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>

3 files changed, 19 insertions, 18 deletions

diff --git a/src/vnet/session-apps/echo_server.c b/src/vnet/session-apps/echo_server.c
index 024ffa66f96..0d0350819c9 100644
--- a/src/vnet/session-apps/echo_server.c
+++ b/src/vnet/session-apps/echo_server.c
@@ -245,7 +245,6 @@ static session_cb_vft_t echo_server_session_cb_vft = {
   .session_disconnect_callback = echo_server_session_disconnect_callback,
   .session_connected_callback = echo_server_session_connected_callback,
   .add_segment_callback = echo_server_add_segment_callback,
-  .redirect_connect_callback = echo_server_redirect_connect_callback,
   .builtin_server_rx_callback = echo_server_rx_callback,
   .session_reset_callback = echo_server_session_reset_callback
 };
@@ -387,7 +386,7 @@ echo_server_create_command_fn (vlib_main_t * vm, unformat_input_t * input,
   u8 server_uri_set = 0, *appns_id = 0;
   u64 tmp, appns_flags = 0, appns_secret = 0;
   char *default_uri = "tcp://0.0.0.0/1234";
-  int rv;
+  int rv, is_stop = 0;
 
   esm->no_echo = 0;
   esm->fifo_size = 64 << 10;
@@ -431,11 +430,29 @@ echo_server_create_command_fn (vlib_main_t * vm, unformat_input_t * input,
 	appns_flags |= APP_OPTIONS_FLAGS_USE_GLOBAL_SCOPE;
       else if (unformat (input, "secret %lu", &appns_secret))
 	;
+      else if (unformat (input, "stop"))
+	is_stop = 1;
       else
 	return clib_error_return (0, "failed: unknown input `%U'",
 				  format_unformat_error, input);
     }
 
+  if (is_stop)
+    {
+      if (esm->app_index == (u32) ~ 0)
+	{
+	  clib_warning ("server not running");
+	  return clib_error_return (0, "failed: server not running");
+	}
+      rv = echo_server_detach ();
+      if (rv)
+	{
+	  clib_warning ("failed: detach");
+	  return clib_error_return (0, "failed: server detach %d", rv);
+	}
+      return 0;
+    }
+
   vnet_session_enable_disable (vm, 1 /* turn on TCP, etc. */ );
 
   if (!server_uri_set)
diff --git a/src/vnet/session-apps/http_server.c b/src/vnet/session-apps/http_server.c
index 07eaab4c1ae..eeb755b0fc4 100644
--- a/src/vnet/session-apps/http_server.c
+++ b/src/vnet/session-apps/http_server.c
@@ -471,19 +471,11 @@ http_server_add_segment_callback (u32 client_index, const ssvm_private_t * sp)
   return -1;
 }
 
-static int
-http_server_redirect_connect_callback (u32 client_index, void *mp)
-{
-  clib_warning ("called...");
-  return -1;
-}
-
 static session_cb_vft_t http_server_session_cb_vft = {
   .session_accept_callback = http_server_session_accept_callback,
   .session_disconnect_callback = http_server_session_disconnect_callback,
   .session_connected_callback = http_server_session_connected_callback,
   .add_segment_callback = http_server_add_segment_callback,
-  .redirect_connect_callback = http_server_redirect_connect_callback,
   .builtin_server_rx_callback = http_server_rx_callback,
   .session_reset_callback = http_server_session_reset_callback
 };
diff --git a/src/vnet/session-apps/proxy.c b/src/vnet/session-apps/proxy.c
index 2fdb63f1780..1cbacdbc894 100644
--- a/src/vnet/session-apps/proxy.c
+++ b/src/vnet/session-apps/proxy.c
@@ -146,13 +146,6 @@ proxy_add_segment_callback (u32 client_index, const ssvm_private_t * sp)
 }
 
 static int
-proxy_redirect_connect_callback (u32 client_index, void *mp)
-{
-  clib_warning ("called...");
-  return -1;
-}
-
-static int
 proxy_rx_callback (stream_session_t * s)
 {
   u32 max_dequeue;
@@ -239,7 +232,6 @@ static session_cb_vft_t proxy_session_cb_vft = {
   .session_disconnect_callback = proxy_disconnect_callback,
   .session_connected_callback = proxy_connected_callback,
   .add_segment_callback = proxy_add_segment_callback,
-  .redirect_connect_callback = proxy_redirect_connect_callback,
   .builtin_server_rx_callback = proxy_rx_callback,
   .session_reset_callback = proxy_reset_callback
 };