Method DialContext

polyamide/tun/netstack/tun.go:957–1053

(ctx context.Context, network, address string)

var protoSplitter = regexp.MustCompile(`^(tcp|udp|ping)(4|6)?$`)

func (tnet *Net) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
	if ctx == nil {
		panic("nil context")
	}
	var acceptV4, acceptV6 bool
	matches := protoSplitter.FindStringSubmatch(network)
	if matches == nil {
		return nil, &net.OpError{Op: "dial", Err: net.UnknownNetworkError(network)}
	} else if len(matches[2]) == 0 {
		acceptV4 = true
		acceptV6 = true
	} else {
		acceptV4 = matches[2][0] == '4'
		acceptV6 = !acceptV4
	}
	var host string
	var port int
	if matches[1] == "ping" {
		host = address
	} else {
		var sport string
		var err error
		host, sport, err = net.SplitHostPort(address)
		if err != nil {
			return nil, &net.OpError{Op: "dial", Err: err}
		}
		port, err = strconv.Atoi(sport)
		if err != nil || port < 0 || port > 65535 {
			return nil, &net.OpError{Op: "dial", Err: errNumericPort}
		}
	}
	allAddr, err := tnet.LookupContextHost(ctx, host)
	if err != nil {
		return nil, &net.OpError{Op: "dial", Err: err}
	}
	var addrs []netip.AddrPort
	for _, addr := range allAddr {
		ip, err := netip.ParseAddr(addr)
		if err == nil && ((ip.Is4() && acceptV4) || (ip.Is6() && acceptV6)) {
			addrs = append(addrs, netip.AddrPortFrom(ip, uint16(port)))
		}
	}
	if len(addrs) == 0 && len(allAddr) != 0 {
		return nil, &net.OpError{Op: "dial", Err: errNoSuitableAddress}
	}

	var firstErr error
	for i, addr := range addrs {
		select {
		case <-ctx.Done():
			err := ctx.Err()
			if err == context.Canceled {
				err = errCanceled
			} else if err == context.DeadlineExceeded {
				err = errTimeout
			}
			return nil, &net.OpError{Op: "dial", Err: err}
		default: