busybox/networking/tftp.c

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/* vi: set sw=4 ts=4: */
/* -------------------------------------------------------------------------
* tftp.c
*
* A simple tftp client for busybox.
* Tries to follow RFC1350.
* Only "octet" mode supported.
* Optional blocksize negotiation (RFC2347 + RFC2348)
*
* Copyright (C) 2001 Magnus Damm <damm@opensource.se>
*
* Parts of the code based on:
*
* atftp: Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
* and Remi Lefebvre <remi@debian.org>
*
* utftp: Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
* ------------------------------------------------------------------------- */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include "busybox.h"
#define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
#define TFTP_TIMEOUT 5 /* seconds */
#define TFTP_NUM_RETRIES 5 /* number of retries */
static const char * const MODE_OCTET = "octet";
#define MODE_OCTET_LEN 6 /* sizeof(MODE_OCTET)*/
static const char * const OPTION_BLOCKSIZE = "blksize";
#define OPTION_BLOCKSIZE_LEN 8 /* sizeof(OPTION_BLOCKSIZE) */
/* opcodes we support */
#define TFTP_RRQ 1
#define TFTP_WRQ 2
#define TFTP_DATA 3
#define TFTP_ACK 4
#define TFTP_ERROR 5
#define TFTP_OACK 6
static const char *const tftp_bb_error_msg[] = {
"Undefined error",
"File not found",
"Access violation",
"Disk full or allocation error",
"Illegal TFTP operation",
"Unknown transfer ID",
"File already exists",
"No such user"
};
#define tftp_cmd_get ENABLE_FEATURE_TFTP_GET
#if ENABLE_FEATURE_TFTP_PUT
# define tftp_cmd_put (tftp_cmd_get+ENABLE_FEATURE_TFTP_PUT)
#else
# define tftp_cmd_put 0
#endif
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#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
static int tftp_blocksize_check(int blocksize, int bufsize)
{
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/* Check if the blocksize is valid:
* RFC2348 says between 8 and 65464,
* but our implementation makes it impossible
* to use blocksizes smaller than 22 octets.
*/
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if ((bufsize && (blocksize > bufsize)) ||
(blocksize < 8) || (blocksize > 65564)) {
bb_error_msg("bad blocksize");
return 0;
}
return blocksize;
}
static char *tftp_option_get(char *buf, int len, const char * const option)
{
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int opt_val = 0;
int opt_found = 0;
int k;
while (len > 0) {
/* Make sure the options are terminated correctly */
for (k = 0; k < len; k++) {
if (buf[k] == '\0') {
break;
}
}
if (k >= len) {
break;
}
if (opt_val == 0) {
if (strcasecmp(buf, option) == 0) {
opt_found = 1;
}
} else {
if (opt_found) {
return buf;
}
}
k++;
buf += k;
len -= k;
opt_val ^= 1;
}
return NULL;
}
#endif
static int tftp(const int cmd, const struct hostent *host,
const char *remotefile, const int localfd,
const unsigned short port, int tftp_bufsize)
{
struct sockaddr_in sa;
struct sockaddr_in from;
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struct timeval tv;
socklen_t fromlen;
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fd_set rfds;
int socketfd;
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int len;
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int opcode = 0;
int finished = 0;
int timeout = TFTP_NUM_RETRIES;
unsigned short block_nr = 1;
unsigned short tmp;
char *cp;
USE_FEATURE_TFTP_BLOCKSIZE(int want_option_ack = 0;)
/* Can't use RESERVE_CONFIG_BUFFER here since the allocation
* size varies meaning BUFFERS_GO_ON_STACK would fail */
char *buf=xmalloc(tftp_bufsize += 4);
if ((socketfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
/* need to unlink the localfile, so don't use bb_xsocket here. */
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bb_perror_msg("socket");
return EXIT_FAILURE;
}
len = sizeof(sa);
memset(&sa, 0, len);
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bb_xbind(socketfd, (struct sockaddr *)&sa, len);
sa.sin_family = host->h_addrtype;
sa.sin_port = port;
memcpy(&sa.sin_addr, (struct in_addr *) host->h_addr,
sizeof(sa.sin_addr));
/* build opcode */
if (cmd & tftp_cmd_get) {
opcode = TFTP_RRQ;
}
if (cmd & tftp_cmd_put) {
opcode = TFTP_WRQ;
}
while (1) {
cp = buf;
/* first create the opcode part */
*((unsigned short *) cp) = htons(opcode);
cp += 2;
/* add filename and mode */
