Changed groups and hosts to use maps in config, reorganized code, cleaned up command line arguments

alrmrc

@@ -1,11 +1,13 @@
 set interval 30
 
-monitor host gateway address 10.11.135.100
-
 monitor group webservers
 	host www1.example.com address 10.11.135.101
 		check ping
 	host www2.example.com address 10.11.135.102
-		check ping
+		# comments can occur at the beginning
+		check ping # or the end of a line
+		check ping # checks are not named, so multiple is okay
+
+monitor host gateway address 10.11.135.100
 
 monitor host database

check/check.go

@@ -1,13 +1,18 @@
-package main
+package check
 
 import (
 	"fmt"
 )
 
+type AlrmCheck interface {
+	Parse(string) (bool, error)
+	Check() error
+}
+
 func NewCheck(name string, addr string) (AlrmCheck, error) {
 	switch name {
 	case "ping":
-		return &CheckPing{Address: addr}, nil
+		return &CheckPing{Type: "ping", Address: addr}, nil
 	default:
 		return nil, fmt.Errorf("unknown check name \"%s\"", name)
 	}

check/check_ping.go

@@ -1,6 +1,7 @@
-package main
+package check
 
 type CheckPing struct {
+	Type string
 	Address string
 }
 

check/ping/ping.go

@@ -0,0 +1,660 @@
+// Package ping is an ICMP ping library seeking to emulate the unix "ping"
+// command.
+//
+// Here is a very simple example that sends & receives 3 packets:
+//
+//	pinger, err := ping.NewPinger("www.google.com")
+//	if err != nil {
+//		panic(err)
+//	}
+//
+//	pinger.Count = 3
+//	pinger.Run() // blocks until finished
+//	stats := pinger.Statistics() // get send/receive/rtt stats
+//
+// Here is an example that emulates the unix ping command:
+//
+//	pinger, err := ping.NewPinger("www.google.com")
+//	if err != nil {
+//		fmt.Printf("ERROR: %s\n", err.Error())
+//		return
+//	}
+//
+//	pinger.OnRecv = func(pkt *ping.Packet) {
+//		fmt.Printf("%d bytes from %s: icmp_seq=%d time=%v\n",
+//			pkt.Nbytes, pkt.IPAddr, pkt.Seq, pkt.Rtt)
+//	}
+//	pinger.OnFinish = func(stats *ping.Statistics) {
+//		fmt.Printf("\n--- %s ping statistics ---\n", stats.Addr)
+//		fmt.Printf("%d packets transmitted, %d packets received, %v%% packet loss\n",
+//			stats.PacketsSent, stats.PacketsRecv, stats.PacketLoss)
+//		fmt.Printf("round-trip min/avg/max/stddev = %v/%v/%v/%v\n",
+//			stats.MinRtt, stats.AvgRtt, stats.MaxRtt, stats.StdDevRtt)
+//	}
+//
+//	fmt.Printf("PING %s (%s):\n", pinger.Addr(), pinger.IPAddr())
+//	pinger.Run()
+//
+// It sends ICMP packet(s) and waits for a response. If it receives a response,
+// it calls the "receive" callback. When it's finished, it calls the "finish"
+// callback.
+//
+// For a full ping example, see "cmd/ping/ping.go".
+//
+package ping
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"math"
+	"math/rand"
+	"net"
+	"runtime"
+	"sync"
+	"syscall"
+	"time"
+
+	"golang.org/x/net/icmp"
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
+)
+
+const (
+	timeSliceLength  = 8
+	trackerLength    = 8
+	protocolICMP     = 1
+	protocolIPv6ICMP = 58
+)
+
+var (
+	ipv4Proto = map[string]string{"icmp": "ip4:icmp", "udp": "udp4"}
+	ipv6Proto = map[string]string{"icmp": "ip6:ipv6-icmp", "udp": "udp6"}
+)
+
+// New returns a new Pinger struct pointer.
+func New(addr string) *Pinger {
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	return &Pinger{
+		Count:      -1,
