static int verify_jwt_signature(EVP_PKEY *key, const char *alg,
                                grpc_slice signature, grpc_slice signed_data) {
  EVP_MD_CTX *md_ctx = EVP_MD_CTX_create();
  const EVP_MD *md = evp_md_from_alg(alg);
  int result = 0;

  GPR_ASSERT(md != NULL); /* Checked before. */
  if (md_ctx == NULL) {
    gpr_log(GPR_ERROR, "Could not create EVP_MD_CTX.");
    goto end;
  }
  if (EVP_DigestVerifyInit(md_ctx, NULL, md, NULL, key) != 1) {
    gpr_log(GPR_ERROR, "EVP_DigestVerifyInit failed.");
    goto end;
  }
  if (EVP_DigestVerifyUpdate(md_ctx, GRPC_SLICE_START_PTR(signed_data),
                             GRPC_SLICE_LENGTH(signed_data)) != 1) {
    gpr_log(GPR_ERROR, "EVP_DigestVerifyUpdate failed.");
    goto end;
  }
  if (EVP_DigestVerifyFinal(md_ctx, GRPC_SLICE_START_PTR(signature),
                            GRPC_SLICE_LENGTH(signature)) != 1) {
    gpr_log(GPR_ERROR, "JWT signature verification failed.");
    goto end;
  }
  result = 1;

end:
  if (md_ctx != NULL) EVP_MD_CTX_destroy(md_ctx);
  return result;
}

static void test_load_empty_file(void) {
  FILE *tmp = NULL;
  grpc_slice slice;
  grpc_slice slice_with_null_term;
  grpc_error *error;
  char *tmp_name;

  LOG_TEST_NAME("test_load_empty_file");

  tmp = gpr_tmpfile(prefix, &tmp_name);
  GPR_ASSERT(tmp_name != NULL);
  GPR_ASSERT(tmp != NULL);
  fclose(tmp);

  error = grpc_load_file(tmp_name, 0, &slice);
  GPR_ASSERT(error == GRPC_ERROR_NONE);
  GPR_ASSERT(GRPC_SLICE_LENGTH(slice) == 0);

  error = grpc_load_file(tmp_name, 1, &slice_with_null_term);
  GPR_ASSERT(error == GRPC_ERROR_NONE);
  GPR_ASSERT(GRPC_SLICE_LENGTH(slice_with_null_term) == 1);
  GPR_ASSERT(GRPC_SLICE_START_PTR(slice_with_null_term)[0] == 0);

  remove(tmp_name);
  gpr_free(tmp_name);
  grpc_slice_unref(slice);
  grpc_slice_unref(slice_with_null_term);
}

static void test_load_small_file(void) {
  FILE *tmp = NULL;
  grpc_slice slice;
  grpc_slice slice_with_null_term;
  grpc_error *error;
  char *tmp_name;
  const char *blah = "blah";

  LOG_TEST_NAME("test_load_small_file");

  tmp = gpr_tmpfile(prefix, &tmp_name);
  GPR_ASSERT(tmp_name != NULL);
  GPR_ASSERT(tmp != NULL);
  GPR_ASSERT(fwrite(blah, 1, strlen(blah), tmp) == strlen(blah));
  fclose(tmp);

  error = grpc_load_file(tmp_name, 0, &slice);
  GPR_ASSERT(error == GRPC_ERROR_NONE);
  GPR_ASSERT(GRPC_SLICE_LENGTH(slice) == strlen(blah));
  GPR_ASSERT(!memcmp(GRPC_SLICE_START_PTR(slice), blah, strlen(blah)));

  error = grpc_load_file(tmp_name, 1, &slice_with_null_term);
  GPR_ASSERT(error == GRPC_ERROR_NONE);
  GPR_ASSERT(GRPC_SLICE_LENGTH(slice_with_null_term) == (strlen(blah) + 1));
  GPR_ASSERT(strcmp((const char *)GRPC_SLICE_START_PTR(slice_with_null_term),
                    blah) == 0);

  remove(tmp_name);
  gpr_free(tmp_name);
  grpc_slice_unref(slice);
  grpc_slice_unref(slice_with_null_term);
}

static size_t md_ary_datasize(const void *p) {
  const grpc_metadata_array *const ary = (grpc_metadata_array *)p;
  size_t i, datasize = sizeof(grpc_metadata_array);
  for (i = 0; i < ary->count; ++i) {
    const grpc_metadata *const md = &ary->metadata[i];
    datasize += GRPC_SLICE_LENGTH(md->key);
    datasize += GRPC_SLICE_LENGTH(md->value);
  }
  datasize += ary->capacity * sizeof(grpc_metadata);
  return datasize;
}

