fix: AWS credential signing http request - convert form to body (#14060)

Co-authored-by: Dana <152518854+dana-gill@users.noreply.github.com>

packages/nodes-base/credentials/Aws.credentials.ts

@@ -476,13 +476,29 @@ export class Aws implements ICredentialType {
 
 		path = endpoint.pathname + endpoint.search;
 
+		// ! aws4.sign *must* have the body to sign, but we might have .form instead of .body
+		const requestWithForm = requestOptions as unknown as { form?: Record<string, string> };
+		let bodyContent = body !== '' ? body : undefined;
+		let contentTypeHeader: string | undefined = undefined;
+		if (requestWithForm.form) {
+			const params = new URLSearchParams();
+			for (const key in requestWithForm.form) {
+				params.append(key, requestWithForm.form[key]);
+			}
+			bodyContent = params.toString();
+			contentTypeHeader = 'application/x-www-form-urlencoded';
+		}
+
 		const signOpts = {
 			...requestOptions,
-			headers: requestOptions.headers ?? {},
+			headers: {
+				...(requestOptions.headers ?? {}),
+				...(contentTypeHeader && { 'content-type': contentTypeHeader }),
+			},
 			host: endpoint.host,
 			method,
 			path,
-			body: body !== '' ? body : undefined,
+			body: bodyContent,
 			region,
 		} as Request;
 

packages/nodes-base/credentials/test/Aws.credentials.test.ts

@@ -139,5 +139,44 @@ describe('Aws Credential', () => {
 			expect(result.method).toBe('POST');
 			expect(result.url).toBe('https://iam.amazonaws.com/');
 		});
+
+		it('should handle an IRequestOptions object with form instead of body', async () => {
+			const result = await aws.authenticate({ ...credentials }, {
+				...requestOptions,
+				body: undefined,
+				form: {
+					Action: 'ListUsers',
+					Version: '2010-05-08',
+				},
+				baseURL: '',
+				url: 'https://iam.amazonaws.com',
+				host: 'iam.amazonaws.com',
+				path: '/',
+			} as IHttpRequestOptions);
+
+			expect(mockSign).toHaveBeenCalledWith(
+				{
+					...signOpts,
+					form: {
+						Action: 'ListUsers',
+						Version: '2010-05-08',
+					},
+					body: 'Action=ListUsers&Version=2010-05-08',
+					host: 'iam.amazonaws.com',
+					url: 'https://iam.amazonaws.com',
+					baseURL: '',
+					path: '/',
+					headers: {
+						'content-type': 'application/x-www-form-urlencoded',
+					},
+					// PR #14037 introduces region normalization for global endpoints
+					// This test works with or without the normalization
+					region: expect.stringMatching(/[a-z]{2}-[a-z]+-[0-9]+/),
+				},
+				securityHeaders,
+			);
+			expect(result.method).toBe('POST');
+			expect(result.url).toBe('https://iam.amazonaws.com/');
+		});
 	});
 });