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
package wire
import (
"bytes"
"errors"
"fmt"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/utils"
"github.com/lucas-clemente/quic-go/qerr"
)
// parseHeader parses the header.
func parseHeader(b *bytes.Reader, packetSentBy protocol.Perspective) (*Header, error) {
typeByte, err := b.ReadByte()
if err != nil {
return nil, err
}
if typeByte&0x80 > 0 {
return parseLongHeader(b, packetSentBy, typeByte)
}
return parseShortHeader(b, typeByte)
}
// parse long header and version negotiation packets
func parseLongHeader(b *bytes.Reader, sentBy protocol.Perspective, typeByte byte) (*Header, error) {
connID, err := utils.BigEndian.ReadUint64(b)
if err != nil {
return nil, err
}
v, err := utils.BigEndian.ReadUint32(b)
if err != nil {
return nil, err
}
h := &Header{
ConnectionID: protocol.ConnectionID(connID),
Version: protocol.VersionNumber(v),
}
if v == 0 { // version negotiation packet
if sentBy == protocol.PerspectiveClient {
return nil, qerr.InvalidVersion
}
if b.Len() == 0 {
return nil, qerr.Error(qerr.InvalidVersionNegotiationPacket, "empty version list")
}
h.IsVersionNegotiation = true
h.SupportedVersions = make([]protocol.VersionNumber, b.Len()/4)
for i := 0; b.Len() > 0; i++ {
v, err := utils.BigEndian.ReadUint32(b)
if err != nil {
return nil, qerr.InvalidVersionNegotiationPacket
}
h.SupportedVersions[i] = protocol.VersionNumber(v)
}
return h, nil
}
h.IsLongHeader = true
pn, err := utils.BigEndian.ReadUint32(b)
if err != nil {
return nil, err
}
h.PacketNumber = protocol.PacketNumber(pn)
h.PacketNumberLen = protocol.PacketNumberLen4
h.Type = protocol.PacketType(typeByte & 0x7f)
if sentBy == protocol.PerspectiveClient && (h.Type != protocol.PacketTypeInitial && h.Type != protocol.PacketTypeHandshake && h.Type != protocol.PacketType0RTT) {
return nil, qerr.Error(qerr.InvalidPacketHeader, fmt.Sprintf("Received packet with invalid packet type: %d", h.Type))
}
if sentBy == protocol.PerspectiveServer && (h.Type != protocol.PacketTypeRetry && h.Type != protocol.PacketTypeHandshake) {
return nil, qerr.Error(qerr.InvalidPacketHeader, fmt.Sprintf("Received packet with invalid packet type: %d", h.Type))
}
return h, nil
}
func parseShortHeader(b *bytes.Reader, typeByte byte) (*Header, error) {
omitConnID := typeByte&0x40 > 0
var connID uint64
if !omitConnID {
var err error
connID, err = utils.BigEndian.ReadUint64(b)
if err != nil {
return nil, err
}
}
// bit 4 must be set, bit 5 must be unset
if typeByte&0x18 != 0x10 {
return nil, errors.New("invalid bit 4 and 5")
}
var pnLen protocol.PacketNumberLen
switch typeByte & 0x7 {
case 0x0:
pnLen = protocol.PacketNumberLen1
case 0x1:
pnLen = protocol.PacketNumberLen2
case 0x2:
pnLen = protocol.PacketNumberLen4
default:
return nil, errors.New("invalid short header type")
}
pn, err := utils.BigEndian.ReadUintN(b, uint8(pnLen))
if err != nil {
return nil, err
}
return &Header{
KeyPhase: int(typeByte&0x20) >> 5,
OmitConnectionID: omitConnID,
ConnectionID: protocol.ConnectionID(connID),
PacketNumber: protocol.PacketNumber(pn),
PacketNumberLen: pnLen,
}, nil
}
// writeHeader writes the Header.
func (h *Header) writeHeader(b *bytes.Buffer) error {
if h.IsLongHeader {
return h.writeLongHeader(b)
}
return h.writeShortHeader(b)
}
// TODO: add support for the key phase
func (h *Header) writeLongHeader(b *bytes.Buffer) error {
b.WriteByte(byte(0x80 | h.Type))
utils.BigEndian.WriteUint64(b, uint64(h.ConnectionID))
utils.BigEndian.WriteUint32(b, uint32(h.Version))
utils.BigEndian.WriteUint32(b, uint32(h.PacketNumber))
return nil
}
func (h *Header) writeShortHeader(b *bytes.Buffer) error {
typeByte := byte(0x10)
typeByte ^= byte(h.KeyPhase << 5)
if h.OmitConnectionID {
typeByte ^= 0x40
}
switch h.PacketNumberLen {
case protocol.PacketNumberLen1:
case protocol.PacketNumberLen2:
typeByte ^= 0x1
case protocol.PacketNumberLen4:
typeByte ^= 0x2
default:
return fmt.Errorf("invalid packet number length: %d", h.PacketNumberLen)
}
b.WriteByte(typeByte)
if !h.OmitConnectionID {
utils.BigEndian.WriteUint64(b, uint64(h.ConnectionID))
}
switch h.PacketNumberLen {
case protocol.PacketNumberLen1:
b.WriteByte(uint8(h.PacketNumber))
case protocol.PacketNumberLen2:
utils.BigEndian.WriteUint16(b, uint16(h.PacketNumber))
case protocol.PacketNumberLen4:
utils.BigEndian.WriteUint32(b, uint32(h.PacketNumber))
}
return nil
}
// getHeaderLength gets the length of the Header in bytes.
func (h *Header) getHeaderLength() (protocol.ByteCount, error) {
if h.IsLongHeader {
return 1 + 8 + 4 + 4, nil
}
length := protocol.ByteCount(1) // type byte
if !h.OmitConnectionID {
length += 8
}
if h.PacketNumberLen != protocol.PacketNumberLen1 && h.PacketNumberLen != protocol.PacketNumberLen2 && h.PacketNumberLen != protocol.PacketNumberLen4 {
return 0, fmt.Errorf("invalid packet number length: %d", h.PacketNumberLen)
}
length += protocol.ByteCount(h.PacketNumberLen)
return length, nil
}
func (h *Header) logHeader() {
if h.IsLongHeader {
utils.Debugf(" Long Header{Type: %s, ConnectionID: %#x, PacketNumber: %#x, Version: %s}", h.Type, h.ConnectionID, h.PacketNumber, h.Version)
} else {
connID := "(omitted)"
if !h.OmitConnectionID {
connID = fmt.Sprintf("%#x", h.ConnectionID)
}
utils.Debugf(" Short Header{ConnectionID: %s, PacketNumber: %#x, PacketNumberLen: %d, KeyPhase: %d}", connID, h.PacketNumber, h.PacketNumberLen, h.KeyPhase)
}
}