507 lines
12 KiB
C
507 lines
12 KiB
C
/*
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* Copyright (c) 1983 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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char copyright[] =
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"@(#) Copyright (c) 1983 Regents of the University of California.\n\
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All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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/*static char sccsid[] = "from: @(#)tftpd.c 5.13 (Berkeley) 2/26/91";*/
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static char rcsid[] = "$Id: tftpd.c,v 1.3 1993/08/01 18:28:53 mycroft Exp $";
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#endif /* not lint */
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/*
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* Trivial file transfer protocol server.
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*
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* This version includes many modifications by Jim Guyton <guyton@rand-unix>
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*/
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include <signal.h>
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#include <fcntl.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/tftp.h>
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#include <netdb.h>
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#include <setjmp.h>
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#include <syslog.h>
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#include <stdio.h>
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#include <errno.h>
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#include <ctype.h>
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#include <string.h>
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#include <stdlib.h>
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#define TIMEOUT 5
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extern int errno;
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struct sockaddr_in s_in = { AF_INET };
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int peer;
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int rexmtval = TIMEOUT;
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int maxtimeout = 5*TIMEOUT;
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#define PKTSIZE SEGSIZE+4
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char buf[PKTSIZE];
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char ackbuf[PKTSIZE];
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struct sockaddr_in from;
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int fromlen;
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#define MAXARG 4
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char *dirs[MAXARG+1];
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main(ac, av)
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char **av;
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{
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register struct tftphdr *tp;
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register int n = 0;
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int on = 1;
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ac--; av++;
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while (ac-- > 0 && n < MAXARG)
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dirs[n++] = *av++;
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openlog("tftpd", LOG_PID, LOG_DAEMON);
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if (ioctl(0, FIONBIO, &on) < 0) {
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syslog(LOG_ERR, "ioctl(FIONBIO): %m\n");
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exit(1);
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}
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fromlen = sizeof (from);
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n = recvfrom(0, buf, sizeof (buf), 0,
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(struct sockaddr *)&from, &fromlen);
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if (n < 0) {
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syslog(LOG_ERR, "recvfrom: %m\n");
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exit(1);
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}
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/*
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* Now that we have read the message out of the UDP
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* socket, we fork and exit. Thus, inetd will go back
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* to listening to the tftp port, and the next request
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* to come in will start up a new instance of tftpd.
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*
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* We do this so that inetd can run tftpd in "wait" mode.
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* The problem with tftpd running in "nowait" mode is that
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* inetd may get one or more successful "selects" on the
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* tftp port before we do our receive, so more than one
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* instance of tftpd may be started up. Worse, if tftpd
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* break before doing the above "recvfrom", inetd would
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* spawn endless instances, clogging the system.
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*/
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{
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int pid;
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int i, j;
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for (i = 1; i < 20; i++) {
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pid = fork();
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if (pid < 0) {
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sleep(i);
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/*
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* flush out to most recently sent request.
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*
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* This may drop some request, but those
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* will be resent by the clients when
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* they timeout. The positive effect of
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* this flush is to (try to) prevent more
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* than one tftpd being started up to service
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* a single request from a single client.
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*/
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j = sizeof from;
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i = recvfrom(0, buf, sizeof (buf), 0,
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(struct sockaddr *)&from, &j);
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if (i > 0) {
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n = i;
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fromlen = j;
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}
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} else {
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break;
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}
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}
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if (pid < 0) {
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syslog(LOG_ERR, "fork: %m\n");
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exit(1);
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} else if (pid != 0) {
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exit(0);
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}
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}
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from.sin_family = AF_INET;
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alarm(0);
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close(0);
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close(1);
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peer = socket(AF_INET, SOCK_DGRAM, 0);
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if (peer < 0) {
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syslog(LOG_ERR, "socket: %m\n");
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exit(1);
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}
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if (bind(peer, (struct sockaddr *)&s_in, sizeof (s_in)) < 0) {
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syslog(LOG_ERR, "bind: %m\n");
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exit(1);
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}
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if (connect(peer, (struct sockaddr *)&from, sizeof(from)) < 0) {
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syslog(LOG_ERR, "connect: %m\n");
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exit(1);
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}
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tp = (struct tftphdr *)buf;
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tp->th_opcode = ntohs(tp->th_opcode);
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if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
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tftp(tp, n);
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exit(1);
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}
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int validate_access();
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int sendfile(), recvfile();
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struct formats {
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char *f_mode;
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int (*f_validate)();
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int (*f_send)();
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int (*f_recv)();
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int f_convert;
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} formats[] = {
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{ "netascii", validate_access, sendfile, recvfile, 1 },
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{ "octet", validate_access, sendfile, recvfile, 0 },
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#ifdef notdef
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{ "mail", validate_user, sendmail, recvmail, 1 },
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#endif
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{ 0 }
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};
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/*
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* Handle initial connection protocol.
