Silence idle connection timeout logs in lookup and policy servers

Read timeouts on idle connections are expected behavior when Postfix
does not send further requests over a reused TCP connection. Treat
these timeouts the same as EOF — silently close instead of logging.

Co-Authored-By: OpenCode <noreply@opencode.ai>

Author: 0x46616c6b

lookup.go

@@ -2,8 +2,8 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
-	"io"
 	"net"
 	"strings"
 	"sync"
@@ -77,12 +77,11 @@ func (s *LookupServer) HandleConnection(ctx context.Context, conn net.Conn) {
 		// Read the request netstring
 		requestBytes, err := decoder.Decode()
 		if err != nil {
-			// Check if this is a normal connection closure (EOF) or an actual error
-			if err == io.EOF {
-				logger.Debug("Client closed connection")
-			} else {
-				logger.Debug("Failed to decode request", zap.Error(err))
+			var netErr net.Error
+			if errors.As(err, &netErr) && netErr.Timeout() {
+				return
 			}
+			logger.Debug("Failed to decode request", zap.Error(err))
 			return
 		}
 		request := string(requestBytes)

policy.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"net"
 	"strings"
 	"sync"
@@ -62,9 +61,11 @@ func (p *PolicyServer) HandleConnection(ctx context.Context, conn net.Conn) {
 
 		request, err := p.readRequest(reader)
 		if err != nil {
-			if !errors.Is(err, io.EOF) {
-				logger.Debug("Failed to read policy request", zap.Error(err))
+			var netErr net.Error
+			if errors.As(err, &netErr) && netErr.Timeout() {
+				return
 			}
+			logger.Debug("Failed to read policy request", zap.Error(err))
 			return
 		}