func fetchNonce(ctx context.Context, client *http.Client, url string) (string, error) {
resp, err := ctxhttp.Head(ctx, client, url)
if err != nil {
return "", nil
}
defer resp.Body.Close()
enc := resp.Header.Get("replay-nonce")
if enc == "" {
return "", errors.New("acme: nonce not found")
}
return enc, nil
}
func (u *URLFetcher) head(ctx context.Context, url *url.URL) (http.Header, error) {
res, err := ctxhttp.Head(ctx, u.client, url.String())
if err != nil {
return nil, err
}
defer res.Body.Close()
u.StatusCode = res.StatusCode
if u.IsStatusUnauthorized() || u.IsStatusOK() {
return res.Header, nil
}
return nil, fmt.Errorf("Unexpected http code: %d, URL: %s", u.StatusCode, url)
}