ftp.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 ***************************************************************************/

#include "setup.h"

#ifndef CURL_DISABLE_FTP
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifndef WIN32
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_UTSNAME_H
#include <sys/utsname.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef  VMS
#include <in.h>
#include <inet.h>
#endif
#endif  /* !WIN32 */

#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
#undef in_addr_t
#define in_addr_t unsigned long
#endif

#include <curl/curl.h>
#include "urldata.h"
#include "sendf.h"
#include "easyif.h" /* for Curl_convert_... prototypes */

#include "if2ip.h"
#include "hostip.h"
#include "progress.h"
#include "transfer.h"
#include "escape.h"
#include "http.h" /* for HTTP proxy tunnel stuff */
#include "socks.h"
#include "ftp.h"

#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
#include "krb4.h"
#endif

#include "strtoofft.h"
#include "strequal.h"
#include "sslgen.h"
#include "connect.h"
#include "strerror.h"
#include "memory.h"
#include "inet_ntop.h"
#include "select.h"
#include "parsedate.h" /* for the week day and month names */
#include "sockaddr.h" /* required for Curl_sockaddr_storage */
#include "multiif.h"
#include "url.h"

#if defined(HAVE_INET_NTOA_R) && !defined(HAVE_INET_NTOA_R_DECL)
#include "inet_ntoa_r.h"
#endif

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

/* The last #include file should be: */
#ifdef CURLDEBUG
#include "memdebug.h"
#endif

#ifdef HAVE_NI_WITHSCOPEID
#define NIFLAGS NI_NUMERICHOST | NI_NUMERICSERV | NI_WITHSCOPEID
#else
#define NIFLAGS NI_NUMERICHOST | NI_NUMERICSERV
#endif

#ifdef CURL_DISABLE_VERBOSE_STRINGS
#define ftp_pasv_verbose(a,b,c,d)  do { } while (0)
#endif

/* Local API functions */
static CURLcode ftp_sendquote(struct connectdata *conn,
                              struct curl_slist *quote);
static CURLcode ftp_quit(struct connectdata *conn);
static CURLcode ftp_parse_url_path(struct connectdata *conn);
static CURLcode ftp_regular_transfer(struct connectdata *conn, bool *done);
#ifndef CURL_DISABLE_VERBOSE_STRINGS
static void ftp_pasv_verbose(struct connectdata *conn,
                             Curl_addrinfo *ai,
                             char *newhost, /* ascii version */
                             int port);
#endif
static CURLcode ftp_state_post_rest(struct connectdata *conn);
static CURLcode ftp_state_post_cwd(struct connectdata *conn);
static CURLcode ftp_state_quote(struct connectdata *conn,
                                bool init, ftpstate instate);
static CURLcode ftp_nb_type(struct connectdata *conn,
                            bool ascii, ftpstate newstate);
static int ftp_need_type(struct connectdata *conn,
                         bool ascii);
static CURLcode Curl_ftp(struct connectdata *conn, bool *done);
static CURLcode Curl_ftp_done(struct connectdata *conn,
                              CURLcode, bool premature);
static CURLcode Curl_ftp_connect(struct connectdata *conn, bool *done);
static CURLcode Curl_ftp_disconnect(struct connectdata *conn);
static CURLcode Curl_ftp_nextconnect(struct connectdata *conn);
static CURLcode Curl_ftp_multi_statemach(struct connectdata *conn, bool *done);
static int Curl_ftp_getsock(struct connectdata *conn,
                            curl_socket_t *socks,
                            int numsocks);
static CURLcode Curl_ftp_doing(struct connectdata *conn,
                               bool *dophase_done);
static CURLcode Curl_ftp_setup_connection(struct connectdata * conn);
#ifdef USE_SSL
static CURLcode Curl_ftps_setup_connection(struct connectdata * conn);
#endif

