grpcio-sys 0.1.0

/*
 *
 * 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.
 *
 */

// Copyright 2017 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

// Because rust's union implementation is unstable and possibly buggy
// (rust-lang/rust#32836),
// so we need to wrap the type and expose more safer interfaces.

#include <grpc/byte_buffer_reader.h>
#include <grpc/grpc.h>
#include <grpc/grpc_security.h>
#include <grpc/slice.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/port_platform.h>
#include <grpc/support/string_util.h>
#include <grpc/support/thd.h>

#include <string.h>

#ifdef GPR_WINDOWS
#define GPR_EXPORT __declspec(dllexport)
#define GPR_CALLTYPE __stdcall
#endif

#ifndef GPR_EXPORT
#define GPR_EXPORT
#endif

#ifndef GPR_CALLTYPE
#define GPR_CALLTYPE
#endif

grpc_byte_buffer *string_to_byte_buffer(const char *buffer, size_t len) {
  grpc_slice slice = grpc_slice_from_copied_buffer(buffer, len);
  grpc_byte_buffer *bb = grpc_raw_byte_buffer_create(&slice, 1);
  grpc_slice_unref(slice);
  return bb;
}

/*
 * Helper to maintain lifetime of batch op inputs and store batch op outputs.
 */
typedef struct grpcwrap_batch_context {
  grpc_metadata_array send_initial_metadata;
  grpc_byte_buffer *send_message;
  struct {
    grpc_metadata_array trailing_metadata;
  } send_status_from_server;
  grpc_metadata_array recv_initial_metadata;
  grpc_byte_buffer *recv_message;
  struct {
    grpc_metadata_array trailing_metadata;
    grpc_status_code status;
    grpc_slice status_details;
  } recv_status_on_client;
  int recv_close_on_server_cancelled;
} grpcwrap_batch_context;

GPR_EXPORT grpcwrap_batch_context *GPR_CALLTYPE
grpcwrap_batch_context_create() {
  grpcwrap_batch_context *ctx = gpr_malloc(sizeof(grpcwrap_batch_context));
  memset(ctx, 0, sizeof(grpcwrap_batch_context));
  return ctx;
}

typedef struct {
  grpc_call *call;
  grpc_call_details call_details;
  grpc_metadata_array request_metadata;
} grpcwrap_request_call_context;

GPR_EXPORT grpcwrap_request_call_context *GPR_CALLTYPE
grpcwrap_request_call_context_create() {
  grpcwrap_request_call_context *ctx =
      gpr_malloc(sizeof(grpcwrap_request_call_context));
  memset(ctx, 0, sizeof(grpcwrap_request_call_context));
  return ctx;
}

/*
 * Destroys array->metadata.
 * The array pointer itself is not freed.
 */
void grpcwrap_metadata_array_destroy_metadata_only(grpc_metadata_array *array) {
  gpr_free(array->metadata);
}

/*
 * Destroys keys, values and array->metadata.
 * The array pointer itself is not freed.
 */
void grpcwrap_metadata_array_destroy_metadata_including_entries(
    grpc_metadata_array *array) {
  size_t i;
  if (array->metadata) {
    for (i = 0; i < array->count; i++) {
      grpc_slice_unref(array->metadata[i].key);
      grpc_slice_unref(array->metadata[i].value);
    }
  }
  gpr_free(array->metadata);
}

/*
 * Fully destroys the metadata array.
 */
GPR_EXPORT void GPR_CALLTYPE
grpcwrap_metadata_array_destroy_full(grpc_metadata_array *array) {
  if (!array) {
    return;
  }
  grpcwrap_metadata_array_destroy_metadata_including_entries(array);
  gpr_free(array);
}

