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
|
// Copyright 2015 Google Inc. All rights reserved.
//
// 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 marbl
import (
"bufio"
"encoding/binary"
"fmt"
"io"
)
// Header is either an HTTP header or meta-data pertaining to the request or response.
type Header struct {
ID string
MessageType MessageType
Name string
Value string
}
// String returns the contents of a Header frame in a format appropriate for debugging and runtime logging.
func (hf Header) String() string {
return fmt.Sprintf("ID=%s; Type=%d; Name=%s; Value=%s", hf.ID, hf.MessageType, hf.Name, hf.Value)
}
// FrameType returns HeaderFrame
func (hf Header) FrameType() FrameType {
return HeaderFrame
}
// Data is the payload (body) of the request or response.
type Data struct {
ID string
MessageType MessageType
Index uint32
Terminal bool
Data []byte
}
// String returns the contents of a Data frame in a format appropriate for debugging and runtime logging. The
// contents of the data content slice (df.Data) is not printed, instead the length of Data is printed.
func (df Data) String() string {
return fmt.Sprintf("ID=%s; Type=%d; Index=%d; Terminal=%t; Data length=%d",
df.ID, df.MessageType, df.Index, df.Terminal, len(df.Data))
}
// FrameType returns DataFrame
func (df Data) FrameType() FrameType {
return DataFrame
}
// Frame describes the interface for a frame (either Data or Header).
type Frame interface {
String() string
FrameType() FrameType
}
// Reader wraps a buffered Reader that reads from the io.Reader and emits Frames.
type Reader struct {
r io.Reader
}
// NewReader returns a Reader initialized with a buffered reader.
func NewReader(r io.Reader) *Reader {
return &Reader{
r: bufio.NewReader(r),
}
}
// ReadFrame reads from r, determines the FrameType, and returns either a Header or Data and an error.
func (r *Reader) ReadFrame() (Frame, error) {
fh := make([]byte, 10)
if _, err := io.ReadFull(r.r, fh); err != nil {
return nil, err
}
switch FrameType(fh[0]) {
case HeaderFrame:
hf := Header{
ID: string(fh[2:]),
MessageType: MessageType(fh[1]),
}
lens := make([]byte, 8)
if _, err := io.ReadFull(r.r, lens); err != nil {
return nil, err
}
nl := binary.BigEndian.Uint32(lens[:4])
vl := binary.BigEndian.Uint32(lens[4:])
nv := make([]byte, int(nl+vl))
if _, err := io.ReadFull(r.r, nv); err != nil {
return nil, err
}
hf.Name = string(nv[:nl])
hf.Value = string(nv[nl:])
return hf, nil
case DataFrame:
df := Data{
ID: string(fh[2:]),
MessageType: MessageType(fh[1]),
}
// Reading 9 bytes:
// 4 bytes index
// 1 byte terminal
// 4 bytes data length
desc := make([]byte, 9)
if _, err := io.ReadFull(r.r, desc); err != nil {
return nil, err
}
df.Index = binary.BigEndian.Uint32(desc[:4])
df.Terminal = desc[4] == 1
dl := binary.BigEndian.Uint32(desc[5:])
data := make([]byte, int(dl))
if _, err := io.ReadFull(r.r, data); err != nil {
return nil, err
}
df.Data = data
return df, nil
default:
return nil, fmt.Errorf("marbl: unknown type of frame")
}
}
|
