From 720fb664de02ab4d569f8675f8322d7323a3be4e Mon Sep 17 00:00:00 2001
From: Sarah Jamie Lewis <sarah@openprivacy.ca>
Date: Fri, 19 Aug 2022 09:27:19 -0700
Subject: [PATCH] Add additional checks around file download directories

---
 .../filesharing/filesharing_functionality.go  | 19 ++++++++++++++++++-
 .../file_sharing_integration_test.go          | 18 +++++++++++++++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/functionality/filesharing/filesharing_functionality.go b/functionality/filesharing/filesharing_functionality.go
index d69f9ab..a6b778e 100644
--- a/functionality/filesharing/filesharing_functionality.go
+++ b/functionality/filesharing/filesharing_functionality.go
@@ -74,7 +74,22 @@ func (om *OverlayMessage) ShouldAutoDL() bool {
 
 // DownloadFile given a profile, a conversation handle and a file sharing key, start off a download process
 // to downloadFilePath
-func (f *Functionality) DownloadFile(profile peer.CwtchPeer, conversationID int, downloadFilePath string, manifestFilePath string, key string, limit uint64) {
+func (f *Functionality) DownloadFile(profile peer.CwtchPeer, conversationID int, downloadFilePath string, manifestFilePath string, key string, limit uint64) error {
+
+	// Don't download files if the download or manifest path is not set
+	if downloadFilePath == "" || manifestFilePath == "" {
+		return errors.New("download path or manifest path is empty")
+	}
+
+	// Don't download files if the download file directory does not exist
+	if _, err := os.Stat(path.Dir(downloadFilePath)); os.IsNotExist(err) {
+		return errors.New("download directory does not exist")
+	}
+
+	// Don't download files if the manifest file directory does not exist
+	if _, err := os.Stat(path.Dir(manifestFilePath)); os.IsNotExist(err) {
+		return errors.New("manifest directory does not exist")
+	}
 
 	// Store local.filesharing.filekey.manifest as the location of the manifest
 	profile.SetScopedZonedAttribute(attr.LocalScope, attr.FilesharingZone, fmt.Sprintf("%s.manifest", key), manifestFilePath)
@@ -87,6 +102,8 @@ func (f *Functionality) DownloadFile(profile peer.CwtchPeer, conversationID int,
 
 	// Get the value of conversation.filesharing.filekey.manifest.size from `handle`
 	profile.SendScopedZonedGetValToContact(conversationID, attr.ConversationScope, attr.FilesharingZone, fmt.Sprintf("%s.manifest.size", key))
+
+	return nil
 }
 
 // RestartFileShare takes in an existing filekey and, assuming the manifest exists, restarts sharing of the manifest
diff --git a/testing/filesharing/file_sharing_integration_test.go b/testing/filesharing/file_sharing_integration_test.go
index 8770d5c..e0570cc 100644
--- a/testing/filesharing/file_sharing_integration_test.go
+++ b/testing/filesharing/file_sharing_integration_test.go
@@ -192,7 +192,23 @@ func testBobDownloadFile(t *testing.T, bob peer.CwtchPeer, filesharingFunctional
 		err := json.Unmarshal([]byte(messageWrapper.Data), &fileMessageOverlay)
 
 		if err == nil {
-			filesharingFunctionality.DownloadFile(bob, 1, "cwtch.out.png", "cwtch.out.png.manifest", fmt.Sprintf("%s.%s", fileMessageOverlay.Hash, fileMessageOverlay.Nonce), constants.ImagePreviewMaxSizeInBytes)
+
+			// try downloading with invalid download dir
+			err = filesharingFunctionality.DownloadFile(bob, 1, "/do/not/download/this/file/cwtch.out.png", "./cwtch.out.png.manifest", fmt.Sprintf("%s.%s", fileMessageOverlay.Hash, fileMessageOverlay.Nonce), constants.ImagePreviewMaxSizeInBytes)
+			if err == nil {
+				t.Fatalf("should not download file with invalid download dir")
+			}
+
+			// try downloading with invalid manifest dir
+			err = filesharingFunctionality.DownloadFile(bob, 1, "./cwtch.out.png", "/do/not/download/this/file/cwtch.out.png.manifest", fmt.Sprintf("%s.%s", fileMessageOverlay.Hash, fileMessageOverlay.Nonce), constants.ImagePreviewMaxSizeInBytes)
+			if err == nil {
+				t.Fatalf("should not download file with invalid manifest dir")
+			}
+
+			err = filesharingFunctionality.DownloadFile(bob, 1, "./cwtch.out.png", "./cwtch.out.png.manifest", fmt.Sprintf("%s.%s", fileMessageOverlay.Hash, fileMessageOverlay.Nonce), constants.ImagePreviewMaxSizeInBytes)
+			if err != nil {
+				t.Fatalf("could not download file: %v", err)
+			}
 		}
 	}