/* $OpenBSD: netcat.c,v 1.103 2011/10/04 08:34:34 fgsch Exp $ */
/*
* Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Re-written nc(1) for OpenBSD. Original implementation by
* *Hobbit* <hobbit@avian.org>.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/tcp.h>
#include <netinet/ip.h>
#include <arpa/telnet.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <poll.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <limits.h>
#include "atomicio.h"
#ifndef SUN_LEN
#define SUN_LEN(su) \
(sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))
#endif
#define PORT_MAX 65535
#define PORT_MAX_LEN 6
#define UNIX_DG_TMP_SOCKET_SIZE 19
/* Command Line Options */
int dflag; /* detached, no stdin */
unsigned int iflag; /* Interval Flag */
#ifdef ANDROID
int jflag = 0;
#else
int jflag; /* use jumbo frames if we can */
#endif /* !ANDROID */
int kflag; /* More than one connect */
int lflag; /* Bind to local port */
int nflag; /* Don't do name look up */
char *Pflag; /* Proxy username */
char *pflag; /* Localport flag */
int rflag; /* Random ports flag */
char *sflag; /* Source Address */
int tflag; /* Telnet Emulation */
int uflag; /* UDP - Default to TCP */
int vflag; /* Verbosity */
#ifndef ANDROID
int xflag; /* Socks proxy */
#endif /* !ANDROID */
int zflag; /* Port Scan Flag */
int Dflag; /* sodebug */
int Iflag; /* TCP receive buffer size */
int Oflag; /* TCP send buffer size */
#ifndef ANDROID
int Sflag; /* TCP MD5 signature option */
int Tflag = -1; /* IP Type of Service */
u_int rtableid;
#endif /* !ANDROID */
int timeout = -1;
int family = AF_UNSPEC;
char *portlist[PORT_MAX+1];
char *unix_dg_tmp_socket;
void atelnet(int, unsigned char *, unsigned int);
void build_ports(char *);
void help(void);
int local_listen(char *, char *, struct addrinfo);
void readwrite(int);
int remote_connect(const char *, const char *, struct addrinfo);
int timeout_connect(int, const struct sockaddr *, socklen_t);
#ifndef ANDROID
int socks_connect(const char *, const char *, struct addrinfo,
const char *, const char *, struct addrinfo, int, const char *);
#endif /* !ANDROID */
int udptest(int);
int unix_bind(char *);
int unix_connect(char *);
int unix_listen(char *);
void set_common_sockopts(int);
int map_tos(char *, int *);
void usage(int);
int
main(int argc, char *argv[])
{
int ch, s, ret, socksv;
char *host, *uport;
struct addrinfo hints;
struct servent *sv;
socklen_t len;
struct sockaddr_storage cliaddr;
char *proxy;
const char *errstr, *proxyhost = "", *proxyport = NULL;
struct addrinfo proxyhints;
char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
ret = 1;
s = 0;
socksv = 5;
host = NULL;
uport = NULL;
sv = NULL;
while ((ch = getopt(argc, argv,
"46DdhI:i:jklnO:P:p:rSs:tT:UuV:vw:X:x:z")) != -1) {
switch (ch) {
case '4':
family = AF_INET;
break;
case '6':
family = AF_INET6;
break;
case 'U':
family = AF_UNIX;
break;
case 'X':
if (strcasecmp(optarg, "connect") == 0)
socksv = -1; /* HTTP proxy CONNECT */
else if (strcmp(optarg, "4") == 0)
socksv = 4; /* SOCKS v.4 */
else if (strcmp(optarg, "5") == 0)
socksv = 5; /* SOCKS v.5 */
else
errx(1, "unsupported proxy protocol");
break;
case 'd':
dflag = 1;
break;
case 'h':
help();
