1/*
2 *
3 * Copyright 2018 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
19package grpcutil
20
21import (
22	"errors"
23	"strings"
24)
25
26// ParseMethod splits service and method from the input. It expects format
27// "/service/method".
28//
29func ParseMethod(methodName string) (service, method string, _ error) {
30	if !strings.HasPrefix(methodName, "/") {
31		return "", "", errors.New("invalid method name: should start with /")
32	}
33	methodName = methodName[1:]
34
35	pos := strings.LastIndex(methodName, "/")
36	if pos < 0 {
37		return "", "", errors.New("invalid method name: suffix /method is missing")
38	}
39	return methodName[:pos], methodName[pos+1:], nil
40}
41
42const baseContentType = "application/grpc"
43
44// ContentSubtype returns the content-subtype for the given content-type.  The
45// given content-type must be a valid content-type that starts with
46// "application/grpc". A content-subtype will follow "application/grpc" after a
47// "+" or ";". See
48// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
49// more details.
50//
51// If contentType is not a valid content-type for gRPC, the boolean
52// will be false, otherwise true. If content-type == "application/grpc",
53// "application/grpc+", or "application/grpc;", the boolean will be true,
54// but no content-subtype will be returned.
55//
56// contentType is assumed to be lowercase already.
57func ContentSubtype(contentType string) (string, bool) {
58	if contentType == baseContentType {
59		return "", true
60	}
61	if !strings.HasPrefix(contentType, baseContentType) {
62		return "", false
63	}
64	// guaranteed since != baseContentType and has baseContentType prefix
65	switch contentType[len(baseContentType)] {
66	case '+', ';':
67		// this will return true for "application/grpc+" or "application/grpc;"
68		// which the previous validContentType function tested to be valid, so we
69		// just say that no content-subtype is specified in this case
70		return contentType[len(baseContentType)+1:], true
71	default:
72		return "", false
73	}
74}
75
76// ContentType builds full content type with the given sub-type.
77//
78// contentSubtype is assumed to be lowercase
79func ContentType(contentSubtype string) string {
80	if contentSubtype == "" {
81		return baseContentType
82	}
83	return baseContentType + "+" + contentSubtype
84}
85