Documentation ¶
Overview ¶
Package websocket implements the RFC 6455 WebSocket protocol.
https://tools.ietf.org/html/rfc6455
Use Dial to dial a WebSocket server.
Use Accept to accept a WebSocket client.
Conn represents the resulting WebSocket connection.
The examples are the best way to understand how to correctly use the library.
The wsjson and wspb subpackages contain helpers for JSON and protobuf messages.
More documentation at https://github.com/ZackaryWelch/websocket.
Wasm ¶
The client side supports compiling to Wasm. It wraps the WebSocket browser API.
See https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
Some important caveats to be aware of:
- Accept always errors out
- Conn.Ping is no-op
- HTTPClient, HTTPHeader and CompressionMode in DialOptions are no-op
- *http.Response from Dial is &http.Response{} with a 101 status code on success
Example (CrossOrigin) ¶
package main import ( "log" "net/http" "github.com/ZackaryWelch/websocket" ) func main() { // This handler demonstrates how to safely accept cross origin WebSockets // from the origin example.com. fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { c, err := websocket.Accept(w, r, &websocket.AcceptOptions{ OriginPatterns: []string{"example.com"}, }) if err != nil { log.Println(err) return } c.Close(websocket.StatusNormalClosure, "cross origin WebSocket accepted") }) err := http.ListenAndServe("localhost:8080", fn) log.Fatal(err) }
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Example (Echo) ¶
This example demonstrates a echo server.
package main import () func main() { // https://github.com/nhooyr/websocket/tree/master/examples/echo }
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Example (FullStackChat) ¶
This example demonstrates full stack chat with an automated test.
package main import () func main() { // https://github.com/nhooyr/websocket/tree/master/examples/chat }
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Example (WriteOnly) ¶
package main import ( "context" "log" "net/http" "time" "github.com/ZackaryWelch/websocket" "github.com/ZackaryWelch/websocket/wsjson" ) func main() { // This handler demonstrates how to correctly handle a write only WebSocket connection. // i.e you only expect to write messages and do not expect to read any messages. fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { c, err := websocket.Accept(w, r, nil) if err != nil { log.Println(err) return } defer c.Close(websocket.StatusInternalError, "the sky is falling") ctx, cancel := context.WithTimeout(r.Context(), time.Minute*10) defer cancel() ctx = c.CloseRead(ctx) t := time.NewTicker(time.Second * 30) defer t.Stop() for { select { case <-ctx.Done(): c.Close(websocket.StatusNormalClosure, "") return case <-t.C: err = wsjson.Write(ctx, c, "hi") if err != nil { log.Println(err) return } } } }) err := http.ListenAndServe("localhost:8080", fn) log.Fatal(err) }
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Index ¶
- func NetConn(ctx context.Context, c *Conn, msgType MessageType) net.Conn
- func Wrap(err *error, f string, v ...interface{})
- type AcceptOptions
- type CloseError
- type CompressionMode
- type Conn
- func (c *Conn) Close(code StatusCode, reason string) error
- func (c *Conn) CloseRead(ctx context.Context) context.Context
- func (c *Conn) Ping(ctx context.Context) error
- func (c *Conn) Read(ctx context.Context) (MessageType, []byte, error)
- func (c *Conn) Reader(ctx context.Context) (MessageType, io.Reader, error)
- func (c *Conn) SetReadLimit(n int64)
- func (c *Conn) Subprotocol() string
- func (c *Conn) Write(ctx context.Context, typ MessageType, p []byte) error
- func (c *Conn) Writer(ctx context.Context, typ MessageType) (io.WriteCloser, error)
- type DialOptions
- type MessageType
- type StatusCode
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func NetConn ¶
NetConn converts a *websocket.Conn into a net.Conn.
It's for tunneling arbitrary protocols over WebSockets. Few users of the library will need this but it's tricky to implement correctly and so provided in the library. See https://github.com/nhooyr/websocket/issues/100.
Every Write to the net.Conn will correspond to a message write of the given type on *websocket.Conn.
The passed ctx bounds the lifetime of the net.Conn. If cancelled, all reads and writes on the net.Conn will be cancelled.
If a message is read that is not of the correct type, the connection will be closed with StatusUnsupportedData and an error will be returned.
Close will close the *websocket.Conn with StatusNormalClosure.
When a deadline is hit, the connection will be closed. This is different from most net.Conn implementations where only the reading/writing goroutines are interrupted but the connection is kept alive.
The Addr methods will return a mock net.Addr that returns "websocket" for Network and "websocket/unknown-addr" for String.
A received StatusNormalClosure or StatusGoingAway close frame will be translated to io.EOF when reading.
func Wrap ¶
Wrap wraps err with fmt.Errorf if err is non nil. Intended for use with defer and a named error return. Inspired by https://github.com/golang/go/issues/32676.
Types ¶
type AcceptOptions ¶
type AcceptOptions struct { // Subprotocols lists the WebSocket subprotocols that Accept will negotiate with the client. // The empty subprotocol will always be negotiated as per RFC 6455. If you would like to // reject it, close the connection when c.Subprotocol() == "". Subprotocols []string // InsecureSkipVerify is used to disable Accept's origin verification behaviour. // // You probably want to use OriginPatterns instead. InsecureSkipVerify bool // OriginPatterns lists the host patterns for authorized origins. // The request host is always authorized. // Use this to enable cross origin WebSockets. // // i.e javascript running on example.com wants to access a WebSocket server at chat.example.com. // In such a case, example.com is the origin and chat.example.com is the request host. // One would set this field to []string{"example.com"} to authorize example.com to connect. // // Each pattern is matched case insensitively against the request origin host // with filepath.Match. // See https://golang.org/pkg/path/filepath/#Match // // Please ensure you understand the ramifications of enabling this. // If used incorrectly your WebSocket server will be open to CSRF attacks. // // Do not use * as a pattern to allow any origin, prefer to use InsecureSkipVerify instead // to bring attention to the danger of such a setting. OriginPatterns []string // CompressionMode controls the compression mode. // Defaults to CompressionNoContextTakeover. // // See docs on CompressionMode for details. CompressionMode CompressionMode // CompressionThreshold controls the minimum size of a message before compression is applied. // // Defaults to 512 bytes for CompressionNoContextTakeover and 128 bytes // for CompressionContextTakeover. CompressionThreshold int }
AcceptOptions represents Accept's options.
type CloseError ¶
type CloseError struct { Code StatusCode Reason string }
CloseError is returned when the connection is closed with a status and reason.
Use Go 1.13's errors.As to check for this error. Also see the CloseStatus helper.
func (CloseError) Error ¶
func (ce CloseError) Error() string
type CompressionMode ¶
type CompressionMode int
CompressionMode represents the modes available to the deflate extension. See https://tools.ietf.org/html/rfc7692
A compatibility layer is implemented for the older deflate-frame extension used by safari. See https://tools.ietf.org/html/draft-tyoshino-hybi-websocket-perframe-deflate-06 It will work the same in every way except that we cannot signal to the peer we want to use no context takeover on our side, we can only signal that they should. It is however currently disabled due to Safari bugs. See https://github.com/nhooyr/websocket/issues/218
const ( // CompressionNoContextTakeover grabs a new flate.Reader and flate.Writer as needed // for every message. This applies to both server and client side. // // This means less efficient compression as the sliding window from previous messages // will not be used but the memory overhead will be lower if the connections // are long lived and seldom used. // // The message will only be compressed if greater than 512 bytes. CompressionNoContextTakeover CompressionMode = iota // CompressionContextTakeover uses a flate.Reader and flate.Writer per connection. // This enables reusing the sliding window from previous messages. // As most WebSocket protocols are repetitive, this can be very efficient. // It carries an overhead of 8 kB for every connection compared to CompressionNoContextTakeover. // // If the peer negotiates NoContextTakeover on the client or server side, it will be // used instead as this is required by the RFC. CompressionContextTakeover // CompressionDisabled disables the deflate extension. // // Use this if you are using a predominantly binary protocol with very // little duplication in between messages or CPU and memory are more // important than bandwidth. CompressionDisabled )
type Conn ¶
type Conn struct {
// contains filtered or unexported fields
}
Conn represents a WebSocket connection. All methods may be called concurrently except for Reader and Read.
You must always read from the connection. Otherwise control frames will not be handled. See Reader and CloseRead.
Be sure to call Close on the connection when you are finished with it to release associated resources.
On any error from any method, the connection is closed with an appropriate reason.
func Accept ¶
func Accept(w http.ResponseWriter, r *http.Request, opts *AcceptOptions) (*Conn, error)
Accept accepts a WebSocket handshake from a client and upgrades the the connection to a WebSocket.
Accept will not allow cross origin requests by default. See the InsecureSkipVerify and OriginPatterns options to allow cross origin requests.
