libssh: The libssh callbacks

libssh 0.12.0 The SSH library

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Data Structures | Macros | Typedefs | Functions
The libssh callbacks
The libssh API

## Data Structures
struct | ssh_callbacks_struct
struct | ssh_server_callbacks_struct
struct | ssh_socket_callbacks_struct

## Macros
#define | ssh_callbacks_init(p)
| Initializes an ssh_callbacks_struct A call to this macro is mandatory when you have set a new ssh_callback_struct structure. Its goal is to maintain the binary compatibility with future versions of libssh as the structure evolves with time.
#define | ssh_callbacks_exists(p, c)
#define | ssh_callbacks_execute_list(list, cbtype, c, ...)
#define | ssh_callbacks_iterate(_cb_list, _cb_type, _cb_name)
#define | ssh_callbacks_iterate_exec(_cb_name, ...)
#define | ssh_callbacks_iterate_end()
#define | SSH_PACKET_USED 1
#define | SSH_PACKET_NOT_USED 2
#define | SSH_PACKET_CALLBACK(name)
| This macro declares a packet callback handler.

## Typedefs
typedef void(* | ssh_log_callback) (ssh_session session, int priority, const char *message, void *userdata)
| SSH log callback. All logging messages will go through this callback.
typedef void(* | ssh_logging_callback) (int priority, const char *function, const char *buffer, void *userdata)
| SSH log callback.
typedef void(* | ssh_status_callback) (ssh_session session, float status, void *userdata)
| SSH Connection status callback.
typedef void(* | ssh_global_request_callback) (ssh_session session, ssh_message message, void *userdata)
| SSH global request callback. All global request will go through this callback.
typedef void(* | ssh_connect_status_callback) (void *userdata, float status)
| SSH connect status callback. These are functions that report the status of the connection i,e. a function indicating the completed percentage of the connection steps.
typedef ssh_channel(* | ssh_channel_open_request_x11_callback) (ssh_session session, const char *originator_address, int originator_port, void *userdata)
| Handles an SSH new channel open X11 request. This happens when the server sends back an X11 connection attempt. This is a client-side API.
typedef ssh_channel(* | ssh_channel_open_request_auth_agent_callback) (ssh_session session, void *userdata)
| Handles an SSH new channel open "auth-agent" request. This happens when the server sends back an "auth-agent" connection attempt. This is a client-side API.
typedef ssh_channel(* | ssh_channel_open_request_forwarded_tcpip_callback) (ssh_session session, const char *destination_address, int destination_port, const char *originator_address, int originator_port, void *userdata)
| Handles an SSH new channel open "forwarded-tcpip" request. This happens when the server forwards an incoming TCP connection on a port it was previously requested to listen on. This is a client-side API.
typedef int(* | ssh_auth_password_callback) (ssh_session session, const char *user, const char *password, void *userdata)
| SSH authentication callback.
typedef int(* | ssh_auth_none_callback) (ssh_session session, const char *user, void *userdata)
| SSH authentication callback. Tries to authenticates user with the "none" method which is anonymous or passwordless.
typedef int(* | ssh_auth_gssapi_mic_callback) (ssh_session session, const char *user, const char *principal, void *userdata)
| SSH authentication callback. Tries to authenticates user with the "gssapi-with-mic" method.
typedef int(* | ssh_auth_pubkey_callback) (ssh_session session, const char *user, struct ssh_key_struct *pubkey, char signature_state, void *userdata)
| SSH authentication callback.
typedef int(* | ssh_auth_kbdint_callback) (ssh_message message, ssh_session session, void *userdata)
| SSH authentication callback. Tries to authenticates user with the "keyboard-interactive" method.
typedef int(* | ssh_service_request_callback) (ssh_session session, const char *service, void *userdata)
| Handles an SSH service request.
typedef ssh_channel(* | ssh_channel_open_request_session_callback) (ssh_session session, void *userdata)
| Handles an SSH new channel open session request.
typedef ssh_channel(* | ssh_channel_open_request_direct_tcpip_callback) (ssh_session session, const char *destination_address, int destination_port, const char *originator_address, int originator_port, void *userdata)
| Handles an SSH new channel open "direct-tcpip" request. This happens when the client forwards an incoming TCP connection on a port it wants to forward to the destination. This is a server-side API.
typedef int(* | ssh_packet_callback) (ssh_session session, uint8_t type, ssh_buffer packet, void *user)
| Prototype for a packet callback, to be called when a new packet arrives.
typedef int(* | ssh_channel_data_callback) (ssh_session session, ssh_channel channel, void *data, uint32_t len, int is_stderr, void *userdata)
| SSH channel data callback. Called when data is available on a channel.
typedef void(* | ssh_channel_eof_callback) (ssh_session session, ssh_channel channel, void *userdata)
| SSH channel eof callback. Called when a channel receives EOF.
typedef void(* | ssh_channel_close_callback) (ssh_session session, ssh_channel channel, void *userdata)
| SSH channel close callback. Called when a channel is closed by remote peer.
typedef void(* | ssh_channel_signal_callback) (ssh_session session, ssh_channel channel, const char *signal, void *userdata)
| SSH channel signal callback. Called when a channel has received a signal.
typedef void(* | ssh_channel_exit_status_callback) (ssh_session session, ssh_channel channel, int exit_status, void *userdata)
| SSH channel exit status callback. Called when a channel has received an exit status.
typedef void(* | ssh_channel_exit_signal_callback) (ssh_session session, ssh_channel channel, const char *signal, int core, const char *errmsg, const char *lang, void *userdata)
| SSH channel exit signal callback. Called when a channel has received an exit signal.
typedef int(* | ssh_channel_pty_request_callback) (ssh_session session, ssh_channel channel, const char *term, int width, int height, int pxwidth, int pwheight, void *userdata)
| SSH channel PTY request from a client.
typedef int(* | ssh_channel_shell_request_callback) (ssh_session session, ssh_channel channel, void *userdata)
| SSH channel Shell request from a client.
typedef void(* | ssh_channel_auth_agent_req_callback) (ssh_session session, ssh_channel channel, void *userdata)
| SSH auth-agent-request from the client. This request is sent by a client when agent forwarding is available. Server is free to ignore this callback, no answer is expected.
typedef void(* | ssh_channel_x11_req_callback) (ssh_session session, ssh_channel channel, int single_connection, const char *auth_protocol, const char *auth_cookie, uint32_t screen_number, void *userdata)
| SSH X11 request from the client. This request is sent by a client when X11 forwarding is requested(and available). Server is free to ignore this callback, no answer is expected.
typedef int(* | ssh_channel_pty_window_change_callback) (ssh_session session, ssh_channel channel, int width, int height, int pxwidth, int pwheight, void *userdata)
| SSH channel PTY windows change (terminal size) from a client.
typedef int(* | ssh_channel_exec_request_callback) (ssh_session session, ssh_channel channel, const char *command, void *userdata)
| SSH channel Exec request from a client.
typedef int(* | ssh_channel_env_request_callback) (ssh_session session, ssh_channel channel, const char *env_name, const char *env_value, void *userdata)
| SSH channel environment request from a client.
typedef int(* | ssh_channel_subsystem_request_callback) (ssh_session session, ssh_channel channel, const char *subsystem, void *userdata)
| SSH channel subsystem request from a client.
typedef int(* | ssh_channel_write_wontblock_callback) (ssh_session session, ssh_channel channel, uint32_t bytes, void *userdata)
| SSH channel write will not block (flow control).
typedef void(* | ssh_channel_open_resp_callback) (ssh_session session, ssh_channel channel, bool is_success, void *userdata)
| SSH channel open callback. Called when a channel open succeeds or fails.
typedef void(* | ssh_channel_request_resp_callback) (ssh_session session, ssh_channel channel, void *userdata)
| SSH channel request response callback. Called when a response to the pending request is received.

