Merge commit 'ecb787046271de708b94da70240713e725299d86'

1 files changed, 53 insertions, 11 deletions

diff --git a/common/misc.js b/common/misc.js
index 7e48059..8cb26ab 100644
--- a/common/misc.js
+++ b/common/misc.js
@@ -15,6 +15,14 @@
  * IMPORTS_END
  */
 
+/* Generate a random base64-encoded 128-bit sequence */
+function gen_nonce()
+{
+    let randomData = new Uint8Array(16);
+    crypto.getRandomValues(randomData);
+    return btoa(String.fromCharCode.apply(null, randomData));
+}
+
 /*
  * generating unique, per-site value that can be computed synchronously
  * and is impossible to guess for a malicious website
@@ -61,24 +69,51 @@ function url_item(url)
 }
 
 /*
- * Assume a url like: https://example.com/green?illuminati=confirmed#tinky#winky
+ * Assume a url like:
+ *     https://example.com/green?illuminati=confirmed#<injected-policy>#winky
  * This function will make it into an object like:
  * {
- *     "base_url" : "https://example.com/green?illuminati=confirmed",
- *     "target" : "#tinky",
- *     "target2" : "#winky"
+ *     "base_url": "https://example.com/green?illuminati=confirmed",
+ *     "target":   "#<injected-policy>",
+ *     "target2":  "#winky",
+ *     "policy":   <injected-policy-as-js-object>,
+ *     "current":  <boolean-indicating-whether-policy-url-matches>
  * }
  * In case url doesn't have 2 #'s, target2 and target can be set to undefined.
  */
 function url_extract_target(url)
 {
-    let url_re = /^([^#]*)((#[^#]*)(#.*)?)?$/;
-    let match = url_re.exec(url);
-    return {
-	base_url : match[1],
-	target : match[3],
-	target2 : match[4]
+    const url_re = /^([^#]*)((#[^#]*)(#.*)?)?$/;
+    const match = url_re.exec(url);
+    const targets  = {
+	base_url: match[1],
+	target:   match[3] || "",
+	target2:  match[4] || ""
     };
+    if (!targets.target)
+	return targets;
+
+    /* %7B -> { */
+    const index = targets.target.indexOf('%7B');
+    if (index === -1)
+	return targets;
+
+    const now = new Date();
+    const sig = targets.target.substring(1, index);
+    const policy = targets.target.substring(index);
+    if (sig !== sign_policy(policy, now) &&
+	sig !== sign_policy(policy, now, -1))
+	return targets;
+
+    try {
+	targets.policy = JSON.parse(decodeURIComponent(policy));
+	targets.current = targets.policy.base_url === targets.base_url;
+    } catch (e) {
+	/* This should not be reached - it's our self-produced valid JSON. */
+	console.log("Unexpected internal error - invalid JSON smuggled!", e);
+    }
+
+    return targets;
 }
 
 /* csp rule that blocks all scripts except for those injected by us */
@@ -113,12 +148,19 @@ function is_privileged_url(url)
     return !!/^(chrome(-extension)?|moz-extension):\/\/|^about:/i.exec(url);
 }
 
+/* Sign a given policy for a given time */
+function sign_policy(policy, now, hours_offset) {
+    let time = Math.floor(now / 3600000) + (hours_offset || 0);
+    return gen_unique(time + policy);
+}
+
 /*
  * EXPORTS_START
- * EXPORT gen_unique
  * EXPORT gen_nonce
+ * EXPORT gen_unique
  * EXPORT url_item
  * EXPORT url_extract_target
+ * EXPORT sign_policy
  * EXPORT csp_rule
  * EXPORT nice_name
  * EXPORT open_in_settings