Accept will write a response to w on all errors.
Example ¶
package main import ( "context" "log" "net/http" "time" "github.com/ZackaryWelch/websocket" "github.com/ZackaryWelch/websocket/wsjson" ) func main() { // This handler accepts a WebSocket connection, reads a single JSON // message from the client and then closes the connection. fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { c, err := websocket.Accept(w, r, nil) if err != nil { log.Println(err) return } defer c.Close(websocket.StatusInternalError, "the sky is falling") ctx, cancel := context.WithTimeout(r.Context(), time.Second*10) defer cancel() var v interface{} err = wsjson.Read(ctx, c, &v) if err != nil { log.Println(err) return } c.Close(websocket.StatusNormalClosure, "") }) err := http.ListenAndServe("localhost:8080", fn) log.Fatal(err) }
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func Dial ¶
Dial performs a WebSocket handshake on url.
The response is the WebSocket handshake response from the server. You never need to close resp.Body yourself.
If an error occurs, the returned response may be non nil. However, you can only read the first 1024 bytes of the body.
This function requires at least Go 1.12 as it uses a new feature in net/http to perform WebSocket handshakes. See docs on the HTTPClient option and https://github.com/golang/go/issues/26937#issuecomment-415855861
URLs with http/https schemes will work and are interpreted as ws/wss.
Example ¶
package main import ( "context" "log" "time" "github.com/ZackaryWelch/websocket" "github.com/ZackaryWelch/websocket/wsjson" ) func main() { // Dials a server, writes a single JSON message and then // closes the connection. ctx, cancel := context.WithTimeout(context.Background(), time.Minute) defer cancel() c, _, err := websocket.Dial(ctx, "ws://localhost:8080", nil) if err != nil { log.Fatal(err) } defer c.Close(websocket.StatusInternalError, "the sky is falling") err = wsjson.Write(ctx, c, "hi") if err != nil { log.Fatal(err) } c.Close(websocket.StatusNormalClosure, "") }
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func (*Conn) Close ¶
func (c *Conn) Close(code StatusCode, reason string) error
Close performs the WebSocket close handshake with the given status code and reason.
It will write a WebSocket close frame with a timeout of 5s and then wait 5s for the peer to send a close frame. All data messages received from the peer during the close handshake will be discarded.
The connection can only be closed once. Additional calls to Close are no-ops.
The maximum length of reason must be 125 bytes. Avoid sending a dynamic reason.
Close will unblock all goroutines interacting with the connection once complete.
func (*Conn) CloseRead ¶
CloseRead starts a goroutine to read from the connection until it is closed or a data message is received.
Once CloseRead is called you cannot read any messages from the connection. The returned context will be cancelled when the connection is closed.
If a data message is received, the connection will be closed with StatusPolicyViolation.
Call CloseRead when you do not expect to read any more messages. Since it actively reads from the connection, it will ensure that ping, pong and close frames are responded to. This means c.Ping and c.Close will still work as expected.
func (*Conn) Ping ¶
Ping sends a ping to the peer and waits for a pong. Use this to measure latency or ensure the peer is responsive. Ping must be called concurrently with Reader as it does not read from the connection but instead waits for a Reader call to read the pong.
TCP Keepalives should suffice for most use cases.
func (*Conn) Read ¶
Read is a convenience method around Reader to read a single message from the connection.
func (*Conn) Reader ¶
Reader reads from the connection until there is a WebSocket data message to be read. It will handle ping, pong and close frames as appropriate.
It returns the type of the message and an io.Reader to read it. The passed context will also bound the reader. Ensure you read to EOF otherwise the connection will hang.
Call CloseRead if you do not expect any data messages from the peer.
Only one Reader may be open at a time.
func (*Conn) SetReadLimit ¶
SetReadLimit sets the max number of bytes to read for a single message. It applies to the Reader and Read methods.
By default, the connection has a message read limit of 32768 bytes.
When the limit is hit, the connection will be closed with StatusMessageTooBig.
func (*Conn) Subprotocol ¶
Subprotocol returns the negotiated subprotocol. An empty string means the default protocol.
func (*Conn) Write ¶
Write writes a message to the connection.
See the Writer method if you want to stream a message.
If compression is disabled or the threshold is not met, then it will write the message in a single frame.
func (*Conn) Writer ¶
func (c *Conn) Writer(ctx context.Context, typ MessageType) (io.WriteCloser, error)
Writer returns a writer bounded by the context that will write a WebSocket message of type dataType to the connection.
