2003-03-29 19:52:50 +00:00
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/*
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* Unix PuTTY main program.
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*/
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#include <stdio.h>
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2003-03-31 12:10:53 +00:00
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#include <ctype.h>
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2003-03-31 11:21:07 +00:00
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#include <stdlib.h>
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2003-03-29 19:52:50 +00:00
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#include <assert.h>
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#include <unistd.h>
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2015-08-22 13:07:02 +00:00
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#include <gtk/gtk.h>
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2004-10-06 22:31:07 +00:00
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#include <gdk/gdk.h>
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2003-03-29 19:52:50 +00:00
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Make the configuration dialog non-modal.
Now every call to do_config_box is replaced with a call to
create_config_box, which returns immediately having constructed the
new GTK window object, and is passed a callback function which it will
arrange to be called when the dialog terminates (whether by OK or by
Cancel). That callback is now what triggers the construction of a
session window after 'Open' is pressed in the initial config box, or
the actual mid-session reconfiguration action after 'Apply' is pressed
in a Change Settings box.
We were already prepared to ignore the re-selection of 'Change
Settings' from the context menu of a window that already had a Change
Settings box open (and not accidentally create a second config box for
the same window); but now we do slightly better, by finding the
existing config box and un-minimising and raising it, in case the user
had forgotten it was there.
That's a useful featurelet, but not the main purpose of this change.
The mani point, of course, is that now the multi-window GtkApplication
based front ends now don't do anything confusing to the nesting of
gtk_main() when config boxes are involved. Whether you're changing the
settings of one (or more than one) of your already-running sessions,
preparing to start up a new PuTTY connection, or both at once, we stay
in the same top-level instance of gtk_main() and all sessions' top-
level callbacks continue to run sensibly.
2017-11-26 11:58:02 +00:00
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#define MAY_REFER_TO_GTK_IN_HEADERS
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2003-03-29 19:52:50 +00:00
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#include "putty.h"
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2020-01-29 06:19:30 +00:00
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#include "ssh.h"
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2003-03-29 19:52:50 +00:00
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#include "storage.h"
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2015-08-22 13:07:02 +00:00
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#include "gtkcompat.h"
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2023-07-15 20:05:41 +00:00
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#ifndef NOT_X_WINDOWS
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#include <gdk/gdkx.h>
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#endif
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2005-02-06 15:52:00 +00:00
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/*
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2022-01-22 15:38:53 +00:00
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* Stubs to avoid pty.c needing to be linked in.
|
2005-02-06 15:52:00 +00:00
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|
*/
|
Convert a lot of 'int' variables to 'bool'.
My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
2018-11-02 19:23:19 +00:00
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const bool use_pty_argv = false;
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2019-09-08 19:29:00 +00:00
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char **pty_argv; /* never used */
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2016-03-23 22:13:30 +00:00
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char *pty_osx_envrestore_prefix;
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2005-02-06 15:52:00 +00:00
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2003-03-29 19:52:50 +00:00
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/*
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* Clean up and exit.
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*/
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void cleanup_exit(int code)
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{
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/*
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* Clean up.
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*/
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sk_cleanup();
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random_save_seed();
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exit(code);
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}
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2018-10-05 06:03:46 +00:00
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const struct BackendVtable *select_backend(Conf *conf)
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2003-03-29 19:52:50 +00:00
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{
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2018-10-05 06:03:46 +00:00
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const struct BackendVtable *vt =
|
2018-09-11 15:23:38 +00:00
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backend_vt_from_proto(conf_get_int(conf, CONF_protocol));
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assert(vt != NULL);
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return vt;
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2003-03-29 19:52:50 +00:00
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}
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|
|
|
|
|
Make the configuration dialog non-modal.
Now every call to do_config_box is replaced with a call to
create_config_box, which returns immediately having constructed the
new GTK window object, and is passed a callback function which it will
arrange to be called when the dialog terminates (whether by OK or by
Cancel). That callback is now what triggers the construction of a
session window after 'Open' is pressed in the initial config box, or
the actual mid-session reconfiguration action after 'Apply' is pressed
in a Change Settings box.
We were already prepared to ignore the re-selection of 'Change
Settings' from the context menu of a window that already had a Change
Settings box open (and not accidentally create a second config box for
the same window); but now we do slightly better, by finding the
existing config box and un-minimising and raising it, in case the user
had forgotten it was there.
That's a useful featurelet, but not the main purpose of this change.
The mani point, of course, is that now the multi-window GtkApplication
based front ends now don't do anything confusing to the nesting of
gtk_main() when config boxes are involved. Whether you're changing the
settings of one (or more than one) of your already-running sessions,
preparing to start up a new PuTTY connection, or both at once, we stay
in the same top-level instance of gtk_main() and all sessions' top-
level callbacks continue to run sensibly.
