Fixed a problem where the server might segfault if there was an error occuring while...

[betaftpd] / cmds.c

/*  cmds.c: BetaFTPD command handlers
    Copyright (C) 1999-2000 Steinar H. Gunderson

    This program is is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2 of the
    License as published by the Free Software Foundation.

    This program 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#define _GNU_SOURCE

#if HAVE_CONFIG_H
#include <config.h>
#endif

#if HAVE_STROPTS_H
#include <stropts.h>
#endif

#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
 
#if HAVE_SYS_CONF_H
#include <sys/conf.h>
#endif

#if HAVE_DIRENT_H
#include <dirent.h>
#endif

#if HAVE_CRYPT_H
#include <crypt.h>
#endif

#if HAVE_ERRNO_H
#include <errno.h>
#endif

#if HAVE_GLOB_H
#include <glob.h>
#endif

#if HAVE_STDIO_H
#include <stdio.h>
#endif

#if HAVE_STDLIB_H
#include <stdlib.h>
#endif

#if HAVE_STRING_H
#include <string.h>
#endif

#if HAVE_STRINGS_H
#include <strings.h>
#endif

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

#if HAVE_TIME_H
#include <time.h>
#endif

#if HAVE_FCNTL_H
#include <fcntl.h>
#endif

#if HAVE_GRP_H
#include <grp.h>
#endif

#if HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif

#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

#if HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

#if HAVE_STROPTS_H
#include <stropts.h>
#endif

#if HAVE_SYS_CONF_H
#include <sys/conf.h>
#endif

#if HAVE_SHADOW_H
#include <shadow.h>
#endif

#if HAVE_SYS_FILIO_H
#include <sys/filio.h>
#endif

#if HAVE_SYS_POLL_H
#include <sys/poll.h>
#endif

#if WANT_NONROOT
#define NO_SETUID
#define DO_SETUID
#else
#define NO_SETUID ,0
#define DO_SETUID ,1
#endif

#ifndef NBBY
#define NBBY 8
#endif

#include <ftpd.h>
#include <cmds.h>
#include <nonroot.h>

#if WANT_DCACHE
#include <dcache.h>
#endif

#define lstat stat

extern struct conn *first_conn;
#if WANT_DCACHE
extern struct dcache *first_dcache;
#endif

#if HAVE_POLL
extern struct pollfd fds[];
#else
extern fd_set master_fds, master_send_fds;
#endif

struct handler {
        char cmd_name[6];
        char add_cmlen;         /* =1 if the command takes an argument */
        void (*callback)(struct conn * const);
        char min_auth;
#if !WANT_NONROOT
        char do_setuid;         /* =1 if root is not *really* needed */
#endif
};

static const struct handler handler_table[] = {
        { "user ", 1, cmd_user, 0       NO_SETUID },
        { "pass ", 1, cmd_pass, 1       NO_SETUID },
        { "retr ", 1, cmd_retr, 3       DO_SETUID },
        { "acct ", 1, cmd_acct, 0       NO_SETUID },
        { "port ", 1, cmd_port, 3       DO_SETUID },
        { "pasv" , 0, cmd_pasv, 3       DO_SETUID },
        { "pwd"  , 0, cmd_pwd,  3       DO_SETUID },
        { "cwd " , 1, cmd_cwd,  3       DO_SETUID },
        { "cdup" , 0, cmd_cdup, 3       DO_SETUID },
        { "rest ", 1, cmd_rest, 3       DO_SETUID },
        { "list" , 0, cmd_list, 3       DO_SETUID },
        { "nlst" , 0, cmd_nlst, 3       DO_SETUID },
        { "type ", 1, cmd_type, 3       DO_SETUID },
        { "mode ", 1, cmd_mode, 3       DO_SETUID },
        { "stru ", 1, cmd_stru, 3       DO_SETUID },
        { "size ", 1, cmd_size, 3       DO_SETUID },
        { "mdtm ", 1, cmd_mdtm, 3       DO_SETUID },
        { "abor" , 0, cmd_abor, 3       DO_SETUID },
        { "dele ", 1, cmd_dele, 3       DO_SETUID },
        { "rnfr ", 1, cmd_rnfr, 3       DO_SETUID },
        { "rnto ", 1, cmd_rnto, 3       DO_SETUID },
        { "mkd " , 1, cmd_mkd,  3       DO_SETUID },
        { "rmd " , 1, cmd_rmd,  3       DO_SETUID },
        { "allo ", 1, cmd_allo, 3       DO_SETUID },
        { "stat" , 0, cmd_stat, 0       NO_SETUID },
        { "noop" , 0, cmd_noop, 0       DO_SETUID },
        { "syst" , 0, cmd_syst, 0       DO_SETUID },
        { "help" , 0, cmd_help, 0       NO_SETUID },
        { "quit" , 0, cmd_quit, 0       DO_SETUID },
        { "rein" , 0, cmd_rein, 0       DO_SETUID },

        /* deprecated forms */
        { "xcup" , 0, cmd_cdup, 3       DO_SETUID },
        { "xcwd ", 1, cmd_cwd,  3       DO_SETUID },
        { "xpwd" , 0, cmd_pwd,  3       DO_SETUID },
        { "xmkd ", 1, cmd_mkd,  3       DO_SETUID },
        { "xrmd ", 1, cmd_rmd,  3       DO_SETUID },
#if WANT_UPLOAD
        { "stor ", 1, cmd_stor, 3       DO_SETUID },
        { "appe ", 1, cmd_appe, 3       DO_SETUID },
#endif
#if DOING_PROFILING
#warning Use DOING_PROFILING with caution, and NEVER on a production server! :-)
        { "exit",  0, cmd_exit, 0       NO_SETUID },
#endif
        { ""    ,  0, NULL,     0       NO_SETUID }
};

/*
 * do_chdir():  Does a chdir() to newd on c, staying inside the
 *              limits of root_dir. Use this instead of a chdir() whenever
 *              you can, and possibly even when you can't :-)
 *
 *              This command quirks around some problems in the rest of
 *              the code (namely translate_path()), so a blank newdir is
 *              interpreted as the root directory.
 */
int do_chdir(struct conn * const c, const char * const newd)
{
        char chd[512], temp[512];

        TRAP_ERROR(chdir(c->curr_dir) == -1, 550, return -1);

        /* handle `absolute' paths */
        if (newd[0] == '/' || newd[0] == '\0') {
                strcpy(temp, c->root_dir);

                /*
                 * is this the root directory? if not, remove the trailing `/'
                 * and concatenate the new directory on
                 */
                if (newd[1] != '\0' && newd[0] != '\0') {
                        temp[strlen(temp) - 1] = 0;
                        strcat(temp, newd);
                }
        } else {
                strcpy(temp, newd);
        }

#if WANT_NONROOT
        if (nr_check_permission(c->uid, temp, 1, 1, NULL) == -1) {
                numeric(c, 550, "Permission denied");
                return -1;
        }
#endif

        TRAP_ERROR(chdir(temp) == -1, 550, return -1);

        getcwd(chd, 254);
        if (chd[strlen(chd) - 1] != '/') {
                strcat(chd, "/");
        }

        if (strncmp(chd, c->root_dir, strlen(c->root_dir)) != 0) {
                numeric(c, 550, "No such file or directory.");
                return -1;
        }

        return 0;
}

/*
 * cmd_user():  Handles the USER command, and does most of the initial
 *              authentication work. User names are limited to 16
 *              characters, by force...
 */
void cmd_user(struct conn * const c)
{
        strncpy(c->username, c->recv_buf, 16);
        c->username[16] = 0;

        if (strcasecmp(c->username, "anonymous") == 0) {
                strcpy(c->username, "ftp");
        }
        if (strcasecmp(c->username, "ftp") == 0) {
                numeric(c, 331, "Login OK, send password (your e-mail).");
                c->auth = 1;
        } else {
                numeric(c, 331, "Password required for %s.", c->username);
                c->auth = 2;
        }
}

/*
 * cmd_pass():  Handles the PASS command, and checks the password.
 *              This function is rather long and complicated, mostly
 *              because there are so many ways of doing users
 *              (including my nonroot system) out there... And we
 *              don't even support PAM or real shadow passwords (with
 *              expiry etc) yet...
 */
void cmd_pass(struct conn * const c)
{
#if WANT_NONROOT
        c->auth = nr_userinfo(c->username, &c->uid, c->curr_dir, c->root_dir,
                              c->recv_buf);
#else /* !WANT_NONROOT */
#if WANT_SHADOW && HAVE_SHADOW_H
        struct spwd *s;
#endif
        struct passwd *p;

        p = getpwnam(c->username);
#if WANT_SHADOW && HAVE_SHADOW_H
        s = getspnam(c->username);
#endif
        
        if (p == NULL) {
                c->auth = 0;
        } else {
                c->uid = p->pw_uid;
                c->gid = p->pw_gid;
                strncpy(c->curr_dir, p->pw_dir, 254);
                c->curr_dir[254] = 0;
        }

        if (c->auth == 1) {
                if (c->curr_dir[strlen(c->curr_dir) - 1] != '/') {
                        strcat(c->curr_dir, "/");
                }
                strcpy(c->root_dir, c->curr_dir);       
                c->auth = 3;
        } else if (c->auth != 0) {
                strcpy(c->root_dir, "/");
                if (strcmp(crypt(c->recv_buf, p->pw_passwd), p->pw_passwd) != 0
#if WANT_SHADOW && HAVE_SHADOW_H
                    && (s == NULL || strcmp(crypt(c->recv_buf, s->sp_pwdp), s->sp_pwdp) != 0)
#endif
                ) {
                        c->auth = 0;
                } else {
                        c->auth = 4;
                }
        }
#endif /* !WANT_NONROOT */

        /* root should not be allowed to FTP */
        if (c->uid == 0) {
                c->auth = 0;
        }
        if (c->auth == 0) {
                numeric(c, 530, "Login incorrect.");
        } else {
#if WANT_MESSAGE
                chdir(c->curr_dir);
                dump_file(c, 230, "welcome.msg");
#endif
                /* Have a different message for anonymous users? */
                numeric(c, 230, "User logged in.");
        }
}

/*
 * cmd_acct():  Handle (ignore) the ACCT command. I don't see how we
 *              could make use of this command... wu-ftpd doesn't, either.
 *              However, wu-ftpd (at least the version I have here) uses
 *              502, which isn't a legal error code according to RFC959.
 *              202, on the other hand, is, and seems to be applicable.
 *
 *              I'm unsure if this one should require setuid or not, but
 *              I feel that the RFC959 intention is having it _before_
 *              USER/PASS. Therefore, this one runs with root privilegies :-)
 */
void cmd_acct(struct conn * const c)
{
        numeric(c, 202, "ACCT ignored OK -- not applicable on this system.");
}

/*
 * cmd_port():  Handles the PORT command, and sets up the data socket.
 *              Making a brief uid=0 (root) appearance (to bind the socket) --
 *              I feel it's safer that way (instead of running as root
 *              the whole way), in case there are some weird overflows
 *              somewhere.
 */
void cmd_port(struct conn * const c)
{
        short int a0, a1, a2, a3, p0, p1;
        int i, sock, err;
        struct ftran *f;
        struct sockaddr_in sin;
    
        if ((c->transfer != NULL) && (c->transfer->state >= 4)) {
                numeric(c, 500, "Sorry, only one transfer at a time.");
                return;
        }

        sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        TRAP_ERROR(sock == -1, 500, return);

        destroy_ftran(c->transfer);
        c->transfer = f = alloc_new_ftran(sock, c);

        i = sscanf(c->recv_buf, "%3hu,%3hu,%3hu,%3hu,%3hu,%3hu", &a0, &a1, &a2, &a3, &p0, &p1);
        if (i < 6) {
                numeric(c, 501, "Parse error.");
        } else {
                const int one = 1;
                int tmp;

                /* bind to own address, port 20 (FTP data) */
                tmp = sizeof(sin);
                err = getsockname(c->sock, (struct sockaddr *)&sin, &tmp);
                TRAP_ERROR(err == -1, 500, return);
                sin.sin_port = FTP_PORT - 1;

                numeric(c, 200, "PORT command OK.");

                /* note that bind() might well fail, so we don't error check */
#if !WANT_NONROOT
                /* need root privilegies for a short while */
                seteuid(getuid());
                setegid(getgid());
#endif
                bind(sock, (struct sockaddr *)&sin, sizeof(sin));
#if !WANT_NONROOT
                setegid(c->gid);
                seteuid(c->uid);
#endif

                f->sin.sin_family = AF_INET;
                f->sin.sin_addr.s_addr = htonl(
                        ((unsigned char)(a0) << 24) +
                        ((unsigned char)(a1) << 16) +
                        ((unsigned char)(a2) <<  8) +
                        ((unsigned char)(a3)      ));
                f->sin.sin_port = htons(
                        ((unsigned char)(p0) << 8) +
                        ((unsigned char)(p1)     ));
                f->sock = sock;
                f->state = 3;

                i = 1;          
                ioctl(f->sock, FIONBIO, &one);
        }
}

/*
 * cmd_pasv():  Handles the PASV command, and sets up the data socket.
 *              Uses port numbers > 1024, since it doesn't run as root.
 */
void cmd_pasv(struct conn * const c)
{
        struct ftran *f;
        int tmp, sock, err;
        unsigned int one = 1;
        struct sockaddr_in addr;

        if ((c->transfer != NULL) && (c->transfer->state >= 4)) {
                numeric(c, 503, "Sorry, only one transfer at once.");
                return;
        }
        destroy_ftran(c->transfer);

        sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        TRAP_ERROR(sock == -1, 500, return);
        err = add_fd(sock, POLLIN);
        TRAP_ERROR(err != 0, 501, return);

        c->transfer = f = alloc_new_ftran(sock, c);

        ioctl(sock, FIONBIO, &one);

        /* setup socket */
        tmp = sizeof(addr);
        err = getsockname(c->sock, (struct sockaddr *)&addr, &tmp);
        TRAP_ERROR(err == -1, 500, return);

        addr.sin_port = 0;      /* let the system choose */
        err = bind(sock, (struct sockaddr *)&addr, sizeof(struct sockaddr));
        TRAP_ERROR(err == -1, 500, return);

        tmp = sizeof(addr);
        err = getsockname(sock, (struct sockaddr *)&addr, &tmp);
        TRAP_ERROR(err == -1, 500, return);

        err = listen(f->sock, 1);
        TRAP_ERROR(err == -1, 500, return);
        f->state = 1;

        numeric(c, 227, "Entering passive mode (%u,%u,%u,%u,%u,%u)",
                (htonl(addr.sin_addr.s_addr) & 0xff000000) >> 24,
                (htonl(addr.sin_addr.s_addr) & 0x00ff0000) >> 16,
                (htonl(addr.sin_addr.s_addr) & 0x0000ff00) >>  8,
                (htonl(addr.sin_addr.s_addr) & 0x000000ff),
                (htons(addr.sin_port) & 0xff00) >> 8,
                (htons(addr.sin_port) & 0x00ff));
}

/*
 * cmd_pwd():   Handles PWD command (print working directory).
 *
 *              Note that if somebody contacts you with the message `the server
 *              says curr_dir() is outside root_dir()', you should fix your
 *              /betaftpd.users file, if you use nonroot. If not, it's a bug.
 *              Try to get it _reproducible_, and mail it to me.
 */
void cmd_pwd(struct conn * const c)
{
        char temp[512], *cdir = NULL;

        cdir = do_pwd(c, temp, c->curr_dir);
        if (cdir != NULL) {
                numeric(c, 257, "\"%s\" is current working directory.", cdir);
        }
}

/*
 * do_pwd():    Translates an absolute path to a path suitable for viewing
 *              to the user (ie. removes the root_dir, and removes a trailing
 *              slash if it exists). Note that the retbuf is only used as a
 *              storage place -- the pointer to the right place within retbuf
 *              is _returned_.
 */
char *do_pwd(struct conn * const c, char * const retbuf, const char * const dir) 
{
        char *cdir = NULL;

        strcpy(retbuf, dir);

        if (strncmp(retbuf, c->root_dir, strlen(c->root_dir)) != 0) {
                numeric(c, 550, "curr_dir is outside root_dir, please contact site administrator.");
                return NULL;
        }

        cdir = retbuf + strlen(c->root_dir) - 1;
        if (cdir[strlen(cdir) - 1] == '/' && strlen(cdir) > 1) {
                cdir[strlen(cdir) - 1] = 0;
        } else if (strlen(cdir) == 0) {
                strcpy(cdir, "/");
        }       

        return cdir;
}

/*
 * cmd_cwd():   Handles CWD command (change working directory). Uses
 *              cmd_cwd_internal() (see below).
 */
void cmd_cwd(struct conn * const c)
{
        cmd_cwd_internal(c, c->recv_buf);
}

/*
 * cmd_cdup():  Handles a CDUP command (identical to `CWD ..'). Note that
 *              RFC959 gives two different response codes (250 and 200) --
 *              250 is the same as CWD gives, which sounds logical to me.
 *              wu-ftpd uses it as well.
 *
 *              Note that using a CDUP to try to get outside root_dir returns
 *              an error, instead of just staying in the root directory (as
 *              the OS and thus wu-ftpd does).
 */
void cmd_cdup(struct conn * const c)
{
        cmd_cwd_internal(c, "..");
}

/*
 * cmd_cwd_internal():
 *              Does the work for CWD and CDUP (modularized to save some
 *              space and have clearer code). Mostly, it just uses do_chdir(),
 *              and sees where that takes us. It adds a trailing slash if needed.
 */
void cmd_cwd_internal(struct conn * const c, const char * const newd)
{
        if (do_chdir(c, newd) != -1) {
                int i;

                getcwd(c->curr_dir, 254);
                i = strlen(c->curr_dir);
                if (c->curr_dir[i - 1] != '/') {
                        c->curr_dir[i++] = '/';
                        c->curr_dir[i] = '\0';
                }

#if WANT_MESSAGE
                dump_file(c, 250, ".message");
                list_readmes(c);
#endif

                numeric(c, 250, "CWD successful.");
        }
}

/*
 * cmd_rest():  Handles the REST command. All it does is tell the file
 *              sending functions to start at the correct number. We should
 *              perhaps add some better error checking to this?
 */
void cmd_rest(struct conn * const c)
{
        c->rest_pos = abs(atoi(c->recv_buf));
        numeric(c, 350, "Setting resume at %u bytes.", c->rest_pos);
}

/*
 * cmd_retr():  Handles the RETR command. This command doesn't send the
 *              file, but it opens it and tells the socket handling code
 *              to check for activity on the data socket. When the
 *              connection occurs (or succeeds, if we're using PORT mode),
 *              the actual file transfer begins.
 */
void cmd_retr(struct conn * const c)
{
        struct ftran *f = c->transfer;

        if ((f == NULL) || ((f->state != 1) && (f->state != 3))) {
                numeric(c, 425, "No data connection set up; please use PASV or PORT.");
                return;
        }

#if WANT_ASCII
        if ((c->rest_pos > 0) && (c->ascii_mode == 1)) {
                numeric(c, 500, "Cannot resume while in ASCII mode.");
                return;
        }
#endif

        f->local_file = do_openfile(c, c->recv_buf, f->filename, O_RDONLY
#if WANT_NONROOT
                , 4
#endif
        );
        f->dir_listing = 0;

        if (f->local_file == -1) {
                numeric(f->owner, 550, strerror(errno));
                destroy_ftran(f);
        } else if (f->local_file == -2) {
                f->local_file = -1;
                destroy_ftran(f);
        } else {
#if WANT_UPLOAD
                f->upload = 0;
#endif
                prepare_for_transfer(f);
        }
}

#if WANT_UPLOAD
/*
 * cmd_stor():  Handles the STOR command (upload file). Pushes the
 *              work down to do_store(), below.
 */
void cmd_stor(struct conn * const c)
{
        do_store(c, 0);
}

/*
 * cmd_appe():  Handles the APPE command (append to file). Pushes
 *              the work down to do_store(), below.
 */
void cmd_appe(struct conn * const c)
{
        do_store(c, 1);
}

/*
 * do_store():  Initiate an upload. Most of the comments to do_retr()
 *              (above) apply to this one as well.
 */
void do_store(struct conn * const c, const int append)
{
        struct ftran *f = c->transfer;

        if ((f == NULL) || ((f->state != 1) && (f->state != 3))) {
                numeric(c, 425, "No data connection set up; please use PASV or PORT.");
                return;
        }

#if WANT_ASCII
        if ((c->rest_pos > 0) && (c->ascii_mode == 1)) {
                numeric(c, 500, "Cannot resume while in ASCII mode.");
                return;
        }
#endif

        f->local_file = do_openfile(c, c->recv_buf, f->filename, O_WRONLY |
                O_CREAT | ((append || c->rest_pos > 0) ? 0 : O_TRUNC)
#if WANT_NONROOT
                , 2
#endif
        );
        f->dir_listing = 0;

        if (f->local_file == -1) {
                numeric(f->owner, 550, strerror(errno));
        } else if (f->local_file == -2) {
                f->local_file = -1;
        } else {
                f->upload = 1;
                f->append = append;
#if WANT_ASCII
                f->ascii_mode = c->ascii_mode;
#endif
                prepare_for_transfer(f);
        }
}
#endif /* WANT_UPLOAD */

/*
 * cmd_size():  Handle the SIZE command -- returns the size of a
 *              file. Note that this command is not part of RFC959,
 *              and thus there is no clear specification (except
 *              for some ftpext documents, which we try to follow
 *              as closely as we can). BetaFTPD deviates from wu-ftpd
 *              in that it lets you check the `size' of directories
 *              as well (instead of giving 550). This is _not_ the
 *              size of all the files in the directory, rather how
 *              much space the directory inode uses.
 */
void cmd_size(struct conn * const c)
{
#if WANT_ASCII
        if (c->ascii_mode) {
                numeric(c, 550, "SIZE not available in ASCII mode.");
                return;
        }
#endif
        {
                const char * const fname = translate_path(c, c->recv_buf);
                struct stat buf;
        
                TRAP_ERROR(fname == NULL || lstat(fname, &buf) == -1, 550, return);
        
                numeric(c, 213, "%lu", (unsigned long)(buf.st_size));
        }
}

/*
 * cmd_mdtm():  Handle the MDTM command -- returns the modification
 *              date/time of a file. See the comments on cmd_size(),
 *              above.
 */
void cmd_mdtm(struct conn * const c)
{
        const char * const fname = translate_path(c, c->recv_buf);
        struct stat buf;
        struct tm *m;

        TRAP_ERROR(fname == NULL || lstat(fname, &buf) == -1, 550, return);

        m = gmtime(&(buf.st_mtime));    /* at least wu-ftpd does it in GMT */
        numeric(c, 213, "%u%02u%02u%02u%02u%02u", m->tm_year + 1900,
                m->tm_mon + 1, m->tm_mday, m->tm_hour, m->tm_min, m->tm_sec);
}

/*
 * cmd_abor():  Handle the ABOR command (abort a file transfer). This should
 *              be clean enough, but isn't tested extensively.
 */
void cmd_abor(struct conn * const c)
{
        if (c->transfer != NULL) {
                numeric(c, 426, "File transfer aborted.");
                destroy_ftran(c->transfer);
        }
        numeric(c, 226, "ABOR command processed OK.");
}

/*
 * cmd_dele():  Handle the DELE command (delete a file).
 */
void cmd_dele(struct conn * const c)
{
        const char * const fname = translate_path(c, c->recv_buf);
        
        TRAP_ERROR(fname == NULL || unlink(fname) == -1, 550, return);
        numeric(c, 250, "File deleted OK.");
}

/*
 * cmd_rnfr():  Handle the RNFR command (take a filename to rename from).
 */
void cmd_rnfr(struct conn * const c)
{
        const char * const fname = translate_path(c, c->recv_buf);
        char cwd[256];
        struct stat buf;

        c->rename_from[0] = '\0';
        if (fname == NULL) return;
        
        getcwd(cwd, 256);
        snprintf(c->rename_from, 256, "%s/%s", cwd, fname);

        /* Just check that the file exists. */
        TRAP_ERROR(lstat(c->rename_from, &buf) == -1, 550, c->rename_from[0] = '\0'; return);

        numeric(c, 350, "File exists, send RNTO.");
}

/*
 * cmd_rnto():  Handle the RNTO command (do the actual renaming).
 */
void cmd_rnto(struct conn * const c)
{
        const char * const fname = translate_path(c, c->recv_buf);

        if (fname == NULL) return;
        if (c->rename_from[0] == '\0') {
                numeric(c, 503, "Please send RNFR first.");
                return;
        }

        TRAP_ERROR(rename(c->rename_from, fname) == -1, 550, c->rename_from[0] = '\0'; return);
        c->rename_from[0] = '\0';

        numeric(c, 250, "File renamed successfully.");
}

/*
 * cmd_mkd():   Handle the MKD/XMKD command (create a new directory).
 *              RFC959 is not clear on the error codes for this command --
 *              one place, 521 is cited as the correct error, but is
 *              mentioned nowhere else. Different FTP servers differ here
 *              as well. Thus, I've followed what appears to be the intention
 *              (having `analogous' errors with STOR), and use 550 instead.
 *
 *              Making directories is probably the topic covered most
 *              extensively by RFC959 (and in the most confusing way as
 *              well). I try to follow the conventions, but it isn't always
 *              easy :-) (This code isn't quite easy to understand, because
 *              temp2 is used twice, in two different roles.)
 */
void cmd_mkd(struct conn * const c)
{
        const char * const fname = translate_path(c, c->recv_buf);
        char temp[512], temp2[1024], *cdir;
        int i, j;

        TRAP_ERROR(fname == NULL || mkdir(fname, 0755) == -1, 550, return);

        chdir(fname);
        getcwd(temp2, 512);
        cdir = do_pwd(c, temp, temp2);

        if (do_pwd == NULL) return;
        
        /* double the quotes in the output */ 
        for (i = 0, j = 0; i <= strlen(cdir); i++, j++) {
                temp2[j] = cdir[i];
                if (cdir[i] == '"') {
                        temp2[++j] = '"';
                }
        }
        numeric(c, 257, "\"%s\" created.", temp2);
}

/*
 * cmd_rmd():   Handle the RMD/XRMD command. Works just like DELE, only for
 *              directories.
 */
void cmd_rmd(struct conn * const c)
{
        const char * const fname = translate_path(c, c->recv_buf);

        TRAP_ERROR(fname == NULL || rmdir(fname) == -1, 550, return);
        numeric(c, 250, "Directory deleted.");
}

/*
 * cmd_allo():  Handle the ALLO command. The command does not do anything, except
 *              sit around and play compliant. Some Windows FTP servers (Serv-U,
 *              for instance), verifies that there is enough space on the disk,
 *              but since we have no idea on what the filesystem will be stored on,
 *              we just ignore the command.
 *
 *              We could theoretically use this information to give more information
 *              to the full-screen mode, but close to no FTP clients send this
 *              command, and it would touch too much code.
 */
void cmd_allo(struct conn * const c)
{
        numeric(c, 202, "No storage allocation necessary.");
}

/*
 * cmd_stat():  Handle the STAT command. Please see README for more details.
 *              Note that this command is run with euid=root, since it has
 *              to be able to run before USER.
 *
 *              Note that we need to bypass numeric(), to get a multi-line
 *              reply.
 */
#if WANT_STAT
char conn_state[5][27] = {
        "Not logged in",
        "Waiting for e-mail address",
        "Waiting for password",
        "Logged in",
        "Logged in",            /* non-anonymous */
};

char ftran_state[6][42] = {
        "Not initialized",
        "Decided PASV address/port",
        "Waiting on PASV socket",
        "Got PORT address/port",
        "Connecting on PORT address/port",
        "Transferring file (or connecting on PORT)"
};
#endif

void cmd_stat(struct conn * const c)
{ 
#if WANT_STAT
        char buf[1024];
        int i, err;
        struct ftran *f = c->transfer;

        snprintf(buf, 1024, "211- FTP server status:\r\n"
                            "     BetaFTPD version " VERSION " (http://members.xoom.com/sneeze/betaftpd.html)\r\n"
                            "     Connected to %s\r\n"
                            "     Control connection state: %s\r\n"
#if WANT_ASCII
                            "     TYPE: %s; STRUcture: File; transfer MODE: Stream\r\n"
#else
                            "     TYPE: Image; STRUcture: File; transfer MODE: Stream\r\n"
#endif
                            "     Data connection state: %s\r\n"
                            "211 End of status\r\n",
                                inet_ntoa(((struct sockaddr_in *)(&(c->addr)))->sin_addr),
                                conn_state[c->auth],
#if WANT_ASCII
                                (c->ascii_mode == 1) ? "ASCII, FORM: Nonprint" : "Image",
#endif
                                (f) ? ftran_state[f->state] : ftran_state[0]);

        i = strlen(buf);

        err = send(c->sock, buf, i, 0);
        if (err == -1 && errno == EPIPE) {
                this->free_me = 1;
        }
#else
        numeric(c, 502, "STAT command disabled for security reasons.");
#endif
}

