302 lines
9.0 KiB
Markdown
302 lines
9.0 KiB
Markdown
letsencrypt
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===========
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Let's Encrypt for node.js
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This allows you to get Free SSL Certificates for Automatic HTTPS.
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NOT YET PUBLISHED
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============
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* Dec 12 2015: gettin' really close
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* Dec 11 2015: almost done (node-letsencrypt-python complete)
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* Dec 10 2015: began tinkering
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Install
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=======
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```bash
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npm install --save letsencrypt
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```
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Right now this uses [`letsencrypt-python`](https://github.com/Daplie/node-letsencrypt-python),
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but it's built to be able to use a pure javasript version.
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```bash
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# install the python client (takes 2 minutes normally, 20 on a rasberry pi)
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git clone https://github.com/letsencrypt/letsencrypt
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pushd letsencrypt
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./letsencrypt-auto
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```
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Usage Examples
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========
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Here's a small snippet:
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```javascript
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le.register({
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domains: ['example.com', 'www.example.com']
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, email: 'user@example.com'
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, agreeTos: true
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}, function (err, certs) {
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// do stuff
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});
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```
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**However**, due to the nature of what this library does, it has a few more "moving parts"
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than what makes sense to show in a minimal snippet.
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* [commandline (standalone with "webroot")](https://github.com/Daplie/node-letsencrypt/blob/master/examples/commandline.js)
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* [expressjs (fully automatic https)](https://github.com/Daplie/node-letsencrypt/blob/master/examples/express.js)
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See Also
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========
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* See [Examples](https://github.com/Daplie/node-letsencrypt/tree/master/examples)
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* [Let's Encrypt in (exactly) 90 seconds with Caddy](https://daplie.com/articles/lets-encrypt-in-literally-90-seconds/)
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* [lego](https://github.com/xenolf/lego): Let's Encrypt for golang
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API
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===
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* `LetsEncrypt.create(backend, bkDefaults, handlers)`
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* `le.middleware()`
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* `le.sniCallback(hostname, function (err, tlsContext) {})`
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* `le.register({ domains, email, agreeTos, ... }, cb)`
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* `le.fetch({domains, email, agreeTos, ... }, cb)`
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* `le.validate(domains, cb)`
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### `LetsEncrypt.create(backend, bkDefaults, handlers)`
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#### backend
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Currently only `letsencrypt-python` is supported, but we plan to work on
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native javascript support in February or so (when ECDSA keys are available).
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If you'd like to help with that, see **how to write a backend** below and also
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look at the wrapper `backend-python.js`.
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**Example**:
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```javascript
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{ fetch: function (args, cb) {
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// cb(err) when there is an actual error (db, fs, etc)
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// cb(null, null) when the certificate was NOT available on disk
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// cb(null, { cert: '<fullchain.pem>', key: '<privkey.pem>', renewedAt: 0, duration: 0 }) cert + meta
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}
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, register: function (args, setChallenge, cb) {
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// setChallenge(hostnames, key, value, cb) when a challenge needs to be set
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// cb(err) when there is an error
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// cb(null, null) when the registration is successful, but fetch still needs to be called
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// cb(null, cert /*see above*/) if registration can easily return the same as fetch
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}
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}
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```
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#### bkDefualts
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The arguments passed here (typically `webpathRoot`, `configDir`, etc) will be merged with
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any `args` (typically `domains`, `email`, and `agreeTos`) and passed to the backend whenever
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it is called.
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Typically the backend wrapper will already merge any necessary backend-specific arguments.
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**Example**:
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```javascript
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{ webrootPath: __dirname, '/acme-challenge'
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, fullchainTpl: '/live/:hostname/fullchain.pem'
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, privkeyTpl: '/live/:hostname/fullchain.pem'
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, configDir: '/etc/letsencrypt'
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}
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```
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#### handlers *optional*
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`h.setChallenge(hostnames, name, value, cb)`:
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default is to write to fs
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`h.getChallenge(hostnames, value cb)`
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default is to read from fs
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`h.sniRegisterCallback(args, currentCerts, cb)`
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The default is to immediately call `cb(null, null)` and register (or renew) in the background
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during the `SNICallback` phase. Right now it isn't reasonable to renew during SNICallback,
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but around February when it is possible to use ECDSA keys (as opposed to RSA at present),
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registration will take very little time.
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This will not be called while another registration is already in progress.
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**SECURITY WARNING**: If you use this option with a custom `h.validate()`, make sure that `args.domains`
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refers to domains you expect, otherwise an attacker will spoof SNI and cause your server to rate-limit
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letsencrypt.org and get blocked. Note that `le.validate()` will check A records before attempting to
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register to help prevent such possible attacks.
