/*
 *
 * 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 <grpc/grpc.h>

#include <string.h>

#include "src/core/channel/channel_args.h"
#include "src/core/channel/http_server_filter.h"
#include "src/core/iomgr/endpoint.h"
#include "src/core/iomgr/resolve_address.h"
#include "src/core/iomgr/tcp_server.h"
#include "src/core/security/auth_filters.h"
#include "src/core/security/credentials.h"
#include "src/core/security/security_connector.h"
#include "src/core/security/security_context.h"
#include "src/core/security/secure_transport_setup.h"
#include "src/core/surface/server.h"
#include "src/core/transport/chttp2_transport.h"
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <grpc/support/useful.h>

typedef struct tcp_endpoint_list {
  grpc_endpoint *tcp_endpoint;
  struct tcp_endpoint_list *next;
} tcp_endpoint_list;

typedef struct grpc_server_secure_state {
  grpc_server *server;
  grpc_tcp_server *tcp;
  grpc_security_connector *sc;
  grpc_server_credentials *creds;
  tcp_endpoint_list *handshaking_tcp_endpoints;
  int is_shutdown;
  gpr_mu mu;
  gpr_refcount refcount;
} grpc_server_secure_state;

static void state_ref(grpc_server_secure_state *state) {
  gpr_ref(&state->refcount);
}

static void state_unref(grpc_server_secure_state *state) {
  if (gpr_unref(&state->refcount)) {
    /* ensure all threads have unlocked */
    gpr_mu_lock(&state->mu);
    gpr_mu_unlock(&state->mu);
    /* clean up */
    GRPC_SECURITY_CONNECTOR_UNREF(state->sc, "server");
    grpc_server_credentials_unref(state->creds);
    gpr_free(state);
  }
}

static void setup_transport(void *statep, grpc_transport *transport,
                            grpc_mdctx *mdctx) {
  static grpc_channel_filter const *extra_filters[] = {
      &grpc_server_auth_filter, &grpc_http_server_filter};
  grpc_server_secure_state *state = statep;
  grpc_channel_args *args_copy;
  grpc_arg args_to_add[2];
  args_to_add[0] = grpc_security_connector_to_arg(state->sc);
  args_to_add[1] =
      grpc_auth_metadata_processor_to_arg(&state->creds->processor);
  args_copy = grpc_channel_args_copy_and_add(
      grpc_server_get_channel_args(state->server), args_to_add,
      GPR_ARRAY_SIZE(args_to_add));
  grpc_server_setup_transport(state->server, transport, extra_filters,
                              GPR_ARRAY_SIZE(extra_filters), mdctx, args_copy);
  grpc_channel_args_destroy(args_copy);
}

static int remove_tcp_from_list_locked(grpc_server_secure_state *state,
                                       grpc_endpoint *tcp) {
  tcp_endpoint_list *node = state->handshaking_tcp_endpoints;
  tcp_endpoint_list *tmp = NULL;
  if (node && node->tcp_endpoint == tcp) {
    state->handshaking_tcp_endpoints = state->handshaking_tcp_endpoints->next;
    gpr_free(node);
    return 0;
  }
  while (node) {
    if (node->next->tcp_endpoint == tcp) {
      tmp = node->next;
      node->next = node->next->next;
      gpr_free(tmp);
      return 0;
    }
    node = node->next;
  }
  return -1;
}

static void on_secure_transport_setup_done(void *statep,
                                           grpc_security_status status,
                                           grpc_endpoint *wrapped_endpoint,
                                           grpc_endpoint *secure_endpoint) {
  grpc_server_secure_state *state = statep;
  grpc_transport *transport;
  grpc_mdctx *mdctx;
  if (status == GRPC_SECURITY_OK) {
    gpr_mu_lock(&state->mu);
    remove_tcp_from_list_locked(state, wrapped_endpoint);
    if (!state->is_shutdown) {
      mdctx = grpc_mdctx_create();
      transport = grpc_create_chttp2_transport(
          grpc_server_get_channel_args(state->server), secure_endpoint, mdctx,
          0);
      setup_transport(state, transport, mdctx);
      grpc_chttp2_transport_start_reading(transport, NULL, 0);
    } else {
      /* We need to consume this here, because the server may already have gone
       * away. */
      grpc_endpoint_destroy(secure_endpoint);
    }
    gpr_mu_unlock(&state->mu);
  } else {
    gpr_mu_lock(&state->mu);
    remove_tcp_from_list_locked(state, wrapped_endpoint);
    gpr_mu_unlock(&state->mu);
    gpr_log(GPR_ERROR, "Secure transport failed with error %d", status);
  }
  state_unref(state);
}

static void on_accept(void *statep, grpc_endpoint *tcp) {
  grpc_server_secure_state *state = statep;
  tcp_endpoint_list *node;
  state_ref(state);
  node = gpr_malloc(sizeof(tcp_endpoint_list));
  node->tcp_endpoint = tcp;
  gpr_mu_lock(&state->mu);
  node->next = state->handshaking_tcp_endpoints;
  state->handshaking_tcp_endpoints = node;
  gpr_mu_unlock(&state->mu);
  grpc_setup_secure_transport(state->sc, tcp, on_secure_transport_setup_done,
                              state);
}

