Provided by: erlang-manpages_16.b.3-dfsg-1ubuntu2.2_all 
NAME
ssh_connection - This module provides API functions to send SSH Connection Protocol
events to the other side of an SSH channel.
DESCRIPTION
The SSH Connection Protocol is used by clients and servers (i.e. SSH channels) to
communicate over the SSH connection. The API functions in this module sends SSH Connection
Protocol events that are received as messages by the remote channel. In the case that the
receiving channel is an Erlang process the message will be on the following format
{ssh_cm, ssh_connection_ref(), ssh_event_msg()}. If the ssh_channel behavior is used to
implement the channel process these will be handled by handle_ssh_msg/2 .
DATA TYPES
Type definitions that are used more than once in this module and/or abstractions to
indicate the intended use of the data type:
boolean() = true | false
string() = list of ASCII characters
timeout() = infinity | integer() - in milliseconds.
ssh_connection_ref() - opaque to the user returned by ssh:connect/3 or sent to an SSH
channel processes
ssh_channel_id() = integer()
ssh_data_type_code() = 1 ("stderr") | 0 ("normal") are currently valid values see RFC 4254
section 5.2.
ssh_request_status() = success | failure
event() = {ssh_cm, ssh_connection_ref(), ssh_event_msg()}
ssh_event_msg() = data_events() | status_events() | terminal_events()
data_events() :
{data, ssh_channel_id(), ssh_data_type_code(), binary() = Data}:
Data has arrived on the channel. This event is sent as result of calling
ssh_connection:send/[3,4,5]
{eof, ssh_channel_id()}:
Indicates that the other side will not send any more data. This event is sent as
result of calling ssh_connection:send_eof/2
status_events() :
{signal, ssh_channel_id(), ssh_signal()}:
A signal can be delivered to the remote process/service using the following message.
Some systems will not support signals, in which case they should ignore this
message. There is currently no funtion to generate this event as the signals refered
to are on OS-level and not something generated by an Erlang program.
{exit_signal, ssh_channel_id(), string() = ExitSignal, string() = ErrorMsg, string() =
LanguageString}:
A remote execution may terminate violently due to a signal then this message may be
received. For details on valid string values see RFC 4254 section 6.10. Special case
of the signals mentioned above.
{exit_status, ssh_channel_id(), integer() = ExitStatus}:
When the command running at the other end terminates, the following message can be
sent to return the exit status of the command. A zero 'exit_status' usually means
that the command terminated successfully. This event is sent as result of calling
ssh_connection:exit_status/3
{closed, ssh_channel_id()}:
This event is sent as result of calling ssh_connection:close/2 Both the handling of
this event and sending of it will be taken care of by the ssh_channel behavior.
terminal_events() :
Channels implementing a shell and command execution on the server side should handle
the following messages that may be sent by client channel processes.
Note:
Events that includes a WantReply expects the event handling process to call
ssh_connection:reply_request/4 with the boolean value of WantReply as the second
argument.
{env, ssh_channel_id(), boolean() = WantReply, string() = Var, string() = Value}:
Environment variables may be passed to the shell/command to be started later. This
event is sent as result of calling ssh_connection:setenv/5
{pty, ssh_channel_id(), boolean() = WantReply, {string() = Terminal, integer() =
CharWidth, integer() = RowHeight, integer() = PixelWidth, integer() = PixelHight,
[{atom() | integer() = Opcode, integer() = Value}] = TerminalModes}}:
A pseudo-terminal has been requested for the session. Terminal is the value of the
TERM environment variable value (e.g., vt100). Zero dimension parameters must be
ignored. The character/row dimensions override the pixel dimensions (when nonzero).
Pixel dimensions refer to the drawable area of the window. The Opcode in the
TerminalModes list is the mnemonic name, represented as an lowercase erlang atom,
defined in RFC 4254 section 8, or the opcode if the mnemonic name is not listed in
the RFC. Example OP code: 53, mnemonic name ECHO erlang atom: echo. There is
currently no API function to generate this event.
{shell, boolean() = WantReply}:
This message will request that the user's default shell be started at the other
end. This event is sent as result of calling ssh_connection:shell/2
{window_change, ssh_channel_id(), integer() = CharWidth, integer() = RowHeight,
integer() = PixWidth, integer() = PixHeight}:
When the window (terminal) size changes on the client side, it MAY send a message
to the server side to inform it of the new dimensions. There is currently no API
function to generate this event.
{exec, ssh_channel_id(), boolean() = WantReply, string() = Cmd}:
This message will request that the server starts execution of the given command.
