Add nullable annotations to Http.Abstractions, Http.Features, Connections.Abstractions

src/Http/Headers/ref/Microsoft.Net.Http.Headers.csproj

@@ -2,6 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(DefaultNetCoreTargetFramework)</TargetFrameworks>
+    <Nullable>annotations</Nullable>
   </PropertyGroup>
   <ItemGroup Condition="'$(TargetFramework)' == '$(DefaultNetCoreTargetFramework)'">
     <Compile Include="Microsoft.Net.Http.Headers.netcoreapp.cs" />

src/Http/Headers/src/BaseHeaderParser.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.Net.Http.Headers
@@ -12,11 +13,11 @@ protected BaseHeaderParser(bool supportsMultipleValues)
         {
         }
 
-        protected abstract int GetParsedValueLength(StringSegment value, int startIndex, out T parsedValue);
+        protected abstract int GetParsedValueLength(StringSegment value, int startIndex, [MaybeNull] out T parsedValue);
 
-        public sealed override bool TryParseValue(StringSegment value, ref int index, out T parsedValue)
+        public sealed override bool TryParseValue(StringSegment value, ref int index, [MaybeNull] out T parsedValue)
         {
-            parsedValue = default(T);
+            parsedValue = default;
 
             // If multiple values are supported (i.e. list of values), then accept an empty string: The header may
             // be added multiple times to the request/response message. E.g.

src/Http/Headers/src/CacheControlHeaderValue.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Diagnostics.Contracts;
 using System.Globalization;
 using System.Text;
@@ -31,12 +32,12 @@ public class CacheControlHeaderValue
         // Cache-Control headers, only one instance of CacheControlHeaderValue is created (if all headers contain valid
         // values, otherwise we may have multiple strings containing the invalid values).
         private static readonly HttpHeaderParser<CacheControlHeaderValue> Parser
-            = new GenericHeaderParser<CacheControlHeaderValue>(true, GetCacheControlLength);
+            = new GenericHeaderParser<CacheControlHeaderValue>(true, GetCacheControlLength!);
 
         private static readonly Action<StringSegment> CheckIsValidTokenAction = CheckIsValidToken;
 
         private bool _noCache;
-        private ICollection<StringSegment> _noCacheHeaders;
+        private ICollection<StringSegment>? _noCacheHeaders;
         private bool _noStore;
         private TimeSpan? _maxAge;
         private TimeSpan? _sharedMaxAge;
@@ -47,10 +48,10 @@ private static readonly HttpHeaderParser<CacheControlHeaderValue> Parser
         private bool _onlyIfCached;
         private bool _public;
         private bool _private;
-        private ICollection<StringSegment> _privateHeaders;
+        private ICollection<StringSegment>? _privateHeaders;
         private bool _mustRevalidate;
         private bool _proxyRevalidate;
-        private IList<NameValueHeaderValue> _extensions;
+        private IList<NameValueHeaderValue>? _extensions;
 
         public CacheControlHeaderValue()
         {
@@ -240,7 +241,7 @@ public override string ToString()
             return sb.ToString();
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             var other = obj as CacheControlHeaderValue;
 
@@ -325,7 +326,7 @@ public override int GetHashCode()
 
         public static CacheControlHeaderValue Parse(StringSegment input)
         {
-            int index = 0;
+            var index = 0;
             // Cache-Control is unusual because there are no required values so the parser will succeed for an empty string, but still return null.
             var result = Parser.ParseValue(input, ref index);
             if (result == null)
@@ -335,9 +336,9 @@ public static CacheControlHeaderValue Parse(StringSegment input)
             return result;
         }
 
-        public static bool TryParse(StringSegment input, out CacheControlHeaderValue parsedValue)
+        public static bool TryParse(StringSegment input, [NotNullWhen(true)] out CacheControlHeaderValue? parsedValue)
         {
-            int index = 0;
+            var index = 0;
             // Cache-Control is unusual because there are no required values so the parser will succeed for an empty string, but still return null.
             if (Parser.TryParseValue(input, ref index, out parsedValue) && parsedValue != null)
             {
@@ -347,7 +348,7 @@ public static bool TryParse(StringSegment input, out CacheControlHeaderValue par
             return false;
         }
 
-        private static int GetCacheControlLength(StringSegment input, int startIndex, out CacheControlHeaderValue parsedValue)
+        private static int GetCacheControlLength(StringSegment input, int startIndex, out CacheControlHeaderValue? parsedValue)
         {
             Contract.Requires(startIndex >= 0);
 
@@ -361,16 +362,18 @@ private static int GetCacheControlLength(StringSegment input, int startIndex, ou
             // Cache-Control header consists of a list of name/value pairs, where the value is optional. So use an
             // instance of NameValueHeaderParser to parse the string.
             var current = startIndex;
-            NameValueHeaderValue nameValue = null;
             var nameValueList = new List<NameValueHeaderValue>();
             while (current < input.Length)
             {
-                if (!NameValueHeaderValue.MultipleValueParser.TryParseValue(input, ref current, out nameValue))
+                if (!NameValueHeaderValue.MultipleValueParser.TryParseValue(input, ref current, out var nameValue))
                 {
                     return 0;
                 }
 
