Modernize CookieContainer domain-matching

src/libraries/Common/src/System/Net/CookieComparer.cs

@@ -23,11 +23,8 @@ internal static bool Equals(Cookie left, Cookie right)
         }
 
         internal static bool EqualDomains(ReadOnlySpan<char> left, ReadOnlySpan<char> right)
-        {
-            if (left.StartsWith('.')) left = left.Slice(1);
-            if (right.StartsWith('.')) right = right.Slice(1);
+            => StripLeadingDot(left).Equals(StripLeadingDot(right), StringComparison.OrdinalIgnoreCase);
 
-            return left.Equals(right, StringComparison.OrdinalIgnoreCase);
-        }
+        internal static ReadOnlySpan<char> StripLeadingDot(ReadOnlySpan<char> s) => s.StartsWith('.') ? s[1..] : s;
     }
 }

src/libraries/System.Net.Primitives/src/System.Net.Primitives.csproj

@@ -76,8 +76,6 @@
              Link="Common\System\Net\SocketAddressExtensions.cs" />
     <Compile Include="$(CommonPath)System\Net\NegotiationInfoClass.cs"
              Link="Common\System\Net\NegotiationInfoClass.cs" />
-    <Compile Include="$(CommonPath)System\Net\NetworkInformation\HostInformation.cs"
-             Link="Common\System\Net\NetworkInformation\HostInformation.cs" />
     <Compile Include="$(CommonPath)System\Text\StringBuilderCache.cs"
              Link="Common\System\Text\StringBuilderCache.cs" />
     <Compile Include="$(CommonPath)System\HexConverter.cs"

src/libraries/System.Net.Primitives/tests/FunctionalTests/CookieTest.cs

@@ -294,6 +294,8 @@ public static void Equals_Compare_Success()
             Cookie c14 = new Cookie("name", "value", "path", "domain") { Version = 5 };
             Cookie c15 = new Cookie("name", "value", "path", "domain") { Version = 100 };
 
+            Cookie c9dot = new Cookie("name", "value", "path", ".domain");
+
             Assert.False(c2.Equals(null));
             Assert.False(c2.Equals(""));
 
@@ -329,6 +331,9 @@ public static void Equals_Compare_Success()
             Assert.NotEqual(c13, c15);
             Assert.Equal(c13.GetHashCode(), c14.GetHashCode());
             Assert.NotEqual(c13.GetHashCode(), c15.GetHashCode());
+
+            Assert.Equal(c9, c9dot);
+            Assert.Equal(c9.GetHashCode(), c9dot.GetHashCode());
         }
 
         [Fact]

src/libraries/System.Net.Primitives/tests/FunctionalTests/CookieTest/CookieContainerTest.cs

@@ -93,39 +93,6 @@ public void GetCookies_AddCookieVersion0WithExplicitDomain_CookieReturnedForDoma
             Assert.Equal(1, cookies.Count);
         }
 
-        [Fact]
-        public void GetCookies_AddCookieVersion1WithExplicitDomain_CookieReturnedForDomainAndOneLevelSubDomain()
-        {
-            const string SchemePrefix = "http://";
-            const string OriginalDomain = "contoso.com";
-            const string OriginalDomainWithLeadingDot = "." + OriginalDomain;
-
-            var container = new CookieContainer();
-            var cookie1 = new Cookie(CookieName1, CookieValue1) { Domain = OriginalDomainWithLeadingDot, Version = 1 };
-            container.Add(new Uri(SchemePrefix + OriginalDomain), cookie1);
-
-            var uri = new Uri(SchemePrefix + OriginalDomain);
-            var cookies = container.GetCookies(uri);
-            Assert.Equal(1, cookies.Count);
-            Assert.Equal(OriginalDomainWithLeadingDot, cookies[CookieName1].Domain);
-
-            uri = new Uri(SchemePrefix + "www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(1, cookies.Count);
-
-            uri = new Uri(SchemePrefix + "x.www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(0, cookies.Count);
-
-            uri = new Uri(SchemePrefix + "y.x.www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(0, cookies.Count);
-
-            uri = new Uri(SchemePrefix + "z.y.x.www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(0, cookies.Count);
-        }
-
         [Fact]
         public void GetAllCookies_Empty_ReturnsEmptyCollection()
         {

src/libraries/System.Net.Primitives/tests/UnitTests/CookieContainerTest.cs

@@ -467,39 +467,6 @@ public void GetCookies_AddCookieVersion0WithExplicitDomain_CookieReturnedForDoma
             Assert.Equal(1, cookies.Count);
         }
 
