forked from rainhq/signalr
/
conn.go
351 lines (287 loc) · 7.92 KB
/
conn.go
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package signalr
import (
"context"
"crypto/rand"
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"math/big"
"net/http"
"net/http/cookiejar"
"net/url"
"sync"
"github.com/cenkalti/backoff/v4"
)
// Conn represents a SignalR connection
type Conn struct {
rmtx, wmtx sync.Mutex
client *http.Client
dialer WebsocketDialer
conn WebsocketConn
endpoint string
config *config
state *State
}
// State represents a SignalR connection state
type State struct {
ConnectionData string
ConnectionID string
ConnectionToken string
GroupsToken string
MessageID string
Protocol string
}
// Dial connects to Signalr endpoint
func Dial(ctx context.Context, endpoint, cdata string, opts ...DialOpt) (*Conn, error) {
cfg := newDefaultConfig()
for _, opt := range opts {
opt(&cfg)
}
client := cfg.Client
if client.Jar == nil {
jar, err := cookiejar.New(nil)
if err != nil {
return nil, err
}
client.Jar = jar
}
state := State{
ConnectionData: cdata,
Protocol: cfg.Protocol,
}
if err := negotiate(ctx, client, endpoint, cfg.Headers, &state, cfg.NegotiateBackoff()); err != nil {
return nil, &NegotiateError{cause: err}
}
dialer := cfg.Dialer(client)
conn, err := connect(ctx, dialer, endpoint, "connect", cfg.Headers, &state, cfg.ConnectBackoff())
if err != nil {
return nil, &ConnectError{cause: err}
}
err = start(ctx, client, conn, endpoint, cfg.Headers, &state, cfg.StartBackoff())
if err != nil {
return nil, &StartError{cause: err}
}
return &Conn{
client: client,
dialer: dialer,
conn: conn,
endpoint: endpoint,
config: &cfg,
state: &state,
}, nil
}
func (c *Conn) State() *State {
c.rmtx.Lock()
state := *c.state
c.rmtx.Unlock()
return &state
}
// ReadMessage reads single message from websocket
func (c *Conn) ReadMessage(ctx context.Context, msg *Message) error {
c.rmtx.Lock()
defer c.rmtx.Unlock()
err := readMessage(ctx, c.conn, msg, c.state)
if IsCloseError(err, 1000, 1001, 1006) {
dctx, cancel := context.WithTimeout(ctx, c.config.MaxReconnectDuration)
defer cancel()
var conn WebsocketConn
conn, err = connect(dctx, c.dialer, c.endpoint, "reconnect", c.config.Headers, c.state, c.config.ReconnectBackoff())
if err != nil {
return &ConnectError{cause: err}
}
c.conn = conn
// read message again
err = readMessage(ctx, conn, msg, c.state)
}
if err != nil {
return &ReadError{cause: err}
}
return nil
}
// Send sends a message to the websocket connection.
func (c *Conn) WriteMessage(ctx context.Context, msg ClientMsg) error {
c.wmtx.Lock()
defer c.wmtx.Unlock()
data, err := json.Marshal(msg)
if err != nil {
return &WriteError{cause: err}
}
if err := c.conn.WriteMessage(ctx, textMessage, data); err != nil {
return &WriteError{cause: err}
}
return nil
}
// Close closes underlying websocket connection
func (c *Conn) Close() error {
return c.conn.Close()
}
// negotiate implements the negotiate step of the SignalR connection sequence.
func negotiate(ctx context.Context, client *http.Client, endpoint string, headers http.Header, state *State, bo backoff.BackOff) error {
// Reset Token
state.ConnectionToken = ""
// Make a "negotiate" URL.
endpoint, err := makeURL(endpoint, "negotiate", state)
if err != nil {
return err
}
return backoff.Retry(func() error {
req, err := prepareRequest(ctx, endpoint, headers)
if err != nil {
return fmt.Errorf("failed to prepare request: %w", err)
}
// Perform the request.
httpRes, err := client.Do(req)
if err != nil {
return fmt.Errorf("request failed: %w", err)
}
defer httpRes.Body.Close()
if httpRes.StatusCode != http.StatusOK {
return fmt.Errorf("request failed: %s", httpRes.Status)
}
data, err := ioutil.ReadAll(httpRes.Body)
if err != nil {
return fmt.Errorf("read failed: %w", err)
}
var res negotiateResponse
if err := json.Unmarshal(data, &res); err != nil {
return err
}
// Set the connection token and ID.
state.ConnectionToken = res.ConnectionToken
state.ConnectionID = res.ConnectionID
// Update the protocol version.
state.Protocol = res.ProtocolVersion
return nil
}, backoff.WithContext(bo, ctx))
}
// connect implements the connect step of the SignalR connection sequence.
func connect(ctx context.Context, dialer WebsocketDialer, endpoint, command string, headers http.Header, state *State, bo backoff.BackOff) (WebsocketConn, error) {
// Example connect URL:
// https://socket.bittrex.com/signalr/connect?
