Communication with other nodes

Author: akondas

README.md

@@ -12,7 +12,7 @@ Clean code approach to blockchain technology. Learn blockchain by reading source
  - [x] Genesis block
  - [x] Storing and validate Blockchain
  - [x] Proof of Work with difficulty (missing consensus on the difficulty)
- - [ ] Communicating with other nodes & controlling the node (based on ReactPHP)
+ - [X] Communicating with other nodes & controlling the node (based on ReactPHP)
  - [ ] Going serverless with AWS Lambda (experiment)
  - [ ] Start working on KondasCoin [akondas/coin](https://github.com/akondas/coin) :rocket: (Transactions, Wallet, Transaction relaying, Maybe some UI)
 
@@ -40,21 +40,36 @@ bin/node --p2p-port=2020
 
 To control node you can use simple (pseudo) REST API:
 
+**[GET] /blocks**
+Response (list of all blocks):
 ```
-GET /blocks
-
-Return list of blocks:
 [{"index":0,"hash":"8b31c9ec8c2df21968aca3edd2bda8fc77ed45b0b3bc8bc39fa27d5c795bc829","previousHash":"","createdAt":"2018-02-23 23:59:59","data":"PHP is awesome!","difficulty":0,"nonce":0}]
 ```
 
+**[POST] /mine**
+Request (raw):
+```
+Data to mine (any string).
+```
+Response (mined block):
 ```
-POST /mine 
-"post content is data to mine"
-
-Return mined block:
 {"index":1,"hash":"a6eba6325a677802536337dc83268e524ffae5dc7db0950c98ff970846118f80","previousHash":"8b31c9ec8c2df21968aca3edd2bda8fc77ed45b0b3bc8bc39fa27d5c795bc829","createdAt":"2018-03-13 22:37:07","data":"Something goof","difficulty":0,"nonce":0}
 ```
 
+**[GET] /peers**
+Response (list of all connected peers):
+```
+[{"host":"127.0.0.1","port":3131}]
+```
+
+**[POST] /peers/add**
+Request (json with peer):
+```
+{"host":"127.0.0.1", "port":"3131"}
+```
+Response: 204 (empty)
+
+
 ## Tests
 
 To run test suite:

bin/node

@@ -25,6 +25,7 @@ $node = new Node(
     new Miner(new Blockchain(Block::genesis()), new HashDifficulty\ZeroPrefix()),
     $p2pServer
 );
+$p2pServer->attachNode($node);
 
 (new SocketServer($p2pPort, $loop))->on('connection', $p2pServer);
 (new HttpServer(new WebServer($node)))->listen(new SocketServer($httpPort, $loop));

src/Block.php

@@ -103,6 +103,11 @@ public function hash(): string
         return $this->hash;
     }
 
+    public function previousHash(): string
+    {
+        return $this->previousHash;
+    }
+
     public function difficulty(): int
     {
         return $this->difficulty;

src/Blockchain.php

@@ -60,4 +60,9 @@ public function blocks(): array
     {
         return $this->blocks;
     }
+
+    public function size(): int
+    {
+        return count($this->blocks);
+    }
 }

src/Miner.php

@@ -51,4 +51,13 @@ public function blockchain(): Blockchain
     {
         return $this->blockchain;
     }
+
+    public function replaceBlockchain(Blockchain $blockchain): void
+    {
+        if (! $blockchain->isValid()) {
+            return;
+        }
+
+        $this->blockchain = $blockchain;
+    }
 }

src/Node.php

@@ -38,7 +38,7 @@ public function blocks(): array
     public function mineBlock(string $data): Block
     {
         $block = $this->miner->mineBlock($data);
-        $this->p2pServer->broadcast(new Message(Message::TYPE_LAST_BLOCK, json_encode($block)));
+        $this->p2pServer->broadcast(new Message(Message::BLOCKCHAIN, serialize($this->blockchain()->withLastBlockOnly())));
 
         return $block;
     }
@@ -55,4 +55,14 @@ public function connect(string $host, int $port): void
     {
         $this->p2pServer->connect($host, $port);
     }
+
+    public function blockchain(): Blockchain
+    {
+        return $this->miner->blockchain();
+    }
+
+    public function replaceBlockchain(Blockchain $blockchain): void
+    {
+        $this->miner->replaceBlockchain($blockchain);
+    }
 }

src/Node/Message.php

@@ -6,19 +6,23 @@
 
 final class Message
 {
-    public const TYPE_LAST_BLOCK = 'last-block';
+    public const REQUEST_LATEST = 'request-latest';
+
+    public const REQUEST_ALL = 'request-all';
+
+    public const BLOCKCHAIN = 'blockchain';
 
