/*
 * $Id: pinger.c,v 1.45.2.1 2001/01/12 00:51:51 wessels Exp $
 *
 * DEBUG: section 42    ICMP Pinger program
 * AUTHOR: Duane Wessels
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  This program 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 of the License, or
 *  (at your option) any later version.
 *  
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "squid.h"

#if USE_ICMP

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>

#ifndef _SQUID_LINUX_
#ifndef _SQUID_CYGWIN_
#define icmphdr icmp
#define iphdr ip
#endif
#endif

#if defined (_SQUID_LINUX_) || defined (_SQUID_CYGWIN_)
#ifdef icmp_id
#undef icmp_id
#endif
#ifdef icmp_seq
#undef icmp_seq
#endif
#define icmp_type type
#define icmp_code code
#define icmp_cksum checksum
#define icmp_id un.echo.id
#define icmp_seq un.echo.sequence
#define ip_hl ihl
#define ip_v version
#define ip_tos tos
#define ip_len tot_len
#define ip_id id
#define ip_off frag_off
#define ip_ttl ttl
#define ip_p protocol
#define ip_sum check
#define ip_src saddr
#define ip_dst daddr
#endif

#if ALLOW_SOURCE_PING
#define MAX_PKT_SZ 8192
#define MAX_PAYLOAD (MAX_PKT_SZ - sizeof(struct icmphdr) - sizeof (char) - sizeof(struct timeval) - 1)
#else
#define MAX_PAYLOAD SQUIDHOSTNAMELEN
#define MAX_PKT_SZ (MAX_PAYLOAD + sizeof(struct timeval) + sizeof (char) + sizeof(struct icmphdr) + 1)
#endif

typedef struct {
    struct timeval tv;
    unsigned char opcode;
    char payload[MAX_PAYLOAD];
} icmpEchoData;

int icmp_ident = -1;
int icmp_pkts_sent = 0;

static const char *icmpPktStr[] =
{
    "Echo Reply",
    "ICMP 1",
    "ICMP 2",
    "Destination Unreachable",
    "Source Quench",
    "Redirect",
    "ICMP 6",
    "ICMP 7",
    "Echo",
    "ICMP 9",
    "ICMP 10",
    "Time Exceeded",
    "Parameter Problem",
    "Timestamp",
    "Timestamp Reply",
    "Info Request",
    "Info Reply",
    "Out of Range Type"
};

static int in_cksum(unsigned short *ptr, int size);
static void pingerRecv(void);
static void pingerLog(struct icmphdr *, struct in_addr, int, int);
static int ipHops(int ttl);
static void pingerSendtoSquid(pingerReplyData * preply);

void
pingerOpen(void)
{
    struct protoent *proto = NULL;
    if ((proto = getprotobyname("icmp")) == 0) {
	debug(42, 0) ("pingerOpen: unknown protocol: icmp\n");
	exit(1);
    }
    icmp_sock = socket(PF_INET, SOCK_RAW, proto->p_proto);
    if (icmp_sock < 0) {
	debug(50, 0) ("pingerOpen: icmp_sock: %s\n", xstrerror());
	exit(1);
    }
    icmp_ident = getpid() & 0xffff;
    debug(42, 0) ("pinger: ICMP socket opened\n");
}

void
pingerClose(void)
{
    close(icmp_sock);
    icmp_sock = -1;
    icmp_ident = 0;
}

static void
pingerSendEcho(struct in_addr to, int opcode, char *payload, int len)
{
    LOCAL_ARRAY(char, pkt, MAX_PKT_SZ);
    struct icmphdr *icmp = NULL;
    icmpEchoData *echo;
    int icmp_pktsize = sizeof(struct icmphdr);
    struct sockaddr_in S;
    memset(pkt, '\0', MAX_PKT_SZ);
    icmp = (struct icmphdr *) (void *) pkt;