break;
case 'i':
#ifdef ANDROID
iflag = atoi(optarg);
#else
iflag = strtonum(optarg, 0, UINT_MAX, &errstr);
if (errstr)
errx(1, "interval %s: %s", errstr, optarg);
#endif /* ANDROID */
break;
#ifndef ANDROID
case 'j':
jflag = 1;
break;
#endif /* !ANDROID */
case 'k':
kflag = 1;
break;
case 'l':
lflag = 1;
break;
case 'n':
nflag = 1;
break;
case 'P':
Pflag = optarg;
break;
case 'p':
pflag = optarg;
break;
case 'r':
rflag = 1;
break;
case 's':
sflag = optarg;
break;
case 't':
tflag = 1;
break;
case 'u':
uflag = 1;
break;
#ifndef ANDROID
case 'V':
rtableid = (unsigned int)strtonum(optarg, 0,
RT_TABLEID_MAX, &errstr);
if (errstr)
errx(1, "rtable %s: %s", errstr, optarg);
break;
#endif /* !ANDROID */
case 'v':
vflag = 1;
break;
case 'w':
#ifdef ANDROID
timeout = atoi(optarg);
#else
timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr);
if (errstr)
errx(1, "timeout %s: %s", errstr, optarg);
#endif
timeout *= 1000;
break;
#ifndef ANDROID
case 'x':
xflag = 1;
if ((proxy = strdup(optarg)) == NULL)
err(1, NULL);
break;
#endif /* !ANDROID */
case 'z':
zflag = 1;
break;
case 'D':
Dflag = 1;
break;
case 'I':
#ifdef ANDROID
Iflag = atoi(optarg);
#else
Iflag = strtonum(optarg, 1, 65536 << 14, &errstr);
if (errstr != NULL)
errx(1, "TCP receive window %s: %s",
errstr, optarg);
#endif
break;
case 'O':
#ifdef ANDROID
Oflag = atoi(optarg);
#else
Oflag = strtonum(optarg, 1, 65536 << 14, &errstr);
if (errstr != NULL)
errx(1, "TCP send window %s: %s",
errstr, optarg);
#endif
break;
#ifndef ANDROID
case 'S':
Sflag = 1;
break;
case 'T':
errstr = NULL;
errno = 0;
if (map_tos(optarg, &Tflag))
break;
if (strlen(optarg) > 1 && optarg[0] == '0' &&
optarg[1] == 'x')
Tflag = (int)strtol(optarg, NULL, 16);
else
Tflag = (int)strtonum(optarg, 0, 255,
&errstr);
if (Tflag < 0 || Tflag > 255 || errstr || errno)
errx(1, "illegal tos value %s", optarg);
break;
#endif /* !ANDROID */
default:
usage(1);
}
}
argc -= optind;
argv += optind;
/* Cruft to make sure options are clean, and used properly. */
if (argv[0] && !argv[1] && family == AF_UNIX) {
host = argv[0];
uport = NULL;
} else if (argv[0] && !argv[1]) {
if (!lflag)
usage(1);
uport = argv[0];
host = NULL;
} else if (argv[0] && argv[1]) {
host = argv[0];
uport = argv[1];
} else
usage(1);
if (lflag && sflag)
errx(1, "cannot use -s and -l");
if (lflag && pflag)
errx(1, "cannot use -p and -l");
if (lflag && zflag)
errx(1, "cannot use -z and -l");
if (!lflag && kflag)
errx(1, "must use -l with -k");
/* Get name of temporary socket for unix datagram client */
if ((family == AF_UNIX) && uflag && !lflag) {
if (sflag) {
unix_dg_tmp_socket = sflag;
} else {
strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX",
UNIX_DG_TMP_SOCKET_SIZE);
if (mktemp(unix_dg_tmp_socket_buf) == NULL)
err(1, "mktemp");
unix_dg_tmp_socket = unix_dg_tmp_socket_buf;
}
}
/* Initialize addrinfo structure. */
if (family != AF_UNIX) {
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = family;
hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
if (nflag)
hints.ai_flags |= AI_NUMERICHOST;
}
#ifndef ANDROID
if (xflag) {
if (uflag)
errx(1, "no proxy support for UDP mode");
if (lflag)
errx(1, "no proxy support for listen");
