From 759013750f98f80739bc531d267f9ee3e4322aa9 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Thu, 3 Feb 2022 10:27:16 +0100
Subject: [PATCH] Bump RLIMIT_NOFILE

We're a TCP server, we'll handle potentially a lot of FDs.

See https://0pointer.net/blog/file-descriptor-limits.html
---
 cmd/tlstunnel/main.go | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/cmd/tlstunnel/main.go b/cmd/tlstunnel/main.go
index c9d2e64..d99652a 100644
--- a/cmd/tlstunnel/main.go
+++ b/cmd/tlstunnel/main.go
@@ -54,10 +54,26 @@ func newServer() (*tlstunnel.Server, error) {
 	return srv, nil
 }
 
+func bumpOpenedFileLimit() error {
+	var rlimit syscall.Rlimit
+	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit); err != nil {
+		return fmt.Errorf("failed to get RLIMIT_NOFILE: %v", err)
+	}
+	rlimit.Cur = rlimit.Max
+	if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit); err != nil {
+		return fmt.Errorf("failed to set RLIMIT_NOFILE: %v", err)
+	}
+	return nil
+}
+
 func main() {
 	flag.StringVar(&configPath, "config", configPath, "path to configuration file")
 	flag.Parse()
 
+	if err := bumpOpenedFileLimit(); err != nil {
+		log.Printf("failed to bump max number of opened files: %v", err)
+	}
+
 	srv, err := newServer()
 	if err != nil {
 		log.Fatalf("failed to create server: %v", err)