From b928d074b461c6f2578c989e48adadc951ed3154 Mon Sep 17 00:00:00 2001
From: Bhasker Hariharan <bhaskerh@google.com>
Date: Thu, 13 Aug 2020 09:02:18 -0700
Subject: Ensure TCP TIME-WAIT is not terminated prematurely.

Netstack's TIME-WAIT state for a TCP socket could be terminated prematurely if
the socket entered TIME-WAIT using shutdown(..., SHUT_RDWR) and then was closed
using close(). This fixes that bug and updates the tests to verify that Netstack
correctly honors TIME-WAIT under such conditions.

Fixes #3106

PiperOrigin-RevId: 326456443
---
 pkg/tcpip/header/ipv4.go | 9 +++++++++
 pkg/tcpip/header/ipv6.go | 3 +++
 2 files changed, 12 insertions(+)

(limited to 'pkg/tcpip/header')

diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go
index d0d1efd0d..680eafd16 100644
--- a/pkg/tcpip/header/ipv4.go
+++ b/pkg/tcpip/header/ipv4.go
@@ -315,3 +315,12 @@ func IsV4MulticastAddress(addr tcpip.Address) bool {
 	}
 	return (addr[0] & 0xf0) == 0xe0
 }
+
+// IsV4LoopbackAddress determines if the provided address is an IPv4 loopback
+// address (belongs to 127.0.0.1/8 subnet).
+func IsV4LoopbackAddress(addr tcpip.Address) bool {
+	if len(addr) != IPv4AddressSize {
+		return false
+	}
+	return addr[0] == 0x7f
+}
diff --git a/pkg/tcpip/header/ipv6.go b/pkg/tcpip/header/ipv6.go
index 4f367fe4c..ea3823898 100644
--- a/pkg/tcpip/header/ipv6.go
+++ b/pkg/tcpip/header/ipv6.go
@@ -98,6 +98,9 @@ const (
 	// section 5.
 	IPv6MinimumMTU = 1280
 
+	// IPv6Loopback is the IPv6 Loopback address.
+	IPv6Loopback tcpip.Address = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"
+
 	// IPv6Any is the non-routable IPv6 "any" meta address. It is also
 	// known as the unspecified address.
 	IPv6Any tcpip.Address = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
-- 
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