libssh_channel(3)

NAME
libssh_channel - The SSH channel functions

Functions that manage a SSH channel.

  Functions
int channel_read_buffer (ssh_channel channel, ssh_buffer buffer, uint32_t count, int is_stderr)
Read data from a channel into a buffer.
ssh_channel ssh_channel_accept_forward (ssh_session session, int timeout_ms, int *destination_port)
Accept an incoming TCP/IP forwarding channel and get information about incomming connection.
ssh_channel ssh_channel_accept_x11 (ssh_channel channel, int timeout_ms)
Accept an X11 forwarding channel.
int ssh_channel_cancel_forward (ssh_session session, const char *address, int port)
Sends the 'cancel-tcpip-forward' global request to ask the server to cancel the tcpip-forward request.
int ssh_channel_change_pty_size (ssh_channel channel, int cols, int rows)
Change the size of the terminal associated to a channel.
int ssh_channel_close (ssh_channel channel)
Close a channel.
void ssh_channel_free (ssh_channel channel)
Close and free a channel.
int ssh_channel_get_exit_status (ssh_channel channel)
Get the exit status of the channel (error code from the executed instruction).
ssh_session ssh_channel_get_session (ssh_channel channel)
Recover the session in which belongs a channel.
int ssh_channel_is_closed (ssh_channel channel)
Check if the channel is closed or not.
int ssh_channel_is_eof (ssh_channel channel)
Check if remote has sent an EOF.
int ssh_channel_is_open (ssh_channel channel)
Check if the channel is open or not.
int ssh_channel_listen_forward (ssh_session session, const char *address, int port, int *bound_port)
Sends the 'tcpip-forward' global request to ask the server to begin listening for inbound connections.
ssh_channel ssh_channel_new (ssh_session session)
Allocate a new channel.
int ssh_channel_open_auth_agent (ssh_channel channel)
Open an agent authentication forwarding channel.
int ssh_channel_open_forward (ssh_channel channel, const char *remotehost, int remoteport, const char *sourcehost, int localport)
Open a TCP/IP forwarding channel.
int ssh_channel_open_reverse_forward (ssh_channel channel, const char *remotehost, int remoteport, const char *sourcehost, int localport)
Open a TCP/IP reverse forwarding channel.
int ssh_channel_open_session (ssh_channel channel)
Open a session channel (suited for a shell, not TCP forwarding).
int ssh_channel_open_x11 (ssh_channel channel, const char *orig_addr, int orig_port)
Open a X11 channel.
int ssh_channel_poll (ssh_channel channel, int is_stderr)
Polls a channel for data to read.
int ssh_channel_poll_timeout (ssh_channel channel, int timeout, int is_stderr)
Polls a channel for data to read, waiting for a certain timeout.
int ssh_channel_read (ssh_channel channel, void *dest, uint32_t count, int is_stderr)
Reads data from a channel.
int ssh_channel_read_nonblocking (ssh_channel channel, void *dest, uint32_t count, int is_stderr)
Do a nonblocking read on the channel.
int ssh_channel_read_timeout (ssh_channel channel, void *dest, uint32_t count, int is_stderr, int timeout)
Reads data from a channel.
int ssh_channel_request_env (ssh_channel channel, const char *name, const char *value)
Set environment variables.
int ssh_channel_request_exec (ssh_channel channel, const char *cmd)
Run a shell command without an interactive shell.
int ssh_channel_request_pty (ssh_channel channel)
Request a PTY.
int ssh_channel_request_pty_size (ssh_channel channel, const char *terminal, int col, int row)
Request a pty with a specific type and size.
int ssh_channel_request_send_exit_signal (ssh_channel channel, const char *sig, int core, const char *errmsg, const char *lang)
Send an exit signal to remote process (RFC 4254, section 6.10).
int ssh_channel_request_send_exit_status (ssh_channel channel, int exit_status)
Send the exit status to the remote process.
int ssh_channel_request_send_signal (ssh_channel channel, const char *sig)
Send a signal to remote process (as described in RFC 4254, section 6.9).
int ssh_channel_request_shell (ssh_channel channel)
Request a shell.
int ssh_channel_request_subsystem (ssh_channel channel, const char *subsys)
Request a subsystem (for example 'sftp').
int ssh_channel_request_x11 (ssh_channel channel, int single_connection, const char *protocol, const char *cookie, int screen_number)
Sends the 'x11-req' channel request over an existing session channel.
int ssh_channel_select (ssh_channel *readchans, ssh_channel *writechans, ssh_channel *exceptchans, struct timeval *timeout)
Act like the standard select(2) on channels.
int ssh_channel_send_eof (ssh_channel channel)
Send an end of file on the channel.
void ssh_channel_set_blocking (ssh_channel channel, int blocking)
Put the channel into blocking or nonblocking mode.
void ssh_channel_set_counter (ssh_channel channel, ssh_counter counter)
Set the channel data counter.
int ssh_channel_write (ssh_channel channel, const void *data, uint32_t len)
Blocking write on a channel.
int ssh_channel_write_stderr (ssh_channel channel, const void *data, uint32_t len)
Blocking write on a channel stderr.

