internet_mapper_viewer/browser/background.js

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.onBeforeSendHeaders.addListener(
    handle_header, { urls: ["<all_urls>"] }, ["blocking", "requestHeaders"]
);

browser.webRequest.onBeforeRequest.addListener(
    url_redirect, { urls: ["<all_urls>"] }, ["blocking"]
)