From 2675f2061525bc954be14988d64384b74aa7bf8b Mon Sep 17 00:00:00 2001

From: Beniamino Galvani <bgalvani@redhat.com>

Date: Sun, 28 Aug 2016 20:44:05 +0100

Subject: [PATCH] Handle binding upstream servers to an interface

 (--server=1.2.3.4@eth0) when the named interface is destroyed and recreated

 in the kernel.

---

 CHANGELOG     |  5 +++++

 src/dnsmasq.h |  1 +

 src/network.c | 31 +++++++++++++++++++++++++++++--

 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/dnsmasq.h b/src/dnsmasq.h

index 27385a9..f239ce5 100644

--- a/src/dnsmasq.h

+++ b/src/dnsmasq.h

@@ -488,6 +488,7 @@ struct serverfd {

   int fd;

   union mysockaddr source_addr;

   char interface[IF_NAMESIZE+1];

+  unsigned int ifindex, used;

   struct serverfd *next;

 };

diff --git a/src/network.c b/src/network.c

index e7722fd..ddf8d31 100644

--- a/src/network.c

+++ b/src/network.c

@@ -1204,6 +1204,7 @@ int local_bind(int fd, union mysockaddr *addr, char *intname, int is_tcp)

 static struct serverfd *allocate_sfd(union mysockaddr *addr, char *intname)

 {

   struct serverfd *sfd;

+  unsigned int ifindex = 0;

   int errsave;

   /* when using random ports, servers which would otherwise use

@@ -1224,11 +1225,15 @@ static struct serverfd *allocate_sfd(union mysockaddr *addr, char *intname)

 	return NULL;

 #endif

     }

+

+  if (intname && strlen(intname) != 0)

+    ifindex = if_nametoindex(intname); /* index == 0 when not binding to an interface */

   /* may have a suitable one already */

   for (sfd = daemon->sfds; sfd; sfd = sfd->next )

     if (sockaddr_isequal(&sfd->source_addr, addr) &&

-	strcmp(intname, sfd->interface) == 0)

+	strcmp(intname, sfd->interface) == 0 &&

+	ifindex == sfd->ifindex) 

       return sfd;

   /* need to make a new one. */

@@ -1250,11 +1255,13 @@ static struct serverfd *allocate_sfd(union mysockaddr *addr, char *intname)

       errno = errsave;

       return NULL;

     }

-    

+

   strcpy(sfd->interface, intname); 

   sfd->source_addr = *addr;

   sfd->next = daemon->sfds;

+  sfd->ifindex = ifindex;

   daemon->sfds = sfd;

+

   return sfd; 

 }

@@ -1429,12 +1436,16 @@ void check_servers(void)

 {

   struct irec *iface;

   struct server *serv;

+  struct serverfd *sfd, *tmp, **up;

   int port = 0, count;

   /* interface may be new since startup */

   if (!option_bool(OPT_NOWILD))

     enumerate_interfaces(0);

+  for (sfd = daemon->sfds; sfd; sfd = sfd->next)

+    sfd->used = 0;

+

 #ifdef HAVE_DNSSEC

  /* Disable DNSSEC validation when using server=/domain/.... servers

     unless there's a configured trust anchor. */

@@ -1505,6 +1516,8 @@ void check_servers(void)

 	      serv->flags |= SERV_MARK;

 	      continue;

 	    }

+

+	  serv->sfd->used = 1;

 	}

       if (!(serv->flags & SERV_NO_REBIND) && !(serv->flags & SERV_LITERAL_ADDRESS))

@@ -1547,6 +1560,20 @@ void check_servers(void)

   if (count - 1 > SERVERS_LOGGED)

     my_syslog(LOG_INFO, _("using %d more nameservers"), count - SERVERS_LOGGED - 1);

+  /* Remove unused sfds */

+  for (sfd = daemon->sfds, up = &daemon->sfds; sfd; sfd = tmp)

+    {

+       tmp = sfd->next;

+       if (!sfd->used) 

+	{

+	  *up = sfd->next;

+	  close(sfd->fd);

+	  free(sfd);

+	} 

+      else

+	up = &sfd->next;

+    }

+  

   cleanup_servers();

 }

-- 

2.7.4