From dd9228b861e41c816b31035ce9c2dfa3e5b5dc97 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Wed, 19 Mar 2008 05:00:05 +0000 Subject: tftpd: make it emit error packets telnetd: use login always, not "sometimes login, sometimes shell" text data bss dec hex filename 797612 641 7380 805633 c4b01 busybox_old 797695 641 7380 805716 c4b54 busybox_unstripped --- networking/tftp.c | 292 +++++++++++++++++++++++++++++++++--------------------- 1 file changed, 178 insertions(+), 114 deletions(-) (limited to 'networking/tftp.c') diff --git a/networking/tftp.c b/networking/tftp.c index 3075ab04b..83b0ef36f 100644 --- a/networking/tftp.c +++ b/networking/tftp.c @@ -25,7 +25,7 @@ #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT -#define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */ +#define TFTP_BLKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */ #define TFTP_TIMEOUT_MS 50 #define TFTP_MAXTIMEOUT_MS 2000 #define TFTP_NUM_RETRIES 12 /* number of backed-off retries */ @@ -38,6 +38,17 @@ #define TFTP_ERROR 5 #define TFTP_OACK 6 +/* error codes sent over network */ +#define ERR_UNSPEC 0 +#define ERR_NOFILE 1 +#define ERR_ACCESS 2 +#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 + #if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT #define USE_GETPUT(...) #define CMD_GET(cmd) 1 @@ -56,29 +67,48 @@ * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive */ -// TODO: emit error packets before dying + +struct globals { + /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */ + uint8_t error_pkt[4 + 32]; + /* used in tftpd_main(), a bit big fro stack: */ + char block_buf[TFTP_BLKSIZE_DEFAULT]; +}; +#define G (*(struct globals*)&bb_common_bufsiz1) +#define block_buf (G.block_buf ) +#define error_pkt (G.error_pkt ) +#define INIT_G() \ + do { \ + } while (0) + +#define error_pkt_reason (error_pkt[3]) +#define error_pkt_str (error_pkt + 4) #if ENABLE_FEATURE_TFTP_BLOCKSIZE -static int tftp_blocksize_check(int blocksize, int bufsize) +static int tftp_blksize_check(const char *blksize_str, int maxsize) { - /* Check if the blocksize is valid: + /* Check if the blksize is valid: * RFC2348 says between 8 and 65464, * but our implementation makes it impossible - * to use blocksizes smaller than 22 octets. - */ - if ((bufsize && (blocksize > bufsize)) - || (blocksize < 24) || (blocksize > 65564) + * 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"); - return 0; + bb_error_msg("bad blocksize '%s'", blksize_str); + return -1; } - return blocksize; +#if ENABLE_DEBUG_TFTP + bb_error_msg("using blksize %u", blksize); +#endif + return blksize; } -static char *tftp_option_get(char *buf, int len, const char *option) +static char *tftp_get_blksize(char *buf, int len) { +#define option "blksize" int opt_val = 0; int opt_found = 0; int k; @@ -110,6 +140,7 @@ static char *tftp_option_get(char *buf, int len, const char *option) } return NULL; +#undef option } #endif @@ -120,7 +151,7 @@ static int tftp_protocol( len_and_sockaddr *peer_lsa, USE_TFTP(const char *remote_file,) int local_fd, - int blocksize) + int blksize) { #if !ENABLE_TFTP #define remote_file NULL @@ -135,14 +166,14 @@ static int tftp_protocol( uint16_t block_nr; uint16_t recv_blk; int retries, waittime_ms; - int tftp_bufsize = blocksize + 4; + 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 */ - char *xbuf = xmalloc(tftp_bufsize); - char *rbuf = xmalloc(tftp_bufsize); + 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); @@ -160,6 +191,10 @@ static int tftp_protocol( 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 (error_pkt_reason || error_pkt_str[0]) + goto send_err_pkt; + if (CMD_GET(cmd)) { /* it's upload - we must ACK 1st packet (with filename) * as if it's "block 0" */ @@ -167,10 +202,11 @@ static int tftp_protocol( } #if ENABLE_FEATURE_TFTP_BLOCKSIZE - if (blocksize != TFTP_BLOCKSIZE_DEFAULT) { + if (blksize != TFTP_BLKSIZE_DEFAULT) { /* Create and send OACK packet */ - /* block_nr is still 1, we expect ACK to (block_nr-1), - * that is, to "block 0" */ + /* 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; cp = xbuf + 2; goto add_blksize_opt; @@ -200,7 +236,7 @@ static int tftp_protocol( /* add filename and mode */ /* fill in packet if the filename fits into xbuf */ len = strlen(remote_file) + 1; - if (2 + len + sizeof("octet") >= tftp_bufsize) { + if (2 + len + sizeof("octet") >= io_bufsize) { bb_error_msg("remote filename is too long"); goto ret; } @@ -211,18 +247,18 @@ static int tftp_protocol( cp += sizeof("octet"); #if