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freebsd-skq/contrib/netcat/netcat.c
Xin LI 8c54dbfb9b MFV r282611: netcat from OpenBSD 5.7. 
MFC after:	2 weeks
2015-05-07 22:54:31 +00:00

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/* $OpenBSD: netcat.c,v 1.127 2015/02/14 22:40:22 jca 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.
*
* $FreeBSD$
*/
/*
* Re-written nc(1) for OpenBSD. Original implementation by
* *Hobbit* <hobbit@avian.org>.
*/
#include <sys/limits.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <netinet/in.h>
#ifdef IPSEC
#include <netipsec/ipsec.h>
#endif
#include <netinet/tcp.h>
#include <netinet/ip.h>
#include <arpa/telnet.h>
#include <err.h>
#include <errno.h>
#include <getopt.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
#define POLL_STDIN 0
#define POLL_NETOUT 1
#define POLL_NETIN 2
#define POLL_STDOUT 3
#define BUFSIZE 16384
/* Command Line Options */
int dflag; /* detached, no stdin */
int Fflag; /* fdpass sock to stdout */
unsigned int iflag; /* Interval Flag */
int kflag; /* More than one connect */
int lflag; /* Bind to local port */
int Nflag; /* shutdown() network socket */
int nflag; /* Don't do name look up */
int FreeBSD_Oflag; /* Do not use TCP options */
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 */
int xflag; /* Socks proxy */
int zflag; /* Port Scan Flag */
int Dflag; /* sodebug */
int Iflag; /* TCP receive buffer size */
int Oflag; /* TCP send buffer size */
int Sflag; /* TCP MD5 signature option */
int Tflag = -1; /* IP Type of Service */
int rtableid = -1;
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);
void fdpass(int nfd) __attribute__((noreturn));
int remote_connect(const char *, const char *, struct addrinfo);
int timeout_connect(int, const struct sockaddr *, socklen_t);
int socks_connect(const char *, const char *, struct addrinfo,
const char *, const char *, struct addrinfo, int, const char *);
int udptest(int);
int unix_bind(char *);
int unix_connect(char *);
int unix_listen(char *);
void set_common_sockopts(int, int);
int map_tos(char *, int *);
void report_connect(const struct sockaddr *, socklen_t);
void usage(int);
ssize_t drainbuf(int, unsigned char *, size_t *);
ssize_t fillbuf(int, unsigned char *, size_t *);
#ifdef IPSEC
void add_ipsec_policy(int, char *);
char *ipsec_policy[2];
#endif
int
main(int argc, char *argv[])
{
int ch, s, ret, socksv, ipsec_count;
int numfibs;
size_t intsize = sizeof(int);
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];
struct option longopts[] = {
{ "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 },
{ NULL, 0, NULL, 0 }
};
ret = 1;
ipsec_count = 0;
s = 0;
socksv = 5;
host = NULL;
uport = NULL;
sv = NULL;
while ((ch = getopt_long(argc, argv,
"46DdEe:FhI:i:klNnoO:P:p:rSs:tT:UuV:vw:X:x:z",
longopts, NULL)) != -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 'e':
#ifdef IPSEC
ipsec_policy[ipsec_count++ % 2] = optarg;
#else
errx(1, "IPsec support unavailable.");
#endif
break;
case 'E':
#ifdef IPSEC
ipsec_policy[0] = "in ipsec esp/transport//require";
ipsec_policy[1] = "out ipsec esp/transport//require";
#else
errx(1, "IPsec support unavailable.");
#endif
break;
case 'F':
Fflag = 1;
break;
case 'h':
help();
break;
case 'i':
iflag = strtonum(optarg, 0, UINT_MAX, &errstr);
if (errstr)
errx(1, "interval %s: %s", errstr, optarg);
break;
case 'k':
kflag = 1;
break;
case 'l':
lflag = 1;
break;
case 'N':
Nflag = 1;
break;
case 'n':
nflag = 1;
break;
case 'o':
fprintf(stderr, "option -o is deprecated.\n");
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;
case 'V':
if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1)
errx(1, "Multiple FIBS not supported");
rtableid = (int)strtonum(optarg, 0,
numfibs - 1, &errstr);
if (errstr)
errx(1, "rtable %s: %s", errstr, optarg);
break;
case 'v':
vflag = 1;
break;
case 'w':
timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr);
if (errstr)
errx(1, "timeout %s: %s", errstr, optarg);
timeout *= 1000;
break;
case 'x':
xflag = 1;
if ((proxy = strdup(optarg)) == NULL)
err(1, NULL);
break;
case 'z':
zflag = 1;
break;
case 'D':
Dflag = 1;
break;
case 'I':
Iflag = strtonum(optarg, 1, 65536 << 14, &errstr);
if (errstr != NULL)
errx(1, "TCP receive window %s: %s",
errstr, optarg);
break;
case 'O':
Oflag = strtonum(optarg, 1, 65536 << 14, &errstr);
if (errstr != NULL) {
if (strcmp(errstr, "invalid") != 0)
errx(1, "TCP send window %s: %s",
errstr, optarg);
}
break;
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;
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;
}
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;
}
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 and -k, don't connect the socket, let it
* receive datagrams from multiple socket pairs.
