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 "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 */
/* 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"
};
#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
#define USE_GETPUT(a)
#define CMD_GET(cmd) 1
#define CMD_PUT(cmd) 0
#elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
#define USE_GETPUT(a)
#define CMD_GET(cmd) 0
#define CMD_PUT(cmd) 1
#else
#define USE_GETPUT(a) a
/* masks coming from getpot32 */
#define CMD_GET(cmd) (cmd & 1)
#define CMD_PUT(cmd) (cmd & 2)
#endif
/* NB: in the code below
* CMD_GET(cmd) and CMD_GET(cmd) are mutually exclusive
*/
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#if ENABLE_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.
*/
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(
#if ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
const int cmd,
#endif
const len_and_sockaddr *peer_lsa,
const char *remotefile, const int localfd,
unsigned port, int tftp_bufsize)
{
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struct timeval tv;
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;
uint16_t block_nr = 1;
uint16_t 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 */
/* We must keep the transmit and receive buffers seperate */
/* In case we rcv a garbage pkt and we need to rexmit the last pkt */
char *xbuf = xmalloc(tftp_bufsize += 4);
char *rbuf = xmalloc(tftp_bufsize);
port = htons(port);
socketfd = xsocket(peer_lsa->sa.sa_family, SOCK_DGRAM, 0);
/* build opcode */
opcode = TFTP_WRQ;
if (CMD_GET(cmd)) {
opcode = TFTP_RRQ;
}
while (1) {
cp = xbuf;
/* first create the opcode part */
*((uint16_t*)cp) = htons(opcode);
cp += 2;
/* add filename and mode */
if (CMD_GET(cmd) ? (opcode == TFTP_RRQ) : (opcode == TFTP_WRQ)) {
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int too_long = 0;
/* see if the filename fits into xbuf
* and fill in packet. */
len = strlen(remotefile) + 1;
if ((cp + len) >= &xbuf[tftp_bufsize - 1]) {
too_long = 1;
} else {
safe_strncpy(cp, remotefile, len);
cp += len;
}
if (too_long || (&xbuf[tftp_bufsize - 1] - cp) < sizeof("octet")) {
bb_error_msg("remote filename too long");
break;
}
/* add "mode" part of the package */
memcpy(cp, "octet", sizeof("octet"));
cp += sizeof("octet");
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
len = tftp_bufsize - 4; /* data block size */
if (len != TFTP_BLOCKSIZE_DEFAULT) {
if ((&xbuf[tftp_bufsize - 1] - cp) < 15) {
bb_error_msg("remote filename too long");
break;
}
/* add "blksize" + number of blocks */
memcpy(cp, "blksize", sizeof("blksize"));
cp += sizeof("blksize");
cp += snprintf(cp, 6, "%d", len) + 1;
want_option_ack = 1;
}
#endif
}
/* add ack and data */
if (CMD_GET(cmd) ? (opcode == TFTP_ACK) : (opcode == TFTP_DATA)) {
*((uint16_t*)cp) = htons(block_nr);
cp += 2;
block_nr++;
if (CMD_PUT(cmd) && (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 - xbuf;
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "sending %u bytes\n", len);
for (cp = xbuf; cp < &xbuf[len]; cp++)
fprintf(stderr, "%02x ", (unsigned char) *cp);
fprintf(stderr, "\n");
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#endif
if (sendto(socketfd, xbuf, len, 0,
&peer_lsa->sa, peer_lsa->len) < 0) {
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bb_perror_msg("send");
len = -1;
break;
}
if (finished && (opcode == TFTP_ACK)) {
break;
}
/* receive packet */
recv_again:
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)) {
struct sockaddr *from;
socklen_t fromlen;
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case 1:
fromlen = peer_lsa->len;
from = alloca(fromlen);
memset(from, 0, fromlen);
len = recvfrom(socketfd, rbuf, tftp_bufsize, 0,
from, &fromlen);
if (len < 0) {
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bb_perror_msg("recvfrom");
break;
}
#if ENABLE_FEATURE_IPV6
if (from->sa_family == AF_INET6)
if (((struct sockaddr_in6*)from)->sin6_port != port)
goto recv_again;
#endif
if (from->sa_family == AF_INET)
if (((struct sockaddr_in*)from)->sin_port != port)
goto recv_again;
timeout = 0;
break;
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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( ((uint16_t*)rbuf)[0] );
tmp = ntohs( ((uint16_t*)rbuf)[1] );
#if ENABLE_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 (rbuf[4] != '\0') {
msg = &rbuf[4];
rbuf[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;
}
#if ENABLE_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(&rbuf[2], len - 2, "blksize");
if (res) {
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int blksize = xatoi_u(res);
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if (tftp_blocksize_check(blksize, tftp_bufsize - 4)) {
if (CMD_PUT(cmd)) {
opcode = TFTP_DATA;
} else {
opcode = TFTP_ACK;
}
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "using blksize %u\n",
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_GET(cmd) && (opcode == TFTP_DATA)) {
if (tmp == block_nr) {
len = full_write(localfd, &rbuf[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;
// tmp==(block_nr-1) and (tmp+1)==block_nr is always same, I think. wtf?
} else if (tmp + 1 == block_nr) {
/* Server lost our TFTP_ACK. Resend it */
block_nr = tmp;
opcode = TFTP_ACK;
continue;
}
}
if (CMD_PUT(cmd) && (opcode == TFTP_ACK)) {
if (tmp == (uint16_t) (block_nr - 1)) {
if (finished) {
break;
}
opcode = TFTP_DATA;
continue;
}
}
}
if (ENABLE_FEATURE_CLEAN_UP) {
close(socketfd);
free(xbuf);
free(rbuf);
}
return finished ? EXIT_SUCCESS : EXIT_FAILURE;
}
int tftp_main(int argc, char **argv)
{
len_and_sockaddr *peer_lsa;
const char *localfile = NULL;
const char *remotefile = NULL;
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
const char *sblocksize = NULL;
#endif
int port;
USE_GETPUT(int cmd;)
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int fd = -1;
int flags = 0;
int result;
int blocksize = TFTP_BLOCKSIZE_DEFAULT;
/* -p or -g is mandatory, and they are mutually exclusive */
opt_complementary = "" USE_FEATURE_TFTP_GET("g:") USE_FEATURE_TFTP_PUT("p:")
USE_GETPUT("?g--p:p--g");
USE_GETPUT(cmd =) getopt32(argc, argv,
USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
"l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
&localfile, &remotefile
USE_FEATURE_TFTP_BLOCKSIZE(, &sblocksize));
flags = O_RDONLY;
if (CMD_GET(cmd))
flags = O_WRONLY | O_CREAT | O_TRUNC;
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (sblocksize) {
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blocksize = xatoi_u(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 || LONE_DASH(localfile)) {
fd = CMD_GET(cmd) ? STDOUT_FILENO : STDIN_FILENO;
} else {
fd = xopen3(localfile, flags, 0644);
}
port = bb_lookup_port(argv[optind + 1], "udp", 69);
peer_lsa = host2sockaddr(argv[optind], port);
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "using server \"%s\", "
"remotefile \"%s\", localfile \"%s\".\n",
xmalloc_sockaddr2dotted(&peer_lsa->sa, peer_lsa->len),
remotefile, localfile);
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#endif
result = tftp(
#if ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
cmd,
#endif
peer_lsa, remotefile, fd, port, blocksize);
if (fd > 1) {
if (ENABLE_FEATURE_CLEAN_UP)
close(fd);
if (CMD_GET(cmd) && result != EXIT_SUCCESS)
unlink(localfile);
}
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return result;
}