1 /* $NetBSD: tftpd.c,v 1.24 2001/10/09 18:46:18 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1983, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #ifndef lint 38 __COPYRIGHT("@(#) Copyright (c) 1983, 1993\n\ 39 The Regents of the University of California. All rights reserved.\n"); 40 #if 0 41 static char sccsid[] = "@(#)tftpd.c 8.1 (Berkeley) 6/4/93"; 42 #else 43 __RCSID("$NetBSD: tftpd.c,v 1.24 2001/10/09 18:46:18 christos Exp $"); 44 #endif 45 #endif /* not lint */ 46 47 /* 48 * Trivial file transfer protocol server. 49 * 50 * This version includes many modifications by Jim Guyton 51 * <guyton@rand-unix>. 52 */ 53 54 #include <sys/param.h> 55 #include <sys/ioctl.h> 56 #include <sys/stat.h> 57 #include <sys/socket.h> 58 59 #include <netinet/in.h> 60 #include <arpa/tftp.h> 61 #include <arpa/inet.h> 62 63 #include <ctype.h> 64 #include <errno.h> 65 #include <fcntl.h> 66 #include <fcntl.h> 67 #include <grp.h> 68 #include <netdb.h> 69 #include <pwd.h> 70 #include <setjmp.h> 71 #include <signal.h> 72 #include <signal.h> 73 #include <stdio.h> 74 #include <stdlib.h> 75 #include <string.h> 76 #include <syslog.h> 77 #include <unistd.h> 78 79 #include "tftpsubs.h" 80 81 #define DEFAULTUSER "nobody" 82 83 #define TIMEOUT 5 84 85 int peer; 86 int rexmtval = TIMEOUT; 87 int maxtimeout = 5*TIMEOUT; 88 89 #define PKTSIZE SEGSIZE+4 90 char buf[PKTSIZE]; 91 char ackbuf[PKTSIZE]; 92 struct sockaddr_storage from; 93 int fromlen; 94 int debug; 95 96 /* 97 * Null-terminated directory prefix list for absolute pathname requests and 98 * search list for relative pathname requests. 99 * 100 * MAXDIRS should be at least as large as the number of arguments that 101 * inetd allows (currently 20). 102 */ 103 #define MAXDIRS 20 104 static struct dirlist { 105 char *name; 106 int len; 107 } dirs[MAXDIRS+1]; 108 static int suppress_naks; 109 static int logging; 110 static int secure; 111 static char *securedir; 112 113 struct formats; 114 115 static const char *errtomsg(int); 116 static void nak(int); 117 static void tftp(struct tftphdr *, int); 118 static void usage(void); 119 static char *verifyhost(struct sockaddr *); 120 void justquit(int); 121 int main(int, char **); 122 void recvfile(struct formats *); 123 void sendfile(struct formats *); 124 void timer(int); 125 static const char *opcode(int); 126 int validate_access(char **, int); 127 128 struct formats { 129 const char *f_mode; 130 int (*f_validate)(char **, int); 131 void (*f_send)(struct formats *); 132 void (*f_recv)(struct formats *); 133 int f_convert; 134 } formats[] = { 135 { "netascii", validate_access, sendfile, recvfile, 1 }, 136 { "octet", validate_access, sendfile, recvfile, 0 }, 137 { 0 } 138 }; 139 140 static void 141 usage(void) 142 { 143 144 syslog(LOG_ERR, 145 "Usage: %s [-dln] [-u user] [-g group] [-s directory] [directory ...]", 146 getprogname()); 147 exit(1); 148 } 149 150 int 151 main(int argc, char *argv[]) 152 { 153 struct sockaddr_storage me; 154 struct passwd *pwent; 155 struct group *grent; 156 struct tftphdr *tp; 157 char *tgtuser, *tgtgroup, *ep; 158 int n, ch, on, fd; 159 int len; 160 uid_t curuid, tgtuid; 161 gid_t curgid, tgtgid; 162 long nid; 163 164 n = 0; 165 fd = 0; 166 openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_DAEMON); 167 tgtuser = DEFAULTUSER; 168 tgtgroup = NULL; 169 