ftpd.c

linux下ftpd服务器端的源码实现

#else
  va_start (ap);
#endif
  printf ("%d ", n);
  vprintf (fmt, ap);
  printf ("\r\n");
  fflush (stdout);
  if (debug)
    {
      syslog (LOG_DEBUG, "<--- %d ", n);
      vsyslog (LOG_DEBUG, fmt, ap);
    }
}

void
lreply (int n, const char *fmt, ...)
{
  va_list ap;
#if defined(HAVE_STDARG_H) && defined(__STDC__) && __STDC__
  va_start (ap, fmt);
#else
  va_start (ap);
#endif
  printf ("%d- ", n);
  vprintf (fmt, ap);
  printf ("\r\n");
  fflush (stdout);
  if (debug)
    {
      syslog (LOG_DEBUG, "<--- %d- ", n);
      vsyslog (LOG_DEBUG, fmt, ap);
    }
}

static void
ack (const char *s)
{
  reply (250, "%s command successful.", s);
}

void
nack (const char *s)
{
  reply (502, "%s command not implemented.", s);
}

void
delete (const char *name)
{
  struct stat st;

  LOGCMD ("delete", name);
  if (stat (name, &st) < 0)
    {
      perror_reply (550, name);
      return;
    }
  if (S_ISDIR (st.st_mode))
    {
      if (rmdir (name) < 0)
	{
	  perror_reply (550, name);
	  return;
	}
      goto done;
    }
  if (unlink (name) < 0)
    {
      perror_reply (550, name);
      return;
    }
 done:
  ack ("DELE");
}

void
cwd (const char *path)
{
  if (chdir (path) < 0)
    perror_reply (550, path);
  else
    ack ("CWD");
}

void
makedir (const char *name)
{
  extern char *xgetcwd (void);

  LOGCMD ("mkdir", name);
  if (mkdir (name, 0777) < 0)
    perror_reply (550, name);
  else if (name[0] == '/')
    reply (257, "\"%s\" new directory created.");
  else
    {
      /* We have to figure out what our current directory is so that we can
	 give an absolute name in the reply.  */
      char *current = xgetcwd ();
      if (current)
	{
	  if (current[1] == '\0')
	    current[0] = '\0';
	  reply (257, "\"%s/%s\" new directory created.", current, name);
	  free (current);
	}
      else
	reply (257, "(unknown absolute name) new directory created.");
    }
}

void
removedir (const char *name)
{
  LOGCMD ("rmdir", name);
  if (rmdir (name) < 0)
    perror_reply (550, name);
  else
    ack("RMD");
}

void
pwd (void)
{
  extern char *xgetcwd (void);
  char *path = xgetcwd ();
  if (path)
    {
      reply (257, "\"%s\" is current directory.", path);
      free (path);
    }
  else
    reply (550, "%s.", strerror (errno));
}

char *
renamefrom (const char *name)
{
  struct stat st;

  if (stat (name, &st) < 0)
    {
      perror_reply (550, name);
      return ((char *)0);
    }
  reply (350, "File exists, ready for destination name");
  return (char *)(name);
}

void
renamecmd (const char *from, const char *to)
{
  LOGCMD2 ("rename", from, to);
  if (rename (from, to) < 0)
    perror_reply (550, "rename");
  else
    ack ("RNTO");
}

static void
dolog (struct sockaddr_in *sin, struct credentials *pcred)
{
  const char *name;
  struct hostent *hp = gethostbyaddr ((char *)&sin->sin_addr,
				      sizeof (struct in_addr), AF_INET);

  if (hp)
    name = hp->h_name;
  else
    name = inet_ntoa (sin->sin_addr);

  if (pcred->remotehost)
    free (pcred->remotehost);
  pcred->remotehost = sgetsave (name);

