noble (3) gensio_event.3.gz

Provided by: libgensio-dev_2.8.2-6.1build1_amd64 bug

NAME

       gensio_event - Event handler for events from a gensio

SYNOPSIS

       #include <gensio/gensio.h>

       typedef int (*gensio_event)(struct gensio *io, void *user_data,
                           int event, int err,
                           unsigned char *buf, gensiods *buflen,
                           const char *const *auxdata);

DESCRIPTION

       When an event happens on a gensio that is reported to the user, the gensio library calls the gensio_event
       type handler that was registered with the gensio.

       The use of the various parameters depends on the particular event.  The parameters that don't vary are:

       io     - The gensio the event is being reported for.

       user_data
              - The user_data supplied when the event handler was registered.

       event  - The particular event being reported.

       Events follow.

   GENSIO_EVENT_READ
       Called when data is read from the I/O device.

       If err is zero, buf points to a data buffer and buflen is the number of bytes available.

       If err is set, buf and buflen are undefined and you should not  use  them  or  modify  them.   err  is  a
       standard gensio errno.

       If err is non-zero, you must set the number of bytes consumed in buflen.  Note that you must disable read
       if you don't consume all the bytes or in other situations where you don't want the read  handler  called.
       auxdata,  if  not  NULL, may contain information about the message, like if it is out of band (oob) data.
       See information on the specific gensio for details.

       Note that only one read callback is allowed to run at a time on a gensio.

       If an error is reported in err, then the gensio will be closed.  This is used to report  that  the  other
       end closed the connection (GE_REMCLOSE), or that other internal errors occurred.

       You should always return zero, it used to not matter, but it does now.

   GENSIO_EVENT_WRITE_READY
       Called when data can be written to the I/O device.

       Note that only one write callback is allowed to run at a time on a gensio.

       Unlike  Unix-like  systems,  a  write  handler  will  be  called  (if  enabled) if the lower layer has an
       exception.  This is necessary because we don't have a separate exception handler coming  from  the  lower
       layer.  But this lets the write operation return a failure if something has gone wrong.

       You should always return zero, it used to not matter, but it does now.

   GENSIO_EVENT_NEW_CHANNEL
       A new channel has been created by the remote end of the connection.  The new channel gensio is in buf and
       must be cast.  Information about the channel  will  be  passed  in  auxdata,  see  documentation  on  the
       particular  gensio  for details.  If this returns an error (non-zero) the channel is shut down, though in
       the future specific error returns may have different behavior.   You  must  return  GE_NOTSUP  (like  you
       should  for  all unhandled events) if you don't support this event.  All other error returns besides zero
       and GE_NOTSUP are reserved.

   GENSIO_EVENT_SEND_BREAK
       Got a request from the other end to send a break.  Telnet client or server.

       Blocked if gensio read is disabled.

   GENSIO_EVENT_AUTH_BEGIN
       Authorization has begun, the username and service is available but nothing else.

       There are a few special return values from this event:

       GE_AUTHREJECT
              - Fail the connection, but continue to go through the motions.  This should be called if the  user
              was invalid or data wasn't properly provided.

       0      -  authorization has succeeded.  No more authentication is required, but the protocol may still go
              through the motions of the protocol.

       GE_NOTSUP
              - Just continue with authentication.

       Any other error will terminate the connection, these should generally be things like out  of  memory  and
       such, NOT authentication failures of any kind.

       certauth only

   GENSIO_EVENT_PRECERT_VERIFY
       The  connection  has  received  a certificate but has not verified it yet.  This lets the user modify the
       certificate authority based on certificate information.

       Return values are the same as GENSIO_EVENT_AUTH_BEGIN.

       ssl and certauth

   GENSIO_EVENT_POSTCERT_VERIFY
       The connection has received a certificate and has verified it.  The verification may have  failed.   This
       lets the user handle their own verification override.  err will be one of the following:

       0      on verification success.

