Expose AuthContext in C#

[jtattermusch]

Expose C core's auth context in C#, ready for initial review.

@jboeuf for general sanity
@apolcyn for C#

@nathanielmanistaatgoogle FYI

[jtattermusch]

@apolcyn this should be ready for review.

[apolcyn]

nit: extra blank line here

[jtattermusch]

done.

[apolcyn]

nit: s/"string of value"/"string value"

[jtattermusch]

done

[apolcyn]

nit: s/"and instance"/"an instance"`

[jtattermusch]

done

[apolcyn]

nit: IMO only but maybe simpler as:

                if (!propertiesDict.ContainsKey(authProperty.Name))
                {
                    propertiesDict[authProperty.Name] = new List<AuthProperty>();
                }
                propertiesDict[authProperty.Name].Add(authProperty);

[jtattermusch]

done.

[apolcyn]

small wording nits on summary comments. s/a/an

[jtattermusch]

done

[jtattermusch]

comments addressed.

[apolcyn]

comments I accidentally left out - I think. sorry ignore if already saw these

[apolcyn]

always safe to assume the value read out is UTF8 encoded?

[jtattermusch]

I think so.

[apolcyn]

nit: for comment, 'Gets the string value of the property as a UTF8 decoding of the value's bytes.' ?

[jtattermusch]

To me that's an implementation detail. Normally, the auth property will be created by gRPC and users will just read string values and from that perspective, the original encoding is not really important.

[apolcyn]

since it looks like AuthProperty only created within grpc and passed up to the app, does the Create method here need to be exposed?

[jtattermusch]

It is useful for testing, otherwise there is no way for the users to create instances of AuthProperty.

[apolcyn]

For that, need the public constructor for AuthContext too?

[jtattermusch]

I'd better not expose the public constructor for AuthContext for now. Once a constructor is published, it's hard to change the internals of the auth context if changes are necessary. We can later add the constructor once the existing implementation proves to be working well for people.

[apolcyn]

nit: for comment, 'Gets the string value of the property as a UTF8 decoding of the value's bytes.' ?

[apolcyn]

more idiomatic to use the Enumerable<AuthProperty>?

one thought on API is it seems AuthContext could be more like a dictionary.

basically Dictionary<string, List<Property>> could be more like Dictionary<string, List<Value>>?

[jtattermusch]

yeah, ideally properties should be a read only multi-map, but unfortunately C# libraries don't have a type for multimap nor they have the right type that would allow use to preserve immutability. So what I'm exposing is my best attempt to make the API clear and preserve all the properties I want it to have.

[apolcyn]

For that, need the public constructor for AuthContext too?

[jtattermusch]

I believe I've addressed/answered all comments.
Also rebased against the latest master and added a note that AuthContext/AuthProperty api is experimental for now (so we have a bit of freedom to make adjustments to the API if needed).
Btw, master now has a high-level doc about server side auth (docs/server_side_auth.md)

PTAL.

[jtattermusch]

Known failures:

• TIMEOUT: qps_json_driver.cpp_protobuf_sync_unary_qps_unconstrained_secure_500kib_resource_quota  #9399
• HTTP parsing broken in interop tests (for large messages) #9956

[jtattermusch]

@dgquintas FYI I'd like to merge this one before cutting the 1.2.x release branch (I need a final LGTM)

[apolcyn]

LGTM

[dgquintas]

@jtattermusch in that case add the "release blocker" label