Here is my problem:
I am preparing a pcmcia-cs package for the next 2.4.16 ("Bering") LEAF
release.
The /etc/pcmcia/network script is using a ifuser utility to see if any of a
list of hosts or network addresses are routed through a specified interface.
This small program call netstat and I would like to modify it in order to get
read of it. I would like to remove the
f = popen("netstat -nr", "r");
by something like
f = popen("cat /proc/net/route","r")
but I am a bit lost in the processing of this file (IP in hex + tabs)
Is there someone around for which this would be a 101 type of C programming
exercice?
Fortran is the only language I have ever practised in my life.
I really feel like a dinosaur...
The program is attached.
gcc ifuser.c -o ifuser
is enough to compile it.
Thanks
Jacques
/*======================================================================
This utility checks to see if any of a list of hosts or network
addresses are routed through a specified interface. Destinations
may be specified either by IP address or by name.
usage: ifuser [-v] interface [target ...]
The exit code is 0 if any host is using the specified interface,
and 1 if the interface is not in use (just like fuser).
ifuser.c 1.16 2001/08/24 12:19:20
1998/10/24: Regis "HPReg" Duchesne <[EMAIL PROTECTED]>
. Added network names (/etc/networks) management
. Used u_int32_t instead of u_int
. Handled a malloc error
The contents of this file are subject to the Mozilla Public
License Version 1.1 (the "License"); you may not use this file
except in compliance with the License. You may obtain a copy of
the License at http://www.mozilla.org/MPL/
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
The initial developer of the original code is David A. Hinds
<[EMAIL PROTECTED]>. Portions created by David A. Hinds
are Copyright (C) 1999 David A. Hinds. All Rights Reserved.
Alternatively, the contents of this file may be used under the
terms of the GNU General Public License version 2 (the "GPL"), in
which case the provisions of the GPL are applicable instead of the
above. If you wish to allow the use of your version of this file
only under the terms of the GPL and not to allow others to use
your version of this file under the MPL, indicate your decision
by deleting the provisions above and replace them with the notice
and other provisions required by the GPL. If you do not delete
the provisions above, a recipient may use your version of this
file under either the MPL or the GPL.
Portions created by Regis "HPReg" Duchesne are Copyright (C) 1998
Regis "HPReg" Duchesne. All Rights Reserved.
======================================================================*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <ctype.h>
#include <netinet/in.h>
#include <arpa/inet.h>
typedef struct route_t {
u_int32_t dest, mask;
int match;
struct route_t *next;
} route_t;
/*====================================================================*/
static int resolv_name(char *s, u_int32_t *a)
{
struct in_addr addr;
struct hostent *hp;
struct netent *np;
if (inet_aton(s, &addr)) {
*a = (u_int32_t)ntohl(addr.s_addr);
return 0;
}
np = getnetbyname(s);
if (np) {
*a = (u_int32_t)np->n_net;
return 0;
}
hp = gethostbyname(s);
if (hp) {
*a = (u_int32_t)ntohl(*(u_int32_t *)hp->h_addr_list[0]);
return 0;
}
return -1;
}
/*====================================================================*/
static void usage(char *s)
{
fprintf(stderr, "usage: %s [-v] interface [target ...]\n", s);
exit(1);
}
int main(int argc, char *argv[])
{
char *dev, s[129], dest[16], mask[16], iface[10];
route_t *r, *tbl, **tail;
int i, verbose = 0, busy = 0;
FILE *f;
i = 1;
if (argc < 2) usage(argv[0]);
if (strcmp(argv[1], "-v") == 0) {
verbose = 1; i++;
}
if ((*argv[i] == '-') || (argc < i+1)) usage(argv[0]);
dev = argv[i]; i++;
/* Get routing table */
f = popen("netstat -nr", "r");
if (f == NULL) {
fprintf(stderr, "%s: could not get routing table: %s\n",
argv[0], strerror(errno));
return 2;
}
do {
fgets(s, 128, f);
} while (!feof(f) && !isdigit(s[0]));
tail = &tbl;
do {
r = malloc(sizeof(route_t));
if (r == NULL) {
fprintf(stderr, "%s: out of memory\n", argv[0]);
return 2;
}
sscanf(s, "%s %*s %s %*s %*s %*s %*s %s", dest, mask, iface);
resolv_name(dest, &r->dest);
resolv_name(mask, &r->mask);
r->match = (strcmp(iface, dev) == 0);
*tail = r; tail = &(r->next);
} while (fgets(s, 128, f) != NULL);
*tail = NULL;
pclose(f);
/* Check each host on command line */
for (; i < argc; i++) {
u_int32_t a;
if (resolv_name(argv[i], &a) != 0) {
fprintf(stderr, "%s: lookup failed: %s\n",
argv[0], argv[i]);
continue;
}
for (r = tbl; r; r = r->next) {
if ((a & r->mask) == r->dest) {
if (r->match) {
if (verbose) {
if (!busy) printf("%s:", dev);
printf(" %s", argv[i]);
}
busy = 1;
}
break;
}
}
}
if (busy && verbose)
printf("\n");
return (!busy);
}