/*
 * Creates an empty metadata array with given capacity.
 * Array can later be destroyed by grpc_metadata_array_destroy_full.
 */
GPR_EXPORT grpc_metadata_array *GPR_CALLTYPE
grpcwrap_metadata_array_create(size_t capacity) {
  grpc_metadata_array *array =
      (grpc_metadata_array *)gpr_malloc(sizeof(grpc_metadata_array));
  grpc_metadata_array_init(array);
  array->capacity = capacity;
  array->count = 0;
  if (capacity > 0) {
    array->metadata =
        (grpc_metadata *)gpr_malloc(sizeof(grpc_metadata) * capacity);
    memset(array->metadata, 0, sizeof(grpc_metadata) * capacity);
  } else {
    array->metadata = NULL;
  }
  return array;
}

GPR_EXPORT void GPR_CALLTYPE
grpcwrap_metadata_array_add(grpc_metadata_array *array, const char *key,
                            const char *value, size_t value_length) {
  size_t i = array->count;
  GPR_ASSERT(array->count < array->capacity);
  array->metadata[i].key = grpc_slice_from_copied_string(key);
  array->metadata[i].value = grpc_slice_from_copied_buffer(value, value_length);
  array->count++;
}

GPR_EXPORT size_t GPR_CALLTYPE
grpcwrap_metadata_array_count(grpc_metadata_array *array) {
  return array->count;
}

GPR_EXPORT const char *GPR_CALLTYPE grpcwrap_metadata_array_get_key(
    grpc_metadata_array *array, size_t index, size_t *key_length) {
  GPR_ASSERT(index < array->count);
  *key_length = GRPC_SLICE_LENGTH(array->metadata[index].key);
  return (char *)GRPC_SLICE_START_PTR(array->metadata[index].key);
}

GPR_EXPORT const char *GPR_CALLTYPE grpcwrap_metadata_array_get_value(
    grpc_metadata_array *array, size_t index, size_t *value_length) {
  GPR_ASSERT(index < array->count);
  *value_length = GRPC_SLICE_LENGTH(array->metadata[index].value);
  return (char *)GRPC_SLICE_START_PTR(array->metadata[index].value);
}

/* Move contents of metadata array */
void grpcwrap_metadata_array_move(grpc_metadata_array *dest,
                                  grpc_metadata_array *src) {
  if (!src) {
    dest->capacity = 0;
    dest->count = 0;
    dest->metadata = NULL;
    return;
  }

  dest->capacity = src->capacity;
  dest->count = src->count;
  dest->metadata = src->metadata;

  src->capacity = 0;
  src->count = 0;
  src->metadata = NULL;
}

GPR_EXPORT void GPR_CALLTYPE
grpcwrap_batch_context_destroy(grpcwrap_batch_context *ctx) {
  if (!ctx) {
    return;
  }
  grpcwrap_metadata_array_destroy_metadata_including_entries(
      &(ctx->send_initial_metadata));

  grpc_byte_buffer_destroy(ctx->send_message);

  grpcwrap_metadata_array_destroy_metadata_including_entries(
      &(ctx->send_status_from_server.trailing_metadata));

  grpcwrap_metadata_array_destroy_metadata_only(&(ctx->recv_initial_metadata));

  grpc_byte_buffer_destroy(ctx->recv_message);

  grpcwrap_metadata_array_destroy_metadata_only(
      &(ctx->recv_status_on_client.trailing_metadata));
  grpc_slice_unref(ctx->recv_status_on_client.status_details);

  gpr_free(ctx);
}

GPR_EXPORT void GPR_CALLTYPE
grpcwrap_request_call_context_destroy(grpcwrap_request_call_context *ctx) {
  if (!ctx) {
    return;
  }

  if (ctx->call) {
    grpc_call_unref(ctx->call);
  }

  grpc_call_details_destroy(&(ctx->call_details));
  grpcwrap_metadata_array_destroy_metadata_only(&(ctx->request_metadata));

  gpr_free(ctx);
}

GPR_EXPORT const grpc_metadata_array *GPR_CALLTYPE
grpcwrap_batch_context_recv_initial_metadata(
    const grpcwrap_batch_context *ctx) {
  return &(ctx->recv_initial_metadata);
}

GPR_EXPORT size_t GPR_CALLTYPE
grpcwrap_batch_context_recv_message_length(const grpcwrap_batch_context *ctx) {
  grpc_byte_buffer_reader reader;
  if (!ctx->recv_message) {
    return -1;
  }

  GPR_ASSERT(grpc_byte_buffer_reader_init(&reader, ctx->recv_message));
  size_t result = grpc_byte_buffer_length(reader.buffer_out);
  grpc_byte_buffer_reader_destroy(&reader);

  return result;
}

/*
 * Copies data from recv_message to a buffer. Fatal error occurs if
 * buffer is too small.
 */
GPR_EXPORT void GPR_CALLTYPE grpcwrap_batch_context_recv_message_to_buffer(
    const grpcwrap_batch_context *ctx, char *buffer, size_t buffer_len) {
  grpc_byte_buffer_reader reader;
  grpc_slice slice;
  size_t offset = 0;

  GPR_ASSERT(grpc_byte_buffer_reader_init(&reader, ctx->recv_message));

  while (grpc_byte_buffer_reader_next(&reader, &slice)) {
    size_t len = GRPC_SLICE_LENGTH(slice);
    GPR_ASSERT(offset + len <= buffer_len);
    memcpy(buffer + offset, GRPC_SLICE_START_PTR(slice),
           GRPC_SLICE_LENGTH(slice));
    offset += len;
    grpc_slice_unref(slice);
  }

  grpc_byte_buffer_reader_destroy(&reader);
}

GPR_EXPORT grpc_status_code GPR_CALLTYPE
grpcwrap_batch_context_recv_status_on_client_status(
    const grpcwrap_batch_context *ctx) {
  return ctx->recv_status_on_client.status;
}

GPR_EXPORT const char *GPR_CALLTYPE
grpcwrap_batch_context_recv_status_on_client_details(
    const grpcwrap_batch_context *ctx, size_t *details_length) {
  *details_length =
      GRPC_SLICE_LENGTH(ctx->recv_status_on_client.status_details);
  return (char *)GRPC_SLICE_START_PTR(
      ctx->recv_status_on_client.status_details);
}

GPR_EXPORT const grpc_metadata_array *GPR_CALLTYPE
grpcwrap_batch_context_recv_status_on_client_trailing_metadata(
    const grpcwrap_batch_context *ctx) {
  return &(ctx->recv_status_on_client.trailing_metadata);
}

GPR_EXPORT grpc_call *GPR_CALLTYPE
grpcwrap_request_call_context_take_call(grpcwrap_request_call_context *ctx) {
  grpc_call *call = ctx->call;
  ctx->call = NULL;
  return call;
}

GPR_EXPORT grpc_call *GPR_CALLTYPE
grpcwrap_request_call_context_get_call(grpcwrap_request_call_context *ctx) {
  return ctx->call;
}

GPR_EXPORT const char *GPR_CALLTYPE grpcwrap_request_call_context_method(
    const grpcwrap_request_call_context *ctx, size_t *method_length) {
  *method_length = GRPC_SLICE_LENGTH(ctx->call_details.method);
  return (char *)GRPC_SLICE_START_PTR(ctx->call_details.method);
}

GPR_EXPORT const char *GPR_CALLTYPE grpcwrap_request_call_context_host(
    const grpcwrap_request_call_context *ctx, size_t *host_length) {
  *host_length = GRPC_SLICE_LENGTH(ctx->call_details.host);
  return (char *)GRPC_SLICE_START_PTR(ctx->call_details.host);
}

GPR_EXPORT gpr_timespec GPR_CALLTYPE grpcwrap_request_call_context_deadline(
    const grpcwrap_request_call_context *ctx) {
  return ctx->call_details.deadline;
}

GPR_EXPORT const grpc_metadata_array *GPR_CALLTYPE
grpcwrap_request_call_context_request_metadata(
    const grpcwrap_request_call_context *ctx) {
  return &(ctx->request_metadata);
}

