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Keys stuff w/ indexeddb

From: Martin Thomson <martin.thomson@gmail.com>
Date: Fri, 31 Oct 2014 08:16:48 -0700
Message-ID: <CABkgnnV89sxveHQL0uSNQraSyaHi2PYY62xw33HWroahbXQ0Ew@mail.gmail.com>
To: "public-webrtc@w3.org" <public-webrtc@w3.org>
So a recap on the keys stuff:

RTCKeys.generate(algorithm).then(key => {
  pc = new RTCPeerConnection({ dtlsKeys: [ key ] });
});

The key that you get can be stored in indexeddb, and I can't pretend
that I like the API: it's awful.

Most of this awfulness is because indexeddb is awful.  It's so awful
that I can't describe it.  I've done this all inline, but obviously
you can build a good wrapper that doesn't suck.  Everyone does.

////// This is just setup
let dbRequest = indexedDB.open("keys");
let dbResolve;
let dbPromise = new Promise(r => dbResolve = r);

request.onupgradeneeded = e => {
  let store = dbRequest.result.createObjectStore("peerKeys", {keyPath:
"peerIdentity"});
  dbResolve(dbRequest.result);
};
request.onsuccess = e => {
  dbResolve(dbRequest.result);
};

////// this is to retrieve a key
let userid = "john@example.com";
let retrievePromise = dbPromise.then(db => {
  return new Promise((resolve, reject) => {
    let tx = db.transaction("peerKeys", "readonly");
    let store = tx.objectStore("peerKeys");
    let request = store.get(userid);
    request.onsuccess = e => {
      if (e.target.result) {
        resolve(e.target.result.key);
      } else {
        reject(new Error("no stored key for " + userid));
      }
    };
  });
})

/////// if the storage fails, then generate
.catch(e => {
  return RTCKeys.generate(algorithm).then(key => {
    // store the key for next time...
    return dbPromise.then(db => {
      let tx = db.transaction("peerKeys", "readwrite");
      let store = tx.objectStore("peerKeys");
      return new Promise(resolve => {
        let request = store.put({ peerIdentity: userid, key: key });
        request.onsuccess = e => resolve(key);
      });
    });
  });
})

////// finally use it
.then(key => {
  pc = new RTCPeerConnection({ dtlsKeys: [ key ] });
});

Promises are awesome.
Received on Friday, 31 October 2014 15:17:16 UTC

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