[feature] More consistent API error handling (#637)

* update templates

* start reworking api error handling

* update template

* return AP status at web endpoint if negotiated

* start making api error handling much more consistent

* update account endpoints to new error handling

* use new api error handling in admin endpoints

* go fmt ./...

* use api error logic in app

* use generic error handling in auth

* don't export generic error handler

* don't defer clearing session

* user nicer error handling on oidc callback handler

* tidy up the sign in handler

* tidy up the token handler

* use nicer error handling in blocksget

* auth emojis endpoint

* fix up remaining api endpoints

* fix whoopsie during login flow

* regenerate swagger docs

* change http error logging to debug

1 files changed, 54 insertions, 45 deletions

diff --git a/internal/api/client/streaming/stream.go b/internal/api/client/streaming/stream.go
index c01bf2216..2c18e4e41 100644
--- a/internal/api/client/streaming/stream.go
+++ b/internal/api/client/streaming/stream.go
@@ -2,14 +2,24 @@ package streaming
 
 import (
 	"fmt"
-	"github.com/sirupsen/logrus"
 	"net/http"
 	"time"
 
+	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+
 	"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.
@@ -108,79 +118,78 @@ import (
 //   '400':
 //      description: bad request
 func (m *Module) StreamGETHandler(c *gin.Context) {
-	l := logrus.WithField("func", "StreamGETHandler")
-
 	streamType := c.Query(StreamQueryKey)
 	if streamType == "" {
-		c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("no stream type provided under query key %s", StreamQueryKey)})
+		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 == "" {
-		c.JSON(http.StatusUnauthorized, gin.H{"error": fmt.Sprintf("no access token provided under query key %s", AccessTokenQueryKey)})
+		err := fmt.Errorf("no access token provided under query key %s", AccessTokenQueryKey)
+		api.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
 		return
 	}
 
-	// make sure a valid token has been provided and obtain the associated account
-	account, err := m.processor.AuthorizeStreamingRequest(c.Request.Context(), accessToken)
-	if err != nil {
-		c.JSON(http.StatusUnauthorized, gin.H{"error": "could not authorize with given token"})
+	account, errWithCode := m.processor.AuthorizeStreamingRequest(c.Request.Context(), accessToken)
+	if errWithCode != nil {
+		api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
 		return
 	}
 
-	// prepare to upgrade the connection to a websocket connection
-	upgrader := websocket.Upgrader{
-		ReadBufferSize:  1024,
-		WriteBufferSize: 1024,
-		CheckOrigin: func(r *http.Request) bool {
-			// we fully expect cors requests (via something like pinafore.social) so we should be lenient here
-			return true
-		},
+	stream, errWithCode := m.processor.OpenStreamForAccount(c.Request.Context(), account, streamType)
+	if errWithCode != nil {
+		api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
 	}
 
-	// do the actual upgrade here
-	conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
+	l := logrus.WithFields(logrus.Fields{
+		"account":    account.Username,
+		"path":       BasePath,
+		"streamID":   stream.ID,
+		"streamType": streamType,
+	})
+
+	wsConn, err := wsUpgrader.Upgrade(c.Writer, c.Request, nil)
 	if err != nil {
-		l.Infof("error upgrading websocket connection: %s", err)
+		// 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 conn.Close() // whatever happens, when we leave this function we want to close the websocket connection
 
-	// inform the processor that we have a new connection and want a s for it
-	s, errWithCode := m.processor.OpenStreamForAccount(c.Request.Context(), account, streamType)
-	if errWithCode != nil {
-		c.JSON(errWithCode.Code(), errWithCode.Safe())
-		return
-	}
-	defer close(s.Hangup) // closing stream.Hangup indicates that we've finished with the connection (the client has gone), so we want to do this on exiting this handler
+	defer func() {
+		// cleanup
+		wsConn.Close()
+		close(stream.Hangup)
+	}()
 
-	// spawn a new ticker for pinging the connection periodically
-	t := time.NewTicker(30 * time.Second)
+	streamTicker := time.NewTicker(30 * time.Second)
 
-	// we want to stay in the sendloop as long as possible while the client is connected -- the only thing that should break the loop is if the client leaves or something else goes wrong
-sendLoop:
+	// 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 := <-s.Messages:
-			// we've got a streaming message!!
+		case m := <-stream.Messages:
 			l.Trace("received message from stream")
-			if err := conn.WriteJSON(m); err != nil {
-				l.Debugf("error writing json to websocket connection: %s", err)
-				// if something is wrong we want to bail and drop the connection -- the client will create a new one
-				break sendLoop
+			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 <-t.C:
+		case <-streamTicker.C:
 			l.Trace("received TICK from ticker")
-			if err := conn.WriteMessage(websocket.PingMessage, []byte(": ping")); err != nil {
-				l.Debugf("error writing ping to websocket connection: %s", err)
-				// if something is wrong we want to bail and drop the connection -- the client will create a new one
-				break sendLoop
+			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")
 		}
 	}
-
-	l.Trace("leaving StreamGETHandler")
 }