## Functions
LIBSSH_API int | ssh_set_server_callbacks (ssh_session session, ssh_server_callbacks cb)
| Set the session server callback functions.
LIBSSH_API int | ssh_set_callbacks (ssh_session session, ssh_callbacks cb)
| Set the session callback functions.
LIBSSH_API int | ssh_set_channel_callbacks (ssh_channel channel, ssh_channel_callbacks cb)
| Set the channel callback functions.
LIBSSH_API int | ssh_add_channel_callbacks (ssh_channel channel, ssh_channel_callbacks cb)
| Add channel callback functions.
LIBSSH_API int | ssh_remove_channel_callbacks (ssh_channel channel, ssh_channel_callbacks cb)
| Remove a channel callback.

## Detailed Description

Callback which can be replaced in libssh.

## Macro Definition Documentation

## ◆ ssh_callbacks_execute_list

#define ssh_callbacks_execute_list | ( |  | list,
|  |  | cbtype,
|  |  | c,
|  |  | ... )

Value:
do { \
struct ssh_iterator *i = ssh_list_get_iterator(list); \
cbtype cb; \
while (i != NULL){ \
cb = ssh_iterator_value(cbtype, i); \
if (ssh_callbacks_exists(cb, c)) \
cb-> c (__VA_ARGS__, cb->userdata); \
i = i->next; \
} \
} while(0)

## ◆ ssh_callbacks_exists

#define ssh_callbacks_exists | ( |  | p,
|  |  | c )

Value:
(\
(p != NULL) && ( (char *)&((p)-> c) < (char *)(p) + (p)->size ) && \
((p)-> c != NULL) \
)

## ◆ ssh_callbacks_init

#define ssh_callbacks_init | ( |  | p | ) |

Value:
do {\
(p)->size=sizeof(*(p)); \
} while(0);

Initializes an ssh_callbacks_struct A call to this macro is mandatory when you have set a new ssh_callback_struct structure. Its goal is to maintain the binary compatibility with future versions of libssh as the structure evolves with time.

## ◆ ssh_callbacks_iterate

#define ssh_callbacks_iterate | ( |  | _cb_list,
|  |  | _cb_type,
|  |  | _cb_name )

Value:
do { \
struct ssh_iterator *_cb_i = ssh_list_get_iterator(_cb_list); \
_cb_type _cb; \
for (; _cb_i != NULL; _cb_i = _cb_i->next) { \
_cb = ssh_iterator_value(_cb_type, _cb_i); \
if (ssh_callbacks_exists(_cb, _cb_name))

## ◆ ssh_callbacks_iterate_end

#define ssh_callbacks_iterate_end | ( |  | ) |

Value:
} \
} while(0)

## ◆ ssh_callbacks_iterate_exec

#define ssh_callbacks_iterate_exec | ( |  | _cb_name,
|  |  | ... )

Value:
_cb->_cb_name(__VA_ARGS__, _cb->userdata)

## ◆ SSH_PACKET_CALLBACK

#define SSH_PACKET_CALLBACK | ( |  | name | ) |

Value:
int name (ssh_session session, uint8_t type, ssh_buffer packet, void *user)

This macro declares a packet callback handler.

SSH_PACKET_CALLBACK(mycallback){
...
}
SSH_PACKET_CALLBACK
#define SSH_PACKET_CALLBACK(name)
This macro declares a packet callback handler.
Definition callbacks.h:624

## ◆ SSH_PACKET_NOT_USED

#define SSH_PACKET_NOT_USED 2

Packet was not used and should be passed to any other callback available

## ◆ SSH_PACKET_USED

#define SSH_PACKET_USED 1

return values for a ssh_packet_callback Packet was used and should not be parsed by another callback

## Typedef Documentation

## ◆ ssh_auth_gssapi_mic_callback

typedef int(* ssh_auth_gssapi_mic_callback) (ssh_session session, const char *user, const char *principal, void *userdata)

SSH authentication callback. Tries to authenticates user with the "gssapi-with-mic" method.

