ftplib.c

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/***************************************************************************/
/* ftplib.c - callable ftp access routines                                 */
/* Copyright (C) 1996-2000 Thomas Pfau, pfau@cnj.digex.net                 */
/*  73 Catherine Street, South Bound Brook, NJ, 08880                      */
/*                                                                         */
/* This library is free software; you can redistribute it and/or           */
/* modify it under the terms of the GNU Library General Public             */
/* License as published by the Free Software Foundation; either            */
/* version 2 of the License, or (at your option) any later version.        */
/*                                                                         */
/* This library is distributed in the hope that it will be useful,         */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of          */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU       */
/* Library General Public License for more details.                        */
/*                                                                         */
/* You should have received a copy of the GNU Library General Public       */
/* License along with this progam; if not, write to the                    */
/* Free Software Foundation, Inc., 59 Temple Place - Suite 330,            */
/* Boston, MA 02111-1307, USA.                                             */
/*                                                                         */
/***************************************************************************/
// changes made by Lorn Potter <llornkcor@handhelds.org>
// 
#if defined(__unix__) || defined(__VMS)
#include <unistd.h>
#endif
#if defined(_WIN32)
#include <windows.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>

#if defined(__unix__)

#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>

#elif defined(VMS)

#include <types.h>
#include <socket.h>
#include <in.h>
#include <netdb.h>
#include <inet.h>

#elif defined(_WIN32)

#include <winsock.h>

#ifndef socklen_t
#define socklen_t int
#endif

#endif

#define BUILDING_LIBRARY
#include "ftplib.h"

#if defined(_WIN32)
#define SETSOCKOPT_OPTVAL_TYPE (const char *)
#else
#define SETSOCKOPT_OPTVAL_TYPE (void *)
#endif

#define FTPLIB_BUFSIZ 8192
#define ACCEPT_TIMEOUT 10

#define FTPLIB_CONTROL 0
#define FTPLIB_READ 1
#define FTPLIB_WRITE 2

#if !defined FTPLIB_DEFMODE
#define FTPLIB_DEFMODE FTPLIB_PASSIVE
#endif

#ifdef ANDROID
#include <android/log.h>
#define perror(M) __android_log_write(ANDROID_LOG_DEBUG, "perror_ftplib", M)
#define lllog(M) __android_log_write(ANDROID_LOG_DEBUG, "ftplib", M)
#else
#define lllog(M) fprintf(stderr, M);
#endif

void *mymemccpy(void *dst, const void *src, int c, size_t n)
{
    char*        q     = dst;
    const char*  p     = src;
    const char*  p_end = p + n;
    char         ch    = ~(char)c;  /* ensure ch != c */

    for (;;) {
        if (ch == c || p >= p_end) break;
        *q++ = ch = *p++;

        if (ch == c || p >= p_end) break;
        *q++ = ch = *p++;

        if (ch == c || p >= p_end) break;
        *q++ = ch = *p++;

        if (ch == c || p >= p_end) break;
        *q++ = ch = *p++;
    }

    if (p >= p_end && ch != c)
        return NULL;

    return q;
}


struct NetBuf {
    char *cput,*cget;
    int handle;
    int cavail,cleft;
    char *buf;
    int dir;
    netbuf *ctrl;
    netbuf *data;    
    int cmode;
    struct timeval idletime;
    FtpCallback idlecb;
    FtpCallbackWriter writercb;
    void *idlearg;
    void *writerarg;
    int xfered;
    int cbbytes;
    int xfered1;
    char response[256];
};

#if 0
static char *version =
"ftplib Release 3.1-1 9/16/00, copyright 1996-2000 Thomas Pfau";
#endif

GLOBALDEF int ftplib_debug = 0;

#if defined(__unix__) || defined(VMS)
#define net_read read
#define net_write write
#define net_close close
#elif defined(_WIN32)
#define net_read(x,y,z) recv(x,y,z,0)
#define net_write(x,y,z) send(x,y,z,0)
#define net_close closesocket
#endif

#if defined(NEED_MEMCCPY)
/*
 * VAX C does not supply a memccpy routine so I provide my own
 */
void *memccpy(void *dest, const void *src, int c, size_t n)
{
    int i=0;
    const unsigned char *ip=src;
    unsigned char *op=dest;

    while (i < n)
      {
          if ((*op++ = *ip++) == c)
              break;
          i++;
      }
    if (i == n)
        return NULL;
    return op;
}
#endif
#if defined(NEED_STRDUP)
/*
 * strdup - return a malloc'ed copy of a string
 */
char *strdup(const char *src)
{
    int l = strlen(src) + 1;
    char *dst = malloc(l);
    if (dst)
        strcpy(dst,src);
    return dst;
}
#endif

