vapi: support api clients within vpp process

Add vapi_connect_from_vpp() and vapi_disconnect_from_vpp()
calls to allow API clients from within VPP process.

Add a new memclnt_create version that gives the user a
knob to enable or disable dead client scans (keepalive).

Type: feature
Signed-off-by: Ole Troan <ot@cisco.com>
Change-Id: Id0b7bb89308db3a3aed2d3fcbedf4e1282dcd03f
Signed-off-by: Ole Troan <ot@cisco.com>

9 files changed, 673 insertions, 58 deletions

diff --git a/src/plugins/unittest/CMakeLists.txt b/src/plugins/unittest/CMakeLists.txt
index 34e47fa24f4..faf55dfec2d 100644
--- a/src/plugins/unittest/CMakeLists.txt
+++ b/src/plugins/unittest/CMakeLists.txt
@@ -15,9 +15,10 @@ set(chacha20_poly1305)
 if (OPENSSL_VERSION VERSION_GREATER_EQUAL 1.1.0)
     set(chacha20_poly1305 crypto/chacha20_poly1305.c)
 endif()
-
+include_directories(${CMAKE_SOURCE_DIR}/vpp-api ${CMAKE_CURRENT_BINARY_DIR}/../../vpp-api)
 add_vpp_plugin(unittest
   SOURCES
+  api_test.c
   api_fuzz_test.c
   bier_test.c
   bihash_test.c
@@ -60,4 +61,5 @@ add_vpp_plugin(unittest
 
   COMPONENT
   vpp-plugin-devtools
+  LINK_LIBRARIES vapiclient
 )
diff --git a/src/plugins/unittest/api_test.c b/src/plugins/unittest/api_test.c
new file mode 100644
index 00000000000..4bed50c2969
--- /dev/null
+++ b/src/plugins/unittest/api_test.c
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright(c) 2022 Cisco Systems, Inc.
+ */
+
+#include <vnet/vnet.h>
+#include <vnet/plugin/plugin.h>
+
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+#include <vpp/app/version.h>
+#include <stdbool.h>
+#include <vapi/vapi.h>
+
+#include <vapi/memclnt.api.vapi.h>
+#include <vapi/vlib.api.vapi.h>
+#include <vapi/vpe.api.vapi.h>
+
+/*
+ * Example of how to call the VPP binary API from an internal API client.
+ * Using the VAPI C language binding.
+ */
+
+DEFINE_VAPI_MSG_IDS_VPE_API_JSON;
+
+/*
+ * Connect an VPP binary API client to VPP API
+ */
+static vapi_ctx_t
+connect_to_vpp (void)
+{
+  vapi_ctx_t ctx;
+  if (vapi_ctx_alloc (&ctx) != VAPI_OK)
+    {
+      clib_warning ("ctx_alloc failed");
+      return 0;
+    }
+  if (vapi_connect_from_vpp (ctx, "apifromplugin", 64, 32, VAPI_MODE_BLOCKING,
+			     true) != VAPI_OK)
+    {
+      clib_warning ("vapi_connect failed");
+      return 0;
+    }
+  return ctx;
+}
+
+/*
+ * Gets called when the show_version_reply message is received
+ */
+vapi_error_e
+show_version_cb (vapi_ctx_t ctx, void *caller_ctx, vapi_error_e rv,
+		 bool is_last, vapi_payload_show_version_reply *p)
+{
+  if (rv != VAPI_OK)
+    clib_warning ("Return value: %d", rv);
+  fformat (
+    stdout,
+    "show_version_reply: program: `%s', version: `%s', build directory: "
+    "`%s', build date: `%s'\n",
+    p->program, p->version, p->build_directory, p->build_date);
+  return VAPI_OK;
+}
+
+static void *
+api_show_version_blocking_fn (void *args)
+{
+  vapi_ctx_t ctx;
+
+  if ((ctx = connect_to_vpp ()) == 0)
+    return clib_error_return (0, "API connection failed");
+
+  int called;
+  vapi_msg_show_version *sv = vapi_alloc_show_version (ctx);
+  vapi_error_e vapi_rv = vapi_show_version (ctx, sv, show_version_cb, &called);
+  if (vapi_rv != VAPI_OK)
+    clib_warning ("call failed");
+
+  vapi_disconnect_from_vpp (ctx);
+  vapi_ctx_free (ctx);
+
+  return 0;
+}
+
+static clib_error_t *
+test_api_test_command_fn (vlib_main_t *vm, unformat_input_t *input,
+			  vlib_cli_command_t *cmd)
+{
+  /* Run call in a pthread */
+  pthread_t thread;
+  int rv = pthread_create (&thread, NULL, api_show_version_blocking_fn, 0);
+  if (rv)
+    {
+      return clib_error_return (0, "API call failed");
+    }
+  return 0;
+}
+
+VLIB_CLI_COMMAND (test_api_command, static) = {
+  .path = "test api internal",
+  .short_help = "test internal api client",
+  .function = test_api_test_command_fn,
+};
diff --git a/src/vlibapi/api_common.h b/src/vlibapi/api_common.h
index 4c48b003e1e..491ecb8eaef 100644
--- a/src/vlibapi/api_common.h
+++ b/src/vlibapi/api_common.h
@@ -75,6 +75,8 @@ typedef struct vl_api_registration_
   /* socket client only */
   u32 server_handle;		/**< Socket client only: server handle */
   u32 server_index;		/**< Socket client only: server index */
+
+  bool keepalive; /**< Dead client scan */
 } vl_api_registration_t;
 
