so close!

browser/background.js

@@ -1,13 +1,39 @@
-function handle(requestDetails) {
-    let b64 = btoa(requestDetails.url)
-    if (!requestDetails.url.startsWith("http://localhost")) {
-        console.log(`Loading: ${requestDetails.url} || ${b64}`);
+function handle_header(req) {
+    // Headers
+    // let x = req.requestHeaders;
+    // if (!x) {
+    x = new Headers()
+    // }
+    x.append("og", old)
+
+    console.log(x)
+
+    // appending header of the original url so that relative urls can be built into
+    // absolute urls
+    // TODO This doesn't work yet
+    return {
+        requestHeaders: x,
+    }
+}
+
+let old = ""
+
+function url_redirect (req)  {
+    let b64 = btoa(req.url)
+    if (!req.url.startsWith("http://localhost")) {
+        old = req.url
+        // console.debug(`Loading: ${req.url} || ${b64}`);
         return {
             redirectUrl: `http://localhost:4433/s3/${b64}`
         }
     }
 }
 
-browser.webRequest.onBeforeRequest.addListener(
-    handle, { urls: ["<all_urls>"] }, ["blocking"]
+browser.webRequest.onBeforeSendHeaders.addListener(
+    handle_header, { urls: ["<all_urls>"] }, ["blocking", "requestHeaders"]
 );
+
+browser.webRequest.onBeforeRequest.addListener(
+    url_redirect, { urls: ["<all_urls>"] }, ["blocking"]
+)
+