s3: libsmb: For SMB2 opens on a DFS share, convert to a DFS path if not already done.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Noel Power <npower@samba.org>

source3/libsmb/cli_smb2_fnum.c

@@ -153,6 +153,42 @@ static uint8_t flags_to_smb2_oplock(uint32_t create_flags)
 	return SMB2_OPLOCK_LEVEL_NONE;
 }
 
+/***************************************************************
+ If we're on a DFS share, ensure we convert to a full DFS path
+ if this hasn't already been done.
+***************************************************************/
+
+static const char *smb2_dfs_share_path(TALLOC_CTX *ctx,
+				       struct cli_state *cli,
+				       const char *path)
+{
+	bool is_dfs = smbXcli_conn_dfs_supported(cli->conn) &&
+			smbXcli_tcon_is_dfs_share(cli->smb2.tcon);
+	bool is_already_dfs_path = false;
+
+	if (!is_dfs) {
+		return path;
+	}
+	is_already_dfs_path = cli_dfs_is_already_full_path(cli, path);
+	if (is_already_dfs_path) {
+		return path;
+	}
+	if (path[0] == '\0') {
+		return talloc_asprintf(ctx,
+				       "%s\\%s",
+					smbXcli_conn_remote_name(cli->conn),
+					cli->share);
+	}
+	while (*path == '\\') {
+		path++;
+	}
+	return talloc_asprintf(ctx,
+			       "%s\\%s\\%s",
+			       smbXcli_conn_remote_name(cli->conn),
+			       cli->share,
+			       path);
+}
+
 /***************************************************************
  Small wrapper that allows SMB2 create to return a uint16_t fnum.
 ***************************************************************/
@@ -254,6 +290,11 @@ struct tevent_req *cli_smb2_create_fnum_send(
 		}
 	}
 
+	fname = smb2_dfs_share_path(state, cli, fname);
+	if (tevent_req_nomem(fname, req)) {
+		return tevent_req_post(req, ev);
+	}
+
 	/* SMB2 is pickier about pathnames. Ensure it doesn't
 	   start in a '\' */
 	if (*fname == '\\') {