-
Notifications
You must be signed in to change notification settings - Fork 1
/
msgcfheaders.go
153 lines (142 loc) · 5.12 KB
/
msgcfheaders.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
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
package wire
import (
"fmt"
"io"
"github.com/cybriq/p9/pkg/chainhash"
)
const (
// MaxCFHeaderPayload is the maximum byte size of a committed filter header.
MaxCFHeaderPayload = chainhash.HashSize
// MaxCFHeadersPerMsg is the maximum number of committed filter headers that can be in a single bitcoin cfheaders message.
MaxCFHeadersPerMsg = 2000
)
// MsgCFHeaders implements the Message interface and represents a bitcoin cfheaders message. It is used to deliver
// committed filter header information in response to a getcfheaders message (MsgGetCFHeaders). The maximum number of
// committed filter headers per message is currently 2000. See MsgGetCFHeaders for details on requesting the headers.
type MsgCFHeaders struct {
FilterType FilterType
StopHash chainhash.Hash
PrevFilterHeader chainhash.Hash
FilterHashes []*chainhash.Hash
}
// AddCFHash adds a new filter hash to the message.
func (msg *MsgCFHeaders) AddCFHash(hash *chainhash.Hash) (e error) {
if len(msg.FilterHashes)+1 > MaxCFHeadersPerMsg {
str := fmt.Sprintf(
"too many block headers in message [max %v]",
MaxBlockHeadersPerMsg,
)
return messageError("MsgCFHeaders.AddCFHash", str)
}
msg.FilterHashes = append(msg.FilterHashes, hash)
return nil
}
// BtcDecode decodes r using the bitcoin protocol encoding into the receiver. This is part of the Message interface
// implementation.
func (msg *MsgCFHeaders) BtcDecode(
r io.Reader, pver uint32, _ MessageEncoding,
) (e error) {
// Read filter type
if e = readElement(r, &msg.FilterType); E.Chk(e) {
return
}
// Read stop hash
if e = readElement(r, &msg.StopHash); E.Chk(e) {
return
}
// Read prev filter header
if e = readElement(r, &msg.PrevFilterHeader); E.Chk(e) {
return
}
// Read number of filter headers
var count uint64
if count, e = ReadVarInt(r, pver); E.Chk(e) {
return
}
// Limit to max committed filter headers per message.
if count > MaxCFHeadersPerMsg {
str := fmt.Sprintf(
"too many committed filter headers for "+
"message [count %v, max %v]", count,
MaxBlockHeadersPerMsg,
)
return messageError("MsgCFHeaders.BtcDecode", str)
}
// Create a contiguous slice of hashes to deserialize into in order to reduce the number of allocations.
msg.FilterHashes = make([]*chainhash.Hash, 0, count)
for i := uint64(0); i < count; i++ {
var cfh chainhash.Hash
if e = readElement(r, &cfh); E.Chk(e) {
return
}
if e = msg.AddCFHash(&cfh); E.Chk(e) {
}
}
return
}
// BtcEncode encodes the receiver to w using the bitcoin protocol encoding. This is part of the Message interface
// implementation.
func (msg *MsgCFHeaders) BtcEncode(
w io.Writer, pver uint32, _ MessageEncoding,
) (e error) {
// Write filter type
if e = writeElement(w, msg.FilterType); E.Chk(e) {
return
}
// Write stop hash
if e = writeElement(w, msg.StopHash); E.Chk(e) {
return
}
// Write prev filter header
if e = writeElement(w, msg.PrevFilterHeader); E.Chk(e) {
return
}
// Limit to max committed headers per message.
count := len(msg.FilterHashes)
if count > MaxCFHeadersPerMsg {
str := fmt.Sprintf(
"too many committed filter headers for "+
"message [count %v, max %v]", count,
MaxBlockHeadersPerMsg,
)
return messageError("MsgCFHeaders.BtcEncode", str)
}
if e = WriteVarInt(w, pver, uint64(count)); E.Chk(e) {
return
}
for _, cfh := range msg.FilterHashes {
if e = writeElement(w, cfh); E.Chk(e) {
return
}
}
return
}
// Deserialize decodes a filter header from r into the receiver using a format that is suitable for long-term storage
// such as a database. This function differs from BtcDecode in that BtcDecode decodes from the bitcoin wire protocol as
// it was sent across the network. The wire encoding can technically differ depending on the protocol version and
// doesn't even really need to match the format of a stored filter header at all. As of the time this comment was
// written, the encoded filter header is the same in both instances, but there is a distinct difference and separating
// the two allows the API to be flexible enough to deal with changes.
func (msg *MsgCFHeaders) Deserialize(r io.Reader) (e error) {
// At the current time, there is no difference between the wire encoding and the stable long-term storage format. As
// a result, make use of BtcDecode.
return msg.BtcDecode(r, 0, BaseEncoding)
}
// Command returns the protocol command string for the message. This is part of the Message interface implementation.
func (msg *MsgCFHeaders) Command() string {
return CmdCFHeaders
}
// MaxPayloadLength returns the maximum length the payload can be for the receiver. This is part of the Message
// interface implementation.
func (msg *MsgCFHeaders) MaxPayloadLength(pver uint32) uint32 {
// Hash size + filter type + num headers (varInt) + (header size * max headers).
return 1 + chainhash.HashSize + chainhash.HashSize + MaxVarIntPayload +
(MaxCFHeaderPayload * MaxCFHeadersPerMsg)
}
// NewMsgCFHeaders returns a new bitcoin cfheaders message that conforms to the Message interface. See MsgCFHeaders for
// details.
func NewMsgCFHeaders() *MsgCFHeaders {
return &MsgCFHeaders{
FilterHashes: make([]*chainhash.Hash, 0, MaxCFHeadersPerMsg),
}
}