fix #6949: prevent RangeError when using large Buffers in axios requests

[manishsahanidev]

Description

This PR fixes a critical RangeError that occurs when using large Buffers (>100-200MB) as request data in axios. The error was caused by calling Object.keys() on Buffer instances during configuration merging, which attempts to enumerate every byte as a key.

Problem

When axios processes large Buffer data, several utility functions would call Object.keys() on the Buffer:

// This would crash with large Buffers
function isEmptyObject(val) {
  return val && Object.keys(val).length === 0 && Object.getPrototypeOf(val) === Object.prototype;
}

Error: RangeError: Invalid array length when Buffer size exceeds ~100-200MB

Solution

Added Buffer checks to prevent Object.keys() from being called on Buffer instances in:

• ✅ isEmptyObject() - Returns false for all Buffers (not empty objects)
• ✅ forEach() - Skips iteration for Buffers
• ✅ findKey() - Returns null for Buffers
• ✅ toJSONObject() - Returns Buffer as-is without processing

Changes Made

1. Enhanced isEmptyObject function

const isEmptyObject = (val) => {
  // Early return for non-objects or Buffers to prevent RangeError
  if (!isObject(val) || isBuffer(val)) {
    return false;
  }
  
  try {
    return Object.keys(val).length === 0 && Object.getPrototypeOf(val) === Object.prototype;
  } catch (e) {
    // Fallback for any other objects that might cause RangeError with Object.keys()
    return false;
  }
}

2. Enhanced forEach function

function forEach(obj, fn, {allOwnKeys = false} = {}) {
  // ... existing code ...
  } else {
    // Buffer check to prevent RangeError
    if (isBuffer(obj)) {
      return;
    }
    // ... rest of object iteration ...
  }
}

3. Enhanced findKey function

function findKey(obj, key) {
  if (isBuffer(obj)){
    return null;
  }
  // ... rest of function ...
}

4. Enhanced toJSONObject function

const toJSONObject = (obj) => {
  const visit = (source, i) => {
    if (isObject(source)) {
      // ... existing checks ...
      
      // Buffer check to prevent RangeError
      if (isBuffer(source)) {
        return source;
      }
      
      // ... rest of processing ...
    }
    return source;
  }
  return visit(obj, 0);
}

Test Coverage

Added comprehensive tests in test/unit/utils/utils.js:

describe('Buffer RangeError Fix', function () {
  it('should handle large Buffer in isEmptyObject without RangeError', function () {
    const largeBuffer = Buffer.alloc(1024 * 1024 * 200); // 200MB
    const result = utils.isEmptyObject(largeBuffer);
    assert.strictEqual(result, false);
  });

  it('should handle large Buffer in forEach without RangeError', function () {
    const largeBuffer = Buffer.alloc(1024 * 1024 * 200); // 200MB
    let count = 0;
    utils.forEach(largeBuffer, () => count++);
    assert.strictEqual(count, 0); // Should be skipped
  });

  it('should handle large Buffer in findKey without RangeError', function () {
    const largeBuffer = Buffer.alloc(1024 * 1024 * 200); // 200MB
    const result = utils.findKey(largeBuffer, 'test');
    assert.strictEqual(result, null);
  });
});

Reproduction Case

Before (throws RangeError):

import axios from 'axios'

const buffer = Buffer.alloc(1024 * 1024 * 200) // 200 MB buffer
await axios({
  method: 'POST',
  url: 'http://localhost:8080',
  data: buffer
})
// RangeError: Invalid array length

After (works correctly):

import axios from 'axios'

const buffer = Buffer.alloc(1024 * 1024 * 200) // 200 MB buffer
await axios({
  method: 'POST',
  url: 'http://localhost:8080',  
  data: buffer
})
// ✅ Works without error

Backward Compatibility

• ✅ No breaking changes
• ✅ All existing functionality preserved
• ✅ Performance impact minimal (fast Buffer checks)
• ✅ Only affects Buffer handling behavior

Impact

This fix enables axios to handle large file uploads and binary data processing in Node.js environments without crashes, which is essential for:

• File upload services
• Image/video processing APIs
• Binary data streaming
• Large payload handling

Testing

• ✅ All existing tests pass
• ✅ New Buffer-specific tests added
• ✅ Manual testing with 200MB+ Buffers
• ✅ Integration testing with real HTTP requests

Closes #[#6949]

[jasonsaayman]

this looks great to me

[github-actions]

Hi, @manishsahanidev! This PR has been published in v1.11.0 release. Thank you for your contribution ❤️!