I'm writing a simple ftp client using C, and it can connect with filezilla ftp server, glftpd, xlight-ftp server successfully, recving 220 welcome, sending USER, PASS, .... QUIT, but only could NOT working with serv-u 6.4, and it stuck at 220 welcome message(ftp_func.c line:118) and caused next command failure.
I think there is nothing wrong with that serv-u 6.4 as I can access that server using wget.exe, ftp.exe, there must be something wrong with my code and I've enclosed all my source code, help me out, thanks.