Introduce getter functions for MD info fields

This commit continues the introduction of the MD digest implementation
abstraction layer given by `mbedtls_md_handle_t` by adding getter
functions returning the various properties of an implementation
(e.g. name, digest type, digest size). For the existing implementation,
these are just structure field accesses; however, in configurations
hardcoding the choice of a fixed digest algorithm, we'll be able to
implement them as inline functions returning compile-time constants.

include/mbedtls/md_internal.h

@@ -44,6 +44,21 @@ extern "C" {
  * Message digest information.
  * Allows message digest functions to be called in a generic way.
  */
+
+typedef int mbedtls_md_starts_func_t( void *ctx );
+typedef int mbedtls_md_update_func_t( void *ctx,
+                                       const unsigned char *input,
+                                       size_t ilen );
+typedef int mbedtls_md_finish_func_t( void *ctx, unsigned char *output );
+typedef int mbedtls_md_digest_func_t( const unsigned char *input,
+                                       size_t ilen,
+                                       unsigned char *output );
+typedef void* mbedtls_md_ctx_alloc_func_t( void );
+typedef void mbedtls_md_ctx_free_func_t( void *ctx );
+typedef void mbedtls_md_clone_func_t( void *st, const void *src );
+typedef int mbedtls_md_process_func_t( void *ctx,
+                                          const unsigned char *input );
+
 struct mbedtls_md_info_t
 {
     /** Digest identifier */
@@ -59,31 +74,106 @@ struct mbedtls_md_info_t
     int block_size;
 
     /** Digest initialisation function */
-    int (*starts_func)( void *ctx );
+    mbedtls_md_starts_func_t *starts_func;
 
     /** Digest update function */
-    int (*update_func)( void *ctx, const unsigned char *input, size_t ilen );
+    mbedtls_md_update_func_t *update_func;
 
     /** Digest finalisation function */
-    int (*finish_func)( void *ctx, unsigned char *output );
+    mbedtls_md_finish_func_t *finish_func;
 
     /** Generic digest function */
-    int (*digest_func)( const unsigned char *input, size_t ilen,
+    mbedtls_md_digest_func_t *digest_func;
-                        unsigned char *output );
 
     /** Allocate a new context */
-    void * (*ctx_alloc_func)( void );
+    mbedtls_md_ctx_alloc_func_t *ctx_alloc_func;
 
     /** Free the given context */
-    void (*ctx_free_func)( void *ctx );
+    mbedtls_md_ctx_free_func_t *ctx_free_func;
 
     /** Clone state from a context */
-    void (*clone_func)( void *dst, const void *src );
+    mbedtls_md_clone_func_t *clone_func;
 
     /** Internal use only */
-    int (*process_func)( void *ctx, const unsigned char *input );
+    mbedtls_md_process_func_t *process_func;
 };
 
+/*
+ * Getter functions for MD info structure.
+ */
+
+static inline mbedtls_md_type_t mbedtls_md_info_type(
+    mbedtls_md_handle_t info )
+{
+    return( info->type );
+}
+
+static inline const char * mbedtls_md_info_name(
+    mbedtls_md_handle_t info )
+{
+    return( info->name );
+}
+
+static inline int mbedtls_md_info_size(
+    mbedtls_md_handle_t info )
+{
+    return( info->size );
+}
+
+static inline int mbedtls_md_info_block_size(
+    mbedtls_md_handle_t info )
+{
+    return( info->block_size );
+}
+
+static inline mbedtls_md_starts_func_t *mbedtls_md_info_starts_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->starts_func );
+}
+
+static inline mbedtls_md_update_func_t *mbedtls_md_info_update_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->update_func );
+}
+
+static inline mbedtls_md_finish_func_t *mbedtls_md_info_finish_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->finish_func );
+}
+
+static inline mbedtls_md_digest_func_t *mbedtls_md_info_digest_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->digest_func );
+}
+
+static inline mbedtls_md_ctx_alloc_func_t *mbedtls_md_info_ctx_alloc_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->ctx_alloc_func );
+}
+
+static inline mbedtls_md_ctx_free_func_t *mbedtls_md_info_ctx_free_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->ctx_free_func );
+}
+
+static inline mbedtls_md_clone_func_t *mbedtls_md_info_clone_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->clone_func );
+}
+
+static inline mbedtls_md_process_func_t *mbedtls_md_info_process_func(
+    mbedtls_md_handle_t info )
+{
+    return( info->process_func );
+}
+
 #if defined(MBEDTLS_MD2_C)
 extern const mbedtls_md_info_t mbedtls_md2_info;
 #endif

library/md.c

@@ -191,12 +191,12 @@ void mbedtls_md_free( mbedtls_md_context_t *ctx )
         return;
 
     if( ctx->md_ctx != NULL )
-        ctx->md_info->ctx_free_func( ctx->md_ctx );
+        mbedtls_md_info_ctx_free_func( ctx->md_info )( ctx->md_ctx );
 
     if( ctx->hmac_ctx != NULL )
     {
         mbedtls_platform_zeroize( ctx->hmac_ctx,
-                                  2 * ctx->md_info->block_size );
+                     2 * mbedtls_md_info_block_size( ctx->md_info ) );
         mbedtls_free( ctx->hmac_ctx );
     }
 
@@ -213,8 +213,7 @@ int mbedtls_md_clone( mbedtls_md_context_t *dst,
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     }
 
-    dst->md_info->clone_func( dst->md_ctx, src->md_ctx );
+    mbedtls_md_info_clone_func( dst->md_info )( dst->md_ctx, src->md_ctx );
-
     return( 0 );
 }
 
@@ -230,15 +229,16 @@ int mbedtls_md_setup( mbedtls_md_context_t *ctx, mbedtls_md_handle_t md_info, in
     if( md_info == MBEDTLS_MD_INVALID_HANDLE || ctx == NULL )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    if( ( ctx->md_ctx = md_info->ctx_alloc_func() ) == NULL )
+    ctx->md_ctx = mbedtls_md_info_ctx_alloc_func( md_info )();
+    if( ctx->md_ctx == NULL )
         return( MBEDTLS_ERR_MD_ALLOC_FAILED );
 
     if( hmac != 0 )
     {
-        ctx->hmac_ctx = mbedtls_calloc( 2, md_info->block_size );
+        ctx->hmac_ctx = mbedtls_calloc( 2, mbedtls_md_info_block_size( md_info ) );
         if( ctx->hmac_ctx == NULL )
         {
-            md_info->ctx_free_func( ctx->md_ctx );
+            mbedtls_md_info_ctx_free_func( md_info )( ctx->md_ctx );
             return( MBEDTLS_ERR_MD_ALLOC_FAILED );
         }
     }
@@ -253,7 +253,7 @@ int mbedtls_md_starts( mbedtls_md_context_t *ctx )
     if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    return( ctx->md_info->starts_func( ctx->md_ctx ) );
+    return( mbedtls_md_info_starts_func( ctx->md_info )( ctx->md_ctx ) );
 }
 
 int mbedtls_md_update( mbedtls_md_context_t *ctx, const unsigned char *input, size_t ilen )
@@ -261,7 +261,8 @@ int mbedtls_md_update( mbedtls_md_context_t *ctx, const unsigned char *input, si
     if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    return( ctx->md_info->update_func( ctx->md_ctx, input, ilen ) );
+    return( mbedtls_md_info_update_func( ctx->md_info )( ctx->md_ctx,
+                                                             input, ilen ) );
 }
 
 int mbedtls_md_finish( mbedtls_md_context_t *ctx, unsigned char *output )
@@ -269,7 +270,8 @@ int mbedtls_md_finish( mbedtls_md_context_t *ctx, unsigned char *output )
     if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    return( ctx->md_info->finish_func( ctx->md_ctx, output ) );
+    return( mbedtls_md_info_finish_func( ctx->md_info )( ctx->md_ctx,
+                                                             output ) );
 }
 
 int mbedtls_md( mbedtls_md_handle_t md_info, const unsigned char *input, size_t ilen,
@@ -278,7 +280,8 @@ int mbedtls_md( mbedtls_md_handle_t md_info, const unsigned char *input, size_t
     if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    return( md_info->digest_func( input, ilen, output ) );
+    return( mbedtls_md_info_digest_func( md_info )(
+                input, ilen, output) );
 }
 
 #if defined(MBEDTLS_FS_IO)
@@ -301,17 +304,27 @@ int mbedtls_md_file( mbedtls_md_handle_t md_info, const char *path, unsigned cha
     if( ( ret = mbedtls_md_setup( &ctx, md_info, 0 ) ) != 0 )
         goto cleanup;
 
-    if( ( ret = md_info->starts_func( ctx.md_ctx ) ) != 0 )
+    ret = mbedtls_md_info_starts_func( md_info )( ctx.md_ctx );
+    if( ret != 0 )
         goto cleanup;
 
     while( ( n = fread( buf, 1, sizeof( buf ), f ) ) > 0 )
-        if( ( ret = md_info->update_func( ctx.md_ctx, buf, n ) ) != 0 )
+    {
+        ret = mbedtls_md_info_update_func( md_info )( ctx.md_ctx,
+                                                          buf, n );
+        if( ret != 0 )
             goto cleanup;
+    }
 
     if( ferror( f ) != 0 )
+    {
         ret = MBEDTLS_ERR_MD_FILE_IO_ERROR;
+    }
     else
-        ret = md_info->finish_func( ctx.md_ctx, output );
+    {
+        ret = mbedtls_md_info_finish_func( md_info )( ctx.md_ctx,
+                                                          output );
+    }
 
 cleanup:
     mbedtls_platform_zeroize( buf, sizeof( buf ) );
@@ -329,6 +342,10 @@ int mbedtls_md_hmac_starts( mbedtls_md_context_t *ctx, const unsigned char *key,
     unsigned char *ipad, *opad;
     size_t i;
 
