proxydial

type Dialer struct {
	// AllowedNets is a whitelist of nets that connections may be made over. For http
	// this should be only []string{"tcp"}
	AllowedNets []string

	// AllowedPorts is a whitelist of ports that connections may be made to. For http
	// the usual suspects would be []int16{80, 443}, but some other ports are used
	// fairly frequently.
	AllowedPorts []int16

	// BlockedRanges is a black list of IP ranges that connections may not be made to
	// This should usually include net.ParseCIDR("127.0.0.1/8") to prevent connections
	// to localhost, in addition to any other subnets that you use internally.
	BlockedRanges []*net.IPNet

	// BlockPrivate blocks any IP on a private network
	BlockPrivate bool
	// BlockLinkLocal blocks any IP on a link local network
	BlockLinkLocal bool
	// BlockMulticast blocks any IP on a multicast network
	BlockMulticast bool
	// BlockUnspecified blocks any unspecified IP
	BlockUnspecified bool

	// Timeout is the maximum amount of time a dial will wait for
	// a connection to complete. If Deadline is also set, it may fail
	// earlier.
	//
	// The default is no timeout.
	//
	// When dialing a name with multiple IP addresses, the timeout
	// may be divided between them.
	//
	// With or without a timeout, the operating system may impose
	// its own earlier timeout. For instance, TCP timeouts are
	// often around 3 minutes.
	Timeout time.Duration

	// Deadline is the absolute point in time after which dials
	// will fail. If Timeout is set, it may fail earlier.
	// Zero means no deadline, or dependent on the operating system
	// as with the Timeout option.
	Deadline time.Time

	// KeepAlive specifies the keep-alive period for an active
	// network connection.
	// If zero, keep-alives are not enabled. Network protocols
	// that do not support keep-alives ignore this field.
	KeepAlive time.Duration

	// LocalAddr is the local address to use when dialing an
	// address. The address must be of a compatible type for the
	// network being dialed.
	// If nil, a local address is automatically chosen.
	LocalAddr net.Addr
}