From 0d697f675484cfd990af640aad6fa54c44ecd208 Mon Sep 17 00:00:00 2001
From: Till <2353100+S7evinK@users.noreply.github.com>
Date: Wed, 7 Sep 2022 16:14:09 +0200
Subject: [PATCH] Add HTTP status code to FederationClientError (#2699)

Also ensures we wait on more HTTP status codes.
---
 federationapi/api/api.go                 |  4 +++-
 federationapi/inthttp/server.go          | 10 ++++++++--
 keyserver/internal/device_list_update.go | 21 +++++++++++++--------
 sytest-blacklist                         |  3 +++
 sytest-whitelist                         |  1 -
 5 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/federationapi/api/api.go b/federationapi/api/api.go
index 292ed55a..f2553878 100644
--- a/federationapi/api/api.go
+++ b/federationapi/api/api.go
@@ -5,9 +5,10 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/matrix-org/dendrite/federationapi/types"
 	"github.com/matrix-org/gomatrix"
 	"github.com/matrix-org/gomatrixserverlib"
+
+	"github.com/matrix-org/dendrite/federationapi/types"
 )
 
 // FederationInternalAPI is used to query information from the federation sender.
@@ -108,6 +109,7 @@ type FederationClientError struct {
 	Err         string
 	RetryAfter  time.Duration
 	Blacklisted bool
+	Code        int // HTTP Status code from the remote server
 }
 
 func (e FederationClientError) Error() string {
diff --git a/federationapi/inthttp/server.go b/federationapi/inthttp/server.go
index a8b829a7..58ea9ddc 100644
--- a/federationapi/inthttp/server.go
+++ b/federationapi/inthttp/server.go
@@ -6,10 +6,12 @@ import (
 	"net/http"
 
 	"github.com/gorilla/mux"
-	"github.com/matrix-org/dendrite/federationapi/api"
-	"github.com/matrix-org/dendrite/internal/httputil"
+	"github.com/matrix-org/gomatrix"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
+
+	"github.com/matrix-org/dendrite/federationapi/api"
+	"github.com/matrix-org/dendrite/internal/httputil"
 )
 
 // AddRoutes adds the FederationInternalAPI handlers to the http.ServeMux.
@@ -229,6 +231,10 @@ func federationClientError(err error) error {
 		return &ferr
 	case *api.FederationClientError:
 		return ferr
+	case gomatrix.HTTPError:
+		return &api.FederationClientError{
+			Code: ferr.Code,
+		}
 	default:
 		return &api.FederationClientError{
 			Err: err.Error(),
diff --git a/keyserver/internal/device_list_update.go b/keyserver/internal/device_list_update.go
index b70d6a5e..41534fe8 100644
--- a/keyserver/internal/device_list_update.go
+++ b/keyserver/internal/device_list_update.go
@@ -407,10 +407,13 @@ userLoop:
 					waitTime = e.RetryAfter
 				} else if e.Blacklisted {
 					waitTime = time.Hour * 8
-				} else {
+					break userLoop
+				} else if e.Code >= 300 {
+					// We didn't get a real FederationClientError (e.g. in polylith mode, where gomatrix.HTTPError
+					// are "converted" to FederationClientError), but we probably shouldn't hit them every $waitTime seconds.
 					waitTime = time.Hour
+					break userLoop
 				}
-				break userLoop
 			case net.Error:
 				// Use the default waitTime, if it's a timeout.
 				// It probably doesn't make sense to try further users.
@@ -420,9 +423,10 @@ userLoop:
 					break userLoop
 				}
 			case gomatrix.HTTPError:
-				// The remote server returned an error, give it some time to recover
-				if e.Code >= 500 {
-					waitTime = time.Minute * 10
+				// The remote server returned an error, give it some time to recover.
+				// This is to avoid spamming remote servers, which may not be Matrix servers anymore.
+				if e.Code >= 300 {
+					waitTime = time.Hour
 					logrus.WithError(e).Error("GetUserDevices returned gomatrix.HTTPError")
 					break userLoop
 				}
@@ -459,9 +463,10 @@ userLoop:
 	}
 	if failCount > 0 {
 		logger.WithFields(logrus.Fields{
-			"total":   len(userIDs),
-			"failed":  failCount,
-			"skipped": len(userIDs) - failCount,
+			"total":    len(userIDs),
+			"failed":   failCount,
+			"skipped":  len(userIDs) - failCount,
+			"waittime": waitTime,
 		}).Warn("Failed to query device keys for some users")
 	}
 	for _, userID := range userIDs {
diff --git a/sytest-blacklist b/sytest-blacklist
index bcc345f6..5b2e973a 100644
--- a/sytest-blacklist
+++ b/sytest-blacklist
@@ -49,3 +49,6 @@ Notifications can be viewed with GET /notifications
 
 If remote user leaves room we no longer receive device updates
 Guest users can join guest_access rooms
+
+# This will fail in HTTP API mode, so blacklisted for now
+If a device list update goes missing, the server resyncs on the next one
\ No newline at end of file
diff --git a/sytest-whitelist b/sytest-whitelist
index fc10bd3c..31940b88 100644
--- a/sytest-whitelist
+++ b/sytest-whitelist
@@ -742,4 +742,3 @@ User in private room doesn't appear in user directory
 User joining then leaving public room appears and dissappears from directory
 User in remote room doesn't appear in user directory after server left room
 User in shared private room does appear in user directory until leave
-If a device list update goes missing, the server resyncs on the next one
\ No newline at end of file