From 3303d7d70d4b9749c39ca87085d17495beab6030 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <koszko@koszko.org>
Date: Thu, 26 Aug 2021 15:53:23 +0200
Subject: filter HTTP request headers to remove Hachette cookies in case they
 slip through

---
 background/cookie_filter.js | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 background/cookie_filter.js

(limited to 'background/cookie_filter.js')

diff --git a/background/cookie_filter.js b/background/cookie_filter.js
new file mode 100644
index 0000000..fea2d23
--- /dev/null
+++ b/background/cookie_filter.js
@@ -0,0 +1,45 @@
+/**
+ * part of Hachette
+ * Filtering request headers to remove hachette cookies that might have slipped
+ * through.
+ *
+ * Copyright (C) 2021 Wojtek Kosior
+ * Redistribution terms are gathered in the `copyright' file.
+ */
+
+/*
+ * IMPORTS_START
+ * IMPORT extract_signed
+ * IMPORTS_END
+ */
+
+function is_valid_hachette_cookie(cookie)
+{
+    const match = /^hachette-(\w*)=(.*)$/.exec(cookie);
+    if (!match)
+	return false;
+
+    return !extract_signed(match.slice(1, 3)).fail;
+}
+
+function remove_hachette_cookies(header)
+{
+    if (header.name !== "Cookie")
+	return header;
+
+    const cookies = header.value.split("; ");
+    const value = cookies.filter(c => !is_valid_hachette_cookie(c)).join("; ");
+
+    return value ? {name: "Cookie", value} : null;
+}
+
+function filter_cookie_headers(headers)
+{
+    return headers.map(remove_hachette_cookies).filter(h => h);
+}
+
+/*
+ * EXPORTS_START
+ * EXPORT filter_cookie_headers
+ * EXPORTS_END
+ */
-- 
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