safetynet/apps/browser/page-clipboard-guard.cjs

'use strict';
// This capability stays in the main process. Neither pages nor agents receive CDP access.
const owners=new WeakMap();
function protectClipboardPrimitives(){
  const prototype=Document.prototype,existing=Object.getOwnPropertyDescriptor(prototype,'execCommand');
  if(existing?.value?._managedClipboardGuard===true&&!existing.configurable)return;
  const original=prototype.execCommand,apply=Reflect.apply,test=RegExp.prototype.test.bind(/^(copy|cut|paste)/i);
  function managedClipboardCommand(command,...args){
    if(typeof command!=='string'||test(command))return false;
    return apply(original,this,[command,...args]);
  }
  Object.defineProperty(managedClipboardCommand,'_managedClipboardGuard',{value:true});
  Object.defineProperty(prototype,'execCommand',{value:managedClipboardCommand,writable:false,configurable:false});
  const SecurityException=DOMException;
  const denyReplacement=()=>{throw new SecurityException('Managed document replacement is disabled','SecurityError');};
  for(const name of ['open','write','writeln'])Object.defineProperty(prototype,name,{value:denyReplacement,writable:false,configurable:false});
  const deny=event=>{event.preventDefault();event.stopImmediatePropagation();};
  for(const name of ['copy','cut','paste','dragstart','dragover','drop'])window.addEventListener(name,deny,true);
  const transferred=RegExp.prototype.test.bind(/^(insertFromPaste|insertFromDrop|deleteByCut)/);
  window.addEventListener('beforeinput',event=>{if(transferred(event.inputType||''))deny(event);},true);
}
const source=`(${protectClipboardPrimitives.toString()})();`;
function deadline(operation){let timer;return Promise.race([operation,new Promise((_,reject)=>{timer=setTimeout(()=>reject(Error('Page security initialization timed out')),5000);})]).finally(()=>clearTimeout(timer));}
async function attachPageClipboardGuard(contents,onFailure){
  const api=contents.debugger;
  if(!api||api.isAttached()||owners.has(contents))throw Error('Page security initialization unavailable');
  const owner={api,healthy:false};
  const detached=()=>{owners.delete(contents);owner.healthy=false;if(!contents.isDestroyed())onFailure();};
  owner.detached=detached;
  api.on('detach',detached);
  try{
    api.attach('1.3');
    await deadline(api.sendCommand('Page.enable',{}));
    const registration=await deadline(api.sendCommand('Page.addScriptToEvaluateOnNewDocument',{source}));
    if(typeof registration?.identifier!=='string'||!registration.identifier||!api.isAttached())throw Error('Page security initialization failed');
    owner.healthy=true;owners.set(contents,owner);
  }catch{
    api.removeListener('detach',detached);
    if(api.isAttached())api.detach();
    throw Error('Page security initialization failed');
  }
}
function guardedScreenshot(contents,parameters){
  const owner=owners.get(contents);
  if(!owner)return null;
  if(!owner.healthy||owner.api!==contents.debugger||!owner.api.isAttached())throw Error('Page security connection unavailable');
  // Only the fixed screenshot command is shared. There is no general command dispatcher.
  return owner.api.sendCommand('Page.captureScreenshot',parameters);
}
function disposePageClipboardGuard(contents){
  const owner=owners.get(contents);if(!owner)return;
  owners.delete(contents);owner.healthy=false;owner.api.removeListener('detach',owner.detached);
  if(owner.api.isAttached())owner.api.detach();
}
async function guardedVisualStructure(contents){
  const owner=owners.get(contents);
  if(!owner?.healthy||!owner.api.isAttached()||contents.isDestroyed())throw Error('Managed visual export refused');
  // Native DOM data detects closed/declarative roots that isolated DOM queries
  // cannot see. It is consumed privately and never logged or returned to agents.
  const result=await deadline(owner.api.sendCommand('DOM.getDocument',{depth:-1,pierce:true}));
  if(owners.get(contents)!==owner||!owner.healthy||!owner.api.isAttached())throw Error('Managed visual export refused');
  const queue=[result?.root];let nodes=0,characters=0;
  while(queue.length){
    const node=queue.pop();if(!node||++nodes>20000)throw Error('Managed visual export refused');
    for(const text of [node.nodeName,node.nodeValue,...(node.attributes||[])]){if(typeof text!=='string'||(characters+=text.length)>1024*1024)throw Error('Managed visual export refused');}
    const shadows=node.shadowRoots||[],children=node.children||[];
    if(!Array.isArray(shadows)||!Array.isArray(children)||nodes+queue.length+shadows.length+children.length>20000)throw Error('Managed visual export refused');
    for(const root of shadows){if(root.shadowRootType==='closed')throw Error('Managed visual export refused');queue.push(root);}
    if(node.contentDocument)throw Error('Managed visual export refused');
    queue.push(...children);
  }
  return {safe:true,nodes};
}
module.exports={attachPageClipboardGuard,guardedScreenshot,guardedVisualStructure,disposePageClipboardGuard};