From d01c14193202748b5ae46bee051dff91c08bb2e0 Mon Sep 17 00:00:00 2001
From: Dominik Roos <roos@anapaya.net>
Date: Fri, 15 Sep 2023 10:04:56 +0200
Subject: [PATCH] scion/ping: wait for send go routine to terminate

Wait for the ping sender go routine to terminate before we return the
stats. With bad luck, the receiver go routine receives all the replies
before the sender go routine has terminated. Because only the sender
go routine increments the stats.Sent count, we end up with wrong stats
that claim more packets were received then sent.
---
 scion/ping/ping.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scion/ping/ping.go b/scion/ping/ping.go
index c332bce42c..4efea528d5 100644
--- a/scion/ping/ping.go
+++ b/scion/ping/ping.go
@@ -20,6 +20,7 @@ import (
 	"encoding/binary"
 	"math/rand"
 	"net"
+	"sync"
 	"time"
 
 	"github.com/scionproto/scion/pkg/addr"
@@ -178,8 +179,12 @@ func (p *pinger) Ping(ctx context.Context, remote *snet.UDPAddr) (Stats, error)
 		p.drain(ctx)
 	}()
 
+	var wg sync.WaitGroup
+	wg.Add(1)
+
 	go func() {
 		defer log.HandlePanic()
+		defer wg.Done()
 		for i := uint16(0); i < p.attempts; i++ {
 			if err := p.send(remote); err != nil {
 				errSend <- serrors.WrapStr("sending", err)
@@ -210,6 +215,7 @@ func (p *pinger) Ping(ctx context.Context, remote *snet.UDPAddr) (Stats, error)
 			p.receive(reply)
 		}
 	}
+	wg.Wait()
 	return p.stats, nil
 }