top: add keyboard commands to --help
[oweals/busybox.git] / networking / tftp.c
index 36e63e0f725fe48e9678a2c169d8f8ef95630122..fcd933f6ad76adcd416b347faa6fa6eb3a7032b1 100644 (file)
@@ -1,7 +1,5 @@
 /* vi: set sw=4 ts=4: */
-/* -------------------------------------------------------------------------
- * tftp.c
- *
+/*
  * A simple tftp client/server for busybox.
  * Tries to follow RFC1350.
  * Only "octet" mode supported.
  *
  * tftpd added by Denys Vlasenko & Vladimir Dronnikov
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
- * ------------------------------------------------------------------------- */
-
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
 #include "libbb.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"
-#define TFTP_TIMEOUT_MS             50
+/* 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 */
 
@@ -39,7 +37,7 @@
 #define TFTP_ERROR 5
 #define TFTP_OACK  6
 
-/* error codes sent over network (we use only 0, 3 and 8) */
+/* 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
@@ -64,15 +62,15 @@ enum {
 };
 
 #if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
-#define USE_GETPUT(...)
+#define IF_GETPUT(...)
 #define CMD_GET(cmd) 1
 #define CMD_PUT(cmd) 0
 #elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
-#define USE_GETPUT(...)
+#define IF_GETPUT(...)
 #define CMD_GET(cmd) 0
 #define CMD_PUT(cmd) 1
 #else
-#define USE_GETPUT(...) __VA_ARGS__
+#define IF_GETPUT(...) __VA_ARGS__
 #define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
 #define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
 #endif
@@ -87,18 +85,47 @@ struct globals {
        char *user_opt;
        /* 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 block_buf        (G.block_buf   )
 #define user_opt         (G.user_opt    )
 #define error_pkt        (G.error_pkt   )
-#define INIT_G() \
-       do { \
-       } while (0)
+#define INIT_G() do { } while (0)
 
 #define error_pkt_reason (error_pkt[3])
 #define error_pkt_str    (error_pkt + 4)
 
+#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+static void tftp_progress_update(void)
+{
+       bb_progress_update(&G.pmt, G.file, 0, G.pos, G.size);
+}
+static void tftp_progress_init(void)
+{
+       bb_progress_init(&G.pmt);
+       tftp_progress_update();
+}
+static void tftp_progress_done(void)
+{
+       if (G.pmt.inited) {
+               tftp_progress_update();
+               bb_putchar_stderr('\n');
+               G.pmt.inited = 0;
+       }
+}
+#else
+# define tftp_progress_init() ((void)0)
+# define tftp_progress_done() ((void)0)
+#endif
 
 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 
@@ -115,15 +142,14 @@ static int tftp_blksize_check(const char *blksize_str, int maxsize)
                bb_error_msg("bad blocksize '%s'", blksize_str);
                return -1;
        }
-#if ENABLE_DEBUG_TFTP
+# if ENABLE_TFTP_DEBUG
        bb_error_msg("using blksize %u", blksize);
-#endif
+# endif
        return blksize;
 }
 
-static char *tftp_get_blksize(char *buf, int len)
+static char *tftp_get_option(const char *option, char *buf, int len)
 {
-#define option "blksize"
        int opt_val = 0;
        int opt_found = 0;
        int k;
@@ -155,26 +181,32 @@ static char *tftp_get_blksize(char *buf, int len)
        }
 
        return NULL;
-#undef option
 }
 
 #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,
-               USE_TFTP(const char *remote_file,)
-               int blksize)
-{
+               const char *local_file
+               IF_TFTP(, const char *remote_file)
 #if !ENABLE_TFTP
-#define remote_file NULL
+# 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;
-       USE_FEATURE_TFTP_BLOCKSIZE(smallint want_option_ack = 0;)
+       IF_FEATURE_TFTP_BLOCKSIZE(smallint expect_OACK = 0;)
        smallint finished = 0;
        uint16_t opcode;
        uint16_t block_nr;
@@ -184,21 +216,18 @@ static int tftp_protocol(
        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 seperate */
-       /* In case we rcv a garbage pkt and we need to rexmit the last pkt */
+        * 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);
 
-       block_nr = 1;
-       cp = xbuf + 2;
-
-       if (!ENABLE_TFTP || our_lsa) {
-               /* tftpd */
-
+       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
@@ -212,21 +241,13 @@ static int tftp_protocol(
                if (error_pkt_reason || error_pkt_str[0])
                        goto send_err_pkt;
 
-               if (CMD_GET(option_mask32)) {
-                       /* it's upload - we must ACK 1st packet (with filename)
-                        * as if it's "block 0" */
-                       block_nr = 0;
-               }
-
                if (user_opt) {
-                       struct passwd *pw = getpwnam(user_opt);
-                       if (!pw)
-                               bb_error_msg_and_die("unknown user '%s'", user_opt);
+                       struct passwd *pw = xgetpwnam(user_opt);
                        change_identity(pw); /* initgroups, setgid, setuid */
                }
        }
 
-       /* Open local file (must be after changing user) */
+       /* Prepare open mode */
        if (CMD_PUT(option_mask32)) {
                open_mode = O_RDONLY;
        } else {
@@ -238,22 +259,49 @@ static int tftp_protocol(
                }
 #endif
        }
-       if (!(option_mask32 & TFTPD_OPT)) {
-               local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
-               if (NOT_LONE_DASH(local_file))
-                       local_fd = xopen(local_file, open_mode);
-       } else {
-               local_fd = open_or_warn(local_file, open_mode);
+
+       /* 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) {
-                       /*error_pkt_reason = ERR_NOFILE/ERR_ACCESS?*/
+                       error_pkt_reason = ERR_NOFILE;
                        strcpy((char*)error_pkt_str, "can't open file");
                        goto send_err_pkt;
                }
-       }
-
-       if (!ENABLE_TFTP || our_lsa) {
+/* gcc 4.3.1 would NOT optimize it out as it should! */
 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
-               if (blksize != TFTP_BLKSIZE_DEFAULT) {
+               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),
@@ -262,9 +310,19 @@ static int tftp_protocol(
                        goto add_blksize_opt;
                }
 #endif
-       }
-       else {
-/* Removing it, or using if() statement instead may lead to
+               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 */
@@ -294,29 +352,52 @@ static int tftp_protocol(
                }
                strcpy(cp, remote_file);
                cp += len;
-               /* add "mode" part of the package */
+               /* add "mode" part of the packet */
                strcpy(cp, "octet");
                cp += sizeof("octet");
 
-#if ENABLE_FEATURE_TFTP_BLOCKSIZE
-               if (blksize == TFTP_BLKSIZE_DEFAULT)
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
+               if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
                        goto send_pkt;
 
-               /* Non-standard blocksize: add option to pkt */
-               if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
+               /* 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;
                }
-               want_option_ack = 1;
-#endif
+               expect_OACK = 1;
+# endif
 #endif /* ENABLE_TFTP */
 
 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
  add_blksize_opt:
-               /* add "blksize", <nul>, blksize, <nul> */
-               strcpy(cp, "blksize");
-               cp += sizeof("blksize");
-               cp += snprintf(cp, 6, "%d", blksize) + 1;
+               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;
@@ -349,17 +430,24 @@ static int tftp_protocol(
                /* NB: send_len value is preserved in code below
                 * for potential resend */
 
-               retries = TFTP_NUM_RETRIES;     /* re-initialize */
+               retries = TFTP_NUM_RETRIES;  /* re-initialize */
                waittime_ms = TFTP_TIMEOUT_MS;
 
  send_again:
-#if ENABLE_DEBUG_TFTP
+#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 (ENABLE_TFTP && remote_file) /* tftp */
+                       G.pos = (block_nr - 1) * (uoff_t)blksize;
+               if (G.pmt.inited)
+                       tftp_progress_update();
+#endif
                /* Was it final ACK? then exit */
                if (finished && (opcode == TFTP_ACK))
                        goto ret;
@@ -375,6 +463,7 @@ static int tftp_protocol(
                case 0:
                        retries--;
                        if (retries == 0) {
+                               tftp_progress_done();
                                bb_error_msg("timeout");
                                goto ret; /* no err packet sent */
                        }
@@ -415,12 +504,11 @@ static int tftp_protocol(
                /* Process recv'ed packet */
                opcode = ntohs( ((uint16_t*)rbuf)[0] );
                recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
-#if ENABLE_DEBUG_TFTP
+#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[] =
+                       static const char errcode_str[] ALIGN1 =
                                "\0"
                                "file not found\0"
                                "access violation\0"
@@ -444,13 +532,13 @@ static int tftp_protocol(
                }
 
 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
-               if (want_option_ack) {
-                       want_option_ack = 0;
+               if (expect_OACK) {
+                       expect_OACK = 0;
                        if (opcode == TFTP_OACK) {
                                /* server seems to support options */
                                char *res;
 
-                               res = tftp_get_blksize(&rbuf[2], len - 2);
+                               res = tftp_get_option("blksize", &rbuf[2], len - 2);
                                if (res) {
                                        blksize = tftp_blksize_check(res, blksize);
                                        if (blksize < 0) {
@@ -458,16 +546,30 @@ static int tftp_protocol(
                                                goto send_err_pkt;
                                        }
                                        io_bufsize = blksize + 4;
-                                       /* Send ACK for OACK ("block" no: 0) */
+                               }
+# 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." */
+                               continue;
                        }
-                       bb_error_msg("server only supports blocksize of 512");
+                       /* 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;
                }
@@ -488,11 +590,14 @@ static int tftp_protocol(
                                }
                                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)) {
@@ -528,43 +633,44 @@ static int tftp_protocol(
        strcpy((char*)error_pkt_str, bb_msg_read_error);
  send_err_pkt:
        if (error_pkt_str[0])
-               bb_error_msg((char*)error_pkt_str);
+               bb_error_msg("%s", (char*)error_pkt_str);
        error_pkt[1] = TFTP_ERROR;
        xsendto(socket_fd, error_pkt, 4 + 1 + strlen((char*)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 ATTRIBUTE_UNUSED, char **argv)
+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
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
        const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
-#endif
        int blksize;
+# endif
        int result;
        int port;
-       USE_GETPUT(int opt;)
+       IF_GETPUT(int opt;)
 
        INIT_G();
 
        /* -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:");
+       opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
+                       IF_GETPUT("g--p:p--g:");
 
-       USE_GETPUT(opt =) getopt32(argv,
-                       USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
-                               "l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
+       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
-                       USE_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
+                       IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
        argv += optind;
 
-#if ENABLE_FEATURE_TFTP_BLOCKSIZE
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
        /* Check if the blksize is valid:
         * RFC2348 says between 8 and 65464 */
        blksize = tftp_blksize_check(blksize_str, 65564);
@@ -572,14 +678,17 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
                //bb_error_msg("bad block size");
                return EXIT_FAILURE;
        }
-#else
-       blksize = TFTP_BLKSIZE_DEFAULT;
-#endif
+# endif
 
-       if (!local_file)
-               local_file = remote_file;
-       if (!remote_file)
+       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();
@@ -587,16 +696,22 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
        port = bb_lookup_port(argv[1], "udp", 69);
        peer_lsa = xhost2sockaddr(argv[0], port);
 
-#if ENABLE_DEBUG_TFTP
+# 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
+# endif
 
+# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
+       G.file = remote_file;
+# endif
        result = tftp_protocol(
-                       NULL /* our_lsa*/, peer_lsa,
-                       local_file, remote_file,
-                       blksize);
+               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);
@@ -607,36 +722,29 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
 #endif /* ENABLE_TFTP */
 
 #if ENABLE_TFTPD
-
-/* TODO: libbb candidate? */
-static len_and_sockaddr *get_sock_lsa(int s)
-{
-       len_and_sockaddr *lsa;
-       socklen_t len = 0;
-
-       if (getsockname(s, NULL, &len) != 0)
-               return NULL;
-       lsa = xzalloc(LSA_LEN_SIZE + len);
-       lsa->len = len;
-       getsockname(s, &lsa->u.sa, &lsa->len);
-       return lsa;
-}
-
 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
+int tftpd_main(int argc UNUSED_PARAM, char **argv)
 {
        len_and_sockaddr *our_lsa;
        len_and_sockaddr *peer_lsa;
        char *local_file, *mode;
        const char *error_msg;
        int opt, result, opcode;
-       int blksize = TFTP_BLKSIZE_DEFAULT;
+       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)
-               bb_perror_msg_and_die("stdin is not a socket");
+       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;
 
@@ -654,9 +762,9 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
        opcode = ntohs(*(uint16_t*)block_buf);
        if (result < 4 || result >= sizeof(block_buf)
         || block_buf[result-1] != '\0'
-        || (USE_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
-            USE_GETPUT(&&)
-            USE_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
+        || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
+            IF_GETPUT(&&)
+            IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
            )
        ) {
                goto err;
@@ -670,13 +778,13 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
        if (mode >= block_buf + result || strcmp(mode, "octet") != 0) {
                goto err;
        }
-#if ENABLE_FEATURE_TFTP_BLOCKSIZE
+# if ENABLE_FEATURE_TFTP_BLOCKSIZE
        {
                char *res;
                char *opt_str = mode + sizeof("octet");
                int opt_len = block_buf + result - opt_str;
                if (opt_len > 0) {
-                       res = tftp_get_blksize(opt_str, opt_len);
+                       res = tftp_get_option("blksize", opt_str, opt_len);
                        if (res) {
                                blksize = tftp_blksize_check(res, 65564);
                                if (blksize < 0) {
@@ -685,9 +793,15 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
                                        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
+# endif
 
        if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
                if (opt & TFTPD_OPT_r) {
@@ -696,21 +810,22 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
                        error_msg = bb_msg_write_error;
                        goto err;
                }
-               USE_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
+               IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
        } else {
-               USE_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
+               IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
        }
 
-       close(STDIN_FILENO); /* close old, possibly wildcard socket */
-       /* tftp_protocol() will create new one, bound to particular local IP */
-
        /* NB: if error_pkt_str or 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, USE_TFTP(NULL /*remote_file*/,)
-               blksize
+               local_file IF_TFTP(, NULL /*remote_file*/)
+               IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
+               IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
        );
 
        return result;