if (family == AF_UNIX)
errx(1, "no proxy support for unix sockets");
/* XXX IPv6 transport to proxy would probably work */
if (family == AF_INET6)
errx(1, "no proxy support for IPv6");
if (sflag)
errx(1, "no proxy support for local source address");
proxyhost = strsep(&proxy, ":");
proxyport = proxy;
memset(&proxyhints, 0, sizeof(struct addrinfo));
proxyhints.ai_family = family;
proxyhints.ai_socktype = SOCK_STREAM;
proxyhints.ai_protocol = IPPROTO_TCP;
if (nflag)
proxyhints.ai_flags |= AI_NUMERICHOST;
}
#endif /* !ANDROID */
if (lflag) {
int connfd;
ret = 0;
if (family == AF_UNIX) {
if (uflag)
s = unix_bind(host);
else
s = unix_listen(host);
}
/* Allow only one connection at a time, but stay alive. */
for (;;) {
if (family != AF_UNIX)
s = local_listen(host, uport, hints);
if (s < 0)
err(1, NULL);
/*
* For UDP, we will use recvfrom() initially
* to wait for a caller, then use the regular
* functions to talk to the caller.
*/
if (uflag) {
int rv, plen;
char buf[16384];
struct sockaddr_storage z;
len = sizeof(z);
plen = jflag ? 16384 : 2048;
rv = recvfrom(s, buf, plen, MSG_PEEK,
(struct sockaddr *)&z, &len);
if (rv < 0)
err(1, "recvfrom");
rv = connect(s, (struct sockaddr *)&z, len);
if (rv < 0)
err(1, "connect");
readwrite(s);
} else {
len = sizeof(cliaddr);
connfd = accept(s, (struct sockaddr *)&cliaddr,
&len);
readwrite(connfd);
close(connfd);
}
if (family != AF_UNIX)
close(s);
else if (uflag) {
if (connect(s, NULL, 0) < 0)
err(1, "connect");
}
if (!kflag)
break;
}
} else if (family == AF_UNIX) {
ret = 0;
if ((s = unix_connect(host)) > 0 && !zflag) {
readwrite(s);
close(s);
} else
ret = 1;
if (uflag)
unlink(unix_dg_tmp_socket);
exit(ret);
} else {
int i = 0;
/* Construct the portlist[] array. */
build_ports(uport);
/* Cycle through portlist, connecting to each port. */
for (i = 0; portlist[i] != NULL; i++) {
if (s)
close(s);
#ifndef ANDROID
if (xflag)
s = socks_connect(host, portlist[i], hints,
proxyhost, proxyport, proxyhints, socksv,
Pflag);
else
#endif /* !ANDROID */
s = remote_connect(host, portlist[i], hints);
if (s < 0)
continue;
ret = 0;
if (vflag || zflag) {
/* For UDP, make sure we are connected. */
if (uflag) {
if (udptest(s) == -1) {
ret = 1;
continue;
}
}
/* Don't look up port if -n. */
if (nflag)
sv = NULL;
else {
sv = getservbyport(
ntohs(atoi(portlist[i])),
uflag ? "udp" : "tcp");
}
fprintf(stderr,
"Connection to %s %s port [%s/%s] "
"succeeded!\n", host, portlist[i],
uflag ? "udp" : "tcp",
sv ? sv->s_name : "*");
}
if (!zflag)
readwrite(s);
}
}
if (s)
close(s);
exit(ret);
}
/*
* unix_bind()
* Returns a unix socket bound to the given path
*/
int
unix_bind(char *path)
{
struct sockaddr_un sun;
int s;
/* Create unix domain socket. */
if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM,
0)) < 0)
return (-1);
memset(&sun, 0, sizeof(struct sockaddr_un));
sun.sun_family = AF_UNIX;
if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
sizeof(sun.sun_path)) {
close(s);
errno = ENAMETOOLONG;
return (-1);
}
if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
close(s);
return (-1);
}
return (s);
}
/*
* unix_connect()
* Returns a socket connected to a local unix socket. Returns -1 on failure.