/* easy-to-use macro: */
#define FTPSENDF(x,y,z)    if ((result = Curl_ftpsendf(x,y,z)) != CURLE_OK) \
                              return result
#define NBFTPSENDF(x,y,z)  if ((result = Curl_nbftpsendf(x,y,z)) != CURLE_OK) \
                              return result


/*
 * FTP protocol handler.
 */

const struct Curl_handler Curl_handler_ftp = {
  "FTP",                                /* scheme */
  Curl_ftp_setup_connection,            /* setup_connection */
  Curl_ftp,                             /* do_it */
  Curl_ftp_done,                        /* done */
  Curl_ftp_nextconnect,                 /* do_more */
  Curl_ftp_connect,                     /* connect_it */
  Curl_ftp_multi_statemach,             /* connecting */
  Curl_ftp_doing,                       /* doing */
  Curl_ftp_getsock,                     /* proto_getsock */
  Curl_ftp_getsock,                     /* doing_getsock */
  Curl_ftp_disconnect,                  /* disconnect */
  PORT_FTP,                             /* defport */
  PROT_FTP                              /* protocol */
};


#ifdef USE_SSL
/*
 * FTPS protocol handler.
 */

const struct Curl_handler Curl_handler_ftps = {
  "FTPS",                               /* scheme */
  Curl_ftps_setup_connection,           /* setup_connection */
  Curl_ftp,                             /* do_it */
  Curl_ftp_done,                        /* done */
  Curl_ftp_nextconnect,                 /* do_more */
  Curl_ftp_connect,                     /* connect_it */
  Curl_ftp_multi_statemach,             /* connecting */
  Curl_ftp_doing,                       /* doing */
  Curl_ftp_getsock,                     /* proto_getsock */
  Curl_ftp_getsock,                     /* doing_getsock */
  Curl_ftp_disconnect,                  /* disconnect */
  PORT_FTPS,                            /* defport */
  PROT_FTP | PROT_FTPS | PROT_SSL       /* protocol */
};
#endif

#ifndef CURL_DISABLE_HTTP
/*
 * HTTP-proxyed FTP protocol handler.
 */

const struct Curl_handler Curl_handler_ftp_proxy = {
  "FTP",                                /* scheme */
  ZERO_NULL,                            /* setup_connection */
  Curl_http,                            /* do_it */
  Curl_http_done,                       /* done */
  ZERO_NULL,                            /* do_more */
  ZERO_NULL,                            /* connect_it */
  ZERO_NULL,                            /* connecting */
  ZERO_NULL,                            /* doing */
  ZERO_NULL,                            /* proto_getsock */
  ZERO_NULL,                            /* doing_getsock */
  ZERO_NULL,                            /* disconnect */
  PORT_FTP,                             /* defport */
  PROT_HTTP                             /* protocol */
};


#ifdef USE_SSL
/*
 * HTTP-proxyed FTPS protocol handler.
 */

const struct Curl_handler Curl_handler_ftps_proxy = {
  "FTPS",                               /* scheme */
  ZERO_NULL,                            /* setup_connection */
  Curl_http,                            /* do_it */
  Curl_http_done,                       /* done */
  ZERO_NULL,                            /* do_more */
  ZERO_NULL,                            /* connect_it */
  ZERO_NULL,                            /* connecting */
  ZERO_NULL,                            /* doing */
  ZERO_NULL,                            /* proto_getsock */
  ZERO_NULL,                            /* doing_getsock */
  ZERO_NULL,                            /* disconnect */
  PORT_FTPS,                            /* defport */
  PROT_HTTP                             /* protocol */
};
#endif
#endif


