Merge commit from fork

Signed-off-by: Jan Larwig <jan@larwig.com>

docs/docs/configuration/alpha_config.md

@@ -266,6 +266,7 @@ response header.
 | ----- | ---- | ----------- |
 | `name` | _string_ | Name is the header name to be used for this set of values.<br/>Names should be unique within a list of Headers. |
 | `preserveRequestValue` | _bool_ | PreserveRequestValue determines whether any values for this header<br/>should be preserved for the request to the upstream server.<br/>This option only applies to injected request headers.<br/>Defaults to false (headers that match this header will be stripped). |
+| `InsecureSkipHeaderNormalization` | _bool_ | InsecureSkipHeaderNormalization disables normalizing the header name<br/>According to RFC 7230 Section 3.2 there aren't any rules about<br/>capitalization of header names, but the standard practice is to use<br/>Title-Case (e.g. X-Forwarded-For). By default, header names will be<br/>normalized to Title-Case and any incoming headers that match will be<br/>treated as the same header. Additionally underscores (_) in header names<br/>will be converted to dashes (-) when normalizing.<br/>Defaults to false (header names will be normalized). |
 | `values` | _[[]HeaderValue](#headervalue)_ | Values contains the desired values for this header |
 
 ### HeaderValue

pkg/apis/options/header.go

@@ -13,6 +13,16 @@ type Header struct {
 	// Defaults to false (headers that match this header will be stripped).
 	PreserveRequestValue bool `json:"preserveRequestValue,omitempty"`
 
+	// InsecureSkipHeaderNormalization disables normalizing the header name
+	// According to RFC 7230 Section 3.2 there aren't any rules about
+	// capitalization of header names, but the standard practice is to use
+	// Title-Case (e.g. X-Forwarded-For). By default, header names will be
+	// normalized to Title-Case and any incoming headers that match will be
+	// treated as the same header. Additionally underscores (_) in header names
+	// will be converted to dashes (-) when normalizing.
+	// Defaults to false (header names will be normalized).
+	InsecureSkipHeaderNormalization bool `json:"InsecureSkipHeaderNormalization,omitempty"`
+
 	// Values contains the desired values for this header
 	Values []HeaderValue `json:"values,omitempty"`
 }

pkg/middleware/headers.go

@@ -53,6 +53,11 @@ func flattenHeaders(headers http.Header) {
 func stripHeaders(headers []options.Header, next http.Handler) http.Handler {
 	return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
 		for _, header := range headers {
+			if header.InsecureSkipHeaderNormalization {
+				req.Header.Del(header.Name)
+				continue
+			}
+
 			stripNormalizedHeader(req, header)
 		}
 		next.ServeHTTP(rw, req)

pkg/middleware/headers_test.go

@@ -205,7 +205,7 @@ var _ = Describe("Headers Suite", func() {
 			expectedHeaders: nil,
 			expectedErr:     "error building request header injector: error building request injector: error building injector for header \"X-Auth-Request-Authorization\": error loading basicAuthPassword: secret source is invalid: exactly one entry required, specify either value, fromEnv or fromFile",
 		}),
-		Entry("strips normalized variants before injecting (no preservation)", headersTableInput{
+		Entry("strips normalized variants before injecting", headersTableInput{
 			headers: []options.Header{
 				{
 					Name: "X-Auth-Request-User",
@@ -226,6 +226,29 @@ var _ = Describe("Headers Suite", func() {
 			},
 			expectedErr: "",
 		}),
+		Entry("doesn't strip normalized variants before injecting", headersTableInput{
+			headers: []options.Header{
+				{
+					Name:                            "X-Auth-Request-User",
+					InsecureSkipHeaderNormalization: true,
+					Values: []options.HeaderValue{
+						{
+							ClaimSource: &options.ClaimSource{Claim: "user"},
+						},
+					},
+				},
+			},
+			initialHeaders: http.Header{
+				"X-Auth-Request-User": []string{"old"},
+				"X-Auth_Request_User": []string{"evil"},
+			},
+			session: &sessionsapi.SessionState{User: "user-123"},
+			expectedHeaders: http.Header{
+				"X-Auth-Request-User": []string{"user-123"},
+				"X-Auth_Request_User": []string{"evil"},
+			},
+			expectedErr: "",
+		}),
 	)
 
 	DescribeTable("the response header injector",