70 lines
1.6 KiB
Go
70 lines
1.6 KiB
Go
package monitor
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import (
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"context"
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"fmt"
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"net"
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"time"
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"arclineit/arcline-uptime/internal/config"
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)
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// DNSChecker resolves a hostname and optionally asserts a specific IP is returned.
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type DNSChecker struct {
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cfg config.MonitorConfig
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timeout time.Duration
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}
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func NewDNSChecker(cfg config.MonitorConfig, timeout time.Duration) *DNSChecker {
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return &DNSChecker{cfg: cfg, timeout: timeout}
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}
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func (d *DNSChecker) Name() string { return d.cfg.Name }
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func (d *DNSChecker) Interval() time.Duration { return time.Duration(d.cfg.Interval) * time.Second }
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func (d *DNSChecker) Check() Result {
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start := time.Now()
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result := Result{
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MonitorName: d.cfg.Name,
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CheckedAt: start,
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}
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ctx, cancel := context.WithTimeout(context.Background(), d.timeout)
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defer cancel()
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addrs, err := net.DefaultResolver.LookupHost(ctx, d.cfg.Host)
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result.ResponseTime = time.Since(start)
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if err != nil {
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result.Error = err.Error()
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return result
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}
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if d.cfg.ExpectedIP != "" {
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want := normalizeIP(d.cfg.ExpectedIP)
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found := false
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for _, addr := range addrs {
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if normalizeIP(addr) == want {
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found = true
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break
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}
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}
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if !found {
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result.Error = fmt.Sprintf("expected IP %q not found in results %v", d.cfg.ExpectedIP, addrs)
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return result
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}
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}
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result.Up = true
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applyThreshold(&result, d.cfg.MaxResponseMS)
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return result
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}
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// normalizeIP parses and re-serialises an IP string so different representations
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// of the same address compare equal (e.g. "::1" and "0:0:0:0:0:0:0:1").
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func normalizeIP(s string) string {
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if ip := net.ParseIP(s); ip != nil {
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return ip.String()
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}
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return s
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}
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