/*
 * socket_wait - wait for socket to receive or flush data
 *
 * return 1 if no user callback, otherwise, return value returned by
 * user callback
 */
static int socket_wait(netbuf *ctl)
{
    fd_set fd,*rfd = NULL,*wfd = NULL;
    struct timeval tv;
    int rv = 0;
    if ((ctl->dir == FTPLIB_CONTROL) || (ctl->idlecb == NULL))
        return 1;
    if (ctl->dir == FTPLIB_WRITE)
        wfd = &fd;
    else
        rfd = &fd;
    FD_ZERO(&fd);
    do
      {
          FD_SET(ctl->handle,&fd);
          tv = ctl->idletime;
          rv = select(ctl->handle+1, rfd, wfd, NULL, &tv);
          if (rv == -1)
            {
                rv = 0;
                strncpy(ctl->ctrl->response, strerror(errno),
                        sizeof(ctl->ctrl->response));
                break;
            }
          else if (rv > 0)
            {
                rv = 1;
                break;
            }
      }
    while ((rv = ctl->idlecb(ctl, ctl->xfered, ctl->idlearg)));
    return rv;
}

/*
 * read a line of text
 *
 * return -1 on error or bytecount
 */
static int readline(char *buf,int max,netbuf *ctl)
{
    int x,retval = 0;
    char *end,*bp=buf;
    int eof = 0;

    if ((ctl->dir != FTPLIB_CONTROL) && (ctl->dir != FTPLIB_READ))
        return -1;
    if (max == 0)
        return 0;
    do
      {
          if (ctl->cavail > 0)
            {
                x = (max >= ctl->cavail) ? ctl->cavail : max-1;
                end = mymemccpy(bp,ctl->cget,'\n',x);
                if (end != NULL) {
                    x = (int)(end - bp);
             }
                retval += x;
                bp += x;
                *bp = '\0';
                max -= x;
                ctl->cget += x;
                ctl->cavail -= x;
                if (end != NULL)
                  {
                      bp -= 2;
                      if (strcmp(bp,"\r\n") == 0)
                        {
                            *bp++ = '\n';
                            *bp++ = '\0';
                            --retval;
                        }
                      break;
                  }
            }
          if (max == 1)
            {
                *buf = '\0';
                break;
            }
          if (ctl->cput == ctl->cget)
            {
                ctl->cput = ctl->cget = ctl->buf;
                ctl->cavail = 0;
                ctl->cleft = FTPLIB_BUFSIZ;
            }
          if (eof)
            {
                if (retval == 0)
                    retval = -1;
                break;
            }
          if (!socket_wait(ctl))
              return retval;
          if ((x = (int)net_read(ctl->handle,ctl->cput,ctl->cleft)) == -1)
            {
                perror("read");
                retval = -1;
                break;
            }
          if (x == 0) //< ctl->cleft)
              eof = 1;
          ctl->cleft -= x;
          ctl->cavail += x;
          ctl->cput += x;
      }
    while (1);
    return retval;
}

/*
 * write lines of text
 *
 * return -1 on error or bytecount
 */
static int writeline(char *buf, int len, netbuf *nData)
{
    int x, nb=0, w;
    char *ubp = buf, *nbp;
    char lc=0;

    if (nData->dir != FTPLIB_WRITE)
        return -1;
    nbp = nData->buf;
    for (x=0; x < len; x++)
      {
          if ((*ubp == '\n') && (lc != '\r'))
            {
                if (nb == FTPLIB_BUFSIZ)
                  {
                      if (!socket_wait(nData))
                          return x;
                      w = (int)net_write(nData->handle, nbp, FTPLIB_BUFSIZ);
                      if (w != FTPLIB_BUFSIZ)
                        {
                            if (ftplib_debug > 1)
                                printf("net_write(1) returned %d, errno = %d\n", w, errno);
                            return(-1);
                        }
                      nb = 0;
                  }
                nbp[nb++] = '\r';
            }
          if (nb == FTPLIB_BUFSIZ)
            {
                if (!socket_wait(nData))
                    return x;
                w = (int)net_write(nData->handle, nbp, FTPLIB_BUFSIZ);
                if (w != FTPLIB_BUFSIZ)
                  {
                        if (ftplib_debug > 1)
                            printf("net_write(2) returned %d, errno = %d\n", w, errno);
                      return(-1);
                  }
                nb = 0;
            }
          nbp[nb++] = lc = *ubp++;
      }
    if (nb)
      {
          if (!socket_wait(nData))
              return x;
          w = (int)net_write(nData->handle, nbp, nb);
          if (w != nb)
            {
                if (ftplib_debug > 1)
                    printf("net_write(3) returned %d, errno = %d\n", w, errno);
                return(-1);
            }
      }
    return len;
}

