FTP implementation in C

Most of the beginners would wonder how the known services work. Well this post will give an overview of one of the well-written services in C , the FTP application. I thought that there is no need to re-invent the wheel and use this code as is from Apple's open source initiative.The code is written in C.

I am providing the code only for the main file which contains FTP specific functions. The rest of the supporting files including the Makefile can be downloaded from here.

Disclaimer : This code is taken from Apple Opensource . I don't want Apple to sue me ;)

 /*ftp.c*/

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.0 (the 'License').  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License."
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1985, 1989, 1993, 1994
 * The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * This product includes software developed by the University of
 * California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/file.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <arpa/ftp.h>
#include <arpa/telnet.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdarg.h>

#include "ftp_var.h"

extern int h_errno;

struct sockaddr_in hisctladdr;
struct sockaddr_in data_addr;
int data = -1;
int abrtflag = 0;
jmp_buf ptabort;
int ptabflg;
int ptflag = 0;
struct sockaddr_in myctladdr;
off_t restart_point = 0;

FILE *cin, *cout;

char *
hookup(host, port)
 char *host;
 int port;
{
 struct hostent *hp = 0;
 int s, len, tos;
 static char hostnamebuf[80];

 memset((char *)&hisctladdr, 0, sizeof (hisctladdr));
 hisctladdr.sin_addr.s_addr = inet_addr(host);
 if (hisctladdr.sin_addr.s_addr != -1) {
  hisctladdr.sin_family = AF_INET;
  (void) strncpy(hostnamebuf, host, sizeof(hostnamebuf));
 } else {
  hp = gethostbyname(host);
  if (hp == NULL) {
   warnx("%s: %s", host, hstrerror(h_errno));
   code = -1;
   return ((char *) 0);
  }
  hisctladdr.sin_family = hp->h_addrtype;
  memmove((caddr_t)&hisctladdr.sin_addr,
    hp->h_addr_list[0], hp->h_length);
  (void) strncpy(hostnamebuf, hp->h_name, sizeof(hostnamebuf));
 }
 hostname = hostnamebuf;
 s = socket(hisctladdr.sin_family, SOCK_STREAM, 0);
 if (s < 0) {
  warn("socket");
  code = -1;
  return (0);
 }
 hisctladdr.sin_port = port;
 while (connect(s, (struct sockaddr *)&hisctladdr, sizeof (hisctladdr)) < 0) {
  if (hp && hp->h_addr_list[1]) {
   int oerrno = errno;
   char *ia;

   ia = inet_ntoa(hisctladdr.sin_addr);
   errno = oerrno;
   warn("connect to address %s", ia);
   hp->h_addr_list++;
   memmove((caddr_t)&hisctladdr.sin_addr,
     hp->h_addr_list[0], hp->h_length);
   fprintf(stdout, "Trying %s...\n",
    inet_ntoa(hisctladdr.sin_addr));
   (void) close(s);
   s = socket(hisctladdr.sin_family, SOCK_STREAM, 0);
   if (s < 0) {
    warn("socket");
    code = -1;
    return (0);
   }
   continue;
  }
  warn("connect");
  code = -1;
  goto bad;
 }
 len = sizeof (myctladdr);
 if (getsockname(s, (struct sockaddr *)&myctladdr, &len) < 0) {
  warn("getsockname");
  code = -1;
  goto bad;
 }
#ifdef IP_TOS
 tos = IPTOS_LOWDELAY;
 if (setsockopt(s, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(int)) < 0)
  warn("setsockopt TOS (ignored)");
#endif
 cin = fdopen(s, "r");
 cout = fdopen(s, "w");
 if (cin == NULL || cout == NULL) {
  warnx("fdopen failed.");
  if (cin)
   (void) fclose(cin);
  if (cout)
   (void) fclose(cout);
  code = -1;
  goto bad;
 }
 if (verbose)
  printf("Connected to %s.\n", hostname);
 if (getreply(0) > 2) {  /* read startup message from server */
  if (cin)
   (void) fclose(cin);
  if (cout)
   (void) fclose(cout);
  code = -1;
  goto bad;
 }
#ifdef SO_OOBINLINE
 {
 int on = 1;

 if (setsockopt(s, SOL_SOCKET, SO_OOBINLINE, (char *)&on, sizeof(on))
  < 0 && debug) {
   warn("setsockopt");
  }
 }
#endif /* SO_OOBINLINE */

 return (hostname);
bad:
 (void) close(s);
 return ((char *)0);
}

int
login(host)
 char *host;
{
 char tmp[80];
 char *user, *pass, *acct;
 int n, aflag = 0;

 user = pass = acct = 0;
 if (ruserpass(host, &user, &pass, &acct) < 0) {
  code = -1;
  return (0);
 }
 while (user == NULL) {
  char *myname = getlogin();

  if (myname == NULL) {
   struct passwd *pp = getpwuid(getuid());

