Use relative instead of absolute URLs to play tracks

Previously, the front-end requested webdav URL from the back-end and
the latter returned an absolute URL which was then used for playing.
This caused problems with some untypical proxy configurations, as it is
possible that the protocol (HTTP/HTTPS) seen by the back-end is not the
same as the one used by the front-end. Attempting to play content over
HTTP on a page otherwise using HTTPS is blocked by browsers for security
reasons.

Now the back-end returns only a relative path of the file. It's up to
the front-end to build the full webdav URL out of this. Furthermore,
the URL built by the front-end is also relative since there is no
reason for it to be absolute. The solution is inspired by the one used
in the Files app.

Fixes #650

README.md

@@ -229,7 +229,7 @@ Beside those mentioned resources following additional resources are implemented:
 * `/api/cover/{hash}`
 * `/api/file/{fileId}`
 * `/api/file/{fileId}/info`
-* `/api/file/{fileId}/webdav`
+* `/api/file/{fileId}/path`
 * `/api/file/{fileId}/download`
 * `/api/scan`
 * `/api/scanstate`
@@ -259,7 +259,7 @@ Response:
 
 ### `/api/collection`
 
-Returns all artists with nested albums and each album with nested tracks. The tracks carry file IDs which can be used to obtain WebDAV link for playing with /api/file/{fileId}/webdav.
+Returns all artists with nested albums and each album with nested tracks. Each track carries a file ID which can be used to obtain the file path with `/api/file/{fileId}/path`. The front-end converts the path into playable WebDAV link like this: `OC.linkToRemoteBase('webdav') + path`.
 
 	GET /api/collection
 

appinfo/routes.php

@@ -29,7 +29,8 @@
 	['name' => 'api#prepareCollection',	'url' => '/api/prepare_collection',		'verb' => 'POST'],
 	['name' => 'api#collection',		'url' => '/api/collection',				'verb' => 'GET'],
 	['name' => 'api#trackByFileId',		'url' => '/api/file/{fileId}',			'verb' => 'GET'],
-	['name' => 'api#fileWebDavUrl',		'url' => '/api/file/{fileId}/webdav',	'verb' => 'GET'],
+	['name' => 'api#fileWebDavUrl',		'url' => '/api/file/{fileId}/webdav',	'verb' => 'GET'], // DEPRECATED
+	['name' => 'api#filePath',			'url' => '/api/file/{fileId}/path',		'verb' => 'GET'],
 	['name' => 'api#download',			'url' => '/api/file/{fileId}/download',	'verb' => 'GET'],
 	['name' => 'api#fileInfo',			'url' => '/api/file/{fileId}/info',		'verb' => 'GET'],
 	['name' => 'api#getScanState',		'url' => '/api/scanstate',				'verb' => 'GET'],

controller/apicontroller.php

@@ -310,6 +310,24 @@ public function trackByFileId($fileId) {
 	 * @NoAdminRequired
 	 * @NoCSRFRequired
 	 */
+	public function filePath($fileId) {
+		$nodes = $this->userFolder->getById($fileId);
+		if (\count($nodes) == 0) {
+			return new ErrorResponse(Http::STATUS_NOT_FOUND);
+		} else {
+			$node = $nodes[0];
+			$path = $this->userFolder->getRelativePath($node->getPath());
+			// URL encode each part of the file path
+			$path = \join('/', \array_map('rawurlencode', \explode('/', $path)));
+			return new JSONResponse(['path' => $path]);
+		}
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @NoCSRFRequired
+	 * DEPRECATED
+	 */
 	public function fileWebDavUrl($fileId) {
 		$nodes = $this->userFolder->getById($fileId);
 		if (\count($nodes) == 0) {

js/app/controllers/playercontroller.js

@@ -106,11 +106,12 @@ function ($scope, $rootScope, playlistService, libraryService,
 
 			// get webDAV URL to the track and start playing it
 			var mimeAndId = $scope.getPlayableFileId(track);
-			Restangular.one('file', mimeAndId.id).one('webdav').get().then(function(result) {
+			Restangular.one('file', mimeAndId.id).one('path').get().then(function(result) {
 				// It is possible that the active track has already changed again by the time we get
 				// the URI. Do not start playback in that case.
 				if (track == $scope.currentTrack) {
-					var url = result.url + '?requesttoken=' + encodeURIComponent(OC.requestToken);
+					var url = OC.linkToRemoteBase('webdav') + result.path +
+							'?requesttoken=' + encodeURIComponent(OC.requestToken);
 					$scope.player.fromURL(url, mimeAndId.mime);
 					$scope.seekCursorType = $scope.player.seekingSupported() ? 'pointer' : 'default';
 

js/public/app.js

@@ -681,11 +681,12 @@ function ($scope, $rootScope, playlistService, libraryService,
 
 			// get webDAV URL to the track and start playing it
 			var mimeAndId = $scope.getPlayableFileId(track);
-			Restangular.one('file', mimeAndId.id).one('webdav').get().then(function(result) {
+			Restangular.one('file', mimeAndId.id).one('path').get().then(function(result) {
 				// It is possible that the active track has already changed again by the time we get
 				// the URI. Do not start playback in that case.
 				if (track == $scope.currentTrack) {
-					var url = result.url + '?requesttoken=' + encodeURIComponent(OC.requestToken);
+					var url = OC.linkToRemoteBase('webdav') + result.path +
+							'?requesttoken=' + encodeURIComponent(OC.requestToken);
 					$scope.player.fromURL(url, mimeAndId.mime);
 					$scope.seekCursorType = $scope.player.seekingSupported() ? 'pointer' : 'default';