       GE_CERTNOTFOUND
              if no certificate was found

       GE_CERTREVOKED
              if the if the certificate was revoked

       GE_CERTEXPIRED
              if the certificate has expired

       GE_CERTINVALID
              for other errors.

       Any  other  error  will terminate the connection, these should generally be things like out of memory and
       such, NOT authentication failures of any kind.

       auxdata[0] will be an error string (or NULL if none available).  Make sure to check if  auxdata  is  NULL
       before indexing auxdata[0].

       Return values are:

       0      - Authentication successed (even if an error was reported).

       GE_NOTSUP
              -  Continue  with the authentication process.  Password authentication may occur, for instance, if
              an error was reported.

       GE_AUTHREJECT
              - Fail the authentication. No more authentication will occur.

       ssl and certauth

   GENSIO_EVENT_PASSWORD_VERIFY
       A password has been received from the remote end, it is passed in buf.  The callee  should  validate  it.
       If  doing  2-factor auth, you should also fetch the 2-factor data with the GENSIO_CONTROL_2FA control and
       handle that here, too.  If this function is called, GENSIO_EVENT_2FA_VERIFY is not called.  The length is
       passed in *buflen.  Note that the buf is nil terminated one past the length.  Return values are:

       0      - The password verification succeeds.

       GE_NOTSUP
              - Fail the validation, but the connection shutdown will depend on the setting of allow-authfail.

       GE_AUTHREJECT
              - Reject the authorization for some other reason besides failing validation.

       Any  other  error  will terminate the connection, these should generally be things like out of memory and
       such, NOT authentication failures of any kind.

       certauth only

   GENSIO_EVENT_REQUEST_PASSWORD
       On the client side of an authorization, the remote end has requested that a password be sent.  buf points
       to  a buffer of *buflen bytes to place the password in, the user should put the password there and update
       *buflen to the actual length.

       Return 0 for success, or any other gensio error to fail the password fetch.

   GENSIO_EVENT_REQUEST_2FA
       On the client side of an authorization, the remote end has requested two-factor authentication data,  but
       it has not been supplied already.  buf points to a pointer to a buffer (unsigned char **) that you should
       return.  It should be allocated with the zalloc function of the os_functions in use.  *buflen is where to
       put the size of the buffer.  This buffer will be zeroed and freed when done.

       Return 0 for success, or any other gensio error to fail the 2FA fetch.

   GENSIO_EVENT_2FA_VERIFY
       A  2-factor auth has been received from the remote end and passed as part of the password transfer.  This
       is only called if the login was validated with a certificate, this is called to handle 2-factor auth with
       a  certificate.   The 2fa data is passed in buf.  The callee should validate it.  The length is passed in
       *buflen.  Note that the buf is nil terminated one past the length.  Return values are:

       0      - The verification succeeds.

       GE_NOTSUP
              - Fail the validation, but the connection shutdown will depend on the setting of allow-authfail.

       GE_AUTHREJECT
              - Reject the authorization for some other reason besides failing validation.

       Any other error will terminate the connection, these should generally be things like out  of  memory  and
       such, NOT authentication failures of any kind.

       certauth only

   GENSIO_EVENT_PARMLOG
       When  parsing  a gensio string, this will be called if the gensio detects an error in the initial parsing
       or initial configuration.  This is called only during the allocation (  str_to_gensio()  or  equivalent).
       Logging  this  information  will  make  it  easier  for  users to find out what's wrong with their gensio
       strings.

       The buf parameter contains a pointer to the following structure:

       struct gensio_parmlog_data {
           const char *log;
           va_list args;
       };

       which can be printed with normal vprintf() and the like.

   GENSIO_EVENT_WIN_SIZE
       The other end of the connection is reporting a window size change.  Currently only on telnet with RFC1073
       enabled.

   GENSIO_EVENT_LOG
       Used to report general logs in gensios while processing.  Can be called any time the gensio exists.

       The buf parameter contains a pointer to the following structure:

       struct gensio_log_data {
           const char *log;
           va_list args;
       };

       which can be printed with normal vprintf() and the like.

