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/* vi: set sw=4 ts=4:
*
* nc: mini-netcat - Forward stdin/stdout to a file or network connection.
*
* Copyright 2007 Rob Landley <rob@landley.net>
*
* Not in SUSv3.
config NETCAT
bool "netcat"
default n
help
usage: netcat [-iwlp] {IPADDR PORTNUM|-f FILENAME} [-e COMMAND]
-e exec the rest of the command line
-i SECONDS delay after each line sent
-w SECONDS timeout for connection
-f filename use file (ala /dev/ttyS0) instead of network
-l listen for incoming connection (twice for persistent connection)
-p local port number
-s local source address
-q SECONDS quit this many seconds after EOF on stdin.
Use -l twice with -e for a quick-and-dirty server.
Use "stty 115200 -F /dev/ttyS0 && stty raw -echo -ctlecho" with
netcat -f to connect to a serial port.
*/
#include "toys.h"
#include "toynet.h"
#define TT toy.netcat
static void timeout(int signum)
{
error_exit("Timeout");
}
// Translate x.x.x.x numeric IPv4 address, or else DNS lookup an IPv4 name.
void lookup_name(char *name, uint32_t *result)
{
struct hostent *hostbyname;
hostbyname = gethostbyname(*toys.optargs);
if (!hostbyname) error_exit("name lookup failed");
*result = *(uint32_t *)*hostbyname->h_addr_list;
}
// Worry about a fancy lookup later.
void lookup_port(char *str, uint16_t *port)
{
*port = SWAP_BE16(atoi(str));
}
void netcat_main(void)
{
int sockfd, pollcount;
struct pollfd pollfds[2];
if (TT.wait) {
signal(SIGALRM, timeout);
alarm(TT.wait);
}
if (TT.filename) pollfds[0].fd = xopen(TT.filename, O_RDWR);
else {
int temp;
struct sockaddr_in address;
// The argument parsing logic can't make "<2" conditional on "-f", so...
if (!*toys.optargs || !toys.optargs[1]) {
toys.exithelp++;
error_exit("Need address and port");
}
// Setup socket
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (-1 == sockfd) perror_exit("socket");
fcntl(sockfd, F_SETFD, FD_CLOEXEC);
temp = 1;
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &temp, sizeof(temp));
memset(&address, 0, sizeof(address));
address.sin_family = AF_INET;
if (TT.port) {
address.sin_port = TT.port;
if (-1 == bind(sockfd, &address, sizeof(address)))
perror_exit("bind");
}
// Figure out where to dial out to.
lookup_name(*toys.optargs, (uint32_t *)&address.sin_addr);
lookup_port(toys.optargs[1], &address.sin_port);
temp = connect(sockfd, (struct sockaddr *)&address, sizeof(address));
if (temp<0) perror_exit("connect");
pollfds[0].fd = sockfd;
}
// We have a connection. Disarm timeout.
if (TT.wait) {
alarm(0);
signal(SIGALRM, SIG_DFL);
}
pollcount = 2;
pollfds[1].fd = 0;
pollfds[0].events = pollfds[1].events = POLLIN;
// Poll loop copying stdin->socket and socket->stdout.
for (;;) {
int i;
if (0>poll(pollfds, pollcount, -1)) perror_exit("poll");
for (i=0; i<pollcount; i++) {
if (pollfds[i].revents & POLLIN) {
int len = read(pollfds[i].fd, toybuf, sizeof(toybuf));
if (len<1) goto dohupnow;
xwrite(i ? pollfds[0].fd : 1, toybuf, len);
}
if (pollfds[i].revents & POLLHUP) {
dohupnow:
// Close half-connect. This is needed for things like
// "echo GET / | netcat landley.net 80" to work.
if (i) {
shutdown(pollfds[0].fd, SHUT_WR);
pollcount--;
} else goto cleanup;
}
}
}
cleanup:
close(pollfds[0].fd);
// close(sockfd);
}
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