Access the local address of a call from ServerCallHandler

[fiower]

Please answer these questions before submitting your issue.

What version of gRPC are you using?

most recent

What did you expect to see?

After #4134, I'd like to know which port/address the current inbound request comes from.

[zpencer]

Would the authority be sufficient here?

[carl-mastrangelo]

@zpencer in this case it would not. The server wants to to know what address it was listening on which is not exposed. The authority would say who the client thinks it is talking to, but that may not include the port.

[ejona86]

What is the use-case here? I see #4134 is related, but what will you do with the address/port? Is this to have like a "admin port" which has different authn/authz/security checking?

[fiower]

@ejona86 My use case may not be common -- I'm creating a gRPC proxy which involves differentiating servers which implement the same service with different ports of the proxy.

@zpencer I guess authority would work in my case if I could make sure all address contains port, is it right? But it's kind of indirect and depends on the "host:port" assumption, as @carl-mastrangelo suggested.

[ejona86]

@fiower, why not configure your proxy differently between the two ports? Is there some reason making two instances of the proxy service (one for each server/port) would be a problem? I could understand more if you needed the local ip, but it sounds like you need the local port; that's likely best served in other ways.

I'm not against providing local address information, but it sounds like even if it was available today I would suggest avoid using it for your use-case.

[ejona86]

@fiower, friendly ping.

[fiower]

@ejona86 Yes, this should work though ideally I'd like to only have one instance of the proxy component. The authority approach would also work in my case.

[ejona86]

We've seen another request for this internally at b/116771888. It can be used for security analysis and to create a connection to back the same server for co-hosted protocols other than gRPC.