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.
This is another cleanup I felt a need for while I was doing
boolification. If you define a function or variable in one .c file and
declare it extern in another, then nothing will check you haven't got
the types of the two declarations mismatched - so when you're
_changing_ the type, it's a pain to make sure you've caught all the
copies of it.
It's better to put all those extern declarations in header files, so
that the declaration in the header is also in scope for the
definition. Then the compiler will complain if they don't match, which
is what I want.
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.
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.
I had set up an event object for signalling incoming connections to
the named pipe, and then called handle_add_foreign_event to get that
event object watched for connections - but when I closed down the
listening pipe, I deleted the event object without also cancelling
that foreign-event handle, so that winhandl.c would potentially call
the callback for a destroyed object.
Daniel Meidlinger reports that at least one Windows machine which is
not obviously otherwise misconfigured will respond to our
SetEntriesInAcl call with odd errors like ERROR_NONE_MAPPED or
ERROR_TRUSTED_RELATIONSHIP_FAILURE. This is apparently to do with
failure to convert the names "EVERYONE" and "CURRENT_USER" used in the
ACL specification to SIDs. (Or perhaps only one of them is the problem
- I didn't investigate in that direction.)
If we instead construct a fully SID-based ACL, using the well-known
world SID in place of EVERYONE and calling our existing get_user_sid
routine in place of CURRENT_USER, he reports that the problem goes
away, so let's do that instead.
While I'm here, I've slightly simplified the function prototype of
make_private_security_descriptor(), by turning 'networksid' into an
internal static that we can reuse in subsequent calls once we've set
it up. (Mostly because I didn't fancy adding another two pointless
parameters at every call site for the two new SIDs.)
[originally from svn r10096]
The basic strategy is described at the top of the new source file
sshshare.c. In very brief: an 'upstream' PuTTY opens a Unix-domain
socket or Windows named pipe, and listens for connections from other
PuTTYs wanting to run sessions on the same server. The protocol spoken
down that socket/pipe is essentially the bare ssh-connection protocol,
using a trivial binary packet protocol with no encryption, and the
upstream has to do some fiddly transformations that I've been
referring to as 'channel-number NAT' to avoid resource clashes between
the sessions it's managing.
This is quite different from OpenSSH's approach of using the Unix-
domain socket as a means of passing file descriptors around; the main
reason for that is that fd-passing is Unix-specific but this system
has to work on Windows too. However, there are additional advantages,
such as making it easy for each downstream PuTTY to run its own
independent set of port and X11 forwardings (though the method for
making the latter work is quite painful).
Sharing is off by default, but configuration is intended to be very
easy in the normal case - just tick one box in the SSH config panel
and everything else happens automatically.
[originally from svn r10083]
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]
This commit adds two new support modules, winnpc.c and winnps.c, which
deal respectively with being a client and server of a Windows named
pipe (which, in spite of what Unix programmers will infer from that
name, is actually closer to Windows's analogue of a Unix-domain
socket). Each one provides a fully featured Socket wrapper around the
hairy Windows named pipe API, so that the rest of the code base should
be able to use these interchangeably with ordinary sockets and hardly
notice the difference.
As part of this work, I've introduced a mechanism in winhandl.c to
permit it to store handles of event objects on behalf of other Windows
support modules and deal with passing them to applications' main event
loops as necessary. (Perhaps it would have been cleaner to split
winhandl.c into an event-object tracking layer analogous to uxsel, and
the handle management which is winhandl.c's proper job, but this is
less disruptive for the present.)
[originally from svn r10069]
Simon Tatham