From 3613f084c262f125c59f93097172580655b8f289 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Burak=20Varl=C4=B1?= <burakvar@amazon.co.uk>
Date: Fri, 17 Jan 2025 14:42:22 +0000
Subject: [PATCH] Make sure `mountoptions.{Send, Recv}` respects `ctx`'s
 deadline (#345)
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`net.{Listen, Dial}` functions does not accept context argument, but
only `{ListenContext, DialContext}` counterparts do. But even those
functions does not respect to context's deadline, so we need to call
`SetDeadline` with passed context's deadline explicitly to ensure
context's deadline is respected.

---

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Signed-off-by: Burak Varlı <burakvar@amazon.co.uk>
---
 pkg/podmounter/mountoptions/mount_options.go | 25 +++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/pkg/podmounter/mountoptions/mount_options.go b/pkg/podmounter/mountoptions/mount_options.go
index aa555872..73575e34 100644
--- a/pkg/podmounter/mountoptions/mount_options.go
+++ b/pkg/podmounter/mountoptions/mount_options.go
@@ -32,7 +32,8 @@ func Send(ctx context.Context, sockPath string, options Options) error {
 		return fmt.Errorf("failed to marshal message to send %s: %w", sockPath, err)
 	}
 
-	conn, err := net.Dial("unix", sockPath)
+	var d net.Dialer
+	conn, err := d.DialContext(ctx, "unix", sockPath)
 	if err != nil {
 		return fmt.Errorf("failed to dial to unix socket %s: %w", sockPath, err)
 	}
@@ -40,6 +41,14 @@ func Send(ctx context.Context, sockPath string, options Options) error {
 
 	unixConn := conn.(*net.UnixConn)
 
+	// `unixConn.WriteMsgUnix` does not respect `ctx`'s deadline, we need to call `unixConn.SetDeadline` to ensure `unixConn.WriteMsgUnix` has a deadline.
+	if deadline, ok := ctx.Deadline(); ok {
+		err := unixConn.SetDeadline(deadline)
+		if err != nil {
+			return fmt.Errorf("failed to set deadline on unix socket %s: %w", sockPath, err)
+		}
+	}
+
 	unixRights := syscall.UnixRights(options.Fd)
 	messageN, unixRightsN, err := unixConn.WriteMsgUnix(message, unixRights, nil)
 	if err != nil {
@@ -55,7 +64,7 @@ func Send(ctx context.Context, sockPath string, options Options) error {
 
 var (
 	messageRecvSize = 1024
-	// We only pass one file descriptor and its 32 bits
+	// We only pass one file descriptor and it's 32 bits
 	unixRightsRecvSize = syscall.CmsgSpace(4)
 )
 
@@ -63,12 +72,22 @@ var (
 func Recv(ctx context.Context, sockPath string) (Options, error) {
 	warnAboutLongUnixSocketPath(sockPath)
 
-	l, err := net.Listen("unix", sockPath)
+	var lc net.ListenConfig
+	l, err := lc.Listen(ctx, "unix", sockPath)
 	if err != nil {
 		return Options{}, fmt.Errorf("failed to listen unix socket %s: %w", sockPath, err)
 	}
 	defer l.Close()
 
+	// `l.Accept` does not respect `ctx`'s deadline, we need to call `ul.SetDeadline` to ensure `l.Accept` has a deadline.
+	if deadline, ok := ctx.Deadline(); ok {
+		ul := l.(*net.UnixListener)
+		err := ul.SetDeadline(deadline)
+		if err != nil {
+			return Options{}, fmt.Errorf("failed to set deadline on unix socket %s: %w", sockPath, err)
+		}
+	}
+
 	conn, err := l.Accept()
 	if err != nil {
 		return Options{}, fmt.Errorf("failed to accept connection from unix socket %s: %w", sockPath, err)