// transport=webSockets&
// clientProtocol=1.5&
// connectionToken=<token>&
// connectionData=%5B%7B%22name%22%3A%22corehub%22%7D%5D&
// tid=5
// -> returns connection ID. (e.g.: d-F2577E41-B,0|If60z,0|If600,1)
endpoint, err := makeURL(endpoint, command, state)
if err != nil {
return nil, err
}
var conn WebsocketConn
err = backoff.Retry(func() error {
var (
status int
err error
)
conn, status, err = dialer.Dial(ctx, endpoint, headers)
if err != nil {
return &DialError{status: status, cause: err}
}
return nil
}, backoff.WithContext(bo, ctx))
return conn, err
}
// Start implements the start step of the SignalR connection sequence.
func start(ctx context.Context, client *http.Client, conn WebsocketConn, endpoint string, headers http.Header, state *State, bo backoff.BackOff) error {
endpoint, err := makeURL(endpoint, "start", state)
if err != nil {
return err
}
req, err := prepareRequest(ctx, endpoint, headers)
if err != nil {
return fmt.Errorf("failed to prepare request: %w", err)
}
// Perform the request in a retry loop.
return backoff.Retry(func() error {
httpRes, err := client.Do(req)
if err != nil {
return fmt.Errorf("request failed: %w", err)
}
defer httpRes.Body.Close()
data, err := ioutil.ReadAll(httpRes.Body)
if err != nil {
return fmt.Errorf("read failed: %w", err)
}
var res startResponse
if err := json.Unmarshal(data, &res); err != nil {
return err
}
if res.Response != "started" {
return &InvalidStartResponseError{actual: res.Response}
}
var msg Message
if err := readMessage(ctx, conn, &msg, state); err != nil {
return &ReadError{cause: err}
}
if msg.Status != statusStarted {
return &InvalidInitMessageError{actual: msg.Status}
}
return nil
}, backoff.WithContext(bo, ctx))
}
func makeURL(endpoint, command string, state *State) (string, error) {
u, err := url.Parse(endpoint)
if err != nil {
return "", err
}
if u.Scheme != "http" && u.Scheme != "https" {
return "", &url.Error{
Op: "Get",
URL: endpoint,
Err: errors.New("unsupported scheme"),
}
}
query := u.Query()
query.Set("connectionData", state.ConnectionData)
query.Set("clientProtocol", state.Protocol)
// Set the connectionToken.
if state.ConnectionToken != "" {
query.Set("connectionToken", state.ConnectionToken)
}
switch command {
case "negotiate":
u.Path += "/negotiate"
case "connect":
connectURL(u, query)
u.Path += "/connect"
case "reconnect":
connectURL(u, query)
if groupsToken := state.GroupsToken; groupsToken != "" {
query.Set("groupsToken", groupsToken)
}
if messageID := state.MessageID; messageID != "" {
query.Set("messageId", messageID)
}
u.Path += "/reconnect"
case "start":
query.Set("transport", "webSockets")
u.Path += "/start"
}
// Set the parameters.
u.RawQuery = query.Encode()
return u.String(), nil
}
func connectURL(u *url.URL, query url.Values) {
switch {
case u.Scheme == "https":
u.Scheme = "wss"
case u.Scheme == "http":
u.Scheme = "ws"
}
query.Set("transport", "webSockets")
tid, _ := rand.Int(rand.Reader, big.NewInt(1000000))
query.Set("tid", tid.String())
}
func prepareRequest(ctx context.Context, u string, headers http.Header) (*http.Request, error) {
// Make the GET request object.
req, err := http.NewRequestWithContext(ctx, "GET", u, nil)
if err != nil {
err = fmt.Errorf("get request creation failed")
return nil, err
}
// Add all header values.
req.Header = headers
return req, nil
}