*/
int
unix_connect(char *path)
{
struct sockaddr_un sun;
int s;
if (uflag) {
if ((s = unix_bind(unix_dg_tmp_socket)) < 0)
return (-1);
} else {
if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
return (-1);
}
(void)fcntl(s, F_SETFD, 1);
memset(&sun, 0, sizeof(struct sockaddr_un));
sun.sun_family = AF_UNIX;
if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
sizeof(sun.sun_path)) {
close(s);
errno = ENAMETOOLONG;
return (-1);
}
if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
close(s);
return (-1);
}
return (s);
}
/*
* unix_listen()
* Create a unix domain socket, and listen on it.
*/
int
unix_listen(char *path)
{
int s;
if ((s = unix_bind(path)) < 0)
return (-1);
if (listen(s, 5) < 0) {
close(s);
return (-1);
}
return (s);
}
/*
* remote_connect()
* Returns a socket connected to a remote host. Properly binds to a local
* port or source address if needed. Returns -1 on failure.
*/
int
remote_connect(const char *host, const char *port, struct addrinfo hints)
{
struct addrinfo *res, *res0;
int s, error, on = 1;
if ((error = getaddrinfo(host, port, &hints, &res)))
errx(1, "getaddrinfo: %s", gai_strerror(error));
res0 = res;
do {
if ((s = socket(res0->ai_family, res0->ai_socktype,
res0->ai_protocol)) < 0)
continue;
#ifndef ANDROID
if (rtableid) {
if (setsockopt(s, SOL_SOCKET, SO_RTABLE, &rtableid,
sizeof(rtableid)) == -1)
err(1, "setsockopt SO_RTABLE");
}
#endif /* !ANDROID */
/* Bind to a local port or source address if specified. */
if (sflag || pflag) {
struct addrinfo ahints, *ares;
#ifndef ANDROID
/* try SO_BINDANY, but don't insist */
setsockopt(s, SOL_SOCKET, SO_BINDANY, &on, sizeof(on));
#endif /* !ANDROID */
memset(&ahints, 0, sizeof(struct addrinfo));
ahints.ai_family = res0->ai_family;
ahints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
ahints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
ahints.ai_flags = AI_PASSIVE;
if ((error = getaddrinfo(sflag, pflag, &ahints, &ares)))
errx(1, "getaddrinfo: %s", gai_strerror(error));
if (bind(s, (struct sockaddr *)ares->ai_addr,
ares->ai_addrlen) < 0)
errx(1, "bind failed: %s", strerror(errno));
freeaddrinfo(ares);
}
set_common_sockopts(s);
if (timeout_connect(s, res0->ai_addr, res0->ai_addrlen) == 0)
break;
else if (vflag)
warn("connect to %s port %s (%s) failed", host, port,
uflag ? "udp" : "tcp");
close(s);
s = -1;
} while ((res0 = res0->ai_next) != NULL);
freeaddrinfo(res);
return (s);
}
int
timeout_connect(int s, const struct sockaddr *name, socklen_t namelen)
{
struct pollfd pfd;
socklen_t optlen;
int flags, optval;
int ret;
if (timeout != -1) {
flags = fcntl(s, F_GETFL, 0);
if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1)
err(1, "set non-blocking mode");
}
if ((ret = connect(s, name, namelen)) != 0 && errno == EINPROGRESS) {
pfd.fd = s;
pfd.events = POLLOUT;
if ((ret = poll(&pfd, 1, timeout)) == 1) {
optlen = sizeof(optval);
if ((ret = getsockopt(s, SOL_SOCKET, SO_ERROR,
&optval, &optlen)) == 0) {
errno = optval;
ret = optval == 0 ? 0 : -1;
}
} else if (ret == 0) {
errno = ETIMEDOUT;
ret = -1;
} else
err(1, "poll failed");
}
if (timeout != -1 && fcntl(s, F_SETFL, flags) == -1)
err(1, "restoring flags");
return (ret);
}
/*
* local_listen()
* Returns a socket listening on a local port, binds to specified source
* address. Returns -1 on failure.
