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authorWojtek Kosior <koszko@koszko.org>2021-08-23 11:05:51 +0200
committerWojtek Kosior <koszko@koszko.org>2021-08-23 11:05:51 +0200
commit6b53d6c840140fc5df6d7638808b978d96502a35 (patch)
tree87a76576824c49b65b1aa9f4213b63926ba7d243 /content/sanitize_document.js
parentd09b7ee10541b5a81430d2e11abb3a9a09643ade (diff)
downloadbrowser-extension-6b53d6c840140fc5df6d7638808b978d96502a35.tar.gz
browser-extension-6b53d6c840140fc5df6d7638808b978d96502a35.zip
use StreamFilter under Mozilla to prevent csp <meta> tags from blocking our injected scripts
Diffstat (limited to 'content/sanitize_document.js')
-rw-r--r--content/sanitize_document.js229
1 files changed, 182 insertions, 47 deletions
diff --git a/content/sanitize_document.js b/content/sanitize_document.js
index 1533526..727bb6c 100644
--- a/content/sanitize_document.js
+++ b/content/sanitize_document.js
@@ -43,76 +43,100 @@ function block_attribute(node, attr)
node.removeAttribute(attr);
}
-function sanitize_script(script, policy)
+function sanitize_script(script, data)
{
- if (policy.allow)
+ if (script.getAttribute("data-hachette-deleteme") === data.policy.nonce) {
+ script.remove();
+ script.hachette_deleted = true;
+ script.hachette_ignore = true;
+ }
+
+ if (data.policy.allow)
return;
block_attribute(script, "type");
script.setAttribute("type", "application/json");
}
-function inject_csp(head, policy)
+function inject_csp(head, data)
{
- if (policy.allow)
+ if (data.policy.allow)
return;
const meta = document.createElement("meta");
meta.setAttribute("http-equiv", "Content-Security-Policy");
- meta.setAttribute("content", csp_rule(policy.nonce));
+ meta.setAttribute("content", csp_rule(data.policy.nonce));
meta.hachette_ignore = true;
head.prepend(meta);
+
+ data.new_added.unshift([meta, head]);
}
-function sanitize_http_equiv_csp_rule(meta, policy)
+function sanitize_http_equiv_csp_rule(meta, data)
{
const http_equiv = meta.getAttribute("http-equiv");
+ const value = meta.content;
- if (!is_csp_header_name(http_equiv, !policy.allow))
+ if (!value || !is_csp_header_name(http_equiv, !data.policy.allow))
return;
- if (policy.allow || is_csp_header_name(http_equiv, false)) {
- let value = meta.getAttribute("content");
- block_attribute(meta, "content");
- if (value) {
- value = sanitize_csp_header({value}, policy).value;
- meta.setAttribute("content", value);
- }
- return;
- }
+ block_attribute(meta, "content");
- block_attribute(meta, "http-equiv");
+ if (data.policy.allow || is_csp_header_name(http_equiv, false))
+ meta.content = sanitize_csp_header({value}, data.policy).value;
}
-function sanitize_node(node, policy)
+function sanitize_node(node, data)
{
if (node.tagName === "SCRIPT")
- sanitize_script(node, policy);
+ sanitize_script(node, data);
if (node.tagName === "HEAD")
- inject_csp(node, policy);
+ inject_csp(node, data);
if (node.tagName === "META")
- sanitize_http_equiv_csp_rule(node, policy);
+ sanitize_http_equiv_csp_rule(node, data);
+
+ if (!data.policy.allow)
+ sanitize_attributes(node, data);
+}
- if (!policy.allow)
- sanitize_attributes(node, policy);
+/*
+ * Instead of calling writer directly with multiple small chunks of reconstruced
+ * HTML code, we utilize `setTimeout()' to only have it called once,
+ * asynchronously.
+ */
+function do_write_callback(data)
+{
+ data.writer(data.chunks.join(""));
+ data.chunks = [];
+
+ if (data.finished && data.finisher)
+ data.finisher();
+}
+
+function do_write(chunk, data)
+{
+ data.chunks.push(chunk);
+ clearTimeout(data.write_timeout);
+ data.write_timeout = setTimeout(() => do_write_callback(data), 0);
}
const serializer = new XMLSerializer();
-function start_node(node, data)
+function start_serializing_node(node, data)
{
+ node.hachette_started = true;
+
if (!data.writer)
return;
- node.hachette_started = true;
const clone = node.cloneNode(false);
clone.textContent = data.uniq;
- data.writer(data.uniq_reg.exec(clone.outerHTML)[1]);
+ do_write(data.uniq_reg.exec(clone.outerHTML)[1], data);
}
-function finish_node(node, data)
+function finish_serializing_node(node, data)
{
const nodes_to_process = [node];
@@ -127,40 +151,103 @@ function finish_node(node, data)
while (nodes_to_process.length > 0) {
const node = nodes_to_process.pop();
node.remove();
+ node.hachette_ignore = true;
if (!data.writer)
continue;
if (node.hachette_started) {
node.textContent = data.uniq;
- data.writer(data.uniq_reg.exec(node.outerHTML)[2]);
+ do_write(data.uniq_reg.exec(node.outerHTML)[2], data);
+ continue;
+ }
+
+ do_write(node.outerHTML || serializer.serializeToString(node), data);
+ }
+}
+
+function process_initial_nodes(node, data)
+{
+ if (data.processed_initial_nodes)
+ return;
+
+ data.processed_initial_nodes = true;
+
+ start_serializing_node(data.html_root, data);
+
+ const new_added = [];
+ const nodes_to_process = [data.html_root];
+
+ let i = 0;
+ while (nodes_to_process.length > 0) {
+ let current = nodes_to_process.shift();
+
+ if (current.firstChild) {
+ if (current.firstChild === node)
+ break;
+ nodes_to_process.unshift(current.firstChild, current);
+ new_added.push([current.firstChild, current]);
continue;
}
- data.writer(node.outerHTML || serializer.serializeToString(node));
+ while (current && !current.nextSibling)
+ current = nodes_to_process.shift();
+
+ if (!current || current.nextSibling === node)
+ break;
+
+ nodes_to_process.unshift(current.nextSibling);
+ new_added.push([current.nextSibling, nodes_to_process[1]]);
}
+
+ data.new_added.unshift(...new_added);
}
/*
* Important! Due to some weirdness node.parentElement is not alway correct
- * under Chromium. Track node relations manually.
