src/core/security/security_connector.c

/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "src/core/security/security_connector.h"

#include <string.h>

#include "src/core/security/credentials.h"
#include "src/core/security/handshake.h"
#include "src/core/security/secure_endpoint.h"
#include "src/core/security/security_context.h"
#include "src/core/support/env.h"
#include "src/core/support/file.h"
#include "src/core/support/string.h"
#include "src/core/transport/chttp2/alpn.h"

#include <grpc/support/alloc.h>
#include <grpc/support/host_port.h>
#include <grpc/support/log.h>
#include <grpc/support/slice_buffer.h>
#include <grpc/support/string_util.h>
#include "src/core/tsi/fake_transport_security.h"
#include "src/core/tsi/ssl_transport_security.h"

/* -- Constants. -- */

#ifndef INSTALL_PREFIX
static const char *installed_roots_path = "/usr/share/grpc/roots.pem";
#else
static const char *installed_roots_path = INSTALL_PREFIX "/share/grpc/roots.pem";
#endif

/* -- Cipher suites. -- */

/* Defines the cipher suites that we accept by default. All these cipher suites
   are compliant with HTTP2. */
#define GRPC_SSL_CIPHER_SUITES                                            \
  "ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-" \
  "SHA384:ECDHE-RSA-AES256-GCM-SHA384"

static gpr_once cipher_suites_once = GPR_ONCE_INIT;
static const char *cipher_suites = NULL;

static void
init_cipher_suites (void)
{
  char *overridden = gpr_getenv ("GRPC_SSL_CIPHER_SUITES");
  cipher_suites = overridden != NULL ? overridden : GRPC_SSL_CIPHER_SUITES;
}

static const char *
ssl_cipher_suites (void)
{
  gpr_once_init (&cipher_suites_once, init_cipher_suites);
  return cipher_suites;
}

/* -- Common methods. -- */

/* Returns the first property with that name. */
const tsi_peer_property *
tsi_peer_get_property_by_name (const tsi_peer * peer, const char *name)
{
  size_t i;
  if (peer == NULL)
    return NULL;
  for (i = 0; i < peer->property_count; i++)
    {
      const tsi_peer_property *property = &peer->properties[i];
      if (name == NULL && property->name == NULL)
	{
	  return property;
	}
      if (name != NULL && property->name != NULL && strcmp (property->name, name) == 0)
	{
	  return property;
	}
    }
  return NULL;
}

void
grpc_security_connector_do_handshake (grpc_exec_ctx * exec_ctx, grpc_security_connector * sc, grpc_endpoint * nonsecure_endpoint, grpc_security_handshake_done_cb cb, void *user_data)
{
  if (sc == NULL || nonsecure_endpoint == NULL)
    {
      cb (exec_ctx, user_data, GRPC_SECURITY_ERROR, nonsecure_endpoint, NULL);
    }
  else
    {
      sc->vtable->do_handshake (exec_ctx, sc, nonsecure_endpoint, cb, user_data);
    }
}

grpc_security_status
grpc_security_connector_check_peer (grpc_security_connector * sc, tsi_peer peer, grpc_security_check_cb cb, void *user_data)
{
  if (sc == NULL)
    {
      tsi_peer_destruct (&peer);
      return GRPC_SECURITY_ERROR;
    }
  return sc->vtable->check_peer (sc, peer, cb, user_data);
}

grpc_security_status
grpc_channel_security_connector_check_call_host (grpc_exec_ctx * exec_ctx, grpc_channel_security_connector * sc, const char *host, grpc_security_check_cb cb, void *user_data)
{
  if (sc == NULL || sc->check_call_host == NULL)
    return GRPC_SECURITY_ERROR;
  return sc->check_call_host (exec_ctx, sc, host, cb, user_data);
}

#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
grpc_security_connector *
grpc_security_connector_ref (grpc_security_connector * sc, const char *file, int line, const char *reason)
{
  if (sc == NULL)
    return NULL;
  gpr_log (file, line, GPR_LOG_SEVERITY_DEBUG, "SECURITY_CONNECTOR:%p   ref %d -> %d %s", sc, (int) sc->refcount.count, (int) sc->refcount.count + 1, reason);
#else
grpc_security_connector *
grpc_security_connector_ref (grpc_security_connector * sc)
{
  if (sc == NULL)
    return NULL;
#endif
  gpr_ref (&sc->refcount);
  return sc;
}

