server: Set incoming TTL before accepting connection

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/server/util.go b/server/util.go
index 92f73504..b122fbdb 100644
--- a/server/util.go
+++ b/server/util.go
@@ -66,6 +66,31 @@ func decodeAdministrativeCommunication(data []byte) (string, []byte) {
 	return string(data[1 : communicationLen+1]), data[communicationLen+1:]
 }
 
+func extractFileAndFamilyFromTCPListener(l *net.TCPListener) (*os.File, int, error) {
+	// Note #1: TCPListener.File() has the unexpected side-effect of putting
+	// the original socket into blocking mode. See Note #2.
+	fi, err := l.File()
+	if err != nil {
+		return nil, 0, err
+	}
+
+	// Note #2: Call net.FileListener() to put the original socket back into
+	// non-blocking mode.
+	fl, err := net.FileListener(fi)
+	if err != nil {
+		fi.Close()
+		return nil, 0, err
+	}
+	fl.Close()
+
+	family := syscall.AF_INET
+	if strings.Contains(l.Addr().String(), "[") {
+		family = syscall.AF_INET6
+	}
+
+	return fi, family, nil
+}
+
 func extractFileAndFamilyFromTCPConn(conn *net.TCPConn) (*os.File, int, error) {
 	// Note #1: TCPConn.File() has the unexpected side-effect of putting
 	// the original socket into blocking mode. See Note #2.