-        [Fact]
-        public void GetCookies_AddCookieVersion1WithExplicitDomain_CookieReturnedForDomainAndOneLevelSubDomain()
-        {
-            const string SchemePrefix = "http://";
-            const string OriginalDomain = "contoso.com";
-            const string OriginalDomainWithLeadingDot = "." + OriginalDomain;
-
-            var container = new CookieContainer();
-            var cookie1 = new Cookie(CookieName1, CookieValue1) { Domain = OriginalDomainWithLeadingDot, Version = 1 };
-            container.Add(new Uri(SchemePrefix + OriginalDomain), cookie1);
-
-            var uri = new Uri(SchemePrefix + OriginalDomain);
-            CookieCollection cookies = container.GetCookies(uri);
-            Assert.Equal(1, cookies.Count);
-            Assert.Equal(OriginalDomainWithLeadingDot, cookies[CookieName1].Domain);
-
-            uri = new Uri(SchemePrefix + "www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(1, cookies.Count);
-
-            uri = new Uri(SchemePrefix + "x.www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(0, cookies.Count);
-
-            uri = new Uri(SchemePrefix + "y.x.www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(0, cookies.Count);
-
-            uri = new Uri(SchemePrefix + "z.y.x.www." + OriginalDomain);
-            cookies = container.GetCookies(uri);
-            Assert.Equal(0, cookies.Count);
-        }
-
         [Fact]
         public void Ctor_Capacity_Success()
         {
@@ -590,13 +557,20 @@ public void Add_SameCookieDifferentVairants_OverridesOlderVariant()
         {
             Uri uri = new Uri("http://domain.com");
 
+            Cookie c0 = new Cookie("name1", "value", "", "domain.com");
             Cookie c1 = new Cookie("name1", "value", "", ".domain.com"); // Variant = Plain
             Cookie c2 = new Cookie("name1", "value", "", ".domain.com") { Port = "\"80\"" }; // Variant = RFC2965 (should override)
             Cookie c3 = new Cookie("name1", "value", "", ".domain.com") { Port = "\"80, 90\"" }; // Variant = RFC2965 (should override)
             Cookie c4 = new Cookie("name1", "value", "", ".domain.com") { Version = 1 }; // Variant = RFC2109 (should be rejected)
 
             CookieContainer cc = new CookieContainer();
+
+            cc.Add(c0);
+            Assert.Equal("domain.com", cc.GetCookies(uri)[0].Domain);
+
             cc.Add(c1);
+            Assert.Equal(1, cc.Count);
+            Assert.Equal(".domain.com", cc.GetCookies(uri)[0].Domain);
 
             // Adding a newer variant should override an older one
             cc.Add(c2);
@@ -614,6 +588,24 @@ public void Add_SameCookieDifferentVairants_OverridesOlderVariant()
             Assert.Equal(1, cc.Count);
         }
 
+        [Fact]
+        public static void Add_SetCookies_SameCookieDifferentVairants_OverridesOlderVariant()
+        {
+            Uri uri = new Uri("http://domain.com");
+            CookieContainer cc = new();
+            Cookie a = new()
+            {
+                Domain = "domain.com",
+                Name = "lol",
+                Value = "0"
+            };
+            cc.Add(uri, a);
+            cc.SetCookies(uri, "lol=42");
+
+            Assert.Equal(1, cc.Count);
+            Assert.Equal("42", cc.GetCookies(uri).Single().Value);
+        }
+
         [Fact]
         public void Add_Cookie_Invalid()
         {
@@ -781,10 +773,10 @@ private void VerifyGetCookies(CookieContainer cc1, Uri uri, Cookie[] expected)
 
             for (int i = 0; i < expected.Length; i++)
             {
-                Cookie c1 = expected[i];
                 Cookie c2 = cc2[i];
-                Assert.Equal(c1.Name, c2.Name); // Primitive check for equality
-                Assert.Equal(c1.Value, c2.Value);
+                Cookie c1 = expected.Single(c => c.Name == c2.Name);
+
+                Assert.Equal(c1.Value, c2.Value); // Primitive check for equality
             }
         }
 
