busybox/nc.c

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/* vi: set sw=4 ts=4: */
/* nc: mini-netcat - built from the ground up for LRP
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Copyright (C) 1998 Charles P. Wright
0.0.1 6K It works.
0.0.2 5K Smaller and you can also check the exit condition if you wish.
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0.0.3 Uses select()
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19980918 Busy Boxed! Dave Cinege
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19990512 Uses Select. Charles P. Wright
19990513 Fixes stdin stupidity and uses buffers. Charles P. Wright
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This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/time.h>
#include <sys/ioctl.h>
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#define BUFSIZE 100
static const char nc_usage[] = "nc [IP] [port]\n"
#ifndef BB_FEATURE_TRIVIAL_HELP
"\nNetcat opens a pipe to IP:port\n"
#endif
;
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int nc_main(int argc, char **argv)
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{
int sfd;
int result;
int len;
char ch[BUFSIZE];
struct sockaddr_in address;
struct hostent *hostinfo;
fd_set readfds, testfds;
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argc--;
argv++;
if (argc < 2 || **(argv + 1) == '-') {
usage(nc_usage);
}
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sfd = socket(AF_INET, SOCK_STREAM, 0);
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hostinfo = (struct hostent *) gethostbyname(*argv);
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if (!hostinfo) {
fatalError("nc: cannot resolve %s\n", *argv);
}
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address.sin_family = AF_INET;
address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
address.sin_port = htons(atoi(*(++argv)));
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len = sizeof(address);
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result = connect(sfd, (struct sockaddr *) &address, len);
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if (result < 0) {
perror("nc: connect");
exit(2);
}
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FD_ZERO(&readfds);
FD_SET(sfd, &readfds);
FD_SET(fileno(stdin), &readfds);
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while (1) {
int fd;
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int ofd;
int nread;
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testfds = readfds;
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result =
select(FD_SETSIZE, &testfds, (fd_set *) NULL, (fd_set *) NULL,
(struct timeval *) 0);
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if (result < 1) {
perror("nc: select");
exit(3);
}
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for (fd = 0; fd < FD_SETSIZE; fd++) {
if (FD_ISSET(fd, &testfds)) {
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int trn = 0;
int rn;
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ioctl(fd, FIONREAD, &nread);
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if (fd == sfd) {
if (nread == 0)
exit(0);
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ofd = fileno(stdout);
} else {
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ofd = sfd;
}
do {
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rn = (BUFSIZE < nread - trn) ? BUFSIZE : nread - trn;
trn += rn;
read(fd, ch, rn);
write(ofd, ch, rn);
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}
while (trn < nread);
}
}
}
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}