session: support local sessions and deprecate redirects

Memfd backed shared memory segments can only be negotiated over sockets.
For such scenarios, the existing redirect mechanism that establishes
cut-through sessions does not work anymore as the two peer application
do not share such a socket.

This patch adds support for local sessions, as opposed to sessions
backed by a transport connection, in a way that is almost transparent to
the two applications by reusing the existing binary api messages.
Moreover, all segment allocations are now entirely done through the
segment manager valloc, so segment overlaps due to independent
allocations previously required for redirects are completely avoided.
The one notable characteristic of local sessions (cut-through from app
perspective) notification messages is that they carry pointers to two
event queues, one for each app peer, instead of one. For
transport-backed sessions one of the queues can be inferred but for
local session they cannot.

Change-Id: Ia443fb63e2d9d8e43490275062a708f039038175
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 48 insertions, 10 deletions

diff --git a/src/vnet/session/session.h b/src/vnet/session/session.h
index ec00e291721..108e5fe259a 100644
--- a/src/vnet/session/session.h
+++ b/src/vnet/session/session.h
@@ -87,12 +87,14 @@ typedef struct
   void *arg;
 } rpc_args_t;
 
+typedef u64 session_handle_t;
+
 /* *INDENT-OFF* */
 typedef CLIB_PACKED (struct {
   union
     {
       svm_fifo_t * fifo;
-      u64 session_handle;
+      session_handle_t session_handle;
       rpc_args_t rpc_args;
     };
   u8 event_type;
@@ -251,38 +253,61 @@ session_get_if_valid (u64 si, u32 thread_index)
   return pool_elt_at_index (session_manager_main.sessions[thread_index], si);
 }
 
-always_inline u64
+always_inline session_handle_t
 session_handle (stream_session_t * s)
 {
   return ((u64) s->thread_index << 32) | (u64) s->session_index;
 }
 
 always_inline u32
-session_index_from_handle (u64 handle)
+session_index_from_handle (session_handle_t handle)
 {
   return handle & 0xFFFFFFFF;
 }
 
 always_inline u32
-session_thread_from_handle (u64 handle)
+session_thread_from_handle (session_handle_t handle)
 {
   return handle >> 32;
 }
 
 always_inline void
-session_parse_handle (u64 handle, u32 * index, u32 * thread_index)
+session_parse_handle (session_handle_t handle, u32 * index,
+		      u32 * thread_index)
 {
   *index = session_index_from_handle (handle);
   *thread_index = session_thread_from_handle (handle);
 }
 
 always_inline stream_session_t *
-session_get_from_handle (u64 handle)
+session_get_from_handle (session_handle_t handle)
 {
   session_manager_main_t *smm = &session_manager_main;
-  return
-    pool_elt_at_index (smm->sessions[session_thread_from_handle (handle)],
-		       session_index_from_handle (handle));
+  u32 session_index, thread_index;
+  session_parse_handle (handle, &session_index, &thread_index);
+  return pool_elt_at_index (smm->sessions[thread_index], session_index);
+}
+
+always_inline stream_session_t *
+session_get_from_handle_if_valid (session_handle_t handle)
+{
+  u32 session_index, thread_index;
+  session_parse_handle (handle, &session_index, &thread_index);
+  return session_get_if_valid (session_index, thread_index);
+}
+
+always_inline u8
+session_handle_is_local (session_handle_t handle)
+{
+  if ((handle >> 32) == SESSION_LOCAL_TABLE_PREFIX)
+    return 1;
+  return 0;
+}
+
+always_inline transport_proto_t
+session_type_transport_proto (session_type_t st)
+{
+  return (st >> 1);
 }
 
 always_inline transport_proto_t
@@ -291,12 +316,25 @@ session_get_transport_proto (stream_session_t * s)
   return (s->session_type >> 1);
 }
 
+always_inline fib_protocol_t
+session_get_fib_proto (stream_session_t * s)
+{
+  u8 is_ip4 = s->session_type & 1;
+  return (is_ip4 ? FIB_PROTOCOL_IP4 : FIB_PROTOCOL_IP6);
+}
+
 always_inline session_type_t
 session_type_from_proto_and_ip (transport_proto_t proto, u8 is_ip4)
 {
   return (proto << 1 | is_ip4);
 }
 
+always_inline u8
+session_has_transport (stream_session_t * s)
+{
+  return (session_get_transport_proto (s) != TRANSPORT_PROTO_NONE);
+}
+
 /**
  * Acquires a lock that blocks a session pool from expanding.
  *
@@ -470,7 +508,7 @@ listen_session_get_handle (stream_session_t * s)
 }
 
 always_inline stream_session_t *
-listen_session_get_from_handle (u64 handle)
+listen_session_get_from_handle (session_handle_t handle)
 {
   session_manager_main_t *smm = &session_manager_main;
   stream_session_t *s;