[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit

Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/app/busybox/src/networking/tftp.c b/ap/app/busybox/src/networking/tftp.c
new file mode 100644
index 0000000..630fdaf
--- /dev/null
+++ b/ap/app/busybox/src/networking/tftp.c
@@ -0,0 +1,879 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * A simple tftp client/server 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>
+ *
+ * tftpd added by Denys Vlasenko & Vladimir Dronnikov
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+//usage:#define tftp_trivial_usage
+//usage:       "[OPTIONS] HOST [PORT]"
+//usage:#define tftp_full_usage "\n\n"
+//usage:       "Transfer a file from/to tftp server\n"
+//usage:     "\n	-l FILE	Local FILE"
+//usage:     "\n	-r FILE	Remote FILE"
+//usage:	IF_FEATURE_TFTP_GET(
+//usage:     "\n	-g	Get file"
+//usage:	)
+//usage:	IF_FEATURE_TFTP_PUT(
+//usage:     "\n	-p	Put file"
+//usage:	)
+//usage:	IF_FEATURE_TFTP_BLOCKSIZE(
+//usage:     "\n	-b SIZE	Transfer blocks of SIZE octets"
+//usage:	)
+//usage:
+//usage:#define tftpd_trivial_usage
+//usage:       "[-cr] [-u USER] [DIR]"
+//usage:#define tftpd_full_usage "\n\n"
+//usage:       "Transfer a file on tftp client's request\n"
+//usage:       "\n"
+//usage:       "tftpd should be used as an inetd service.\n"
+//usage:       "tftpd's line for inetd.conf:\n"
+//usage:       "	69 dgram udp nowait root tftpd tftpd -l /files/to/serve\n"
+//usage:       "It also can be ran from udpsvd:\n"
+//usage:       "	udpsvd -vE 0.0.0.0 69 tftpd /files/to/serve\n"
+//usage:     "\n	-r	Prohibit upload"
+//usage:     "\n	-c	Allow file creation via upload"
+//usage:     "\n	-u	Access files as USER"
+//usage:     "\n	-l	Log to syslog (inetd mode requires this)"
+
+#include "libbb.h"
+#include <syslog.h>
+
+#if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
+
+#define TFTP_BLKSIZE_DEFAULT       512  /* according to RFC 1350, don't change */
+#define TFTP_BLKSIZE_DEFAULT_STR "512"
+/* Was 50 ms but users asked to bump it up a bit */
+#define TFTP_TIMEOUT_MS            100
+#define TFTP_MAXTIMEOUT_MS        2000
+#define TFTP_NUM_RETRIES            12  /* number of backed-off 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
+
+/* error codes sent over network (we use only 0, 1, 3 and 8) */
+/* generic (error message is included in the packet) */
+#define ERR_UNSPEC   0
+#define ERR_NOFILE   1
+#define ERR_ACCESS   2
+/* disk full or allocation exceeded */
+#define ERR_WRITE    3
+#define ERR_OP       4
+#define ERR_BAD_ID   5
+#define ERR_EXIST    6
+#define ERR_BAD_USER 7
+#define ERR_BAD_OPT  8
+
+/* masks coming from getopt32 */
+enum {
+	TFTP_OPT_GET = (1 << 0),
+	TFTP_OPT_PUT = (1 << 1),
+	/* pseudo option: if set, it's tftpd */
+	TFTPD_OPT = (1 << 7) * ENABLE_TFTPD,
+	TFTPD_OPT_r = (1 << 8) * ENABLE_TFTPD,
+	TFTPD_OPT_c = (1 << 9) * ENABLE_TFTPD,
+	TFTPD_OPT_u = (1 << 10) * ENABLE_TFTPD,
+	TFTPD_OPT_l = (1 << 11) * ENABLE_TFTPD,
+};
+
+#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
+#define IF_GETPUT(...)
+#define CMD_GET(cmd) 1
+#define CMD_PUT(cmd) 0
+#elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
+#define IF_GETPUT(...)