/*
 * read a response from the server
 *
 * return 0 if first char doesn't match
 * return 1 if first char matches
 */
static int readresp(char c, netbuf *nControl)
{
    char match[5];
    if (readline(nControl->response,256,nControl) == -1)
      {
          perror("Control socket read failed");
          return 0;
      }
    if (ftplib_debug > 1)
        fprintf(stderr,"%s",nControl->response);
    if (nControl->response[3] == '-')
      {
          strncpy(match,nControl->response,3);
          match[3] = ' ';
          match[4] = '\0';
          do
            {
                if (readline(nControl->response,256,nControl) == -1)
                  {
                      perror("Control socket read failed");
                      return 0;
                  }
                if (ftplib_debug > 1)
                    fprintf(stderr,"%s",nControl->response);
            }
          while (strncmp(nControl->response,match,4));
      }
    if (nControl->response[0] == c)
        return 1;
    return 0;
}

/*
 * FtpInit for stupid operating systems that require it (Windows NT)
 */
GLOBALDEF void FtpInit(void)
{
#if defined(_WIN32)
    WORD wVersionRequested;
    WSADATA wsadata;
    int err;
    wVersionRequested = MAKEWORD(1,1);
    if ((err = WSAStartup(wVersionRequested,&wsadata)) != 0)
        if (ftplib_debug > 1)
            fprintf(stderr,"Network failed to start: %d\n",err);
#endif
}

/*
 * FtpLastResponse - return a pointer to the last response received
 */
GLOBALDEF char *FtpLastResponse(netbuf *nControl)
{
    if ((nControl) && (nControl->dir == FTPLIB_CONTROL))
        return nControl->response;
    return NULL;
}

/*
 * FtpConnect - connect to remote server
 *
 * return 1 if connected, 0 if not
 */
GLOBALDEF int FtpConnect(const char *host, netbuf **nControl)
{
    int sControl, stat, flags, oldflags;
    struct sockaddr_in sin;
    struct hostent *phe;
    struct servent *pse;
    int on=1;
    netbuf *ctrl;
    char *lhost;
    char *pnum;
    struct timeval tv;
    fd_set wr;

    memset(&sin,0,sizeof(sin));
    sin.sin_family = AF_INET;
    lhost = strdup(host);
    pnum = strchr(lhost,':');
    if (pnum == NULL)
      {
#if defined(VMS) || defined(ANDROID)
          sin.sin_port = htons(21);
#else
          if ((pse = getservbyname("ftp","tcp")) == NULL)
            {
                perror("getservbyname");
                return 0;
            }
          sin.sin_port = pse->s_port;
#endif
      }
    else
      {
          *pnum++ = '\0';
          if (isdigit(*pnum))
              sin.sin_port = htons(atoi(pnum));
          else
            {
                pse = getservbyname(pnum,"tcp");
                sin.sin_port = pse->s_port;
            }
      }
    if ((sin.sin_addr.s_addr = inet_addr(lhost)) == -1)
      {
          if ((phe = gethostbyname(lhost)) == NULL)
            {
                perror("gethostbyname");
                return 0;
            }

          memcpy((char *)&sin.sin_addr, phe->h_addr, phe->h_length);

      }
    free(lhost);

    sControl = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (sControl == -1)
      {
          perror("socket");
          return 0;
      }

    if ( setsockopt(sControl,SOL_SOCKET,SO_REUSEADDR,
                   SETSOCKOPT_OPTVAL_TYPE &on, sizeof(on)) == -1)
      {
          perror("setsockopt");
          net_close(sControl);
          return 0;
      }

#if defined(_WIN32)
    if (connect(sControl, (struct sockaddr *)&sin, sizeof(sin)) == -1)
    {
        perror("connect");
        net_close(sControl);
        return 0;
    }
#else
     //set nonblocking for connection timeout
    flags = fcntl( sControl, F_GETFL,0);
    oldflags=flags;
    fcntl( sControl, F_SETFL, O_NONBLOCK|flags);

    stat=connect( sControl, (struct sockaddr *)&sin, sizeof(sin));
    if (stat < 0) 
      { 
          if (errno != EWOULDBLOCK && errno != EINPROGRESS) 
            { 
                perror("connect");
                net_close(sControl);
                return 0;
            } 
      } 

    FD_ZERO(&wr); 
    FD_SET( sControl, &wr); 

    tv.tv_sec = ACCEPT_TIMEOUT;
    tv.tv_usec = 0; 

    stat = select(sControl+1, 0, &wr, 0, &tv);

    if (stat < 1)
      { 
            // time out has expired, 
            // or an error has ocurred
          perror("timeout");
          net_close(sControl);
          return 0;
      } 

    if (ftplib_debug > 1)
        printf("connected\n");

