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package monitor
import (
"context"
"fmt"
"net"
"strings"
"time"
"github.com/Fuwn/kaze/internal/config"
)
// DNSMonitor monitors DNS resolution
type DNSMonitor struct {
id string
name string
group string
target string // Domain to resolve
interval time.Duration
timeout time.Duration
retries int
roundResponseTime bool
roundUptime bool
dnsServer string // Optional DNS server
expectedIPs []string // Expected IP addresses
expectedCNAME string // Expected CNAME
recordType string // DNS record type (A, AAAA, CNAME, MX, TXT, etc.)
}
// NewDNSMonitor creates a new DNS monitor
func NewDNSMonitor(cfg config.MonitorConfig) (*DNSMonitor, error) {
// Default to A record if not specified
recordType := "A"
if cfg.RecordType != "" {
recordType = strings.ToUpper(cfg.RecordType)
}
return &DNSMonitor{
id: cfg.ID(),
name: cfg.Name,
group: cfg.Group,
target: cfg.Target,
interval: cfg.Interval.Duration,
timeout: cfg.Timeout.Duration,
retries: cfg.Retries,
roundResponseTime: cfg.RoundResponseTime,
roundUptime: cfg.RoundUptime,
dnsServer: cfg.DNSServer,
expectedIPs: cfg.ExpectedIPs,
expectedCNAME: cfg.ExpectedCNAME,
recordType: recordType,
}, nil
}
// ID returns the unique identifier for this monitor
func (m *DNSMonitor) ID() string {
return m.id
}
// Name returns the monitor's name
func (m *DNSMonitor) Name() string {
return m.name
}
// Group returns the group this monitor belongs to
func (m *DNSMonitor) Group() string {
return m.group
}
// Type returns the monitor type
func (m *DNSMonitor) Type() string {
return "dns"
}
// Target returns the monitor target
func (m *DNSMonitor) Target() string {
return m.target
}
// Interval returns the check interval
func (m *DNSMonitor) Interval() time.Duration {
return m.interval
}
// Retries returns the number of retry attempts
func (m *DNSMonitor) Retries() int {
return m.retries
}
// HideSSLDays returns whether to hide SSL days from display
func (m *DNSMonitor) HideSSLDays() bool {
return false // DNS doesn't use SSL
}
// RoundResponseTime returns whether to round response time
func (m *DNSMonitor) RoundResponseTime() bool {
return m.roundResponseTime
}
// RoundUptime returns whether to round uptime percentage
func (m *DNSMonitor) RoundUptime() bool {
return m.roundUptime
}
// Check performs the DNS resolution check
func (m *DNSMonitor) Check(ctx context.Context) *Result {
result := &Result{
MonitorName: m.id,
Timestamp: time.Now(),
}
// Create resolver
resolver := &net.Resolver{}
if m.dnsServer != "" {
// Use custom DNS server
resolver = &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
d := net.Dialer{Timeout: m.timeout}
return d.DialContext(ctx, "udp", m.dnsServer)
},
}
}
// Create timeout context
timeoutCtx, cancel := context.WithTimeout(ctx, m.timeout)
defer cancel()
start := time.Now()
switch m.recordType {
case "A", "AAAA":
ips, err := resolver.LookupIP(timeoutCtx, "ip", m.target)
result.ResponseTime = time.Since(start)
if err != nil {
result.Status = StatusDown
result.Error = fmt.Errorf("DNS lookup failed: %w", err)
return result
}
if len(ips) == 0 {
result.Status = StatusDown
result.Error = fmt.Errorf("no %s records found", m.recordType)
return result
}
// If expected IPs are specified, verify them
if len(m.expectedIPs) > 0 {
found := false
for _, ip := range ips {
for _, expected := range m.expectedIPs {
if ip.String() == expected {
found = true
break
}
}
if found {
break
}
}
if !found {
result.Status = StatusDegraded
result.Error = fmt.Errorf("expected IPs not found in response")
return result
}
}
result.Status = StatusUp
case "CNAME":
cname, err := resolver.LookupCNAME(timeoutCtx, m.target)
result.ResponseTime = time.Since(start)
if err != nil {
result.Status = StatusDown
result.Error = fmt.Errorf("CNAME lookup failed: %w", err)
return result
}
// If expected CNAME is specified, verify it
if m.expectedCNAME != "" && cname != m.expectedCNAME {
result.Status = StatusDegraded
result.Error = fmt.Errorf("CNAME mismatch: got %s, expected %s", cname, m.expectedCNAME)
return result
}
result.Status = StatusUp
case "MX":
mxs, err := resolver.LookupMX(timeoutCtx, m.target)
result.ResponseTime = time.Since(start)
if err != nil {
result.Status = StatusDown
result.Error = fmt.Errorf("MX lookup failed: %w", err)
return result
}
if len(mxs) == 0 {
result.Status = StatusDown
result.Error = fmt.Errorf("no MX records found")
return result
}
result.Status = StatusUp
case "TXT":
txts, err := resolver.LookupTXT(timeoutCtx, m.target)
result.ResponseTime = time.Since(start)
if err != nil {
result.Status = StatusDown
result.Error = fmt.Errorf("TXT lookup failed: %w", err)
return result
}
if len(txts) == 0 {
result.Status = StatusDown
result.Error = fmt.Errorf("no TXT records found")
return result
}
result.Status = StatusUp
default:
result.ResponseTime = time.Since(start)
result.Status = StatusDown
result.Error = fmt.Errorf("unsupported record type: %s", m.recordType)
}
return result
}
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