+		Interval:   time.Second,
+		RecordRtts: true,
+		Size:       timeSliceLength,
+		Timeout:    time.Second * 100000,
+		Tracker:    r.Int63n(math.MaxInt64),
+
+		addr:     addr,
+		done:     make(chan bool),
+		id:       r.Intn(math.MaxInt16),
+		ipaddr:   nil,
+		ipv4:     false,
+		network:  "ip",
+		protocol: "udp",
+	}
+}
+
+// NewPinger returns a new Pinger and resolves the address.
+func NewPinger(addr string) (*Pinger, error) {
+	p := New(addr)
+	return p, p.Resolve()
+}
+
+// Pinger represents a packet sender/receiver.
+type Pinger struct {
+	// Interval is the wait time between each packet send. Default is 1s.
+	Interval time.Duration
+
+	// Timeout specifies a timeout before ping exits, regardless of how many
+	// packets have been received.
+	Timeout time.Duration
+
+	// Count tells pinger to stop after sending (and receiving) Count echo
+	// packets. If this option is not specified, pinger will operate until
+	// interrupted.
+	Count int
+
+	// Debug runs in debug mode
+	Debug bool
+
+	// Number of packets sent
+	PacketsSent int
+
+	// Number of packets received
+	PacketsRecv int
+
+	// If true, keep a record of rtts of all received packets.
+	// Set to false to avoid memory bloat for long running pings.
+	RecordRtts bool
+
+	// rtts is all of the Rtts
+	rtts []time.Duration
+
+	// OnSend is called when Pinger sends a packet
+	OnSend func(*Packet)
+
+	// OnRecv is called when Pinger receives and processes a packet
+	OnRecv func(*Packet)
+
+	// OnFinish is called when Pinger exits
+	OnFinish func(*Statistics)
+
+	// Size of packet being sent
+	Size int
+
+	// Tracker: Used to uniquely identify packet when non-priviledged
+	Tracker int64
+
+	// Source is the source IP address
+	Source string
+
+	// stop chan bool
+	done chan bool
+
+	ipaddr *net.IPAddr
+	addr   string
+
+	ipv4     bool
+	id       int
+	sequence int
+	// network is one of "ip", "ip4", or "ip6".
+	network string
+	// protocol is "icmp" or "udp".
+	protocol string
+}
+
+type packet struct {
+	bytes  []byte
+	nbytes int
+	ttl    int
+}
+
+// Packet represents a received and processed ICMP echo packet.
+type Packet struct {
+	// Rtt is the round-trip time it took to ping.
+	Rtt time.Duration
+
+	// IPAddr is the address of the host being pinged.
+	IPAddr *net.IPAddr
+
+	// Addr is the string address of the host being pinged.
+	Addr string
+
+	// NBytes is the number of bytes in the message.
+	Nbytes int
+
+	// Seq is the ICMP sequence number.
+	Seq int
+
+	// TTL is the Time To Live on the packet.
+	Ttl int
+}
+
+// Statistics represent the stats of a currently running or finished
+// pinger operation.
+type Statistics struct {
+	// PacketsRecv is the number of packets received.
+	PacketsRecv int
+
+	// PacketsSent is the number of packets sent.
+	PacketsSent int
+
+	// PacketLoss is the percentage of packets lost.
+	PacketLoss float64
+
+	// IPAddr is the address of the host being pinged.
+	IPAddr *net.IPAddr
+
+	// Addr is the string address of the host being pinged.
+	Addr string
+
+	// Rtts is all of the round-trip times sent via this pinger.
+	Rtts []time.Duration
+
+	// MinRtt is the minimum round-trip time sent via this pinger.
+	MinRtt time.Duration
+
+	// MaxRtt is the maximum round-trip time sent via this pinger.
+	MaxRtt time.Duration
+
