
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0x00, 0x43, 0xE9, 0x54, 0x97, 0xAF, 0x50, 0x4B,
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0xD1, 0x41, 0xBA, 0x95, 0x31, 0x5A, 0x0B, 0x97
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};
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static const unsigned char base64_test_enc[] =
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"JEhuVodiWr2/F9mixBcaAZTtjx4Rs9cJDLbpEG8i7hPK"
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"swcFdsn6MWwINP+Nwmw4AEPpVJevUEvRQbqVMVoLlw==";
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/*
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* Checkup routine
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*/
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int mbedtls_base64_self_test( int verbose )
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{
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size_t len;
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const unsigned char *src;
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unsigned char buffer[128];
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if( verbose != 0 )
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mbedtls_printf( " Base64 encoding test: " );
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src = base64_test_dec;
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if( mbedtls_base64_encode( buffer, sizeof( buffer ), &len, src, 64 ) != 0 ||
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memcmp( base64_test_enc, buffer, 88 ) != 0 )
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{
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if( verbose != 0 )
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mbedtls_printf( "failed\n" );
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return( 1 );
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}
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if( verbose != 0 )
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mbedtls_printf( "passed\n Base64 decoding test: " );
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src = base64_test_enc;
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if( mbedtls_base64_decode( buffer, sizeof( buffer ), &len, src, 88 ) != 0 ||
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memcmp( base64_test_dec, buffer, 64 ) != 0 )
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{
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if( verbose != 0 )
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mbedtls_printf( "failed\n" );
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return( 1 );
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}
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if( verbose != 0 )
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mbedtls_printf( "passed\n\n" );
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return( 0 );
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}
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#endif /* MBEDTLS_SELF_TEST */
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#endif /* MBEDTLS_BASE64_C */
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