[vlc-devel] [PATCH v2 03/15] src: add cleaner md5 API
Steve Lhomme
robux4 at ycbcr.xyz
Wed Apr 8 08:45:10 CEST 2020
On 2020-04-08 0:04, Marvin Scholz wrote:
> This API is intended to replace the existing MD5 hashing API.
> It uses properly prefixed functions and has documentation.
> ---
> include/vlc_hash.h | 126 +++++++++++++++++++++++++++++++++++++++++++++
> src/Makefile.am | 1 +
> src/libvlccore.sym | 4 ++
> src/misc/md5.c | 37 ++++++++++++-
> 4 files changed, 167 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..19d137c9cc
> --- /dev/null
> +++ b/include/vlc_hash.h
> @@ -0,0 +1,126 @@
> +/*****************************************************************************
> + * 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
> +
> +/**
> + * 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 pointe to by output, which must be at
> + * least \ref VLC_HASH_MD5_DIGEST_SIZE big.
> + *
> + * \note The context is reset.
> + *
> + * \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.
> + *
> + * \note The context is reset, if this function returns successfully. On error, the
> + * context is not modified.
> + *
> + * \param[in,out] ctx MD5 hash context to finish
> + * \return Heap-allocated zero-terminated string with the hexadecimal representation
> + * of the MD5 digest data, or NULL in case of error.
> + */
> +VLC_API char* vlc_hash_md5_FinishHex(vlc_hash_md5_t *ctx);
> +
> +/**
> + * @}
> + */
> +
> +/**
> + * @}
> + */
> +
> +#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..24b940debf 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 +349,36 @@ 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);
Doing an Init at the end of a Finish is odd. It should be the
responsibility of the caller to match init/finish calls. If needed you
can add debug code to check this is always done.
> +}
> +
> +char* vlc_hash_md5_FinishHex(vlc_hash_md5_t *ctx)
> +{
> + char *hex = malloc(VLC_HASH_MD5_DIGEST_SIZE * 2 + 1); // Two chars per byte + NULL
> + if (unlikely(hex == NULL))
> + return NULL;
> +
> + md5_final(&ctx->priv);
> + vlc_hex_encode_binary(ctx->priv.buf, VLC_HASH_MD5_DIGEST_SIZE, hex);
> + vlc_hash_md5_Init(ctx);
Same here.
> +
> + return hex;
> +}
> +
> --
> 2.24.1 (Apple Git-126)
>
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