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1.1 root 1: /*
2: * Copyright (c) 1983 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms are permitted
6: * provided that: (1) source distributions retain this entire copyright
7: * notice and comment, and (2) distributions including binaries display
8: * the following acknowledgement: ``This product includes software
9: * developed by the University of California, Berkeley and its contributors''
10: * in the documentation or other materials provided with the distribution
11: * and in all advertising materials mentioning features or use of this
12: * software. Neither the name of the University nor the names of its
13: * contributors may be used to endorse or promote products derived
14: * from this software without specific prior written permission.
15: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
17: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
18: */
19:
20: #ifndef lint
21: char copyright[] =
22: "@(#) Copyright (c) 1983 Regents of the University of California.\n\
23: All rights reserved.\n";
24: #endif /* not lint */
25:
26: #ifndef lint
27: static char sccsid[] = "@(#)tftpd.c 5.12 (Berkeley) 6/1/90";
28: #endif /* not lint */
29:
30: /*
31: * Trivial file transfer protocol server.
32: *
33: * This version includes many modifications by Jim Guyton <guyton@rand-unix>
34: */
35:
36: #include <sys/types.h>
37: #include <sys/socket.h>
38: #include <sys/ioctl.h>
39: #include <sys/wait.h>
40: #include <sys/stat.h>
41: #include <sys/signal.h>
42:
43: #include <netinet/in.h>
44:
45: #include <arpa/tftp.h>
46:
47: #include <netdb.h>
48: #include <setjmp.h>
49: #include <stdio.h>
50: #include <errno.h>
51: #include <ctype.h>
52: #include <syslog.h>
53: #include <string.h>
54:
55: #define TIMEOUT 5
56:
57: extern int errno;
58: struct sockaddr_in sin = { AF_INET };
59: int peer;
60: int rexmtval = TIMEOUT;
61: int maxtimeout = 5*TIMEOUT;
62:
63: #define PKTSIZE SEGSIZE+4
64: char buf[PKTSIZE];
65: char ackbuf[PKTSIZE];
66: struct sockaddr_in from;
67: int fromlen;
68:
69: #define MAXARG 4
70: char *dirs[MAXARG+1];
71:
72: main(ac, av)
73: char **av;
74: {
75: register struct tftphdr *tp;
76: register int n = 0;
77: int on = 1;
78:
79: ac--; av++;
80: while (ac-- > 0 && n < MAXARG)
81: dirs[n++] = *av++;
82: openlog("tftpd", LOG_PID, LOG_DAEMON);
83: if (ioctl(0, FIONBIO, &on) < 0) {
84: syslog(LOG_ERR, "ioctl(FIONBIO): %m\n");
85: exit(1);
86: }
87: fromlen = sizeof (from);
88: n = recvfrom(0, buf, sizeof (buf), 0,
89: (caddr_t)&from, &fromlen);
90: if (n < 0) {
91: syslog(LOG_ERR, "recvfrom: %m\n");
92: exit(1);
93: }
94: /*
95: * Now that we have read the message out of the UDP
96: * socket, we fork and exit. Thus, inetd will go back
97: * to listening to the tftp port, and the next request
98: * to come in will start up a new instance of tftpd.
99: *
100: * We do this so that inetd can run tftpd in "wait" mode.
101: * The problem with tftpd running in "nowait" mode is that
102: * inetd may get one or more successful "selects" on the
103: * tftp port before we do our receive, so more than one
104: * instance of tftpd may be started up. Worse, if tftpd
105: * break before doing the above "recvfrom", inetd would
106: * spawn endless instances, clogging the system.
107: */
108: {
109: int pid;
110: int i, j;
111:
112: for (i = 1; i < 20; i++) {
113: pid = fork();
114: if (pid < 0) {
115: sleep(i);
116: /*
117: * flush out to most recently sent request.
