Guy Harris wrote:
> On Thu, Sep 12, 2002 at 01:25:44PM +0200, Ren Hoek wrote:
>
>>My problem is, that I cannot seem to use a select() on the pcap
>>filedescriptor (pcap_fileno()). It simply won't return.
>
>
> On what OS are you doing this?
>
I'm working on Linux.. I saw that I made a very bad mistake in my program.. I put
the timeout in front of my loop, instead of inside.. :(
I got it to work.. Here is an example of how it SHOULD be done :) You might want
to consider putting this example in the libpcap tutorial or FAQ or something :)
Thanks for your reply :)
-- Ren
/* Example code on how to use a select() with libpcap
Compile with cc -Wall -o select select.c -lpcap
By Ren Hoek ([EMAIL PROTECTED])
*/
#include <stdio.h>
#include <sys/time.h> /* select */
#include <sys/types.h> /* select */
#include <unistd.h> /* select, exit */
#include <stdlib.h> /* atexit */
#include <pcap.h>
void packet_callback(unsigned char *Args,
const struct pcap_pkthdr* Pkthdr,
unsigned char *Packet)
{
fprintf(stderr, "+"); fflush(stderr);
}
int main(void)
{
int t;
fd_set fd_wait;
struct timeval st;
struct pcap *pcap;
char errbuf[PCAP_ERRBUF_SIZE];
char *device="eth0"; /* Change this to whatever */
pcap = pcap_open_live(device, BUFSIZ, 1, -1, errbuf);
if(pcap == NULL)
{
fprintf(stderr, "Could not open device \"%s\": %s\n", device, errbuf);
exit(1);
}
if(pcap_setnonblock(pcap, 1, errbuf) == 1)
{
fprintf(stderr, "Could not set device \"%s\" to non-blocking: %s\n", device,
errbuf);
exit(1);
}
for(;;)
{
/* If you include STDIN_FILENO, be sure to read from it when you get
traffic from it, or select will return every time it is called,
since there will still be traffic waiting there.
*/
FD_ZERO(&fd_wait);
/*FD_SET(STDIN_FILENO, &fd_wait);*/
FD_SET(pcap_fileno(pcap), &fd_wait);
st.tv_sec = 1;
st.tv_usec = 0; /* 1000 = 1 second */
t=select(FD_SETSIZE, &fd_wait, NULL, NULL, &st);
switch(t)
{
case -1: /* Something went really wrong */
fprintf(stderr, "Argh!\n\n");
exit(1);
case 0: /* We timed out, no trafffic */
fprintf(stderr, ".");
break;
default: /* We got traffic */
pcap_dispatch(pcap, 1, (void *) packet_callback, NULL);
}
/* Put your service routine here.. is called when select times out
or when a packet is processed
*/
} /* End of for(;;) */
} /* End of main() */
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