      //set original flags
    fcntl( sControl, F_SETFL, oldflags);
#endif

    ctrl = calloc(1,sizeof(netbuf));
    if (ctrl == NULL)
      {
          perror("calloc");
          net_close(sControl);
          return 0;
      }
    ctrl->buf = malloc(FTPLIB_BUFSIZ);
    if (ctrl->buf == NULL)
      {
          perror("calloc");
          net_close(sControl);
          free(ctrl);
          return 0;
      }
    ctrl->handle = sControl;
    ctrl->dir = FTPLIB_CONTROL;
    ctrl->ctrl = NULL;
    ctrl->cmode = FTPLIB_DEFMODE;
    ctrl->idlecb = NULL;
    ctrl->writercb = NULL;
    ctrl->idletime.tv_sec = ctrl->idletime.tv_usec = 0;
    ctrl->idlearg = NULL;
    ctrl->writerarg = NULL;
    ctrl->xfered = 0;
    ctrl->xfered1 = 0;
    ctrl->cbbytes = 0;
    if (readresp('2', ctrl) == 0)
      {
          net_close(sControl);
          free(ctrl->buf);
          free(ctrl);
          return 0;
      }
    *nControl = ctrl;
    return 1;
}

/*
 * FtpOptions - change connection options
 *
 * returns 1 if successful, 0 on error
 */
GLOBALDEF int FtpOptions(int opt, long val, netbuf *nControl)
{
    int v,rv=0;
    switch (opt)
      {
        case FTPLIB_CONNMODE:
            v = (int) val;
            if ((v == FTPLIB_PASSIVE) || (v == FTPLIB_PORT))
              {
                  nControl->cmode = v;
                  rv = 1;
              }
            break;
        case FTPLIB_CALLBACK:
            nControl->idlecb = (FtpCallback) val;
            rv = 1;
            break;
        case FTPLIB_CALLBACK_WRITER:
            nControl->writercb = (FtpCallbackWriter) val;
            rv = 1;
            break;
        case FTPLIB_IDLETIME:
            v = (int) val;
            rv = 1;
            nControl->idletime.tv_sec = v / 1000;
            nControl->idletime.tv_usec = (v % 1000) * 1000;
            break;
        case FTPLIB_CALLBACKARG:
            rv = 1;
            nControl->idlearg = (void *) val;
            break;
        case FTPLIB_CALLBACK_WRITERARG:
            rv = 1;
            nControl->writerarg = (void *) val;
            break;
        case FTPLIB_CALLBACKBYTES:
            rv = 1;
            nControl->cbbytes = (int) val;
            break;
      }
    return rv;
}

/*
 * FtpSendCmd - send a command and wait for expected response
 *
 * return 1 if proper response received, 0 otherwise
 */
static int FtpSendCmd(const char *cmd, char expresp, netbuf *nControl)
{
    char buf[256];
    if (nControl->dir != FTPLIB_CONTROL)
        return 0;
    if (ftplib_debug > 2)
        fprintf(stderr,"%s\n",cmd);
    if ((strlen(cmd) + 3) > sizeof(buf))
        return 0;
    sprintf(buf,"%s\r\n",cmd);
    if (net_write(nControl->handle,buf,strlen(buf)) <= 0)
      {
          perror("write");
          return 0;
      }
    return readresp(expresp, nControl);
}

/*
 * FtpLogin - log in to remote server
 *
 * return 1 if logged in, 0 otherwise
 */
GLOBALDEF int FtpLogin(const char *user, const char *pass, netbuf *nControl)
{
    char tempbuf[64];

    if (((strlen(user) + 7) > sizeof(tempbuf)) ||
        ((strlen(pass) + 7) > sizeof(tempbuf)))
        return 0;
    sprintf(tempbuf,"USER %s",user);
    if (!FtpSendCmd(tempbuf,'3',nControl))
      {
          if (nControl->response[0] == '2')
              return 1;
          return 0;
      }
    sprintf(tempbuf,"PASS %s",pass);
    return FtpSendCmd(tempbuf,'2',nControl);
}

