normalize incoming header keys to lowercase at ingestion

gyliu513 · gyliu513 · commit 7ccd90c28dab · 2026-06-18T12:11:24.000-04:00
Signed-off-by: Guangya Liu &lt;gyliu513@gmail.com&gt;
diff --git a/pkg/handlers/request.go b/pkg/handlers/request.go
@@ -45,7 +45,10 @@ func (s *Server) HandleRequestHeaders(ctx context.Context, reqCtx *RequestContex
 
 	if headers != nil && headers.Headers != nil {
 		for _, header := range headers.Headers.Headers {
-			reqCtx.Request.Headers[header.Key] = envoy.GetHeaderValue(header)
+			// Normalize keys to lowercase so later case-insensitive lookups and
+			// mutations (e.g. the trace context injection below) overwrite the
+			// upstream header instead of producing a case-differentiated duplicate.
+			reqCtx.Request.Headers[strings.ToLower(header.Key)] = envoy.GetHeaderValue(header)
 		}
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -45,7 +45,10 @@ func (s Server) HandleRequestHeaders(ctx context.Context, reqCtx RequestContex`
`45`	`45`
`46`	`46`	`if headers != nil && headers.Headers != nil {`
`47`	`47`	`for _, header := range headers.Headers.Headers {`
`48`		`- reqCtx.Request.Headers[header.Key] = envoy.GetHeaderValue(header)`
	`48`	`+ // Normalize keys to lowercase so later case-insensitive lookups and`
	`49`	`+ // mutations (e.g. the trace context injection below) overwrite the`
	`50`	`+ // upstream header instead of producing a case-differentiated duplicate.`
	`51`	`+ reqCtx.Request.Headers[strings.ToLower(header.Key)] = envoy.GetHeaderValue(header)`
`49`	`52`	`}`
`50`	`53`	`}`
`51`	`54`