1 /* 2 * Copyright (c) 1983, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#) Copyright (c) 1983, 1993 The Regents of the University of California. All rights reserved. 34 * @(#)tftpd.c 8.1 (Berkeley) 6/4/93 35 * $FreeBSD: src/libexec/tftpd/tftpd.c,v 1.15.2.5 2003/04/06 19:42:56 dwmalone Exp $ 36 * $DragonFly: src/libexec/tftpd/tftpd.c,v 1.3 2003/11/20 14:32:17 eirikn Exp $ 37 */ 38 39 /* 40 * Trivial file transfer protocol server. 41 * 42 * This version includes many modifications by Jim Guyton 43 * <guyton@rand-unix>. 44 */ 45 46 #include <sys/param.h> 47 #include <sys/ioctl.h> 48 #include <sys/stat.h> 49 #include <sys/socket.h> 50 #include <sys/types.h> 51 52 #include <netinet/in.h> 53 #include <arpa/tftp.h> 54 #include <arpa/inet.h> 55 56 #include <ctype.h> 57 #include <errno.h> 58 #include <fcntl.h> 59 #include <libutil.h> 60 #include <netdb.h> 61 #include <pwd.h> 62 #include <setjmp.h> 63 #include <signal.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <syslog.h> 68 #include <unistd.h> 69 70 #include "tftpsubs.h" 71 72 #define TIMEOUT 5 73 #define MAX_TIMEOUTS 5 74 75 int peer; 76 int rexmtval = TIMEOUT; 77 int max_rexmtval = 2*TIMEOUT; 78 79 #define PKTSIZE SEGSIZE+4 80 char buf[PKTSIZE]; 81 char ackbuf[PKTSIZE]; 82 struct sockaddr_storage from; 83 int fromlen; 84 85 void tftp(struct tftphdr *, int); 86 static void unmappedaddr(struct sockaddr_in6 *); 87 88 /* 89 * Null-terminated directory prefix list for absolute pathname requests and 90 * search list for relative pathname requests. 91 * 92 * MAXDIRS should be at least as large as the number of arguments that 93 * inetd allows (currently 20). 94 */ 95 #define MAXDIRS 20 96 static struct dirlist { 97 const char *name; 98 int len; 99 } dirs[MAXDIRS+1]; 100 static int suppress_naks; 101 static int logging; 102 static int ipchroot; 103 104 static const char *errtomsg(int); 105 static void nak(int); 106 static void oack(void); 107 108 static void timer(int); 109 static void justquit(int); 110 111 int 112 main(int argc, char *argv[]) 113 { 114 struct tftphdr *tp; 115 int n; 116 int ch, on; 117 struct sockaddr_storage me; 118 int len; 119 char *chroot_dir = NULL; 120 struct passwd *nobody; 121 const char *chuser = "nobody"; 122 123 openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP); 124 while ((ch = getopt(argc, argv, "cClns:u:")) != -1) { 125 switch (ch) { 126 case 'c': 127 ipchroot = 1; 128 break; 129 case 'C': 130 ipchroot = 2; 131 break; 132 case 'l': 133 logging = 1; 134 break; 135 case 'n': 136 suppress_naks = 1; 137 break; 138 case 's': 139 chroot_dir = optarg; 140 break; 141 case 'u': 142 chuser = optarg; 143 break; 144 default: 145 syslog(LOG_WARNING, "ignoring unknown option -%c", ch); 146 } 147 } 148 if (optind < argc) { 149 struct dirlist *dirp; 150 151 /* Get list of directory prefixes. Skip relative pathnames. */ 152 for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS]; 153 optind++) { 154 if (argv[optind][0] == '/') { 155 dirp->name = argv[optind]; 156 dirp->len = strlen(dirp->name); 157 dirp++; 158 } 159 } 160 } 161 else if (chroot_dir) { 162 dirs->name = "/"; 163 dirs->len = 1; 164 } 165 if (ipchroot && chroot_dir == NULL) { 166 syslog(LOG_ERR, "-c requires -s"); 167 exit(1); 168 } 169 170 on = 1; 171 if (ioctl(0, FIONBIO, &on) < 0) { 172 syslog(LOG_ERR, "ioctl(FIONBIO): %m"); 173 exit(1); 174 } 175 fromlen = sizeof (from); 176 n = recvfrom(0, buf, sizeof (buf), 0, 177 (struct sockaddr *)&from, &fromlen); 178 if (n < 0) { 179 syslog(LOG_ERR, "recvfrom: %m"); 180 exit(1); 181 } 182 /* 183 * Now that we have read the message out of the UDP 184 * socket, we fork and exit. Thus, inetd will go back 185 * to listening to the tftp port, and the next request 186 * to come in will start up a new instance of tftpd. 187 * 188 * We do this so that inetd can run tftpd in "wait" mode. 189 * The problem with tftpd running in "nowait" mode is that 190 * inetd may get one or more successful "selects" on the 191 * tftp port before we do our receive, so more than one 192 * instance of tftpd may be started up. Worse, if tftpd 193 * break before doing the above "recvfrom", inetd would 194 * spawn endless instances, clogging the system. 195 */ 196 { 197 int pid; 198 int i, j; 199 200 for (i = 1; i < 20; i++) { 201 pid = fork(); 202 if (pid < 0) { 203 sleep(i); 204 /* 205 * flush out to most recently sent request. 206 * 207 * This may drop some request, but those 208 * will be resent by the clients when 209 * they timeout. The positive effect of 210 * this flush is to (try to) prevent more 211 * than one tftpd being started up to service 212 * a single request from a single client. 213 */ 214 j = sizeof from; 215 i = recvfrom(0, buf, sizeof (buf), 0, 216 (struct sockaddr *)&from, &j); 217 if (i > 0) { 218 n = i; 219 fromlen = j; 220 } 221 } else { 222 break; 223 } 224 } 225 if (pid < 0) { 226 syslog(LOG_ERR, "fork: %m"); 227 exit(1); 228 } else if (pid != 0) { 229 exit(0); 230 } 231 } 232 233 /* 234 * Since we exit here, we should do that only after the above 235 * recvfrom to keep inetd from constantly forking should there 236 * be a problem. See the above comment about system clogging. 237 */ 238 if (chroot_dir) { 239 if (ipchroot) { 240 char *tempchroot; 241 struct stat sb; 242 int statret; 243 struct sockaddr_storage ss; 244 char hbuf[NI_MAXHOST]; 245 246 memcpy(&ss, &from, from.ss_len); 247 unmappedaddr((struct sockaddr_in6 *)&ss); 248 getnameinfo((struct sockaddr *)&ss, ss.ss_len, 249 hbuf, sizeof(hbuf), NULL, 0, 250 NI_NUMERICHOST | NI_WITHSCOPEID); 251 asprintf(&tempchroot, "%s/%s", chroot_dir, hbuf); 252 statret = stat(tempchroot, &sb); 253 if ((sb.st_mode & S_IFDIR) && 254 (statret == 0 || (statret == -1 && ipchroot == 1))) 255 chroot_dir = tempchroot; 256 } 257 /* Must get this before chroot because /etc might go away */ 258 if ((nobody = getpwnam(chuser)) == NULL) { 259 syslog(LOG_ERR, "%s: no such user", chuser); 260 exit(1); 261 } 262 if (chroot(chroot_dir)) { 263 syslog(LOG_ERR, "chroot: %s: %m", chroot_dir); 264 exit(1); 265 } 266 chdir( "/" ); 267 setuid(nobody->pw_uid); 268 setgroups(1, &nobody->pw_gid); 269 } 270 271 len = sizeof(me); 272 if (getsockname(0, (struct sockaddr *)&me, &len) == 0) { 273 switch (me.ss_family) { 274 case AF_INET: 275 ((struct sockaddr_in *)&me)->sin_port = 0; 276 break; 277 case AF_INET6: 278 ((struct sockaddr_in6 *)&me)->sin6_port = 0; 279 break; 280 default: 281 /* unsupported */ 282 break; 283 } 284 } else { 285 memset(&me, 0, sizeof(me)); 286 me.ss_family = from.ss_family; 287 me.ss_len = from.ss_len; 288 } 289 alarm(0); 290 close(0); 291 close(1); 292 peer = socket(from.ss_family, SOCK_DGRAM, 0); 293 if (peer < 0) { 294 syslog(LOG_ERR, "socket: %m"); 295 exit(1); 296 } 297 if (bind(peer, (struct sockaddr *)&me, me.ss_len) < 0) { 298 syslog(LOG_ERR, "bind: %m"); 299 exit(1); 300 } 301 if (connect(peer, (struct sockaddr *)&from, from.ss_len) < 0) { 302 syslog(LOG_ERR, "connect: %m"); 303 exit(1); 304 } 305 tp = (struct tftphdr *)buf; 306 tp->th_opcode = ntohs(tp->th_opcode); 307 if (tp->th_opcode == RRQ || tp->th_opcode == WRQ) 308 tftp(tp, n); 309 exit(1); 310 } 311 312 struct formats; 313 int validate_access(char **, int); 314 void xmitfile(struct formats *); 315 void recvfile(struct formats *); 316 317 struct formats { 318 const char *f_mode; 319 int (*f_validate)(char **, int); 320 void (*f_send)(struct formats *); 321 void (*f_recv)(struct formats *); 322 int f_convert; 323 } formats[] = { 324 { "netascii", validate_access, xmitfile, recvfile, 1 }, 325 { "octet", validate_access, xmitfile, recvfile, 0 }, 326 #ifdef notdef 327 { "mail", validate_user, sendmail, recvmail, 1 }, 328 #endif 329 { 0, NULL, NULL, NULL, 0 } 330 }; 331 332 struct options { 333 const char *o_type; 334 char *o_request; 335 int o_reply; /* turn into union if need be */ 336 } options[] = { 337 { "tsize", NULL, 0 }, /* OPT_TSIZE */ 338 { "timeout", NULL, 0 }, /* OPT_TIMEOUT */ 339 { NULL, NULL, 0 } 340 }; 341 342 enum opt_enum { 343 OPT_TSIZE = 0, 344 OPT_TIMEOUT, 345 }; 346 347 /* 348 * Handle initial connection protocol. 349 */ 350 void 351 tftp(struct tftphdr *tp, int size) 352 { 353 char *cp; 354 int i, first = 1, has_options = 0, ecode; 355 struct formats *pf; 356 char *filename, *mode, *option, *ccp; 357 char fnbuf[MAXPATHLEN]; 358 359 cp = tp->th_stuff; 360 again: 361 while (cp < buf + size) { 362 if (*cp == '\0') 363 break; 364 cp++; 365 } 366 if (*cp != '\0') { 367 nak(EBADOP); 368 exit(1); 369 } 370 i = cp - tp->th_stuff; 371 if (i >= sizeof(fnbuf)) { 372 nak(EBADOP); 373 exit(1); 374 } 375 memcpy(fnbuf, tp->th_stuff, i); 376 fnbuf[i] = '\0'; 377 filename = fnbuf; 378 if (first) { 379 mode = ++cp; 380 first = 0; 381 goto again; 382 } 383 for (cp = mode; *cp; cp++) 384 if (isupper(*cp)) 385 *cp = tolower(*cp); 386 for (pf = formats; pf->f_mode; pf++) 387 if (strcmp(pf->f_mode, mode) == 0) 388 break; 389 if (pf->f_mode == 0) { 390 nak(EBADOP); 391 exit(1); 392 } 393 while (++cp < buf + size) { 394 for (i = 2, ccp = cp; i > 0; ccp++) { 395 if (ccp >= buf + size) { 396 /* 397 * Don't reject the request, just stop trying 398 * to parse the option and get on with it. 399 * Some Apple OpenFirmware versions have 400 * trailing garbage on the end of otherwise 401 * valid requests. 