go-xmpp/component.go

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package xmpp
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import (
"crypto/sha1"
"encoding/hex"
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"encoding/xml"
"errors"
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"fmt"
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"io"
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"net"
"time"
"gosrc.io/xmpp/stanza"
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)
const componentStreamOpen = "<?xml version='1.0'?><stream:stream to='%s' xmlns='%s' xmlns:stream='%s'>"
type ComponentOptions struct {
// =================================
// Component Connection Info
// Domain is the XMPP server subdomain that the component will handle
Domain string
// Secret is the "password" used by the XMPP server to secure component access
Secret string
// Address is the XMPP Host and port to connect to. Host is of
// the form 'serverhost:port' i.e "localhost:8888"
Address string
// =================================
// Component discovery
// Component human readable name, that will be shown in XMPP discovery
Name string
// Typical categories and types: https://xmpp.org/registrar/disco-categories.html
Category string
Type string
// =================================
// Communication with developer client / StreamManager
// Track and broadcast connection state
EventManager
}
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// 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 {
ComponentOptions
router *Router
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// TCP level connection
conn net.Conn
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// read / write
socketProxy io.ReadWriter // TODO
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decoder *xml.Decoder
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}
func NewComponent(opts ComponentOptions, r *Router) (*Component, error) {
c := Component{ComponentOptions: opts, router: r}
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return &c, nil
}
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// Connect triggers component connection to XMPP server component port.
// TODO: Failed handshake should be a permanent error
func (c *Component) Connect() error {
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var state SMState
return c.Resume(state)
}
func (c *Component) Resume(sm SMState) error {
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var conn net.Conn
var err error
if conn, err = net.DialTimeout("tcp", c.Address, time.Duration(5)*time.Second); err != nil {
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return err
}
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c.conn = conn
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c.updateState(StateConnected)
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// 1. Send stream open tag
if _, err := fmt.Fprintf(conn, componentStreamOpen, c.Domain, stanza.NSComponent, stanza.NSStream); err != nil {
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c.updateState(StateStreamError)
return NewConnError(errors.New("cannot send stream open "+err.Error()), false)
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}
c.decoder = xml.NewDecoder(conn)
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// 2. Initialize xml decoder and extract streamID from reply
streamId, err := stanza.InitStream(c.decoder)
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if err != nil {
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c.updateState(StateStreamError)
return NewConnError(errors.New("cannot init decoder "+err.Error()), false)
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}
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// 3. Authentication
if _, err := fmt.Fprintf(conn, "<handshake>%s</handshake>", c.handshake(streamId)); err != nil {
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c.updateState(StateStreamError)
return NewConnError(errors.New("cannot send handshake "+err.Error()), false)
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}
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// 4. Check server response for authentication
val, err := stanza.NextPacket(c.decoder)
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if err != nil {
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c.updateState(StateDisconnected)
return NewConnError(err, true)
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}
switch v := val.(type) {
case stanza.StreamError:
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c.streamError("conflict", "no auth loop")
return NewConnError(errors.New("handshake failed "+v.Error.Local), true)
case stanza.Handshake:
// Start the receiver go routine
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c.updateState(StateSessionEstablished)
go c.recv()
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return nil
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default:
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c.updateState(StateStreamError)
return NewConnError(errors.New("expecting handshake result, got "+v.Name()), true)
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}
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}
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func (c *Component) Disconnect() {
_ = c.SendRaw("</stream:stream>")
// TODO: Add a way to wait for stream close acknowledgement from the server for clean disconnect
conn := c.conn
if conn != nil {
_ = conn.Close()
}
}
func (c *Component) SetHandler(handler EventHandler) {
c.Handler = handler
}
// Receiver Go routine receiver
func (c *Component) recv() (err error) {
for {
val, err := stanza.NextPacket(c.decoder)
if err != nil {
c.updateState(StateDisconnected)
return err
}
// Handle stream errors
switch p := val.(type) {
case stanza.StreamError:
c.router.route(c, val)
c.streamError(p.Error.Local, p.Text)
return errors.New("stream error: " + p.Error.Local)
}
c.router.route(c, val)
}
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}
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// Send marshalls XMPP stanza and sends it to the server.
func (c *Component) Send(packet stanza.Packet) error {
conn := c.conn
if conn == nil {
return errors.New("component is not connected")
}
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data, err := xml.Marshal(packet)
if err != nil {
return errors.New("cannot marshal packet " + err.Error())
}
if _, err := fmt.Fprintf(conn, string(data)); err != nil {
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return errors.New("cannot send packet " + err.Error())
}
return nil
}
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// SendRaw sends an XMPP stanza as a string to the server.
// It can be invalid XML or XMPP content. In that case, the server will
// disconnect the component. It is up to the user of this method to
// carefully craft the XML content to produce valid XMPP.
func (c *Component) SendRaw(packet string) error {
conn := c.conn
if conn == nil {
return errors.New("component is not connected")
}
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var err error
_, err = fmt.Fprintf(c.conn, packet)
return err
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}
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// 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
}
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/*
TODO: Add support for discovery management directly in component
TODO: Support multiple identities on disco info
TODO: Support returning features on disco info
*/