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/* netcat.c - Forward stdin/stdout to a file or network connection.
*
* Copyright 2007 Rob Landley <rob@landley.net>
*
* TODO: udp, ipv6, genericize for telnet/microcom/tail-f
* fix -t, xconnect
* netcat -L zombies
USE_NETCAT(OLDTOY(nc, netcat, TOYFLAG_USR|TOYFLAG_BIN))
USE_NETCAT(NEWTOY(netcat, USE_NETCAT_LISTEN("^tlL")"w#<1W#<1p#<1>65535q#<1s:f:"USE_NETCAT_LISTEN("[!tlL][!Lw]"), TOYFLAG_BIN))
config NETCAT
bool "netcat"
default y
help
usage: netcat [-u] [-wpq #] [-s addr] {IPADDR PORTNUM|-f FILENAME}
-f Use FILENAME (ala /dev/ttyS0) instead of network
-p Local port number
-q Quit SECONDS after EOF on stdin, even if stdout hasn't closed yet
-s Local source address
-w SECONDS timeout to establish connection
-W SECONDS timeout for more data on an idle connection
Use "stty 115200 -F /dev/ttyS0 && stty raw -echo -ctlecho" with
netcat -f to connect to a serial port.
config NETCAT_LISTEN
bool "netcat server options (-let)"
default y
depends on NETCAT
help
usage: netcat [-t] [-lL COMMAND...]
-l Listen for one incoming connection
-L Listen for multiple incoming connections (server mode)
-t Allocate tty (must come before -l or -L)
The command line after -l or -L is executed (as a child process) to handle
each incoming connection. If blank -l waits for a connection and forwards
it to stdin/stdout. If no -p specified, -l prints port it bound to and
backgrounds itself (returning immediately).
For a quick-and-dirty server, try something like:
netcat -s 127.0.0.1 -p 1234 -tL /bin/bash -l
*/
#define FOR_netcat
#include "toys.h"
GLOBALS(
char *f, *s;
long q, p, W, w;
)
static void timeout(int signum)
{
if (TT.w) error_exit("Timeout");
// TODO This should be xexit() but would need siglongjmp()...
exit(0);
}
static void set_alarm(int seconds)
{
xsignal(SIGALRM, seconds ? timeout : SIG_DFL);
alarm(seconds);
}
// Translate x.x.x.x numeric IPv4 address, or else DNS lookup an IPv4 name.
static void lookup_name(char *name, uint32_t *result)
{
struct hostent *hostbyname;
hostbyname = gethostbyname(name); // getaddrinfo
if (!hostbyname) error_exit("no host '%s'", name);
*result = *(uint32_t *)*hostbyname->h_addr_list;
}
// Worry about a fancy lookup later.
static unsigned short lookup_port(char *str)
{
struct servent *se;
int i = atoi(str);
if (i>0 && i<65536) return SWAP_BE16(i);
se = getservbyname(str, "tcp");
i = se ? se->s_port : 0;
endservent();
return i;
}
void netcat_main(void)
{
struct sockaddr_in *address = (void *)toybuf;
int sockfd=-1, in1 = 0, in2 = 0, out1 = 1, out2 = 1;
pid_t child;
// Addjust idle and quit_delay to miliseconds or -1 for no timeout
TT.W = TT.W ? TT.W*1000 : -1;
TT.q = TT.q ? TT.q*1000 : -1;
set_alarm(TT.w);
// The argument parsing logic can't make "<2" conditional on other
// arguments like -f and -l, so do it by hand here.
if ((toys.optflags&FLAG_f) ? toys.optc :
(!(toys.optflags&(FLAG_l|FLAG_L)) && toys.optc!=2))
help_exit("bad argument count");
if (TT.f) in1 = out2 = xopen(TT.f, O_RDWR);
else {
// Setup socket
sockfd = xsocket(AF_INET, SOCK_STREAM, 0);
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &out1, sizeof(out1));
address->sin_family = AF_INET;
if (TT.s || TT.p) {
address->sin_port = SWAP_BE16(TT.p);
if (TT.s)
lookup_name(TT.s, (uint32_t *)&(address->sin_addr));
if (bind(sockfd, (struct sockaddr *)address, sizeof(*address)))
perror_exit("bind");
}
// Dial out
if (!(toys.optflags&(FLAG_L|FLAG_l))) {
// Figure out where to dial out to.
lookup_name(*toys.optargs, (uint32_t *)&(address->sin_addr));
address->sin_port = lookup_port(toys.optargs[1]);
// TODO xconnect
if (connect(sockfd, (struct sockaddr *)address, sizeof(*address))<0)
perror_exit("connect");
// We have a connection. Disarm timeout.
set_alarm(0);
in1 = out2 = sockfd;
pollinate(in1, in2, out1, out2, TT.W, TT.q);
} else {
// Listen for incoming connections
socklen_t len = sizeof(*address);
if (listen(sockfd, 5)) error_exit("listen");
if (!TT.p) {
getsockname(sockfd, (struct sockaddr *)address, &len);
printf("%d\n", SWAP_BE16(address->sin_port));
fflush(stdout);
// Return immediately if no -p and -Ll has arguments, so wrapper
// script can use port number.
if (CFG_TOYBOX_FORK && toys.optc && xfork()) goto cleanup;
}
do {
child = 0;
in1 = out2 = accept(sockfd, (struct sockaddr *)address, &len);
if (in1<0) perror_exit("accept");
// We have a connection. Disarm timeout.
set_alarm(0);
if (toys.optc) {
// Do we need a tty?
// TODO nommu, and -t only affects server mode...? Only do -t with optc
// if (CFG_TOYBOX_FORK && (toys.optflags&FLAG_t))
// child = forkpty(&fdout, NULL, NULL, NULL);
// else
// Do we need to fork and/or redirect for exec?
if (toys.optflags&FLAG_L) NOEXIT(child = XVFORK());
if (child) {
close(in1);
continue;
}
dup2(in1, 0);
dup2(in1, 1);
if (toys.optflags&FLAG_L) dup2(in1, 2);
if (in1>2) close(in1);
xexec(toys.optargs);
}
pollinate(in1, in2, out1, out2, TT.W, TT.q);
close(in1);
} while (!(toys.optflags&FLAG_l));
}
}
cleanup:
if (CFG_TOYBOX_FREE) {
close(in1);
close(sockfd);
}
}
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