cert.go

package certmon

import (
	"crypto/tls"
	"crypto/x509"
	"net"
	"time"
)

type Cert struct {
	ID           int      `json:"id"`
	Addr         string   `json:"addr"`
	DNS          string   `json:"dns"` // for customized DNS resolution, optional
	UpdateTime   JSONTime `json:"updateTime"`
	DaysLeft     int      `json:"daysLeft"`
	UpdateStatus string   `json:"updateStatus"`
}

func (c *Cert) Update(rootCAs *x509.CertPool) {
	cert, err := CheckCert(c.Addr, c.DNS, rootCAs)
	c.UpdateStatus = "ok"
	c.UpdateTime = JSONTime(time.Now())

	if err != nil {
		c.UpdateStatus = err.Error()
		return
	}
	c.DaysLeft = int(time.Until(cert.NotAfter) / (time.Hour * 24))
}

func CheckCert(addr, dns string, rootCAs *x509.CertPool) (*x509.Certificate, error) {
	cfg := &tls.Config{
		ServerName: dns,
		RootCAs:    rootCAs,
	}

	dialer := &net.Dialer{
		Timeout: time.Second * 10,
	}
	conn, err := tls.DialWithDialer(dialer, "tcp", addr, cfg)
	if err != nil {
		return nil, err
	}
	cert := conn.ConnectionState().PeerCertificates[0]
	return cert, nil
}