Bug 1883 - IPv6 don't consider the prefix and network when choosing output address

RELEASE_NOTES

@@ -50,6 +50,7 @@ Bugs fixed
 - Bug 1870 - Remove unnecessary AsInt functions
 - Bug 1874 - Ipv4L3Protocol::ProcessFragment: addressCombination and idProto identifiers not properly computed
 - Bug 1882 - int64x64 tests trigger valgrind bug
+- Bug 1883 - IPv6 don't consider the prefix and network when choosing output address
 
 Release 3.19
 =============

src/applications/model/ping6.cc

@@ -171,13 +171,14 @@ void Ping6::Send ()
       /* hack to have ifIndex in Ipv6RawSocketImpl
        * maybe add a SetIfIndex in Ipv6RawSocketImpl directly 
        */
-      Ipv6InterfaceAddress dstIa (m_peerAddress);
       for (uint32_t i = 0; i < GetNode ()->GetObject<Ipv6> ()->GetNAddresses (m_ifIndex); i++)
         {
-          src = GetNode ()->GetObject<Ipv6> ()->GetAddress (m_ifIndex, i).GetAddress ();
-          Ipv6InterfaceAddress srcIa (src);
-          if ( srcIa.GetScope() == dstIa.GetScope() )
+          Ipv6InterfaceAddress srcIa;
+          srcIa = GetNode ()->GetObject<Ipv6> ()->GetAddress (m_ifIndex, i);
+
+          if (srcIa.IsInSameSubnet (m_peerAddress))
             {
+              src = srcIa.GetAddress ();
               break;
             }
         }

src/internet/model/ipv6-interface-address.cc

@@ -137,6 +137,29 @@ Ipv6InterfaceAddress::Scope_e Ipv6InterfaceAddress::GetScope () const
   return m_scope;
 }
 
+bool Ipv6InterfaceAddress::IsInSameSubnet (Ipv6Address b) const
+{
+  NS_LOG_FUNCTION_NOARGS ();
+
+  Ipv6Address aAddr = m_address;
+  aAddr = aAddr.CombinePrefix (m_prefix);
+  Ipv6Address bAddr = b;
+  bAddr = bAddr.CombinePrefix (m_prefix);
+
+  if (aAddr == bAddr)
+    {
+      return true;
+    }
+
+  if ((bAddr.IsLinkLocalMulticast () && aAddr.IsLinkLocal ()) ||
+      (aAddr.IsLinkLocalMulticast () && bAddr.IsLinkLocal ()))
+    {
+      return true;
+    }
+
+  return false;
+}
+
 std::ostream& operator<< (std::ostream& os, const Ipv6InterfaceAddress &addr)
 {
   os << "address: " << addr.GetAddress () << addr.GetPrefix () << "; scope: ";

src/internet/model/ipv6-interface-address.h

@@ -133,6 +133,13 @@ public:
    */
   Ipv6InterfaceAddress::Scope_e GetScope () const;
 
+  /**
+   * \brief Checks if the address is in the same subnet.
+   * \param b the address to check
+   * \return true if the address is in the same subnet.
+   */
+  bool IsInSameSubnet (Ipv6Address b) const;
+
   /**
    * \brief Set the latest DAD probe packet UID.
    * \param uid packet uid

src/internet/model/ipv6-static-routing.cc

@@ -309,7 +309,7 @@ Ptr<Ipv6Route> Ipv6StaticRouting::LookupStatic (Ipv6Address dst, Ptr<NetDevice>
 
       if (mask.IsMatch (dst, entry))
         {
-          NS_LOG_LOGIC ("Found global network route " << j << ", mask length " << maskLen << ", metric " << metric);
+          NS_LOG_LOGIC ("Found global network route " << *j << ", mask length " << maskLen << ", metric " << metric);
 
           /* if interface is given, check the route will output on this interface */
           if (!interface || interface == m_ipv6->GetNetDevice (j->GetInterface ()))
@@ -798,27 +798,37 @@ Ipv6Address Ipv6StaticRouting::SourceAddressSelection (uint32_t interface, Ipv6A
   NS_LOG_FUNCTION (this << interface << dest);
   Ipv6Address ret;
 
-  /* first address of an IPv6 interface is link-local ones */
-  ret = m_ipv6->GetAddress (interface, 0).GetAddress ();
-
-  if (dest == Ipv6Address::GetAllNodesMulticast () || dest == Ipv6Address::GetAllRoutersMulticast () || dest == Ipv6Address::GetAllHostsMulticast ())
+  if (dest.IsLinkLocal () || dest.IsLinkLocalMulticast ())
     {
-      return ret;
+      for (uint32_t i = 0; i < m_ipv6->GetNAddresses (interface); i++)
+        {
+          Ipv6InterfaceAddress test = m_ipv6->GetAddress (interface, i);
+          if (test.GetScope () == Ipv6InterfaceAddress::LINKLOCAL)
+            {
+              return test.GetAddress ();
+            }
+        }
+      NS_ASSERT_MSG (false, "No link-local address found on interface " << interface);
     }
 
-  /* usually IPv6 interfaces have one link-local address and one global address */
-
-  for (uint32_t i = 1; i < m_ipv6->GetNAddresses (interface); i++)
+  for (uint32_t i = 0; i < m_ipv6->GetNAddresses (interface); i++)
     {
       Ipv6InterfaceAddress test = m_ipv6->GetAddress (interface, i);
-      Ipv6InterfaceAddress dst(dest);
 
-      if (test.GetScope() == dst.GetScope())
+      if (test.GetScope () == Ipv6InterfaceAddress::GLOBAL)
         {
-          return test.GetAddress ();
+          if (test.IsInSameSubnet (dest))
+            {
+              return test.GetAddress ();
+            }
+          else
+            {
+              ret = test.GetAddress ();
+            }
         }
     }
 
+  // no specific match found. Use a global address (any useful is fine).
   return ret;
 }