Add first version of script to parse leases

.gitignore

@@ -9,6 +9,9 @@
 *.so
 *.dylib
 
+# Build files
+build/
+
 # Test binary, built with `go test -c`
 *.test
 

go.mod

@@ -0,0 +1,8 @@
+module git.faercol.me/faercol/dnsmasq-netbox-connector
+
+go 1.23.1
+
+require (
+	git.faercol.me/faercol/go-healthchecks v0.0.0-20241003132603-97f47d027454 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+)

go.sum

@@ -0,0 +1,8 @@
+git.faercol.me/faercol/go-healthchecks v0.0.0-20241002141124-24c3d5c5b25a h1:/TuqUOdAUxHQehPOY7zOUMLvQc3W60xXUZWieYiCJyY=
+git.faercol.me/faercol/go-healthchecks v0.0.0-20241002141124-24c3d5c5b25a/go.mod h1:d69XefG7I7Y7XyRajFoNpeyWgt89+OFvxIqjlJwia1E=
+git.faercol.me/faercol/go-healthchecks v0.0.0-20241003132603-97f47d027454 h1:sWDu4XNMwODSzKjmIZOIWLPhEOhReRUVpo4fEVywp6g=
+git.faercol.me/faercol/go-healthchecks v0.0.0-20241003132603-97f47d027454/go.mod h1:d69XefG7I7Y7XyRajFoNpeyWgt89+OFvxIqjlJwia1E=
+github.com/google/uuid v1.1.2 h1:EVhdT+1Kseyi1/pUmXKaFxYsDNy9RQYkMWRH68J/W7Y=
+github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=

internal/config/config.go

@@ -0,0 +1,44 @@
+package config
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+)
+
+type HealthchecksConfig struct {
+	Enabled     bool   `json:"enabled"`
+	HostPingAPI string `json:"host_ping_api"`
+	PingKey     string `json:"ping_key"`
+}
+
+type Config struct {
+	HealthchecksConfig `json:"healthchecks"`
+	LeasesPath         string `json:"leases_path"`
+}
+
+func defaultConfig() *Config {
+	return &Config{
+		HealthchecksConfig: HealthchecksConfig{
+			Enabled: false,
+		},
+		LeasesPath: "/var/lib/misc/dnsmasq.leases",
+	}
+}
+
+func New(path string) (*Config, error) {
+	fileContent, err := os.ReadFile(path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return defaultConfig(), nil
+		}
+		return nil, fmt.Errorf("failed to read config file %w", err)
+	}
+
+	var c Config
+	if err := json.Unmarshal(fileContent, &c); err != nil {
+		return nil, fmt.Errorf("failed to parse config file: %w", err)
+	}
+	return &c, nil
+}

internal/dnsmasq/dnsmasq.go

@@ -0,0 +1,61 @@
+package dnsmasq
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type Lease struct {
+	ExpireDate time.Time
+	Mac        string
+	IP         string
+	Hostname   string
+	ClientID   string
+}
+
+func (l Lease) String() string {
+	return fmt.Sprintf("[expire on %v]: host %s IP %s (mac %s - clientID %s)", l.ExpireDate, l.Hostname, l.IP, l.Mac, l.ClientID)
+}
+
+func parseLeaseLine(rawLine string) (*Lease, error) {
+	lineValues := strings.Split(rawLine, " ")
+	if len(lineValues) != 5 {
+		return nil, fmt.Errorf("unexpected number of values, expected 5, got %d", len(lineValues))
+	}
+
+	expireTimeInt, err := strconv.Atoi(lineValues[0])
+	if err != nil {
+		return nil, fmt.Errorf("unexpected unix timestamp value %s", lineValues[0])
+	}
+
+	return &Lease{
+		ExpireDate: time.Unix(int64(expireTimeInt), 0),
+		Mac:        lineValues[1],
+		IP:         lineValues[2],
+		Hostname:   lineValues[3],
+		ClientID:   lineValues[4],
+	}, nil
+}
+
+func GetLeases(leasesPath string) ([]*Lease, error) {
+	fileContent, err := os.ReadFile(leasesPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read leases file: %w", err)
+	}
+
+	leases := []*Lease{}
+	for i, l := range strings.Split(string(fileContent), "\n") {
+		if l == "" {
+			continue
+		}
+		lease, err := parseLeaseLine(l)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse line %d: %w", i, err)
+		}
+		leases = append(leases, lease)
+	}
+	return leases, nil
+}

internal/healthchecks/healthchecks.go

@@ -0,0 +1,38 @@
+package healthchecks
+
+import (
+	"context"
+	"fmt"
+
+	"git.faercol.me/faercol/dnsmasq-netbox-connector/internal/config"
+	go_healthchecks "git.faercol.me/faercol/go-healthchecks"
+	"github.com/google/uuid"
+)
+
+func Start(ctx context.Context, conf config.HealthchecksConfig, clt go_healthchecks.PingClient) (go_healthchecks.Check, error) {
+	if !conf.Enabled {
+		return nil, nil
+	}
+
+	runID := uuid.New()
+	check, err := go_healthchecks.NewSlugCheck(conf.PingKey, "dnsmasq-netbox-connector", true, runID.String())
+	if err != nil {
+		return nil, fmt.Errorf("failed to create check: %w", err)
+	}
+
+	return check, clt.ReportStart(ctx, check)
+}
+
+func Success(ctx context.Context, conf config.HealthchecksConfig, clt go_healthchecks.PingClient, check go_healthchecks.Check) error {
+	if !conf.Enabled {
+		return nil
+	}
+	return clt.ReportSuccess(ctx, check)
+}
+
+func Failure(ctx context.Context, conf config.HealthchecksConfig, clt go_healthchecks.PingClient, check go_healthchecks.Check, msg string) error {
+	if !conf.Enabled {
+		return nil
+	}
+	return clt.ReportFailure(ctx, check, msg)
+}

main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"git.faercol.me/faercol/dnsmasq-netbox-connector/internal/config"
+	"git.faercol.me/faercol/dnsmasq-netbox-connector/internal/dnsmasq"
+	"git.faercol.me/faercol/dnsmasq-netbox-connector/internal/healthchecks"
+	gohealthchecks "git.faercol.me/faercol/go-healthchecks"
+)
+
+func main() {
+	configPath := "/etc/dnmasq-netbox/config.json"
+
+	if len(os.Args) > 1 {
+		configPath = os.Args[1]
+	}
+
+	conf, err := config.New(configPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to read configuration: %s\n", err)
+		os.Exit(1)
+	}
+
+	healtchecksClt := gohealthchecks.NewPingClient(conf.HostPingAPI)
+
+	check, err := healthchecks.Start(context.Background(), conf.HealthchecksConfig, healtchecksClt)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to notify process start: %s\n", err)
+	}
+
+	leases, err := dnsmasq.GetLeases(conf.LeasesPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to parse leases: %s\n", err)
+		if err := healthchecks.Failure(context.Background(), conf.HealthchecksConfig, healtchecksClt, check, "failed to parse lease file"); err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to notify failure: %s\n", err)
+		}
+		os.Exit(1)
+	}
+
+	for _, l := range leases {
+		fmt.Printf("Got lease %s\n", l)
+	}
+
+	if err := healthchecks.Success(context.Background(), conf.HealthchecksConfig, healtchecksClt, check); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to notify process success: %s\n", err)
+	}
+}