/*
 * NOTE: back in the old days, we added code in the FTP code that made NOBODY
 * requests on files respond with headers passed to the client/stdout that
 * looked like HTTP ones.
 *
 * This approach is not very elegant, it causes confusion and is error-prone.
 * It is subject for removal at the next (or at least a future) soname bump.
 * Until then you can test the effects of the removal by undefining the
 * following define named CURL_FTP_HTTPSTYLE_HEAD.
 */
#define CURL_FTP_HTTPSTYLE_HEAD 1

static void freedirs(struct connectdata *conn)
{
  struct ftp_conn *ftpc = &conn->proto.ftpc;

  int i;
  if(ftpc->dirs) {
    for (i=0; i < ftpc->dirdepth; i++){
      if(ftpc->dirs[i]) {
        free(ftpc->dirs[i]);
        ftpc->dirs[i]=NULL;
      }
    }
    free(ftpc->dirs);
    ftpc->dirs = NULL;
  }
  if(ftpc->file) {
    free(ftpc->file);
    ftpc->file = NULL;
  }
}

/* Returns non-zero if the given string contains CR (\r) or LF (\n),
   which are not allowed within RFC 959 <string>.
   Note: The input string is in the client's encoding which might
   not be ASCII, so escape sequences \r & \n must be used instead
   of hex values 0x0d & 0x0a.
*/
static bool isBadFtpString(const char *string)
{
  return (bool)((NULL != strchr(string, '\r')) || (NULL != strchr(string, '\n')));
}

/***********************************************************************
 *
 * AllowServerConnect()
 *
 * When we've issue the PORT command, we have told the server to connect
 * to us. This function will sit and wait here until the server has
 * connected.
 *
 */
static CURLcode AllowServerConnect(struct connectdata *conn)
{
  long timeout_ms;
  struct SessionHandle *data = conn->data;
  curl_socket_t sock = conn->sock[SECONDARYSOCKET];
  int timeout_set = 0;

  /* if a timeout is set, use the most restrictive one */

  if (data->set.timeout > 0)
    timeout_set += 1;
  if (data->set.connecttimeout > 0)
    timeout_set += 2;

  switch (timeout_set) {
  case 1:
    timeout_ms = data->set.timeout;
    break;
  case 2:
    timeout_ms = data->set.connecttimeout;
    break;
  case 3:
    if (data->set.timeout < data->set.connecttimeout)
      timeout_ms = data->set.timeout;
    else
      timeout_ms = data->set.connecttimeout;
    break;
  default:
    timeout_ms = 60000; /* 60 seconds default timeout */
    break;
  }

  if (timeout_set > 0) {
    /* if a timeout was already set, substract elapsed time */
    timeout_ms -= Curl_tvdiff(Curl_tvnow(), conn->now);
    if(timeout_ms < 0) {
      failf(data, "Timed out before server could connect to us");
      return CURLE_OPERATION_TIMEDOUT;
    }
  }

  switch (Curl_socket_ready(sock, CURL_SOCKET_BAD, (int)timeout_ms)) {
  case -1: /* error */
    /* let's die here */
    failf(data, "Error while waiting for server connect");
    return CURLE_FTP_PORT_FAILED;
  case 0:  /* timeout */
    /* let's die here */
    failf(data, "Timeout while waiting for server connect");
    return CURLE_FTP_PORT_FAILED;
  default:
    /* we have received data here */
    {
      curl_socket_t s = CURL_SOCKET_BAD;
#ifdef ENABLE_IPV6
      struct Curl_sockaddr_storage add;
#else
      struct sockaddr_in add;
#endif
      socklen_t size = (socklen_t) sizeof(add);

      if(0 == getsockname(sock, (struct sockaddr *) &add, &size)) {
        size = sizeof(add);

        s=accept(sock, (struct sockaddr *) &add, &size);
      }
      sclose(sock); /* close the first socket */

      if (CURL_SOCKET_BAD == s) {
        /* DIE! */
        failf(data, "Error accept()ing server connect");
        return CURLE_FTP_PORT_FAILED;
      }
      infof(data, "Connection accepted from server\n");

      conn->sock[SECONDARYSOCKET] = s;
      Curl_nonblock(s, TRUE); /* enable non-blocking */
    }
    break;
  }

  return CURLE_OK;
}

/* initialize stuff to prepare for reading a fresh new response */
static void ftp_respinit(struct connectdata *conn)
{
  struct ftp_conn *ftpc = &conn->proto.ftpc;
  ftpc->nread_resp = 0;
  ftpc->linestart_resp = conn->data->state.buffer;
}

