Add proxySafe flag to middleware.

src/handlers/requestHandler.js

@@ -710,6 +710,9 @@ function requestHandler(req, res) {
   // Call the next middleware function
   const next = () => {
     const currentMiddleware = middleware[index++];
+    while (req.isProxy && currentMiddleware && !currentMiddleware.proxySafe) {
+      currentMiddleware = middleware[index++];
+    }
     if (currentMiddleware) {
       try {
         currentMiddleware(req, res, logFacilities, config, next);

src/middleware/blocklist.js

@@ -51,3 +51,5 @@ module.exports.commands = {
     }
   },
 };
+
+module.exports.proxySafe = true;

src/middleware/checkForbiddenPaths.js

@@ -111,3 +111,5 @@ module.exports = (req, res, logFacilities, config, next) => {
 
   next();
 };
+
+module.exports.proxySafe = true;

src/middleware/defaultHandlerChecks.js

@@ -37,3 +37,5 @@ module.exports = (req, res, logFacilities, config, next) => {
 
   next();
 };
+
+module.exports.proxySafe = true;

src/middleware/nonStandardCodesAndHttpAuthentication.js

@@ -462,3 +462,5 @@ module.exports.commands = {
     passCommand(args, log);
   },
 };
+
+module.exports.proxySafe = true;

src/middleware/redirectTrailingSlashes.js

@@ -32,3 +32,5 @@ module.exports = (req, res, logFacilities, config, next) => {
     next();
   }
 };
+
+module.exports.proxySafe = true;

src/middleware/redirects.js

@@ -79,3 +79,5 @@ module.exports = (req, res, logFacilities, config, next) => {
 
   next();
 };
+
+module.exports.proxySafe = true;

src/middleware/responseHeaders.js

@@ -12,3 +12,5 @@ module.exports = (req, res, logFacilities, config, next) => {
 
   next();
 };
+
+module.exports.proxySafe = true;

src/middleware/rewriteURL.js

@@ -153,3 +153,5 @@ module.exports = (req, res, logFacilities, config, next) => {
     next();
   });
 };
+
+module.exports.proxySafe = true;

src/middleware/staticFileServingAndDirectoryListings.js

@@ -990,3 +990,5 @@ module.exports = (req, res, logFacilities, config, next) => {
     }
   });
 };
+
+module.exports.proxySafe = true;

src/middleware/status.js

@@ -134,3 +134,5 @@ module.exports = (req, res, logFacilities, config, next) => {
   }
   next();
 };
+
+module.exports.proxySafe = true;

src/middleware/urlSanitizer.js

@@ -52,3 +52,5 @@ module.exports = (req, res, logFacilities, config, next) => {
 
   next();
 };
+
+module.exports.proxySafe = true;

src/middleware/webRootPostfixes.js

@@ -140,3 +140,5 @@ module.exports = (req, res, logFacilities, config, next) => {
 
   next();
 };
+
+module.exports.proxySafe = true;