   if (pp != NULL)
    myname = pp->pw_name;
  }
  if (myname)
   printf("Name (%s:%s): ", host, myname);
  else
   printf("Name (%s): ", host);
  (void) fgets(tmp, sizeof(tmp) - 1, stdin);
  tmp[strlen(tmp) - 1] = '\0';
  if (*tmp == '\0')
   user = myname;
  else
   user = tmp;
 }
 n = command("USER %s", user);
 if (n == CONTINUE) {
  if (pass == NULL)
   pass = getpass("Password:");
  n = command("PASS %s", pass);
 }
 if (n == CONTINUE) {
  aflag++;
  acct = getpass("Account:");
  n = command("ACCT %s", acct);
 }
 if (n != COMPLETE) {
  warnx("Login failed.");
  return (0);
 }
 if (!aflag && acct != NULL)
  (void) command("ACCT %s", acct);
 if (proxy)
  return (1);
 for (n = 0; n < macnum; ++n) {
  if (!strcmp("init", macros[n].mac_name)) {
   (void) strcpy(line, "$init");
   makeargv();
   domacro(margc, margv);
   break;
  }
 }
 return (1);
}

void
cmdabort()
{

 printf("\n");
 (void) fflush(stdout);
 abrtflag++;
 if (ptflag)
  longjmp(ptabort,1);
}

int command(const char *fmt, ...)
{
 va_list ap;
 int r;
 sig_t oldintr;

 abrtflag = 0;
 if (debug) {
  printf("---> ");
  va_start(ap, fmt);
  if (strncmp("PASS ", fmt, 5) == 0)
   printf("PASS XXXX");
  else 
   vfprintf(stdout, fmt, ap);
  va_end(ap);
  printf("\n");
  (void) fflush(stdout);
 }
 if (cout == NULL) {
  warn("No control connection for command");
  code = -1;
  return (0);
 }
 oldintr = signal(SIGINT, cmdabort);
 va_start(ap, fmt);
 vfprintf(cout, fmt, ap);
 va_end(ap);
 fprintf(cout, "\r\n");
 (void) fflush(cout);
 cpend = 1;
 r = getreply(!strcmp(fmt, "QUIT"));
 if (abrtflag && oldintr != SIG_IGN)
  (*oldintr)(SIGINT);
 (void) signal(SIGINT, oldintr);
 return (r);
}

char reply_string[BUFSIZ];  /* last line of previous reply */

int
getreply(expecteof)
 int expecteof;
{
 int c, n;
 int dig;
 int originalcode = 0, continuation = 0;
 sig_t oldintr;
 int pflag = 0;
 char *cp, *pt = pasv;

 oldintr = signal(SIGINT, cmdabort);
 for (;;) {
  dig = n = code = 0;
  cp = reply_string;
  while ((c = getc(cin)) != '\n') {
   if (c == IAC) {     /* handle telnet commands */
    switch (c = getc(cin)) {
    case WILL:
    case WONT:
     c = getc(cin);
     fprintf(cout, "%c%c%c", IAC, DONT, c);
     (void) fflush(cout);
     break;
    case DO:
    case DONT:
     c = getc(cin);
     fprintf(cout, "%c%c%c", IAC, WONT, c);
     (void) fflush(cout);
     break;
    default:
     break;
    }
    continue;
   }
   dig++;
   if (c == EOF) {
    if (expecteof) {
     (void) signal(SIGINT,oldintr);
     code = 221;
     return (0);
    }
    lostpeer();
    if (verbose) {
     printf("421 Service not available, remote server has closed connection\n");
     (void) fflush(stdout);
    }
    code = 421;
    return (4);
   }
   if (c != '\r' && (verbose > 0 ||
       (verbose > -1 && n == '5' && dig > 4))) {
    if (proxflag &&
       (dig == 1 || dig == 5 && verbose == 0))
     printf("%s:",hostname);
    (void) putchar(c);
   }
   if (dig < 4 && isdigit(c))
    code = code * 10 + (c - '0');
   if (!pflag && code == 227)
    pflag = 1;
   if (dig > 4 && pflag == 1 && isdigit(c))
    pflag = 2;
   if (pflag == 2) {
    if (c != '\r' && c != ')')
     *pt++ = c;
    else {
     *pt = '\0';
     pflag = 3;
    }
   }
   if (dig == 4 && c == '-') {
    if (continuation)
     code = 0;
    continuation++;
   }
   if (n == 0)
    n = c;
   if (cp < &reply_string[sizeof(reply_string) - 1])
    *cp++ = c;
  }
  if (verbose > 0 || verbose > -1 && n == '5') {
   (void) putchar(c);
   (void) fflush (stdout);
  }
  if (continuation && code != originalcode) {
   if (originalcode == 0)
    originalcode = code;
   continue;
  }
  *cp = '\0';
  if (n != '1')
   cpend = 0;
  (void) signal(SIGINT,oldintr);
  if (code == 421 || originalcode == 421)
   lostpeer();
  if (abrtflag && oldintr != cmdabort && oldintr != SIG_IGN)
   (*oldintr)(SIGINT);
  return (n - '0');
 }
}

int
empty(mask, sec)
 struct fd_set *mask;
 int sec;
{
 struct timeval t;

 t.tv_sec = (long) sec;
 t.tv_usec = 0;
 return (select(32, mask, (struct fd_set *) 0, (struct fd_set *) 0, &t));
}

jmp_buf sendabort;

void
abortsend()
{

 mflag = 0;
 abrtflag = 0;
 printf("\nsend aborted\nwaiting for remote to finish abort\n");
 (void) fflush(stdout);
 longjmp(sendabort, 1);
}

