From d5a2609f759374e3bd3133621ad83eee084f0433 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Wed, 20 Dec 2017 11:27:42 -0800
Subject: [PATCH] peer: add reverse dns lookup.

---
 lib/net/peer.js | 20 ++++++++++++++++++++
 lib/node/rpc.js |  8 ++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/lib/net/peer.js b/lib/net/peer.js
index 53ca78ca..97d4aed1 100644
--- a/lib/net/peer.js
+++ b/lib/net/peer.js
@@ -12,6 +12,7 @@ const EventEmitter = require('events');
 const {Lock} = require('bmutex');
 const {format} = require('util');
 const tcp = require('btcp');
+const dns = require('bdns');
 const Logger = require('blgr');
 const {RollingFilter} = require('bfilter');
 const util = require('../utils/util');
@@ -87,6 +88,7 @@ class Peer extends EventEmitter {
     this.loader = false;
     this.address = new NetAddress();
     this.local = new NetAddress();
+    this.name = null;
     this.connected = false;
     this.destroyed = false;
     this.ack = false;
@@ -375,6 +377,24 @@ class Peer extends EventEmitter {
     return socket;
   }
 
+  /**
+   * Do a reverse dns lookup on peer's addr.
+   * @returns {Promise}
+   */
+
+  async getName() {
+    try {
+      if (!this.name) {
+        const {host, port} = this.address;
+        const {hostname} = await dns.lookupService(host, port);
+        this.name = hostname;
+      }
+    } catch (e) {
+      ;
+    }
+    return this.name;
+  }
+
   /**
    * Open and perform initial handshake (without rejection).
    * @method
diff --git a/lib/node/rpc.js b/lib/node/rpc.js
index b84d0a22..57a08422 100644
--- a/lib/node/rpc.js
+++ b/lib/node/rpc.js
@@ -456,23 +456,23 @@ class RPC extends RPCBase {
     const peers = [];
 
     for (let peer = this.pool.peers.head(); peer; peer = peer.next) {
-      let offset = this.network.time.known.get(peer.hostname());
+      const offset = this.network.time.known.get(peer.hostname()) || 0;
       const hashes = [];
 
-      if (offset == null)
-        offset = 0;
-
       for (const hash in peer.blockMap.keys()) {
         const str = util.revHex(hash);
         hashes.push(str);
       }
 
+      peer.getName();
+
       peers.push({
         id: peer.id,
         addr: peer.hostname(),
         addrlocal: !peer.local.isNull()
           ? peer.local.hostname
           : undefined,
+        name: peer.name || undefined,
         services: hex32(peer.services),
         relaytxes: !peer.noRelay,
         lastsend: peer.lastSend / 1000 | 0,