402 */ 403 goto option_fail; 404 } else if (*ccp == '\0') 405 i--; 406 } 407 for (option = cp; *cp; cp++) 408 if (isupper(*cp)) 409 *cp = tolower(*cp); 410 for (i = 0; options[i].o_type != NULL; i++) 411 if (strcmp(option, options[i].o_type) == 0) { 412 options[i].o_request = ++cp; 413 has_options = 1; 414 } 415 cp = ccp-1; 416 } 417 418 option_fail: 419 if (options[OPT_TIMEOUT].o_request) { 420 int to = atoi(options[OPT_TIMEOUT].o_request); 421 if (to < 1 || to > 255) { 422 nak(EBADOP); 423 exit(1); 424 } 425 else if (to <= max_rexmtval) 426 options[OPT_TIMEOUT].o_reply = rexmtval = to; 427 else 428 options[OPT_TIMEOUT].o_request = NULL; 429 } 430 431 ecode = (*pf->f_validate)(&filename, tp->th_opcode); 432 if (has_options) 433 oack(); 434 if (logging) { 435 char hbuf[NI_MAXHOST]; 436 437 getnameinfo((struct sockaddr *)&from, from.ss_len, 438 hbuf, sizeof(hbuf), NULL, 0, 439 NI_WITHSCOPEID); 440 syslog(LOG_INFO, "%s: %s request for %s: %s", hbuf, 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 * Note also, full path name must be 473 * given as we have no login directory. 474 */ 475 int 476 validate_access(char **filep, int mode) 477 { 478 struct stat stbuf; 479 int fd; 480 struct dirlist *dirp; 481 static char pathname[MAXPATHLEN]; 482 char *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 ((stbuf.st_mode & S_IFMT) != S_IFREG) 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 int err; 519 520 /* 521 * Relative file name: search the approved locations for it. 522 * Don't allow write requests that avoid directory 523 * restrictions. 524 */ 525 526 if (!strncmp(filename, "../", 3)) 527 return (EACCESS); 528 529 /* 530 * If the file exists in one of the directories and isn't 531 * readable, continue looking. However, change the error code 532 * to give an indication that the file exists. 533 */ 534 err = ENOTFOUND; 535 for (dirp = dirs; dirp->name != NULL; dirp++) { 536 snprintf(pathname, sizeof(pathname), "%s/%s", 537 dirp->name, filename); 538 if (stat(pathname, &stbuf) == 0 && 539 (stbuf.st_mode & S_IFMT) == S_IFREG) { 540 if ((stbuf.st_mode & S_IROTH) != 0) { 541 break; 542 } 543 err = EACCESS; 544 } 545 } 546 if (dirp->name == NULL) 547 return (err); 548 *filep = filename = pathname; 549 } 550 if (options[OPT_TSIZE].o_request) { 551 if (mode == RRQ) 552 options[OPT_TSIZE].o_reply = stbuf.st_size; 553 else 554 /* XXX Allows writes of all sizes. */ 555 options[OPT_TSIZE].o_reply = 556 atoi(options[OPT_TSIZE].o_request); 557 } 558 fd = open(filename, mode == RRQ ? O_RDONLY : O_WRONLY|O_TRUNC); 559 if (fd < 0) 560 return (errno + 100); 561 file = fdopen(fd, (mode == RRQ)? "r":"w"); 562 if (file == NULL) { 563 return errno+100; 564 } 565 return (0); 566 } 567 568 int timeouts; 569 jmp_buf timeoutbuf; 570 571 void 572 timer(int sig __unused) 573 { 574 if (++timeouts > MAX_TIMEOUTS) 575 exit(1); 576 longjmp(timeoutbuf, 1); 577 } 578 579 /* 580 * Send the requested file. 581 */ 582 void 583 xmitfile(struct formats *pf) 584 { 585 struct tftphdr *dp; 586 struct tftphdr *ap; /* ack packet */ 587 int size, n; 588 volatile unsigned short block; 589 590 signal(SIGALRM, timer); 591 dp = r_init(); 592 ap = (struct tftphdr *)ackbuf; 593 block = 1; 594 do { 595 size = readit(file, &dp, pf->f_convert); 596 if (size < 0) { 597 nak(errno + 100); 598 goto abort; 599 } 600 dp->th_opcode = htons((u_short)DATA); 601 dp->th_block = htons((u_short)block); 602 timeouts = 0; 603 (void)setjmp(timeoutbuf); 604 605 send_data: 606 { 607 int i, t = 1; 608 for (i = 0; ; i++){ 609 if (send(peer, dp, size + 4, 0) != size + 4) { 610 sleep(t); 611 t = (t < 32) ? t<< 1 : t; 612 if (i >= 12) { 613 syslog(LOG_ERR, "write: %m"); 614 goto abort; 615 } 616 } 617 break; 618 } 619 } 620 read_ahead(file, pf->f_convert); 621 for ( ; ; ) { 622 alarm(rexmtval); /* read the ack */ 623 n = recv(peer, ackbuf, sizeof (ackbuf), 0); 624 alarm(0); 625 if (n < 0) { 626 syslog(LOG_ERR, "read: %m"); 627 goto abort; 628 } 629 ap->th_opcode = ntohs((u_short)ap->th_opcode); 630 ap->th_block = ntohs((u_short)ap->th_block); 631 632 if (ap->th_opcode == ERROR) 633 goto abort; 634 635 if (ap->th_opcode == ACK) { 636 if (ap->th_block == block) 637 break; 638 /* Re-synchronize with the other side */ 639 (void) synchnet(peer); 640 if (ap->th_block == (block -1)) 641 goto send_data; 642 } 643 644 } 645 block++; 646 } while (size == SEGSIZE); 647 abort: 648 (void) fclose(file); 649 } 650 651 void 652 justquit(int sig __unused) 653 { 654 exit(0); 655 } 656 657 658 /* 659 * Receive a file. 660 */ 661 void 662 recvfile(struct formats *pf) 663 { 664 struct tftphdr *dp; 665 struct tftphdr *ap; /* ack buffer */ 666 int n, size; 667 volatile unsigned short block; 668 669 signal(SIGALRM, timer); 670 dp = w_init(); 671 ap = (struct tftphdr *)ackbuf; 672 block = 0; 673 do { 674 timeouts = 0; 675 ap->th_opcode = htons((u_short)ACK); 676 ap->th_block = htons((u_short)block); 677 block++; 678 (void) setjmp(timeoutbuf); 679 send_ack: 680 if (send(peer, ackbuf, 4, 0) != 4) { 681 syslog(LOG_ERR, "write: %m"); 682 goto abort; 683 } 684 write_behind(file, pf->f_convert); 685 for ( ; ; ) { 686 alarm(rexmtval); 687 n = recv(peer, dp, PKTSIZE, 0); 688 alarm(0); 689 if (n < 0) { /* really? */ 690 syslog(LOG_ERR, "read: %m"); 691 goto abort; 692 } 693 dp->th_opcode = ntohs((u_short)dp->th_opcode); 694 dp->th_block = ntohs((u_short)dp->th_block); 695 if (dp->th_opcode == ERROR) 696 goto abort; 697 if (dp->th_opcode == DATA) { 698 if (dp->th_block == block) { 699 break; /* normal */ 700 } 701 /* Re-synchronize with the other side */ 702 (void) synchnet(peer); 703 if (dp->th_block == (block-1)) 704 goto send_ack; /* rexmit */ 705 } 706 } 707 /* size = write(file, dp->th_data, n - 4); */ 708 size = writeit(file, &dp, n - 4, pf->f_convert); 709 if (size != (n-4)) { /* ahem */ 710 if (size < 0) nak(errno + 100); 711 else nak(ENOSPACE); 712 goto abort; 713 } 714 } while (size == SEGSIZE); 715 write_behind(file, pf->f_convert); 716 (void) fclose(file); /* close data file */ 717 718 ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */ 719 ap->th_block = htons((u_short)(block)); 720 (void) send(peer, ackbuf, 4, 0); 721 722 signal(SIGALRM, justquit); /* just quit on timeout */ 723 alarm(rexmtval); 724 n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */ 725 alarm(0); 726 if (n >= 4 && /* if read some data */ 727 dp->th_opcode == DATA && /* and got a data block */ 728 block == dp->th_block) { /* then my last ack was lost */ 729 (void) send(peer, ackbuf, 4, 0); /* resend final ack */ 730 } 731 abort: 732 return; 733 } 734 735 struct errmsg { 736 int e_code; 737 const char *e_msg; 738 } errmsgs[] = { 739 { EUNDEF, "Undefined error code" }, 740 { ENOTFOUND, "File not found" }, 741 { EACCESS, "Access violation" }, 742 { ENOSPACE, "Disk full or