static size_t count_slices(grpc_slice *slices, size_t nslices,
                           int *current_data) {
  size_t num_bytes = 0;
  unsigned i, j;
  unsigned char *buf;
  for (i = 0; i < nslices; ++i) {
    buf = GRPC_SLICE_START_PTR(slices[i]);
    for (j = 0; j < GRPC_SLICE_LENGTH(slices[i]); ++j) {
      GPR_ASSERT(buf[j] == *current_data);
      *current_data = (*current_data + 1) % 256;
    }
    num_bytes += GRPC_SLICE_LENGTH(slices[i]);
  }
  return num_bytes;
}

void grpc_split_slices(grpc_slice_split_mode mode, grpc_slice *src_slices,
                       size_t src_slice_count, grpc_slice **dst_slices,
                       size_t *dst_slice_count) {
  size_t i, j;
  size_t length;

  switch (mode) {
    case GRPC_SLICE_SPLIT_IDENTITY:
      *dst_slice_count = src_slice_count;
      *dst_slices = gpr_malloc(sizeof(grpc_slice) * src_slice_count);
      for (i = 0; i < src_slice_count; i++) {
        (*dst_slices)[i] = src_slices[i];
        grpc_slice_ref((*dst_slices)[i]);
      }
      break;
    case GRPC_SLICE_SPLIT_MERGE_ALL:
      *dst_slice_count = 1;
      length = 0;
      for (i = 0; i < src_slice_count; i++) {
        length += GRPC_SLICE_LENGTH(src_slices[i]);
      }
      *dst_slices = gpr_malloc(sizeof(grpc_slice));
      **dst_slices = grpc_slice_malloc(length);
      length = 0;
      for (i = 0; i < src_slice_count; i++) {
        memcpy(GRPC_SLICE_START_PTR(**dst_slices) + length,
               GRPC_SLICE_START_PTR(src_slices[i]),
               GRPC_SLICE_LENGTH(src_slices[i]));
        length += GRPC_SLICE_LENGTH(src_slices[i]);
      }
      break;
    case GRPC_SLICE_SPLIT_ONE_BYTE:
      length = 0;
      for (i = 0; i < src_slice_count; i++) {
        length += GRPC_SLICE_LENGTH(src_slices[i]);
      }
      *dst_slice_count = length;
      *dst_slices = gpr_malloc(sizeof(grpc_slice) * length);
      length = 0;
      for (i = 0; i < src_slice_count; i++) {
        for (j = 0; j < GRPC_SLICE_LENGTH(src_slices[i]); j++) {
          (*dst_slices)[length] = grpc_slice_sub(src_slices[i], j, j + 1);
          length++;
        }
      }
      break;
  }
}

static void test_load_big_file(void) {
  FILE *tmp = NULL;
  grpc_slice slice;
  grpc_error *error;
  char *tmp_name;
  static const size_t buffer_size = 124631;
  unsigned char *buffer = gpr_malloc(buffer_size);
  unsigned char *current;
  size_t i;

  LOG_TEST_NAME("test_load_big_file");

  memset(buffer, 42, buffer_size);

  tmp = gpr_tmpfile(prefix, &tmp_name);
  GPR_ASSERT(tmp != NULL);
  GPR_ASSERT(tmp_name != NULL);
  GPR_ASSERT(fwrite(buffer, 1, buffer_size, tmp) == buffer_size);
  fclose(tmp);

  error = grpc_load_file(tmp_name, 0, &slice);
  GPR_ASSERT(error == GRPC_ERROR_NONE);
  GPR_ASSERT(GRPC_SLICE_LENGTH(slice) == buffer_size);
  current = GRPC_SLICE_START_PTR(slice);
  for (i = 0; i < buffer_size; i++) {
    GPR_ASSERT(current[i] == 42);
  }

  remove(tmp_name);
  gpr_free(tmp_name);
  grpc_slice_unref(slice);
  gpr_free(buffer);
}

int grpc_slice_rchr(grpc_slice s, char c) {
  const char *b = (const char *)GRPC_SLICE_START_PTR(s);
  int i;
  for (i = (int)GRPC_SLICE_LENGTH(s) - 1; i != -1 && b[i] != c; i--)
    ;
  return i;
}

