641 lines
15 KiB
C
641 lines
15 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 are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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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[] = "@(#)tftpd.c 5.8 (Berkeley) 6/18/88";
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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 <string.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <sys/wait.h>
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#include <sys/stat.h>
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#include <netinet/in.h>
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#include <arpa/tftp.h>
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#include <signal.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 <netdb.h>
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#include <setjmp.h>
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#include <syslog.h>
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#ifdef sgi
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/*
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* use *stat64 for files on large filesystems
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*/
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#define stat stat64
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#endif
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#define TIMEOUT 5
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struct sockaddr_in sin = { AF_INET };
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int peer;
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int rexmtval = TIMEOUT;
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int maxtimeout = 24*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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extern struct hostent * __getverfhostent(struct in_addr, int);
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/*
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* Null-terminated directory prefix list for absolute pathname requests and
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* search list for relative pathname requests.
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*
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* MAXDIRS should be at least as large as the number of arguments that
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* inetd allows (currently 10). Add one for the default home directory.
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*/
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#define MAXDIRS (10+1)
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static struct dir {
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char *name;
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int len;
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} dirs[MAXDIRS+1];
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static char *homedir = "/var/boot";
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static int suppress_naks;
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static int secure;
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static int logging;
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static char * errtomsg(int);
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main(argc, argv)
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int argc;
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char **argv;
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{
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register struct tftphdr *tp;
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register int n;
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int on = 1;
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extern char *optarg;
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extern int optind, opterr, optopt;
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register struct dir *dirp;
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openlog("tftpd", LOG_PID, LOG_DAEMON);
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opterr = 0;
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while (getopt(argc, argv, "h:lns") != EOF) {
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switch (optopt) {
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case 'h':
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if (*optarg != '/') {
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syslog(LOG_WARNING,
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"ignoring illegal home directory %s",
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optarg);
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} else
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homedir = optarg;
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break;
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case 'l':
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logging = 1;
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break;
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case 'n':
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suppress_naks = 1;
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break;
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case 's':
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secure = 1;
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break;
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default:
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syslog(LOG_WARNING, "ignoring unknown option -%c",
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optopt);
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}
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}
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/*
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* Get list of directory prefixes. By default, the list is at least
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* the default home directory. If not secure and no directory list
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* specified, append the null prefix ("/") to allow access to any file.
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*/
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dirs[0].name = homedir;
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dirs[0].len = strlen(dirs[0].name);
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dirp = &dirs[1];
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if (optind < argc) {
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for (; optind < argc && dirp < &dirs[MAXDIRS]; optind++) {
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if (argv[optind][0] == '/') {
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dirp->name = argv[optind];
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dirp->len = strlen(dirp->name);
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if (dirp->name[dirp->len - 1] == '/') {
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dirp->len--;
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dirp->name[dirp->len] = '\0';
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}
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dirp++;
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}
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}
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} else if (!secure) {
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dirp->name = "/";
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dirp->len = 1;
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}
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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, (caddr_t)&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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* XXX enhance inetd to support nowait for udp by forking, binding
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* XXX a new socket, and connecting it to the peer.
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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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(caddr_t)&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, (caddr_t)&sin, sizeof (sin)) < 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, (caddr_t)&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 (logging) {
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syslog(LOG_INFO, "%s: %s request for %s: %s",
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__getverfhostent(from.sin_addr, 1)->h_name,
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tp->th_opcode == WRQ ? "write" : "read",
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filename, errtomsg(ecode));
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}
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if (ecode) {
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/*
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* Avoid storms of naks to a RRQ broadcast for a relative
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* bootfile pathname from a diskless Sun. Sun's tftpd just
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* defers the storm.
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*/
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if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
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exit(0);
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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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* 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(filep, mode)
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char **filep;
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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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struct dir *dirp;
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static char pathname[MAXPATHLEN];
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char *filename = *filep;
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if (strstr(filename, "../"))
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return (EACCESS);
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if (*filename == '/') {
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/*
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* Allow the request if it's in one of the approved locations.
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* Special case: check the null prefix ("/") by looking
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* for length = 1 and relying on the arg. processing that
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* it's a /.
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*/
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for (dirp = dirs; dirp->name; dirp++) {
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if (dirp->len == 1 ||
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(!strncmp(filename, dirp->name, dirp->len) &&
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filename[dirp->len] == '/'))
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break;
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}
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if (dirp->name == NULL && 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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} else {
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int err;
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/*
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* Relative file name: search the approved locations for it.
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* Don't allow write requests, in secure mode.
