1/*
 2 *
 3 * Copyright 2017 gRPC authors.
 4 *
 5 * Licensed under the Apache License, Version 2.0 (the "License");
 6 * you may not use this file except in compliance with the License.
 7 * You may obtain a copy of the License at
 8 *
 9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19// Package passthrough implements a pass-through resolver. It sends the target
20// name without scheme back to gRPC as resolved address.
21package passthrough
22
23import (
24	"errors"
25
26	"google.golang.org/grpc/resolver"
27)
28
29const scheme = "passthrough"
30
31type passthroughBuilder struct{}
32
33func (*passthroughBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
34	if target.Endpoint() == "" && opts.Dialer == nil {
35		return nil, errors.New("passthrough: received empty target in Build()")
36	}
37	r := &passthroughResolver{
38		target: target,
39		cc:     cc,
40	}
41	r.start()
42	return r, nil
43}
44
45func (*passthroughBuilder) Scheme() string {
46	return scheme
47}
48
49type passthroughResolver struct {
50	target resolver.Target
51	cc     resolver.ClientConn
52}
53
54func (r *passthroughResolver) start() {
55	r.cc.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: r.target.Endpoint()}}})
56}
57
58func (*passthroughResolver) ResolveNow(resolver.ResolveNowOptions) {}
59
60func (*passthroughResolver) Close() {}
61
62func init() {
63	resolver.Register(&passthroughBuilder{})
64}