*/
int
local_listen(char *host, char *port, struct addrinfo hints)
{
struct addrinfo *res, *res0;
int s, ret, x = 1;
int error;
/* Allow nodename to be null. */
hints.ai_flags |= AI_PASSIVE;
/*
* In the case of binding to a wildcard address
* default to binding to an ipv4 address.
*/
if (host == NULL && hints.ai_family == AF_UNSPEC)
hints.ai_family = AF_INET;
if ((error = getaddrinfo(host, port, &hints, &res)))
errx(1, "getaddrinfo: %s", gai_strerror(error));
res0 = res;
do {
if ((s = socket(res0->ai_family, res0->ai_socktype,
res0->ai_protocol)) < 0)
continue;
#ifndef ANDROID
if (rtableid) {
if (setsockopt(s, IPPROTO_IP, SO_RTABLE, &rtableid,
sizeof(rtableid)) == -1)
err(1, "setsockopt SO_RTABLE");
}
#endif /* !ANDROID */
#ifdef ANDROID
ret = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &x, sizeof(x));
#else
ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x));
#endif
if (ret == -1)
err(1, NULL);
set_common_sockopts(s);
if (bind(s, (struct sockaddr *)res0->ai_addr,
res0->ai_addrlen) == 0)
break;
close(s);
s = -1;
} while ((res0 = res0->ai_next) != NULL);
if (!uflag && s != -1) {
if (listen(s, 1) < 0)
err(1, "listen");
}
freeaddrinfo(res);
return (s);
}
/*
* readwrite()
* Loop that polls on the network file descriptor and stdin.
*/
void
readwrite(int nfd)
{
struct pollfd pfd[2];
unsigned char buf[16384];
int n, wfd = fileno(stdin);
int lfd = fileno(stdout);
int plen;
plen = jflag ? 16384 : 2048;
/* Setup Network FD */
pfd[0].fd = nfd;
pfd[0].events = POLLIN;
/* Set up STDIN FD. */
pfd[1].fd = wfd;
pfd[1].events = POLLIN;
while (pfd[0].fd != -1) {
if (iflag)
sleep(iflag);
if ((n = poll(pfd, 2 - dflag, timeout)) < 0) {
close(nfd);
err(1, "Polling Error");
}
if (n == 0)
return;
if (pfd[0].revents & POLLIN) {
if ((n = read(nfd, buf, plen)) < 0)
return;
else if (n == 0) {
shutdown(nfd, SHUT_RD);
pfd[0].fd = -1;
pfd[0].events = 0;
} else {
if (tflag)
atelnet(nfd, buf, n);
if (atomicio(vwrite, lfd, buf, n) != n)
return;
}
}
if (!dflag && pfd[1].revents & POLLIN) {
if ((n = read(wfd, buf, plen)) < 0)
return;
else if (n == 0) {
shutdown(nfd, SHUT_WR);
pfd[1].fd = -1;
pfd[1].events = 0;
} else {
if (atomicio(vwrite, nfd, buf, n) != n)
return;
}
}
}
}
/* Deal with RFC 854 WILL/WONT DO/DONT negotiation. */
void
atelnet(int nfd, unsigned char *buf, unsigned int size)
{
unsigned char *p, *end;
unsigned char obuf[4];
if (size < 3)
return;
end = buf + size - 2;
for (p = buf; p < end; p++) {
if (*p != IAC)
continue;
obuf[0] = IAC;
p++;
if ((*p == WILL) || (*p == WONT))
obuf[1] = DONT;
else if ((*p == DO) || (*p == DONT))
obuf[1] = WONT;
else
continue;
p++;
obuf[2] = *p;
if (atomicio(vwrite, nfd, obuf, 3) != 3)
warn("Write Error!");
}
}
/*
* build_ports()
* Build an array or ports in portlist[], listing each port
* that we should try to connect to.
