1 /* 2 * Copyright (c) 1983 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #ifndef lint 8 char copyright[] = 9 "@(#) Copyright (c) 1983 Regents of the University of California.\n\ 10 All rights reserved.\n"; 11 #endif not lint 12 13 #ifndef lint 14 static char sccsid[] = "@(#)tftpd.c 5.4 (Berkeley) 02/07/86"; 15 #endif not lint 16 17 18 /* 19 * Trivial file transfer protocol server. 20 * 21 * This version includes many modifications by Jim Guyton <guyton@rand-unix> 22 */ 23 24 #include <sys/types.h> 25 #include <sys/socket.h> 26 #include <sys/ioctl.h> 27 #include <sys/wait.h> 28 #include <sys/stat.h> 29 30 #include <netinet/in.h> 31 32 #include <arpa/tftp.h> 33 34 #include <signal.h> 35 #include <stdio.h> 36 #include <errno.h> 37 #include <ctype.h> 38 #include <netdb.h> 39 #include <setjmp.h> 40 #include <syslog.h> 41 42 #define TIMEOUT 5 43 44 extern int errno; 45 struct sockaddr_in sin = { AF_INET }; 46 int peer; 47 int rexmtval = TIMEOUT; 48 int maxtimeout = 5*TIMEOUT; 49 50 #define PKTSIZE SEGSIZE+4 51 char buf[PKTSIZE]; 52 char ackbuf[PKTSIZE]; 53 struct sockaddr_in from; 54 int fromlen; 55 56 main() 57 { 58 register struct tftphdr *tp; 59 register int n; 60 61 openlog("tftpd", LOG_PID, LOG_DAEMON); 62 alarm(10); 63 fromlen = sizeof (from); 64 n = recvfrom(0, buf, sizeof (buf), 0, 65 (caddr_t)&from, &fromlen); 66 if (n < 0) { 67 perror("tftpd: recvfrom"); 68 exit(1); 69 } 70 from.sin_family = AF_INET; 71 alarm(0); 72 close(0); 73 close(1); 74 peer = socket(AF_INET, SOCK_DGRAM, 0); 75 if (peer < 0) { 76 syslog(LOG_ERR, "socket: %m"); 77 exit(1); 78 } 79 if (bind(peer, (caddr_t)&sin, sizeof (sin)) < 0) { 80 syslog(LOG_ERR, "bind: %m"); 81 exit(1); 82 } 83 if (connect(peer, (caddr_t)&from, sizeof(from)) < 0) { 84 syslog(LOG_ERR, "connect: %m"); 85 exit(1); 86 } 87 tp = (struct tftphdr *)buf; 88 tp->th_opcode = ntohs(tp->th_opcode); 89 if (tp->th_opcode == RRQ || tp->th_opcode == WRQ) 90 tftp(tp, n); 91 exit(1); 92 } 93 94 int validate_access(); 95 int sendfile(), recvfile(); 96 97 struct formats { 98 char *f_mode; 99 int (*f_validate)(); 100 int (*f_send)(); 101 int (*f_recv)(); 102 int f_convert; 103 } formats[] = { 104 { "netascii", validate_access, sendfile, recvfile, 1 }, 105 { "octet", validate_access, sendfile, recvfile, 0 }, 106 #ifdef notdef 107 { "mail", validate_user, sendmail, recvmail, 1 }, 108 #endif 109 { 0 } 110 }; 111 112 /* 113 * Handle initial connection protocol. 114 */ 115 tftp(tp, size) 116 struct tftphdr *tp; 117 int size; 118 { 119 register char *cp; 120 int first = 1, ecode; 121 register struct formats *pf; 122 char *filename, *mode; 123 124 filename = cp = tp->th_stuff; 125 again: 126 while (cp < buf + size) { 127 if (*cp == '\0') 128 break; 129 cp++; 130 } 131 if (*cp != '\0') { 132 nak(EBADOP); 133 exit(1); 134 } 135 if (first) { 136 mode = ++cp; 137 first = 0; 138 goto again; 139 } 140 for (cp = mode; *cp; cp++) 141 if (isupper(*cp)) 142 *cp = tolower(*cp); 143 for (pf = formats; pf->f_mode; pf++) 144 if (strcmp(pf->f_mode, mode) == 0) 145 break; 146 if (pf->f_mode == 0) { 147 nak(EBADOP); 148 exit(1); 149 } 150 ecode = (*pf->f_validate)(filename, tp->th_opcode); 151 if (ecode) { 152 nak(ecode); 153 exit(1); 154 } 155 if (tp->th_opcode == WRQ) 156 (*pf->f_recv)(pf); 157 else 158 (*pf->f_send)(pf); 159 exit(0); 160 } 161 162 163 FILE *file; 164 165 /* 166 * Validate file access. Since we 167 * have no uid or gid, for now require 168 * file to exist and be publicly 169 * readable/writable. 