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#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <linux/types.h>
#include <linux/if.h>
#include <stdlib.h>
#include <assert.h>
#include "nlrequest.h"
#include "getifn.h"
#define MAX_ROUTES 64
struct nlmsghdr* routes[MAX_ROUTES];
int n_routes = 0;
int enumerate_callback(struct nlmsghdr *n, void *u) {
struct rtmsg *r;
struct rtattr *a = NULL;
int l, *ifn = u;
if (n->nlmsg_type != RTM_NEWROUTE) {
fprintf(stderr, "NETLINK: Got response for wrong request.\n");
return -1;
}
r = NLMSG_DATA(n);
l = NLMSG_PAYLOAD(n, sizeof(struct rtmsg));
a = RTM_RTA(r);
if (r->rtm_table != RT_TABLE_MAIN)
return 0;
while(RTA_OK(a, l)) {
switch(a->rta_type) {
case RTA_OIF:
if (RTA_PAYLOAD(a) != sizeof(int)) {
fprintf(stderr, "NETLINK: Recieved corrupt RTA_OIF payload.\n");
return -1;
}
if (*((int*) RTA_DATA(a)) == *ifn) {
if (n_routes < MAX_ROUTES) {
struct nlmsghdr* copy;
if (!(copy = malloc(n->nlmsg_len))) {
fprintf(stderr, "Could not allocate memory.\n");
return -1;
}
memcpy(copy, n, n->nlmsg_len);
routes[n_routes++] = copy;
} else
fprintf(stderr, "Found too many routes.\n");
break;
}
}
a = RTA_NEXT(a, l);
}
return 0;
}
int enumerate(int s, int ifn) {
struct {
struct nlmsghdr n;
struct rtmsg r;
char a[1024];
} req;
memset(&req, 0, sizeof(req));
req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
req.n.nlmsg_flags = NLM_F_REQUEST|NLM_F_MATCH;
req.n.nlmsg_type = RTM_GETROUTE;
req.r.rtm_family = AF_INET;
req.r.rtm_table = RT_TABLE_MAIN;
return netlink_request(s, (struct nlmsghdr*) &req, enumerate_callback, &ifn);
}
struct nlmsghdr* set_route_metric(struct nlmsghdr* n, int metric) {
struct rtmsg *r;
struct rtattr *a = NULL;
int l, t;
r = NLMSG_DATA(n);
l = NLMSG_PAYLOAD(n, sizeof(struct rtmsg));
a = RTM_RTA(r);
while(RTA_OK(a, l)) {
switch(a->rta_type) {
case RTA_PRIORITY:
if (RTA_PAYLOAD(a) != sizeof(int)) {
fprintf(stderr, "NETLINK: Recieved corrupt RTA_PRIORITY payload.\n");
return NULL;
}
*((int*) RTA_DATA(a)) = metric;
return n;
}
a = RTA_NEXT(a, l);
}
if ((n = realloc(n, (t = n->nlmsg_len+1024))))
addattr32(n, t, RTA_PRIORITY, metric);
else
fprintf(stderr, "realloc() failed.\n");
return n;
}
int delete_route(int s, struct nlmsghdr* n) {
assert(s >= 0 && n);
n->nlmsg_type = RTM_DELROUTE;
n->nlmsg_flags = NLM_F_REQUEST;
return netlink_request(s, n, NULL, NULL);
}
int add_route(int s, struct nlmsghdr* n) {
assert(s >= 0 && n);
n->nlmsg_type = RTM_NEWROUTE;
n->nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE;
return netlink_request(s, n, NULL, NULL);
}
int go(char *iface, int metric) {
int r = -1, j;
int s = -1, ifn;
if ((s = netlink_open()) < 0)
return -1;
if ((ifn = getifn(s, iface)) < 0)
goto finish;
n_routes = 0;
if (enumerate(s, ifn) < 0)
goto finish;
if (n_routes) {
for (j = 0; j < n_routes; j++) {
if (delete_route(s, routes[j]) >= 0)
if ((routes[j] = set_route_metric(routes[j], metric)))
add_route(s, routes[j]);
free(routes[j]);
}
}
r = 0;
finish:
if (s >= 0)
close(s);
return r;
}
int main(int argc, char *argv[]) {
char *iface;
int metric;
if (argc <= 1 || (argc > 1 && (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")))) {
char *b;
if ((b = strrchr(argv[0], '/')))
b++;
else
b = argv[0];
printf("Usage: %s <iface> [metric]\n"
"\n"
"%s is a tool for setting the metrics of all IPv4 routes\n"
"attached to a given network interface at once.\n"
"\n"
" <iface> The interface\n"
" <metric> The new metric (default: 0)\n", b, b);
return 0;
}
iface = argv[1];
metric = argc > 2 ? atoi(argv[2]) : 0;
return go(iface, metric) < 0 ? 1 : 0;
}
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