Parameters

  session | Current session handler
  user | Username of the user (can be spoofed)
  principal | Authenticated principal of the user, including realm.
  userdata | Userdata to be passed to the callback function.

Returns
  SSH_AUTH_SUCCESS Authentication is accepted.
  SSH_AUTH_PARTIAL Partial authentication, more authentication means are needed.
  SSH_AUTH_DENIED Authentication failed.

Warning
  Implementations should verify that parameter user matches in some way the principal. user and principal can be different. Only the latter is guaranteed to be safe.

## ◆ ssh_auth_kbdint_callback

typedef int(* ssh_auth_kbdint_callback) (ssh_message message, ssh_session session, void *userdata)

SSH authentication callback. Tries to authenticates user with the "keyboard-interactive" method.

Parameters

  message | Current message
  session | Current session handler
  userdata | Userdata to be passed to the callback function.

Returns
  SSH_AUTH_SUCCESS Authentication is accepted.
  SSH_AUTH_INFO More info required for authentication.
  SSH_AUTH_PARTIAL Partial authentication, more authentication means are needed.
  SSH_AUTH_DENIED Authentication failed.

## ◆ ssh_auth_none_callback

typedef int(* ssh_auth_none_callback) (ssh_session session, const char *user, void *userdata)

SSH authentication callback. Tries to authenticates user with the "none" method which is anonymous or passwordless.

Parameters

  session | Current session handler
  user | User that wants to authenticate
  userdata | Userdata to be passed to the callback function.

Returns
  SSH_AUTH_SUCCESS Authentication is accepted.
  SSH_AUTH_PARTIAL Partial authentication, more authentication means are needed.
  SSH_AUTH_DENIED Authentication failed.

## ◆ ssh_auth_password_callback

typedef int(* ssh_auth_password_callback) (ssh_session session, const char *user, const char *password, void *userdata)

SSH authentication callback.

These are callbacks used specifically in SSH servers.

Parameters

  session | Current session handler
  user | User that wants to authenticate
  password | Password used for authentication
  userdata | Userdata to be passed to the callback function.

Returns
  SSH_AUTH_SUCCESS Authentication is accepted.
  SSH_AUTH_PARTIAL Partial authentication, more authentication means are needed.
  SSH_AUTH_DENIED Authentication failed.

## ◆ ssh_auth_pubkey_callback

typedef int(* ssh_auth_pubkey_callback) (ssh_session session, const char *user, struct ssh_key_struct *pubkey, char signature_state, void *userdata)

SSH authentication callback.

Parameters

  session | Current session handler
  user | User that wants to authenticate
  pubkey | public key used for authentication
  signature_state | SSH_PUBLICKEY_STATE_NONE if the key is not signed (simple public key probe), SSH_PUBLICKEY_STATE_VALID if the signature is valid. Others values should be replied with a SSH_AUTH_DENIED.
  userdata | Userdata to be passed to the callback function.

Returns
  SSH_AUTH_SUCCESS Authentication is accepted.
  SSH_AUTH_PARTIAL Partial authentication, more authentication means are needed.
  SSH_AUTH_DENIED Authentication failed.

## ◆ ssh_channel_auth_agent_req_callback

typedef void(* ssh_channel_auth_agent_req_callback) (ssh_session session, ssh_channel channel, void *userdata)

SSH auth-agent-request from the client. This request is sent by a client when agent forwarding is available. Server is free to ignore this callback, no answer is expected.

Parameters

  session | the session
  channel | the channel
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_close_callback

typedef void(* ssh_channel_close_callback) (ssh_session session, ssh_channel channel, void *userdata)

SSH channel close callback. Called when a channel is closed by remote peer.

Parameters

  session | Current session handler
  channel | the actual channel
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_data_callback

typedef int(* ssh_channel_data_callback) (ssh_session session, ssh_channel channel, void *data, uint32_t len, int is_stderr, void *userdata)

SSH channel data callback. Called when data is available on a channel.

