Accept and route VCS HTTP requests

Summary:
Mostly ripped from D7391, with some changes:

  - Serve repositories at `/diffusion/X/`, with no special `/git/` or `/serve/` URI component.
    - This requires a little bit of magic, but I got the magic working for Git, Mercurial and SVN, and it seems reasonable.
    - I think having one URI for everything will make it easier for users to understand.
    - One downside is that git will clone into `X` by default, but I think that's not a big deal, and we can work around that in the future easily enough.
  - Accept HTTP requests for Git, SVN and Mercurial repositories.
  - Auth logic is a little different in order to be more consistent with how other things work.
  - Instead of AphrontBasicAuthResponse, added "VCSResponse". Mercurial can print strings we send it on the CLI if we're careful, so support that. I did a fair amount of digging and didn't have any luck with git or svn.
  - Commands we don't know about are assumed to require "Push" capability by default.

No actual VCS data going over the wire yet.

Test Plan:
Ran a bunch of stuff like this:

  $ hg clone http://local.aphront.com:8080/diffusion/P/
  abort: HTTP Error 403: This repository is not available over HTTP.

...and got pretty reasonable-seeming errors in all cases. All this can do is produce errors for now.

Reviewers: hach-que, btrahan

Reviewed By: hach-que

CC: aran

Maniphest Tasks: T2230

Differential Revision: https://secure.phabricator.com/D7417

src/__phutil_library_map__.php

@@ -509,6 +509,7 @@ phutil_register_library_map(array(
     'DiffusionRenameHistoryQuery' => 'applications/diffusion/query/DiffusionRenameHistoryQuery.php',
     'DiffusionRepositoryController' => 'applications/diffusion/controller/DiffusionRepositoryController.php',
     'DiffusionRepositoryCreateController' => 'applications/diffusion/controller/DiffusionRepositoryCreateController.php',
+    'DiffusionRepositoryDefaultController' => 'applications/diffusion/controller/DiffusionRepositoryDefaultController.php',
     'DiffusionRepositoryEditActionsController' => 'applications/diffusion/controller/DiffusionRepositoryEditActionsController.php',
     'DiffusionRepositoryEditActivateController' => 'applications/diffusion/controller/DiffusionRepositoryEditActivateController.php',
     'DiffusionRepositoryEditBasicController' => 'applications/diffusion/controller/DiffusionRepositoryEditBasicController.php',
@@ -1867,6 +1868,7 @@ phutil_register_library_map(array(
     'PhabricatorUserTestCase' => 'applications/people/storage/__tests__/PhabricatorUserTestCase.php',
     'PhabricatorUserTitleField' => 'applications/people/customfield/PhabricatorUserTitleField.php',
     'PhabricatorUserTransaction' => 'applications/people/storage/PhabricatorUserTransaction.php',
+    'PhabricatorVCSResponse' => 'applications/repository/response/PhabricatorVCSResponse.php',
     'PhabricatorWorker' => 'infrastructure/daemon/workers/PhabricatorWorker.php',
     'PhabricatorWorkerActiveTask' => 'infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php',
     'PhabricatorWorkerArchiveTask' => 'infrastructure/daemon/workers/storage/PhabricatorWorkerArchiveTask.php',
@@ -2691,6 +2693,7 @@ phutil_register_library_map(array(
     'DiffusionRemarkupRule' => 'PhabricatorRemarkupRuleObject',
     'DiffusionRepositoryController' => 'DiffusionController',
     'DiffusionRepositoryCreateController' => 'DiffusionRepositoryEditController',
+    'DiffusionRepositoryDefaultController' => 'DiffusionController',
     'DiffusionRepositoryEditActionsController' => 'DiffusionRepositoryEditController',
     'DiffusionRepositoryEditActivateController' => 'DiffusionRepositoryEditController',
     'DiffusionRepositoryEditBasicController' => 'DiffusionRepositoryEditController',
@@ -4202,6 +4205,7 @@ phutil_register_library_map(array(
     'PhabricatorUserTestCase' => 'PhabricatorTestCase',
     'PhabricatorUserTitleField' => 'PhabricatorUserCustomField',
     'PhabricatorUserTransaction' => 'PhabricatorApplicationTransaction',
+    'PhabricatorVCSResponse' => 'AphrontResponse',
     'PhabricatorWorkerActiveTask' => 'PhabricatorWorkerTask',
     'PhabricatorWorkerArchiveTask' => 'PhabricatorWorkerTask',
     'PhabricatorWorkerDAO' => 'PhabricatorLiskDAO',