#define HASHBYTES 1024

void
sendrequest(cmd, local, remote, printnames)
 char *cmd, *local, *remote;
 int printnames;
{
 struct stat st;
 struct timeval start, stop;
 int c, d;
 FILE *fin, *dout = 0, *popen();
 int (*closefunc) __P((FILE *));
 sig_t oldintr, oldintp;
 long bytes = 0, hashbytes = HASHBYTES;
 char *lmode, buf[BUFSIZ], *bufp;

 if (verbose && printnames) {
  if (local && *local != '-')
   printf("local: %s ", local);
  if (remote)
   printf("remote: %s\n", remote);
 }
 if (proxy) {
  proxtrans(cmd, local, remote);
  return;
 }
 if (curtype != type)
  changetype(type, 0);
 closefunc = NULL;
 oldintr = NULL;
 oldintp = NULL;
 lmode = "w";
 if (setjmp(sendabort)) {
  while (cpend) {
   (void) getreply(0);
  }
  if (data >= 0) {
   (void) close(data);
   data = -1;
  }
  if (oldintr)
   (void) signal(SIGINT,oldintr);
  if (oldintp)
   (void) signal(SIGPIPE,oldintp);
  code = -1;
  return;
 }
 oldintr = signal(SIGINT, abortsend);
 if (strcmp(local, "-") == 0)
  fin = stdin;
 else if (*local == '|') {
  oldintp = signal(SIGPIPE,SIG_IGN);
  fin = popen(local + 1, "r");
  if (fin == NULL) {
   warn("%s", local + 1);
   (void) signal(SIGINT, oldintr);
   (void) signal(SIGPIPE, oldintp);
   code = -1;
   return;
  }
  closefunc = pclose;
 } else {
  fin = fopen(local, "r");
  if (fin == NULL) {
   warn("local: %s", local);
   (void) signal(SIGINT, oldintr);
   code = -1;
   return;
  }
  closefunc = fclose;
  if (fstat(fileno(fin), &st) < 0 ||
      (st.st_mode&S_IFMT) != S_IFREG) {
   fprintf(stdout, "%s: not a plain file.\n", local);
   (void) signal(SIGINT, oldintr);
   fclose(fin);
   code = -1;
   return;
  }
 }
 if (initconn()) {
  (void) signal(SIGINT, oldintr);
  if (oldintp)
   (void) signal(SIGPIPE, oldintp);
  code = -1;
  if (closefunc != NULL)
   (*closefunc)(fin);
  return;
 }
 if (setjmp(sendabort))
  goto abort;

 if (restart_point &&
     (strcmp(cmd, "STOR") == 0 || strcmp(cmd, "APPE") == 0)) {
  int rc;

  switch (curtype) {
  case TYPE_A:
   rc = fseek(fin, (long) restart_point, SEEK_SET);
   break;
  case TYPE_I:
  case TYPE_L:
   rc = lseek(fileno(fin), restart_point, SEEK_SET);
   break;
  }
  if (rc < 0) {
   warn("local: %s", local);
   restart_point = 0;
   if (closefunc != NULL)
    (*closefunc)(fin);
   return;
  }
  if (command("REST %ld", (long) restart_point)
   != CONTINUE) {
   restart_point = 0;
   if (closefunc != NULL)
    (*closefunc)(fin);
   return;
  }
  restart_point = 0;
  lmode = "r+w";
 }
 if (remote) {
  if (command("%s %s", cmd, remote) != PRELIM) {
   (void) signal(SIGINT, oldintr);
   if (oldintp)
    (void) signal(SIGPIPE, oldintp);
   if (closefunc != NULL)
    (*closefunc)(fin);
   return;
  }
 } else
  if (command("%s", cmd) != PRELIM) {
   (void) signal(SIGINT, oldintr);
   if (oldintp)
    (void) signal(SIGPIPE, oldintp);
   if (closefunc != NULL)
    (*closefunc)(fin);
   return;
  }
 dout = dataconn(lmode);
 if (dout == NULL)
  goto abort;
 (void) gettimeofday(&start, (struct timezone *)0);
 oldintp = signal(SIGPIPE, SIG_IGN);
 switch (curtype) {

 case TYPE_I:
 case TYPE_L:
  errno = d = 0;
  while ((c = read(fileno(fin), buf, sizeof (buf))) > 0) {
   bytes += c;
   for (bufp = buf; c > 0; c -= d, bufp += d)
    if ((d = write(fileno(dout), bufp, c)) <= 0)
     break;
   if (hash) {
    while (bytes >= hashbytes) {
     (void) putchar('#');
     hashbytes += HASHBYTES;
    }
    (void) fflush(stdout);
   }
  }
  if (hash && bytes > 0) {
   if (bytes < HASHBYTES)
    (void) putchar('#');
   (void) putchar('\n');
   (void) fflush(stdout);
  }
  if (c < 0)
   warn("local: %s", local);
  if (d < 0) {
   if (errno != EPIPE) 
    warn("netout");
   bytes = -1;
  }
  break;

