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 5.3 (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 if (send(peer, dp, size + 4, 0) != size + 4) { 238 perror("tftpd: write"); 239 goto abort; 240 } 241 read_ahead(file, pf->f_convert); 242 do { 243 alarm(rexmtval); /* read the ack */ 244 n = recv(peer, ackbuf, sizeof (ackbuf), 0); 245 alarm(0); 246 if (n < 0) { 247 perror("tftpd: read"); 248 goto abort; 249 } 250 ap->th_opcode = ntohs((u_short)ap->th_opcode); 251 ap->th_block = ntohs((u_short)ap->th_block); 252 253 if (ap->th_opcode == ERROR) 254 goto abort; 255 256 } while (ap->th_opcode != ACK || ap->th_block != block); 257 block++; 258 } while (size == SEGSIZE); 259 abort: 260 (void) fclose(file); 261 } 262 263 justquit() 264 { 265 exit(0); 266 } 267 268 269 /* 270 * Receive a file. 271 */ 272 recvfile(pf) 273 struct formats *pf; 274 { 275 struct tftphdr *dp, *w_init(); 276 register struct tftphdr *ap; /* ack buffer */ 277 register int block = 0, n, size; 278 279 signal(SIGALRM, timer); 280 dp = w_init(); 281 ap = (struct tftphdr *)ackbuf; 282 do { 283 timeout = 0; 284 ap->th_opcode = htons((u_short)ACK); 285 ap->th_block = htons((u_short)block); 286 block++; 287 (void) setjmp(timeoutbuf); 288 send_ack: 289 if (send(peer, ackbuf, 4, 0) != 4) { 290 perror("tftpd: write"); 291 goto abort; 292 } 293 write_behind(file, pf->f_convert); 294 for ( ; ; ) { 295 alarm(rexmtval); 296 n = recv(peer, dp, PKTSIZE, 0); 297 alarm(0); 298 if (n < 0) { /* really? */ 299 perror("tftpd: read"); 300 goto abort; 301 } 302 dp->th_opcode = ntohs((u_short)dp->th_opcode); 303 dp->th_block = ntohs((u_short)dp->th_block); 304 if (dp->th_opcode == ERROR) 305 goto abort; 306 if (dp->th_opcode == DATA) { 307 if (dp->th_block == block) { 308 break; /* normal */ 309 } 310 if (dp->th_block == (block-1)) 311 goto send_ack; /* rexmit */ 312 } 313 } 314 /* size = write(file, dp->th_data, n - 4); */ 315 size = writeit(file, &dp, n - 4, pf->f_convert); 316 if (size != (n-4)) { /* ahem */ 317 if (size < 0) nak(errno + 100); 318 else nak(ENOSPACE); 319 goto abort; 320 } 321 } while (size == SEGSIZE); 322 write_behind(file, pf->f_convert); 323 (void) fclose(file); /* close data file */ 324 325 ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */ 326 ap->th_block = htons((u_short)(block)); 327 (void) send(peer, ackbuf, 4, 0); 328 329 signal(SIGALRM, justquit); /* just quit on timeout */ 330 alarm(rexmtval); 331 n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */ 332 alarm(0); 333 if (n >= 4 && /* if read some data */ 334 dp->th_opcode == DATA && /* and got a data block */ 335 block == dp->th_block) { /* then my last ack was lost */ 336 (void) send(peer, ackbuf, 4, 0); /* resend final ack */ 337 } 338 abort: 339 return; 340 } 341 342 struct errmsg { 343 int e_code; 344 char *e_msg; 345 } errmsgs[] = { 346 { EUNDEF, "Undefined error code" }, 347 { ENOTFOUND, "File not found" }, 348 { EACCESS, "Access violation" }, 349 { ENOSPACE, "Disk full or allocation exceeded" }, 350 { EBADOP, "Illegal TFTP operation" }, 351 { EBADID, "Unknown transfer ID" }, 352 { EEXISTS, "File already exists" }, 353 { ENOUSER, "No such user" }, 354 { -1, 0 } 355 }; 356 357 /* 358 * Send a nak packet (error message). 359 * Error code passed in is one of the 360 * standard TFTP codes, or a UNIX errno 361 * offset by 100. 362 */ 363 nak(error) 364 int error; 365 { 366 register struct tftphdr *tp; 367 int length; 368 register struct errmsg *pe; 369 extern char *sys_errlist[]; 370 371 tp = (struct tftphdr *)buf; 372 tp->th_opcode = htons((u_short)ERROR); 373 tp->th_code = htons((u_short)error); 374 for (pe = errmsgs; pe->e_code >= 0; pe++) 375 if (pe->e_code == error) 376 break; 377 if (pe->e_code < 0) { 378 pe->e_msg = sys_errlist[error - 100]; 379 tp->th_code = EUNDEF; /* set 'undef' errorcode */ 380 } 381 strcpy(tp->th_msg, pe->e_msg); 382 length = strlen(pe->e_msg); 383 tp->th_msg[length] = '\0'; 384 length += 5; 385 if (send(peer, buf, length, 0) != length) 386 perror("nak"); 387 } 388