SwitchyMalaccamax

PAC Export Feature

Export profiles as PAC scripts — Generate standards-compliant .pac files for use in browsers or proxy systems using File System Access API.

Overview

Implemented PAC (Proxy Auto-Config) script export functionality, achieving feature parity with ZeroOmega’s omega-pac module. Users can export configured profiles as PAC scripts for use in browsers or proxy systems.

Implementation

Core Module: src/core/pac/pac-generator.ts

Main Function:

generatePacScript(profile: Profile, allProfiles: Profile[]): string

Supported Profile Types:

Profile Type Status Description
FixedProfile ✅ Single proxy with optional bypass rules
SwitchProfile ✅ Rule-based switching with conditions
DirectProfile ✅ Returns “DIRECT” connection
SystemProfile ✅ Returns “DIRECT” (system proxy not applicable in PAC)
PacProfile ⏳ Returns original PAC URL (future enhancement)

Supported Condition Types:

All 7 condition types from the schema:

Condition Type PAC Function
HostWildcard shExpMatch(host, pattern)
UrlWildcard shExpMatch(url, pattern)
HostRegex JavaScript RegExp matching on host
UrlRegex JavaScript RegExp matching on URL
Keyword Simple substring search in URL
HostLevels Domain level counting
Bypass For fixed profiles with bypass rules

Special Features:

Feature Implementation
CIDR notation 192.168.0.0/16 → isInNet(host, "192.168.0.0", "255.255.0.0")
Proxy protocol mapping HTTP→PROXY, HTTPS→HTTPS, SOCKS4→SOCKS, SOCKS5→SOCKS5
Wildcard escaping Converts user-friendly wildcards to PAC-safe patterns
Minification Removes comments and whitespace for production use

UI Integration: src/options/OptionsApp.vue

Location: Profile Detail View → Action buttons (between Edit and Delete)

Button:

<button
  v-if="selectedProfile.profileType === 'FixedProfile' || selectedProfile.profileType === 'SwitchProfile'"
  @click="exportProfileAsPac(selectedProfile)"
  class="px-3 py-1.5 text-[12px] font-medium rounded-md bg-blue-100 dark:bg-blue-950/30 text-blue-700 dark:text-blue-400"
  title="Export as PAC script"
>
  <Download class="h-3.5 w-3.5" />
  Export PAC
</button>

Export Function:

import { saveBlobToFile } from '@/lib/fileSaver';

async function exportProfileAsPac(profile: Profile) {
  // 1. Generate PAC script using pac-generator module
  const pacScript = generatePacScript(profile, profiles.value);

  // 2. Create downloadable blob
  const blob = new Blob([pacScript], { type: 'application/x-ns-proxy-autoconfig' });

  // 3. Save file (File System Access API with anchor fallback)
  const safeName = profile.name.replace(/[^a-zA-Z0-9-_]/g, '_');
  const filename = `${safeName}.pac`;

  try {
    await saveBlobToFile(blob, filename, 'application/x-ns-proxy-autoconfig');
    toastRef.value?.success(`PAC script exported: ${filename}`, 'Exported', 3000);
  } catch (err) {
    // User cancelled or error - handle gracefully
    if (err && (err.name === 'AbortError' || err.message?.includes('cancelled'))) {
      toastRef.value?.info('Export cancelled', 'Cancelled');
    } else {
      toastRef.value?.error('Failed to export PAC script', 'Error');
      console.error('Export failed', err);
    }
  }
}

Usage

For Users

  1. Navigate to Settings → Profiles
  2. Select a profile (Fixed or Switch type)
  3. Click Export PAC button (blue, between Edit and Delete)
  4. Save file dialog prompts for destination and filename
  5. Use the PAC file in:
    • Browser proxy settings (Chrome, Firefox, etc.)
    • System proxy configuration
    • Corporate proxy systems
    • Network testing tools

Example Output

Fixed Profile with Bypass:

function FindProxyForURL(url, host) {
  // Direct access for bypass rules
  if (shExpMatch(host, "*.local")) return "DIRECT";
  if (shExpMatch(host, "localhost")) return "DIRECT";

  // Fixed proxy
  return "PROXY proxy.example.com:8080";
}

Switch Profile with Rules:

function FindProxyForURL(url, host) {
  // Rule: Work Sites
  if (shExpMatch(host, "*.company.com")) {
    return "PROXY corporate-proxy:3128";
  }

  // Rule: Streaming
  if (shExpMatch(host, "*.netflix.com") || shExpMatch(host, "*.youtube.com")) {
    return "SOCKS5 streaming-proxy:1080";
  }

  // Default fallback
  return "DIRECT";
}

Testing

Manual Testing

  1. Build extension: npm run build
  2. Load in Chrome: chrome://extensions → Load unpacked → Select dist/
  3. Open extension options
  4. Create/select a Fixed or Switch profile
  5. Click Export PAC
  6. Save file dialog appears; choose destination and save .pac file
  7. Verify saved .pac file opens in text editor with expected FindProxyForURL logic
  8. Check PAC syntax is valid JavaScript

Automated Tests

Unit tests for file save helper: tests/lib/fileSaver.spec.ts

PAC Validation

# Test PAC file in browser
1. Open chrome://net-internals/#proxy
2. Check "Use custom proxy configuration"
3. Enter: file:///path/to/exported.pac
4. Test URLs to verify routing

Technical Details

File Structure

Path Description
src/core/pac/pac-generator.ts Core PAC generation logic (345 lines)
src/options/OptionsApp.vue UI integration
src/lib/fileSaver.ts File save helper with File System Access API

Dependencies

Dependency Usage
Native Blob API Create downloadable content
URL.createObjectURL() Generate blob URLs
File System Access API Native save dialog (progressive enhancement)
src/lib/fileSaver.ts saveBlobToFile() helper
TypeScript types @/core/schema

Security Considerations

Measure Description
Filename sanitization Prevents path traversal
Regex validation Handled by existing regexSafe.ts
Browser sandbox PAC scripts run in browser sandbox
No eval() No dynamic code execution
Permissions No downloads permission required; uses File System Access API with anchor fallback

Future Enhancements

Phase 2 (Optional)

Advanced Features

Status

Status Description
✅ COMPLETE PAC export fully functional
✅ TESTED Core logic, UI integration, build successful
This site is open source. Improve this page.