 case TYPE_A:
  while ((c = getc(fin)) != EOF) {
   if (c == '\n') {
    while (hash && (bytes >= hashbytes)) {
     (void) putchar('#');
     (void) fflush(stdout);
     hashbytes += HASHBYTES;
    }
    if (ferror(dout))
     break;
    (void) putc('\r', dout);
    bytes++;
   }
   (void) putc(c, dout);
   bytes++;
 /*  if (c == '\r') {      */
 /*  (void) putc('\0', dout);  // this violates rfc */
 /*   bytes++;    */
 /*  }                             */ 
  }
  if (hash) {
   if (bytes < hashbytes)
    (void) putchar('#');
   (void) putchar('\n');
   (void) fflush(stdout);
  }
  if (ferror(fin))
   warn("local: %s", local);
  if (ferror(dout)) {
   if (errno != EPIPE)
    warn("netout");
   bytes = -1;
  }
  break;
 }
 if (closefunc != NULL)
  (*closefunc)(fin);
 (void) fclose(dout);
 (void) gettimeofday(&stop, (struct timezone *)0);
 (void) getreply(0);
 (void) signal(SIGINT, oldintr);
 if (oldintp)
  (void) signal(SIGPIPE, oldintp);
 if (bytes > 0)
  ptransfer("sent", bytes, &start, &stop);
 return;
abort:
 (void) signal(SIGINT, oldintr);
 if (oldintp)
  (void) signal(SIGPIPE, oldintp);
 if (!cpend) {
  code = -1;
  return;
 }
 if (data >= 0) {
  (void) close(data);
  data = -1;
 }
 if (dout)
  (void) fclose(dout);
 (void) getreply(0);
 code = -1;
 if (closefunc != NULL && fin != NULL)
  (*closefunc)(fin);
 (void) gettimeofday(&stop, (struct timezone *)0);
 if (bytes > 0)
  ptransfer("sent", bytes, &start, &stop);
}

jmp_buf recvabort;

void
abortrecv()
{

 mflag = 0;
 abrtflag = 0;
 printf("\nreceive aborted\nwaiting for remote to finish abort\n");
 (void) fflush(stdout);
 longjmp(recvabort, 1);
}

void
recvrequest(cmd, local, remote, lmode, printnames)
 char *cmd, *local, *remote, *lmode;
 int printnames;
{
 FILE *fout, *din = 0;
 int (*closefunc) __P((FILE *));
 sig_t oldintr, oldintp;
 int c, d, is_retr, tcrflag, bare_lfs = 0;
 static int bufsize;
 static char *buf;
 long bytes = 0, hashbytes = HASHBYTES;
 struct timeval start, stop;
 struct stat st;

 is_retr = strcmp(cmd, "RETR") == 0;
 if (is_retr && verbose && printnames) {
  if (local && *local != '-')
   printf("local: %s ", local);
  if (remote)
   printf("remote: %s\n", remote);
 }
 if (proxy && is_retr) {
  proxtrans(cmd, local, remote);
  return;
 }
 closefunc = NULL;
 oldintr = NULL;
 oldintp = NULL;
 tcrflag = !crflag && is_retr;
 if (setjmp(recvabort)) {
  while (cpend) {
   (void) getreply(0);
  }
  if (data >= 0) {
   (void) close(data);
   data = -1;
  }
  if (oldintr)
   (void) signal(SIGINT, oldintr);
  code = -1;
  return;
 }
 oldintr = signal(SIGINT, abortrecv);
 if (strcmp(local, "-") && *local != '|') {
  if (access(local, 2) < 0) {
   char *dir = strrchr(local, '/');

   if (errno != ENOENT && errno != EACCES) {
    warn("local: %s", local);
    (void) signal(SIGINT, oldintr);
    code = -1;
    return;
   }
   if (dir != NULL)
    *dir = 0;
   d = access(dir ? local : ".", 2);
   if (dir != NULL)
    *dir = '/';
   if (d < 0) {
    warn("local: %s", local);
    (void) signal(SIGINT, oldintr);
    code = -1;
    return;
   }
   if (!runique && errno == EACCES &&
       chmod(local, 0600) < 0) {
    warn("local: %s", local);
    (void) signal(SIGINT, oldintr);
    (void) signal(SIGINT, oldintr);
    code = -1;
    return;
   }
   if (runique && errno == EACCES &&
      (local = gunique(local)) == NULL) {
    (void) signal(SIGINT, oldintr);
    code = -1;
    return;
   }
  }
  else if (runique && (local = gunique(local)) == NULL) {
   (void) signal(SIGINT, oldintr);
   code = -1;
   return;
  }
 }
 if (!is_retr) {
  if (curtype != TYPE_A)
   changetype(TYPE_A, 0);
 } else if (curtype != type)
  changetype(type, 0);
 if (initconn()) {
  (void) signal(SIGINT, oldintr);
  code = -1;
  return;
 }
 if (setjmp(recvabort))
  goto abort;
 if (is_retr && restart_point &&
     command("REST %ld", (long) restart_point) != CONTINUE)
  return;
 if (remote) {
  if (command("%s %s", cmd, remote) != PRELIM) {
   (void) signal(SIGINT, oldintr);
   return;
  }
 } else {
  if (command("%s", cmd) != PRELIM) {
   (void) signal(SIGINT, oldintr);
   return;
  }
 }
 din = dataconn("r");
 if (din == NULL)
  goto abort;
 if (strcmp(local, "-") == 0)
  fout = stdout;
 else if (*local == '|') {
  oldintp = signal(SIGPIPE, SIG_IGN);
  fout = popen(local + 1, "w");
  if (fout == NULL) {
   warn("%s", local+1);
   goto abort;
  }
  closefunc = pclose;
 } else {
  fout = fopen(local, lmode);
  if (fout == NULL) {
   warn("local: %s", local);
   goto abort;
  }
  closefunc = fclose;
 }
 if (fstat(fileno(fout), &st) < 0 || st.st_blksize == 0)
  st.st_blksize = BUFSIZ;
 if (st.st_blksize > bufsize) {
  if (buf)
   (void) free(buf);
  buf = malloc((unsigned)st.st_blksize);
  if (buf == NULL) {
   warn("malloc");
   bufsize = 0;
   goto abort;
  }
  bufsize = st.st_blksize;
 }
 (void) gettimeofday(&start, (struct timezone *)0);
 switch (curtype) {

