Preserve case of user-provided http headers in request node

Fixes #3081

packages/node_modules/@node-red/nodes/core/network/21-httprequest.js

@@ -171,8 +171,23 @@ in your Node-RED user directory (${RED.settings.userDir}).
                     opts.timeout = msg.requestTimeout;
                 }
             }
+            const originalHeaderMap = {};
 
             opts.hooks = {
+                beforeRequest: [
+                    options => {
+                        // Whilst HTTP headers are meant to be case-insensitive,
+                        // in the real world, there are servers that aren't so compliant.
+                        // GOT will lower case all headers given a chance, so we need
+                        // to restore the case of any headers the user has set.
+                        Object.keys(options.headers).forEach(h => {
+                            if (originalHeaderMap[h] && originalHeaderMap[h] !== h) {
+                                options.headers[originalHeaderMap[h]] = options.headers[h];
+                                delete options.headers[h];
+                            }
+                        })
+                    }
+                ],
                 beforeRedirect: [
                     (options, response) => {
                         let redirectInfo = {
@@ -283,7 +298,7 @@ in your Node-RED user directory (${RED.settings.userDir}).
                             })
                             if (normalisedHeaders['www-authenticate']) {
                                 let authHeader = buildDigestHeader(digestCreds.user,digestCreds.password, options.method, requestUrl.pathname, normalisedHeaders['www-authenticate'])
-                                options.headers.authorization = authHeader;
+                                options.headers.Authorization = authHeader;
                             }
                             sentCreds = true;
                             return retry(options);
@@ -439,6 +454,14 @@ in your Node-RED user directory (${RED.settings.userDir}).
                     opts.https = { rejectUnauthorized: msg.rejectUnauthorized };
                 }
             }
+
+            // Now we have established all of our own headers, take a snapshot
+            // of their case so we can restore it prior to the request being sent.
+            if (opts.headers) {
+                Object.keys(opts.headers).forEach(h => {
+                    originalHeaderMap[h.toLowerCase()] = h
+                })
+            }
             got(url,opts).then(res => {
                 msg.statusCode = res.statusCode;
                 msg.headers = res.headers;

test/nodes/core/network/21-httprequest_spec.js

@@ -270,6 +270,16 @@ describe('HTTP Request Node', function() {
         testApp.get('/returnError/:code', function(req,res) {
             res.status(parseInt(req.params.code)).json({gotError:req.params.code});
         })
+
+        testApp.get('/rawHeaders', function(req,res) {
+            const result = {};
+            for (let i=0;i<req.rawHeaders.length;i++) {
+                result[req.rawHeaders[i]] = req.rawHeaders[i+1]
+            }
+            res.json({
+                headers:result
+            });
+        })
         startServer(function(err) {
             if (err) {
                 done(err);
@@ -1348,6 +1358,8 @@ describe('HTTP Request Node', function() {
         });
 
         it('should convert all HTTP headers into lower case', function(done) {
+            // This is a bad test. Express lower-cases headers in the `req.headers` object,
+            // so this is actually testing express, not the original request.
             var flow = [{id:"n1",type:"http request",wires:[["n2"]],method:"POST",ret:"obj",url:getTestURL('/postInspect')},
                 {id:"n2", type:"helper"}];
             helper.load(httpRequestNode, flow, function() {
@@ -1369,6 +1381,26 @@ describe('HTTP Request Node', function() {
             });
         });
 
+        it('should keep HTTP header case as provided by the user', function(done) {
+            var flow = [{id:"n1",type:"http request",wires:[["n2"]],method:"GET",ret:"obj",url:getTestURL('/rawHeaders')},
+                {id:"n2", type:"helper"}];
+            helper.load(httpRequestNode, flow, function() {
+                var n1 = helper.getNode("n1");
+                var n2 = helper.getNode("n2");
+                n2.on("input", function(msg) {
+                    try {
+                        msg.should.have.property('statusCode',200);
+                        msg.payload.should.have.property('headers');
+                        msg.payload.headers.should.have.property('Content-Type').which.startWith('text/plain');
+                        msg.payload.headers.should.have.property('X-Test-HEAD', "foo");
+                        done();
+                    } catch(err) {
+                        done(err);
+                    }
+                });
+                n1.receive({payload:"foo", headers: { 'Content-Type':'text/plain', "X-Test-HEAD": "foo"}});
+            });
+        });
         it('should receive HTTP header', function(done) {
             var flow = [{id:"n1",type:"http request",wires:[["n2"]],method:"GET",ret:"txt",url:getTestURL('/headersInspect')},
                 {id:"n2", type:"helper"}];