/* macro to check for a three-digit ftp status code at the start of the
   given string */
#define STATUSCODE(line) (ISDIGIT(line[0]) && ISDIGIT(line[1]) && \
                        ISDIGIT(line[2]))

/* macro to check for the last line in an FTP server response */
#define LASTLINE(line) (STATUSCODE(line) && (' ' == line[3]))

static CURLcode ftp_readresp(curl_socket_t sockfd,
                             struct connectdata *conn,
                             int *ftpcode, /* return the ftp-code if done */
                             size_t *size) /* size of the response */
{
  int perline; /* count bytes per line */
  bool keepon=TRUE;
  ssize_t gotbytes;
  char *ptr;
  struct SessionHandle *data = conn->data;
  char *buf = data->state.buffer;
  CURLcode result = CURLE_OK;
  struct ftp_conn *ftpc = &conn->proto.ftpc;
  int code = 0;

  *ftpcode = 0; /* 0 for errors or not done */

  ptr=buf + ftpc->nread_resp;

  perline= (int)(ptr-ftpc->linestart_resp); /* number of bytes in the current
                                              line, so far */
  keepon=TRUE;

  while((ftpc->nread_resp<BUFSIZE) && (keepon && !result)) {

    if(ftpc->cache) {
      /* we had data in the "cache", copy that instead of doing an actual
       * read
       *
       * ftp->cache_size is cast to int here.  This should be safe,
       * because it would have been populated with something of size
       * int to begin with, even though its datatype may be larger
       * than an int.
       */
      memcpy(ptr, ftpc->cache, (int)ftpc->cache_size);
      gotbytes = (int)ftpc->cache_size;
      free(ftpc->cache);    /* free the cache */
      ftpc->cache = NULL;   /* clear the pointer */
      ftpc->cache_size = 0; /* zero the size just in case */
    }
    else {
      int res;
#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
      enum protection_level prot = conn->data_prot;

      conn->data_prot = 0;
#endif
      res = Curl_read(conn, sockfd, ptr, BUFSIZE-ftpc->nread_resp,
                      &gotbytes);
#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
      conn->data_prot = prot;
#endif
      if(res < 0)
        /* EWOULDBLOCK */
        return CURLE_OK; /* return */

#ifdef CURL_DOES_CONVERSIONS
      if((res == CURLE_OK) && (gotbytes > 0)) {
        /* convert from the network encoding */
        result = res = Curl_convert_from_network(data, ptr, gotbytes);
        /* Curl_convert_from_network calls failf if unsuccessful */
      }
#endif /* CURL_DOES_CONVERSIONS */

      if(CURLE_OK != res)
        keepon = FALSE;
    }

    if(!keepon)
      ;
    else if(gotbytes <= 0) {
      keepon = FALSE;
      result = CURLE_RECV_ERROR;
      failf(data, "FTP response reading failed");
    }
    else {
      /* we got a whole chunk of data, which can be anything from one
       * byte to a set of lines and possible just a piece of the last
       * line */
      ssize_t i;
      int clipamount = 0;
      bool restart = FALSE;

      data->reqdata.keep.headerbytecount += gotbytes;

      ftpc->nread_resp += gotbytes;
      for(i = 0; i < gotbytes; ptr++, i++) {
        perline++;
        if(*ptr=='\n') {
          /* a newline is CRLF in ftp-talk, so the CR is ignored as
             the line isn't really terminated until the LF comes */

          /* output debug output if that is requested */
#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
          if(!conn->sec_complete)
#endif
          if(data->set.verbose)
            Curl_debug(data, CURLINFO_HEADER_IN,
                       ftpc->linestart_resp, (size_t)perline, conn);

