cleanup logwtmp stuff, stupid mistakes

[unix-history] / usr / src / libexec / ftpd / ftpd.c

/*
* Copyright (c) 1985 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1985 Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)ftpd.c      5.17 (Berkeley) %G%";
#endif /* not lint */

/*
* FTP server.
*/
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/wait.h>

#include <netinet/in.h>

#include <arpa/ftp.h>
#include <arpa/inet.h>
#include <arpa/telnet.h>

#include <stdio.h>
#include <signal.h>
#include <pwd.h>
#include <setjmp.h>
#include <netdb.h>
#include <errno.h>
#include <strings.h>
#include <syslog.h>

/*
* File containing login names
* NOT to be used on this machine.
* Commonly used to disallow uucp.
*/
#define FTPUSERS        "/etc/ftpusers"

extern  int errno;
extern  char *sys_errlist[];
extern  char *crypt();
extern  char version[];
extern  char *home;             /* pointer to home directory for glob */
extern  FILE *popen(), *fopen(), *freopen();
extern  int  pclose(), fclose();
extern  char *getline();
extern  char cbuf[];

struct  sockaddr_in ctrl_addr;
struct  sockaddr_in data_source;
struct  sockaddr_in data_dest;
struct  sockaddr_in his_addr;

int     data;
jmp_buf errcatch, urgcatch;
int     logged_in;
struct  passwd *pw;
int     debug;
int     timeout = 900;    /* timeout after 15 minutes of inactivity */
int     logging;
int     guest;
int     type;
int     form;
int     stru;                   /* avoid C keyword */
int     mode;
int     usedefault = 1;         /* for data transfers */
int     pdata;                  /* for passive mode */
int     unique;
int     transflag;
char    tmpline[7];
char    hostname[32];
char    remotehost[32];

/*
* Timeout intervals for retrying connections
* to hosts that don't accept PORT cmds.  This
* is a kludge, but given the problems with TCP...
*/
#define SWAITMAX        90      /* wait at most 90 seconds */
#define SWAITINT        5       /* interval between retries */

int     swaitmax = SWAITMAX;
int     swaitint = SWAITINT;

int     lostconn();
int     myoob();
FILE    *getdatasock(), *dataconn();

main(argc, argv)
       int argc;
       char *argv[];
{
       int addrlen, on = 1;
       long pgid;
       char *cp;

       addrlen = sizeof (his_addr);
       if (getpeername(0, &his_addr, &addrlen) < 0) {
               syslog(LOG_ERR, "getpeername (%s): %m",argv[0]);
               exit(1);
       }
       addrlen = sizeof (ctrl_addr);
       if (getsockname(0, (char *) &ctrl_addr, &addrlen) < 0) {
               syslog(LOG_ERR, "getsockname (%s): %m",argv[0]);
               exit(1);
       }
       data_source.sin_port = htons(ntohs(ctrl_addr.sin_port) - 1);
       debug = 0;
       openlog("ftpd", LOG_PID, LOG_DAEMON);
       argc--, argv++;
       while (argc > 0 && *argv[0] == '-') {
               for (cp = &argv[0][1]; *cp; cp++) switch (*cp) {

               case 'v':
                       debug = 1;
                       break;

               case 'd':
                       debug = 1;
                       break;

               case 'l':
                       logging = 1;
                       break;

               case 't':
                       timeout = atoi(++cp);
                       goto nextopt;
                       break;

               default:
                       fprintf(stderr, "ftpd: Unknown flag -%c ignored.\n",
                            *cp);
                       break;
               }
nextopt:
               argc--, argv++;
       }
       (void) freopen("/dev/null", "w", stderr);
       (void) signal(SIGPIPE, lostconn);
       (void) signal(SIGCHLD, SIG_IGN);
       if ((int)signal(SIGURG, myoob) < 0)
               syslog(LOG_ERR, "signal: %m");