*/
void
build_ports(char *p)
{
const char *errstr;
char *n;
int hi, lo, cp;
int x = 0;
if ((n = strchr(p, '-')) != NULL) {
if (lflag)
errx(1, "Cannot use -l with multiple ports!");
*n = '\0';
n++;
/* Make sure the ports are in order: lowest->highest. */
#ifdef ANDROID
hi = atoi(n);
#else
hi = strtonum(n, 1, PORT_MAX, &errstr);
if (errstr)
errx(1, "port number %s: %s", errstr, n);
#endif
#ifdef ANDROID
lo = atoi(p);
#else
lo = strtonum(p, 1, PORT_MAX, &errstr);
if (errstr)
errx(1, "port number %s: %s", errstr, p);
#endif
if (lo > hi) {
cp = hi;
hi = lo;
lo = cp;
}
/* Load ports sequentially. */
for (cp = lo; cp <= hi; cp++) {
portlist[x] = calloc(1, PORT_MAX_LEN);
if (portlist[x] == NULL)
err(1, NULL);
snprintf(portlist[x], PORT_MAX_LEN, "%d", cp);
x++;
}
/* Randomly swap ports. */
if (rflag) {
int y;
char *c;
for (x = 0; x <= (hi - lo); x++) {
y = (arc4random() & 0xFFFF) % (hi - lo);
c = portlist[x];
portlist[x] = portlist[y];
portlist[y] = c;
}
}
} else {
#ifdef ANDROID
hi = atoi(p);
#else
hi = strtonum(p, 1, PORT_MAX, &errstr);
if (errstr)
errx(1, "port number %s: %s", errstr, p);
#endif
portlist[0] = strdup(p);
if (portlist[0] == NULL)
err(1, NULL);
}
}
/*
* udptest()
* Do a few writes to see if the UDP port is there.
* XXX - Better way of doing this? Doesn't work for IPv6.
* Also fails after around 100 ports checked.
*/
int
udptest(int s)
{
int i, ret;
for (i = 0; i <= 3; i++) {
if (write(s, "X", 1) == 1)
ret = 1;
else
ret = -1;
}
return (ret);
}
void
set_common_sockopts(int s)
{
int x = 1;
#ifndef ANDROID
if (Sflag) {
if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,
&x, sizeof(x)) == -1)
err(1, NULL);
}
#endif
if (Dflag) {
if (setsockopt(s, SOL_SOCKET, SO_DEBUG,
&x, sizeof(x)) == -1)
err(1, NULL);
}
#ifndef ANDROID
if (jflag) {
if (setsockopt(s, SOL_SOCKET, SO_JUMBO,
&x, sizeof(x)) == -1)
err(1, NULL);
}
if (Tflag != -1) {
if (setsockopt(s, IPPROTO_IP, IP_TOS,
&Tflag, sizeof(Tflag)) == -1)
err(1, "set IP ToS");
}
#endif
if (Iflag) {
if (setsockopt(s, SOL_SOCKET, SO_RCVBUF,
&Iflag, sizeof(Iflag)) == -1)
err(1, "set TCP receive buffer size");
}
if (Oflag) {
if (setsockopt(s, SOL_SOCKET, SO_SNDBUF,
&Oflag, sizeof(Oflag)) == -1)
err(1, "set TCP send buffer size");
}
}
#ifndef ANDROID
int
map_tos(char *s, int *val)
{
/* DiffServ Codepoints and other TOS mappings */
const struct toskeywords {
const char *keyword;
int val;
} *t, toskeywords[] = {
{ "af11", IPTOS_DSCP_AF11 },
