ftp-basic.c

Wget很好的处理了http和ftp的下载,很值得学习的经典代码

  /* Parse the response.  */
  s = respline;
  for (s += 4; *s && !ISDIGIT (*s); s++)
    ;
  if (!*s)
    return FTPINVPASV;

  /* First, get the address family */
  af = 0;
  for (; ISDIGIT (*s); s++)
    af = (*s - '0') + 10 * af;

  if (af != 4 && af != 6)
    {
      xfree (respline);
      return FTPINVPASV;
    }

  if (!*s || *s++ != ',')
    {
      xfree (respline);
      return FTPINVPASV;
    }

  /* Then, get the address length */
  addrlen = 0;
  for (; ISDIGIT (*s); s++)
    addrlen = (*s - '0') + 10 * addrlen;

  if (!*s || *s++ != ',')
    {
      xfree (respline);
      return FTPINVPASV;
    }

  if (addrlen > 16)
    {
      xfree (respline);
      return FTPINVPASV;
    }

  if ((af == 4 && addrlen != 4)
      || (af == 6 && addrlen != 16))
    {
      xfree (respline);
      return FTPINVPASV;
    }

  /* Now, we get the actual address */
  for (i = 0; i < addrlen; i++)
    {
      tmp[i] = 0;
      for (; ISDIGIT (*s); s++)
        tmp[i] = (*s - '0') + 10 * tmp[i];
      if (*s == ',')
        s++;
      else
        {
          xfree (respline);
          return FTPINVPASV;
        }
    }

  /* Now, get the port length */
  portlen = 0;
  for (; ISDIGIT (*s); s++)
    portlen = (*s - '0') + 10 * portlen;

  if (!*s || *s++ != ',')
    {
      xfree (respline);
      return FTPINVPASV;
    }

  if (portlen > 2)
    {
      xfree (respline);
      return FTPINVPASV;
    }

  /* Finally, we get the port number */
  tmpprt[0] = 0;
  for (; ISDIGIT (*s); s++)
    tmpprt[0] = (*s - '0') + 10 * tmpprt[0];

  if (!*s || *s++ != ',')
    {
      xfree (respline);
      return FTPINVPASV;
    }

  tmpprt[1] = 0;
  for (; ISDIGIT (*s); s++)
    tmpprt[1] = (*s - '0') + 10 * tmpprt[1];

  assert (s != NULL);

  if (af == 4)
    {
      addr->family = AF_INET;
      memcpy (IP_INADDR_DATA (addr), tmp, 4);
      *port = ((tmpprt[0] << 8) & 0xff00) + tmpprt[1];
      DEBUGP (("lpsv addr is: %s\n", print_address(addr)));
      DEBUGP (("tmpprt[0] is: %d\n", tmpprt[0]));
      DEBUGP (("tmpprt[1] is: %d\n", tmpprt[1]));
      DEBUGP (("*port is: %d\n", *port));
    }
  else
    {
      assert (af == 6);
      addr->family = AF_INET6;
      memcpy (IP_INADDR_DATA (addr), tmp, 16);
      *port = ((tmpprt[0] << 8) & 0xff00) + tmpprt[1];
      DEBUGP (("lpsv addr is: %s\n", print_address(addr)));
      DEBUGP (("tmpprt[0] is: %d\n", tmpprt[0]));
      DEBUGP (("tmpprt[1] is: %d\n", tmpprt[1]));
      DEBUGP (("*port is: %d\n", *port));
    }

  xfree (respline);
  return FTPOK;
}

/* Similar to ftp_eprt, but uses `EPSV' to initiate the passive FTP
   transfer.  Reads the response from server and parses it.  Reads the
   host and port addresses and returns them.  */
uerr_t
ftp_epsv (int csock, ip_address *ip, int *port)
{
  char *request, *respline, *start, delim, *s;
  int nwritten, i;
  uerr_t err;
  int tport;

  assert (ip != NULL);
  assert (port != NULL);

  /* IP already contains the IP address of the control connection's
     peer, so we don't need to call socket_ip_address here.  */

  /* Form the request.  */
  /* EPSV 1 means that we ask for IPv4 and EPSV 2 means that we ask for IPv6. */
  request = ftp_request ("EPSV", (ip->family == AF_INET ? "1" : "2"));

  /* And send it.  */
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);

  /* Get the server response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '2')
    {
      xfree (respline);
      return FTPNOPASV;
    }  

  assert (respline != NULL);

  DEBUGP(("respline is %s\n", respline));

  /* Parse the response.  */
  s = respline;

  /* Skip the useless stuff and get what's inside the parentheses */
  start = strchr (respline, '(');
  if (start == NULL)
    {
      xfree (respline);
      return FTPINVPASV;
    }  

  /* Skip the first two void fields */
  s = start + 1;
  delim = *s++;
  if (delim < 33 || delim > 126)
    {
      xfree (respline);
      return FTPINVPASV;
    }  

  for (i = 0; i < 2; i++)
    {
      if (*s++ != delim) 
        {
          xfree (respline);
        return FTPINVPASV;
        }  
    }

  /* Finally, get the port number */
  tport = 0; 
  for (i = 1; ISDIGIT (*s); s++) 
    {
      if (i > 5)
        {
          xfree (respline);
          return FTPINVPASV;
        }  
      tport = (*s - '0') + 10 * tport;
    }

  /* Make sure that the response terminates correcty */
  if (*s++ != delim)
    {
      xfree (respline);
      return FTPINVPASV;
    }  

  if (*s++ != ')')
    {
      xfree (respline);
      return FTPINVPASV;
    }  

  *port = tport;

  xfree (respline);
  return FTPOK;
}
#endif

/* Sends the TYPE request to the server.  */
uerr_t
ftp_type (int csock, int type)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;
  char stype[2];

