HI
Can anyone provide me with codes for file transfer server to client or vice versa?
Also please explain how to compile those programs in ubuntu terminal as i am totally new to socket programming.
Thanks
Client is one code, Server is another.
You use C, traditionally, but now sockets are available in all languages. An example tcp/ip server I wrote is around here somewhere, u_inetd.c: Is this case is normal when programming in socket? It just listens and executes the server instance, so the server needs no sockets code unless you want to rewrite something ugly like FTP itself. This is like UNIX inetd, but for high ports, one app each and no root needed! If you find code for tcp_relay.c, it is a tcp server that for every connection fires up a client and shuffles the data back and forth, so all tcp code is in there. Sockets can do udp, too, and other protocols peer to tcp and udp, by raw IP packet sockets.
There are many tutorials on each language, sockets in it, and ubuntu can run them all.
Now, are you writing your own file transfer protocol, and why?
Here is tcp_relay.c as I last used it:
$ cat mysrc/tcp_relay.c
/* This software is Copyright 1995, 1996 by Karl-Johan Johnsson
* Modified by Voon-Li Chung to allow access from any host
*
* Permission is hereby granted to copy, reproduce, redistribute or otherwise
* use this software as long as: there is no monetary profit gained
* specifically from the use or reproduction of this software, it is not
* sold, rented, traded or otherwise marketed, and this copyright notice is
* included prominently in any copy made.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. ANY USE OF THIS
* SOFTWARE IS AT THE USER'S OWN RISK.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/wait.h>
#undef False
#define False 0
#undef True
#define True 1
#define DEFAULT_REMOTE_PORT 119
/*
* Define this if <unistd.h> doesn't declare getopt() and friends.
*/
#define BOGUS_UNISTD
static void perror_exit(const char *msg)
{
perror(msg);
_exit(1);
}
static void* xrealloc(void *ptr, size_t size)
{
if (!ptr)
ptr = malloc(size); /* Hack for broken C libraries */
else
ptr = realloc(ptr, size);
if (!ptr)
perror_exit("malloc");
return ptr;
}
static struct sockaddr_in get_remote_host(char *host)
{
struct sockaddr_in addr;
struct hostent *hent;
char *c;
memset(&addr, 0, sizeof addr);
addr.sin_family = PF_INET;
addr.sin_port = htons(DEFAULT_REMOTE_PORT);
c = strchr(host, ':');
if (c) {
*c++ = '\0';
/* FIXME: error check? */
addr.sin_port = htons(atoi(c));
}
hent = gethostbyname(host);
if (!hent) {
fprintf(stderr, "No such host: %s\n", host);
_exit(1);
}
memcpy(&addr.sin_addr, hent->h_addr, hent->h_length);
return addr;
}
static int do_rw(int from, int to)
{
static char buffer[16384];
char *c;
long i, j, n;
do {
n = read(from, buffer, sizeof buffer);
} while (n < 0 && errno == EINTR);
c = buffer;
i = n;
while (i > 0) {
j = write(to, c, i);
if (j < 0)
if (errno == EINTR)
continue;
else
return -1;
if (j == 0)
return 0;
c += j;
i -= j;
}
return n;
}
static int open_serv_socket(struct sockaddr_in *serv_addr)
{
int ss, tmp;
ss = socket(PF_INET, SOCK_STREAM, 0);
if (ss < 0)
return -1;
do {
tmp = connect(ss, (struct sockaddr *)serv_addr, sizeof *serv_addr);
} while (tmp < 0 && errno == EINTR);
if (tmp < 0) {
perror("connect");
close(ss);
return -1;
}
return ss;
}
static int child(struct sockaddr_in *serv_addr, int cs)
{
fd_set fds;
int max, ss, tmp = 0;
ss = open_serv_socket(serv_addr);
if (ss < 0)
return -1;
FD_ZERO(&fds);
FD_SET(cs, &fds);
FD_SET(ss, &fds);
max = (cs > ss ? cs : ss) + 1;
for (;;) {
fd_set rd_fds = fds;
tmp = select(max, &rd_fds, NULL, NULL, NULL);
if (tmp < 0)
if (errno == EINTR)
continue;
else
break;
if (FD_ISSET(cs, &rd_fds)) {
tmp = do_rw(cs, ss);
if (tmp <= 0)
break;
}
if (FD_ISSET(ss, &rd_fds)) {
tmp = do_rw(ss, cs);
if (tmp <= 0)
break;
}
}
if (tmp < 0)
perror("read/write");
close(ss);
return tmp;
}
static void doit(struct sockaddr_in *serv_addr, int port, int single)
{
struct sockaddr_in local_addr, cli_addr;
int as;
int yes = 1;
memset(&local_addr, 0, sizeof local_addr);
local_addr.sin_family = PF_INET;
local_addr.sin_port = port;
as = socket(PF_INET, SOCK_STREAM, 0);
if (as < 0)
perror_exit("socket");
if (setsockopt(as, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof yes) < 0)
perror_exit("setsockopt(SO_REUSEADDR)");
if (bind(as, (struct sockaddr *)&local_addr, sizeof local_addr) < 0)
perror_exit("bind");
if (listen(as, 5) < 0)
perror_exit("listen");
for (;;) {
int cs, len;
do {
len = sizeof cli_addr;
cs = accept(as, (struct sockaddr *)&cli_addr, &len);
} while (cs < 0 && errno == EINTR);
if (cs < 0)
perror_exit("accept");
if (single)
child(serv_addr, cs);
else
switch (fork()) {
case -1:
perror_exit("fork");
break;
case 0:
if (child(serv_addr, cs) < 0)
_exit(1);
default:
break;
}
close(cs);
}
}
/************************************************************************/
static void sig_chld(int no)
{
while (waitpid(-1, NULL, WNOHANG) > 0);
}
static void install_sig_handlers(void)
{
struct sigaction sig_act;
sig_act.sa_handler = sig_chld;
sig_act.sa_flags = 0;
sigfillset(&sig_act.sa_mask);
if (sigaction(SIGCHLD, &sig_act, NULL) < 0)
perror_exit("sigaction(SIGCHLD)");
sig_act.sa_handler = SIG_IGN;
sig_act.sa_flags = 0;
sigemptyset(&sig_act.sa_mask);
if (sigaction(SIGPIPE, &sig_act, NULL) < 0)
perror_exit("sigaction(SIGPIPE)");
}
static void usage(char *name)
{
fprintf(stderr, "Usage: %s -p port [-s] remotehost:port\n",
name);
_exit(1);
}
int main(int argc, char *argv[])
{
struct sockaddr_in serv_addr;
int single = False;
int port = 0;
int c;
#ifdef BOGUS_UNISTD
extern int getopt(int, char *const[], const char*);
extern char *optarg;
extern int optind, opterr;
#endif
freopen("/dev/null", "r", stdin);
freopen("/dev/null", "w", stdout);
install_sig_handlers();
opterr = 0;
while ((c = getopt(argc, argv, "p:h:s")) != -1)
switch (c) {
case 'p': /* port to listen on */
if (sscanf(optarg, "%d", &port) != 1 || port < 0)
usage(argv[0]);
port = htons(port);
break;
case 's':
single = True;
break;
default:
usage(argv[0]);
break;
}
if (optind != argc - 1 || port == 0)
usage(argv[0]);
serv_addr = get_remote_host(argv[optind]);
doit(&serv_addr, port, single);
return 0;
}