newlib/winsup/cygserver/transport_pipes.cc

363 lines
8.2 KiB
C++

/* cygserver_transport_pipes.cc
Copyright 2001, 2002 Red Hat Inc.
Written by Robert Collins <rbtcollins@hotmail.com>
This file is part of Cygwin.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
/* to allow this to link into cygwin and the .dll, a little magic is needed. */
#ifdef __OUTSIDE_CYGWIN__
#include "woutsup.h"
#else
#include "winsup.h"
#endif
#include <sys/types.h>
#include <assert.h>
#include <netdb.h>
#include <pthread.h>
#include <unistd.h>
#include "cygerrno.h"
#include "cygwin/cygserver_transport.h"
#include "cygwin/cygserver_transport_pipes.h"
#ifndef __INSIDE_CYGWIN__
#include "cygwin/cygserver.h"
#endif
enum
{
MAX_WAIT_NAMED_PIPE_RETRY = 64,
WAIT_NAMED_PIPE_TIMEOUT = 10 // milliseconds
};
#ifndef __INSIDE_CYGWIN__
static pthread_once_t pipe_instance_lock_once = PTHREAD_ONCE_INIT;
static CRITICAL_SECTION pipe_instance_lock;
static long pipe_instance = 0;
static void
initialise_pipe_instance_lock ()
{
assert (pipe_instance == 0);
InitializeCriticalSection (&pipe_instance_lock);
}
#endif /* !__INSIDE_CYGWIN__ */
#ifndef __INSIDE_CYGWIN__
transport_layer_pipes::transport_layer_pipes (const HANDLE hPipe)
: _pipe_name (""),
_hPipe (hPipe),
_is_accepted_endpoint (true),
_is_listening_endpoint (false)
{
assert (_hPipe);
assert (_hPipe != INVALID_HANDLE_VALUE);
init_security ();
}
#endif /* !__INSIDE_CYGWIN__ */
transport_layer_pipes::transport_layer_pipes ()
: _pipe_name ("\\\\.\\pipe\\cygwin_lpc"),
_hPipe (NULL),
_is_accepted_endpoint (false),
_is_listening_endpoint (false)
{
init_security ();
}
void
transport_layer_pipes::init_security ()
{
assert (wincap.has_security ());
/* FIXME: pthread_once or equivalent needed */
InitializeSecurityDescriptor (&_sd, SECURITY_DESCRIPTOR_REVISION);
SetSecurityDescriptorDacl (&_sd, TRUE, NULL, FALSE);
_sec_all_nih.nLength = sizeof (SECURITY_ATTRIBUTES);
_sec_all_nih.lpSecurityDescriptor = &_sd;
_sec_all_nih.bInheritHandle = FALSE;
}
transport_layer_pipes::~transport_layer_pipes ()
{
close ();
}
#ifndef __INSIDE_CYGWIN__
int
transport_layer_pipes::listen ()
{
assert (!_hPipe);
assert (!_is_accepted_endpoint);
assert (!_is_listening_endpoint);
_is_listening_endpoint = true;
/* no-op */
return 0;
}
class transport_layer_pipes *
transport_layer_pipes::accept (bool *const recoverable)
{
assert (!_hPipe);
assert (!_is_accepted_endpoint);
assert (_is_listening_endpoint);
pthread_once (&pipe_instance_lock_once, &initialise_pipe_instance_lock);
EnterCriticalSection (&pipe_instance_lock);
// Read: http://www.securityinternals.com/research/papers/namedpipe.php
// See also the Microsoft security bulletins MS00-053 and MS01-031.
// FIXME: Remove FILE_CREATE_PIPE_INSTANCE.
const bool first_instance = (pipe_instance == 0);
const HANDLE accept_pipe =
CreateNamedPipe (_pipe_name,
(PIPE_ACCESS_DUPLEX
| (first_instance ? FILE_FLAG_FIRST_PIPE_INSTANCE : 0)),
(PIPE_TYPE_BYTE | PIPE_WAIT),
PIPE_UNLIMITED_INSTANCES,
0, 0, 1000,
&_sec_all_nih);
const bool duplicate = (accept_pipe == INVALID_HANDLE_VALUE
&& pipe_instance == 0
&& GetLastError () == ERROR_ACCESS_DENIED);
if (accept_pipe != INVALID_HANDLE_VALUE)
InterlockedIncrement (&pipe_instance);
LeaveCriticalSection (&pipe_instance_lock);
if (duplicate)
{
*recoverable = false;
system_printf ("failed to create named pipe: "
"is the daemon already running?");
return NULL;
}
if (accept_pipe == INVALID_HANDLE_VALUE)
{
debug_printf ("error creating pipe (%lu).", GetLastError ());
*recoverable = true; // FIXME: case analysis?
return NULL;
}
assert (accept_pipe);
if (!ConnectNamedPipe (accept_pipe, NULL)
&& GetLastError () != ERROR_PIPE_CONNECTED)
{
debug_printf ("error connecting to pipe (%lu)", GetLastError ());
(void) CloseHandle (accept_pipe);
*recoverable = true; // FIXME: case analysis?
return NULL;
}
return safe_new (transport_layer_pipes, accept_pipe);
}
#endif /* !__INSIDE_CYGWIN__ */
void
transport_layer_pipes::close ()
{
// verbose: debug_printf ("closing pipe %p", _hPipe);
if (_hPipe)
{
assert (_hPipe != INVALID_HANDLE_VALUE);
#ifndef __INSIDE_CYGWIN__
if (_is_accepted_endpoint)
{
(void) FlushFileBuffers (_hPipe); // Blocks until client reads.
(void) DisconnectNamedPipe (_hPipe);
EnterCriticalSection (&pipe_instance_lock);
(void) CloseHandle (_hPipe);
assert (pipe_instance > 0);
InterlockedDecrement (&pipe_instance);
LeaveCriticalSection (&pipe_instance_lock);
}
else
(void) CloseHandle (_hPipe);
#else /* __INSIDE_CYGWIN__ */
assert (!_is_accepted_endpoint);
(void) ForceCloseHandle (_hPipe);
#endif /* __INSIDE_CYGWIN__ */
_hPipe = NULL;
}
}
ssize_t
transport_layer_pipes::read (void *const buf, const size_t len)
{
// verbose: debug_printf ("reading from pipe %p", _hPipe);
assert (_hPipe);
assert (_hPipe != INVALID_HANDLE_VALUE);
assert (!_is_listening_endpoint);
DWORD count;
if (!ReadFile (_hPipe, buf, len, &count, NULL))
{
debug_printf ("error reading from pipe (%lu)", GetLastError ());
set_errno (EINVAL); // FIXME?
return -1;
}
return count;
}
ssize_t
transport_layer_pipes::write (void *const buf, const size_t len)
{
// verbose: debug_printf ("writing to pipe %p", _hPipe);
assert (_hPipe);
assert (_hPipe != INVALID_HANDLE_VALUE);
assert (!_is_listening_endpoint);
DWORD count;
if (!WriteFile (_hPipe, buf, len, &count, NULL))
{
debug_printf ("error writing to pipe, error = %lu", GetLastError ());
set_errno (EINVAL); // FIXME?
return -1;
}
return count;
}
/*
* This routine holds a static variable, assume_cygserver, that is set
* if the transport has good reason to think that cygserver is
* running, i.e. if if successfully connected to it with the previous
* attempt. If this is set, the code tries a lot harder to get a
* connection, making the assumption that any failures are just
* congestion and overloading problems.
*/
int
transport_layer_pipes::connect ()
{
assert (!_hPipe);
assert (!_is_accepted_endpoint);
assert (!_is_listening_endpoint);
static bool assume_cygserver = false;
BOOL rc = TRUE;
int retries = 0;
while (rc)
{
_hPipe = CreateFile (_pipe_name,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
&_sec_all_nih,
OPEN_EXISTING,
SECURITY_IMPERSONATION,
NULL);
if (_hPipe != INVALID_HANDLE_VALUE)
{
assert (_hPipe);
#ifdef __INSIDE_CYGWIN__
ProtectHandle (_hPipe);
#endif
assume_cygserver = true;
return 0;
}
_hPipe = NULL;
if (!assume_cygserver && GetLastError () != ERROR_PIPE_BUSY)
{
debug_printf ("Error opening the pipe (%lu)", GetLastError ());
return -1;
}
/* Note: `If no instances of the specified named pipe exist, the
* WaitNamedPipe function returns immediately, regardless of the
* time-out value.' Thus the explicit Sleep if the call fails
* with ERROR_FILE_NOT_FOUND.
*/
while (retries != MAX_WAIT_NAMED_PIPE_RETRY
&& !(rc = WaitNamedPipe (_pipe_name, WAIT_NAMED_PIPE_TIMEOUT)))
{
if (GetLastError () == ERROR_FILE_NOT_FOUND)
Sleep (0); // Give the server a chance.
retries += 1;
}
}
assert (retries == MAX_WAIT_NAMED_PIPE_RETRY);
system_printf ("lost connection to cygserver, error = %lu",
GetLastError ());
assume_cygserver = false;
return -1;
}
#ifndef __INSIDE_CYGWIN__
void
transport_layer_pipes::impersonate_client ()
{
assert (_hPipe);
assert (_hPipe != INVALID_HANDLE_VALUE);
assert (_is_accepted_endpoint);
// verbose: debug_printf ("impersonating pipe %p", _hPipe);
if (_hPipe)
{
assert (_hPipe != INVALID_HANDLE_VALUE);
if (!ImpersonateNamedPipeClient (_hPipe))
debug_printf ("Failed to Impersonate the client, (%lu)",
GetLastError ());
}
// verbose: debug_printf ("I am who you are");
}
void
transport_layer_pipes::revert_to_self ()
{
assert (_is_accepted_endpoint);
RevertToSelf ();
// verbose: debug_printf ("I am who I yam");
}
#endif /* !__INSIDE_CYGWIN__ */