  /* Construct argument.  */
  stype[0] = type;
  stype[1] = 0;
  /* Send TYPE request.  */
  request = ftp_request ("TYPE", stype);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '2')
    {
      xfree (respline);
      return FTPUNKNOWNTYPE;
    }
  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* Changes the working directory by issuing a CWD command to the
   server.  */
uerr_t
ftp_cwd (int csock, const char *dir)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;

  /* Send CWD request.  */
  request = ftp_request ("CWD", dir);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline == '5')
    {
      xfree (respline);
      return FTPNSFOD;
    }
  if (*respline != '2')
    {
      xfree (respline);
      return FTPRERR;
    }
  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* Sends REST command to the FTP server.  */
uerr_t
ftp_rest (int csock, wgint offset)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;

  request = ftp_request ("REST", number_to_static_string (offset));
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '3')
    {
      xfree (respline);
      return FTPRESTFAIL;
    }
  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* Sends RETR command to the FTP server.  */
uerr_t
ftp_retr (int csock, const char *file)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;

  /* Send RETR request.  */
  request = ftp_request ("RETR", file);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline == '5')
    {
      xfree (respline);
      return FTPNSFOD;
    }
  if (*respline != '1')
    {
      xfree (respline);
      return FTPRERR;
    }
  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* Sends the LIST command to the server.  If FILE is NULL, send just
   `LIST' (no space).  */
uerr_t
ftp_list (int csock, const char *file)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;
  bool ok = false;
  int i = 0;
  /* Try `LIST -a' first and revert to `LIST' in case of failure.  */
  const char *list_commands[] = { "LIST -a", 
                                  "LIST" };

  do {
    /* Send request.  */
    request = ftp_request (list_commands[i], file);
    nwritten = fd_write (csock, request, strlen (request), -1);
    if (nwritten < 0)
      {
        xfree (request);
        return WRITEFAILED;
      }
    xfree (request);
    /* Get appropriate response.  */
    err = ftp_response (csock, &respline);
    if (err == FTPOK)
      {
        if (*respline == '5')
          {
            err = FTPNSFOD;
          }
        else if (*respline == '1')
          {
            err = FTPOK;
            ok = true;
          }
        else 
          {
            err = FTPRERR;
          }
        xfree (respline);
      }
    ++i;
  } while (i < countof (list_commands) && !ok);
  
  return err;
}

/* Sends the SYST command to the server. */
uerr_t
ftp_syst (int csock, enum stype *server_type)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;

  /* Send SYST request.  */
  request = ftp_request ("SYST", NULL);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);

  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline == '5')
    {
      xfree (respline);
      return FTPSRVERR;
    }

  /* Skip the number (215, but 200 (!!!) in case of VMS) */
  strtok (respline, " ");

  /* Which system type has been reported (we are interested just in the
     first word of the server response)?  */
  request = strtok (NULL, " ");

  if (request == NULL)
    *server_type = ST_OTHER;
  else if (!strcasecmp (request, "VMS"))
    *server_type = ST_VMS;
  else if (!strcasecmp (request, "UNIX"))
    *server_type = ST_UNIX;
  else if (!strcasecmp (request, "WINDOWS_NT")
           || !strcasecmp (request, "WINDOWS2000"))
    *server_type = ST_WINNT;
  else if (!strcasecmp (request, "MACOS"))
    *server_type = ST_MACOS;
  else if (!strcasecmp (request, "OS/400"))
    *server_type = ST_OS400;
  else
    *server_type = ST_OTHER;

  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* Sends the PWD command to the server. */
uerr_t
ftp_pwd (int csock, char **pwd)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;

  /* Send PWD request.  */
  request = ftp_request ("PWD", NULL);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline == '5')
    {
    err:
      xfree (respline);
      return FTPSRVERR;
    }

  /* Skip the number (257), leading citation mark, trailing citation mark
     and everything following it. */
  strtok (respline, "\"");
  request = strtok (NULL, "\"");
  if (!request)
    /* Treat the malformed response as an error, which the caller has
       to handle gracefully anyway.  */
    goto err;

  /* Has the `pwd' been already allocated?  Free! */
  xfree_null (*pwd);

  *pwd = xstrdup (request);

  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* Sends the SIZE command to the server, and returns the value in 'size'.
 * If an error occurs, size is set to zero. */
uerr_t
ftp_size (int csock, const char *file, wgint *size)
{
  char *request, *respline;
  int nwritten;
  uerr_t err;

  /* Send PWD request.  */
  request = ftp_request ("SIZE", file);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      *size = 0;
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    {
      *size = 0;
      return err;
    }
  if (*respline == '5')
    {
      /* 
       * Probably means SIZE isn't supported on this server.
       * Error is nonfatal since SIZE isn't in RFC 959 
       */
      xfree (respline);
      *size = 0;
      return FTPOK;
    }

  errno = 0;
  *size = str_to_wgint (respline + 4, NULL, 10);
  if (errno)
    {
      /* 
       * Couldn't parse the response for some reason.  On the (few)
       * tests I've done, the response is 213 <SIZE> with nothing else -
       * maybe something a bit more resilient is necessary.  It's not a
       * fatal error, however.
       */
      xfree (respline);
      *size = 0;
      return FTPOK;
    }

  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

/* If URL's params are of the form "type=X", return character X.
   Otherwise, return 'I' (the default type).  */
char
ftp_process_type (const char *params)
{
  if (params
      && 0 == strncasecmp (params, "type=", 5)
      && params[5] != '\0')
    return TOUPPER (params[5]);
  else
    return 'I';
}