/* myping.c
*
* Copyright (c) 2000 Sean Walton and Macmillan Publishers. Use may be in
* whole or in part in accordance to the General Public License (GPL).
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*****************************************************************************/
/*** myping.c ***/
/*** ***/
/*** Use the ICMP protocol to request "echo" from destination. ***/
/*****************************************************************************/
#include <fcntl.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/ip_icmp.h>
#define PACKETSIZE 64
struct packet
{
struct icmphdr hdr;
char msg[PACKETSIZE-sizeof(struct icmphdr)];
};
int pid=-1;
struct protoent *proto=NULL;
/*--------------------------------------------------------------------*/
/*--- checksum - standard 1s complement checksum ---*/
/*--------------------------------------------------------------------*/
unsigned short checksum(void *b, int len)
{ unsigned short *buf = b;
unsigned int sum=0;
unsigned short result;
for ( sum = 0; len > 1; len -= 2 )
sum += *buf++;
if ( len == 1 )
sum += *(unsigned char*)buf;
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
result = ~sum;
return result;
}
/*--------------------------------------------------------------------*/
/*--- display - present echo info ---*/
/*--------------------------------------------------------------------*/
void display(void *buf, int bytes)
{ int i;
struct iphdr *ip = buf;
struct icmphdr *icmp = buf+ip->ihl*4;
printf("----------------\n");
for ( i = 0; i < bytes; i++ )
{
if ( !(i & 15) ) printf("\n%04X: ", i);
printf("%04X ", ((unsigned char*)buf)[i]);
}
printf("\n");
printf("IPv%d: hdr-size=%d pkt-size=%d protocol=%d TTL=%d src=%s ",
ip->version, ip->ihl*4, ntohs(ip->tot_len), ip->protocol,
ip->ttl, inet_ntoa(ip->saddr));
printf("dst=%s\n", inet_ntoa(ip->daddr));
if ( icmp->un.echo.id == pid )
{
printf("ICMP: type[%d/%d] checksum[%d] id[%d] seq[%d]\n",
icmp->type, icmp->code, ntohs(icmp->checksum),
icmp->un.echo.id, icmp->un.echo.sequence);
}
}
/*--------------------------------------------------------------------*/
/*--- listener - separate process to listen for and collect messages--*/
/*--------------------------------------------------------------------*/
void listener(void)
{ int sd;
struct sockaddr_in addr;
unsigned char buf[1024];
sd = socket(PF_INET, SOCK_RAW, proto->p_proto);
if ( sd < 0 )
{
perror("socket");
exit(0);
}
for (;;)
{ int bytes, len=sizeof(addr);
bzero(buf, sizeof(buf));
bytes = recvfrom(sd, buf, sizeof(buf), 0, (struct sockaddr*)&addr, &len);
if ( bytes > 0 )
display(buf, bytes);
else
perror("recvfrom");
}
exit(0);
}
/*--------------------------------------------------------------------*/
/*--- ping - Create message and send it. ---*/
/*--------------------------------------------------------------------*/
void ping(struct sockaddr_in *addr)
{ const int val=255;
int i, sd, cnt=1;
struct packet pckt;
struct sockaddr_in r_addr;
sd = socket(PF_INET, SOCK_RAW, proto->p_proto);
if ( sd < 0 )
{
perror("socket");
return;
}
if ( setsockopt(sd, SOL_IP, IP_TTL, &val, sizeof(val)) != 0)
perror("Set TTL option");
if ( fcntl(sd, F_SETFL, O_NONBLOCK) != 0 )
perror("Request nonblocking I/O");
for (;;)
{ int len=sizeof(r_addr);
printf("Msg #%d\n", cnt);
if ( recvfrom(sd, &pckt, sizeof(pckt), 0, (struct sockaddr*)&r_addr, &len) > 0 )
printf("***Got message!***\n");
bzero(&pckt, sizeof(pckt));
pckt.hdr.type = ICMP_ECHO;
pckt.hdr.un.echo.id = pid;
for ( i = 0; i < sizeof(pckt.msg)-1; i++ )
pckt.msg[i] = i+'0';
pckt.msg[i] = 0;
pckt.hdr.un.echo.sequence = cnt++;
pckt.hdr.checksum = checksum(&pckt, sizeof(pckt));
if ( sendto(sd, &pckt, sizeof(pckt), 0, (struct sockaddr*)addr, sizeof(*addr)) <= 0 )
perror("sendto");
sleep(1);
}
}
/*--------------------------------------------------------------------*/
/*--- main - look up host and start ping processes. ---*/
/*--------------------------------------------------------------------*/
int main(int count, char *strings[])
{ struct hostent *hname;
struct sockaddr_in addr;
if ( count != 2 )
{
printf("usage: %s <addr>\n", strings[0]);
exit(0);
}
if ( count > 1 )
{
pid = getpid();
proto = getprotobyname("ICMP");
hname = gethostbyname(strings[1]);
bzero(&addr, sizeof(addr));
addr.sin_family = hname->h_addrtype;
addr.sin_port = 0;
addr.sin_addr.s_addr = *(long*)hname->h_addr;
if ( fork() == 0 )
listener();
else
ping(&addr);
wait(0);
}
else
printf("usage: myping <hostname>\n");
return 0;
}