allocation exceeded" }, 743 { EBADOP, "Illegal TFTP operation" }, 744 { EBADID, "Unknown transfer ID" }, 745 { EEXISTS, "File already exists" }, 746 { ENOUSER, "No such user" }, 747 { EOPTNEG, "Option negotiation" }, 748 { -1, 0 } 749 }; 750 751 static const char * 752 errtomsg(int error) 753 { 754 static char ebuf[20]; 755 struct errmsg *pe; 756 if (error == 0) 757 return "success"; 758 for (pe = errmsgs; pe->e_code >= 0; pe++) 759 if (pe->e_code == error) 760 return pe->e_msg; 761 snprintf(ebuf, sizeof(buf), "error %d", error); 762 return ebuf; 763 } 764 765 /* 766 * Send a nak packet (error message). 767 * Error code passed in is one of the 768 * standard TFTP codes, or a UNIX errno 769 * offset by 100. 770 */ 771 static void 772 nak(int error) 773 { 774 struct tftphdr *tp; 775 int length; 776 struct errmsg *pe; 777 778 tp = (struct tftphdr *)buf; 779 tp->th_opcode = htons((u_short)ERROR); 780 tp->th_code = htons((u_short)error); 781 for (pe = errmsgs; pe->e_code >= 0; pe++) 782 if (pe->e_code == error) 783 break; 784 if (pe->e_code < 0) { 785 pe->e_msg = strerror(error - 100); 786 tp->th_code = EUNDEF; /* set 'undef' errorcode */ 787 } 788 strcpy(tp->th_msg, pe->e_msg); 789 length = strlen(pe->e_msg); 790 tp->th_msg[length] = '\0'; 791 length += 5; 792 if (send(peer, buf, length, 0) != length) 793 syslog(LOG_ERR, "nak: %m"); 794 } 795 796 /* translate IPv4 mapped IPv6 address to IPv4 address */ 797 static void 798 unmappedaddr(struct sockaddr_in6 *sin6) 799 { 800 struct sockaddr_in *sin4; 801 u_int32_t addr; 802 int port; 803 804 if (sin6->sin6_family != AF_INET6 || 805 !IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) 806 return; 807 sin4 = (struct sockaddr_in *)sin6; 808 addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12]; 809 port = sin6->sin6_port; 810 memset(sin4, 0, sizeof(struct sockaddr_in)); 811 sin4->sin_addr.s_addr = addr; 812 sin4->sin_port = port; 813 sin4->sin_family = AF_INET; 814 sin4->sin_len = sizeof(struct sockaddr_in); 815 } 816 817 /* 818 * Send an oack packet (option acknowledgement). 819 */ 820 static void 821 oack(void) 822 { 823 struct tftphdr *tp, *ap; 824 int size, i, n; 825 char *bp; 826 827 tp = (struct tftphdr *)buf; 828 bp = buf + 2; 829 size = sizeof(buf) - 2; 830 tp->th_opcode = htons((u_short)OACK); 831 for (i = 0; options[i].o_type != NULL; i++) { 832 if (options[i].o_request) { 833 n = snprintf(bp, size, "%s%c%d", options[i].o_type, 834 0, options[i].o_reply); 835 bp += n+1; 836 size -= n+1; 837 if (size < 0) { 838 syslog(LOG_ERR, "oack: buffer overflow"); 839 exit(1); 840 } 841 } 842 } 843 size = bp - buf; 844 ap = (struct tftphdr *)ackbuf; 845 signal(SIGALRM, timer); 846 timeouts = 0; 847 848 (void)setjmp(timeoutbuf); 849 if (send(peer, buf, size, 0) != size) { 850 syslog(LOG_INFO, "oack: %m"); 851 exit(1); 852 } 853 854 for (;;) { 855 alarm(rexmtval); 856 n = recv(peer, ackbuf, sizeof (ackbuf), 0); 857 alarm(0); 858 if (n < 0) { 859 syslog(LOG_ERR, "recv: %m"); 860 exit(1); 861 } 862 ap->th_opcode = ntohs((u_short)ap->th_opcode); 863 ap->th_block = ntohs((u_short)ap->th_block); 864 if (ap->th_opcode == ERROR) 865 exit(1); 866 if (ap->th_opcode == ACK && ap->th_block == 0) 867 break; 868 } 869 } 870