Parameters

  session | Current session handler
  channel | the actual channel
  data | the data that has been read on the channel
  len | the length of the data
  is_stderr | is 0 for stdout or 1 for stderr
  userdata | Userdata to be passed to the callback function.

Returns
  number of bytes processed by the callee. The remaining bytes will be sent in the next callback message, when more data is available.

## ◆ ssh_channel_env_request_callback

typedef int(* ssh_channel_env_request_callback) (ssh_session session, ssh_channel channel, const char *env_name, const char *env_value, void *userdata)

SSH channel environment request from a client.

Parameters

  session | the session
  channel | the channel
  env_name | name of the environment value to be set
  env_value | value of the environment value to be set
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the env request is accepted
  1 if the request is denied

Warning
  some environment variables can be dangerous if changed (e.g. LD_PRELOAD) and should not be fulfilled.

## ◆ ssh_channel_eof_callback

typedef void(* ssh_channel_eof_callback) (ssh_session session, ssh_channel channel, void *userdata)

SSH channel eof callback. Called when a channel receives EOF.

Parameters

  session | Current session handler
  channel | the actual channel
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_exec_request_callback

typedef int(* ssh_channel_exec_request_callback) (ssh_session session, ssh_channel channel, const char *command, void *userdata)

SSH channel Exec request from a client.

Parameters

  session | the session
  channel | the channel
  command | the shell command to be executed
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the exec request is accepted
  1 if the request is denied

## ◆ ssh_channel_exit_signal_callback

typedef void(* ssh_channel_exit_signal_callback) (ssh_session session, ssh_channel channel, const char *signal, int core, const char *errmsg, const char *lang, void *userdata)

SSH channel exit signal callback. Called when a channel has received an exit signal.

Parameters

  session | Current session handler
  channel | the actual channel
  signal | the signal name (without the SIG prefix)
  core | a boolean telling whether a core has been dumped or not
  errmsg | the description of the exception
  lang | the language of the description (format: RFC 3066)
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_exit_status_callback

typedef void(* ssh_channel_exit_status_callback) (ssh_session session, ssh_channel channel, int exit_status, void *userdata)

SSH channel exit status callback. Called when a channel has received an exit status.

Parameters

  session | Current session handler
  channel | the actual channel
  exit_status | Exit status of the ran command
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_open_request_auth_agent_callback

typedef ssh_channel(* ssh_channel_open_request_auth_agent_callback) (ssh_session session, void *userdata)

Handles an SSH new channel open "auth-agent" request. This happens when the server sends back an "auth-agent" connection attempt. This is a client-side API.

Parameters

  session | current session handler
  userdata | Userdata to be passed to the callback function.

Returns
  a valid ssh_channel handle if the request is to be allowed
  NULL if the request should not be allowed

Warning
  The channel pointer returned by this callback must be closed by the application.

## ◆ ssh_channel_open_request_direct_tcpip_callback

typedef ssh_channel(* ssh_channel_open_request_direct_tcpip_callback) (ssh_session session, const char *destination_address, int destination_port, const char *originator_address, int originator_port, void *userdata)

Handles an SSH new channel open "direct-tcpip" request. This happens when the client forwards an incoming TCP connection on a port it wants to forward to the destination. This is a server-side API.

Parameters

  session | current session handler
  destination_address | the address that the TCP connection connected to
  destination_port | the port that the TCP connection connected to
  originator_address | the originator IP address
  originator_port | the originator port
  userdata | Userdata to be passed to the callback function.

Returns
  a valid ssh_channel handle if the request is to be allowed
  NULL if the request should not be allowed

Warning
  The channel pointer returned by this callback must be closed by the application.

## ◆ ssh_channel_open_request_forwarded_tcpip_callback

typedef ssh_channel(* ssh_channel_open_request_forwarded_tcpip_callback) (ssh_session session, const char *destination_address, int destination_port, const char *originator_address, int originator_port, void *userdata)

Handles an SSH new channel open "forwarded-tcpip" request. This happens when the server forwards an incoming TCP connection on a port it was previously requested to listen on. This is a client-side API.

Parameters

  session | current session handler
  destination_address | the address that the TCP connection connected to
  destination_port | the port that the TCP connection connected to
  originator_address | the originator IP address
  originator_port | the originator port
  userdata | Userdata to be passed to the callback function.

Returns
  a valid ssh_channel handle if the request is to be allowed
  NULL if the request should not be allowed

Warning
  The channel pointer returned by this callback must be closed by the application.

## ◆ ssh_channel_open_request_session_callback

typedef ssh_channel(* ssh_channel_open_request_session_callback) (ssh_session session, void *userdata)

Handles an SSH new channel open session request.

Parameters

  session | current session handler
  userdata | Userdata to be passed to the callback function.

Returns
  a valid ssh_channel handle if the request is to be allowed
  NULL if the request should not be allowed

Warning
  The channel pointer returned by this callback must be closed by the application.

## ◆ ssh_channel_open_request_x11_callback

typedef ssh_channel(* ssh_channel_open_request_x11_callback) (ssh_session session, const char *originator_address, int originator_port, void *userdata)

Handles an SSH new channel open X11 request. This happens when the server sends back an X11 connection attempt. This is a client-side API.

Parameters

  session | current session handler
  userdata | Userdata to be passed to the callback function.
  originator_address | IP address of the machine who sent the request
  originator_port | port number of the machine who sent the request

Returns
  a valid ssh_channel handle if the request is to be allowed
  NULL if the request should not be allowed

Warning
  The channel pointer returned by this callback must be closed by the application.

## ◆ ssh_channel_open_resp_callback

typedef void(* ssh_channel_open_resp_callback) (ssh_session session, ssh_channel channel, bool is_success, void *userdata)

SSH channel open callback. Called when a channel open succeeds or fails.

Parameters

  session | Current session handler
  channel | the actual channel
  is_success | is 1 when the open succeeds, and 0 otherwise.
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_pty_request_callback

typedef int(* ssh_channel_pty_request_callback) (ssh_session session, ssh_channel channel, const char *term, int width, int height, int pxwidth, int pwheight, void *userdata)

SSH channel PTY request from a client.

Parameters

  session | the session
  channel | the channel
  term | The type of terminal emulation
  width | width of the terminal, in characters
  height | height of the terminal, in characters
  pxwidth | width of the terminal, in pixels
  pwheight | height of the terminal, in pixels
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the pty request is accepted
  -1 if the request is denied

## ◆ ssh_channel_pty_window_change_callback

typedef int(* ssh_channel_pty_window_change_callback) (ssh_session session, ssh_channel channel, int width, int height, int pxwidth, int pwheight, void *userdata)

SSH channel PTY windows change (terminal size) from a client.

Parameters

  session | the session
  channel | the channel
  width | width of the terminal, in characters
  height | height of the terminal, in characters
  pxwidth | width of the terminal, in pixels
  pwheight | height of the terminal, in pixels
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the pty request is accepted
  -1 if the request is denied

## ◆ ssh_channel_request_resp_callback

typedef void(* ssh_channel_request_resp_callback) (ssh_session session, ssh_channel channel, void *userdata)

SSH channel request response callback. Called when a response to the pending request is received.

Parameters

  session | Current session handler
  channel | the actual channel
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_shell_request_callback

typedef int(* ssh_channel_shell_request_callback) (ssh_session session, ssh_channel channel, void *userdata)

SSH channel Shell request from a client.

Parameters

  session | the session
  channel | the channel
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the shell request is accepted
  1 if the request is denied

## ◆ ssh_channel_signal_callback

typedef void(* ssh_channel_signal_callback) (ssh_session session, ssh_channel channel, const char *signal, void *userdata)

SSH channel signal callback. Called when a channel has received a signal.

Parameters

  session | Current session handler
  channel | the actual channel
  signal | the signal name (without the SIG prefix)
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_channel_subsystem_request_callback

typedef int(* ssh_channel_subsystem_request_callback) (ssh_session session, ssh_channel channel, const char *subsystem, void *userdata)

SSH channel subsystem request from a client.

