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crypto/tls: support different protocols for different server names #17666

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nhooyr opened this issue Oct 29, 2016 · 2 comments
Closed

crypto/tls: support different protocols for different server names #17666

nhooyr opened this issue Oct 29, 2016 · 2 comments

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@nhooyr
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@nhooyr nhooyr commented Oct 29, 2016

I've written a server that accepts a TLS connection, connects to a address based on the TLS connections server name and ALPN proto, and then copies all data between the two connections.
https://github.com/nhooyr/tlsmuxd

The problem that I am having is for the following configuration:

{
    "email": "user@example.com",
    "cacheDir": "/var/lib/tlsmuxd",
    "protos": [{
        "name": "h2",
        "hosts": {
            "example.com": "localhost:8080",
            "www.example.com": "localhost:8080",
        }
    }, {
        "name": "http/1.1",
        "hosts": {
            "example.com": "localhost:8083",
            "www.example.com": "localhost:8083",
            "example2.com": "localhost:8084",
            "www.example2.com": "localhost:8084"
        }
    }],
    "defaultProto": "http/1.1"
}

Now say a user connects to my server with their ALPN protos as ["h2", "http/1.1"] and server name as "example2.com". According to the above configuration, a connection to localhost:8084 should be made and then all data between the user and localhost:8084 connections should be copied. The problem is that crypto/tls does not allow for dynamic ALPN. So the "h2" protocol will always be selected and then the user will be disconnected because "example2.com" does not exist for "h2".

So I'd like is to be able to offer different protocols for different server names instead of having it static. This isn't a severe problem for me because since I use Go, I'll always be able to serve both "http/1.1" and "h2". However, it feels ugly because say I have the "ssh" protocol defined (I tunnel SSH through TLS when I need to get around a strict network) for "example.com", then if someone connects with Server Name as "example2.com", even though my server cannot actually serve it SSH, it still advertises it.

@bradfitz

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@bradfitz bradfitz commented Oct 29, 2016

Isn't this addressed by Config.GetConfigForClient from https://go-review.googlesource.com/30790?

@nhooyr

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@nhooyr nhooyr commented Oct 29, 2016

Oh, I was not aware of that. Will take a look.

edit: looks like it does. thanks!

@nhooyr nhooyr closed this Oct 29, 2016
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