tftp: explain "block# 0" codepath; report our decision to bail out to server
if blocksize option doesn't look good (it was a FIXME. +33 bytes code); make code more readable.
This commit is contained in:
Denis Vlasenko
parent
a035e9f1a9
commit
bf678d5423
@ -37,15 +37,15 @@
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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(a)
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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(a)
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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(a) a
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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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@ -109,10 +109,7 @@ static char *tftp_option_get(char *buf, int len, const char *option)
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#endif
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static int tftp(
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#if ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
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const int cmd,
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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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@ -181,6 +178,9 @@ static int tftp(
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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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@ -203,67 +203,64 @@ static int tftp(
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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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timeout = TFTP_NUM_RETRIES; /* re-initialize */
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while (1) {
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send_len = cp - xbuf;
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/* nb: need to preserve send_len value in code below
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* for potential resend! */
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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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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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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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/* Receive packet */
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timeout = TFTP_NUM_RETRIES; /* re-initialize */
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recv_again:
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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 recvd_good;
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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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/* 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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} /* while we don't see recv packet with correct port# */
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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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recvd_good:
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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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@ -281,9 +278,9 @@ static int tftp(
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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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enum { NUM_ERRCODE = sizeof(errcode_str) / sizeof(errcode_str[0]) };
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const char *msg = "";
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if (rbuf[4] != '\0') {
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@ -308,8 +305,13 @@ static int tftp(
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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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// FIXME: must also send ERROR 8 to server...
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goto ret;
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}
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#if ENABLE_DEBUG_TFTP
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@ -317,7 +319,8 @@ static int tftp(
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blksize);
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#endif
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tftp_bufsize = blksize + 4;
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block_nr = 0; // TODO: explain why???
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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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@ -430,9 +433,8 @@ int tftp_main(int argc, char **argv)
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if (!remotefile || !argv[0])
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bb_show_usage();
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if (LONE_DASH(localfile)) {
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fd = CMD_GET(cmd) ? STDOUT_FILENO : STDIN_FILENO;
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} else {
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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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@ -440,17 +442,12 @@ int tftp_main(int argc, char **argv)
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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\", "
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"remotefile \"%s\", localfile \"%s\"\n",
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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(
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#if ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
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cmd,
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#endif
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peer_lsa, remotefile, fd, port, blocksize);
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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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