boulder/vendor/github.com/eggsampler/acme/v3/ari.go

132 lines
3.4 KiB
Go

package acme
import (
_ "crypto/sha1"
_ "crypto/sha256"
_ "crypto/sha512"
"crypto/x509"
"encoding/asn1"
"encoding/base64"
"fmt"
"math/rand"
"net/http"
"strconv"
"strings"
"time"
)
// GetRenewalInfo returns the renewal information (if present and supported by
// the ACME server), and a Retry-After time if indicated in the http response
// header.
func (c Client) GetRenewalInfo(cert *x509.Certificate) (RenewalInfo, error) {
if c.dir.RenewalInfo == "" {
return RenewalInfo{}, ErrRenewalInfoNotSupported
}
certID, err := GenerateARICertID(cert)
if err != nil {
return RenewalInfo{}, fmt.Errorf("acme: error generating certificate id: %v", err)
}
renewalURL := c.dir.RenewalInfo
if !strings.HasSuffix(renewalURL, "/") {
renewalURL += "/"
}
renewalURL += certID
var ri RenewalInfo
resp, err := c.get(renewalURL, &ri, http.StatusOK)
if err != nil {
return ri, err
}
defer resp.Body.Close()
ri.RetryAfter, err = parseRetryAfter(resp.Header.Get("Retry-After"))
return ri, err
}
// GenerateARICertID constructs a certificate identifier as described in
// draft-ietf-acme-ari-03, section 4.1.
func GenerateARICertID(cert *x509.Certificate) (string, error) {
if cert == nil {
return "", fmt.Errorf("certificate not found")
}
derBytes, err := asn1.Marshal(cert.SerialNumber)
if err != nil {
return "", err
}
if len(derBytes) < 3 {
return "", fmt.Errorf("invalid DER encoding of serial number")
}
// Extract only the integer bytes from the DER encoded Serial Number
// Skipping the first 2 bytes (tag and length). The result is base64url
// encoded without padding.
serial := base64.RawURLEncoding.EncodeToString(derBytes[2:])
// Convert the Authority Key Identifier to base64url encoding without
// padding.
aki := base64.RawURLEncoding.EncodeToString(cert.AuthorityKeyId)
// Construct the final identifier by concatenating AKI and Serial Number.
return fmt.Sprintf("%s.%s", aki, serial), nil
}
func (r RenewalInfo) ShouldRenewAt(now time.Time, willingToSleep time.Duration) *time.Time {
// Explicitly convert all times to UTC.
now = now.UTC()
start := r.SuggestedWindow.Start.UTC()
end := r.SuggestedWindow.End.UTC()
// Select a uniform random time within the suggested window.
window := end.Sub(start)
randomDuration := time.Duration(rand.Int63n(int64(window)))
randomTime := start.Add(randomDuration)
// If the selected time is in the past, attempt renewal immediately.
if randomTime.Before(now) {
return &now
}
// Otherwise, if the client can schedule itself to attempt renewal at
// exactly the selected time, do so.
willingToSleepUntil := now.Add(willingToSleep)
if willingToSleepUntil.After(randomTime) || willingToSleepUntil.Equal(randomTime) {
return &randomTime
}
return nil
}
// timeNow and implementations support testing
type timeNow interface {
Now() time.Time
}
type currentTimeNow struct{}
func (currentTimeNow) Now() time.Time {
return time.Now()
}
var systemTime timeNow = currentTimeNow{}
func parseRetryAfter(ra string) (time.Time, error) {
retryAfterString := strings.TrimSpace(ra)
if len(retryAfterString) == 0 {
return time.Time{}, nil
}
if retryAfterTime, err := time.Parse(time.RFC1123, retryAfterString); err == nil {
return retryAfterTime, nil
}
if retryAfterInt, err := strconv.Atoi(retryAfterString); err == nil {
return systemTime.Now().Add(time.Second * time.Duration(retryAfterInt)), nil
}
return time.Time{}, fmt.Errorf("invalid time format: %s", retryAfterString)
}