GPR_EXPORT int32_t GPR_CALLTYPE
grpcwrap_batch_context_recv_close_on_server_cancelled(
    const grpcwrap_batch_context *ctx) {
  return (int32_t)ctx->recv_close_on_server_cancelled;
}

/* Channel */

GPR_EXPORT grpc_call *GPR_CALLTYPE grpcwrap_channel_create_call(
    grpc_channel *channel, grpc_call *parent_call, uint32_t propagation_mask,
    grpc_completion_queue *cq, const char *method, size_t method_len,
    const char *host, size_t host_len, gpr_timespec deadline) {
  grpc_slice method_slice = grpc_slice_from_copied_buffer(method, method_len);
  grpc_slice *host_slice_ptr = NULL;
  grpc_slice host_slice;
  if (host != NULL) {
    host_slice = grpc_slice_from_copied_buffer(host, host_len);
    host_slice_ptr = &host_slice;
  }
  grpc_call *ret =
      grpc_channel_create_call(channel, parent_call, propagation_mask, cq,
                               method_slice, host_slice_ptr, deadline, NULL);
  grpc_slice_unref(method_slice);
  if (host != NULL) {
    grpc_slice_unref(host_slice);
  }
  return ret;
}

/* Channel args */

GPR_EXPORT grpc_channel_args *GPR_CALLTYPE
grpcwrap_channel_args_create(size_t num_args) {
  grpc_channel_args *args =
      (grpc_channel_args *)gpr_malloc(sizeof(grpc_channel_args));
  memset(args, 0, sizeof(grpc_channel_args));

  args->num_args = num_args;
  args->args = (grpc_arg *)gpr_malloc(sizeof(grpc_arg) * num_args);
  memset(args->args, 0, sizeof(grpc_arg) * num_args);
  return args;
}

GPR_EXPORT void GPR_CALLTYPE grpcwrap_channel_args_set_string(
    grpc_channel_args *args, size_t index, const char *key, const char *value) {
  GPR_ASSERT(args);
  GPR_ASSERT(index < args->num_args);
  args->args[index].type = GRPC_ARG_STRING;
  args->args[index].key = gpr_strdup(key);
  args->args[index].value.string = gpr_strdup(value);
}

GPR_EXPORT void GPR_CALLTYPE grpcwrap_channel_args_set_integer(
    grpc_channel_args *args, size_t index, const char *key, int value) {
  GPR_ASSERT(args);
  GPR_ASSERT(index < args->num_args);
  args->args[index].type = GRPC_ARG_INTEGER;
  args->args[index].key = gpr_strdup(key);
  args->args[index].value.integer = value;
}

GPR_EXPORT void GPR_CALLTYPE
grpcwrap_channel_args_destroy(grpc_channel_args *args) {
  size_t i;
  if (args) {
    for (i = 0; i < args->num_args; i++) {
      gpr_free(args->args[i].key);
      if (args->args[i].type == GRPC_ARG_STRING) {
        gpr_free(args->args[i].value.string);
      }
    }
    gpr_free(args->args);
    gpr_free(args);
  }
}

/* Call */

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_start_unary(
    grpc_call *call, grpcwrap_batch_context *ctx, const char *send_buffer,
    size_t send_buffer_len, uint32_t write_flags,
    grpc_metadata_array *initial_metadata, uint32_t initial_metadata_flags,
    void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[6];
  memset(ops, 0, sizeof(ops));
  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
  grpcwrap_metadata_array_move(&(ctx->send_initial_metadata), initial_metadata);
  ops[0].data.send_initial_metadata.count = ctx->send_initial_metadata.count;
  ops[0].data.send_initial_metadata.metadata =
      ctx->send_initial_metadata.metadata;
  ops[0].flags = initial_metadata_flags;
  ops[0].reserved = NULL;

  ops[1].op = GRPC_OP_SEND_MESSAGE;
  ctx->send_message = string_to_byte_buffer(send_buffer, send_buffer_len);
  ops[1].data.send_message.send_message = ctx->send_message;
  ops[1].flags = write_flags;
  ops[1].reserved = NULL;

