442 lines
12 KiB
C
442 lines
12 KiB
C
/*****************************************************************************
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*
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* $Id$
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* Purpose ...............: mbtask - ping functions
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*
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*****************************************************************************
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* Copyright (C) 1997-2003
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*
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* Michiel Broek FIDO: 2:280/2802
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* Beekmansbos 10
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* 1971 BV IJmuiden
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* the Netherlands
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*
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* This file is part of MBSE BBS.
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*
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* This BBS is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* MBSE BBS is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with MBSE BBS; see the file COPYING. If not, write to the Free
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* Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*****************************************************************************/
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#include "../config.h"
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#include "libs.h"
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#include "../lib/structs.h"
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#include "../lib/mberrors.h"
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#include "taskstat.h"
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#include "taskutil.h"
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#include "ping.h"
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/*
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* Global variables
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*/
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extern struct taskrec TCFG; /* Task config record */
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int ping_isocket; /* Ping socket */
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int icmp_errs = 0; /* ICMP error counter */
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extern int internet; /* Internet is down */
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extern int rescan; /* Master rescan flag */
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int pingstate = P_BOOT; /* Ping state */
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struct in_addr paddr; /* Current ping address */
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/*
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* Internal prototypes
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*/
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static int icmp4_errcmp(char *, int, struct in_addr *, char *, int, int);
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unsigned short get_rand16(void);
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int ping_send(struct in_addr);
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int ping_receive(struct in_addr);
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/*
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* different names, same thing... be careful, as these are macros...
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*/
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#if defined(__FreeBSD__) || defined(__NetBSD__)
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# define icmphdr icmp
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# define iphdr ip
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# define ip_saddr ip_src.s_addr
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# define ip_daddr ip_dst.s_addr
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#else
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# define ip_saddr saddr
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# define ip_daddr daddr
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# define ip_hl ihl
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# define ip_p protocol
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#endif
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#ifdef __linux__
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# define icmp_type type
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# define icmp_code code
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# define icmp_cksum checksum
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# ifdef icmp_id
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# undef icmp_id
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# endif
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# define icmp_id un.echo.id
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# ifdef icmp_seq
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# undef icmp_seq
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# endif
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# define icmp_seq un.echo.sequence
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#endif
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#if defined(__FreeBSD__) || defined(__NetBSD__)
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# define ICMP_DEST_UNREACH ICMP_UNREACH
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# define ICMP_TIME_EXCEEDED ICMP_TIMXCEED
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#endif
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#define ICMP_BASEHDR_LEN 8
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#define ICMP4_ECHO_LEN ICMP_BASEHDR_LEN
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short p_sequence = 10;
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unsigned short id;
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struct icmphdr icmpd;
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struct sockaddr_in to;
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/*
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* Takes a packet as send out and a recieved ICMP packet and looks whether the ICMP packet is
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* an error reply on the sent-out one. packet is only the packet (without IP header).
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* errmsg includes an IP header.
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* to is the destination address of the original packet (the only thing that is actually
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* compared of the IP header). The RFC sais that we get at least 8 bytes of the offending packet.
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* We do not compare more, as this is all we need.
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*/
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static int icmp4_errcmp(char *packet, int plen, struct in_addr *too, char *errmsg, int elen, int errtype)
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{
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struct iphdr iph;
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struct icmphdr icmph;
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struct iphdr eiph;
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char *data;
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/*
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* lots of memcpy to avoid unaligned accesses on alpha
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*/
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if (elen < sizeof(struct iphdr))
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return 0;
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memcpy(&iph, errmsg, sizeof(iph));
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if (iph.ip_p != IPPROTO_ICMP || elen < iph.ip_hl * 4 + ICMP_BASEHDR_LEN + sizeof(eiph))
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return 0;
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memcpy(&icmph, errmsg + iph.ip_hl * 4, ICMP_BASEHDR_LEN);
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memcpy(&eiph, errmsg + iph.ip_hl * 4 + ICMP_BASEHDR_LEN, sizeof(eiph));
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if (elen < iph.ip_hl * 4 + ICMP_BASEHDR_LEN + eiph.ip_hl * 4 + 8)
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return 0;
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data = errmsg + iph.ip_hl * 4 + ICMP_BASEHDR_LEN + eiph.ip_hl * 4;
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return icmph.icmp_type == errtype && memcmp(&too->s_addr, &eiph.ip_daddr, sizeof(too->s_addr)) == 0 &&
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memcmp(data, packet, plen < 8 ?plen:8) == 0;
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}
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unsigned short get_rand16(void)
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{
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return random()&0xffff;
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}
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/*
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* IPv4/ICMPv4 ping. Called from ping (see below)
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*/
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int ping_send(struct in_addr addr)
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{
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int len, sentlen;
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#ifdef __linux__
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struct icmp_filter f;
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#else
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struct protoent *pe;
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int SOL_IP;
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#endif
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unsigned long sum;
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unsigned short *ptr;
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#ifndef __linux__
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if (!(pe = getprotobyname("ip"))) {
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Syslog('?', "icmp ping: getprotobyname() failed: %s", strerror(errno));
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return -1;
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}
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SOL_IP = pe->p_proto;
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#endif
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id = (unsigned short)get_rand16(); /* randomize a ping id */
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#ifdef __linux__
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/*
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* Fancy ICMP filering -- only on Linux (as far is I know)
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*
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* In fact, there should be macros for treating icmp_filter, but I haven't found them in Linux 2.2.15.
