[vlc-devel] [PATCH v3 02/14] src: add cleaner md5 API

Marvin Scholz epirat07 at gmail.com
Wed Apr 8 17:14:01 CEST 2020



On 8 Apr 2020, at 17:08, Rémi Denis-Courmont wrote:

> Le keskiviikkona 8. huhtikuuta 2020, 17.10.12 EEST Marvin Scholz a 
> écrit :
>> This API is intended to replace the existing MD5 hashing API.
>> It uses properly prefixed functions and has documentation.
>> ---
>>  include/vlc_hash.h | 128 
>> +++++++++++++++++++++++++++++++++++++++++++++
>>  src/Makefile.am    |   1 +
>>  src/libvlccore.sym |   4 ++
>>  src/misc/md5.c     |  34 +++++++++++-
>>  4 files changed, 166 insertions(+), 1 deletion(-)
>>  create mode 100644 include/vlc_hash.h
>>
>> diff --git a/include/vlc_hash.h b/include/vlc_hash.h
>> new file mode 100644
>> index 0000000000..4712ee9eaf
>> --- /dev/null
>> +++ b/include/vlc_hash.h
>> @@ -0,0 +1,128 @@
>> +/**************************************************************************
>> *** + * vlc_hash.h: Hash functions
>> +
>> ***************************************************************************
>> ** + * Copyright © 2004-2020 VLC authors and VideoLAN
>> + *
>> + * Authors: Rémi Denis-Courmont
>> + *          Rafaël Carré
>> + *          Marvin Scholz
>> + *
>> + * This program is free software; you can redistribute it and/or 
>> modify it
>> + * under the terms of the GNU Lesser General Public License as 
>> published by
>> + * the Free Software Foundation; either version 2.1 of the License, 
>> or + *
>> (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser General Public 
>> License
>> + * along with this program; if not, write to the Free Software 
>> Foundation,
>> + * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA. 
>> +
>> ***************************************************************************
>> **/ +
>> +#ifndef VLC_HASH_H
>> +# define VLC_HASH_H
>> +
>> +#include <vlc_md5.h>
>> +
>> +/**
>> + * \defgroup vlc_hash  Hash functions
>> + * APIs for simple and frequently used hash algorithms in VLC
>> + *
>> + * Each hash algorithm has a context object which stores all data 
>> needed
>> for the + * hash calculation, this context is not supposed to be 
>> modified
>> directly by the + * called but only with the functions listed here.
>> + *
>> + * Supported hash algorithms:
>> + *   - \ref vlc_hash_md5 "MD5"
>> + *
>> + * @{
>> + */
>> +
>> +/**
>> + * \defgroup vlc_hash_md5  MD5 hashing
>> + * APIs to hash data using the Message-Digest Algorithm 5 (MD5)
>> + * @{
>> + */
>> +
>> +/**
>> + * MD5 hash context
>> + */
>> +typedef struct vlc_hash_md5_ctx
>> +{
>> +    struct md5_s priv; /**< \internal Private */
>> +} vlc_hash_md5_t;
>> +
>> +/**
>> + * MD5 digest output size
>> + */
>> +#define VLC_HASH_MD5_DIGEST_SIZE 16
>> +
>> +/**
>> + * MD5 digest hex representation size
>> + */
>> +#define VLC_HASH_MD5_DIGEST_HEX_SIZE 33 // 2 chars per byte + null
>> +
>> +/**
>> + * Initialize MD5 context
>> + *
>> + * Initializes the given MD5 hash function context, if the context 
>> is
>> + * already initialized, it is reset.
>> + *
>> + * \param[out] ctx  MD5 hash context to init
>> + */
>> +VLC_API void vlc_hash_md5_Init(vlc_hash_md5_t *ctx);
>> +
>> +/**
>> + * Update MD5 hash computation with new data
>> + *
>> + * Updates the context with provided data which is used for the hash
>> + * calculation. Can be called repeatedly with new data. The final
>> + * hash represents the hash for the concatenation of all data.
>> + *
>> + * \param[in,out] ctx    MD5 hash context to update
>> + * \param         data   Data to add
>> + * \param         size   Size of the data to add
>> + */
>> +VLC_API void vlc_hash_md5_Update(vlc_hash_md5_t *ctx, const void 
>> *data,
>> size_t size); +
>> +/**
>> + * Finish MD5 hash computation
>> + *
>> + * Finishes the MD5 hash computation and provides the hash for the
