From 3f2873d42c4d7e7dba32b6e64a3687d43928bc8e Mon Sep 17 00:00:00 2001

From: Simon Kelley <simon@thekelleys.org.uk>

Date: Tue, 14 May 2013 11:28:47 +0100

Subject: [PATCH]  Handle IPv4 interface-address labels in Linux.

---

 CHANGELOG     |  9 +++++++++

 src/bpf.c     |  2 +-

 src/dhcp.c    | 14 +++++++++-----

 src/dnsmasq.h |  1 +

 src/forward.c |  3 ++-

 src/lease.c   |  3 ++-

 src/netlink.c |  7 +++++--

 src/network.c | 39 +++++++++++++++++++++++++++++++--------

 src/tftp.c    |  3 ++-

 9 files changed, 62 insertions(+), 19 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG

index f6ce80e..7aa0024 100644

--- a/CHANGELOG

+++ b/CHANGELOG

@@ -21,6 +21,15 @@ version 2.67

	    Fix --dhcp-match, --dhcp-vendorclass and --dhcp-userclass

	    to work with BOOTP and well as DHCP. Thanks to Peter

	    Korsgaard for spotting the problem. 

+

+	    Handle IPv4 interface-address labels in Linux. These are

+	    often used to emulate the old IP-alias addresses. Before,

+	    using --interface=eth0 would service all the addresses of

+	    eth0, including ones configured as aliases, which appear

+	    in ifconfig as eth0:0. Now, only addresses with the label

+	    eth0 are active. This is not backwards compatible: if you

+	    want to continue to bind the aliases too, you need to add

+	    eg. --interface=eth0:0 to the config. 

 version 2.66

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

index 02a3abb..e75b0c6 100644

--- a/src/bpf.c

+++ b/src/bpf.c

@@ -123,7 +123,7 @@ int iface_enumerate(int family, void *parm, int (*callback)())

 		broadcast = ((struct sockaddr_in *) addrs->ifa_broadaddr)->sin_addr; 

 	      else 

 		broadcast.s_addr = 0;	      

-	      if (!((*callback)(addr, iface_index, netmask, broadcast, parm)))

+	      if (!((*callback)(addr, iface_index, NULL, netmask, broadcast, parm)))

 		goto err;

 	    }

 #ifdef HAVE_IPV6

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

index dd25632..333a327 100644

--- a/src/dhcp.c

+++ b/src/dhcp.c

@@ -28,9 +28,9 @@ struct match_param {

   struct in_addr netmask, broadcast, addr;

 };

-static int complete_context(struct in_addr local, int if_index, 

+static int complete_context(struct in_addr local, int if_index, char *label,

 			    struct in_addr netmask, struct in_addr broadcast, void *vparam);

-static int check_listen_addrs(struct in_addr local, int if_index, 

+static int check_listen_addrs(struct in_addr local, int if_index, char *label,

 			      struct in_addr netmask, struct in_addr broadcast, void *vparam);

 static int make_fd(int port)

@@ -287,7 +287,7 @@ void dhcp_packet(time_t now, int pxe_fd)

       iface_addr = match.addr;

       /* make sure secondary address gets priority in case

 	 there is more than one address on the interface in the same subnet */

-      complete_context(match.addr, iface_index, match.netmask, match.broadcast, &parm;;

+      complete_context(match.addr, iface_index, NULL, match.netmask, match.broadcast, &parm;;

     }    

   if (!iface_enumerate(AF_INET, &parm, complete_context))

@@ -411,12 +411,14 @@ void dhcp_packet(time_t now, int pxe_fd)

 }

 /* check against secondary interface addresses */

-static int check_listen_addrs(struct in_addr local, int if_index, 

+static int check_listen_addrs(struct in_addr local, int if_index, char *label,

 			      struct in_addr netmask, struct in_addr broadcast, void *vparam)

 {

   struct match_param *param = vparam;

   struct iname *tmp;

+  (void) label;

+

   if (if_index == param->ind)

     {

       for (tmp = daemon->if_addrs; tmp; tmp = tmp->next)

