go-xmpp/component.go
2018-01-12 19:08:47 +01:00

103 lines
2.7 KiB
Go

package xmpp
import (
"crypto/sha1"
"encoding/hex"
"encoding/xml"
"errors"
"fmt"
"io"
"net"
"time"
)
const componentStreamOpen = "<?xml version='1.0'?><stream:stream to='%s' xmlns='%s' xmlns:stream='%s'>"
// Component implements an XMPP extension allowing to extend XMPP server
// using external components. Component specifications are defined
// in XEP-0114, XEP-0355 and XEP-0356.
type Component struct {
Host string
Secret string
// TCP level connection
conn net.Conn
// read / write
socketProxy io.ReadWriter // TODO
decoder *xml.Decoder
}
// handshake generates an authentication token based on StreamID and shared secret.
func (c *Component) handshake(streamId string) string {
// 1. Concatenate the Stream ID received from the server with the shared secret.
concatStr := streamId + c.Secret
// 2. Hash the concatenated string according to the SHA1 algorithm, i.e., SHA1( concat (sid, password)).
h := sha1.New()
h.Write([]byte(concatStr))
hash := h.Sum(nil)
// 3. Ensure that the hash output is in hexadecimal format, not binary or base64.
// 4. Convert the hash output to all lowercase characters.
encodedStr := hex.EncodeToString(hash)
return encodedStr
}
// TODO Helper to prepare connection string
func (c *Component) Connect(connStr string) error {
var conn net.Conn
var err error
if conn, err = net.DialTimeout("tcp", connStr, time.Duration(5)*time.Second); err != nil {
return err
}
c.conn = conn
// 1. Send stream open tag
if _, err := fmt.Fprintf(conn, componentStreamOpen, c.Host, NSComponent, NSStream); err != nil {
return errors.New("cannot send stream open " + err.Error())
}
c.decoder = xml.NewDecoder(conn)
// 2. Initialize xml decoder and extract streamID from reply
streamId, err := initDecoder(c.decoder)
if err != nil {
return errors.New("cannot init decoder " + err.Error())
}
// 3. Authentication
if _, err := fmt.Fprintf(conn, "<handshake>%s</handshake>", c.handshake(streamId)); err != nil {
return errors.New("cannot send handshake " + err.Error())
}
// 4. Check server response for authentication
name, val, err := next(c.decoder)
if err != nil {
return err
}
switch v := val.(type) {
case *StreamError:
return errors.New("handshake failed " + v.Error.Local)
case *Handshake:
return nil
default:
return errors.New("unexpected packet, got " + name.Local + " in " + name.Space)
}
panic("unreachable")
}
// ReadPacket reads next incoming XMPP packet
// TODO use defined interface Packet
func (c *Component) ReadPacket() (xml.Name, interface{}, error) {
return next(c.decoder)
}
// ============================================================================
// XMPP packets struct
type Handshake struct {
XMLName xml.Name `xml:"jabber:component:accept handshake"`
}