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From bfa1d68bed863e22c40a6d9a19ffbcc8694bbff6 Mon Sep 17 00:00:00 2001
From: Nate Karstens <nate.karstens@garmin.com>
Date: Mon, 24 Jul 2017 09:38:55 -0500
Subject: [PATCH 6/8] Handle noisy netlink sockets
The POSIX implementation currently clears all network interfaces
when netlink indicates that there has been a change. This causes
the following problems:
1) Applications are informed that all of the services they are
tracking have been removed.
2) Increases network load because the client must re-query for
all records it is interested in.
This changes netlink notification handling by:
1) Always comparing with the latest interface list returned
by the OS.
2) Confirming that the interface has been changed in a way
that we care about.
Upstream-Status: Submitted [dts@apple.com]
Signed-off-by: Nate Karstens <nate.karstens@garmin.com>
Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
---
mDNSPosix/mDNSPosix.c | 182 +++++++++++++++++++++++++++++++++++++++---
1 file changed, 172 insertions(+), 10 deletions(-)
Index: mDNSResponder/mDNSPosix/mDNSPosix.c
===================================================================
--- mDNSResponder.orig/mDNSPosix/mDNSPosix.c
+++ mDNSResponder/mDNSPosix/mDNSPosix.c
@@ -1788,14 +1788,43 @@ mDNSlocal void ProcessRoutingNo
#endif // USES_NETLINK
+// Test whether the given PosixNetworkInterface matches the given struct ifaddrs
+mDNSlocal mDNSBool InterfacesMatch(PosixNetworkInterface *intf, struct ifaddrs *ifi)
+{
+ mDNSBool match = mDNSfalse;
+ mDNSAddr ip, mask;
+ unsigned int if_index;
+
+ if_index = if_nametoindex(ifi->ifa_name);
+ if (if_index == 0)
+ return mDNSfalse;
+
+ if((intf->index == if_index) &&
+ (intf->sa_family == ifi->ifa_addr->sa_family) &&
+ (strcmp(intf->coreIntf.ifname, ifi->ifa_name) == 0))
+ {
+ SockAddrTomDNSAddr(ifi->ifa_addr, &ip, NULL);
+ SockAddrTomDNSAddr(ifi->ifa_netmask, &mask, NULL);
+
+ match = mDNSSameAddress(&intf->coreIntf.ip, &ip) &&
+ mDNSSameAddress(&intf->coreIntf.mask, &mask);
+ }
+
+ return match;
+}
+
// Called when data appears on interface change notification socket
mDNSlocal void InterfaceChangeCallback(int fd, void *context)
{
IfChangeRec *pChgRec = (IfChangeRec*) context;
+ mDNS *m = pChgRec->mDNS;
fd_set readFDs;
GenLinkedList changedInterfaces;
NetworkInterfaceIndex *changedInterface;
struct timeval zeroTimeout = { 0, 0 };
+ struct ifaddrs *ifa_list, **ifi, *ifa_loop4 = NULL;
+ PosixNetworkInterface *intf, *intfNext;
+ mDNSBool found, foundav4;
(void)fd; // Unused
@@ -1810,12 +1839,149 @@ mDNSlocal void InterfaceChangeCallback(i
}
while (0 < select(pChgRec->NotifySD + 1, &readFDs, (fd_set*) NULL, (fd_set*) NULL, &zeroTimeout));
- // Currently we rebuild the entire interface list whenever any interface change is
- // detected. If this ever proves to be a performance issue in a multi-homed
- // configuration, more care should be paid to changedInterfaces.
- if (changedInterfaces.Head != NULL)
- mDNSPlatformPosixRefreshInterfaceList(pChgRec->mDNS);
+ CleanRecentInterfaces();
+
+ if (changedInterfaces.Head == NULL) goto cleanup;
+
+ if (getifaddrs(&ifa_list) < 0) goto cleanup;
+
+ for (intf = (PosixNetworkInterface*)(m->HostInterfaces); intf != NULL; intf = intfNext)
+ {
+ intfNext = (PosixNetworkInterface*)(intf->coreIntf.next);
+
+ // Loopback interface(s) are handled later
+ if (intf->coreIntf.Loopback) continue;
+
+ found = mDNSfalse;
+ for (ifi = &ifa_list; *ifi != NULL; ifi = &(*ifi)->ifa_next)
+ {
+ if (InterfacesMatch(intf, *ifi))
+ {
+ found = mDNStrue;
+ break;
+ }
+ }
+
+ // Removes changed and old interfaces from m->HostInterfaces
+ if (!found) TearDownInterface(m, intf);
+ }
+
+ // Add new and changed interfaces in ifa_list
+ // Save off loopback interface in case it is needed later
+ for (ifi = &ifa_list; *ifi != NULL; ifi = &(*ifi)->ifa_next)
