gateway_handler.go

/*
 *Copyright (c) 2022, kaydxh
 *
 *Permission is hereby granted, free of charge, to any person obtaining a copy
 *of this software and associated documentation files (the "Software"), to deal
 *in the Software without restriction, including without limitation the rights
 *to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *copies of the Software, and to permit persons to whom the Software is
 *furnished to do so, subject to the following conditions:
 *
 *The above copyright notice and this permission notice shall be included in all
 *copies or substantial portions of the Software.
 *
 *THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 *SOFTWARE.
 */
package grpcgateway

import (
	"context"
	"net/http"
	"strings"

	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
	"golang.org/x/net/http2"
	"golang.org/x/net/http2/h2c"
	"google.golang.org/grpc"
)

type GRPCHandler interface {
	Register(srv *grpc.Server)
}

type GRPCHandlerFunc func(srv *grpc.Server)

func (h GRPCHandlerFunc) Register(srv *grpc.Server) {
	h(srv)
}

type HTTPHandler interface {
	Register(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) error
}

type HTTPHandlerFunc func(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) error

// ServeMux is a request multiplexer for grpc-gateway.
// It matches http requests to patterns and invokes the corresponding handler.

// grpc.DialOption configures how we set up the connection. grpc client->
// grpc server

func (h HTTPHandlerFunc) Register(
	ctx context.Context,
	mux *runtime.ServeMux,
	endpoint string,
	opts []grpc.DialOption,
) error {
	return h(ctx, mux, endpoint, opts)
}

// grpcHandlerFunc returns an http.Handler that delegates to grpcServer on incoming gRPC
// connections or otherHandler otherwise. Copied from cockroachdb.
func grpcHandlerFunc(grpcServer *grpc.Server, otherHandler http.Handler) http.Handler {
	return h2c.NewHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// TODO(tamird): point to merged gRPC code rather than a PR.
		// This is a partial recreation of gRPC's internal checks https://github.com/grpc/grpc-go/pull/514/files#diff-95e9a25b738459a2d3030e1e6fa2a718R61
		if r.ProtoMajor == 2 && strings.Contains(r.Header.Get("Content-Type"), "application/grpc") {
			grpcServer.ServeHTTP(w, r)
		} else {
			otherHandler.ServeHTTP(w, r)
		}

	}), &http2.Server{})
}