GoToSocial/internal/api/client/streaming/stream.go

package streaming

import (
	"fmt"
	"net/http"
	"time"

	"codeberg.org/gruf/go-kv"
	"github.com/superseriousbusiness/gotosocial/internal/api"
	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
	"github.com/superseriousbusiness/gotosocial/internal/log"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"
)

var wsUpgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 1024,
	// we expect cors requests (via eg., pinafore.social) so be lenient
	CheckOrigin: func(r *http.Request) bool { return true },
}

// StreamGETHandler swagger:operation GET /api/v1/streaming streamGet
//
// Initiate a websocket connection for live streaming of statuses and notifications.
//
// The scheme used should *always* be `wss`. The streaming basepath can be viewed at `/api/v1/instance`.
//
// On a successful connection, a code `101` will be returned, which indicates that the connection is being upgraded to a secure websocket connection.
//
// As long as the connection is open, various message types will be streamed into it.
//
// GoToSocial will ping the connection every 30 seconds to check whether the client is still receiving.
//
// If the ping fails, or something else goes wrong during transmission, then the connection will be dropped, and the client will be expected to start it again.
//
// ---
// tags:
// - streaming
//
// produces:
// - application/json
//
// schemes:
// - wss
//
// parameters:
// - name: access_token
//   type: string
//   description: Access token for the requesting account.
//   in: query
//   required: true
// - name: stream
//   type: string
//   description: |-
//     Type of stream to request.
//
//     Options are:
//
//     `user`: receive updates for the account's home timeline.
//     `public`: receive updates for the public timeline.
//     `public:local`: receive updates for the local timeline.
//     `hashtag`: receive updates for a given hashtag.
//     `hashtag:local`: receive local updates for a given hashtag.
//     `list`: receive updates for a certain list of accounts.
//     `direct`: receive updates for direct messages.
//   in: query
//   required: true
// security:
// - OAuth2 Bearer:
//   - read:streaming
//
// responses:
//   '101':
//     schema:
//       type: object
//       properties:
//         stream:
//           type: array
//           items:
//             type: string
//             enum:
//             - user
//             - public
//             - public:local
//             - hashtag
//             - hashtag:local
//             - list
//             - direct
//         event:
//           description: |-
//             The type of event being received.
//
//             `update`: a new status has been received.
//             `notification`: a new notification has been received.
//             `delete`: a status has been deleted.
//             `filters_changed`: not implemented.
//           type: string
//           enum:
//           - update
//           - notification
//           - delete
//           - filters_changed
//         payload:
//           description: |-
//             The payload of the streamed message.
//             Different depending on the `event` type.
//
//             If present, it should be parsed as a string.
//
//             If `event` = `update`, then the payload will be a JSON string of a status.
//             If `event` = `notification`, then the payload will be a JSON string of a notification.
//             If `event` = `delete`, then the payload will be a status ID.
//           type: string
//           example: "{\"id\":\"01FC3TZ5CFG6H65GCKCJRKA669\",\"created_at\":\"2021-08-02T16:25:52Z\",\"sensitive\":false,\"spoiler_text\":\"\",\"visibility\":\"public\",\"language\":\"en\",\"uri\":\"https://gts.superseriousbusiness.org/users/dumpsterqueer/statuses/01FC3TZ5CFG6H65GCKCJRKA669\",\"url\":\"https://gts.superseriousbusiness.org/@dumpsterqueer/statuses/01FC3TZ5CFG6H65GCKCJRKA669\",\"replies_count\":0,\"reblogs_count\":0,\"favourites_count\":0,\"favourited\":false,\"reblogged\":false,\"muted\":false,\"bookmarked\":fals…//gts.superseriousbusiness.org/fileserver/01JNN207W98SGG3CBJ76R5MVDN/header/original/019036W043D8FXPJKSKCX7G965.png\",\"header_static\":\"https://gts.superseriousbusiness.org/fileserver/01JNN207W98SGG3CBJ76R5MVDN/header/small/019036W043D8FXPJKSKCX7G965.png\",\"followers_count\":33,\"following_count\":28,\"statuses_count\":126,\"last_status_at\":\"2021-08-02T16:25:52Z\",\"emojis\":[],\"fields\":[]},\"media_attachments\":[],\"mentions\":[],\"tags\":[],\"emojis\":[],\"card\":null,\"poll\":null,\"text\":\"a\"}"
//   '401':
//      description: unauthorized
//   '400':
//      description: bad request
func (m *Module) StreamGETHandler(c *gin.Context) {
	streamType := c.Query(StreamQueryKey)
	if streamType == "" {
		err := fmt.Errorf("no stream type provided under query key %s", StreamQueryKey)
		api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
		return
	}

	accessToken := c.Query(AccessTokenQueryKey)
	if accessToken == "" {
		err := fmt.Errorf("no access token provided under query key %s", AccessTokenQueryKey)
		api.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
		return
	}

	account, errWithCode := m.processor.AuthorizeStreamingRequest(c.Request.Context(), accessToken)
	if errWithCode != nil {
		api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
		return
	}

	stream, errWithCode := m.processor.OpenStreamForAccount(c.Request.Context(), account, streamType)
	if errWithCode != nil {
		api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
		return
	}

	l := log.WithFields(kv.Fields{
		{"account", account.Username},
		{"path", BasePath},
		{"streamID", stream.ID},
		{"streamType", streamType},
	}...)

	wsConn, err := wsUpgrader.Upgrade(c.Writer, c.Request, nil)
	if err != nil {
		// If the upgrade fails, then Upgrade replies to the client with an HTTP error response.
		// Because websocket issues are a pretty common source of headaches, we should also log
		// this at Error to make this plenty visible and help admins out a bit.
		l.Errorf("error upgrading websocket connection: %s", err)
		close(stream.Hangup)
		return
	}

	defer func() {
		// cleanup
		wsConn.Close()
		close(stream.Hangup)
	}()

	streamTicker := time.NewTicker(30 * time.Second)

	// We want to stay in the loop as long as possible while the client is connected.
	// The only thing that should break the loop is if the client leaves or the connection becomes unhealthy.
	//
	// If the loop does break, we expect the client to reattempt connection, so it's cheap to leave + try again
wsLoop:
	for {
		select {
		case m := <-stream.Messages:
			l.Trace("received message from stream")
			if err := wsConn.WriteJSON(m); err != nil {
				l.Debugf("error writing json to websocket connection; breaking off: %s", err)
				break wsLoop
			}
			l.Trace("wrote message into websocket connection")
		case <-streamTicker.C:
			l.Trace("received TICK from ticker")
			if err := wsConn.WriteMessage(websocket.PingMessage, []byte(": ping")); err != nil {
				l.Debugf("error writing ping to websocket connection; breaking off: %s", err)
				break wsLoop
			}
			l.Trace("wrote ping message into websocket connection")
		}
	}
}