*/
if (uflag && kflag)
readwrite(s);
/*
* For UDP and not -k, we will use recvfrom() initially
* to wait for a caller, then use the regular functions
* to talk to the caller.
*/
else if (uflag && !kflag) {
int rv, plen;
char buf[16384];
struct sockaddr_storage z;
len = sizeof(z);
plen = 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");
if (vflag)
report_connect((struct sockaddr *)&z, len);
readwrite(s);
} else {
len = sizeof(cliaddr);
connfd = accept(s, (struct sockaddr *)&cliaddr,
&len);
if (connfd == -1) {
/* For now, all errnos are fatal */
err(1, "accept");
}
if (vflag)
report_connect((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);
if (xflag)
s = socks_connect(host, portlist[i], hints,
proxyhost, proxyport, proxyhints, socksv,
Pflag);
else
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 (Fflag)
fdpass(s);
else 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, FD_CLOEXEC);
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;
#ifdef IPSEC
if (ipsec_policy[0] != NULL)
add_ipsec_policy(s, ipsec_policy[0]);
if (ipsec_policy[1] != NULL)
add_ipsec_policy(s, ipsec_policy[1]);
#endif
if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB,
&rtableid, sizeof(rtableid)) == -1))
err(1, "setsockopt SO_SETFIB");
/* Bind to a local port or source address if specified. */
if (sflag || pflag) {
struct addrinfo ahints, *ares;
/* try IP_BINDANY, but don't insist */
setsockopt(s, IPPROTO_IP, IP_BINDANY, &on, sizeof(on));
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)
err(1, "bind failed");
freeaddrinfo(ares);
}
set_common_sockopts(s, res0->ai_family);
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;
if (rtableid >= 0 && (setsockopt(s, SOL_SOCKET, SO_SETFIB,
&rtableid, sizeof(rtableid)) == -1))
err(1, "setsockopt SO_SETFIB");
ret = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &x, sizeof(x));
if (ret == -1)
err(1, NULL);
#ifdef IPSEC
if (ipsec_policy[0] != NULL)
add_ipsec_policy(s, ipsec_policy[0]);
if (ipsec_policy[1] != NULL)
add_ipsec_policy(s, ipsec_policy[1]);
#endif
if (FreeBSD_Oflag) {
if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT,
&FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1)
err(1, "disable TCP options");
}
set_common_sockopts(s, res0->ai_family);
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 net_fd)
{
struct pollfd pfd[4];
int stdin_fd = STDIN_FILENO;
int stdout_fd = STDOUT_FILENO;
unsigned char netinbuf[BUFSIZE];
size_t netinbufpos = 0;
unsigned char stdinbuf[BUFSIZE];
size_t stdinbufpos = 0;
int n, num_fds;
ssize_t ret;
/* don't read from stdin if requested */
if (dflag)
stdin_fd = -1;
/* stdin */
pfd[POLL_STDIN].fd = stdin_fd;
pfd[POLL_STDIN].events = POLLIN;
/* network out */
pfd[POLL_NETOUT].fd = net_fd;
pfd[POLL_NETOUT].events = 0;
/* network in */
pfd[POLL_NETIN].fd = net_fd;
pfd[POLL_NETIN].events = POLLIN;
/* stdout */
pfd[POLL_STDOUT].fd = stdout_fd;
pfd[POLL_STDOUT].events = 0;
while (1) {
/* both inputs are gone, buffers are empty, we are done */
if (pfd[POLL_STDIN].fd == -1 && pfd[POLL_NETIN].fd == -1
&& stdinbufpos == 0 && netinbufpos == 0) {
close(net_fd);
return;
