func newSocketMount()

in internal/proxy/proxy.go [759:827]
48 lines of code
12 McCabe index (conditional complexity)

func newSocketMount(ctx context.Context, conf *Config, pc *portConfig, inst InstanceConnConfig) (*socketMount, error) {
	shortInst, err := ShortInstURI(inst.Name)
	if err != nil {
		return nil, err
	}

	var (
		// network is one of "tcp" or "unix"
		network string
		// address is either a TCP host port, or a Unix socket
		address string
	)

	// IF
	//   a global Unix socket directory is NOT set AND
	//   an instance-level Unix socket is NOT set
	//   (e.g.,  I didn't set a Unix socket globally or for this instance)
	// OR
	//   an instance-level TCP address or port IS set
	//   (e.g., I'm overriding any global settings to use TCP for this
	//   instance)
	// use a TCP listener.
	// Otherwise, use a Unix socket.
	if (conf.UnixSocket == "" && inst.UnixSocket == "" && inst.UnixSocketPath == "") ||
		(inst.Addr != "" || inst.Port != 0) {
		network = "tcp"

		a := conf.Addr
		if inst.Addr != "" {
			a = inst.Addr
		}

		var np int
		switch {
		case inst.Port != 0:
			np = inst.Port
		default:
			np = pc.nextPort()
		}

		address = net.JoinHostPort(a, fmt.Sprint(np))
	} else {
		network = "unix"
		address, err = newUnixSocketMount(inst, conf.UnixSocket, true)
		if err != nil {
			return nil, err
		}
	}

	lc := net.ListenConfig{KeepAlive: 30 * time.Second}
	ln, err := lc.Listen(ctx, network, address)
	if err != nil {
		return nil, err
	}
	// Change file permisions to allow access for user, group, and other.
	if network == "unix" {
		// Best effort. If this call fails, group and other won't have write
		// access.
		_ = os.Chmod(address, 0777)
	}
	opts := dialOptions(*conf, inst)
	m := &socketMount{
		inst:      inst.Name,
		instShort: shortInst,
		listener:  ln,
		dialOpts:  opts,
	}
	return m, nil
}