@@ -444,11 +446,13 @@ static int check_listen_addrs(struct in_addr local, int if_index,

    Note that the current chain may be superceded later for configured hosts or those coming via gateways. */

-static int complete_context(struct in_addr local, int if_index, 

+static int complete_context(struct in_addr local, int if_index, char *label,

 			    struct in_addr netmask, struct in_addr broadcast, void *vparam)

 {

   struct dhcp_context *context;

   struct iface_param *param = vparam;

+

+  (void)label;

   for (context = daemon->dhcp; context; context = context->next)

     {

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

index e177cea..8866dd8 100644

--- a/src/dnsmasq.h

+++ b/src/dnsmasq.h

@@ -1030,6 +1030,7 @@ void create_bound_listeners(int die);

 int is_dad_listeners(void);

 int iface_check(int family, struct all_addr *addr, char *name, int *auth_dns);

 int loopback_exception(int fd, int family, struct all_addr *addr, char *name);

+int label_exception(int index, int family, struct all_addr *addr);

 int fix_fd(int fd);

 int tcp_interface(int fd, int af);

 struct in_addr get_ifaddr(char *intr);

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

index 78495ca..28fe9eb 100644

--- a/src/forward.c

+++ b/src/forward.c

@@ -789,7 +789,8 @@ void receive_query(struct listener *listen, time_t now)

 	{

 	   if (!option_bool(OPT_CLEVERBIND))

 	     enumerate_interfaces(); 

-	   if (!loopback_exception(listen->fd, listen->family, &dst_addr, ifr.ifr_name))

+	   if (!loopback_exception(listen->fd, listen->family, &dst_addr, ifr.ifr_name) &&

+	       !label_exception(if_index, listen->family, &dst_addr))

 	     return;

 	}

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

index a4560ba..b85cf57 100644

--- a/src/lease.c

+++ b/src/lease.c

@@ -345,11 +345,12 @@ void lease_update_file(time_t now)

 }

-static int find_interface_v4(struct in_addr local, int if_index, 

+static int find_interface_v4(struct in_addr local, int if_index, char *label,

 			     struct in_addr netmask, struct in_addr broadcast, void *vparam)

 {

   struct dhcp_lease *lease;

+  (void) label;

   (void) broadcast;

   (void) vparam;

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

index 0881b71..78d0926 100644

--- a/src/netlink.c

+++ b/src/netlink.c

@@ -215,7 +215,8 @@ int iface_enumerate(int family, void *parm, int (*callback)())

 		if (ifa->ifa_family == AF_INET)

 		  {

 		    struct in_addr netmask, addr, broadcast;

-		    

+		    char *label = NULL;

+

 		    netmask.s_addr = htonl(0xffffffff << (32 - ifa->ifa_prefixlen));

 		    addr.s_addr = 0;

 		    broadcast.s_addr = 0;

@@ -226,12 +227,14 @@ int iface_enumerate(int family, void *parm, int (*callback)())

 			  addr = *((struct in_addr *)(rta+1));

 			else if (rta->rta_type == IFA_BROADCAST)

 			  broadcast = *((struct in_addr *)(rta+1));

+			else if (rta->rta_type == IFA_LABEL)

+			  label = RTA_DATA(rta);

 			rta = RTA_NEXT(rta, len1);

 		      }

 		    if (addr.s_addr && callback_ok)

-		      if (!((*callback)(addr, ifa->ifa_index, netmask, broadcast, parm)))

+		      if (!((*callback)(addr, ifa->ifa_index, label,  netmask, broadcast, parm)))

 			callback_ok = 0;

 		  }

 #ifdef HAVE_IPV6

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

index 792914b..473e85f 100644

--- a/src/network.c

+++ b/src/network.c

@@ -204,7 +204,27 @@ int loopback_exception(int fd, int family, struct all_addr *addr, char *name)

   return 0;

 }

-static int iface_allowed(struct irec **irecp, int if_index, 

+/* If we're configured with something like --interface=eth0:0 then we'll listen correctly