    /*
     * cevans - beware signed/unsigned issues in untrusted data from
     * the network!!
     */
    if (len < 0) {
	len = 0;
    }
    icmp->icmp_type = ICMP_ECHO;
    icmp->icmp_code = 0;
    icmp->icmp_cksum = 0;
    icmp->icmp_id = icmp_ident;
    icmp->icmp_seq = (u_short) icmp_pkts_sent++;
    echo = (icmpEchoData *) (icmp + 1);
    echo->opcode = (unsigned char) opcode;
    echo->tv = current_time;
    icmp_pktsize += sizeof(icmpEchoData) - MAX_PAYLOAD;
    if (payload) {
	if (len > MAX_PAYLOAD)
	    len = MAX_PAYLOAD;
	xmemcpy(echo->payload, payload, len);
	icmp_pktsize += len;
    }
    icmp->icmp_cksum = in_cksum((u_short *) icmp, icmp_pktsize);
    S.sin_family = AF_INET;
    /*
     * cevans: alert: trusting to-host, was supplied in network packet
     */
    S.sin_addr = to;
    S.sin_port = 0;
    assert(icmp_pktsize <= MAX_PKT_SZ);
    sendto(icmp_sock,
	pkt,
	icmp_pktsize,
	0,
	(struct sockaddr *) &S,
	sizeof(struct sockaddr_in));
    pingerLog(icmp, to, 0, 0);
}

static void
pingerRecv(void)
{
    int n;
    socklen_t fromlen;
    struct sockaddr_in from;
    int iphdrlen = 20;
    struct iphdr *ip = NULL;
    struct icmphdr *icmp = NULL;
    static char *pkt = NULL;
    struct timeval now;
    icmpEchoData *echo;
    static pingerReplyData preply;

    if (pkt == NULL)
	pkt = xmalloc(MAX_PKT_SZ);
    fromlen = sizeof(from);
    n = recvfrom(icmp_sock,
	pkt,
	MAX_PKT_SZ,
	0,
	(struct sockaddr *) &from,
	&fromlen);
#if GETTIMEOFDAY_NO_TZP
    gettimeofday(&now);
#else
    gettimeofday(&now, NULL);
#endif
    debug(42, 9) ("pingerRecv: %d bytes from %s\n", n, inet_ntoa(from.sin_addr));
    ip = (struct iphdr *) (void *) pkt;
#if HAVE_IP_HL
    iphdrlen = ip->ip_hl << 2;
#else /* HAVE_IP_HL */
#if WORDS_BIGENDIAN
    iphdrlen = (ip->ip_vhl >> 4) << 2;
#else
    iphdrlen = (ip->ip_vhl & 0xF) << 2;
#endif
#endif /* HAVE_IP_HL */
    icmp = (struct icmphdr *) (void *) (pkt + iphdrlen);
    if (icmp->icmp_type != ICMP_ECHOREPLY)
	return;
    if (icmp->icmp_id != icmp_ident)
	return;
    echo = (icmpEchoData *) (void *) (icmp + 1);
    preply.from = from.sin_addr;
    preply.opcode = echo->opcode;
    preply.hops = ipHops(ip->ip_ttl);
    preply.rtt = tvSubMsec(echo->tv, now);
    preply.psize = n - iphdrlen - (sizeof(icmpEchoData) - MAX_PKT_SZ);
    pingerSendtoSquid(&preply);
    pingerLog(icmp, from.sin_addr, preply.rtt, preply.hops);
}


static int
in_cksum(unsigned short *ptr, int size)
{
    long sum;
    unsigned short oddbyte;
    unsigned short answer;
    sum = 0;
    while (size > 1) {
	sum += *ptr++;
	size -= 2;
    }
    if (size == 1) {
	oddbyte = 0;
	*((unsigned char *) &oddbyte) = *(unsigned char *) ptr;
	sum += oddbyte;
    }
    sum = (sum >> 16) + (sum & 0xffff);
    sum += (sum >> 16);
    answer = ~sum;
    return (answer);
}