       /* handle urgent data inline */
#ifdef SO_OOBINLINE
       if (setsockopt(0, SOL_SOCKET, SO_OOBINLINE, (char *)&on, sizeof(on)) < 0) {
               syslog(LOG_ERR, "setsockopt: %m");
       }
#endif SO_OOBINLINE
       pgid = getpid();
       if (ioctl(fileno(stdin), SIOCSPGRP, (char *) &pgid) < 0) {
               syslog(LOG_ERR, "ioctl: %m");
       }
       dolog(&his_addr);
       /* do telnet option negotiation here */
       /*
        * Set up default state
        */
       data = -1;
       type = TYPE_A;
       form = FORM_N;
       stru = STRU_F;
       mode = MODE_S;
       tmpline[0] = '\0';
       (void) gethostname(hostname, sizeof (hostname));
       reply(220, "%s FTP server (%s) ready.",
               hostname, version);
       for (;;) {
               (void) setjmp(errcatch);
               (void) yyparse();
       }
}

lostconn()
{

       if (debug)
               syslog(LOG_DEBUG, "lost connection");
       dologout(-1);
}

static char ttyline[20];

/*
* Helper function for sgetpwnam().
*/
char *
sgetsave(s)
       char *s;
{
#ifdef notdef
       char *new = strdup(s);
#else
       char *malloc();
       char *new = malloc((unsigned) strlen(s) + 1);
#endif
       
       if (new == NULL) {
               reply(553, "Local resource failure");
               dologout(1);
       }
#ifndef notdef
       (void) strcpy(new, s);
#endif
       return (new);
}

/*
* Save the result of a getpwnam.  Used for USER command, since
* the data returned must not be clobbered by any other command
* (e.g., globbing).
*/
struct passwd *
sgetpwnam(name)
       char *name;
{
       static struct passwd save;
       register struct passwd *p;
       char *sgetsave();

       if ((p = getpwnam(name)) == NULL)
               return (p);
       if (save.pw_name) {
               free(save.pw_name);
               free(save.pw_passwd);
               free(save.pw_comment);
               free(save.pw_gecos);
               free(save.pw_dir);
               free(save.pw_shell);
       }
       save = *p;
       save.pw_name = sgetsave(p->pw_name);
       save.pw_passwd = sgetsave(p->pw_passwd);
       save.pw_comment = sgetsave(p->pw_comment);
       save.pw_gecos = sgetsave(p->pw_gecos);
       save.pw_dir = sgetsave(p->pw_dir);
       save.pw_shell = sgetsave(p->pw_shell);
       return (&save);
}

pass(passwd)
       char *passwd;
{
       char *xpasswd;

       if (logged_in || pw == NULL) {
               reply(503, "Login with USER first.");
               return;
       }
       if (!guest) {           /* "ftp" is only account allowed no password */
               xpasswd = crypt(passwd, pw->pw_passwd);
               /* The strcmp does not catch null passwords! */
               if (*pw->pw_passwd == '\0' || strcmp(xpasswd, pw->pw_passwd)) {
                       reply(530, "Login incorrect.");
                       pw = NULL;
                       return;
               }
       }
       setegid(pw->pw_gid);
       initgroups(pw->pw_name, pw->pw_gid);
       if (chdir(pw->pw_dir)) {
               reply(530, "User %s: can't change directory to %s.",
                       pw->pw_name, pw->pw_dir);
               goto bad;
       }

       /* open wtmp before chroot */
       (void)sprintf(ttyline, "ftp%d", getpid());
       logwtmp(ttyline, pw->pw_name, remotehost);
       logged_in = 1;

       if (guest) {
               if (chroot(pw->pw_dir) < 0) {
                       reply(550, "Can't set guest privileges.");
                       goto bad;
               }
               reply(230, "Guest login ok, access restrictions apply.");
       } else
               reply(230, "User %s logged in.", pw->pw_name);
       seteuid(pw->pw_uid);
       home = pw->pw_dir;              /* home dir for globbing */
       return;
bad:
       seteuid(0);
       pw = NULL;
}

retrieve(cmd, name)
       char *cmd, *name;
{
       FILE *fin, *dout;
       struct stat st;
       int (*closefunc)(), tmp;

       if (cmd == 0) {
#ifdef notdef
               /* no remote command execution -- it's a security hole */
               if (*name == '|')
                       fin = popen(name + 1, "r"), closefunc = pclose;
               else
#endif
                       fin = fopen(name, "r"), closefunc = fclose;
       } else {
               char line[BUFSIZ];

               (void) sprintf(line, cmd, name), name = line;
               fin = popen(line, "r"), closefunc = pclose;
       }
       if (fin == NULL) {
               if (errno != 0)
                       reply(550, "%s: %s.", name, sys_errlist[errno]);
               return;
       }
       st.st_size = 0;
       if (cmd == 0 &&
           (stat(name, &st) < 0 || (st.st_mode&S_IFMT) != S_IFREG)) {
               reply(550, "%s: not a plain file.", name);
               goto done;
       }
       dout = dataconn(name, st.st_size, "w");
       if (dout == NULL)
               goto done;
       if ((tmp = send_data(fin, dout)) > 0 || ferror(dout) > 0) {
               reply(550, "%s: %s.", name, sys_errlist[errno]);
       }
       else if (tmp == 0) {
               reply(226, "Transfer complete.");
       }
       (void) fclose(dout);
       data = -1;
       pdata = -1;
done:
       (*closefunc)(fin);
}

store(name, mode)
       char *name, *mode;
{
       FILE *fout, *din;
       int (*closefunc)(), dochown = 0, tmp;
       char *gunique(), *local;

#ifdef notdef
       /* no remote command execution -- it's a security hole */
       if (name[0] == '|')
               fout = popen(&name[1], "w"), closefunc = pclose;
       else
#endif
       {
               struct stat st;

               local = name;
               if (stat(name, &st) < 0) {
                       dochown++;
               }
               else if (unique) {
                       if ((local = gunique(name)) == NULL) {
                               return;
                       }
                       dochown++;
               }
               fout = fopen(local, mode), closefunc = fclose;
       }
       if (fout == NULL) {
               reply(553, "%s: %s.", local, sys_errlist[errno]);
               return;
       }
       din = dataconn(local, (off_t)-1, "r");
       if (din == NULL)
               goto done;
       if ((tmp = receive_data(din, fout)) > 0 || ferror(fout) > 0) {
               reply(552, "%s: %s.", local, sys_errlist[errno]);
       }
       else if (tmp == 0 && !unique) {
               reply(226, "Transfer complete.");
       }
       else if (tmp == 0 && unique) {
               reply(226, "Transfer complete (unique file name:%s).", local);
       }
       (void) fclose(din);
       data = -1;
       pdata = -1;
done:
       if (dochown)
               (void) chown(local, pw->pw_uid, -1);
       (*closefunc)(fout);
}

FILE *
getdatasock(mode)
       char *mode;
{
       int s, on = 1;

       if (data >= 0)
               return (fdopen(data, mode));
       s = socket(AF_INET, SOCK_STREAM, 0);
       if (s < 0)
               return (NULL);
       seteuid(0);
       if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &on, sizeof (on)) < 0)
               goto bad;
       /* anchor socket to avoid multi-homing problems */
       data_source.sin_family = AF_INET;
       data_source.sin_addr = ctrl_addr.sin_addr;
       if (bind(s, &data_source, sizeof (data_source)) < 0)
               goto bad;
       seteuid(pw->pw_uid);
       return (fdopen(s, mode));
bad:
       seteuid(pw->pw_uid);
       (void) close(s);
       return (NULL);
}

FILE *
dataconn(name, size, mode)
       char *name;
       off_t size;
       char *mode;
{
       char sizebuf[32];
       FILE *file;
       int retry = 0;

       if (size >= 0)
               (void) sprintf (sizebuf, " (%ld bytes)", size);
       else
               (void) strcpy(sizebuf, "");
       if (pdata > 0) {
               struct sockaddr_in from;
               int s, fromlen = sizeof(from);

               s = accept(pdata, &from, &fromlen);
               if (s < 0) {
                       reply(425, "Can't open data connection.");
                       (void) close(pdata);
                       pdata = -1;
                       return(NULL);
               }
               (void) close(pdata);
               pdata = s;
               reply(150, "Opening data connection for %s (%s mode)%s.",
                    name, type == TYPE_A ? "ascii" : "binary", sizebuf);
               return(fdopen(pdata, mode));
       }
       if (data >= 0) {
               reply(125, "Using existing data connection for %s%s.",
                   name, sizebuf);
               usedefault = 1;
               return (fdopen(data, mode));
       }
       if (usedefault)
               data_dest = his_addr;
       usedefault = 1;
       file = getdatasock(mode);
       if (file == NULL) {
               reply(425, "Can't create data socket (%s,%d): %s.",
                   inet_ntoa(data_source.sin_addr),
                   ntohs(data_source.sin_port),
                   sys_errlist[errno]);
               return (NULL);
       }
       data = fileno(file);
       while (connect(data, &data_dest, sizeof (data_dest)) < 0) {
               if (errno == EADDRINUSE && retry < swaitmax) {
                       sleep((unsigned) swaitint);
                       retry += swaitint;
                       continue;
               }
               reply(425, "Can't build data connection: %s.",
                   sys_errlist[errno]);
               (void) fclose(file);
               data = -1;
               return (NULL);
       }
       reply(150, "Opening data connection for %s (%s mode)%s.",
           name, type == TYPE_A ? "ascii" : "binary", sizebuf);
       return (file);
}

/*
* Tranfer the contents of "instr" to
* "outstr" peer using the appropriate
* encapulation of the date subject
* to Mode, Structure, and Type.
*
* NB: Form isn't handled.
*/
send_data(instr, outstr)
       FILE *instr, *outstr;
{
       register int c;
       int netfd, filefd, cnt;
       char buf[BUFSIZ];

       transflag++;
       if (setjmp(urgcatch)) {
               transflag = 0;
               return(-1);
       }
       switch (type) {

       case TYPE_A:
               while ((c = getc(instr)) != EOF) {
                       if (c == '\n') {
                               if (ferror (outstr)) {
                                       transflag = 0;
                                       return (1);
                               }
                               (void) putc('\r', outstr);
                       }
                       (void) putc(c, outstr);
               /*      if (c == '\r')                  */
               /*              putc ('\0', outstr);    */
               }
               transflag = 0;
               if (ferror (instr) || ferror (outstr)) {
                       return (1);
               }
               return (0);
               
       case TYPE_I:
       case TYPE_L:
               netfd = fileno(outstr);
               filefd = fileno(instr);

               while ((cnt = read(filefd, buf, sizeof (buf))) > 0) {
                       if (write(netfd, buf, cnt) < 0) {
                               transflag = 0;
                               return (1);
                       }
               }
               transflag = 0;
               return (cnt < 0);
       }
       reply(550, "Unimplemented TYPE %d in send_data", type);
       transflag = 0;
       return (-1);
}

/*
* Transfer data from peer to
* "outstr" using the appropriate
* encapulation of the data subject
* to Mode, Structure, and Type.
*
* N.B.: Form isn't handled.
*/
receive_data(instr, outstr)
       FILE *instr, *outstr;
{
       register int c;
       int cnt;
       char buf[BUFSIZ];


       transflag++;
       if (setjmp(urgcatch)) {
               transflag = 0;
               return(-1);
       }
       switch (type) {

       case TYPE_I:
       case TYPE_L:
               while ((cnt = read(fileno(instr), buf, sizeof buf)) > 0) {
                       if (write(fileno(outstr), buf, cnt) < 0) {
                               transflag = 0;
                               return (1);
                       }
               }
               transflag = 0;
               return (cnt < 0);

       case TYPE_E:
               reply(553, "TYPE E not implemented.");
               transflag = 0;
               return (-1);

       case TYPE_A:
               while ((c = getc(instr)) != EOF) {
                       while (c == '\r') {
                               if (ferror (outstr)) {
                                       transflag = 0;
                                       return (1);
                               }
                               if ((c = getc(instr)) != '\n')
                                       (void) putc ('\r', outstr);
                       /*      if (c == '\0')                  */
                       /*              continue;               */
                       }
                       (void) putc (c, outstr);
               }
               transflag = 0;
               if (ferror (instr) || ferror (outstr))
                       return (1);
               return (0);
       }
       transflag = 0;
       fatal("Unknown type in receive_data.");
       /*NOTREACHED*/
}

fatal(s)
       char *s;
{
       reply(451, "Error in server: %s\n", s);
       reply(221, "Closing connection due to server error.");
       dologout(0);
}

reply(n, s, p0, p1, p2, p3, p4)
       int n;
       char *s;
{

       printf("%d ", n);
       printf(s, p0, p1, p2, p3, p4);
       printf("\r\n");
       (void) fflush(stdout);
       if (debug) {
               syslog(LOG_DEBUG, "<--- %d ", n);
               syslog(LOG_DEBUG, s, p0, p1, p2, p3, p4);
       }
}

lreply(n, s, p0, p1, p2, p3, p4)
       int n;
       char *s;
{
       printf("%d-", n);
       printf(s, p0, p1, p2, p3, p4);
       printf("\r\n");
       (void) fflush(stdout);
       if (debug) {
               syslog(LOG_DEBUG, "<--- %d- ", n);
               syslog(LOG_DEBUG, s, p0, p1, p2, p3, p4);
       }
}

ack(s)
       char *s;
{
       reply(250, "%s command successful.", s);
}

nack(s)
       char *s;
{
       reply(502, "%s command not implemented.", s);
}

yyerror(s)
       char *s;
{
       char *cp;

       cp = index(cbuf,'\n');
       *cp = '\0';
       reply(500, "'%s': command not understood.",cbuf);
}

delete(name)
       char *name;
{
       struct stat st;

       if (stat(name, &st) < 0) {
               reply(550, "%s: %s.", name, sys_errlist[errno]);
               return;
       }
       if ((st.st_mode&S_IFMT) == S_IFDIR) {
               if (rmdir(name) < 0) {
                       reply(550, "%s: %s.", name, sys_errlist[errno]);
                       return;
               }
               goto done;
       }
       if (unlink(name) < 0) {
               reply(550, "%s: %s.", name, sys_errlist[errno]);
               return;
       }
done:
       ack("DELE");
}

cwd(path)
       char *path;
{

       if (chdir(path) < 0) {
               reply(550, "%s: %s.", path, sys_errlist[errno]);
               return;
       }
       ack("CWD");
}

makedir(name)
       char *name;
{
       struct stat st;
       int dochown = stat(name, &st) < 0;
       
       if (mkdir(name, 0777) < 0) {
               reply(550, "%s: %s.", name, sys_errlist[errno]);
               return;
       }
       if (dochown)
               (void) chown(name, pw->pw_uid, -1);
       reply(257, "MKD command successful.");
}

removedir(name)
       char *name;
{

       if (rmdir(name) < 0) {
               reply(550, "%s: %s.", name, sys_errlist[errno]);
               return;
       }
       ack("RMD");
}

pwd()
{
       char path[MAXPATHLEN + 1];

       if (getwd(path) == NULL) {
               reply(550, "%s.", path);
               return;
       }
       reply(257, "\"%s\" is current directory.", path);
}

char *
renamefrom(name)
       char *name;
{
       struct stat st;

       if (stat(name, &st) < 0) {
               reply(550, "%s: %s.", name, sys_errlist[errno]);
               return ((char *)0);
       }
       reply(350, "File exists, ready for destination name");
       return (name);
}

renamecmd(from, to)
       char *from, *to;
{

       if (rename(from, to) < 0) {
               reply(550, "rename: %s.", sys_errlist[errno]);
               return;
       }
       ack("RNTO");
}

dolog(sin)
       struct sockaddr_in *sin;
{
       struct hostent *hp = gethostbyaddr(&sin->sin_addr,
               sizeof (struct in_addr), AF_INET);
       time_t t;
       extern char *ctime();

       if (hp) {
               (void) strncpy(remotehost, hp->h_name, sizeof (remotehost));
               endhostent();
       } else
               (void) strncpy(remotehost, inet_ntoa(sin->sin_addr),
                   sizeof (remotehost));
       if (!logging)
               return;
       t = time((time_t *) 0);
       syslog(LOG_INFO,"FTPD: connection from %s at %s", remotehost, ctime(&t));
}

/*
* Record logout in wtmp file
* and exit with supplied status.
*/
dologout(status)
       int status;
{
       if (logged_in) {
               (void) seteuid(0);
               logwtmp(ttyline, "", "");
       }
       /* beware of flushing buffers after a SIGPIPE */
       _exit(status);
}

/*
* Check user requesting login priviledges.
* Disallow anyone who does not have a standard
* shell returned by getusershell() (/etc/shells).
* Disallow anyone mentioned in the file FTPUSERS
* to allow people such as uucp to be avoided.
*/
checkuser(name)
       register char *name;
{
       register char *cp;
       FILE *fd;
       struct passwd *p;
       char *shell;
       int found = 0;
       char line[BUFSIZ], *index(), *getusershell();

       if ((p = getpwnam(name)) == NULL)
               return (0);
       if ((shell = p->pw_shell) == NULL || *shell == 0)
               shell = "/bin/sh";
       while ((cp = getusershell()) != NULL)
               if (strcmp(cp, shell) == 0)
                       break;
       endusershell();
       if (cp == NULL)
               return (0);
       if ((fd = fopen(FTPUSERS, "r")) == NULL)
               return (1);
       while (fgets(line, sizeof (line), fd) != NULL) {
               if ((cp = index(line, '\n')) != NULL)
                       *cp = '\0';
               if (strcmp(line, name) == 0) {
                       found++;
                       break;
               }
       }
       (void) fclose(fd);
       return (!found);
}

myoob()
{
       char *cp;

       /* only process if transfer occurring */
       if (!transflag) {
               return;
       }
       cp = tmpline;
       if (getline(cp, 7, stdin) == NULL) {
               reply(221, "You could at least say goodby.");
               dologout(0);
       }
       upper(cp);
       if (strcmp(cp, "ABOR\r\n"))
               return;
       tmpline[0] = '\0';
       reply(426,"Transfer aborted. Data connection closed.");
       reply(226,"Abort successful");
       longjmp(urgcatch, 1);
}

/*
* Note: The 530 reply codes could be 4xx codes, except nothing is
* given in the state tables except 421 which implies an exit.  (RFC959)
*/
passive()
{
       int len;
       struct sockaddr_in tmp;
       register char *p, *a;

       pdata = socket(AF_INET, SOCK_STREAM, 0);
       if (pdata < 0) {
               reply(530, "Can't open passive connection");
               return;
       }
       tmp = ctrl_addr;
       tmp.sin_port = 0;
       seteuid(0);
       if (bind(pdata, (struct sockaddr *) &tmp, sizeof(tmp)) < 0) {
               seteuid(pw->pw_uid);
               (void) close(pdata);
               pdata = -1;
               reply(530, "Can't open passive connection");
               return;
       }
       seteuid(pw->pw_uid);
       len = sizeof(tmp);
       if (getsockname(pdata, (char *) &tmp, &len) < 0) {
               (void) close(pdata);
               pdata = -1;
               reply(530, "Can't open passive connection");
               return;
       }
       if (listen(pdata, 1) < 0) {
               (void) close(pdata);
               pdata = -1;
               reply(530, "Can't open passive connection");
               return;
       }
       a = (char *) &tmp.sin_addr;
       p = (char *) &tmp.sin_port;

#define UC(b) (((int) b) & 0xff)

       reply(227, "Entering Passive Mode (%d,%d,%d,%d,%d,%d)", UC(a[0]),
               UC(a[1]), UC(a[2]), UC(a[3]), UC(p[0]), UC(p[1]));
}

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

       if (cp) {
               *cp = '\0';
       }
       d = access(cp ? local : ".", 2);
       if (cp) {
               *cp = '/';
       }
       if (d < 0) {
               syslog(LOG_ERR, "%s: %m", local);
               return((char *) 0);
       }
       (void) strcpy(new, local);
       cp = new + strlen(new);
       *cp++ = '.';
       while (!d) {
               if (++count == 100) {
                       reply(452, "Unique file name not cannot be created.");
                       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);
}