+#define CMD_GET(cmd) 0
+#define CMD_PUT(cmd) 1
+#else
+#define IF_GETPUT(...) __VA_ARGS__
+#define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
+#define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
+#endif
+/* NB: in the code below
+ * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
+ */
+
+
+struct globals {
+	/* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
+	uint8_t error_pkt[4 + 32];
+	struct passwd *pw;
+	/* used in tftpd_main(), a bit big for stack: */
+	char block_buf[TFTP_BLKSIZE_DEFAULT];
+#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+	off_t pos;
+	off_t size;
+	const char *file;
+	bb_progress_t pmt;
+#endif
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+struct BUG_G_too_big {
+	char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
+};
+#define INIT_G() do { } while (0)
+
+#define G_error_pkt_reason (G.error_pkt[3])
+#define G_error_pkt_str    ((char*)(G.error_pkt + 4))
+
+#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+static void tftp_progress_update(void)
+{
+	bb_progress_update(&G.pmt, 0, G.pos, G.size);
+}
+static void tftp_progress_init(void)
+{
+	bb_progress_init(&G.pmt, G.file);
+	tftp_progress_update();
+}
+static void tftp_progress_done(void)
+{
+	if (is_bb_progress_inited(&G.pmt)) {
+		tftp_progress_update();
+		bb_putchar_stderr('\n');
+		bb_progress_free(&G.pmt);
+	}
+}
+#else
+# define tftp_progress_init() ((void)0)
+# define tftp_progress_done() ((void)0)
+#endif
+
+#if ENABLE_FEATURE_TFTP_BLOCKSIZE
+
+static int tftp_blksize_check(const char *blksize_str, int maxsize)
+{
+	/* Check if the blksize is valid:
+	 * RFC2348 says between 8 and 65464,
+	 * but our implementation makes it impossible
+	 * to use blksizes smaller than 22 octets. */
+	unsigned blksize = bb_strtou(blksize_str, NULL, 10);
+	if (errno
+	 || (blksize < 24) || (blksize > maxsize)
+	) {
+		bb_error_msg("bad blocksize '%s'", blksize_str);
+		return -1;
+	}
+# if ENABLE_TFTP_DEBUG
+	bb_error_msg("using blksize %u", blksize);
+# endif
+	return blksize;
+}
+
+static char *tftp_get_option(const char *option, char *buf, int len)
+{
+	int opt_val = 0;
+	int opt_found = 0;
+	int k;
+
+	/* buf points to:
+	 * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */
+
+	while (len > 0) {
+		/* Make sure options are terminated correctly */
+		for (k = 0; k < len; k++) {
+			if (buf[k] == '\0') {
+				goto nul_found;
+			}
+		}
+		return NULL;
+ nul_found:
+		if (opt_val == 0) { /* it's "name" part */
+			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_protocol(
+		/* NULL if tftp, !NULL if tftpd: */
+		len_and_sockaddr *our_lsa,
+		len_and_sockaddr *peer_lsa,
+		const char *local_file
+		IF_TFTP(, const char *remote_file)
+#if !ENABLE_TFTP
+# define remote_file NULL
+#endif
+		/* 1 for tftp; 1/0 for tftpd depending whether client asked about it: */
+		IF_FEATURE_TFTP_BLOCKSIZE(, int want_transfer_size)
+		IF_FEATURE_TFTP_BLOCKSIZE(, int blksize))
+{
+#if !ENABLE_FEATURE_TFTP_BLOCKSIZE
+	enum { blksize = TFTP_BLKSIZE_DEFAULT };
+#endif
+
+	struct pollfd pfd[1];
+#define socket_fd (pfd[0].fd)
+	int len;
+	int send_len;
+	IF_FEATURE_TFTP_BLOCKSIZE(smallint expect_OACK = 0;)
+	smallint finished = 0;
+	uint16_t opcode;
+	uint16_t block_nr;
+	uint16_t recv_blk;
+	int open_mode, local_fd;
+	int retries, waittime_ms;
+	int io_bufsize = blksize + 4;
+	char *cp;
+	/* 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 separate
+	 * in case we rcv a garbage pkt - we need to rexmit the last pkt.
