[syslog-ng] [PATCH] template_escaping: escaping in templates is modified

[Viktor Juhasz]

From: Juhasz Viktor <jviktor at balabit.hu>

the '\' is parsed by lexer and the template_compile
used this character to escaping. It was confusing.
Now, it has to be used $$ for printing literal $ in the result

The other modification is the escaping of the '@' if it follows macro or
temlate function.
if non-numeric value follows the '@', use the '@' as a literal '@', but
show a warning message.
It has to be used '@@' for printing literal '@' in the result

Signed-off-by: Juhasz Viktor <jviktor at balabit.hu>
---
 lib/template/templates.c                   |   33 +++++++++++++++++++++++-----
 lib/template/tests/test_template_compile.c |   25 +++++++++++++++++++--
 2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/lib/template/templates.c b/lib/template/templates.c
index 436d645..442a7ec 100644
--- a/lib/template/templates.c
+++ b/lib/template/templates.c
@@ -882,13 +882,27 @@ parse_msg_ref(LogTemplateCompiler *self)
   if ((*self->cursor) == '@')
     {
       self->cursor++;
-      /* syntax: ${name}@1 to denote the log message index in the correllation state */
-      while ((*self->cursor) >= '0' && (*self->cursor) <= '9')
+      if ((*self->cursor) >= '0' && (*self->cursor) <= '9')
         {
-          self->msg_ref += self->msg_ref * 10 + ((*self->cursor) - '0');
-          self->cursor++;
+          /* syntax: ${name}@1 to denote the log message index in the correllation state */
+          while ((*self->cursor) >= '0' && (*self->cursor) <= '9')
+            {
+              self->msg_ref += self->msg_ref * 10 + ((*self->cursor) - '0');
+              self->cursor++;
+            }
+          self->msg_ref += 1;
+        }
+      else
+        {
+          if ((*self->cursor) != '@')
+            {
+              msg_warning("Non-numeric correlation state ID found, assuming a literal '@' character. To avoid confusion when using a literal '@' after a macro or template function, write '@@' in the template.",
+                          evt_tag_str("Template", self->template->template),
+                          NULL);
+              self->cursor--;
+            }
+          self->msg_ref = 0;
         }
-      self->msg_ref += 1;
     }
 }
 
@@ -1171,7 +1185,14 @@ log_template_compiler_process_token(LogTemplateCompiler *self, GError **error)
     }
   if (*self->cursor == '\\')
     {
-      self->cursor++;
+      if (cfg_is_config_version_older(self->template->cfg, 0x305))
+        {
+          msg_warning("Template escaping changed in version 3.5. Use '$$' to specify a literal dollar sign instead of '\\$' and remove the escaping of the backslash character when you upgrade your configuration",
+                      evt_tag_str("Template", self->template->template),
+                      NULL);
+          self->cursor++;
+        }
+
     }
   if (*self->cursor)
     {
diff --git a/lib/template/tests/test_template_compile.c b/lib/template/tests/test_template_compile.c
index efebfdd..21e1885 100644
--- a/lib/template/tests/test_template_compile.c
+++ b/lib/template/tests/test_template_compile.c
@@ -203,17 +203,22 @@ static void
 test_macro_with_invalid_msgref_are_recognized_as_the_top_element_in_the_stack(void)
 {
   assert_template_compile("${MESSAGE}@gmail.com");
-  assert_compiled_template(text = "", default_value = NULL, macro = M_MESSAGE, type = LTE_MACRO, msg_ref = 1);
+  assert_compiled_template(text = "", default_value = NULL, macro = M_MESSAGE, type = LTE_MACRO, msg_ref = 0);
 
   select_next_element();
-  assert_compiled_template(text = "gmail.com", default_value = NULL, macro = M_NONE, type = LTE_MACRO, msg_ref = 0);
+  assert_compiled_template(text = "@gmail.com", default_value = NULL, macro = M_NONE, type = LTE_MACRO, msg_ref = 0);
 }
 
 static void
 test_dollar_prefixed_with_backslash_is_a_literal_dollar(void)
 {
+  cfg_set_version(configuration, 0x304);
   assert_template_compile("Test \\$STRING");
   assert_compiled_template(text = "Test $STRING", default_value = NULL, macro = M_NONE, type = LTE_MACRO, msg_ref = 0);
+
+  cfg_set_version(configuration, 0x305);
+  assert_template_compile("Test \\$STRING");
+  assert_compiled_template(text = "Test \\", default_value = NULL, value_handle = log_msg_get_value_handle("STRING"), type = LTE_VALUE, msg_ref = 0);
 }
 
 static void
@@ -250,8 +255,23 @@ test_dollar_with_an_invalid_macro_name_without_braces_is_parsed_as_a_literal_dol
 static void
 test_backslash_without_finishing_the_escape_sequence_is_ignored(void)
 {
+  cfg_set_version(configuration, 0x304);
   assert_template_compile("foo\\");
   assert_compiled_template(text = "foo", default_value = NULL, macro = M_NONE, type = LTE_MACRO, msg_ref = 0);
+
+  cfg_set_version(configuration, 0x305);
+  assert_template_compile("foo\\");
+  assert_compiled_template(text = "foo\\", default_value = NULL, macro = M_NONE, type = LTE_MACRO, msg_ref = 0);
+}
+
+static void
+test_double_at_is_a_literal_at(void)
+{
+  assert_template_compile("${MESSAGE}@@12");
+  assert_compiled_template(text = "", default_value = NULL, macro = M_MESSAGE, type = LTE_MACRO, msg_ref = 0);
+
+  select_next_element();
+  assert_compiled_template(text = "@12", default_value = NULL, macro = M_NONE, type = LTE_MACRO, msg_ref = 0);
 }
 
 static void
@@ -270,6 +290,7 @@ test_template_compile_macro(void)
   TEMPLATE_TESTCASE(test_double_dollars_is_a_literal_dollar);
   TEMPLATE_TESTCASE(test_dollar_with_an_invalid_macro_name_without_braces_is_parsed_as_a_literal_dollar);
   TEMPLATE_TESTCASE(test_backslash_without_finishing_the_escape_sequence_is_ignored);
+  TEMPLATE_TESTCASE(test_double_at_is_a_literal_at);
 }
 
 static void
-- 
1.7.9.5