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.
21 package passthrough
22 23 import (
24 "errors"
25 26 "google.golang.org/grpc/resolver"
27 )
28 29 const scheme = "passthrough"
30 31 type passthroughBuilder struct{}
32 33 func (*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 45 func (*passthroughBuilder) Scheme() string {
46 return scheme
47 }
48 49 type passthroughResolver struct {
50 target resolver.Target
51 cc resolver.ClientConn
52 }
53 54 func (r *passthroughResolver) start() {
55 r.cc.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: r.target.Endpoint()}}})
56 }
57 58 func (*passthroughResolver) ResolveNow(resolver.ResolveNowOptions) {}
59 60 func (*passthroughResolver) Close() {}
61 62 func init() {
63 resolver.Register(&passthroughBuilder{})
64 }
65