src/aphront/response/AphrontResponse.php

@@ -49,6 +49,10 @@ abstract class AphrontResponse {
     return $this->responseCode;
   }
 
+  public function getHTTPResponseMessage() {
+    return '';
+  }
+
   public function setFrameable($frameable) {
     $this->frameable = $frameable;
     return $this;

src/aphront/sink/AphrontHTTPSink.php

@@ -25,13 +25,13 @@ abstract class AphrontHTTPSink {
    * @param int Numeric HTTP status code.
    * @return void
    */
-  final public function writeHTTPStatus($code) {
+  final public function writeHTTPStatus($code, $message = '') {
     if (!preg_match('/^\d{3}$/', $code)) {
       throw new Exception("Malformed HTTP status code '{$code}'!");
     }
 
     $code = (int)$code;
-    $this->emitHTTPStatus($code);
+    $this->emitHTTPStatus($code, $message);
   }
 
 
@@ -103,7 +103,9 @@ abstract class AphrontHTTPSink {
       $response->getHeaders(),
       $response->getCacheHeaders());
 
-    $this->writeHTTPStatus($response->getHTTPResponseCode());
+    $this->writeHTTPStatus(
+      $response->getHTTPResponseCode(),
+      $response->getHTTPResponseMessage());
     $this->writeHeaders($all_headers);
     $this->writeData($response_string);
   }
@@ -112,7 +114,7 @@ abstract class AphrontHTTPSink {
 /* -(  Emitting the Response  )---------------------------------------------- */
 
 
-  abstract protected function emitHTTPStatus($code);
+  abstract protected function emitHTTPStatus($code, $message = '');
   abstract protected function emitHeader($name, $value);
   abstract protected function emitData($data);
 }

src/aphront/sink/AphrontIsolatedHTTPSink.php

@@ -11,7 +11,7 @@ final class AphrontIsolatedHTTPSink extends AphrontHTTPSink {
   private $headers;
   private $data;
 
-  protected function emitHTTPStatus($code) {
+  protected function emitHTTPStatus($code, $message = '') {
     $this->status = $code;
   }
 

src/aphront/sink/AphrontPHPHTTPSink.php

@@ -7,9 +7,13 @@
  */
 final class AphrontPHPHTTPSink extends AphrontHTTPSink {
 
-  protected function emitHTTPStatus($code) {
+  protected function emitHTTPStatus($code, $message = '') {
     if ($code != 200) {
-      header("HTTP/1.0 {$code}");
+      $header = "HTTP/1.0 {$code}";
+      if (strlen($message)) {
+        $header .= " {$message}";
+      }
+      header($header);
     }
   }
 

src/applications/base/controller/PhabricatorController.php

@@ -24,7 +24,7 @@ abstract class PhabricatorController extends AphrontController {
     return PhabricatorUserEmail::isEmailVerificationRequired();
   }
 
-  final public function willBeginExecution() {
+  public function willBeginExecution() {
 
     $request = $this->getRequest();
     if ($request->getUser()) {

src/applications/diffusion/application/PhabricatorApplicationDiffusion.php

@@ -79,6 +79,13 @@ final class PhabricatorApplicationDiffusion extends PhabricatorApplication {
             '(?P<serve>serve)/' => 'DiffusionRepositoryEditHostingController',
           ),
         ),
+
+        // NOTE: This must come after the rule above; it just gives us a
+        // catch-all for serving repositories over HTTP. We must accept
+        // requests without the trailing "/" because SVN commands don't
+        // necessarily include it.
+        '(?P<callsign>[A-Z]+)(/|$).*' => 'DiffusionRepositoryDefaultController',
+
         'inline/' => array(
           'edit/(?P<phid>[^/]+)/'    => 'DiffusionInlineCommentController',
           'preview/(?P<phid>[^/]+)/' =>

src/applications/diffusion/controller/DiffusionController.php

@@ -4,6 +4,168 @@ abstract class DiffusionController extends PhabricatorController {
 
   protected $diffusionRequest;
 
