This is a sweeping change applied across the whole code base by a spot
of Emacs Lisp. Now, everywhere I declare a vtable filled with function
pointers (and the occasional const data member), all the members of
the vtable structure are initialised by name using the '.fieldname =
value' syntax introduced in C99.
We were already using this syntax for a handful of things in the new
key-generation progress report system, so it's not new to the code
base as a whole.
The advantage is that now, when a vtable only declares a subset of the
available fields, I can initialise the rest to NULL or zero just by
leaving them out. This is most dramatic in a couple of the outlying
vtables in things like psocks (which has a ConnectionLayerVtable
containing only one non-NULL method), but less dramatically, it means
that the new 'flags' field in BackendVtable can be completely left out
of every backend definition except for the SUPDUP one which defines it
to a nonzero value. Similarly, the test_for_upstream method only used
by SSH doesn't have to be mentioned in the rest of the backends;
network Plugs for listening sockets don't have to explicitly null out
'receive' and 'sent', and vice versa for 'accepting', and so on.
While I'm at it, I've normalised the declarations so they don't use
the unnecessarily verbose 'struct' keyword. Also a handful of them
weren't const; now they are.
The number of people has been steadily increasing who read our source
code with an editor that thinks tab stops are 4 spaces apart, as
opposed to the traditional tty-derived 8 that the PuTTY code expects.
So I've been wondering for ages about just fixing it, and switching to
a spaces-only policy throughout the code. And I recently found out
about 'git blame -w', which should make this change not too disruptive
for the purposes of source-control archaeology; so perhaps now is the
time.
While I'm at it, I've also taken the opportunity to remove all the
trailing spaces from source lines (on the basis that git dislikes
them, and is the only thing that seems to have a strong opinion one
way or the other).
Apologies to anyone downstream of this code who has complicated patch
sets to rebase past this change. I don't intend it to be needed again.
I've only just noticed that it doesn't do anything at all!
Almost every implementation of the Socket vtable provides a flush()
method which does nothing, optionally with a comment explaining why
it's OK to do nothing. The sole exception is the wrapper Proxy_Socket,
which implements the method during its setup phase by setting a
pending_flush flag, so that when its sub-socket is later created, it
can call sk_flush on that. But since the sub-socket's sk_flush will do
nothing, even that is completely pointless!
Source control history says that sk_flush was introduced by Dave
Hinton in 2001 (commit 7b0e08270), who was going to use it for some
purpose involving the SSL Telnet support he was working on at the
time. That SSL support was never finished, and its vestigial
declarations in network.h were removed in 2015 (commit 42334b65b). So
sk_flush is just another vestige of that abandoned work, which I
should have removed in the latter commit but overlooked.
Having explicitly _stated_ in commit 4dcc0fddf the principle that if
you ever queue a toplevel callback on a freeable object then you
should also call delete_callbacks_for_context on that object before
freeing it, I realised I'd never actually gone through and checked
methodically at every call site of queue_toplevel_callback. So I did,
and naturally, I found several missing ones.
If a proxy command jabbers on standard error in a way that doesn't
involve any newline characters, we now won't keep buffering data for
ever.
(Not that I've heard of it happening, but I noticed the theoretical
possibility on the way past in a recent cleanup pass.)
Now that all the call sites are expecting a size_t instead of an int
length field, it's no longer particularly difficult to make it
actually return the pointer,length pair in the form of a ptrlen.
It would be nice to say that simplifies call sites because those
ptrlens can all be passed straight along to other ptrlen-consuming
functions. Actually almost none of the call sites are like that _yet_,
but this makes it possible to move them in that direction in future
(as part of my general aim to migrate ptrlen-wards as much as I can).
But also it's just nicer to keep the pointer and length together in
one variable, and not have to declare them both in advance with two
extra lines of boilerplate.
This is a general cleanup which has been overdue for some time: lots
of length fields are now the machine word type rather than the (in
practice) fixed 'int'.
Now we pass an error code in a separate dedicated parameter, instead
of overloading the length parameter so that a negative value means an
error code. This enables length to become unsigned without causing
trouble.
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'!
This commit includes <stdbool.h> from defs.h and deletes my
traditional definitions of TRUE and FALSE, but other than that, it's a
100% mechanical search-and-replace transforming all uses of TRUE and
FALSE into the C99-standardised lowercase spellings.