Parameters

  session | the session
  channel | the channel
  subsystem | the subsystem required
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the subsystem request is accepted
  1 if the request is denied

## ◆ ssh_channel_write_wontblock_callback

typedef int(* ssh_channel_write_wontblock_callback) (ssh_session session, ssh_channel channel, uint32_t bytes, void *userdata)

SSH channel write will not block (flow control).

Parameters

  | session | the session
  | channel | the channel
  [in] | bytes | size of the remote window in bytes. Writing as much data will not block.
  [in] | userdata | Userdata to be passed to the callback function.

Returns
  0 default return value (other return codes may be added in future).

## ◆ ssh_channel_x11_req_callback

typedef void(* ssh_channel_x11_req_callback) (ssh_session session, ssh_channel channel, int single_connection, const char *auth_protocol, const char *auth_cookie, uint32_t screen_number, void *userdata)

SSH X11 request from the client. This request is sent by a client when X11 forwarding is requested(and available). Server is free to ignore this callback, no answer is expected.

Parameters

  session | the session
  channel | the channel
  single_connection | If true, only one channel should be forwarded
  auth_protocol | The X11 authentication method to be used
  auth_cookie | Authentication cookie encoded hexadecimal
  screen_number | Screen number
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_connect_status_callback

typedef void(* ssh_connect_status_callback) (void *userdata, float status)

SSH connect status callback. These are functions that report the status of the connection i,e. a function indicating the completed percentage of the connection steps.

Parameters

  userdata | Userdata to be passed to the callback function.
  status | Percentage of connection status, going from 0.0 to 1.0 once connection is done.

## ◆ ssh_global_request_callback

typedef void(* ssh_global_request_callback) (ssh_session session, ssh_message message, void *userdata)

SSH global request callback. All global request will go through this callback.

Parameters

  session | Current session handler
  message | the actual message
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_log_callback

typedef void(* ssh_log_callback) (ssh_session session, int priority, const char *message, void *userdata)

SSH log callback. All logging messages will go through this callback.

Parameters

  session | Current session handler
  priority | Priority of the log, the smaller being the more important
  message | the actual message
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_logging_callback

typedef void(* ssh_logging_callback) (int priority, const char *function, const char *buffer, void *userdata)

SSH log callback.

All logging messages will go through this callback.

Parameters

  priority | Priority of the log, the smaller being the more important.
  function | The function name calling the logging functions.
  buffer | The actual message
  userdata | Userdata to be passed to the callback function.

## ◆ ssh_packet_callback

typedef int(* ssh_packet_callback) (ssh_session session, uint8_t type, ssh_buffer packet, void *user)

Prototype for a packet callback, to be called when a new packet arrives.

Parameters

  session | The current session of the packet
  type | packet type (see ssh2.h)
  packet | buffer containing the packet, excluding size, type and padding fields
  user | user argument to the callback and are called each time a packet shows up

Returns
  SSH_PACKET_USED Packet was parsed and used
  SSH_PACKET_NOT_USED Packet was not used or understood, processing must continue

## ◆ ssh_service_request_callback

typedef int(* ssh_service_request_callback) (ssh_session session, const char *service, void *userdata)

Handles an SSH service request.

Parameters

  session | current session handler
  service | name of the service (e.g. "ssh-userauth") requested
  userdata | Userdata to be passed to the callback function.

Returns
  0 if the request is to be allowed
  -1 if the request should not be allowed

## ◆ ssh_status_callback

typedef void(* ssh_status_callback) (ssh_session session, float status, void *userdata)

SSH Connection status callback.

Parameters

  session | Current session handler
  status | Percentage of connection status, going from 0.0 to 1.0 once connection is done.
  userdata | Userdata to be passed to the callback function.

## Function Documentation

## ◆ ssh_add_channel_callbacks()

LIBSSH_API int ssh_add_channel_callbacks | ( | ssh_channel | channel,
|  | ssh_channel_callbacks | cb )

Add channel callback functions.

