From d596e7045d420467b4217b5e91e0e7e9cd4257dd Mon Sep 17 00:00:00 2001
From: Alirie Gray <alirie.gray@gmail.com>
Date: Wed, 29 May 2019 13:33:44 -0700
Subject: [PATCH] Fix runtime panic

---
 ping.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/ping.go b/ping.go
index 53fdf69..b9d64fa 100644
--- a/ping.go
+++ b/ping.go
@@ -442,7 +442,7 @@ func (p *Pinger) processPacket(recv *packet) error {
 	var proto int
 	if p.ipv4 {
 		if p.network == "ip" {
-			bytes = ipv4Payload(recv.bytes)
+			bytes = ipv4Payload(recv)
 		} else {
 			bytes = recv.bytes
 		}
@@ -591,11 +591,13 @@ func byteSliceOfSize(n int) []byte {
 	return b
 }
 
-func ipv4Payload(b []byte) []byte {
+func ipv4Payload(recv *packet) []byte {
+	b := recv.bytes
 	if len(b) < ipv4.HeaderLen {
 		return b
 	}
 	hdrlen := int(b[0]&0x0f) << 2
+	recv.nbytes -= hdrlen
 	return b[hdrlen:]
 }