          /*
           * We pass all response-lines to the callback function registered
           * for "headers". The response lines can be seen as a kind of
           * headers.
           */
          result = Curl_client_write(conn, CLIENTWRITE_HEADER,
                                     ftpc->linestart_resp, perline);
          if(result)
            return result;

          if(perline>3 && LASTLINE(ftpc->linestart_resp)) {
            /* This is the end of the last line, copy the last line to the
               start of the buffer and zero terminate, for old times sake (and
               krb4)! */
            char *meow;
            int n;
            for(meow=ftpc->linestart_resp, n=0; meow<ptr; meow++, n++)
              buf[n] = *meow;
            *meow=0; /* zero terminate */
            keepon=FALSE;
            ftpc->linestart_resp = ptr+1; /* advance pointer */
            i++; /* skip this before getting out */

            *size = ftpc->nread_resp; /* size of the response */
            ftpc->nread_resp = 0; /* restart */
            break;
          }
          perline=0; /* line starts over here */
          ftpc->linestart_resp = ptr+1;
        }
      }

      if(!keepon && (i != gotbytes)) {
        /* We found the end of the response lines, but we didn't parse the
           full chunk of data we have read from the server. We therefore need
           to store the rest of the data to be checked on the next invoke as
           it may actually contain another end of response already! */
        clipamount = gotbytes - i;
        restart = TRUE;
      }
      else if(keepon) {

        if((perline == gotbytes) && (gotbytes > BUFSIZE/2)) {
          /* We got an excessive line without newlines and we need to deal
             with it. First, check if it seems to start with a valid status
             code and then we keep just that in the line cache. Then throw
             away the rest. */
          infof(data, "Excessive FTP response line length received, %zd bytes."
                " Stripping\n", gotbytes);
          restart = TRUE;
          if(STATUSCODE(ftpc->linestart_resp))
            /* we copy 4 bytes since after the three-digit number there is a
               dash or a space and it is significant */
            clipamount = 4;
        }
        else if(perline && (ftpc->nread_resp > BUFSIZE/2)) {
          /* We got a large chunk of data and there's still trailing data to
             take care of, so we put that part in the "cache" and restart */
          clipamount = perline;
          restart = TRUE;
        }
      }
      else if(i == gotbytes)
        restart = TRUE;

      if(clipamount) {
        ftpc->cache_size = clipamount;
        ftpc->cache = (char *)malloc((int)ftpc->cache_size);
        if(ftpc->cache)
          memcpy(ftpc->cache, ftpc->linestart_resp, (int)ftpc->cache_size);
        else
          return CURLE_OUT_OF_MEMORY;
      }
      if(restart) {
        /* now reset a few variables to start over nicely from the start of
           the big buffer */
        ftpc->nread_resp = 0; /* start over from scratch in the buffer */
        ptr = ftpc->linestart_resp = buf;
        perline = 0;
      }

    } /* there was data */

  } /* while there's buffer left and loop is requested */

  if(!result)
    code = atoi(buf);

#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
  /* handle the security-oriented responses 6xx ***/
  /* FIXME: some errorchecking perhaps... ***/
  switch(code) {
  case 631:
    code = Curl_sec_read_msg(conn, buf, prot_safe);
    break;
  case 632:
    code = Curl_sec_read_msg(conn, buf, prot_private);
    break;
  case 633:
    code = Curl_sec_read_msg(conn, buf, prot_confidential);
    break;
  default:
    /* normal ftp stuff we pass through! */
    break;
  }
#endif

  *ftpcode=code; /* return the initial number like this */

  /* store the latest code for later retrieval */
  conn->data->info.httpcode=code;

  return result;
}

/* --- parse FTP server responses --- */

/*
 * Curl_GetFTPResponse() is a BLOCKING function to read the full response
 * from a server after a command.
 *
 */

