/
session.go
168 lines (146 loc) · 4.53 KB
/
session.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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
package netconf
import (
"encoding/xml"
"errors"
"io"
"strconv"
"strings"
)
// ErrCapabilitiesExchange indicates a failed NETCONF hello-exchange due to incompatible versions or invalid session ID
var ErrCapabilitiesExchange = errors.New("capabilities exchange failed")
// Client defines a transport-independent interface for NETCONF clients
type Client interface {
io.Closer
NewSession() (*Session, error)
}
// Session represents a session towards the server
type Session struct {
SessionID uint64
Capabilities map[string]string
transport io.ReadWriteCloser
newFramer func(io.Writer) io.WriteCloser
newUnframer func(io.Reader) io.ReadCloser
messageID int
}
func newSession(transport io.ReadWriteCloser) (*Session, error) {
session := Session{
transport: transport,
newFramer: newFramerV10,
newUnframer: newUnframerV10,
}
// Exchange capabilities
hello := &struct {
XMLName xml.Name `xml:"urn:ietf:params:xml:ns:netconf:base:1.0 hello"`
SessionID uint64 `xml:"session-id,omitempty"`
Capabilities []string `xml:"capabilities>capability"`
}{Capabilities: []string{CapNetconf10, CapNetconf11}}
// Send hello message
framer := session.newFramer(transport)
if err := xml.NewEncoder(framer).Encode(hello); err != nil {
return nil, err
}
if err := framer.Close(); err != nil {
return nil, err
}
// Retrieve and parse server's hello message
reader := session.NewReader()
hello.Capabilities = hello.Capabilities[:0]
if err := xml.NewDecoder(reader).Decode(&hello); err != nil {
return nil, err
} else if err := reader.Close(); err != nil {
return nil, err
}
// Check for non-0 session ID
if session.SessionID = hello.SessionID; session.SessionID == 0 {
return nil, ErrCapabilitiesExchange
}
// Parse capabilities
session.Capabilities = make(map[string]string)
for _, capability := range hello.Capabilities {
cap := strings.SplitN(capability, "?", 2)
if len(cap) > 1 {
session.Capabilities[cap[0]] = cap[1]
} else {
session.Capabilities[cap[0]] = ""
}
}
// Check for compatible version and switch framing method if necessary
if _, compatible := session.Capabilities[CapNetconf11]; compatible {
session.newFramer = newFramerV11
session.newUnframer = newUnframerV11
} else if _, compatible := session.Capabilities[CapNetconf10]; !compatible {
return nil, ErrCapabilitiesExchange
}
return &session, nil
}
// Call a NETCONF RPC and retrieve its reply
func (s *Session) Call(request interface{}, response interface{}) error {
var err error
s.messageID++
writer := s.NewWriter()
element := xml.StartElement{
Name: xml.Name{Local: "rpc", Space: "urn:ietf:params:xml:ns:netconf:base:1.0"},
Attr: []xml.Attr{{Name: xml.Name{Local: "message-id"}, Value: strconv.Itoa(s.messageID)}},
}
rpc := &struct{ Operation interface{} }{Operation: request}
if err = xml.NewEncoder(writer).EncodeElement(rpc, element); err == nil {
err = writer.Close()
}
// Read until rpc-reply (skip spurious notifications etc.)
for haveReply := false; !haveReply && err == nil && response != nil; {
reader := s.NewReader()
decoder := xml.NewDecoder(reader)
for err == nil {
var token xml.Token
token, err = decoder.Token() // Read until the XML document root
if element, ok := token.(xml.StartElement); ok {
if element.Name.Local == "rpc-reply" {
err = decoder.DecodeElement(response, &element)
haveReply = true
}
break
}
}
reader.Close()
}
return err
}
// NewReader creates a low-level reader for receiving the next NETCONF message
func (s *Session) NewReader() io.ReadCloser {
return s.newUnframer(s.transport)
}
// NewWriter creates a low-level writing for sending the next NETCONF message
func (s *Session) NewWriter() io.WriteCloser {
return s.newFramer(s.transport)
}
// Receive a message from the server, e.g. a notification
func (s *Session) Receive(response interface{}) error {
reader := s.NewReader()
err := xml.NewDecoder(reader).Decode(response)
errReader := reader.Close()
if err == nil {
err = errReader
}
return err
}
// CallSimple calls a NETCONF RPC and returns the first rpc-error or nil if there was none
func (s *Session) CallSimple(request interface{}) error {
reply := &RPCReply{}
err := s.Call(request, reply)
if err == nil && len(reply.RPCError) > 0 {
err = &reply.RPCError[0]
}
return err
}
// Close the session gracefully
func (s *Session) Close() error {
closeSession := &struct {
XMLName xml.Name `xml:"close-session"`
}{}
err := s.CallSimple(closeSession)
errTransport := s.transport.Close()
if err == nil {
err = errTransport
}
return err
}