>> + * concatenation of all provided data by previous calls to \ref
>> vlc_hash_md5_Update. + * The result is written to the buffer pointed 
>> to by
>> output, which must be at + * least \ref VLC_HASH_MD5_DIGEST_SIZE big.
>> + *
>> + * \param[in,out] ctx    MD5 hash context to finish
>> + * \param[out]    output Output buffer to write to
>> + * \param         size   Output buffer size
>> + */
>> +VLC_API void vlc_hash_md5_Finish(vlc_hash_md5_t *ctx, void *output, 
>> size_t
>> size); +
>> +/**
>> + * Finish MD5 hash computation and return hex representation
>> + *
>> + * Finishes the MD5 hash computation and provides the hash for the
>> + * concatenation of all provided data by previous calls to \ref
>> vlc_hash_md5_Update + * in hex encoded format.
>> + * The result is written to the buffer pointed to by output, which 
>> must be
>> at + * least \ref VLC_HASH_MD5_DIGEST_HEX_SIZE big.
>> + *
>> + * \param[in,out] ctx    MD5 hash context to finish
>> + * \param[out]    output Output buffer to write the string to
>> + * \param         size   Output buffer size
>> + */
>> +VLC_API void vlc_hash_md5_FinishHex(vlc_hash_md5_t *ctx, char 
>> *output,
>> size_t size); +
>> +/**
>> + * @}
>> + */
>> +
>> +/**
>> + * @}
>> + */
>> +
>> +#endif
>> diff --git a/src/Makefile.am b/src/Makefile.am
>> index 88c6d903ae..7e99d03bc2 100644
>> --- a/src/Makefile.am
>> +++ b/src/Makefile.am
>> @@ -54,6 +54,7 @@ pluginsinclude_HEADERS = \
>>  	../include/vlc_fs.h \
>>  	../include/vlc_gcrypt.h \
>>  	../include/vlc_opengl.h \
>> +	../include/vlc_hash.h \
>>  	../include/vlc_http.h \
>>  	../include/vlc_httpd.h \
>>  	../include/vlc_image.h \
>> diff --git a/src/libvlccore.sym b/src/libvlccore.sym
>> index 17561db932..ed07d998e2 100644
>> --- a/src/libvlccore.sym
>> +++ b/src/libvlccore.sym
>> @@ -144,6 +144,10 @@ httpd_HandlerNew
>>  httpd_HostDelete
>>  vlc_http_HostNew
>>  vlc_https_HostNew
>> +vlc_hash_md5_Init
>> +vlc_hash_md5_Update
>> +vlc_hash_md5_Finish
>> +vlc_hash_md5_FinishHex
>>  vlc_rtsp_HostNew
>>  httpd_MsgAdd
>>  httpd_MsgGet
>> diff --git a/src/misc/md5.c b/src/misc/md5.c
>> index adfd939c0a..66ca2c19d4 100644
>> --- a/src/misc/md5.c
>> +++ b/src/misc/md5.c
>> @@ -40,9 +40,11 @@
>>  #include <stdio.h>
>>  #include <stdlib.h>
>>  #include <string.h>
>> +#include <assert.h>
>>
>>  #include <vlc_common.h>
>> -#include <vlc_md5.h>
>> +#include <vlc_strings.h>
>> +#include <vlc_hash.h>
>>
>>  typedef uint32_t u32;
>>  typedef uint8_t byte;
>> @@ -347,3 +349,33 @@ void EndMD5( struct md5_s *h )
>>  {
>>      md5_final( h );
>>  }
>> +
>> +/* New API */
>> +void vlc_hash_md5_Init(vlc_hash_md5_t *ctx)
>> +{
>> +    md5_init(&ctx->priv);
>> +}
>> +
>> +void vlc_hash_md5_Update(vlc_hash_md5_t *ctx, const void *data, 
>> size_t
>> length) +{
>> +    md5_write(&ctx->priv, data, length);
>> +}
>> +
>> +void vlc_hash_md5_Finish(vlc_hash_md5_t *ctx, void *output, size_t 
>> size)
>> +{
>> +    assert(size >= VLC_HASH_MD5_DIGEST_SIZE);
>> +    md5_final(&ctx->priv);
>> +    memcpy(output, ctx->priv.buf, VLC_HASH_MD5_DIGEST_SIZE);
>> +    vlc_hash_md5_Init(ctx);
>> +}
>> +
>> +void vlc_hash_md5_FinishHex(vlc_hash_md5_t *ctx, char *output, 
>> size_t size)
>> +{
>> +    assert(size >= VLC_HASH_MD5_DIGEST_SIZE);
>> +    VLC_UNUSED(size);
>> +
>> +    md5_final(&ctx->priv);
>> +    vlc_hex_encode_binary(ctx->priv.buf, VLC_HASH_MD5_DIGEST_SIZE, 
>> output);
>> +    vlc_hash_md5_Init(ctx);
>> +}
>> +
>
> As somebody already pointed out, the two init calls seem out of place 
> here.
>
> And the FinishHex could be a static inline so as not to couple 
> unrelated
> conversion and hashing routines.
>

Indeed, will change that.

> -- 
> Rémi Denis-Courmont
> Ville neuve de Tapiola, République d´Uusimaa
>
>
>
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