tftpd.c

linux下从网卡远程启动

/*
 * Copyright (c) 1983 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) 1983 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)tftpd.c	5.8 (Berkeley) 6/18/88";
#endif /* not lint */

/*
 * Trivial file transfer protocol server.
 *
 * This version includes many modifications by Jim Guyton <guyton@rand-unix>
 *
 * Further modifications by Markus Gutschke <[e-mail]>
 *  - RFC1782 option parsing
 *  - RFC1783 extended blocksize
 *  - "-c" option for changing the root directory
 *  - "-d" option for debugging output
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sys/stat.h>

#include <netinet/in.h>

#include <arpa/tftp.h>

#include <alloca.h>
#include <string.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <netdb.h>
#include <setjmp.h>
#include <syslog.h>

#define	TIMEOUT		5

#ifndef	OACK
#define	OACK	06
#endif

#ifndef EOPTNEG
#define	EOPTNEG	8
#endif

extern	int errno;
struct	sockaddr_in sin = { AF_INET };
int	peer;
int	rexmtval = TIMEOUT;
int	maxtimeout = 5*TIMEOUT;

#define	PKTSIZE	(1432+4) /* SEGSIZE+4 */
int	segsize = SEGSIZE;
char	buf[PKTSIZE];
char	ackbuf[PKTSIZE];
struct	sockaddr_in from;
int	fromlen;

char	*rootdir = NULL;
int	debug = 0;

struct filters {
	struct filters *next;
	char           *fname;
} *filters = NULL;
int     isfilter = 0;

main(argc, argv)
	char *argv[];
{
	register struct tftphdr *tp;
	register int n;
	int on = 1;
	extern int optind;
	extern char *optarg;

	openlog(argv[0], LOG_PID, LOG_DAEMON);

	while ((n = getopt(argc, argv, "c:dr:")) >= 0) {
		switch (n) {
		case 'c':
			if (rootdir)
				goto usage;
			rootdir = optarg;
			break;
		case 'd':
			debug++;
			break;
		case 'r': {
			struct filters *fp = (void *)
				             malloc(sizeof(struct filters) +
						    strlen(optarg) + 1);
			fp->next  = filters;
			fp->fname = (char *)(fp + 1);
			strcpy(fp->fname, optarg);
			filters   = fp;
			break; }
		default:
		usage:
			syslog(LOG_ERR, "Usage: %s [-c chroot] "
			       "[-r readfilter] [-d]\n",
			       argv[0]);
			exit(1);
		}
	}
	if (argc-optind != 0)
		goto usage;

	ioctl(0, FIONBIO, &on);
/*	if (ioctl(0, FIONBIO, &on) < 0) {
		syslog(LOG_ERR, "ioctl(FIONBIO): %m\n");
		exit(1);
	}
*/
	fromlen = sizeof (from);
	n = recvfrom(0, buf, segsize+4, 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, segsize+4, 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);
	}
	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);
}

int	validate_access();
int	sendfile(), recvfile();

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

int	set_blksize();

struct options {
	char	*o_opt;
	int	(*o_fnc)();
} options[] = {
	{ "blksize",	set_blksize },
	{ 0 }
};

/*
 * Set a non-standard block size (c.f. RFC1783)
 */

set_blksize(val, ret)
	char *val;
	char **ret;
{
	static char b_ret[5];
	int sz = atoi(val);

	if (sz < 8) {
		if (debug)
			syslog(LOG_ERR, "Requested packetsize %d < 8\n", sz);
		return(0);
	} else if (sz > PKTSIZE-4) {
		if (debug)
			syslog(LOG_INFO, "Requested packetsize %d > %d\n",
			       sz, PKTSIZE-4);
		sz = PKTSIZE-4;
	} else if (debug)
		syslog(LOG_INFO, "Adjusted packetsize to %d octets\n", sz);
	
	segsize = sz;
	sprintf(*ret = b_ret, "%d", sz);
	return(1);
}

/*
 * Parse RFC1782 style options
 */

do_opt(opt, val, ap)
	char *opt;
	char *val;
	char **ap;
{
	struct options *po;
	char *ret;

	for (po = options; po->o_opt; po++)
		if (strcasecmp(po->o_opt, opt) == 0) {
			if (po->o_fnc(val, &ret)) {
				if (*ap + strlen(opt) + strlen(ret) + 2 >=
				    ackbuf + sizeof(ackbuf)) {
					if (debug)
						syslog(LOG_ERR,
						       "Ackbuf overflow\n");
					nak(ENOSPACE);
					exit(1);
				}
				*ap = strrchr(strcpy(strrchr(strcpy(*ap, opt),
							     '\000')+1, val),
					      '\000')+1;
			} else {
				nak(EOPTNEG);
				exit(1);
			}
			break;
		}
	if (debug && !po->o_opt)
		syslog(LOG_WARNING, "Unhandled option: %d = %d\n", opt, val);
	return;
}

/*
 * Handle initial connection protocol.
 */
tftp(tp, size)
	struct tftphdr *tp;
	int size;
{
	register char *cp;
	int argn = 0, ecode;
	register struct formats *pf;
	char *filename, *mode;
	char *val, *opt;
	char *ap = ackbuf+2;
	int  isopts;

	((struct tftphdr *)ackbuf)->th_opcode = ntohs(OACK);
	filename = cp = tp->th_stuff;
again:
	while (cp < buf + size) {
		if (*cp == '\0')
			break;
		cp++;
	}
	if (*cp != '\0') {
		if (debug)
			syslog(LOG_WARNING, "Received illegal request\n");
		nak(EBADOP);
		exit(1);
	}
	if (!argn++) {
		mode = ++cp;
		goto again;
	} else {
		if (debug && argn == 3)
			syslog(LOG_INFO, "Found RFC1782 style options\n");
		*(argn & 1 ? &val : &opt) = ++cp;
		if (argn & 1)
			do_opt(opt, val, &ap);
		if (cp < buf + size && *cp != '\000')
			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) {
		if (debug)
			syslog(LOG_WARNING, "Unknown data format: %s\n", mode);
		nak(EBADOP);
		exit(1);
	}

	if (rootdir) {
		cp = alloca(strlen(rootdir) + strlen(filename) + 1);
		if (cp == NULL) {
			nak(100+ENOMEM);
			exit(1);