ProFTPD Developer's Guide: NetIO API Functions

ProFTPD Version 1.2

NetIO API Functions

  pr_netio_t *pr_alloc_netio(pool *pool);
  int pr_register_netio(pr_netio_t *netio, int strm_types);
  int pr_unregister_netio(int strm_types);

The pr_alloc_netio() function allocates a pr_netio_stream_t object from the given pool, and returns a pointer to that object. The callback pointers for this object will all be initialized to the system default callbacks.

The pr_register_netio() function sets the given netio object as a stream to use from that point on, after verifying that the given netio has valid pointers for all of its callbacks. If NULL is given as a argument, this function will automatically instantiate a pr_netio_stream_t object and register it. The strm_types parameter is used to signal for which types of streams this object should be used; strm_types may be one of the following flags:

• PR_NETIO_STRM_CTRL
  Use this stream for control channel I/O
  
• PR_NETIO_STRM_DATA
  Use this stream for data channel I/O
  
• PR_NETIO_STRM_OTHR
  Use this stream for "other" channels. Note: this is very rarely used (e.g. for streams used to perform RFC913 identity lookups).

The pr_unregister_netio() function removes any custom objects that have been registered for the given strm_types. The default objects cannot be unregistered.

Custom NetIO Functions
The following are the function prototypes to which any custom NetIO functions must adhere:

  void (*abort)(pr_netio_stream_t *nstrm);
  int (*close)(pr_netio_stream_t *nstrm);
  pr_netio_stream_t *(*open)(pr_netio_stream_t *nstrm, int fd, int mode);
  int (*poll)(pr_netio_stream_t *nstrm);
  int (*postopen)(pr_netio_stream_t *nstrm);
  int (*read)(pr_netio_stream_t *nstrm, char *buf, size_t buflen);
  pr_netio_stream_t *(*reopen)(pr_netio_stream_t *nstrm, int fd, int mode);
  int (*shutdown)(pr_netio_stream_t *nstrm, int how);
  int (*write)(pr_netio_stream_t *nstrm, char *buf, size_t buflen);