From ff5d4ffe1c4b379b0920bef41cdbaebb751f25aa Mon Sep 17 00:00:00 2001
From: Loic Blot <loic.blot@unix-experience.fr>
Date: Sat, 9 Feb 2019 19:52:38 +0100
Subject: [PATCH] Fix Address::isLocalhost algorithm

---
 src/network/address.cpp       |  8 ++--
 src/unittest/CMakeLists.txt   |  1 +
 src/unittest/test_address.cpp | 69 +++++++++++++++++++++++++++++++++++
 3 files changed, 74 insertions(+), 4 deletions(-)
 create mode 100644 src/unittest/test_address.cpp

diff --git a/src/network/address.cpp b/src/network/address.cpp
index 0ecface37f47..fce3b48f01a2 100644
--- a/src/network/address.cpp
+++ b/src/network/address.cpp
@@ -277,13 +277,13 @@ bool Address::isLocalhost() const {
 		static const unsigned char localhost_bytes[] = {
 				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
 		static const unsigned char mapped_ipv4_localhost[] = {
-				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 0x7f, 0, 0, 1};
+				0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 0x7f, 0, 0, 0};
 
 		auto addr = m_address.ipv6.sin6_addr.s6_addr;
 
 		return memcmp(addr, localhost_bytes, 16) == 0 ||
-			memcmp(addr, mapped_ipv4_localhost, 16) == 0;
-	} else {
-		return m_address.ipv4.sin_addr.s_addr == 0x0100007F;
+			memcmp(addr, mapped_ipv4_localhost, 13) == 0;
 	}
+
+	return (m_address.ipv4.sin_addr.s_addr & 0xFF) == 0x7f;
 }
diff --git a/src/unittest/CMakeLists.txt b/src/unittest/CMakeLists.txt
index 993137939547..71aa1fa567bd 100644
--- a/src/unittest/CMakeLists.txt
+++ b/src/unittest/CMakeLists.txt
@@ -1,5 +1,6 @@
 set (UNITTEST_SRCS
 	${CMAKE_CURRENT_SOURCE_DIR}/test.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/test_address.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_authdatabase.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_activeobject.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_areastore.cpp
diff --git a/src/unittest/test_address.cpp b/src/unittest/test_address.cpp
new file mode 100644
index 000000000000..000a648f1ff2
--- /dev/null
+++ b/src/unittest/test_address.cpp
@@ -0,0 +1,69 @@
+/*
+Minetest
+Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "test.h"
+
+#include "log.h"
+#include "settings.h"
+#include "network/socket.h"
+
+class TestAddress : public TestBase {
+public:
+	TestAddress()
+	{
+		TestManager::registerTestModule(this);
+	}
+
+	const char *getName() { return "TestAddress"; }
+
+	void runTests(IGameDef *gamedef);
+
+	void testIsLocalhost();
+};
+
+static TestAddress g_test_instance;
+
+void TestAddress::runTests(IGameDef *gamedef)
+{
+	TEST(testIsLocalhost);
+}
+
+void TestAddress::testIsLocalhost()
+{
+	// v4
+	UASSERT(Address(127, 0, 0, 1, 0).isLocalhost());
+	UASSERT(Address(127, 254, 12, 99, 0).isLocalhost());
+	UASSERT(Address(127, 188, 255, 247, 0).isLocalhost());
+	UASSERT(!Address(126, 255, 255, 255, 0).isLocalhost());
+	UASSERT(!Address(128, 0, 0, 0, 0).isLocalhost());
+	UASSERT(!Address(1, 0, 0, 0, 0).isLocalhost());
+	UASSERT(!Address(255, 255, 255, 255, 0).isLocalhost());
+	UASSERT(!Address(36, 45, 99, 158, 0).isLocalhost());
+	UASSERT(!Address(172, 45, 37, 68, 0).isLocalhost());
+
+	// v6
+	std::unique_ptr<IPv6AddressBytes> ipv6Bytes(new IPv6AddressBytes());
+	std::vector<u8> ipv6RawAddr = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+	memcpy(ipv6Bytes->bytes, &ipv6RawAddr[0], 16);
+	UASSERT(Address(ipv6Bytes.get(), 0).isLocalhost())
+
+	ipv6RawAddr = {16, 34, 0, 0, 0, 0, 29, 0, 0, 0, 188, 0, 0, 0, 0, 14};
+	memcpy(ipv6Bytes->bytes, &ipv6RawAddr[0], 16);
+	UASSERT(!Address(ipv6Bytes.get(), 0).isLocalhost())
+}