ENABLE_FEATURE_TFTP_BLOCKSIZE - if (blocksize != TFTP_BLOCKSIZE_DEFAULT) { + if (blksize != TFTP_BLKSIZE_DEFAULT) { /* rfc2348 says that 65464 is a max allowed value */ - if ((&xbuf[tftp_bufsize - 1] - cp) < sizeof("blksize NNNNN")) { + if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN")) { bb_error_msg("remote filename is too long"); goto ret; } want_option_ack = 1; add_blksize_opt: - /* add "blksize", , blocksize, */ + /* add "blksize", , blksize, */ strcpy(cp, "blksize"); cp += sizeof("blksize"); - cp += snprintf(cp, 6, "%d", blocksize) + 1; + cp += snprintf(cp, 6, "%d", blksize) + 1; } #endif /* First packet is built, so skip packet generation */ @@ -240,12 +276,11 @@ static int tftp_protocol( opcode = TFTP_ACK; if (CMD_PUT(cmd)) { opcode = TFTP_DATA; - len = full_read(local_fd, cp, tftp_bufsize - 4); + len = full_read(local_fd, cp, blksize); if (len < 0) { - bb_perror_msg(bb_msg_read_error); - goto ret; + goto send_read_err_pkt; } - if (len != (tftp_bufsize - 4)) { + if (len != blksize) { finished = 1; } cp += len; @@ -277,11 +312,28 @@ static int tftp_protocol( /*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) { + 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, tftp_bufsize, 0, + 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. @@ -291,62 +343,44 @@ static int tftp_protocol( } else { /* tftpd, or not the very first packet: * socket is connect()ed, can just read from it. */ - len = safe_read(socket_fd, rbuf, tftp_bufsize); + /* Don't full_read()! + * This is not TCP, one read == one pkt! */ + len = safe_read(socket_fd, rbuf, io_bufsize); } if (len < 0) { - bb_perror_msg("read"); - goto ret; + goto send_read_err_pkt; } - if (len < 4) /* too small? */ + if (len < 4) { /* too small? */ goto recv_again; - goto process_pkt; - case 0: - retries--; - if (retries == 0) { - bb_error_msg("timeout"); - goto ret; } - - /* 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 */ - default: - /*bb_perror_msg("poll"); - done in safe_poll */ - goto ret; } - process_pkt: + /* Process recv'ed packet */ opcode = ntohs( ((uint16_t*)rbuf)[0] ); recv_blk = ntohs( ((uint16_t*)rbuf)[1] ); - #if ENABLE_DEBUG_TFTP fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk); #endif if (opcode == TFTP_ERROR) { - static const char *const errcode_str[] = { - "", - "file not found", - "access violation", - "disk full", - "illegal TFTP operation", - "unknown transfer id", - "file already exists", - "no such user", - "bad option" - }; + static const char errcode_str[] = + "\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[tftp_bufsize - 1] = '\0'; - } else if (recv_blk < ARRAY_SIZE(errcode_str)) { - msg = errcode_str[recv_blk]; + 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; @@ -355,29 +389,18 @@ static int tftp_protocol( #if ENABLE_FEATURE_TFTP_BLOCKSIZE if (want_option_ack) { want_option_ack = 0; - if (opcode == TFTP_OACK) { /* server seems to support options */ char *res; - res = tftp_option_get(&rbuf[2], len - 2, "blksize"); + res = tftp_get_blksize(&rbuf[2], len - 2); if (res) { - int blksize = xatoi_u(res); - if (!tftp_blocksize_check(blksize, tftp_bufsize - 4)) { - /* send ERROR 8 to server... */ - /* htons can be impossible to use in const initializer: */ - /*static const uint16_t error_8[2] = { htons(TFTP_ERROR), htons(8) };*/ - /* thus we open-code big-endian layout */ - static const uint8_t error_8[4] = { 0,TFTP_ERROR, 0,8 }; - xsendto(socket_fd, error_8, 4, &peer_lsa->u.sa, peer_lsa->len); - bb_error_msg("server proposes bad blksize %d, exiting", blksize); - goto ret; + blksize = tftp_blksize_check(res, blksize); + if (blksize < 0) { + error_pkt_reason = ERR_BAD_OPT; + goto send_err_pkt; } -#if ENABLE_DEBUG_TFTP - fprintf(stderr, "using blksize %u\n", - blksize); -#endif - tftp_bufsize = blksize + 4; + io_bufsize = blksize + 4; /* Send ACK for OACK ("block" no: 0) */ block_nr = 0; continue; @@ -387,10 +410,9 @@ static int tftp_protocol( * must be ignored by the client and server * as if it were never requested." */ } - - bb_error_msg("blksize is not supported by server" - " - reverting to 512"); - tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4; + bb_error_msg("server only supports blocksize of 512"); + blksize = TFTP_BLKSIZE_DEFAULT; + io_bufsize = TFTP_BLKSIZE_DEFAULT + 4; } #endif /* block_nr is already advanced to next block# we expect @@ -401,9 +423,10 @@ static int tftp_protocol( len = full_write(local_fd, &rbuf[4], len - 4); if (len < 0) { bb_perror_msg(bb_msg_write_error); - goto ret; + error_pkt_reason = ERR_WRITE; + goto send_err_pkt; } - if (len != (tftp_bufsize - 4)) { + if (len != blksize) { finished = 1; } continue; /* send ACK */ @@ -442,6 +465,15 @@ static int tftp_protocol( free(rbuf); } return finished == 0; /* returns 1 on failure */ + + send_read_err_pkt: + bb_perror_msg(bb_msg_read_error); + strcpy(error_pkt_str, bb_msg_read_error); + send_err_pkt: + error_pkt[1] = TFTP_ERROR; + xsendto(socket_fd, error_pkt, 4 + 1 + strlen(error_pkt_str), + &peer_lsa->u.sa, peer_lsa->len); + return EXIT_FAILURE; } #if ENABLE_TFTP @@ -457,18 +489,20 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv) int local_fd; int flags = 0; int result; - int blocksize = TFTP_BLOCKSIZE_DEFAULT; + int blksize; + const char *blksize_str = "512"; + + 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:") - USE_FEATURE_TFTP_BLOCKSIZE("b+"); + USE_GETPUT("g--p:p--g:"); USE_GETPUT(cmd =) getopt32(argv, USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p") "l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"), &local_file, &remote_file - USE_FEATURE_TFTP_BLOCKSIZE(, &blocksize)); + USE_FEATURE_TFTP_BLOCKSIZE(, &blksize_str)); argv += optind; flags = O_RDONLY; @@ -476,8 +510,13 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv) flags = O_WRONLY | O_CREAT | O_TRUNC; #if ENABLE_FEATURE_TFTP_BLOCKSIZE - if (!tftp_blocksize_check(blocksize, 0)) + /* 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 (!local_file) @@ -506,7 +545,7 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv) USE_GETPUT(cmd,) NULL /* our_lsa*/, peer_lsa, - remote_file, local_fd, blocksize); + remote_file, local_fd, blksize); if (ENABLE_FEATURE_CLEAN_UP) close(local_fd); @@ -537,12 +576,16 @@ static len_and_sockaddr *get_sock_lsa(int s) int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv) { - char block_buf[TFTP_BLOCKSIZE_DEFAULT]; len_and_sockaddr *our_lsa; len_and_sockaddr *peer_lsa; - char *filename, *mode, *opt_str; - int opt_r, result, opcode, open_mode, local_fd, blksize; - USE_GETPUT(int cmd;) + char *filename, *mode; + const char *error_msg; + int opt_r, result, opcode, open_mode; + int local_fd = local_fd; /* for compiler */ + int blksize = blksize; + USE_GETPUT(int cmd = cmd;) + + INIT_G(); our_lsa = get_sock_lsa(STDIN_FILENO); if (!our_lsa) @@ -559,6 +602,7 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv) 0 /* flags */, &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len); + error_msg = "malformed packet"; opcode = ntohs(*(uint16_t*)block_buf); if (result < 4 || result >= sizeof(block_buf) || block_buf[result-1] != '\0' @@ -567,27 +611,35 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv) USE_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */ ) ) { - bb_error_msg_and_die("malformed packet"); + goto err; } filename = block_buf + 2; if (filename[0] == '.' || strstr(filename, "/.")) { - bb_error_msg_and_die("dot in filename"); + error_msg = "dot in filename"; + goto err; } mode = filename + strlen(filename) + 1; - if (mode >= block_buf + sizeof(block_buf) + if (mode >= block_buf + result || strcmp(mode, "octet") != 0 ) { - bb_error_msg_and_die("malformed packet"); + goto err; } - blksize = TFTP_BLOCKSIZE_DEFAULT; + blksize = TFTP_BLKSIZE_DEFAULT; #if ENABLE_FEATURE_TFTP_BLOCKSIZE - opt_str = mode + 6; - if (opt_str < block_buf + sizeof(block_buf)) { - char *res = tftp_option_get(opt_str, block_buf + sizeof(block_buf) - opt_str, "blksize"); - if (res) { - int sz = xatoi_u(res); - if (tftp_blocksize_check(sz, 0)) - blksize = sz; + { + 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); + if (res) { + blksize = tftp_blksize_check(res, 65564); + if (blksize < 0) { + error_pkt_reason = ERR_BAD_OPT; + /* will just send error pkt */ + goto do_proto; + } + } } } #endif @@ -599,16 +651,28 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv) #endif #if ENABLE_FEATURE_TFTP_GET if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) { - if (opt_r) - bb_error_msg_and_die("upload is prohibited"); + if (opt_r) { + error_pkt_reason = ERR_WRITE; + /* will just send error pkt */ + goto do_proto; + } USE_GETPUT(cmd = 1;) /* CMD_GET: we will receive file's data */ open_mode = O_WRONLY | O_TRUNC; } #endif - local_fd = xopen(filename, open_mode); + local_fd = open(filename, open_mode); + if (local_fd < 0) { + error_msg = "can't open file"; + err: + strcpy(error_pkt_str, error_msg); + } 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: result = tftp_protocol( USE_GETPUT(cmd,) our_lsa, peer_lsa, -- cgit v1.2.3