You must close the writer once you have written the entire message.
Only one writer can be open at a time, multiple calls will block until the previous writer is closed.
type DialOptions ¶
type DialOptions struct { // HTTPClient is used for the connection. // Its Transport must return writable bodies for WebSocket handshakes. // http.Transport does beginning with Go 1.12. HTTPClient *http.Client // HTTPHeader specifies the HTTP headers included in the handshake request. HTTPHeader http.Header // Subprotocols lists the WebSocket subprotocols to negotiate with the server. Subprotocols []string // CompressionMode controls the compression mode. // Defaults to CompressionNoContextTakeover. // // See docs on CompressionMode for details. CompressionMode CompressionMode // CompressionThreshold controls the minimum size of a message before compression is applied. // // Defaults to 512 bytes for CompressionNoContextTakeover and 128 bytes // for CompressionContextTakeover. CompressionThreshold int }
DialOptions represents Dial's options.
type MessageType ¶
type MessageType int
MessageType represents the type of a WebSocket message. See https://tools.ietf.org/html/rfc6455#section-5.6
const ( // MessageText is for UTF-8 encoded text messages like JSON. MessageText MessageType = iota + 1 // MessageBinary is for binary messages like protobufs. MessageBinary )
MessageType constants.
func (MessageType) String ¶
func (i MessageType) String() string
type StatusCode ¶
type StatusCode int
StatusCode represents a WebSocket status code. https://tools.ietf.org/html/rfc6455#section-7.4
const ( StatusNormalClosure StatusCode = 1000 StatusGoingAway StatusCode = 1001 StatusProtocolError StatusCode = 1002 StatusUnsupportedData StatusCode = 1003 // StatusNoStatusRcvd cannot be sent in a close message. // It is reserved for when a close message is received without // a status code. StatusNoStatusRcvd StatusCode = 1005 // StatusAbnormalClosure is exported for use only with Wasm. // In non Wasm Go, the returned error will indicate whether the // connection was closed abnormally. StatusAbnormalClosure StatusCode = 1006 StatusInvalidFramePayloadData StatusCode = 1007 StatusPolicyViolation StatusCode = 1008 StatusMessageTooBig StatusCode = 1009 StatusMandatoryExtension StatusCode = 1010 StatusInternalError StatusCode = 1011 StatusServiceRestart StatusCode = 1012 StatusTryAgainLater StatusCode = 1013 StatusBadGateway StatusCode = 1014 // StatusTLSHandshake is only exported for use with Wasm. // In non Wasm Go, the returned error will indicate whether there was // a TLS handshake failure. StatusTLSHandshake StatusCode = 1015 )
https://www.iana.org/assignments/websocket/websocket.xhtml#close-code-number
These are only the status codes defined by the protocol.
You can define custom codes in the 3000-4999 range. The 3000-3999 range is reserved for use by libraries, frameworks and applications. The 4000-4999 range is reserved for private use.
func CloseStatus ¶
func CloseStatus(err error) StatusCode
CloseStatus is a convenience wrapper around Go 1.13's errors.As to grab the status code from a CloseError.
-1 will be returned if the passed error is nil or not a CloseError.
Example ¶
package main import ( "context" "log" "time" "github.com/ZackaryWelch/websocket" ) func main() { // Dials a server and then expects to be disconnected with status code // websocket.StatusNormalClosure. ctx, cancel := context.WithTimeout(context.Background(), time.Minute) defer cancel() c, _, err := websocket.Dial(ctx, "ws://localhost:8080", nil) if err != nil { log.Fatal(err) } defer c.Close(websocket.StatusInternalError, "the sky is falling") _, _, err = c.Reader(ctx) if websocket.CloseStatus(err) != websocket.StatusNormalClosure { log.Fatalf("expected to be disconnected with StatusNormalClosure but got: %v", err) } }
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func (StatusCode) String ¶
func (i StatusCode) String() string
Source Files ¶
Directories ¶
Path | Synopsis |
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examples
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internal
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test
Package test contains subpackages only used in tests.
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Package test contains subpackages only used in tests. |
wsjs
Package wsjs implements typed access to the browser javascript WebSocket API.
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Package wsjs implements typed access to the browser javascript WebSocket API. |
Package wsjson provides helpers for reading and writing JSON messages.
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Package wsjson provides helpers for reading and writing JSON messages. |
Package wspb provides helpers for reading and writing protobuf messages.
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Package wspb provides helpers for reading and writing protobuf messages. |