170 * Note also, full path name must be 171 * given as we have no login directory. 172 */ 173 validate_access(filename, mode) 174 char *filename; 175 int mode; 176 { 177 struct stat stbuf; 178 int fd; 179 180 if (*filename != '/') 181 return (EACCESS); 182 if (stat(filename, &stbuf) < 0) 183 return (errno == ENOENT ? ENOTFOUND : EACCESS); 184 if (mode == RRQ) { 185 if ((stbuf.st_mode&(S_IREAD >> 6)) == 0) 186 return (EACCESS); 187 } else { 188 if ((stbuf.st_mode&(S_IWRITE >> 6)) == 0) 189 return (EACCESS); 190 } 191 fd = open(filename, mode == RRQ ? 0 : 1); 192 if (fd < 0) 193 return (errno + 100); 194 file = fdopen(fd, (mode == RRQ)? "r":"w"); 195 if (file == NULL) { 196 return errno+100; 197 } 198 return (0); 199 } 200 201 int timeout; 202 jmp_buf timeoutbuf; 203 204 timer() 205 { 206 207 timeout += rexmtval; 208 if (timeout >= maxtimeout) 209 exit(1); 210 longjmp(timeoutbuf, 1); 211 } 212 213 /* 214 * Send the requested file. 215 */ 216 sendfile(pf) 217 struct formats *pf; 218 { 219 struct tftphdr *dp, *r_init(); 220 register struct tftphdr *ap; /* ack packet */ 221 register int block = 1, size, n; 222 223 signal(SIGALRM, timer); 224 dp = r_init(); 225 ap = (struct tftphdr *)ackbuf; 226 do { 227 size = readit(file, &dp, pf->f_convert); 228 if (size < 0) { 229 nak(errno + 100); 230 goto abort; 231 } 232 dp->th_opcode = htons((u_short)DATA); 233 dp->th_block = htons((u_short)block); 234 timeout = 0; 235 (void) setjmp(timeoutbuf); 236 237 send_data: 238 /* Now, we flush anything pending to be read */ 239 /* This is to try to keep in synch between the two sides */ 240 while (1) { 241 int i; 242 char rbuf[PKTSIZE]; 243 244 (void) ioctl(peer, FIONREAD, &i); 245 if (i) { 246 fromlen = sizeof from; 247 n = recvfrom(peer, rbuf, sizeof (rbuf), 0, 248 (caddr_t)&from, &fromlen); 249 } else { 250 break; 251 } 252 } 253 if (send(peer, dp, size + 4, 0) != size + 4) { 254 perror("tftpd: write"); 255 goto abort; 256 } 257 read_ahead(file, pf->f_convert); 258 for ( ; ; ) { 259 alarm(rexmtval); /* read the ack */ 260 n = recv(peer, ackbuf, sizeof (ackbuf), 0); 261 alarm(0); 262 if (n < 0) { 263 perror("tftpd: read"); 264 goto abort; 265 } 266 ap->th_opcode = ntohs((u_short)ap->th_opcode); 267 ap->th_block = ntohs((u_short)ap->th_block); 268 269 if (ap->th_opcode == ERROR) 270 goto abort; 271 272 if (ap->th_opcode == ACK) { 273 if (ap->th_block == block) { 274 break; 275 } 276 if (ap->th_block == (block -1)) { 277 goto send_data; 278 } 279 } 280 281 } 282 block++; 283 } while (size == SEGSIZE); 284 abort: 285 (void) fclose(file); 286 } 287 288 justquit() 289 { 290 exit(0); 291 } 292 293 294 /* 295 * Receive a file. 296 */ 297 recvfile(pf) 298 struct formats *pf; 299 { 300 struct tftphdr *dp, *w_init(); 301 register struct tftphdr *ap; /* ack buffer */ 302 register int block = 0, n, size; 303 304 signal(SIGALRM, timer); 305 dp = w_init(); 306 ap = (struct tftphdr *)ackbuf; 307 do { 308 timeout = 0; 309 ap->th_opcode = htons((u_short)ACK); 310 