在golang

Question

我正在尝试使用cli命令openssl s_client -connect www.yahoo.no:443 2> /dev/null | openssl x509 -noout -enddate | cut -d = -f 2读取远程网站ssl证书。

这在cli中工作正常，但是当我在golang中执行它时：

package main

import (
    "bytes"
    "log"
    "os/exec"
    "time"
)

func main() {
    cmd := exec.Command("echo", "| openssl s_client -connect www.yahoo.com:443 2> /dev/null | openssl x509 -noout -enddate | cut -d = -f 2")
    var out bytes.Buffer
    cmd.Stdout = &out
    err := cmd.Run()

    log.Println(out.String())
}

我一无所获。如何在go中运行此命令？

更新：

这是我尝试过的但没有成功

func command() {

    cmd1 := exec.Command("openssl", "s_client", "-connect", "www.yahoo.no:443", "2>", "/dev/null")
    cmd2 := exec.Command("openssl", "x509", "-noout", "-enddate")

    var out bytes.Buffer

    reader, writer := io.Pipe()
    cmd1.Stdout = writer
    cmd2.Stdin = reader

    cmd2.Stdout = &out

    cmd1.Start()
    cmd2.Start()

    cmd1.Wait()
    writer.Close()

    cmd2.Wait()
    reader.Close()

    io.Copy(&out, reader)
    log.Println(out.String())

}

我得到空的答复。

Answer 1

Go的标准库包含功能完善的TLS实现，因此实际上没有理由启动两个繁重的openssl进程：

package main

import (
    "crypto/tls"
    "fmt"
    "log"
    "net"
    "time"
)

func main() {
    conn, err := net.Dial("tcp", "example.com:443")
    if err != nil {
            log.Fatal(err)
    }

    client := tls.Client(conn, &tls.Config{
            ServerName: "example.com",
    })
    defer client.Close()

    if err := client.Handshake(); err != nil {
            log.Fatal(err)
    }

    cert := client.ConnectionState().PeerCertificates[0]
    fmt.Println(cert.NotAfter.Format(time.RFC3339)) // Output: 2020-12-02T12:00:00Z
}