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73 lines
2.6 KiB
Markdown
73 lines
2.6 KiB
Markdown
# cmux: Connection Mux [](https://travis-ci.org/cockroachdb/cmux) [](https://godoc.org/github.com/cockroachdb/cmux)
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cmux is a generic Go library to multiplex connections based on their payload.
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Using cmux, you can serve gRPC, SSH, HTTPS, HTTP, Go RPC, and pretty much any
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other protocol on the same TCP listener.
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## How-To
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Simply create your main listener, create a cmux for that listener,
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and then match connections:
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```go
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// Create the main listener.
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l, err := net.Listen("tcp", ":23456")
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if err != nil {
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log.Fatal(err)
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}
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// Create a cmux.
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m := cmux.New(l)
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// Match connections in order:
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// First grpc, then HTTP, and otherwise Go RPC/TCP.
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grpcL := m.Match(cmux.HTTP2HeaderField("content-type", "application/grpc"))
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httpL := m.Match(cmux.HTTP1Fast())
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trpcL := m.Match(cmux.Any()) // Any means anything that is not yet matched.
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// Create your protocol servers.
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grpcS := grpc.NewServer()
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grpchello.RegisterGreeterServer(grpcs, &server{})
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httpS := &http.Server{
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Handler: &helloHTTP1Handler{},
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}
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trpcS := rpc.NewServer()
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s.Register(&ExampleRPCRcvr{})
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// Use the muxed listeners for your servers.
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go grpcS.Serve(grpcL)
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go httpS.Serve(httpL)
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go trpcS.Accept(trpcL)
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// Start serving!
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m.Serve()
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```
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There are [more examples on GoDoc](https://godoc.org/github.com/cockroachdb/cmux#pkg-examples).
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## Performance
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Since we are only matching the very first bytes of a connection, the
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performance overhead on long-lived connections (i.e., RPCs and pipelined HTTP
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streams) is negligible.
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## Limitations
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* *TLS*: `net/http` uses a [type assertion](https://github.com/golang/go/issues/14221)
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to identify TLS connections; since cmux's lookahead-implementing connection
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wraps the underlying TLS connection, this type assertion fails. This means you
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can serve HTTPS using cmux but `http.Request.TLS` will not be set in your
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handlers. If you are able to wrap TLS around cmux, you can work around this
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limitation. See https://github.com/cockroachdb/cockroach/commit/83caba2 for an
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example of this approach.
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* *Different Protocols on The Same Connection*: `cmux` matches the connection
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when it's accepted. For example, one connection can be either gRPC or REST, but
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not both. That is, we assume that a client connection is either used for gRPC
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or REST.
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# Copyright and License
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Copyright 2016 The CMux Authors. All rights reserved.
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See [CONTRIBUTORS](https://github.com/cockroachdb/cmux/blob/master/CONTRIBUTORS)
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for the CMux Authors. Code is released under
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[the Apache 2 license](https://github.com/cockroachdb/cmux/blob/master/LICENSE).
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