#if HAVE_MMAP
/*
 * _mwrite():   This define is for mmap-listing. It works as a write()
 *              (not in parameter, but in function), and is used in
 *              cmd_list() and cmd_nlst() only.
 *
 *              Note that this function returns the new position in the
 *              `file'. The caller is expected to send this information
 *              back in `pos' at the next call to _mwrite().
 */
int _mwrite(const char * const buf, const struct ftran * const f,
            const int pos, const int count, const int size)
{
        if (pos + count >= size) return size;   /* out of space */
        memcpy(f->file_data + pos, buf, count);
        return pos + count;
}
#endif

/*
 * mwrite:      This is a short_hand define, making calls to _mwrite() very
 *              similiar to calls to write(). It works both with and without
 *              mmap().
 */
#if HAVE_MMAP
#define mwrite(buf, count) pos = _mwrite((buf), (f), (pos), (count), (size));
#else
#define mwrite(buf, count) write(f->local_file, buf, count);
#endif

/*
 * long_listing():
 *              Formats output in `ls -l' style. It returns one line for the
 *              file PATHNAME, and returns it in retbuf. Setting do_classify
 *              to nonzero has the same effect as `ls -F'.
 *
 *              This command is so long, because simply there is so much to
 *              be done. GNU ls has some extra functions, but it's close to
 *              3000 lines too...
 */
int long_listing(char * const retbuf, const char * const pathname, const int do_classify)
{
        int i, year;
        char newd[512], temp[1026];
        struct stat buf;
        struct tm *t;
        time_t now;
        char username[17], groupname[17];

        time(&now);
        year = localtime(&now)->tm_year;
        {
#if !WANT_NONROOT
                struct passwd *p;
                struct group *g;
#endif

                if (lstat(pathname, &buf) == -1) return 0;

#if WANT_NONROOT
                strcpy(username, nr_get_uname(buf.st_uid));
                strcpy(groupname, nr_get_gname(buf.st_gid));
#else
                p = getpwuid(buf.st_uid);
                if (p != NULL) {
                        strncpy(username, p->pw_name, 16);
                        username[16] = 0;
                } else {
                        snprintf(username, 16, "%u", buf.st_uid);
                }

                g = getgrgid(buf.st_gid);
                if (g != NULL) {
                        strncpy(groupname, g->gr_name, 16);
                        groupname[16] = 0;
                } else {
                        snprintf(groupname, 16, "%u", buf.st_gid);
                }
#endif
        }

        /*
         * This POSIX approximation is based on GNU ls code (and obfuscated
         * a bit...), to be compatible with `real' ls implementations.
         */
        t = localtime(&(buf.st_mtime));
        strftime(newd, 512, ((now > buf.st_mtime + 6L * 30L * 24L * 60L * 60L) ||
                             (now < buf.st_mtime - 60L * 60L))
                        ? "%b %e  %Y" : "%b %e %H:%M", t);

        {
#if WANT_NONROOT
                char rights[16];

                if (nr_check_permission(0, pathname, 0, (S_ISDIR(buf.st_mode)), rights) == -1) {
                        /* no permission to even see this file */
                        return 0;
                }

                snprintf(temp, 1024, "%c%s %3u %-8s %-8s %8lu %12s %s\r\n",
#else
                snprintf(temp, 1024, "%c%c%c%c%c%c%c%c%c%c %3u %-8s %-8s %8lu %12s %s",
#endif
                        decode_mode(buf.st_mode),
#if WANT_NONROOT
                        rights,
#else
                        (buf.st_mode & S_IRUSR) ? 'r' : '-', 
                        (buf.st_mode & S_IWUSR) ? 'w' : '-',
                        (buf.st_mode & S_IXUSR) ? ((buf.st_mode & S_ISUID) ? 's' : 'x') : '-',
                        (buf.st_mode & S_IRGRP) ? 'r' : '-',
                        (buf.st_mode & S_IWGRP) ? 'w' : '-',
                        (buf.st_mode & S_IXGRP) ? ((buf.st_mode & S_ISGID) ? 's' : 'x') : '-',
                        (buf.st_mode & S_IROTH) ? 'r' : '-',
                        (buf.st_mode & S_IWOTH) ? 'w' : '-',
                        (buf.st_mode & S_IXOTH) ? ((buf.st_mode & S_ISVTX) ? 't' : 'x') : '-',
#endif
                        buf.st_nlink, username, groupname,
                        (unsigned long)(buf.st_size), newd, pathname);
                i = strlen(temp);
        
#if 0
                /*
                 * vim needs this extra character for some reason... It's too 
                 * bad I'll have to do it this way, but syntax colouring
                 * that works properly is almost a `must' for me :-)
                 */
                )
#endif
 
                /* add an extra classification `sign' if we got -F */
                if (do_classify) {
                        int len = strlen(temp);
                        temp[len] = classify(buf.st_mode);
                        temp[len + 1] = '\0';
                }
        }

        strcpy(retbuf, temp);
}

/*
 * cmd_list():  Handles the LIST command (directory listing). Does a
 *              long listing (of type `ls -l'). The listing work is
 *              done by do_listing(), below.
 */
void cmd_list(struct conn * const c)
{
        struct list_options lo;

        lo.recursive = 0;
        lo.long_listing = 1;
        lo.classify = 0;

        do_listing(c, &lo);
}

/*
 * cmd_nlst():  Handles the NLST command (plain directory listing).
 *              Does a plain listing (no dates etc.), unless overridden
 *              by the `-l' or `-L' flag (case insensitivity because most
 *              FTP clients don't have a clue about what they send out). 
 *              The listing work is done by do_listing(), below.
 */     
void cmd_nlst(struct conn * const c)
{
        struct list_options lo;

        lo.recursive = 0;
        lo.long_listing = 0;
        lo.classify = 0;

        do_listing(c, &lo);
}

/*
 * do_listing():
 *              Prepares any listing buffers, temp files, etc., before
 *              pushing the work one step further :-)
 *
 *              If the directory listing cache is enabled, the cache
 *              is checked first, to see if we still have a valid entry.
 */
void do_listing(struct conn * const c, struct list_options * const lo)
{
        int i;
        char *ptr;
#if HAVE_MMAP
        int size;
#endif
        struct ftran * const f = c->transfer;

#if WANT_DCACHE
        char cwd[256];
#endif

#if WANT_NONROOT
#warning No nonroot checking for list_core() yet
#endif

        i = prepare_for_listing(c, &ptr, lo);
        if (i == -1) {
                destroy_ftran(c->transfer);
                return;
        }

#if WANT_DCACHE
        getcwd(cwd, 256);
#endif

#if HAVE_MMAP
        strcpy(f->filename, "(directory listing)");
#endif

#if WANT_DCACHE
        {
                struct dcache *d = find_dcache(cwd, ptr, lo);
                if (d != NULL) {
                        d->use_count++;
                        f->dir_cache = d;
                        f->file_data = d->dir_data;
                        f->size = d->dir_size;
                        f->dir_listing = 1;
                        f->pos = 0;

