Allow signing mutable data asynchronously

README.md

@@ -238,7 +238,7 @@ For mutable content, the hash will be the hash of the public key, `opts.k`.
 These options are available:
 
 * `opts.k` - ed25519 public key buffer (32 bytes) (REQUIRED)
-* `opts.sign(buf)` - function to generate an ed25519 signature buffer (64 bytes) corresponding to the `opts.k` public key (REQUIRED)
+* `opts.sign(buf[, cb])` - function to generate an ed25519 signature buffer (64 bytes) corresponding to the `opts.k` public key (REQUIRED)
 * `opts.seq` - optional sequence (integer), must monotonically increase (REQUIRED)
 * `opts.cas` - optional previous sequence for compare-and-swap
 * `opts.salt` - optional salt buffer to include (<= 64 bytes) when calculating
@@ -263,8 +263,8 @@ const opts = {
   k: keypair.pk,
   seq: 0,
   v: value,
-  sign: function (buf) {
-    return ed.sign(buf, keypair.sk)
+  sign: function (buf, cb) {
+    cb(ed.sign(buf, keypair.sk))
   }
 }
 

client.js

@@ -309,18 +309,33 @@ class DHT extends EventEmitter {
       if (opts.salt) message.a.salt = opts.salt
       message.a.k = opts.k
       message.a.seq = opts.seq
-      if (typeof opts.sign === 'function') message.a.sig = opts.sign(encodeSigData(message.a))
-      else if (Buffer.isBuffer(opts.sig)) message.a.sig = opts.sig
+      if (typeof opts.sign === 'function') {
+        if (opts.sign.length === 1) {
+          message.a.sig = opts.sign(encodeSigData(message.a))
+          this._putSigned(table, key, message, cb)
+        } else {
+          opts.sign(encodeSigData(message.a), (sig) => {
+            message.a.sig = sig
+            this._putSigned(table, key, message, cb)
+          })
+        }
+      } else if (Buffer.isBuffer(opts.sig)) {
+        message.a.sig = opts.sig
+        this._putSigned(table, key, message, cb)
+      }
     } else {
       this._values.set(key.toString('hex'), message.a)
+      this._putSigned(table, key, message, cb)
     }
 
+    return key
+  }
+
+  _putSigned (table, key, message, cb) {
     this._rpc.queryAll(table.closest(key), message, null, (err, n) => {
       if (err) return cb(err, key, n)
       cb(null, key, n)
     })
-
-    return key
   }
 
   _preput (key, opts, cb) {

test/dht_store_mutable.js

@@ -612,3 +612,47 @@ test('valid sequence', t => {
     }
   })
 })
+
+test('asynchronous signing', t => {
+  t.plan(4)
+
+  const keypair = ed.keygen()
+
+  const dht = new DHT({ bootstrap: false, verify: ed.verify })
+  t.once('end', () => {
+    dht.destroy()
+  })
+  common.failOnWarningOrError(t, dht)
+
+  dht.listen(() => {
+    dht.addNode({ host: '127.0.0.1', port: dht.address().port })
+    dht.once('node', ready)
+  })
+
+  function ready () {
+    const value = common.fill(500, 'abc')
+    const opts = {
+      k: keypair.pk,
+      sign: (data, cb) => cb(common.sign(keypair)(data)),
+      seq: 0,
+      v: value
+    }
+
+    const expectedHash = crypto.createHash('sha1').update(opts.k).digest()
+
+    dht.put(opts, (_, hash) => {
+      t.equal(
+        hash.toString('hex'),
+        expectedHash.toString('hex'),
+        'hash of the public key'
+      )
+      dht.get(hash, (err, res) => {
+        t.ifError(err)
+        t.equal(res.v.toString('utf8'), opts.v.toString('utf8'),
+          'got back what we put in'
+        )
+        t.equal(res.seq, 0)
+      })
+    })
+  }
+})