1123 lines
25 KiB
C
1123 lines
25 KiB
C
/* $OpenBSD: netcat.c,v 1.105 2012/02/09 06:25:35 lum Exp $ */
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/*
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* Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Re-written nc(1) for OpenBSD. Original implementation by
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* *Hobbit* <hobbit@avian.org>.
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*/
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#include <sys/limits.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/sysctl.h>
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#include <sys/time.h>
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#include <sys/un.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#ifdef IPSEC
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#include <netipsec/ipsec.h>
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#endif
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#include <netinet/tcp.h>
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#include <netinet/ip.h>
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#include <arpa/telnet.h>
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#include <err.h>
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#include <errno.h>
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#include <getopt.h>
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#include <netdb.h>
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#include <poll.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <limits.h>
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#include "atomicio.h"
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#ifndef SUN_LEN
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#define SUN_LEN(su) \
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(sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))
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#endif
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#define PORT_MAX 65535
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#define PORT_MAX_LEN 6
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#define UNIX_DG_TMP_SOCKET_SIZE 19
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/* Command Line Options */
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int dflag; /* detached, no stdin */
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unsigned int iflag; /* Interval Flag */
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int jflag; /* use jumbo frames if we can */
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int kflag; /* More than one connect */
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int lflag; /* Bind to local port */
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int nflag; /* Don't do name look up */
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int FreeBSD_Oflag; /* Do not use TCP options */
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char *Pflag; /* Proxy username */
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char *pflag; /* Localport flag */
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int rflag; /* Random ports flag */
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char *sflag; /* Source Address */
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int tflag; /* Telnet Emulation */
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int uflag; /* UDP - Default to TCP */
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int vflag; /* Verbosity */
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int xflag; /* Socks proxy */
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int zflag; /* Port Scan Flag */
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int Dflag; /* sodebug */
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int Iflag; /* TCP receive buffer size */
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int Oflag; /* TCP send buffer size */
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int Sflag; /* TCP MD5 signature option */
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int Tflag = -1; /* IP Type of Service */
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u_int rtableid;
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int timeout = -1;
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int family = AF_UNSPEC;
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char *portlist[PORT_MAX+1];
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char *unix_dg_tmp_socket;
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void atelnet(int, unsigned char *, unsigned int);
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void build_ports(char *);
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void help(void);
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int local_listen(char *, char *, struct addrinfo);
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void readwrite(int);
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int remote_connect(const char *, const char *, struct addrinfo);
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int timeout_connect(int, const struct sockaddr *, socklen_t);
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int socks_connect(const char *, const char *, struct addrinfo,
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const char *, const char *, struct addrinfo, int, const char *);
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int udptest(int);
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int unix_bind(char *);
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int unix_connect(char *);
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int unix_listen(char *);
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void set_common_sockopts(int);
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int map_tos(char *, int *);
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void usage(int);
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#ifdef IPSEC
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void add_ipsec_policy(int, char *);
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char *ipsec_policy[2];
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#endif
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int
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main(int argc, char *argv[])
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{
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int ch, s, ret, socksv, ipsec_count;
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int numfibs;
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size_t intsize = sizeof(int);
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char *host, *uport;
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struct addrinfo hints;
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struct servent *sv;
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socklen_t len;
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struct sockaddr_storage cliaddr;
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char *proxy;
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const char *errstr, *proxyhost = "", *proxyport = NULL;
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struct addrinfo proxyhints;
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char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
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struct option longopts[] = {
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{ "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 },
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{ NULL, 0, NULL, 0 }
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};
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ret = 1;
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ipsec_count = 0;
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s = 0;
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socksv = 5;
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host = NULL;
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uport = NULL;
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sv = NULL;
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while ((ch = getopt_long(argc, argv,
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"46DdEe:hI:i:jklnoO:P:p:rSs:tT:UuV:vw:X:x:z",
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longopts, NULL)) != -1) {
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switch (ch) {
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case '4':
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family = AF_INET;
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break;
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case '6':
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family = AF_INET6;
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break;
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case 'U':
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family = AF_UNIX;
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break;
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case 'X':
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if (strcasecmp(optarg, "connect") == 0)
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socksv = -1; /* HTTP proxy CONNECT */
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else if (strcmp(optarg, "4") == 0)
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socksv = 4; /* SOCKS v.4 */
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else if (strcmp(optarg, "5") == 0)
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socksv = 5; /* SOCKS v.5 */
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else
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errx(1, "unsupported proxy protocol");
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break;
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case 'd':
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dflag = 1;
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break;
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case 'e':
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#ifdef IPSEC
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ipsec_policy[ipsec_count++ % 2] = optarg;
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#else
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errx(1, "IPsec support unavailable.");
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#endif
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break;
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case 'E':
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#ifdef IPSEC
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ipsec_policy[0] = "in ipsec esp/transport//require";
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ipsec_policy[1] = "out ipsec esp/transport//require";
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#else
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errx(1, "IPsec support unavailable.");
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#endif
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break;
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case 'h':
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help();
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break;
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case 'i':
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iflag = strtonum(optarg, 0, UINT_MAX, &errstr);
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if (errstr)
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errx(1, "interval %s: %s", errstr, optarg);
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break;
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#ifdef SO_JUMBO
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case 'j':
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jflag = 1;
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break;
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#endif
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case 'k':
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kflag = 1;
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break;
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case 'l':
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lflag = 1;
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break;
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case 'n':
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nflag = 1;
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break;