No actual types are changed in this commit; that will come next. This
is just getting the noise out of the way, so that subsequent commits
can have a higher proportion of signal.
Previously, it returned a human-readable string suitable for log
files, which tried to say something useful about the remote end of a
socket. Now it returns a whole SocketPeerInfo structure, of which that
human-friendly log string is just one field, but also some of the same
information - remote IP address and port, in particular - is provided
in machine-readable form where it's available.
Ian Jackson points out that the Linux kernel has a macro of this name
with the same purpose, and suggests that it's a good idea to use the
same name as they do, so that at least some people reading one code
base might recognise it from the other.
I never really thought very hard about what order FROMFIELD's
parameters should go in, and therefore I'm pleasantly surprised to
find that my order agrees with the kernel's, so I don't have to
permute every call site as part of making this change :-)
I don't actually know why this was ever here; it appeared in the very
first commit that invented Plug in the first place (7b0e08270) without
explanation. Perhaps Dave's original idea was that sometimes you'd
need those macros _not_ to be defined so that the same names could be
reused as the methods for a particular Plug instance? But I don't
think that ever actually happened, and the code base builds just fine
with those macros defined unconditionally just like all the other sets
of method macros we now have, so let's get rid of this piece of cruft
that was apparently unnecessary all along.
I think that means that _every_ one of my traitoids is now a struct
containing a vtable pointer as one of its fields (albeit sometimes the
only field), and never just a bare pointer.
All the main backend structures - Ssh, Telnet, Pty, Serial etc - now
describe structure types themselves rather than pointers to them. The
same goes for the codebase-wide trait types Socket and Plug, and the
supporting types SockAddr and Pinger.
All those things that were typedefed as pointers are older types; the
newer ones have the explicit * at the point of use, because that's
what I now seem to be preferring. But whichever one of those is
better, inconsistently using a mixture of the two styles is worse, so
let's make everything consistent.
A few types are still implicitly pointers, such as Bignum and some of
the GSSAPI types; generally this is either because they have to be
void *, or because they're typedefed differently on different
platforms and aren't always pointers at all. Can't be helped. But I've
got rid of the main ones, at least.
Now I've got FROMFIELD, I can rework it so that structures providing
an implementation of the Socket or Plug trait no longer have to have
the vtable pointer as the very first thing in the structure. In
particular, this means that the ProxySocket structure can now directly
implement _both_ the Socket and Plug traits, which is always
_logically_ how it's worked, but previously it had to be implemented
via two separate structs linked to each other.
This is a cleanup I started to notice a need for during the BinarySink
work. It removes a lot of faffing about casting things to char * or
unsigned char * so that some API will accept them, even though lots of
such APIs really take a plain 'block of raw binary data' argument and
don't care what C thinks the signedness of that data might be - they
may well reinterpret it back and forth internally.
So I've tried to arrange for all the function call APIs that ought to
have a void * (or const void *) to have one, and those that need to do
pointer arithmetic on the parameter internally can cast it back at the
top of the function. That saves endless ad-hoc casts at the call
sites.
These include an unused variable left over from the command-line
refactoring; an explicit referencing of the module handle for
sspicli.dll which we really do deliberately load and then don't
(directly) use; a missing pointer-type cast in the Windows handle
socket code; and two 32/64 bit integer size mismatches in the types of
functions I was importing from system API DLLs.
The last of those are a bit worrying, and suggest to me that after
going to all that trouble to add type-checking of those runtime
imports in commit 49fb598b0, I might have only checked the resulting
compiler output in a 32-bit build and not a 64-bit one. Oops!
Like every other toolchain I've tried, my Coverity scanning build has
its share of random objections to parts of my Windows API type-
checking system. I do wonder if that bright idea was worth the hassle
- but it would probably cost all the annoyance all over again to back
out now...
plug_receive() and plug_closing() return 0 or 1 depending on whether
they think the main connection has closed. It is not appropriate, as
handle_gotdata and handle_socket_unfreeze did, to treat them as
returning a backlog. In fact, plugs are unusual in PuTTY in not
reporting a backlog, but just calling into the socket to freeze and
unfreeze it as required.
This gives me an extra safety-check against having mistyped one of the
function prototypes that we load at run time from DLLs: we verify that
the typedef we defined based on the prototype in our source code
matches the type of the real function as declared in the Windows
headers.
This was an idea I had while adding a pile of further functions using
this mechanism. It didn't catch any errors (either in the new
functions or in the existing collection), but that's no reason not to
keep it anyway now that I've thought of it!
