Add preserveHeaderKeyCase Option

Author: pachirel

README.md

@@ -333,6 +333,7 @@ proxyServer.listen(8015);
 *  **ignorePath**: true/false, Default: false - specify whether you want to ignore the proxy path of the incoming request (note: you will have to append / manually if required).
 *  **localAddress**: Local interface string to bind for outgoing connections
 *  **changeOrigin**: true/false, Default: false - changes the origin of the host header to the target URL
+*  **preserveHeaderKeyCase**: true/false, Default: false - specify whether you want to keep letter case of response header key
 *  **auth**: Basic authentication i.e. 'user:password' to compute an Authorization header.
 *  **hostRewrite**: rewrites the location hostname on (201/301/302/307/308) redirects.
 *  **autoRewrite**: rewrites the location host/port on (201/301/302/307/308) redirects based on requested host/port. Default: false.

lib/http-proxy.js

@@ -35,6 +35,7 @@ function createProxyServer(options) {
    *    ignorePath: <true/false, Default: false - specify whether you want to ignore the proxy path of the incoming request>
    *    localAddress : <Local interface string to bind for outgoing connections>
    *    changeOrigin: <true/false, Default: false - changes the origin of the host header to the target URL>
+   *    preserveHeaderKeyCase: <true/false, Default: false - specify whether you want to keep letter case of response header key >
    *    auth   : Basic authentication i.e. 'user:password' to compute an Authorization header.
    *    hostRewrite: rewrites the location hostname on (301/302/307/308) redirects, Default: null.
    *    autoRewrite: rewrites the location host/port on (301/302/307/308) redirects based on requested host/port. Default: false.

lib/http-proxy/passes/web-outgoing.js

@@ -84,7 +84,8 @@ module.exports = { // <--
    */
   writeHeaders: function writeHeaders(req, res, proxyRes, options) {
     var rewriteCookieDomainConfig = options.cookieDomainRewrite,
-        rawHeaderKeyMap = {},
+        preserveHeaderKeyCase = options.preserveHeaderKeyCase,
+        rawHeaderKeyMap,
         setHeader = function(key, header) {
           if (header == undefined) return;
           if (rewriteCookieDomainConfig && key.toLowerCase() === 'set-cookie') {
@@ -99,7 +100,8 @@ module.exports = { // <--
 
     // message.rawHeaders is added in: v0.11.6
     // https://nodejs.org/api/http.html#http_message_rawheaders
-    if (proxyRes.rawHeaders != undefined) {
+    if (preserveHeaderKeyCase && proxyRes.rawHeaders != undefined) {
+      rawHeaderKeyMap = {};
       for (var i = 0; i < proxyRes.rawHeaders.length; i += 2) {
         var key = proxyRes.rawHeaders[i];
         rawHeaderKeyMap[key.toLowerCase()] = key;
@@ -108,7 +110,7 @@ module.exports = { // <--
 
     Object.keys(proxyRes.headers).forEach(function(key) {
       var header = proxyRes.headers[key];
-      if (preserveHeaderKeyCase) {
+      if (preserveHeaderKeyCase && rawHeaderKeyMap) {
         key = rawHeaderKeyMap[key] || key;
       }
       setHeader(key, header);

test/lib-http-proxy-test.js

@@ -130,7 +130,8 @@ describe('lib/http-proxy.js', function() {
     it('should make the request, handle response and finish it', function(done) {
       var ports = { source: gen.port, proxy: gen.port };
       var proxy = httpProxy.createProxyServer({
-        target: 'http://127.0.0.1:' + ports.source
+        target: 'http://127.0.0.1:' + ports.source,
+        preserveHeaderKeyCase: true
       }).listen(ports.proxy);
 
       var source = http.createServer(function(req, res) {