+  public function willBeginExecution() {
+    $request = $this->getRequest();
+    $uri = $request->getRequestURI();
+
+    // Check if this is a VCS request, e.g. from "git clone", "hg clone", or
+    // "svn checkout". If it is, we jump off into repository serving code to
+    // process the request.
+
+    $regex = '@^/diffusion/(?P<callsign>[A-Z]+)(/|$)@';
+    $matches = null;
+    if (preg_match($regex, (string)$uri, $matches)) {
+      $vcs = null;
+
+      if ($request->getExists('__vcs__')) {
+        // This is magic to make it easier for us to debug stuff by telling
+        // users to run:
+        //
+        //   curl http://example.phabricator.com/diffusion/X/?__vcs__=1
+        //
+        // ...to get a human-readable error.
+        $vcs = $request->getExists('__vcs__');
+      } else if ($request->getExists('service')) {
+        // Git also gives us a User-Agent like "git/1.8.2.3".
+        $vcs = PhabricatorRepositoryType::REPOSITORY_TYPE_GIT;
+      } else if ($request->getExists('cmd')) {
+        // Mercurial also sends an Accept header like
+        // "application/mercurial-0.1", and a User-Agent like
+        // "mercurial/proto-1.0".
+        $vcs = PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL;
+      } else {
+        // Subversion also sends an initial OPTIONS request (vs GET/POST), and
+        // has a User-Agent like "SVN/1.8.3 (x86_64-apple-darwin11.4.2)
+        // serf/1.3.2".
+        $dav = $request->getHTTPHeader('DAV');
+        $dav = new PhutilURI($dav);
+        if ($dav->getDomain() === 'subversion.tigris.org') {
+          $vcs = PhabricatorRepositoryType::REPOSITORY_TYPE_SVN;
+        }
+      }
+
+      if ($vcs) {
+        return $this->processVCSRequest($matches['callsign']);
+      }
+    }
+
+    parent::willBeginExecution();
+  }
+
+  private function processVCSRequest($callsign) {
+
+    // TODO: Authenticate user.
+
+    $viewer = new PhabricatorUser();
+
+    $allow_public = PhabricatorEnv::getEnvConfig('policy.allow-public');
+    if (!$allow_public) {
+      if (!$viewer->isLoggedIn()) {
+        return new PhabricatorVCSResponse(
+          403,
+          pht('You must log in to access repositories.'));
+      }
+    }
+
+    try {
+      $repository = id(new PhabricatorRepositoryQuery())
+        ->setViewer($viewer)
+        ->withCallsigns(array($callsign))
+        ->executeOne();
+      if (!$repository) {
+        return new PhabricatorVCSResponse(
+          404,
+          pht('No such repository exists.'));
+      }
+    } catch (PhabricatorPolicyException $ex) {
+      if ($viewer->isLoggedIn()) {
+        return new PhabricatorVCSResponse(
+          403,
+          pht('You do not have permission to access this repository.'));
+      } else {
+        return new PhabricatorVCSResponse(
+          401,
+          pht('You must log in to access this repository.'));
+      }
+    }
+
+    $is_push = !$this->isReadOnlyRequest($repository);
+
+    switch ($repository->getServeOverHTTP()) {
+      case PhabricatorRepository::SERVE_READONLY:
+        if ($is_push) {
+          return new PhabricatorVCSResponse(
+            403,
+            pht('This repository is read-only over HTTP.'));
+        }
+        break;
+      case PhabricatorRepository::SERVE_READWRITE:
+        if ($is_push) {
+          $can_push = PhabricatorPolicyFilter::hasCapability(
+            $viewer,
+            $repository,
+            DiffusionCapabilityPush::CAPABILITY);
+          if (!$can_push) {
+            if ($viewer->isLoggedIn()) {
+              return new PhabricatorVCSResponse(
+                403,
+                pht('You do not have permission to push to this repository.'));
+            } else {
+              return new PhabricatorVCSResponse(
+                401,
+                pht('You must log in to push to this repository.'));
+            }
+          }
+        }
+        break;
+      case PhabricatorRepository::SERVE_OFF:
+      default:
+        return new PhabricatorVCSResponse(
+          403,
+          pht('This repository is not available over HTTP.'));
+    }
+
+    return new PhabricatorVCSResponse(
+      999,
+      pht('TODO: Implement meaningful responses.'));
+  }
+
+  private function isReadOnlyRequest(
+    PhabricatorRepository $repository) {
+    $request = $this->getRequest();
+
+    // TODO: This implementation is safe by default, but very incomplete.
+
+    switch ($repository->getVersionControlSystem()) {
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
+        $service = $request->getStr('service');
+        // NOTE: Service names are the reverse of what you might expect, as they
+        // are from the point of view of the server. The main read service is
+        // "git-upload-pack", and the main write service is "git-receive-pack".
+        switch ($service) {
+          case 'git-upload-pack':
+            return true;
+          case 'git-receive-pack':
+          default:
+            return false;
+        }
+        break;
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL:
+        $cmd = $request->getStr('cmd');
+        switch ($cmd) {
+          case 'capabilities':
+            return true;
+          default:
+            return false;
+        }
+        break;
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_SUBVERSION:
+        break;
+    }
+
+    return false;
+  }
+
   public function willProcessRequest(array $data) {
     if (isset($data['callsign'])) {
       $drequest = DiffusionRequest::newFromAphrontRequestDictionary(

