IPv6 구현

IPv6 Implementation for Net Module

Overview

Added comprehensive IPv6 support to the std/net.vais module, enabling network programming with both IPv4 and IPv6 protocols.

Implementation Date

2026-01-20

Components Added

1. Constants

C AF_INET6: i64 = 30          # IPv6 address family (macOS: 30, Linux: 10)
C IPPROTO_IPV6: i64 = 41      # IPv6 protocol
C IPV6_V6ONLY: i64 = 27       # IPv6-only socket option (macOS)
C SOCKADDR_IN6_SIZE: i64 = 28 # sockaddr_in6 structure size

2. sockaddr_in6 Structure Support

The IPv6 socket address structure (28 bytes):

  • sin6_family (2 bytes): Address family (AF_INET6)
  • sin6_port (2 bytes): Port number (network byte order)
  • sin6_flowinfo (4 bytes): IPv6 flow information
  • sin6_addr (16 bytes): 128-bit IPv6 address
  • sin6_scope_id (4 bytes): Scope ID for link-local addresses

Helper Functions

make_sockaddr_in6(host: *i8, port: i64) -> *sockaddr_in6

  • Creates an IPv6 socket address structure
  • Converts string IPv6 address to binary format using inet_pton(AF_INET6, ...)
  • Returns allocated pointer (caller must free)

make_sockaddr_any6(port: i64) -> *sockaddr_in6

  • Creates IPv6 wildcard address (::) for listening on all interfaces
  • Convenience wrapper around make_sockaddr_in6(0, port)

3. TcpListener IPv6 Support

TcpListener.bind6(port: i64) -> TcpListener

  • Creates and binds an IPv6 TCP listener
  • Sets SO_REUSEADDR option for address reuse
  • Listens on all IPv6 interfaces (::)
  • Supports dual-stack mode by default (accepts IPv4 connections as ::ffff:x.x.x.x)

C-Style API:

tcp_listen6(port: i64) -> i64  # Returns file descriptor

4. TcpStream IPv6 Support

TcpStream.connect6(host: *i8, port: i64) -> TcpStream

  • Connects to a remote IPv6 host
  • Supports standard IPv6 addresses:
    • Loopback: ::1
    • Link-local: fe80::1
    • Global unicast: 2001:db8::1
    • IPv4-mapped: ::ffff:192.0.2.1

C-Style API:

tcp_connect6(host: *i8, port: i64) -> i64  # Returns file descriptor

5. UdpSocket IPv6 Support

UdpSocket.new6() -> UdpSocket

  • Creates an unbound IPv6 UDP socket

UdpSocket.bind6(port: i64) -> UdpSocket

  • Creates and binds an IPv6 UDP socket to a port

socket.send_to6(data: *i8, len: i64, host: *i8, port: i64) -> i64

  • Sends data to an IPv6 address
  • Returns bytes sent or -1 on error

socket.recv_from6(buffer: *i8, len: i64, src_addr_out: *i8, src_port_out: *i64) -> i64

  • Receives data with source IPv6 address information
  • src_addr_out buffer should be at least 46 bytes (max IPv6 string length)
  • Extracts source address and port from received packet

C-Style API:

udp_bind6(port: i64) -> i64
udp_send_to6(socket_fd: i64, data: *i8, len: i64, host: *i8, port: i64) -> i64

6. Utility Functions

is_valid_ip6(host: *i8) -> i64

  • Validates IPv6 address string format
  • Returns 1 if valid, 0 otherwise
  • Uses inet_pton(AF_INET6, ...) for validation

Platform Considerations

macOS vs Linux

  • AF_INET6: macOS = 30, Linux = 10
  • Current implementation uses macOS value (30)
  • For cross-platform support, this should be detected at compile-time or runtime

Dual-Stack Behavior

  • By default, IPv6 sockets accept both IPv4 and IPv6 connections
  • IPv4 clients appear as IPv4-mapped IPv6 addresses: ::ffff:x.x.x.x
  • To force IPv6-only mode, set IPV6_V6ONLY socket option to 1

Examples Created

1. /examples/ipv6_test.vais

Comprehensive test suite demonstrating:

  • IPv6 address validation
  • sockaddr_in6 structure creation
  • TCP listener (IPv6)
  • TCP client connection attempts
  • UDP socket send/receive operations
  • C-style API usage

2. /examples/ipv6_dual_stack.vais

Demonstrates dual-stack functionality:

  • Creating listeners that accept both IPv4 and IPv6
  • Setting IPV6_V6ONLY for IPv6-only mode
  • Understanding IPv4-mapped IPv6 addresses

API Consistency

All IPv6 functions follow the naming pattern of existing IPv4 functions with a 6 suffix:

  • bind() → bind6()
  • connect() → connect6()
  • send_to() → send_to6()
  • recv_from() → recv_from6()
  • tcp_listen() → tcp_listen6()
  • tcp_connect() → tcp_connect6()
  • udp_bind() → udp_bind6()

Documentation

Updated Files

  1. std/net.vais: Added 200+ lines of IPv6 implementation
  2. ROADMAP.md: Marked IPv6 support as completed, added recent changes section
  3. docs/STDLIB.md: Added comprehensive networking section with IPv6 documentation
  4. Examples: Created ipv6_test.vais and ipv6_dual_stack.vais

Module Index

Added std/net to the standard library module index with key types: TcpListener, TcpStream, UdpSocket

Testing Recommendations

  1. IPv6 Address Validation: Test with various IPv6 formats
  2. Loopback Connections: Test TCP/UDP with ::1
  3. Dual-Stack Mode: Test IPv4 clients connecting to IPv6 sockets
  4. IPv6-Only Mode: Test with IPV6_V6ONLY set
  5. Link-Local Addresses: Test with fe80::1 (may require scope ID)
  6. Cross-Platform: Test on both macOS and Linux for AF_INET6 compatibility

Future Enhancements

  1. Auto-detect AF_INET6: Use platform detection instead of hardcoded value
  2. Scope ID Support: Better handling of link-local addresses with scope IDs
  3. IPv6 Flow Information: Support for sin6_flowinfo field
  4. Address Resolution: DNS resolution with getaddrinfo for both IPv4/IPv6
  5. Network Interface Enumeration: List available IPv6 interfaces

Summary

This implementation provides complete parity between IPv4 and IPv6 networking in the Vais standard library. All core socket operations (TCP listen/connect, UDP bind/send/receive) now support both protocols, enabling modern network applications that can work across the full Internet Protocol spectrum.