From 748a806adc5a325e63ca6883b2aa9bf15da90513 Mon Sep 17 00:00:00 2001
From: T <t@tjp.lol>
Date: Thu, 3 Apr 2025 10:00:40 -0600
Subject: Harden Gopher parsing and recover server goroutines

Reject oversized or malformed Gopher selectors as parse errors instead of panicking. Keep search requests bounded, and wrap shared server goroutines with panic logging so one bad connection cannot take down the process.
---
 internal/server.go | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

(limited to 'internal/server.go')

diff --git a/internal/server.go b/internal/server.go
index 46b95ef..3ae9be2 100644
--- a/internal/server.go
+++ b/internal/server.go
@@ -2,7 +2,9 @@ package internal
 
 import (
 	"context"
+	"fmt"
 	"net"
+	"runtime/debug"
 	"strings"
 	"sync"
 
@@ -84,6 +86,7 @@ func (s *Server) Serve() error {
 		go func() {
 			defer s.Wg.Done()
 			defer func() { _ = conn.Close() }()
+			defer s.recoverPanic("connection", "remote", conn.RemoteAddr().String())
 			s.HandleConn(conn)
 		}()
 	}
@@ -129,12 +132,25 @@ func (s *Server) propagateClose() {
 	s.Wg.Add(1)
 	go func() {
 		defer s.Wg.Done()
+		defer s.recoverPanic("close propagation")
 
 		<-s.Ctx.Done()
 		_ = s.Listener.Close()
 	}()
 }
 
+func (s *Server) recoverPanic(goroutine string, keyvals ...any) {
+	if r := recover(); r != nil {
+		keyvals = append([]any{
+			"msg", "panic in server goroutine",
+			"goroutine", goroutine,
+			"panic", fmt.Sprintf("%v", r),
+			"stack", string(debug.Stack()),
+		}, keyvals...)
+		_ = s.ErrorLog.Log(keyvals...)
+	}
+}
+
 // JoinDefaultPort appends ":<port>" iff the address does not already contain a port.
 func JoinDefaultPort(address string, port string) string {
 	if len(address) > 0 && address[0] == '[' {
-- 
cgit v1.3