Detailed Description

Functions that manage a SSH channel.

Function Documentation

  int channel_read_buffer (ssh_channel channel, ssh_buffer buffer, uint32_t count, int is_stderr)

Read data from a channel into a buffer.

Parameters:
    channel The channel to read from.
    buffer The buffer which will get the data.
    count The count of bytes to be read. If it is bigger than 0, the exact size will be read, else (bytes=0) it will return once anything is available.
    is_stderr A boolean value to mark reading from the stderr stream.

Returns:
    The number of bytes read, 0 on end of file or SSH_ERROR on error.

Deprecated
    Please use ssh_channel_read instead

Warning:
    This function doesn't work in nonblocking/timeout mode

See also:
    ssh_channel_read

References ssh_channel_is_eof(), ssh_channel_poll(), and ssh_channel_read().

  ssh_channel ssh_channel_accept_forward (ssh_session session, int timeout_ms, int * destination_port)

Accept an incoming TCP/IP forwarding channel and get information about incomming connection.

Parameters:
    session The ssh session to use.
    timeout_ms A timeout in milliseconds.
    destination_port A pointer to destination port or NULL.

Returns:
    Newly created channel, or NULL if no incoming channel request from the server

Referenced by ssh::Session::acceptForward().

  ssh_channel ssh_channel_accept_x11 (ssh_channel channel, int timeout_ms)

Accept an X11 forwarding channel.

Parameters:
    channel An x11-enabled session channel.
    timeout_ms Timeout in milliseconds.

Returns:
    A newly created channel, or NULL if no X11 request from the server.

References SSH_LOG_PACKET, SSH_LOG_PROTOCOL, SSH_PACKET_CALLBACK, and SSH_PACKET_USED.

Referenced by ssh::Channel::acceptX11().

  int ssh_channel_cancel_forward (ssh_session session, const char * address, int port)

Sends the 'cancel-tcpip-forward' global request to ask the server to cancel the tcpip-forward request.

Parameters:
    session The ssh session to send the request.
    address The bound address on the server.
    port The bound port on the server.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Session::writeKnownhost().

  int ssh_channel_change_pty_size (ssh_channel channel, int cols, int rows)

Change the size of the terminal associated to a channel.

Parameters:
    channel The channel to change the size.
    cols The new number of columns.
    rows The new number of rows.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred.

Warning:
    Do not call it from a signal handler if you are not sure any other libssh function using the same channel/session is running at same time (not 100% threadsafe).

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Channel::changePtySize().

  int ssh_channel_close (ssh_channel channel)

Close a channel. This sends an end of file and then closes the channel. You won't be able to recover any data the server was going to send or was in buffers.

Parameters:
    channel The channel to close.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred.

See also:
    ssh_channel_free()

    ssh_channel_is_eof()

References ssh_blocking_flush(), ssh_channel_send_eof(), SSH_LOG_PACKET, and SSH_LOG_PROTOCOL.

Referenced by ssh::Channel::close(), ssh_channel_free(), and ssh_scp_close().

  void ssh_channel_free (ssh_channel channel)

Close and free a channel.

Parameters:
    channel The channel to free.

Warning:
    Any data unread on this channel will be lost.

References ssh_buffer_free(), and ssh_channel_close().

Referenced by sftp_free(), sftp_new(), ssh_message_free(), ssh_scp_close(), and ssh_scp_free().

  int ssh_channel_get_exit_status (ssh_channel channel)

Get the exit status of the channel (error code from the executed instruction).

Parameters:
    channel The channel to get the status from.

Returns:
    The exit status, -1 if no exit status has been returned (yet).

Warning:
    This function may block until a timeout (or never) if the other side is not willing to close the channel.

If you're looking for an async handling of this register a callback for the exit status.