{ "af12", IPTOS_DSCP_AF12 },
{ "af13", IPTOS_DSCP_AF13 },
{ "af21", IPTOS_DSCP_AF21 },
{ "af22", IPTOS_DSCP_AF22 },
{ "af23", IPTOS_DSCP_AF23 },
{ "af31", IPTOS_DSCP_AF31 },
{ "af32", IPTOS_DSCP_AF32 },
{ "af33", IPTOS_DSCP_AF33 },
{ "af41", IPTOS_DSCP_AF41 },
{ "af42", IPTOS_DSCP_AF42 },
{ "af43", IPTOS_DSCP_AF43 },
{ "critical", IPTOS_PREC_CRITIC_ECP },
{ "cs0", IPTOS_DSCP_CS0 },
{ "cs1", IPTOS_DSCP_CS1 },
{ "cs2", IPTOS_DSCP_CS2 },
{ "cs3", IPTOS_DSCP_CS3 },
{ "cs4", IPTOS_DSCP_CS4 },
{ "cs5", IPTOS_DSCP_CS5 },
{ "cs6", IPTOS_DSCP_CS6 },
{ "cs7", IPTOS_DSCP_CS7 },
{ "ef", IPTOS_DSCP_EF },
{ "inetcontrol", IPTOS_PREC_INTERNETCONTROL },
{ "lowdelay", IPTOS_LOWDELAY },
{ "netcontrol", IPTOS_PREC_NETCONTROL },
{ "reliability", IPTOS_RELIABILITY },
{ "throughput", IPTOS_THROUGHPUT },
{ NULL, -1 },
};
for (t = toskeywords; t->keyword != NULL; t++) {
if (strcmp(s, t->keyword) == 0) {
*val = t->val;
return (1);
}
}
return (0);
}
#endif
void
help(void)
{
usage(0);
fprintf(stderr, "\tCommand Summary:\n\
\t-4 Use IPv4\n\
\t-6 Use IPv6\n\
\t-D Enable the debug socket option\n\
\t-d Detach from stdin\n\
\t-h This help text\n\
\t-I length TCP receive buffer length\n\
\t-i secs\t Delay interval for lines sent, ports scanned\n\
\t-k Keep inbound sockets open for multiple connects\n\
\t-l Listen mode, for inbound connects\n\
\t-n Suppress name/port resolutions\n\
\t-O length TCP send buffer length\n\
\t-P proxyuser\tUsername for proxy authentication\n\
\t-p port\t Specify local port for remote connects\n\
\t-r Randomize remote ports\n\
\t-S Enable the TCP MD5 signature option\n\
\t-s addr\t Local source address\n\
\t-T toskeyword\tSet IP Type of Service\n\
\t-t Answer TELNET negotiation\n\
\t-U Use UNIX domain socket\n\
\t-u UDP mode\n\
\t-V rtable Specify alternate routing table\n\
\t-v Verbose\n\
\t-w secs\t Timeout for connects and final net reads\n\
\t-X proto Proxy protocol: \"4\", \"5\" (SOCKS) or \"connect\"\n\
\t-x addr[:port]\tSpecify proxy address and port\n\
\t-z Zero-I/O mode [used for scanning]\n\
Port numbers can be individual or ranges: lo-hi [inclusive]\n");
exit(1);
}
void
usage(int ret)
{
fprintf(stderr,
"usage: nc [-46DdhklnrStUuvz] [-I length] [-i interval] [-O length]\n"
"\t [-P proxy_username] [-p source_port] [-s source] [-T ToS]\n"
"\t [-V rtable] [-w timeout] [-X proxy_protocol]\n"
"\t [-x proxy_address[:port]] [destination] [port]\n");
if (ret)
exit(1);
}