#ifdef HAVE_SETPROCTITLE
  snprintf (proctitle, sizeof (proctitle), "%s: connected", pcred->remotehost);
  setproctitle ("%s",proctitle);
#endif /* HAVE_SETPROCTITLE */

  if (logging)
    syslog (LOG_INFO, "connection from %s", pcred->remotehost);
}

/*  Record logout in wtmp file
    and exit with supplied status.  */
void
dologout (int status)
{
  /* Racing condition with SIGURG: If SIGURG is receive
     here, it will jump back has root in the main loop
     David Greenman:[e-mail].  */
  transflag = 0;

  if (cred.logged_in)
    {
      seteuid ((uid_t)0);
      logwtmp_keep_open (ttyline, "", "");
    }
  /* beware of flushing buffers after a SIGPIPE */
  _exit (status);
}

static RETSIGTYPE
myoob (int signo ARG_UNUSED)
{
  char *cp;

  /* only process if transfer occurring */
  if (!transflag)
    return;
  cp = tmpline;
  if (telnet_fgets (cp, 7, stdin) == NULL)
    {
      reply (221, "You could at least say goodbye.");
      dologout (0);
    }
  upper (cp);
  if (strcmp (cp, "ABOR\r\n") == 0)
    {
      tmpline[0] = '\0';
      reply (426, "Transfer aborted. Data connection closed.");
      reply (226, "Abort successful");
      longjmp (urgcatch, 1);
    }
  if (strcmp (cp, "STAT\r\n") == 0)
    {
      if (file_size != (off_t) -1)
	reply (213, "Status: %s of %s bytes transferred",
	       off_to_str (byte_count), off_to_str (file_size));
      else
	reply (213, "Status: %s bytes transferred",
	       off_to_str (byte_count));
    }
}

/* Note: a response of 425 is not mentioned as a possible response to
   the PASV command in RFC959. However, it has been blessed as
   a legitimate response by Jon Postel in a telephone conversation
   with Rick Adams on 25 Jan 89.  */
void
passive (void)
{
  int len;
  char *p, *a;

  pdata = socket (AF_INET, SOCK_STREAM, 0);
  if (pdata < 0)
    {
      perror_reply (425, "Can't open passive connection");
      return;
    }
  pasv_addr = ctrl_addr;
  pasv_addr.sin_port = 0;
  seteuid ((uid_t)0);
  if (bind (pdata, (struct sockaddr *)&pasv_addr, sizeof (pasv_addr)) < 0)
    {
      seteuid ((uid_t)cred.uid);
      goto pasv_error;
    }
  seteuid ((uid_t)cred.uid);
  len = sizeof(pasv_addr);
  if (getsockname (pdata, (struct sockaddr *) &pasv_addr, &len) < 0)
    goto pasv_error;
  if (listen (pdata, 1) < 0)
    goto pasv_error;
  a = (char *) &pasv_addr.sin_addr;
  p = (char *) &pasv_addr.sin_port;

#define UC(b) (((int) b) & 0xff)

  reply (227, "Entering Passive Mode (%d,%d,%d,%d,%d,%d)", UC(a[0]),
	 UC(a[1]), UC(a[2]), UC(a[3]), UC(p[0]), UC(p[1]));
  return;

 pasv_error:
  close (pdata);
  pdata = -1;
  perror_reply (425, "Can't open passive connection");
  return;
}

/* Generate unique name for file with basename "local".
   The file named "local" is already known to exist.
   Generates failure reply on error.  */
static char *
gunique (const char *local)
{
  static char *string = 0;
  struct stat st;
  int count;
  char *cp;

  cp = strrchr (local, '/');
  if (cp)
    *cp = '\0';
  if (stat(cp ? local : ".", &st) < 0)
    {
      perror_reply (553, cp ? local : ".");
      return ((char *) 0);
    }
  if (cp)
    *cp = '/';

  if (string)
    free (string);

  string = malloc (strlen (local) + 5); /* '.' + DIG + DIG + '\0' */
  if (string)
    {
      strcpy (string, local);
      cp = string + strlen (string);
      *cp++ = '.';
      for (count = 1; count < 100; count++)
	{
	  sprintf (cp, "%d", count);
	  if (stat (string, &st) < 0)
	    return string;
	}
    }

  reply (452, "Unique file name cannot be created.");
  return NULL;
}

/*
 * Format and send reply containing system error number.
 */
void
perror_reply (int code, const char *string)
{
  reply (code, "%s: %s.", string, strerror (errno));
}

static char *onefile[] = {
	"",
	0
};

void
send_file_list (const char *whichf)
{
  struct stat st;
  DIR *dirp = NULL;
  struct dirent *dir;
  FILE *dout = NULL;
  char **dirlist, *dirname;
  int simple = 0;
  int freeglob = 0;
  glob_t gl;
  char *p = NULL;

  if (strpbrk(whichf, "~{[*?") != NULL)
    {
      int flags = GLOB_NOCHECK;

