From 5f9a4b9757b9751c1d46c2138a299488bfff4c7f Mon Sep 17 00:00:00 2001
From: Ayman Bagabas <ayman.bagabas@gmail.com>
Date: Thu, 18 Sep 2025 12:57:40 -0400
Subject: [PATCH] feat: server: log RPC requests and responses

---
 internal/server/codec.go  | 42 +++++++++++++++++++++++++++++++++++++++
 internal/server/server.go | 22 ++++++++++++--------
 2 files changed, 56 insertions(+), 8 deletions(-)
 create mode 100644 internal/server/codec.go

diff --git a/internal/server/codec.go b/internal/server/codec.go
new file mode 100644
index 0000000000000000000000000000000000000000..9311a5767848ba25aa0e09d9b4de2768b05a1024
--- /dev/null
+++ b/internal/server/codec.go
@@ -0,0 +1,42 @@
+package server
+
+import (
+	"log/slog"
+	"net/rpc"
+
+	msgpackrpc "github.com/hashicorp/net-rpc-msgpackrpc/v2"
+)
+
+// ServerCodec is a wrapper around msgpackrpc.ServerCodec that adds logging
+// functionality.
+type ServerCodec struct {
+	*msgpackrpc.MsgpackCodec
+	logger *slog.Logger
+}
+
+var _ rpc.ServerCodec = (*ServerCodec)(nil)
+
+// ReadRequestHeader reads the request header and logs it.
+func (c *ServerCodec) ReadRequestHeader(r *rpc.Request) error {
+	err := c.MsgpackCodec.ReadRequestHeader(r)
+	if c.logger != nil {
+		c.logger.Debug("rpc request",
+			slog.String("service_method", r.ServiceMethod),
+			slog.Int("seq", int(r.Seq)),
+		)
+	}
+	return err
+}
+
+// WriteResponse writes the response and logs it.
+func (c *ServerCodec) WriteResponse(r *rpc.Response, body any) error {
+	err := c.MsgpackCodec.WriteResponse(r, body)
+	if c.logger != nil {
+		c.logger.Debug("rpc response",
+			slog.String("service_method", r.ServiceMethod),
+			slog.String("error", r.Error),
+			slog.Int("seq", int(r.Seq)),
+		)
+	}
+	return err
+}
diff --git a/internal/server/server.go b/internal/server/server.go
index 3b7e16643bac914b9b634ce70a2afd8106872e37..f4f75eda1a9dffd99a366aeaca02e01ae80df3a7 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -84,6 +84,11 @@ type Server struct {
 	shutdown atomic.Bool
 }
 
+// SetLogger sets the logger for the server.
+func (s *Server) SetLogger(logger *slog.Logger) {
+	s.logger = logger
+}
+
 // DefaultServer returns a new [Server] instance with the default address.
 func DefaultServer(cfg *config.Config) *Server {
 	return NewServer(cfg, "unix", DefaultAddr())
@@ -171,14 +176,15 @@ func (s *Server) Shutdown(ctx context.Context) error {
 }
 
 func (s *Server) handleConn(conn net.Conn) {
-	s.info("accepted connection from %s", conn.RemoteAddr())
-	msgpackrpc.ServeConn(conn)
-	// var req rpc.Request
-	// codec := msgpackrpc.NewServerCodec(conn)
-	// if err := codec.ReadRequestHeader(&req); err != nil {
-	// 	s.error("failed to read request header: %v", err)
-	// }
-	// rpc.ServeCodec(codec)
+	s.info("accepted connection", "remote_addr", conn.LocalAddr())
+	codec := &ServerCodec{
+		MsgpackCodec: msgpackrpc.NewCodec(true, true, conn),
+		logger: s.logger.With(
+			slog.String("remote_addr", conn.RemoteAddr().String()),
+			slog.String("local_addr", conn.LocalAddr().String()),
+		),
+	}
+	rpc.ServeCodec(codec)
 }
 
 func (s *Server) shuttingDown() bool {