Calling the ShareLink Sharepoint REST API Endpoint, but using the CSOM connection

Question

I have a desktop solution that uses CSOM and I use SharePointOnlineCredentials to get authenticated.
I need to share a file but using the ShareLink endpoint. Although I could share my files using the native CSOM methods, ShareLink provides more options that are needed.

I use SharePoint Online. The way I authenticate using SharePointOnlineCredentials is the standard way (creds = new SharePointOnlineCredentials(szUserName, password);)

This is the function I use:

    private static void ShareFile(string szFileName, ClientContext context, string szLoginUrl, SharePointOnlineCredentials creds)
    {
        try
        {
            string szRelativeRemotePath;
            szRelativeRemotePath = (new Uri(szLoginUrl).AbsolutePath) ;
            string szFullRemotePath_File = "https://" + new Uri(szLoginUrl).Host + szRelativeRemotePath + szDocumentLibrary + "/Attachments/"+ szFileName;
            string szFullRemotePath_API = "https://" + new Uri(szLoginUrl).Host + szRelativeRemotePath + "_api/web/GetFileByUrl(@v)/ListItemAllFields/ShareLink?@v=";
            string szRequestURL = szFullRemotePath_API + "%27" + HttpUtility.UrlEncode(szFullRemotePath_File) + "%27";
            HttpWebRequest endpointRequest = (HttpWebRequest)HttpWebRequest.Create(szRequestURL);
            string response = "";
            using (var client = new WebClient())
            {
                client.Credentials = creds;
                client.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");
                client.Headers.Add(HttpRequestHeader.ContentType, "application/json;odata=verbose");
                client.Headers.Add(HttpRequestHeader.Accept, "application/json;odata=verbose");
                client.Headers.Add(HttpRequestHeader.UserAgent, "Mozilla/4.0+(compatible;+MSIE+5.01;+Windows+NT+5.0");
                var endpointUri = new Uri(szRequestURL);
                response = client.UploadString(szRequestURL, "{\"request\":{\"createLink\":true,\"settings\":{\"allowAnonymousAccess\":true,\"linkKind\":2,\"expiration\":null,\"restrictShareMembership\":false,\"updatePassword\":false,\"password\":\"\", \"description\":\"My description\", \"role\":8,\"applicationLink\":false,\"limitUseToApplication\":false}}}");
                dynamic dynObj = JsonConvert.DeserializeObject(response);
                if (dynObj == null )
                {
                    return;
                }
                string szURL= dynObj.d.ShareLink.sharingLinkInfo.Url.Value;
                Console.WriteLine("Sharing link: " + szURL);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("Error sharing files: " + e.ToString());
        }
    }

The problem is that I get the 403 (Forbidden) error. If instead of calling "client.Credentials = creds;", I register an application in the Azure server, and using ADAL I get the access token and I use "client.Headers.Add("Authorization", "Bearer " + szAccessToken);" then the code works just fine.
This means that the code works fine but there is a problem with the authentication mechanism or maybe if I use a connection with the CSOM credentials then I cannot use that endpoint.
If I connect using the same mechanism but instead of calling that endpoint, I call another endpoint like _layouts/15/download.aspx to download a file, then it works fine.

So until now it smells like if the problem is in the permission that the CSOM connection uses.

Thanks

Answer 1

Hi @Pablo Glomby ,

I understand you want to share a file in a document library (szDocumentLibrary), I did following test:

1. prepare a test file in a library

2. Try below code:

           ClientContext clientContext = new ClientContext(SiteUrl);  
           clientContext.Credentials = new SharePointOnlineCredentials(username, securestring);  
   
           var web = clientContext.Web;  
   
           var dig=clientContext.GetFormDigestDirect();  
   
           clientContext.Load(web);  
           clientContext.ExecuteQuery();  
   
           Console.WriteLine($"{web.Title}--{dig.DigestValue}");  
   
           ShareFile(clientContext, clientContext.Credentials as SharePointOnlineCredentials,dig.DigestValue);  
   
           Console.ReadKey();  
   
       }  
   
       private static void ShareFile(ClientContext context, SharePointOnlineCredentials creds, string digest)  
       {  
           try  
           {               
               string szRequestURL = @"https://abc.sharepoint.com/sites/sbdev/_api/web/GetFileByUrl(@v)/ListItemAllFields/ShareLink?@v='/sites/sbdev/My test doc lib/license.txt'";  
   
               string response = "";  
               using (var client = new WebClient())  
               {  
                   client.Credentials = creds;  
                   client.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");  
                   client.Headers.Add(HttpRequestHeader.ContentType, "application/json;odata=verbose");  
                   client.Headers.Add(HttpRequestHeader.Accept, "application/json;odata=verbose");  
                   client.Headers.Add(HttpRequestHeader.UserAgent, "Mozilla/4.0+(compatible;+MSIE+5.01;+Windows+NT+5.0");  
                   client.Headers.Add("X-RequestDigest", digest);  
   
                   var endpointUri = new Uri(szRequestURL);  
   
   
                   response = client.UploadString(szRequestURL, "{\"request\":{\"createLink\":true,\"settings\":{\"allowAnonymousAccess\":true,\"linkKind\":2,\"expiration\":null,\"restrictShareMembership\":false,\"updatePassword\":false,\"password\":\"\", \"description\":\"My description\", \"role\":8,\"applicationLink\":false,\"limitUseToApplication\":false}}}");  
                   dynamic dynObj = JsonConvert.DeserializeObject(response);  
                   if (dynObj == null)  
                   {  
                       return;  
                   }  
                   string szURL = dynObj.d.ShareLink.sharingLinkInfo.Url.Value;  
                   Console.WriteLine("Sharing link: " + szURL);  
               }  
           }  
           catch (Exception e)  
           {  
               Console.WriteLine("Error sharing files: " + e.ToString());  
           }  
       }  
   
   }  
   

   }

Result:

Could you please have a try?

Best Regards,
Baker Kong

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