 case TYPE_I:
 case TYPE_L:
  if (restart_point &&
      lseek(fileno(fout), restart_point, SEEK_SET) < 0) {
   warn("local: %s", local);
   if (closefunc != NULL)
    (*closefunc)(fout);
   return;
  }
  errno = d = 0;
  while ((c = read(fileno(din), buf, bufsize)) > 0) {
   if ((d = write(fileno(fout), buf, c)) != c)
    break;
   bytes += c;
   if (hash) {
    while (bytes >= hashbytes) {
     (void) putchar('#');
     hashbytes += HASHBYTES;
    }
    (void) fflush(stdout);
   }
  }
  if (hash && bytes > 0) {
   if (bytes < HASHBYTES)
    (void) putchar('#');
   (void) putchar('\n');
   (void) fflush(stdout);
  }
  if (c < 0) {
   if (errno != EPIPE)
    warn("netin");
   bytes = -1;
  }
  if (d < c) {
   if (d < 0)
    warn("local: %s", local);
   else
    warnx("%s: short write", local);
  }
  break;

 case TYPE_A:
  if (restart_point) {
   int i, n, ch;

   if (fseek(fout, 0L, SEEK_SET) < 0)
    goto done;
   n = restart_point;
   for (i = 0; i++ < n;) {
    if ((ch = getc(fout)) == EOF)
     goto done;
    if (ch == '\n')
     i++;
   }
   if (fseek(fout, 0L, SEEK_CUR) < 0) {
done:
    warn("local: %s", local);
    if (closefunc != NULL)
     (*closefunc)(fout);
    return;
   }
  }
  while ((c = getc(din)) != EOF) {
   if (c == '\n')
    bare_lfs++;
   while (c == '\r') {
    while (hash && (bytes >= hashbytes)) {
     (void) putchar('#');
     (void) fflush(stdout);
     hashbytes += HASHBYTES;
    }
    bytes++;
    if ((c = getc(din)) != '\n' || tcrflag) {
     if (ferror(fout))
      goto break2;
     (void) putc('\r', fout);
     if (c == '\0') {
      bytes++;
      goto contin2;
     }
     if (c == EOF)
      goto contin2;
    }
   }
   (void) putc(c, fout);
   bytes++;
 contin2: ;
  }
break2:
  if (bare_lfs) {
   printf("WARNING! %d bare linefeeds received in ASCII mode\n", bare_lfs);
   printf("File may not have transferred correctly.\n");
  }
  if (hash) {
   if (bytes < hashbytes)
    (void) putchar('#');
   (void) putchar('\n');
   (void) fflush(stdout);
  }
  if (ferror(din)) {
   if (errno != EPIPE)
    warn("netin");
   bytes = -1;
  }
  if (ferror(fout))
   warn("local: %s", local);
  break;
 }
 if (closefunc != NULL)
  (*closefunc)(fout);
 (void) signal(SIGINT, oldintr);
 if (oldintp)
  (void) signal(SIGPIPE, oldintp);
 (void) fclose(din);
 (void) gettimeofday(&stop, (struct timezone *)0);
 (void) getreply(0);
 if (bytes > 0 && is_retr)
  ptransfer("received", bytes, &start, &stop);
 return;
abort:

/* abort using RFC959 recommended IP,SYNC sequence  */

 if (oldintp)
  (void) signal(SIGPIPE, oldintr);
 (void) signal(SIGINT, SIG_IGN);
 if (!cpend) {
  code = -1;
  (void) signal(SIGINT, oldintr);
  return;
 }

 abort_remote(din);
 code = -1;
 if (data >= 0) {
  (void) close(data);
  data = -1;
 }
 if (closefunc != NULL && fout != NULL)
  (*closefunc)(fout);
 if (din)
  (void) fclose(din);
 (void) gettimeofday(&stop, (struct timezone *)0);
 if (bytes > 0)
  ptransfer("received", bytes, &start, &stop);
 (void) signal(SIGINT, oldintr);
}

