compat.c

关于tor匿名通信的源代码

 */
uint32_t
get_uint32(const char *cp)
{
  uint32_t v;
  memcpy(&v,cp,4);
  return v;
}
/**
 * Set a 16-bit value beginning at <b>cp</b> to <b>v</b>. Equivalent to
 * *(uint16_t)(cp) = v, but will not cause segfaults on platforms that forbid
 * unaligned memory access. */
void
set_uint16(char *cp, uint16_t v)
{
  memcpy(cp,&v,2);
}
/**
 * Set a 32-bit value beginning at <b>cp</b> to <b>v</b>. Equivalent to
 * *(uint32_t)(cp) = v, but will not cause segfaults on platforms that forbid
 * unaligned memory access. */
void
set_uint32(char *cp, uint32_t v)
{
  memcpy(cp,&v,4);
}

/**
 * Rename the file <b>from</b> to the file <b>to</b>.  On unix, this is
 * the same as rename(2).  On windows, this removes <b>to</b> first if
 * it already exists.
 * Returns 0 on success.  Returns -1 and sets errno on failure.
 */
int
replace_file(const char *from, const char *to)
{
#ifndef MS_WINDOWS
  return rename(from,to);
#else
  switch (file_status(to))
    {
    case FN_NOENT:
      break;
    case FN_FILE:
      if (unlink(to)) return -1;
      break;
    case FN_ERROR:
      return -1;
    case FN_DIR:
      errno = EISDIR;
      return -1;
    }
  return rename(from,to);
#endif
}

/** Change <b>fname</b>'s modification time to now. */
int
touch_file(const char *fname)
{
  if (utime(fname, NULL)!=0)
    return -1;
  return 0;
}

#undef DEBUG_SOCKET_COUNTING
#ifdef DEBUG_SOCKET_COUNTING
/** A bitarray of all fds that should be passed to tor_socket_close(). Only
 * used if DEBUG_SOCKET_COUNTING is defined. */
static bitarray_t *open_sockets = NULL;
/** The size of <b>open_sockets</b>, in bits. */
static int max_socket = -1;
#endif

/** Count of number of sockets currently open.  (Undercounts sockets opened by
 * eventdns and libevent.) */
static int n_sockets_open = 0;

/** As close(), but guaranteed to work for sockets across platforms (including
 * Windows, where close()ing a socket doesn't work.  Returns 0 on success, -1
 * on failure. */
int
tor_close_socket(int s)
{
  int r = 0;
#ifdef DEBUG_SOCKET_COUNTING
  if (s > max_socket || ! bitarray_is_set(open_sockets, s)) {
    log_warn(LD_BUG, "Closing a socket (%d) that wasn't returned by tor_open_"
             "socket(), or that was already closed or something.", s);
  } else {
    tor_assert(open_sockets && s <= max_socket);
    bitarray_clear(open_sockets, s);
  }
#endif
  /* On Windows, you have to call close() on fds returned by open(),
   * and closesocket() on fds returned by socket().  On Unix, everything
   * gets close()'d.  We abstract this difference by always using
   * tor_close_socket to close sockets, and always using close() on
   * files.
   */
#ifdef USE_BSOCKETS
  r = bclose(s);
#elif defined(MS_WINDOWS)
  r = closesocket(s);
#else
  r = close(s);
#endif
  if (r == 0) {
    --n_sockets_open;
  } else {
    int err = tor_socket_errno(-1);
    log_info(LD_NET, "Close returned an error: %s", tor_socket_strerror(err));
#ifdef WIN32
    if (err != WSAENOTSOCK)
      --n_sockets_open;
#else
    if (err != EBADF)
      --n_sockets_open;
#endif
    r = -1;
  }
  if (n_sockets_open < 0)
    log_warn(LD_BUG, "Our socket count is below zero: %d. Please submit a "
             "bug report.", n_sockets_open);
  return r;
}

#ifdef DEBUG_SOCKET_COUNTING
/** Helper: if DEBUG_SOCKET_COUNTING is enabled, remember that <b>s</b> is
 * now an open socket. */
static INLINE void
mark_socket_open(int s)
{
  if (s > max_socket) {
    if (max_socket == -1) {
      open_sockets = bitarray_init_zero(s+128);
      max_socket = s+128;
    } else {
      open_sockets = bitarray_expand(open_sockets, max_socket, s+128);
      max_socket = s+128;
    }
  }
  if (bitarray_is_set(open_sockets, s)) {
    log_warn(LD_BUG, "I thought that %d was already open, but socket() just "
             "gave it to me!", s);
  }
  bitarray_set(open_sockets, s);
}
#else
#define mark_socket_open(s) STMT_NIL
#endif

/** As socket(), but counts the number of open sockets. */
int
tor_open_socket(int domain, int type, int protocol)
{
  int s = socket(domain, type, protocol);
  if (s >= 0) {
    ++n_sockets_open;
    mark_socket_open(s);
  }
  return s;
}