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case 'o':
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fprintf(stderr, "option -o is deprecated.\n");
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break;
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case 'P':
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Pflag = optarg;
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break;
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case 'p':
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pflag = optarg;
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break;
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case 'r':
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rflag = 1;
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break;
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case 's':
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sflag = optarg;
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break;
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case 't':
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tflag = 1;
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break;
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case 'u':
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uflag = 1;
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break;
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case 'V':
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if (sysctlbyname("net.fibs", &numfibs, &intsize, NULL, 0) == -1)
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errx(1, "Multiple FIBS not supported");
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rtableid = (unsigned int)strtonum(optarg, 0,
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numfibs - 1, &errstr);
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if (errstr)
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errx(1, "rtable %s: %s", errstr, optarg);
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break;
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case 'v':
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vflag = 1;
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break;
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case 'w':
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timeout = strtonum(optarg, 0, INT_MAX / 1000, &errstr);
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if (errstr)
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errx(1, "timeout %s: %s", errstr, optarg);
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timeout *= 1000;
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break;
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case 'x':
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xflag = 1;
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if ((proxy = strdup(optarg)) == NULL)
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err(1, NULL);
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break;
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case 'z':
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zflag = 1;
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break;
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case 'D':
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Dflag = 1;
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break;
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case 'I':
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Iflag = strtonum(optarg, 1, 65536 << 14, &errstr);
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if (errstr != NULL)
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errx(1, "TCP receive window %s: %s",
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errstr, optarg);
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break;
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case 'O':
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Oflag = strtonum(optarg, 1, 65536 << 14, &errstr);
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if (errstr != NULL) {
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if (strcmp(errstr, "invalid") != 0)
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errx(1, "TCP send window %s: %s",
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errstr, optarg);
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}
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break;
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case 'S':
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Sflag = 1;
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break;
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case 'T':
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errstr = NULL;
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errno = 0;
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if (map_tos(optarg, &Tflag))
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break;
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if (strlen(optarg) > 1 && optarg[0] == '0' &&
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optarg[1] == 'x')
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Tflag = (int)strtol(optarg, NULL, 16);
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else
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Tflag = (int)strtonum(optarg, 0, 255,
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&errstr);
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if (Tflag < 0 || Tflag > 255 || errstr || errno)
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errx(1, "illegal tos value %s", optarg);
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break;
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default:
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usage(1);
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}
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}
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argc -= optind;
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argv += optind;
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/* Cruft to make sure options are clean, and used properly. */
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if (argv[0] && !argv[1] && family == AF_UNIX) {
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host = argv[0];
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uport = NULL;
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} else if (argv[0] && !argv[1]) {
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if (!lflag)
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usage(1);
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uport = argv[0];
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host = NULL;
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} else if (argv[0] && argv[1]) {
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host = argv[0];
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uport = argv[1];
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} else
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usage(1);
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if (lflag && sflag)
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errx(1, "cannot use -s and -l");
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if (lflag && pflag)
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errx(1, "cannot use -p and -l");
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if (lflag && zflag)
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errx(1, "cannot use -z and -l");
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if (!lflag && kflag)
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errx(1, "must use -l with -k");
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/* Get name of temporary socket for unix datagram client */
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if ((family == AF_UNIX) && uflag && !lflag) {
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if (sflag) {
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unix_dg_tmp_socket = sflag;
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} else {
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strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX",
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UNIX_DG_TMP_SOCKET_SIZE);
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if (mktemp(unix_dg_tmp_socket_buf) == NULL)
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err(1, "mktemp");
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unix_dg_tmp_socket = unix_dg_tmp_socket_buf;
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}
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}
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/* Initialize addrinfo structure. */
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if (family != AF_UNIX) {
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memset(&hints, 0, sizeof(struct addrinfo));
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hints.ai_family = family;
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hints.ai_socktype = uflag ? SOCK_DGRAM : SOCK_STREAM;
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hints.ai_protocol = uflag ? IPPROTO_UDP : IPPROTO_TCP;
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if (nflag)
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hints.ai_flags |= AI_NUMERICHOST;
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}
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if (xflag) {
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if (uflag)
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errx(1, "no proxy support for UDP mode");
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if (lflag)
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errx(1, "no proxy support for listen");
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if (family == AF_UNIX)
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errx(1, "no proxy support for unix sockets");
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/* XXX IPv6 transport to proxy would probably work */
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if (family == AF_INET6)
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errx(1, "no proxy support for IPv6");
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if (sflag)
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errx(1, "no proxy support for local source address");
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proxyhost = strsep(&proxy, ":");
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proxyport = proxy;
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memset(&proxyhints, 0, sizeof(struct addrinfo));
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proxyhints.ai_family = family;
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proxyhints.ai_socktype = SOCK_STREAM;
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proxyhints.ai_protocol = IPPROTO_TCP;
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if (nflag)
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proxyhints.ai_flags |= AI_NUMERICHOST;
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}
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if (lflag) {
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int connfd;
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ret = 0;
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if (family == AF_UNIX) {
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if (uflag)
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s = unix_bind(host);
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else
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s = unix_listen(host);
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}
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/* Allow only one connection at a time, but stay alive. */
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for (;;) {
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if (family != AF_UNIX)
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s = local_listen(host, uport, hints);
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if (s < 0)
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err(1, NULL);
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/*
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* For UDP, we will use recvfrom() initially
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* to wait for a caller, then use the regular
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* functions to talk to the caller.