                        prepare_for_transfer(f);
                        return;
                }
        }
#endif

#if HAVE_MMAP
        {
                int num_files = get_num_files(c, ptr, lo);
                if (num_files == -1) return;

                size = num_files * 160;
                f->file_data = malloc(size + 1);
                TRAP_ERROR(f->file_data == NULL, 550, return);
                list_core(c, ptr, "", lo, size, 0);
        }
#else
        list_core(c, ptr, "", lo);
#endif

#if WANT_DCACHE
        populate_dcache(f, cwd, ptr, lo);
#endif

#if HAVE_MMAP
        f->pos = 0;
#endif
        prepare_for_transfer(f);
}

/*
 * get_num_files():
 *              Get the number of files in PATHNAME (optionally matching
 *              a pattern). Note that c is needed for TRAP_ERROR.
 */
int get_num_files(struct conn * const c, const char * const pathname,
                   struct list_options * const lo)
{
        int num_files;
        glob_t pglob;

        /*
         * glob() fails to set errno correctly, so we simply guess on
         * `permission denied'... The others are far less likely to happen.
         */
        switch (glob(pathname, 0, NULL, &pglob)) {
#ifdef GLOB_NOMATCH
        case GLOB_NOMATCH:
                return 0;
#endif
        case 0:
                num_files = pglob.gl_pathc;
                break;
        default:
                numeric(c, 550, strerror(EACCES));
                return -1;
        }

        if (lo->recursive) {
                int i;
                for (i = 0; i < pglob.gl_pathc; i++) {
                        char *temp = pglob.gl_pathv[i];
                        struct stat buf;

                        lstat(temp, &buf);
                        if (S_ISDIR(buf.st_mode)) {
                                chdir(temp);
                                num_files += get_num_files(c, "*", lo);
                                chdir("..");
                        }
                }
        }

        globfree(&pglob);

        return num_files;
}

/*
 * list_core(): Enumerate all the files in PATHNAME, and formats them
 *              according to list_options (calling format functions if
 *              required).
 *
 *              Note that we don't do any realloc() yet, so if your
 *              _average_ file name length is over a certain size (a little
 *              under 80 for long listings, and a little under 160 for
 *              short listings), the list will be truncated. Fix...
 *
 *              The return value only makes sense if mmap()'ing, since it
 *              returns the number of bytes written into the buffer.
 *
 *              This function is rather long.
 */
int list_core(struct conn * const c, const char * const pathname,
              char * const disp_pathname, struct list_options * const lo
#if HAVE_MMAP
                , const int size, int pos
#endif
                )
{
        int i;
        glob_t pglob;
        struct ftran * const f = c->transfer;

        /*
         * glob() fails to set errno correctly, so we simply guess on
         * `permission denied'... The others are far less likely to happen.
         */
        switch (glob(pathname, GLOB_MARK, NULL, &pglob)) {
        case 0:
#ifdef GLOB_NOMATCH
        case GLOB_NOMATCH:
#endif
                break;          /* note: break, not return */
        default:
                numeric(c, 550, strerror(EACCES));
#if HAVE_MMAP
                return pos;
#else
                return 0;
#endif
        }

        if (lo->recursive) {
                if (disp_pathname[0] == '\0') {
                        mwrite(".:\r\n", 4);
                } else {
                        char temp[1024];
                        int i;

                        snprintf(temp, 1024, "%s:\r\n", disp_pathname);
                        i = strlen(temp);
                        mwrite(temp, i);
                }
        }
        if (lo->long_listing) {
                /* FIX: we may get too high total number if we are running nonroot! */
                struct stat buf;
                long unsigned int total = 0;
                char temp[1024];

                for (i = 0; i < pglob.gl_pathc; i++) {
                        if (lstat(pglob.gl_pathv[i], &buf) != -1) {
                                total += buf.st_blocks;
                        }
                }
                snprintf(temp, 1024, "total %lu\r\n", total >> 1);
                i = strlen(temp);
                mwrite(temp, i);
        }

        for (i = 0; i < pglob.gl_pathc; i++) {
                char * const temp = pglob.gl_pathv[i];
                char buf[2048];

                /* strip `/' away from the pathname -- add it later if -F */
                {
                        int len = strlen(temp);
                        if (temp[len - 1] == '/') {
                                temp[len - 1] = '\0';
                        }
                }

                if (lo->long_listing) {
                        if (long_listing(buf, temp, lo->classify) == 0) continue;
                } else {
                        strcpy(buf, temp);
                        if (lo->classify) {
                                struct stat statbuf;

                                if (lstat(buf, &statbuf) != -1) {
                                        const int len = strlen(buf);

                                        buf[len] = classify(statbuf.st_mode);
                                        buf[len + 1] = 0;
                                }
                        }
                }

                mwrite(buf, strlen(buf));
                mwrite("\r\n", 2);
        }

        /*
         * If recursion is on, dive into any subdirectories now -- note
         * that each entry is stat()'ed twice, hopefully the OS will manage,
         * and we've got our own dcache anyways -- this could be fixed at
         * the expense of some memory, consider for later inclusion.
         */
        if (lo->recursive) {
                for (i = 0; i < pglob.gl_pathc; i++) {
                        struct stat buf;
                        const char * const temp = pglob.gl_pathv[i];

                        /* don't dive into `.' or `..' */
                        if (lstat(temp, &buf) != -1 && S_ISDIR(buf.st_mode) &&
                                (temp[0] != '.' || (temp[1] != '.' && temp[1] != '\0'))) {
                                char tmp2[1024];

                                mwrite("\r\n", 2);

                                /* attach the pathname to the end of the displayed path */
                                if (disp_pathname[0] == '\0') {
                                        snprintf(tmp2, 1024, "%s", temp);
                                } else {
                                        snprintf(tmp2, 1024, "%s/%s", disp_pathname, temp);
                                }

                                chdir(temp);
                                pos = list_core(c, "*", tmp2, lo, 
#if HAVE_MMAP
                                        size, pos);
#endif
                                chdir("..");
                        }
                }
        }

#if HAVE_MMAP
        f->size = pos;
#else
        lseek(f->local_file, 0, SEEK_SET);
#endif

        globfree(&pglob);
#if HAVE_MMAP
        return pos;
#else
        return 0;
#endif
}

/*
 * cmd_noop():  Handles the NOOP command. Does nothing, doesn't even
 *              reset the timeout.
 */
void cmd_noop(struct conn * const c)
{
        numeric(c, 200, "NOOP command successful.");
}

/*
 * cmd_syst():  Handles the SYST command. Returns the system identification.
 */
void cmd_syst(struct conn * const c)
{
        numeric(c, 215, "UNIX Type: L%u", NBBY);
}

/*
 * cmd_type():  Handles the TYPE command.
 */
void cmd_type(struct conn * const c)
{
#if WANT_ASCII
        c->recv_buf[0] &= (255-32);     /* convert to upper case */
        if (c->recv_buf[0] == 'A') {
                c->ascii_mode = 1;
                numeric(c, 200, "Type is ASCII.");
        } else if (c->recv_buf[0] == 'I') {
                c->ascii_mode = 0;
                numeric(c, 200, "Type is IMAGE.");
        } else {
                numeric(c, 504, "Unknown type.");
        }
#else
        numeric(c, 200, "TYPE ignored (always I)");
#endif
}

