Merge branch 'lordelph-master'

# Conflicts:
#	src/Data/Authorization.php

README.md

@@ -117,6 +117,53 @@ foreach ($authorizations as $authorization) {
 The code above will first perform a self test and, if successful, will do 15 attempts to ask LetsEncrypt to validate the challenge (with 1 second intervals) and
 retrieve an updated status (it might take Lets Encrypt a few seconds to validate the challenge).
 
+### Alternative ownership validation via DNS
+
+You can also use DNS validation - to do this, you will need access to an API for your DNS 
+provider to create TXT records for the target domains.
+
+```php
+
+//store a map of domain=>TXT record we can use to wait with
+$dnsRecords[];
+
+foreach ($authorizations as $authorization) {
+    $challenge = $authorization->getDnsChallenge();
+
+    $txtRecord = $authorization->getTxtRecord($challenge);
+    
+    $domain=$authorization->getDomain();
+    $validationDomain='_acme-challenge.'.$domain;
+    
+    //remember the record we're about to set
+    $dnsRecords[$validationDomain] = $txtRecord;
+
+    //set TXT record for $validationDomain to $txtRecord value  
+    //--
+    //-- you need to add code for your DNS provider here 
+    //--
+}
+```
+
+A helper is included which will allow you to wait until you can see the
+DNS changes before asking Let's Encrypt to validate it, e.g.
+
+```php
+//wait up to 60 seconds for all our DNS updates to propagate
+if (!Helper::waitForDNS($dnsRecords, 60)) {
+    throw new \Exception('Unable to verify TXT record update');
+}
+```
+
+Once this passes we can ask Let's Encrypt to do the same...
+
+```php
+foreach ($authorizations as $authorization) {
+    $ok = $client->validate($authorization->getDnsChallenge(), 15);
+}
+```
+
+
 ### Get the certificate
 
 Now to know if we can request a certificate for the order, test if the order is ready as follows:

src/Client.php

@@ -55,6 +55,11 @@ class Client
      */
     const VALIDATION_HTTP = 'http-01';
 
+    /**
+     * DNS validation
+     */
+    const VALIDATION_DNS = 'dns-01';
+
     /**
      * @var string
      */

src/Data/Authorization.php

@@ -3,6 +3,7 @@
 namespace Afosto\Acme\Data;
 
 use Afosto\Acme\Client;
+use Afosto\Acme\Helper;
 
 class Authorization
 {
@@ -93,6 +94,20 @@ class Authorization
         return false;
     }
 
+    /**
+     * @return Challenge|bool
+     */
+    public function getDnsChallenge()
+    {
+        foreach ($this->getChallenges() as $challenge) {
+            if ($challenge->getType() == Client::VALIDATION_DNS) {
+                return $challenge;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Return File object for the given challenge
      * @return File|bool
@@ -105,4 +120,15 @@ class Authorization
         }
         return false;
     }
+
+    /**
+     * @param Challenge $challenge
+     * @return string containing TXT record for DNS challenge
+     */
+    public function getTxtRecord(Challenge $challenge)
+    {
+        $raw=$challenge->getToken() . '.' . $this->digest;
+        $hash=hash('sha256', $raw, true);
+        return Helper::toSafeString($hash);
+    }
 }

src/Helper.php

@@ -140,4 +140,37 @@ class Helper
 
         return $accountDetails;
     }
+
+    /**
+     * Wait until a set of DNS records return specific TXT record values
+     *
+     * @param array mapping domain to desired TXT record value
+     * @param $txtRecord
+     * @param int $maxSeconds to wait
+     * @return bool true if record found, false otherwise
+     */
+    public static function waitForDNS(array $records, $maxSeconds=60)
+    {
+        $waitUntil = time() + $maxSeconds;
+
+        do {
+            //validate all remaining records..
+            foreach($records as $domain=>$txtRecord) {
+                $record=dns_get_record($domain, DNS_TXT);
+                if (isset($record[0]['txt']) && ($record[0]['txt']===$txtRecord)) {
+                    unset($records[$domain]);
+                }
+            }
+
+            //did we find them all?
+            if (empty($records)) {
+                return true;
+            }
+
+            //otherwise still domains to check...have a short sleep
+            sleep(1);
+        } while(time() < $waitUntil);
+
+        return false;
+    }
 }