#ifdef GLOB_BRACE
      flags |= GLOB_BRACE;
#endif
#ifdef GLOB_QUOTE
      flags |= GLOB_QUOTE;
#endif
#ifdef GLOB_TILDE
      flags |= GLOB_TILDE;
#endif

      memset (&gl, 0, sizeof (gl));
      freeglob = 1;
      if (glob (whichf, flags, 0, &gl))
	{
	  reply (550, "not found");
	  goto out;
	}
      else if (gl.gl_pathc == 0)
	{
	  errno = ENOENT;
	  perror_reply (550, whichf);
	  goto out;
	}
      dirlist = gl.gl_pathv;
    }
  else
    {
      p = strdup (whichf);
      onefile[0] = p;
      dirlist = onefile;
      simple = 1;
    }

  if (setjmp (urgcatch))
    {
      transflag = 0;
      goto out;
    }
  while ((dirname = *dirlist++))
    {
      if (stat (dirname, &st) < 0)
	{
	  /* If user typed "ls -l", etc, and the client
	     used NLST, do what the user meant.  */
	  if (dirname[0] == '-' && *dirlist == NULL
	      && transflag == 0)
	    {
	      retrieve ("/bin/ls %s", dirname);
	      goto out;
	    }
	  perror_reply (550, whichf);
	  if (dout != NULL)
	    {
	      fclose (dout);
	      transflag = 0;
	      data = -1;
	      pdata = -1;
	    }
	  goto out;
	}

      if (S_ISREG(st.st_mode))
	{
	  if (dout == NULL)
	    {
	      dout = dataconn ("file list", (off_t)-1, "w");
	      if (dout == NULL)
		goto out;
	      transflag++;
	    }
	  fprintf (dout, "%s%s\n", dirname,
		   type == TYPE_A ? "\r" : "");
	  byte_count += strlen (dirname) + 1;
	  continue;
	}
      else if (!S_ISDIR (st.st_mode))
	continue;

      dirp = opendir (dirname);
      if (dirp == NULL)
	continue;

      while ((dir = readdir (dirp)) != NULL)
	{
	  char *nbuf;

	  if (dir->d_name[0] == '.' && dir->d_name[1] == '\0')
	    continue;
	  if (dir->d_name[0] == '.' && dir->d_name[1] == '.' &&
	      dir->d_name[2] == '\0')
	    continue;

	  nbuf = (char *) alloca (strlen (dirname) + 1 +
				  strlen (dir->d_name) + 1);
	  sprintf (nbuf, "%s/%s", dirname, dir->d_name);

	  /* We have to do a stat to insure it's
	     not a directory or special file.  */
	  if (simple || (stat (nbuf, &st) == 0
			 && S_ISREG(st.st_mode)))
	    {
	      if (dout == NULL)
		{
		  dout = dataconn ("file list", (off_t)-1, "w");
		  if (dout == NULL)
		    goto out;
		  transflag++;
		}
	      if (nbuf[0] == '.' && nbuf[1] == '/')
		fprintf (dout, "%s%s\n", &nbuf[2], type == TYPE_A ? "\r" : "");
	      else
		fprintf (dout, "%s%s\n", nbuf, type == TYPE_A ? "\r" : "");
	      byte_count += strlen (nbuf) + 1;
	    }
	}
      closedir (dirp);
    }

  if (dout == NULL)
    reply (550, "No files found.");
  else if (ferror (dout) != 0)
    perror_reply (550, "Data connection");
  else
    reply (226, "Transfer complete.");

  transflag = 0;
  if (dout != NULL)
    fclose (dout);
  data = -1;
  pdata = -1;
 out:
  if (p)
    free (p);
  if (freeglob)
    {
      freeglob = 0;
      globfree (&gl);
    }
}