/*
 * FtpOpenPort - set up data connection
 *
 * return 1 if successful, 0 otherwise
 */
static int FtpOpenPort(netbuf *nControl, netbuf **nData, int mode, int dir)
{
    int sData;
    union {
        struct sockaddr sa;
        struct sockaddr_in in;
    } sin;
    struct linger lng = { 0, 0 };
    socklen_t l;
    int on=1;
    netbuf *ctrl;
    char *cp;
    unsigned int v[6];
    char buf[256];

    if (nControl->dir != FTPLIB_CONTROL)
        return -1;
    if ((dir != FTPLIB_READ) && (dir != FTPLIB_WRITE))
      {
          sprintf(nControl->response, "Invalid direction %d\n", dir);
          return -1;
      }
    if ((mode != FTPLIB_ASCII) && (mode != FTPLIB_IMAGE))
      {
          sprintf(nControl->response, "Invalid mode %c\n", mode);
          return -1;
      }
    l = sizeof(sin);
    if (nControl->cmode == FTPLIB_PASSIVE)
      {
          memset(&sin, 0, l);
          sin.in.sin_family = AF_INET;
          if (!FtpSendCmd("PASV",'2',nControl))
              return -1;
          cp = strchr(nControl->response,'(');
          if (cp == NULL)
              return -1;
          cp++;
          sscanf(cp,"%u,%u,%u,%u,%u,%u",&v[2],&v[3],&v[4],&v[5],&v[0],&v[1]);
          sin.sa.sa_data[2] = v[2];
          sin.sa.sa_data[3] = v[3];
          sin.sa.sa_data[4] = v[4];
          sin.sa.sa_data[5] = v[5];
          sin.sa.sa_data[0] = v[0];
          sin.sa.sa_data[1] = v[1];
      }
    else
      {
          if (getsockname(nControl->handle, &sin.sa, &l) < 0)
            {
                perror("getsockname");
                return 0;
            }
      }
    sData = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
    if (sData == -1)
      {
          perror("socket");
          return -1;
      }
    if (setsockopt(sData,SOL_SOCKET,SO_REUSEADDR,
                   SETSOCKOPT_OPTVAL_TYPE &on,sizeof(on)) == -1)
      {
          perror("setsockopt");
          net_close(sData);
          return -1;
      }
    if (setsockopt(sData,SOL_SOCKET,SO_LINGER,
                   SETSOCKOPT_OPTVAL_TYPE &lng,sizeof(lng)) == -1)
      {
          perror("setsockopt");
          net_close(sData);
          return -1;
      }
    if (nControl->cmode == FTPLIB_PASSIVE)
      {
          if (connect(sData, &sin.sa, sizeof(sin.sa)) == -1)
            {
                perror("connect");
                net_close(sData);
                return -1;
            }
      }
    else
      {
          sin.in.sin_port = 0;
          if (bind(sData, &sin.sa, sizeof(sin)) == -1)
            {
                perror("bind");
                net_close(sData);
                return 0;
            }
          if (listen(sData, 1) < 0)
            {
                perror("listen");
                net_close(sData);
                return 0;
            }
          if (getsockname(sData, &sin.sa, &l) < 0)
              return 0;
          sprintf(buf, "PORT %d,%d,%d,%d,%d,%d",
                  (unsigned char) sin.sa.sa_data[2],
                  (unsigned char) sin.sa.sa_data[3],
                  (unsigned char) sin.sa.sa_data[4],
                  (unsigned char) sin.sa.sa_data[5],
                  (unsigned char) sin.sa.sa_data[0],
                  (unsigned char) sin.sa.sa_data[1]);
          if (!FtpSendCmd(buf,'2',nControl))
            {
                net_close(sData);
                return 0;
            }
      }
    ctrl = calloc(1,sizeof(netbuf));
    if (ctrl == NULL)
      {
          perror("calloc");
          net_close(sData);
          return -1;
      }
    if ((mode == 'A') && ((ctrl->buf = malloc(FTPLIB_BUFSIZ)) == NULL))
      {
          perror("calloc");
          net_close(sData);
          free(ctrl);
          return -1;
      }
    ctrl->handle = sData;
    ctrl->dir = dir;
    ctrl->idletime = nControl->idletime;
    ctrl->idlearg = nControl->idlearg;
    ctrl->writerarg = nControl->writerarg;
    ctrl->xfered = 0;
    ctrl->xfered1 = 0;
    ctrl->cbbytes = nControl->cbbytes;
    if (ctrl->idletime.tv_sec || ctrl->idletime.tv_usec || ctrl->cbbytes)
        ctrl->idlecb = nControl->idlecb;
    else
        ctrl->idlecb = NULL;
    ctrl->writercb = nControl->writercb;
    *nData = ctrl;
    return 1;
}

/*
 * FtpAcceptConnection - accept connection from server
 *
 * return 1 if successful, 0 otherwise
 */
static int FtpAcceptConnection(netbuf *nData, netbuf *nControl)
{
    int sData;
    struct sockaddr addr;
    socklen_t l;
    int i;
    struct timeval tv;
    fd_set mask;
    int rv = 0;