+ * in MutationRecords under Chromium. Track node relations manually.
*/
function handle_added_node(node, true_parent, data)
{
- if (node.hachette_ignore || true_parent.hachette_ignore)
- return;
+ /*
+ * Functions we call here might cause new nodes to be injected or found
+ * that require processing before the one we got in function argument.
+ * We rely on those functions putting the node(s) they create/find at the
+ * very beginning of the `new_added' queue and (for created nodes) setting
+ * their `hachette_ignore' property, based on which their MutationRecord
+ * will not be processed. A function can also mark a node already in the
+ * `new_added' queue as not eligible for processing by setting its
+ * `hachette_deleted' property.
+ */
- if (!true_parent.hachette_started)
- start_node(true_parent, data)
+ process_initial_nodes(node, data);
- sanitize_node(node, data.policy);
+ data.new_added.push([node, true_parent]);
- if (data.node_eater)
- data.node_eater(node, true_parent);
+ while (data.new_added.length > 0) {
+ [node, true_parent] = data.new_added.shift();
- finish_node(true_parent.hachette_last_added, data);
+ if (true_parent.hachette_deleted)
+ node.hachette_deleted = true;
+ if (node.hachette_deleted)
+ continue;
+
+ if (!true_parent.hachette_started)
+ start_serializing_node(true_parent, data)
+
+ if (!node.hachette_ignore)
+ sanitize_node(node, data);
+
+ if (node.hachette_deleted)
+ continue;
+
+ if (data.node_eater)
+ data.node_eater(node, true_parent);
- true_parent.hachette_last_added = node;
+ finish_serializing_node(true_parent.hachette_last_added, data);
+
+ true_parent.hachette_last_added = node;
+ }
}
function handle_mutation(mutations, data)
@@ -170,28 +257,76 @@ function handle_mutation(mutations, data)
* node.parentElement. The former is the correct one.
*/
for (const mutation of mutations) {
- for (const node of mutation.addedNodes)
+ for (const node of mutation.addedNodes) {
+ /* Check for nodes added by ourselves. */
+ if (mutation.target.hachette_ignore)
+ node.hachette_ignore = true;
+ if (node.hachette_ignore)
+ continue;
+
handle_added_node(node, mutation.target, data);
+ }
}
}
function finish_processing(data)
{
+ process_initial_nodes(undefined, data);
+
+ /*
+ * The `finisher' callback should be called, if provided. Normally our
+ * function that performs the last write does it after seeing `finished'
+ * set to `true'. If, however, there's no `writer' callback and hence no
+ * writes to perform, we need to take care of calling `finisher' here.
+ */
+ data.finished = true;
handle_mutation(data.observer.takeRecords(), data);
- finish_node(data.html_element, data);
data.observer.disconnect();
+
+ /*
+ * Additional whitespace that was after `</body>' gets appended to body.
+ * Although it's a minor issue, it is not what we want. There's no way to
+ * tell exactly what part of that whitespace was after `</body>' and what
+ * was before, so we just replace it with a single newline which looks good
+ * when printed.
+ */
+ const body = data.html_root.lastChild;
+ const text = body && body.tagName === "BODY" && body.lastChild;
+ if (text && text.nodeName === "#text") {
+ const new_content = /^([\S\s]*\S)?\s*$/.exec(text.textContent)[1] || "";
+ text.textContent = new_content + "\n";
+ }
+
+ finish_serializing_node(data.html_root, data);
+ if (!data.writer && data.finisher)
+ setTimeout(data.finisher, 0);
}
-function modify_on_the_fly(html_element, policy, consumers)
+/*
+ * This function sanitizes `html_root' according to `policy'. It is capable of
+ * working on an HTML document that is being written to, sanitizing new nodes
+ * as they appear.
+ *
+ * `consumers' object may contain 3 optional callback functions: `writer',
+ * `node_eater' and `finisher'. The first one, if present, is called with chunks
+ * of reconstructed HTML code. The second one, if present, gets called for every
+ * added node with 2 arguments: that node and its parent. The third one is
+ * called at the end, after all processing has been done.
+ *
+ * `modify_on_the_fly()' returns a callback that should be called (with no
+ * arguments) once the document of html_root has finished being written to.
+ * Unfortunately, due to specifics behavior of document that has had its
+ * documentElement replaced
+ */
+function modify_on_the_fly(html_root, policy, consumers)
{
const uniq = gen_nonce();
- const uniq_reg = new RegExp(`^(.*)${uniq}(.*)$`);
- const data = {policy, html_element, uniq, uniq_reg, ...consumers};
-
- start_node(data.html_element, data);
+ const uniq_reg = new RegExp(`^([\\s\\S]*)${uniq}([\\s\\S]*)$`);
+ const data = {policy, html_root, uniq, uniq_reg, chunks: [], new_added: []};
+ Object.assign(data, consumers);
var observer = new MutationObserver(m => handle_mutation(m, data));
- observer.observe(data.html_element, {
+ observer.observe(data.html_root, {
attributes: true,
childList: true,
subtree: true