-                nameValueList.Add(nameValue);
+                if (nameValue != null)
+                {
+                    nameValueList.Add(nameValue);
+                }
             }
 
             // If we get here, we were able to successfully parse the string as list of name/value pairs. Now analyze
@@ -539,10 +542,8 @@ private static bool TrySetTokenOnlyValue(NameValueHeaderValue nameValue, ref boo
         private static bool TrySetOptionalTokenList(
             NameValueHeaderValue nameValue,
             ref bool boolField,
-            ref ICollection<StringSegment> destination)
+            ref ICollection<StringSegment>? destination)
         {
-            Contract.Requires(nameValue != null);
-
             if (nameValue.Value == null)
             {
                 boolField = true;
@@ -603,8 +604,6 @@ private static bool TrySetOptionalTokenList(
 
         private static bool TrySetTimeSpan(NameValueHeaderValue nameValue, ref TimeSpan? timeSpan)
         {
-            Contract.Requires(nameValue != null);
-
             if (nameValue.Value == null)
             {
                 return false;

src/Http/Headers/src/ContentDispositionHeaderValue.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Buffers;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Diagnostics.Contracts;
 using System.Globalization;
 using System.Linq;
@@ -26,10 +27,10 @@ public class ContentDispositionHeaderValue
         private static readonly char[] SingleQuote = new char[] { '\'' };
 
         private static readonly HttpHeaderParser<ContentDispositionHeaderValue> Parser
-            = new GenericHeaderParser<ContentDispositionHeaderValue>(false, GetDispositionTypeLength);
+            = new GenericHeaderParser<ContentDispositionHeaderValue>(false, GetDispositionTypeLength!);
 
         // Use list instead of dictionary since we may have multiple parameters with the same name.
-        private ObjectCollection<NameValueHeaderValue> _parameters;
+        private ObjectCollection<NameValueHeaderValue>? _parameters;
         private StringSegment _dispositionType;
 
         private ContentDispositionHeaderValue()
@@ -128,7 +129,7 @@ public long? Size
                     // Remove parameter
                     if (sizeParameter != null)
                     {
-                        _parameters.Remove(sizeParameter);
+                        _parameters!.Remove(sizeParameter);
                     }
                 }
                 else if (value < 0)
@@ -142,7 +143,7 @@ public long? Size
                 else
                 {
                     string sizeString = value.GetValueOrDefault().ToString(CultureInfo.InvariantCulture);
-                    _parameters.Add(new NameValueHeaderValue(SizeString, sizeString));
+                    _parameters!.Add(new NameValueHeaderValue(SizeString, sizeString));
                 }
             }
         }
@@ -180,7 +181,7 @@ public override string ToString()
             return _dispositionType + NameValueHeaderValue.ToString(_parameters, ';', true);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             var other = obj as ContentDispositionHeaderValue;
 
@@ -202,16 +203,16 @@ public override int GetHashCode()
         public static ContentDispositionHeaderValue Parse(StringSegment input)
         {
             var index = 0;
-            return Parser.ParseValue(input, ref index);
+            return Parser.ParseValue(input, ref index)!;
         }
 
-        public static bool TryParse(StringSegment input, out ContentDispositionHeaderValue parsedValue)
+        public static bool TryParse(StringSegment input, [NotNullWhen(true)] out ContentDispositionHeaderValue? parsedValue)
         {
             var index = 0;
-            return Parser.TryParseValue(input, ref index, out parsedValue);
+            return Parser.TryParseValue(input, ref index, out parsedValue!);
         }
 
-        private static int GetDispositionTypeLength(StringSegment input, int startIndex, out ContentDispositionHeaderValue parsedValue)
+        private static int GetDispositionTypeLength(StringSegment input, int startIndex, out ContentDispositionHeaderValue? parsedValue)
         {
             Contract.Requires(startIndex >= 0);
 
@@ -253,7 +254,7 @@ private static int GetDispositionTypeLength(StringSegment input, int startIndex,
 
         private static int GetDispositionTypeExpressionLength(StringSegment input, int startIndex, out StringSegment dispositionType)
         {
-            Contract.Requires((input != null) && (input.Length > 0) && (startIndex < input.Length));
+            Contract.Requires((input.Length > 0) && (startIndex < input.Length));
 
