From 668a722ee0e85b1f058962bd4df96ae542018a23 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Tue, 8 Sep 2020 13:41:08 +0100
Subject: [PATCH] Backoff for 401s (#1410)

* Backoff for 401s

* Human-readable retry_after in logs
---
 federationsender/api/api.go      | 2 +-
 federationsender/internal/api.go | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/federationsender/api/api.go b/federationsender/api/api.go
index 655d1d10..adc3b34c 100644
--- a/federationsender/api/api.go
+++ b/federationsender/api/api.go
@@ -30,7 +30,7 @@ type FederationClientError struct {
 }
 
 func (e *FederationClientError) Error() string {
-	return fmt.Sprintf("%s - (retry_after=%d, blacklisted=%v)", e.Err, e.RetryAfter, e.Blacklisted)
+	return fmt.Sprintf("%s - (retry_after=%s, blacklisted=%v)", e.Err, e.RetryAfter.String(), e.Blacklisted)
 }
 
 // FederationSenderInternalAPI is used to query information from the federation sender.
diff --git a/federationsender/internal/api.go b/federationsender/internal/api.go
index 61663be3..2a70f7ed 100644
--- a/federationsender/internal/api.go
+++ b/federationsender/internal/api.go
@@ -70,7 +70,10 @@ func failBlacklistableError(err error, stats *statistics.ServerStatistics) (unti
 	if !ok {
 		return stats.Failure()
 	}
-	if mxerr.Code >= 500 && mxerr.Code < 600 {
+	if mxerr.Code == 401 { // invalid signature in X-Matrix header
+		return stats.Failure()
+	}
+	if mxerr.Code >= 500 && mxerr.Code < 600 { // internal server errors
 		return stats.Failure()
 	}
 	return