  ops[2].op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
  ops[2].flags = 0;
  ops[2].reserved = NULL;

  ops[3].op = GRPC_OP_RECV_INITIAL_METADATA;
  ops[3].data.recv_initial_metadata.recv_initial_metadata =
      &(ctx->recv_initial_metadata);
  ops[3].flags = 0;
  ops[3].reserved = NULL;

  ops[4].op = GRPC_OP_RECV_MESSAGE;
  ops[4].data.recv_message.recv_message = &(ctx->recv_message);
  ops[4].flags = 0;
  ops[4].reserved = NULL;

  ops[5].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
  ops[5].data.recv_status_on_client.trailing_metadata =
      &(ctx->recv_status_on_client.trailing_metadata);
  ops[5].data.recv_status_on_client.status =
      &(ctx->recv_status_on_client.status);
  ops[5].data.recv_status_on_client.status_details =
      &(ctx->recv_status_on_client.status_details);
  ops[5].flags = 0;
  ops[5].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_start_client_streaming(
    grpc_call *call, grpcwrap_batch_context *ctx,
    grpc_metadata_array *initial_metadata, uint32_t initial_metadata_flags,
    void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[4];
  memset(ops, 0, sizeof(ops));
  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
  grpcwrap_metadata_array_move(&(ctx->send_initial_metadata), initial_metadata);
  ops[0].data.send_initial_metadata.count = ctx->send_initial_metadata.count;
  ops[0].data.send_initial_metadata.metadata =
      ctx->send_initial_metadata.metadata;
  ops[0].flags = initial_metadata_flags;
  ops[0].reserved = NULL;

  ops[1].op = GRPC_OP_RECV_INITIAL_METADATA;
  ops[1].data.recv_initial_metadata.recv_initial_metadata =
      &(ctx->recv_initial_metadata);
  ops[1].flags = 0;
  ops[1].reserved = NULL;

  ops[2].op = GRPC_OP_RECV_MESSAGE;
  ops[2].data.recv_message.recv_message = &(ctx->recv_message);
  ops[2].flags = 0;
  ops[2].reserved = NULL;

  ops[3].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
  ops[3].data.recv_status_on_client.trailing_metadata =
      &(ctx->recv_status_on_client.trailing_metadata);
  ops[3].data.recv_status_on_client.status =
      &(ctx->recv_status_on_client.status);
  ops[3].data.recv_status_on_client.status_details =
      &(ctx->recv_status_on_client.status_details);
  ops[3].flags = 0;
  ops[3].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_start_server_streaming(
    grpc_call *call, grpcwrap_batch_context *ctx, const char *send_buffer,
    size_t send_buffer_len, uint32_t write_flags,
    grpc_metadata_array *initial_metadata, uint32_t initial_metadata_flags,
    void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[4];
  memset(ops, 0, sizeof(ops));
  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
  grpcwrap_metadata_array_move(&(ctx->send_initial_metadata), initial_metadata);
  ops[0].data.send_initial_metadata.count = ctx->send_initial_metadata.count;
  ops[0].data.send_initial_metadata.metadata =
      ctx->send_initial_metadata.metadata;
  ops[0].flags = initial_metadata_flags;
  ops[0].reserved = NULL;

  ops[1].op = GRPC_OP_SEND_MESSAGE;
  ctx->send_message = string_to_byte_buffer(send_buffer, send_buffer_len);
  ops[1].data.send_message.send_message = ctx->send_message;
  ops[1].flags = write_flags;
  ops[1].reserved = NULL;

  ops[2].op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
  ops[2].flags = 0;
  ops[2].reserved = NULL;