118: *
119: * This may drop some request, but those
120: * will be resent by the clients when
121: * they timeout. The positive effect of
122: * this flush is to (try to) prevent more
123: * than one tftpd being started up to service
124: * a single request from a single client.
125: */
126: j = sizeof from;
127: i = recvfrom(0, buf, sizeof (buf), 0,
128: (caddr_t)&from, &j);
129: if (i > 0) {
130: n = i;
131: fromlen = j;
132: }
133: } else {
134: break;
135: }
136: }
137: if (pid < 0) {
138: syslog(LOG_ERR, "fork: %m\n");
139: exit(1);
140: } else if (pid != 0) {
141: exit(0);
142: }
143: }
144: from.sin_family = AF_INET;
145: alarm(0);
146: close(0);
147: close(1);
148: peer = socket(AF_INET, SOCK_DGRAM, 0);
149: if (peer < 0) {
150: syslog(LOG_ERR, "socket: %m\n");
151: exit(1);
152: }
153: if (bind(peer, (caddr_t)&sin, sizeof (sin)) < 0) {
154: syslog(LOG_ERR, "bind: %m\n");
155: exit(1);
156: }
157: if (connect(peer, (caddr_t)&from, sizeof(from)) < 0) {
158: syslog(LOG_ERR, "connect: %m\n");
159: exit(1);
160: }
161: tp = (struct tftphdr *)buf;
162: tp->th_opcode = ntohs(tp->th_opcode);
163: if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
164: tftp(tp, n);
165: exit(1);
166: }
167:
168: int validate_access();
169: int sendfile(), recvfile();
170:
171: struct formats {
172: char *f_mode;
173: int (*f_validate)();
174: int (*f_send)();
175: int (*f_recv)();
176: int f_convert;
177: } formats[] = {
178: { "netascii", validate_access, sendfile, recvfile, 1 },
179: { "octet", validate_access, sendfile, recvfile, 0 },
180: #ifdef notdef
181: { "mail", validate_user, sendmail, recvmail, 1 },
182: #endif
183: { 0 }
184: };
185:
186: /*
187: * Handle initial connection protocol.
188: */
189: tftp(tp, size)
190: struct tftphdr *tp;
191: int size;
192: {
193: register char *cp;
194: int first = 1, ecode;
195: register struct formats *pf;
196: char *filename, *mode;
197:
198: filename = cp = tp->th_stuff;
199: again:
200: while (cp < buf + size) {
201: if (*cp == '\0')
202: break;
203: cp++;
204: }
205: if (*cp != '\0') {
206: nak(EBADOP);
207: exit(1);
208: }
209: if (first) {
210: mode = ++cp;
211: first = 0;
212: goto again;
213: }
214: for (cp = mode; *cp; cp++)
215: if (isupper(*cp))
216: *cp = tolower(*cp);
217: for (pf = formats; pf->f_mode; pf++)
218: if (strcmp(pf->f_mode, mode) == 0)
219: break;
220: if (pf->f_mode == 0) {
221: nak(EBADOP);
222: exit(1);
223: }
224: ecode = (*pf->f_validate)(filename, tp->th_opcode);
225: if (ecode) {
226: nak(ecode);
227: exit(1);
228: }
229: if (tp->th_opcode == WRQ)
230: (*pf->f_recv)(pf);
231: else
232: (*pf->f_send)(pf);
233: exit(0);
234: }
235:
236:
237: FILE *file;
238:
239: /*
240: * Validate file access. Since we
241: * have no uid or gid, for now require
242: * file to exist and be publicly
243: * readable/writable.
244: * If we were invoked with arguments
245: * from inetd then the file must also be
246: * in one of the given directory prefixes.
247: * Note also, full path name must be
248: * given as we have no login directory.