/* Server callback: start listening on our ports */
static void start(grpc_server *server, void *statep, grpc_pollset **pollsets,
                  size_t pollset_count) {
  grpc_server_secure_state *state = statep;
  grpc_tcp_server_start(state->tcp, pollsets, pollset_count, on_accept, state);
}

static void destroy_done(void *statep) {
  grpc_server_secure_state *state = statep;
  grpc_server_listener_destroy_done(state->server);
  gpr_mu_lock(&state->mu);
  while (state->handshaking_tcp_endpoints != NULL) {
    grpc_endpoint_shutdown(state->handshaking_tcp_endpoints->tcp_endpoint);
    remove_tcp_from_list_locked(state,
                                state->handshaking_tcp_endpoints->tcp_endpoint);
  }
  gpr_mu_unlock(&state->mu);
  state_unref(state);
}

/* Server callback: destroy the tcp listener (so we don't generate further
   callbacks) */
static void destroy(grpc_server *server, void *statep) {
  grpc_server_secure_state *state = statep;
  grpc_tcp_server *tcp;
  gpr_mu_lock(&state->mu);
  state->is_shutdown = 1;
  tcp = state->tcp;
  gpr_mu_unlock(&state->mu);
  grpc_tcp_server_destroy(tcp, destroy_done, state);
}

int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
                                      grpc_server_credentials *creds) {
  grpc_resolved_addresses *resolved = NULL;
  grpc_tcp_server *tcp = NULL;
  grpc_server_secure_state *state = NULL;
  size_t i;
  unsigned count = 0;
  int port_num = -1;
  int port_temp;
  grpc_security_status status = GRPC_SECURITY_ERROR;
  grpc_security_connector *sc = NULL;

  /* create security context */
  if (creds == NULL) goto error;
  status = grpc_server_credentials_create_security_connector(creds, &sc);
  if (status != GRPC_SECURITY_OK) {
    gpr_log(GPR_ERROR,
            "Unable to create secure server with credentials of type %s.",
            creds->type);
    goto error;
  }

  /* resolve address */
  resolved = grpc_blocking_resolve_address(addr, "https");
  if (!resolved) {
    goto error;
  }

  tcp = grpc_tcp_server_create();
  if (!tcp) {
    goto error;
  }

  for (i = 0; i < resolved->naddrs; i++) {
    port_temp = grpc_tcp_server_add_port(
        tcp, (struct sockaddr *)&resolved->addrs[i].addr,
        resolved->addrs[i].len);
    if (port_temp >= 0) {
      if (port_num == -1) {
        port_num = port_temp;
      } else {
        GPR_ASSERT(port_num == port_temp);
      }
      count++;
    }
  }
  if (count == 0) {
    gpr_log(GPR_ERROR, "No address added out of total %d resolved",
            resolved->naddrs);
    goto error;
  }
  if (count != resolved->naddrs) {
    gpr_log(GPR_ERROR, "Only %d addresses added out of total %d resolved",
            count, resolved->naddrs);
    /* if it's an error, don't we want to goto error; here ? */
  }
  grpc_resolved_addresses_destroy(resolved);

  state = gpr_malloc(sizeof(*state));
  memset(state, 0, sizeof(*state));
  state->server = server;
  state->tcp = tcp;
  state->sc = sc;
  state->creds = grpc_server_credentials_ref(creds);

  state->handshaking_tcp_endpoints = NULL;
  state->is_shutdown = 0;
  gpr_mu_init(&state->mu);
  gpr_ref_init(&state->refcount, 1);

  /* Register with the server only upon success */
  grpc_server_add_listener(server, state, start, destroy);

  return port_num;

/* Error path: cleanup and return */
error:
  if (sc) {
    GRPC_SECURITY_CONNECTOR_UNREF(sc, "server");
  }
  if (resolved) {
    grpc_resolved_addresses_destroy(resolved);
  }
  if (tcp) {
    grpc_tcp_server_destroy(tcp, NULL, NULL);
  }
  if (state) {
    gpr_free(state);
  }
  return 0;
}