  ops[3].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
  ops[3].data.recv_status_on_client.trailing_metadata =
      &(ctx->recv_status_on_client.trailing_metadata);
  ops[3].data.recv_status_on_client.status =
      &(ctx->recv_status_on_client.status);
  ops[3].data.recv_status_on_client.status_details =
      &(ctx->recv_status_on_client.status_details);
  ops[3].flags = 0;
  ops[3].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_start_duplex_streaming(
    grpc_call *call, grpcwrap_batch_context *ctx,
    grpc_metadata_array *initial_metadata, uint32_t initial_metadata_flags,
    void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[2];
  memset(ops, 0, sizeof(ops));
  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
  grpcwrap_metadata_array_move(&(ctx->send_initial_metadata), initial_metadata);
  ops[0].data.send_initial_metadata.count = ctx->send_initial_metadata.count;
  ops[0].data.send_initial_metadata.metadata =
      ctx->send_initial_metadata.metadata;
  ops[0].flags = initial_metadata_flags;
  ops[0].reserved = NULL;

  ops[1].op = GRPC_OP_RECV_STATUS_ON_CLIENT;
  ops[1].data.recv_status_on_client.trailing_metadata =
      &(ctx->recv_status_on_client.trailing_metadata);
  ops[1].data.recv_status_on_client.status =
      &(ctx->recv_status_on_client.status);
  ops[1].data.recv_status_on_client.status_details =
      &(ctx->recv_status_on_client.status_details);
  ops[1].flags = 0;
  ops[1].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_recv_initial_metadata(
    grpc_call *call, grpcwrap_batch_context *ctx, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[1];
  ops[0].op = GRPC_OP_RECV_INITIAL_METADATA;
  ops[0].data.recv_initial_metadata.recv_initial_metadata =
      &(ctx->recv_initial_metadata);
  ops[0].flags = 0;
  ops[0].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_send_message(
    grpc_call *call, grpcwrap_batch_context *ctx, const char *send_buffer,
    size_t send_buffer_len, uint32_t write_flags,
    int32_t send_empty_initial_metadata, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[2];
  memset(ops, 0, sizeof(ops));
  size_t nops = send_empty_initial_metadata ? 2 : 1;
  ops[0].op = GRPC_OP_SEND_MESSAGE;
  ctx->send_message = string_to_byte_buffer(send_buffer, send_buffer_len);
  ops[0].data.send_message.send_message = ctx->send_message;
  ops[0].flags = write_flags;
  ops[0].reserved = NULL;
  ops[1].op = GRPC_OP_SEND_INITIAL_METADATA;
  ops[1].flags = 0;
  ops[1].reserved = NULL;