+	 */
+	char *xbuf = xmalloc(io_bufsize);
+	char *rbuf = xmalloc(io_bufsize);
+
+	socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
+	setsockopt_reuseaddr(socket_fd);
+
+	if (!ENABLE_TFTP || our_lsa) { /* tftpd */
+		/* Create a socket which is:
+		 * 1. bound to IP:port peer sent 1st datagram to,
+		 * 2. connected to peer's IP:port
+		 * This way we will answer from the IP:port peer
+		 * expects, will not get any other packets on
+		 * the socket, and also plain read/write will work. */
+		xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
+		xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
+
+		/* Is there an error already? Send pkt and bail out */
+		if (G_error_pkt_reason || G_error_pkt_str[0])
+			goto send_err_pkt;
+
+		if (G.pw) {
+			change_identity(G.pw); /* initgroups, setgid, setuid */
+		}
+	}
+
+	/* Prepare open mode */
+	if (CMD_PUT(option_mask32)) {
+		open_mode = O_RDONLY;
+	} else {
+		open_mode = O_WRONLY | O_TRUNC | O_CREAT;
+#if ENABLE_TFTPD
+		if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
+			/* tftpd without -c */
+			open_mode = O_WRONLY | O_TRUNC;
+		}
+#endif
+	}
+
+	/* Examples of network traffic.
+	 * Note two cases when ACKs with block# of 0 are sent.
+	 *
+	 * Download without options:
+	 * tftp -> "\0\1FILENAME\0octet\0"
+	 *         "\0\3\0\1FILEDATA..." <- tftpd
+	 * tftp -> "\0\4\0\1"
+	 * ...
+	 * Download with option of blksize 16384:
+	 * tftp -> "\0\1FILENAME\0octet\0blksize\00016384\0"
+	 *         "\0\6blksize\00016384\0" <- tftpd
+	 * tftp -> "\0\4\0\0"
+	 *         "\0\3\0\1FILEDATA..." <- tftpd
+	 * tftp -> "\0\4\0\1"
+	 * ...
+	 * Upload without options:
+	 * tftp -> "\0\2FILENAME\0octet\0"
+	 *         "\0\4\0\0" <- tftpd
+	 * tftp -> "\0\3\0\1FILEDATA..."
+	 *         "\0\4\0\1" <- tftpd
+	 * ...
+	 * Upload with option of blksize 16384:
+	 * tftp -> "\0\2FILENAME\0octet\0blksize\00016384\0"
+	 *         "\0\6blksize\00016384\0" <- tftpd
+	 * tftp -> "\0\3\0\1FILEDATA..."
+	 *         "\0\4\0\1" <- tftpd
+	 * ...
+	 */
+	block_nr = 1;
+	cp = xbuf + 2;
+
+	if (!ENABLE_TFTP || our_lsa) { /* tftpd */
+		/* Open file (must be after changing user) */
+		local_fd = open(local_file, open_mode, 0666);
+		if (local_fd < 0) {
+			G_error_pkt_reason = ERR_NOFILE;
+			strcpy(G_error_pkt_str, "can't open file");
+			goto send_err_pkt;
+		}
+/* gcc 4.3.1 would NOT optimize it out as it should! */
+#if ENABLE_FEATURE_TFTP_BLOCKSIZE
+		if (blksize != TFTP_BLKSIZE_DEFAULT || want_transfer_size) {
+			/* Create and send OACK packet. */
+			/* For the download case, block_nr is still 1 -
+			 * we expect 1st ACK from peer to be for (block_nr-1),
+			 * that is, for "block 0" which is our OACK pkt */
+			opcode = TFTP_OACK;
+			goto add_blksize_opt;
+		}
+#endif
+		if (CMD_GET(option_mask32)) {
+			/* It's upload and we don't send OACK.
+			 * We must ACK 1st packet (with filename)
+			 * as if it is "block 0" */
+			block_nr = 0;
+		}
+
+	} else { /* tftp */
+		/* Open file (must be after changing user) */
+		local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
+		if (NOT_LONE_DASH(local_file))
+			local_fd = xopen(local_file, open_mode);
+/* Removing #if, or using if() statement instead of #if may lead to
+ * "warning: null argument where non-null required": */
+#if ENABLE_TFTP
+		/* tftp */
+
+		/* We can't (and don't really need to) bind the socket:
+		 * we don't know from which local IP datagrams will be sent,
+		 * but kernel will pick the same IP every time (unless routing
+		 * table is changed), thus peer will see dgrams consistently
+		 * coming from the same IP.
