Better curl error messages for ^6.1 (Spomky-Labs#319)

Better curl error messages for ^6.1
Proposal for issue #316

Author: Spomky

src/Object/DownloadedJWKSet.php

@@ -119,7 +119,10 @@ protected function getContent()
     }
 
     /**
-     * @throws \InvalidArgumentException
+     * @throws \InvalidArgumentException Has CURL error message and the CURL error
+     *                                   number as exception code.
+     *                                   Throws exception with error number 0
+     *                                   if the error is not related to CURL.
      *
      * @return string
      */
@@ -137,9 +140,25 @@ private function downloadContent()
         $ch = curl_init();
         curl_setopt_array($ch, $params);
         $content = curl_exec($ch);
-        curl_close($ch);
 
-        Assertion::false(false === $content, 'Unable to get content.');
+        try {
+            Assertion::false(false === $content, 'Failed to load JWK contents: ');
+        } catch (\Assert\AssertionFailedException $e) {
+            $curlError = curl_error($ch);
+            $curlErrorNumber = curl_errno($ch);
+
+            throw new \InvalidArgumentException(
+                $e->getMessage().$curlError,
+                $curlErrorNumber
+            );
+        } catch (\Exception $e) {
+            throw new \InvalidArgumentException(
+                'Failed to load JWK contents: '.$e->getMessage(),
+                0
+            );
+        } finally {
+            curl_close($ch);
+        }
 
         return $content;
     }

src/Object/JKUJWKSet.php

@@ -24,8 +24,8 @@ final class JKUJWKSet extends DownloadedJWKSet
     public function getKeys()
     {
         $content = json_decode($this->getContent(), true);
-        Assertion::isArray($content, 'Invalid content.');
-        Assertion::keyExists($content, 'keys', 'Invalid content.');
+        Assertion::isArray($content, 'Invalid JWK content.');
+        Assertion::keyExists($content, 'keys', 'Invalid JWKSet content.');
 
         return (new JWKSet($content))->getKeys();
     }

src/Object/X5UJWKSet.php

@@ -25,11 +25,11 @@ final class X5UJWKSet extends DownloadedJWKSet
     public function getKeys()
     {
         $content = json_decode($this->getContent(), true);
-        Assertion::isArray($content, 'Invalid content.');
+        Assertion::isArray($content, 'Invalid JWK content.');
         $jwkset = new JWKSet();
         foreach ($content as $kid => $cert) {
             $jwk = KeyConverter::loadKeyFromCertificate($cert);
-            Assertion::notEmpty($jwk, 'Invalid content.');
+            Assertion::notEmpty($jwk, 'Invalid JWKSet content.');
             if (is_string($kid)) {
                 $jwk['kid'] = $kid;
             }