From 6a95f412c942b871025436ade85e7207d27ee6ec Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Sat, 23 Jan 2021 18:27:23 -0800
Subject: [PATCH] avoid double CORS headers in federation (#11334)

CORS proxying adds double headers one
by the receiving server, one by proxied
server. Remove them before proxying
when 'Origin' header is found.
---
 cmd/common-main.go      |  5 ++++-
 cmd/generic-handlers.go | 10 ++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/cmd/common-main.go b/cmd/common-main.go
index 69dfaa60f..30cd5c60f 100644
--- a/cmd/common-main.go
+++ b/cmd/common-main.go
@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"context"
 	"crypto/x509"
 	"encoding/gob"
 	"errors"
@@ -61,7 +62,9 @@ func init() {
 		PassHost:     true,
 		RoundTripper: newGatewayHTTPTransport(1 * time.Hour),
 		Logger: func(err error) {
-			logger.LogIf(GlobalContext, err)
+			if err != nil && !errors.Is(err, context.Canceled) {
+				logger.LogIf(GlobalContext, err)
+			}
 		},
 	})
 
diff --git a/cmd/generic-handlers.go b/cmd/generic-handlers.go
index 02f8d4e98..35b74e347 100644
--- a/cmd/generic-handlers.go
+++ b/cmd/generic-handlers.go
@@ -580,6 +580,11 @@ func setBucketForwardingHandler(h http.Handler) http.Handler {
 					r.URL.Scheme = "https"
 				}
 				r.URL.Host = getHostFromSrv(sr)
+				// Make sure we remove any existing headers before
+				// proxying the request to another node.
+				for k := range w.Header() {
+					w.Header().Del(k)
+				}
 				globalForwarder.ServeHTTP(w, r)
 				return
 			}
@@ -630,6 +635,11 @@ func setBucketForwardingHandler(h http.Handler) http.Handler {
 				r.URL.Scheme = "https"
 			}
 			r.URL.Host = getHostFromSrv(sr)
+			// Make sure we remove any existing headers before
+			// proxying the request to another node.
+			for k := range w.Header() {
+				w.Header().Del(k)
+			}
 			globalForwarder.ServeHTTP(w, r)
 			return
 		}