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* So, set it manually and unportable ;-)
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* This filter lets ECHO_REPLY (0), DEST_UNREACH(3) and TIME_EXCEEDED(11) pass.
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* !(0000 1000 0000 1001) = 0xff ff f7 f6
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*/
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f.data=0xfffff7f6;
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if (setsockopt(ping_isocket, SOL_RAW, ICMP_FILTER, &f, sizeof(f)) == -1) {
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if (icmp_errs < ICMP_MAX_ERRS)
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Syslog('?', "$icmp ping: setsockopt() failed %d", ping_isocket);
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return -1;
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}
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#endif
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icmpd.icmp_type = ICMP_ECHO;
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icmpd.icmp_code = 0;
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icmpd.icmp_cksum = 0;
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icmpd.icmp_id = htons((short)id);
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icmpd.icmp_seq = htons(p_sequence);
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/* Checksumming - Algorithm taken from nmap. Thanks... */
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ptr = (unsigned short *)&icmpd;
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sum = 0;
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for (len = 0; len < 4; len++) {
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sum += *ptr++;
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}
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sum = (sum >> 16) + (sum & 0xffff);
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sum += (sum >> 16);
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icmpd.icmp_cksum = ~sum;
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memset(&to, 0, sizeof(to));
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to.sin_family = AF_INET;
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to.sin_port = 0;
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to.sin_addr = addr;
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SET_SOCKA_LEN4(to);
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sentlen = sendto(ping_isocket, &icmpd, ICMP4_ECHO_LEN, 0, (struct sockaddr *)&to, sizeof(to));
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if (sentlen != ICMP4_ECHO_LEN) {
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if (icmp_errs < ICMP_MAX_ERRS) {
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if (sentlen == -1)
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Syslog('+', "ping: sent error: %s", strerror(errno));
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else
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Syslog('+', "ping: sent %d octets, ret %d", ICMP4_ECHO_LEN, sentlen);
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}
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return -2;
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}
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return 0;
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}
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/*
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* 0 = reply received Ok.
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* -1 = reply packet not for us, this is Ok.
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* -2 = destination unreachable.
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* -3 = poll/select error.
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* -4 = time exceeded.
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* -5 = wrong packetlen received.
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* -6 = no data received, this is Ok.
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* -7 = icmp parameter problem.
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*/
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int ping_receive(struct in_addr addr)
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{
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char buf[1024];
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int len;
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struct sockaddr_in ffrom;
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struct icmphdr icmpp;
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struct iphdr iph;
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socklen_t sl;
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struct pollfd pfd;
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pfd.fd = ping_isocket;
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pfd.events = POLLIN;
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/*
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* 10 mSec is enough, this function is called at regular intervals.
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*/
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if (poll(&pfd, 1, 10) < 0) {
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if (icmp_errs < ICMP_MAX_ERRS)
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Syslog('?', "$poll/select failed");
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return -3;
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}
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if (pfd.revents & POLLIN || pfd.revents & POLLERR || pfd.revents & POLLHUP || pfd.revents & POLLNVAL) {
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sl = sizeof(ffrom);
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if ((len = recvfrom(ping_isocket, &buf, sizeof(buf)-1, 0,(struct sockaddr *)&ffrom, &sl)) != -1) {
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if (len > sizeof(struct iphdr)) {
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memcpy(&iph, buf, sizeof(iph));
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if (len - iph.ip_hl * 4 >= ICMP_BASEHDR_LEN) {
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memcpy(&icmpp, ((unsigned long int *)buf)+iph.ip_hl, sizeof(icmpp));
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if (iph.ip_saddr == addr.s_addr && icmpp.icmp_type == ICMP_ECHOREPLY &&
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ntohs(icmpp.icmp_id) == id && ntohs(icmpp.icmp_seq) == p_sequence) {
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return 0;
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} else {
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/* No regular echo reply. Maybe an error? */
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if (icmp4_errcmp((char *)&icmpd, ICMP4_ECHO_LEN, &to.sin_addr, buf, len, ICMP_DEST_UNREACH))
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return -2;
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if (icmp4_errcmp((char *)&icmpd, ICMP4_ECHO_LEN, &to.sin_addr, buf, len, ICMP_TIME_EXCEEDED))
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return -4;
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#ifdef __linux__
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if (icmp4_errcmp((char *)&icmpd, ICMP4_ECHO_LEN, &to.sin_addr, buf, len, ICMP_PARAMETERPROB))
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return -7;
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#endif
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/*
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* No fatal problem, the return code will be -1 caused by other
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* icmp trafic on the network (packets not for us).