   SERIAL PORT CONTROLS
       These  are  controls  for  serial  port settings.  These are received on the server side only.  It should
       respond by setting the value (if possible and the value isn't zero) and responding with the current value
       with sergensio_xxx().

       If  the  server  receives  a  zero  value for any of this, it should just report the value and not change
       anything.

       GENSIO_EVENT_SER_BAUD
       GENSIO_EVENT_SER_DATASIZE
       GENSIO_EVENT_SER_PARITY
       GENSIO_EVENT_SER_STOPBITS
       GENSIO_EVENT_SER_FLOWCONTROL
       GENSIO_EVENT_SER_IFLOWCONTROL
       GENSIO_EVENT_SER_SBREAK
       GENSIO_EVENT_SER_DTR
       GENSIO_EVENT_SER_RTS

       For baud, databits, and stopbits, the value is an integer with the number.

       Parity values can be:
       GENSIO_SER_PARITY_NONE
       GENSIO_SER_PARITY_ODD
       GENSIO_SER_PARITY_EVEN
       GENSIO_SER_PARITY_MARK
       GENSIO_SER_PARITY_SPACE

       Flow control values can be:
       GENSIO_SER_FLOWCONTROL_NONE
       GENSIO_SER_FLOWCONTROL_XON_XOFF
       GENSIO_SER_FLOWCONTROL_RTS_CTS

       Input flow control values can be:
       GENSIO_SER_FLOWCONTROL_DCD
       GENSIO_SER_FLOWCONTROL_DTR
       GENSIO_SER_FLOWCONTROL_DSR

       For values that are on/off (the rest), use the following:
       GENSIO_SER_ON
       GENSIO_SER_OFF

   SIGNATURE
       GENSIO_EVENT_SER_SIGNATURE is received on the server side only and is a request for the  signature.   The
       server should respond by send the signature with sergensio_signature().  No value is passed in this case.

   STATE FUNCTIONS
       GENSIO_EVENT_SER_MODEMSTATE_MASK
       GENSIO_EVENT_SER_LINESTATE_MASK
       These are received on the server side to request updating the mask of reported values.  The server should
       respond by returning the current mask with the  sergensio_modemstate  or  sergensio_linestate  functions.
       The server need not handle all the bits requested by the user.

       GENSIO_EVENT_SER_MODEMSTATE
       GENSIO_EVENT_SER_LINESTATE

       On  the client side, these are reporting current modemstate and linestate changes as an unsigned integer.
       See sergensio_modemstate(3) and sergensio_linestate(3) for a meaning of the bits in the integer.

   OTHER SERIAL PORT CONTROLS
       These are server-only, these are received requesting the various operations.  The server should do  them,
       but  no  response  is  required.   You  may  notice  that break is not here, break is handled through the
       GENSIO_EVENT_SEND_BREAK event.

       GENSIO_EVENT_SER_FLOW_STATE
       GENSIO_EVENT_SER_FLUSH

   SYNC
       GENSIO_EVENT_SER_SYNC is a special operation that comes in when a TCP sync event is received.  It may  be
       received  on  both  sides.   A  server should send a break.  The client can do whatever it wants with the
       information, that is not defined by the RFC2217 specification.

OTHER EVENTS

       sergensio gensios have a set of other events, see sergensio(5) for details.  Other gensio  that  are  not
       part of the gensio library proper may have their own events, too.

RETURN VALUES

       See  the  individual  events  for  the values you should return.  If an event is not handled by the event
       handler,  the  handler  must  return  GE_NOTSUP,  except   in   the   case   of   GENSIO_EVENT_READ   and
       GENSIO_EVENT_WRITE_READY which must be handled.

SEE ALSO

       gensio_set_callback(3),    str_to_gensio_child(3),    gensio_open_channel(3),   gensio_open_channel_s(3),
       gensio_acc_str_to_gensio(3), str_to_gensio(3) sergensio(5), gensio_err(3)

                                                   21 Feb 2019                                   gensio_event(3)