From 40d40c55aa576b8e782a9a86a271c2b34fdf8a8a Mon Sep 17 00:00:00 2001
From: Kagami Hiiragi <kagami@genshiken.org>
Date: Thu, 5 Feb 2015 22:55:36 +0300
Subject: [PATCH] TCP bootstrap

---
 lib/net/tcp.js          | 49 ++++++++++++++++++++++++++++++++++++-----
 tests/functional.js     | 31 ++++++++++++++++++++++++++
 tests/run-test-nodes.js |  2 +-
 3 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/lib/net/tcp.js b/lib/net/tcp.js
index d60b807..eea2e51 100644
--- a/lib/net/tcp.js
+++ b/lib/net/tcp.js
@@ -8,6 +8,7 @@
 
 var inherits = require("inherits");
 var net = require("net");
+var dns = require("dns");
 var assert = require("../_util").assert;
 var PPromise = require("../platform").Promise;
 var BaseTransport = require("./base").BaseTransport;
@@ -22,9 +23,8 @@ var sockIdCounter = 0;
 function Transport(opts) {
   Transport.super_.call(this);
   opts = opts || {};
-  if (opts.seeds) {
-    this.seeds = opts.seeds;
-  }
+  this.seeds = opts.seeds || [];
+  this.dnsSeeds = opts.dnsSeeds || [];
   if (opts.client) {
     this._setupClient(opts.client);
   }
@@ -62,9 +62,47 @@ Transport.prototype._setupClient = function(client) {
   });
 };
 
+function resolveDnsSeed(seed) {
+  var host = seed[0];
+  var port = seed[1];
+  var nodes = [];
+  // NOTE(Kagami):
+  // 1) Node's `getaddrinfo` (`dns.lookup`) returns only one address so
+  // we can't use it.
+  // 2) Node's `dig host any` (`dns.resolve`) doesn't return type of the
+  // record! So we resolve twice for A and AAAA.
+  // 3) We ignore any errors here, promise's result is always a list.
+  return new PPromise(function(resolve) {
+    dns.resolve4(host, function(err, nodes4) {
+      if (!err) {
+        nodes4.forEach(function(n) {
+          nodes.push([n, port]);
+        });
+      }
+      dns.resolve6(host, function(err, nodes6) {
+        if (!err) {
+          nodes6.forEach(function(n) {
+            nodes.push([n, port]);
+          });
+        }
+        resolve(nodes);
+      });
+    });
+  });
+}
+
 Transport.prototype.bootstrap = function() {
-  // TODO(Kagami): Think how to set up DNS/IP nodes. Do we need to
-  // hardcode them?
+  var promises = this.dnsSeeds.map(resolveDnsSeed);
+  var hardcodedNodes = this.seeds;
+  // FIXME(Kagami): Filter incorrect/private IP range nodes?
+  // See also: <https://github.com/Bitmessage/PyBitmessage/issues/768>.
+  return PPromise.all(promises).then(function(dnsNodes) {
+    // Add hardcoded nodes to the end of list because DNS nodes should
+    // be more up-to-date.
+    // Flatten array of array of arrays.
+    dnsNodes = Array.prototype.concat.apply([], dnsNodes);
+    return dnsNodes.concat(hardcodedNodes);
+  });
 };
 
 Transport.prototype.connect = function() {
@@ -92,6 +130,7 @@ Transport.prototype.listen = function() {
     var transport = new self.constructor({
       client: sock,
       seeds: this.seeds,
+      dnsSeeds: this.dnsSeeds,
     });
     self.emit("connection", transport);
   });
diff --git a/tests/functional.js b/tests/functional.js
index 1dc6ac0..0de3817 100644
--- a/tests/functional.js
+++ b/tests/functional.js
@@ -1,3 +1,5 @@
+var expect = require("chai").expect;
+
 var bitmessage = require("../lib");
 var structs = bitmessage.structs;
 var message = structs.message;
@@ -18,6 +20,35 @@ if (!process.browser) {
       setTimeout(done, 1000);
     });
 
+    it("should return nothing on bootstrap by default", function() {
+      return tcp.bootstrap().then(function(nodes) {
+        expect(nodes).to.be.empty;
+      });
+    });
+
+    it("should resolve DNS seeds on bootstrap", function() {
+      var tcp2 = new TcpTransport({
+        dnsSeeds: [["bootstrap8444.bitmessage.org", 8444]],
+      });
+      return tcp2.bootstrap().then(function(nodes) {
+        expect(nodes).to.be.not.empty;
+        expect(nodes[0][1]).to.be.equal(8444);
+      });
+    });
+
+    it("should return hardcoded seeds on bootstrap", function() {
+      var tcp3 = new TcpTransport({
+        seeds: [["1.1.1.1", 8080]],
+        dnsSeeds: [["bootstrap8444.bitmessage.org", 8444]],
+      });
+      return tcp3.bootstrap().then(function(nodes) {
+        expect(nodes).to.have.length.at.least(2);
+        expect(nodes[0][1]).to.be.equal(8444);
+        expect(nodes[nodes.length - 1][0]).to.equal("1.1.1.1");
+        expect(nodes[nodes.length - 1][1]).to.equal(8080);
+      });
+    });
+
     it("should allow to interconnect two nodes", function(done) {
       tcp.connect(22333, "127.0.0.1");
       tcp.on("open", function() {
diff --git a/tests/run-test-nodes.js b/tests/run-test-nodes.js
index e246f1f..e602716 100644
--- a/tests/run-test-nodes.js
+++ b/tests/run-test-nodes.js
@@ -30,7 +30,7 @@ module.exports = function() {
       } catch(e) {
         console.log(e.stack);
       }
-      if (err) console.log(err.stack);
+      if (err && err.stack) console.log(err.stack);
       if (doExit) process.exit(1);
     };
   }