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`h.validate(domains, cb)`
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When specified this will override `le.validate()`. You will need to do this if the ip address of this
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server is not one specified in the A records for your domain.
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### `le.middleware()`
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An express handler for `/.well-known/acme-challenge/<challenge>`.
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Will call `getChallenge([hostname], key, cb)` if present or otherwise read `challenge` from disk.
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Example:
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```javascript
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app.use('/', le.middleware())
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```
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### `le.sniCallback(hostname, function (err, tlsContext) {});`
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Will call `fetch`. If fetch does not return certificates or returns expired certificates
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it will call `sniRegisterCallback(args, currentCerts, cb)` and then return the error,
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the new certificates, or call `fetch` a final time.
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Example:
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```javascript
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var server = require('https').createServer({ SNICallback: le.sniCallback });
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server.on('request', app);
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```
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### `le.register({ domains, email, agreeTos, ... }, cb)`
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Get certificates for a domain
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Example:
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```javascript
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le.register({
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domains: ['example.com', 'www.example.com']
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, email: 'user@example.com'
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, agreeTos: true
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}, function (err, certs) {
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// err is some error
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console.log(certs);
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/*
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{ cert: "contents of fullchain.pem"
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, key: "contents of privkey.pem"
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, renewedAt: <date in milliseconds>
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, duration: <duration in milliseconds (90-days)>
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}
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*/
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});
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```
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### `le.isValidDomain(hostname)`
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returns `true` if `hostname` is a valid ascii or punycode domain name.
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(also exposed on the main exported module as `LetsEncrypt.isValidDomain()`)
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### `le.validate(args, cb)`
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Used internally, but exposed for convenience. Checks `LetsEncrypt.isValidDomain()`
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and then checks to see that the current server
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Called before `backend.register()` to validate the following:
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* the hostnames don't use any illegal characters
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* the server's actual public ip (via api.apiify.org)
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* the A records for said hostnames
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### `le.fetch(args, cb)`
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Used internally, but exposed for convenience.
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Checks in-memory cache of certificates for `args.domains` and calls then calls `backend.fetch(args, cb)`
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**after** merging `args` if necessary.
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Backends
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--------
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* [`letsencrypt-python`](https://github.com/Daplie/node-letsencrypt-python) (complete)
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* [`lejs`](https://github.com/Daplie/node-lejs) (in progress)
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#### How to write a backend
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A backend must implement (or be wrapped to implement) this API:
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* fetch(hostname, cb) will cb(err, certs) will get registered certs or null unless there is an error
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* register(args, challengeCb, done) will register and or renew a cert
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* args = `{ domains, email, agreeTos }` MUST check that agreeTos === true
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* challengeCb = `function (challenge, cb) { }` handle challenge as needed, call cb()
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This is what `args` looks like:
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```javascript
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{ domains: ['example.com', 'www.example.com']
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, email: 'user@email.com'
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, agreeTos: true
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, configDir: '/etc/letsencrypt'
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, fullchainTpl: '/live/:hostname/fullchain.pem' // :hostname will be replaced with the domainname
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, privkeyTpl: '/live/:hostname/privkey.pem' // :hostname
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}
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```
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This is what the implementation should look like:
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(it's expected that the client will follow the same conventions as
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the python client, but it's not necessary)
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```javascript
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return {
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fetch: function (args, cb) {
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// NOTE: should return an error if args.domains cannot be satisfied with a single cert
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// (usually example.com and www.example.com will be handled on the same cert, for example)
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if (errorHappens) {
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// return an error if there is an actual error (db, etc)
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cb(err);
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return;
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}
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// return null if there is no error, nor a certificate
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else if (!cert) {
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cb(null, null);
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return;
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}
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// NOTE: if the certificate is available but expired it should be
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// returned and the calling application will decide to renew when
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// it is convenient
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// NOTE: the application should handle caching, not the library
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// return the cert with metadata
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cb(null, {
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cert: "/*contcatonated certs in pem format: cert + intermediate*/"
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, key: "/*private keypair in pem format*/"
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, renewedAt: new Date() // fs.stat cert.pem should also work
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, duration: 90 * 24 * 60 * 60 * 1000 // assumes 90-days unless specified
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});
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}
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, register: function (args, challengeCallback, completeCallback) {
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// **MUST** reject if args.agreeTos is not true
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// once you're ready for the caller to know the challenge
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if (challengeCallback) {
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challengeCallback(challenge, function () {
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continueRegistration();
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})
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} else {
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continueRegistration();
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}
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function continueRegistration() {
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// it is not necessary to to return the certificates here
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// the client will call fetch() when it needs them
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completeCallback(err);
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}
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}
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};
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```
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LICENSE
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=======
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Dual-licensed MIT and Apache-2.0
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See LICENSE
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