/** As socket(), but counts the number of open sockets. */
int
tor_accept_socket(int sockfd, struct sockaddr *addr, socklen_t *len)
{
  int s = accept(sockfd, addr, len);
  if (s >= 0) {
    ++n_sockets_open;
    mark_socket_open(s);
  }
  return s;
}

/** Return the number of sockets we currently have opened. */
int
get_n_open_sockets(void)
{
  return n_sockets_open;
}

/** Turn <b>socket</b> into a nonblocking socket.
 */
void
set_socket_nonblocking(int socket)
{
#if defined(MS_WINDOWS) && !defined(USE_BSOCKETS)
  unsigned long nonblocking = 1;
  ioctlsocket(socket, FIONBIO, (unsigned long*) &nonblocking);
#else
  fcntl(socket, F_SETFL, O_NONBLOCK);
#endif
}

/**
 * Allocate a pair of connected sockets.  (Like socketpair(family,
 * type,protocol,fd), but works on systems that don't have
 * socketpair.)
 *
 * Currently, only (AF_UNIX, SOCK_STREAM, 0) sockets are supported.
 *
 * Note that on systems without socketpair, this call will fail if
 * localhost is inaccessible (for example, if the networking
 * stack is down). And even if it succeeds, the socket pair will not
 * be able to read while localhost is down later (the socket pair may
 * even close, depending on OS-specific timeouts).
 *
 * Returns 0 on success and -errno on failure; do not rely on the value
 * of errno or WSAGetLastError().
 **/
/* It would be nicer just to set errno, but that won't work for windows. */
int
tor_socketpair(int family, int type, int protocol, int fd[2])
{
//don't use win32 socketpairs (they are always bad)
#if defined(HAVE_SOCKETPAIR) && !defined(MS_WINDOWS)
  int r;
  r = socketpair(family, type, protocol, fd);
  if (r == 0) {
    if (fd[0] >= 0) {
      ++n_sockets_open;
      mark_socket_open(fd[0]);
    }
    if (fd[1] >= 0) {
      ++n_sockets_open;
      mark_socket_open(fd[1]);
    }
  }
  return r < 0 ? -errno : r;
#elif defined(USE_BSOCKETS)
  return bsocketpair(family, type, protocol, fd);
#else
    /* This socketpair does not work when localhost is down. So
     * it's really not the same thing at all. But it's close enough
     * for now, and really, when localhost is down sometimes, we
     * have other problems too.
     */
    int listener = -1;
    int connector = -1;
    int acceptor = -1;
    struct sockaddr_in listen_addr;
    struct sockaddr_in connect_addr;
    int size;
    int saved_errno = -1;

    if (protocol
#ifdef AF_UNIX
        || family != AF_UNIX
#endif
        ) {
#ifdef MS_WINDOWS
      return -WSAEAFNOSUPPORT;
#else
      return -EAFNOSUPPORT;
#endif
    }
    if (!fd) {
      return -EINVAL;
    }

    listener = tor_open_socket(AF_INET, type, 0);
    if (listener < 0)
      return -tor_socket_errno(-1);
    memset(&listen_addr, 0, sizeof(listen_addr));
    listen_addr.sin_family = AF_INET;
    listen_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    listen_addr.sin_port = 0;   /* kernel chooses port.  */
    if (bind(listener, (struct sockaddr *) &listen_addr, sizeof (listen_addr))
        == -1)
      goto tidy_up_and_fail;
    if (listen(listener, 1) == -1)
      goto tidy_up_and_fail;

    connector = tor_open_socket(AF_INET, type, 0);
    if (connector < 0)
      goto tidy_up_and_fail;
    /* We want to find out the port number to connect to.  */
    size = sizeof(connect_addr);
    if (getsockname(listener, (struct sockaddr *) &connect_addr, &size) == -1)
      goto tidy_up_and_fail;
    if (size != sizeof (connect_addr))
      goto abort_tidy_up_and_fail;
    if (connect(connector, (struct sockaddr *) &connect_addr,
                sizeof(connect_addr)) == -1)
      goto tidy_up_and_fail;

    size = sizeof(listen_addr);
    acceptor = tor_accept_socket(listener,
                                 (struct sockaddr *) &listen_addr, &size);
    if (acceptor < 0)
      goto tidy_up_and_fail;
    if (size != sizeof(listen_addr))
      goto abort_tidy_up_and_fail;
    tor_close_socket(listener);
    /* Now check we are talking to ourself by matching port and host on the
       two sockets.  */
    if (getsockname(connector, (struct sockaddr *) &connect_addr, &size) == -1)
      goto tidy_up_and_fail;
    if (size != sizeof (connect_addr)
        || listen_addr.sin_family != connect_addr.sin_family
        || listen_addr.sin_addr.s_addr != connect_addr.sin_addr.s_addr
        || listen_addr.sin_port != connect_addr.sin_port) {
      goto abort_tidy_up_and_fail;
    }
    fd[0] = connector;
    fd[1] = acceptor;

    return 0;

  abort_tidy_up_and_fail:
#ifdef MS_WINDOWS
    saved_errno = WSAECONNABORTED;
#else
    saved_errno = ECONNABORTED; /* I hope this is portable and appropriate.  */
#endif
  tidy_up_and_fail:
    if (saved_errno < 0)
      saved_errno = errno;
    if (listener != -1)
      tor_close_socket(listener);
    if (connector != -1)
      tor_close_socket(connector);
    if (acceptor != -1)
      tor_close_socket(acceptor);
    return -saved_errno;
#endif
}

#define ULIMIT_BUFFER 32 /* keep 32 extra fd's beyond _ConnLimit */

/** Learn the maximum allowed number of file descriptors. (Some systems
 * have a low soft limit.
 *
 * We compute this by finding the largest number that we can use.
 * If we can't find a number greater than or equal to <b>limit</b>,
 * then we fail: return -1.
 *
 * Otherwise, return 0 and store the maximum we found inside <b>max_out</b>.*/
int
set_max_file_descriptors(rlim_t limit, int *max_out)
{
  /* Define some maximum connections values for systems where we cannot
   * automatically determine a limit. Re Cygwin, see
   * http://archives.seul.org/or/talk/Aug-2006/msg00210.html
   * For an iPhone, 9999 should work. For Windows and all other unknown
   * systems we use 15000 as the default. */
#ifndef HAVE_GETRLIMIT
#if defined(CYGWIN) || defined(__CYGWIN__)
  const char *platform = "Cygwin";
  const unsigned long MAX_CONNECTIONS = 3200;
#elif defined(IPHONE)
  const char *platform = "iPhone";
  const unsigned long MAX_CONNECTIONS = 9999;
#elif defined(MS_WINDOWS)
  const char *platform = "Windows";
  const unsigned long MAX_CONNECTIONS = 15000;
#else
  const char *platform = "unknown platforms with no getrlimit()";
  const unsigned long MAX_CONNECTIONS = 15000;
#endif
  log_fn(LOG_INFO, LD_NET,
         "This platform is missing getrlimit(). Proceeding.");
  if (limit > MAX_CONNECTIONS) {
    log_warn(LD_CONFIG,
             "We do not support more than %lu file descriptors "
             "on %s. Tried to raise to %lu.",
             (unsigned long)MAX_CONNECTIONS, platform, (unsigned long)limit);
    return -1;
  }
  limit = MAX_CONNECTIONS;
#else /* HAVE_GETRLIMIT */
  struct rlimit rlim;
  tor_assert(limit > 0);

  if (getrlimit(RLIMIT_NOFILE, &rlim) != 0) {
    log_warn(LD_NET, "Could not get maximum number of file descriptors: %s",
             strerror(errno));
    return -1;
  }

  if (rlim.rlim_max < limit) {
    log_warn(LD_CONFIG,"We need %lu file descriptors available, and we're "
             "limited to %lu. Please change your ulimit -n.",
             (unsigned long)limit, (unsigned long)rlim.rlim_max);
    return -1;
  }

  if (rlim.rlim_max > rlim.rlim_cur) {
    log_info(LD_NET,"Raising max file descriptors from %lu to %lu.",
             (unsigned long)rlim.rlim_cur, (unsigned long)rlim.rlim_max);
  }
  rlim.rlim_cur = rlim.rlim_max;

  if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) {
    int bad = 1;
#ifdef OPEN_MAX
    if (errno == EINVAL && OPEN_MAX < rlim.rlim_cur) {
      /* On some platforms, OPEN_MAX is the real limit, and getrlimit() is
       * full of nasty lies.  I'm looking at you, OSX 10.5.... */
      rlim.rlim_cur = OPEN_MAX;
      if (setrlimit(RLIMIT_NOFILE, &rlim) == 0) {
        if (rlim.rlim_cur < (rlim_t)limit) {
          log_warn(LD_CONFIG, "We are limited to %lu file descriptors by "
                 "OPEN_MAX, and ConnLimit is %lu.  Changing ConnLimit; sorry.",
                   (unsigned long)OPEN_MAX, (unsigned long)limit);
        } else {
          log_info(LD_CONFIG, "Dropped connection limit to OPEN_MAX (%lu); "
                   "Apparently, %lu was too high and rlimit lied to us.",
                   (unsigned long)OPEN_MAX, (unsigned long)rlim.rlim_max);
        }
        bad = 0;
      }
    }
#endif /* OPEN_MAX */
    if (bad) {
      log_warn(LD_CONFIG,"Couldn't set maximum number of file descriptors: %s",
               strerror(errno));
      return -1;
    }
  }
  /* leave some overhead for logs, etc, */
  limit = rlim.rlim_cur;