See also:
    ssh_channel_exit_status_callback

References ssh_channel_is_closed(), and ssh_channel_is_open().

Referenced by ssh::Channel::close().

  ssh_session ssh_channel_get_session (ssh_channel channel)

Recover the session in which belongs a channel.

Parameters:
    channel The channel to recover the session from.

Returns:
    The session pointer.

  int ssh_channel_is_closed (ssh_channel channel)

Check if the channel is closed or not.

Parameters:
    channel The channel to check.

Returns:
    0 if channel is opened, nonzero otherwise.

See also:
    ssh_channel_is_open()

Referenced by ssh::Channel::isClosed(), and ssh_channel_get_exit_status().

  int ssh_channel_is_eof (ssh_channel channel)

Check if remote has sent an EOF.

Parameters:
    channel The channel to check.

Returns:
    0 if there is no EOF, nonzero otherwise.

Referenced by channel_read_buffer(), ssh::Channel::isEof(), ssh_scp_close(), and ssh_scp_pull_request().

  int ssh_channel_is_open (ssh_channel channel)

Check if the channel is open or not.

Parameters:
    channel The channel to check.

Returns:
    0 if channel is closed, nonzero otherwise.

See also:
    ssh_channel_is_closed()

Referenced by ssh::Channel::isOpen(), and ssh_channel_get_exit_status().

  int ssh_channel_listen_forward (ssh_session session, const char * address, int port, int * bound_port)

Sends the 'tcpip-forward' global request to ask the server to begin listening for inbound connections.

Parameters:
    session The ssh session to send the request.
    address The address to bind to on the server. Pass NULL to bind to all available addresses on all protocol families supported by the server.
    port The port to bind to on the server. Pass 0 to ask the server to allocate the next available unprivileged port number
    bound_port The pointer to get actual bound port. Pass NULL to ignore.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Session::writeKnownhost().

  ssh_channel ssh_channel_new (ssh_session session)

Allocate a new channel.

Parameters:
    session The ssh session to use.

Returns:
    A pointer to a newly allocated channel, NULL on error.

References ssh_buffer_free(), ssh_buffer_new(), ssh_get_error(), SSH_LOG_FUNCTIONS, SSH_LOG_PACKET, SSH_LOG_PROTOCOL, SSH_LOG_WARNING, SSH_PACKET_CALLBACK, SSH_PACKET_USED, ssh_string_data(), ssh_string_free(), and ssh_string_len().

Referenced by sftp_new(), ssh_message_free(), and ssh_scp_init().

  int ssh_channel_open_auth_agent (ssh_channel channel)

Open an agent authentication forwarding channel. This type of channel can be opened by a server towards a client in order to provide SSH-Agent services to the server-side process. This channel can only be opened if the client claimed support by sending a channel request beforehand.

Parameters:
    channel An allocated channel.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

See also:
    ssh_channel_open_forward()

  int ssh_channel_open_forward (ssh_channel channel, const char * remotehost, int remoteport, const char * sourcehost, int localport)

Open a TCP/IP forwarding channel.

Parameters:
    channel An allocated channel.
    remotehost The remote host to connected (host name or IP).
    remoteport The remote port.
    sourcehost The numeric IP address of the machine from where the connection request originates. This is mostly for logging purposes.
    localport The port on the host from where the connection originated. This is mostly for logging purposes.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Warning:
    This function does not bind the local port and does not automatically forward the content of a socket to the channel. You still have to use channel_read and channel_write for this.

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_free().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_open_reverse_forward (ssh_channel channel, const char * remotehost, int remoteport, const char * sourcehost, int localport)

Open a TCP/IP reverse forwarding channel.

Parameters:
    channel An allocated channel.
    remotehost The remote host to connected (host name or IP).
    remoteport The remote port.
    sourcehost The source host (your local computer). It's optional and for logging purpose.
    localport The source port (your local computer). It's optional and for logging purpose.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Warning:
    This function does not bind the local port and does not automatically forward the content of a socket to the channel. You still have to use channel_read and channel_write for this.

References ssh_buffer_free(), and ssh_buffer_new().

  int ssh_channel_open_session (ssh_channel channel)

Open a session channel (suited for a shell, not TCP forwarding).

Parameters:
    channel An allocated channel.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

See also:
    ssh_channel_open_forward()

    ssh_channel_request_env()

    ssh_channel_request_shell()

    ssh_channel_request_exec()

Referenced by ssh::Channel::isOpen(), sftp_new(), and ssh_scp_init().

  int ssh_channel_open_x11 (ssh_channel channel, const char * orig_addr, int orig_port)

Open a X11 channel.

