/*****************************************************************************
*
* $Id$
* Purpose ...............: mbtask - ping functions
*
*****************************************************************************
* Copyright (C) 1997-2002
*
* Michiel Broek FIDO: 2:280/2802
* Beekmansbos 10
* 1971 BV IJmuiden
* the Netherlands
*
* This file is part of MBSE BBS.
*
* This BBS is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* MBSE BBS is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with MBSE BBS; see the file COPYING. If not, write to the Free
* Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*****************************************************************************/
#include "../config.h"
#include "libs.h"
#include "../lib/structs.h"
#include "taskstat.h"
#include "taskutil.h"
#include "ping.h"
/*
* Global variables
*/
extern struct taskrec TCFG; /* Task config record */
int ping_isocket; /* Ping socket */
int icmp_errs = 0; /* ICMP error counter */
extern int internet; /* Internet is down */
extern int rescan; /* Master rescan flag */
int pingstate = P_BOOT; /* Ping state */
struct in_addr paddr; /* Current ping address */
/*
* Internal prototypes
*/
static int icmp4_errcmp(char *, int, struct in_addr *, char *, int, int);
unsigned short get_rand16(void);
int ping_send(struct in_addr);
int ping_receive(struct in_addr);
/*
* different names, same thing... be careful, as these are macros...
*/
#if defined(__FreeBSD__) || defined(__NetBSD__)
# define icmphdr icmp
# define iphdr ip
# define ip_saddr ip_src.s_addr
# define ip_daddr ip_dst.s_addr
#else
# define ip_saddr saddr
# define ip_daddr daddr
# define ip_hl ihl
# define ip_p protocol
#endif
#ifdef __linux__
# define icmp_type type
# define icmp_code code
# define icmp_cksum checksum
# ifdef icmp_id
# undef icmp_id
# endif
# define icmp_id un.echo.id
# ifdef icmp_seq
# undef icmp_seq
# endif
# define icmp_seq un.echo.sequence
#endif
#if defined(__FreeBSD__) || defined(__NetBSD__)
# define ICMP_DEST_UNREACH ICMP_UNREACH
# define ICMP_TIME_EXCEEDED ICMP_TIMXCEED
#endif
#define ICMP_BASEHDR_LEN 8
#define ICMP4_ECHO_LEN ICMP_BASEHDR_LEN
// short p_sequence = 0;
short p_sequence = 10;
unsigned short id;
struct icmphdr icmpd;
struct sockaddr_in to;
/*
* Takes a packet as send out and a recieved ICMP packet and looks whether the ICMP packet is
* an error reply on the sent-out one. packet is only the packet (without IP header).
* errmsg includes an IP header.
* to is the destination address of the original packet (the only thing that is actually
* compared of the IP header). The RFC sais that we get at least 8 bytes of the offending packet.
* We do not compare more, as this is all we need.
*/
static int icmp4_errcmp(char *packet, int plen, struct in_addr *too, char *errmsg, int elen, int errtype)
{
struct iphdr iph;
struct icmphdr icmph;
struct iphdr eiph;
char *data;
/*
* lots of memcpy to avoid unaligned accesses on alpha
*/
if (elen < sizeof(struct iphdr))
return 0;
memcpy(&iph, errmsg, sizeof(iph));
if (iph.ip_p != IPPROTO_ICMP || elen < iph.ip_hl * 4 + ICMP_BASEHDR_LEN + sizeof(eiph))
return 0;
memcpy(&icmph, errmsg + iph.ip_hl * 4, ICMP_BASEHDR_LEN);
memcpy(&eiph, errmsg + iph.ip_hl * 4 + ICMP_BASEHDR_LEN, sizeof(eiph));
if (elen < iph.ip_hl * 4 + ICMP_BASEHDR_LEN + eiph.ip_hl * 4 + 8)
return 0;
data = errmsg + iph.ip_hl * 4 + ICMP_BASEHDR_LEN + eiph.ip_hl * 4;
return icmph.icmp_type == errtype && memcmp(&too->s_addr, &eiph.ip_daddr, sizeof(too->s_addr)) == 0 &&
memcmp(data, packet, plen < 8 ?plen:8) == 0;
}
unsigned short get_rand16(void)
{
return random()&0xffff;
}
/*
* IPv4/ICMPv4 ping. Called from ping (see below)
*/
int ping_send(struct in_addr addr)
{
int len, sentlen;
#ifdef __linux__
struct icmp_filter f;
#else
struct protoent *pe;
int SOL_IP;
#endif
unsigned long sum;
unsigned short *ptr;
#ifndef __linux__
if (!(pe = getprotobyname("ip"))) {
tasklog('?', "icmp ping: getprotobyname() failed: %s", strerror(errno));
return -1;
}
SOL_IP = pe->p_proto;
#endif
// p_sequence++;
id = (unsigned short)get_rand16(); /* randomize a ping id */
#ifdef __linux__
/*
* Fancy ICMP filering -- only on Linux (as far is I know)
*
* In fact, there should be macros for treating icmp_filter, but I haven't found them in Linux 2.2.15.