// Callback to read the HTTP CONNECT request.
// TODO(roth): Technically, for any of the failure modes handled by this
// function, we should handle the error by returning an HTTP response to
// the client indicating that the request failed.  However, for the purposes
// of this test code, it's fine to pretend this is a client-side error,
// which will cause the client connection to be dropped.
static void on_read_request_done(grpc_exec_ctx* exec_ctx, void* arg,
                                 grpc_error* error) {
  proxy_connection* conn = arg;
  if (error != GRPC_ERROR_NONE) {
    proxy_connection_failed(exec_ctx, conn, true /* is_client */,
                            "HTTP proxy read request", error);
    return;
  }
  // Read request and feed it to the parser.
  for (size_t i = 0; i < conn->client_read_buffer.count; ++i) {
    if (GRPC_SLICE_LENGTH(conn->client_read_buffer.slices[i]) > 0) {
      error = grpc_http_parser_parse(&conn->http_parser,
                                     conn->client_read_buffer.slices[i], NULL);
      if (error != GRPC_ERROR_NONE) {
        proxy_connection_failed(exec_ctx, conn, true /* is_client */,
                                "HTTP proxy request parse", error);
        GRPC_ERROR_UNREF(error);
        return;
      }
    }
  }
  grpc_slice_buffer_reset_and_unref(&conn->client_read_buffer);
  // If we're not done reading the request, read more data.
  if (conn->http_parser.state != GRPC_HTTP_BODY) {
    grpc_endpoint_read(exec_ctx, conn->client_endpoint,
                       &conn->client_read_buffer, &conn->on_read_request_done);
    return;
  }
  // Make sure we got a CONNECT request.
  if (strcmp(conn->http_request.method, "CONNECT") != 0) {
    char* msg;
    gpr_asprintf(&msg, "HTTP proxy got request method %s",
                 conn->http_request.method);
    error = GRPC_ERROR_CREATE(msg);
    gpr_free(msg);
    proxy_connection_failed(exec_ctx, conn, true /* is_client */,
                            "HTTP proxy read request", error);
    GRPC_ERROR_UNREF(error);
    return;
  }
  // Resolve address.
  grpc_resolved_addresses* resolved_addresses = NULL;
  error = grpc_blocking_resolve_address(conn->http_request.path, "80",
                                        &resolved_addresses);
  if (error != GRPC_ERROR_NONE) {
    proxy_connection_failed(exec_ctx, conn, true /* is_client */,
                            "HTTP proxy DNS lookup", error);
    GRPC_ERROR_UNREF(error);
    return;
  }
  GPR_ASSERT(resolved_addresses->naddrs >= 1);
  // Connect to requested address.
  // The connection callback inherits our reference to conn.
  const gpr_timespec deadline = gpr_time_add(
      gpr_now(GPR_CLOCK_MONOTONIC), gpr_time_from_seconds(10, GPR_TIMESPAN));
  grpc_tcp_client_connect(exec_ctx, &conn->on_server_connect_done,
                          &conn->server_endpoint, conn->pollset_set, NULL,
                          &resolved_addresses->addrs[0], deadline);
  grpc_resolved_addresses_destroy(resolved_addresses);
}

/*
 * Gets the next slice from recv_message byte buffer.
 * Returns 1 if a slice was get successfully, 0 if there are no more slices to
 * read. Set slice_len to the length of the slice and the slice_data_ptr to
 * point to slice's data. Caller must ensure that the byte buffer being read
 * from stays alive as long as the data of the slice are being accessed
 * (grpc_byte_buffer_reader_peek method is used internally)
 *
 * Remarks:
 * Slices can only be iterated once.
 * Initializes recv_message_buffer_reader if it was not initialized yet.
 */
GPR_EXPORT int GPR_CALLTYPE
grpcsharp_batch_context_recv_message_next_slice_peek(
    grpcsharp_batch_context* ctx, size_t* slice_len, uint8_t** slice_data_ptr) {
  *slice_len = 0;
  *slice_data_ptr = NULL;

  if (!ctx->recv_message) {
    return 0;
  }

  if (!ctx->recv_message_reader) {
    ctx->recv_message_reader = &ctx->reserved_recv_message_reader;
    GPR_ASSERT(grpc_byte_buffer_reader_init(ctx->recv_message_reader,
                                            ctx->recv_message));
  }

  grpc_slice* slice_ptr;
  if (!grpc_byte_buffer_reader_peek(ctx->recv_message_reader, &slice_ptr)) {
    return 0;
  }

  /* recv_message buffer must not be deleted before all the data is read */
  *slice_len = GRPC_SLICE_LENGTH(*slice_ptr);
  *slice_data_ptr = GRPC_SLICE_START_PTR(*slice_ptr);
  return 1;
}

GPR_EXPORT const char* GPR_CALLTYPE
grpcsharp_batch_context_recv_status_on_client_details(
    const grpcsharp_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);
}

grpc_error *grpc_chttp2_data_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
                                          grpc_chttp2_transport *t,
                                          grpc_chttp2_stream *s,
                                          grpc_slice slice, int is_last) {
  /* grpc_error *error = parse_inner_buffer(exec_ctx, p, t, s, slice); */
  s->stats.incoming.framing_bytes += GRPC_SLICE_LENGTH(slice);
  if (!s->pending_byte_stream) {
    grpc_slice_ref_internal(slice);
    grpc_slice_buffer_add(&s->frame_storage, slice);
    grpc_chttp2_maybe_complete_recv_message(exec_ctx, t, s);
  } else if (s->on_next) {
    GPR_ASSERT(s->frame_storage.length == 0);
    grpc_slice_ref_internal(slice);
    grpc_slice_buffer_add(&s->unprocessed_incoming_frames_buffer, slice);
    grpc_closure_sched(exec_ctx, s->on_next, GRPC_ERROR_NONE);
    s->on_next = NULL;
  } else {
    grpc_slice_ref_internal(slice);
    grpc_slice_buffer_add(&s->frame_storage, slice);
  }

  if (is_last && s->received_last_frame) {
    grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, false,
                                   GRPC_ERROR_NONE);
  }

  return GRPC_ERROR_NONE;
}

/* Takes ownership of creds_path if not NULL. */
static grpc_error *create_default_creds_from_path(
    grpc_exec_ctx *exec_ctx, char *creds_path, grpc_call_credentials **creds) {
  grpc_json *json = NULL;
  grpc_auth_json_key key;
  grpc_auth_refresh_token token;
  grpc_call_credentials *result = NULL;
  grpc_slice creds_data = grpc_empty_slice();
  grpc_error *error = GRPC_ERROR_NONE;
  if (creds_path == NULL) {
    error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("creds_path unset");
    goto end;
  }
  error = grpc_load_file(creds_path, 0, &creds_data);
  if (error != GRPC_ERROR_NONE) {
    goto end;
  }
  json = grpc_json_parse_string_with_len(
      (char *)GRPC_SLICE_START_PTR(creds_data), GRPC_SLICE_LENGTH(creds_data));
  if (json == NULL) {
    error = grpc_error_set_str(
        GRPC_ERROR_CREATE_FROM_STATIC_STRING("Failed to parse JSON"),
        GRPC_ERROR_STR_RAW_BYTES, grpc_slice_ref_internal(creds_data));
    goto end;
  }

  /* First, try an auth json key. */
  key = grpc_auth_json_key_create_from_json(json);
  if (grpc_auth_json_key_is_valid(&key)) {
    result =
        grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
            exec_ctx, key, grpc_max_auth_token_lifetime());
    if (result == NULL) {
      error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
          "grpc_service_account_jwt_access_credentials_create_from_auth_json_"
          "key failed");
    }
    goto end;
  }

  /* Then try a refresh token if the auth json key was invalid. */
  token = grpc_auth_refresh_token_create_from_json(json);
  if (grpc_auth_refresh_token_is_valid(&token)) {
    result =
        grpc_refresh_token_credentials_create_from_auth_refresh_token(token);
    if (result == NULL) {
      error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
          "grpc_refresh_token_credentials_create_from_auth_refresh_token "
          "failed");
    }
    goto end;
  }

end:
  GPR_ASSERT((result == NULL) + (error == GRPC_ERROR_NONE) == 1);
  if (creds_path != NULL) gpr_free(creds_path);
  grpc_slice_unref_internal(exec_ctx, creds_data);
  if (json != NULL) grpc_json_destroy(json);
  *creds = result;
  return error;
}

static void win_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                     grpc_slice_buffer *read_slices, grpc_closure *cb) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  grpc_winsocket *handle = tcp->socket;
  grpc_winsocket_callback_info *info = &handle->read_info;
  int status;
  DWORD bytes_read = 0;
  DWORD flags = 0;
  WSABUF buffer;

  if (tcp->shutting_down) {
    GRPC_CLOSURE_SCHED(
        exec_ctx, cb,
        GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
            "TCP socket is shutting down", &tcp->shutdown_error, 1));
    return;
  }

  tcp->read_cb = cb;
  tcp->read_slices = read_slices;
  grpc_slice_buffer_reset_and_unref_internal(exec_ctx, read_slices);

  tcp->read_slice = GRPC_SLICE_MALLOC(8192);

  buffer.len = (ULONG)GRPC_SLICE_LENGTH(
      tcp->read_slice);  // we know slice size fits in 32bit.
  buffer.buf = (char *)GRPC_SLICE_START_PTR(tcp->read_slice);

  TCP_REF(tcp, "read");

  /* First let's try a synchronous, non-blocking read. */
  status =
      WSARecv(tcp->socket->socket, &buffer, 1, &bytes_read, &flags, NULL, NULL);
  info->wsa_error = status == 0 ? 0 : WSAGetLastError();

  /* Did we get data immediately ? Yay. */
  if (info->wsa_error != WSAEWOULDBLOCK) {
    info->bytes_transfered = bytes_read;
    GRPC_CLOSURE_SCHED(exec_ctx, &tcp->on_read, GRPC_ERROR_NONE);
    return;
  }

  /* Otherwise, let's retry, by queuing a read. */
  memset(&tcp->socket->read_info.overlapped, 0, sizeof(OVERLAPPED));
  status = WSARecv(tcp->socket->socket, &buffer, 1, &bytes_read, &flags,
                   &info->overlapped, NULL);

  if (status != 0) {
    int wsa_error = WSAGetLastError();
    if (wsa_error != WSA_IO_PENDING) {
      info->wsa_error = wsa_error;
      GRPC_CLOSURE_SCHED(exec_ctx, &tcp->on_read,
                         GRPC_WSA_ERROR(info->wsa_error, "WSARecv"));
      return;
    }
  }

  grpc_socket_notify_on_read(exec_ctx, tcp->socket, &tcp->on_read);
}

static void continue_send_message(grpc_exec_ctx *exec_ctx,
                                  grpc_call_element *elem) {
  call_data *calld = elem->call_data;
  uint8_t *wrptr = calld->payload_bytes;
  while (grpc_byte_stream_next(exec_ctx, calld->send_op.send_message,
                               &calld->incoming_slice, ~(size_t)0,
                               &calld->got_slice)) {
    memcpy(wrptr, GRPC_SLICE_START_PTR(calld->incoming_slice),
           GRPC_SLICE_LENGTH(calld->incoming_slice));
    wrptr += GRPC_SLICE_LENGTH(calld->incoming_slice);
    grpc_slice_buffer_add(&calld->slices, calld->incoming_slice);
    if (calld->send_length == calld->slices.length) {
      calld->send_message_blocked = false;
      break;
    }
  }
}

grpc_slice grpc_slice_merge(grpc_slice *slices, size_t nslices) {
  uint8_t *out = NULL;
  size_t length = 0;
  size_t capacity = 0;
  size_t i;

  for (i = 0; i < nslices; i++) {
    if (GRPC_SLICE_LENGTH(slices[i]) + length > capacity) {
      capacity = GPR_MAX(capacity * 2, GRPC_SLICE_LENGTH(slices[i]) + length);
      out = gpr_realloc(out, capacity);
    }
    memcpy(out + length, GRPC_SLICE_START_PTR(slices[i]),
           GRPC_SLICE_LENGTH(slices[i]));
    length += GRPC_SLICE_LENGTH(slices[i]);
  }

  return grpc_slice_new(out, length, gpr_free);
}

static void emit_lithdr_noidx_v(grpc_chttp2_hpack_compressor *c,
                                grpc_mdelem elem, framer_state *st) {
  uint32_t len_key = (uint32_t)GRPC_SLICE_LENGTH(GRPC_MDKEY(elem));
  uint8_t huffman_prefix;
  grpc_slice value_slice = get_wire_value(elem, &huffman_prefix);
  uint32_t len_val = (uint32_t)GRPC_SLICE_LENGTH(value_slice);
  uint32_t len_key_len = GRPC_CHTTP2_VARINT_LENGTH(len_key, 1);
  uint32_t len_val_len = GRPC_CHTTP2_VARINT_LENGTH(len_val, 1);
  GPR_ASSERT(len_key <= UINT32_MAX);
  GPR_ASSERT(GRPC_SLICE_LENGTH(value_slice) <= UINT32_MAX);
  *add_tiny_header_data(st, 1) = 0x00;
  GRPC_CHTTP2_WRITE_VARINT(len_key, 1, 0x00,
                           add_tiny_header_data(st, len_key_len), len_key_len);
  add_header_data(st, grpc_slice_ref_internal(GRPC_MDKEY(elem)));
  GRPC_CHTTP2_WRITE_VARINT(len_val, 1, huffman_prefix,
                           add_tiny_header_data(st, len_val_len), len_val_len);
  add_header_data(st, value_slice);
}