+	// AvgRtt is the average round-trip time sent via this pinger.
+	AvgRtt time.Duration
+
+	// StdDevRtt is the standard deviation of the round-trip times sent via
+	// this pinger.
+	StdDevRtt time.Duration
+}
+
+// SetIPAddr sets the ip address of the target host.
+func (p *Pinger) SetIPAddr(ipaddr *net.IPAddr) {
+	p.ipv4 = isIPv4(ipaddr.IP)
+
+	p.ipaddr = ipaddr
+	p.addr = ipaddr.String()
+}
+
+// IPAddr returns the ip address of the target host.
+func (p *Pinger) IPAddr() *net.IPAddr {
+	return p.ipaddr
+}
+
+// Resolve does the DNS lookup for the Pinger address and sets IP protocol.
+func (p *Pinger) Resolve() error {
+	if len(p.addr) == 0 {
+		return errors.New("addr cannot be empty")
+	}
+	ipaddr, err := net.ResolveIPAddr(p.network, p.addr)
+	if err != nil {
+		return err
+	}
+
+	p.ipv4 = isIPv4(ipaddr.IP)
+
+	p.ipaddr = ipaddr
+
+	return nil
+}
+
+// SetAddr resolves and sets the ip address of the target host, addr can be a
+// DNS name like "www.google.com" or IP like "127.0.0.1".
+func (p *Pinger) SetAddr(addr string) error {
+	oldAddr := p.addr
+	p.addr = addr
+	err := p.Resolve()
+	if err != nil {
+		p.addr = oldAddr
+		return err
+	}
+	return nil
+}
+
+// Addr returns the string ip address of the target host.
+func (p *Pinger) Addr() string {
+	return p.addr
+}
+
+// SetNetwork allows configuration of DNS resolution.
+// * "ip" will automatically select IPv4 or IPv6.
+// * "ip4" will select IPv4.
+// * "ip6" will select IPv6.
+func (p *Pinger) SetNetwork(n string) {
+	switch n {
+	case "ip4":
+		p.network = "ip4"
+	case "ip6":
+		p.network = "ip6"
+	default:
+		p.network = "ip"
+	}
+}
+
+// SetPrivileged sets the type of ping pinger will send.
+// false means pinger will send an "unprivileged" UDP ping.
+// true means pinger will send a "privileged" raw ICMP ping.
+// NOTE: setting to true requires that it be run with super-user privileges.
+func (p *Pinger) SetPrivileged(privileged bool) {
+	if privileged {
+		p.protocol = "icmp"
+	} else {
+		p.protocol = "udp"
+	}
+}
+
+// Privileged returns whether pinger is running in privileged mode.
+func (p *Pinger) Privileged() bool {
+	return p.protocol == "icmp"
+}
+
+// Run runs the pinger. This is a blocking function that will exit when it's
+// done. If Count or Interval are not specified, it will run continuously until
+// it is interrupted.
+func (p *Pinger) Run() error {
+	var conn *icmp.PacketConn
+	var err error
+	if p.ipaddr == nil {
+		err = p.Resolve()
+	}
+	if err != nil {
+		return err
+	}
+	if p.ipv4 {
+		if conn, err = p.listen(ipv4Proto[p.protocol]); err != nil {
+			return err
+		}
+		if err = conn.IPv4PacketConn().SetControlMessage(ipv4.FlagTTL, true); runtime.GOOS != "windows" && err != nil {
+			return err
+		}
+	} else {
+		if conn, err = p.listen(ipv6Proto[p.protocol]); err != nil {
+			return err
+		}
+		if err = conn.IPv6PacketConn().SetControlMessage(ipv6.FlagHopLimit, true); runtime.GOOS != "windows" && err != nil {
+			return err
+		}
+	}
+	defer conn.Close()
+	defer p.finish()
+
+	var wg sync.WaitGroup
+	recv := make(chan *packet, 5)
+	defer close(recv)
+	wg.Add(1)
+	//nolint:errcheck
+	go p.recvICMP(conn, recv, &wg)
+
+	err = p.sendICMP(conn)
+	if err != nil {
+		return err
+	}
+
+	timeout := time.NewTicker(p.Timeout)
+	defer timeout.Stop()