@@ -983,5 +975,100 @@ public void GetCookies_PathMatchingFollowsRfc6265(bool useDefaultPath, string[]
             CookieCollection collection = container.GetCookies(requestUri);
             Assert.Equal(expectedMatches, collection.Count);
         }
+
+        [Fact]
+        public void Add_ImplicitDomainOfIPv6Hostname_Success()
+        {
+            CookieContainer container = new CookieContainer();
+            Cookie cookie = new Cookie("lol", "haha");
+            Uri uri = new Uri("https://[::FFFF:192.168.0.1]/test");
+            container.Add(uri, cookie);
+            Assert.Equal(uri.Host, container.GetCookies(uri).Single().Domain);
+        }
+
+        public static TheoryData<string, string> DomainMatching_WhenMatches_Success_Data = new TheoryData<string, string>()
+        {
+            { "https://q", "q" },
+            { "https://localhost/", "localhost" },
+            { "https://test.com", "test.com" },
+            { "https://test.COM", "tEsT.com" },
+            { "https://test.com", ".test.com" },
+            { "https://yay.test.com", "yay.test.com" },
+            { "https://yay.test.com", ".yay.test.com" },
+            { "https://yay.test.com", ".test.com" },
+            { "https://42.aaaa.bbb.cc.d.test.com", "d.test.com" },
+            { "https://yay.test.com/foo/bar", "test.com" },
+            { "https://127.0.1.1", "127.0.1.1" },
+            { "https://42.42.100.100", "42.42.100.100" },
+        };
+
+        [Theory]
+        [MemberData(nameof(DomainMatching_WhenMatches_Success_Data))]
+        public void DomainMatching_WhenMatches_Success(string uriString, string domain)
+        {
+            CookieContainer container = new CookieContainer();
+            Cookie cookie = new Cookie("lol", "haha")
+            {
+                Domain = domain
+            };
+
+            Uri uri = new Uri(uriString);
+            container.Add(uri, cookie);
+            Assert.Equal(1, container.Count);
+
+            CookieCollection collection = container.GetCookies(uri);
+            Assert.Equal(1, collection.Count);
+        }
+
+        [Fact]
+        public void DomainMatching_ExplicitDomain_MatchesMultiple()
+        {
+            CookieContainer container = new CookieContainer();
+            Cookie a = new Cookie("a", "aa", null, "a.com");
+            Cookie b = new Cookie("b", "bb", null, "b.a.com");
+            Cookie c = new Cookie("c", "cc", null, "c.b.a.com");
+
+            container.Add(new Uri("http://a.com"), a);
+            container.Add(new Uri("http://b.a.com"), b);
+            container.Add(new Uri("http://c.b.a.com"), c);
+
+            CookieCollection matches = container.GetCookies(new Uri("http://c.b.a.com"));
+            Assert.Equal(3, matches.Count);
+        }
+
+        public static TheoryData<string, string> DomainMatching_WhenDoesNotMatch_ThrowsCookieException_Data = new TheoryData<string, string>()
+        {
+            { "https://test.com", "test.co" }, // Domain is not a suffix
+            { "https://test.com", "x.test.com" }, // Domain is not a suffix (extra chars at start)
+            { "https://test.com", "ttest.com" }, // Suffix but not separated by dot
+            { "https://test.com", "test.com." }, // Trailing dot
+            { "https://test.com", "..test.com" }, // 2 leading dots
+            { "https://foo.test.com", "yay.test.com" }, // subdomain mismatch
+            { "https://42.42.100.100", "41.42.100.100" }, // different IP
+
+            // Single label domain without a full match.
+            { "https://test.com", ".com" },
+            { "https://test.com", "com" }, 
+
+            // If Host is an IP address, it should be equal to the domain.
+            // See https://issues.chromium.org/issues/40126142 and the last condition in
+            // https://datatracker.ietf.org/doc/html/rfc6265#section-5.1.3
+            { "https://1.2.3.4", ".2.3.4" }
+        };
+
+
+        [Theory]
+        [MemberData(nameof(DomainMatching_WhenDoesNotMatch_ThrowsCookieException_Data))]
+        public void DomainMatching_WhenDoesNotMatch_ThrowsCookieException(string uriString, string domain)
+        {
+            CookieContainer container = new CookieContainer();
+            Cookie cookie = new Cookie("lol", "haha")
+            {
+                Domain = domain
+            };
+
+            Uri uri = new Uri(uriString);
+            Assert.Throws<CookieException>(() => container.Add(uri, cookie));
+        }
     }
 }

src/libraries/System.Net.Primitives/tests/UnitTests/System.Net.Primitives.UnitTests.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>$(NoWarn);169;649</NoWarn>
@@ -28,6 +28,10 @@
              Link="ProductionCode\System\Net\Sockets\SocketError.cs" />
     <Compile Include="..\..\src\System\Net\IPAddress.cs"
              Link="ProductionCode\System\Net\IPAddress.cs" />
+    <Compile Include="$(CommonPath)System\Net\IPv4AddressHelper.Common.cs"
+             Link="ProductionCode\Common\System\Net\IPv4AddressHelper.Common.cs" />
+    <Compile Include="$(CommonPath)System\Net\IPv6AddressHelper.Common.cs"
+             Link="ProductionCode\Common\System\Net\IPv6AddressHelper.Common.cs" />
     <Compile Include="..\..\src\System\Net\EndPoint.cs"
              Link="ProductionCode\System\Net\EndPoint.cs" />
     <Compile Include="..\..\src\System\Net\Sockets\AddressFamily.cs"
@@ -58,9 +62,6 @@
   <ItemGroup>
     <Compile Include="CookieCollectionTest.cs" />
     <Compile Include="Fakes\CookieException.cs" />
-    <Compile Include="Fakes\HostInformation.cs" />
-    <Compile Include="Fakes\IPv4AddressHelper.cs" />
-    <Compile Include="Fakes\IPv6AddressHelper.cs" />
     <Compile Include="$(CommonPath)System\Net\HttpKnownHeaderNames.cs"
              Link="ProductionCode\Common\System\Net\HttpKnownHeaderNames.cs" />
     <Compile Include="$(CommonPath)System\Net\IPAddressParserStatics.cs"