/*
 * cmd_mode():  Handles the MODE command. Only stream mode is supported.
 */
void cmd_mode(struct conn * const c)
{
        c->recv_buf[0] &= (255-32);     /* convert to upper case */
        if (c->recv_buf[0] == 'S') {
                numeric(c, 200, "Mode is STREAM.");
        } else {
                numeric(c, 504, "Unknown mode.");
        }
}

/*
 * cmd_stru():  Handles the STRU command. Only file mode is supported.
 */
void cmd_stru(struct conn * const c)
{
        c->recv_buf[0] &= (255-32);     /* convert to upper case */
        if (c->recv_buf[0] == 'F') {
                numeric(c, 200, "Structure is FILE.");
        } else {
                numeric(c, 504, "Unknown structure.");
        }
}

/*
 * cmd_help():  Handle the HELP command. I'm sorry, but I'm unwilling
 *              to use a lot of space to explain the RFCs in such a message,
 *              and BetaFTPD doesn't have any special things that should
 *              be noted anywhere. Thus, this message is close to empty. I
 *              feel that a 5xx entry would have been better, but that is
 *              disallowed.
 *
 *              As with ACCT, this command is supposed to be executed from
 *              everywhere, so we have to run without setuid. I don't like
 *              it, but at the same time I have to idea what could go
 *              wrong...
 *
 *              Perhaps I should make this message sound a little less
 *              like an error, since the error code is intended for helpful
 *              messages? :-)
 */
void cmd_help(struct conn * const c)
{
        numeric(c, 414, "Sorry, no detailed help; use standard FTP commands.");
}

/*
 * cmd_quit():  Handles the QUIT command, which shuts down the control
 *              and data sockets.
 */
void cmd_quit(struct conn * const c)
{
        numeric(c, 221, "Have a nice day!");
        c->free_me = 1;
}

/*
 * cmd_rein():  Handle the REIN command, which does close to a full reset
 *              of the connection. Much of the code here is intentionally
 *              copied directly from alloc_new_conn() -- perhaps we should
 *              modularize this?
 */
void cmd_rein(struct conn * const c)
{
        destroy_ftran(c->transfer);
        c->buf_len = c->auth = c->rest_pos = 0;

        /* equals: strcpy(c->curr_dir, "/") ; strcpy(c->last_cmd, ""); */
        c->curr_dir[0] = '/';
#if WANT_FULLSCREEN
        c->curr_dir[1] = c->last_cmd[0] = '\0';
#else
        c->curr_dir[1] = '\0';
#endif

        time(&(c->last_transfer));
        numeric(c, 220, "BetaFTPD " VERSION " ready.");
}

#if DOING_PROFILING
/*
 * cmd_exit():  Handles the EXIT command, my own `extension' to the
 *              FTP protocol... IMPORTANT: Only to be used for profiling
 *              purposes!! (It's needed to get some profiling data out
 *              of the server after compiling it with -pg, since such data
 *              is only written on a clear exit()). Any user (even those
 *              not logged in) can issue an EXIT, and make the server shut
 *              down without clearing any sockets etc. In other words:
 *              Don't use it on a production site.
 */
void cmd_exit(struct conn * const c)
{
        while (first_conn->next_conn)
                destroy_conn(first_conn->next_conn);
        exit(0);
}
#endif

/*
 * parse_command():
 *              Gets a command from c->recv_buf, determines which command
 *              it is, sets proper effective user-ID and calls the command
 *              handler. Finally, it cleans up.
 *
 *              To me, this command seems optimizable, but I'm not really
 *              sure where :-)
 */
void parse_command(struct conn *c)
{
        int cmlen;
        const struct handler *h = handler_table;        /* first entry */

        if (c == NULL) return;

        /* strip any leading non-ASCII characters (including CR/LFs) */
        while (c->buf_len > 0 && (c->recv_buf[0] < 'a' || c->recv_buf[0] > 'z')
                              && (c->recv_buf[0] < 'A' || c->recv_buf[0] > 'Z')) {
                remove_bytes(c, 1);             /* not good */
        }

        /* scan, searching for CR or LF */      
        cmlen = strcspn(c->recv_buf, "\r\n");
        if (cmlen >= c->buf_len) return;

#if WANT_FULLSCREEN
        strncpy(c->last_cmd, c->recv_buf, cmlen);
        c->last_cmd[cmlen] = 0;
#endif

        do {
                if ((cmlen >= (strlen(h->cmd_name) + h->add_cmlen)) &&
                    (strncasecmp(c->recv_buf, h->cmd_name, strlen(h->cmd_name)) == 0)) {
                        if (c->auth < h->min_auth) {
                                numeric(c, 503, "Please login with USER and PASS.");
                                while (c->recv_buf[0] != '\n') remove_bytes(c, 1);
                        } else {
                                char schar;

#if !WANT_NONROOT
                                if (h->do_setuid) {
                                        setegid(c->gid);
                                        seteuid(c->uid);
                                } else {
                                        seteuid(getuid());
                                        setegid(getgid());
                                }
#endif

                                remove_bytes(c, strlen(h->cmd_name));
                                cmlen -= strlen(h->cmd_name);
                                while (c->recv_buf[0] == ' ') {
                                        remove_bytes(c, 1);
                                        cmlen--;
                                }

                                schar = c->recv_buf[cmlen];
                                c->recv_buf[cmlen] = 0;
                                
                                message_buf[0] = '\0';
                                h->callback(c);
                                if (message_buf[0] != '\0') {
                                        /* send any feedback we might have */
                                        int err = send(c->sock, message_buf, strlen(message_buf), 0);
                                        if (err == -1 && errno == EPIPE) {
                                                c->free_me = 1;
                                        }
                                }       
                                
                                if (c->free_me) {
                                        destroy_conn(c);
                                } else {
                                        c->recv_buf[cmlen] = schar;
#if !WANT_NONROOT
                                        if (h->do_setuid) {
                                                seteuid(getuid());
                                                setegid(getgid());
                                        }
#endif
                                        remove_bytes(c, cmlen);
                                }
                        }
                        return;
                }
        } while ((++h)->callback != NULL);

        numeric(c, 500, "Sorry, no such command.");
        remove_bytes(c, cmlen); 
}

/*
 * prepare_for_transfer():
 *              Prepares an ftran object for a file transfer, setting
 *              file size, opening sockets etc.
 *
 *              nonroot notice: prepare_for_transfer() assumes all access
 *              checks are already done.
 */
void prepare_for_transfer(struct ftran *f)
{
#if WANT_NONROOT
#warning No nonroot checking for prepare_for_transfer() yet
#endif

#if HAVE_MMAP
        /* mmap doesn't make temp files for dir listings */
        if (!f->dir_listing) {
#endif

                f->size = lseek(f->local_file, 0, SEEK_END);
                errno = 0;
#if WANT_UPLOAD
                if (f->upload == 0 || f->append == 0 || f->owner->rest_pos != 0)
#endif 
                        lseek(f->local_file, f->owner->rest_pos, SEEK_SET);
#if HAVE_MMAP
        }
#endif
        
        if (f->state == 1) {            /* PASV connection */
                f->state = 2;           /* waiting */
        } else if (f->state == 3) {     /* PORT connection */
                f->state = 4;
                connect(f->sock, (struct sockaddr *)&f->sin, sizeof(f->sin));
                add_fd(f->sock, POLLOUT);
        }
        time(&(f->tran_start));
}