Parameters:
    channel An allocated channel.
    orig_addr The source host (the local server).
    orig_port The source port (the local server).

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Warning:
    This function does not bind the local port and does not automatically forward the content of a socket to the channel. You still have to use channel_read and channel_write for this.

References ssh_buffer_free(), and ssh_buffer_new().

  int ssh_channel_poll (ssh_channel channel, int is_stderr)

Polls a channel for data to read.

Parameters:
    channel The channel to poll.
    is_stderr A boolean to select the stderr stream.

Returns:
    The number of bytes available for reading, 0 if nothing is available or SSH_ERROR on error.

Warning:
    When the channel is in EOF state, the function returns SSH_EOF.

See also:
    ssh_channel_is_eof()

Referenced by channel_read_buffer(), ssh::Channel::isOpen(), sftp_async_read(), sftp_read(), ssh_channel_read_nonblocking(), ssh_scp_write(), and ssh_select().

  int ssh_channel_poll_timeout (ssh_channel channel, int timeout, int is_stderr)

Polls a channel for data to read, waiting for a certain timeout.

Parameters:
    channel The channel to poll.
    timeout Set an upper limit on the time for which this function will block, in milliseconds. Specifying a negative value means an infinite timeout. This parameter is passed to the poll() function.
    is_stderr A boolean to select the stderr stream.

Returns:
    The number of bytes available for reading, 0 if nothing is available (timeout elapsed), SSH_EOF on end of file, SSH_ERROR on error.

Warning:
    When the channel is in EOF state, the function returns SSH_EOF.

See also:
    ssh_channel_is_eof()

  int ssh_channel_read (ssh_channel channel, void * dest, uint32_t count, int is_stderr)

Reads data from a channel.

Parameters:
    channel The channel to read from.
    dest The destination buffer which will get the data.
    count The count of bytes to be read.
    is_stderr A boolean value to mark reading from the stderr flow.

Returns:
    The number of bytes read, 0 on end of file or SSH_ERROR on error. In nonblocking mode it Can return 0 if no data is available or SSH_AGAIN.

Warning:
    This function may return less than count bytes of data, and won't block until count bytes have been read.

    The read function using a buffer has been renamed to channel_read_buffer().

References ssh_channel_read_timeout().

Referenced by channel_read_buffer(), sftp_free(), ssh_channel_read_nonblocking(), ssh_scp_close(), ssh_scp_init(), ssh_scp_leave_directory(), ssh_scp_push_directory(), ssh_scp_push_file(), ssh_scp_push_file64(), ssh_scp_read(), ssh_scp_read_string(), and ssh_scp_write().

  int ssh_channel_read_nonblocking (ssh_channel channel, void * dest, uint32_t count, int is_stderr)

Do a nonblocking read on the channel. A nonblocking read on the specified channel. it will return <= count bytes of data read atomically.

Parameters:
    channel The channel to read from.
    dest A pointer to a destination buffer.
    count The count of bytes of data to be read.
    is_stderr A boolean to select the stderr stream.

Returns:
    The number of bytes read, 0 if nothing is available or SSH_ERROR on error.

Warning:
    Don't forget to check for EOF as it would return 0 here.

See also:
    ssh_channel_is_eof()

References ssh_channel_poll(), ssh_channel_read(), ssh_is_blocking(), and ssh_set_blocking().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_read_timeout (ssh_channel channel, void * dest, uint32_t count, int is_stderr, int timeout)

Reads data from a channel.

Parameters:
    channel The channel to read from.
    dest The destination buffer which will get the data.
    count The count of bytes to be read.
    is_stderr A boolean value to mark reading from the stderr flow.
    timeout_ms A timeout in milliseconds. A value of -1 means infinite timeout.

Returns:
    The number of bytes read, 0 on end of file or SSH_ERROR on error. In nonblocking mode it Can return 0 if no data is available or SSH_AGAIN.

Warning:
    This function may return less than count bytes of data, and won't block until count bytes have been read.

    The read function using a buffer has been renamed to channel_read_buffer().

References SSH_LOG_PACKET.

Referenced by ssh::Channel::isOpen(), and ssh_channel_read().

  int ssh_channel_request_env (ssh_channel channel, const char * name, const char * value)

Set environment variables.

