Date: Mon, 28 Feb 2000 05:18:29 -0800 From: Rahul Dhesi <dhesi@rahul.net> To: freebsd-stable@freebsd.org Subject: divert(4) non-working code example Message-ID: <20000228131831.63A783FF09@bolero.rahul.net>
next in thread | raw e-mail | index | archive | help
The following is a relatively simple program that should read and write
divert-ed packets, without modifying them. But it never returns from the
recvfrom() system call. Any suggestions?
An extensive web search appears to indicate that only one existing
program, i.e., natd(8), uses divert(4). I found no other examples of
anybody using divert(4).
Rahul
-- cut here --
/* TEST PROGRAM TO SEE IF divert(4) will work */
/*
FreeBSD 3.4-STABLE. Kernel currently include options
DUMMYNET, IPDIVERT, IPFIREWALL, and IPFIREWALL_DEFAULT_TO_ACCEPT.
This code is based on information from the divert(4) man page
and also after examining the natd(8) source code.
To test:
cc -o testdivert testdivert.c
./testdivert >& Log &
ipfw add 1 divert 22222 all from 0.0.0.0/0 to xx.xx.xx.xx/32
where xx.xx.xx.xx is the IP address of some other host.
Now ping xx.xx.xx.xx. Each ping packet should result in an entry
being made into the file 'Log'. But in fact I see no output into
'Log' and no traffic to xx.xx.xx.xx gets through. Tracing with ktrace
shows that testdivert is waiting for recvfrom() to return.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
/* required by netinet/ip.h */
#include <netinet/in_systm.h>
/* to define IP_MAXPACKET */
#include <netinet/ip.h>
/* big enough to hold a network packet */
#define SZ_PACKET IP_MAXPACKET
static char *myname = "testdivert";
int main(int argc, char **argv)
{
unsigned port = 22222;
int socket_fd = -1;
char packetbuf[SZ_PACKET];
struct sockaddr_in addr;
/* make the socket */
socket_fd = socket(PF_INET, SOCK_RAW, IPPROTO_DIVERT);
if (socket_fd == -1) {
(void) fprintf(stderr, "%s: error: can't make socket: %s\n",
myname, strerror(errno));
exit(1);
}
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY); /* will be ignored by bind() */
addr.sin_port = port;
if (bind(socket_fd, (struct sockaddr *) &addr, sizeof addr) == -1) {
(void) fprintf(stderr,
"%s: error: can't bind socket to port %u: %s\n",
myname, port, strerror(errno));
exit(1);
}
(void) fprintf(stdout, "%s: note: socket_fd is %d, port is %d\n",
myname, socket_fd, port);
/* make output unbufferd so we can print status dots */
(void) setbuf(stdout, (char *) NULL);
/* go into read/write loop */
for ( ; ; ) {
int incount;
int addrlen;
addrlen = sizeof addr;
incount = recvfrom(socket_fd, packetbuf, sizeof packetbuf, 0,
(struct sockaddr *) &addr, &addrlen);
if (incount >= 0) {
int sendstatus;
(void) fprintf(stdout, "<"); /* < means got a packet */
sendstatus = sendto(socket_fd, packetbuf, incount, 0,
(struct sockaddr *) &addr, sizeof addr);
if (sendstatus != -1) {
(void) fprintf(stdout, ">"); /* > means sent a packet */
} else {
(void) fprintf(stdout, "?"); /* ? = send error */
}
} else {
(void) fprintf(stdout, "."); /* . = receive error */
}
}
/*NOTREACHED*/
return 0;
}
-- cut here --
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-stable" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20000228131831.63A783FF09>