Refactoring the Windows specific code in NegotiateStream

[shrutigarg]

summary

Renaming NegoState.Windows.cs to InternalNegoState.cs as it had much common code applicable for Unix. (commit1)
Separating out the common code and windows specific code in InternalNegoState and NegoState.Windows.cs respectiviely.
Adding NegotiateInfoClass.cs to be used by Unix impl.

Tested locally both AuthenticateAsServer/Client on Windows.
/cc:@stephentoub @bartonjs @CIPop @vijaykota

[shrutigarg]

following up #5581

[vijaykota]

Adding a reference to #2483

[shrutigarg]

ping .. This is on top of the PR in dotnet/Master #5581 and has all the comments incorporated.

[stephentoub]

Why is this changing from Win32Exception to Exception? I realize the naming is poor, but it is actually supported on Unix, and it has the key features of both storing the error code and mapping it to a string supplied by the OS. Changing it to be Exception as is done here would seem to lose both of those things.

[shrutigarg]

ohk ,, in that case , will revert back.

[CIPop]

@shrutigarg The extracted new methods in NegoState.* look good, except for cases where more refactoring was made (e.g. splitting existing methods or morphing two or more methods in a single method).
While optimizations can be made, I'd prefer if these are made in separate PR after we're done with the XPlat implementation. Any optimization will require a pinning test that maximizes code coverage over the affected areas. We should avoid this extra work in the earliest phases.

To be consistent between SslStream/NegotiateStream as well as make support between Desktop and CoreFX, could we extract the PAL in a separate class? We could create NegotiateStreamPal.Windows/Unix.cs similarly to how SslStreamPal is implemented. That way, we can create a very clear PAL internal contract between platforms.

[shrutigarg]

@CIPop I fixed the refactoring by moving pal implementation to NegotiateStreamPal and created adapter class in last commit iteration. and other nit-pick comments in second last iteration. PTAL.

[vijaykota]

@stephentoub , @bartonjs. please take a look at the last 2 commits. Thanks!

[vijaykota]

@dotnet-bot test this please

[stephentoub]

@dotnet-bot test this please

[stephentoub]

Why was this case deleted?

[shrutigarg]

shrutigarg@d0a04a1#commitcomment-15873616

[stephentoub]

Ok, good, thanks.

[stephentoub]

A few more comments, but as long as they're tracked to be addressed subsequently, I think it's ok to merge this. We'll want to re-review everything before the dev branch gets merged to master.

[shrutigarg]

Thanks. Will track them in an issue.

[shrutigarg]

fixed a few comments and test issue. A few remaining comments are listed in issue #6063.

Other failures in build seems unrelated to me

[stephentoub]

@dotnet-bot test this please