CURLcode Curl_GetFTPResponse(ssize_t *nreadp, /* return number of bytes read */
                             struct connectdata *conn,
                             int *ftpcode) /* return the ftp-code */
{
  /*
   * We cannot read just one byte per read() and then go back to select() as
   * the OpenSSL read() doesn't grok that properly.
   *
   * Alas, read as much as possible, split up into lines, use the ending
   * line in a response or continue reading.  */

  curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
  long timeout;              /* timeout in milliseconds */
  long interval_ms;
  struct SessionHandle *data = conn->data;
  CURLcode result = CURLE_OK;
  struct ftp_conn *ftpc = &conn->proto.ftpc;
  struct timeval now = Curl_tvnow();
  size_t nread;
  int cache_skip=0;

  if (ftpcode)
    *ftpcode = 0; /* 0 for errors */

  *nreadp=0;

  while(!*ftpcode && !result) {
    /* check and reset timeout value every lap */
    if(data->set.ftp_response_timeout )
      /* if CURLOPT_FTP_RESPONSE_TIMEOUT is set, use that to determine
         remaining time.  Also, use "now" as opposed to "conn->now"
         because ftp_response_timeout is only supposed to govern
         the response for any given ftp response, not for the time
         from connect to the given ftp response. */
      timeout = data->set.ftp_response_timeout - /* timeout time */
        Curl_tvdiff(Curl_tvnow(), now); /* spent time */
    else if(data->set.timeout)
      /* if timeout is requested, find out how much remaining time we have */
      timeout = data->set.timeout - /* timeout time */
        Curl_tvdiff(Curl_tvnow(), conn->now); /* spent time */
    else
      /* Even without a requested timeout, we only wait response_time
         seconds for the full response to arrive before we bail out */
      timeout = ftpc->response_time -
        Curl_tvdiff(Curl_tvnow(), now); /* spent time */

    if(timeout <=0 ) {
      failf(data, "FTP response timeout");
      return CURLE_OPERATION_TIMEDOUT; /* already too little time */
    }

    interval_ms = 1 * 1000;  /* use 1 second timeout intervals */
    if(timeout < interval_ms)
      interval_ms = timeout;

    /*
     * Since this function is blocking, we need to wait here for input on the
     * connection and only then we call the response reading function. We do
     * timeout at least every second to make the timeout check run.
     *
     * A caution here is that the ftp_readresp() function has a cache that may
     * contain pieces of a response from the previous invoke and we need to
     * make sure we don't just wait for input while there is unhandled data in
     * that cache. But also, if the cache is there, we call ftp_readresp() and
     * the cache wasn't good enough to continue we must not just busy-loop
     * around this function.
     *
     */

    if(ftpc->cache && (cache_skip < 2)) {
      /*
       * There's a cache left since before. We then skipping the wait for
       * socket action, unless this is the same cache like the previous round
       * as then the cache was deemed not enough to act on and we then need to
       * wait for more data anyway.
       */
    }
    else {
      switch (Curl_socket_ready(sockfd, CURL_SOCKET_BAD, (int)interval_ms)) {
      case -1: /* select() error, stop reading */
        failf(data, "FTP response aborted due to select/poll error: %d",
              SOCKERRNO);
        return CURLE_RECV_ERROR;

      case 0: /* timeout */
        if(Curl_pgrsUpdate(conn))
          return CURLE_ABORTED_BY_CALLBACK;
        continue; /* just continue in our loop for the timeout duration */

      default: /* for clarity */
        break;
      }
    }
    result = ftp_readresp(sockfd, conn, ftpcode, &nread);
    if(result)
      break;

    if(!nread && ftpc->cache)
      /* bump cache skip counter as on repeated skips we must wait for more
         data */
      cache_skip++;
    else
      /* when we got data or there is no cache left, we reset the cache skip
         counter */
      cache_skip=0;

    *nreadp += nread;