src/applications/diffusion/controller/DiffusionRepositoryDefaultController.php

@@ -0,0 +1,11 @@
+<?php
+
+final class DiffusionRepositoryDefaultController extends DiffusionController {
+
+  public function processRequest() {
+    // NOTE: This controller is just here to make sure we call
+    // willBeginExecution() on any /diffusion/X/ URI, so we can intercept
+    // `git`, `hg` and `svn` HTTP protocol requests.
+    return new Aphront404Response();
+  }
+}

src/applications/repository/response/PhabricatorVCSResponse.php

@@ -0,0 +1,62 @@
+<?php
+
+/**
+ * In Git, there appears to be no way to send a message which will be output
+ * by `git clone http://...`, although the response code is visible.
+ *
+ * In Mercurial, the HTTP status response message is printed to the console, so
+ * we send human-readable text there.
+ *
+ * In Subversion, we can get it to print a custom message if we send an
+ * invalid/unknown response code, although the output is ugly and difficult
+ * to read. For known codes like 404, it prints a canned message.
+ *
+ * All VCS binaries ignore the response body; we include it only for
+ * completeness.
+ */
+final class PhabricatorVCSResponse extends AphrontResponse {
+
+  private $code;
+  private $message;
+
+  public function __construct($code, $message) {
+    $this->code = $code;
+
+    $message = head(phutil_split_lines($message));
+    $this->message = $message;
+  }
+
+  public function getMessage() {
+    return $this->message;
+  }
+
+  public function buildResponseString() {
+    return $this->code.' '.$this->message;
+  }
+
+  public function getHeaders() {
+    $headers = array();
+
+    if ($this->getHTTPResponseCode() == 401) {
+      $headers[] = array(
+        'WWW-Authenticate',
+        'Basic realm="Phabricator Repositories"',
+      );
+    }
+
+    return $headers;
+  }
+
+  public function getCacheHeaders() {
+    return array();
+  }
+
+  public function getHTTPResponseCode() {
+    return $this->code;
+  }
+
+  public function getHTTPResponseMessage() {
+    return $this->message;
+  }
+
+}