The SSH poll functions

Collaboration diagram for The SSH poll functions:

Functions
void	ssh_poll_init (void)
void	ssh_poll_cleanup (void)
int	ssh_poll (ssh_pollfd_t *fds, nfds_t nfds, int timeout)
ssh_poll_handle	ssh_poll_new (socket_t fd, short events, ssh_poll_callback cb, void *userdata)
	Allocate a new poll object, which could be used within a poll context.
void	ssh_poll_free (ssh_poll_handle p)
	Free a poll object.
ssh_poll_ctx	ssh_poll_get_ctx (ssh_poll_handle p)
	Get the poll context of a poll object.
short	ssh_poll_get_events (ssh_poll_handle p)
	Get the events of a poll object.
void	ssh_poll_set_events (ssh_poll_handle p, short events)
	Set the events of a poll object. The events will also be propagated to an associated poll context unless the fd is locked. In that case, only the POLLOUT can be set.
void	ssh_poll_set_fd (ssh_poll_handle p, socket_t fd)
	Set the file descriptor of a poll object. The FD will also be propagated to an associated poll context.
void	ssh_poll_add_events (ssh_poll_handle p, short events)
	Add extra events to a poll object. Duplicates are ignored. The events will also be propagated to an associated poll context.
void	ssh_poll_remove_events (ssh_poll_handle p, short events)
	Remove events from a poll object. Non-existent are ignored. The events will also be propagated to an associated poll context.
socket_t	ssh_poll_get_fd (ssh_poll_handle p)
	Get the raw socket of a poll object.
void	ssh_poll_set_callback (ssh_poll_handle p, ssh_poll_callback cb, void *userdata)
	Set the callback of a poll object.
ssh_poll_ctx	ssh_poll_ctx_new (size_t chunk_size)
	Create a new poll context. It could be associated with many poll object which are going to be polled at the same time as the poll context. You would need a single poll context per thread.
void	ssh_poll_ctx_free (ssh_poll_ctx ctx)
	Free a poll context.
int	ssh_poll_ctx_add (ssh_poll_ctx ctx, ssh_poll_handle p)
	Add a poll object to a poll context.
int	ssh_poll_ctx_add_socket (ssh_poll_ctx ctx, ssh_socket s)
	Add a socket object to a poll context.
void	ssh_poll_ctx_remove (ssh_poll_ctx ctx, ssh_poll_handle p)
	Remove a poll object from a poll context.
int	ssh_poll_ctx_dopoll (ssh_poll_ctx ctx, int timeout)
	Poll all the sockets associated through a poll object with a poll context. If any of the events are set after the poll, the call back function of the socket will be called. This function should be called once within the program's main loop.
ssh_poll_ctx	ssh_poll_get_default_ctx (ssh_session session)
ssh_event	ssh_event_new (void)
	Create a new event context. It could be associated with many ssh_session objects and socket fd which are going to be polled at the same time as the event context. You would need a single event context per thread.
int	ssh_event_add_fd (ssh_event event, socket_t fd, short events, ssh_event_callback cb, void *userdata)
	Add a fd to the event and assign it a callback, when used in blocking mode.
int	ssh_event_add_poll (ssh_event event, ssh_poll_handle p)
	Add a poll handle to the event.
void	ssh_event_remove_poll (ssh_event event, ssh_poll_handle p)
	remove a poll handle to the event.
int	ssh_event_add_session (ssh_event event, ssh_session session)
	remove the poll handle from session and assign them to an event, when used in blocking mode.
int	ssh_event_add_connector (ssh_event event, ssh_connector connector)
	Add a connector to the SSH event loop.
int	ssh_event_dopoll (ssh_event event, int timeout)
	Poll all the sockets and sessions associated through an event object.
int	ssh_event_remove_fd (ssh_event event, socket_t fd)
	Remove a socket fd from an event context.
int	ssh_event_remove_session (ssh_event event, ssh_session session)
	Remove a session object from an event context.
int	ssh_event_remove_connector (ssh_event event, ssh_connector connector)
	Remove a connector from an event context.
void	ssh_event_free (ssh_event event)
	Free an event context.

Detailed Description

Add a generic way to handle sockets asynchronously.

It's based on poll objects, each of which store a socket, its events and a callback, which gets called whenever an event is set. The poll objects are attached to a poll context, which should be allocated on a per thread basis.

Polling the poll context will poll all the attached poll objects and call their callbacks (handlers) if any of the socket events are set. This should be done within the main loop of an application.

Function Documentation

ssh_event_add_connector()

int ssh_event_add_connector	(	ssh_event	event,
		ssh_connector	connector )

Add a connector to the SSH event loop.

Parameters

[in]	event	The SSH event loop
[in]	connector	The connector object

Returns

SSH_OK

SSH_ERROR in case of error

ssh_event_add_fd()

int ssh_event_add_fd	(	ssh_event	event,
		socket_t	fd,
		short	events,
		ssh_event_callback	cb,
		void *	userdata )

Add a fd to the event and assign it a callback, when used in blocking mode.

Parameters

event	The ssh_event
fd	Socket that will be polled.
events	Poll events that will be monitored for the socket. i.e. POLLIN, POLLPRI, POLLOUT
cb	Function to be called if any of the events are set. The prototype of cb is: int (*ssh_event_callback)(socket_t fd, int revents, void *userdata);
userdata	Userdata to be passed to the callback function. NULL if not needed.

Returns

SSH_OK on success SSH_ERROR on failure

ssh_event_add_poll()

int ssh_event_add_poll	(	ssh_event	event,
		ssh_poll_handle	p )

Add a poll handle to the event.

Parameters

event	the ssh_event
p	the poll handle

Returns

SSH_OK on success SSH_ERROR on failure

ssh_event_add_session()

int ssh_event_add_session	(	ssh_event	event,
		ssh_session	session )

remove the poll handle from session and assign them to an event, when used in blocking mode.

Parameters

event	The ssh_event object
session	The session to add to the event.

Returns

SSH_OK on success SSH_ERROR on failure

ssh_event_dopoll()

int ssh_event_dopoll	(	ssh_event	event,
		int	timeout )

Poll all the sockets and sessions associated through an event object.

If any of the events are set after the poll, the call back functions of the sessions or sockets will be called. This function should be called once within the programs main loop. In case of failure, the errno should be consulted to find more information about the failure set by underlying poll imlpementation.

Parameters

event	The ssh_event object to poll.
timeout	An upper limit on the time for which the poll will block, in milliseconds. Specifying a negative value means an infinite timeout. This parameter is passed to the poll() function.

Returns

SSH_OK on success. SSH_ERROR Error happened during the poll. Check errno to get more details about why it failed. SSH_AGAIN Timeout occurred

ssh_event_free()

void ssh_event_free

(

ssh_event

event

)

Free an event context.

Parameters

event

The ssh_event object to free. Note: you have to manually remove sessions and socket fds before freeing the event object.

ssh_event_new()

ssh_event ssh_event_new

(

void

)

Create a new event context. It could be associated with many ssh_session objects and socket fd which are going to be polled at the same time as the event context. You would need a single event context per thread.

Returns

The ssh_event object on success, NULL on failure.

ssh_event_remove_connector()

int ssh_event_remove_connector	(	ssh_event	event,
		ssh_connector	connector )

Remove a connector from an event context.

Parameters

[in]	event	The ssh_event object.
[in]	connector	connector object to remove

Returns

SSH_OK on success

SSH_ERROR on failure

ssh_event_remove_fd()

int ssh_event_remove_fd	(	ssh_event	event,
		socket_t	fd )

Remove a socket fd from an event context.

Parameters

event	The ssh_event object.
fd	The fd to remove.

Returns

SSH_OK on success SSH_ERROR on failure

ssh_event_remove_poll()

void ssh_event_remove_poll	(	ssh_event	event,
		ssh_poll_handle	p )

remove a poll handle to the event.

Parameters

event	the ssh_event
p	the poll handle

ssh_event_remove_session()

int ssh_event_remove_session	(	ssh_event	event,
		ssh_session	session )

Remove a session object from an event context.

Parameters

event	The ssh_event object.
session	The session to remove.

Returns

SSH_OK on success SSH_ERROR on failure

ssh_poll_add_events()

void ssh_poll_add_events	(	ssh_poll_handle	p,
		short	events )

Add extra events to a poll object. Duplicates are ignored. The events will also be propagated to an associated poll context.

Parameters

p	Pointer to an already allocated poll object.
events	Poll events.

ssh_poll_ctx_add()

int ssh_poll_ctx_add	(	ssh_poll_ctx	ctx,
		ssh_poll_handle	p )

Add a poll object to a poll context.

Parameters

ctx	Pointer to an already allocated poll context.
p	Pointer to an already allocated poll object.

Returns

0 on success, < 0 on error

ssh_poll_ctx_add_socket()

int ssh_poll_ctx_add_socket	(	ssh_poll_ctx	ctx,
		ssh_socket	s )

Add a socket object to a poll context.

Parameters

ctx	Pointer to an already allocated poll context.
s	A SSH socket handle

Returns

0 on success, < 0 on error

ssh_poll_ctx_dopoll()

int ssh_poll_ctx_dopoll	(	ssh_poll_ctx	ctx,
		int	timeout )

Poll all the sockets associated through a poll object with a poll context. If any of the events are set after the poll, the call back function of the socket will be called. This function should be called once within the program's main loop.

Parameters

ctx	Pointer to an already allocated poll context.
timeout	An upper limit on the time for which ssh_poll_ctx() will block, in milliseconds. Specifying a negative value means an infinite timeout. This parameter is passed to the poll() function.

Returns

SSH_OK No error. SSH_ERROR Error happened during the poll. SSH_AGAIN Timeout occurred

ssh_poll_ctx_free()

void ssh_poll_ctx_free

(

ssh_poll_ctx

ctx

)

Free a poll context.

Parameters

ctx	Pointer to an already allocated poll context.

ssh_poll_ctx_new()

ssh_poll_ctx ssh_poll_ctx_new

(

size_t

chunk_size

)

Create a new poll context. It could be associated with many poll object which are going to be polled at the same time as the poll context. You would need a single poll context per thread.

Parameters

chunk_size

The size of the memory chunk that will be allocated, when more memory is needed. This is for efficiency reasons, i.e. don't allocate memory for each new poll object, but for the next 5. Set it to 0 if you want to use the library's default value.

ssh_poll_ctx_remove()

void ssh_poll_ctx_remove	(	ssh_poll_ctx	ctx,
		ssh_poll_handle	p )

Remove a poll object from a poll context.

Parameters

ctx	Pointer to an already allocated poll context.
p	Pointer to an already allocated poll object.

ssh_poll_free()

void ssh_poll_free

(

ssh_poll_handle

p

)

Free a poll object.

Parameters

p	Pointer to an already allocated poll object.

ssh_poll_get_ctx()

ssh_poll_ctx ssh_poll_get_ctx

(

ssh_poll_handle

p

)

Get the poll context of a poll object.

Parameters

p	Pointer to an already allocated poll object.

Returns

Poll context or NULL if the poll object isn't attached.

ssh_poll_get_events()

short ssh_poll_get_events

(

ssh_poll_handle

p

)

Get the events of a poll object.

Parameters

p	Pointer to an already allocated poll object.

Returns

Poll events.

ssh_poll_get_fd()

socket_t ssh_poll_get_fd

(

ssh_poll_handle

p

)

Get the raw socket of a poll object.

Parameters

p	Pointer to an already allocated poll object.

Returns

Raw socket.

ssh_poll_new()

ssh_poll_handle ssh_poll_new	(	socket_t	fd,
		short	events,
		ssh_poll_callback	cb,
		void *	userdata )

Allocate a new poll object, which could be used within a poll context.

Parameters

[in]	fd	Socket that will be polled.
[in]	events	Poll events that will be monitored for the socket. i.e. POLLIN, POLLPRI, POLLOUT
[in]	cb	Function to be called if any of the events are set. The prototype of cb is: int (*ssh_poll_callback)(ssh_poll_handle p, socket_t fd, int revents, void *userdata);
[in]	userdata	Userdata to be passed to the callback function. NULL if not needed.

Returns

A new poll object, NULL on error

ssh_poll_remove_events()

void ssh_poll_remove_events	(	ssh_poll_handle	p,
		short	events )

Remove events from a poll object. Non-existent are ignored. The events will also be propagated to an associated poll context.

Parameters

p	Pointer to an already allocated poll object.
events	Poll events.

ssh_poll_set_callback()

void ssh_poll_set_callback	(	ssh_poll_handle	p,
		ssh_poll_callback	cb,
		void *	userdata )

Set the callback of a poll object.

Parameters

p	Pointer to an already allocated poll object.
cb	Function to be called if any of the events are set.
userdata	Userdata to be passed to the callback function. NULL if not needed.

ssh_poll_set_events()

void ssh_poll_set_events	(	ssh_poll_handle	p,
		short	events )

Set the events of a poll object. The events will also be propagated to an associated poll context unless the fd is locked. In that case, only the POLLOUT can be set.

Parameters

p	Pointer to an already allocated poll object.
events	Poll events.

ssh_poll_set_fd()

void ssh_poll_set_fd	(	ssh_poll_handle	p,
		socket_t	fd )

Set the file descriptor of a poll object. The FD will also be propagated to an associated poll context.

Parameters

p	Pointer to an already allocated poll object.
fd	New file descriptor.