This event is sent as result of calling ssh_connection:exec/4
EXPORTS
adjust_window(ConnectionRef, ChannelId, NumOfBytes) -> ok
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
NumOfBytes = integer()
Adjusts the SSH flowcontrol window. This shall be done by both client and server
side channel processes.
Note:
Channels implemented with the ssh_channel behavior will normaly not need to call
this function as flow control will be handled by the behavior. The behavior will
adjust the window every time the callback handle_ssh_msg/2 has returned after
processing channel data
close(ConnectionRef, ChannelId) -> ok
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
A server or client channel process can choose to close their session by sending a
close event.
Note:
This function will be called by the ssh_channel behavior when the channel is
terminated see ssh_channel(3erl) so channels implemented with the behavior should
not call this function explicitly.
exec(ConnectionRef, ChannelId, Command, TimeOut) -> ssh_request_status()
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Command = string()
Timeout = timeout()
Should be called by a client channel process to request that the server starts
execution of the given command, the result will be several messages according to
the following pattern. Note that the last message will be a channel close message,
as the exec request is a one time execution that closes the channel when it is
done.
N x {ssh_cm, ssh_connection_ref(), {data, ssh_channel_id(),
ssh_data_type_code(), binary() = Data}} :
The result of executing the command may be only one line or thousands of lines
depending on the command.
0 or 1 x {ssh_cm, ssh_connection_ref(), {eof, ssh_channel_id()}}:
Indicates that no more data will be sent.
0 or 1 x {ssh_cm, ssh_connection_ref(), {exit_signal, ssh_channel_id(), string()
= ExitSignal, string() = ErrorMsg, string() = LanguageString}}:
Not all systems send signals. For details on valid string values see RFC 4254
section 6.10
0 or 1 x {ssh_cm, ssh_connection_ref(), {exit_status, ssh_channel_id(), integer()
= ExitStatus}}:
It is recommended by the ssh connection protocol that this message shall be
sent, but that may not always be the case.
1 x {ssh_cm, ssh_connection_ref(), {closed, ssh_channel_id()}}:
Indicates that the ssh channel started for the execution of the command has now
been shutdown.
exit_status(ConnectionRef, ChannelId, Status) -> ok
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Status = integer()
Should be called by a server channel process to sends the exit status of a command
to the client.
reply_request(ConnectionRef, WantReply, Status, ChannelId) -> ok
Types:
ConnectionRef = ssh_connection_ref()
WantReply = boolean()
Status = ssh_request_status()
ChannelId = ssh_channel_id()
Sends status replies to requests where the requester has stated that they want a
status report e.i . WantReply = true, if WantReply is false calling this function
will be a "noop". Should be called while handling an ssh connection protocol
message containing a WantReply boolean value.
send(ConnectionRef, ChannelId, Data) ->
send(ConnectionRef, ChannelId, Data, Timeout) ->
send(ConnectionRef, ChannelId, Type, Data) ->
send(ConnectionRef, ChannelId, Type, Data, TimeOut) -> ok | {error, timeout} | {error,
closed}
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Data = binary()
Type = ssh_data_type_code()
Timeout = timeout()
Should be called by client- and server channel processes to send data to each
other.
send_eof(ConnectionRef, ChannelId) -> ok | {error, closed}
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Sends eof on the channel ChannelId.
session_channel(ConnectionRef, Timeout) ->
session_channel(ConnectionRef, InitialWindowSize, MaxPacketSize, Timeout) -> {ok,
ssh_channel_id()} | {error, Reason}
Types:
ConnectionRef = ssh_connection_ref()
InitialWindowSize = integer()
MaxPacketSize = integer()
Timeout = timeout()
Reason = term()
Opens a channel for an SSH session. The channel id returned from this function is
the id used as input to the other funtions in this module.
setenv(ConnectionRef, ChannelId, Var, Value, TimeOut) -> ssh_request_status()
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Var = string()
Value = string()
Timeout = timeout()
Environment variables may be passed before starting the shell/command. Should be
called by a client channel processes.
shell(ConnectionRef, ChannelId) -> ssh_request_status()
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Should be called by a client channel process to request that the user's default
shell (typically defined in /etc/passwd in UNIX systems) shall be executed at the
server end.
subsystem(ConnectionRef, ChannelId, Subsystem, Timeout) -> ssh_request_status()
Types:
ConnectionRef = ssh_connection_ref()
ChannelId = ssh_channel_id()
Subsystem = string()
Timeout = timeout()
Should be called by a client channel process for requesting to execute a predefined
subsystem on the server.