Improvements to web-fetch tool (#1030)

5 files changed, 292 insertions, 18 deletions

diff --git a/packages/core/src/tools/tools.ts b/packages/core/src/tools/tools.ts
index ced53995..e9fc042b 100644
--- a/packages/core/src/tools/tools.ts
+++ b/packages/core/src/tools/tools.ts
@@ -222,10 +222,19 @@ export interface ToolMcpConfirmationDetails {
   onConfirm: (outcome: ToolConfirmationOutcome) => Promise<void>;
 }
 
+export interface ToolInfoConfirmationDetails {
+  type: 'info';
+  title: string;
+  onConfirm: (outcome: ToolConfirmationOutcome) => Promise<void>;
+  prompt: string;
+  urls?: string[];
+}
+
 export type ToolCallConfirmationDetails =
   | ToolEditConfirmationDetails
   | ToolExecuteConfirmationDetails
-  | ToolMcpConfirmationDetails;
+  | ToolMcpConfirmationDetails
+  | ToolInfoConfirmationDetails;
 
 export enum ToolConfirmationOutcome {
   ProceedOnce = 'proceed_once',
diff --git a/packages/core/src/tools/web-fetch.test.ts b/packages/core/src/tools/web-fetch.test.ts
new file mode 100644
index 00000000..f4e3a652
--- /dev/null
+++ b/packages/core/src/tools/web-fetch.test.ts
@@ -0,0 +1,86 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { WebFetchTool } from './web-fetch.js';
+import { Config, ApprovalMode } from '../config/config.js';
+import { ToolConfirmationOutcome } from './tools.js';
+
+describe('WebFetchTool', () => {
+  const mockConfig = {
+    getApprovalMode: vi.fn(),
+    setApprovalMode: vi.fn(),
+  } as unknown as Config;
+
+  describe('shouldConfirmExecute', () => {
+    it('should return confirmation details with the correct prompt and urls', async () => {
+      const tool = new WebFetchTool(mockConfig);
+      const params = { prompt: 'fetch https://example.com' };
+      const confirmationDetails = await tool.shouldConfirmExecute(params);
+
+      expect(confirmationDetails).toEqual({
+        type: 'info',
+        title: 'Confirm Web Fetch',
+        prompt: 'fetch https://example.com',
+        urls: ['https://example.com'],
+        onConfirm: expect.any(Function),
+      });
+    });
+
+    it('should convert github urls to raw format', async () => {
+      const tool = new WebFetchTool(mockConfig);
+      const params = {
+        prompt:
+          'fetch https://github.com/google/gemini-react/blob/main/README.md',
+      };
+      const confirmationDetails = await tool.shouldConfirmExecute(params);
+
+      expect(confirmationDetails).toEqual({
+        type: 'info',
+        title: 'Confirm Web Fetch',
+        prompt:
+          'fetch https://github.com/google/gemini-react/blob/main/README.md',
+        urls: [
+          'https://raw.githubusercontent.com/google/gemini-react/main/README.md',
+        ],
+        onConfirm: expect.any(Function),
+      });
+    });
+
+    it('should return false if approval mode is AUTO_EDIT', async () => {
+      const tool = new WebFetchTool({
+        ...mockConfig,
+        getApprovalMode: () => ApprovalMode.AUTO_EDIT,
+      } as unknown as Config);
+      const params = { prompt: 'fetch https://example.com' };
+      const confirmationDetails = await tool.shouldConfirmExecute(params);
+
+      expect(confirmationDetails).toBe(false);
+    });
+
+    it('should call setApprovalMode when onConfirm is called with ProceedAlways', async () => {
+      const setApprovalMode = vi.fn();
+      const tool = new WebFetchTool({
+        ...mockConfig,
+        setApprovalMode,
+      } as unknown as Config);
+      const params = { prompt: 'fetch https://example.com' };
+      const confirmationDetails = await tool.shouldConfirmExecute(params);
+
+      if (
+        confirmationDetails &&
+        typeof confirmationDetails === 'object' &&
+        'onConfirm' in confirmationDetails
+      ) {
+        await confirmationDetails.onConfirm(
+          ToolConfirmationOutcome.ProceedAlways,
+        );
+      }
+
+      expect(setApprovalMode).toHaveBeenCalledWith(ApprovalMode.AUTO_EDIT);
+    });
+  });
+});
diff --git a/packages/core/src/tools/web-fetch.ts b/packages/core/src/tools/web-fetch.ts
index 6a6048fc..85491d01 100644
--- a/packages/core/src/tools/web-fetch.ts
+++ b/packages/core/src/tools/web-fetch.ts
@@ -6,10 +6,26 @@
 
 import { GroundingMetadata } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
-import { BaseTool, ToolResult } from './tools.js';
+import {
+  BaseTool,
+  ToolResult,
+  ToolCallConfirmationDetails,
+  ToolConfirmationOutcome,
+} from './tools.js';
 import { getErrorMessage } from '../utils/errors.js';
-import { Config } from '../config/config.js';
+import { Config, ApprovalMode } from '../config/config.js';
 import { getResponseText } from '../utils/generateContentResponseUtilities.js';
+import { fetchWithTimeout, isPrivateIp } from '../utils/fetch.js';
+import { convert } from 'html-to-text';
+
+const URL_FETCH_TIMEOUT_MS = 10000;
+const MAX_CONTENT_LENGTH = 100000;
+
+// Helper function to extract URLs from a string
+function extractUrls(text: string): string[] {
+  const urlRegex = /(https?:\/\/[^\s]+)/g;
+  return text.match(urlRegex) || [];
+}
 
 // Interfaces for grounding metadata (similar to web-search.ts)
 interface GroundingChunkWeb {
@@ -52,7 +68,7 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
     super(
       WebFetchTool.Name,
       'WebFetch',
-      "Processes content from URL(s) embedded in a prompt. Include up to 20 URLs and instructions (e.g., summarize, extract specific data) directly in the 'prompt' parameter.",
+      "Processes content from URL(s), including local and private network addresses (e.g., localhost), embedded in a prompt. Include up to 20 URLs and instructions (e.g., summarize, extract specific data) directly in the 'prompt' parameter.",
       {
         properties: {
           prompt: {
@@ -67,6 +83,71 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
     );
   }
 
+  private async executeFallback(
+    params: WebFetchToolParams,
+    signal: AbortSignal,
+  ): Promise<ToolResult> {
+    const urls = extractUrls(params.prompt);
+    if (urls.length === 0) {
+      return {
+        llmContent: 'Error: No URL found in the prompt for fallback.',
+        returnDisplay: 'Error: No URL found in the prompt for fallback.',
+      };
+    }
+    // For now, we only support one URL for fallback
+    let url = urls[0];
+
+    // Convert GitHub blob URL to raw URL
+    if (url.includes('github.com') && url.includes('/blob/')) {
+      url = url
+        .replace('github.com', 'raw.githubusercontent.com')
+        .replace('/blob/', '/');
+    }
+
+    try {
+      const response = await fetchWithTimeout(url, URL_FETCH_TIMEOUT_MS);
+      if (!response.ok) {
+        throw new Error(
+          `Request failed with status code ${response.status} ${response.statusText}`,
+        );
+      }
+      const html = await response.text();
+      const textContent = convert(html, {
+        wordwrap: false,
+        selectors: [
+          { selector: 'a', options: { ignoreHref: true } },
+          { selector: 'img', format: 'skip' },
+        ],
+      }).substring(0, MAX_CONTENT_LENGTH);
+
+      const geminiClient = this.config.getGeminiClient();
+      const fallbackPrompt = `The user requested the following: "${params.prompt}".
+
+I was unable to access the URL directly. Instead, I have fetched the raw content of the page. Please use the following content to answer the user's request. Do not attempt to access the URL again.
+
+---
+${textContent}
+---`;
+      const result = await geminiClient.generateContent(
+        [{ role: 'user', parts: [{ text: fallbackPrompt }] }],
+        {},
+        signal,
+      );
+      const resultText = getResponseText(result) || '';
+      return {
+        llmContent: resultText,
+        returnDisplay: `Content for ${url} processed using fallback fetch.`,
+      };
+    } catch (e) {
+      const error = e as Error;
+      const errorMessage = `Error during fallback fetch for ${url}: ${error.message}`;
+      return {
+        llmContent: `Error: ${errorMessage}`,
+        returnDisplay: `Error: ${errorMessage}`,
+      };
+    }
+  }
+
   validateParams(params: WebFetchToolParams): string | null {
     if (
       this.schema.parameters &&
@@ -97,6 +178,43 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
     return `Processing URLs and instructions from prompt: "${displayPrompt}"`;
   }
 
+  async shouldConfirmExecute(
+    params: WebFetchToolParams,
+  ): Promise<ToolCallConfirmationDetails | false> {
+    if (this.config.getApprovalMode() === ApprovalMode.AUTO_EDIT) {
+      return false;
+    }
+
+    const validationError = this.validateParams(params);
+    if (validationError) {
+      return false;
+    }
+
+    // Perform GitHub URL conversion here to differentiate between user-provided
+    // URL and the actual URL to be fetched.
+    const urls = extractUrls(params.prompt).map((url) => {
+      if (url.includes('github.com') && url.includes('/blob/')) {
+        return url
+          .replace('github.com', 'raw.githubusercontent.com')
+          .replace('/blob/', '/');
+      }
+      return url;
+    });
+
+    const confirmationDetails: ToolCallConfirmationDetails = {
+      type: 'info',
+      title: `Confirm Web Fetch`,
+      prompt: params.prompt,
+      urls,
+      onConfirm: async (outcome: ToolConfirmationOutcome) => {
+        if (outcome === ToolConfirmationOutcome.ProceedAlways) {
+          this.config.setApprovalMode(ApprovalMode.AUTO_EDIT);
+        }
+      },
+    };
+    return confirmationDetails;
+  }
+
   async execute(
     params: WebFetchToolParams,
     signal: AbortSignal,
@@ -110,6 +228,14 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
     }
 
     const userPrompt = params.prompt;
+    const urls = extractUrls(userPrompt);
+    const url = urls[0];
+    const isPrivate = isPrivateIp(url);
+
+    if (isPrivate) {
+      return this.executeFallback(params, signal);
+    }
+
     const geminiClient = this.config.getGeminiClient();
 
     try {
@@ -120,7 +246,10 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
       );
 
       console.debug(
-        `[WebFetchTool] Full response for prompt "${userPrompt.substring(0, 50)}...":`,
+        `[WebFetchTool] Full response for prompt "${userPrompt.substring(
+          0,
+          50,
+        )}...":`,
         JSON.stringify(response, null, 2),
       );
 