* So, set it manually and unportable ;-)
* This filter lets ECHO_REPLY (0), DEST_UNREACH(3) and TIME_EXCEEDED(11) pass.
* !(0000 1000 0000 1001) = 0xff ff f7 f6
*/
f.data=0xfffff7f6;
if (setsockopt(ping_isocket, SOL_RAW, ICMP_FILTER, &f, sizeof(f)) == -1) {
if (icmp_errs < ICMP_MAX_ERRS)
tasklog('?', "$icmp ping: setsockopt() failed %d", ping_isocket);
return -1;
}
#endif
icmpd.icmp_type = ICMP_ECHO;
icmpd.icmp_code = 0;
icmpd.icmp_cksum = 0;
icmpd.icmp_id = htons((short)id);
icmpd.icmp_seq = htons(p_sequence);
/* Checksumming - Algorithm taken from nmap. Thanks... */
ptr = (unsigned short *)&icmpd;
sum = 0;
for (len = 0; len < 4; len++) {
sum += *ptr++;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
icmpd.icmp_cksum = ~sum;
memset(&to, 0, sizeof(to));
to.sin_family = AF_INET;
to.sin_port = 0;
to.sin_addr = addr;
SET_SOCKA_LEN4(to);
sentlen = sendto(ping_isocket, &icmpd, ICMP4_ECHO_LEN, 0, (struct sockaddr *)&to, sizeof(to));
if (sentlen != ICMP4_ECHO_LEN) {
if (icmp_errs < ICMP_MAX_ERRS) {
if (sentlen == -1)
tasklog('+', "ping: sent error: %s", strerror(errno));
else
tasklog('+', "ping: sent %d octets, ret %d", ICMP4_ECHO_LEN, sentlen);
}
return -2;
}
return 0;
}
/*
* 0 = reply received Ok.
* -1 = reply packet not for us, this is Ok.
* -2 = destination unreachable.
* -3 = poll/select error.
* -4 = time exceeded.
* -5 = wrong packetlen received.
* -6 = no data received, this is Ok.
* -7 = icmp parameter problem.
*/
int ping_receive(struct in_addr addr)
{
char buf[1024];
int len;
struct sockaddr_in ffrom;
struct icmphdr icmpp;
struct iphdr iph;
socklen_t sl;
struct pollfd pfd;
pfd.fd = ping_isocket;
pfd.events = POLLIN;
/*
* 10 mSec is enough, this function is called at regular intervals.
*/
if (poll(&pfd, 1, 10) < 0) {
if (icmp_errs < ICMP_MAX_ERRS)
tasklog('?', "$poll/select failed");
return -3;
}
if (pfd.revents & POLLIN || pfd.revents & POLLERR || pfd.revents & POLLHUP || pfd.revents & POLLNVAL) {
sl = sizeof(ffrom);
if ((len = recvfrom(ping_isocket, &buf, sizeof(buf)-1, 0,(struct sockaddr *)&ffrom, &sl)) != -1) {
if (len > sizeof(struct iphdr)) {
memcpy(&iph, buf, sizeof(iph));
if (len - iph.ip_hl * 4 >= ICMP_BASEHDR_LEN) {
memcpy(&icmpp, ((unsigned long int *)buf)+iph.ip_hl, sizeof(icmpp));
if (iph.ip_saddr == addr.s_addr && icmpp.icmp_type == ICMP_ECHOREPLY &&
ntohs(icmpp.icmp_id) == id && ntohs(icmpp.icmp_seq) == p_sequence) {
return 0;
} else {
/* No regular echo reply. Maybe an error? */
if (icmp4_errcmp((char *)&icmpd, ICMP4_ECHO_LEN, &to.sin_addr, buf, len, ICMP_DEST_UNREACH))
return -2;
if (icmp4_errcmp((char *)&icmpd, ICMP4_ECHO_LEN, &to.sin_addr, buf, len, ICMP_TIME_EXCEEDED))
return -4;
#ifdef __linux__
if (icmp4_errcmp((char *)&icmpd, ICMP4_ECHO_LEN, &to.sin_addr, buf, len, ICMP_PARAMETERPROB))
return -7;
#endif
/*
* No fatal problem, the return code will be -1 caused by other
* icmp trafic on the network (packets not for us).
