122 lines
3.8 KiB
Go
122 lines
3.8 KiB
Go
package main
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import (
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"crypto/tls"
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"crypto/x509"
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"flag"
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"fmt"
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"strings"
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"time"
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"nocternity.net/monitoring/perfdata"
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"nocternity.net/monitoring/plugin"
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)
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type cliFlags struct {
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hostname string
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port int
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warn int
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crit int
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ignoreCnOnly bool
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}
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func handleCli(p *plugin.Plugin) (flags *cliFlags) {
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flags = &cliFlags{}
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flag.StringVar(&flags.hostname, "hostname", "", "Host name to connect to.")
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flag.StringVar(&flags.hostname, "H", "", "Host name to connect to (shorthand).")
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flag.IntVar(&flags.port, "port", -1, "Port to connect to.")
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flag.IntVar(&flags.port, "P", -1, "Port to connect to (shorthand).")
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flag.IntVar(&flags.warn, "warning", -1, "Validity threshold below which a warning state is issued, in days.")
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flag.IntVar(&flags.warn, "W", -1, "Validity threshold below which a warning state is issued, in days (shorthand).")
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flag.IntVar(&flags.crit, "critical", -1, "Validity threshold below which a critical state is issued, in days.")
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flag.IntVar(&flags.crit, "C", -1, "Validity threshold below which a critical state is issued, in days (shorthand).")
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flag.BoolVar(&flags.ignoreCnOnly, "ignore-cn-only", false,
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"Do not issue warnings regarding certificates that do not use SANs at all.")
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flag.Parse()
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return
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}
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func checkFlags(p *plugin.Plugin, flags *cliFlags) bool {
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if flags.hostname == "" {
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p.SetState(plugin.UNKNOWN, "no hostname specified")
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return false
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}
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if flags.port < 1 || flags.port > 65535 {
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p.SetState(plugin.UNKNOWN, "invalid or missing port number")
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return false
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}
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if flags.warn != -1 && flags.crit != -1 && flags.warn <= flags.crit {
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p.SetState(plugin.UNKNOWN, "nonsensical thresholds")
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return false
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}
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flags.hostname = strings.ToLower(flags.hostname)
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return true
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}
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func findHostname(cert *x509.Certificate, hostname string) bool {
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for _, name := range cert.DNSNames {
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if strings.ToLower(name) == hostname {
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return true
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}
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}
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return false
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}
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func main() {
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p := plugin.New("Certificate check")
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defer p.Done()
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flags := handleCli(p)
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if !checkFlags(p, flags) {
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return
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}
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tls_cfg := &tls.Config{
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InsecureSkipVerify: true,
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MinVersion: tls.VersionTLS10,
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}
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tls_conn, tls_err := tls.Dial("tcp", fmt.Sprintf("%s:%d", flags.hostname, flags.port), tls_cfg)
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if tls_err != nil {
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p.SetState(plugin.UNKNOWN, fmt.Sprintf("connection failed: %s", tls_err))
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return
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}
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defer tls_conn.Close()
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if hsk_err := tls_conn.Handshake(); hsk_err != nil {
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p.SetState(plugin.UNKNOWN, fmt.Sprintf("handshake failed: %s", hsk_err))
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return
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}
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certificate := tls_conn.ConnectionState().PeerCertificates[0]
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if len(certificate.DNSNames) == 0 {
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if !flags.ignoreCnOnly {
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p.SetState(plugin.WARNING, "certificate doesn't have SAN domain names")
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return
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}
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dn := strings.ToLower(certificate.Subject.String())
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if !strings.HasPrefix(dn, fmt.Sprintf("cn=%s,", flags.hostname)) {
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p.SetState(plugin.ERROR, "incorrect certificate CN")
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return
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}
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} else if !findHostname(certificate, flags.hostname) {
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p.SetState(plugin.ERROR, "host name not found in SAN domain names")
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return
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}
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timeLeft := certificate.NotAfter.Sub(time.Now())
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tlDays := int((timeLeft + 86399*time.Second) / (24 * time.Hour))
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if flags.crit > 0 && tlDays <= flags.crit {
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p.SetState(plugin.ERROR, fmt.Sprintf("certificate will expire in %d days (<= %d)", tlDays, flags.crit))
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} else if flags.warn > 0 && tlDays <= flags.warn {
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p.SetState(plugin.WARNING, fmt.Sprintf("certificate will expire in %d days (<= %d)", tlDays, flags.warn))
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} else {
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p.SetState(plugin.OK, fmt.Sprintf("certificate will expire in %d days", tlDays))
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}
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var pdat perfdata.PerfData
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pdat = perfdata.New("validity", perfdata.UOM_NONE, fmt.Sprintf("%d", tlDays))
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if flags.crit > 0 {
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pdat.SetCrit(perfdata.PDRMax(fmt.Sprint(flags.crit)))
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}
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if flags.warn > 0 {
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pdat.SetWarn(perfdata.PDRMax(fmt.Sprint(flags.warn)))
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}
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p.AddPerfData(pdat)
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}
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