probe

type Config struct {
	// Network to use (ala net.Dial).
	Network string

	// Address to probe.
	Address string

	// BaselineData is any data saved from a previously run probe. Providing baseline data will
	// reduce the time needed for a probe test.
	BaselineData io.Reader

	// MaxParallelism is the maximum number of goroutines spawned during a probe. This number is
	// approximate and will be honored on a best-effort basis. A value <= 0 indicates that there is
	// no limit to parallelism.
	MaxParallelism int

	// ResponseTimeout is the time the probe allows the server to respond to each probe payload.
	// After this duration has passed, the server is determined to have no response. A value <= 0
	// indicates that there should be no timeout.
	ResponseTimeout time.Duration

	Logger io.Writer
}

type ForRandomizedTransportBaseline struct {
	MinResponseTime, MaxResponseTime, ResponseTimeStdDev time.Duration

	// ResponseFlags is the set of TCP flags seen on the first response packet. The first response
	// packet is defined as the first packet received from the server which (a) was sent after the
	// first client payload packet and (b) was more than a simple ACK.
	//
	// In the case where the set of flags in the first response packet is not consistent, this will
	// be an empty, non-nil slice. In the case where no response was received, this will be nil.
	ResponseFlags []string
}

type ForRandomizedTransportExplanation struct {
	// PayloadSizeThreshold is the payload size at which the behavior of the server changed.
	PayloadSizeThreshold int

	// ResponseTime is the time the server took to respond to a payload of the threshold size.
	ResponseTime time.Duration

	// ResponseFlags is the set of TCP flags seen on the first response packet. The first response
	// packet is defined as the first packet received from the server which (a) was sent after the
	// first client payload packet and (b) was more than a simple ACK.
	ResponseFlags []string

	// Baseline against which responses were compared.
	Baseline ForRandomizedTransportBaseline
}

type Results struct {
	// Success reports whether the probe found what it was looking for. In most cases, you want this
	// to be false. True means that the probe was able to identify the server as a circumvention
	// tool.
	Success bool

	// An explanation is provided when Success is true.
	Explanation fmt.Stringer

	// BaselineData encodes the baseline against which the probe's test was run. BaselineData is
	// non-nil iff the probe created baseline data outside of what was provided by Config.
	BaselineData io.Reader
}