Add option to check validity of certificate

[DaemonBeast]

Issue has been abandoned - revised issue: #30

Abandoned due to flaw: If the old certificate was retrieved, it would not match the newly generated key and would result in an error

Please can you add another option to the client.auto() function called renewIfExpired.

It will have the following properties:

• string data type.
  • contains the directory path of a certificate.
• return value:
  • if the certificate in the specified directory has expired, a new certificate is returned.
  • if the certificate in the specified directory is still valid, it is returned.
• default value: null (new certificate is always generated).
• prevents the rate limit from being reached from unnecessary repeated certificate requests.
• allows the user to use their own certificate and have node-acme-client as a fallback to generate a certificate in case their certificate expires.

---

Possible Implementation

if (renewIfExpired) {
    if (fs.existsSync(renewIfExpired)) {
        var cert = fs.readFileSync(renewIfExpired);
        var expiry = (new Date((await ACME.forge.readCertificateInfo(cert)).notAfter)).valueOf();
        var time = (new Date()).valueOf();

        if (expiry >= time) {
            return cert;
        }
    } else {
        // ERROR: file does not exist
    }
}

// Continue certificate generation

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By the way, thank you so much for such a great package!
I really appreciate the sophisticated code, clear documentation and constant bug fixes (all of the other major ACME clients are either really complicated or have serious bugs).

[Trackhe]

+1

[DaemonBeast]

Issue has been abandoned - revised issue: #30

Abandoned due to flaw: If the old certificate was retrieved, it would not match the newly generated key and would result in an error