249: */
250: validate_access(filename, mode)
251: char *filename;
252: int mode;
253: {
254: struct stat stbuf;
255: int fd;
256: char *cp, **dirp;
257:
258: if (*filename != '/')
259: return (EACCESS);
260: /*
261: * prevent tricksters from getting around the directory restrictions
262: */
263: for (cp = filename + 1; *cp; cp++)
264: if(*cp == '.' && strncmp(cp-1, "/../", 4) == 0)
265: return(EACCESS);
266: for (dirp = dirs; *dirp; dirp++)
267: if (strncmp(filename, *dirp, strlen(*dirp)) == 0)
268: break;
269: if (*dirp==0 && dirp!=dirs)
270: return (EACCESS);
271: if (stat(filename, &stbuf) < 0)
272: return (errno == ENOENT ? ENOTFOUND : EACCESS);
273: if (mode == RRQ) {
274: if ((stbuf.st_mode&(S_IREAD >> 6)) == 0)
275: return (EACCESS);
276: } else {
277: if ((stbuf.st_mode&(S_IWRITE >> 6)) == 0)
278: return (EACCESS);
279: }
280: fd = open(filename, mode == RRQ ? 0 : 1);
281: if (fd < 0)
282: return (errno + 100);
283: file = fdopen(fd, (mode == RRQ)? "r":"w");
284: if (file == NULL) {
285: return errno+100;
286: }
287: return (0);
288: }
289:
290: int timeout;
291: jmp_buf timeoutbuf;
292:
293: timer()
294: {
295:
296: timeout += rexmtval;
297: if (timeout >= maxtimeout)
298: exit(1);
299: longjmp(timeoutbuf, 1);
300: }
301:
302: /*
303: * Send the requested file.
304: */
305: sendfile(pf)
306: struct formats *pf;
307: {
308: struct tftphdr *dp, *r_init();
309: register struct tftphdr *ap; /* ack packet */
310: register int block = 1, size, n;
311:
312: signal(SIGALRM, timer);
313: dp = r_init();
314: ap = (struct tftphdr *)ackbuf;
315: do {
316: size = readit(file, &dp, pf->f_convert);
317: if (size < 0) {
318: nak(errno + 100);
319: goto abort;
320: }
321: dp->th_opcode = htons((u_short)DATA);
322: dp->th_block = htons((u_short)block);
323: timeout = 0;
324: (void) setjmp(timeoutbuf);
325:
326: send_data:
327: if (send(peer, dp, size + 4, 0) != size + 4) {
328: syslog(LOG_ERR, "tftpd: write: %m\n");
329: goto abort;
330: }
331: read_ahead(file, pf->f_convert);
332: for ( ; ; ) {
333: alarm(rexmtval); /* read the ack */
334: n = recv(peer, ackbuf, sizeof (ackbuf), 0);
335: alarm(0);
336: if (n < 0) {
337: syslog(LOG_ERR, "tftpd: read: %m\n");
338: goto abort;
339: }
340: ap->th_opcode = ntohs((u_short)ap->th_opcode);
341: ap->th_block = ntohs((u_short)ap->th_block);
342:
343: if (ap->th_opcode == ERROR)
344: goto abort;
345:
346: if (ap->th_opcode == ACK) {
347: if (ap->th_block == block) {
348: break;
349: }
350: /* Re-synchronize with the other side */
351: (void) synchnet(peer);
352: if (ap->th_block == (block -1)) {
353: goto send_data;
354: }
355: }
356:
357: }
358: block++;
359: } while (size == SEGSIZE);
360: abort:
361: (void) fclose(file);
362: }
363:
364: justquit()
365: {
366: exit(0);
367: }
368:
369:
370: /*
371: * Receive a file.
