tftpd.c

压缩包中包含LINUX下多个命令的源码

/*
 * Copyright (c) 1983, 1993
 *	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.
 * 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.
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1983, 1993\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)tftpd.c	8.1 (Berkeley) 6/4/93";
#endif /* not lint */

/*
 * Trivial file transfer protocol server.
 *
 * This version includes many modifications by Jim Guyton
 * <guyton@rand-unix>.
 */

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

#include <sys/param.h>
#include <sys/ioctl.h>
#ifdef HAVE_SYS_FILIO_H
#include <sys/filio.h>
#endif
#include <sys/stat.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <arpa/tftp.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <netdb.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "tftpsubs.h"

#if !HAVE_DECL_STRERROR
extern const char *strerror __P ((int));
#endif

#define	TIMEOUT		5

#ifndef LOG_FTP
#define LOG_FTP LOG_DAEMON	/* Use generic facility.  */
#endif

int	peer;
int	rexmtval = TIMEOUT;
int	maxtimeout = 5*TIMEOUT;

#define	PKTSIZE	SEGSIZE+4
char	buf[PKTSIZE];
char	ackbuf[PKTSIZE];
struct	sockaddr_in from;
int	fromlen;

void	tftp __P((struct tftphdr *, int));

/*
 * Null-terminated directory prefix list for absolute pathname requests and
 * search list for relative pathname requests.
 *
 * MAXDIRS should be at least as large as the number of arguments that
 * inetd allows (currently 20).
 */
#define MAXDIRS	20
static struct dirlist {
	char	*name;
	int	len;
} dirs[MAXDIRS+1];
static int	suppress_naks;
static int	logging;

static const char *errtomsg __P((int));
static void  nak __P((int));
static const char *verifyhost __P((struct sockaddr_in *));

int
main(int argc, char *argv[])
{
	register struct tftphdr *tp;
	register int n;
	int ch, on;
	struct sockaddr_in sin;

	openlog("tftpd", LOG_PID, LOG_FTP);
	while ((ch = getopt(argc, argv, "ln")) != EOF) {
		switch (ch) {
		case 'l':
			logging = 1;
			break;
		case 'n':
			suppress_naks = 1;
			break;
		default:
			syslog(LOG_WARNING, "ignoring unknown option -%c", ch);
		}
	}
	if (optind < argc) {
		struct dirlist *dirp;

		/* Get list of directory prefixes. Skip relative pathnames. */
		for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
		     optind++) {
			if (argv[optind][0] == '/') {
				dirp->name = argv[optind];
				dirp->len  = strlen(dirp->name);
				dirp++;
			}
		}
	}

	on = 1;
	if (ioctl(0, FIONBIO, &on) < 0) {
		syslog(LOG_ERR, "ioctl(FIONBIO): %m\n");
		exit(1);
	}
	fromlen = sizeof (from);
	n = recvfrom(0, buf, sizeof (buf), 0,
	    (struct sockaddr *)&from, &fromlen);
	if (n < 0) {
		syslog(LOG_ERR, "recvfrom: %m\n");
		exit(1);
	}
	/*
	 * Now that we have read the message out of the UDP
	 * socket, we fork and exit.  Thus, inetd will go back
	 * to listening to the tftp port, and the next request
	 * to come in will start up a new instance of tftpd.
	 *
	 * We do this so that inetd can run tftpd in "wait" mode.
	 * The problem with tftpd running in "nowait" mode is that
	 * inetd may get one or more successful "selects" on the
	 * tftp port before we do our receive, so more than one
	 * instance of tftpd may be started up.  Worse, if tftpd
	 * break before doing the above "recvfrom", inetd would
	 * spawn endless instances, clogging the system.
	 */
	{
		int pid;
		int i, j;

		for (i = 1; i < 20; i++) {
		    pid = fork();
		    if (pid < 0) {
				sleep(i);
				/*
				 * flush out to most recently sent request.
				 *
				 * This may drop some request, but those
				 * will be resent by the clients when
				 * they timeout.  The positive effect of
				 * this flush is to (try to) prevent more
				 * than one tftpd being started up to service
				 * a single request from a single client.
				 */
				j = sizeof from;
				i = recvfrom(0, buf, sizeof (buf), 0,
				    (struct sockaddr *)&from, &j);
				if (i > 0) {
					n = i;
					fromlen = j;
				}
		    } else {
				break;
		    }
		}
		if (pid < 0) {
			syslog(LOG_ERR, "fork: %m\n");
			exit(1);
		} else if (pid != 0) {
			exit(0);
		}
	}
	from.sin_family = AF_INET;
	alarm(0);
	close(0);
	close(1);
	peer = socket(AF_INET, SOCK_DGRAM, 0);
	if (peer < 0) {
		syslog(LOG_ERR, "socket: %m\n");
		exit(1);
	}
	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	if (bind(peer, (struct sockaddr *)&sin, sizeof (sin)) < 0) {
		syslog(LOG_ERR, "bind: %m\n");
		exit(1);
	}
	if (connect(peer, (struct sockaddr *)&from, sizeof(from)) < 0) {
		syslog(LOG_ERR, "connect: %m\n");
		exit(1);
	}
	tp = (struct tftphdr *)buf;
	tp->th_opcode = ntohs(tp->th_opcode);
	if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
		tftp(tp, n);
	exit(1);
}

struct formats;
int	validate_access __P((char **, int));
void	send_file __P((struct formats *));
void	recvfile __P((struct formats *));

struct formats {
	char	*f_mode;
	int	(*f_validate) __P((char **, int));
	void	(*f_send) __P((struct formats *));
	void	(*f_recv) __P((struct formats *));
	int	f_convert;
} formats[] = {
	{ "netascii",	validate_access,	send_file,	recvfile, 1 },
	{ "octet",	validate_access,	send_file,	recvfile, 0 },
#ifdef notdef
	{ "mail",	validate_user,		sendmail,	recvmail, 1 },
#endif
	{ 0 }
};

/*
 * Handle initial connection protocol.
 */
void
tftp(struct tftphdr *tp, int size)
{
	register char *cp;
	int first = 1, ecode;
	register struct formats *pf;
	char *filename, *mode;

	filename = cp = tp->th_stuff;
again:
	while (cp < buf + size) {
		if (*cp == '\0')
			break;
		cp++;
	}
	if (*cp != '\0') {
		nak(EBADOP);
		exit(1);
	}
	if (first) {
		mode = ++cp;
		first = 0;
		goto again;
	}
	for (cp = mode; *cp; cp++)
		if (isupper(*cp))
			*cp = tolower(*cp);
	for (pf = formats; pf->f_mode; pf++)
		if (strcmp(pf->f_mode, mode) == 0)
			break;
	if (pf->f_mode == 0) {
		nak(EBADOP);
		exit(1);
	}
	ecode = (*pf->f_validate)(&filename, tp->th_opcode);
	if (logging) {
		syslog(LOG_INFO, "%s: %s request for %s: %s",
			verifyhost(&from),
			tp->th_opcode == WRQ ? "write" : "read",
			filename, errtomsg(ecode));
	}
	if (ecode) {
		/*
		 * Avoid storms of naks to a RRQ broadcast for a relative
		 * bootfile pathname from a diskless Sun.
		 */
		if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
			exit(0);
		nak(ecode);
		exit(1);
	}
	if (tp->th_opcode == WRQ)
		(*pf->f_recv)(pf);
	else
		(*pf->f_send)(pf);
	exit(0);
}


FILE *file;

/*
 * Validate file access.  Since we
 * have no uid or gid, for now require
 * file to exist and be publicly