Esempio n. 1
0
// FillTemplate is a utility function that tries to load as much of
// the certificate template as possible from the profiles and current
// template. It fills in the key uses, expiration, revocation URLs,
// serial number, and SKI.
func FillTemplate(template *x509.Certificate, defaultProfile, profile *config.SigningProfile, serialSeq string) error {
	ski, err := ComputeSKI(template)

	var (
		eku             []x509.ExtKeyUsage
		ku              x509.KeyUsage
		backdate        time.Duration
		expiry          time.Duration
		notBefore       time.Time
		notAfter        time.Time
		crlURL, ocspURL string
	)

	// The third value returned from Usages is a list of unknown key usages.
	// This should be used when validating the profile at load, and isn't used
	// here.
	ku, eku, _ = profile.Usages()
	if profile.IssuerURL == nil {
		profile.IssuerURL = defaultProfile.IssuerURL
	}

	if ku == 0 && len(eku) == 0 {
		return cferr.New(cferr.PolicyError, cferr.NoKeyUsages)
	}

	if expiry = profile.Expiry; expiry == 0 {
		expiry = defaultProfile.Expiry
	}

	if crlURL = profile.CRL; crlURL == "" {
		crlURL = defaultProfile.CRL
	}
	if ocspURL = profile.OCSP; ocspURL == "" {
		ocspURL = defaultProfile.OCSP
	}
	if backdate = profile.Backdate; backdate == 0 {
		backdate = -5 * time.Minute
	} else {
		backdate = -1 * profile.Backdate
	}

	if !profile.NotBefore.IsZero() {
		notBefore = profile.NotBefore.UTC()
	} else {
		notBefore = time.Now().Round(time.Minute).Add(backdate).UTC()
	}

	if !profile.NotAfter.IsZero() {
		notAfter = profile.NotAfter.UTC()
	} else {
		notAfter = notBefore.Add(expiry).UTC()
	}

	serialNumber, err := rand.Int(rand.Reader, new(big.Int).SetInt64(math.MaxInt64))

	if err != nil {
		return cferr.Wrap(cferr.CertificateError, cferr.Unknown, err)
	}

	if serialSeq != "" {
		randomPart := fmt.Sprintf("%016X", serialNumber) // 016 ensures we're left-0-padded
		_, ok := serialNumber.SetString(serialSeq+randomPart, 16)
		if !ok {
			return cferr.Wrap(cferr.CertificateError, cferr.SerialSeqParseError, err)
		}
	}

	template.SerialNumber = serialNumber
	template.NotBefore = notBefore
	template.NotAfter = notAfter
	template.KeyUsage = ku
	template.ExtKeyUsage = eku
	template.BasicConstraintsValid = true
	template.IsCA = profile.CA
	template.SubjectKeyId = ski

	if ocspURL != "" {
		template.OCSPServer = []string{ocspURL}
	}
	if crlURL != "" {
		template.CRLDistributionPoints = []string{crlURL}
	}

	if len(profile.IssuerURL) != 0 {
		template.IssuingCertificateURL = profile.IssuerURL
	}
	if len(profile.Policies) != 0 {
		template.PolicyIdentifiers = profile.Policies
	}
	if profile.OCSPNoCheck {
		ocspNoCheckExtension := pkix.Extension{
			Id:       asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 1, 5},
			Critical: false,
			Value:    []byte{0x05, 0x00},
		}
		template.ExtraExtensions = append(template.ExtraExtensions, ocspNoCheckExtension)
	}

	return nil
}