现在好多通信是用中间件,觉得中间件也挺好的
只有想不到,没有做不到
这个代码运行出来有很多问题。改了很多次，最后还是运行失败？
#include "libbb.h"
#if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
#define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
#define TFTP_TIMEOUT 5 /* seconds */
#define TFTP_NUM_RETRIES 5 /* number of 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
#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
#define USE_GETPUT(...)
#define CMD_GET(cmd) 1
#define CMD_PUT(cmd) 0
#elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
#define USE_GETPUT(...)
#define CMD_GET(cmd) 0
#define CMD_PUT(cmd) 1
#else
#define USE_GETPUT(...) __VA_ARGS__
/* masks coming from getpot32 */
#define CMD_GET(cmd) ((cmd) & 1)
#define CMD_PUT(cmd) ((cmd) & 2)
#endif
/* NB: in the code below
* CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
*/
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
static int tftp_blocksize_check(int blocksize, int bufsize)
{
/* Check if the blocksize 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 < 8) || (blocksize > 65564)
) {
bb_error_msg("bad blocksize");
return 0;
}
return blocksize;
}
static char *tftp_option_get(char *buf, int len, const char *option)
{
int opt_val = 0;
int opt_found = 0;
int k;
while (len > 0) {
/* Make sure the 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) {
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( USE_GETPUT(const int cmd,)
len_and_sockaddr *peer_lsa,
const char *remotefile, const int localfd,
unsigned port, int tftp_bufsize)
{
struct timeval tv;
fd_set rfds;
int socketfd;
int len;
int send_len;
USE_FEATURE_TFTP_BLOCKSIZE(smallint want_option_ack = 0;)
smallint finished = 0;
uint16_t opcode;
uint16_t block_nr = 1;
uint16_t recv_blk;
int timeout = TFTP_NUM_RETRIES;
char *cp;
unsigned org_port;
len_and_sockaddr *const from = alloca(offsetof(len_and_sockaddr, sa) + peer_lsa->len);
/* 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 += 4);
char *rbuf = xmalloc(tftp_bufsize);
port = org_port = htons(port);
socketfd = xsocket(peer_lsa->sa.sa_family, SOCK_DGRAM, 0);
/* build opcode */
opcode = TFTP_WRQ;
if (CMD_GET(cmd)) {
opcode = TFTP_RRQ;
}
cp = xbuf + 2;
/* add filename and mode */
/* fill in packet if the filename fits into xbuf */
len = strlen(remotefile) + 1;
if (2 + len + sizeof("octet") >= tftp_bufsize) {
bb_error_msg("remote filename is too long");
goto ret;
}
strcpy(cp, remotefile);
cp += len;
/* add "mode" part of the package */
strcpy(cp, "octet");
cp += sizeof("octet");
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
len = tftp_bufsize - 4; /* data block size */
if (len != TFTP_BLOCKSIZE_DEFAULT) {
/* rfc2348 says that 65464 is a max allowed value */
if ((&xbuf[tftp_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
bb_error_msg("remote filename is too long");
goto ret;
}
/* add "blksize", <nul>, blocksize */
strcpy(cp, "blksize");
cp += sizeof("blksize");
cp += snprintf(cp, 6, "%d", len) + 1;
want_option_ack = 1;
}
#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(cmd)) {
opcode = TFTP_DATA;
len = full_read(localfd, cp, tftp_bufsize - 4);
if (len < 0) {
bb_perror_msg(bb_msg_read_error);
goto ret;
}
if (len != (tftp_bufsize - 4)) {
finished = 1;
}
cp += 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 */
send_again:
#if ENABLE_DEBUG_TFTP
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(socketfd, xbuf, send_len, &peer_lsa->sa, peer_lsa->len);
/* Was it final ACK? then exit */
if (finished && (opcode == TFTP_ACK))
goto ret;
timeout = TFTP_NUM_RETRIES; /* re-initialize */
recv_again:
/* Receive packet */
tv.tv_sec = TFTP_TIMEOUT;
tv.tv_usec = 0;
FD_ZERO(&rfds);
FD_SET(socketfd, &rfds);
switch (select(socketfd + 1, &rfds, NULL, NULL, &tv)) {
unsigned from_port;
case 1:
from->len = peer_lsa->len;
memset(&from->sa, 0, peer_lsa->len);
len = recvfrom(socketfd, rbuf, tftp_bufsize, 0,
&from->sa, &from->len);
if (len < 0) {
bb_perror_msg("recvfrom");
goto ret;
}
from_port = get_nport(&from->sa);
if (port == org_port) {
/* Our first query went to port 69
* but reply will come from different one.
* Remember and use this new port */
port = from_port;
set_nport(peer_lsa, from_port);
}
if (port != from_port)
goto recv_again;
goto process_pkt;
case 0:
timeout--;
if (timeout == 0) {
bb_error_msg("last timeout");
goto ret;
}
bb_error_msg("last timeout" + 5);
goto send_again; /* resend last sent pkt */
default:
bb_perror_msg("select");
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"
};
const char *msg = "";
if (rbuf[4] != '\0') {
msg = &rbuf[4];
rbuf[tftp_bufsize - 1] = '\0';
} else if (recv_blk < ARRAY_SIZE(errcode_str)) {
msg = errcode_str[recv_blk];
}
bb_error_msg("server error: (%u) %s", recv_blk, msg);
goto ret;
}
#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");
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(socketfd, error_8, 4, &peer_lsa->sa, peer_lsa->len);
bb_error_msg("server proposes bad blksize %d, exiting", blksize);
goto ret;
}
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "using blksize %u\n",
blksize);
#endif
tftp_bufsize = blksize + 4;
/* Send ACK for OACK ("block" no: 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." */
}
bb_error_msg("blksize is not supported by server"
" - reverting to 512");
tftp_bufsize = TFTP_BLOCKSIZE_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(cmd) && (opcode == TFTP_DATA)) {
if (recv_blk == block_nr) {
len = full_write(localfd, &rbuf[4], len - 4);
if (len < 0) {
bb_perror_msg(bb_msg_write_error);
goto ret;
}
if (len != (tftp_bufsize - 4)) {
finished = 1;
}
continue; /* send ACK */
}
if (recv_blk == (block_nr - 1)) {
/* Server lost our TFTP_ACK. Resend it */
block_nr = recv_blk;
continue;
}
}
if (CMD_PUT(cmd) && (opcode == TFTP_ACK)) {
/* did server 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:
* [url]http://en.'s_Apprentice_Syndrome[/url]
*/
}
ret:
if (ENABLE_FEATURE_CLEAN_UP) {
close(socketfd);
free(xbuf);
free(rbuf);
}
return finished == 0; /* returns 1 on failure */
}
int tftp_main(int argc, char **argv);
int tftp_main(int argc, char **argv)
{
len_and_sockaddr *peer_lsa;
const char *localfile = NULL;
const char *remotefile = NULL;
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
const char *sblocksize = NULL;
#endif
int port;
USE_GETPUT(int cmd;)
int fd = -1;
int flags = 0;
int result;
int blocksize = TFTP_BLOCKSIZE_DEFAULT;
/* -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_GETPUT(cmd =) getopt32(argv,
USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
"l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
&localfile, &remotefile
USE_FEATURE_TFTP_BLOCKSIZE(, &sblocksize));
argv += optind;
flags = O_RDONLY;
if (CMD_GET(cmd))
flags = O_WRONLY | O_CREAT | O_TRUNC;
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (sblocksize) {
blocksize = xatoi_u(sblocksize);
if (!tftp_blocksize_check(blocksize, 0)) {
return EXIT_FAILURE;
}
}
#endif
if (!localfile)
localfile = remotefile;
if (!remotefile)
remotefile = localfile;
/* Error if filename or host is not known */
if (!remotefile || !argv[0])
bb_show_usage();
fd = CMD_GET(cmd) ? STDOUT_FILENO : STDIN_FILENO;
if (!LONE_DASH(localfile)) {
fd = xopen(localfile, flags);
}
port = bb_lookup_port(argv[1], "udp", 69);
peer_lsa = xhost2sockaddr(argv[0], port);
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "using server '%s', remotefile '%s', localfile '%s'\n",
xmalloc_sockaddr2dotted(&peer_lsa->sa),
remotefile, localfile);
#endif
result = tftp( USE_GETPUT(cmd,) peer_lsa, remotefile, fd, port, blocksize);
if (ENABLE_FEATURE_CLEAN_UP)
close(fd);
if (result != EXIT_SUCCESS && !LONE_DASH(localfile) && CMD_GET(cmd)) {
unlink(localfile);
}
return result;
}
#endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */