compat.c

关于tor匿名通信的源代码

  return (unsigned long)GetCurrentThreadId();
}
#elif defined(USE_WIN32_THREADS)
/** A generic lock structure for multithreaded builds. */
struct tor_mutex_t {
  CRITICAL_SECTION mutex;
};
tor_mutex_t *
tor_mutex_new(void)
{
  tor_mutex_t *m = tor_malloc_zero(sizeof(tor_mutex_t));
  InitializeCriticalSection(&m->mutex);
  return m;
}
void
tor_mutex_free(tor_mutex_t *m)
{
  DeleteCriticalSection(&m->mutex);
  tor_free(m);
}
void
tor_mutex_acquire(tor_mutex_t *m)
{
  tor_assert(m);
  EnterCriticalSection(&m->mutex);
}
void
tor_mutex_release(tor_mutex_t *m)
{
  LeaveCriticalSection(&m->mutex);
}
unsigned long
tor_get_thread_id(void)
{
  return (unsigned long)GetCurrentThreadId();
}
#elif defined(USE_PTHREADS)
/** A generic lock structure for multithreaded builds. */
struct tor_mutex_t {
  pthread_mutex_t mutex;
};
static pthread_mutexattr_t attr_reentrant;
static int threads_initialized = 0;
/** Allocate and return new lock. */
tor_mutex_t *
tor_mutex_new(void)
{
  int err;
  tor_mutex_t *mutex = tor_malloc_zero(sizeof(tor_mutex_t));
  if (PREDICT_UNLIKELY(!threads_initialized))
    tor_threads_init();
  err = pthread_mutex_init(&mutex->mutex, &attr_reentrant);
  if (PREDICT_UNLIKELY(err)) {
    log_err(LD_GENERAL, "Error %d creating a mutex.", err);
    tor_fragile_assert();
  }
  return mutex;
}
/** Wait until <b>m</b> is free, then acquire it. */
void
tor_mutex_acquire(tor_mutex_t *m)
{
  int err;
  tor_assert(m);
  err = pthread_mutex_lock(&m->mutex);
  if (PREDICT_UNLIKELY(err)) {
    log_err(LD_GENERAL, "Error %d locking a mutex.", err);
    tor_fragile_assert();
  }
}
/** Release the lock <b>m</b> so another thread can have it. */
void
tor_mutex_release(tor_mutex_t *m)
{
  int err;
  tor_assert(m);
  err = pthread_mutex_unlock(&m->mutex);
  if (PREDICT_UNLIKELY(err)) {
    log_err(LD_GENERAL, "Error %d unlocking a mutex.", err);
    tor_fragile_assert();
  }
}
/** Free all storage held by the lock <b>m</b>. */
void
tor_mutex_free(tor_mutex_t *m)
{
  int err;
  tor_assert(m);
  err = pthread_mutex_destroy(&m->mutex);
  if (PREDICT_UNLIKELY(err)) {
    log_err(LD_GENERAL, "Error %d destroying a mutex.", err);
    tor_fragile_assert();
  }
  tor_free(m);
}
/** Return an integer representing this thread. */
unsigned long
tor_get_thread_id(void)
{
  union {
    pthread_t thr;
    unsigned long id;
  } r;
  r.thr = pthread_self();
  return r.id;
}
#else
/** A generic lock structure for multithreaded builds. */
struct tor_mutex_t {
  int _unused;
};
#endif