}
/* both outputs are gone, we can't continue */
if (pfd[POLL_NETOUT].fd == -1 && pfd[POLL_STDOUT].fd == -1) {
close(net_fd);
return;
}
/* listen and net in gone, queues empty, done */
if (lflag && pfd[POLL_NETIN].fd == -1
&& stdinbufpos == 0 && netinbufpos == 0) {
close(net_fd);
return;
}
/* help says -i is for "wait between lines sent". We read and
* write arbitrary amounts of data, and we don't want to start
* scanning for newlines, so this is as good as it gets */
if (iflag)
sleep(iflag);
/* poll */
num_fds = poll(pfd, 4, timeout);
/* treat poll errors */
if (num_fds == -1) {
close(net_fd);
err(1, "polling error");
}
/* timeout happened */
if (num_fds == 0)
return;
/* treat socket error conditions */
for (n = 0; n < 4; n++) {
if (pfd[n].revents & (POLLERR|POLLNVAL)) {
pfd[n].fd = -1;
}
}
/* reading is possible after HUP */
if (pfd[POLL_STDIN].events & POLLIN &&
pfd[POLL_STDIN].revents & POLLHUP &&
! (pfd[POLL_STDIN].revents & POLLIN))
pfd[POLL_STDIN].fd = -1;
if (pfd[POLL_NETIN].events & POLLIN &&
pfd[POLL_NETIN].revents & POLLHUP &&
! (pfd[POLL_NETIN].revents & POLLIN))
pfd[POLL_NETIN].fd = -1;
if (pfd[POLL_NETOUT].revents & POLLHUP) {
if (Nflag)
shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
pfd[POLL_NETOUT].fd = -1;
}
/* if HUP, stop watching stdout */
if (pfd[POLL_STDOUT].revents & POLLHUP)
pfd[POLL_STDOUT].fd = -1;
/* if no net out, stop watching stdin */
if (pfd[POLL_NETOUT].fd == -1)
pfd[POLL_STDIN].fd = -1;
/* if no stdout, stop watching net in */
if (pfd[POLL_STDOUT].fd == -1) {
if (pfd[POLL_NETIN].fd != -1)
shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
pfd[POLL_NETIN].fd = -1;
}
/* try to read from stdin */
if (pfd[POLL_STDIN].revents & POLLIN && stdinbufpos < BUFSIZE) {
ret = fillbuf(pfd[POLL_STDIN].fd, stdinbuf,
&stdinbufpos);
/* error or eof on stdin - remove from pfd */
if (ret == 0 || ret == -1)
pfd[POLL_STDIN].fd = -1;
/* read something - poll net out */
if (stdinbufpos > 0)
pfd[POLL_NETOUT].events = POLLOUT;
/* filled buffer - remove self from polling */
if (stdinbufpos == BUFSIZE)
pfd[POLL_STDIN].events = 0;
}
/* try to write to network */
if (pfd[POLL_NETOUT].revents & POLLOUT && stdinbufpos > 0) {
ret = drainbuf(pfd[POLL_NETOUT].fd, stdinbuf,
&stdinbufpos);
if (ret == -1)
pfd[POLL_NETOUT].fd = -1;
/* buffer empty - remove self from polling */
if (stdinbufpos == 0)
pfd[POLL_NETOUT].events = 0;
/* buffer no longer full - poll stdin again */
if (stdinbufpos < BUFSIZE)
pfd[POLL_STDIN].events = POLLIN;
}
/* try to read from network */
if (pfd[POLL_NETIN].revents & POLLIN && netinbufpos < BUFSIZE) {
ret = fillbuf(pfd[POLL_NETIN].fd, netinbuf,
&netinbufpos);
if (ret == -1)
pfd[POLL_NETIN].fd = -1;
/* eof on net in - remove from pfd */
if (ret == 0) {
shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
pfd[POLL_NETIN].fd = -1;
}
/* read something - poll stdout */
if (netinbufpos > 0)
pfd[POLL_STDOUT].events = POLLOUT;
/* filled buffer - remove self from polling */
if (netinbufpos == BUFSIZE)
pfd[POLL_NETIN].events = 0;
/* handle telnet */
if (tflag)
atelnet(pfd[POLL_NETIN].fd, netinbuf,
netinbufpos);
}