+    mbedtls_md_starts_func_t *starts;
+    mbedtls_md_update_func_t *update;
+    mbedtls_md_finish_func_t *finish;
+
     if( ctx == NULL                               ||
         ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
         ctx->hmac_ctx == NULL )
@@ -336,24 +353,30 @@ int mbedtls_md_hmac_starts( mbedtls_md_context_t *ctx, const unsigned char *key,
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     }
 
-    if( keylen > (size_t) ctx->md_info->block_size )
+    starts = mbedtls_md_info_starts_func( ctx->md_info );
+    update = mbedtls_md_info_update_func( ctx->md_info );
+    finish = mbedtls_md_info_finish_func( ctx->md_info );
+
+    if( keylen > (size_t) mbedtls_md_info_block_size( ctx->md_info ) )
     {
-        if( ( ret = ctx->md_info->starts_func( ctx->md_ctx ) ) != 0 )
+        if( ( ret = starts( ctx->md_ctx ) ) != 0 )
-            goto cleanup;
-        if( ( ret = ctx->md_info->update_func( ctx->md_ctx, key, keylen ) ) != 0 )
-            goto cleanup;
-        if( ( ret = ctx->md_info->finish_func( ctx->md_ctx, sum ) ) != 0 )
             goto cleanup;
 
-        keylen = ctx->md_info->size;
+        if( ( ret = update( ctx->md_ctx, key, keylen ) ) )
+            goto cleanup;
+
+        if( ( ret = finish( ctx->md_ctx, sum ) ) != 0 )
+            goto cleanup;
+
+        keylen = mbedtls_md_info_size( ctx->md_info );
         key = sum;
     }
 
     ipad = (unsigned char *) ctx->hmac_ctx;
-    opad = (unsigned char *) ctx->hmac_ctx + ctx->md_info->block_size;
+    opad = (unsigned char *) ctx->hmac_ctx + mbedtls_md_info_block_size( ctx->md_info );
 
-    memset( ipad, 0x36, ctx->md_info->block_size );
+    memset( ipad, 0x36, mbedtls_md_info_block_size( ctx->md_info ) );
-    memset( opad, 0x5C, ctx->md_info->block_size );
+    memset( opad, 0x5C, mbedtls_md_info_block_size( ctx->md_info ) );
 
     for( i = 0; i < keylen; i++ )
     {
@@ -361,10 +384,10 @@ int mbedtls_md_hmac_starts( mbedtls_md_context_t *ctx, const unsigned char *key,
         opad[i] = (unsigned char)( opad[i] ^ key[i] );
     }
 
-    if( ( ret = ctx->md_info->starts_func( ctx->md_ctx ) ) != 0 )
+    if( ( ret = starts( ctx->md_ctx ) ) != 0 )
         goto cleanup;
-    if( ( ret = ctx->md_info->update_func( ctx->md_ctx, ipad,
+
-                                           ctx->md_info->block_size ) ) != 0 )
+    if( ( ret = update( ctx->md_ctx, ipad, mbedtls_md_info_block_size( ctx->md_info ) ) ) != 0 )
         goto cleanup;
 
 cleanup:
@@ -382,7 +405,8 @@ int mbedtls_md_hmac_update( mbedtls_md_context_t *ctx, const unsigned char *inpu
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     }
 
-    return( ctx->md_info->update_func( ctx->md_ctx, input, ilen ) );
+    return( mbedtls_md_info_update_func( ctx->md_info )(
+                ctx->md_ctx, input, ilen ) );
 }
 
 int mbedtls_md_hmac_finish( mbedtls_md_context_t *ctx, unsigned char *output )
@@ -391,6 +415,10 @@ int mbedtls_md_hmac_finish( mbedtls_md_context_t *ctx, unsigned char *output )
     unsigned char tmp[MBEDTLS_MD_MAX_SIZE];
     unsigned char *opad;
 
+    mbedtls_md_starts_func_t *starts;
+    mbedtls_md_update_func_t *update;
+    mbedtls_md_finish_func_t *finish;
+
     if( ctx == NULL                               ||
         ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
         ctx->hmac_ctx == NULL )
@@ -398,19 +426,28 @@ int mbedtls_md_hmac_finish( mbedtls_md_context_t *ctx, unsigned char *output )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     }
 
-    opad = (unsigned char *) ctx->hmac_ctx + ctx->md_info->block_size;
+    starts = mbedtls_md_info_starts_func( ctx->md_info );
+    update = mbedtls_md_info_update_func( ctx->md_info );
+    finish = mbedtls_md_info_finish_func( ctx->md_info );
 
-    if( ( ret = ctx->md_info->finish_func( ctx->md_ctx, tmp ) ) != 0 )
+    opad = (unsigned char *) ctx->hmac_ctx + mbedtls_md_info_block_size( ctx->md_info );
+
+    if( ( ret = finish( ctx->md_ctx, tmp ) ) != 0 )
         return( ret );
-    if( ( ret = ctx->md_info->starts_func( ctx->md_ctx ) ) != 0 )
+
+    if( ( ret = starts( ctx->md_ctx ) ) != 0 )
         return( ret );
-    if( ( ret = ctx->md_info->update_func( ctx->md_ctx, opad,
+
-                                           ctx->md_info->block_size ) ) != 0 )
+    if( ( ret = update( ctx->md_ctx, opad, mbedtls_md_info_block_size( ctx->md_info ) ) ) != 0 )
         return( ret );
-    if( ( ret = ctx->md_info->update_func( ctx->md_ctx, tmp,
+
-                                           ctx->md_info->size ) ) != 0 )
+    if( ( ret = update( ctx->md_ctx, tmp, mbedtls_md_info_size( ctx->md_info ) ) ) != 0 )
         return( ret );
-    return( ctx->md_info->finish_func( ctx->md_ctx, output ) );
+
+    if( ( ret = finish( ctx->md_ctx, output ) ) != 0 )
+        return( ret );
+
+    return( 0 );
 }
 
 int mbedtls_md_hmac_reset( mbedtls_md_context_t *ctx )
@@ -427,10 +464,13 @@ int mbedtls_md_hmac_reset( mbedtls_md_context_t *ctx )
 
     ipad = (unsigned char *) ctx->hmac_ctx;
 
-    if( ( ret = ctx->md_info->starts_func( ctx->md_ctx ) ) != 0 )
+    ret = mbedtls_md_info_starts_func( ctx->md_info )( ctx->md_ctx );
+    if( ret != 0 )
+        return( ret );
+
+    ret = mbedtls_md_info_update_func( ctx->md_info )(
+        ctx->md_ctx, ipad, mbedtls_md_info_block_size( ctx->md_info ) );
     return( ret );
-    return( ctx->md_info->update_func( ctx->md_ctx, ipad,
-                                       ctx->md_info->block_size ) );
 }
 
 int mbedtls_md_hmac( mbedtls_md_handle_t md_info,
@@ -470,7 +510,8 @@ int mbedtls_md_process( mbedtls_md_context_t *ctx, const unsigned char *data )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     }
 
-    return( ctx->md_info->process_func( ctx->md_ctx, data ) );
+    return( mbedtls_md_info_process_func( ctx->md_info )(
+                ctx->md_ctx, data ) );
 }
 
 unsigned char mbedtls_md_get_size( mbedtls_md_handle_t md_info )
@@ -478,7 +519,7 @@ unsigned char mbedtls_md_get_size( mbedtls_md_handle_t md_info )
     if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( 0 );
 
-    return md_info->size;
+    return mbedtls_md_info_size( md_info );
 }
 
 mbedtls_md_type_t mbedtls_md_get_type( mbedtls_md_handle_t md_info )
@@ -486,7 +527,7 @@ mbedtls_md_type_t mbedtls_md_get_type( mbedtls_md_handle_t md_info )
     if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_MD_NONE );
 
-    return md_info->type;
+    return mbedtls_md_info_type( md_info );
 }
 
 const char *mbedtls_md_get_name( mbedtls_md_handle_t md_info )
@@ -494,7 +535,7 @@ const char *mbedtls_md_get_name( mbedtls_md_handle_t md_info )
     if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( NULL );
 
-    return md_info->name;
+    return mbedtls_md_info_name( md_info );
 }
 
 #endif /* MBEDTLS_MD_C */

tests/suites/test_suite_hkdf.function

@@ -114,7 +114,7 @@ exit:
 }
 /* END_CASE */
 
-/* BEGIN_CASE */
+/* BEGIN_CASE depends_on:!MBEDTLS_MD_SINGLE_HASH */
 void test_hkdf_extract_ret( int hash_len, int ret )
 {
     int output_ret;
@@ -141,7 +141,7 @@ exit:
 }
 /* END_CASE */
 
-/* BEGIN_CASE */
+/* BEGIN_CASE depends_on:!MBEDTLS_MD_SINGLE_HASH */
 void test_hkdf_expand_ret( int hash_len, int prk_len, int okm_len, int ret )
 {
     int output_ret;