commit e5702489f503f1fc26debc846cb3f4c0ab0b5b66
author Gilles Peskine <Gilles.Peskine@arm.com> Fri Jun 11 21:59:08 2021 +0200
committer Gilles Peskine <Gilles.Peskine@arm.com> Tue Jun 15 00:14:28 2021 +0200
tree 6c01de4fee0d751fa269fb8aa02fdcbbb145174f
parent cadd3d860ee5fba1e380200d2866f75843fc3579

mbedtls_dhm_get_value parameter order: context first, output last

mbedtls_dhm_get_value can be seen as either a copy function or a getter
function. Given the name and the semantics, it's more of a getter, even if
it "gets" by doing a copy. Therefore, put the context first, and the
selector next, leaving the output for last.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

include/mbedtls/dhm.h

diff --git a/include/mbedtls/dhm.h b/include/mbedtls/dhm.h
index 6c319f8..e8c8a82 100644
--- a/include/mbedtls/dhm.h
+++ b/include/mbedtls/dhm.h
@@ -315,18 +315,18 @@
 /**
  * \brief          This function copies a parameter of a DHM key.
  *
- * \param dest     The MPI object to copy the value into. It must be
- *                 initialized.
  * \param ctx      The DHM context to query.
  * \param param    The parameter to copy.
+ * \param dest     The MPI object to copy the value into. It must be
+ *                 initialized.
  *
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_DHM_BAD_INPUT_DATA if \p field is invalid.
  * \return         An \c MBEDTLS_ERR_MPI_XXX error code if the copy fails.
  */
-int mbedtls_dhm_get_value( mbedtls_mpi *dest,
-                           const mbedtls_dhm_context *ctx,
-                           mbedtls_dhm_parameter param );
+int mbedtls_dhm_get_value( const mbedtls_dhm_context *ctx,
+                           mbedtls_dhm_parameter param,
+                           mbedtls_mpi *dest );
 
 /**
  * \brief          This function frees and clears the components

library/dhm.c

diff --git a/library/dhm.c b/library/dhm.c
index cb9299f..e88f3a2 100644
--- a/library/dhm.c
+++ b/library/dhm.c
@@ -134,9 +134,9 @@
     return( mbedtls_mpi_size( &ctx->P ) );
 }
 
-int mbedtls_dhm_get_value( mbedtls_mpi *dest,
-                           const mbedtls_dhm_context *ctx,
-                           mbedtls_dhm_parameter param )
+int mbedtls_dhm_get_value( const mbedtls_dhm_context *ctx,
+                           mbedtls_dhm_parameter param,
+                           mbedtls_mpi *dest )
 {
     const mbedtls_mpi *src = NULL;
     switch( param )

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index bef6864..560597d 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3871,10 +3871,10 @@
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
-    if( ( ret = mbedtls_dhm_get_value( &conf->dhm_P, dhm_ctx,
-                                       MBEDTLS_DHM_PARAM_P ) ) != 0 ||
-        ( ret = mbedtls_dhm_get_value( &conf->dhm_G, dhm_ctx,
-                                       MBEDTLS_DHM_PARAM_G ) ) != 0 )
+    if( ( ret = mbedtls_dhm_get_value( dhm_ctx, MBEDTLS_DHM_PARAM_P,
+                                       &conf->dhm_P ) ) != 0 ||
+        ( ret = mbedtls_dhm_get_value( dhm_ctx, MBEDTLS_DHM_PARAM_G,
+                                       &conf->dhm_G ) ) != 0 )
     {
         mbedtls_mpi_free( &conf->dhm_P );
         mbedtls_mpi_free( &conf->dhm_G );

tests/suites/test_suite_dhm.function

diff --git a/tests/suites/test_suite_dhm.function b/tests/suites/test_suite_dhm.function
index d48c4e3..62e634a 100644
--- a/tests/suites/test_suite_dhm.function
+++ b/tests/suites/test_suite_dhm.function
@@ -9,7 +9,7 @@
     int ok = 0;
     mbedtls_mpi_init( &actual );
 
-    TEST_ASSERT( mbedtls_dhm_get_value( &actual, ctx, param ) == 0 );
+    TEST_ASSERT( mbedtls_dhm_get_value( ctx, param, &actual ) == 0 );
     TEST_ASSERT( mbedtls_mpi_cmp_mpi( &actual, expected ) == 0 );
     ok = 1;