I couldn’t get Sharepoint to be loaded as an External Storage in Nextcloud. I had find a way to use the old school `curl` to debug the problem.

To properly authenticate, you will have to add some extra parameters to curl

$ curl –ntlm –negotiate -u <Domain>/<Username>:<Password> “http://<url>/<site>/_api/Web/getfolderbyserverrelativeurl(‘%2F<site>/<Folder>’)?$select=Length,TimeLastModified” -v

Notice the `–ntlm –negotiate`. These parameters enable “NTLM Authentication Scheme for HTTP” rather that the usual HTTP Basic Auth. This in turns make lots of back and forth between the curl and MS Sharepoint.

The logs of my HAProxy looks like this. We can see that the curl request has made 3 HTTP requests.

web sharepoint/sharepoint 0/0/1/8/9 401 503 - - ---- 2/2/0/1/0 0/0 "GET /my/_api/Web/getfolderbyserverrelativeurl('%2Fmy/MeraDocs')?=Length,TimeLastModified HTTP/1.1"
web sharepoint/sharepoint 0/0/0/8/8 401 830 - - ---- 2/2/0/1/0 0/0 "GET /my/_api/Web/getfolderbyserverrelativeurl('%2Fmy/MeraDocs')?=Length,TimeLastModified HTTP/1.1"
web sharepoint/sharepoint 0/0/0/15/18 200 3314 - - ---- 2/2/0/1/0 0/0 "GET /my/_api/Web/getfolderbyserverrelativeurl('%2Fmy/MeraDocs')?=Length,TimeLastModified HTTP/1.1"

However I was getting a 404 response in the third response initially. Turns out the API endpoints are different for OneDrive, SharePoint Online and SharePoint Server 2016:

Since I was using SharePoint Server locally, I chose the 2nd endpoint and it worked perfect.

[1] http://www.commandlinefu.com/commands/view/7005/get-a-file-from-sharepoint-with-curl

[2] https://stackoverflow.com/questions/15697157/using-curl-with-ntlm-auth-to-make-a-post-is-failing

[3] https://docs.microsoft.com/en-us/onedrive/developer/rest-api/getting-started/sharepoint-server-2016