ap->th_block = htons((u_short)block); 311 block++; 312 (void) setjmp(timeoutbuf); 313 send_ack: 314 /* Now, we flush anything pending to be read */ 315 /* This is to try to keep in synch between the two sides */ 316 while (1) { 317 int i; 318 char rbuf[PKTSIZE]; 319 320 (void) ioctl(peer, FIONREAD, &i); 321 if (i) { 322 fromlen = sizeof from; 323 n = recvfrom(peer, rbuf, sizeof (rbuf), 0, 324 (caddr_t)&from, &fromlen); 325 } else { 326 break; 327 } 328 } 329 if (send(peer, ackbuf, 4, 0) != 4) { 330 perror("tftpd: write"); 331 goto abort; 332 } 333 write_behind(file, pf->f_convert); 334 for ( ; ; ) { 335 alarm(rexmtval); 336 n = recv(peer, dp, PKTSIZE, 0); 337 alarm(0); 338 if (n < 0) { /* really? */ 339 perror("tftpd: read"); 340 goto abort; 341 } 342 dp->th_opcode = ntohs((u_short)dp->th_opcode); 343 dp->th_block = ntohs((u_short)dp->th_block); 344 if (dp->th_opcode == ERROR) 345 goto abort; 346 if (dp->th_opcode == DATA) { 347 if (dp->th_block == block) { 348 break; /* normal */ 349 } 350 if (dp->th_block == (block-1)) 351 goto send_ack; /* rexmit */ 352 } 353 } 354 /* size = write(file, dp->th_data, n - 4); */ 355 size = writeit(file, &dp, n - 4, pf->f_convert); 356 if (size != (n-4)) { /* ahem */ 357 if (size < 0) nak(errno + 100); 358 else nak(ENOSPACE); 359 goto abort; 360 } 361 } while (size == SEGSIZE); 362 write_behind(file, pf->f_convert); 363 (void) fclose(file); /* close data file */ 364 365 ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */ 366 ap->th_block = htons((u_short)(block)); 367 (void) send(peer, ackbuf, 4, 0); 368 369 signal(SIGALRM, justquit); /* just quit on timeout */ 370 alarm(rexmtval); 371 n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */ 372 alarm(0); 373 if (n >= 4 && /* if read some data */ 374 dp->th_opcode == DATA && /* and got a data block */ 375 block == dp->th_block) { /* then my last ack was lost */ 376 (void) send(peer, ackbuf, 4, 0); /* resend final ack */ 377 } 378 abort: 379 return; 380 } 381 382 struct errmsg { 383 int e_code; 384 char *e_msg; 385 } errmsgs[] = { 386 { EUNDEF, "Undefined error code" }, 387 { ENOTFOUND, "File not found" }, 388 { EACCESS, "Access violation" }, 389 { ENOSPACE, "Disk full or allocation exceeded" }, 390 { EBADOP, "Illegal TFTP operation" }, 391 { EBADID, "Unknown transfer ID" }, 392 { EEXISTS, "File already exists" }, 393 { ENOUSER, "No such user" }, 394 { -1, 0 } 395 }; 396 397 /* 398 * Send a nak packet (error message). 399 * Error code passed in is one of the 400 * standard TFTP codes, or a UNIX errno 401 * offset by 100. 402 */ 403 nak(error) 404 int error; 405 { 406 register struct tftphdr *tp; 407 int length; 408 register struct errmsg *pe; 409 extern char *sys_errlist[]; 410 411 tp = (struct tftphdr *)buf; 412 tp->th_opcode = htons((u_short)ERROR); 413 tp->th_code = htons((u_short)error); 414 for (pe = errmsgs; pe->e_code >= 0; pe++) 415 if (pe->e_code == error) 416 break; 417 if (pe->e_code < 0) { 418 pe->e_msg = sys_errlist[error - 100]; 419 tp->th_code = EUNDEF; /* set 'undef' errorcode */ 420 } 421 strcpy(tp->th_msg, pe->e_msg); 422 length = strlen(pe->e_msg); 423 tp->th_msg[length] = '\0'; 424 length += 5; 425 if (send(peer, buf, length, 0) != length) 426 perror("nak"); 427 } 428