From eedf7ca599b799b11f4997f327f6e081430e16ec Mon Sep 17 00:00:00 2001
From: Stephen Shelton <steve@brewcraft.org>
Date: Mon, 20 Jul 2020 13:48:57 -0600
Subject: [PATCH] Add implementation of get_peer_stats API

---
 llarp/peerstats/peer_db.cpp    | 16 ++++++++++++++++
 llarp/peerstats/peer_db.hpp    |  8 ++++++++
 llarp/peerstats/types.cpp      | 20 +++++++++++++++++++-
 llarp/peerstats/types.hpp      |  5 ++++-
 llarp/rpc/lokid_rpc_client.cpp | 30 +++++++++++++++++++++++++++++-
 5 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/llarp/peerstats/peer_db.cpp b/llarp/peerstats/peer_db.cpp
index 045839d43..9d4fe50d2 100644
--- a/llarp/peerstats/peer_db.cpp
+++ b/llarp/peerstats/peer_db.cpp
@@ -140,6 +140,22 @@ namespace llarp
       return itr->second;
   }
 
+  std::vector<PeerStats>
+  PeerDb::listAllPeerStats() const
+  {
+    std::lock_guard guard(m_statsLock);
+
+    std::vector<PeerStats> statsList;
+    statsList.reserve(m_peerStats.size());
+
+    for (const auto& [routerId, stats] : m_peerStats)
+    {
+      statsList.push_back(stats);
+    }
+
+    return statsList;
+  }
+
   /// Assume we receive an RC at some point `R` in time which was signed at some point `S` in time
   /// and expires at some point `E` in time, as depicted below:
   ///
diff --git a/llarp/peerstats/peer_db.hpp b/llarp/peerstats/peer_db.hpp
index c61fb3716..d7985e1bd 100644
--- a/llarp/peerstats/peer_db.hpp
+++ b/llarp/peerstats/peer_db.hpp
@@ -82,6 +82,14 @@ namespace llarp
     std::optional<PeerStats>
     getCurrentPeerStats(const RouterID& routerId) const;
 
+    /// Lists all peer stats. This essentially dumps the database into a list of PeerStats objects.
+    ///
+    /// Note that this avoids disk I/O by copying from our cached map of peers.
+    ///
+    /// @return a list of all PeerStats we have maintained
+    std::vector<PeerStats>
+    listAllPeerStats() const;
+
     /// Handles a new gossiped RC, updating stats as needed. The database tracks the last
     /// advertised update time, so it knows whether this is a new RC or not.
     ///
diff --git a/llarp/peerstats/types.cpp b/llarp/peerstats/types.cpp
index 4a0900760..af78d70c0 100644
--- a/llarp/peerstats/types.cpp
+++ b/llarp/peerstats/types.cpp
@@ -101,7 +101,7 @@ namespace llarp
   }
 
   void
-  PeerStats::BEncode(llarp_buffer_t* buf)
+  PeerStats::BEncode(llarp_buffer_t* buf) const
   {
     if (not buf)
       throw std::runtime_error("PeerStats: Can't use null buf");
@@ -138,4 +138,22 @@ namespace llarp
 
   }
 
+  void
+  PeerStats::BEncodeList(const std::vector<PeerStats>& statsList, llarp_buffer_t* buf)
+  {
+    if (not buf)
+      throw std::runtime_error("PeerStats: Can't use null buf");
+
+    if (not bencode_start_list(buf))
+      throw std::runtime_error("PeerStats: Could not create bencode dict");
+
+    for (const auto& stats : statsList)
+    {
+      stats.BEncode(buf);
+    }
+
+    if (not bencode_end(buf))
+      throw std::runtime_error("PeerStats: Could not end bencode dict");
+  }
+
 };  // namespace llarp
diff --git a/llarp/peerstats/types.hpp b/llarp/peerstats/types.hpp
index d705d99db..78684a61a 100644
--- a/llarp/peerstats/types.hpp
+++ b/llarp/peerstats/types.hpp
@@ -50,7 +50,10 @@ namespace llarp
     toJson() const;
 
     void
-    BEncode(llarp_buffer_t* buf);
+    BEncode(llarp_buffer_t* buf) const;
+
+    static void
+    BEncodeList(const std::vector<PeerStats>& statsList, llarp_buffer_t* buf);
   };
 
 }  // namespace llarp
diff --git a/llarp/rpc/lokid_rpc_client.cpp b/llarp/rpc/lokid_rpc_client.cpp
index 640131167..aef954844 100644
--- a/llarp/rpc/lokid_rpc_client.cpp
+++ b/llarp/rpc/lokid_rpc_client.cpp
@@ -220,12 +220,40 @@ namespace llarp
     void
     LokidRpcClient::HandleGetPeerStats(lokimq::Message& msg)
     {
-      // TODO: construct response
       LogInfo("Got request for peer stats (size: ", msg.data.size(), ")");
       for (auto str : msg.data)
       {
         LogInfo("    :", str);
       }
+
+      assert(m_Router != nullptr);
+
+      if (not m_Router->peerDb())
+      {
+        LogWarn("HandleGetPeerStats called when router has no peerDb set up.");
+        throw std::runtime_error("Cannot handle get_peer_stats request when no peer db available");
+      }
+
+      try
+      {
+        // TODO: parse input, expect list of peers to query for
+
+        auto statsList = m_Router->peerDb()->listAllPeerStats();
+
+        int32_t bufSize =
+            256 + (statsList.size() * 1024);  // TODO: tune this or allow to grow dynamically
+        auto buf = std::unique_ptr<uint8_t[]>(new uint8_t[bufSize]);
+        llarp_buffer_t llarpBuf(buf.get(), bufSize);
+
+        PeerStats::BEncodeList(statsList, &llarpBuf);
+
+        msg.send_reply(std::string_view((const char*)llarpBuf.base, llarpBuf.cur - llarpBuf.base));
+      }
+      catch (const std::exception& e)
+      {
+        LogError("Failed to handle get_peer_stats request: ", e.what());
+        // TODO: reply with explicit rejection to make lokid's life easier
+      }
     }
 
   }  // namespace rpc