/*
 * Need to start a listen on the data channel before we send the command,
 * otherwise the server's connect may fail.
 */
int
initconn()
{
 char *p, *a;
 int result, len, tmpno = 0;
 int on = 1;
 int a0, a1, a2, a3, p0, p1;

 if (passivemode) {
  data = socket(AF_INET, SOCK_STREAM, 0);
  if (data < 0) {
   perror("ftp: socket");
   return(1);
  }
  if ((options & SO_DEBUG) &&
      setsockopt(data, SOL_SOCKET, SO_DEBUG, (char *)&on,
          sizeof (on)) < 0)
   perror("ftp: setsockopt (ignored)");
  if (command("PASV") != COMPLETE) {
   printf("Passive mode refused.\n");
   goto bad;
  }

  /*
   * What we've got at this point is a string of comma
   * separated one-byte unsigned integer values.
   * The first four are the an IP address. The fifth is
   * the MSB of the port number, the sixth is the LSB.
   * From that we'll prepare a sockaddr_in.
   */

  if (sscanf(pasv,"%d,%d,%d,%d,%d,%d",
      &a0, &a1, &a2, &a3, &p0, &p1) != 6) {
   printf("Passive mode address scan failure. "
          "Shouldn't happen!\n");
   goto bad;
  }

  bzero(&data_addr, sizeof(data_addr));
  data_addr.sin_family = AF_INET;
  a = (char *)&data_addr.sin_addr.s_addr;
  a[0] = a0 & 0xff;
  a[1] = a1 & 0xff;
  a[2] = a2 & 0xff;
  a[3] = a3 & 0xff;
  p = (char *)&data_addr.sin_port;
  p[0] = p0 & 0xff;
  p[1] = p1 & 0xff;

  if (connect(data, (struct sockaddr *)&data_addr,
       sizeof(data_addr)) < 0) {
   perror("ftp: connect");
   goto bad;
  }
#ifdef IP_TOS
  on = IPTOS_THROUGHPUT;
  if (setsockopt(data, IPPROTO_IP, IP_TOS, (char *)&on,
          sizeof(int)) < 0)
   perror("ftp: setsockopt TOS (ignored)");
#endif
  return(0);
 }

noport:
 data_addr = myctladdr;
 if (sendport)
  data_addr.sin_port = 0; /* let system pick one */ 
 if (data != -1)
  (void) close(data);
 data = socket(AF_INET, SOCK_STREAM, 0);
 if (data < 0) {
  warn("socket");
  if (tmpno)
   sendport = 1;
  return (1);
 }
 if (!sendport)
  if (setsockopt(data, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof (on)) < 0) {
   warn("setsockopt (reuse address)");
   goto bad;
  }
 if (bind(data, (struct sockaddr *)&data_addr, sizeof (data_addr)) < 0) {
  warn("bind");
  goto bad;
 }
 if (options & SO_DEBUG &&
     setsockopt(data, SOL_SOCKET, SO_DEBUG, (char *)&on, sizeof (on)) < 0)
  warn("setsockopt (ignored)");
 len = sizeof (data_addr);
 if (getsockname(data, (struct sockaddr *)&data_addr, &len) < 0) {
  warn("getsockname");
  goto bad;
 }
 if (listen(data, 1) < 0)
  warn("listen");
 if (sendport) {
  a = (char *)&data_addr.sin_addr;
  p = (char *)&data_addr.sin_port;
#define UC(b) (((int)b)&0xff)
  result =
      command("PORT %d,%d,%d,%d,%d,%d",
        UC(a[0]), UC(a[1]), UC(a[2]), UC(a[3]),
        UC(p[0]), UC(p[1]));
  if (result == ERROR && sendport == -1) {
   sendport = 0;
   tmpno = 1;
   goto noport;
  }
  return (result != COMPLETE);
 }
 if (tmpno)
  sendport = 1;
#ifdef IP_TOS
 on = IPTOS_THROUGHPUT;
 if (setsockopt(data, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
  warn("setsockopt TOS (ignored)");
#endif
 return (0);
bad:
 (void) close(data), data = -1;
 if (tmpno)
  sendport = 1;
 return (1);
}

FILE *
dataconn(lmode)
 char *lmode;
{
 struct sockaddr_in from;
 int s, fromlen = sizeof (from), tos;

 if (passivemode)
  return (fdopen(data, lmode));

 s = accept(data, (struct sockaddr *) &from, &fromlen);
 if (s < 0) {
  warn("accept");
  (void) close(data), data = -1;
  return (NULL);
 }
 (void) close(data);
 data = s;
#ifdef IP_TOS
 tos = IPTOS_THROUGHPUT;
 if (setsockopt(s, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(int)) < 0)
  warn("setsockopt TOS (ignored)");
#endif
 return (fdopen(data, lmode));
}

void
ptransfer(direction, bytes, t0, t1)
 char *direction;
 long bytes;
 struct timeval *t0, *t1;
{
 struct timeval td;
 float s;
 long bs;

 if (verbose) {
  tvsub(&td, t1, t0);
  s = td.tv_sec + (td.tv_usec / 1000000.);
#define nz(x) ((x) == 0 ? 1 : (x))
  bs = bytes / nz(s);
  printf("%ld bytes %s in %.3g seconds (%ld bytes/s)\n",
      bytes, direction, s, bs);
 }
}