  return grpc_call_start_batch(call, ops, nops, tag, NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_send_close_from_client(
    grpc_call *call, grpcwrap_batch_context *ctx, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[1];
  ops[0].op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
  ops[0].flags = 0;
  ops[0].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_send_status_from_server(
    grpc_call *call, grpcwrap_batch_context *ctx, grpc_status_code status_code,
    const char *status_details, size_t status_details_len,
    grpc_metadata_array *trailing_metadata, int32_t send_empty_initial_metadata,
    const char *optional_send_buffer, size_t optional_send_buffer_len,
    uint32_t write_flags, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[3];
  memset(ops, 0, sizeof(ops));
  size_t nops = 1;
  grpc_slice status_details_slice =
      grpc_slice_from_copied_buffer(status_details, status_details_len);
  ops[0].op = GRPC_OP_SEND_STATUS_FROM_SERVER;
  ops[0].data.send_status_from_server.status = status_code;
  ops[0].data.send_status_from_server.status_details = &status_details_slice;
  grpcwrap_metadata_array_move(
      &(ctx->send_status_from_server.trailing_metadata), trailing_metadata);
  ops[0].data.send_status_from_server.trailing_metadata_count =
      ctx->send_status_from_server.trailing_metadata.count;
  ops[0].data.send_status_from_server.trailing_metadata =
      ctx->send_status_from_server.trailing_metadata.metadata;
  ops[0].flags = 0;
  ops[0].reserved = NULL;
  if (optional_send_buffer) {
    ops[nops].op = GRPC_OP_SEND_MESSAGE;
    ctx->send_message =
        string_to_byte_buffer(optional_send_buffer, optional_send_buffer_len);
    ops[nops].data.send_message.send_message = ctx->send_message;
    ops[nops].flags = write_flags;
    ops[nops].reserved = NULL;
    nops++;
  }
  if (send_empty_initial_metadata) {
    ops[nops].op = GRPC_OP_SEND_INITIAL_METADATA;
    ops[nops].flags = 0;
    ops[nops].reserved = NULL;
    nops++;
  }
  grpc_call_error ret = grpc_call_start_batch(call, ops, nops, tag, NULL);
  grpc_slice_unref(status_details_slice);
  return ret;
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_recv_message(
    grpc_call *call, grpcwrap_batch_context *ctx, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[1];
  ops[0].op = GRPC_OP_RECV_MESSAGE;
  ops[0].data.recv_message.recv_message = &(ctx->recv_message);
  ops[0].flags = 0;
  ops[0].reserved = NULL;
  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_start_serverside(
    grpc_call *call, grpcwrap_batch_context *ctx, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[1];
  ops[0].op = GRPC_OP_RECV_CLOSE_ON_SERVER;
  ops[0].data.recv_close_on_server.cancelled =
      (&ctx->recv_close_on_server_cancelled);
  ops[0].flags = 0;
  ops[0].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcwrap_call_send_initial_metadata(
    grpc_call *call, grpcwrap_batch_context *ctx,
    grpc_metadata_array *initial_metadata, void *tag) {
  /* TODO: don't use magic number */
  grpc_op ops[1];
  memset(ops, 0, sizeof(ops));
  ops[0].op = GRPC_OP_SEND_INITIAL_METADATA;
  grpcwrap_metadata_array_move(&(ctx->send_initial_metadata), initial_metadata);
  ops[0].data.send_initial_metadata.count = ctx->send_initial_metadata.count;
  ops[0].data.send_initial_metadata.metadata =
      ctx->send_initial_metadata.metadata;
  ops[0].flags = 0;
  ops[0].reserved = NULL;

  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), tag,
                               NULL);
}

/* Server */

GPR_EXPORT grpc_call_error GPR_CALLTYPE
grpcwrap_server_request_call(grpc_server *server, grpc_completion_queue *cq,
                             grpcwrap_request_call_context *ctx, void *tag) {
  return grpc_server_request_call(server, &(ctx->call), &(ctx->call_details),
                                  &(ctx->request_metadata), cq, cq, tag);
}

/* Security */

static char *default_pem_root_certs = NULL;

static grpc_ssl_roots_override_result override_ssl_roots_handler(
    char **pem_root_certs) {
  if (!default_pem_root_certs) {
    *pem_root_certs = NULL;
    return GRPC_SSL_ROOTS_OVERRIDE_FAIL_PERMANENTLY;
  }
  *pem_root_certs = gpr_strdup(default_pem_root_certs);
  return GRPC_SSL_ROOTS_OVERRIDE_OK;
}

GPR_EXPORT void GPR_CALLTYPE
grpcwrap_override_default_ssl_roots(const char *pem_root_certs) {
  /*
   * This currently wastes ~300kB of memory by keeping a copy of roots
   * in a static variable, but for desktop/server use, the overhead
   * is negligible. In the future, we might want to change the behavior
   * for mobile (e.g. Xamarin).
   */
  default_pem_root_certs = gpr_strdup(pem_root_certs);
  grpc_set_ssl_roots_override_callback(override_ssl_roots_handler);
}

