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authorroot <root@rbsd.ankarstrom.se>2021-04-29 00:02:41 +0000
committerroot <root@rbsd.ankarstrom.se>2021-04-29 00:11:29 +0000
commit96e026c1815f123e5a60ee106cb802fc841faa6c (patch)
tree5f410a9d50a757e21b104afc2d22a8a22551b60d /README
parent6cac80b5c80e89ac46e8a8fc928aa98de183a47f (diff)
downloadApache-Inject-96e026c1815f123e5a60ee106cb802fc841faa6c.tar.gz
Fix filter-related bugHEADmaster
Apparently, an Apache filter can be invoked more than once for a single request, depending on the size of the contents [1]. Luckily, though, a filter can save state in the ctx field [1,2]. The solution isn't perfect, as it can't handle arbitrary long heads, but they're very unlikely. [1] https://httpd.apache.org/docs/2.4/developer/output-filters.html#invocation [2] https://perl.apache.org/docs/2.0/user/handlers/filters.html#Introducing_Filters
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@@ -116,31 +116,36 @@ OPERATION
and forwards their combined contents.
CAVEATS
- Apache::Inject::Filter uses a regular expression to determine the proper
- location of the injected header. It supports all valid HTML. However, it
- does not parse embedded CSS and JavaScript, which means that it is
- *possible* to construct an example where it will fail:
-
- <script>
- /* this looks like the closing tag for script: </script> */
- /* this looks like an opening tag for a new element: <title> */
- </script>
- <body>
- This is where the header <i>should</i> be inserted.
- <script>
- /* this looks like the closing tag for the title: </title>
- This is where the header is <i>actually</i> inserted.
- */
- </script>
- </body>
-
- This specific type of document, however, is *incredibly* unlikely. In
- this case, an ad-hoc solution is simpler, more efficient and more
- maintainable than a general one.
-
- On FreeBSD, you may need to enable the accf_http kernel module in order
- for the tests to work. Note that Apache::Inject works fine without the
- module; it is only the tests that require it.
+ * Apache::Inject::Filter uses a regular expression to determine the
+ proper location of the injected header. It supports all valid HTML.
+ However, it does not parse embedded CSS and JavaScript, which means
+ that it is *possible* to construct an example where it will fail:
+
+ <script>
+ /* this looks like the closing tag for script: </script> */
+ /* this looks like an opening tag for a new element: <title> */
+ </script>
+ <body>
+ This is where the header <i>should</i> be inserted.
+ <script>
+ /* this looks like the closing tag for the title: </title>
+ This is where the header is <i>actually</i> inserted.
+ */
+ </script>
+ </body>
+
+ This specific type of document, however, is *incredibly* unlikely.
+ In this case, an ad-hoc solution is simpler, more efficient and more
+ maintainable than a general one.
+
+ * Because of how Apache filters work, Inject may fail to find the end
+ of the <head> if the <head> is very long (in my experience over 7000
+ characters). If this happens, it will decline the request, and the
+ contents will be served as though Inject had not been enabled.
+
+ * On FreeBSD, you may need to enable the accf_http kernel module in
+ order for the tests to work. Note that Apache::Inject works fine
+ without the module; it is only the tests that require it.
DIAGNOSTICS
Apache::Inject and Apache::Inject::Filter log all errors and warnings to