ftp.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2013, 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.
 *
 ***************************************************************************/

#include "curl_setup.h"

#ifndef CURL_DISABLE_FTP

#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

#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 "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"
#include "fileinfo.h"
#include "ftplistparser.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 "inet_ntop.h"
#include "inet_pton.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"
#include "rawstr.h"
#include "speedcheck.h"
#include "warnless.h"
#include "http_proxy.h"
#include "non-ascii.h"

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

#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"

#ifndef NI_MAXHOST
#define NI_MAXHOST 1025
#endif
#ifndef INET_ADDRSTRLEN
#define INET_ADDRSTRLEN 16
#endif

#ifdef CURL_DISABLE_VERBOSE_STRINGS
#define ftp_pasv_verbose(a,b,c,d)  Curl_nop_stmt
#endif

/* Local API functions */
#ifndef DEBUGBUILD
static void _state(struct connectdata *conn,
                   ftpstate newstate);
#define state(x,y) _state(x,y)
#else
static void _state(struct connectdata *conn,
                   ftpstate newstate,
                   int lineno);
#define state(x,y) _state(x,y,__LINE__)
#endif

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 ftp_do(struct connectdata *conn, bool *done);
static CURLcode ftp_done(struct connectdata *conn,
                         CURLcode, bool premature);
static CURLcode ftp_connect(struct connectdata *conn, bool *done);
static CURLcode ftp_disconnect(struct connectdata *conn, bool dead_connection);
static CURLcode ftp_do_more(struct connectdata *conn, bool *completed);
static CURLcode ftp_multi_statemach(struct connectdata *conn, bool *done);
static int ftp_getsock(struct connectdata *conn, curl_socket_t *socks,
                       int numsocks);
static int ftp_domore_getsock(struct connectdata *conn, curl_socket_t *socks,
                              int numsocks);
static CURLcode ftp_doing(struct connectdata *conn,
                          bool *dophase_done);
static CURLcode ftp_setup_connection(struct connectdata * conn);

static CURLcode init_wc_data(struct connectdata *conn);
static CURLcode wc_statemach(struct connectdata *conn);

static void wc_data_dtor(void *ptr);

static CURLcode ftp_state_post_retr_size(struct connectdata *conn,
                                         curl_off_t filesize);

static CURLcode ftp_readresp(curl_socket_t sockfd,
                             struct pingpong *pp,
                             int *ftpcode,
                             size_t *size);
static CURLcode ftp_dophase_done(struct connectdata *conn,
                                 bool connected);

/* easy-to-use macro: */
#define PPSENDF(x,y,z)  if((result = Curl_pp_sendf(x,y,z)) != CURLE_OK) \
                              return result


/*
 * FTP protocol handler.
 */

const struct Curl_handler Curl_handler_ftp = {
  "FTP",                           /* scheme */
  ftp_setup_connection,            /* setup_connection */
  ftp_do,                          /* do_it */
  ftp_done,                        /* done */
  ftp_do_more,                     /* do_more */
  ftp_connect,                     /* connect_it */
  ftp_multi_statemach,             /* connecting */
  ftp_doing,                       /* doing */
  ftp_getsock,                     /* proto_getsock */
  ftp_getsock,                     /* doing_getsock */
  ftp_domore_getsock,              /* domore_getsock */
  ZERO_NULL,                       /* perform_getsock */
  ftp_disconnect,                  /* disconnect */
  ZERO_NULL,                       /* readwrite */
  PORT_FTP,                        /* defport */
  CURLPROTO_FTP,                   /* protocol */
  PROTOPT_DUAL | PROTOPT_CLOSEACTION | PROTOPT_NEEDSPWD
  | PROTOPT_NOURLQUERY /* flags */
};