+		 * We would like to connect the socket, but since peer's
+		 * UDP code can be less perfect than ours, _peer's_ IP:port
+		 * in replies may differ from IP:port we used to send
+		 * our first packet. We can connect() only when we get
+		 * first reply. */
+
+		/* build opcode */
+		opcode = TFTP_WRQ;
+		if (CMD_GET(option_mask32)) {
+			opcode = TFTP_RRQ;
+		}
+		/* add filename and mode */
+		/* fill in packet if the filename fits into xbuf */
+		len = strlen(remote_file) + 1;
+		if (2 + len + sizeof("octet") >= io_bufsize) {
+			bb_error_msg("remote filename is too long");
+			goto ret;
+		}
+		strcpy(cp, remote_file);
+		cp += len;
+		/* add "mode" part of the packet */
+		strcpy(cp, "octet");
+		cp += sizeof("octet");
+
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
+		if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
+			goto send_pkt;
+
+		/* Need to add option to pkt */
+		if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN tsize ") + sizeof(off_t)*3) {
+			bb_error_msg("remote filename is too long");
+			goto ret;
+		}
+		expect_OACK = 1;
+# endif
+#endif /* ENABLE_TFTP */
+
+#if ENABLE_FEATURE_TFTP_BLOCKSIZE
+ add_blksize_opt:
+		if (blksize != TFTP_BLKSIZE_DEFAULT) {
+			/* add "blksize", <nul>, blksize, <nul> */
+			strcpy(cp, "blksize");
+			cp += sizeof("blksize");
+			cp += snprintf(cp, 6, "%d", blksize) + 1;
+		}
+		if (want_transfer_size) {
+			/* add "tsize", <nul>, size, <nul> (see RFC2349) */
+			/* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
+			 * and this makes server to send "tsize" option with the size */
+			/* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
+			/* if tftpd and downloading, we are answering to client's request */
+			/* if tftpd and uploading: !want_transfer_size, this code is not executed */
+			struct stat st;
+			strcpy(cp, "tsize");
+			cp += sizeof("tsize");
+			st.st_size = 0;
+			fstat(local_fd, &st);
+			cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
+# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+			/* Save for progress bar. If 0 (tftp downloading),
+			 * we look at server's reply later */
+			G.size = st.st_size;
+			if (remote_file && st.st_size)
+				tftp_progress_init();
+# endif
+		}
+#endif
+		/* First packet is built, so skip packet generation */
+		goto send_pkt;
+	}
+
+	/* Using mostly goto's - continue/break will be less clear
+	 * in where we actually jump to */
+	while (1) {
+		/* Build ACK or DATA */
+		cp = xbuf + 2;
+		*((uint16_t*)cp) = htons(block_nr);
+		cp += 2;
+		block_nr++;
+		opcode = TFTP_ACK;
+		if (CMD_PUT(option_mask32)) {
+			opcode = TFTP_DATA;
+			len = full_read(local_fd, cp, blksize);
+			if (len < 0) {
+				goto send_read_err_pkt;
+			}
+			if (len != blksize) {
+				finished = 1;
+			}
+			cp += len;
+			IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += len;)
+		}
+ send_pkt:
+		/* Send packet */
+		*((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
+		send_len = cp - xbuf;
+		/* NB: send_len value is preserved in code below
+		 * for potential resend */
+
+		retries = TFTP_NUM_RETRIES;  /* re-initialize */
+		waittime_ms = TFTP_TIMEOUT_MS;
+
+ send_again:
+#if ENABLE_TFTP_DEBUG
+		fprintf(stderr, "sending %u bytes\n", send_len);
+		for (cp = xbuf; cp < &xbuf[send_len]; cp++)
+			fprintf(stderr, "%02x ", (unsigned char) *cp);
+		fprintf(stderr, "\n");
+#endif
+		xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);
+
+#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+		if (is_bb_progress_inited(&G.pmt))
+			tftp_progress_update();
+#endif
+		/* Was it final ACK? then exit */
+		if (finished && (opcode == TFTP_ACK))
+			goto ret;
+
+ recv_again:
+		/* Receive packet */
+		/*pfd[0].fd = socket_fd;*/
+		pfd[0].events = POLLIN;
+		switch (safe_poll(pfd, 1, waittime_ms)) {
+		default:
+			/*bb_perror_msg("poll"); - done in safe_poll */
+			goto ret;
+		case 0:
+			retries--;
+			if (retries == 0) {
+				tftp_progress_done();
+				bb_error_msg("timeout");
+				goto ret; /* no err packet sent */
+			}
+
+			/* exponential backoff with limit */
+			waittime_ms += waittime_ms/2;
+			if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
+				waittime_ms = TFTP_MAXTIMEOUT_MS;
+			}
+
+			goto send_again; /* resend last sent pkt */
+		case 1:
+			if (!our_lsa) {
+				/* tftp (not tftpd!) receiving 1st packet */
+				our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
+				len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
+						&peer_lsa->u.sa, &peer_lsa->len);
+				/* Our first dgram went to port 69
+				 * but reply may come from different one.
+				 * Remember and use this new port (and IP) */
+				if (len >= 0)
+					xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
+			} else {
+				/* tftpd, or not the very first packet:
+				 * socket is connect()ed, can just read from it. */
+				/* Don't full_read()!
+				 * This is not TCP, one read == one pkt! */
+				len = safe_read(socket_fd, rbuf, io_bufsize);
+			}
+			if (len < 0) {
+				goto send_read_err_pkt;
+			}
+			if (len < 4) { /* too small? */
+				goto recv_again;
+			}
+		}
+
+		/* Process recv'ed packet */
+		opcode = ntohs( ((uint16_t*)rbuf)[0] );
+		recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
+#if ENABLE_TFTP_DEBUG
+		fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
+#endif
+		if (opcode == TFTP_ERROR) {
+			static const char errcode_str[] ALIGN1 =
+				"\0"
+				"file not found\0"
+				"access violation\0"
+				"disk full\0"
+				"bad operation\0"
+				"unknown transfer id\0"
+				"file already exists\0"
+				"no such user\0"
+				"bad option";
+
+			const char *msg = "";
+
+			if (len > 4 && rbuf[4] != '\0') {
+				msg = &rbuf[4];
+				rbuf[io_bufsize - 1] = '\0'; /* paranoia */
+			} else if (recv_blk <= 8) {
+				msg = nth_string(errcode_str, recv_blk);
+			}
+			bb_error_msg("server error: (%u) %s", recv_blk, msg);
+			goto ret;
+		}
+
+#if ENABLE_FEATURE_TFTP_BLOCKSIZE
+		if (expect_OACK) {
+			expect_OACK = 0;
+			if (opcode == TFTP_OACK) {
+				/* server seems to support options */
+				char *res;
+
+				res = tftp_get_option("blksize", &rbuf[2], len - 2);
+				if (res) {
+					blksize = tftp_blksize_check(res, blksize);
+					if (blksize < 0) {
+						G_error_pkt_reason = ERR_BAD_OPT;
+						goto send_err_pkt;
+					}
+					io_bufsize = blksize + 4;
+				}
+# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+				if (remote_file && G.size == 0) { /* if we don't know it yet */
+					res = tftp_get_option("tsize", &rbuf[2], len - 2);
+					if (res) {
+						G.size = bb_strtoull(res, NULL, 10);
+						if (G.size)
+							tftp_progress_init();
+					}
+				}
+# endif
+				if (CMD_GET(option_mask32)) {
+					/* We'll send ACK for OACK,
+					 * such ACK has "block no" of 0 */
+					block_nr = 0;
+				}
+				continue;
+			}
+			/* rfc2347:
+			 * "An option not acknowledged by the server
+			 * must be ignored by the client and server
+			 * as if it were never requested." */
+			if (blksize != TFTP_BLKSIZE_DEFAULT)
+				bb_error_msg("falling back to blocksize "TFTP_BLKSIZE_DEFAULT_STR);
+			blksize = TFTP_BLKSIZE_DEFAULT;
+			io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
+		}
+#endif
+		/* block_nr is already advanced to next block# we expect
+		 * to get / block# we are about to send next time */
+
+		if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
+			if (recv_blk == block_nr) {
+				int sz = full_write(local_fd, &rbuf[4], len - 4);
+				if (sz != len - 4) {
+					strcpy(G_error_pkt_str, bb_msg_write_error);
+					G_error_pkt_reason = ERR_WRITE;
+					goto send_err_pkt;
+				}
+				if (sz != blksize) {
+					finished = 1;
+				}
+				IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += sz;)
+				continue; /* send ACK */
+			}
+/* Disabled to cope with servers with Sorcerer's Apprentice Syndrome */
+#if 0
+			if (recv_blk == (block_nr - 1)) {
+				/* Server lost our TFTP_ACK.  Resend it */
+				block_nr = recv_blk;
+				continue;
+			}
+#endif
+		}
+
+		if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
+			/* did peer ACK our last DATA pkt? */
+			if (recv_blk == (uint16_t) (block_nr - 1)) {
+				if (finished)
+					goto ret;
+				continue; /* send next block */
+			}
+		}
+		/* Awww... recv'd packet is not recognized! */
+		goto recv_again;
+		/* why recv_again? - rfc1123 says:
+		 * "The sender (i.e., the side originating the DATA packets)
+		 *  must never resend the current DATA packet on receipt
+		 *  of a duplicate ACK".
+		 * DATA pkts are resent ONLY on timeout.
+		 * Thus "goto send_again" will ba a bad mistake above.
+		 * See:
+		 * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
+		 */
+	} /* end of "while (1)" */
+ ret:
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		close(local_fd);
+		close(socket_fd);
+		free(xbuf);
+		free(rbuf);
+	}
+	return finished == 0; /* returns 1 on failure */
+
+ send_read_err_pkt:
+	strcpy(G_error_pkt_str, bb_msg_read_error);
+ send_err_pkt:
+	if (G_error_pkt_str[0])
+		bb_error_msg("%s", G_error_pkt_str);
+	G.error_pkt[1] = TFTP_ERROR;
+	xsendto(socket_fd, G.error_pkt, 4 + 1 + strlen(G_error_pkt_str),
+			&peer_lsa->u.sa, peer_lsa->len);
+	return EXIT_FAILURE;
+#undef remote_file
+}
+
+#if ENABLE_TFTP
+
+int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int tftp_main(int argc UNUSED_PARAM, char **argv)
+{
+	len_and_sockaddr *peer_lsa;
+	const char *local_file = NULL;
+	const char *remote_file = NULL;
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
+	const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
+	int blksize;
+# endif
+	int result;
+	int port;
+	IF_GETPUT(int opt;)
+
+	INIT_G();
+
+	/* -p or -g is mandatory, and they are mutually exclusive */
+	opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
+			IF_GETPUT("g--p:p--g:");
+
+	IF_GETPUT(opt =) getopt32(argv,
+			IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
+				"l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
+			&local_file, &remote_file
+			IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
+	argv += optind;
+
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
+	/* Check if the blksize is valid:
+	 * RFC2348 says between 8 and 65464 */
+	blksize = tftp_blksize_check(blksize_str, 65564);
+	if (blksize < 0) {
+		//bb_error_msg("bad block size");
+		return EXIT_FAILURE;
+	}
+# endif
+
+	if (remote_file) {
+		if (!local_file) {
+			const char *slash = strrchr(remote_file, '/');
+			local_file = slash ? slash + 1 : remote_file;
+		}
+	} else {
+		remote_file = local_file;
+	}
+
+	/* Error if filename or host is not known */
+	if (!remote_file || !argv[0])
+		bb_show_usage();
+
+	port = bb_lookup_port(argv[1], "udp", 69);
+	peer_lsa = xhost2sockaddr(argv[0], port);
+
+# if ENABLE_TFTP_DEBUG
+	fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
+			xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
+			remote_file, local_file);
+# endif
+
+# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+	G.file = remote_file;
+# endif
+	result = tftp_protocol(
+		NULL /*our_lsa*/, peer_lsa,
+		local_file, remote_file
+		IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
+		IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
+	);
+	tftp_progress_done();
+
+	if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
+		unlink(local_file);
+	}
+	return result;
+}
+
+#endif /* ENABLE_TFTP */
+
+#if ENABLE_TFTPD
+int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int tftpd_main(int argc UNUSED_PARAM, char **argv)
+{
+	len_and_sockaddr *our_lsa;
+	len_and_sockaddr *peer_lsa;
+	char *local_file, *mode, *user_opt;
+	const char *error_msg;
+	int opt, result, opcode;
+	IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
+	IF_FEATURE_TFTP_BLOCKSIZE(int want_transfer_size = 0;)
+
+	INIT_G();
+
+	our_lsa = get_sock_lsa(STDIN_FILENO);
+	if (!our_lsa) {
+		/* This is confusing:
+		 *bb_error_msg_and_die("stdin is not a socket");
+		 * Better: */
+		bb_show_usage();
+		/* Help text says that tftpd must be used as inetd service,
+		 * which is by far the most usual cause of get_sock_lsa
+		 * failure */
+	}
+	peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
+	peer_lsa->len = our_lsa->len;
+
+	/* Shifting to not collide with TFTP_OPTs */
+	opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:l", &user_opt) << 8);
+	argv += optind;
+	if (opt & TFTPD_OPT_l) {
+		openlog(applet_name, LOG_PID, LOG_DAEMON);
+		logmode = LOGMODE_SYSLOG;
+	}
+	if (opt & TFTPD_OPT_u) {
+		/* Must be before xchroot */
+		G.pw = xgetpwnam(user_opt);
+	}
+	if (argv[0]) {
+		xchroot(argv[0]);
+	}
+
+	result = recv_from_to(STDIN_FILENO, G.block_buf, sizeof(G.block_buf),
+			0 /* flags */,
+			&peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
+
+	error_msg = "malformed packet";
+	opcode = ntohs(*(uint16_t*)G.block_buf);
+	if (result < 4 || result >= sizeof(G.block_buf)
+	 || G.block_buf[result-1] != '\0'
+	 || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
+	     IF_GETPUT(&&)
+	     IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
+	    )
+	) {
+		goto err;
+	}
+	local_file = G.block_buf + 2;
+	if (local_file[0] == '.' || strstr(local_file, "/.")) {
+		error_msg = "dot in file name";
+		goto err;
+	}
+	mode = local_file + strlen(local_file) + 1;
+	/* RFC 1350 says mode string is case independent */
+	if (mode >= G.block_buf + result || strcasecmp(mode, "octet") != 0) {
+		goto err;
+	}
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
+	{
+		char *res;
+		char *opt_str = mode + sizeof("octet");
+		int opt_len = G.block_buf + result - opt_str;
+		if (opt_len > 0) {
+			res = tftp_get_option("blksize", opt_str, opt_len);
+			if (res) {
+				blksize = tftp_blksize_check(res, 65564);
+				if (blksize < 0) {
+					G_error_pkt_reason = ERR_BAD_OPT;
+					/* will just send error pkt */
+					goto do_proto;
+				}
+			}
+			if (opcode != TFTP_WRQ /* download? */
+			/* did client ask us about file size? */
+			 && tftp_get_option("tsize", opt_str, opt_len)
+			) {
+				want_transfer_size = 1;
+			}
+		}
+	}
+# endif
+
+	if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
+		if (opt & TFTPD_OPT_r) {
+			/* This would mean "disk full" - not true */
+			/*G_error_pkt_reason = ERR_WRITE;*/
+			error_msg = bb_msg_write_error;
+			goto err;
+		}
+		IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
+	} else {
+		IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
+	}
+
+	/* NB: if G_error_pkt_str or G_error_pkt_reason is set up,
+	 * tftp_protocol() just sends one error pkt and returns */
+
+ do_proto:
+	close(STDIN_FILENO); /* close old, possibly wildcard socket */
+	/* tftp_protocol() will create new one, bound to particular local IP */
+	result = tftp_protocol(
+		our_lsa, peer_lsa,
+		local_file IF_TFTP(, NULL /*remote_file*/)
+		IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
+		IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
+	);
+
+	return result;
+ err:
+	strcpy(G_error_pkt_str, error_msg);
+	goto do_proto;
+}
+
+#endif /* ENABLE_TFTPD */
+
+#endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */