NAME

SYNOPSIS

#include <libssh2.h>
void *libssh2_session_callback_set(LIBSSH2_SESSION *session,
                                   int cbtype, void *callback);

DESCRIPTION

session - Session instance as returned by libssh2_session_init_ex(3)

cbtype - Callback type. One of the types listed in Callback Types.

callback - Pointer to custom callback function. The prototype for this function must match the associated callback declaration macro.

CALLBACK TYPES

LIBSSH2_CALLBACK_IGNORE

Called when a SSH_MSG_IGNORE message is received

LIBSSH2_CALLBACK_DEBUG

Called when a SSH_MSG_DEBUG message is received

LIBSSH2_CALLBACK_DISCONNECT

Called when a SSH_MSG_DISCONNECT message is received

LIBSSH2_CALLBACK_MACERROR

Called when a mismatched MAC has been detected in the transport layer. If the function returns 0, the packet will be accepted nonetheless.

LIBSSH2_CALLBACK_X11

Called when an X11 connection has been accepted

LIBSSH2_CALLBACK_SEND

Called when libssh2 wants to send data on the connection. Can be set to a custom function to handle I/O your own way.

The prototype of the callback:

ssize_t sendcb(libssh2_socket_t sockfd, const void *buffer,
               size_t length, int flags, void **abstract);
    

sockfd is the socket to write to, buffer points to the data to send, length is the size of the data, flags is the flags that would've been used to a send() call and abstract is a pointer to the abstract pointer set in the libssh2_session_init_ex(3) call.

The callback returns the number of bytes sent, or -1 for error. The special return code -EAGAIN can be returned to signal that the send was aborted to prevent getting blocked and it needs to be called again.

LIBSSH2_CALLBACK_RECV

Called when libssh2 wants to read data from the connection. Can be set to a custom function to handle I/O your own way.

The prototype of the callback:

ssize_t recvcb(libssh2_socket_t sockfd, void *buffer,
               size_t length, int flags, void **abstract);
    

sockfd is the socket to read from, buffer where to store received data into, length is the size of the buffer, flags is the flags that would've been used to a recv() call and abstract is a pointer to the abstract pointer set in the libssh2_session_init_ex(3) call.

The callback returns the number of bytes read, or -1 for error. The special return code -EAGAIN can be returned to signal that the read was aborted to prevent getting blocked and it needs to be called again.

RETURN VALUE

SEE ALSO