#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
void
grpc_security_connector_unref (grpc_security_connector * sc, const char *file, int line, const char *reason)
{
  if (sc == NULL)
    return;
  gpr_log (file, line, GPR_LOG_SEVERITY_DEBUG, "SECURITY_CONNECTOR:%p unref %d -> %d %s", sc, (int) sc->refcount.count, (int) sc->refcount.count - 1, reason);
#else
void
grpc_security_connector_unref (grpc_security_connector * sc)
{
  if (sc == NULL)
    return;
#endif
  if (gpr_unref (&sc->refcount))
    sc->vtable->destroy (sc);
}

static void
connector_pointer_arg_destroy (void *p)
{
  GRPC_SECURITY_CONNECTOR_UNREF (p, "connector_pointer_arg");
}

static void *
connector_pointer_arg_copy (void *p)
{
  return GRPC_SECURITY_CONNECTOR_REF (p, "connector_pointer_arg");
}

grpc_arg
grpc_security_connector_to_arg (grpc_security_connector * sc)
{
  grpc_arg result;
  result.type = GRPC_ARG_POINTER;
  result.key = GRPC_SECURITY_CONNECTOR_ARG;
  result.value.pointer.destroy = connector_pointer_arg_destroy;
  result.value.pointer.copy = connector_pointer_arg_copy;
  result.value.pointer.p = sc;
  return result;
}

grpc_security_connector *
grpc_security_connector_from_arg (const grpc_arg * arg)
{
  if (strcmp (arg->key, GRPC_SECURITY_CONNECTOR_ARG))
    return NULL;
  if (arg->type != GRPC_ARG_POINTER)
    {
      gpr_log (GPR_ERROR, "Invalid type %d for arg %s", arg->type, GRPC_SECURITY_CONNECTOR_ARG);
      return NULL;
    }
  return arg->value.pointer.p;
}

grpc_security_connector *
grpc_find_security_connector_in_args (const grpc_channel_args * args)
{
  size_t i;
  if (args == NULL)
    return NULL;
  for (i = 0; i < args->num_args; i++)
    {
      grpc_security_connector *sc = grpc_security_connector_from_arg (&args->args[i]);
      if (sc != NULL)
	return sc;
    }
  return NULL;
}

static int
check_request_metadata_creds (grpc_credentials * creds)
{
  if (creds != NULL && !grpc_credentials_has_request_metadata (creds))
    {
      gpr_log (GPR_ERROR, "Incompatible credentials for channel security connector: needs to " "set request metadata.");
      return 0;
    }
  return 1;
}

/* -- Fake implementation. -- */

typedef struct
{
  grpc_channel_security_connector base;
  int call_host_check_is_async;
} grpc_fake_channel_security_connector;

static void
fake_channel_destroy (grpc_security_connector * sc)
{
  grpc_channel_security_connector *c = (grpc_channel_security_connector *) sc;
  grpc_credentials_unref (c->request_metadata_creds);
  GRPC_AUTH_CONTEXT_UNREF (sc->auth_context, "connector");
  gpr_free (sc);
}

static void
fake_server_destroy (grpc_security_connector * sc)
{
  GRPC_AUTH_CONTEXT_UNREF (sc->auth_context, "connector");
  gpr_free (sc);
}

static grpc_security_status
fake_check_peer (grpc_security_connector * sc, tsi_peer peer, grpc_security_check_cb cb, void *user_data)
{
  const char *prop_name;
  grpc_security_status status = GRPC_SECURITY_OK;
  if (peer.property_count != 1)
    {
      gpr_log (GPR_ERROR, "Fake peers should only have 1 property.");
      status = GRPC_SECURITY_ERROR;
      goto end;
    }
  prop_name = peer.properties[0].name;
  if (prop_name == NULL || strcmp (prop_name, TSI_CERTIFICATE_TYPE_PEER_PROPERTY))
    {
      gpr_log (GPR_ERROR, "Unexpected property in fake peer: %s.", prop_name == NULL ? "<EMPTY>" : prop_name);
      status = GRPC_SECURITY_ERROR;
      goto end;
    }
  if (strncmp (peer.properties[0].value.data, TSI_FAKE_CERTIFICATE_TYPE, peer.properties[0].value.length))
    {
      gpr_log (GPR_ERROR, "Invalid value for cert type property.");
      status = GRPC_SECURITY_ERROR;
      goto end;
    }
  GRPC_AUTH_CONTEXT_UNREF (sc->auth_context, "connector");
  sc->auth_context = grpc_auth_context_create (NULL);
  grpc_auth_context_add_cstring_property (sc->auth_context, GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME, GRPC_FAKE_TRANSPORT_SECURITY_TYPE);

end:
  tsi_peer_destruct (&peer);
  return status;
}

static grpc_security_status
fake_channel_check_call_host (grpc_exec_ctx * exec_ctx, grpc_channel_security_connector * sc, const char *host, grpc_security_check_cb cb, void *user_data)
{
  grpc_fake_channel_security_connector *c = (grpc_fake_channel_security_connector *) sc;
  if (c->call_host_check_is_async)
    {
      cb (exec_ctx, user_data, GRPC_SECURITY_OK);
      return GRPC_SECURITY_PENDING;
    }
  else
    {
      return GRPC_SECURITY_OK;
    }
}

static void
fake_channel_do_handshake (grpc_exec_ctx * exec_ctx, grpc_security_connector * sc, grpc_endpoint * nonsecure_endpoint, grpc_security_handshake_done_cb cb, void *user_data)
{
  grpc_do_security_handshake (tsi_create_fake_handshaker (exec_ctx, 1), sc, nonsecure_endpoint, cb, user_data);
}

static void
fake_server_do_handshake (grpc_exec_ctx * exec_ctx, grpc_security_connector * sc, grpc_endpoint * nonsecure_endpoint, grpc_security_handshake_done_cb cb, void *user_data)
{
  grpc_do_security_handshake (tsi_create_fake_handshaker (exec_ctx, 0), sc, nonsecure_endpoint, cb, user_data);
}

static grpc_security_connector_vtable fake_channel_vtable = {
  fake_channel_destroy, fake_channel_do_handshake, fake_check_peer
};

static grpc_security_connector_vtable fake_server_vtable = {
  fake_server_destroy, fake_server_do_handshake, fake_check_peer
};

grpc_channel_security_connector *
grpc_fake_channel_security_connector_create (grpc_credentials * request_metadata_creds, int call_host_check_is_async)
{
  grpc_fake_channel_security_connector *c = gpr_malloc (sizeof (grpc_fake_channel_security_connector));
  memset (c, 0, sizeof (grpc_fake_channel_security_connector));
  gpr_ref_init (&c->base.base.refcount, 1);
  c->base.base.is_client_side = 1;
  c->base.base.url_scheme = GRPC_FAKE_SECURITY_URL_SCHEME;
  c->base.base.vtable = &fake_channel_vtable;
  GPR_ASSERT (check_request_metadata_creds (request_metadata_creds));
  c->base.request_metadata_creds = grpc_credentials_ref (request_metadata_creds);
  c->base.check_call_host = fake_channel_check_call_host;
  c->call_host_check_is_async = call_host_check_is_async;
  return &c->base;
}

grpc_security_connector *
grpc_fake_server_security_connector_create (void)
{
  grpc_security_connector *c = gpr_malloc (sizeof (grpc_security_connector));
  memset (c, 0, sizeof (grpc_security_connector));
  gpr_ref_init (&c->refcount, 1);
  c->is_client_side = 0;
  c->vtable = &fake_server_vtable;
  c->url_scheme = GRPC_FAKE_SECURITY_URL_SCHEME;
  return c;
}

/* --- Ssl implementation. --- */

typedef struct
{
  grpc_channel_security_connector base;
  tsi_ssl_handshaker_factory *handshaker_factory;
  char *target_name;
  char *overridden_target_name;
  tsi_peer peer;
} grpc_ssl_channel_security_connector;

typedef struct
{
  grpc_security_connector base;
  tsi_ssl_handshaker_factory *handshaker_factory;
} grpc_ssl_server_security_connector;

static void
ssl_channel_destroy (grpc_security_connector * sc)
{
  grpc_ssl_channel_security_connector *c = (grpc_ssl_channel_security_connector *) sc;
  grpc_credentials_unref (c->base.request_metadata_creds);
  if (c->handshaker_factory != NULL)
    {
      tsi_ssl_handshaker_factory_destroy (c->handshaker_factory);
    }
  if (c->target_name != NULL)
    gpr_free (c->target_name);
  if (c->overridden_target_name != NULL)
    gpr_free (c->overridden_target_name);
  tsi_peer_destruct (&c->peer);
  GRPC_AUTH_CONTEXT_UNREF (sc->auth_context, "connector");
  gpr_free (sc);
}

static void
ssl_server_destroy (grpc_security_connector * sc)
{
  grpc_ssl_server_security_connector *c = (grpc_ssl_server_security_connector *) sc;
  if (c->handshaker_factory != NULL)
    {
      tsi_ssl_handshaker_factory_destroy (c->handshaker_factory);
    }
  GRPC_AUTH_CONTEXT_UNREF (sc->auth_context, "connector");
  gpr_free (sc);
}

static grpc_security_status
ssl_create_handshaker (tsi_ssl_handshaker_factory * handshaker_factory, int is_client, const char *peer_name, tsi_handshaker ** handshaker)
{
  tsi_result result = TSI_OK;
  if (handshaker_factory == NULL)
    return GRPC_SECURITY_ERROR;
  result = tsi_ssl_handshaker_factory_create_handshaker (handshaker_factory, is_client ? peer_name : NULL, handshaker);
  if (result != TSI_OK)
    {
      gpr_log (GPR_ERROR, "Handshaker creation failed with error %s.", tsi_result_to_string (result));
      return GRPC_SECURITY_ERROR;
    }
  return GRPC_SECURITY_OK;
}

static void
ssl_channel_do_handshake (grpc_exec_ctx * exec_ctx, grpc_security_connector * sc, grpc_endpoint * nonsecure_endpoint, grpc_security_handshake_done_cb cb, void *user_data)
{
  grpc_ssl_channel_security_connector *c = (grpc_ssl_channel_security_connector *) sc;
  tsi_handshaker *handshaker;
  grpc_security_status status = ssl_create_handshaker (c->handshaker_factory, 1,
						       c->overridden_target_name != NULL ? c->overridden_target_name : c->target_name,
						       &handshaker);
  if (status != GRPC_SECURITY_OK)
    {
      cb (exec_ctx, user_data, status, nonsecure_endpoint, NULL);
    }
  else
    {
      grpc_do_security_handshake (exec_ctx, handshaker, sc, nonsecure_endpoint, cb, user_data);
    }
}

static void
ssl_server_do_handshake (grpc_exec_ctx * exec_ctx, grpc_security_connector * sc, grpc_endpoint * nonsecure_endpoint, grpc_security_handshake_done_cb cb, void *user_data)
{
  grpc_ssl_server_security_connector *c = (grpc_ssl_server_security_connector *) sc;
  tsi_handshaker *handshaker;
  grpc_security_status status = ssl_create_handshaker (c->handshaker_factory, 0, NULL, &handshaker);
  if (status != GRPC_SECURITY_OK)
    {
      cb (exec_ctx, user_data, status, nonsecure_endpoint, NULL);
    }
  else
    {
      grpc_do_security_handshake (exec_ctx, handshaker, sc, nonsecure_endpoint, cb, user_data);
    }
}

static int
ssl_host_matches_name (const tsi_peer * peer, const char *peer_name)
{
  char *allocated_name = NULL;
  int r;

  if (strchr (peer_name, ':') != NULL)
    {
      char *ignored_port;
      gpr_split_host_port (peer_name, &allocated_name, &ignored_port);
      gpr_free (ignored_port);
      peer_name = allocated_name;
      if (!peer_name)
	return 0;
    }
  r = tsi_ssl_peer_matches_name (peer, peer_name);
  gpr_free (allocated_name);
  return r;
}

grpc_auth_context *
tsi_ssl_peer_to_auth_context (const tsi_peer * peer)
{
  size_t i;
  grpc_auth_context *ctx = NULL;
  const char *peer_identity_property_name = NULL;

  /* The caller has checked the certificate type property. */
  GPR_ASSERT (peer->property_count >= 1);
  ctx = grpc_auth_context_create (NULL);
  grpc_auth_context_add_cstring_property (ctx, GRPC_TRANSPORT_SECURITY_TYPE_PROPERTY_NAME, GRPC_SSL_TRANSPORT_SECURITY_TYPE);
  for (i = 0; i < peer->property_count; i++)
    {
      const tsi_peer_property *prop = &peer->properties[i];
      if (prop->name == NULL)
	continue;
      if (strcmp (prop->name, TSI_X509_SUBJECT_COMMON_NAME_PEER_PROPERTY) == 0)
	{
	  /* If there is no subject alt name, have the CN as the identity. */
	  if (peer_identity_property_name == NULL)
	    {
	      peer_identity_property_name = GRPC_X509_CN_PROPERTY_NAME;
	    }
	  grpc_auth_context_add_property (ctx, GRPC_X509_CN_PROPERTY_NAME, prop->value.data, prop->value.length);
	}
      else if (strcmp (prop->name, TSI_X509_SUBJECT_ALTERNATIVE_NAME_PEER_PROPERTY) == 0)
	{
	  peer_identity_property_name = GRPC_X509_SAN_PROPERTY_NAME;
	  grpc_auth_context_add_property (ctx, GRPC_X509_SAN_PROPERTY_NAME, prop->value.data, prop->value.length);
	}
    }
  if (peer_identity_property_name != NULL)
    {
      GPR_ASSERT (grpc_auth_context_set_peer_identity_property_name (ctx, peer_identity_property_name) == 1);
    }
  return ctx;
}

static grpc_security_status
ssl_check_peer (grpc_security_connector * sc, const char *peer_name, const tsi_peer * peer)
{
  /* Check the ALPN. */
  const tsi_peer_property *p = tsi_peer_get_property_by_name (peer, TSI_SSL_ALPN_SELECTED_PROTOCOL);
  if (p == NULL)
    {
      gpr_log (GPR_ERROR, "Missing selected ALPN property.");
      return GRPC_SECURITY_ERROR;
    }
  if (!grpc_chttp2_is_alpn_version_supported (p->value.data, p->value.length))
    {
      gpr_log (GPR_ERROR, "Invalid ALPN value.");
      return GRPC_SECURITY_ERROR;
    }

  /* Check the peer name if specified. */
  if (peer_name != NULL && !ssl_host_matches_name (peer, peer_name))
    {
      gpr_log (GPR_ERROR, "Peer name %s is not in peer certificate", peer_name);
      return GRPC_SECURITY_ERROR;
    }
  if (sc->auth_context != NULL)
    {
      GRPC_AUTH_CONTEXT_UNREF (sc->auth_context, "connector");
    }
  sc->auth_context = tsi_ssl_peer_to_auth_context (peer);
  return GRPC_SECURITY_OK;
}

static grpc_security_status
ssl_channel_check_peer (grpc_security_connector * sc, tsi_peer peer, grpc_security_check_cb cb, void *user_data)
{
  grpc_ssl_channel_security_connector *c = (grpc_ssl_channel_security_connector *) sc;
  grpc_security_status status;
  tsi_peer_destruct (&c->peer);
  c->peer = peer;
  status = ssl_check_peer (sc, c->overridden_target_name != NULL ? c->overridden_target_name : c->target_name, &peer);
  return status;
}

static grpc_security_status
ssl_server_check_peer (grpc_security_connector * sc, tsi_peer peer, grpc_security_check_cb cb, void *user_data)
{
  grpc_security_status status = ssl_check_peer (sc, NULL, &peer);
  tsi_peer_destruct (&peer);
  return status;
}

static grpc_security_status
ssl_channel_check_call_host (grpc_exec_ctx * exec_ctx, grpc_channel_security_connector * sc, const char *host, grpc_security_check_cb cb, void *user_data)
{
  grpc_ssl_channel_security_connector *c = (grpc_ssl_channel_security_connector *) sc;

  if (ssl_host_matches_name (&c->peer, host))
    return GRPC_SECURITY_OK;

  /* If the target name was overridden, then the original target_name was
     'checked' transitively during the previous peer check at the end of the
     handshake. */
  if (c->overridden_target_name != NULL && strcmp (host, c->target_name) == 0)
    {
      return GRPC_SECURITY_OK;
    }
  else
    {
      return GRPC_SECURITY_ERROR;
    }
}

static grpc_security_connector_vtable ssl_channel_vtable = {
  ssl_channel_destroy, ssl_channel_do_handshake, ssl_channel_check_peer
};

static grpc_security_connector_vtable ssl_server_vtable = {
  ssl_server_destroy, ssl_server_do_handshake, ssl_server_check_peer
};

static gpr_slice default_pem_root_certs;

static void
init_default_pem_root_certs (void)
{
  /* First try to load the roots from the environment. */
  char *default_root_certs_path = gpr_getenv (GRPC_DEFAULT_SSL_ROOTS_FILE_PATH_ENV_VAR);
  if (default_root_certs_path == NULL)
    {
      default_pem_root_certs = gpr_empty_slice ();
    }
  else
    {
      default_pem_root_certs = gpr_load_file (default_root_certs_path, 0, NULL);
      gpr_free (default_root_certs_path);
    }

  /* Fall back to installed certs if needed. */
  if (GPR_SLICE_IS_EMPTY (default_pem_root_certs))
    {
      default_pem_root_certs = gpr_load_file (installed_roots_path, 0, NULL);
    }
}

size_t
grpc_get_default_ssl_roots (const unsigned char **pem_root_certs)
{
  /* TODO(jboeuf@google.com): Maybe revisit the approach which consists in
     loading all the roots once for the lifetime of the process. */
  static gpr_once once = GPR_ONCE_INIT;
  gpr_once_init (&once, init_default_pem_root_certs);
  *pem_root_certs = GPR_SLICE_START_PTR (default_pem_root_certs);
  return GPR_SLICE_LENGTH (default_pem_root_certs);
}

grpc_security_status
grpc_ssl_channel_security_connector_create (grpc_credentials * request_metadata_creds, const grpc_ssl_config * config, const char *target_name, const char *overridden_target_name, grpc_channel_security_connector ** sc)
{
  size_t num_alpn_protocols = grpc_chttp2_num_alpn_versions ();
  const unsigned char **alpn_protocol_strings = gpr_malloc (sizeof (const char *) * num_alpn_protocols);
  unsigned char *alpn_protocol_string_lengths = gpr_malloc (sizeof (unsigned char) * num_alpn_protocols);
  tsi_result result = TSI_OK;
  grpc_ssl_channel_security_connector *c;
  size_t i;
  const unsigned char *pem_root_certs;
  size_t pem_root_certs_size;
  char *port;

  for (i = 0; i < num_alpn_protocols; i++)
    {
      alpn_protocol_strings[i] = (const unsigned char *) grpc_chttp2_get_alpn_version_index (i);
      alpn_protocol_string_lengths[i] = (unsigned char) strlen (grpc_chttp2_get_alpn_version_index (i));
    }

  if (config == NULL || target_name == NULL)
    {
      gpr_log (GPR_ERROR, "An ssl channel needs a config and a target name.");
      goto error;
    }
  if (!check_request_metadata_creds (request_metadata_creds))
    {
      goto error;
    }
  if (config->pem_root_certs == NULL)
    {
      pem_root_certs_size = grpc_get_default_ssl_roots (&pem_root_certs);
      if (pem_root_certs == NULL || pem_root_certs_size == 0)
	{
	  gpr_log (GPR_ERROR, "Could not get default pem root certs.");
	  goto error;
	}
    }
  else
    {
      pem_root_certs = config->pem_root_certs;
      pem_root_certs_size = config->pem_root_certs_size;
    }

  c = gpr_malloc (sizeof (grpc_ssl_channel_security_connector));
  memset (c, 0, sizeof (grpc_ssl_channel_security_connector));

  gpr_ref_init (&c->base.base.refcount, 1);
  c->base.base.vtable = &ssl_channel_vtable;
  c->base.base.is_client_side = 1;
  c->base.base.url_scheme = GRPC_SSL_URL_SCHEME;
  c->base.request_metadata_creds = grpc_credentials_ref (request_metadata_creds);
  c->base.check_call_host = ssl_channel_check_call_host;
  gpr_split_host_port (target_name, &c->target_name, &port);
  gpr_free (port);
  if (overridden_target_name != NULL)
    {
      c->overridden_target_name = gpr_strdup (overridden_target_name);
    }
  result = tsi_create_ssl_client_handshaker_factory (config->pem_private_key, config->pem_private_key_size, config->pem_cert_chain, config->pem_cert_chain_size, pem_root_certs, pem_root_certs_size, ssl_cipher_suites (), alpn_protocol_strings, alpn_protocol_string_lengths, (uint16_t) num_alpn_protocols, &c->handshaker_factory);
  if (result != TSI_OK)
    {
      gpr_log (GPR_ERROR, "Handshaker factory creation failed with %s.", tsi_result_to_string (result));
      ssl_channel_destroy (&c->base.base);
      *sc = NULL;
      goto error;
    }
  *sc = &c->base;
  gpr_free (alpn_protocol_strings);
  gpr_free (alpn_protocol_string_lengths);
  return GRPC_SECURITY_OK;

error:
  gpr_free (alpn_protocol_strings);
  gpr_free (alpn_protocol_string_lengths);
  return GRPC_SECURITY_ERROR;
}

grpc_security_status
grpc_ssl_server_security_connector_create (const grpc_ssl_server_config * config, grpc_security_connector ** sc)
{
  size_t num_alpn_protocols = grpc_chttp2_num_alpn_versions ();
  const unsigned char **alpn_protocol_strings = gpr_malloc (sizeof (const char *) * num_alpn_protocols);
  unsigned char *alpn_protocol_string_lengths = gpr_malloc (sizeof (unsigned char) * num_alpn_protocols);
  tsi_result result = TSI_OK;
  grpc_ssl_server_security_connector *c;
  size_t i;

  for (i = 0; i < num_alpn_protocols; i++)
    {
      alpn_protocol_strings[i] = (const unsigned char *) grpc_chttp2_get_alpn_version_index (i);
      alpn_protocol_string_lengths[i] = (unsigned char) strlen (grpc_chttp2_get_alpn_version_index (i));
    }

  if (config == NULL || config->num_key_cert_pairs == 0)
    {
      gpr_log (GPR_ERROR, "An SSL server needs a key and a cert.");
      goto error;
    }
  c = gpr_malloc (sizeof (grpc_ssl_server_security_connector));
  memset (c, 0, sizeof (grpc_ssl_server_security_connector));

  gpr_ref_init (&c->base.refcount, 1);
  c->base.url_scheme = GRPC_SSL_URL_SCHEME;
  c->base.vtable = &ssl_server_vtable;
  result = tsi_create_ssl_server_handshaker_factory ((const unsigned char **) config->pem_private_keys, config->pem_private_keys_sizes, (const unsigned char **) config->pem_cert_chains, config->pem_cert_chains_sizes, config->num_key_cert_pairs, config->pem_root_certs, config->pem_root_certs_size, config->force_client_auth, ssl_cipher_suites (), alpn_protocol_strings, alpn_protocol_string_lengths, (uint16_t) num_alpn_protocols, &c->handshaker_factory);
  if (result != TSI_OK)
    {
      gpr_log (GPR_ERROR, "Handshaker factory creation failed with %s.", tsi_result_to_string (result));
      ssl_server_destroy (&c->base);
      *sc = NULL;
      goto error;
    }
  *sc = &c->base;
  gpr_free (alpn_protocol_strings);
  gpr_free (alpn_protocol_string_lengths);
  return GRPC_SECURITY_OK;

error:
  gpr_free (alpn_protocol_strings);
  gpr_free (alpn_protocol_string_lengths);
  return GRPC_SECURITY_ERROR;
}