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

const struct Curl_handler Curl_handler_ftps = {
  "FTPS",                          /* scheme */
  ftp_setup_connection,            /* setup_connection */
  ftp_do,                          /* do_it */
  ftp_done,                        /* done */
  ftp_do_more,                     /* do_more */
  ftp_connect,                     /* connect_it */
  ftp_multi_statemach,             /* connecting */
  ftp_doing,                       /* doing */
  ftp_getsock,                     /* proto_getsock */
  ftp_getsock,                     /* doing_getsock */
  ftp_domore_getsock,              /* domore_getsock */
  ZERO_NULL,                       /* perform_getsock */
  ftp_disconnect,                  /* disconnect */
  ZERO_NULL,                       /* readwrite */
  PORT_FTPS,                       /* defport */
  CURLPROTO_FTP | CURLPROTO_FTPS,  /* protocol */
  PROTOPT_SSL | PROTOPT_DUAL | PROTOPT_CLOSEACTION |
  PROTOPT_NEEDSPWD | PROTOPT_NOURLQUERY /* flags */
};
#endif

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

static 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,                            /* domore_getsock */
  ZERO_NULL,                            /* perform_getsock */
  ZERO_NULL,                            /* disconnect */
  ZERO_NULL,                            /* readwrite */
  PORT_FTP,                             /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};


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

static 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,                            /* domore_getsock */
  ZERO_NULL,                            /* perform_getsock */
  ZERO_NULL,                            /* disconnect */
  ZERO_NULL,                            /* readwrite */
  PORT_FTPS,                            /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};
#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 ftp_conn *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;
    ftpc->dirdepth = 0;
  }
  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 ((NULL != strchr(string, '\r')) ||
          (NULL != strchr(string, '\n'))) ? TRUE : FALSE;
}

/***********************************************************************
 *
 * AcceptServerConnect()
 *
 * After connection request is received from the server this function is
 * called to accept the connection and close the listening socket
 *
 */
static CURLcode AcceptServerConnect(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  curl_socket_t sock = conn->sock[SECONDARYSOCKET];
  curl_socket_t s = CURL_SOCKET_BAD;
#ifdef ENABLE_IPV6
  struct Curl_sockaddr_storage add;
#else
  struct sockaddr_in add;
#endif
  curl_socklen_t size = (curl_socklen_t) sizeof(add);

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

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

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

  conn->sock[SECONDARYSOCKET] = s;
  curlx_nonblock(s, TRUE); /* enable non-blocking */
  conn->sock_accepted[SECONDARYSOCKET] = TRUE;

  if(data->set.fsockopt) {
    int error = 0;

    /* activate callback for setting socket options */
    error = data->set.fsockopt(data->set.sockopt_client,
                               s,
                               CURLSOCKTYPE_ACCEPT);

    if(error) {
      Curl_closesocket(conn, s); /* close the socket and bail out */
      conn->sock[SECONDARYSOCKET] = CURL_SOCKET_BAD;
      return CURLE_ABORTED_BY_CALLBACK;
    }
  }

  return CURLE_OK;

}

/*
 * ftp_timeleft_accept() returns the amount of milliseconds left allowed for
 * waiting server to connect. If the value is negative, the timeout time has
 * already elapsed.
 *
 * The start time is stored in progress.t_acceptdata - as set with
 * Curl_pgrsTime(..., TIMER_STARTACCEPT);
 *
 */
static long ftp_timeleft_accept(struct SessionHandle *data)
{
  long timeout_ms = DEFAULT_ACCEPT_TIMEOUT;
  long other;
  struct timeval now;

  if(data->set.accepttimeout > 0)
    timeout_ms = data->set.accepttimeout;

  now = Curl_tvnow();

  /* check if the generic timeout possibly is set shorter */
  other =  Curl_timeleft(data, &now, FALSE);
  if(other && (other < timeout_ms))
    /* note that this also works fine for when other happens to be negative
       due to it already having elapsed */
    timeout_ms = other;
  else {
    /* subtract elapsed time */
    timeout_ms -= Curl_tvdiff(now, data->progress.t_acceptdata);
    if(!timeout_ms)
      /* avoid returning 0 as that means no timeout! */
      return -1;
  }

