wt/finit
1
0
Fork 0
mirror of https://github.com/troglobit/finit.git synced 2026-09-30 13:02:37 +07:00
Code Issues Packages Projects Releases Wiki Activity

Fix #170: check for loss of default route when interfaces go down

Browse Source 
This patch fixes the problem with Linux not sending netlink route change
notifications when interfaces for these routes goes down.  When an iface
goes down we now send a route request to the kernel and check the return
message, if no default route is found we deassert net/default/route.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This commit is contained in:
Joachim Wiberg
2021-05-03 15:18:25 +02:00
parent fead3b0671
commit ea8c46cd30
1 changed files with 105 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
plugins/netlink.c
+105 -7
View File
@@ -31,6 +31,9 @@
#include "helpers.h"
#include "plugin.h"
static int ifdown = 0;
static int nlmsg_validate(struct nlmsghdr *nh, size_t len)
{
if (!NLMSG_OK(nh, len))
@@ -51,10 +54,16 @@ static int nlmsg_validate(struct nlmsghdr *nh, size_t len)
static void nl_route(struct nlmsghdr *nlmsg, ssize_t len)
{
char daddr[INET_ADDRSTRLEN];
char gaddr[INET_ADDRSTRLEN];
struct in_addr ind, ing;
struct rtmsg *r;
struct rtattr *a;
int plen = 0;
int dst = 0;
int idx = 0;
int gw = 0;
int la;
int gw = 0, dst = 0, mask = 0, idx = 0;
if (nlmsg->nlmsg_len < NLMSG_LENGTH(sizeof(struct rtmsg))) {
_e("Packet too small or truncated!");
@@ -80,8 +89,8 @@ static void nl_route(struct nlmsghdr *nlmsg, ssize_t len)
case RTA_DST:
dst = *((int *)data);
mask = r->rtm_dst_len;
//_d("MASK: 0x%04x", mask);
plen = r->rtm_dst_len;
//_d("Prefix LEN: 0x%04x", plen);
break;
case RTA_OIF:
@@ -93,7 +102,13 @@ static void nl_route(struct nlmsghdr *nlmsg, ssize_t len)
a = RTA_NEXT(a, la);
}
if ((!dst && !mask) && (gw || idx)) {
ind.s_addr = dst;
ing.s_addr = gw;
inet_ntop(AF_INET, &ind, daddr, sizeof(daddr));
inet_ntop(AF_INET, &ing, gaddr, sizeof(gaddr));
_d("Got gw %s dst/len %s/%d ifindex %d", gaddr, daddr, plen, idx);
if ((!dst && !plen) && (gw || idx)) {
if (nlmsg->nlmsg_type == RTM_DELROUTE)
cond_clear("net/route/default");
else
@@ -101,6 +116,36 @@ static void nl_route(struct nlmsghdr *nlmsg, ssize_t len)
}
}
static int nl_default(struct nlmsghdr *nlh, struct in_addr *dst, struct in_addr *gw)
{
struct in_addr nil = { 0 };
struct rtattr *a;
struct rtmsg *r;
int len;
r = (struct rtmsg *)NLMSG_DATA(nlh);
if ((r->rtm_family != AF_INET) || (r->rtm_table != RT_TABLE_MAIN))
return -1;
len = RTM_PAYLOAD(nlh);
for (a = RTM_RTA(r); RTA_OK(a, len); a = RTA_NEXT(a, len)) {
switch (a->rta_type) {
case RTA_GATEWAY:
memcpy(gw, RTA_DATA(a), sizeof(*gw));
break;
case RTA_DST:
memcpy(dst, RTA_DATA(a), sizeof(*dst));
break;
}
}
if (!memcmp(dst, &nil, sizeof(nil)) && memcmp(gw, &nil, sizeof(nil)))
return 0;
return 1;
}
static void net_cond_set(char *ifname, char *cond, int set)
{
char msg[MAX_ARG_LEN];
@@ -134,10 +179,10 @@ static int validate_ifname(const char *ifname)
static void nl_link(struct nlmsghdr *nlmsg, ssize_t len)
{
int la;
char ifname[IFNAMSIZ + 1];
struct rtattr *a;
struct ifinfomsg *i;
struct rtattr *a;
int la;
if (nlmsg->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifinfomsg))) {
_e("Packet too small or truncated!");
@@ -172,6 +217,8 @@ static void nl_link(struct nlmsghdr *nlmsg, ssize_t len)
net_cond_set(ifname, "exist", 1);
net_cond_set(ifname, "up", i->ifi_flags & IFF_UP);
net_cond_set(ifname, "running", i->ifi_flags & IFF_RUNNING);
if (!(i->ifi_flags & IFF_UP) || !(i->ifi_flags & IFF_RUNNING))
ifdown = 1;
break;
case RTM_DELLINK:
@@ -180,6 +227,7 @@ static void nl_link(struct nlmsghdr *nlmsg, ssize_t len)
net_cond_set(ifname, "exist", 0);
net_cond_set(ifname, "up", 0);
net_cond_set(ifname, "running", 0);
ifdown = 1;
break;
case RTM_NEWADDR:
@@ -211,6 +259,9 @@ static void nl_callback(void *arg, int sd, int events)
return;
}
/* check for interface changes -> loss of default route */
ifdown = 0;
for (nh = (struct nlmsghdr *)buf; !nlmsg_validate(nh, len); nh = NLMSG_NEXT(nh, len)) {
//_d("Well formed netlink message received. type %d ...", nh->nlmsg_type);
if (nh->nlmsg_type == RTM_NEWROUTE || nh->nlmsg_type == RTM_DELROUTE)
@@ -218,6 +269,53 @@ static void nl_callback(void *arg, int sd, int events)
else
nl_link(nh, len);
}
/*
* Linux doesn't send route changes, when interfaces go down, so
* we need to check ourselves, e.g. for loss of default route.
*/
if (ifdown) {
unsigned int seq = 0;
int found = 0;
sd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
if (sd < 0) {
_pe("netlink socket");
return;
}
memset(buf, 0, sizeof(buf));
nh = (struct nlmsghdr *)buf;
nh->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
nh->nlmsg_type = RTM_GETROUTE;
nh->nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
nh->nlmsg_seq = seq++;
nh->nlmsg_pid = 1;
if (send(sd, nh, nh->nlmsg_len, 0) < 0) {
_pe("Failed netlink route request");
close(sd);
return;
}
len = recv(sd, buf, sizeof(buf), 0);
close(sd);
for (; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
struct in_addr dst = { 0 };
struct in_addr gw = { 0 };
if (nl_default(nh, &dst, &gw))
continue;
_d("default via %s\n", inet_ntoa(gw));
found = 1;
}
/* We already get notification when adding default rt */
if (!found)
cond_clear("net/route/default");
}
}
static void nl_reconf(void *arg)
@@ -236,8 +334,8 @@ static plugin_t plugin = {
PLUGIN_INIT(plugin_init)
{
int sd;
struct sockaddr_nl sa;
int sd;
sd = socket(AF_NETLINK, SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC, NETLINK_ROUTE);
if (sd < 0) {