forked from Zilog8/hgmessage
/
sender.go
129 lines (114 loc) · 3.21 KB
/
sender.go
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
// sender
package hgmessage
import (
"bytes"
"code.google.com/p/lzma"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/gob"
"fmt"
"net"
"time"
)
//Returns the lzma-compressed bytes
func shortcompress(expanded []byte, level int) []byte {
var b bytes.Buffer
w := lzma.NewWriterSizeLevel(&b, int64(len(expanded)), level)
w.Write(expanded)
w.Close()
return b.Bytes()
}
//Encrypts (AES-GCM) a plainbytes with the provided key (128-, 192-, or 256-bit)
//Returns the resulting cipherbytes and the nonce used or an error
func shortencrypt(key, plainbytes []byte) ([]byte, []byte, error) {
b, err := aes.NewCipher(key)
if err != nil {
return nil, nil, err
}
gcm, err := cipher.NewGCM(b)
if err != nil {
return nil, nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err := rand.Read(nonce); err != nil {
return nil, nil, err
}
cipherbytes := gcm.Seal(nil, nonce, plainbytes, nil)
return cipherbytes, nonce, nil
}
//Blocking Sender:
// compressionlevel; <1 or >9 means no compression
// key; any 128-, 192-, or 256-bit key
// connection; for example: "127.0.0.1:4040"
func Send(message Message, compressionlevel int, key []byte, connection string) error {
compressed := false
messageBytes, _ := message.MarshalBinary()
if compressionlevel > 0 && compressionlevel < 10 {
compressed = true
messageBytes = shortcompress(messageBytes, compressionlevel)
}
cipherbytes, nonce, err := shortencrypt(key, messageBytes)
if err != nil {
fmt.Println("Encryption error", err)
return err
}
for err = safeSender(cipherbytes, nonce, compressed, connection); err != nil; err = safeSender(cipherbytes, nonce, compressed, connection) {
fmt.Println("Connection error", err)
}
return nil
}
func safeSender(messageBytes, nonce []byte, compressed bool, connection string) error {
defer func() {
recover()
}()
conn, err := net.Dial("tcp", connection)
if err != nil {
return err
}
encoder := gob.NewEncoder(conn)
p := &courier{Cipherbytes: messageBytes, Nonce: nonce, IsCompressed: compressed}
encoder.Encode(p)
conn.Close()
return nil
}
//Buffered channel version of Send. Pass a nil to close
func SendChannel(compressionlevel int, key []byte, connection string) (chan<- Message, error) {
conn, err := net.Dial("tcp", connection)
if err != nil {
return nil, err
}
gencoder := gob.NewEncoder(conn)
isCompressed := false
if compressionlevel > 0 && compressionlevel < 10 {
isCompressed = true
}
c := make(chan Message, 16)
go func() {
for message := <-c; message != nil; message = <-c {
messageBytes, _ := message.MarshalBinary()
if isCompressed {
messageBytes = shortcompress(messageBytes, compressionlevel)
}
cipherbytes, nonce, err := shortencrypt(key, messageBytes)
if err != nil {
fmt.Println("Encryption error", err)
}
p := &courier{Cipherbytes: cipherbytes, Nonce: nonce, IsCompressed: isCompressed}
for err1 := gencoder.Encode(p); err1 != nil; err1 = gencoder.Encode(p) {
fmt.Println("Error sending (trying again in 2 seconds):", err1)
time.Sleep(2 * time.Second)
if conn != nil {
conn.Close()
}
conn, err1 = net.Dial("tcp", connection)
if err1 == nil {
gencoder = gob.NewEncoder(conn)
}
}
}
conn.Close()
close(c)
}()
return c, nil
}