From d860dc42392d81a7b09e27f631781f81c99b4fb1 Mon Sep 17 00:00:00 2001
From: Andrei Maiboroda <andrei@ethereum.org>
Date: Wed, 26 Feb 2020 18:02:04 +0100
Subject: [PATCH] Preparation for updating fork-id in ENR when it changes in
 BlockChain

---
 libethereum/BlockChain.h |  3 +++
 libp2p/Host.h            |  7 +++++++
 libp2p/NodeTable.cpp     |  1 +
 libp2p/NodeTable.h       | 19 +++++++++++++++++++
 libwebthree/WebThree.cpp |  9 +++++++++
 libwebthree/WebThree.h   |  4 ++++
 6 files changed, 43 insertions(+)

diff --git a/libethereum/BlockChain.h b/libethereum/BlockChain.h
index cd60f4e9ab4..5def0308ed5 100644
--- a/libethereum/BlockChain.h
+++ b/libethereum/BlockChain.h
@@ -311,6 +311,9 @@ class BlockChain
     /// Change the chain start block.
     void setChainStartBlockNumber(unsigned _number);
 
+    FixedHash<4> forkHash() const { return {}; }
+    unsigned nextForkBlockNumber() const { return 0; }
+
 private:
     static h256 chunkId(unsigned _level, unsigned _index) { return h256(_index * 0xff + _level); }
 
diff --git a/libp2p/Host.h b/libp2p/Host.h
index cf0cc2468a5..8d2f6028671 100644
--- a/libp2p/Host.h
+++ b/libp2p/Host.h
@@ -257,6 +257,13 @@ class Host: public Worker
         return m_nodeTable ? m_nodeTable->hostENR() : m_restoredENR;
     }
 
+    void updateForkID(FixedHash<4> const& _forkHash, uint64_t _forkNext)
+    {
+        Guard l(x_nodeTable);
+        if (m_nodeTable)
+            m_nodeTable->updateENRForkID(_forkHash, _forkNext);
+    }
+
     /// Apply function to each session
     void forEachPeer(
         std::string const& _capabilityName, std::function<bool(NodeID const&)> _f) const;
diff --git a/libp2p/NodeTable.cpp b/libp2p/NodeTable.cpp
index 8ab37bfe67f..c72100cc230 100644
--- a/libp2p/NodeTable.cpp
+++ b/libp2p/NodeTable.cpp
@@ -560,6 +560,7 @@ shared_ptr<NodeEntry> NodeTable::handlePong(
                 newUdpEndpoint.address(), newUdpEndpoint.port(), m_hostNodeEndpoint.tcpPort()};
             {
                 Guard l(m_hostENRMutex);
+                // TODO include m_hostForkHash and m_hostForkNext in ENR
                 m_hostENR =
                     IdentitySchemeV4::updateENR(m_hostENR, m_secret, m_hostNodeEndpoint.address(),
                         m_hostNodeEndpoint.tcpPort(), m_hostNodeEndpoint.udpPort());
diff --git a/libp2p/NodeTable.h b/libp2p/NodeTable.h
index 2a9bc80d0db..982c81a6813 100644
--- a/libp2p/NodeTable.h
+++ b/libp2p/NodeTable.h
@@ -187,6 +187,23 @@ class NodeTable : UDPSocketEvents
 
     void cancelTimer(std::shared_ptr<ba::steady_timer> _timer);
 
+    void updateENRForkID(FixedHash<4> const& _forkHash, uint64_t _forkNext)
+    {
+        if (_forkHash != m_hostForkHash && _forkNext != m_hostForkNext)
+        {
+            m_hostForkHash = _forkHash;
+            m_hostForkNext = _forkNext;
+
+            {
+                Guard l(m_hostENRMutex);
+                // TODO include forkHash and forkNext in ENR
+                m_hostENR = IdentitySchemeV4::updateENR(m_hostENR, m_secret, m_hostNodeEndpoint.address(),
+                                                        m_hostNodeEndpoint.tcpPort(), m_hostNodeEndpoint.udpPort());
+            }
+            clog(VerbosityInfo, "net") << "ENR updated: " << m_hostENR;
+        }
+    }
+
     // protected only for derived classes in tests
 protected:
     /**
@@ -339,6 +356,8 @@ class NodeTable : UDPSocketEvents
     bi::address const m_hostStaticIP;
     // Dynamically updated host endpoint
     NodeIPEndpoint m_hostNodeEndpoint;
+    FixedHash<4> m_hostForkHash;
+    uint64_t m_hostForkNext = 0;
     ENR m_hostENR;
     mutable Mutex m_hostENRMutex;
     Secret m_secret;												///< This nodes secret key.
diff --git a/libwebthree/WebThree.cpp b/libwebthree/WebThree.cpp
index 8e5bdda513e..4ec172b7fef 100644
--- a/libwebthree/WebThree.cpp
+++ b/libwebthree/WebThree.cpp
@@ -34,6 +34,9 @@ WebThreeDirect::WebThreeDirect(std::string const& _clientVersion,
         m_ethereum.reset(new eth::Client(_params, (int)_params.networkID, m_net,
             shared_ptr<GasPricer>(), _dbPath, _snapshotPath, _we));
 
+    m_chainChangedHandler =
+        m_ethereum->setOnChainChanged([this](h256s const&, h256s const&) { onChainChanged(); });
+
     m_ethereum->startWorking();
     const auto* buildinfo = aleth_get_buildinfo();
     m_ethereum->setExtraData(rlpList(0, string{buildinfo->project_version}.substr(0, 5) + "++" +
@@ -105,3 +108,9 @@ void WebThreeDirect::addPeer(NodeSpec const& _s, PeerType _t)
     m_net.addPeer(_s, _t);
 }
 
+void WebThreeDirect::onChainChanged()
+{
+    const auto forkHash = m_ethereum->blockChain().forkHash();
+    const auto forkNext = m_ethereum->blockChain().nextForkBlockNumber();
+    m_net.updateForkID(forkHash, forkNext);
+}
diff --git a/libwebthree/WebThree.h b/libwebthree/WebThree.h
index 92d02dca420..350b08c2be7 100644
--- a/libwebthree/WebThree.h
+++ b/libwebthree/WebThree.h
@@ -170,11 +170,15 @@ class WebThreeDirect: public NetworkFace
     bool isNetworkStarted() const override { return m_net.isStarted(); }
 
 private:
+    void onChainChanged();
+
     std::string m_clientVersion;                    ///< Our end-application client's name/version.
 
     std::unique_ptr<eth::Client> m_ethereum;        ///< Client for Ethereum ("eth") protocol.
 
     p2p::Host m_net;                                ///< Should run in background and send us events when blocks found and allow us to send blocks as required.
+
+    eth::Handler<h256s const&, h256s const&> m_chainChangedHandler;
 };