chore: sort relay addresses to listen for public first

package.json

@@ -61,7 +61,7 @@
     "it-protocol-buffers": "^0.2.0",
     "libp2p-crypto": "^0.18.0",
     "libp2p-interfaces": "^0.5.1",
-    "libp2p-utils": "^0.2.0",
+    "libp2p-utils": "^0.2.1",
     "mafmt": "^8.0.0",
     "merge-options": "^2.0.0",
     "moving-average": "^1.0.0",

src/circuit/auto-relay.js

@@ -4,6 +4,8 @@ const debug = require('debug')
 const log = debug('libp2p:auto-relay')
 log.error = debug('libp2p:auto-relay:error')
 
+const isPrivate = require('libp2p-utils/src/multiaddr/is-private')
+
 const uint8ArrayFromString = require('uint8arrays/from-string')
 const uint8ArrayToString = require('uint8arrays/to-string')
 const multiaddr = require('multiaddr')
@@ -131,9 +133,13 @@ class AutoRelay {
     let listenAddr, remoteMultiaddr, remoteAddrs
 
     try {
+      // Get peer known addresses and sort them per public addresses first
       remoteAddrs = this._peerStore.addressBook.get(connection.remotePeer)
-      // TODO: HOP Relays should avoid advertising private addresses!
+      // TODO: This sort should be customizable in the config (dialer addr sort)
+      remoteAddrs.sort(multiaddrsCompareFunction)
+
       remoteMultiaddr = remoteAddrs.find(a => a.isCertified).multiaddr // Get first announced address certified
+      // TODO: HOP Relays should avoid advertising private addresses!
     } catch (_) {
       log.error(`${id} does not have announced certified multiaddrs`)
 
@@ -267,4 +273,24 @@ class AutoRelay {
   }
 }
 
+/**
+ * Compare function for array.sort().
+ * This sort aims to move the private adresses to the end of the array.
+ *
+ * @param {Address} a
+ * @param {Address} b
+ * @returns {number}
+ */
+function multiaddrsCompareFunction (a, b) {
+  const isAPrivate = isPrivate(a.multiaddr)
+  const isBPrivate = isPrivate(b.multiaddr)
+
+  if (isAPrivate && !isBPrivate) {
+    return 1
+  } else if (!isAPrivate && isBPrivate) {
+    return -1
+  }
+  return 0
+}
+
 module.exports = AutoRelay