    FD_ZERO(&mask);
    FD_SET(nControl->handle, &mask);
    FD_SET(nData->handle, &mask);
    tv.tv_usec = 0;
    tv.tv_sec = ACCEPT_TIMEOUT;
    if (ftplib_debug > 1)
        printf("<<<<<<<<<<<<<<<<%d\n",ACCEPT_TIMEOUT);
    i = nControl->handle;
    if (i < nData->handle)
        i = nData->handle;
    i = select(i+1, &mask, NULL, NULL, &tv);
    if (i == -1)
      {
          strncpy(nControl->response, strerror(errno),
                  sizeof(nControl->response));
          net_close(nData->handle);
          nData->handle = 0;
          rv = 0;
      }
    else if (i == 0)
      {
          strcpy(nControl->response, "timed out waiting for connection");
          net_close(nData->handle);
          nData->handle = 0;
          rv = 0;
      }
    else
      {
          if (FD_ISSET(nData->handle, &mask))
            {
                l = sizeof(addr);
                sData = accept(nData->handle, &addr, &l);
                i = errno;
                net_close(nData->handle);
                if (sData > 0)
                  {
                      rv = 1;
                      nData->handle = sData;
                  }
                else
                  {
                      strncpy(nControl->response, strerror(i),
                              sizeof(nControl->response));
                      nData->handle = 0;
                      rv = 0;
                  }
            }
          else if (FD_ISSET(nControl->handle, &mask))
            {
                net_close(nData->handle);
                nData->handle = 0;
                readresp('2', nControl);
                rv = 0;
            }
      }
    return rv;  
}

/*
 * FtpAccess - return a handle for a data stream
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpAccess(const char *path, int typ, int mode, netbuf *nControl,
                        netbuf **nData)
{
    char buf[256];
    int dir;
    if ((path == NULL) &&
        ((typ == FTPLIB_FILE_WRITE) || (typ == FTPLIB_FILE_READ)))
      {
          sprintf(nControl->response,
                  "Missing path argument for file transfer\n");
          return 0;
      }
    sprintf(buf, "TYPE %c", mode);
    if (!FtpSendCmd(buf, '2', nControl))
        return 0;
    switch (typ)
      {
        case FTPLIB_DIR:
            strcpy(buf,"NLST");
            dir = FTPLIB_READ;
            break;
        case FTPLIB_DIR_VERBOSE:
            strcpy(buf,"LIST");
            dir = FTPLIB_READ;
            break;
        case FTPLIB_FILE_READ:
            strcpy(buf,"RETR");
            dir = FTPLIB_READ;
            break;
        case FTPLIB_FILE_WRITE:
            strcpy(buf,"STOR");
            dir = FTPLIB_WRITE;
            break;
        default:
            sprintf(nControl->response, "Invalid open type %d\n", typ);
            return 0;
      }
    if (path != NULL)
      {
          int i = (int)strlen(buf);
          buf[i++] = ' ';
          if ((strlen(path) + i) >= sizeof(buf))
              return 0;
          strcpy(&buf[i],path);
      }
    if (FtpOpenPort(nControl, nData, mode, dir) == -1)
        return 0;
    if (!FtpSendCmd(buf, '1', nControl))
      {
          FtpClose(*nData);
          *nData = NULL;
          return 0;
      }
    (*nData)->ctrl = nControl;
    nControl->data = *nData;
    if (nControl->cmode == FTPLIB_PORT)
      {
          if (!FtpAcceptConnection(*nData,nControl))
            {
                FtpClose(*nData);
                *nData = NULL;
                nControl->data = NULL;
                return 0;
            }
      }
    return 1;
}

/*
 * FtpRead - read from a data connection
 */
GLOBALDEF int FtpRead(void *buf, int max, netbuf *nData)
{
    int i;
    if (nData->dir != FTPLIB_READ)
        return 0;
    if (nData->buf)
        i = readline(buf, max, nData);
    else
      {
          i = socket_wait(nData);
          if (i != 1)
              return 0;
          i = (int)net_read(nData->handle, buf, max);
      }
    if (i == -1)
        return 0;
    nData->xfered += i;
    if (nData->idlecb && nData->cbbytes)
      {
          nData->xfered1 += i;
          if (nData->xfered1 > nData->cbbytes)
            {
                if (nData->idlecb(nData, nData->xfered, nData->idlearg) == 0)
                    return 0;
                nData->xfered1 = 0;
            }
      }
    return i;
}

/*
 * FtpWrite - write to a data connection
 */
GLOBALDEF int FtpWrite(void *buf, int len, netbuf *nData)
{
    int i;
    if (nData->dir != FTPLIB_WRITE)
        return 0;
    if (nData->buf)
        i = writeline(buf, len, nData);
    else
      {
          socket_wait(nData);
          i = (int)net_write(nData->handle, buf, len);
      }
    if (i == -1)
        return 0;
    nData->xfered += i;
    if (nData->idlecb && nData->cbbytes)
      {
          nData->xfered1 += i;
          if (nData->xfered1 > nData->cbbytes)
            {
                nData->idlecb(nData, nData->xfered, nData->idlearg);
                nData->xfered1 = 0;
            }
      }
    return i;
}

