From 083e92e21eebde7a218b0da26a7a1b27c9b5e0f0 Mon Sep 17 00:00:00 2001
From: Dan Williams <dcbw@redhat.com>
Date: Fri, 4 Mar 2022 15:19:46 -0600
Subject: [PATCH] addr: add receive timeout option for AddrSubscribe

Otherwise addrSubscribeAt()'s goroutine will block in s.Receive()
and potentially call callbacks long after the done channel has
been closed by the caller.

Signed-off-by: Dan Williams <dcbw@redhat.com>
---
 addr_linux.go | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/addr_linux.go b/addr_linux.go
index e4a167d..2ca5d81 100644
--- a/addr_linux.go
+++ b/addr_linux.go
@@ -296,13 +296,13 @@ type AddrUpdate struct {
 // AddrSubscribe takes a chan down which notifications will be sent
 // when addresses change.  Close the 'done' chan to stop subscription.
 func AddrSubscribe(ch chan<- AddrUpdate, done <-chan struct{}) error {
-	return addrSubscribeAt(netns.None(), netns.None(), ch, done, nil, false, 0)
+	return addrSubscribeAt(netns.None(), netns.None(), ch, done, nil, false, 0, nil)
 }
 
 // AddrSubscribeAt works like AddrSubscribe plus it allows the caller
 // to choose the network namespace in which to subscribe (ns).
 func AddrSubscribeAt(ns netns.NsHandle, ch chan<- AddrUpdate, done <-chan struct{}) error {
-	return addrSubscribeAt(ns, netns.None(), ch, done, nil, false, 0)
+	return addrSubscribeAt(ns, netns.None(), ch, done, nil, false, 0, nil)
 }
 
 // AddrSubscribeOptions contains a set of options to use with
@@ -312,6 +312,7 @@ type AddrSubscribeOptions struct {
 	ErrorCallback     func(error)
 	ListExisting      bool
 	ReceiveBufferSize int
+	ReceiveTimeout    *unix.Timeval
 }
 
 // AddrSubscribeWithOptions work like AddrSubscribe but enable to
@@ -322,14 +323,20 @@ func AddrSubscribeWithOptions(ch chan<- AddrUpdate, done <-chan struct{}, option
 		none := netns.None()
 		options.Namespace = &none
 	}
-	return addrSubscribeAt(*options.Namespace, netns.None(), ch, done, options.ErrorCallback, options.ListExisting, options.ReceiveBufferSize)
+	return addrSubscribeAt(*options.Namespace, netns.None(), ch, done, options.ErrorCallback, options.ListExisting, options.ReceiveBufferSize, options.ReceiveTimeout)
 }
 
-func addrSubscribeAt(newNs, curNs netns.NsHandle, ch chan<- AddrUpdate, done <-chan struct{}, cberr func(error), listExisting bool, rcvbuf int) error {
+func addrSubscribeAt(newNs, curNs netns.NsHandle, ch chan<- AddrUpdate, done <-chan struct{}, cberr func(error), listExisting bool, rcvbuf int, rcvTimeout *unix.Timeval) error {
 	s, err := nl.SubscribeAt(newNs, curNs, unix.NETLINK_ROUTE, unix.RTNLGRP_IPV4_IFADDR, unix.RTNLGRP_IPV6_IFADDR)
 	if err != nil {
 		return err
 	}
+	if rcvTimeout != nil {
+		if err := s.SetReceiveTimeout(rcvTimeout); err != nil {
+			return err
+		}
+	}
+
 	if done != nil {
 		go func() {
 			<-done