+ {
+ found = mDNSfalse;
+ for (intf = (PosixNetworkInterface*)(m->HostInterfaces); intf != NULL; intf = intfNext)
+ {
+ intfNext = (PosixNetworkInterface*)(intf->coreIntf.next);
+
+ // Loopback interface(s) are handled later
+ if (intf->coreIntf.Loopback) continue;
+
+ if (InterfacesMatch(intf, *ifi))
+ {
+ found = mDNStrue;
+ break;
+ }
+
+ // Removes changed and old interfaces from m->HostInterfaces
+ }
+ if (found)
+ continue;
+
+ if ((ifa_loop4 == NULL) &&
+ ((*ifi)->ifa_addr->sa_family == AF_INET) &&
+ ((*ifi)->ifa_flags & IFF_UP) &&
+ ((*ifi)->ifa_flags & IFF_LOOPBACK))
+ {
+ ifa_loop4 = *ifi;
+ continue;
+ }
+
+ if ( (((*ifi)->ifa_addr->sa_family == AF_INET)
+#if HAVE_IPV6
+ || ((*ifi)->ifa_addr->sa_family == AF_INET6)
+#endif
+ ) && ((*ifi)->ifa_flags & IFF_UP)
+ && !((*ifi)->ifa_flags & IFF_POINTOPOINT)
+ && !((*ifi)->ifa_flags & IFF_LOOPBACK))
+ {
+ struct ifaddrs *i = *ifi;
+
+#define ethernet_addr_len 6
+ uint8_t hwaddr[ethernet_addr_len];
+ int hwaddr_len = 0;
+
+#if defined(TARGET_OS_LINUX) && TARGET_OS_LINUX
+ struct ifreq ifr;
+ int sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
+ if (sockfd >= 0)
+ {
+ /* Add hardware address */
+ memcpy(ifr.ifr_name, i->ifa_name, IFNAMSIZ);
+ if (ioctl(sockfd, SIOCGIFHWADDR, &ifr) != -1)
+ {
+ if (ifr.ifr_hwaddr.sa_family == ARPHRD_ETHER)
+ {
+ memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, ethernet_addr_len);
+ hwaddr_len = ethernet_addr_len;
+ }
+ }
+ close(sockfd);
+ }
+ else
+ {
+ memset(hwaddr, 0, sizeof(hwaddr));
+ }
+#endif // TARGET_OS_LINUX
+ SetupOneInterface(m, i->ifa_addr, i->ifa_netmask,
+ hwaddr, hwaddr_len, i->ifa_name, if_nametoindex(i->ifa_name), i->ifa_flags);
+ }
+ }
+
+ // Determine if there is at least one non-loopback IPv4 interface. This is to work around issues
+ // with multicast loopback on IPv6 interfaces -- see corresponding logic in SetupInterfaceList().
+ foundav4 = mDNSfalse;
+ for (intf = (PosixNetworkInterface*)(m->HostInterfaces); intf != NULL; intf = (PosixNetworkInterface*)(intf->coreIntf.next))
+ {
+ if (intf->sa_family == AF_INET && !intf->coreIntf.Loopback)
+ {
+ foundav4 = mDNStrue;
+ break;
+ }
+ }
+
+ if (foundav4)
+ {
+ for (intf = (PosixNetworkInterface*)(m->HostInterfaces); intf != NULL; intf = intfNext)
+ {
+ intfNext = (PosixNetworkInterface*)(intf->coreIntf.next);
+ if (intf->coreIntf.Loopback) TearDownInterface(m, intf);
+ }
+ }
+ else
+ {
+ found = mDNSfalse;
+
+ for (intf = (PosixNetworkInterface*)(m->HostInterfaces); intf != NULL; intf = (PosixNetworkInterface*)(intf->coreIntf.next))
+ {
+ if (intf->coreIntf.Loopback)
+ {
+ found = mDNStrue;
+ break;
+ }
+ }
+
+ if (!found && (ifa_loop4 != NULL))
+ {
+ SetupOneInterface(m, ifa_loop4->ifa_addr, ifa_loop4->ifa_netmask,
+ NULL, 0, ifa_loop4->ifa_name, if_nametoindex(ifa_loop4->ifa_name), ifa_loop4->ifa_flags);
+ }
+ }
+
+ if (ifa_list != NULL) freeifaddrs(ifa_list);
+cleanup:
while ((changedInterface = (NetworkInterfaceIndex*)changedInterfaces.Head) != NULL)
{
RemoveFromList(&changedInterfaces, changedInterface);
@@ -1947,15 +2113,11 @@ mDNSexport void mDNSPlatformClose(mDNS *
#endif
}
-// This is used internally by InterfaceChangeCallback.
-// It's also exported so that the Standalone Responder (mDNSResponderPosix)
+// This is exported so that the Standalone Responder (mDNSResponderPosix)
// can call it in response to a SIGHUP (mainly for debugging purposes).
mDNSexport mStatus mDNSPlatformPosixRefreshInterfaceList(mDNS *const m)
{
int err;
- // This is a pretty heavyweight way to process interface changes --
- // destroying the entire interface list and then making fresh one from scratch.
- // We should make it like the OS X version, which leaves unchanged interfaces alone.
ClearInterfaceList(m);
err = SetupInterfaceList(m);
return PosixErrorToStatus(err);
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