/*
 * FtpClose - close a data connection
 */
GLOBALDEF int FtpClose(netbuf *nData)
{
    netbuf *ctrl;
    switch (nData->dir)
      {
        case FTPLIB_WRITE:
              /* potential problem - if buffer flush fails, how to notify user? */
            if (nData->buf != NULL)
                writeline(NULL, 0, nData);
        case FTPLIB_READ:
            if (nData->buf)
                free(nData->buf);
            shutdown(nData->handle,2);
            net_close(nData->handle);
            ctrl = nData->ctrl;
            free(nData);
            if (ctrl)
              {
                  ctrl->data = NULL;
                  return(readresp('2', ctrl));
              }
            return 1;
        case FTPLIB_CONTROL:
            if (nData->data)
              {
                  nData->ctrl = NULL;
                  FtpClose(nData);
              }
            net_close(nData->handle);
            free(nData);
            return 0;
      }
    return 1;
}

/*
 * FtpSite - send a SITE command
 *
 * return 1 if command successful, 0 otherwise
 */
GLOBALDEF int FtpSite(const char *cmd, netbuf *nControl)
{
    char buf[256];
    
    if ((strlen(cmd) + 7) > sizeof(buf))
        return 0;
    sprintf(buf,"SITE %s",cmd);
    if (!FtpSendCmd(buf,'2',nControl))
        return 0;
    return 1;
}

/*
 * FtpSysType - send a SYST command
 *
 * Fills in the user buffer with the remote system type.  If more
 * information from the response is required, the user can parse
 * it out of the response buffer returned by FtpLastResponse().
 *
 * return 1 if command successful, 0 otherwise
 */
GLOBALDEF int FtpSysType(char *buf, int max, netbuf *nControl)
{
    int l = max;
    char *b = buf;
    char *s;
    if (!FtpSendCmd("SYST",'2',nControl))
        return 0;
    s = &nControl->response[4];
    while ((--l) && (*s != ' '))
        *b++ = *s++;
    *b++ = '\0';
    return 1;
}

/*
 * FtpMkdir - create a directory at server
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpMkdir(const char *path, netbuf *nControl)
{
    char buf[256];

    if ((strlen(path) + 6) > sizeof(buf))
        return 0;
    sprintf(buf,"MKD %s",path);
    if (!FtpSendCmd(buf,'2', nControl))
        return 0;
    return 1;
}

/*
 * FtpChdir - change path at remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpChdir(const char *path, netbuf *nControl)
{
    char buf[256];

    if ((strlen(path) + 6) > sizeof(buf))
        return 0;
    sprintf(buf,"CWD %s",path);
    if (!FtpSendCmd(buf,'2',nControl))
        return 0;
    return 1;
}

/*
 * FtpCDUp - move to parent directory at remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpCDUp(netbuf *nControl)
{
    if (!FtpSendCmd("CDUP",'2',nControl))
        return 0;
    return 1;
}

/*
 * FtpRmdir - remove directory at remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpRmdir(const char *path, netbuf *nControl)
{
    char buf[256];

    if ((strlen(path) + 6) > sizeof(buf))
        return 0;
    sprintf(buf,"RMD %s",path);
    if (!FtpSendCmd(buf,'2',nControl))
        return 0;
    return 1;
}

/*
 * FtpPwd - get working directory at remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpPwd(char *path, int max, netbuf *nControl)
{
    int l = max;
    char *b = path;
    char *s;
    if (!FtpSendCmd("PWD",'2',nControl))
        return 0;
    s = strchr(nControl->response, '"');
    if (s == NULL)
        return 0;
    s++;
    while ((--l) && (*s) && (*s != '"'))
        *b++ = *s++;
    *b++ = '\0';
    return 1;
}

/*
 * FtpXfer - issue a command and transfer data
 *
 * return 1 if successful, 0 otherwise
 */
static int FtpXfer(const char *localfile, const char *path,
                   netbuf *nControl, int typ, int mode)
{
    int l,c;
    char *dbuf;
    FILE *local = NULL;
    netbuf *nData;
    int rv=1;
    int writeResult = 0;