GPR_EXPORT grpc_channel_credentials *GPR_CALLTYPE
grpcwrap_ssl_credentials_create(const char *pem_root_certs,
                                const char *key_cert_pair_cert_chain,
                                const char *key_cert_pair_private_key) {
  grpc_ssl_pem_key_cert_pair key_cert_pair;
  if (key_cert_pair_cert_chain || key_cert_pair_private_key) {
    key_cert_pair.cert_chain = key_cert_pair_cert_chain;
    key_cert_pair.private_key = key_cert_pair_private_key;
    return grpc_ssl_credentials_create(pem_root_certs, &key_cert_pair, NULL);
  } else {
    GPR_ASSERT(!key_cert_pair_cert_chain);
    GPR_ASSERT(!key_cert_pair_private_key);
    return grpc_ssl_credentials_create(pem_root_certs, NULL, NULL);
  }
}

GPR_EXPORT grpc_server_credentials *GPR_CALLTYPE
grpcwrap_ssl_server_credentials_create(
    const char *pem_root_certs, const char **key_cert_pair_cert_chain_array,
    const char **key_cert_pair_private_key_array, size_t num_key_cert_pairs,
    int force_client_auth) {
  size_t i;
  grpc_server_credentials *creds;
  grpc_ssl_pem_key_cert_pair *key_cert_pairs =
      gpr_malloc(sizeof(grpc_ssl_pem_key_cert_pair) * num_key_cert_pairs);
  memset(key_cert_pairs, 0,
         sizeof(grpc_ssl_pem_key_cert_pair) * num_key_cert_pairs);

  for (i = 0; i < num_key_cert_pairs; i++) {
    if (key_cert_pair_cert_chain_array[i] ||
        key_cert_pair_private_key_array[i]) {
      key_cert_pairs[i].cert_chain = key_cert_pair_cert_chain_array[i];
      key_cert_pairs[i].private_key = key_cert_pair_private_key_array[i];
    }
  }
  creds = grpc_ssl_server_credentials_create_ex(
      pem_root_certs, key_cert_pairs, num_key_cert_pairs,
      force_client_auth
          ? GRPC_SSL_REQUEST_AND_REQUIRE_CLIENT_CERTIFICATE_AND_VERIFY
          : GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE,
      NULL);
  gpr_free(key_cert_pairs);
  return creds;
}

/* Metadata credentials plugin */

GPR_EXPORT void GPR_CALLTYPE grpcwrap_metadata_credentials_notify_from_plugin(
    grpc_credentials_plugin_metadata_cb cb, void *user_data,
    grpc_metadata_array *metadata, grpc_status_code status,
    const char *error_details) {
  if (metadata) {
    cb(user_data, metadata->metadata, metadata->count, status, error_details);
  } else {
    cb(user_data, NULL, 0, status, error_details);
  }
}

typedef void(GPR_CALLTYPE *grpcwrap_metadata_interceptor_func)(
    void *state, const char *service_url, const char *method_name,
    grpc_credentials_plugin_metadata_cb cb, void *user_data,
    int32_t is_destroy);

static void grpcwrap_get_metadata_handler(
    void *state, grpc_auth_metadata_context context,
    grpc_credentials_plugin_metadata_cb cb, void *user_data) {
  grpcwrap_metadata_interceptor_func interceptor =
      (grpcwrap_metadata_interceptor_func)(intptr_t)state;
  interceptor(state, context.service_url, context.method_name, cb, user_data,
              0);
}

static void grpcwrap_metadata_credentials_destroy_handler(void *state) {
  grpcwrap_metadata_interceptor_func interceptor =
      (grpcwrap_metadata_interceptor_func)(intptr_t)state;
  interceptor(state, NULL, NULL, NULL, NULL, 1);
}

GPR_EXPORT grpc_call_credentials *GPR_CALLTYPE
grpcwrap_metadata_credentials_create_from_plugin(
    grpcwrap_metadata_interceptor_func metadata_interceptor) {
  grpc_metadata_credentials_plugin plugin;
  plugin.get_metadata = grpcwrap_get_metadata_handler;
  plugin.destroy = grpcwrap_metadata_credentials_destroy_handler;
  plugin.state = (void *)(intptr_t)metadata_interceptor;
  plugin.type = "";
  return grpc_metadata_credentials_create_from_plugin(plugin, NULL);
}