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putty-source/unix/local-proxy.c

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/*
* uxproxy.c: Unix implementation of platform_new_connection(),
* supporting an OpenSSH-like proxy command.
*/
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include "tree234.h"
#include "putty.h"
#include "network.h"
#include "proxy.h"
Socket *platform_new_connection(SockAddr *addr, const char *hostname,
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
int port, bool privport,
bool oobinline, bool nodelay, bool keepalive,
Plug *plug, Conf *conf)
{
char *cmd;
int to_cmd_pipe[2], from_cmd_pipe[2], cmd_err_pipe[2], pid, proxytype;
int infd, outfd, inerrfd;
proxytype = conf_get_int(conf, CONF_proxy_type);
if (proxytype != PROXY_CMD && proxytype != PROXY_FUZZ)
return NULL;
if (proxytype == PROXY_CMD) {
cmd = format_telnet_command(addr, port, conf);
{
char *logmsg = dupprintf("Starting local proxy command: %s", cmd);
plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
sfree(logmsg);
}
/*
* Create the pipes to the proxy command, and spawn the proxy
* command process.
*/
if (pipe(to_cmd_pipe) < 0 ||
pipe(from_cmd_pipe) < 0 ||
Remove FLAG_STDERR completely. Originally, it controlled whether ssh.c should send terminal messages (such as login and password prompts) to terminal.c or to stderr. But we've had the from_backend() abstraction for ages now, which even has an existing flag to indicate that the data is stderr rather than stdout data; applications which set FLAG_STDERR are precisely those that link against uxcons or wincons, so from_backend will do the expected thing anyway with data sent to it with that flag set. So there's no reason ssh.c can't just unconditionally pass everything through that, and remove the special case. FLAG_STDERR was also used by winproxy and uxproxy to decide whether to capture standard error from a local proxy command, or whether to let the proxy command send its diagnostics directly to the usual standard error. On reflection, I think it's better to unconditionally capture the proxy's stderr, for three reasons. Firstly, it means proxy diagnostics are prefixed with 'proxy:' so that you can tell them apart from any other stderr spew (which used to be particularly confusing if both the main application and the proxy command were instances of Plink); secondly, proxy diagnostics are now reliably copied to packet log files along with all the other Event Log entries, even by command-line tools; and thirdly, this means the option to suppress proxy command diagnostics after the main session starts will actually _work_ in the command-line tools, which it previously couldn't. A more minor structure change is that copying of Event Log messages to stderr in verbose mode is now done by wincons/uxcons, instead of centrally in logging.c (since logging.c can now no longer check FLAG_STDERR to decide whether to do it). The total amount of code to do this is considerably smaller than the defensive-sounding comment in logevent.c explaining why I did it the other way instead :-)
2018-09-21 15:15:49 +00:00
pipe(cmd_err_pipe) < 0) {
sfree(cmd);
return new_error_socket_fmt(plug, "pipe: %s", strerror(errno));
}
cloexec(to_cmd_pipe[1]);
cloexec(from_cmd_pipe[0]);
Remove FLAG_STDERR completely. Originally, it controlled whether ssh.c should send terminal messages (such as login and password prompts) to terminal.c or to stderr. But we've had the from_backend() abstraction for ages now, which even has an existing flag to indicate that the data is stderr rather than stdout data; applications which set FLAG_STDERR are precisely those that link against uxcons or wincons, so from_backend will do the expected thing anyway with data sent to it with that flag set. So there's no reason ssh.c can't just unconditionally pass everything through that, and remove the special case. FLAG_STDERR was also used by winproxy and uxproxy to decide whether to capture standard error from a local proxy command, or whether to let the proxy command send its diagnostics directly to the usual standard error. On reflection, I think it's better to unconditionally capture the proxy's stderr, for three reasons. Firstly, it means proxy diagnostics are prefixed with 'proxy:' so that you can tell them apart from any other stderr spew (which used to be particularly confusing if both the main application and the proxy command were instances of Plink); secondly, proxy diagnostics are now reliably copied to packet log files along with all the other Event Log entries, even by command-line tools; and thirdly, this means the option to suppress proxy command diagnostics after the main session starts will actually _work_ in the command-line tools, which it previously couldn't. A more minor structure change is that copying of Event Log messages to stderr in verbose mode is now done by wincons/uxcons, instead of centrally in logging.c (since logging.c can now no longer check FLAG_STDERR to decide whether to do it). The total amount of code to do this is considerably smaller than the defensive-sounding comment in logevent.c explaining why I did it the other way instead :-)
2018-09-21 15:15:49 +00:00
cloexec(cmd_err_pipe[0]);
pid = fork();
if (pid == 0) {
close(0);
close(1);
dup2(to_cmd_pipe[0], 0);
dup2(from_cmd_pipe[1], 1);
close(to_cmd_pipe[0]);
close(from_cmd_pipe[1]);
Remove FLAG_STDERR completely. Originally, it controlled whether ssh.c should send terminal messages (such as login and password prompts) to terminal.c or to stderr. But we've had the from_backend() abstraction for ages now, which even has an existing flag to indicate that the data is stderr rather than stdout data; applications which set FLAG_STDERR are precisely those that link against uxcons or wincons, so from_backend will do the expected thing anyway with data sent to it with that flag set. So there's no reason ssh.c can't just unconditionally pass everything through that, and remove the special case. FLAG_STDERR was also used by winproxy and uxproxy to decide whether to capture standard error from a local proxy command, or whether to let the proxy command send its diagnostics directly to the usual standard error. On reflection, I think it's better to unconditionally capture the proxy's stderr, for three reasons. Firstly, it means proxy diagnostics are prefixed with 'proxy:' so that you can tell them apart from any other stderr spew (which used to be particularly confusing if both the main application and the proxy command were instances of Plink); secondly, proxy diagnostics are now reliably copied to packet log files along with all the other Event Log entries, even by command-line tools; and thirdly, this means the option to suppress proxy command diagnostics after the main session starts will actually _work_ in the command-line tools, which it previously couldn't. A more minor structure change is that copying of Event Log messages to stderr in verbose mode is now done by wincons/uxcons, instead of centrally in logging.c (since logging.c can now no longer check FLAG_STDERR to decide whether to do it). The total amount of code to do this is considerably smaller than the defensive-sounding comment in logevent.c explaining why I did it the other way instead :-)
2018-09-21 15:15:49 +00:00
dup2(cmd_err_pipe[1], 2);
noncloexec(0);
noncloexec(1);
execl("/bin/sh", "sh", "-c", cmd, (void *)NULL);
_exit(255);
}
sfree(cmd);
if (pid < 0)
return new_error_socket_fmt(plug, "fork: %s", strerror(errno));
close(to_cmd_pipe[0]);
close(from_cmd_pipe[1]);
Remove FLAG_STDERR completely. Originally, it controlled whether ssh.c should send terminal messages (such as login and password prompts) to terminal.c or to stderr. But we've had the from_backend() abstraction for ages now, which even has an existing flag to indicate that the data is stderr rather than stdout data; applications which set FLAG_STDERR are precisely those that link against uxcons or wincons, so from_backend will do the expected thing anyway with data sent to it with that flag set. So there's no reason ssh.c can't just unconditionally pass everything through that, and remove the special case. FLAG_STDERR was also used by winproxy and uxproxy to decide whether to capture standard error from a local proxy command, or whether to let the proxy command send its diagnostics directly to the usual standard error. On reflection, I think it's better to unconditionally capture the proxy's stderr, for three reasons. Firstly, it means proxy diagnostics are prefixed with 'proxy:' so that you can tell them apart from any other stderr spew (which used to be particularly confusing if both the main application and the proxy command were instances of Plink); secondly, proxy diagnostics are now reliably copied to packet log files along with all the other Event Log entries, even by command-line tools; and thirdly, this means the option to suppress proxy command diagnostics after the main session starts will actually _work_ in the command-line tools, which it previously couldn't. A more minor structure change is that copying of Event Log messages to stderr in verbose mode is now done by wincons/uxcons, instead of centrally in logging.c (since logging.c can now no longer check FLAG_STDERR to decide whether to do it). The total amount of code to do this is considerably smaller than the defensive-sounding comment in logevent.c explaining why I did it the other way instead :-)
2018-09-21 15:15:49 +00:00
close(cmd_err_pipe[1]);
outfd = to_cmd_pipe[1];
infd = from_cmd_pipe[0];
inerrfd = cmd_err_pipe[0];
} else {
cmd = format_telnet_command(addr, port, conf);
outfd = open("/dev/null", O_WRONLY);
if (outfd == -1) {
sfree(cmd);
return new_error_socket_fmt(
plug, "/dev/null: %s", strerror(errno));
}
infd = open(cmd, O_RDONLY);
if (infd == -1) {
Socket *toret = new_error_socket_fmt(
plug, "%s: %s", cmd, strerror(errno));
sfree(cmd);
close(outfd);
return toret;
}
sfree(cmd);
inerrfd = -1;
}
return make_fd_socket(infd, outfd, inerrfd, addr, port, plug);
}