if (((cmd & tftp_cmd_get) && (opcode == TFTP_RRQ)) ||
((cmd & tftp_cmd_put) && (opcode == TFTP_WRQ)))
{
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int too_long = 0;
/* see if the filename fits into buf
* and fill in packet. */
len = strlen(remotefile) + 1;
if ((cp + len) >= &buf[tftp_bufsize - 1]) {
too_long = 1;
} else {
safe_strncpy(cp, remotefile, len);
cp += len;
}
if (too_long || ((&buf[tftp_bufsize - 1] - cp) < MODE_OCTET_LEN)) {
bb_error_msg("remote filename too long");
break;
}
/* add "mode" part of the package */
memcpy(cp, MODE_OCTET, MODE_OCTET_LEN);
cp += MODE_OCTET_LEN;
#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
len = tftp_bufsize - 4; /* data block size */
if (len != TFTP_BLOCKSIZE_DEFAULT) {
if ((&buf[tftp_bufsize - 1] - cp) < 15) {
bb_error_msg("remote filename too long");
break;
}
/* add "blksize" + number of blocks */
memcpy(cp, OPTION_BLOCKSIZE, OPTION_BLOCKSIZE_LEN);
cp += OPTION_BLOCKSIZE_LEN;
cp += snprintf(cp, 6, "%d", len) + 1;
want_option_ack = 1;
}
#endif
}
/* add ack and data */
if (((cmd & tftp_cmd_get) && (opcode == TFTP_ACK)) ||
((cmd & tftp_cmd_put) && (opcode == TFTP_DATA))) {
*((unsigned short *) cp) = htons(block_nr);
cp += 2;
block_nr++;
if ((cmd & tftp_cmd_put) && (opcode == TFTP_DATA)) {
len = full_read(localfd, cp, tftp_bufsize - 4);
if (len < 0) {
bb_perror_msg(bb_msg_read_error);
break;
}
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if (len != (tftp_bufsize - 4)) {
finished++;
}
cp += len;
}
}
/* send packet */
timeout = TFTP_NUM_RETRIES; /* re-initialize */
do {
len = cp - buf;
#ifdef CONFIG_DEBUG_TFTP
fprintf(stderr, "sending %u bytes\n", len);
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for (cp = buf; cp < &buf[len]; cp++)
fprintf(stderr, "%02x ", (unsigned char) *cp);
fprintf(stderr, "\n");
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#endif
if (sendto(socketfd, buf, len, 0,
(struct sockaddr *) &sa, sizeof(sa)) < 0) {
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bb_perror_msg("send");
len = -1;
break;
}
if (finished && (opcode == TFTP_ACK)) {
break;
}
/* receive packet */
memset(&from, 0, sizeof(from));
fromlen = sizeof(from);
tv.tv_sec = TFTP_TIMEOUT;
tv.tv_usec = 0;
FD_ZERO(&rfds);
FD_SET(socketfd, &rfds);
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switch (select(socketfd + 1, &rfds, NULL, NULL, &tv)) {
case 1:
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len = recvfrom(socketfd, buf, tftp_bufsize, 0,
(struct sockaddr *) &from, &fromlen);
if (len < 0) {
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bb_perror_msg("recvfrom");
break;
}
timeout = 0;
if (sa.sin_port == port) {
sa.sin_port = from.sin_port;
}
if (sa.sin_port == from.sin_port) {
break;
}
/* fall-through for bad packets! */
/* discard the packet - treat as timeout */
timeout = TFTP_NUM_RETRIES;
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case 0:
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bb_error_msg("timeout");
timeout--;
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if (timeout == 0) {
len = -1;
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bb_error_msg("last timeout");
}
break;
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default:
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bb_perror_msg("select");
len = -1;
}
} while (timeout && (len >= 0));
if ((finished) || (len < 0)) {
break;
}
/* process received packet */
opcode = ntohs(*((unsigned short *) buf));
tmp = ntohs(*((unsigned short *) &buf[2]));
#ifdef CONFIG_DEBUG_TFTP
fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, tmp);
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#endif
if (opcode == TFTP_ERROR) {
const char *msg = NULL;
if (buf[4] != '\0') {
msg = &buf[4];
buf[tftp_bufsize - 1] = '\0';
} else if (tmp < (sizeof(tftp_bb_error_msg)
/ sizeof(char *))) {
msg = tftp_bb_error_msg[tmp];
}
if (msg) {
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bb_error_msg("server says: %s", msg);
}
break;
}
#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
if (want_option_ack) {
want_option_ack = 0;
if (opcode == TFTP_OACK) {
/* server seems to support options */
char *res;
res = tftp_option_get(&buf[2], len - 2, OPTION_BLOCKSIZE);
if (res) {
int blksize = atoi(res);
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if (tftp_blocksize_check(blksize, tftp_bufsize - 4)) {
