ardop.go

// Copyright 2015 Martin Hebnes Pedersen (LA5NTA). All rights reserved.
// Use of this source code is governed by the MIT-license that can be
// found in the LICENSE file.

// Package ardop provides means of establishing a connection to a remote node using ARDOP TNC
package ardop

import (
	"errors"
	"fmt"
	"os"
	"strings"
	"time"
)

const (
	DefaultAddr       = "localhost:8515" // The default address Ardop TNC listens on
	DefaultARQTimeout = 90 * time.Second // The default ARQ session idle timout
)

const (
	ModeARQ = "ARQ" // ARQ mode
	ModeFEC = "FEC" // FEC mode
)

// TNC states
const (
	//go:generate stringer -type=State .
	Unknown      State = iota
	Offline            // Sound card disabled and all sound card resources are released
	Disconnected       // The session is disconnected, the sound card remains active
	ISS                // Information Sending Station (Sending Data)
	IRS                // Information Receiving Station (Receiving data)
	Idle               // ??
	FECSend            // ??
	FECReceive         // Receiving FEC (unproto) data
)

var (
	ErrBusy                 = errors.New("TNC control port is busy.")
	ErrConnectInProgress    = errors.New("A connect is in progress.")
	ErrFlushTimeout         = errors.New("Flush timeout.")
	ErrActiveListenerExists = errors.New("An active listener is already registered with this TNC.")
	ErrDisconnectTimeout    = errors.New("Disconnect timeout: aborted connection.")
	ErrConnectTimeout       = errors.New("Connect timeout")
	ErrChecksumMismatch     = errors.New("Control protocol checksum mismatch")
	ErrTNCClosed            = errors.New("TNC closed")
	ErrUnsupportedBandwidth = errors.New("Unsupported ARQ bandwidth")
)

// Bandwidth definitions of all supported ARQ bandwidths.
var (
	Bandwidth200Max     = Bandwidth{false, 200}
	Bandwidth500Max     = Bandwidth{false, 500}
	Bandwidth1000Max    = Bandwidth{false, 1000}
	Bandwidth2000Max    = Bandwidth{false, 2000}
	Bandwidth200Forced  = Bandwidth{true, 200}
	Bandwidth500Forced  = Bandwidth{true, 500}
	Bandwidth1000Forced = Bandwidth{true, 1000}
	Bandwidth2000Forced = Bandwidth{true, 2000}
)

type State uint8

// Bandwidth represents the ARQ bandwidth.
type Bandwidth struct {
	Forced bool // Force use of max bandwidth.
	Max    uint // Max bandwidh to use.
}

// Stringer for Bandwidth returns a valid bandwidth parameter that can be sent to the TNC.
func (bw Bandwidth) String() string {
	str := fmt.Sprintf("%d", bw.Max)
	if bw.Forced {
		str += "FORCED"
	} else {
		str += "MAX"
	}
	return str
}

// IsZero returns true if bw is it's zero value.
func (bw Bandwidth) IsZero() bool { return bw.Max == 0 }

// BandwidthFromString returns a Bandwidth representation of the given string.
//
// The string must be a valid ARDOP ARQ bandwidth string (e.g. "2000MAX", "2000FORCED").
// The MAX/FORCED suffix may be omitted. Defaults to MAX.
func BandwidthFromString(str string) (Bandwidth, error) {
	//  Default to MAX if MAX/FORCED is not given.
	if strings.HasSuffix(str, "0") {
		str += "MAX"
	}
	for _, bw := range Bandwidths() {
		if bw.String() == str {
			return bw, nil
		}
	}
	return Bandwidth{}, ErrUnsupportedBandwidth
}

// Bandwidths returns a list of all ARDOP ARQ bandwidths.
func Bandwidths() []Bandwidth {
	return []Bandwidth{
		Bandwidth200Max,
		Bandwidth500Max,
		Bandwidth1000Max,
		Bandwidth2000Max,
		Bandwidth200Forced,
		Bandwidth500Forced,
		Bandwidth1000Forced,
		Bandwidth2000Forced,
	}
}

var stateMap = map[string]State{
	"":        Unknown,
	"OFFLINE": Offline,
	"DISC":    Disconnected,
	"ISS":     ISS,
	"IRS":     IRS,
	"IDLE":    Idle,
	"FECRcv":  FECReceive,
	"FECSend": FECSend,
}

func strToState(str string) (State, bool) {
	state, ok := stateMap[strings.ToUpper(str)]
	return state, ok
}

func debugEnabled() bool {
	return os.Getenv("ARDOP_DEBUG") != ""
}