401 Unauthorized - Google Drive API

Question

I'm working with the Google APIs for the first time and I'm having problems trying to download files with the File object "downloadUrl" property. I'm currently using the "Service Account" option with the associated service account email and P12 certificate.

However, the URL returned "https://doc-08-68-docs.googleusercontent.com/docs/securesc/bteg36c1tifegg79l2ov17og25612tet/gk7kn52ahe4d0to7d6hte9f0f2hv47e4/1434132000000/11750183130219432819/11750183130219432819/0BziIKv2_NWCxc3RhcnRlcl9maWxl?e=download&gd=true" returns a 401 - Unauthorized response.

Imports System.Collections.Generic
Imports System.Security.Cryptography.X509Certificates
Imports System.IO

Imports Google.Apis.Drive.v2
Imports Google.Apis.Drive.v2.Data
Imports Google.Apis.Services
Imports Google.Apis.Auth.OAuth2

Namespace Videos

    Partial Class List
        Inherits System.Web.UI.UserControl

        Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

            Const serviceAccountEmail As String = "@developer.gserviceaccount.com"

            Dim certificate = New X509Certificate2(
                Server.MapPath("~/bin/key.p12"),
                "notasecret",
                X509KeyStorageFlags.MachineKeySet Or X509KeyStorageFlags.PersistKeySet Or X509KeyStorageFlags.Exportable
            )

            Dim credential = New ServiceAccountCredential(
               New ServiceAccountCredential.Initializer(serviceAccountEmail) With {
                   .Scopes = New String() {DriveService.Scope.Drive}
               }.FromCertificate(certificate)
            )

            Dim service = New DriveService(
                New BaseClientService.Initializer() With {
                    .HttpClientInitializer = credential,
                    .ApplicationName = "LexVid-VideoEncode/1.0"
                }
            )

            UxFiles.DataSource = RetrieveAllFiles(service)
            UxFiles.DataBind()

        End Sub

        Public Shared Function RetrieveAllFiles(service As DriveService) As List(Of Data.File)

            Dim result = New List(Of Data.File)()
            Dim request As FilesResource.ListRequest = service.Files.List()

            Do

                Try

                    Dim files As FileList = request.Execute()

                    result.AddRange(files.Items)
                    request.PageToken = files.NextPageToken

                Catch e As Exception
                    request.PageToken = Nothing
                End Try

            Loop While (Not String.IsNullOrEmpty(request.PageToken))

            Return result

        End Function


        Public Shared Function DownloadFile(ByVal service As DriveService, ByVal file As Data.File) As System.IO.Stream

            If (Not String.IsNullOrEmpty(file.DownloadUrl)) Then

                Try

                    Dim x = service.HttpClient.GetByteArrayAsync(file.DownloadUrl)
                    Dim result As [Byte]() = x.Result

                    Return New MemoryStream(result)

                Catch e As Exception
                    Return Nothing
                End Try

            Else
                Return Nothing
            End If

        End Function

        Protected Sub UxFiles_ItemDataBound(ByVal sender As Object, ByVal e As ListViewItemEventArgs) Handles UxFiles.ItemDataBound

            Dim dataItem = CType(e.Item.DataItem, Data.File)

            Dim file = CType(e.Item.FindControl("UxFile"), HyperLink)
            file.NavigateUrl = dataItem.DownloadUrl
            file.Text = dataItem.Title

        End Sub

    End Class

End Namespace

Answer 1

I got this resolved through some trial and error. Although I'm building the links manually now, so the request token isn't even necessary anymore. However, I'm posting here in case anyone else is looking to resolve a similar issue.

Imports System.Collections.Generic
Imports System.Security.Cryptography.X509Certificates
Imports System.IO
Imports System.Threading

Imports Google.Apis.Drive.v2
Imports Google.Apis.Drive.v2.Data
Imports Google.Apis.Services
Imports Google.Apis.Auth.OAuth2

Namespace Videos

    Partial Class List
        Inherits System.Web.UI.UserControl

        Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

            Const serviceAccountEmail As String = "@developer.gserviceaccount.com"

            Dim certificate = New X509Certificate2(
                Server.MapPath("~/bin/key.p12"),
                "notasecret",
                X509KeyStorageFlags.MachineKeySet Or X509KeyStorageFlags.PersistKeySet Or X509KeyStorageFlags.Exportable
            )

            Dim credential As ServiceAccountCredential = New ServiceAccountCredential(
            New ServiceAccountCredential.Initializer(serviceAccountEmail) With {
                .Scopes = New String() {DriveService.Scope.Drive}
            }.FromCertificate(certificate)
            )

            If (credential.RequestAccessTokenAsync(CancellationToken.None).Result) Then

                Dim service = New DriveService(
                    New BaseClientService.Initializer() With {
                        .HttpClientInitializer = credential,
                        .ApplicationName = "LexVid-VideoEncode/1.0"
                    }
                )

                UxFiles.DataSource = RetrieveAllFiles(service)
                UxFiles.DataBind()

            End If

        End Sub

        Public Shared Function RetrieveAllFiles(service As DriveService) As List(Of Data.File)

            Dim result = New List(Of Data.File)()
            Dim request As FilesResource.ListRequest = service.Files.List()

            Do

                Try

                    Const folderID As String = "0B5RLR6VRZsR4fkE5QjVFajg2dzZOMXZLYkNZUVdGbEtNODF0XzVBVGdjMW9ISDF5OE9kM0E"
                    request.Q = String.Format("'{0}' in parents and trashed=false", folderID)
                    Dim files As FileList = request.Execute()

                    result.AddRange(files.Items)
                    request.PageToken = files.NextPageToken

                Catch e As Exception
                    request.PageToken = Nothing
                End Try

            Loop While (Not String.IsNullOrEmpty(request.PageToken))

            Return result

        End Function

        Protected Sub UxFiles_ItemDataBound(ByVal sender As Object, ByVal e As ListViewItemEventArgs) Handles UxFiles.ItemDataBound

            Dim dataItem = CType(e.Item.DataItem, Data.File)

            Const folderID As String = "0B5RLR6VRZsR4fkE5QjVFajg2dzZOMXZLYkNZUVdGbEtNODF0XzVBVGdjMW9ISDF5OE9kM0E"

            Dim file = CType(e.Item.FindControl("UxFile"), HyperLink)
            file.NavigateUrl = String.Format("http://googledrive.com/host/{0}/{1}", folderID, dataItem.Title)
            ' Large files prompt for virus scan; no bypass available.
            ' file.NavigateUrl = String.Format("https://drive.google.com/uc?export=download&id={0}", dataItem.Id)
            file.Text = dataItem.Title

        End Sub

    End Class

End Namespace