As I understood that, pptp is implemented upon PPP. Is the current pptp client has any library calls exposed for developers? Since the existing one is a GPL one, I fear to use the source code for my application which is non open source.

If not, does anybody know how to talk to PPPD daemon to send the username, password and status check command like OpenVPN has?

If anybody knows about a LGPL based PPTP client for linux, please let me know.