2017-11-26 11:58:02 +00:00
|
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|
void initial_config_box(Conf *conf, post_dialog_fn_t after, void *afterctx)
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2003-03-29 19:52:50 +00:00
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{
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Make dupcat() into a variadic macro.
Up until now, it's been a variadic _function_, whose argument list
consists of 'const char *' ASCIZ strings to concatenate, terminated by
one containing a null pointer. Now, that function is dupcat_fn(), and
it's wrapped by a C99 variadic _macro_ called dupcat(), which
automatically suffixes the null-pointer terminating argument.
This has three benefits. Firstly, it's just less effort at every call
site. Secondly, it protects against the risk of accidentally leaving
off the NULL, causing arbitrary words of stack memory to be
dereferenced as char pointers. And thirdly, it protects against the
more subtle risk of writing a bare 'NULL' as the terminating argument,
instead of casting it explicitly to a pointer. That last one is
necessary because C permits the macro NULL to expand to an integer
constant such as 0, so NULL by itself may not have pointer type, and
worse, it may not be marshalled in a variadic argument list in the
same way as a pointer. (For example, on a 64-bit machine it might only
occupy 32 bits. And yet, on another 64-bit platform, it might work
just fine, so that you don't notice the mistake!)
I was inspired to do this by happening to notice one of those bare
NULL terminators, and thinking I'd better check if there were any
more. Turned out there were quite a few. Now there are none.
2019-10-14 18:42:37 +00:00
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char *title = dupcat(appname, " Configuration");
|
2018-10-29 19:50:29 +00:00
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create_config_box(title, conf, false, 0, after, afterctx);
|
2008-06-15 13:26:08 +00:00
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sfree(title);
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2003-03-29 19:52:50 +00:00
|
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}
|
|
|
|
|
|
Convert a lot of 'int' variables to 'bool'.
My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
2018-11-02 19:23:19 +00:00
|
|
|
const bool use_event_log = true, new_session = true, saved_sessions = true;
|
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|
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const bool dup_check_launchable = true;
|
2003-04-09 18:46:45 +00:00
|
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|
|
2004-10-06 22:31:07 +00:00
|
|
|
/*
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|
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* X11-forwarding-related things suitable for Gtk app.
|
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|
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*/
|
|
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|
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char *platform_get_x_display(void) {
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|
|
|
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const char *display;
|
2023-07-15 20:05:41 +00:00
|
|
|
#ifndef NOT_X_WINDOWS
|
2004-10-06 22:31:07 +00:00
|
|
|
/* Try to take account of --display and what have you. */
|
2023-07-15 20:05:41 +00:00
|
|
|
if (!GDK_IS_X11_DISPLAY(gdk_display_get_default()) ||
|
|
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!(display = gdk_get_display()))
|
|
|
|
|
#endif
|
2019-09-08 19:29:00 +00:00
|
|
|
/* fall back to traditional method */
|
|
|
|
|
display = getenv("DISPLAY");
|
2004-10-06 22:31:07 +00:00
|
|
|
return dupstr(display);
|
|
|
|
|
}
|
|
|
|
|
|
Convert a lot of 'int' variables to 'bool'.
My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
2018-11-02 19:23:19 +00:00
|
|
|
const bool share_can_be_downstream = true;
|
|
|
|
|
const bool share_can_be_upstream = true;
|
2013-11-17 14:05:41 +00:00
|
|
|
|
2020-01-30 06:40:22 +00:00
|
|
|
const unsigned cmdline_tooltype =
|
|
|
|
|
TOOLTYPE_HOST_ARG |
|
|
|
|
|
TOOLTYPE_PORT_ARG |
|
|
|
|
|
TOOLTYPE_NO_VERBOSE_OPTION;
|
|
|
|
|
|
Convert a lot of 'int' variables to 'bool'.
My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
2018-11-02 19:23:19 +00:00
|
|
|
void setup(bool single)
|
2003-03-29 19:52:50 +00:00
|
|
|
{
|
|
|
|
|
sk_init();
|
Arm: turn on PSTATE.DIT if available and needed.
DIT, for 'Data-Independent Timing', is a bit you can set in the
processor state on sufficiently new Arm CPUs, which promises that a
long list of instructions will deliberately avoid varying their timing
based on the input register values. Just what you want for keeping
your constant-time crypto primitives constant-time.
As far as I'm aware, no CPU has _yet_ implemented any data-dependent
optimisations, so DIT is a safety precaution against them doing so in
future. It would be embarrassing to be caught without it if a future
CPU does do that, so we now turn on DIT in the PuTTY process state.
