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Add a warning when Sequel Pro was launched from Terminal and a SSH co…

…nnection is made
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dmoagx committed Jan 28, 2017
1 parent ed51940 commit 325b447afff5bb1ae4fa898f495a0f78d268e866
Showing with 46 additions and 1 deletion.
  1. +46 −1 Source/SPSSHTunnel.m
@@ -383,6 +383,7 @@ - (void)launchTask:(id) dummy
} else {
TA(@"-L", ([NSString stringWithFormat:@"%ld:%@:%ld", (long)localPort, remoteHost, (long)remotePort]));
}
#undef TA

[task setArguments:taskArguments];

@@ -414,10 +415,54 @@ - (void)launchTask:(id) dummy
[task setStandardError:standardError];
[[ NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(standardErrorHandler:)
name:@"NSFileHandleDataAvailableNotification"
name:NSFileHandleDataAvailableNotification
object:[standardError fileHandleForReading]];
[[standardError fileHandleForReading] waitForDataInBackgroundAndNotify];

{
static BOOL hasCheckedTTY = NO;
if(!hasCheckedTTY) {
int fd = open("/dev/tty", O_RDWR);
if(fd >= 0) {
close(fd);
fprintf(stderr, (
"!!!\n"
"!!! You are running Sequel Pro from a TTY.\n"
"!!! Any SSH connections that require user input (e.g. a password/passphrase) will fail\n"
"!!! and appear stalled indefinitely.\n"
"!!! Sorry!\n"
"!!!\n"
));
fflush(stderr);
// Explanation:
// OpenSSH by default requests passwords AND yes/no questions directly from the TTY,
// if it is part of a session group that has a controlling terminal (which is the case for
// processes created by Terminal.app).
//
// But this won't work, because only the foreground process group can read from /dev/tty and
// NSTask will create a new (background) process group for OpenSSH on launch.
// Side note: The internal method called from -[NSTask launch]
// -[NSConcreteTask launchWithDictionary:] accepts key @"_NSTaskNoNewProcessGroup" to skip that.
//
// Now, there are two preconditions for OpenSSH to use our SSH_ASKPASS utility instead:
// 1) The "DISPLAY" envvar has to be set
// 2) There must be no controlling terminal (ie. open("/dev/tty") fails)
// (See readpass.c#read_passphrase() in OpenSSH for the relevant code)
//
// -[NSTask launch] internally uses posix_spawn() and according to its documentation
// "The new process also inherits the following attributes from the calling
// process: [...] control terminal [...]"
// So if we wanted to avoid that, we would have to reimplement the whole NSTask class
// and use fork()+exec*()+setsid() instead (or use GNUStep's NSTask which already does this).
//
// We could also do ioctl(fd, TIOCNOTTY, 0); before launching the child process, but
// changing our own controlling terminal does not seem like a good idea in the middle
// of the application lifecycle, when we don't know what other Cocoa code may use it...
}
hasCheckedTTY = YES;
}
}

@try {
// Launch and run the tunnel
[task launch]; //throws for invalid paths, missing +x permission

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