Add library call to irma server to subscribe on statuses using channels

privacybydesign · Sep 4, 2020 · 15ee246 · 15ee246
1 parent 656dcaf
commit 15ee246
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Showing 4 changed files with 46 additions and 22 deletions.
diff --git a/irma/cmd/session.go b/irma/cmd/session.go
@@ -8,7 +8,6 @@ import (
 	"regexp"
 	"strconv"
 	"sync"
-	"time"
 
 	"github.com/go-errors/errors"
 	"github.com/privacybydesign/irmago"
@@ -133,21 +132,10 @@ func libraryRequest(
 
 	if binding {
 		// Listen for session status
-		statuschan := make(chan irma.ServerStatus)
-		go func() {
-			var status irma.ServerStatus
-			for {
-				newStatus := irmaServer.GetSessionResult(requestorToken).Status
-				if newStatus != status {
-					status = newStatus
-					statuschan <- status
-					if status.Finished() {
-						return
-					}
-				}
-				time.Sleep(500 * time.Millisecond)
-			}
-		}()
+		statuschan, err := irmaServer.GetSessionStatus(string(requestorToken), true)
+		if err != nil {
+			return nil, errors.WrapPrefix(err, "Failed to start listening for session statuses", 0)
+		}
 
 		_, err = handleBinding(sessionOptions, statuschan, func() error {
 			return irmaServer.BindingCompleted(requestorToken)
@@ -309,7 +297,7 @@ func handleBinding(options *irma.SessionOptions, statusChan chan irma.ServerStat
 			}
 			return status, nil
 		case err := <-errorChan:
-			return status, err
+			return "", err
 		}
 	}
 }

diff --git a/server/irmaserver/api.go b/server/irmaserver/api.go
@@ -317,3 +317,27 @@ func (s *Server) SubscribeServerSentEvents(w http.ResponseWriter, r *http.Reques
 	s.serverSentEvents.ServeHTTP(w, r)
 	return nil
 }
+
+// GetSessionStatus retrieves a channel on which the current session status of the specified
+// IRMA session can be retrieved.
+func GetSessionStatus(token string, requestor bool) (chan irma.ServerStatus, error) {
+	return s.GetSessionStatus(token, requestor)
+}
+func (s *Server) GetSessionStatus(token string, requestor bool) (chan irma.ServerStatus, error) {
+	var session *session
+	if requestor {
+		session = s.sessions.get(irma.RequestorToken(token))
+	} else {
+		session = s.sessions.clientGet(irma.ClientToken(token))
+	}
+	if session == nil {
+		return nil, server.LogError(errors.Errorf("can't get session status of unknown session %s", token))
+	}
+
+	statusChan := make(chan irma.ServerStatus)
+	go func() {
+		statusChan <- session.status
+	}()
+	session.statusChannels = append(session.statusChannels, statusChan)
+	return statusChan, nil
+}
diff --git a/server/irmaserver/helpers.go b/server/irmaserver/helpers.go
@@ -42,6 +42,17 @@ func (session *session) setStatus(status irma.ServerStatus) {
 }
 
 func (session *session) onUpdate() {
+	// Perform sending to channels async to make sure session handling
+	// will not hang if channel is not (immediately) read.
+	for _, statusChan := range session.statusChannels {
+		go func(statusChan chan irma.ServerStatus, status irma.ServerStatus) {
+			statusChan <- status
+			if status.Finished() {
+				close(statusChan)
+			}
+		}(statusChan, session.status)
+	}
+
 	if session.sse == nil {
 		return
 	}

diff --git a/server/irmaserver/sessions.go b/server/irmaserver/sessions.go
@@ -27,11 +27,12 @@ type session struct {
 	request          irma.SessionRequest
 	legacyCompatible bool // if the request is convertible to pre-condiscon format
 
-	options       irma.SessionOptions
-	status        irma.ServerStatus
-	prevStatus    irma.ServerStatus
-	sse           *sse.Server
-	responseCache responseCache
+	options        irma.SessionOptions
+	status         irma.ServerStatus
+	prevStatus     irma.ServerStatus
+	sse            *sse.Server
+	statusChannels []chan irma.ServerStatus
+	responseCache  responseCache
 
 	clientAuth irma.ClientAuthorization
 	lastActive time.Time