+   on the relevant address, but the name of the arrival interface, derived from the

+   index won't match the config. Check that we found an interface address for the arrival 

+   interface: daemon->interfaces must be up-to-date. */

+int label_exception(int index, int family, struct all_addr *addr)

+{

+  struct irec *iface;

+

+  /* labels only supported on IPv4 addresses. */

+  if (family != AF_INET)

+    return 0;

+

+  for (iface = daemon->interfaces; iface; iface = iface->next)

+    if (iface->index == index && iface->addr.sa.sa_family == AF_INET &&

+	iface->addr.in.sin_addr.s_addr == addr->addr.addr4.s_addr)

+      return 1;

+

+  return 0;

+}

+

+static int iface_allowed(struct irec **irecp, int if_index, char *label,

 			 union mysockaddr *addr, struct in_addr netmask, int dad) 

 {

   struct irec *iface;

@@ -242,8 +262,8 @@ static int iface_allowed(struct irec **irecp, int if_index,

   loopback = ifr.ifr_flags & IFF_LOOPBACK;

   if (loopback)

-     dhcp_ok = 0;

-

+    dhcp_ok = 0;

+  

   if (ioctl(fd, SIOCGIFMTU, &ifr) != -1)

     mtu = ifr.ifr_mtu;

@@ -272,13 +292,16 @@ static int iface_allowed(struct irec **irecp, int if_index,

 	}

     }

+  if (!label)

+    label = ifr.ifr_name;

+

   if (addr->sa.sa_family == AF_INET &&

-      !iface_check(AF_INET, (struct all_addr *)&addr->in.sin_addr, ifr.ifr_name, &auth_dns))

+      !iface_check(AF_INET, (struct all_addr *)&addr->in.sin_addr, label, &auth_dns))

     return 1;

 #ifdef HAVE_IPV6

   if (addr->sa.sa_family == AF_INET6 &&

-      !iface_check(AF_INET6, (struct all_addr *)&addr->in6.sin6_addr, ifr.ifr_name, &auth_dns))

+      !iface_check(AF_INET6, (struct all_addr *)&addr->in6.sin6_addr, label, &auth_dns))

     return 1;

 #endif

@@ -348,11 +371,11 @@ static int iface_allowed_v6(struct in6_addr *local, int prefix,

   addr.in6.sin6_port = htons(daemon->port);

   addr.in6.sin6_scope_id = if_index;

-  return iface_allowed((struct irec **)vparam, if_index, &addr, netmask, !!(flags & IFACE_TENTATIVE));

+  return iface_allowed((struct irec **)vparam, if_index, NULL, &addr, netmask, !!(flags & IFACE_TENTATIVE));

 }

 #endif

-static int iface_allowed_v4(struct in_addr local, int if_index, 

+static int iface_allowed_v4(struct in_addr local, int if_index, char *label,

 			    struct in_addr netmask, struct in_addr broadcast, void *vparam)

 {

   union mysockaddr addr;

@@ -366,7 +389,7 @@ static int iface_allowed_v4(struct in_addr local, int if_index,

   addr.in.sin_addr = local;

   addr.in.sin_port = htons(daemon->port);

-  return iface_allowed((struct irec **)vparam, if_index, &addr, netmask, 0);

+  return iface_allowed((struct irec **)vparam, if_index, label, &addr, netmask, 0);

 }

 int enumerate_interfaces(void)

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

index 960b1ee..d7d050f 100644

--- a/src/tftp.c

+++ b/src/tftp.c

@@ -202,7 +202,8 @@ void tftp_request(struct listener *listen, time_t now)

 	{

 	  if (!option_bool(OPT_CLEVERBIND))

 	    enumerate_interfaces(); 

-	  if (!loopback_exception(listen->tftpfd, listen->family, &addra, name))

+	  if (!loopback_exception(listen->tftpfd, listen->family, &addra, name) &&

+	      !label_exception(if_index, listen->family, &addra) )

 	    return;

 	}

-- 

1.8.1.4