自从云厂商的免费ssl证书改成3个月，而且证书数量还是20个之后，自己网站的ssl证书就换成了其它免费方案。但是免费方案不会提醒证书过期，所以写个工具每天定时查询证书剩余有效天数，如果证书即将过期，就发送邮件提醒。
基本实现
最基本的代码功能就是检测网站ssl证书的有效天数，可以用命令行传参的方式指定网站域名。
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package main
import (
"crypto/tls"
"flag"
"fmt"
"net"
"os"
"sync"
"time"
)
var (
port int
wg sync.WaitGroup
)
func checkssl(domain string, port int) {
defer wg.Done()
host := fmt.Sprintf("%s:%d", domain, port)
conn, err := tls.DialWithDialer(&net.Dialer{
Timeout: time.Second * 5,
Deadline: time.Now().Add(time.Second * 5),
}, "tcp", host, &tls.Config{InsecureSkipVerify: true})
if err != nil {
fmt.Println(err)
return
}
defer conn.Close()
stats := conn.ConnectionState()
certs := stats.PeerCertificates[0]
localtz, _ := time.LoadLocation("Asia/Shanghai")
issueTime := certs.NotBefore.In(localtz)
expireTime := certs.NotAfter.In(localtz)
today := time.Now().In(localtz)
dayLeft := int(expireTime.Sub(today).Hours() / 24)
fmt.Printf("%s, issue time: %v, expire time: %v, days left: %v\n", domain, issueTime, expireTime, dayLeft)
}
func main() {
flag.IntVar(&port, "p", 443, "port, example: ./checkssl -p 1443 <domain name>")
flag.Parse()
positionArgs := flag.Args()
if len(positionArgs) == 0 {
fmt.Println("Error: Missing domain name")
fmt.Println("Usage: ./checkssl <domain name>")
os.Exit(1)
}
wg.Add(len(positionArgs))
for _, arg := range positionArgs {
go checkssl(arg, port)
}
wg.Wait()
}
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使用示例
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# 1. 编译
go build
# 2. 命令行传参的方式指定域名
./check-ssl baidu.com ithome.com qq.com
# 输出
baidu.com, issue time: 2024-01-30 08:00:00 +0800 CST, expire time: 2025-03-02 07:59:59 +0800 CST, days left: 187
ithome.com, issue time: 2024-01-22 08:00:00 +0800 CST, expire time: 2025-02-22 07:59:59 +0800 CST, days left: 179
qq.com, issue time: 2024-06-04 08:00:00 +0800 CST, expire time: 2025-06-11 07:59:59 +0800 CST, days left: 288
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完善功能
需要完善的功能主要是发送邮件，这里使用SMTP协议来发送邮件。如果跟我一样用的是163邮箱，则需要先去获取一个SMTP的授权码。
因为需要配置SMTP的连接信息，所以改成了用文件来传入配置，也方便后期修改。配置文件config.yaml示例：
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domains:
- baidu.com
- qq.com
email:
smtp:
host: "smtp.163.com" # smtp服务器的地址
port: 465 # 因为云服务器屏蔽了25端口, 只能使用tls加密的465端口
from: "" # 发送方邮箱
token: "" # 授权码
sendto:
- "qq@qq.com" # 接收方的邮箱地址
expire: 7 # 证书剩余有效天数, 小于7天时发送邮件提醒
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读取配置的代码文件config.go，使用viper来读取配置文件。
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package main
import "github.com/spf13/viper"
var (
v *viper.Viper
)
type SMTPServer struct {
Host string
Port int
Token string
From string
}
func initViper() {
v = viper.New()
v.AddConfigPath(".")
v.SetConfigType("yaml")
v.SetConfigFile(configfile)
err := v.ReadInConfig()
if err != nil {
panic(err)
}
}
type configer struct{}
func NewConfiger() configer {
if v == nil {
initViper()
}
return configer{}
}
func (c configer) GetSMTPServer() SMTPServer {
return SMTPServer{
Host: v.GetString("email.smtp.host"),
Port: v.GetInt("email.smtp.port"),
Token: v.GetString("email.smtp.token"),
From: v.GetString("email.smtp.from"),
}
}
func (c configer) GetDomains() []string {
return v.GetStringSlice("domains")
}
func (c configer) GetSendTos() []string {
return v.GetStringSlice("email.sendto")
}
func (c configer) GetExpiry() int {
return v.GetInt("email.expire")
}
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发送邮件的相关代码文件：notify.go
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package main
import (
"crypto/tls"
"fmt"
"net/smtp"
"github.com/jordan-wright/email"
)
type Postman struct {
SmtpServer SMTPServer
SendTos []string
}
func (p Postman) SendEmail(domain string, dayleft int) {
auth := smtp.PlainAuth("", p.SmtpServer.From, p.SmtpServer.Token, p.SmtpServer.Host)
e := &email.Email{
To: p.SendTos,
From: fmt.Sprintf("YXHYW <%s>", p.SmtpServer.From),
Subject: fmt.Sprintf("域名 %s SSL证书过期提醒", domain),
Text: []byte(fmt.Sprintf("域名 %s 的SSL证书即将过期, 剩余有效期 %d 天", domain, dayleft)),
}
// err := e.Send(fmt.Sprintf("%s:%d", p.SmtpServer.Host, p.SmtpServer.Port), auth)
addr := fmt.Sprintf("%s:%d", p.SmtpServer.Host, p.SmtpServer.Port)
fmt.Println("SMTP Server addr: ", addr)
err := e.SendWithTLS(addr, auth, &tls.Config{
InsecureSkipVerify: false,
ServerName: p.SmtpServer.Host,
})
if err != nil {
fmt.Printf("Send email failed, %v\n", err)
}
}
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主体代码文件main.go，主要修改地方：检测到证书即将过期后，调用发送邮件的相关方法。
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package main
import (
"crypto/tls"
"flag"
"fmt"
"net"
"sync"
"time"
)
var (
port int
configfile string
wg sync.WaitGroup
c configer = NewConfiger()
)
func checkssl(domain string, port int) {
defer wg.Done()
host := fmt.Sprintf("%s:%d", domain, port)
conn, err := tls.DialWithDialer(&net.Dialer{
Timeout: time.Second * 5,
Deadline: time.Now().Add(time.Second * 5),
}, "tcp", host, &tls.Config{InsecureSkipVerify: true})
if err != nil {
fmt.Println(err)
return
}
defer conn.Close()
stats := conn.ConnectionState()
certs := stats.PeerCertificates[0]
localtz, _ := time.LoadLocation("Asia/Shanghai")
issueTime := certs.NotBefore.In(localtz)
expireTime := certs.NotAfter.In(localtz)
today := time.Now().In(localtz)
dayLeft := int(expireTime.Sub(today).Hours() / 24)
fmt.Printf("%s, issue time: %v, expire time: %v, days left: %v\n", domain, issueTime, expireTime, dayLeft)
// c := NewConfiger()
if dayLeft < c.GetExpiry() {
p := Postman{SmtpServer: c.GetSMTPServer(), SendTos: c.GetSendTos()}
p.SendEmail(domain, dayLeft)
}
}
func main() {
flag.IntVar(&port, "p", 443, "port, example: ./check-ssl -p 1443 <domain name>")
flag.StringVar(&configfile, "c", "config.yaml", "config file")
flag.Parse()
conf := NewConfiger()
domains := conf.GetDomains()
wg.Add(len(domains))
for _, arg := range domains {
go checkssl(arg, port)
}
wg.Wait()
}
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本地测试通过后，可以配到服务器的crontab中每天执行。
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