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d3a9142dac
Some kinds of channel, even after they've sent EOF in both directions, still have something to do before they initiate the CLOSE mechanism and wind up the channel completely. For example, a session channel with a subprocess running inside it will want to be sure to send the "exit-status" or "exit-signal" notification, even if that happens after bidirectional EOF of the data channels. Previously, the SSH-2 connection layer had the standard policy that once EOF had been both sent and received, it would start the final close procedure. There's a method chan_want_close() by which a Channel could vary this policy in one direction, by indicating that it wanted the close procedure to commence after EOF was sent in only one direction. Its parameters are a pair of booleans saying whether EOF has been sent, and whether it's been received. Now chan_want_close can vary the policy in the other direction as well: if it returns FALSE even when _both_ parameters are true, the connection layer will honour that, and not send CHANNEL_CLOSE. If it does that, the Channel is responsible for indicating when it _does_ want close later, by calling sshfwd_initiate_close.
210 lines
8.8 KiB
C
210 lines
8.8 KiB
C
/*
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* Abstraction of the various ways to handle the local end of an SSH
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* connection-layer channel.
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*/
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#ifndef PUTTY_SSHCHAN_H
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#define PUTTY_SSHCHAN_H
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struct ChannelVtable {
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void (*free)(Channel *);
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/* Called for channel types that were created at the same time as
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* we sent an outgoing CHANNEL_OPEN, when the confirmation comes
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* back from the server indicating that the channel has been
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* opened, or the failure message indicating that it hasn't,
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* respectively. In the latter case, this must _not_ free the
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* Channel structure - the client will call the free method
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* separately. But it might do logging or other local cleanup. */
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void (*open_confirmation)(Channel *);
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void (*open_failed)(Channel *, const char *error_text);
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int (*send)(Channel *, int is_stderr, const void *buf, int len);
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void (*send_eof)(Channel *);
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void (*set_input_wanted)(Channel *, int wanted);
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char *(*log_close_msg)(Channel *);
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int (*want_close)(Channel *, int sent_local_eof, int rcvd_remote_eof);
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/* A method for every channel request we know of. All of these
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* return TRUE for success or FALSE for failure. */
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int (*rcvd_exit_status)(Channel *, int status);
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int (*rcvd_exit_signal)(
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Channel *chan, ptrlen signame, int core_dumped, ptrlen msg);
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int (*rcvd_exit_signal_numeric)(
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Channel *chan, int signum, int core_dumped, ptrlen msg);
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/* A method for signalling success/failure responses to channel
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* requests initiated from the SshChannel vtable with want_reply
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* true. */
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void (*request_response)(Channel *, int success);
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};
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struct Channel {
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const struct ChannelVtable *vt;
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unsigned initial_fixed_window_size;
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};
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#define chan_free(ch) ((ch)->vt->free(ch))
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#define chan_open_confirmation(ch) ((ch)->vt->open_confirmation(ch))
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#define chan_open_failed(ch, err) ((ch)->vt->open_failed(ch, err))
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#define chan_send(ch, err, buf, len) ((ch)->vt->send(ch, err, buf, len))
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#define chan_send_eof(ch) ((ch)->vt->send_eof(ch))
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#define chan_set_input_wanted(ch, wanted) \
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((ch)->vt->set_input_wanted(ch, wanted))
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#define chan_log_close_msg(ch) ((ch)->vt->log_close_msg(ch))
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#define chan_want_close(ch, leof, reof) ((ch)->vt->want_close(ch, leof, reof))
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#define chan_rcvd_exit_status(ch, status) \
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((ch)->vt->rcvd_exit_status(ch, status))
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#define chan_rcvd_exit_signal(ch, sig, core, msg) \
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((ch)->vt->rcvd_exit_signal(ch, sig, core, msg))
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#define chan_rcvd_exit_signal_numeric(ch, sig, core, msg) \
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((ch)->vt->rcvd_exit_signal_numeric(ch, sig, core, msg))
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#define chan_request_response(ch, success) \
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((ch)->vt->request_response(ch, success))
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/*
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* Reusable methods you can put in vtables to give default handling of
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* some of those functions.
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*/
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/* open_confirmation / open_failed for any channel it doesn't apply to */
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void chan_remotely_opened_confirmation(Channel *chan);
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void chan_remotely_opened_failure(Channel *chan, const char *errtext);
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/* want_close for any channel that wants the default behaviour of not
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* closing until both directions have had an EOF */
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int chan_default_want_close(Channel *, int, int);
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/* default implementations that refuse all the channel requests */
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int chan_no_exit_status(Channel *, int);
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int chan_no_exit_signal(Channel *, ptrlen, int, ptrlen);
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int chan_no_exit_signal_numeric(Channel *, int, int, ptrlen);
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/* default implementation that never expects to receive a response */
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void chan_no_request_response(Channel *, int);
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/*
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* Constructor for a trivial do-nothing implementation of
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* ChannelVtable. Used for 'zombie' channels, i.e. channels whose
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* proper local source of data has been shut down or otherwise stopped
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* existing, but the SSH side is still there and needs some kind of a
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* Channel implementation to talk to. In particular, the want_close
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* method for this channel always returns 'yes, please close this
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* channel asap', regardless of whether local and/or remote EOF have
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* been sent - indeed, even if _neither_ has.