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*/
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return -1;
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}
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}
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}
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} else {
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return -5; /* error */
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}
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}
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return -6; /* no answer */
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}
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void check_ping(void)
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{
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int rc = 0;
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static int pingnr, pingresult[2];
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static char pingaddress[41];
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static time_t pingtime;
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switch (pingstate) {
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case P_BOOT: pingnr = 2;
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pingstate = P_SENT;
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pingresult[1] = pingresult[2] = internet = FALSE;
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break;
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case P_PAUSE: if (time(NULL) >= pingtime)
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pingstate = P_SENT;
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break;
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case P_WAIT: if (time(NULL) >= pingtime) {
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pingstate = P_ERROR;
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if (icmp_errs < ICMP_MAX_ERRS)
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Syslog('?', "ping: to %s timeout", pingaddress);
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} else {
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/*
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* Quickly eat all packets not for us, we only want our
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* packets and empty results (packet still underway).
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*/
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while ((rc = ping_receive(paddr)) == -1);
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if (!rc) {
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/*
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* Reply received.
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*/
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rc = time(NULL) - (pingtime - 20);
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if (rc > 10)
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Syslog('+', "Ping: slow reply after %d seconds", rc);
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pingresult[pingnr] = TRUE;
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if (pingresult[1] || pingresult[2]) {
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if (!internet) {
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Syslog('!', "Internet connection is up");
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internet = TRUE;
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sem_set((char *)"scanout", TRUE);
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CreateSema((char *)"is_inet");
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rescan = TRUE;
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}
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icmp_errs = 0;
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}
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pingtime = time(NULL) + 5; // 5 secs pause until next ping
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pingstate = P_PAUSE;
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} else {
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if (rc != -6) {
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Syslog('p', "ping: recv %s id=%d rc=%d", pingaddress, id, rc);
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pingstate = P_ERROR;
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}
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}
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}
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break;
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case P_SENT: pingtime = time(NULL) + 10; // 10 secs timeout for pause.
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if (pingnr == 1) {
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pingnr = 2;
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if (strlen(TCFG.isp_ping2)) {
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sprintf(pingaddress, "%s", TCFG.isp_ping2);
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} else {
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pingresult[2] = FALSE;
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pingstate = P_PAUSE;
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break;
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}
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} else {
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pingnr = 1;
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if (strlen(TCFG.isp_ping1)) {
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sprintf(pingaddress, "%s", TCFG.isp_ping1);
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} else {
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pingresult[1] = FALSE;
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pingstate = P_PAUSE;
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break;
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}
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}
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pingtime = time(NULL) + 20; // 20 secs timeout for a real ping
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if (inet_aton(pingaddress, &paddr)) {
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rc = ping_send(paddr);
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if (rc) {
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if (icmp_errs++ < ICMP_MAX_ERRS)
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Syslog('?', "ping: to %s rc=%d", pingaddress, rc);
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pingstate = P_ERROR;
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pingresult[pingnr] = FALSE;
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} else {
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pingstate = P_WAIT;
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}
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} else {
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if (icmp_errs++ < ICMP_MAX_ERRS)
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Syslog('?', "Ping address %d is invalid \"%s\"", pingnr, pingaddress);
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pingstate = P_PAUSE;
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}
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break;
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case P_ERROR: pingresult[pingnr] = FALSE;
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if (pingresult[1] == FALSE && pingresult[2] == FALSE) {
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icmp_errs++;
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if (internet) {
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Syslog('!', "Internet connection is down");
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internet = FALSE;
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sem_set((char *)"scanout", TRUE);
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RemoveSema((char *)"is_inet");
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rescan = TRUE;
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}
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}
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pingtime = time(NULL) + 5; // 5 secs pause until next ping
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pingstate = P_PAUSE;
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break;
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}
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}
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/*
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* Create the ping socket, called from main() during init as root.
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*/
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void init_pingsocket(void)
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{
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if ((ping_isocket = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) == -1) {
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if (errno == EPERM) {
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fprintf(stderr, "socket init failed, mbtask not installed setuid root\n");
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} else {
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fprintf(stderr, "socket init failed\n");
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}
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exit(MBERR_INIT_ERROR);
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}
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/*
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* If someone's messing with us, bail.
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* It would be nice to issue an error message, but to where?
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*/
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if (ping_isocket == STDIN_FILENO || ping_isocket == STDOUT_FILENO || ping_isocket == STDERR_FILENO) {
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exit(MBERR_GENERAL);
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}
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}
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