Use HTTPEngineExtension proxy for git HTTP operations

Summary: Ref T10227. When we perform `git` http operations (fetch, mirror) check if we should use a proxy; if we should, set `http_proxy` or `https_proxy` in the environment to make `git` have `curl` use it.

Test Plan:
  - Configured a proxy extension to run stuff through a local instance of Charles.
  - Ran `repository pull` and `repository mirror`.
  - Saw `git` HTTP requests route through the proxy.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10227

Differential Revision: https://secure.phabricator.com/D16092

src/applications/diffusion/protocol/DiffusionCommandEngine.php

@@ -9,6 +9,7 @@ abstract class DiffusionCommandEngine extends Phobject {
   private $passthru;
   private $connectAsDevice;
   private $sudoAsDaemon;
+  private $uri;
 
   public static function newCommandEngine(PhabricatorRepository $repository) {
     $engines = self::newCommandEngines();
@@ -48,6 +49,16 @@ abstract class DiffusionCommandEngine extends Phobject {
     return $this->repository;
   }
 
+  public function setURI(PhutilURI $uri) {
+    $this->uri = $uri;
+    $this->setProtocol($uri->getProtocol());
+    return $this;
+  }
+
+  public function getURI() {
+    return $this->uri;
+  }
+
   public function setProtocol($protocol) {
     $this->protocol = $protocol;
     return $this;

src/applications/diffusion/protocol/DiffusionGitCommandEngine.php

@@ -30,6 +30,21 @@ final class DiffusionGitCommandEngine
       $env['GIT_SSH'] = $this->getSSHWrapper();
     }
 
+    if ($this->isAnyHTTPProtocol()) {
+      $uri = $this->getURI();
+      if ($uri) {
+        $proxy = PhutilHTTPEngineExtension::buildHTTPProxyURI($uri);
+        if ($proxy) {
+          if ($this->isHTTPSProtocol()) {
+            $env_key = 'https_proxy';
+          } else {
+            $env_key = 'http_proxy';
+          }
+          $env[$env_key] = (string)$proxy;
+        }
+      }
+    }
+
     return $env;
   }
 

src/applications/diffusion/protocol/DiffusionRepositoryClusterEngine.php

@@ -598,7 +598,7 @@ final class DiffusionRepositoryClusterEngine extends Phobject {
       ->setArgv($argv)
       ->setSudoAsDaemon(true)
       ->setCredentialPHID($repository->getCredentialPHID())
-      ->setProtocol($repository->getRemoteProtocol())
+      ->setURI($repository->getRemoteURI())
       ->newFuture();
 
     $future->setCWD($local_path);
@@ -704,7 +704,7 @@ final class DiffusionRepositoryClusterEngine extends Phobject {
       ->setArgv($argv)
       ->setConnectAsDevice(true)
       ->setSudoAsDaemon(true)
-      ->setProtocol($fetch_uri->getProtocol())
+      ->setURI($fetch_uri)
       ->newFuture();
 
     $future->setCWD($local_path);

src/applications/repository/storage/PhabricatorRepository.php

@@ -508,7 +508,7 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
     return DiffusionCommandEngine::newCommandEngine($this)
       ->setArgv($argv)
       ->setCredentialPHID($this->getCredentialPHID())
-      ->setProtocol($this->getRemoteProtocol());
+      ->setURI($this->getRemoteURIObject());
   }
 
 /* -(  Local Command Execution  )-------------------------------------------- */

src/applications/repository/storage/PhabricatorRepositoryURI.php

@@ -587,11 +587,10 @@ final class PhabricatorRepositoryURI
 
   public function newCommandEngine() {
     $repository = $this->getRepository();
-    $protocol = $this->getEffectiveURI()->getProtocol();
 
     return DiffusionCommandEngine::newCommandEngine($repository)
       ->setCredentialPHID($this->getCredentialPHID())
-      ->setProtocol($protocol);
+      ->setURI($this->getEffectiveURI());
   }
 
   public function getURIScore() {