 #define VL_API_INVALID_FI ((u32)~0)
diff --git a/src/vlibmemory/memclnt.api b/src/vlibmemory/memclnt.api
index bd999b51dd0..0532f1734bf 100644
--- a/src/vlibmemory/memclnt.api
+++ b/src/vlibmemory/memclnt.api
@@ -232,3 +232,19 @@ define control_ping_reply
   u32 vpe_pid;
 };
 
+define memclnt_create_v2 {
+    u32 context;                /* opaque value to be returned in the reply */
+    i32 ctx_quota;              /* requested punt context quota */
+    u64 input_queue;            /* client's queue */
+    string name[64];            /* for show, find by name, whatever */
+    u32 api_versions[8];        /* client-server pairs use as desired */
+    bool keepalive[default=true];  /* dead client scan keepalives */
+};
+
+define memclnt_create_v2_reply {
+    u32 context;                /* opaque value from the create request */
+    i32 response;               /* Non-negative = success */
+    u64 handle;                 /* handle by which vlib knows this client */
+    u32 index;                  /* index, used e.g. by API trace replay */
+    u64 message_table;          /* serialized message table in shmem */
+};
diff --git a/src/vlibmemory/memory_api.c b/src/vlibmemory/memory_api.c
index a16110f2fa1..b1d250b8a5f 100644
--- a/src/vlibmemory/memory_api.c
+++ b/src/vlibmemory/memory_api.c
@@ -192,6 +192,7 @@ vl_api_memclnt_create_t_handler (vl_api_memclnt_create_t * mp)
 
   regp->name = format (0, "%s", mp->name);
   vec_add1 (regp->name, 0);
+  regp->keepalive = true;
 
   if (am->serialized_message_table_in_shmem == 0)
     am->serialized_message_table_in_shmem =
@@ -218,6 +219,87 @@ vl_api_memclnt_create_t_handler (vl_api_memclnt_create_t * mp)
 }
 
 void
+vl_api_memclnt_create_v2_t_handler (vl_api_memclnt_create_v2_t *mp)
+{
+  vl_api_registration_t **regpp;
+  vl_api_registration_t *regp;
+  vl_api_memclnt_create_v2_reply_t *rp;
+  svm_queue_t *q;
+  int rv = 0;
+  void *oldheap;
+  api_main_t *am = vlibapi_get_main ();
+  u8 *msg_table;
+
+  /*
+   * This is tortured. Maintain a vlib-address-space private
+   * pool of client registrations. We use the shared-memory virtual
+   * address of client structure as a handle, to allow direct
+   * manipulation of context quota vbls from the client library.
+   *
+   * This scheme causes trouble w/ API message trace replay, since
+   * some random VA from clib_mem_alloc() certainly won't
+   * occur in the Linux sim. The (very) few places
+   * that care need to use the pool index.
+   *
+   * Putting the registration object(s) into a pool in shared memory and
+   * using the pool index as a handle seems like a great idea.
+   * Unfortunately, each and every reference to that pool would need
+   * to be protected by a mutex:
+   *
+   *     Client                      VLIB
+   *     ------                      ----
+   *     convert pool index to
+   *     pointer.
+   *     <deschedule>
+   *                                 expand pool
+   *                                 <deschedule>
+   *     kaboom!
+   */
+
+  pool_get (am->vl_clients, regpp);
+
+  oldheap = vl_msg_push_heap ();
+  *regpp = clib_mem_alloc (sizeof (vl_api_registration_t));
+
+  regp = *regpp;
+  clib_memset (regp, 0, sizeof (*regp));
+  regp->registration_type = REGISTRATION_TYPE_SHMEM;
+  regp->vl_api_registration_pool_index = regpp - am->vl_clients;
+  regp->vlib_rp = am->vlib_rp;
+  regp->shmem_hdr = am->shmem_hdr;
+  regp->clib_file_index = am->shmem_hdr->clib_file_index;
+
+  q = regp->vl_input_queue = (svm_queue_t *) (uword) mp->input_queue;
+  VL_MSG_API_SVM_QUEUE_UNPOISON (q);
+
+  regp->name = format (0, "%s", mp->name);
+  vec_add1 (regp->name, 0);
+  regp->keepalive = mp->keepalive;
+
+  if (am->serialized_message_table_in_shmem == 0)
+    am->serialized_message_table_in_shmem =
+      vl_api_serialize_message_table (am, 0);
+
+  if (am->vlib_rp != am->vlib_primary_rp)
+    msg_table = vl_api_serialize_message_table (am, 0);
+  else
+    msg_table = am->serialized_message_table_in_shmem;
+
+  vl_msg_pop_heap (oldheap);
+
+  rp = vl_msg_api_alloc (sizeof (*rp));
+  rp->_vl_msg_id = ntohs (VL_API_MEMCLNT_CREATE_V2_REPLY);
+  rp->handle = (uword) regp;
+  rp->index = vl_msg_api_handle_from_index_and_epoch (
+    regp->vl_api_registration_pool_index, am->shmem_hdr->application_restarts);
+  rp->context = mp->context;
+  rp->response = ntohl (rv);
+  rp->message_table = pointer_to_uword (msg_table);
+
+  vl_msg_api_send_shmem (q, (u8 *) &rp);
+}
+
+void
 vl_api_call_reaper_functions (u32 client_index)
 {
   clib_error_t *error = 0;
@@ -399,6 +481,7 @@ vl_api_memclnt_keepalive_t_handler (vl_api_memclnt_keepalive_t * mp)
 
 #define foreach_vlib_api_msg                                                  \
   _ (MEMCLNT_CREATE, memclnt_create, 0)                                       \
+  _ (MEMCLNT_CREATE_V2, memclnt_create_v2, 0)                                 \
   _ (MEMCLNT_DELETE, memclnt_delete, 0)                                       \
   _ (MEMCLNT_KEEPALIVE, memclnt_keepalive, 0)                                 \
   _ (MEMCLNT_KEEPALIVE_REPLY, memclnt_keepalive_reply, 0)
@@ -578,8 +661,10 @@ vl_mem_api_dead_client_scan (api_main_t * am, vl_shmem_hdr_t * shm, f64 now)
 
   /* *INDENT-OFF* */
   pool_foreach (regpp, am->vl_clients)  {
+      if (!(*regpp)->keepalive)
+	continue;
       vl_mem_send_client_keepalive_w_reg (am, now, regpp, &dead_indices,
-                                          &confused_indices);
+					  &confused_indices);
   }
   /* *INDENT-ON* */
 
@@ -944,7 +1029,7 @@ vl_api_client_index_to_input_queue (u32 index)
 static clib_error_t *
 setup_memclnt_exit (vlib_main_t * vm)
 {
-  atexit (vl_unmap_shmem);
+  atexit (vl_unmap_shmem_client);
   return 0;
 }
 
diff --git a/src/vnet/interface_api.c b/src/vnet/interface_api.c
index 00a1ce3a599..29f98f7851f 100644
--- a/src/vnet/interface_api.c
+++ b/src/vnet/interface_api.c
@@ -1624,23 +1624,27 @@ interface_api_hookup (vlib_main_t * vm)
 {
   api_main_t *am = vlibapi_get_main ();
 
+  /*
+   * Set up the (msg_name, crc, message-id) table
+   */
+  REPLY_MSG_ID_BASE = setup_message_id_table ();
+
   /* Mark these APIs as mp safe */
-  am->is_mp_safe[VL_API_SW_INTERFACE_DUMP] = 1;
-  am->is_mp_safe[VL_API_SW_INTERFACE_DETAILS] = 1;
-  am->is_mp_safe[VL_API_SW_INTERFACE_TAG_ADD_DEL] = 1;
-  am->is_mp_safe[VL_API_SW_INTERFACE_SET_INTERFACE_NAME] = 1;
+  am->is_mp_safe[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_DUMP] = 1;
+  am->is_mp_safe[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_DETAILS] = 1;
+  am->is_mp_safe[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_TAG_ADD_DEL] = 1;
+  am->is_mp_safe[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_SET_INTERFACE_NAME] =
+    1;
 
   /* Do not replay VL_API_SW_INTERFACE_DUMP messages */
-  am->api_trace_cfg[VL_API_SW_INTERFACE_DUMP].replay_enable = 0;
+  am->api_trace_cfg[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_DUMP]
+    .replay_enable = 0;
 
   /* Mark these APIs as autoendian */
-  am->is_autoendian[VL_API_SW_INTERFACE_SET_TX_PLACEMENT] = 1;
-  am->is_autoendian[VL_API_SW_INTERFACE_TX_PLACEMENT_GET] = 1;
-
-  /*
-   * Set up the (msg_name, crc, message-id) table
-   */
-  REPLY_MSG_ID_BASE = setup_message_id_table ();
+  am->is_autoendian[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_SET_TX_PLACEMENT] =
+    1;
+  am->is_autoendian[REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_TX_PLACEMENT_GET] =
+    1;
 
   return 0;
 }
diff --git a/src/vpp-api/vapi/vapi.c b/src/vpp-api/vapi/vapi.c
index ca46f8d3b84..7808bec8521 100644
--- a/src/vpp-api/vapi/vapi.c
+++ b/src/vpp-api/vapi/vapi.c
@@ -30,10 +30,18 @@
 #include <vlib/vlib.h>
 #include <vlibapi/api_common.h>
 #include <vlibmemory/memory_client.h>
+#include <vlibmemory/memory_api.h>
+#include <vlibmemory/api.h>
 
 #include <vapi/memclnt.api.vapi.h>
 #include <vapi/vlib.api.vapi.h>
 
+#include <vlibmemory/vl_memory_msg_enum.h>
+
+#define vl_typedefs /* define message structures */
+#include <vlibmemory/vl_memory_api_h.h>
+#undef vl_typedefs
+
 /* we need to use control pings for some stuff and because we're forced to put
  * the code in headers, we need a way to be able to grab the ids of these
  * messages - so declare them here as extern */
@@ -89,6 +97,11 @@ struct vapi_ctx_s
   bool connected;
   bool handle_keepalives;
   pthread_mutex_t requests_mutex;
+
+  svm_queue_t *vl_input_queue;
+  u32 my_client_index;
+  /** client message index hash table */
+  uword *msg_index_by_name_and_crc;
 };
 
 u32
@@ -221,7 +234,7 @@ vapi_msg_alloc (vapi_ctx_t ctx, size_t size)
     {
       return NULL;
     }
-  void *rv = vl_msg_api_alloc_or_null (size);
+  void *rv = vl_msg_api_alloc_as_if_client_or_null (size);
   if (rv)
     {
       clib_memset (rv, 0, size);
@@ -302,13 +315,174 @@ vapi_is_msg_available (vapi_ctx_t ctx, vapi_msg_id_t id)
   return vapi_lookup_vl_msg_id (ctx, id) != UINT16_MAX;
 }
 
+/* Cut and paste to avoid adding dependency to client library */
+__clib_nosanitize_addr static void
+VL_API_VEC_UNPOISON (const void *v)
+{
+  const vec_header_t *vh = &((vec_header_t *) v)[-1];
+  clib_mem_unpoison (vh, sizeof (*vh) + vec_len (v));
+}
+
+static void
+vapi_api_name_and_crc_free (vapi_ctx_t ctx)
+{
+  int i;
+  u8 **keys = 0;
+  hash_pair_t *hp;
+
+  if (!ctx->msg_index_by_name_and_crc)
+    return;
+  hash_foreach_pair (hp, ctx->msg_index_by_name_and_crc,
+		     ({ vec_add1 (keys, (u8 *) hp->key); }));
+  for (i = 0; i < vec_len (keys); i++)
+    vec_free (keys[i]);
+  vec_free (keys);
+  hash_free (ctx->msg_index_by_name_and_crc);
+}
+
+static void
+vapi_memclnt_create_v2_reply_t_handler (vapi_ctx_t ctx,
+					vl_api_memclnt_create_v2_reply_t *mp)
+{
+  serialize_main_t _sm, *sm = &_sm;
+  u8 *tblv;
+  u32 nmsgs;
+  int i;
+  u8 *name_and_crc;
+  u32 msg_index;
+
+  ctx->my_client_index = mp->index;
+
+  /* Clean out any previous hash table (unlikely) */
+  vapi_api_name_and_crc_free (ctx);
+
+  ctx->msg_index_by_name_and_crc = hash_create_string (0, sizeof (uword));
+
+  /* Recreate the vnet-side API message handler table */
+  tblv = uword_to_pointer (mp->message_table, u8 *);
+  unserialize_open_data (sm, tblv, vec_len (tblv));
+  unserialize_integer (sm, &nmsgs, sizeof (u32));
+
+  VL_API_VEC_UNPOISON (tblv);
+
+  for (i = 0; i < nmsgs; i++)
+    {
+      msg_index = unserialize_likely_small_unsigned_integer (sm);
+      unserialize_cstring (sm, (char **) &name_and_crc);
+      hash_set_mem (ctx->msg_index_by_name_and_crc, name_and_crc, msg_index);
+    }
+}
+
+static void
+vapi_memclnt_delete_reply_t_handler (vapi_ctx_t ctx,
+				     vl_api_memclnt_delete_reply_t *mp)
+{
+  void *oldheap;
+  oldheap = vl_msg_push_heap ();
+  svm_queue_free (ctx->vl_input_queue);
+  vl_msg_pop_heap (oldheap);
+
+  ctx->my_client_index = ~0;
+  ctx->vl_input_queue = 0;
+}
+
+int
+vapi_client_connect (vapi_ctx_t ctx, const char *name, int ctx_quota,
+		     int input_queue_size, bool keepalive)
+{
+  vl_api_memclnt_create_v2_t *mp;
+  vl_api_memclnt_create_v2_reply_t *rp;
+  svm_queue_t *vl_input_queue;
+  vl_shmem_hdr_t *shmem_hdr;
+  int rv = 0;
+  void *oldheap;
+  api_main_t *am = vlibapi_get_main ();
+
+  shmem_hdr = am->shmem_hdr;
+
+  if (shmem_hdr == 0 || shmem_hdr->vl_input_queue == 0)
+    {
+      clib_warning ("shmem_hdr / input queue NULL");
+      return -1;
+    }
+
+  clib_mem_unpoison (shmem_hdr, sizeof (*shmem_hdr));
+  VL_MSG_API_SVM_QUEUE_UNPOISON (shmem_hdr->vl_input_queue);
+
+  oldheap = vl_msg_push_heap ();
+  vl_input_queue =
+    svm_queue_alloc_and_init (input_queue_size, sizeof (uword), getpid ());
+  vl_msg_pop_heap (oldheap);
+
+  ctx->my_client_index = ~0;
+  ctx->vl_input_queue = vl_input_queue;
+
+  mp = vl_msg_api_alloc_as_if_client (sizeof (vl_api_memclnt_create_v2_t));
+  clib_memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id = ntohs (VL_API_MEMCLNT_CREATE_V2);
+  mp->ctx_quota = ctx_quota;
+  mp->input_queue = (uword) vl_input_queue;
+  strncpy ((char *) mp->name, name, sizeof (mp->name) - 1);
+  mp->keepalive = keepalive;
+
+  vl_msg_api_send_shmem (shmem_hdr->vl_input_queue, (u8 *) &mp);
+
+  while (1)
+    {
+      int qstatus;
+      struct timespec ts, tsrem;
+      int i;
+
+      /* Wait up to 10 seconds */
+      for (i = 0; i < 1000; i++)
+	{
+	  qstatus =
+	    svm_queue_sub (vl_input_queue, (u8 *) &rp, SVM_Q_NOWAIT, 0);
+	  if (qstatus == 0)
+	    goto read_one_msg;
+	  ts.tv_sec = 0;
+	  ts.tv_nsec = 10000 * 1000; /* 10 ms */
+	  while (nanosleep (&ts, &tsrem) < 0)
+	    ts = tsrem;
+	}
+      /* Timeout... */
+      return -1;
+
+    read_one_msg:
+      VL_MSG_API_UNPOISON (rp);
+      if (ntohs (rp->_vl_msg_id) != VL_API_MEMCLNT_CREATE_V2_REPLY)
+	{
+	  clib_warning ("unexpected reply: id %d", ntohs (rp->_vl_msg_id));
+	  continue;
+	}
+      rv = clib_net_to_host_u32 (rp->response);
+      vapi_memclnt_create_v2_reply_t_handler (ctx, rp);
+      break;
+    }
+  return (rv);
+}
+
+u32
+vapi_api_get_msg_index (vapi_ctx_t ctx, u8 *name_and_crc)
+{
+  uword *p;
+
+  if (ctx->msg_index_by_name_and_crc)
+    {
+      p = hash_get_mem (ctx->msg_index_by_name_and_crc, name_and_crc);
+      if (p)
+	return p[0];
+    }
+  return ~0;
+}
+
 vapi_error_e
-vapi_connect (vapi_ctx_t ctx, const char *name,
-	      const char *chroot_prefix,
-	      int max_outstanding_requests,
-	      int response_queue_size, vapi_mode_e mode,
-	      bool handle_keepalives)
+vapi_connect (vapi_ctx_t ctx, const char *name, const char *chroot_prefix,
+	      int max_outstanding_requests, int response_queue_size,
+	      vapi_mode_e mode, bool handle_keepalives)
 {
+  int rv;
+
   if (response_queue_size <= 0 || max_outstanding_requests <= 0)
     {
       return VAPI_EINVAL;
@@ -317,6 +491,7 @@ vapi_connect (vapi_ctx_t ctx, const char *name,
     {
       return VAPI_ENOMEM;
     }
+
   ctx->requests_size = max_outstanding_requests;
   const size_t size = ctx->requests_size * sizeof (*ctx->requests);
   void *tmp = realloc (ctx->requests, size);
@@ -328,6 +503,7 @@ vapi_connect (vapi_ctx_t ctx, const char *name,
   clib_memset (ctx->requests, 0, size);
   /* coverity[MISSING_LOCK] - 177211 requests_mutex is not needed here */
   ctx->requests_start = ctx->requests_count = 0;
+
   if (chroot_prefix)
     {
       VAPI_DBG ("set memory root path `%s'", chroot_prefix);
@@ -335,12 +511,13 @@ vapi_connect (vapi_ctx_t ctx, const char *name,
     }
   static char api_map[] = "/vpe-api";
   VAPI_DBG ("client api map `%s'", api_map);
-  if ((vl_client_api_map (api_map)) < 0)
+  if ((rv = vl_map_shmem (api_map, 0 /* is_vlib */)) < 0)
     {
       return VAPI_EMAP_FAIL;
     }
   VAPI_DBG ("connect client `%s'", name);
-  if (vl_client_connect ((char *) name, 0, response_queue_size) < 0)
+  if (vapi_client_connect (ctx, (char *) name, 0, response_queue_size, true) <
+      0)
     {
       vl_client_api_unmap ();
       return VAPI_ECON_FAIL;
@@ -348,14 +525,15 @@ vapi_connect (vapi_ctx_t ctx, const char *name,
 #if VAPI_DEBUG_CONNECT
   VAPI_DBG ("start probing messages");
 #endif
-  int rv;
+
   int i;
   for (i = 0; i < __vapi_metadata.count; ++i)
     {
       vapi_message_desc_t *m = __vapi_metadata.msgs[i];
       u8 scratch[m->name_with_crc_len + 1];
       memcpy (scratch, m->name_with_crc, m->name_with_crc_len + 1);
-      u32 id = vl_msg_api_get_msg_index (scratch);
+      u32 id = vapi_api_get_msg_index (ctx, scratch);
+
       if (VAPI_INVALID_MSG_ID != id)
 	{
 	  if (id > UINT16_MAX)
@@ -367,10 +545,9 @@ vapi_connect (vapi_ctx_t ctx, const char *name,
 	    }
 	  if (id > ctx->vl_msg_id_max)
 	    {
-	      vapi_msg_id_t *tmp = realloc (ctx->vl_msg_id_to_vapi_msg_t,
-					    sizeof
-					    (*ctx->vl_msg_id_to_vapi_msg_t) *
-					    (id + 1));
+	      vapi_msg_id_t *tmp =
+		realloc (ctx->vl_msg_id_to_vapi_msg_t,
+			 sizeof (*ctx->vl_msg_id_to_vapi_msg_t) * (id + 1));
 	      if (!tmp)
 		{
 		  rv = VAPI_ENOMEM;
@@ -398,8 +575,8 @@ vapi_connect (vapi_ctx_t ctx, const char *name,
   if (!vapi_is_msg_available (ctx, vapi_msg_id_control_ping) ||
       !vapi_is_msg_available (ctx, vapi_msg_id_control_ping_reply))
     {
-      VAPI_ERR
-	("control ping or control ping reply not available, cannot connect");
+      VAPI_ERR (
+	"control ping or control ping reply not available, cannot connect");
       rv = VAPI_EINCOMPATIBLE;
       goto fail;
     }
@@ -420,6 +597,157 @@ fail:
   return rv;
 }
 
+/*
+ * API client running in the same process as VPP
+ */
+vapi_error_e
+vapi_connect_from_vpp (vapi_ctx_t ctx, const char *name,
+		       int max_outstanding_requests, int response_queue_size,
+		       vapi_mode_e mode, bool handle_keepalives)
+{
+  int rv;
+
+  if (response_queue_size <= 0 || max_outstanding_requests <= 0)
+    {
+      return VAPI_EINVAL;
+    }
+
+  ctx->requests_size = max_outstanding_requests;
+  const size_t size = ctx->requests_size * sizeof (*ctx->requests);
+  void *tmp = realloc (ctx->requests, size);
+  if (!tmp)
+    {
+      return VAPI_ENOMEM;
+    }
+  ctx->requests = tmp;
+  clib_memset (ctx->requests, 0, size);
+  /* coverity[MISSING_LOCK] - 177211 requests_mutex is not needed here */
+  ctx->requests_start = ctx->requests_count = 0;
+
+  VAPI_DBG ("connect client `%s'", name);
+  if (vapi_client_connect (ctx, (char *) name, 0, response_queue_size,
+			   handle_keepalives) < 0)
+    {
+      return VAPI_ECON_FAIL;
+    }
+
+  int i;
+  for (i = 0; i < __vapi_metadata.count; ++i)
+    {
+      vapi_message_desc_t *m = __vapi_metadata.msgs[i];
+      u8 scratch[m->name_with_crc_len + 1];
+      memcpy (scratch, m->name_with_crc, m->name_with_crc_len + 1);
+      u32 id = vapi_api_get_msg_index (ctx, scratch);
+      if (VAPI_INVALID_MSG_ID != id)
+	{
+	  if (id > UINT16_MAX)
+	    {
+	      VAPI_ERR ("Returned vl_msg_id `%u' > UINT16MAX `%u'!", id,
+			UINT16_MAX);
+	      rv = VAPI_EINVAL;
+	      goto fail;
+	    }
+	  if (id > ctx->vl_msg_id_max)
+	    {
+	      vapi_msg_id_t *tmp =
+		realloc (ctx->vl_msg_id_to_vapi_msg_t,
+			 sizeof (*ctx->vl_msg_id_to_vapi_msg_t) * (id + 1));
+	      if (!tmp)
+		{
+		  rv = VAPI_ENOMEM;
+		  goto fail;
+		}
+	      ctx->vl_msg_id_to_vapi_msg_t = tmp;
+	      ctx->vl_msg_id_max = id;
+	    }
+	  ctx->vl_msg_id_to_vapi_msg_t[id] = m->id;
+	  ctx->vapi_msg_id_t_to_vl_msg_id[m->id] = id;
+	}
+      else
+	{
+	  ctx->vapi_msg_id_t_to_vl_msg_id[m->id] = UINT16_MAX;
+	  VAPI_DBG ("Message `%s' not available", m->name_with_crc);
+	}
+    }
+  if (!vapi_is_msg_available (ctx, vapi_msg_id_control_ping) ||
+      !vapi_is_msg_available (ctx, vapi_msg_id_control_ping_reply))
+    {
+      VAPI_ERR (
+	"control ping or control ping reply not available, cannot connect");
+      rv = VAPI_EINCOMPATIBLE;
+      goto fail;
+    }
+  ctx->mode = mode;
+  ctx->connected = true;
+  if (vapi_is_msg_available (ctx, vapi_msg_id_memclnt_keepalive))
+    {
+      ctx->handle_keepalives = handle_keepalives;
+    }
+  else
+    {
+      ctx->handle_keepalives = false;
+    }
+  return VAPI_OK;
+fail:
+  vl_client_disconnect ();
+  return rv;
+}
+
+vapi_error_e
+vapi_disconnect_from_vpp (vapi_ctx_t ctx)
+{
+  if (!ctx->connected)
+    {
+      return VAPI_EINVAL;
+    }
+  vl_api_memclnt_delete_reply_t *rp;
+  svm_queue_t *vl_input_queue;
+  time_t begin;
+  vl_input_queue = ctx->vl_input_queue;
+  vl_client_send_disconnect (0 /* wait for reply */);
+
+  /*
+   * Have to be careful here, in case the client is disconnecting
+   * because e.g. the vlib process died, or is unresponsive.
+   */
+  begin = time (0);
+  vapi_error_e rv = VAPI_OK;
+  while (1)
+    {
+      time_t now;
+
+      now = time (0);
+
+      if (now >= (begin + 2))
+	{
+	  clib_warning ("peer unresponsive, give up");
+	  ctx->my_client_index = ~0;
+	  rv = VAPI_ENORESP;
+	  goto fail;
+	}
+      if (svm_queue_sub (vl_input_queue, (u8 *) &rp, SVM_Q_NOWAIT, 0) < 0)
+	continue;
+
+      VL_MSG_API_UNPOISON (rp);
+
+      /* drain the queue */
+      if (ntohs (rp->_vl_msg_id) != VL_API_MEMCLNT_DELETE_REPLY)
+	{
+	  clib_warning ("queue drain: %d", ntohs (rp->_vl_msg_id));
+	  vl_msg_api_free (rp);
+	  continue;
+	}
+      vapi_memclnt_delete_reply_t_handler (
+	ctx, (void *) rp /*, ntohl (msgbuf->data_len)*/);
+      break;
+    }
+fail:
+  vapi_api_name_and_crc_free (ctx);
+
+  ctx->connected = false;
+  return rv;
+}
+
 vapi_error_e
 vapi_disconnect (vapi_ctx_t ctx)
 {
@@ -427,13 +755,57 @@ vapi_disconnect (vapi_ctx_t ctx)
     {
       return VAPI_EINVAL;
     }
-  vl_client_disconnect ();
+
+  vl_api_memclnt_delete_reply_t *rp;
+  svm_queue_t *vl_input_queue;
+  time_t begin;
+  vl_input_queue = ctx->vl_input_queue;
+  vl_client_send_disconnect (0 /* wait for reply */);
+
+  /*
+   * Have to be careful here, in case the client is disconnecting
+   * because e.g. the vlib process died, or is unresponsive.
+   */
+  begin = time (0);
+  vapi_error_e rv = VAPI_OK;
+  while (1)
+    {
+      time_t now;
+
+      now = time (0);
+
+      if (now >= (begin + 2))
+	{
+	  clib_warning ("peer unresponsive, give up");
+	  ctx->my_client_index = ~0;
+	  rv = VAPI_ENORESP;
+	  goto fail;
+	}
+      if (svm_queue_sub (vl_input_queue, (u8 *) &rp, SVM_Q_NOWAIT, 0) < 0)
+	continue;
+
+      VL_MSG_API_UNPOISON (rp);
+
+      /* drain the queue */
+      if (ntohs (rp->_vl_msg_id) != VL_API_MEMCLNT_DELETE_REPLY)
+	{
+	  clib_warning ("queue drain: %d", ntohs (rp->_vl_msg_id));
+	  vl_msg_api_free (rp);
+	  continue;
+	}
+      vapi_memclnt_delete_reply_t_handler (
+	ctx, (void *) rp /*, ntohl (msgbuf->data_len)*/);
+      break;
+    }
+fail:
+  vapi_api_name_and_crc_free (ctx);
+
   vl_client_api_unmap ();
 #if VAPI_DEBUG_ALLOC
   vapi_to_be_freed_validate ();
 #endif
   ctx->connected = false;
-  return VAPI_OK;
+  return rv;
 }
 
 vapi_error_e
@@ -541,15 +913,10 @@ vapi_recv (vapi_ctx_t ctx, void **msg, size_t * msg_size,
       return VAPI_EINVAL;
     }
   vapi_error_e rv = VAPI_OK;
-  api_main_t *am = vlibapi_get_main ();
   uword data;
 
-  if (am->our_pid == 0)
-    {
-      return VAPI_EINVAL;
-    }
+  svm_queue_t *q = ctx->vl_input_queue;
 
-  svm_queue_t *q = am->vl_input_queue;
 again:
   VAPI_DBG ("doing shm queue sub");
 
@@ -610,7 +977,6 @@ again:
 	      vapi_msg_memclnt_keepalive_reply_hton (reply);
 	      while (VAPI_EAGAIN == vapi_send (ctx, reply));
 	      vapi_msg_free (ctx, *msg);
-	      VAPI_DBG ("autohandled memclnt_keepalive");
 	      goto again;
 	    }
 	}
@@ -689,9 +1055,8 @@ vapi_dispatch_response (vapi_ctx_t ctx, vapi_msg_id_t id,
 	}
       if (payload_offset != -1)
 	{
-	  rv =
-	    ctx->requests[tmp].callback (ctx, ctx->requests[tmp].callback_ctx,
-					 VAPI_OK, is_last, payload);
+	  rv = ctx->requests[tmp].callback (
+	    ctx, ctx->requests[tmp].callback_ctx, VAPI_OK, is_last, payload);
 	}
       else
 	{
@@ -870,7 +1235,7 @@ vapi_lookup_vl_msg_id (vapi_ctx_t ctx, vapi_msg_id_t id)
 int
 vapi_get_client_index (vapi_ctx_t ctx)
 {
-  return vlibapi_get_main ()->my_client_index;
+  return ctx->my_client_index;
 }
 
 bool
diff --git a/src/vpp-api/vapi/vapi.h b/src/vpp-api/vapi/vapi.h
index 08d016b0dd7..46666293e4b 100644
--- a/src/vpp-api/vapi/vapi.h
+++ b/src/vpp-api/vapi/vapi.h
@@ -44,7 +44,7 @@ extern "C"
  * process). It's not recommended to mix the higher and lower level APIs. Due
  * to version issues, the higher-level APIs are not part of the shared library.
  */
-  typedef struct vapi_ctx_s *vapi_ctx_t;
+typedef struct vapi_ctx_s *vapi_ctx_t;
 
 /**
  * @brief allocate vapi message of given size
@@ -56,7 +56,7 @@ extern "C"
  *
  * @return pointer to message or NULL if out of memory
  */
-  void *vapi_msg_alloc (vapi_ctx_t ctx, size_t size);
+void *vapi_msg_alloc (vapi_ctx_t ctx, size_t size);
 
 /**
  * @brief free a vapi message
@@ -66,7 +66,7 @@ extern "C"
  * @param ctx opaque vapi context
  * @param msg message to be freed
  */
-  void vapi_msg_free (vapi_ctx_t ctx, void *msg);
+void vapi_msg_free (vapi_ctx_t ctx, void *msg);
 
 /**
  * @brief allocate vapi context
@@ -75,18 +75,18 @@ extern "C"
  *
  * @return VAPI_OK on success, other error code on error
  */
-  vapi_error_e vapi_ctx_alloc (vapi_ctx_t * result);
+vapi_error_e vapi_ctx_alloc (vapi_ctx_t *result);
 
 /**
  * @brief free vapi context
  */
-  void vapi_ctx_free (vapi_ctx_t ctx);
+void vapi_ctx_free (vapi_ctx_t ctx);
 
 /**
  * @brief check if message identified by it's message id is known by the vpp to
  * which the connection is open
  */
-  bool vapi_is_msg_available (vapi_ctx_t ctx, vapi_msg_id_t type);
+bool vapi_is_msg_available (vapi_ctx_t ctx, vapi_msg_id_t type);
 
 /**
  * @brief connect to vpp
@@ -101,11 +101,30 @@ extern "C"
  *
  * @return VAPI_OK on success, other error code on error
  */
-  vapi_error_e vapi_connect (vapi_ctx_t ctx, const char *name,
-			     const char *chroot_prefix,
-			     int max_outstanding_requests,
-			     int response_queue_size, vapi_mode_e mode,
-			     bool handle_keepalives);
+vapi_error_e vapi_connect (vapi_ctx_t ctx, const char *name,
+			   const char *chroot_prefix,
+			   int max_outstanding_requests,
+			   int response_queue_size, vapi_mode_e mode,
+			   bool handle_keepalives);
+
+/**
+ * @brief connect to vpp from a client in same process
+ * @remark This MUST be called from a separate thread. If called
+ *         from the main thread, it will deadlock.
+ *
+ * @param ctx opaque vapi context, must be allocated using vapi_ctx_alloc first
+ * @param name application name
+ * @param max_outstanding_requests max number of outstanding requests queued
+ * @param response_queue_size size of the response queue
+ * @param mode mode of operation - blocking or nonblocking
+ * @param handle_keepalives - if true, automatically handle memclnt_keepalive
+ *
+ * @return VAPI_OK on success, other error code on error
+ */
+vapi_error_e vapi_connect_from_vpp (vapi_ctx_t ctx, const char *name,
+				    int max_outstanding_requests,
+				    int response_queue_size, vapi_mode_e mode,
+				    bool handle_keepalives);
 
 /**
  * @brief disconnect from vpp
@@ -114,7 +133,8 @@ extern "C"
  *
  * @return VAPI_OK on success, other error code on error
  */
-  vapi_error_e vapi_disconnect (vapi_ctx_t ctx);
+vapi_error_e vapi_disconnect (vapi_ctx_t ctx);
+vapi_error_e vapi_disconnect_from_vpp (vapi_ctx_t ctx);
 
 /**
  * @brief get event file descriptor
@@ -127,7 +147,7 @@ extern "C"
  *
  * @return VAPI_OK on success, other error code on error
  */
-  vapi_error_e vapi_get_fd (vapi_ctx_t ctx, int *fd);
+vapi_error_e vapi_get_fd (vapi_ctx_t ctx, int *fd);
 
 /**
  * @brief low-level api for sending messages to vpp
@@ -140,7 +160,7 @@ extern "C"
  *
  * @return VAPI_OK on success, other error code on error
  */
-  vapi_error_e vapi_send (vapi_ctx_t ctx, void *msg);
+vapi_error_e vapi_send (vapi_ctx_t ctx, void *msg);
 
 /**
  * @brief low-level api for atomically sending two messages to vpp - either
diff --git a/test/test_api_client.py b/test/test_api_client.py
new file mode 100644
index 00000000000..ec44be7e370
--- /dev/null
+++ b/test/test_api_client.py
@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+import unittest
+
+from framework import VppTestCase, VppTestRunner
+from vpp_ip_route import VppIpTable, VppIpRoute, VppRoutePath
+
+
+class TestAPIClient(VppTestCase):
+    """ API Internal client Test Cases """
+
+    def test_client_unittest(self):
+        """ Internal API client """
+        error = self.vapi.cli("test api internal")
+        if error:
+            self.logger.critical(error)
+            self.assertNotIn('failed', error)
+
+if __name__ == '__main__':
+    unittest.main(testRunner=VppTestRunner)