static void uv_endpoint_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                              grpc_slice_buffer *write_slices,
                              grpc_closure *cb) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  uv_buf_t *buffers;
  unsigned int buffer_count;
  unsigned int i;
  grpc_slice *slice;
  uv_write_t *write_req;

  if (grpc_tcp_trace) {
    size_t j;

    for (j = 0; j < write_slices->count; j++) {
      char *data = grpc_dump_slice(write_slices->slices[j],
                                   GPR_DUMP_HEX | GPR_DUMP_ASCII);
      gpr_log(GPR_DEBUG, "WRITE %p (peer=%s): %s", tcp, tcp->peer_string, data);
      gpr_free(data);
    }
  }

  if (tcp->shutting_down) {
    grpc_closure_sched(exec_ctx, cb,
                       GRPC_ERROR_CREATE("TCP socket is shutting down"));
    return;
  }

  GPR_ASSERT(tcp->write_cb == NULL);
  tcp->write_slices = write_slices;
  GPR_ASSERT(tcp->write_slices->count <= UINT_MAX);
  if (tcp->write_slices->count == 0) {
    // No slices means we don't have to do anything,
    // and libuv doesn't like empty writes
    grpc_closure_sched(exec_ctx, cb, GRPC_ERROR_NONE);
    return;
  }

  tcp->write_cb = cb;
  buffer_count = (unsigned int)tcp->write_slices->count;
  buffers = gpr_malloc(sizeof(uv_buf_t) * buffer_count);
  grpc_resource_user_alloc(exec_ctx, tcp->resource_user,
                           sizeof(uv_buf_t) * buffer_count, NULL);
  for (i = 0; i < buffer_count; i++) {
    slice = &tcp->write_slices->slices[i];
    buffers[i].base = (char *)GRPC_SLICE_START_PTR(*slice);
    buffers[i].len = GRPC_SLICE_LENGTH(*slice);
  }
  tcp->write_buffers = buffers;
  write_req = &tcp->write_req;
  write_req->data = tcp;
  TCP_REF(tcp, "write");
  // TODO(murgatroid99): figure out what the return value here means
  uv_write(write_req, (uv_stream_t *)tcp->handle, buffers, buffer_count,
           write_callback);
}

int grpc_slice_slice(grpc_slice haystack, grpc_slice needle) {
  size_t haystack_len = GRPC_SLICE_LENGTH(haystack);
  const uint8_t *haystack_bytes = GRPC_SLICE_START_PTR(haystack);
  size_t needle_len = GRPC_SLICE_LENGTH(needle);
  const uint8_t *needle_bytes = GRPC_SLICE_START_PTR(needle);

  if (haystack_len == 0 || needle_len == 0) return -1;
  if (haystack_len < needle_len) return -1;
  if (haystack_len == needle_len)
    return grpc_slice_eq(haystack, needle) ? 0 : -1;
  if (needle_len == 1) return grpc_slice_chr(haystack, (char)*needle_bytes);

  const uint8_t *last = haystack_bytes + haystack_len - needle_len;
  for (const uint8_t *cur = haystack_bytes; cur != last; ++cur) {
    if (0 == memcmp(cur, needle_bytes, needle_len)) {
      return (int)(cur - haystack_bytes);
    }
  }
  return -1;
}

static void alloc_uv_buf(uv_handle_t *handle, size_t suggested_size,
                         uv_buf_t *buf) {
  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
  grpc_tcp *tcp = handle->data;
  (void)suggested_size;
  tcp->read_slice = grpc_resource_user_slice_malloc(
      &exec_ctx, tcp->resource_user, GRPC_TCP_DEFAULT_READ_SLICE_SIZE);
  buf->base = (char *)GRPC_SLICE_START_PTR(tcp->read_slice);
  buf->len = GRPC_SLICE_LENGTH(tcp->read_slice);
  grpc_exec_ctx_finish(&exec_ctx);
}