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*/
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tftp(tp, size)
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struct tftphdr *tp;
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int size;
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{
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register char *cp;
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int first = 1, ecode;
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register struct formats *pf;
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char *filename, *mode;
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filename = cp = tp->th_stuff;
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again:
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while (cp < buf + size) {
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if (*cp == '\0')
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break;
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cp++;
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}
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if (*cp != '\0') {
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nak(EBADOP);
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exit(1);
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}
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if (first) {
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mode = ++cp;
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first = 0;
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goto again;
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}
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for (cp = mode; *cp; cp++)
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if (isupper(*cp))
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*cp = tolower(*cp);
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for (pf = formats; pf->f_mode; pf++)
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if (strcmp(pf->f_mode, mode) == 0)
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break;
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if (pf->f_mode == 0) {
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nak(EBADOP);
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exit(1);
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}
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ecode = (*pf->f_validate)(filename, tp->th_opcode);
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if (ecode) {
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nak(ecode);
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exit(1);
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}
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if (tp->th_opcode == WRQ)
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(*pf->f_recv)(pf);
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else
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(*pf->f_send)(pf);
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exit(0);
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}
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FILE *file;
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/*
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* Validate file access. Since we
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* have no uid or gid, for now require
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* file to exist and be publicly
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* readable/writable.
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* If we were invoked with arguments
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* from inetd then the file must also be
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* in one of the given directory prefixes.
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* Note also, full path name must be
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* given as we have no login directory.
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*/
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validate_access(filename, mode)
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char *filename;
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int mode;
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{
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struct stat stbuf;
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int fd;
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char *cp, **dirp;
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if (*filename != '/')
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return (EACCESS);
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/*
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* prevent tricksters from getting around the directory restrictions
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*/
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for (cp = filename + 1; *cp; cp++)
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if(*cp == '.' && strncmp(cp-1, "/../", 4) == 0)
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return(EACCESS);
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for (dirp = dirs; *dirp; dirp++)
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if (strncmp(filename, *dirp, strlen(*dirp)) == 0)
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break;
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if (*dirp==0 && dirp!=dirs)
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return (EACCESS);
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if (stat(filename, &stbuf) < 0)
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return (errno == ENOENT ? ENOTFOUND : EACCESS);
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if (mode == RRQ) {
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if ((stbuf.st_mode&(S_IREAD >> 6)) == 0)
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return (EACCESS);
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} else {
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if ((stbuf.st_mode&(S_IWRITE >> 6)) == 0)
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return (EACCESS);
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}
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fd = open(filename, mode == RRQ ? 0 : 1);
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if (fd < 0)
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return (errno + 100);
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file = fdopen(fd, (mode == RRQ)? "r":"w");
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if (file == NULL) {
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return errno+100;
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}
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return (0);
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}
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int timeout;
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jmp_buf timeoutbuf;
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void
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timer()
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{
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timeout += rexmtval;
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if (timeout >= maxtimeout)
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exit(1);
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longjmp(timeoutbuf, 1);
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}
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/*
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* Send the requested file.
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*/
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sendfile(pf)
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struct formats *pf;
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{
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struct tftphdr *dp, *r_init();
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register struct tftphdr *ap; /* ack packet */
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register int block = 1, size, n;
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signal(SIGALRM, timer);
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dp = r_init();
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ap = (struct tftphdr *)ackbuf;
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do {
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size = readit(file, &dp, pf->f_convert);
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if (size < 0) {
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nak(errno + 100);
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goto abort;
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}
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dp->th_opcode = htons((u_short)DATA);
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dp->th_block = htons((u_short)block);
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timeout = 0;
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(void) setjmp(timeoutbuf);
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send_data:
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if (send(peer, dp, size + 4, 0) != size + 4) {
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syslog(LOG_ERR, "tftpd: write: %m\n");
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goto abort;
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}
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read_ahead(file, pf->f_convert);
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for ( ; ; ) {
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alarm(rexmtval); /* read the ack */
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n = recv(peer, ackbuf, sizeof (ackbuf), 0);
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alarm(0);
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if (n < 0) {
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syslog(LOG_ERR, "tftpd: read: %m\n");
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goto abort;
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}
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ap->th_opcode = ntohs((u_short)ap->th_opcode);
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ap->th_block = ntohs((u_short)ap->th_block);
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if (ap->th_opcode == ERROR)
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goto abort;
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if (ap->th_opcode == ACK) {
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if (ap->th_block == block) {
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break;
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}
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/* Re-synchronize with the other side */
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(void) synchnet(peer);
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if (ap->th_block == (block -1)) {
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goto send_data;
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}
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}
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}
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block++;
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} while (size == SEGSIZE);
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abort:
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(void) fclose(file);
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}
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void
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justquit()
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{
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exit(0);
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}
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/*
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* Receive a file.
