1 files changed, 54 insertions, 0 deletions
diff --git a/src/net/sock_linux.go b/src/net/sock_linux.go
new file mode 100644
index 0000000..cffe9a2
--- /dev/null
+++ b/src/net/sock_linux.go
@@ -0,0 +1,54 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import (
+	"internal/syscall/unix"
+	"syscall"
+)
+
+// Linux stores the backlog as:
+//
+//   - uint16 in kernel version < 4.1,
+//   - uint32 in kernel version >= 4.1
+//
+// Truncate number to avoid wrapping.
+//
+// See issue 5030 and 41470.
+func maxAckBacklog(n int) int {
+	major, minor := unix.KernelVersion()
+	size := 16
+	if major > 4 || (major == 4 && minor >= 1) {
+		size = 32
+	}
+
+	var max uint = 1<<size - 1
+	if uint(n) > max {
+		n = int(max)
+	}
+	return n
+}
+
+func maxListenerBacklog() int {
+	fd, err := open("/proc/sys/net/core/somaxconn")
+	if err != nil {
+		return syscall.SOMAXCONN
+	}
+	defer fd.close()
+	l, ok := fd.readLine()
+	if !ok {
+		return syscall.SOMAXCONN
+	}
+	f := getFields(l)
+	n, _, ok := dtoi(f[0])
+	if n == 0 || !ok {
+		return syscall.SOMAXCONN
+	}
+
+	if n > 1<<16-1 {
+		return maxAckBacklog(n)
+	}
+	return n
+}