/* try to write to stdout */
if (pfd[POLL_STDOUT].revents & POLLOUT && netinbufpos > 0) {
ret = drainbuf(pfd[POLL_STDOUT].fd, netinbuf,
&netinbufpos);
if (ret == -1)
pfd[POLL_STDOUT].fd = -1;
/* buffer empty - remove self from polling */
if (netinbufpos == 0)
pfd[POLL_STDOUT].events = 0;
/* buffer no longer full - poll net in again */
if (netinbufpos < BUFSIZE)
pfd[POLL_NETIN].events = POLLIN;
}
/* stdin gone and queue empty? */
if (pfd[POLL_STDIN].fd == -1 && stdinbufpos == 0) {
if (pfd[POLL_NETOUT].fd != -1 && Nflag)
shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
pfd[POLL_NETOUT].fd = -1;
}
/* net in gone and queue empty? */
if (pfd[POLL_NETIN].fd == -1 && netinbufpos == 0) {
pfd[POLL_STDOUT].fd = -1;
}
}
}
ssize_t
drainbuf(int fd, unsigned char *buf, size_t *bufpos)
{
ssize_t n;
ssize_t adjust;
n = write(fd, buf, *bufpos);
/* don't treat EAGAIN, EINTR as error */
if (n == -1 && (errno == EAGAIN || errno == EINTR))
n = -2;
if (n <= 0)
return n;
/* adjust buffer */
adjust = *bufpos - n;
if (adjust > 0)
memmove(buf, buf + n, adjust);
*bufpos -= n;
return n;
}
ssize_t
fillbuf(int fd, unsigned char *buf, size_t *bufpos)
{
size_t num = BUFSIZE - *bufpos;
ssize_t n;
n = read(fd, buf + *bufpos, num);
/* don't treat EAGAIN, EINTR as error */
if (n == -1 && (errno == EAGAIN || errno == EINTR))
n = -2;
if (n <= 0)
return n;
*bufpos += n;
return n;
}
/*
* fdpass()
* Pass the connected file descriptor to stdout and exit.
*/
void
fdpass(int nfd)
{
struct msghdr mh;
union {
struct cmsghdr hdr;
char buf[CMSG_SPACE(sizeof(int))];
} cmsgbuf;
struct cmsghdr *cmsg;
struct iovec iov;
char c = '\0';
ssize_t r;
struct pollfd pfd;
/* Avoid obvious stupidity */
if (isatty(STDOUT_FILENO))
errx(1, "Cannot pass file descriptor to tty");
bzero(&mh, sizeof(mh));
bzero(&cmsgbuf, sizeof(cmsgbuf));
bzero(&iov, sizeof(iov));
bzero(&pfd, sizeof(pfd));
mh.msg_control = (caddr_t)&cmsgbuf.buf;
mh.msg_controllen = sizeof(cmsgbuf.buf);
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
*(int *)CMSG_DATA(cmsg) = nfd;
iov.iov_base = &c;
iov.iov_len = 1;
mh.msg_iov = &iov;
mh.msg_iovlen = 1;
bzero(&pfd, sizeof(pfd));
pfd.fd = STDOUT_FILENO;
for (;;) {
r = sendmsg(STDOUT_FILENO, &mh, 0);
if (r == -1) {
if (errno == EAGAIN || errno == EINTR) {
pfd.events = POLLOUT;
if (poll(&pfd, 1, -1) == -1)
err(1, "poll");
continue;
}
err(1, "sendmsg");
} else if (r == -1)
errx(1, "sendmsg: unexpected return value %zd", r);
else
break;
}
exit(0);
}
/* 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 of 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) {
*n = '\0';
n++;
/* Make sure the ports are in order: lowest->highest. */
hi = strtonum(n, 1, PORT_MAX, &errstr);
if (errstr)
errx(1, "port number %s: %s", errstr, n);
lo = strtonum(p, 1, PORT_MAX, &errstr);
if (errstr)
errx(1, "port number %s: %s", errstr, p);
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 {
hi = strtonum(p, 1, PORT_MAX, &errstr);
if (errstr)
errx(1, "port number %s: %s", errstr, p);
portlist[0] = strdup(p);
if (portlist[0] == NULL)
err(1, NULL);
}
}
/*
* udptest()
* Do a few writes to see if the UDP port is there.
