<invalid gRPC request method "PRI">, when happend grpc and http use sample port about grpc-go HOT 2 CLOSED

这里可以使用 x/net 中的 h2c 替代

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Based on https://webconcepts.info/concepts/http-method/PRI:

HTTP Request Method: PRI
This method is never used by an actual client. This method will appear to be used when an HTTP/1.1 server or intermediary attempts to parse an HTTP/2 connection preface.

It looks like the http server from the standard library is trying to parse an http2 packet from a gRPC client as an http1.1 packet. The docstring of the gRPC ServeHttp method mentions the following:

The provided HTTP request must have arrived on an HTTP/2 connection. When using the Go standard library's server, practically this means that the Request must also have arrived over TLS.

It could mean that the postman client negotiated http1.1 with the go http server during the handshake, but then started using http2 for sending gRPC requests.

Can you use tls and see if the problem is resolved? When configuring the tls Config for the server, set the NextProtos field:

TLSConfig: &tls.Config{
    // Other configs.
    NextProtos: []string{"h2"}, // Only advertise HTTP/2 support
},

When the http connection is established after the TLS handshake, both server and client should be using http/2.

Example of configuring TLS:

1. https://github.com/grpc/grpc-go/tree/master/examples/features/encryption
2. https://github.com/grpc/grpc-go/tree/master/examples/route_guide
3. Script that is used to generate the certs for examples: https://github.com/grpc/grpc-go/blob/master/testdata/x509/create.sh

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