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*/
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Channel *zombiechan_new(void);
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/* ----------------------------------------------------------------------
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* This structure is owned by an SSH connection layer, and identifies
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* the connection layer's end of the channel, for the Channel
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* implementation to talk back to.
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*/
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struct SshChannelVtable {
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int (*write)(SshChannel *c, const void *, int);
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void (*write_eof)(SshChannel *c);
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void (*initiate_close)(SshChannel *c, const char *err);
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void (*unthrottle)(SshChannel *c, int bufsize);
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Conf *(*get_conf)(SshChannel *c);
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void (*window_override_removed)(SshChannel *c);
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void (*x11_sharing_handover)(SshChannel *c,
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ssh_sharing_connstate *share_cs,
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share_channel *share_chan,
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const char *peer_addr, int peer_port,
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int endian, int protomajor, int protominor,
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const void *initial_data, int initial_len);
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/*
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* All the outgoing channel requests we support. Each one has a
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* want_reply flag, which will cause a callback to
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* chan_request_response when the result is available.
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*
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* The ones that return 'int' use it to indicate that the SSH
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* protocol in use doesn't support this request at all.
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*
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* (It's also intentional that not all of them have a want_reply
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* flag: the ones that don't are because SSH-1 has no method for
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* signalling success or failure of that request, or because we
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* wouldn't do anything usefully different with the reply in any
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* case.)
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*/
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void (*request_x11_forwarding)(
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SshChannel *c, int want_reply, const char *authproto,
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const char *authdata, int screen_number, int oneshot);
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void (*request_agent_forwarding)(
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SshChannel *c, int want_reply);
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void (*request_pty)(
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SshChannel *c, int want_reply, Conf *conf, int w, int h);
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int (*send_env_var)(
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SshChannel *c, int want_reply, const char *var, const char *value);
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void (*start_shell)(
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SshChannel *c, int want_reply);
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void (*start_command)(
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SshChannel *c, int want_reply, const char *command);
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int (*start_subsystem)(
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SshChannel *c, int want_reply, const char *subsystem);
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int (*send_serial_break)(
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SshChannel *c, int want_reply, int length); /* length=0 for default */
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int (*send_signal)(
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SshChannel *c, int want_reply, const char *signame);
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void (*send_terminal_size_change)(
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SshChannel *c, int w, int h);
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void (*hint_channel_is_simple)(SshChannel *c);
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};
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struct SshChannel {
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const struct SshChannelVtable *vt;
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ConnectionLayer *cl;
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};
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#define sshfwd_write(c, buf, len) ((c)->vt->write(c, buf, len))
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#define sshfwd_write_eof(c) ((c)->vt->write_eof(c))
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#define sshfwd_initiate_close(c, err) ((c)->vt->initiate_close(c, err))
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#define sshfwd_unthrottle(c, bufsize) ((c)->vt->unthrottle(c, bufsize))
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#define sshfwd_get_conf(c) ((c)->vt->get_conf(c))
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#define sshfwd_window_override_removed(c) ((c)->vt->window_override_removed(c))
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#define sshfwd_x11_sharing_handover(c, cs, ch, pa, pp, e, pmaj, pmin, d, l) \
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((c)->vt->x11_sharing_handover(c, cs, ch, pa, pp, e, pmaj, pmin, d, l))
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#define sshfwd_request_x11_forwarding(c, wr, ap, ad, scr, oneshot) \
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((c)->vt->request_x11_forwarding(c, wr, ap, ad, scr, oneshot))
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#define sshfwd_request_agent_forwarding(c, wr) \
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((c)->vt->request_agent_forwarding(c, wr))
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#define sshfwd_request_pty(c, wr, conf, w, h) \
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((c)->vt->request_pty(c, wr, conf, w, h))
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#define sshfwd_send_env_var(c, wr, var, value) \
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((c)->vt->send_env_var(c, wr, var, value))
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#define sshfwd_start_shell(c, wr) \
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((c)->vt->start_shell(c, wr))
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#define sshfwd_start_command(c, wr, cmd) \
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((c)->vt->start_command(c, wr, cmd))
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#define sshfwd_start_subsystem(c, wr, subsys) \
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((c)->vt->start_subsystem(c, wr, subsys))
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#define sshfwd_send_serial_break(c, wr, length) \
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((c)->vt->send_serial_break(c, wr, length))
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#define sshfwd_send_signal(c, wr, sig) \
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((c)->vt->send_signal(c, wr, sig))
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#define sshfwd_send_terminal_size_change(c, w, h) \
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((c)->vt->send_terminal_size_change(c, w, h))
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#define sshfwd_hint_channel_is_simple(c) \
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((c)->vt->hint_channel_is_simple(c))
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/* ----------------------------------------------------------------------
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* The 'main' or primary channel of the SSH connection is special,
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* because it's the one that's connected directly to parts of the
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* frontend such as the terminal and the specials menu. So it exposes
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* a richer API.
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*/
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mainchan *mainchan_new(
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PacketProtocolLayer *ppl, ConnectionLayer *cl, Conf *conf,
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int term_width, int term_height, int is_simple, SshChannel **sc_out);
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void mainchan_get_specials(
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mainchan *mc, add_special_fn_t add_special, void *ctx);
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void mainchan_special_cmd(mainchan *mc, SessionSpecialCode code, int arg);
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void mainchan_terminal_size(mainchan *mc, int width, int height);
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#endif /* PUTTY_SSHCHAN_H */
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