  return timeout_ms;
}


/***********************************************************************
 *
 * ReceivedServerConnect()
 *
 * After allowing server to connect to us from data port, this function
 * checks both data connection for connection establishment and ctrl
 * connection for a negative response regarding a failure in connecting
 *
 */
static CURLcode ReceivedServerConnect(struct connectdata *conn, bool *received)
{
  struct SessionHandle *data = conn->data;
  curl_socket_t ctrl_sock = conn->sock[FIRSTSOCKET];
  curl_socket_t data_sock = conn->sock[SECONDARYSOCKET];
  struct ftp_conn *ftpc = &conn->proto.ftpc;
  struct pingpong *pp = &ftpc->pp;
  int result;
  long timeout_ms;
  ssize_t nread;
  int ftpcode;

  *received = FALSE;

  timeout_ms = ftp_timeleft_accept(data);
  infof(data, "Checking for server connect\n");
  if(timeout_ms < 0) {
    /* if a timeout was already reached, bail out */
    failf(data, "Accept timeout occurred while waiting server connect");
    return CURLE_FTP_ACCEPT_TIMEOUT;
  }

  /* First check whether there is a cached response from server */
  if(pp->cache_size && pp->cache && pp->cache[0] > '3') {
    /* Data connection could not be established, let's return */
    infof(data, "There is negative response in cache while serv connect\n");
    Curl_GetFTPResponse(&nread, conn, &ftpcode);
    return CURLE_FTP_ACCEPT_FAILED;
  }

  result = Curl_socket_check(ctrl_sock, data_sock, CURL_SOCKET_BAD, 0);

  /* see if the connection request is already here */
  switch (result) {
  case -1: /* error */
    /* let's die here */
    failf(data, "Error while waiting for server connect");
    return CURLE_FTP_ACCEPT_FAILED;
  case 0:  /* Server connect is not received yet */
    break; /* loop */
  default:

    if(result & CURL_CSELECT_IN2) {
      infof(data, "Ready to accept data connection from server\n");
      *received = TRUE;
    }
    else if(result & CURL_CSELECT_IN) {
      infof(data, "Ctrl conn has data while waiting for data conn\n");
      Curl_GetFTPResponse(&nread, conn, &ftpcode);

      if(ftpcode/100 > 3)
        return CURLE_FTP_ACCEPT_FAILED;

      return CURLE_FTP_WEIRD_SERVER_REPLY;
    }

    break;
  } /* switch() */

  return CURLE_OK;
}


/***********************************************************************
 *
 * InitiateTransfer()
 *
 * After connection from server is accepted this function is called to
 * setup transfer parameters and initiate the data transfer.
 *
 */
static CURLcode InitiateTransfer(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  struct FTP *ftp = data->state.proto.ftp;
  CURLcode result = CURLE_OK;

  if(conn->ssl[SECONDARYSOCKET].use) {
    /* since we only have a plaintext TCP connection here, we must now
     * do the TLS stuff */
    infof(data, "Doing the SSL/TLS handshake on the data stream\n");
    result = Curl_ssl_connect(conn, SECONDARYSOCKET);
    if(result)
      return result;
  }

  if(conn->proto.ftpc.state_saved == FTP_STOR) {
    *(ftp->bytecountp)=0;

    /* When we know we're uploading a specified file, we can get the file
       size prior to the actual upload. */

    Curl_pgrsSetUploadSize(data, data->set.infilesize);

    /* set the SO_SNDBUF for the secondary socket for those who need it */
    Curl_sndbufset(conn->sock[SECONDARYSOCKET]);

    Curl_setup_transfer(conn, -1, -1, FALSE, NULL, /* no download */
                        SECONDARYSOCKET, ftp->bytecountp);
  }
  else {
    /* FTP download: */
    Curl_setup_transfer(conn, SECONDARYSOCKET,
                        conn->proto.ftpc.retr_size_saved, FALSE,
                        ftp->bytecountp, -1, NULL); /* no upload here */
  }

  conn->proto.ftpc.pp.pending_resp = TRUE; /* expect server response */
  state(conn, FTP_STOP);

  return CURLE_OK;
}

/***********************************************************************
 *
 * AllowServerConnect()
 *
 * When we've issue the PORT command, we have told the server to connect to
 * us. This function checks whether data connection is established if so it is
 * accepted.
 *
 */
static CURLcode AllowServerConnect(struct connectdata *conn, bool *connected)
{
  struct SessionHandle *data = conn->data;
  long timeout_ms;
  CURLcode ret = CURLE_OK;

