[core-rest-pipeline] Preserve header casing

sdk/core/core-rest-pipeline/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Features Added
 
+- Changed behavior when sending HTTP headers to preserve the original casing of header names. Iterating over `HttpHeaders` now keeps the original name casing. There is also a new `preserveCase` option for `HttpHeaders.toJSON()`. See [PR #18517](https://github.com/Azure/azure-sdk-for-js/pull/18517)
+
 ### Breaking Changes
 
 ### Bugs Fixed

sdk/core/core-rest-pipeline/review/core-rest-pipeline.api.md

@@ -126,7 +126,9 @@ export interface HttpHeaders extends Iterable<[string, string]> {
     get(name: string): string | undefined;
     has(name: string): boolean;
     set(name: string, value: string | number | boolean): void;
-    toJSON(): RawHttpHeaders;
+    toJSON(options?: {
+        preserveCase?: boolean;
+    }): RawHttpHeaders;
 }
 
 // @public

sdk/core/core-rest-pipeline/src/httpHeaders.ts

@@ -3,15 +3,26 @@
 
 import { HttpHeaders, RawHttpHeaders, RawHttpHeadersInput } from "./interfaces";
 
+interface HeaderEntry {
+  name: string;
+  value: string;
+}
+
 function normalizeName(name: string): string {
   return name.toLowerCase();
 }
 
+function* headerIterator(map: Map<string, HeaderEntry>): IterableIterator<[string, string]> {
+  for (const entry of map.values()) {
+    yield [entry.name, entry.value];
+  }
+}
+
 class HttpHeadersImpl implements HttpHeaders {
-  private readonly _headersMap: Map<string, string>;
+  private readonly _headersMap: Map<string, HeaderEntry>;
 
   constructor(rawHeaders?: RawHttpHeaders | RawHttpHeadersInput) {
-    this._headersMap = new Map<string, string>();
+    this._headersMap = new Map<string, HeaderEntry>();
     if (rawHeaders) {
       for (const headerName of Object.keys(rawHeaders)) {
         this.set(headerName, rawHeaders[headerName]);
@@ -26,7 +37,7 @@ class HttpHeadersImpl implements HttpHeaders {
    * @param value - The value of the header to set.
    */
   public set(name: string, value: string | number | boolean): void {
-    this._headersMap.set(normalizeName(name), String(value));
+    this._headersMap.set(normalizeName(name), { name, value: String(value) });
   }
 
   /**
@@ -35,7 +46,7 @@ class HttpHeadersImpl implements HttpHeaders {
    * @param name - The name of the header. This value is case-insensitive.
    */
   public get(name: string): string | undefined {
-    return this._headersMap.get(normalizeName(name));
+    return this._headersMap.get(normalizeName(name))?.value;
   }
 
   /**
@@ -57,26 +68,33 @@ class HttpHeadersImpl implements HttpHeaders {
   /**
    * Get the JSON object representation of this HTTP header collection.
    */
-  public toJSON(): RawHttpHeaders {
+  public toJSON(options: { preserveCase?: boolean } = {}): RawHttpHeaders {
     const result: RawHttpHeaders = {};
-    for (const [key, value] of this._headersMap) {
-      result[key] = value;
+    if (options.preserveCase) {
+      for (const entry of this._headersMap.values()) {
+        result[entry.name] = entry.value;
+      }
+    } else {
+      for (const [normalizedName, entry] of this._headersMap) {
+        result[normalizedName] = entry.value;
+      }
     }
+
     return result;
   }
 
   /**
    * Get the string representation of this HTTP header collection.
    */
   public toString(): string {
-    return JSON.stringify(this.toJSON());
+    return JSON.stringify(this.toJSON({ preserveCase: true }));
   }
 
   /**
    * Iterate over tuples of header [name, value] pairs.
    */
   [Symbol.iterator](): Iterator<[string, string]> {
-    return this._headersMap.entries();
+    return headerIterator(this._headersMap);
   }
 }
 

sdk/core/core-rest-pipeline/src/interfaces.ts

@@ -44,7 +44,7 @@ export interface HttpHeaders extends Iterable<[string, string]> {
    * Accesses a raw JS object that acts as a simple map
    * of header names to values.
    */
-  toJSON(): RawHttpHeaders;
+  toJSON(options?: { preserveCase?: boolean }): RawHttpHeaders;
 }
 
 /**

sdk/core/core-rest-pipeline/src/nodeHttpClient.ts

@@ -208,7 +208,7 @@ class NodeHttpClient implements HttpClient {
       path: `${url.pathname}${url.search}`,
       port: url.port,
       method: request.method,
-      headers: request.headers.toJSON()
+      headers: request.headers.toJSON({ preserveCase: true })
     };
 
     return new Promise<http.IncomingMessage>((resolve, reject) => {

sdk/core/core-rest-pipeline/test/httpHeaders.spec.ts

@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+import { assert } from "chai";
+import { createHttpHeaders } from "../src/httpHeaders";
+
+describe("HttpHeaders", () => {
+  it("toJSON() should use normalized header names", () => {
+    const rawHeaders = {
+      lowercase: "lower case value",
+      camelCase: "camel case value",
+      ALLUPPERCASE: "all upper case value"
+    };
+    const normalizedHeaders = {
+      lowercase: "lower case value",
+      camelcase: "camel case value",
+      alluppercase: "all upper case value"
+    };
+    const headers = createHttpHeaders(rawHeaders);
+
+    assert.deepStrictEqual(headers.toJSON(), normalizedHeaders);
+  });
+
+  it("toJSON({preserveCase: true}) should keep the original header names", () => {
+    const rawHeaders = {
+      lowercase: "lower case value",
+      camelCase: "camel case value",
+      ALLUPPERCASE: "all upper case value"
+    };
+    const headers = createHttpHeaders(rawHeaders);
+
+    assert.deepStrictEqual(headers.toJSON({ preserveCase: true }), rawHeaders);
+  });
+
+  it("iteration should use original header names", () => {
+    const rawHeaders = {
+      lowercase: "lower case value",
+      camelCase: "camel case value",
+      ALLUPPERCASE: "all upper case value"
+    };
+    const headers = createHttpHeaders(rawHeaders);
+
+    for (const [name, value] of headers) {
+      assert.include(rawHeaders, { [name]: value });
+    }
+  });
+});

sdk/identity/identity/src/credentials/managedIdentityCredential/fabricMsi.ts

@@ -72,7 +72,7 @@ function prepareRequestOptions(
     method: "GET",
     headers: createHttpHeaders({
       Accept: "application/json",
-      Secret: process.env.IDENTITY_HEADER
+      secret: process.env.IDENTITY_HEADER
     })
   };
 }

sdk/identity/identity/test/internal/node/managedIdentityCredential.spec.ts

@@ -434,7 +434,7 @@ describe("ManagedIdentityCredential", function() {
         "URL does not start with expected host and path"
       );
 
-      assert.equal(authRequest.headers.authorization, `Basic ${key}`);
+      assert.equal(authRequest.headers.Authorization, `Basic ${key}`);
       if (authDetails.result!.token) {
         // We use Date.now underneath.
         assert.ok(authDetails.result!.expiresOnTimestamp);