/*
 * decode_mode():
 *              Takes a mode_t argument (from a `struct stat'), and
 *              returns the proper dirlist letter for that type.
 *
 *              Note: S_IFLNK seems to be broken, or perhaps I just have
 *              missed something (S_IFLNK is always set for all *files* on
 *              my glibc 2.0.111 system).
 *
 *              The most common cases are put first, for speed :-)
 */
char decode_mode(mode_t mode) {
        if (S_ISREG(mode))  return '-';
        if (S_ISDIR(mode))  return 'd';
        if (S_ISLNK(mode))  return 'l';
        if (S_ISBLK(mode))  return 'b';
        if (S_ISCHR(mode))  return 'c';
        if (S_ISSOCK(mode)) return 's';
        if (S_ISFIFO(mode))  return 'f';

        return '-';
}

/*
 * translate_path():
 *              Take an FTP path, do all neccessary root_dir checks,
 *              change to the correct directory and return the proper
 *              file name to open/stat/whatever. The path returned is
 *              relative to the current directory (NOT absolute). chdir()
 *              in any way will `destroy' this argument.
 *
 *              Note that `path' will be _changed_, and used as a return pointer
 *              base. Do not attempt to free the result from this function --
 *              if you need to, free path instead.
 */
char *translate_path(struct conn * const c, char * const path)
{
        char *ptr = NULL;

        /* chdir to the right dir, then chop it off */
        chdir(c->curr_dir);

        ptr = strrchr(path, '/');
        if (ptr != NULL) {
                char save_char = ptr[0];
                ptr[0] = 0;

                if (do_chdir(c, path) == -1) {
                        return NULL;
                }
                ptr[0] = save_char;
                ptr++;
        } else {
                ptr = path;
        }
        return ptr;
}

/*
 * do_openfile():
 *              Opens the file PATH with access parameters FLAGS, translating
 *              paths and checking permissions as neccessary. Generally, this
 *              should be used whenever you need an open().
 *
 *              The parameters might be a bit confusing. To clarify them a bit:
 *              c:              IN/OUT (will be changed)
 *              path:           IN (but _will_ be changed)
 *              filename:       OUT
 *              flags:          IN
 *              check_perm:     IN
 */
int do_openfile(struct conn * const c, char * const path,
                char * const filename, const int flags
#if WANT_NONROOT
                , const int check_permission
#endif
)
{
        char *ptr;
        struct stat buf;

#if WANT_NONROOT
        if (nr_check_permission(c->uid, path, check_permission, 0, NULL) == -1) {
                return -1;
        }
#endif

        ptr = translate_path(c, c->recv_buf);
        if (ptr == NULL) return -1;

#if WANT_UPLOAD
        if ((flags & O_CREAT) == 0) {
#endif
                TRAP_ERROR(stat(ptr, &buf) == -1, 550, return -2);
                if (!S_ISREG(buf.st_mode)) {
                        numeric(c, 550, "Not a plain file.", ptr);
                        return -2;
                }
#if WANT_UPLOAD
        }
#endif

        if (filename != NULL) { /* filename should always be != NULL */
                strcpy(filename, ptr);
        }
        return open(ptr, flags, 0666);
}

/*
 * prepare_for_listing():
 *              Parse list options, put them back into the list_options
 *              structure lo, and make temporary room for the list.
 */
int prepare_for_listing(struct conn * const c, char ** const ptr,
                        struct list_options * const lo)
{
#if !HAVE_MMAP
        char *tfname;
#endif
        struct ftran *f = c->transfer;
        char *tmp;
        char *optr = NULL, *fptr = NULL; 
#if WANT_NONROOT
        char chd[512];
#endif

#if WANT_NONROOT
#warning No nonroot checking for prepare_for_listing() yet
#endif

        if ((f == NULL) || ((f->state != 1) && (f->state != 3))) {
                numeric(c, 425, "No data connection set up; please use PASV or PORT.");
                return -1;
        }

        /*
         * A little parameter scanning is required here. There can only
         * be two parts: the directory name, and any options. We'll find
         * any options first.
         */
        if (c->recv_buf[0] == '-') {
                optr = c->recv_buf;
        } else {
                optr = strstr(c->recv_buf, " -");
        }

        /* Then see if there are any options to parse. */
        if (optr != NULL) {
                while (*++optr) {
                        switch (*optr & (255-32)) {     /* uppercase */
                        case 'R':       /* actually case sensitive... */
                                lo->recursive = 1;
                                break;
                        case 'L':
                                lo->long_listing = 1;
                                break;
                        case 'F':
                                lo->classify = 1;
                                break;
                        case '\0':
                                fptr = optr + 1;
                                *(optr--) = 0;
                                break;
                        default:
                                break;
                        }
                }
        } else {
                fptr = c->recv_buf;
        }

        /* then we chdir to the dir in fptr (if any) */
        tmp = fptr ? strrchr(fptr, '/') : NULL;
        if (tmp != NULL) {
                tmp[0] = 0;
                if (do_chdir(c, fptr) == -1) return -1;
                fptr = tmp + 1;
        } else {
                /* current directory */
                TRAP_ERROR(chdir(c->curr_dir) == -1, 550, return -1);
        }

        /* if no argument, choose all files */
        if (fptr == NULL || fptr[0] == 0) {
                fptr = "*";
        } else {
                /* we need to check if the last part is a directory (no -d switch) */
                struct stat buf;
                if (stat(fptr, &buf) == 0 && S_ISDIR(buf.st_mode)) {
                        TRAP_ERROR(chdir(fptr) == -1, 550, return -1);
                        fptr = "*";
                }
        }
        *ptr = fptr;

#if WANT_NONROOT
        getcwd(chd, 512);
        if (nr_check_permission(c->uid, chd, 4, 1, NULL) == -1) {
                numeric(c, 550, "Permission denied");
                return -1;
        }
#endif

#if !HAVE_MMAP
        tfname = tempnam(NULL, "ftp");

#if WANT_NONROOT
        if (tfname == NULL) tfname = tempnam("/", "ftp");
#endif

        TRAP_ERROR(tfname == NULL, 550, return -1);
        strcpy(f->filename, tfname);
        free(tfname);

        f->local_file = open(f->filename, O_RDWR | O_CREAT | O_TRUNC, 0666);
        TRAP_ERROR(f->local_file == -1, 550, return -1);
#endif
        f->dir_listing = 1;
#if WANT_UPLOAD
        f->upload = 0;
#endif

        return 0;
}

/*
 * classify():  Takes a mode_t argument (from `struct stat'), and returns
 *              the parameter to be used in an `ls -F'-style listing.
 */
char classify(const mode_t mode)
{
        if (S_ISREG(mode)) {
                if (mode & (S_IXUSR | S_IXGRP | S_IXOTH)) {
                        return '*';
                } else {
                        return '\0';
                }
        }
        if (S_ISDIR(mode)) return '/';
        if (S_ISLNK(mode)) return '@';
        if (S_ISSOCK(mode)) return '=';
        if (S_ISFIFO(mode)) return '|';
        return '\0'; 
}