     /**
      * @var string
      */
     private $type;
 
     /**
-     * @var string
+     * @var ?string
      */
     private $data;
 
-    public function __construct(string $type, string $data)
+    public function __construct(string $type, ?string $data = null)
     {
         $this->type = $type;
         $this->data = $data;
@@ -29,7 +33,7 @@ public function type(): string
         return $this->type;
     }
 
-    public function data(): string
+    public function data(): ?string
     {
         return $this->data;
     }

src/Node/P2pServer.php

@@ -4,6 +4,7 @@
 
 namespace Blockchain\Node;
 
+use Blockchain\Blockchain;
 use Blockchain\Node;
 use React\Socket\ConnectionInterface;
 use React\Socket\Connector;
@@ -33,12 +34,40 @@ public function __construct(Connector $connector)
 
     public function __invoke(ConnectionInterface $connection): void
     {
-        $peer = new Peer($connection);
-        if ($this->contains($peer)) {
+        if (isset($this->peers[$connection->getRemoteAddress()])) {
             return;
         }
 
-        //$connection->on('data')
+        $connection->on('data', function (string $data) use ($connection): void {
+            $message = unserialize($data, [Message::class]);
+            switch ($message->type()) {
+                case Message::REQUEST_LATEST:
+                    $connection->write(serialize(new Message(
+                        Message::BLOCKCHAIN,
+                        serialize($this->node->blockchain()->withLastBlockOnly())
+                    )));
+
+                    break;
+                case Message::REQUEST_ALL:
+                    $connection->write(serialize(new Message(
+                        Message::BLOCKCHAIN,
+                        serialize($this->node->blockchain())
+                    )));
+
+                    break;
+                case Message::BLOCKCHAIN:
+                    $this->handleBlockchain(unserialize($message->data(), [Blockchain::class]), $connection);
+
+                    break;
+            }
+        });
+
+        $connection->on('close', function () use ($connection): void {
+            unset($this->peers[$connection->getRemoteAddress()]);
+        });
+
+        $this->peers[$connection->getRemoteAddress()] = new Peer($connection);
+        $this->peers[$connection->getRemoteAddress()]->send(new Message(Message::REQUEST_LATEST));
     }
 
     public function attachNode(Node $node): void
@@ -59,24 +88,35 @@ public function connect(string $host, int $port): void
 
     public function broadcast(Message $message): void
     {
+        foreach ($this->peers as $peer) {
+            $peer->send($message);
+        }
     }
 
     /**
      * @return Peer[]
      */
     public function peers(): array
     {
-        return $this->peers;
+        return array_values($this->peers);
     }
 
-    private function contains(Peer $peer): bool
+    private function handleBlockchain(Blockchain $blockchain, ConnectionInterface $connection): void
     {
-        foreach ($this->peers as $p) {
-            if ($p->isEqual($peer)) {
-                return true;
-            }
+        if ($blockchain->size() === 0) {
+            return;
         }
 
-        return false;
+        if ($blockchain->last()->index() <= $this->node->blockchain()->last()->index()) {
+            return; // received blockchain is no longer than current blockchain, skip
+        }
+
+        if ($blockchain->last()->previousHash() === $this->node->blockchain()->last()->hash()) {
+            $this->node->blockchain()->add($blockchain->last());
+        } elseif ($blockchain->size() === 1) {
+            $connection->write(serialize(new Message(Message::REQUEST_ALL)));
+        } else {
+            $this->node->replaceBlockchain($blockchain);
+        }
     }
 }

src/Node/Peer.php

@@ -34,11 +34,6 @@ public function port(): int
         return parse_url($this->connection->getRemoteAddress(), PHP_URL_PORT);
     }
 
-    public function isEqual(self $peer): bool
-    {
-        $this->host() === $peer->host() && $this->port() === $peer->port();
-    }
-
     /**
      * @return mixed[]
      */