/* Conditions. */
#ifdef USE_PTHREADS
#if 0
/** Cross-platform condition implementation. */
struct tor_cond_t {
  pthread_cond_t cond;
};
/** Return a newly allocated condition, with nobody waiting on it. */
tor_cond_t *
tor_cond_new(void)
{
  tor_cond_t *cond = tor_malloc_zero(sizeof(tor_cond_t));
  if (pthread_cond_init(&cond->cond, NULL)) {
    tor_free(cond);
    return NULL;
  }
  return cond;
}
/** Release all resources held by <b>cond</b>. */
void
tor_cond_free(tor_cond_t *cond)
{
  tor_assert(cond);
  if (pthread_cond_destroy(&cond->cond)) {
    log_warn(LD_GENERAL,"Error freeing condition: %s", strerror(errno));
    return;
  }
  tor_free(cond);
}
/** Wait until one of the tor_cond_signal functions is called on <b>cond</b>.
 * All waiters on the condition must wait holding the same <b>mutex</b>.
 * Returns 0 on success, negative on failure. */
int
tor_cond_wait(tor_cond_t *cond, tor_mutex_t *mutex)
{
  return pthread_cond_wait(&cond->cond, &mutex->mutex) ? -1 : 0;
}
/** Wake up one of the waiters on <b>cond</b>. */
void
tor_cond_signal_one(tor_cond_t *cond)
{
  pthread_cond_signal(&cond->cond);
}
/** Wake up all of the waiters on <b>cond</b>. */
void
tor_cond_signal_all(tor_cond_t *cond)
{
  pthread_cond_broadcast(&cond->cond);
}
#endif
/** Set up common structures for use by threading. */
void
tor_threads_init(void)
{
  if (!threads_initialized) {
    pthread_mutexattr_init(&attr_reentrant);
    pthread_mutexattr_settype(&attr_reentrant, PTHREAD_MUTEX_RECURSIVE);
    threads_initialized = 1;
  }
}
#elif defined(USE_WIN32_THREADS)
#if 0
static DWORD cond_event_tls_index;
struct tor_cond_t {
  CRITICAL_SECTION mutex;
  smartlist_t *events;
};
tor_cond_t *
tor_cond_new(void)
{
  tor_cond_t *cond = tor_malloc_zero(sizeof(tor_cond_t));
  InitializeCriticalSection(&cond->mutex);
  cond->events = smartlist_create();
  return cond;
}
void
tor_cond_free(tor_cond_t *cond)
{
  tor_assert(cond);
  DeleteCriticalSection(&cond->mutex);
  /* XXXX notify? */
  smartlist_free(cond->events);
  tor_free(cond);
}
int
tor_cond_wait(tor_cond_t *cond, tor_mutex_t *mutex)
{
  HANDLE event;
  int r;
  tor_assert(cond);
  tor_assert(mutex);
  event = TlsGetValue(cond_event_tls_index);
  if (!event) {
    event = CreateEvent(0, FALSE, FALSE, NULL);
    TlsSetValue(cond_event_tls_index, event);
  }
  EnterCriticalSection(&cond->mutex);

  tor_assert(WaitForSingleObject(event, 0) == WAIT_TIMEOUT);
  tor_assert(!smartlist_isin(cond->events, event));
  smartlist_add(cond->events, event);

  LeaveCriticalSection(&cond->mutex);

  tor_mutex_release(mutex);
  r = WaitForSingleObject(event, INFINITE);
  tor_mutex_acquire(mutex);

  switch (r) {
    case WAIT_OBJECT_0: /* we got the mutex normally. */
      break;
    case WAIT_ABANDONED: /* holding thread exited. */
    case WAIT_TIMEOUT: /* Should never happen. */
      tor_assert(0);
      break;
    case WAIT_FAILED:
      log_warn(LD_GENERAL, "Failed to acquire mutex: %d",(int) GetLastError());
  }
  return 0;
}
void
tor_cond_signal_one(tor_cond_t *cond)
{
  HANDLE event;
  tor_assert(cond);

  EnterCriticalSection(&cond->mutex);

  if ((event = smartlist_pop_last(cond->events)))
    SetEvent(event);

  LeaveCriticalSection(&cond->mutex);
}
void
tor_cond_signal_all(tor_cond_t *cond)
{
  tor_assert(cond);

  EnterCriticalSection(&cond->mutex);
  SMARTLIST_FOREACH(cond->events, HANDLE, event, SetEvent(event));
  smartlist_clear(cond->events);
  LeaveCriticalSection(&cond->mutex);
}
#endif
void
tor_threads_init(void)
{
#if 0
  cond_event_tls_index = TlsAlloc();
#endif
}
#endif

/**
 * On Windows, WSAEWOULDBLOCK is not always correct: when you see it,
 * you need to ask the socket for its actual errno.  Also, you need to
 * get your errors from WSAGetLastError, not errno.  (If you supply a
 * socket of -1, we check WSAGetLastError, but don't correct
 * WSAEWOULDBLOCKs.)
 *
 * The upshot of all of this is that when a socket call fails, you
 * should call tor_socket_errno <em>at most once</em> on the failing
 * socket to get the error.
 */
#if defined(MS_WINDOWS) && !defined(USE_BSOCKETS)
int
tor_socket_errno(int sock)
{
  int optval, optvallen=sizeof(optval);
  int err = WSAGetLastError();
  if (err == WSAEWOULDBLOCK && sock >= 0) {
    if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval, &optvallen))
      return err;
    if (optval)
      return optval;
  }
  return err;
}
#endif