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*/
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if (uflag) {
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int rv, plen;
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char buf[16384];
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struct sockaddr_storage z;
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len = sizeof(z);
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plen = jflag ? 16384 : 2048;
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rv = recvfrom(s, buf, plen, MSG_PEEK,
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(struct sockaddr *)&z, &len);
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if (rv < 0)
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err(1, "recvfrom");
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rv = connect(s, (struct sockaddr *)&z, len);
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if (rv < 0)
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err(1, "connect");
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readwrite(s);
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} else {
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len = sizeof(cliaddr);
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connfd = accept(s, (struct sockaddr *)&cliaddr,
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&len);
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readwrite(connfd);
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close(connfd);
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}
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if (family != AF_UNIX)
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close(s);
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else if (uflag) {
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if (connect(s, NULL, 0) < 0)
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err(1, "connect");
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}
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if (!kflag)
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break;
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}
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} else if (family == AF_UNIX) {
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ret = 0;
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if ((s = unix_connect(host)) > 0 && !zflag) {
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readwrite(s);
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close(s);
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} else
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ret = 1;
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if (uflag)
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unlink(unix_dg_tmp_socket);
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exit(ret);
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} else {
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int i = 0;
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/* Construct the portlist[] array. */
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build_ports(uport);
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/* Cycle through portlist, connecting to each port. */
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for (i = 0; portlist[i] != NULL; i++) {
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if (s)
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close(s);
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if (xflag)
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s = socks_connect(host, portlist[i], hints,
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proxyhost, proxyport, proxyhints, socksv,
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Pflag);
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else
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s = remote_connect(host, portlist[i], hints);
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if (s < 0)
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continue;
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ret = 0;
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if (vflag || zflag) {
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/* For UDP, make sure we are connected. */
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if (uflag) {
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if (udptest(s) == -1) {
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ret = 1;
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continue;
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}
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}
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/* Don't look up port if -n. */
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if (nflag)
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sv = NULL;
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else {
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sv = getservbyport(
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ntohs(atoi(portlist[i])),
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uflag ? "udp" : "tcp");
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}
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fprintf(stderr,
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"Connection to %s %s port [%s/%s] "
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"succeeded!\n", host, portlist[i],
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uflag ? "udp" : "tcp",
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sv ? sv->s_name : "*");
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}
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if (!zflag)
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readwrite(s);
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}
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}
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if (s)
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close(s);
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exit(ret);
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}
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/*
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* unix_bind()
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* Returns a unix socket bound to the given path
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*/
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int
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unix_bind(char *path)
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{
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struct sockaddr_un sun;
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int s;
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|
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/* Create unix domain socket. */
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if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM,
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0)) < 0)
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return (-1);
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memset(&sun, 0, sizeof(struct sockaddr_un));
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sun.sun_family = AF_UNIX;
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if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
|
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sizeof(sun.sun_path)) {
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close(s);
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errno = ENAMETOOLONG;
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return (-1);
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}
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|
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if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
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close(s);
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return (-1);
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}
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return (s);
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}
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|
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/*
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* 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;
|
|
#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) {
|
|
if (setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid,
|
|
sizeof(rtableid)) == -1)
|
|
err(1, "setsockopt(.., SO_SETFIB, %u, ..)",
|
|
rtableid);
|
|
}
|
|
|
|
/* 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)
|
|
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;
|
|
|
|
if (rtableid) {
|
|
ret = setsockopt(s, SOL_SOCKET, SO_SETFIB, &rtableid,
|
|
sizeof(rtableid));
|
|
if (ret == -1)
|
|
err(1, "setsockopt(.., SO_SETFIB, %u, ..)",
|
|
rtableid);
|
|
}
|
|
|
|
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");
|
|
}
|
|
|
|
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 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 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);
|
|
}
|
|
#ifdef SO_JUMBO
|
|
if (jflag) {
|
|
if (setsockopt(s, SOL_SOCKET, SO_JUMBO,
|
|
&x, sizeof(x)) == -1)
|
|
err(1, NULL);
|
|
}
|
|
#endif
|
|
if (Tflag != -1) {
|
|
if (setsockopt(s, IPPROTO_IP, IP_TOS,
|
|
&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
|
|
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-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--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 [-46DdEhklnrStUuvz] [-e policy] [-I length] [-i interval] [-O length]\n"
|
|
#else
|
|
"usage: nc [-46DdhklnrStUuvz] [-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);
|
|
}
|