Repository navigation
Expand file tree
/
Copy pathserver.go
More file actions
258 lines (210 loc) · 6.44 KB
/
Copy pathserver.go
File metadata and controls
258 lines (210 loc) · 6.44 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/*
* Minio Cloud Storage, (C) 2018 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package rpc
import (
"bytes"
"encoding/gob"
"errors"
"fmt"
"net/http"
"reflect"
"strings"
"unicode"
"unicode/utf8"
)
// Authenticator - validator of first argument of any RPC call.
type Authenticator interface {
// Method to validate first argument of any RPC call.
Authenticate() error
}
// reflect.Type of error interface.
var errorType = reflect.TypeOf((*error)(nil)).Elem()
// reflect.Type of Authenticator interface.
var authenticatorType = reflect.TypeOf((*Authenticator)(nil)).Elem()
var bufPool = NewPool()
func gobEncodeBuf(e interface{}, buf *bytes.Buffer) error {
return gob.NewEncoder(buf).Encode(e)
}
func gobDecode(data []byte, e interface{}) error {
return gob.NewDecoder(bytes.NewReader(data)).Decode(e)
}
// Returns whether given type is exported or builin type or not.
func isExportedOrBuiltinType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
rune, _ := utf8.DecodeRuneInString(t.Name())
return unicode.IsUpper(rune) || t.PkgPath() == ""
}
// Makes method name map from given type.
func getMethodMap(receiverType reflect.Type) map[string]reflect.Method {
methodMap := make(map[string]reflect.Method)
for i := 0; i < recei
8000
verType.NumMethod(); i++ {
// Method.PkgPath is empty for this package.
method := receiverType.Method(i)
// Methods must have three arguments (receiver, args, reply)
if method.Type.NumIn() != 3 {
continue
}
// First argument must be exported.
if !isExportedOrBuiltinType(method.Type.In(1)) {
continue
}
// First argument must be Authenticator.
if !method.Type.In(1).Implements(authenticatorType) {
continue
}
// Second argument must be exported or builtin type.
if !isExportedOrBuiltinType(method.Type.In(2)) {
continue
}
// Second argument must be a pointer.
if method.Type.In(2).Kind() != reflect.Ptr {
continue
}
// Method must return one value.
if method.Type.NumOut() != 1 {
continue
}
// The return type of the method must be error.
if method.Type.Out(0) != errorType {
continue
}
methodMap[method.Name] = method
}
return methodMap
}
// Server - HTTP based RPC server.
type Server struct {
serviceName string
receiverValue reflect.Value
methodMap map[string]reflect.Method
}
// RegisterName - registers receiver with given name to handle RPC requests.
func (server *Server) RegisterName(name string, receiver interface{}) error {
server.serviceName = name
server.receiverValue = reflect.ValueOf(receiver)
if !reflect.Indirect(server.receiverValue).IsValid() {
return fmt.Errorf("nil receiver")
}
receiverName := reflect.Indirect(server.receiverValue).Type().Name()
receiverType := reflect.TypeOf(receiver)
server.methodMap = getMethodMap(receiverType)
if len(server.methodMap) == 0 {
str := "rpc.Register: type " + receiverName + " has no exported methods of suitable type"
// To help the user, see if a pointer receiver would work.
if len(getMethodMap(reflect.PtrTo(receiverType))) != 0 {
str += " (hint: pass a pointer to value of that type)"
}
return errors.New(str)
}
return nil
}
// call - call service method in receiver.
func (server *Server) call(serviceMethod string, argBytes []byte, replyBytes *bytes.Buffer) (err error) {
tokens := strings.SplitN(serviceMethod, ".", 2)
if len(tokens) != 2 {
return fmt.Errorf("invalid service/method request ill-formed %v", serviceMethod)
}
serviceName := tokens[0]
if serviceName != server.serviceName {
return fmt.Errorf("can't find service %v", serviceName)
}
methodName := tokens[1]
method, found := server.methodMap[methodName]
if !found {
return fmt.Errorf("can't find method %v", methodName)
}
var argv reflect.Value
// Decode the argument value.
argIsValue := false // if true, need to indirect before calling.
if method.Type.In(1).Kind() == reflect.Ptr {
argv = reflect.New(method.Type.In(1).Elem())
} else {
argv = reflect.New(method.Type.In(1))
argIsValue = true
}
if err = gobDecode(argBytes, argv.Interface()); err != nil {
return err
}
if argIsValue {
argv = argv.Elem()
}
// call Authenticate() method.
authMethod, ok := method.Type.In(1).MethodByName("Authenticate")
if !ok {
panic("Authenticate() method not found. This should not happen.")
}
returnValues := authMethod.Func.Call([]reflect.Value{argv})
errInter := returnValues[0].Interface()
if errInter != nil {
err = errInter.(error)
}
if err != nil {
return err
}
replyv := reflect.New(method.Type.In(2).Elem())
switch method.Type.In(2).Elem().Kind() {
case reflect.Map:
replyv.Elem().Set(reflect.MakeMap(method.Type.In(2).Elem()))
case reflect.Slice:
replyv.Elem().Set(reflect.MakeSlice(method.Type.In(2).Elem(), 0, 0))
}
returnValues = method.Func.Call([]reflect.Value{server.receiverValue, argv, replyv})
errInter = returnValues[0].Interface()
if errInter != nil {
err = errInter.(error)
}
if err != nil {
return err
}
return gobEncodeBuf(replyv.Interface(), replyBytes)
}
// CallRequest - RPC call request parameters.
type CallRequest struct {
Method string
ArgBytes []byte
}
// CallResponse - RPC call response parameters.
type CallResponse struct {
Error string
ReplyBytes []byte
}
// ServeHTTP - handles RPC on HTTP request.
func (server *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if req.Method != http.MethodPost {
w.WriteHeader(http.StatusMethodNotAllowed)
return
}
var callRequest CallRequest
if err := gob.NewDecoder(req.Body).Decode(&callRequest); err != nil {
w.WriteHeader(http.StatusBadRequest)
return
}
callResponse := CallResponse{}
buf := bufPool.Get()
defer bufPool.Put(buf)
if err := server.call(callRequest.Method, callRequest.ArgBytes, buf); err != nil {
callResponse.Error = err.Error()
}
callResponse.ReplyBytes = buf.Bytes()
gob.NewEncoder(w).Encode(callResponse)
w.(http.Flusher).Flush()
}
// NewServer - returns new RPC server.
func NewServer() *Server {
return &Server{}
}