+	interval := time.NewTicker(p.Interval)
+	defer interval.Stop()
+
+	for {
+		select {
+		case <-p.done:
+			wg.Wait()
+			return nil
+		case <-timeout.C:
+			close(p.done)
+			wg.Wait()
+			return nil
+		case <-interval.C:
+			if p.Count > 0 && p.PacketsSent >= p.Count {
+				continue
+			}
+			err = p.sendICMP(conn)
+			if err != nil {
+				// FIXME: this logs as FATAL but continues
+				fmt.Println("FATAL: ", err.Error())
+			}
+		case r := <-recv:
+			err := p.processPacket(r)
+			if err != nil {
+				// FIXME: this logs as FATAL but continues
+				fmt.Println("FATAL: ", err.Error())
+			}
+		}
+		if p.Count > 0 && p.PacketsRecv >= p.Count {
+			close(p.done)
+			wg.Wait()
+			return nil
+		}
+	}
+}
+
+func (p *Pinger) Stop() {
+	close(p.done)
+}
+
+func (p *Pinger) finish() {
+	handler := p.OnFinish
+	if handler != nil {
+		s := p.Statistics()
+		handler(s)
+	}
+}
+
+// Statistics returns the statistics of the pinger. This can be run while the
+// pinger is running or after it is finished. OnFinish calls this function to
+// get it's finished statistics.
+func (p *Pinger) Statistics() *Statistics {
+	loss := float64(p.PacketsSent-p.PacketsRecv) / float64(p.PacketsSent) * 100
+	var min, max, total time.Duration
+	if len(p.rtts) > 0 {
+		min = p.rtts[0]
+		max = p.rtts[0]
+	}
+	for _, rtt := range p.rtts {
+		if rtt < min {
+			min = rtt
+		}
+		if rtt > max {
+			max = rtt
+		}
+		total += rtt
+	}
+	s := Statistics{
+		PacketsSent: p.PacketsSent,
+		PacketsRecv: p.PacketsRecv,
+		PacketLoss:  loss,
+		Rtts:        p.rtts,
+		Addr:        p.addr,
+		IPAddr:      p.ipaddr,
+		MaxRtt:      max,
+		MinRtt:      min,
+	}
+	if len(p.rtts) > 0 {
+		s.AvgRtt = total / time.Duration(len(p.rtts))
+		var sumsquares time.Duration
+		for _, rtt := range p.rtts {
+			sumsquares += (rtt - s.AvgRtt) * (rtt - s.AvgRtt)
+		}
+		s.StdDevRtt = time.Duration(math.Sqrt(
+			float64(sumsquares / time.Duration(len(p.rtts)))))
+	}
+	return &s
+}
+
+func (p *Pinger) recvICMP(
+	conn *icmp.PacketConn,
+	recv chan<- *packet,
+	wg *sync.WaitGroup,
+) error {
+	defer wg.Done()
+	for {
+		select {
+		case <-p.done:
+			return nil
+		default:
+			bytes := make([]byte, 512)
+			if err := conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100)); err != nil {
+				return err
+			}
+			var n, ttl int
+			var err error
+			if p.ipv4 {
+				var cm *ipv4.ControlMessage
+				n, cm, _, err = conn.IPv4PacketConn().ReadFrom(bytes)
+				if cm != nil {
+					ttl = cm.TTL
+				}
+			} else {
+				var cm *ipv6.ControlMessage
+				n, cm, _, err = conn.IPv6PacketConn().ReadFrom(bytes)
+				if cm != nil {
+					ttl = cm.HopLimit
+				}
+			}
+			if err != nil {
+				if neterr, ok := err.(*net.OpError); ok {
+					if neterr.Timeout() {
+						// Read timeout
+						continue
+					} else {
+						close(p.done)
+						return err
+					}
+				}
+			}
+
+			select {
+			case <-p.done:
+				return nil
+			case recv <- &packet{bytes: bytes, nbytes: n, ttl: ttl}:
+			}
+		}
+	}
+}
+
+func (p *Pinger) processPacket(recv *packet) error {
+	receivedAt := time.Now()
+	var proto int
+	if p.ipv4 {
+		proto = protocolICMP
+	} else {
+		proto = protocolIPv6ICMP
+	}
+
+	var m *icmp.Message
+	var err error
+	if m, err = icmp.ParseMessage(proto, recv.bytes); err != nil {
