github.com/gofiber/contrib/websocket

---

id: websocket

Websocket

Based on Fasthttp WebSocket for Fiber with available *fiber.Ctx methods like Locals, Params, Query and Cookies.

Note: Requires Go 1.18 and above

Install

go get -u github.com/gofiber/fiber/v2
go get -u github.com/gofiber/contrib/websocket

Signatures

func New(handler func(*websocket.Conn), config ...websocket.Config) fiber.Handler {

Config

Property	Type	Description	Default
Filter	func(*fiber.Ctx) bool	Defines a function to skip middleware.	nil
HandshakeTimeout	time.Duration	HandshakeTimeout specifies the duration for the handshake to complete.	0 (No timeout)
Subprotocols	[]string	Subprotocols specifies the client's requested subprotocols.	nil
Origins	[]string	Allowed Origins based on the Origin header. If empty, everything is allowed.	nil
ReadBufferSize	int	ReadBufferSize specifies the I/O buffer size in bytes for incoming messages.	0 (Use default size)
WriteBufferSize	int	WriteBufferSize specifies the I/O buffer size in bytes for outgoing messages.	0 (Use default size)
WriteBufferPool	websocket.BufferPool	WriteBufferPool is a pool of buffers for write operations.	nil
EnableCompression	bool	EnableCompression specifies if the client should attempt to negotiate per message compression (RFC 7692).	false
RecoverHandler	func(*websocket.Conn) void	RecoverHandler is a panic handler function that recovers from panics.	defaultRecover

Example

package main

import (
	"log"

	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/contrib/websocket"
)

func main() {
	app := fiber.New()

	app.Use("/ws", func(c *fiber.Ctx) error {
		// IsWebSocketUpgrade returns true if the client
		// requested upgrade to the WebSocket protocol.
		if websocket.IsWebSocketUpgrade(c) {
			c.Locals("allowed", true)
			return c.Next()
		}
		return fiber.ErrUpgradeRequired
	})

	app.Get("/ws/:id", websocket.New(func(c *websocket.Conn) {
		// c.Locals is added to the *websocket.Conn
		log.Println(c.Locals("allowed"))  // true
		log.Println(c.Params("id"))       // 123
		log.Println(c.Query("v"))         // 1.0
		log.Println(c.Cookies("session")) // ""

		// websocket.Conn bindings https://pkg.go.dev/github.com/fasthttp/websocket?tab=doc#pkg-index
		var (
			mt  int
			msg []byte
			err error
		)
		for {
			if mt, msg, err = c.ReadMessage(); err != nil {
				log.Println("read:", err)
				break
			}
			log.Printf("recv: %s", msg)

			if err = c.WriteMessage(mt, msg); err != nil {
				log.Println("write:", err)
				break
			}
		}

	}))

	log.Fatal(app.Listen(":3000"))
	// Access the websocket server: ws://localhost:3000/ws/123?v=1.0
	// https://www.websocket.org/echo.html
}

Note with cache middleware

If you get the error websocket: bad handshake when using the cache middleware, please use config.Next to skip websocket path.

app := fiber.New()
app.Use(cache.New(cache.Config{
		Next: func(c *fiber.Ctx) bool {
			return strings.Contains(c.Route().Path, "/ws")
		},
}))

app.Get("/ws/:id", websocket.New(func(c *websocket.Conn) {}))

Note with recover middleware

For internal implementation reasons, currently recover middleware is not work with websocket middleware, please use config.RecoverHandler to add recover handler to websocket endpoints. By default, config RecoverHandler is recovers from panic and writes stack trace to stderr, also returns a response that contains panic message in error field.

app := fiber.New()

app.Use(cache.New(cache.Config{
    Next: func(c *fiber.Ctx) bool {
        return strings.Contains(c.Route().Path, "/ws")
    },
}))

cfg := Config{
    RecoverHandler: func(conn *Conn) {
        if err := recover(); err != nil {
            conn.WriteJSON(fiber.Map{"customError": "error occurred"})
        }
    },
}

app.Get("/ws/:id", websocket.New(func(c *websocket.Conn) {}, cfg))

Note for WebSocket subprotocols

The config Subprotocols only helps you negotiate subprotocols and sets a Sec-Websocket-Protocol header if it has a suitable subprotocol. For more about negotiates process, check the comment for Subprotocols in fasthttp.Upgrader .

All connections will be sent to the handler function no matter whether the subprotocol negotiation is successful or not. You can get the selected subprotocol from conn.Subprotocol().

If a connection includes the Sec-Websocket-Protocol header in the request but the protocol negotiation fails, the browser will immediately disconnect the connection after receiving the upgrade response.