Auto add 'Vary' header after compression (#1585)

* Auto add 'Vary' header after compression

Add config `SetAddVaryHeaderForCompression` to enable
'Vary: Accept-Encoding' header when compression is used.

* feat: always set the Vary header

* create and use `ResponseHeader.AddVaryBytes`

* not export 'AddVaryBytes'

1 files changed, 3 insertions, 0 deletions

diff --git a/http.go b/http.go
index ffb02c8..5d8dc93 100644
--- a/http.go
+++ b/http.go
@@ -1723,6 +1723,7 @@ func (resp *Response) brotliBody(level int) error {
 		resp.bodyRaw = nil
 	}
 	resp.Header.SetContentEncodingBytes(strBr)
+	resp.Header.addVaryBytes(strAcceptEncoding)
 	return nil
 }
 
@@ -1778,6 +1779,7 @@ func (resp *Response) gzipBody(level int) error {
 		resp.bodyRaw = nil
 	}
 	resp.Header.SetContentEncodingBytes(strGzip)
+	resp.Header.addVaryBytes(strAcceptEncoding)
 	return nil
 }
 
@@ -1833,6 +1835,7 @@ func (resp *Response) deflateBody(level int) error {
 		resp.bodyRaw = nil
 	}
 	resp.Header.SetContentEncodingBytes(strDeflate)
+	resp.Header.addVaryBytes(strAcceptEncoding)
 	return nil
 }