/*
void
tvadd(tsum, t0)
 struct timeval *tsum, *t0;
{

 tsum->tv_sec += t0->tv_sec;
 tsum->tv_usec += t0->tv_usec;
 if (tsum->tv_usec > 1000000)
  tsum->tv_sec++, tsum->tv_usec -= 1000000;
}
*/

void
tvsub(tdiff, t1, t0)
 struct timeval *tdiff, *t1, *t0;
{

 tdiff->tv_sec = t1->tv_sec - t0->tv_sec;
 tdiff->tv_usec = t1->tv_usec - t0->tv_usec;
 if (tdiff->tv_usec < 0)
  tdiff->tv_sec--, tdiff->tv_usec += 1000000;
}

void
psabort()
{

 abrtflag++;
}

void
pswitch(flag)
 int flag;
{
 sig_t oldintr;
 static struct comvars {
  int connect;
  char name[MAXHOSTNAMELEN];
  struct sockaddr_in mctl;
  struct sockaddr_in hctl;
  FILE *in;
  FILE *out;
  int tpe;
  int curtpe;
  int cpnd;
  int sunqe;
  int runqe;
  int mcse;
  int ntflg;
  char nti[17];
  char nto[17];
  int mapflg;
  char mi[MAXPATHLEN];
  char mo[MAXPATHLEN];
 } proxstruct, tmpstruct;
 struct comvars *ip, *op;

 abrtflag = 0;
 oldintr = signal(SIGINT, psabort);
 if (flag) {
  if (proxy)
   return;
  ip = &tmpstruct;
  op = &proxstruct;
  proxy++;
 } else {
  if (!proxy)
   return;
  ip = &proxstruct;
  op = &tmpstruct;
  proxy = 0;
 }
 ip->connect = connected;
 connected = op->connect;
 if (hostname) {
  (void) strncpy(ip->name, hostname, sizeof(ip->name) - 1);
  ip->name[strlen(ip->name)] = '\0';
 } else
  ip->name[0] = 0;
 hostname = op->name;
 ip->hctl = hisctladdr;
 hisctladdr = op->hctl;
 ip->mctl = myctladdr;
 myctladdr = op->mctl;
 ip->in = cin;
 cin = op->in;
 ip->out = cout;
 cout = op->out;
 ip->tpe = type;
 type = op->tpe;
 ip->curtpe = curtype;
 curtype = op->curtpe;
 ip->cpnd = cpend;
 cpend = op->cpnd;
 ip->sunqe = sunique;
 sunique = op->sunqe;
 ip->runqe = runique;
 runique = op->runqe;
 ip->mcse = mcase;
 mcase = op->mcse;
 ip->ntflg = ntflag;
 ntflag = op->ntflg;
 (void) strncpy(ip->nti, ntin, 16);
 (ip->nti)[strlen(ip->nti)] = '\0';
 (void) strcpy(ntin, op->nti);
 (void) strncpy(ip->nto, ntout, 16);
 (ip->nto)[strlen(ip->nto)] = '\0';
 (void) strcpy(ntout, op->nto);
 ip->mapflg = mapflag;
 mapflag = op->mapflg;
 (void) strncpy(ip->mi, mapin, MAXPATHLEN - 1);
 (ip->mi)[strlen(ip->mi)] = '\0';
 (void) strcpy(mapin, op->mi);
 (void) strncpy(ip->mo, mapout, MAXPATHLEN - 1);
 (ip->mo)[strlen(ip->mo)] = '\0';
 (void) strcpy(mapout, op->mo);
 (void) signal(SIGINT, oldintr);
 if (abrtflag) {
  abrtflag = 0;
  (*oldintr)(SIGINT);
 }
}

void
abortpt()
{

 printf("\n");
 (void) fflush(stdout);
 ptabflg++;
 mflag = 0;
 abrtflag = 0;
 longjmp(ptabort, 1);
}

void
proxtrans(cmd, local, remote)
 char *cmd, *local, *remote;
{
 sig_t oldintr;
 int secndflag = 0, prox_type, nfnd;
 char *cmd2;
 struct fd_set mask;

 if (strcmp(cmd, "RETR"))
  cmd2 = "RETR";
 else
  cmd2 = runique ? "STOU" : "STOR";
 if ((prox_type = type) == 0) {
  if (unix_server && unix_proxy)
   prox_type = TYPE_I;
  else
   prox_type = TYPE_A;
 }
 if (curtype != prox_type)
  changetype(prox_type, 1);
 if (command("PASV") != COMPLETE) {
  printf("proxy server does not support third party transfers.\n");
  return;
 }
 pswitch(0);
 if (!connected) {
  printf("No primary connection\n");
  pswitch(1);
  code = -1;
  return;
 }
 if (curtype != prox_type)
  changetype(prox_type, 1);
 if (command("PORT %s", pasv) != COMPLETE) {
  pswitch(1);
  return;
 }
 if (setjmp(ptabort))
  goto abort;
 oldintr = signal(SIGINT, abortpt);
 if (command("%s %s", cmd, remote) != PRELIM) {
  (void) signal(SIGINT, oldintr);
  pswitch(1);
  return;
 }
 sleep(2);
 pswitch(1);
 secndflag++;
 if (command("%s %s", cmd2, local) != PRELIM)
  goto abort;
 ptflag++;
 (void) getreply(0);
 pswitch(0);
 (void) getreply(0);
 (void) signal(SIGINT, oldintr);
 pswitch(1);
 ptflag = 0;
 printf("local: %s remote: %s\n", local, remote);
 return;
abort:
 (void) signal(SIGINT, SIG_IGN);
 ptflag = 0;
 if (strcmp(cmd, "RETR") && !proxy)
  pswitch(1);
 else if (!strcmp(cmd, "RETR") && proxy)
  pswitch(0);
 if (!cpend && !secndflag) {  /* only here if cmd = "STOR" (proxy=1) */
  if (command("%s %s", cmd2, local) != PRELIM) {
   pswitch(0);
   if (cpend)
    abort_remote((FILE *) NULL);
  }
  pswitch(1);
  if (ptabflg)
   code = -1;
  (void) signal(SIGINT, oldintr);
  return;
 }
 if (cpend)
  abort_remote((FILE *) NULL);
 pswitch(!proxy);
 if (!cpend && !secndflag) {  /* only if cmd = "RETR" (proxy=1) */
  if (command("%s %s", cmd2, local) != PRELIM) {
   pswitch(0);
   if (cpend)
    abort_remote((FILE *) NULL);
   pswitch(1);
   if (ptabflg)
    code = -1;
   (void) signal(SIGINT, oldintr);
   return;
  }
 }
 if (cpend)
  abort_remote((FILE *) NULL);
 pswitch(!proxy);
 if (cpend) {
  FD_ZERO(&mask);
  FD_SET(fileno(cin), &mask);
  if ((nfnd = empty(&mask, 10)) <= 0) {
   if (nfnd < 0) {
    warn("abort");
   }
   if (ptabflg)
    code = -1;
   lostpeer();
  }
  (void) getreply(0);
  (void) getreply(0);
 }
 if (proxy)
  pswitch(0);
 pswitch(1);
 if (ptabflg)
  code = -1;
 (void) signal(SIGINT, oldintr);
}

void
reset(argc, argv)
 int argc;
 char *argv[];
{
 struct fd_set mask;
 int nfnd = 1;

 FD_ZERO(&mask);
 while (nfnd > 0) {
  FD_SET(fileno(cin), &mask);
  if ((nfnd = empty(&mask,0)) < 0) {
   warn("reset");
   code = -1;
   lostpeer();
  }
  else if (nfnd) {
   (void) getreply(0);
  }
 }
}

char *
gunique(local)
 char *local;
{
 static char new[MAXPATHLEN];
 char *cp = strrchr(local, '/');
 int d, count=0;
 char ext = '1';

 if (cp)
  *cp = '\0';
 d = access(cp ? local : ".", 2);
 if (cp)
  *cp = '/';
 if (d < 0) {
  warn("local: %s", local);
  return ((char *) 0);
 }
 (void) strcpy(new, local);
 cp = new + strlen(new);
 *cp++ = '.';
 while (!d) {
  if (++count == 100) {
   printf("runique: can't find unique file name.\n");
   return ((char *) 0);
  }
  *cp++ = ext;
  *cp = '\0';
  if (ext == '9')
   ext = '0';
  else
   ext++;
  if ((d = access(new, 0)) < 0)
   break;
  if (ext != '0')
   cp--;
  else if (*(cp - 2) == '.')
   *(cp - 1) = '1';
  else {
   *(cp - 2) = *(cp - 2) + 1;
   cp--;
  }
 }
 return (new);
}

void
abort_remote(din)
 FILE *din;
{
 char buf[BUFSIZ];
 int nfnd;
 struct fd_set mask;

 /*
  * send IAC in urgent mode instead of DM because 4.3BSD places oob mark
  * after urgent byte rather than before as is protocol now
  */
 sprintf(buf, "%c%c%c", IAC, IP, IAC);
 if (send(fileno(cout), buf, 3, MSG_OOB) != 3)
  warn("abort");
 fprintf(cout,"%cABOR\r\n", DM);
 (void) fflush(cout);
 FD_ZERO(&mask);
 FD_SET(fileno(cin), &mask);
 if (din) { 
  FD_SET(fileno(din), &mask);
 }
 if ((nfnd = empty(&mask, 10)) <= 0) {
  if (nfnd < 0) {
   warn("abort");
  }
  if (ptabflg)
   code = -1;
  lostpeer();
 }
 if (din && FD_ISSET(fileno(din), &mask)) {
  while (read(fileno(din), buf, BUFSIZ) > 0)
   /* LOOP */;
 }
 if (getreply(0) == ERROR && code == 552) {
  /* 552 needed for nic style abort */
  (void) getreply(0);
 }
 (void) getreply(0);
}