             // This method just parses the disposition type string, it does not parse parameters.
             dispositionType = null;
@@ -318,7 +319,7 @@ private void SetDate(string parameter, DateTimeOffset? date)
                 // Remove parameter
                 if (dateParameter != null)
                 {
-                    _parameters.Remove(dateParameter);
+                    _parameters!.Remove(dateParameter);
                 }
             }
             else
@@ -343,7 +344,7 @@ private StringSegment GetName(string parameter)
             var nameParameter = NameValueHeaderValue.Find(_parameters, parameter);
             if (nameParameter != null)
             {
-                string result;
+                string? result;
                 // filename*=utf-8'lang'%7FMyString
                 if (parameter.EndsWith("*", StringComparison.Ordinal))
                 {
@@ -375,7 +376,7 @@ private void SetName(StringSegment parameter, StringSegment value)
                 // Remove parameter
                 if (nameParameter != null)
                 {
-                    _parameters.Remove(nameParameter);
+                    _parameters!.Remove(nameParameter);
                 }
             }
             else
@@ -497,7 +498,7 @@ private unsafe string EncodeMime(StringSegment input)
         }
 
         // Attempt to decode MIME encoded strings
-        private bool TryDecodeMime(StringSegment input, out string output)
+        private bool TryDecodeMime(StringSegment input, [NotNullWhen(true)] out string? output)
         {
             Contract.Assert(input != null);
 
@@ -582,7 +583,7 @@ private static void HexEscape(StringBuilder builder, char c)
 
         // Attempt to decode using RFC 5987 encoding.
         // encoding'language'my%20string
-        private bool TryDecode5987(StringSegment input, out string output)
+        private bool TryDecode5987(StringSegment input, [NotNullWhen(true)] out string? output)
         {
             output = null;
 
@@ -593,7 +594,7 @@ private bool TryDecode5987(StringSegment input, out string output)
             }
 
             var decoded = new StringBuilder();
-            byte[] unescapedBytes = null;
+            byte[]? unescapedBytes = null;
             try
             {
                 var encoding = Encoding.GetEncoding(parts[0].ToString());

src/Http/Headers/src/ContentRangeHeaderValue.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Diagnostics.Contracts;
 using System.Globalization;
 using System.Text;
@@ -12,7 +13,7 @@ namespace Microsoft.Net.Http.Headers
     public class ContentRangeHeaderValue
     {
         private static readonly HttpHeaderParser<ContentRangeHeaderValue> Parser
-            = new GenericHeaderParser<ContentRangeHeaderValue>(false, GetContentRangeLength);
+            = new GenericHeaderParser<ContentRangeHeaderValue>(false, GetContentRangeLength!);
 
         private StringSegment _unit;
         private long? _from;
@@ -113,7 +114,7 @@ public long? Length
             get { return _from != null; }
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             var other = obj as ContentRangeHeaderValue;
 
@@ -176,16 +177,16 @@ public override string ToString()
         public static ContentRangeHeaderValue Parse(StringSegment input)
         {
             var index = 0;
-            return Parser.ParseValue(input, ref index);
+            return Parser.ParseValue(input, ref index)!;
         }
 
         public static bool TryParse(StringSegment input, out ContentRangeHeaderValue parsedValue)
         {
             var index = 0;
-            return Parser.TryParseValue(input, ref index, out parsedValue);
+            return Parser.TryParseValue(input, ref index, out parsedValue!);
         }
 
-        private static int GetContentRangeLength(StringSegment input, int startIndex, out ContentRangeHeaderValue parsedValue)
+        private static int GetContentRangeLength(StringSegment input, int startIndex, out ContentRangeHeaderValue? parsedValue)
         {
             Contract.Requires(startIndex >= 0);
 
@@ -351,7 +352,7 @@ private static bool TryCreateContentRange(
             int toLength,
             int lengthStartIndex,
             int lengthLength,
-            out ContentRangeHeaderValue parsedValue)
+            [NotNullWhen(true)]out ContentRangeHeaderValue? parsedValue)
         {
             parsedValue = null;
 

src/Http/Headers/src/CookieHeaderParser.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Diagnostics.Contracts;
 using Microsoft.Extensions.Primitives;
 
@@ -13,7 +14,7 @@ internal CookieHeaderParser(bool supportsMultipleValues)
         {
         }
 
-        public override bool TryParseValue(StringSegment value, ref int index, out CookieHeaderValue parsedValue)
+        public override bool TryParseValue(StringSegment value, ref int index, [MaybeNull] out CookieHeaderValue? parsedValue)
         {
             parsedValue = null;
 
@@ -43,7 +44,7 @@ public override bool TryParseValue(StringSegment value, ref int index, out Cooki
                 return SupportsMultipleValues;
             }
 
-            CookieHeaderValue result = null;
+            CookieHeaderValue? result = null;
             if (!CookieHeaderValue.TryGetCookieLength(value, ref current, out result))
             {
                 return false;
@@ -64,7 +65,6 @@ public override bool TryParseValue(StringSegment value, ref int index, out Cooki
 
         private static int GetNextNonEmptyOrWhitespaceIndex(StringSegment input, int startIndex, bool skipEmptyValues, out bool separatorFound)
         {
-            Contract.Requires(input != null);
             Contract.Requires(startIndex <= input.Length); // it's OK if index == value.Length.
 
             separatorFound = false;