GH-237: add @load foo.bro -> foo.zeek fallback

When failing to locate a script with explicit .bro suffix, check for
whether one with a .zeek suffix exists and use it instead.

CHANGES

@@ -1,4 +1,11 @@
 
+2.6-227 | 2019-04-16 17:44:31 -0700
+
+  * GH-237: add `@load foo.bro` -> foo.zeek fallback (Jon Siwek, Corelight)
+
+    When failing to locate a script with explicit .bro suffix, check for
+    whether one with a .zeek suffix exists and use it instead.
+
 2.6-225 | 2019-04-16 16:07:49 -0700
 
   * Use .zeek file suffix in unit tests (Jon Siwek, Corelight)

NEWS

@@ -81,10 +81,12 @@ Changed Functionality
   been renamed to ``.zeek``.
 
 - The search logic for the ``@load`` script directive now prefers files
-  ending in ``.zeek``, but will fallback to loading a ``.bro`` file if it
+  ending in ``.zeek``, but will fallback to loading a ``.bro`` file if
-  exists.  E.g. ``@load foo`` will check for ``foo.zeek`` and then ``foo.bro``.
+  it exists.  E.g. ``@load foo`` will first check for a ``foo.zeek``
-  Note that ``@load foo.bro`` will not automatically check for
+  file to load and then otherwise ``foo.bro``.  Note that
-  ``@load foo.zeek``.
+  ``@load foo.bro`` (with the explicit ``.bro`` file suffix) prefers
+  in the opposite order: it first checks for ``foo.bro`` and then
+  falls back to a ``foo.zeek``, if it exists.
 
 - The for-loop index variable for vectors has been changed from
   'int' to 'count' type.  It's unlikely this would alter/break any

VERSION

@@ -1 +1 @@
-2.6-225
+2.6-227

src/util.cc

@@ -1298,6 +1298,14 @@ string find_file(const string& filename, const string& path_set,
 	return string();
 	}
 
+static bool ends_with(const std::string& s, const std::string& ending)
+	{
+	if ( ending.size() > s.size() )
+		return false;
+
+	return std::equal(ending.rbegin(), ending.rend(), s.rbegin());
+	}
+
 string find_script_file(const string& filename, const string& path_set)
 	{
 	vector<string> paths;
@@ -1313,6 +1321,14 @@ string find_script_file(const string& filename, const string& path_set)
 			return f;
 		}
 
+	if ( ends_with(filename, ".bro") )
+		{
+		// We were looking for a file explicitly ending in .bro and didn't
+		// find it, so fall back to one ending in .zeek, if it exists.
+		auto fallback = string(filename.data(), filename.size() - 4) + ".zeek";
+		return find_script_file(fallback, path_set);
+		}
+
 	return string();
 	}
 

testing/btest/Baseline/core.load-explicit-bro-suffix-fallback/out

@@ -0,0 +1 @@
+loaded foo.zeek

testing/btest/core/load-explicit-bro-suffix-fallback.zeek

@@ -0,0 +1,12 @@
+# @TEST-EXEC: bro -b %INPUT >out
+# @TEST-EXEC: btest-diff out
+
+# We don't have a foo.bro, but we'll accept foo.zeek.
+@load foo.bro
+
+@TEST-START-FILE foo.zeek
+event bro_init()
+	{
+	print "loaded foo.zeek";
+	}
+@TEST-END-FILE