+		return fmt.Errorf("error parsing icmp message: %s", err.Error())
+	}
+
+	if m.Type != ipv4.ICMPTypeEchoReply && m.Type != ipv6.ICMPTypeEchoReply {
+		// Not an echo reply, ignore it
+		return nil
+	}
+
+	outPkt := &Packet{
+		Nbytes: recv.nbytes,
+		IPAddr: p.ipaddr,
+		Addr:   p.addr,
+		Ttl:    recv.ttl,
+	}
+
+	switch pkt := m.Body.(type) {
+	case *icmp.Echo:
+		// If we are priviledged, we can match icmp.ID
+		if p.protocol == "icmp" {
+			// Check if reply from same ID
+			if pkt.ID != p.id {
+				return nil
+			}
+		}
+
+		if len(pkt.Data) < timeSliceLength+trackerLength {
+			return fmt.Errorf("insufficient data received; got: %d %v",
+				len(pkt.Data), pkt.Data)
+		}
+
+		tracker := bytesToInt(pkt.Data[timeSliceLength:])
+		timestamp := bytesToTime(pkt.Data[:timeSliceLength])
+
+		if tracker != p.Tracker {
+			return nil
+		}
+
+		outPkt.Rtt = receivedAt.Sub(timestamp)
+		outPkt.Seq = pkt.Seq
+		p.PacketsRecv++
+	default:
+		// Very bad, not sure how this can happen
+		return fmt.Errorf("invalid ICMP echo reply; type: '%T', '%v'", pkt, pkt)
+	}
+
+	if p.RecordRtts {
+		p.rtts = append(p.rtts, outPkt.Rtt)
+	}
+	handler := p.OnRecv
+	if handler != nil {
+		handler(outPkt)
+	}
+
+	return nil
+}
+
+func (p *Pinger) sendICMP(conn *icmp.PacketConn) error {
+	var typ icmp.Type
+	if p.ipv4 {
+		typ = ipv4.ICMPTypeEcho
+	} else {
+		typ = ipv6.ICMPTypeEchoRequest
+	}
+
+	var dst net.Addr = p.ipaddr
+	if p.protocol == "udp" {
+		dst = &net.UDPAddr{IP: p.ipaddr.IP, Zone: p.ipaddr.Zone}
+	}
+
+	t := append(timeToBytes(time.Now()), intToBytes(p.Tracker)...)
+	if remainSize := p.Size - timeSliceLength - trackerLength; remainSize > 0 {
+		t = append(t, bytes.Repeat([]byte{1}, remainSize)...)
+	}
+
+	body := &icmp.Echo{
+		ID:   p.id,
+		Seq:  p.sequence,
+		Data: t,
+	}
+
+	msg := &icmp.Message{
+		Type: typ,
+		Code: 0,
+		Body: body,
+	}
+
+	msgBytes, err := msg.Marshal(nil)
+	if err != nil {
+		return err
+	}
+
+	for {
+		if _, err := conn.WriteTo(msgBytes, dst); err != nil {
+			if neterr, ok := err.(*net.OpError); ok {
+				if neterr.Err == syscall.ENOBUFS {
+					continue
+				}
+			}
+		}
+		handler := p.OnSend
+		if handler != nil {
+			outPkt := &Packet{
+				Nbytes: len(msgBytes),
+				IPAddr: p.ipaddr,
+				Addr:   p.addr,
+				Seq:    p.sequence,
+			}
+			handler(outPkt)
+		}
+
+		p.PacketsSent++
+		p.sequence++
+		break
+	}
+
+	return nil
+}
+
+func (p *Pinger) listen(netProto string) (*icmp.PacketConn, error) {
+	conn, err := icmp.ListenPacket(netProto, p.Source)
+	if err != nil {
+		close(p.done)
+		return nil, err
+	}
+	return conn, nil
+}
+
+func bytesToTime(b []byte) time.Time {
+	var nsec int64
+	for i := uint8(0); i < 8; i++ {
+		nsec += int64(b[i]) << ((7 - i) * 8)
+	}
+	return time.Unix(nsec/1000000000, nsec%1000000000)
+}
+
+func isIPv4(ip net.IP) bool {
+	return len(ip.To4()) == net.IPv4len
+}
+
+func timeToBytes(t time.Time) []byte {
+	nsec := t.UnixNano()
+	b := make([]byte, 8)
+	for i := uint8(0); i < 8; i++ {
+		b[i] = byte((nsec >> ((7 - i) * 8)) & 0xff)
+	}
+	return b
+}
+
+func bytesToInt(b []byte) int64 {
+	return int64(binary.BigEndian.Uint64(b))
+}
+
+func intToBytes(tracker int64) []byte {
+	b := make([]byte, 8)
+	binary.BigEndian.PutUint64(b, uint64(tracker))
+	return b
+}