  *connected = FALSE;
  infof(data, "Preparing for accepting server on data port\n");

  /* Save the time we start accepting server connect */
  Curl_pgrsTime(data, TIMER_STARTACCEPT);

  timeout_ms = ftp_timeleft_accept(data);
  if(timeout_ms < 0) {
    /* if a timeout was already reached, bail out */
    failf(data, "Accept timeout occurred while waiting server connect");
    return CURLE_FTP_ACCEPT_TIMEOUT;
  }

  /* see if the connection request is already here */
  ret = ReceivedServerConnect(conn, connected);
  if(ret)
    return ret;

  if(*connected) {
    ret = AcceptServerConnect(conn);
    if(ret)
      return ret;

    ret = InitiateTransfer(conn);
    if(ret)
      return ret;
  }
  else {
    /* Add timeout to multi handle and break out of the loop */
    if(ret == CURLE_OK && *connected == FALSE) {
      if(data->set.accepttimeout > 0)
        Curl_expire(data, data->set.accepttimeout);
      else
        Curl_expire(data, DEFAULT_ACCEPT_TIMEOUT);
    }
  }

  return ret;
}

/* 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 bool ftp_endofresp(struct connectdata *conn, char *line, size_t len,
                          int *code)
{
  (void)conn;

  if((len > 3) && LASTLINE(line)) {
    *code = curlx_sltosi(strtol(line, NULL, 10));
    return TRUE;
  }

  return FALSE;
}

static CURLcode ftp_readresp(curl_socket_t sockfd,
                             struct pingpong *pp,
                             int *ftpcode, /* return the ftp-code if done */
                             size_t *size) /* size of the response */
{
  struct connectdata *conn = pp->conn;
  struct SessionHandle *data = conn->data;
#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
  char * const buf = data->state.buffer;
#endif
  CURLcode result = CURLE_OK;
  int code;

  result = Curl_pp_readresp(sockfd, pp, &code, size);

#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

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

  if(ftpcode)
    *ftpcode = code;

  if(421 == code) {
    /* 421 means "Service not available, closing control connection." and FTP
     * servers use it to signal that idle session timeout has been exceeded.
     * If we ignored the response, it could end up hanging in some cases.
     *
     * This response code can come at any point so having it treated
     * generically is a good idea.
     */
    infof(data, "We got a 421 - timeout!\n");
    state(conn, FTP_STOP);
    return CURLE_OPERATION_TIMEDOUT;
  }

  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 pingpong *pp = &ftpc->pp;
  size_t nread;
  int cache_skip=0;
  int value_to_be_ignored=0;

  if(ftpcode)
    *ftpcode = 0; /* 0 for errors */
  else
    /* make the pointer point to something for the rest of this function */
    ftpcode = &value_to_be_ignored;

  *nreadp=0;

  while(!*ftpcode && !result) {
    /* check and reset timeout value every lap */
    timeout = Curl_pp_state_timeout(pp);

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

    interval_ms = 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(pp->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, 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, pp, ftpcode, &nread);
    if(result)
      break;

    if(!nread && pp->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 */

  pp->pending_resp = FALSE;

  return result;
}

/* This is the ONLY way to change FTP state! */
static void _state(struct connectdata *conn,
                   ftpstate newstate
#ifdef DEBUGBUILD
                   , int lineno
#endif
  )
{
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  /* for debug purposes */
  static const char * const names[]={
    "STOP",
    "WAIT220",
    "AUTH",
    "USER",
    "PASS",
    "ACCT",
    "PBSZ",
    "PROT",
    "CCC",
    "PWD",
    "SYST",
    "NAMEFMT",
    "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",
    "PRET",
    "PASV",
    "LIST",
    "RETR",
    "STOR",
    "QUIT"
  };
#endif
  struct ftp_conn *ftpc = &conn->proto.ftpc;
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  if(ftpc->state != newstate)
    infof(conn->data, "FTP %p (line %d) state change from %s to %s\n",
          (void *)ftpc, lineno, names[ftpc->state], names[newstate]);
#endif
  ftpc->state = newstate;
}