* Fails once PF state table is full.
*/
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 af)
{
int x = 1;
if (Sflag) {
if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,
&x, sizeof(x)) == -1)
err(1, NULL);
}
if (Dflag) {
if (setsockopt(s, SOL_SOCKET, SO_DEBUG,
&x, sizeof(x)) == -1)
err(1, NULL);
}
if (Tflag != -1) {
int proto, option;
if (af == AF_INET6) {
proto = IPPROTO_IPV6;
option = IPV6_TCLASS;
} else {
proto = IPPROTO_IP;
option = IP_TOS;
}
if (setsockopt(s, proto, option, &Tflag, sizeof(Tflag)) == -1)
err(1, "set IP ToS");
}
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");
}
if (FreeBSD_Oflag) {
if (setsockopt(s, IPPROTO_TCP, TCP_NOOPT,
&FreeBSD_Oflag, sizeof(FreeBSD_Oflag)) == -1)
err(1, "disable TCP options");
}
}
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);
}
void
report_connect(const struct sockaddr *sa, socklen_t salen)
{
char remote_host[NI_MAXHOST];
char remote_port[NI_MAXSERV];
int herr;
int flags = NI_NUMERICSERV;
if (nflag)
flags |= NI_NUMERICHOST;
if ((herr = getnameinfo(sa, salen,
remote_host, sizeof(remote_host),
remote_port, sizeof(remote_port),
flags)) != 0) {
if (herr == EAI_SYSTEM)
err(1, "getnameinfo");
else
errx(1, "getnameinfo: %s", gai_strerror(herr));
}
fprintf(stderr,
"Connection from %s %s "
"received!\n", remote_host, remote_port);
}
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");
#ifdef IPSEC
fprintf(stderr, "\
\t-E Use IPsec ESP\n\
\t-e policy Use specified IPsec policy\n");
#endif
fprintf(stderr, "\
\t-F Pass socket fd\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 Shutdown the network socket after EOF on stdin\n\
\t-n Suppress name/port resolutions\n\
\t--no-tcpopt Disable TCP options\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");
#ifdef IPSEC
fprintf(stderr, "See ipsec_set_policy(3) for -e argument format\n");
#endif
exit(1);
}
#ifdef IPSEC
void
add_ipsec_policy(int s, char *policy)
{
char *raw;
int e;
raw = ipsec_set_policy(policy, strlen(policy));
if (raw == NULL)
errx(1, "ipsec_set_policy `%s': %s", policy,
ipsec_strerror());
e = setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, raw,
ipsec_get_policylen(raw));
if (e < 0)
err(1, "ipsec policy cannot be configured");
free(raw);
if (vflag)
fprintf(stderr, "ipsec policy configured: `%s'\n", policy);
return;
}
#endif /* IPSEC */
void
usage(int ret)
{
fprintf(stderr,
#ifdef IPSEC
"usage: nc [-46DdEFhklNnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n"
#else
"usage: nc [-46DdFhklNnrStUuvz] [-I length] [-i interval] [-O length]\n"
#endif
"\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);
}
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