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*/
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recvfile(pf)
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struct formats *pf;
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{
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struct tftphdr *dp, *w_init();
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register struct tftphdr *ap; /* ack buffer */
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register int block = 0, n, size;
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signal(SIGALRM, timer);
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dp = w_init();
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ap = (struct tftphdr *)ackbuf;
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do {
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timeout = 0;
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ap->th_opcode = htons((u_short)ACK);
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ap->th_block = htons((u_short)block);
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block++;
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(void) setjmp(timeoutbuf);
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send_ack:
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if (send(peer, ackbuf, 4, 0) != 4) {
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syslog(LOG_ERR, "tftpd: write: %m\n");
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goto abort;
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}
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write_behind(file, pf->f_convert);
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for ( ; ; ) {
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alarm(rexmtval);
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n = recv(peer, dp, PKTSIZE, 0);
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alarm(0);
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if (n < 0) { /* really? */
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syslog(LOG_ERR, "tftpd: read: %m\n");
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goto abort;
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}
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dp->th_opcode = ntohs((u_short)dp->th_opcode);
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dp->th_block = ntohs((u_short)dp->th_block);
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if (dp->th_opcode == ERROR)
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goto abort;
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if (dp->th_opcode == DATA) {
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if (dp->th_block == block) {
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break; /* normal */
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}
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/* Re-synchronize with the other side */
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(void) synchnet(peer);
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if (dp->th_block == (block-1))
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goto send_ack; /* rexmit */
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}
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}
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/* size = write(file, dp->th_data, n - 4); */
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size = writeit(file, &dp, n - 4, pf->f_convert);
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if (size != (n-4)) { /* ahem */
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if (size < 0) nak(errno + 100);
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else nak(ENOSPACE);
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goto abort;
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}
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} while (size == SEGSIZE);
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write_behind(file, pf->f_convert);
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(void) fclose(file); /* close data file */
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ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */
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ap->th_block = htons((u_short)(block));
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(void) send(peer, ackbuf, 4, 0);
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signal(SIGALRM, justquit); /* just quit on timeout */
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alarm(rexmtval);
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n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
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alarm(0);
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if (n >= 4 && /* if read some data */
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dp->th_opcode == DATA && /* and got a data block */
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block == dp->th_block) { /* then my last ack was lost */
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(void) send(peer, ackbuf, 4, 0); /* resend final ack */
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}
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abort:
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return;
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}
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struct errmsg {
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int e_code;
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char *e_msg;
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} errmsgs[] = {
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{ EUNDEF, "Undefined error code" },
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{ ENOTFOUND, "File not found" },
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{ EACCESS, "Access violation" },
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{ ENOSPACE, "Disk full or allocation exceeded" },
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{ EBADOP, "Illegal TFTP operation" },
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{ EBADID, "Unknown transfer ID" },
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{ EEXISTS, "File already exists" },
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{ ENOUSER, "No such user" },
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{ -1, 0 }
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};
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/*
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* Send a nak packet (error message).
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* Error code passed in is one of the
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* standard TFTP codes, or a UNIX errno
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* offset by 100.
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*/
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nak(error)
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int error;
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{
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register struct tftphdr *tp;
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int length;
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register struct errmsg *pe;
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tp = (struct tftphdr *)buf;
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tp->th_opcode = htons((u_short)ERROR);
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tp->th_code = htons((u_short)error);
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for (pe = errmsgs; pe->e_code >= 0; pe++)
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if (pe->e_code == error)
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break;
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if (pe->e_code < 0) {
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pe->e_msg = strerror(error - 100);
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tp->th_code = EUNDEF; /* set 'undef' errorcode */
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}
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strcpy(tp->th_msg, pe->e_msg);
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length = strlen(pe->e_msg);
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tp->th_msg[length] = '\0';
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length += 5;
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if (send(peer, buf, length, 0) != length)
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syslog(LOG_ERR, "nak: %m\n");
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}
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