  } /* while there's buffer left and loop is requested */

  return result;
}

/* This is the ONLY way to change FTP state! */
static void state(struct connectdata *conn,
                  ftpstate newstate)
{
#if defined(CURLDEBUG) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  /* for debug purposes */
  static const char * const names[]={
    "STOP",
    "WAIT220",
    "AUTH",
    "USER",
    "PASS",
    "ACCT",
    "PBSZ",
    "PROT",
    "CCC",
    "PWD",
    "QUOTE",
    "RETR_PREQUOTE",
    "STOR_PREQUOTE",
    "POSTQUOTE",
    "CWD",
    "MKD",
    "MDTM",
    "TYPE",
    "LIST_TYPE",
    "RETR_TYPE",
    "STOR_TYPE",
    "SIZE",
    "RETR_SIZE",
    "STOR_SIZE",
    "REST",
    "RETR_REST",
    "PORT",
    "PASV",
    "LIST",
    "RETR",
    "STOR",
    "QUIT"
  };
#endif
  struct ftp_conn *ftpc = &conn->proto.ftpc;
#if defined(CURLDEBUG) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  if(ftpc->state != newstate)
    infof(conn->data, "FTP %p state change from %s to %s\n",
          ftpc, names[ftpc->state], names[newstate]);
#endif
  ftpc->state = newstate;
}

static CURLcode ftp_state_user(struct connectdata *conn)
{
  CURLcode result;
  struct FTP *ftp = conn->data->reqdata.proto.ftp;
  /* send USER */
  NBFTPSENDF(conn, "USER %s", ftp->user?ftp->user:"");

  state(conn, FTP_USER);
  conn->data->state.ftp_trying_alternative = FALSE;

  return CURLE_OK;
}

static CURLcode ftp_state_pwd(struct connectdata *conn)
{
  CURLcode result;

  /* send PWD to discover our entry point */
  NBFTPSENDF(conn, "PWD", NULL);
  state(conn, FTP_PWD);

  return CURLE_OK;
}

/* For the FTP "protocol connect" and "doing" phases only */
static int Curl_ftp_getsock(struct connectdata *conn,
                            curl_socket_t *socks,
                            int numsocks)
{
  struct ftp_conn *ftpc = &conn->proto.ftpc;

  if(!numsocks)
    return GETSOCK_BLANK;

  socks[0] = conn->sock[FIRSTSOCKET];

  if(ftpc->sendleft) {
    /* write mode */
    return GETSOCK_WRITESOCK(0);
  }

  /* read mode */
  return GETSOCK_READSOCK(0);
}

/* This is called after the FTP_QUOTE state is passed.

   ftp_state_cwd() sends the range of PWD commands to the server to change to
   the correct directory. It may also need to send MKD commands to create
   missing ones, if that option is enabled.
*/
static CURLcode ftp_state_cwd(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct ftp_conn *ftpc = &conn->proto.ftpc;

  if(ftpc->cwddone)
    /* already done and fine */
    result = ftp_state_post_cwd(conn);
  else {
    ftpc->count2 = 0;
    if (conn->bits.reuse && ftpc->entrypath) {
      /* This is a re-used connection. Since we change directory to where the
         transfer is taking place, we must first get back to the original dir
         where we ended up after login: */
      ftpc->count1 = 0; /* we count this as the first path, then we add one
                          for all upcoming ones in the ftp->dirs[] array */
      NBFTPSENDF(conn, "CWD %s", ftpc->entrypath);
      state(conn, FTP_CWD);
    }
    else {
      if(ftpc->dirdepth) {
        ftpc->count1 = 1;
        /* issue the first CWD, the rest is sent when the CWD responses are
           received... */
        NBFTPSENDF(conn, "CWD %s", ftpc->dirs[ftpc->count1 -1]);
        state(conn, FTP_CWD);
      }
      else {
        /* No CWD necessary */
        result = ftp_state_post_cwd(conn);
      }
    }
  }
  return result;
}

typedef enum {
  EPRT,
  PORT,
  DONE
} ftpport;

static CURLcode ftp_state_use_port(struct connectdata *conn,
                                   ftpport fcmd) /* start with this */

{
  CURLcode result = CURLE_OK;
  struct ftp_conn *ftpc = &conn->proto.ftpc;
  struct SessionHandle *data=conn->data;
  curl_socket_t portsock= CURL_SOCKET_BAD;
  char myhost[256] = "";