if (cmd & tftp_cmd_put) {
opcode = TFTP_DATA;
} else {
opcode = TFTP_ACK;
}
#ifdef CONFIG_DEBUG_TFTP
fprintf(stderr, "using %s %u\n", OPTION_BLOCKSIZE,
blksize);
#endif
tftp_bufsize = blksize + 4;
block_nr = 0;
continue;
}
}
/* FIXME:
* we should send ERROR 8 */
bb_error_msg("bad server option");
break;
}
bb_error_msg("warning: blksize not supported by server"
" - reverting to 512");
tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4;
}
#endif
if ((cmd & tftp_cmd_get) && (opcode == TFTP_DATA)) {
if (tmp == block_nr) {
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len = full_write(localfd, &buf[4], len - 4);
if (len < 0) {
bb_perror_msg(bb_msg_write_error);
break;
}
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if (len != (tftp_bufsize - 4)) {
finished++;
}
opcode = TFTP_ACK;
continue;
}
/* in case the last ack disappeared into the ether */
if (tmp == (block_nr - 1)) {
--block_nr;
opcode = TFTP_ACK;
continue;
} else if (tmp + 1 == block_nr) {
/* Server lost our TFTP_ACK. Resend it */
block_nr = tmp;
opcode = TFTP_ACK;
continue;
}
}
if ((cmd & tftp_cmd_put) && (opcode == TFTP_ACK)) {
if (tmp == (unsigned short) (block_nr - 1)) {
if (finished) {
break;
}
opcode = TFTP_DATA;
continue;
}
}
}
#ifdef CONFIG_FEATURE_CLEAN_UP
close(socketfd);
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free(buf);
#endif
return finished ? EXIT_SUCCESS : EXIT_FAILURE;
}
int tftp_main(int argc, char **argv)
{
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struct hostent *host = NULL;
const char *localfile = NULL;
const char *remotefile = NULL;
int port;
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int cmd = 0;
int fd = -1;
int flags = 0;
int result;
int blocksize = TFTP_BLOCKSIZE_DEFAULT;
/* figure out what to pass to getopt */
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#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
char *sblocksize = NULL;
#define BS "b:"
#define BS_ARG , &sblocksize
#else
#define BS
#define BS_ARG
#endif
#ifdef CONFIG_FEATURE_TFTP_GET
#define GET "g"
#define GET_COMPL ":g"
#else
#define GET
#define GET_COMPL
#endif
#ifdef CONFIG_FEATURE_TFTP_PUT
#define PUT "p"
#define PUT_COMPL ":p"
#else
#define PUT
#define PUT_COMPL
#endif
#if defined(CONFIG_FEATURE_TFTP_GET) && defined(CONFIG_FEATURE_TFTP_PUT)
bb_opt_complementally = GET_COMPL PUT_COMPL ":?g--p:p--g";
#elif defined(CONFIG_FEATURE_TFTP_GET) || defined(CONFIG_FEATURE_TFTP_PUT)
bb_opt_complementally = GET_COMPL PUT_COMPL;
#endif
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cmd = bb_getopt_ulflags(argc, argv, GET PUT "l:r:" BS,
&localfile, &remotefile BS_ARG);
cmd &= (tftp_cmd_get | tftp_cmd_put);
#ifdef CONFIG_FEATURE_TFTP_GET
if (cmd == tftp_cmd_get)
flags = O_WRONLY | O_CREAT | O_TRUNC;
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#endif
#ifdef CONFIG_FEATURE_TFTP_PUT
if (cmd == tftp_cmd_put)
flags = O_RDONLY;
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#endif
#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
if (sblocksize) {
blocksize = atoi(sblocksize);
if (!tftp_blocksize_check(blocksize, 0)) {
return EXIT_FAILURE;
}
}
#endif
if (localfile == NULL)
localfile = remotefile;
if (remotefile == NULL)
remotefile = localfile;
if ((localfile == NULL && remotefile == NULL) || (argv[optind] == NULL))
bb_show_usage();
if (localfile == NULL || strcmp(localfile, "-") == 0) {
fd = (cmd == tftp_cmd_get) ? STDOUT_FILENO : STDIN_FILENO;
} else {
fd = open(localfile, flags, 0644); /* fail below */
}
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if (fd < 0) {
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bb_perror_msg_and_die("local file");
}
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host = xgethostbyname(argv[optind]);
port = bb_lookup_port(argv[optind + 1], "udp", 69);
#ifdef CONFIG_DEBUG_TFTP
fprintf(stderr, "using server \"%s\", remotefile \"%s\", "
"localfile \"%s\".\n",
inet_ntoa(*((struct in_addr *) host->h_addr)),
remotefile, localfile);
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#endif
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result = tftp(cmd, host, remotefile, fd, port, blocksize);
if (!(fd == STDOUT_FILENO || fd == STDIN_FILENO)) {
if (ENABLE_FEATURE_CLEAN_UP)
close(fd);
if (cmd == tftp_cmd_get && result != EXIT_SUCCESS)
unlink(localfile);
}
return (result);
}