Merge pull request #3176 from aggarg/development

Add support for const error description strings

include/mbedtls/error.h

@@ -127,6 +127,36 @@ extern "C" {
  */
 void mbedtls_strerror( int errnum, char *buffer, size_t buflen );
 
+/**
+ * \brief Translate the high-level part of an Mbed TLS error code into a string
+ *        representation.
+ *
+ * This function returns a const pointer to an un-modifiable string. The caller
+ * must not try to modify the string. It is intended to be used mostly for
+ * logging purposes.
+ *
+ * \param error_code    error code
+ *
+ * \return The string representation of the error code, or \c NULL if the error
+ *         code is unknown.
+ */
+const char * mbedtls_high_level_strerr( int error_code );
+
+/**
+ * \brief Translate the low-level part of an Mbed TLS error code into a string
+ *        representation.
+ *
+ * This function returns a const pointer to an un-modifiable string. The caller
+ * must not try to modify the string. It is intended to be used mostly for
+ * logging purposes.
+ *
+ * \param error_code    error code
+ *
+ * \return The string representation of the error code, or \c NULL if the error
+ *         code is unknown.
+ */
+const char * mbedtls_low_level_strerr( int error_code );
+
 #ifdef __cplusplus
 }
 #endif

scripts/data_files/error.fmt

@@ -42,10 +42,60 @@
 
 HEADER_INCLUDED
 
+const char * mbedtls_high_level_strerr( int error_code )
+{
+    int high_level_error_code;
+    const char *error_description = NULL;
+
+    if( error_code < 0 )
+        error_code = -error_code;
+
+    /* Extract the high-level part from the error code. */
+    high_level_error_code = error_code & 0xFF80;
+
+    switch( high_level_error_code )
+    {
+        /* Begin Auto-Generated Code. */
+HIGH_LEVEL_CODE_CHECKS
+        /* End Auto-Generated Code. */
+
+        default:
+            break;
+    }
+
+    return error_description;
+}
+
+const char * mbedtls_low_level_strerr( int error_code )
+{
+    int low_level_error_code;
+    const char *error_description = NULL;
+
+    if( error_code < 0 )
+        error_code = -error_code;
+
+    /* Extract the low-level part from the error code. */
+    low_level_error_code = error_code & ~0xFF80;
+
+    switch( low_level_error_code )
+    {
+        /* Begin Auto-Generated Code. */
+LOW_LEVEL_CODE_CHECKS
+        /* End Auto-Generated Code. */
+
+        default:
+            break;
+    }
+
+    return error_description;
+}
+
 void mbedtls_strerror( int ret, char *buf, size_t buflen )
 {
     size_t len;
     int use_ret;
+    const char * high_level_error_description = NULL;
+    const char * low_level_error_description = NULL;
 
     if( buflen == 0 )
         return;
@@ -59,14 +109,20 @@ void mbedtls_strerror( int ret, char *buf, size_t buflen )
     {
         use_ret = ret & 0xFF80;
 
-        // High level error codes
+        // Translate high level error code.
-        //
+        high_level_error_description = mbedtls_high_level_strerr( ret );
-        // BEGIN generated code
-HIGH_LEVEL_CODE_CHECKS
-        // END generated code
 
-        if( strlen( buf ) == 0 )
+        if( high_level_error_description == NULL )
             mbedtls_snprintf( buf, buflen, "UNKNOWN ERROR CODE (%04X)", use_ret );
+        else
+            mbedtls_snprintf( buf, buflen, "%s", high_level_error_description );
+
+#if defined(MBEDTLS_SSL_TLS_C)
+        // Early return in case of a fatal error - do not try to translate low
+        // level code.
+        if(use_ret == -(MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE))
+            return;
+#endif /* MBEDTLS_SSL_TLS_C */
     }
 
     use_ret = ret & ~0xFF80;
@@ -90,16 +146,13 @@ HIGH_LEVEL_CODE_CHECKS
         buflen -= len + 3;
     }
 
-    // Low level error codes
+    // Translate low level error code.
-    //
+    low_level_error_description = mbedtls_low_level_strerr( ret );
-    // BEGIN generated code
-LOW_LEVEL_CODE_CHECKS
-    // END generated code
 
-    if( strlen( buf ) != 0 )
+    if( low_level_error_description == NULL )
-        return;
+        mbedtls_snprintf( buf, buflen, "UNKNOWN ERROR CODE (%04X)", use_ret );
-
+    else
-    mbedtls_snprintf( buf, buflen, "UNKNOWN ERROR CODE (%04X)", use_ret );
+        mbedtls_snprintf( buf, buflen, "%s", low_level_error_description );
 }
 
 #else /* MBEDTLS_ERROR_C */

scripts/generate_errors.pl

@@ -119,7 +119,7 @@ foreach my $line (@matches)
     {
         $code_check = \$ll_code_check;
         $old_define = \$ll_old_define;
-        $white_space = '    ';
+        $white_space = '        ';
     }
     else
     {
@@ -160,19 +160,9 @@ foreach my $line (@matches)
         ${$old_define} = $define_name;
     }
 
-    if ($error_name eq "MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE")
+    ${$code_check} .= "${white_space}case -($error_name):\n".
-    {
+                      "${white_space}    error_description = \"$module_name - $description\";\n".
-        ${$code_check} .= "${white_space}if( use_ret == -($error_name) )\n".
+                      "${white_space}    break;\n"
-                          "${white_space}\{\n".
-                          "${white_space}    mbedtls_snprintf( buf, buflen, \"$module_name - $description\" );\n".
-                          "${white_space}    return;\n".
-                          "${white_space}}\n"
-    }
-    else
-    {
-        ${$code_check} .= "${white_space}if( use_ret == -($error_name) )\n".
-                          "${white_space}    mbedtls_snprintf( buf, buflen, \"$module_name - $description\" );\n"
-    }
 };
 
 if ($ll_old_define ne "")