config.go

@@ -1,50 +0,0 @@
-package main
-
-type AlrmConfig struct {
-	Groups   []*AlrmGroup
-	Interval int
-}
-
-func (ac *AlrmConfig) NewGroup() *AlrmGroup {
-	group := &AlrmGroup{}
-	ac.Groups = append(ac.Groups, group)
-	return group
-}
-
-type AlrmGroup struct {
-	Name  string
-	Hosts []*AlrmHost
-}
-
-func (ag *AlrmGroup) NewHost() *AlrmHost {
-	host := &AlrmHost{}
-	ag.Hosts = append(ag.Hosts, host)
-	return host
-}
-
-type AlrmHost struct {
-	Name    string
-	Address string
-	Checks  []AlrmCheck
-}
-
-func (ah *AlrmHost) GetAddress() string {
-	if ah.Address != "" {
-		return ah.Address
-	}
-	return ah.Name
-}
-
-type AlrmCheck interface {
-	Parse(string) (bool, error)
-	Check() error
-}
-
-func ReadConfig(fn string) (*AlrmConfig, error) {
-	parser := &Parser{}
-	config, err := parser.Parse(fn)
-	if err != nil {
-		return nil, err
-	}
-	return config, nil
-}

config/config.go

@@ -0,0 +1,44 @@
+package config
+
+import (
+	"fmt"
+	"strconv"
+)
+
+type AlrmConfig struct {
+	Groups   map[string]*AlrmGroup
+	Interval int
+}
+
+func (ac *AlrmConfig) NewGroup(name string) (*AlrmGroup, error) {
+	if ac.Groups == nil {
+		ac.Groups = make(map[string]*AlrmGroup)
+	}
+
+	if _, exists := ac.Groups[name]; exists {
+		return nil, fmt.Errorf("group %s already exists", name)
+	}
+
+	group := &AlrmGroup{Name: name}
+	ac.Groups[name] = group
+	return group, nil
+}
+
+func (ac *AlrmConfig) SetInterval(val string) error {
+	interval, err := strconv.Atoi(val)
+	if err != nil {
+		return err
+	}
+
+	ac.Interval = interval
+	return nil
+}
+
+func ReadConfig(fn string, debuglvl int) (*AlrmConfig, error) {
+	parser := &Parser{DebugLevel: debuglvl}
+	config, err := parser.Parse(fn)
+	if err != nil {
+		return nil, err
+	}
+	return config, nil
+}

config/group.go

@@ -0,0 +1,24 @@
+package config
+
+import (
+	"fmt"
+)
+
+type AlrmGroup struct {
+	Name  string
+	Hosts map[string]*AlrmHost
+}
+
+func (ag *AlrmGroup) NewHost(name string) (*AlrmHost, error) {
+	if ag.Hosts == nil {
+		ag.Hosts = make(map[string]*AlrmHost)
+	}
+
+	if _, exists := ag.Hosts[name]; exists {
+		return nil, fmt.Errorf("host %s already exists", name)
+	}
+
+	host := &AlrmHost{Name: name}
+	ag.Hosts[name] = host
+	return host, nil
+}

