зеркало из https://github.com/github/putty.git
7 Коммитов
| Автор | SHA1 | Сообщение | Дата |
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Simon Tatham
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e08641c912 |
Start using C99 variadic macros.
In the past, I've had a lot of macros which you call with double
parentheses, along the lines of debug(("format string", params)), so
that the inner parens protect the commas and permit the macro to treat
the whole printf-style argument list as one macro argument.
That's all very well, but it's a bit inconvenient (it doesn't leave
you any way to implement such a macro by prepending another argument
to the list), and now this code base's rules allow C99isms, I can
switch all those macros to using a single pair of parens, using the
C99 ability to say '...' in the parameter list of the #define and get
at the corresponding suffix of the arguments as __VA_ARGS__.
So I'm doing it. I've made the following printf-style macros variadic:
bpp_logevent, ppl_logevent, ppl_printf and debug.
While I'm here, I've also fixed up a collection of conditioned-out
calls to debug() in the Windows front end which were clearly expecting
a macro with a different calling syntax, because they had an integer
parameter first. If I ever have a need to condition those back in,
they should actually work now.
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Simon Tatham
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3214563d8e |
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'! |
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Simon Tatham
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a6f1709c2f |
Adopt C99 <stdbool.h>'s true/false.
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. |
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Simon Tatham
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f789251ee4 |
Fix a couple of benign compile warnings.
A function containing assert(FALSE && "Should never be called") doesn't _really_ need to return a value, but it makes compilers happier if it pretends to. |
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Simon Tatham
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1d323d5c80 |
Add an actual SSH server program.
This server is NOT SECURE! If anyone is reading this commit message, DO NOT DEPLOY IT IN A HOSTILE-FACING ENVIRONMENT! Its purpose is to speak the server end of everything PuTTY speaks on the client side, so that I can test that I haven't broken PuTTY when I reorganise its code, even things like RSA key exchange or chained auth methods which it's hard to find a server that speaks at all. (For this reason, it's declared with [UT] in the Recipe file, so that it falls into the same category as programs like testbn, which won't be installed by 'make install'.) Working title is 'Uppity', partly for 'Universal PuTTY Protocol Interaction Test Yoke', but mostly because it looks quite like the word 'PuTTY' with part of it reversed. (Apparently 'test yoke' is a very rarely used term meaning something not altogether unlike 'test harness', which is a bit of a stretch, but it'll do.) It doesn't actually _support_ everything I want yet. At the moment, it's a proof of concept only. But it has most of the machinery present, and the parts it's missing - such as chained auth methods - should be easy enough to add because I've built in the required flexibility, in the form of an AuthPolicy object which can request them if it wants to. However, the current AuthPolicy object is entirely trivial, and will let in any user with the password "weasel". (Another way in which this is not a production-ready server is that it also has no interaction with the OS's authentication system. In particular, it will not only let in any user with the same password, but it won't even change uid - it will open shells and forwardings under whatever user id you started it up as.) Currently, the program can only speak the SSH protocol on its standard I/O channels (using the new FdSocket facility), so if you want it to listen on a network port, you'll have to run it from some kind of separate listening program similar to inetd. For my own tests, I'm not even doing that: I'm just having PuTTY spawn it as a local proxy process, which also conveniently eliminates the risk of anyone hostile connecting to it. The bulk of the actual code reorganisation is already done by previous commits, so this change is _mostly_ just dropping in a new set of server-specific source files alongside the client-specific ones I created recently. The remaining changes in the shared SSH code are numerous, but all minor: - a few extra parameters to BPP and PPL constructors (e.g. 'are you in server mode?'), and pass both sets of SSH-1 protocol flags from the login to the connection layer - in server mode, unconditionally send our version string _before_ waiting for the remote one - a new hook in the SSH-1 BPP to handle enabling compression in server mode, where the message exchange works the other way round - new code in the SSH-2 BPP to do _deferred_ compression the other way round (the non-deferred version is still nicely symmetric) - in the SSH-2 transport layer, some adjustments to do key derivation either way round (swapping round the identifying letters in the various hash preimages, and making sure to list the KEXINITs in the right order) - also in the SSH-2 transport layer, an if statement that controls whether we send SERVICE_REQUEST and wait for SERVICE_ACCEPT, or vice versa - new ConnectionLayer methods for opening outgoing channels for X and agent forwardings - new functions in portfwd.c to establish listening sockets suitable for remote-to-local port forwarding (i.e. not under the direction of a Conf the way it's done on the client side). |
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Simon Tatham
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9fe719f47d |
Server prep: parse a lot of new channel requests.
ssh2connection.c now knows how to unmarshal the message formats for all the channel requests we'll need to handle when we're the server and a client sends them. Each one is translated into a call to a new method in the Channel vtable, which is implemented by a trivial 'always fail' routine in every channel type we know about so far. |
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Simon Tatham
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b94c6a7e38 |
Move client-specific SSH code into new files.
This is a major code reorganisation in preparation for making this code base into one that can build an SSH server as well as a client. (Mostly for purposes of using the server as a regression test suite for the client, though I have some other possible uses in mind too. However, it's currently no part of my plan to harden the server to the point where it can sensibly be deployed in a hostile environment.) In this preparatory commit, I've broken up the SSH-2 transport and connection layers, and the SSH-1 connection layer, into multiple source files, with each layer having its own header file containing the shared type definitions. In each case, the new source file contains code that's specific to the client side of the protocol, so that a new file can be swapped in in its place when building the server. Mostly this is just a straightforward moving of code without changing it very much, but there are a couple of actual changes in the process: The parsing of SSH-2 global-request and channel open-messages is now done by a new pair of functions in the client module. For channel opens, I've invented a new union data type to be the return value from that function, representing either failure (plus error message), success (plus Channel instance to manage the new channel), or an instruction to hand the channel over to a sharing downstream (plus a pointer to the downstream in question). Also, the tree234 of remote port forwardings in ssh2connection is now initialised on first use by the client-specific code, so that's where its compare function lives. The shared ssh2connection_free() still takes responsibility for freeing it, but now has to check if it's non-null first. The outer shell of the ssh2_lportfwd_open method, for making a local-to-remote port forwarding, is still centralised in ssh2connection.c, but the part of it that actually constructs the outgoing channel-open message has moved into the client code, because that will have to change depending on whether the channel-open has to have type direct-tcpip or forwarded-tcpip. In the SSH-1 connection layer, half the filter_queue method has moved out into the new client-specific code, but not all of it - bidirectional channel maintenance messages are still handled centrally. One exception is SSH_MSG_PORT_OPEN, which can be sent in both directions, but with subtly different semantics - from server to client, it's referring to a previously established remote forwarding (and must be rejected if there isn't one that matches it), but from client to server it's just a "direct-tcpip" request with no prior context. So that one is in the client-specific module, and when I add the server code it will have its own different handler. |