From 4ba9e2ef068ce38cc0f710f3a9a508aa6c14b82d Mon Sep 17 00:00:00 2001
From: songjiayang <songjiayang1@gmail.com>
Date: Tue, 9 Jul 2019 11:34:56 +0800
Subject: [PATCH] icmp: fix ListenPacket panic

Fixes golang/go#32933

Change-Id: I837d6a54e51d91ff3260ec7e1c79412c52dff20d
Reviewed-on: https://go-review.googlesource.com/c/net/+/185317
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---
 icmp/listen_posix.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/icmp/listen_posix.go b/icmp/listen_posix.go
index e1b1aa96..f0f1f2ff 100644
--- a/icmp/listen_posix.go
+++ b/icmp/listen_posix.go
@@ -50,6 +50,9 @@ func ListenPacket(network, address string) (*PacketConn, error) {
 		family, proto = syscall.AF_INET6, iana.ProtocolIPv6ICMP
 	default:
 		i := last(network, ':')
+		if i < 0 {
+			i = len(network)
+		}
 		switch network[:i] {
 		case "ip4":
 			proto = iana.ProtocolICMP