fix incorrect IP address range calculation when using /0 prefix (mfon…

…tanini#484) (mfontanini#486)

According to the C/C++ Standard, for shift operations, the behavior is undefined if the right operand is equal to the width of the promoted left operand.
On a 64-bit Windows machine, this causes IP addresses 0.0.0.0 and 255.255.255.255 to have the same internal representation, leading to various issues when using a /0 prefix.

src/ip_address.cpp

@@ -62,7 +62,7 @@ const AddressRange<IPv4Address> loopback_range = IPv4Address("127.0.0.0") / 8;
 const AddressRange<IPv4Address> multicast_range = IPv4Address("224.0.0.0") / 4;
 
 IPv4Address IPv4Address::from_prefix_length(uint32_t prefix_length) {
-    return IPv4Address(Endian::host_to_be(0xffffffff << (32 - prefix_length)));
+    return IPv4Address(prefix_length ? Endian::host_to_be(0xffffffff << (32 - prefix_length)) : 0u);
 }
 
 IPv4Address::IPv4Address(uint32_t ip) 

tests/src/address_range_test.cpp

@@ -12,11 +12,19 @@ using namespace Tins;
 
 class AddressRangeTest : public testing::Test {
 public:
+    void contain_tests0(const IPv4Range& range);
+    void contain_tests0(const IPv6Range& range);
     void contain_tests24(const IPv4Range& range);
     void contain_tests24(const IPv6Range& range);
     void contain_tests26(const IPv4Range& range);
 };
 
+void AddressRangeTest::contain_tests0(const IPv4Range& range) {
+    EXPECT_TRUE(range.contains("0.0.0.0"));
+    EXPECT_TRUE(range.contains("192.168.1.1"));
+    EXPECT_TRUE(range.contains("255.255.255.255"));
+}
+
 void AddressRangeTest::contain_tests24(const IPv4Range& range) {
     EXPECT_TRUE(range.contains("192.168.0.0"));
     EXPECT_TRUE(range.contains("192.168.0.1"));
@@ -33,6 +41,12 @@ void AddressRangeTest::contain_tests26(const IPv4Range& range) {
     EXPECT_FALSE(range.contains("192.168.254.191"));
 }
 
+void AddressRangeTest::contain_tests0(const IPv6Range& range) {
+    EXPECT_TRUE(range.contains("::"));
+    EXPECT_TRUE(range.contains("dead::1:1"));
+    EXPECT_TRUE(range.contains("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"));
+}
+
 void AddressRangeTest::contain_tests24(const IPv6Range& range) {
     EXPECT_TRUE(range.contains("dead::1"));
     EXPECT_TRUE(range.contains("dead::1fee"));
@@ -42,13 +56,22 @@ void AddressRangeTest::contain_tests24(const IPv6Range& range) {
 }
 
 TEST_F(AddressRangeTest, Contains) {
+    contain_tests0(IPv4Range("0.0.0.0", "255.255.255.255"));
+    contain_tests0(IPv4Range::from_mask("0.0.0.0", "0.0.0.0"));
+    contain_tests0(IPv4Range::from_mask("0.0.0.0", IPv4Address::from_prefix_length(0)));
     contain_tests24(IPv4Range("192.168.0.0", "192.168.0.255"));
     contain_tests24(IPv4Range::from_mask("192.168.0.0", "255.255.255.0"));
+    contain_tests24(IPv4Range::from_mask("192.168.0.0", IPv4Address::from_prefix_length(24)));
     contain_tests26(IPv4Range("192.168.254.192", "192.168.254.255"));
     contain_tests26(IPv4Range::from_mask("192.168.254.192", "255.255.255.192"));
+    contain_tests26(IPv4Range::from_mask("192.168.254.192", IPv4Address::from_prefix_length(26)));
 
+    contain_tests0(IPv6Range("::0", "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"));
+    contain_tests0(IPv6Range::from_mask("::", "::"));
+    contain_tests0(IPv6Range::from_mask("::", IPv6Address::from_prefix_length(0)));
     contain_tests24(IPv6Range("dead::0", "dead::ffff"));
     contain_tests24(IPv6Range::from_mask("dead::0", "ffff:ffff:ffff:ffff:ffff:ffff:ffff:0"));
+    contain_tests24(IPv6Range::from_mask("dead::0", IPv6Address::from_prefix_length(112)));
 
     {
         AddressRange<HWAddress<6> > range("00:00:00:00:00:00", "00:00:00:00:00:ff");