#if defined(MS_WINDOWS) && !defined(USE_BSOCKETS)
#define E(code, s) { code, (s " [" #code " ]") }
struct { int code; const char *msg; } windows_socket_errors[] = {
  E(WSAEINTR, "Interrupted function call"),
  E(WSAEACCES, "Permission denied"),
  E(WSAEFAULT, "Bad address"),
  E(WSAEINVAL, "Invalid argument"),
  E(WSAEMFILE, "Too many open files"),
  E(WSAEWOULDBLOCK,  "Resource temporarily unavailable"),
  E(WSAEINPROGRESS, "Operation now in progress"),
  E(WSAEALREADY, "Operation already in progress"),
  E(WSAENOTSOCK, "Socket operation on nonsocket"),
  E(WSAEDESTADDRREQ, "Destination address required"),
  E(WSAEMSGSIZE, "Message too long"),
  E(WSAEPROTOTYPE, "Protocol wrong for socket"),
  E(WSAENOPROTOOPT, "Bad protocol option"),
  E(WSAEPROTONOSUPPORT, "Protocol not supported"),
  E(WSAESOCKTNOSUPPORT, "Socket type not supported"),
  /* What's the difference between NOTSUPP and NOSUPPORT? :) */
  E(WSAEOPNOTSUPP, "Operation not supported"),
  E(WSAEPFNOSUPPORT,  "Protocol family not supported"),
  E(WSAEAFNOSUPPORT, "Address family not supported by protocol family"),
  E(WSAEADDRINUSE, "Address already in use"),
  E(WSAEADDRNOTAVAIL, "Cannot assign requested address"),
  E(WSAENETDOWN, "Network is down"),
  E(WSAENETUNREACH, "Network is unreachable"),
  E(WSAENETRESET, "Network dropped connection on reset"),
  E(WSAECONNABORTED, "Software caused connection abort"),
  E(WSAECONNRESET, "Connection reset by peer"),
  E(WSAENOBUFS, "No buffer space available"),
  E(WSAEISCONN, "Socket is already connected"),
  E(WSAENOTCONN, "Socket is not connected"),
  E(WSAESHUTDOWN, "Cannot send after socket shutdown"),
  E(WSAETIMEDOUT, "Connection timed out"),
  E(WSAECONNREFUSED, "Connection refused"),
  E(WSAEHOSTDOWN, "Host is down"),
  E(WSAEHOSTUNREACH, "No route to host"),
  E(WSAEPROCLIM, "Too many processes"),
  /* Yes, some of these start with WSA, not WSAE. No, I don't know why. */
  E(WSASYSNOTREADY, "Network subsystem is unavailable"),
  E(WSAVERNOTSUPPORTED, "Winsock.dll out of range"),
  E(WSANOTINITIALISED, "Successful WSAStartup not yet performed"),
  E(WSAEDISCON, "Graceful shutdown now in progress"),
#ifdef WSATYPE_NOT_FOUND
  E(WSATYPE_NOT_FOUND, "Class type not found"),
#endif
  E(WSAHOST_NOT_FOUND, "Host not found"),
  E(WSATRY_AGAIN, "Nonauthoritative host not found"),
  E(WSANO_RECOVERY, "This is a nonrecoverable error"),
  E(WSANO_DATA, "Valid name, no data record of requested type)"),

  /* There are some more error codes whose numeric values are marked
   * <b>OS dependent</b>. They start with WSA_, apparently for the same
   * reason that practitioners of some craft traditions deliberately
   * introduce imperfections into their baskets and rugs "to allow the
   * evil spirits to escape."  If we catch them, then our binaries
   * might not report consistent results across versions of Windows.
   * Thus, I'm going to let them all fall through.
   */
  { -1, NULL },
};
/** There does not seem to be a strerror equivalent for winsock errors.
 * Naturally, we have to roll our own.
 */
const char *
tor_socket_strerror(int e)
{
  int i;
  for (i=0; windows_socket_errors[i].code >= 0; ++i) {
    if (e == windows_socket_errors[i].code)
      return windows_socket_errors[i].msg;
  }
  return strerror(e);
}
#endif

/** Called before we make any calls to network-related functions.
 * (Some operating systems require their network libraries to be
 * initialized.) */
int
network_init(void)
{
#ifdef MS_WINDOWS
  /* This silly exercise is necessary before windows will allow
   * gethostbyname to work. */
  WSADATA WSAData;
  int r;
  r = WSAStartup(0x101,&WSAData);
  if (r) {
    log_warn(LD_NET,"Error initializing windows network layer: code was %d",r);
    return -1;
  }
  /* WSAData.iMaxSockets might show the max sockets we're allowed to use.
   * We might use it to complain if we're trying to be a server but have
   * too few sockets available. */
#endif
  return 0;
}

#ifdef MS_WINDOWS
/** Return a newly allocated string describing the windows system error code
 * <b>err</b>.  Note that error codes are different from errno.  Error codes
 * come from GetLastError() when a winapi call fails.  errno is set only when
 * ansi functions fail.  Whee. */
char *
format_win32_error(DWORD err)
{
  LPVOID str = NULL;
  char *result;

  /* Somebody once decided that this interface was better than strerror(). */
  FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                 FORMAT_MESSAGE_FROM_SYSTEM |
                 FORMAT_MESSAGE_IGNORE_INSERTS,
                 NULL, err,
                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                 (LPTSTR) &str,
                 0, NULL);

  if (str) {
    result = tor_strdup((char*)str);
    LocalFree(str); /* LocalFree != free() */
  } else {
    result = tor_strdup("<unformattable error>");
  }
  return result;
}
#endif