Refactoring post process handling to gracefully handle user space int…

…erfaces

The problem corrected in the first commit was just one symptom of ungraceful handling of user space interfaces.
The real, and generic correction is delivered by this commit.
Post-processing in general is now skipped for links not managed by the kernel.
A warning message is also written when this happens, so post-mortem debugging for kernel managed links is still possible.

pkg/danmep/danmep.go

@@ -204,15 +204,20 @@ func PostProcessInterface(ep *danmtypes.DanmEp, dnet *danmtypes.DanmNet) error {
       return errors.New("failed to create dummy kernel interface for " + ep.Spec.Iface.Name + " because:" + err.Error())
     }
   }
+  link, err := netlink.LinkByName(ep.Spec.Iface.Name)
+  if err != nil {
+    log.Println("WARNING: Interface post-processing was skipped for Pod:" + ep.Spec.Pod + " and link:" + ep.Spec.Iface.Name + " because it does not exist in the kernel. If it is not a user space interface, you should investigate!!!")
+    return nil
+  }
   err = setDanmEpSysctls(ep)
   if err != nil {
     return errors.New("failed to set kernel configs for interface" + ep.Spec.Iface.Name + " because:" + err.Error())
   }
-  err = disableDadOnIface(ep, isVfAttachedToDpdkDriver)
+  err = disableDadOnIface(link, ep)
   if err != nil {
     return errors.New("failed to disable DAD for address" + ep.Spec.Iface.AddressIPv6 + " because:" + err.Error())
   }
-  return addIpRoutes(ep,dnet)
+  return addIpRoutes(link, ep, dnet)
 }
 
 func setDanmEpSysctls(ep *danmtypes.DanmEp) error {
@@ -232,16 +237,14 @@ func setDanmEpSysctls(ep *danmtypes.DanmEp) error {
 }
 
 func isIPv6Needed(ep *danmtypes.DanmEp) bool {
-  _, err := os.Stat(V6SysPath + ep.Spec.Iface.Name)
-  if err == nil && ep.Spec.Iface.AddressIPv6 != "" {
+  if ep.Spec.Iface.AddressIPv6 != "" {
     return true
   }
   return false
 }
 
 func isIPv6NotNeeded(ep *danmtypes.DanmEp) bool {
-  _, err := os.Stat(V6SysPath + ep.Spec.Iface.Name)
-  if err == nil && ep.Spec.Iface.AddressIPv6 == "" {
+  if ep.Spec.Iface.AddressIPv6 == "" {
     return true
   }
   return false

pkg/danmep/ep.go

@@ -144,13 +144,9 @@ func addIpToLink(ip string, iface netlink.Link) error {
   return nil
 }
 
-func addIpRoutes(ep *danmtypes.DanmEp, dnet *danmtypes.DanmNet) error {
+func addIpRoutes(link netlink.Link, ep *danmtypes.DanmEp, dnet *danmtypes.DanmNet) error {
   defaultRoutingTable := 0
-  link, err := netlink.LinkByName(ep.Spec.Iface.Name)
-  if err != nil {
-    return errors.New("cannot find Pod interface: " + ep.Spec.Iface.Name + " for adding IP route because:" + err.Error())
-  }
-  err = addRouteForLink(dnet.Spec.Options.Routes, ep.Spec.Iface.Address, defaultRoutingTable, link)
+  err := addRouteForLink(dnet.Spec.Options.Routes, ep.Spec.Iface.Address, defaultRoutingTable, link)
   if err != nil {
     return err
   }
@@ -341,14 +337,10 @@ func createDummyInterface(ep *danmtypes.DanmEp, dnet *danmtypes.DanmNet) error {
   return configureLink(iface, ep)
 }
 
-func disableDadOnIface(ep *danmtypes.DanmEp, isDummyIface bool) error {
-  if isDummyIface || ep.Spec.NetworkType == "ipvlan" || ep.Spec.Iface.AddressIPv6 == "" || ep.Spec.Iface.AddressIPv6 == ipam.NoneAllocType {
+func disableDadOnIface(link netlink.Link, ep *danmtypes.DanmEp) error {
+  if  ep.Spec.NetworkType == "ipvlan" || ep.Spec.Iface.AddressIPv6 == "" || ep.Spec.Iface.AddressIPv6 == ipam.NoneAllocType {
     return nil
   }
-  link, err := netlink.LinkByName(ep.Spec.Iface.Name)
-  if err != nil {
-    return errors.New("cannot find interface to disable DAD on its V6 address because:" + err.Error())
-  }
   addr, pref, _ := net.ParseCIDR(ep.Spec.Iface.AddressIPv6)
   dadlessAddress := &netlink.Addr{IPNet: &net.IPNet{IP: addr, Mask: pref.Mask}, Flags: syscall.IFA_F_NODAD,}
   return netlink.AddrReplace(link, dadlessAddress)