safetynet/apps/browser/clipboard-guard.cjs

'use strict';
const {randomUUID}=require('node:crypto');
function createClipboardGuard({getContext,stage,validate,commit,discard,readClipboard,writeClipboard,inspect,audit,onCompleted,timeoutMs=10000}){
  const targetFacts=value=>{if(!value||!['a','button','input','textarea','select','div','span','p','body','unknown'].includes(value.tag))return undefined;const target={tag:value.tag};if(['button','link','textbox','checkbox','radio','combobox','menuitem','option'].includes(value.role))target.role=value.role;if(['x','y'].every(k=>Number.isSafeInteger(value[k])&&value[k]>=0&&value[k]<=100000)) {target.x=value.x;target.y=value.y;}return target;};
  let pending=null;
  const current=c=>{const n=getContext(c.webContents);return n.ready&&n.tabId===c.tabId&&n.activation===c.activation&&n.policy===c.policy&&n.url===c.url&&n.navigationId===c.navigationId&&n.webContents===c.webContents&&n.webContents?.focusedFrame===n.webContents?.mainFrame&&Date.parse(n.policy?.expiresAt)>Date.now();};
  async function run(operation,webContents){
    const c=getContext(webContents),token=randomUUID();let text='',timer,expired=false;
    const denied=async ruleId=>{await audit('clipboard.block',ruleId,{action:operation,sessionId:c.tabId,outcome:'denied'});return{completed:false,ruleId};};
    const work=async()=>{try{
      if(!['copy','cut','paste'].includes(operation)||!current(c))return denied('clipboard-context-denied');
      const limit=Math.min(c.policy.security?.clipboard?.maxTextBytes||0,c.policy.dlp.maxBytes);
      if(!limit)return denied('clipboard-policy-unavailable');
      const snapshot=await stage({operation,token,url:c.url,limit,webContents:c.webContents});
      if(!current(c)||expired)return denied('clipboard-context-changed');
      if(operation==='paste')text=await readClipboard(limit);else text=snapshot.text;
      if(!current(c)||expired)return denied('clipboard-context-changed');
      if(typeof text!=='string'||Buffer.byteLength(text)>limit||text.includes('\0'))return denied('clipboard-size-limit');
      const verdict=await inspect(Buffer.from(text),c.policy,operation);
      if(!current(c)||expired)return denied('clipboard-context-changed');
      if(verdict?.decision!=='allow')return denied(verdict?.ruleId||'clipboard-inspection-failed');
      // Persist authorization before side effects; never audit raw clipboard text.
      await audit(`clipboard.${operation}`,undefined,{action:operation,sessionId:c.tabId,outcome:'authorized'});
      if(!current(c)||expired)return denied('clipboard-context-changed');
      const args={operation,token,url:c.url,text,limit,webContents:c.webContents};
      if(operation==='cut'){
        const validated=await validate(args);
        if(validated?.completed!==true||!current(c)||expired)return denied('clipboard-target-changed');
        await writeClipboard(text);
        if(!current(c)||expired)return denied('clipboard-context-changed');
      }
      const result=await commit(args);
      if(result?.completed!==true||!current(c)||expired)return denied('clipboard-target-changed');
      if(operation==='copy'){await writeClipboard(text);if(!current(c)||expired)return denied('clipboard-context-changed');}
      if(onCompleted && /^[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(c.tabId||'')) {
        await onCompleted({action:operation,sessionId:c.tabId,pageUrl:c.url,outcome:'completed',sensitiveField:false,...(targetFacts(snapshot.target)?{target:targetFacts(snapshot.target)}:{}),bytes:Buffer.byteLength(text)});
        if(!current(c)||expired)return denied('clipboard-context-changed');
      }
      return {completed:true};
    }finally{try{await discard?.({token,webContents:c.webContents});}catch{}}};
    try{return await Promise.race([work(),new Promise(resolve=>{timer=setTimeout(()=>{expired=true;Promise.resolve(discard?.({token,webContents:c.webContents})).catch(()=>{});denied('clipboard-timeout').then(resolve,()=>resolve({completed:false,ruleId:'clipboard-timeout'}));},timeoutMs);})]);}
    catch{return denied('clipboard-inspection-failed');}
    finally{clearTimeout(timer);text='';}
  }
  function perform(operation,webContents){if(pending)return Promise.resolve({completed:false,ruleId:'clipboard-busy'});const task=run(operation,webContents);pending=task;task.finally(()=>{if(pending===task)pending=null;}).catch(()=>{});return task;}
  return {perform,isPending:()=>!!pending};
}
module.exports={createClipboardGuard};