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*/
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if (secure && mode != RRQ) {
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return (EACCESS);
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}
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/*
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* If the file exists in one of the directories and isn't
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* readable, continue looking. However, change the error code
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* from "not found" to "no access" so if it's not found in
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* the other places, users will known the file exists somewhere.
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*/
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err = ENOTFOUND;
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for (dirp = dirs; dirp->name; dirp++) {
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sprintf(pathname, "%s/%s", dirp->name, filename);
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if (stat(pathname, &stbuf) == 0) {
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if ((stbuf.st_mode&(S_IREAD >> 6)) != 0) {
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break;
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}
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err = EACCESS;
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}
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}
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if (dirp->name == NULL && dirp != dirs)
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return (err);
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*filep = filename = pathname;
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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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/* reset the trap */
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(void) signal(SIGALRM, timer);
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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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(void) 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 ((u_short)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 ((u_short)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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(void) 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 ((u_short)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 ((u_short)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); */
|
|
size = writeit(file, &dp, n - 4, pf->f_convert);
|
|
if (size != (n-4)) { /* ahem */
|
|
if (size < 0) nak(errno + 100);
|
|
else nak(ENOSPACE);
|
|
goto abort;
|
|
}
|
|
} while (size == SEGSIZE);
|
|
write_behind(file, pf->f_convert);
|
|
(void) fclose(file); /* close data file */
|
|
|
|
ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */
|
|
ap->th_block = htons((u_short)(block));
|
|
(void) send(peer, ackbuf, 4, 0);
|
|
|
|
(void) signal(SIGALRM, justquit); /* just quit on timeout */
|
|
alarm(rexmtval);
|
|
n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
|
|
alarm(0);
|
|
dp = (struct tftphdr *)buf; /* Fixes Bug 112247 */
|
|
/* Bug reported originally in comp.bugs.4bsd. The problem
|
|
* is that if the above recv(2) succeeds, the "dp" pointer
|
|
* is effectively stale because data was just read into "buf".
|
|
* Simplest solution is to make "dp" reference the new data.
|
|
*/
|
|
if (n >= 4 && /* if read some data */
|
|
dp->th_opcode == DATA && /* and got a data block */
|
|
block == (u_short)dp->th_block) { /* then my last ack was lost */
|
|
(void) send(peer, ackbuf, 4, 0); /* resend final ack */
|
|
}
|
|
abort:
|
|
return;
|
|
}
|
|
|
|
struct errmsg {
|
|
int e_code;
|
|
char *e_msg;
|
|
} errmsgs[] = {
|
|
{ EUNDEF, "Undefined error code" },
|
|
{ ENOTFOUND, "File not found" },
|
|
{ EACCESS, "Access violation" },
|
|
{ ENOSPACE, "Disk full or allocation exceeded" },
|
|
{ EBADOP, "Illegal TFTP operation" },
|
|
{ EBADID, "Unknown transfer ID" },
|
|
{ EEXISTS, "File already exists" },
|
|
{ ENOUSER, "No such user" },
|
|
{ -1, 0 }
|
|
};
|
|
|
|
static char *
|
|
errtomsg(int error)
|
|
{
|
|
static char buf[20];
|
|
register struct errmsg *pe;
|
|
if (error == 0)
|
|
return "success";
|
|
for (pe = errmsgs; pe->e_code >= 0; pe++)
|
|
if (pe->e_code == error)
|
|
return pe->e_msg;
|
|
sprintf(buf, "error %d", error);
|
|
return buf;
|
|
}
|
|
|
|
/*
|
|
* Send a nak packet (error message).
|
|
* Error code passed in is one of the
|
|
* standard TFTP codes, or a UNIX errno
|
|
* offset by 100.
|
|
*/
|
|
nak(error)
|
|
int error;
|
|
{
|
|
register struct tftphdr *tp;
|
|
int length;
|
|
register struct errmsg *pe;
|
|
|
|
tp = (struct tftphdr *)buf;
|
|
tp->th_opcode = htons((u_short)ERROR);
|
|
tp->th_code = htons((u_short)error);
|
|
for (pe = errmsgs; pe->e_code >= 0; pe++)
|
|
if (pe->e_code == error)
|
|
break;
|
|
if (pe->e_code < 0) {
|
|
pe->e_msg = sys_errlist[error - 100];
|
|
tp->th_code = EUNDEF; /* set 'undef' errorcode */
|
|
}
|
|
strcpy(tp->th_msg, pe->e_msg);
|
|
length = strlen(pe->e_msg);
|
|
tp->th_msg[length] = '\0';
|
|
length += 5;
|
|
if (send(peer, buf, length, 0) != length)
|
|
syslog(LOG_ERR, "nak: %m\n");
|
|
}
|