curuid = getuid(); 170 curgid = getgid(); 171 172 while ((ch = getopt(argc, argv, "dg:lns:u:")) != -1) 173 switch (ch) { 174 case 'd': 175 debug++; 176 break; 177 178 case 'g': 179 tgtgroup = optarg; 180 break; 181 182 case 'l': 183 logging = 1; 184 break; 185 186 case 'n': 187 suppress_naks = 1; 188 break; 189 190 case 's': 191 secure = 1; 192 securedir = optarg; 193 break; 194 195 case 'u': 196 tgtuser = optarg; 197 break; 198 199 default: 200 usage(); 201 break; 202 } 203 204 if (optind < argc) { 205 struct dirlist *dirp; 206 207 /* Get list of directory prefixes. Skip relative pathnames. */ 208 for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS]; 209 optind++) { 210 if (argv[optind][0] == '/') { 211 dirp->name = argv[optind]; 212 dirp->len = strlen(dirp->name); 213 dirp++; 214 } 215 } 216 } 217 218 if (*tgtuser == '\0' || (tgtgroup != NULL && *tgtgroup == '\0')) 219 usage(); 220 221 nid = (strtol(tgtuser, &ep, 10)); 222 if (*ep == '\0') { 223 if (nid > UID_MAX) { 224 syslog(LOG_ERR, "uid %ld is too large", nid); 225 exit(1); 226 } 227 pwent = getpwuid((uid_t)nid); 228 } else 229 pwent = getpwnam(tgtuser); 230 if (pwent == NULL) { 231 syslog(LOG_ERR, "unknown user `%s'", tgtuser); 232 exit(1); 233 } 234 tgtuid = pwent->pw_uid; 235 tgtgid = pwent->pw_gid; 236 237 if (tgtgroup != NULL) { 238 nid = (strtol(tgtgroup, &ep, 10)); 239 if (*ep == '\0') { 240 if (nid > GID_MAX) { 241 syslog(LOG_ERR, "gid %ld is too large", nid); 242 exit(1); 243 } 244 grent = getgrgid((gid_t)nid); 245 } else 246 grent = getgrnam(tgtgroup); 247 if (grent != NULL) 248 tgtgid = grent->gr_gid; 249 else { 250 syslog(LOG_ERR, "unknown group `%s'", tgtgroup); 251 exit(1); 252 } 253 } 254 255 if (secure) { 256 if (chdir(securedir) < 0) { 257 syslog(LOG_ERR, "chdir %s: %m", securedir); 258 exit(1); 259 } 260 if (chroot(".")) { 261 syslog(LOG_ERR, "chroot: %m"); 262 exit(1); 263 } 264 } 265 266 if (logging) 267 syslog(LOG_DEBUG, "running as user `%s' (%d), group `%s' (%d)", 268 tgtuser, tgtuid, tgtgroup ? tgtgroup : "(unspecified)", 269 tgtgid); 270 if (curgid != tgtgid) { 271 if (setgid(tgtgid)) { 272 syslog(LOG_ERR, "setgid to %d: %m", (int)tgtgid); 273 exit(1); 274 } 275 if (setgroups(0, NULL)) { 276 syslog(LOG_ERR, "setgroups: %m"); 277 exit(1); 278 } 279 } 280 281 if (curuid != tgtuid) { 282 if (setuid(tgtuid)) { 283 syslog(LOG_ERR, "setuid to %d: %m", (int)tgtuid); 284 exit(1); 285 } 286 } 287 288 on = 1; 289 if (ioctl(fd, FIONBIO, &on) < 0) { 290 syslog(LOG_ERR, "ioctl(FIONBIO): %m"); 291 exit(1); 292 } 293 fromlen = sizeof (from); 294 n = recvfrom(fd, buf, sizeof (buf), 0, 295 (struct sockaddr *)&from, &fromlen); 296 if (n < 0) { 297 syslog(LOG_ERR, "recvfrom: %m"); 298 exit(1); 299 } 300 /* 301 * Now that we have read the message out of the UDP 302 * socket, we fork and exit. Thus, inetd will go back 303 * to listening to the tftp port, and the next request 304 * to come in will start up a new instance of tftpd. 305 * 306 * We do this so that inetd can run tftpd in "wait" mode. 307 * The problem with tftpd running in "nowait" mode is that 308 * inetd may get one or more successful "selects" on the 309 * tftp port before we do our receive, so more than one 310 * instance of tftpd may be started up. Worse, if tftpd 311 * break before doing the above "recvfrom", inetd would 312 * spawn endless instances, clogging the system. 313 */ 314 { 315 int pid; 316 int i, j; 317 318 for (i = 1; i < 20; i++) { 319 pid = fork(); 320 if (pid < 0) { 321 sleep(i); 322 /* 323 * flush out to most recently sent request. 324 * 325 * This may drop some request, but those 326 * will be resent by the clients when 327 * they timeout. The positive effect of 328 * this flush is to (try to) prevent more 329 * than one tftpd being started up to service 330 * a single request from a single client. 331 */ 332 j = sizeof from; 333 i = recvfrom(fd, buf, sizeof (buf), 0, 334 (struct sockaddr *)&from, &j); 335 if (i > 0) { 336 n = i; 337 fromlen = j; 338 } 339 } else { 340 break; 341 } 342 } 343 if (pid < 0) { 344 syslog(LOG_ERR, "fork: %m"); 345 exit(1); 346 } else if (pid != 0) { 347 exit(0); 348 } 349 } 350 351 /* 352 * remember what address this was sent to, so we can respond on the 353 * same interface 354 */ 355 len = sizeof(me); 356 if (getsockname(fd, (struct sockaddr *)&me, &len) == 0) { 357 switch (me.ss_family) { 358 case AF_INET: 359 ((struct sockaddr_in *)&me)->sin_port = 0; 360 break; 361 case AF_INET6: 362 ((struct sockaddr_in6 *)&me)->sin6_port = 0; 363 break; 364 default: 365 /* unsupported */ 366 break; 367 } 368 } else { 369 memset(&me, 0, sizeof(me)); 370 me.ss_family = from.ss_family; 371 me.ss_len = from.ss_len; 372 } 373 374 alarm(0); 375 close(fd); 376 close(1); 377 peer = socket(from.ss_family, SOCK_DGRAM, 0); 378 if (peer < 0) { 379 syslog(LOG_ERR, "socket: %m"); 380 exit(1); 381 } 382 if (bind(peer, (struct sockaddr *)&me, me.ss_len) < 0) { 383 syslog(LOG_ERR, "bind: %m"); 384 exit(1); 385 } 386 if (connect(peer, (struct sockaddr *)&from, from.ss_len) < 0) { 387 syslog(LOG_ERR, "connect: %m"); 388 exit(1); 389 } 390 tp = (struct tftphdr *)buf; 391 tp->th_opcode = ntohs(tp->th_opcode); 392 if (tp->th_opcode == RRQ || tp->th_opcode == WRQ) 393 tftp(tp, n); 394 exit(1); 395 } 396 397 /* 398 * Handle initial connection protocol. 399 */ 400 static void 401 tftp(struct tftphdr *tp, int size) 402 { 403 struct formats *pf; 404 char *cp; 405 char *filename, *mode; 406 int first, ecode; 407 408 first = 1; 409 mode = NULL; 410 411 filename = cp = tp->th_stuff; 412 again: 413 while (cp < buf + size) { 414 if (*cp == '\0') 415 break; 416 cp++; 417 } 418 if (*cp != '\0') { 419 nak(EBADOP); 420 exit(1); 421 } 422 if (first) { 423 mode = ++cp; 424 first = 0; 425 goto again; 426 } 427 for (cp = mode; *cp; cp++) 428 if (isupper(*cp)) 429 *cp = tolower(*cp); 430 for (pf = formats; pf->f_mode; pf++) 431 if (strcmp(pf->f_mode, mode) == 0) 432 break; 433 if (pf->f_mode == 0) { 434 nak(EBADOP); 435 exit(1); 436 } 437 ecode = (*pf->f_validate)(&filename, tp->th_opcode); 438 if (logging) { 439 syslog(LOG_INFO, "%s: %s request for %s: %s", 440 verifyhost((struct sockaddr *)&from), 441 tp->th_opcode == WRQ ? "write" : "read", 442 filename, errtomsg(ecode)); 443 } 444 if (ecode) { 445 /* 446 * Avoid storms of naks to a RRQ broadcast for a relative 447 * bootfile pathname from a diskless Sun. 448 */ 449 if (suppress_naks && *filename != '/' && ecode == ENOTFOUND) 450 exit(0); 451 nak(ecode); 452 exit(1); 453 } 454 if (tp->th_opcode == WRQ) 455 (*pf->f_recv)(pf); 456 else 457 (*pf->f_send)(pf); 458 exit(0); 459 } 460 461 462 FILE *file; 463 464 /* 465 * Validate file access. Since we 466 * have no uid or gid, for now require 467 * file to exist and be publicly 468 * readable/writable. 