static CURLcode ftp_state_user(struct connectdata *conn)
{
  CURLcode result;
  struct FTP *ftp = conn->data->state.proto.ftp;
  /* send USER */
  PPSENDF(&conn->proto.ftpc.pp, "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 */
  PPSENDF(&conn->proto.ftpc.pp, "%s", "PWD");
  state(conn, FTP_PWD);

  return CURLE_OK;
}

/* For the FTP "protocol connect" and "doing" phases only */
static int ftp_getsock(struct connectdata *conn,
                       curl_socket_t *socks,
                       int numsocks)
{
  return Curl_pp_getsock(&conn->proto.ftpc.pp, socks, numsocks);
}

/* For the FTP "DO_MORE" phase only */
static int ftp_domore_getsock(struct connectdata *conn, curl_socket_t *socks,
                              int numsocks)
{
  struct ftp_conn *ftpc = &conn->proto.ftpc;

  if(!numsocks)
    return GETSOCK_BLANK;

  /* When in DO_MORE state, we could be either waiting for us to connect to a
     remote site, or we could wait for that site to connect to us. Or just
     handle ordinary commands.

     When waiting for a connect, we can be in FTP_STOP state (or we're in
     FTP_STOR when we do an upload) and then we wait for the secondary socket
     to become writeable. . If we're in another state, we're still handling
     commands on the control (primary) connection.

  */

  switch(ftpc->state) {
  case FTP_STOP:
  case FTP_STOR:
    break;
  default:
    return Curl_pp_getsock(&conn->proto.ftpc.pp, socks, numsocks);
  }

  socks[0] = conn->sock[SECONDARYSOCKET];
  if(ftpc->wait_data_conn) {
    socks[1] = conn->sock[FIRSTSOCKET];
    return GETSOCK_READSOCK(0) | GETSOCK_READSOCK(1);
  }

  return GETSOCK_READSOCK(0);
}

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

   ftp_state_cwd() sends the range of CWD 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; /* count2 counts failed CWDs */

    /* count3 is set to allow a MKD to fail once. In the case when first CWD
       fails and then MKD fails (due to another session raced it to create the
       dir) this then allows for a second try to CWD to it */
    ftpc->count3 = (conn->data->set.ftp_create_missing_dirs==2)?1:0;

    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 */
      PPSENDF(&conn->proto.ftpc.pp, "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... */
        PPSENDF(&conn->proto.ftpc.pp, "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] = "";

  struct Curl_sockaddr_storage ss;
  Curl_addrinfo *res, *ai;
  curl_socklen_t sslen;
  char hbuf[NI_MAXHOST];
  struct sockaddr *sa=(struct sockaddr *)&ss;
  struct sockaddr_in * const sa4 = (void *)sa;
#ifdef ENABLE_IPV6
  struct sockaddr_in6 * const sa6 = (void *)sa;
#endif
  char tmp[1024];
  static const char mode[][5] = { "EPRT", "PORT" };
  int rc;
  int error;
  char *host = NULL;
  char *string_ftpport = data->set.str[STRING_FTPPORT];
  struct Curl_dns_entry *h=NULL;
  unsigned short port_min = 0;
  unsigned short port_max = 0;
  unsigned short port;
  bool possibly_non_local = TRUE;

  char *addr = NULL;

  /* Step 1, figure out what is requested,
   * accepted format :
   * (ipv4|ipv6|domain|interface)?(:port(-range)?)?
   */

  if(data->set.str[STRING_FTPPORT] &&
     (strlen(data->set.str[STRING_FTPPORT]) > 1)) {

#ifdef ENABLE_IPV6