mirror of
https://github.com/sheumann/hush.git
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461 lines
12 KiB
C
461 lines
12 KiB
C
/* vi: set sw=4 ts=4: */
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/* -------------------------------------------------------------------------
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* tftp.c
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*
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* A simple tftp client for busybox.
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* Tries to follow RFC1350.
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* Only "octet" mode supported.
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* Optional blocksize negotiation (RFC2347 + RFC2348)
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*
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* Copyright (C) 2001 Magnus Damm <damm@opensource.se>
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*
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* Parts of the code based on:
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*
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* atftp: Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
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* and Remi Lefebvre <remi@debian.org>
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*
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* utftp: Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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* ------------------------------------------------------------------------- */
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#include "libbb.h"
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#if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
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#define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
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#define TFTP_TIMEOUT 5 /* seconds */
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#define TFTP_NUM_RETRIES 5 /* number of retries */
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/* opcodes we support */
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#define TFTP_RRQ 1
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#define TFTP_WRQ 2
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#define TFTP_DATA 3
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#define TFTP_ACK 4
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#define TFTP_ERROR 5
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#define TFTP_OACK 6
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#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
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#define USE_GETPUT(...)
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#define CMD_GET(cmd) 1
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#define CMD_PUT(cmd) 0
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#elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
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#define USE_GETPUT(...)
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#define CMD_GET(cmd) 0
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#define CMD_PUT(cmd) 1
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#else
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#define USE_GETPUT(...) __VA_ARGS__
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/* masks coming from getpot32 */
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#define CMD_GET(cmd) ((cmd) & 1)
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#define CMD_PUT(cmd) ((cmd) & 2)
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#endif
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/* NB: in the code below
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* CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
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*/
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#if ENABLE_FEATURE_TFTP_BLOCKSIZE
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static int tftp_blocksize_check(int blocksize, int bufsize)
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{
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/* Check if the blocksize is valid:
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* RFC2348 says between 8 and 65464,
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* but our implementation makes it impossible
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* to use blocksizes smaller than 22 octets.
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*/
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if ((bufsize && (blocksize > bufsize))
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|| (blocksize < 8) || (blocksize > 65564)
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) {
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bb_error_msg("bad blocksize");
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return 0;
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}
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return blocksize;
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}
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static char *tftp_option_get(char *buf, int len, const char *option)
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{
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int opt_val = 0;
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int opt_found = 0;
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int k;
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while (len > 0) {
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/* Make sure the options are terminated correctly */
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for (k = 0; k < len; k++) {
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if (buf[k] == '\0') {
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goto nul_found;
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}
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}
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return NULL;
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nul_found:
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if (opt_val == 0) {
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if (strcasecmp(buf, option) == 0) {
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opt_found = 1;
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}
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} else if (opt_found) {
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return buf;
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}
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k++;
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buf += k;
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len -= k;
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opt_val ^= 1;
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}
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return NULL;
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}
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#endif
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static int tftp( USE_GETPUT(const int cmd,)
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len_and_sockaddr *peer_lsa,
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const char *remotefile, const int localfd,
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unsigned port, int tftp_bufsize)
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{
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struct timeval tv;
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fd_set rfds;
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int socketfd;
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int len;
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int send_len;
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USE_FEATURE_TFTP_BLOCKSIZE(smallint want_option_ack = 0;)
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smallint finished = 0;
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uint16_t opcode;
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uint16_t block_nr = 1;
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uint16_t recv_blk;
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int timeout = TFTP_NUM_RETRIES;
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char *cp;
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unsigned org_port;
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len_and_sockaddr *const from = alloca(offsetof(len_and_sockaddr, sa) + peer_lsa->len);
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/* Can't use RESERVE_CONFIG_BUFFER here since the allocation
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* size varies meaning BUFFERS_GO_ON_STACK would fail */
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/* We must keep the transmit and receive buffers seperate */
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/* In case we rcv a garbage pkt and we need to rexmit the last pkt */
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char *xbuf = xmalloc(tftp_bufsize += 4);
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char *rbuf = xmalloc(tftp_bufsize);
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port = org_port = htons(port);
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socketfd = xsocket(peer_lsa->sa.sa_family, SOCK_DGRAM, 0);
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/* build opcode */
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opcode = TFTP_WRQ;
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if (CMD_GET(cmd)) {
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opcode = TFTP_RRQ;
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}
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cp = xbuf + 2;
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/* add filename and mode */
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/* fill in packet if the filename fits into xbuf */
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len = strlen(remotefile) + 1;
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if (2 + len + sizeof("octet") >= tftp_bufsize) {
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bb_error_msg("remote filename is too long");
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goto ret;
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}
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strcpy(cp, remotefile);
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cp += len;
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/* add "mode" part of the package */
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strcpy(cp, "octet");
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cp += sizeof("octet");
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#if ENABLE_FEATURE_TFTP_BLOCKSIZE
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len = tftp_bufsize - 4; /* data block size */
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if (len != TFTP_BLOCKSIZE_DEFAULT) {
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/* rfc2348 says that 65464 is a max allowed value */
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if ((&xbuf[tftp_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
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bb_error_msg("remote filename is too long");
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goto ret;
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}
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/* add "blksize", <nul>, blocksize */
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strcpy(cp, "blksize");
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cp += sizeof("blksize");
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cp += snprintf(cp, 6, "%d", len) + 1;
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want_option_ack = 1;
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}
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#endif
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/* First packet is built, so skip packet generation */
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goto send_pkt;
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/* Using mostly goto's - continue/break will be less clear
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* in where we actually jump to */
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while (1) {
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/* Build ACK or DATA */
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cp = xbuf + 2;
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*((uint16_t*)cp) = htons(block_nr);
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cp += 2;
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block_nr++;
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opcode = TFTP_ACK;
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if (CMD_PUT(cmd)) {
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opcode = TFTP_DATA;
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len = full_read(localfd, cp, tftp_bufsize - 4);
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if (len < 0) {
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bb_perror_msg(bb_msg_read_error);
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goto ret;
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}
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if (len != (tftp_bufsize - 4)) {
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finished = 1;
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}
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cp += len;
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}
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send_pkt:
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/* Send packet */
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*((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
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send_len = cp - xbuf;
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/* NB: send_len value is preserved in code below
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* for potential resend */
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send_again:
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#if ENABLE_DEBUG_TFTP
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fprintf(stderr, "sending %u bytes\n", send_len);
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for (cp = xbuf; cp < &xbuf[send_len]; cp++)
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fprintf(stderr, "%02x ", (unsigned char) *cp);
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fprintf(stderr, "\n");
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#endif
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xsendto(socketfd, xbuf, send_len, &peer_lsa->sa, peer_lsa->len);
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/* Was it final ACK? then exit */
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if (finished && (opcode == TFTP_ACK))
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goto ret;
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timeout = TFTP_NUM_RETRIES; /* re-initialize */
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recv_again:
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/* Receive packet */
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tv.tv_sec = TFTP_TIMEOUT;
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tv.tv_usec = 0;
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FD_ZERO(&rfds);
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FD_SET(socketfd, &rfds);
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switch (select(socketfd + 1, &rfds, NULL, NULL, &tv)) {
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unsigned from_port;
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case 1:
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from->len = peer_lsa->len;
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memset(&from->sa, 0, peer_lsa->len);
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len = recvfrom(socketfd, rbuf, tftp_bufsize, 0,
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&from->sa, &from->len);
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if (len < 0) {
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bb_perror_msg("recvfrom");
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goto ret;
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}
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from_port = get_nport(&from->sa);
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if (port == org_port) {
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/* Our first query went to port 69
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* but reply will come from different one.
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* Remember and use this new port */
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port = from_port;
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set_nport(peer_lsa, from_port);
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}
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if (port != from_port)
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goto recv_again;
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goto process_pkt;
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case 0:
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timeout--;
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if (timeout == 0) {
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bb_error_msg("last timeout");
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goto ret;
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}
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bb_error_msg("last timeout" + 5);
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goto send_again; /* resend last sent pkt */
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default:
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bb_perror_msg("select");
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goto ret;
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}
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process_pkt:
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/* Process recv'ed packet */
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opcode = ntohs( ((uint16_t*)rbuf)[0] );
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recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
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#if ENABLE_DEBUG_TFTP
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fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
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#endif
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if (opcode == TFTP_ERROR) {
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static const char *const errcode_str[] = {
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"",
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"file not found",
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"access violation",
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"disk full",
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"illegal TFTP operation",
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"unknown transfer id",
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"file already exists",
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"no such user",
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"bad option",
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};
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const char *msg = "";
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if (rbuf[4] != '\0') {
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msg = &rbuf[4];
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rbuf[tftp_bufsize - 1] = '\0';
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} else if (recv_blk < ARRAY_SIZE(errcode_str)) {
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msg = errcode_str[recv_blk];
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}
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bb_error_msg("server error: (%u) %s", recv_blk, msg);
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goto ret;
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}
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#if ENABLE_FEATURE_TFTP_BLOCKSIZE
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if (want_option_ack) {
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want_option_ack = 0;
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if (opcode == TFTP_OACK) {
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/* server seems to support options */
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char *res;
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res = tftp_option_get(&rbuf[2], len - 2, "blksize");
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if (res) {
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int blksize = xatoi_u(res);
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if (!tftp_blocksize_check(blksize, tftp_bufsize - 4)) {
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/* send ERROR 8 to server... */
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/* htons can be impossible to use in const initializer: */
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/*static const uint16_t error_8[2] = { htons(TFTP_ERROR), htons(8) };*/
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/* thus we open-code big-endian layout */
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static const char error_8[4] = { 0,TFTP_ERROR, 0,8 };
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xsendto(socketfd, error_8, 4, &peer_lsa->sa, peer_lsa->len);
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bb_error_msg("server proposes bad blksize %d, exiting", blksize);
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goto ret;
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}
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#if ENABLE_DEBUG_TFTP
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fprintf(stderr, "using blksize %u\n",
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blksize);
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#endif
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tftp_bufsize = blksize + 4;
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/* Send ACK for OACK ("block" no: 0) */
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block_nr = 0;
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continue;
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}
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/* rfc2347:
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* "An option not acknowledged by the server
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* must be ignored by the client and server
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* as if it were never requested." */
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}
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bb_error_msg("blksize is not supported by server"
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" - reverting to 512");
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tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4;
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}
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#endif
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/* block_nr is already advanced to next block# we expect
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* to get / block# we are about to send next time */
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if (CMD_GET(cmd) && (opcode == TFTP_DATA)) {
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if (recv_blk == block_nr) {
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len = full_write(localfd, &rbuf[4], len - 4);
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if (len < 0) {
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bb_perror_msg(bb_msg_write_error);
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goto ret;
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}
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if (len != (tftp_bufsize - 4)) {
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finished = 1;
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}
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continue; /* send ACK */
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}
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if (recv_blk == (block_nr - 1)) {
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/* Server lost our TFTP_ACK. Resend it */
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block_nr = recv_blk;
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continue;
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}
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}
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if (CMD_PUT(cmd) && (opcode == TFTP_ACK)) {
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/* did server ACK our last DATA pkt? */
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if (recv_blk == (uint16_t) (block_nr - 1)) {
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if (finished)
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goto ret;
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continue; /* send next block */
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}
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}
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/* Awww... recv'd packet is not recognized! */
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goto recv_again;
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/* why recv_again? - rfc1123 says:
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* "The sender (i.e., the side originating the DATA packets)
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* must never resend the current DATA packet on receipt
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* of a duplicate ACK".
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* DATA pkts are resent ONLY on timeout.
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* Thus "goto send_again" will ba a bad mistake above.
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* See:
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* http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
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*/
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}
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ret:
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if (ENABLE_FEATURE_CLEAN_UP) {
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close(socketfd);
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free(xbuf);
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free(rbuf);
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}
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return finished == 0; /* returns 1 on failure */
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}
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int tftp_main(int argc, char **argv);
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int tftp_main(int argc, char **argv)
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{
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len_and_sockaddr *peer_lsa;
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const char *localfile = NULL;
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const char *remotefile = NULL;
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#if ENABLE_FEATURE_TFTP_BLOCKSIZE
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const char *sblocksize = NULL;
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#endif
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int port;
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USE_GETPUT(int cmd;)
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int fd = -1;
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int flags = 0;
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int result;
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int blocksize = TFTP_BLOCKSIZE_DEFAULT;
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/* -p or -g is mandatory, and they are mutually exclusive */
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opt_complementary = "" USE_FEATURE_TFTP_GET("g:") USE_FEATURE_TFTP_PUT("p:")
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USE_GETPUT("?g--p:p--g");
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USE_GETPUT(cmd =) getopt32(argc, argv,
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USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
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"l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
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&localfile, &remotefile
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USE_FEATURE_TFTP_BLOCKSIZE(, &sblocksize));
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argv += optind;
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flags = O_RDONLY;
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if (CMD_GET(cmd))
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flags = O_WRONLY | O_CREAT | O_TRUNC;
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#if ENABLE_FEATURE_TFTP_BLOCKSIZE
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if (sblocksize) {
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blocksize = xatoi_u(sblocksize);
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if (!tftp_blocksize_check(blocksize, 0)) {
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return EXIT_FAILURE;
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}
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}
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#endif
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if (!localfile)
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localfile = remotefile;
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if (!remotefile)
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remotefile = localfile;
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/* Error if filename or host is not known */
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if (!remotefile || !argv[0])
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bb_show_usage();
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fd = CMD_GET(cmd) ? STDOUT_FILENO : STDIN_FILENO;
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if (!LONE_DASH(localfile)) {
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fd = xopen(localfile, flags);
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}
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port = bb_lookup_port(argv[1], "udp", 69);
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peer_lsa = xhost2sockaddr(argv[0], port);
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#if ENABLE_DEBUG_TFTP
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fprintf(stderr, "using server '%s', remotefile '%s', localfile '%s'\n",
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xmalloc_sockaddr2dotted(&peer_lsa->sa, peer_lsa->len),
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remotefile, localfile);
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#endif
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result = tftp( USE_GETPUT(cmd,) peer_lsa, remotefile, fd, port, blocksize);
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if (ENABLE_FEATURE_CLEAN_UP)
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close(fd);
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if (result != EXIT_SUCCESS && !LONE_DASH(localfile) && CMD_GET(cmd)) {
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unlink(localfile);
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}
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return result;
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}
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#endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */
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