    if (localfile != NULL)
      {
          char ac[4] = "w";
          if (typ == FTPLIB_FILE_WRITE)
              ac[0] = 'r';
          if (mode == FTPLIB_IMAGE)
              ac[1] = 'b';
          local = fopen(localfile, ac);
          if (local == NULL)
            {
                strncpy(nControl->response, strerror(errno),
                        sizeof(nControl->response));
                return 0;
            }
      }
    if (local == NULL)
        local = (typ == FTPLIB_FILE_WRITE) ? stdin : stdout;
    if (!FtpAccess(path, typ, mode, nControl, &nData))
        return 0;
    dbuf = malloc(FTPLIB_BUFSIZ);
    if (typ == FTPLIB_FILE_WRITE)
      {
          while ((l = (int)fread(dbuf, 1, FTPLIB_BUFSIZ, local)) > 0)
              if ((c = FtpWrite(dbuf, l, nData)) < l)
                {
                    if (ftplib_debug > 1)
                        printf("short write: passed %d, wrote %d\n", l, c);
                    rv = 0;
                    break;
                }
      }
    else
      {
          while ((l = FtpRead(dbuf, FTPLIB_BUFSIZ, nData)) > 0) {
              writeResult = (int)((nData->writercb) ? nData->writercb(nData, dbuf, l, nData->writerarg) : fwrite(dbuf, 1, l, local));
              if (writeResult <= 0)
                {
                    perror("localstore write");
                    rv = 0;
                    break;
                }
          }
      }
    free(dbuf);
    fflush(local);
    if (localfile != NULL)
        fclose(local);
    FtpClose(nData);
    return rv;
}

/*
 * FtpNlst - issue an NLST command and write response to output
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpNlst(const char *outputfile, const char *path,
                      netbuf *nControl)
{
    return FtpXfer(outputfile, path, nControl, FTPLIB_DIR, FTPLIB_ASCII);
}

/*
 * FtpDir - issue a LIST command and write response to output
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpDir(const char *outputfile, const char *path, netbuf *nControl)
{
    return FtpXfer(outputfile, path, nControl, FTPLIB_DIR_VERBOSE, FTPLIB_ASCII);
}

/*
 * FtpSize - determine the size of a remote file
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpSize(const char *path, int *size, char mode, netbuf *nControl)
{
    char cmd[256];
    int resp,sz,rv=1;

    if ((strlen(path) + 7) > sizeof(cmd))
        return 0;
    sprintf(cmd, "TYPE %c", mode);
    if (!FtpSendCmd(cmd, '2', nControl))
        return 0;
    sprintf(cmd,"SIZE %s",path);
    if (!FtpSendCmd(cmd,'2',nControl))
        rv = 0;
    else
      {
          if (sscanf(nControl->response, "%d %d", &resp, &sz) == 2)
              *size = sz;
          else
              rv = 0;
      }   
    return rv;
}

/*
 * FtpModDate - determine the modification date of a remote file
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpModDate(const char *path, char *dt, int max, netbuf *nControl)
{
    char buf[256];
    int rv = 1;

    if ((strlen(path) + 7) > sizeof(buf))
        return 0;
    sprintf(buf,"MDTM %s",path);
    if (!FtpSendCmd(buf,'2',nControl))
        rv = 0;
    else
        strncpy(dt, &nControl->response[4], max);
    return rv;
}

/*
 * FtpGet - issue a GET command and write received data to output
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpGet(const char *outputfile, const char *path,
                     char mode, netbuf *nControl)
{
    return FtpXfer(outputfile, path, nControl, FTPLIB_FILE_READ, mode);
}

/*
 * FtpPut - issue a PUT command and send data from input
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpPut(const char *inputfile, const char *path, char mode,
                     netbuf *nControl)
{
    return FtpXfer(inputfile, path, nControl, FTPLIB_FILE_WRITE, mode);
}

/*
 * FtpRename - rename a file at remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpRename(const char *src, const char *dst, netbuf *nControl)
{
    char cmd[256];

    if (((strlen(src) + 7) > sizeof(cmd)) ||
        ((strlen(dst) + 7) > sizeof(cmd)))
        return 0;
    sprintf(cmd,"RNFR %s",src);
    if (!FtpSendCmd(cmd,'3',nControl))
        return 0;
    sprintf(cmd,"RNTO %s",dst);
    if (!FtpSendCmd(cmd,'2',nControl))
        return 0;
    return 1;
}

/*
 * FtpDelete - delete a file at remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF int FtpDelete(const char *fnm, netbuf *nControl)
{
    char cmd[256];

    if ((strlen(fnm) + 7) > sizeof(cmd))
        return 0;
    sprintf(cmd,"DELE %s",fnm);
    if (!FtpSendCmd(cmd,'2', nControl))
        return 0;
    return 1;
}

/*
 * FtpQuit - disconnect from remote
 *
 * return 1 if successful, 0 otherwise
 */
GLOBALDEF void FtpQuit(netbuf *nControl)
{
    if (nControl->dir != FTPLIB_CONTROL)
        return;
    FtpSendCmd("QUIT",'2',nControl);
    net_close(nControl->handle);
    free(nControl->buf);
    free(nControl);
}