Cookie Login in Chrome Extension

cookieLoginChromeExtension.js

// This goes into background/index.js
function parseJwt(token) {
  // Decode base64url encoded string
  function base64UrlDecode(str) {
      return decodeURIComponent(
          atob(str.replace(/_/g, "/").replace(/-/g, "+"))
          .split("")
          .map(c => '%' + c.charCodeAt(0).toString(16).padStart(2, '0'))
          .join("")
      );
  }

  try {
      // Split the JWT token into its three parts
      const parts = token.split(".");
      if (parts.length !== 3) {
          throw new Error("Invalid JWT token");
      }

      // Decode the payload
      const payload = JSON.parse(base64UrlDecode(parts[1]));

      // Check the expiration time
      const currentTime = Math.floor(Date.now() / 1000); // Current time in seconds since epoch
      const isExpired = payload.exp && payload.exp < currentTime;

      return {
          payload,
          isExpired,
      };
  } catch (error) {
      console.error("Error decoding JWT token:", error);
      return null;
  }
}

chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
  if (request.action === 'validLogin') {
    try {
      chrome.cookies.get({ url: 'https://yourdomain', name: 'yourcookiename' }, (cookie) => {
        const result = cookie ? parseJwt(cookie.value) : null;
        if (result && !result.isExpired) {
          console.log("Token Payload:", result.payload);
          console.log("Is Token Expired?", result.isExpired);
          sendResponse({ isValid: true });
        } else {
          console.log("Failed to decode the token");
          sendResponse({ isValid: false });
        }
      });
    } catch (error) {
      sendResponse({ isValid: false });
    }
    return true; // keep the message channel open until sendResponse is called
  }
});

// This goes into your content script
let isLoggedIn = false;
chrome.runtime.sendMessage({ action: 'validLogin' }, (response) => {
  isLoggedIn = response.isValid;
});

// This goes into manifest
{
  permissions: ['cookies'],
  host_permissions: [
    "https://yourdomain/*"
  ],
  externally_connectable: {
    matches: [
      'https://yourdomain/*',
    ],
  }
}