*/
return -1;
}
}
}
} else {
return -5; /* error */
}
}
return -6; /* no answer */
}
void check_ping(void)
{
int rc = 0;
static int pingnr, pingresult[2];
static char pingaddress[41];
static time_t pingtime;
switch (pingstate) {
case P_BOOT: pingnr = 2;
pingstate = P_SENT;
pingresult[1] = pingresult[2] = internet = FALSE;
break;
case P_PAUSE: // tasklog('p', "PAUSE:");
if (time(NULL) >= pingtime)
pingstate = P_SENT;
break;
case P_WAIT: // tasklog('p', "WAIT:");
if (time(NULL) >= pingtime) {
pingstate = P_ERROR;
if (icmp_errs < ICMP_MAX_ERRS)
tasklog('?', "ping: to %s timeout", pingaddress);
} else {
/*
* Quickly eat all packets not for us, we only want our
* packets and empty results (packet still underway).
*/
while ((rc = ping_receive(paddr)) == -1);
if (!rc) {
/*
* Reply received.
*/
rc = time(NULL) - (pingtime - 20);
if (rc > 2)
tasklog('p', "ping: reply after %d seconds", rc);
pingresult[pingnr] = TRUE;
if (pingresult[1] || pingresult[2]) {
if (!internet) {
tasklog('!', "Internet connection is up");
internet = TRUE;
sem_set((char *)"scanout", TRUE);
CreateSema((char *)"is_inet");
rescan = TRUE;
}
icmp_errs = 0;
}
pingtime = time(NULL) + 5; // 5 secs pause until next ping
pingstate = P_PAUSE;
} else {
if (rc != -6) {
tasklog('p', "ping: recv %s id=%d rc=%d", pingaddress, id, rc);
pingstate = P_ERROR;
}
}
}
break;
case P_SENT: // tasklog('p', "SENT:");
pingtime = time(NULL) + 10; // 10 secs timeout for pause.
if (pingnr == 1) {
pingnr = 2;
if (strlen(TCFG.isp_ping2)) {
sprintf(pingaddress, "%s", TCFG.isp_ping2);
} else {
pingresult[2] = FALSE;
pingstate = P_PAUSE;
break;
}
} else {
pingnr = 1;
if (strlen(TCFG.isp_ping1)) {
sprintf(pingaddress, "%s", TCFG.isp_ping1);
} else {
pingresult[1] = FALSE;
pingstate = P_PAUSE;
break;
}
}
pingtime = time(NULL) + 20; // 20 secs timeout for a real ping
// tasklog('p', "nr %d address %s", pingnr, pingaddress);
if (inet_aton(pingaddress, &paddr)) {
rc = ping_send(paddr);
if (rc) {
if (icmp_errs++ < ICMP_MAX_ERRS)
tasklog('?', "ping: to %s rc=%d", pingaddress, rc);
pingstate = P_ERROR;
pingresult[pingnr] = FALSE;
} else {
pingstate = P_WAIT;
}
} else {
if (icmp_errs++ < ICMP_MAX_ERRS)
tasklog('?', "Ping address %d is invalid \"%s\"", pingnr, pingaddress);
pingstate = P_PAUSE;
}
break;
case P_ERROR: // tasklog('p', "ERROR:");
pingresult[pingnr] = FALSE;
if (pingresult[1] == FALSE && pingresult[2] == FALSE) {
icmp_errs++;
if (internet) {
tasklog('!', "Internet connection is down");
internet = FALSE;
sem_set((char *)"scanout", TRUE);
RemoveSema((char *)"is_inet");
rescan = TRUE;
}
}
pingtime = time(NULL) + 5; // 5 secs pause until next ping
pingstate = P_PAUSE;
break;
}
}
/*
* Create the ping socket, called from main() during init as root.
*/
void init_pingsocket(void)
{
if ((ping_isocket = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) == -1) {
if (errno == EPERM) {
fprintf(stderr, "socket init failed, mbtask not installed setuid root\n");
} else {
fprintf(stderr, "socket init failed\n");
}
exit(1);
}
/*
* If someone's messing with us, bail.
* It would be nice to issue an error message, but to where?
*/
if (ping_isocket == STDIN_FILENO || ping_isocket == STDOUT_FILENO || ping_isocket == STDERR_FILENO) {
exit(255);
}
}