@@ -138,7 +267,6 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
 
       // Error Handling
       let processingError = false;
-      let errorDetail = 'An unknown error occurred during content processing.';
 
       if (
         urlContextMeta?.urlMetadata &&
@@ -149,13 +277,10 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
         );
         if (allStatuses.every((s) => s !== 'URL_RETRIEVAL_STATUS_SUCCESS')) {
           processingError = true;
-          errorDetail = `All URL retrieval attempts failed. Statuses: ${allStatuses.join(', ')}. API reported: "${responseText || 'No additional detail.'}"`;
         }
       } else if (!responseText.trim() && !sources?.length) {
         // No URL metadata and no content/sources
         processingError = true;
-        errorDetail =
-          'No content was returned and no URL metadata was available to determine fetch status.';
       }
 
       if (
@@ -165,16 +290,10 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
       ) {
         // Successfully retrieved some URL (or no specific error from urlContextMeta), but no usable text or grounding data.
         processingError = true;
-        errorDetail =
-          'URL(s) processed, but no substantive content or grounding information was found.';
       }
 
       if (processingError) {
-        const errorText = `Failed to process prompt and fetch URL data. ${errorDetail}`;
-        return {
-          llmContent: `Error: ${errorText}`,
-          returnDisplay: `Error: ${errorText}`,
-        };
+        return this.executeFallback(params, signal);
       }
 
       const sourceListFormatted: string[] = [];
@@ -227,7 +346,10 @@ ${sourceListFormatted.join('\n')}`;
         returnDisplay: `Content processed from prompt.`,
       };
     } catch (error: unknown) {
-      const errorMessage = `Error processing web content for prompt "${userPrompt.substring(0, 50)}...": ${getErrorMessage(error)}`;
+      const errorMessage = `Error processing web content for prompt "${userPrompt.substring(
+        0,
+        50,
+      )}...": ${getErrorMessage(error)}`;
       console.error(errorMessage, error);
       return {
         llmContent: `Error: ${errorMessage}`,
diff --git a/packages/core/src/utils/fetch.ts b/packages/core/src/utils/fetch.ts
new file mode 100644
index 00000000..e78a3247
--- /dev/null
+++ b/packages/core/src/utils/fetch.ts
@@ -0,0 +1,57 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { getErrorMessage, isNodeError } from './errors.js';
+import { URL } from 'url';
+
+const PRIVATE_IP_RANGES = [
+  /^10\./,
+  /^127\./,
+  /^172\.(1[6-9]|2[0-9]|3[0-1])\./,
+  /^192\.168\./,
+  /^::1$/,
+  /^fc00:/,
+  /^fe80:/,
+];
+
+export class FetchError extends Error {
+  constructor(
+    message: string,
+    public code?: string,
+  ) {
+    super(message);
+    this.name = 'FetchError';
+  }
+}
+
+export function isPrivateIp(url: string): boolean {
+  try {
+    const hostname = new URL(url).hostname;
+    return PRIVATE_IP_RANGES.some((range) => range.test(hostname));
+  } catch (_e) {
+    return false;
+  }
+}
+
+export async function fetchWithTimeout(
+  url: string,
+  timeout: number,
+): Promise<Response> {
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => controller.abort(), timeout);
+
+  try {
+    const response = await fetch(url, { signal: controller.signal });
+    return response;
+  } catch (error) {
+    if (isNodeError(error) && error.code === 'ABORT_ERR') {
+      throw new FetchError(`Request timed out after ${timeout}ms`, 'ETIMEDOUT');
+    }
+    throw new FetchError(getErrorMessage(error));
+  } finally {
+    clearTimeout(timeoutId);
+  }
+}
diff --git a/packages/core/src/utils/getFolderStructure.test.ts b/packages/core/src/utils/getFolderStructure.test.ts
index 843bf493..63724ba8 100644
--- a/packages/core/src/utils/getFolderStructure.test.ts
+++ b/packages/core/src/utils/getFolderStructure.test.ts
@@ -38,8 +38,8 @@ const createDirent = (name: string, type: 'file' | 'dir'): FSDirent => ({
   isSymbolicLink: () => false,
   isFIFO: () => false,
   isSocket: () => false,
-  parentPath: '',
   path: '',
+  parentPath: '',
 });
 
 describe('getFolderStructure', () => {