In VS2015, this automated type-check works for most functions, but a
couple manage to break it. SetCurrentProcessExplicitAppUserModelID in
winjump.c can't be type-checked, because including <shobjidl.h> where
that function is declared would also bring in a load of other stuff
that conflicts with the painful manual COM declarations in winjump.c.
(That stuff could probably be removed now we're on an up-to-date
Visual Studio, on the other hand, but that's a separate chore.) And
gai_strerror, used in winnet.c, does _have_ an implementation in a
DLL, but the header files like to provide an inline version with a
different calling convention, which defeats this error-checking trick.
And in the older VS2003 that we still precautionarily build with,
several more type-checks have to be #ifdeffed out because the
functions they check against just aren't there at all.
In the sentdata callback function given to handle_output_new, the
'new_backlog' parameter can be negative, and if so, it represents a
Windows error code and not a backlog size at all. handle_sentdata was
not checking for this before passing it on to plug_sent.
When a handle socket is in THAWING state and handle_socket_unfreeze is
gradually passing the backlogged data on to the plug, the plug might
suddenly turn round and close the socket in the course of handling
plug_receive(), which means that handle_socket_unfreeze had better be
careful not to have had everything vanish out from under it when that
call returns. To solve this, I've added a 'deferred close' flag which
handle_socket_unfreeze can set around its call to plug_receive, and
handle_socket_close will detect that and not actually free the socket,
instead leaving that for handle_socket_unfreeze to do under its own
control.
Firstly, I had asserted that data would never arrive on a handle
socket in state FREEZING, which is just an error, because FREEZING is
precisely the state of not being quite frozen _yet_ because one last
read is still expected to arrive from the winhandl.c reading subthread
which it's too late to cancel. I meant to assert that it wasn't
FROZEN.
Secondly, when the handle socket was in state FREEZING, I failed to
actually _set_ it to FROZEN.
And thirdly, when the handle socket starts thawing again (i.e. there's
now outgoing buffer space so we can start sending our backlogged
data), I forgot to ever call bufchain_consume, so that the same block
of data would get sent repeatedly.
I can only assume that nothing I've ever done has actually exercised
this code!
On both Unix and Windows, we now redirect the local proxy command's
standard error into a third pipe; data received from that pipe is
broken up at newlines and logged in the Event Log. So if the proxy
command emits any error messages in the course of failing to connect
to something, you now have a fighting chance of finding out what went
wrong.
This feature is disabled in command-line tools like PSFTP and Plink,
on the basis that in that situation it seems more likely that the user
would expect standard-error output to go to the ordinary standard
error in the ordinary way. Only GUI PuTTY catches it and logs it like
this, because it either doesn't have a standard error at all (on
Windows) or is likely to be pointing it at some completely unhelpful
session log file (under X).
When anyone connects to a PuTTY tool's listening socket - whether it's
a user of a local->remote port forwarding, a connection-sharing
downstream or a client of Pageant - we'd like to log as much
information as we can find out about where the connection came from.
To that end, I've implemented a function sk_peer_info() in the socket
abstraction, which returns a freeform text string as best it can (or
NULL, if it can't get anything at all) describing the thing at the
other end of the connection. For TCP connections, this is done using
getpeername() to get an IP address and port in the obvious way; for
Unix-domain sockets, we attempt SO_PEERCRED (conditionalised on some
moderately hairy autoconfery) to get the pid and owner of the peer. I
haven't implemented anything for Windows named pipes, but I will if I
hear of anything useful.
It was only actually used in X11 and port forwarding, to find internal
state structures given only the Socket that ssh.c held. So now that
that lookup has been reworked to be the sensible way round,
private_ptr is no longer used for anything and can be removed.
[originally from svn r10075]
That's been a FIXME in the code for ages, because it's difficult to
get winhandl.c to stop an already-started read from a handle (since
the read is a blocking system call running in a separate thread). But
I now realise it isn't absolutely necessary to do so - you can just
buffer one lot of data from winhandl and _then_ tell it to stop.
[originally from svn r10067]
It's now kept in a separate module, where it can be reused
conveniently for other kinds of Windows HANDLE that I want to wrap in
the PuTTY Socket abstraction - for example, the named pipes that I
shortly plan to use for the Windows side of connection-sharing IPC.
[originally from svn r10066]
