yats.git

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package main

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/asn1"
	"encoding/pem"
	"fmt"
	"os"
)

func fileExists(fileName string) bool {
	_, error := os.Stat(fileName)

	if os.IsNotExist(error) {
		return false
	}
	return true
}

func (c *YatsClient) CreateCsr() ([]byte, error) {
	var oidEmailAddress = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 1}

	if fileExists(c.config.TlsKeyFile) {
		fmt.Printf("Private key file already exists: %v\n", c.config.TlsKeyFile)
		os.Exit(-1)
	}

	if fileExists(c.config.TlsCertificate) {
		fmt.Printf("Certificate file already exists: %v\n", c.config.TlsKeyFile)
		os.Exit(-1)
	}

	if ("" == c.config.ClientCnName) || ("" == c.config.ClientOrganization) || ("" == c.config.ClientCnName) {
		fmt.Printf("Client name: [%v], organization: [%v], email address: [%v]\n", c.config.ClientCnName, c.config.ClientOrganization, c.config.ClientCnName)
		fmt.Println("No param can be empty, exiting")
		os.Exit(-1)
	}

	keyBytes, _ := rsa.GenerateKey(rand.Reader, 1024)
	pemdata := pem.EncodeToMemory(
		&pem.Block{
			Type:  "RSA PRIVATE KEY",
			Bytes: x509.MarshalPKCS1PrivateKey(keyBytes),
		},
	)

	os.WriteFile(c.config.TlsKeyFile, pemdata, 0644)

	subj := pkix.Name{
		CommonName: c.config.ClientCnName,
		/*
			Country:            []string{"AU"},
			Province:           []string{"Some-State"},
			Locality:           []string{"MyCity"},
		*/
		Organization: []string{c.config.ClientOrganization},
		//OrganizationalUnit: []string{organizationalUnit},

		ExtraNames: []pkix.AttributeTypeAndValue{
			{
				Type: oidEmailAddress,
				Value: asn1.RawValue{
					Tag:   asn1.TagIA5String,
					Bytes: []byte(c.config.ClientCnName),
				},
			},
		},
	}

	template := x509.CertificateRequest{
		Subject:            subj,
		SignatureAlgorithm: x509.SHA256WithRSA,
	}

	csrBytes, _ := x509.CreateCertificateRequest(rand.Reader, &template, keyBytes)
	pem.Encode(os.Stdout, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csrBytes})

	pemcsrdata := pem.EncodeToMemory(
		&pem.Block{
			Type:  "CERTIFICATE REQUEST",
			Bytes: csrBytes,
		},
	)

	os.WriteFile("csr.pem", pemcsrdata, 0644)
	return pemcsrdata, nil
}