Add Cache-Control, Pragma, Expires, and X-DNS-Prefetch-Control headers

Signed-off-by: Margo Crawford <margaretc@vmware.com>

internal/oidc/callback/callback_handler.go

@@ -17,6 +17,7 @@ import (
 	"github.com/ory/fosite/token/jwt"
 
 	"go.pinniped.dev/internal/httputil/httperr"
+	"go.pinniped.dev/internal/httputil/securityheader"
 	"go.pinniped.dev/internal/oidc"
 	"go.pinniped.dev/internal/oidc/csrftoken"
 	"go.pinniped.dev/internal/oidc/provider"
@@ -45,7 +46,7 @@ func NewHandler(
 	stateDecoder, cookieDecoder oidc.Decoder,
 	redirectURI string,
 ) http.Handler {
-	return httperr.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
+	return securityheader.Wrap(httperr.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
 		state, err := validateRequest(r, stateDecoder, cookieDecoder)
 		if err != nil {
 			return err
@@ -108,7 +109,7 @@ func NewHandler(
 		oauthHelper.WriteAuthorizeResponse(w, authorizeRequester, authorizeResponder)
 
 		return nil
-	})
+	}))
 }
 
 func authcode(r *http.Request) string {