469 * If we were invoked with arguments 470 * from inetd then the file must also be 471 * in one of the given directory prefixes. 472 */ 473 int 474 validate_access(char **filep, int mode) 475 { 476 struct stat stbuf; 477 struct dirlist *dirp; 478 static char pathname[MAXPATHLEN]; 479 char *filename; 480 int fd; 481 482 filename = *filep; 483 484 /* 485 * Prevent tricksters from getting around the directory restrictions 486 */ 487 if (strstr(filename, "/../")) 488 return (EACCESS); 489 490 if (*filename == '/') { 491 /* 492 * Allow the request if it's in one of the approved locations. 493 * Special case: check the null prefix ("/") by looking 494 * for length = 1 and relying on the arg. processing that 495 * it's a /. 496 */ 497 for (dirp = dirs; dirp->name != NULL; dirp++) { 498 if (dirp->len == 1 || 499 (!strncmp(filename, dirp->name, dirp->len) && 500 filename[dirp->len] == '/')) 501 break; 502 } 503 /* If directory list is empty, allow access to any file */ 504 if (dirp->name == NULL && dirp != dirs) 505 return (EACCESS); 506 if (stat(filename, &stbuf) < 0) 507 return (errno == ENOENT ? ENOTFOUND : EACCESS); 508 if (!S_ISREG(stbuf.st_mode)) 509 return (ENOTFOUND); 510 if (mode == RRQ) { 511 if ((stbuf.st_mode & S_IROTH) == 0) 512 return (EACCESS); 513 } else { 514 if ((stbuf.st_mode & S_IWOTH) == 0) 515 return (EACCESS); 516 } 517 } else { 518 /* 519 * Relative file name: search the approved locations for it. 520 */ 521 522 if (!strncmp(filename, "../", 3)) 523 return (EACCESS); 524 525 /* 526 * Find the first file that exists in any of the directories, 527 * check access on it. 528 */ 529 if (dirs[0].name != NULL) { 530 for (dirp = dirs; dirp->name != NULL; dirp++) { 531 snprintf(pathname, sizeof pathname, "%s/%s", 532 dirp->name, filename); 533 if (stat(pathname, &stbuf) == 0 && 534 (stbuf.st_mode & S_IFMT) == S_IFREG) { 535 break; 536 } 537 } 538 if (dirp->name == NULL) 539 return (ENOTFOUND); 540 if (mode == RRQ && !(stbuf.st_mode & S_IROTH)) 541 return (EACCESS); 542 if (mode == WRQ && !(stbuf.st_mode & S_IWOTH)) 543 return (EACCESS); 544 *filep = filename = pathname; 545 } else { 546 /* 547 * If there's no directory list, take our cue from the 548 * absolute file request check above (*filename == '/'), 549 * and allow access to anything. 550 */ 551 if (stat(filename, &stbuf) < 0) 552 return (errno == ENOENT ? ENOTFOUND : EACCESS); 553 if (!S_ISREG(stbuf.st_mode)) 554 return (ENOTFOUND); 555 if (mode == RRQ) { 556 if ((stbuf.st_mode & S_IROTH) == 0) 557 return (EACCESS); 558 } else { 559 if ((stbuf.st_mode & S_IWOTH) == 0) 560 return (EACCESS); 561 } 562 *filep = filename; 563 } 564 } 565 fd = open(filename, mode == RRQ ? O_RDONLY : O_WRONLY | O_TRUNC); 566 if (fd < 0) 567 return (errno + 100); 568 file = fdopen(fd, (mode == RRQ)? "r":"w"); 569 if (file == NULL) { 570 close(fd); 571 return (errno + 100); 572 } 573 return (0); 574 } 575 576 int timeout; 577 jmp_buf timeoutbuf; 578 579 void 580 timer(int dummy) 581 { 582 583 timeout += rexmtval; 584 if (timeout >= maxtimeout) 585 exit(1); 586 longjmp(timeoutbuf, 1); 587 } 588 589 static const char * 590 opcode(int code) 591 { 592 static char buf[64]; 593 594 switch (code) { 595 case RRQ: 596 return "RRQ"; 597 case WRQ: 598 return "WRQ"; 599 case DATA: 600 return "DATA"; 601 case ACK: 602 return "ACK"; 603 case ERROR: 604 return "ERROR"; 605 default: 606 (void)snprintf(buf, sizeof(buf), "*code %d*", code); 607 return buf; 608 } 609 } 610 611 /* 612 * Send the requested file. 613 */ 614 void 615 sendfile(struct formats *pf) 616 { 617 volatile unsigned int block; 618 struct tftphdr *dp; 619 struct tftphdr *ap; /* ack packet */ 620 int size, n; 621 622 signal(SIGALRM, timer); 623 dp = r_init(); 624 ap = (struct tftphdr *)ackbuf; 625 block = 1; 626 do { 627 size = readit(file, &dp, pf->f_convert); 628 if (size < 0) { 629 nak(errno + 100); 630 goto abort; 631 } 632 dp->th_opcode = htons((u_short)DATA); 633 dp->th_block = htons((u_short)block); 634 timeout = 0; 635 (void)setjmp(timeoutbuf); 636 637 send_data: 638 if (debug) 639 syslog(LOG_DEBUG, "Send DATA %u", block); 640 if (send(peer, dp, size + 4, 0) != size + 4) { 641 syslog(LOG_ERR, "tftpd: write: %m"); 642 goto abort; 643 } 644 read_ahead(file, pf->f_convert); 645 for ( ; ; ) { 646 alarm(rexmtval); /* read the ack */ 647 n = recv(peer, ackbuf, sizeof (ackbuf), 0); 648 alarm(0); 649 if (n < 0) { 650 syslog(LOG_ERR, "tftpd: read: %m"); 651 goto abort; 652 } 653 ap->th_opcode = ntohs((u_short)ap->th_opcode); 654 ap->th_block = ntohs((u_short)ap->th_block); 655 switch (ap->th_opcode) { 656 case ERROR: 657 goto abort; 658 659 case ACK: 660 if (ap->th_block == block) 661 goto done; 662 if (debug) 663 syslog(LOG_DEBUG, "Resync ACK %u != %u", 664 (unsigned int)ap->th_block, block); 665 /* Re-synchronize with the other side */ 666 (void) synchnet(peer); 667 if (ap->th_block == (block -1)) 668 goto send_data; 669 default: 670 syslog(LOG_INFO, "Received %s in sendfile\n", 671 opcode(dp->th_opcode)); 672 } 673 674 } 675 done: 676 if (debug) 677 syslog(LOG_DEBUG, "Received ACK for block %u", block); 678 block++; 679 } while (size == SEGSIZE); 680 abort: 681 (void) fclose(file); 682 } 683 684 void 685 justquit(int dummy) 686 { 687 688 exit(0); 689 } 690 691 /* 692 * Receive a file. 693 */ 694 void 695 recvfile(struct formats *pf) 696 { 697 volatile unsigned int block; 698 struct tftphdr *dp; 699 struct tftphdr *ap; /* ack buffer */ 700 int n, size; 701 702 signal(SIGALRM, timer); 703 dp = w_init(); 704 ap = (struct tftphdr *)ackbuf; 705 block = 0; 706 do { 707 timeout = 0; 708 ap->th_opcode = htons((u_short)ACK); 709 ap->th_block = htons((u_short)block); 710 if (debug) 711 syslog(LOG_DEBUG, "Sending ACK for block %u\n", block); 712 block++; 713 (void) setjmp(timeoutbuf); 714 send_ack: 715 if (send(peer, ackbuf, 4, 0) != 4) { 716 syslog(LOG_ERR, "tftpd: write: %m"); 717 goto abort; 718 } 719 write_behind(file, pf->f_convert); 720 for ( ; ; ) { 721 alarm(rexmtval); 722 n = recv(peer, dp, PKTSIZE, 0); 723 alarm(0); 724 if (n < 0) { /* really? */ 725 syslog(LOG_ERR, "tftpd: read: %m"); 726 goto abort; 727 } 728 dp->th_opcode = ntohs((u_short)dp->th_opcode); 729 dp->th_block = ntohs((u_short)dp->th_block); 730 if (debug) 731 syslog(LOG_DEBUG, "Received %s for block %u", 732 opcode(dp->th_opcode), 733 (unsigned int)dp->th_block); 734 735 switch (dp->th_opcode) { 736 case ERROR: 737 goto abort; 738 case DATA: 739 if (dp->th_block == block) 740 goto done; /* normal */ 741 if (debug) 742 syslog(LOG_DEBUG, "Resync %u != %u", 743 (unsigned int)dp->th_block, block); 744 /* Re-synchronize with the other side */ 745 (void) synchnet(peer); 746 if (dp->th_block == (block-1)) 747 goto send_ack; /* rexmit */ 748 break; 749 default: 750 syslog(LOG_INFO, "Received %s in recvfile\n", 751 opcode(dp->th_opcode)); 752 break; 753 } 754 } 755 done: 756 if (debug) 757 syslog(LOG_DEBUG, "Got block %u", block); 758 /* size = write(file, dp->th_data, n - 4); */ 759 size = writeit(file, &dp, n - 4, pf->f_convert); 760 if (size != (n-4)) { /* ahem */ 761 if (size < 0) nak(errno + 100); 762 else nak(ENOSPACE); 763 goto abort; 764 } 765 } while (size == SEGSIZE); 766 write_behind(file, pf->f_convert); 767 (void) fclose(file); /* close data file */ 768 769 ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */ 770 ap->th_block = htons((u_short)(block)); 771 if (debug) 772 syslog(LOG_DEBUG, "Send final ACK %u", block); 773 (void) send(peer, ackbuf, 4, 0); 774 775 signal(SIGALRM, justquit); /* just quit on timeout */ 776 alarm(rexmtval); 777 n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */ 778 alarm(0); 779 if (n >= 4 && /* if read some data */ 780 dp->th_opcode == DATA && /* and got a data block */ 781 block == dp->th_block) { /* then my last ack was lost */ 782 (void) send(peer, ackbuf, 4, 0); /* resend final ack */ 783 } 784 abort: 785 return; 786 } 787 788 const struct errmsg { 789 int e_code; 790 const char *e_msg; 791 } errmsgs[] = { 792 { EUNDEF, "Undefined error code" }, 793 { ENOTFOUND, "File not found" }, 794 { EACCESS, "Access violation" }, 795 { ENOSPACE, "Disk full or allocation exceeded" }, 796 { EBADOP, "Illegal TFTP operation" }, 797 { EBADID, "Unknown transfer ID" }, 798 { EEXISTS, "File already exists" }, 799 { ENOUSER, "No such user" }, 800 { -1, 0 } 801 }; 802 803 static const char * 804 errtomsg(int error) 805 { 806 static char ebuf[20]; 807 const struct errmsg *pe; 808 809 if (error == 0) 810 return ("success"); 811 for (pe = errmsgs; pe->e_code >= 0; pe++) 812 if (pe->e_code == error) 813 return (pe->e_msg); 814 snprintf(ebuf, sizeof(ebuf), "error %d", error); 815 return (ebuf); 816 } 817 818 /* 819 * Send a nak packet (error message). 820 * Error code passed in is one of the 821 * standard TFTP codes, or a UNIX errno 822 * offset by 100. 823 */ 824 static void 825 nak(int error) 826 { 827 const struct errmsg *pe; 828 struct tftphdr *tp; 829 int length; 830 size_t msglen; 831 832 tp = (struct tftphdr *)buf; 833 tp->th_opcode = htons((u_short)ERROR); 834 msglen = sizeof(buf) - (&tp->th_msg[0] - buf); 835 for (pe = errmsgs; pe->e_code >= 0; pe++) 836 if (pe->e_code == error) 837 break; 838 if (pe->e_code < 0) { 839 tp->th_code = EUNDEF; /* set 'undef' errorcode */ 840 strlcpy(tp->th_msg, strerror(error - 100), msglen); 841 } else { 842 tp->th_code = htons((u_short)error); 843 strlcpy(tp->th_msg, pe->e_msg, msglen); 844 } 845 if (debug) 846 syslog(LOG_DEBUG, "Send NACK %s", tp->th_msg); 847 length = strlen(tp->th_msg); 848 msglen = &tp->th_msg[length + 1] - buf; 849 if (send(peer, buf, msglen, 0) != msglen) 850 syslog(LOG_ERR, "nak: %m"); 851 } 852 853 static char * 854 verifyhost(struct sockaddr *fromp) 855 { 856 static char hbuf[MAXHOSTNAMELEN]; 857 858 if (getnameinfo(fromp, fromp->sa_len, hbuf, sizeof(hbuf), NULL, 0, 0)) 859 strlcpy(hbuf, "?", sizeof(hbuf)); 860 return (hbuf); 861 } 862