config/host.go

@@ -0,0 +1,27 @@
+package config
+
+import (
+	"alrm/check"
+)
+
+type AlrmHost struct {
+	Name    string
+	Address string
+	Checks  []check.AlrmCheck
+}
+
+func (ah *AlrmHost) GetAddress() string {
+	if ah.Address != "" {
+		return ah.Address
+	}
+	return ah.Name
+}
+
+func (ah *AlrmHost) NewCheck(name string) (check.AlrmCheck, error) {
+	chk, err := check.NewCheck(name, ah.GetAddress())
+	if err != nil {
+		return nil, err
+	}
+	ah.Checks = append(ah.Checks, chk)
+	return chk, nil
+}

config/parser.go

@@ -1,10 +1,10 @@
-package main
+package config
 
 import (
+	"alrm/check"
 	"bufio"
 	"fmt"
 	"os"
-	"strconv"
 	"strings"
 )
 
@@ -18,8 +18,12 @@ const (
 )
 
 type Parser struct {
+	DebugLevel int
 	Line       int
 	states     []int
+	lasthost   *AlrmHost
+	lastgroup  *AlrmGroup
+	lastcheck  check.AlrmCheck
 }
 
 func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
@@ -30,9 +34,6 @@ func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
 	defer file.Close()
 
 	config := &AlrmConfig{}
-	var group *AlrmGroup
-	var host *AlrmHost
-	var check AlrmCheck
 
 	scan := bufio.NewScanner(file)
 	scan.Split(p.Split)
@@ -61,7 +62,7 @@ func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
 			value := scan.Text()
 			switch key {
 			case "interval":
-				config.Interval, err = strconv.Atoi(value)
+				err := config.SetInterval(value)
 				if err != nil {
 					return nil, fmt.Errorf(
 						"invalid number for interval in %s, line %d: \"%s\"",
@@ -78,12 +79,9 @@ func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
 		case TK_MONITOR:
 			switch strings.ToLower(tk) {
 			case "host":
-				group = config.NewGroup()
-				host = group.NewHost()
 				p.setState(TK_HOST)
 
 			case "group":
-				group = config.NewGroup()
 				p.setState(TK_GROUP)
 
 			default:
@@ -92,33 +90,43 @@ func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
 			}
 
 		case TK_GROUP:
-			if group == nil {
+			if p.lastgroup == nil {
-				return nil, fmt.Errorf("group without initialization")
+				p.lastgroup, err = config.NewGroup(tk)
+				if err != nil {
+					return nil, fmt.Errorf("%s in %s, line %d",
+						err.Error(), fn, p.Line+1,
+					)
+				}
+				continue
 			}
 
 			switch strings.ToLower(tk) {
 			case "host":
-				host = group.NewHost()
 				p.setState(TK_HOST)
-				continue
 
 			default:
-				if group.Name == "" {
-					group.Name = tk
-					continue
-				}
-
 				p.prevState()
 				goto stateswitch
 			}
 
 		case TK_HOST:
-			if host == nil {
+			// If a host has no group, inherit the host name
-				return nil, fmt.Errorf("host token without initialization")
+			if p.lastgroup == nil {
+				p.lastgroup, err = config.NewGroup(tk)
+				if err != nil {
+					return nil, fmt.Errorf("%s in %s, line %d",
+						err.Error(), fn, p.Line+1,
+					)
+				}
 			}
 
-			if host.Name == "" {
+			if p.lasthost == nil {
-				host.Name = tk
+				p.lasthost, err = p.lastgroup.NewHost(tk)
+				if err != nil {
+					return nil, fmt.Errorf("%s in %s, line %d",
+						err.Error(), fn, p.Line+1,
+					)
+				}
 				continue
 			}
 
@@ -128,10 +136,9 @@ func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
 					return nil, fmt.Errorf("empty address for host in %s, line %d",
 						fn, p.Line+1)
 				}
-				host.Address = scan.Text()
+				p.lasthost.Address = scan.Text()
 
 			case "check":
-				check = nil
 				p.setState(TK_CHECK)
 
 			default:
@@ -140,23 +147,20 @@ func (p *Parser) Parse(fn string) (*AlrmConfig, error) {
 			}
 