I've put a call to the new enable_dit() function at the start of every
main() and WinMain() belonging to a program that might do
cryptography (even testcrypt, in case someone uses it for something!),
and in case I missed one there, also added a second call at the first
moment that any cryptography-using part of the code looks as if it
might become active: when an instance of the SSH protocol object is
configured, when the system PRNG is initialised, and when selecting
any cryptographic authentication protocol in an HTTP or SOCKS proxy
connection. With any luck those precautions between them should ensure
it's on whenever we need it.
Arm's own recommendation is that you should carefully choose the
granularity at which you enable and disable DIT: there's a potential
time cost to turning it on and off (I'm not sure what, but plausibly
something of the order of a pipeline flush), so it's a performance hit
to do it _inside_ each individual crypto function, but if CPUs start
supporting significant data-dependent optimisation in future, then it
will also become a noticeable performance hit to just leave it on
across the whole process. So you'd like to do it somewhere in the
middle: for example, you might turn on DIT once around the whole
process of verifying and decrypting an SSH packet, instead of once for
decryption and once for MAC.
With all respect to that recommendation as a strategy for maximum
performance, I'm not following it here. I turn on DIT at the start of
the PuTTY process, and then leave it on. Rationale:
1. PuTTY is not otherwise a performance-critical application: it's
not likely to max out your CPU for any purpose _other_ than
cryptography. The most CPU-intensive non-cryptographic thing I can
imagine a PuTTY process doing is the complicated computation of
font rendering in the terminal, and that will normally be cached
(you don't recompute each glyph from its outline and hints for
every time you display it).
2. I think a bigger risk lies in accidental side channels from having
DIT turned off when it should have been on. I can imagine lots of
causes for that. Missing a crypto operation in some unswept corner
of the code; confusing control flow (like my coroutine macros)
jumping with DIT clear into the middle of a region of code that
expected DIT to have been set at the beginning; having a reference
counter of DIT requests and getting it out of sync.
In a more sophisticated programming language, it might be possible to
avoid the risk in #2 by cleverness with the type system. For example,
in Rust, you could have a zero-sized type that acts as a proof token
for DIT being enabled (it would be constructed by a function that also
sets DIT, have a Drop implementation that clears DIT, and be !Send so
you couldn't use it in a thread other than the one where DIT was set),
and then you could require all the actual crypto functions to take a
DitToken as an extra parameter, at zero runtime cost. Then "oops I
forgot to set DIT around this piece of crypto" would become a compile
error. Even so, you'd have to take some care with coroutine-structured
code (what happens if a Rust async function yields while holding a DIT
token?) and with nesting (if you have two DIT tokens, you don't want
dropping the inner one to clear DIT while the outer one is still there
to wrongly convince callees that it's set). Maybe in Rust you could
get this all to work reliably. But not in C!
DIT is an optional feature of the Arm architecture, so we must first
test to see if it's supported. This is done the same way as we already
do for the various Arm crypto accelerators: on ELF-based systems,
check the appropriate bit in the 'hwcap' words in the ELF aux vector;
on Mac, look for an appropriate sysctl flag.
On Windows I don't know of a way to query the DIT feature, _or_ of a
way to write the necessary enabling instruction in an MSVC-compatible
way. I've _heard_ that it might not be necessary, because Windows
might just turn on DIT unconditionally and leave it on, in an even
more extreme version of my own strategy. I don't have a source for
that - I heard it by word of mouth - but I _hope_ it's true, because
that would suit me very well! Certainly I can't write code to enable
DIT without knowing (a) how to do it, (b) how to know if it's safe.
Nonetheless, I've put the enable_dit() call in all the right places in
the Windows main programs as well as the Unix and cross-platform code,
so that if I later find out that I _can_ put in an explicit enable of
DIT in some way, I'll only have to arrange to set HAVE_ARM_DIT and
compile the enable_dit() function appropriately.
2024-12-19 08:47:08 +00:00
|
|
|
enable_dit();
|
2020-02-02 10:00:42 +00:00
|
|
|
settings_set_default_protocol(be_default_protocol);
|
2003-03-29 19:52:50 +00:00
|
|
|
/* Find the appropriate default port. */
|
|
|
|
|
{
|
2018-10-05 06:03:46 +00:00
|
|
|
const struct BackendVtable *vt =
|
2020-02-02 10:00:42 +00:00
|
|
|
backend_vt_from_proto(be_default_protocol);
|
|
|
|
|
settings_set_default_port(0); /* illegal */
|
2018-09-11 15:23:38 +00:00
|
|
|
if (vt)
|
2020-02-02 10:00:42 +00:00
|
|
|
settings_set_default_port(vt->default_port);
|
2003-03-29 19:52:50 +00:00
|
|
|
}
|
|
|
|
|
}
|