Hopefully put the keyserver issues to a rest.

Fingers crossed.
Wow, this is a mess. There is a keyserver software out there thinks it's a good idea to wrap the output in some blinky HTML, even if providing the mr (machine readable!) option. Instead it has some arbitrary criteria to decide whether to add this wrapper or not. The only criteria we have any influence on is a missing User-Agent header which is supposed to indicate an API client instead of a browser. All of this you can only find out if you have access to the server software. At least it's open source.
Next comes the various HTTP backends that you need to convince to not send a User-Agent header. CURL allows to set it to NULL, PECL_HTTP, which uses CURL, not. Instead you have to use an empty string, which again you only can find out when ... yada, yada. I didn't even bother to test the fopen backend.

framework/Crypt/lib/Horde/Crypt/Pgp/Keyserver.php

@@ -61,9 +61,18 @@ class Horde_Crypt_Pgp_Keyserver
     public function __construct($pgp, array $params = array())
     {
         $this->_pgp = $pgp;
-        $this->_http = (isset($params['http']) && ($params['http'] instanceof Horde_Http_Client))
-            ? $params['http']
-            : new Horde_Http_Client();
+        if (isset($params['http'])) {
+            if (!($params['http'] instanceof Horde_Http_Client)) {
+                throw new InvalidArgumentException('Argument is not a Horde_Http_Client instance');
+            }
+            $this->_http = $params['http'];
+        } else {
+            $this->_http = new Horde_Http_Client();
+        }
+        /* There is a broken key server software that returns HTML content
+         * instead of plain text on arbitrary criteria. A User-Agent header is
+         * one of those. */
+        $this->_http->{'request.userAgent'} = '';
         $this->_keyserver = isset($params['keyserver'])
             ? $params['keyserver']
             : 'http://pool.sks-keyservers.net';
@@ -98,7 +107,7 @@ public function get($keyid)
             return substr($start, 0, $length);
         }
 
-        throw new Horde_Crypt_Exception(Horde_Crypt_Translation::t("Could not obtain public key from the keyserver.") . ' Response: ' . $output);
+        throw new Horde_Crypt_Exception(Horde_Crypt_Translation::t("Could not obtain public key from the keyserver."));
     }
 
     /**
@@ -174,7 +183,7 @@ public function getKeyId($address)
 
         if (!$output) {
             throw new Horde_Crypt_Exception(
-                Horde_Crypt_Translation::t("Could not obtain public key from the keyserver.") . ' Response: ' . var_export($response, true)
+                Horde_Crypt_Translation::t("Could not obtain public key from the keyserver.")
             );
         }
 

framework/Crypt/test/Horde/Crypt/PgpKeyserverTest.php

@@ -12,26 +12,26 @@
 class Horde_Crypt_PgpKeyserverTest extends Horde_Test_Case
 {
     protected $_ks;
+    protected $_gnupg;
 
     protected function setUp()
     {
         $c = self::getConfig('CRYPTPGP_TEST_CONFIG', __DIR__);
-        $gnupg = isset($c['gnupg'])
+        $this->_gnupg = isset($c['gnupg'])
             ? $c['gnupg']
             : '/usr/bin/gpg';
 
-        if (!is_executable($gnupg)) {
+        if (!is_executable($this->_gnupg)) {
             $this->markTestSkipped(sprintf(
                 'GPG binary not found at %s.',
-                $gnupg
+                $this->_gnupg
             ));
         }
 
         $this->_ks = new Horde_Crypt_Pgp_Keyserver(
             Horde_Crypt::factory('Pgp', array(
-                'program' => $gnupg
-            )),
-            array('keyserver' => 'http://ha.pool.sks-keyservers.net')
+                'program' => $this->_gnupg
+            ))
         );
     }
 
@@ -64,4 +64,25 @@ public function testKeyserverRetrieveByEmail()
         }
     }
 
+    public function testBrokenKeyserver()
+    {
+        $ks = new Horde_Crypt_Pgp_Keyserver(
+            Horde_Crypt::factory('Pgp', array(
+                'program' => $this->_gnupg
+            )),
+            array('keyserver' => 'http://pgp.key-server.io')
+        );
+        try {
+            $this->assertEquals(
+                '4DE5B969',
+                $ks->getKeyID('jan@horde.org')
+            );
+        } catch (Horde_Crypt_Exception $e) {
+            if (strpos($e->getMessage(), 'Operation timed out') === 0) {
+                $this->markTestSkipped($e->getMessage());
+            } else {
+                throw $e;
+            }
+        }
+    }
 }

framework/Pgp/lib/Horde/Pgp/Keyserver.php

@@ -53,9 +53,17 @@ class Horde_Pgp_Keyserver
      */
     public function __construct(array $params = array())
     {
-        $this->_http = (isset($params['http']) && ($params['http'] instanceof Horde_Http_Client))
-            ? $params['http']
-            : new Horde_Http_Client();
+        if (isset($params['http'])) {
+            if (!($params['http'] instanceof Horde_Http_Client)) {
+                throw new InvalidArgumentException('Argument is not a Horde_Http_Client instance');
+            }
+            $this->_http = $params['http'];
+        } else {
+            $this->_http = new Horde_Http_Client();
+        }
+        /* There is a broken key server software that returns HTML content
+         * instead of plain text on arbitrary criteria. A User-Agent header is
+         * one of those. */
         $this->_http->{'request.userAgent'} = '';
         $this->_keyserver = isset($params['keyserver'])
             ? $params['keyserver']

framework/Pgp/test/Horde/Pgp/KeyserverTest.php

@@ -29,9 +29,7 @@ class Horde_Pgp_KeyserverTest extends Horde_Test_Case
 
     protected function setUp()
     {
-        $this->_ks = new Horde_Pgp_Keyserver(array(
-            'keyserver' => 'http://ha.pool.sks-keyservers.net:11371'
-        ));
+        $this->_ks = new Horde_Pgp_Keyserver();
     }
 
     /**
@@ -73,6 +71,25 @@ public function testKeyserverRetrieveByEmail($email, $id)
         }
     }
 
+    /**
+     * @dataProvider keyserverRetrieveByEmailProvider
+     */
+    public function testBrokenKeyserver($email, $id)
+    {
+        $ks = new Horde_Pgp_Keyserver(array(
+            'keyserver' => 'http://pgp.key-server.io:11371'
+        ));
+        try {
+            $this->_checkKey($ks->getKeyByEmail($email), $id);
+        } catch (Horde_Pgp_Exception $e) {
+            if ($e->getPrevious() instanceof Horde_Http_Exception) {
+                $this->markTestSkipped($e->getPrevious()->getMessage());
+            } else {
+                throw $e;
+            }
+        }
+    }
+
     public function keyserverRetrieveByEmailProvider()
     {
         return array(