 		case TK_CHECK:
-			if check == nil {
+			if p.lastcheck == nil {
-				if host == nil {
+				p.lastcheck, err = p.lasthost.NewCheck(tk)
-					return nil, fmt.Errorf("check token without initialization")
-				}
-				check, err = NewCheck(strings.ToLower(tk), host.GetAddress())
 				if err != nil {
 					return nil, fmt.Errorf("%s in %s, line %d",
 						err.Error(), fn, p.Line+1)
 				}
-				host.Checks = append(host.Checks, check)
 				continue
 			}
-			cont, err := check.Parse(tk)
+			cont, err := p.lastcheck.Parse(tk)
 			if err != nil {
 				return nil, err
 			}
 			if !cont {
+				p.lastcheck = nil
 				p.prevState()
 				goto stateswitch
 			}
@@ -179,9 +183,24 @@ func (p *Parser) state() int {
 }
 
 func (p *Parser) setState(state int) {
-	// fmt.Printf("%s", p.stateName())
+	switch state {
+	case TK_SET, TK_MONITOR:
+		fallthrough
+	case TK_GROUP:
+		p.lastgroup = nil
+		fallthrough
+	case TK_HOST:
+		p.lasthost = nil
+		p.lastcheck = nil
+	}
+
+	if p.DebugLevel > 0 {
+		fmt.Printf("Parser state: %s", p.stateName())
+	}
 	p.states = append(p.states, state)
-	// fmt.Printf(" -> %s\n", p.stateName())
+	if p.DebugLevel > 0 {
+		fmt.Printf(" -> %s\n", p.stateName())
+	}
 }
 
 func (p *Parser) prevState() int {
@@ -222,7 +241,7 @@ func (p *Parser) Split(data []byte, atEOF bool) (int, []byte, error) {
 
 	for i := 0; i < len(data); i++ {
 		c := data[i]
-//		fmt.Printf("%c (%t) (%t)\n", c, started, ignoreline)
+		// fmt.Printf("%c (%t) (%t)\n", c, started, ignoreline)
 		switch c {
 		case '\f', '\n', '\r':
 			p.Line++

main.go

@@ -6,43 +6,51 @@ import (
 	"flag"
 	"os"
 	"strings"
+	"alrm/config"
 )
 
 func main() {
-	configPath := flag.String("config", "", "path to configuration file")
+	cfgPath := flag.String("c", "", "path to configuration file")
+	debuglvl := flag.Int("d", 0, "debug level")
 
 	flag.Parse()
 
-	if *configPath == "" {
+	if *cfgPath == "" {
 		if _, err := os.Stat("./alrmrc"); err == nil {
-			*configPath = "./alrmrc"
+			*cfgPath = "./alrmrc"
 		}
 		if _, err := os.Stat("/etc/alrmrc"); err == nil {
-			*configPath = "/etc/alrmrc"
+			*cfgPath = "/etc/alrmrc"
 		}
-		if *configPath == "" {
+		if *cfgPath == "" {
 			fmt.Fprintf(os.Stderr, "Cannot find configuration\n")
 			os.Exit(1)
 		}
 	}
 
-	config, err := ReadConfig(*configPath)
+	command := strings.ToLower(flag.Arg(0))
+	switch command {
+		case "json":
+			cfg, err := config.ReadConfig(*cfgPath, *debuglvl)
 			if err != nil {
 				fmt.Fprintf(os.Stderr, "%s\n", err.Error())
 				os.Exit(1)
 			}
 
-	command := strings.ToLower(flag.Arg(0))
+			o, err := json.MarshalIndent(cfg, "", "  ")
-	switch command {
-		case "json":
-			o, err := json.MarshalIndent(config, "", "  ")
 			if err != nil {
 				fmt.Fprintf(os.Stderr, "JSON error: %s\n", err.Error())
 				os.Exit(1)
 			}
-			fmt.Fprintf(os.Stdout, "%s", string(o))
+			fmt.Fprintf(os.Stdout, "%s\n", string(o))
 
 		case "", "config":
+			_, err := config.ReadConfig(*cfgPath, *debuglvl)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "%s\n", err.Error())
+				os.Exit(1)
+			}
+
 			fmt.Fprintf(os.Stdout, "Config is OK.\n")
 			os.Exit(0)