Retrieve a certificate

cert-plan9.go

package main

import (
	"context"
	"crypto/tls"
	"flag"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"

	"github.com/lufia/httpclientutil"
	"golang.org/x/crypto/acme/autocert"
)

var (
	flagDir    = flag.String("dir", ".", "certificate cache dir")
	flagDomain = flag.String("dom", "example.com", "domain")
)

func main() {
	flag.Parse()
	log.SetFlags(0)

	m := &autocert.Manager{
		Cache:      autocert.DirCache(*flagDir),
		Prompt:     autocert.AcceptTOS,
		HostPolicy: autocert.HostWhitelist(*flagDomain),
		ForceRSA:   true, // no longer effect
	}
	go http.ListenAndServe(":http", m.HTTPHandler(nil))
	s := &http.Server{
		Addr: ":https",
		TLSConfig: &tls.Config{
			GetCertificate: m.GetCertificate,
		},
	}
	go s.ListenAndServeTLS("", "")

	// Plan 9 haven't supported ECDSA algorithm
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{
			CipherSuites: []uint16{
				tls.TLS_RSA_WITH_AES_256_CBC_SHA,
				tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
			},
		},
	}
	http.DefaultClient.Transport = &httpclientutil.RetriableTransport{
		Transport: tr,
	}
	var u url.URL
	u.Scheme = "https"
	u.Host = *flagDomain
	resp, err := http.Get(u.String())
	if err != nil {
		log.Fatalln(err)
	}
	io.Copy(os.Stdout, resp.Body)
	resp.Body.Close()
	s.Shutdown(context.Background())
}

golang/crypto@8f8078c