#ifdef ENABLE_IPV6
  /******************************************************************
   * IPv6-specific section
   */
  struct Curl_sockaddr_storage ss;
  struct addrinfo *res, *ai;
  socklen_t sslen;
  char hbuf[NI_MAXHOST];
  struct sockaddr *sa=(struct sockaddr *)&ss;
  char tmp[1024];
  static const char * const mode[] = { "EPRT", "PORT", NULL };
  int rc;
  int error;
  char *host=NULL;
  struct Curl_dns_entry *h=NULL;
  unsigned short port = 0;

  /* Step 1, figure out what address that is requested */

  if(data->set.str[STRING_FTPPORT] &&
     (strlen(data->set.str[STRING_FTPPORT]) > 1)) {
    /* attempt to get the address of the given interface name */
    if(!Curl_if2ip(data->set.str[STRING_FTPPORT], hbuf, sizeof(hbuf)))
      /* not an interface, use the given string as host name instead */
      host = data->set.str[STRING_FTPPORT];
    else
      host = hbuf; /* use the hbuf for host name */
  } /* data->set.ftpport */

  if(!host) {
    /* not an interface and not a host name, get default by extracting
       the IP from the control connection */

    sslen = sizeof(ss);
    if (getsockname(conn->sock[FIRSTSOCKET], (struct sockaddr *)&ss, &sslen)) {
      failf(data, "getsockname() failed: %s",
          Curl_strerror(conn, SOCKERRNO) );
      return CURLE_FTP_PORT_FAILED;
    }

    if (sslen > (socklen_t)sizeof(ss))
      sslen = sizeof(ss);
    rc = getnameinfo((struct sockaddr *)&ss, sslen, hbuf, sizeof(hbuf), NULL,
                     0, NIFLAGS);
    if(rc) {
      failf(data, "getnameinfo() returned %d \n", rc);
      return CURLE_FTP_PORT_FAILED;
    }
    host = hbuf; /* use this host name */
  }

  rc = Curl_resolv(conn, host, 0, &h);
  if(rc == CURLRESOLV_PENDING)
    rc = Curl_wait_for_resolv(conn, &h);
  if(h) {
    res = h->addr;
    /* when we return from this function, we can forget about this entry
       to we can unlock it now already */
    Curl_resolv_unlock(data, h);
  } /* (h) */
  else
    res = NULL; /* failure! */


  /* step 2, create a socket for the requested address */

  portsock = CURL_SOCKET_BAD;
  error = 0;
  for (ai = res; ai; ai = ai->ai_next) {
    /*
     * Workaround for AIX5 getaddrinfo() problem (it doesn't set ai_socktype):
     */
    if (ai->ai_socktype == 0)
      ai->ai_socktype = conn->socktype;

    portsock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
    if (portsock == CURL_SOCKET_BAD) {
      error = SOCKERRNO;
      continue;
    }
    break;
  }
  if(!ai) {
    failf(data, "socket failure: %s", Curl_strerror(conn, error));
    return CURLE_FTP_PORT_FAILED;
  }

  /* step 3, bind to a suitable local address */

  /* Try binding the given address. */
  if (bind(portsock, ai->ai_addr, ai->ai_addrlen)) {

    /* It failed. Bind the address used for the control connection instead */
    sslen = sizeof(ss);
    if (getsockname(conn->sock[FIRSTSOCKET],
                    (struct sockaddr *)sa, &sslen)) {
      failf(data, "getsockname() failed: %s",
          Curl_strerror(conn, SOCKERRNO) );
      sclose(portsock);
      return CURLE_FTP_PORT_FAILED;
    }

    /* set port number to zero to make bind() pick "any" */
    if(((struct sockaddr *)sa)->sa_family == AF_INET)
      ((struct sockaddr_in *)sa)->sin_port=0;
    else
      ((struct sockaddr_in6 *)sa)->sin6_port =0;

    if (sslen > (socklen_t)sizeof(ss))