Fix IPv4 excludes and SOCKS5 UDP DNS handling

[FreemanZY]

Summary

Fix three related gaps in the Windows proxy path:

• IPv4 CIDR exclusions were parsed from configuration but were not applied consistently to TCP and UDP forwarding.
• The SOCKS5 UDP data socket was bound to loopback, preventing DNS forwarding and ordinary UDP relay traffic from reaching a remote proxy.
• DNS restoration preserved effective DHCP servers as static values instead of restoring the original automatic DNS mode.

Changes

• Apply global IPv4 exclusions to automatic rules and manual hijacks, and apply process-rule exclusions to the matching rule.
• Evaluate TCP exclusions before creating tracker entries.
• Snapshot UDP exclusion policy at socket registration and evaluate the actual network-order destination before creating a relay session.
• Bind SOCKS5 UDP sockets to the wildcard address and add actionable send-failure diagnostics.
• Preserve automatic versus manual DNS configuration across forwarder enable/disable cycles.
• Detect explicit DNS configuration through the interface NameServer registry value and reset automatic DNS with a valid empty NameServer string.
• Add component coverage for rule priority, manual hijacks, process-tree inheritance, UDP tracking, SOCKS5 UDP relay behavior, DNS state compatibility, and automatic/manual restoration.

Validation

• Release build completed successfully with MSBuild.
• Component test suite: 52 passed, 0 failed.
• Windows integration matrix: 58 passed, 0 failed across:
  • global IPv4 exclusion on/off
  • process-level IPv4 exclusion on/off
  • DNS forwarding on/off
  • TCP and UDP proxy/direct decisions
  • automatic and manual DNS restoration
• Final integration cleanup confirmed the original configuration, effective DNS servers, and DNS mode were restored.

Risks and limitations

• CIDR exclusion and DNS handling remain IPv4-only.
• Existing include CIDRs and port-filter behavior are unchanged.
• Existing TCP relay, process matching, proxy groups, and session lifecycle behavior are preserved.

[sonarqubecloud]

Quality Gate passed

Issues
16 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud