From e29e23bf811aacadc58c6268d692d466bef6fb47 Mon Sep 17 00:00:00 2001
From: Thomas Winget <tewinget@gmail.com>
Date: Tue, 14 Nov 2023 23:55:38 -0500
Subject: [PATCH] implement and use "gossip_rc" command

TODO: refactor or remove RCGossiper and revisit RC regen and
when-to-gossip logic.
---
 llarp/link/link_manager.cpp | 27 ++++++++++++++++++++++---
 llarp/link/link_manager.hpp |  2 +-
 llarp/nodedb.cpp            | 40 ++++++++++++++++++++-----------------
 llarp/nodedb.hpp            | 13 ++++++++----
 llarp/router/router.cpp     |  4 +++-
 5 files changed, 59 insertions(+), 27 deletions(-)

diff --git a/llarp/link/link_manager.cpp b/llarp/link/link_manager.cpp
index 294a84b9a..4563a0e41 100644
--- a/llarp/link/link_manager.cpp
+++ b/llarp/link/link_manager.cpp
@@ -150,6 +150,11 @@ namespace llarp
           [this, &rid, msg = std::move(m)]() mutable { handle_path_control(std::move(msg), rid); });
     });
 
+    s->register_command("gossip_rc"s, [this, rid](oxen::quic::message m) {
+      _router.loop()->call(
+          [this, msg = std::move(m)]() mutable { handle_gossip_rc(std::move(msg)); });
+    });
+
     for (auto& method : direct_requests)
     {
       s->register_command(
@@ -386,10 +391,19 @@ namespace llarp
   }
 
   void
-  LinkManager::gossip_rc(const RemoteRC& rc)
+  LinkManager::gossip_rc(const RouterID& rc_rid, std::string serialized_rc)
   {
     for (auto& [rid, conn] : ep.conns)
-      send_control_message(rid, "gossip_rc", std::string{rc.view()}, nullptr);
+    {
+      // don't send back to the owner...
+      if (rid == rc_rid)
+        continue;
+      // don't gossip RCs to clients
+      if (not conn->remote_is_relay)
+        continue;
+
+      send_control_message(rid, "gossip_rc", serialized_rc, nullptr);
+    }
   }
 
   void
@@ -398,11 +412,18 @@ namespace llarp
     try
     {
       RemoteRC rc{m.body()};
+
+      if (node_db->put_rc_if_newer(rc))
+      {
+        log::info(link_cat, "Received updated RC, forwarding to relay peers.");
+        gossip_rc(rc.router_id(), m.body_str());
+      }
+      else
+        log::debug(link_cat, "Received known or old RC, not storing or forwarding.");
     }
     catch (const std::exception& e)
     {
       log::info(link_cat, "Recieved invalid RC, dropping on the floor.");
-      return;
     }
   }
 
diff --git a/llarp/link/link_manager.hpp b/llarp/link/link_manager.hpp
index 6a456b064..c2be7dcd6 100644
--- a/llarp/link/link_manager.hpp
+++ b/llarp/link/link_manager.hpp
@@ -221,7 +221,7 @@ namespace llarp
     }
 
     void
-    gossip_rc(const RemoteRC& rc);
+    gossip_rc(const RouterID& rc_rid, std::string serialized_rc);
 
     void
     handle_gossip_rc(oxen::quic::message m);
diff --git a/llarp/nodedb.cpp b/llarp/nodedb.cpp
index 5377b19c2..ffc6d268c 100644
--- a/llarp/nodedb.cpp
+++ b/llarp/nodedb.cpp
@@ -99,6 +99,14 @@ namespace llarp
     return m_Root / skiplistDir / fname;
   }
 
+  bool
+  NodeDB::want_rc(const RouterID& rid) const
+  {
+    if (not router.is_service_node())
+      return true;
+    return registered_routers.count(rid);
+  }
+
   void
   NodeDB::set_bootstrap_routers(const std::set<RemoteRC>& rcs)
   {
@@ -284,14 +292,15 @@ namespace llarp
     });
   }
 
-  void
+  bool
   NodeDB::put_rc(RemoteRC rc)
   {
-    router.loop()->call([this, rc]() {
-      const auto& rid = rc.router_id();
-      entries.erase(rid);
-      entries.emplace(rid, rc);
-    });
+    const auto& rid = rc.router_id();
+    if (not want_rc(rid))
+      return false;
+    entries.erase(rid);
+    entries.emplace(rid, rc);
+    return true;
   }
 
   size_t
@@ -300,20 +309,15 @@ namespace llarp
     return router.loop()->call_get([this]() { return entries.size(); });
   }
 
-  void
+  bool
   NodeDB::put_rc_if_newer(RemoteRC rc)
   {
-    router.loop()->call([this, rc]() {
-      auto itr = entries.find(rc.router_id());
-      if (itr == entries.end() or itr->second.rc.other_is_newer(rc))
-      {
-        // delete if existing
-        if (itr != entries.end())
-          entries.erase(itr);
-        // add new entry
-        entries.emplace(rc.router_id(), rc);
-      }
-    });
+    auto itr = entries.find(rc.router_id());
+    if (itr == entries.end() or itr->second.rc.other_is_newer(rc))
+    {
+      return put_rc(std::move(rc));
+    }
+    return false;
   }
 
   void
diff --git a/llarp/nodedb.hpp b/llarp/nodedb.hpp
index 7d7c088eb..76a635316 100644
--- a/llarp/nodedb.hpp
+++ b/llarp/nodedb.hpp
@@ -64,6 +64,9 @@ namespace llarp
     // only ever use to specific edges as path first-hops
     std::unordered_set<RouterID> pinned_edges;
 
+    bool
+    want_rc(const RouterID& rid) const;
+
    public:
     void
     set_bootstrap_routers(const std::set<RemoteRC>& rcs);
@@ -243,12 +246,14 @@ namespace llarp
     void
     remove_stale_rcs(std::unordered_set<RouterID> keep, llarp_time_t cutoff);
 
-    /// put this rc into the cache if it is not there or newer than the one there already
-    void
+    /// if we consider it valid (want_rc),
+    /// put this rc into the cache if it is not there or is newer than the one there already
+    /// returns true if the rc was inserted
+    bool
     put_rc_if_newer(RemoteRC rc);
 
-    /// unconditional put of rc into cache
-    void
+    /// put (or replace) the RC if we consider it valid (want_rc).  returns true if put.
+    bool
     put_rc(RemoteRC rc);
   };
 }  // namespace llarp
diff --git a/llarp/router/router.cpp b/llarp/router/router.cpp
index 4b26ff144..9ef2972cb 100644
--- a/llarp/router/router.cpp
+++ b/llarp/router/router.cpp
@@ -236,7 +236,9 @@ namespace llarp
     /// wait for random uptime
     if (std::chrono::milliseconds{Uptime()} < _randomStartDelay)
       return;
-    _rcGossiper.GossipRC(rc);
+    auto view = rc.view();
+    _link_manager.gossip_rc(
+        pubkey(), std::string{reinterpret_cast<const char*>(view.data()), view.size()});
   }
 
   std::optional<RouterID>