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Examine RTM_NEWADDR, RTM_DELADDR messages contents

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This commit modifies the NetLink handling code in such a way
that the contents of the messages we are interested in is checked
for the local addresses changes only. This helps to avoid spurious
interface re-scans.

The 'route_recv' log messages are also reduced from DEBUG(3) to
DEBUG(9).
This commit is contained in:
Artem Boldariev 2021-12-14 13:38:28 +02:00 committed by Evan Hunt
parent 4861f7d76e
commit fb4e1ed5b2
1 changed files with 103 additions and 15 deletions
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118
lib/ns/interfacemgr.c
View file

@ -40,6 +40,7 @@
#endif /* ifdef HAVE_NET_ROUTE_H */
#if defined(HAVE_LINUX_NETLINK_H) && defined(HAVE_LINUX_RTNETLINK_H)
#define LINUX_NETLINK_AVAILABLE
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#if defined(RTM_NEWADDR) && defined(RTM_DELADDR)
@ -102,14 +103,105 @@ scan_event(isc_task_t *task, isc_event_t *event) {
isc_event_free(&event);
}
static bool
need_rescan(ns_interfacemgr_t *mgr, struct MSGHDR *rtm, size_t len) {
if (rtm->MSGTYPE != RTM_NEWADDR && rtm->MSGTYPE != RTM_DELADDR) {
return (false);
}
#ifndef LINUX_NETLINK_AVAILABLE
UNUSED(mgr);
UNUSED(len);
/* On most systems, any NEWADDR or DELADDR means we rescan */
return (true);
#else /* LINUX_NETLINK_AVAILABLE */
/* ...but on linux we need to check the messages more carefully */
for (struct MSGHDR *nlh = rtm;
NLMSG_OK(nlh, len) && nlh->nlmsg_type != NLMSG_DONE;
nlh = NLMSG_NEXT(nlh, len))
{
struct ifaddrmsg *ifa = (struct ifaddrmsg *)NLMSG_DATA(nlh);
struct rtattr *rth = IFA_RTA(ifa);
size_t rtl = IFA_PAYLOAD(nlh);
while (rtl > 0 && RTA_OK(rth, rtl)) {
/*
* Look for IFA_ADDRESS to detect IPv6 interface
* state changes.
*/
if (rth->rta_type == IFA_ADDRESS &&
ifa->ifa_family == AF_INET6) {
bool was_listening = false;
isc_netaddr_t addr = { 0 };
ns_interface_t *ifp = NULL;
isc_netaddr_fromin6(&addr, RTA_DATA(rth));
/*
* Check whether we were listening on the
* address. We need to do this as the
* Linux kernel seems to issue messages
* containing IFA_ADDRESS far more often
* than the actual state changes (on
* router advertisements?)
*/
LOCK(&mgr->lock);
for (ifp = ISC_LIST_HEAD(mgr->interfaces);
ifp != NULL;
ifp = ISC_LIST_NEXT(ifp, link))
{
isc_netaddr_t tmp = { 0 };
isc_netaddr_fromsockaddr(&tmp,
&ifp->addr);
if (isc_netaddr_equal(&tmp, &addr)) {
was_listening = true;
break;
}
}
UNLOCK(&mgr->lock);
/*
* Do rescan if the state of the interface
* has changed.
*/
if ((!was_listening &&
rtm->MSGTYPE == RTM_NEWADDR) ||
(was_listening &&
rtm->MSGTYPE == RTM_DELADDR))
{
return (true);
}
} else if (rth->rta_type == IFA_ADDRESS &&
ifa->ifa_family == AF_INET) {
/*
* It seems that the IPv4 P2P link state
* has changed.
*/
return (true);
} else if (rth->rta_type == IFA_LOCAL) {
/*
* Local address state has changed - do
* rescan.
*/
return (true);
}
rth = RTA_NEXT(rth, rtl);
}
}
#endif /* LINUX_NETLINK_AVAILABLE */
return (false);
}
static void
route_recv(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
void *arg) {
ns_interfacemgr_t *mgr = (ns_interfacemgr_t *)arg;
struct MSGHDR *rtm = NULL;
bool done = true;
size_t rtmlen;
isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_DEBUG(3), "route_recv: %s",
isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_DEBUG(9), "route_recv: %s",
isc_result_totext(eresult));
if (handle == NULL) {
@ -137,6 +229,8 @@ route_recv(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
}
rtm = (struct MSGHDR *)region->base;
rtmlen = region->length;
#ifdef RTM_VERSION
if (rtm->rtm_version != RTM_VERSION) {
isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
@ -150,19 +244,13 @@ route_recv(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
}
#endif /* ifdef RTM_VERSION */
switch (rtm->MSGTYPE) {
case RTM_NEWADDR:
case RTM_DELADDR:
if (mgr->route != NULL && mgr->sctx->interface_auto) {
isc_event_t *event = NULL;
event = isc_event_allocate(mgr->mctx, mgr,
NS_EVENT_IFSCAN, scan_event,
mgr, sizeof(*event));
isc_task_send(mgr->excl, &event);
}
break;
default:
break;
if (need_rescan(mgr, rtm, rtmlen) && mgr->route != NULL &&
mgr->sctx->interface_auto)
{
isc_event_t *event = NULL;
event = isc_event_allocate(mgr->mctx, mgr, NS_EVENT_IFSCAN,
scan_event, mgr, sizeof(*event));
isc_task_send(mgr->excl, &event);
}
LOCK(&mgr->lock);
@ -183,7 +271,7 @@ static void
route_connected(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
ns_interfacemgr_t *mgr = (ns_interfacemgr_t *)arg;
isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_DEBUG(3),
isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_DEBUG(9),
"route_connected: %s", isc_result_totext(eresult));
if (eresult != ISC_R_SUCCESS) {