static void
pingerLog(struct icmphdr *icmp, struct in_addr addr, int rtt, int hops)
{
    debug(42, 2) ("pingerLog: %9d.%06d %-16s %d %-15.15s %dms %d hops\n",
	(int) current_time.tv_sec,
	(int) current_time.tv_usec,
	inet_ntoa(addr),
	(int) icmp->icmp_type,
	icmpPktStr[icmp->icmp_type],
	rtt,
	hops);
}

static int
ipHops(int ttl)
{
    if (ttl < 33)
	return 33 - ttl;
    if (ttl < 63)
	return 63 - ttl;	/* 62 = (64+60)/2 */
    if (ttl < 65)
	return 65 - ttl;	/* 62 = (64+60)/2 */
    if (ttl < 129)
	return 129 - ttl;
    if (ttl < 193)
	return 193 - ttl;
    return 256 - ttl;
}

static int
pingerReadRequest(void)
{
    static pingerEchoData pecho;
    int n;
    int guess_size;
    memset(&pecho, '\0', sizeof(pecho));
    n = recv(0, (char *) &pecho, sizeof(pecho), 0);
    if (n < 0)
	return n;
    if (0 == n) {
	/* EOF indicator */
	fprintf(stderr, "EOF encountered\n");
	errno = 0;
	return -1;
    }
    guess_size = n - (sizeof(pingerEchoData) - PINGER_PAYLOAD_SZ);
    if (guess_size != pecho.psize) {
	fprintf(stderr, "size mismatch, guess=%d psize=%d\n",
	    guess_size, pecho.psize);
	/* don't process this message, but keep running */
	return 0;
    }
    pingerSendEcho(pecho.to,
	pecho.opcode,
	pecho.payload,
	pecho.psize);
    return n;
}

static void
pingerSendtoSquid(pingerReplyData * preply)
{
    int len = sizeof(pingerReplyData) - MAX_PKT_SZ + preply->psize;
    if (send(1, (char *) preply, len, 0) < 0) {
	debug(50, 0) ("pinger: send: %s\n", xstrerror());
	exit(1);
    }
}

time_t
getCurrentTime(void)
{
#if GETTIMEOFDAY_NO_TZP
    gettimeofday(&current_time);
#else
    gettimeofday(&current_time, NULL);
#endif
    return squid_curtime = current_time.tv_sec;
}


int
main(int argc, char *argv[])
{
    fd_set R;
    int x;
    struct timeval tv;
    const char *debug_args = "ALL,1";
    char *t;
    time_t last_check_time = 0;

/*
 * cevans - do this first. It grabs a raw socket. After this we can
 * drop privs
 */
    pingerOpen();
    setgid(getgid());
    setuid(getuid());

    if ((t = getenv("SQUID_DEBUG")))
	debug_args = xstrdup(t);
    getCurrentTime();
    _db_init(NULL, debug_args);

    for (;;) {
	tv.tv_sec = 10;
	tv.tv_usec = 0;
	FD_ZERO(&R);
	FD_SET(0, &R);
	FD_SET(icmp_sock, &R);
	x = select(icmp_sock + 1, &R, NULL, NULL, &tv);
	getCurrentTime();
	if (x < 0)
	    exit(1);
	if (FD_ISSET(0, &R))
	    if (pingerReadRequest() < 0) {
		debug(42, 0) ("Pinger exiting.\n");
		exit(1);
	    }
	if (FD_ISSET(icmp_sock, &R))
	    pingerRecv();
	if (10 + last_check_time < squid_curtime) {
	    if (send(1, (char *) &tv, 0, 0) < 0)
		exit(1);
	    last_check_time = squid_curtime;
	}
    }
    /* NOTREACHED */
}

#else
#include <stdio.h>
int
main(int argc, char *argv[])
{
    fprintf(stderr, "%s: ICMP support not compiled in.\n", argv[0]);
    return 1;
}
#endif /* USE_ICMP */