fix: reject aborted requests with AbortSignal.reason

.changeset/fix-abort-signal-reason.md

@@ -0,0 +1,6 @@
+---
+"@smithy/node-http-handler": patch
+"@smithy/fetch-http-handler": patch
+---
+
+fix: reject aborted requests with AbortSignal.reason instead of a generic Error

packages/fetch-http-handler/src/fetch-http-handler.ts

@@ -87,8 +87,7 @@ export class FetchHttpHandler implements HttpHandler<FetchHttpHandlerOptions> {
 
     // if the request was already aborted, prevent doing extra work
     if (abortSignal?.aborted) {
-      const abortError = new Error("Request aborted");
-      abortError.name = "AbortError";
+      const abortError = buildAbortError(abortSignal);
       return Promise.reject(abortError);
     }
 
@@ -185,8 +184,7 @@ export class FetchHttpHandler implements HttpHandler<FetchHttpHandlerOptions> {
       raceOfPromises.push(
         new Promise<never>((resolve, reject) => {
           const onAbort = () => {
-            const abortError = new Error("Request aborted");
-            abortError.name = "AbortError";
+            const abortError = buildAbortError(abortSignal);
             reject(abortError);
           };
           if (typeof (abortSignal as AbortSignal).addEventListener === "function") {
@@ -216,3 +214,20 @@ export class FetchHttpHandler implements HttpHandler<FetchHttpHandlerOptions> {
     return this.config ?? {};
   }
 }
+
+/**
+ * Builds an abort error, using the AbortSignal's reason if available.
+ */
+function buildAbortError(abortSignal?: { reason?: unknown }): Error {
+  if (abortSignal?.reason) {
+    if (abortSignal.reason instanceof Error) {
+      return abortSignal.reason;
+    }
+    const abortError = new Error(String(abortSignal.reason));
+    abortError.name = "AbortError";
+    return abortError;
+  }
+  const abortError = new Error("Request aborted");
+  abortError.name = "AbortError";
+  return abortError;
+}

packages/node-http-handler/src/node-http-handler.spec.ts

@@ -410,6 +410,52 @@ describe("NodeHttpHandler", () => {
     });
   });
 
+  describe("abort signal handling", () => {
+    it("rejects with AbortSignal.reason when signal is already aborted with a custom reason", async () => {
+      const nodeHttpHandler = new NodeHttpHandler();
+      const customReason = new Error("custom abort reason");
+      customReason.name = "CustomAbortError";
+      const abortController = new AbortController();
+      abortController.abort(customReason);
+
+      await expect(
+        nodeHttpHandler.handle({ protocol: "http:", hostname: "host", path: "/", headers: {} } as any, {
+          abortSignal: abortController.signal as any,
+        })
+      ).rejects.toBe(customReason);
+    });
+
+    it("rejects with default AbortError when signal has no reason", async () => {
+      const nodeHttpHandler = new NodeHttpHandler();
+      const signal = {
+        aborted: true,
+        onabort: null,
+      };
+
+      await expect(
+        nodeHttpHandler.handle({ protocol: "http:", hostname: "host", path: "/", headers: {} } as any, {
+          abortSignal: signal as any,
+        })
+      ).rejects.toThrow("Request aborted");
+    });
+
+    it("rejects with string reason wrapped in an Error", async () => {
+      const nodeHttpHandler = new NodeHttpHandler();
+      const abortController = new AbortController();
+      abortController.abort("string reason");
+
+      try {
+        await nodeHttpHandler.handle({ protocol: "http:", hostname: "host", path: "/", headers: {} } as any, {
+          abortSignal: abortController.signal as any,
+        });
+        expect.unreachable("should have thrown");
+      } catch (e: any) {
+        expect(e.message).toBe("string reason");
+        expect(e.name).toBe("AbortError");
+      }
+    });
+  });
+
   describe("checkSocketUsage", () => {
     beforeEach(() => {
       vi.spyOn(console, "warn").mockImplementation(vi.fn() as any);

packages/node-http-handler/src/node-http-handler.ts

@@ -196,8 +196,7 @@ or increase socketAcquisitionWarningTimeout=(millis) in the NodeHttpHandler conf
 
       // if the request was already aborted, prevent doing extra work
       if (abortSignal?.aborted) {
-        const abortError = new Error("Request aborted");
-        abortError.name = "AbortError";
+        const abortError = buildAbortError(abortSignal);
         reject(abortError);
         return;
       }
@@ -294,8 +293,7 @@ or increase socketAcquisitionWarningTimeout=(millis) in the NodeHttpHandler conf
         const onAbort = () => {
           // ensure request is destroyed
           req.destroy();
-          const abortError = new Error("Request aborted");
-          abortError.name = "AbortError";
+          const abortError = buildAbortError(abortSignal);
           reject(abortError);
         };
         if (typeof (abortSignal as AbortSignal).addEventListener === "function") {
@@ -354,3 +352,20 @@ or increase socketAcquisitionWarningTimeout=(millis) in the NodeHttpHandler conf
     return this.config ?? {};
   }
 }
+
+/**
+ * Builds an abort error, using the AbortSignal's reason if available.
+ */
+function buildAbortError(abortSignal?: { reason?: unknown }): Error {
+  if (abortSignal?.reason) {
+    if (abortSignal.reason instanceof Error) {
+      return abortSignal.reason;
+    }
+    const abortError = new Error(String(abortSignal.reason));
+    abortError.name = "AbortError";
+    return abortError;
+  }
+  const abortError = new Error("Request aborted");
+  abortError.name = "AbortError";
+  return abortError;
+}

packages/node-http-handler/src/node-http2-handler.ts

@@ -120,8 +120,7 @@ export class NodeHttp2Handler implements HttpHandler<NodeHttp2HandlerOptions> {
       // if the request was already aborted, prevent doing extra work
       if (abortSignal?.aborted) {
         fulfilled = true;
-        const abortError = new Error("Request aborted");
-        abortError.name = "AbortError";
+        const abortError = buildAbortError(abortSignal);
         reject(abortError);
         return;
       }
@@ -194,8 +193,7 @@ export class NodeHttp2Handler implements HttpHandler<NodeHttp2HandlerOptions> {
       if (abortSignal) {
         const onAbort = () => {
           req.close();
-          const abortError = new Error("Request aborted");
-          abortError.name = "AbortError";
+          const abortError = buildAbortError(abortSignal);
           rejectWithDestroy(abortError);
         };
         if (typeof (abortSignal as AbortSignal).addEventListener === "function") {
@@ -261,3 +259,20 @@ export class NodeHttp2Handler implements HttpHandler<NodeHttp2HandlerOptions> {
     }
   }
 }
+
+/**
+ * Builds an abort error, using the AbortSignal's reason if available.
+ */
+function buildAbortError(abortSignal?: { reason?: unknown }): Error {
+  if (abortSignal?.reason) {
+    if (abortSignal.reason instanceof Error) {
+      return abortSignal.reason;
+    }
+    const abortError = new Error(String(abortSignal.reason));
+    abortError.name = "AbortError";
+    return abortError;
+  }
+  const abortError = new Error("Request aborted");
+  abortError.name = "AbortError";
+  return abortError;
+}