372: */
373: recvfile(pf)
374: struct formats *pf;
375: {
376: struct tftphdr *dp, *w_init();
377: register struct tftphdr *ap; /* ack buffer */
378: register int block = 0, n, size;
379:
380: signal(SIGALRM, timer);
381: dp = w_init();
382: ap = (struct tftphdr *)ackbuf;
383: do {
384: timeout = 0;
385: ap->th_opcode = htons((u_short)ACK);
386: ap->th_block = htons((u_short)block);
387: block++;
388: (void) setjmp(timeoutbuf);
389: send_ack:
390: if (send(peer, ackbuf, 4, 0) != 4) {
391: syslog(LOG_ERR, "tftpd: write: %m\n");
392: goto abort;
393: }
394: write_behind(file, pf->f_convert);
395: for ( ; ; ) {
396: alarm(rexmtval);
397: n = recv(peer, dp, PKTSIZE, 0);
398: alarm(0);
399: if (n < 0) { /* really? */
400: syslog(LOG_ERR, "tftpd: read: %m\n");
401: goto abort;
402: }
403: dp->th_opcode = ntohs((u_short)dp->th_opcode);
404: dp->th_block = ntohs((u_short)dp->th_block);
405: if (dp->th_opcode == ERROR)
406: goto abort;
407: if (dp->th_opcode == DATA) {
408: if (dp->th_block == block) {
409: break; /* normal */
410: }
411: /* Re-synchronize with the other side */
412: (void) synchnet(peer);
413: if (dp->th_block == (block-1))
414: goto send_ack; /* rexmit */
415: }
416: }
417: /* size = write(file, dp->th_data, n - 4); */
418: size = writeit(file, &dp, n - 4, pf->f_convert);
419: if (size != (n-4)) { /* ahem */
420: if (size < 0) nak(errno + 100);
421: else nak(ENOSPACE);
422: goto abort;
423: }
424: } while (size == SEGSIZE);
425: write_behind(file, pf->f_convert);
426: (void) fclose(file); /* close data file */
427:
428: ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */
429: ap->th_block = htons((u_short)(block));
430: (void) send(peer, ackbuf, 4, 0);
431:
432: signal(SIGALRM, justquit); /* just quit on timeout */
433: alarm(rexmtval);
434: n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
435: alarm(0);
436: if (n >= 4 && /* if read some data */
437: dp->th_opcode == DATA && /* and got a data block */
438: block == dp->th_block) { /* then my last ack was lost */
439: (void) send(peer, ackbuf, 4, 0); /* resend final ack */
440: }
441: abort:
442: return;
443: }
444:
445: struct errmsg {
446: int e_code;
447: char *e_msg;
448: } errmsgs[] = {
449: { EUNDEF, "Undefined error code" },
450: { ENOTFOUND, "File not found" },
451: { EACCESS, "Access violation" },
452: { ENOSPACE, "Disk full or allocation exceeded" },
453: { EBADOP, "Illegal TFTP operation" },
454: { EBADID, "Unknown transfer ID" },
455: { EEXISTS, "File already exists" },
456: { ENOUSER, "No such user" },
457: { -1, 0 }
458: };
459:
460: /*
461: * Send a nak packet (error message).
462: * Error code passed in is one of the
463: * standard TFTP codes, or a UNIX errno
464: * offset by 100.
465: */
466: nak(error)
467: int error;
468: {
469: register struct tftphdr *tp;
470: int length;
471: register struct errmsg *pe;
472:
473: tp = (struct tftphdr *)buf;
474: tp->th_opcode = htons((u_short)ERROR);
475: tp->th_code = htons((u_short)error);
476: for (pe = errmsgs; pe->e_code >= 0; pe++)
477: if (pe->e_code == error)
478: break;
479: if (pe->e_code < 0) {
480: pe->e_msg = strerror(error - 100);
481: tp->th_code = EUNDEF; /* set 'undef' errorcode */
482: }
483: strcpy(tp->th_msg, pe->e_msg);
484: length = strlen(pe->e_msg);
485: tp->th_msg[length] = '\0';
486: length += 5;
487: if (send(peer, buf, length, 0) != length)
488: syslog(LOG_ERR, "nak: %m\n");
489: }
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