This function will add channel callback functions to the channel callback list. Callbacks missing from a callback structure will be probed in the next on the list.

Parameters

  channel | The channel to set the callback structure.
  cb | The callback structure itself.

Returns
  SSH_OK on success, SSH_ERROR on error.

See also
  ssh_set_channel_callbacks

## ◆ ssh_remove_channel_callbacks()

LIBSSH_API int ssh_remove_channel_callbacks | ( | ssh_channel | channel,
|  | ssh_channel_callbacks | cb )

Remove a channel callback.

The channel has been added with ssh_add_channel_callbacks or ssh_set_channel_callbacks in this case.

Parameters

  channel | The channel to remove the callback structure from.
  cb | The callback structure to remove

Returns
  SSH_OK on success, SSH_ERROR on error.

## ◆ ssh_set_callbacks()

LIBSSH_API int ssh_set_callbacks | ( | ssh_session | session,
|  | ssh_callbacks | cb )

Set the session callback functions.

This functions sets the callback structure to use your own callback functions for auth, logging and status.

Note, that the callback structure is not copied into the session so it needs to be valid for the whole session lifetime.

struct ssh_callbacks_struct cb = {
.userdata = data,
.auth_function = my_auth_function
};
ssh_callbacks_init(&cb);
ssh_set_callbacks(session, &cb);
ssh_set_callbacks
LIBSSH_API int ssh_set_callbacks(ssh_session session, ssh_callbacks cb)
Set the session callback functions.
Definition callbacks.c:56
ssh_callbacks_init
#define ssh_callbacks_init(p)
Initializes an ssh_callbacks_struct A call to this macro is mandatory when you have set a new ssh_cal...
Definition callbacks.h:514
ssh_callbacks_struct
Definition callbacks.h:176

Parameters

  session | The session to set the callback structure.
  cb | The callback structure itself.

Returns
  SSH_OK on success, SSH_ERROR on error.

## ◆ ssh_set_channel_callbacks()

LIBSSH_API int ssh_set_channel_callbacks | ( | ssh_channel | channel,
|  | ssh_channel_callbacks | cb )

Set the channel callback functions.

This functions sets the callback structure to use your own callback functions for channel data and exceptions.

Note, that the structure is not copied to the channel structure so it needs to be valid as for the whole life of the channel or until it is removed with ssh_remove_channel_callbacks().

struct ssh_channel_callbacks_struct cb = {
.userdata = data,
.channel_data_function = my_channel_data_function
};
ssh_callbacks_init(&cb);
ssh_set_channel_callbacks(channel, &cb);
ssh_set_channel_callbacks
LIBSSH_API int ssh_set_channel_callbacks(ssh_channel channel, ssh_channel_callbacks cb)
Set the channel callback functions.
Definition callbacks.c:113

Parameters

  channel | The channel to set the callback structure.
  cb | The callback structure itself.

Returns
  SSH_OK on success, SSH_ERROR on error.

Warning
  this function will not replace existing callbacks but set the new one atop of them.

## ◆ ssh_set_server_callbacks()

LIBSSH_API int ssh_set_server_callbacks | ( | ssh_session | session,
|  | ssh_server_callbacks | cb )

Set the session server callback functions.

This functions sets the callback structure to use your own callback functions for user authentication, new channels and requests.

Note, that the structure is not copied to the session structure so it needs to be valid for the whole session lifetime.

struct ssh_server_callbacks_struct cb = {
.userdata = data,
.auth_password_function = my_auth_function
};
ssh_callbacks_init(&cb);
ssh_set_server_callbacks(session, &cb);
ssh_set_server_callbacks
LIBSSH_API int ssh_set_server_callbacks(ssh_session session, ssh_server_callbacks cb)
Set the session server callback functions.
Definition callbacks.c:141
ssh_server_callbacks_struct
Definition callbacks.h:382

Parameters

  session | The session to set the callback structure.
  cb | The callback structure itself.

Returns
  SSH_OK on success, SSH_ERROR on error.