Parameters:
    channel The channel to set the environment variables.
    name The name of the variable.
    value The value to set.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Warning:
    Some environment variables may be refused by security reasons.

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_request_exec (ssh_channel channel, const char * cmd)

Run a shell command without an interactive shell. This is similar to 'sh -c command'.

Parameters:
    channel The channel to execute the command.
    cmd The command to execute (e.g. 'ls ~/ -al | grep -i reports').

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Example:

1 rc = channel_request_exec(channel, "ps aux");
2 if (rc > 0) {
3     return -1;
4 }
5
6 while ((rc = channel_read(channel, buffer, sizeof(buffer), 0)) > 0) {
7     if (fwrite(buffer, 1, rc, stdout) != (unsigned int) rc) {
8         return -1;
9     }
10 }

See also:
    ssh_channel_request_shell()

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Channel::isOpen(), and ssh_scp_init().

  int ssh_channel_request_pty (ssh_channel channel)

Request a PTY.

Parameters:
    channel The channel to send the request.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

See also:
    ssh_channel_request_pty_size()

References ssh_channel_request_pty_size().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_request_pty_size (ssh_channel channel, const char * terminal, int col, int row)

Request a pty with a specific type and size.

Parameters:
    channel The channel to sent the request.
    terminal The terminal type ('vt100, xterm,...').
    col The number of columns.
    row The number of rows.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Channel::isOpen(), and ssh_channel_request_pty().

  int ssh_channel_request_send_exit_signal (ssh_channel channel, const char * sig, int core, const char * errmsg, const char * lang)

Send an exit signal to remote process (RFC 4254, section 6.10). This sends the exit status of the remote process. Note, that remote system may not support signals concept. In such a case this request will be silently ignored. Only SSH-v2 is supported (I'm not sure about SSH-v1).

Parameters:
    channel The channel to send signal.
    sig The signal to send (without SIG prefix) (e.g. 'TERM' or 'KILL').
    core A boolean to tell if a core was dumped
    errmsg A CRLF explanation text about the error condition
    lang The language used in the message (format: RFC 3066)

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred (including attempts to send signal via SSH-v1 session).

References ssh_buffer_free(), and ssh_buffer_new().

  int ssh_channel_request_send_exit_status (ssh_channel channel, int exit_status)

Send the exit status to the remote process. Sends the exit status to the remote process (as described in RFC 4254, section 6.10). Only SSH-v2 is supported (I'm not sure about SSH-v1).

Parameters:
    channel The channel to send exit status.
    exit_status The exit status to send

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred. (including attempts to send exit status via SSH-v1 session).

References ssh_buffer_free(), and ssh_buffer_new().

  int ssh_channel_request_send_signal (ssh_channel channel, const char * sig)

Send a signal to remote process (as described in RFC 4254, section 6.9). Sends a signal 'sig' to the remote process. Note, that remote system may not support signals concept. In such a case this request will be silently ignored. Only SSH-v2 is supported (I'm not sure about SSH-v1).

OpenSSH doesn't support signals yet, see: https://bugzilla.mindrot.org/show_bug.cgi?id=1424

Parameters:
    channel The channel to send signal.
    sig The signal to send (without SIG prefix)
     SIGABRT -> ABRT
     SIGALRM -> ALRM
     SIGFPE -> FPE
     SIGHUP -> HUP
     SIGILL -> ILL
     SIGINT -> INT
     SIGKILL -> KILL
     SIGPIPE -> PIPE
     SIGQUIT -> QUIT
     SIGSEGV -> SEGV
     SIGTERM -> TERM
     SIGUSR1 -> USR1
     SIGUSR2 -> USR2

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred (including attempts to send signal via SSH-v1 session).

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_request_shell (ssh_channel channel)

Request a shell.

Parameters:
    channel The channel to send the request.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Referenced by ssh::Channel::isOpen().

  int ssh_channel_request_subsystem (ssh_channel channel, const char * subsys)

Request a subsystem (for example 'sftp').

Parameters:
    channel The channel to send the request.
    subsys The subsystem to request (for example 'sftp').

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

Warning:
    You normally don't have to call it for sftp, see sftp_new().

References ssh_buffer_free(), and ssh_buffer_new().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_request_x11 (ssh_channel channel, int single_connection, const char * protocol, const char * cookie, int screen_number)

Sends the 'x11-req' channel request over an existing session channel. This will enable redirecting the display of the remote X11 applications to local X server over an secure tunnel.

