ArgumentNullException("chars") is thrown when iterating HeaderDictionary

[kadukf]

Iterating over Request.Headers throws ArgumentNullException in case the web hosting uses WebListener/HttpSysListener and the request contains a header with empty value, e.g.

GET /api/values HTTP/1.1
If-None-Match:

It fails when calling UTF8Encoding.GetChars(byte* bytes, int byteCount, char* chars, int charCount) because chars point to IntPtr.Zero.

In case of Kestrel, all is fine.

[Tratcher]

Can you share the full stack trace? I assume the issue is here:

HttpSysServer/src/Microsoft.AspNetCore.Server.HttpSys/RequestProcessing/NativeRequestContext.cs

Line 275 in 015de50

if (pKnownHeader->pRawValue != null)

What client are you using? Most won't send empty headers.

[kadukf]

Stack trace:

at System.Text.UTF8Encoding.GetChars(Byte* bytes, Int32 byteCount, Char* chars, Int32 charCount)
at Microsoft.Net.Http.Server.HeaderEncoding.GetString(SByte* pBytes, Int32 byteCount)
at Microsoft.Net.Http.Server.NativeRequestContext.GetKnownHeader(HttpSysRequestHeader header)
at Microsoft.Net.Http.Server.RequestHeaders.get_IfNoneMatch()
at Microsoft.Net.Http.Server.RequestHeaders.d__201.MoveNext()
at System.Linq.Enumerable.d__58`1.MoveNext()

[kadukf]

We have a clients which send us such payload. We migrated from OWIN to ASPNETCORE and we have this regression. We have a nasty hack implemented using reflection (class Microsoft.Net.Http.Server.HeaderEncoding, field Encoding) but we want to get rid of this hack.