Attached hosts

allow this config to function:
  set int ip address loop0 169.254.1.1/32  (the default GW address for attached hosts)
  set int unnumbered af_packet0 use loop0  ('enable' IP on the host interface)
  ip route add 192.168.1.1/32 via af_packet0 (where to find the host)
repeat for each host and host interface.
Inter-host communication is throught the /32 routes.
To allow this:
 1 - attached host routes have the ATTACHED flag set, so the ARP code accepts then as legitimate sources
 2 - unnumbered interfaces inherit the source address from the IP interface

Change-Id: Ib66c5f0e848c528f79372813adc3a0c11b50717f
Signed-off-by: Neale Ranns <nranns@cisco.com>

5 files changed, 22 insertions, 0 deletions

diff --git a/src/vnet/fib/fib_entry_src.c b/src/vnet/fib/fib_entry_src.c
index feb232df7f1..aa1d5a24a0f 100644
--- a/src/vnet/fib/fib_entry_src.c
+++ b/src/vnet/fib/fib_entry_src.c
@@ -946,6 +946,10 @@ fib_path_is_attached (const fib_route_path_t *rpath)
     {
 	return (!0);
     }
+    else if (rpath->frp_flags & FIB_ROUTE_PATH_ATTACHED)
+    {
+        return (!0);
+    }
     return (0);
 }
 
diff --git a/src/vnet/fib/fib_path.c b/src/vnet/fib/fib_path.c
index aa545b5ed45..3ed309f328b 100644
--- a/src/vnet/fib/fib_path.c
+++ b/src/vnet/fib/fib_path.c
@@ -110,6 +110,10 @@ typedef enum fib_path_oper_attribute_t_ {
      */
     FIB_PATH_OPER_ATTRIBUTE_RESOLVED,
     /**
+     * The path is attached, despite what the next-hop may say.
+     */
+    FIB_PATH_OPER_ATTRIBUTE_ATTACHED,
+    /**
      * The path has become a permanent drop.
      */
     FIB_PATH_OPER_ATTRIBUTE_DROP,
@@ -143,6 +147,7 @@ typedef enum fib_path_oper_flags_t_ {
     FIB_PATH_OPER_FLAG_RECURSIVE_LOOP = (1 << FIB_PATH_OPER_ATTRIBUTE_RECURSIVE_LOOP),
     FIB_PATH_OPER_FLAG_DROP = (1 << FIB_PATH_OPER_ATTRIBUTE_DROP),
     FIB_PATH_OPER_FLAG_RESOLVED = (1 << FIB_PATH_OPER_ATTRIBUTE_RESOLVED),
+    FIB_PATH_OPER_FLAG_ATTACHED = (1 << FIB_PATH_OPER_ATTRIBUTE_ATTACHED),
 } __attribute__ ((packed)) fib_path_oper_flags_t;
 
 /**
@@ -963,6 +968,8 @@ fib_path_route_flags_to_cfg_flags (const fib_route_path_t *rpath)
 	cfg_flags |= FIB_PATH_CFG_FLAG_RESOLVE_ATTACHED;
     if (rpath->frp_flags & FIB_ROUTE_PATH_LOCAL)
 	cfg_flags |= FIB_PATH_CFG_FLAG_LOCAL;
+    if (rpath->frp_flags & FIB_ROUTE_PATH_ATTACHED)
+	cfg_flags |= FIB_PATH_CFG_FLAG_ATTACHED;
 
     return (cfg_flags);
 }
diff --git a/src/vnet/fib/fib_path.h b/src/vnet/fib/fib_path.h
index 91f49d09234..14efc1ab842 100644
--- a/src/vnet/fib/fib_path.h
+++ b/src/vnet/fib/fib_path.h
@@ -63,6 +63,10 @@ typedef enum fib_path_cfg_attribute_t_ {
      */
     FIB_PATH_CFG_ATTRIBUTE_RESOLVE_ATTACHED,
     /**
+     * The path is attached
+     */
+    FIB_PATH_CFG_ATTRIBUTE_ATTACHED,
+    /**
      * The path is a for-us path
      */
     FIB_PATH_CFG_ATTRIBUTE_LOCAL,
@@ -83,6 +87,7 @@ typedef enum fib_path_cfg_attribute_t_ {
     [FIB_PATH_CFG_ATTRIBUTE_RESOLVE_HOST] = "resolve-host", \
     [FIB_PATH_CFG_ATTRIBUTE_RESOLVE_ATTACHED] = "resolve-attached", \
     [FIB_PATH_CFG_ATTRIBUTE_LOCAL] = "local",	        \
+    [FIB_PATH_CFG_ATTRIBUTE_ATTACHED] = "attached",	\
 }
 
 #define FOR_EACH_FIB_PATH_CFG_ATTRIBUTE(_item) \
@@ -100,6 +105,7 @@ typedef enum fib_path_cfg_flags_t_ {
     FIB_PATH_CFG_FLAG_RESOLVE_HOST = (1 << FIB_PATH_CFG_ATTRIBUTE_RESOLVE_HOST),
     FIB_PATH_CFG_FLAG_RESOLVE_ATTACHED = (1 << FIB_PATH_CFG_ATTRIBUTE_RESOLVE_ATTACHED),
     FIB_PATH_CFG_FLAG_LOCAL = (1 << FIB_PATH_CFG_ATTRIBUTE_LOCAL),
+    FIB_PATH_CFG_FLAG_ATTACHED = (1 << FIB_PATH_CFG_ATTRIBUTE_ATTACHED),
 } __attribute__ ((packed)) fib_path_cfg_flags_t;
 
 
diff --git a/src/vnet/fib/fib_table.c b/src/vnet/fib/fib_table.c
index a0ce0bbb4de..7818d02e05d 100644
--- a/src/vnet/fib/fib_table.c
+++ b/src/vnet/fib/fib_table.c
@@ -480,6 +480,7 @@ fib_table_route_path_fixup (const fib_prefix_t *prefix,
 	path->frp_sw_if_index != ~0)
     {
 	path->frp_addr = prefix->fp_addr;
+        path->frp_flags |= FIB_ROUTE_PATH_ATTACHED;
     }
 }		  
 
diff --git a/src/vnet/fib/fib_types.h b/src/vnet/fib/fib_types.h
index 05e0e0af4c9..1c5299a9214 100644
--- a/src/vnet/fib/fib_types.h
+++ b/src/vnet/fib/fib_types.h
@@ -282,6 +282,10 @@ typedef enum fib_route_path_flags_t_
      * A for-us/local path
      */
     FIB_ROUTE_PATH_LOCAL = (1 << 2),
+    /**
+     * Attached path
+     */
+    FIB_ROUTE_PATH_ATTACHED = (1 << 3),
 } fib_route_path_flags_t;
 
 /**