Parameters:
    channel An existing session channel where the remote X11 applications are going to be executed.
    single_connection A boolean to mark only one X11 app will be redirected.
    protocol A x11 authentication protocol. Pass NULL to use the default value MIT-MAGIC-COOKIE-1.
    cookie A x11 authentication cookie. Pass NULL to generate a random cookie.
    screen_number The screen number.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred, SSH_AGAIN if in nonblocking mode and call has to be done again.

References ssh_buffer_free(), ssh_buffer_new(), ssh_message_free(), ssh_message_subtype(), and ssh_message_type().

Referenced by ssh::Channel::isOpen().

  int ssh_channel_select (ssh_channel * readchans, ssh_channel * writechans, ssh_channel * exceptchans, struct timeval * timeout)

Act like the standard select(2) on channels. The list of pointers are then actualized and will only contain pointers to channels that are respectively readable, writable or have an exception to trap.

Parameters:
    readchans A NULL pointer or an array of channel pointers, terminated by a NULL.
    writechans A NULL pointer or an array of channel pointers, terminated by a NULL.
    exceptchans A NULL pointer or an array of channel pointers, terminated by a NULL.
    timeout Timeout as defined by select(2).

Returns:
    SSH_OK on a successful operation, SSH_EINTR if the select(2) syscall was interrupted, then relaunch the function.

References ssh_event_add_session(), ssh_event_dopoll(), ssh_event_free(), ssh_event_new(), and ssh_timeout_update().

  int ssh_channel_send_eof (ssh_channel channel)

Send an end of file on the channel. This doesn't close the channel. You may still read from it but not write.

Parameters:
    channel The channel to send the eof to.

Returns:
    SSH_OK on success, SSH_ERROR if an error occurred.

Example:

1 rc = ssh_channel_send_eof(channel);
2 if (rc == SSH_ERROR) {
3     return -1;
4 }
5 while(!ssh_channel_is_eof(channel)) {
6     rc = ssh_channel_read(channel, buf, sizeof(buf), 0);
7     if (rc == SSH_ERROR) {
8         return -1;
9     }
10 }
11 ssh_channel_close(channel);

See also:
    ssh_channel_close()

    ssh_channel_free()

    ssh_channel_is_eof()

References SSH_LOG_PACKET.

Referenced by ssh::Channel::isOpen(), sftp_free(), ssh_channel_close(), and ssh_scp_close().

  void ssh_channel_set_blocking (ssh_channel channel, int blocking)

Put the channel into blocking or nonblocking mode.

Parameters:
    channel The channel to use.
    blocking A boolean for blocking or nonblocking.

Warning:
    A side-effect of this is to put the whole session in non-blocking mode.

See also:
    ssh_set_blocking()

References ssh_get_error(), SSH_LOG_FUNCTIONS, SSH_LOG_PACKET, SSH_LOG_PROTOCOL, SSH_PACKET_CALLBACK, SSH_PACKET_USED, and ssh_set_blocking().

  void ssh_channel_set_counter (ssh_channel channel, ssh_counter counter)

Set the channel data counter.

1 struct ssh_counter_struct counter = {
2     .in_bytes = 0,
3     .out_bytes = 0,
4     .in_packets = 0,
5     .out_packets = 0
6 };
7
8 ssh_channel_set_counter(channel, &counter);

Parameters:
    channel The SSH channel.
    counter Counter for bytes handled by the channel.

  int ssh_channel_write (ssh_channel channel, const void * data, uint32_t len)

Blocking write on a channel.

Parameters:
    channel The channel to write to.
    data A pointer to the data to write.
    len The length of the buffer to write to.

Returns:
    The number of bytes written, SSH_ERROR on error.

See also:
    ssh_channel_read()

Referenced by sftp_free(), ssh_scp_accept_request(), ssh_scp_deny_request(), ssh_scp_init(), ssh_scp_leave_directory(), ssh_scp_pull_request(), ssh_scp_push_directory(), ssh_scp_push_file64(), ssh_scp_read(), ssh_scp_write(), and ssh::Channel::write().

  int ssh_channel_write_stderr (ssh_channel channel, const void * data, uint32_t len)

Blocking write on a channel stderr.

Parameters:
    channel The channel to write to.
    data A pointer to the data to write.
    len The length of the buffer to write to.

Returns:
    The number of bytes written, SSH_ERROR on error.

See also:
    ssh_channel_read()

Referenced by ssh::Channel::write().

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