| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * 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, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include <grpc/support/port_platform.h> |
| |
| #include "src/core/ext/filters/http/server/http_server_filter.h" |
| |
| #include <string.h> |
| |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/log.h> |
| |
| #include "src/core/lib/channel/channel_args.h" |
| #include "src/core/lib/gprpp/manual_constructor.h" |
| #include "src/core/lib/profiling/timers.h" |
| #include "src/core/lib/slice/b64.h" |
| #include "src/core/lib/slice/percent_encoding.h" |
| #include "src/core/lib/slice/slice_internal.h" |
| #include "src/core/lib/slice/slice_string_helpers.h" |
| #include "src/core/lib/transport/static_metadata.h" |
| |
| #define EXPECTED_CONTENT_TYPE "application/grpc" |
| #define EXPECTED_CONTENT_TYPE_LENGTH (sizeof(EXPECTED_CONTENT_TYPE) - 1) |
| |
| static void hs_recv_initial_metadata_ready(void* user_data, |
| grpc_error_handle err); |
| static void hs_recv_trailing_metadata_ready(void* user_data, |
| grpc_error_handle err); |
| static void hs_recv_message_ready(void* user_data, grpc_error_handle err); |
| |
| namespace { |
| |
| struct call_data { |
| call_data(grpc_call_element* elem, const grpc_call_element_args& args) |
| : call_combiner(args.call_combiner) { |
| GRPC_CLOSURE_INIT(&recv_initial_metadata_ready, |
| hs_recv_initial_metadata_ready, elem, |
| grpc_schedule_on_exec_ctx); |
| GRPC_CLOSURE_INIT(&recv_message_ready, hs_recv_message_ready, elem, |
| grpc_schedule_on_exec_ctx); |
| GRPC_CLOSURE_INIT(&recv_trailing_metadata_ready, |
| hs_recv_trailing_metadata_ready, elem, |
| grpc_schedule_on_exec_ctx); |
| } |
| |
| ~call_data() { |
| GRPC_ERROR_UNREF(recv_initial_metadata_ready_error); |
| if (have_read_stream) { |
| read_stream->Orphan(); |
| } |
| } |
| |
| grpc_core::CallCombiner* call_combiner; |
| |
| // Outgoing headers to add to send_initial_metadata. |
| grpc_linked_mdelem status; |
| grpc_linked_mdelem content_type; |
| |
| // If we see the recv_message contents in the GET query string, we |
| // store it here. |
| grpc_core::ManualConstructor<grpc_core::SliceBufferByteStream> read_stream; |
| bool have_read_stream = false; |
| |
| // State for intercepting recv_initial_metadata. |
| grpc_closure recv_initial_metadata_ready; |
| grpc_error_handle recv_initial_metadata_ready_error = GRPC_ERROR_NONE; |
| grpc_closure* original_recv_initial_metadata_ready; |
| grpc_metadata_batch* recv_initial_metadata = nullptr; |
| uint32_t* recv_initial_metadata_flags; |
| bool seen_recv_initial_metadata_ready = false; |
| |
| // State for intercepting recv_message. |
| grpc_closure* original_recv_message_ready; |
| grpc_closure recv_message_ready; |
| grpc_core::OrphanablePtr<grpc_core::ByteStream>* recv_message; |
| bool seen_recv_message_ready = false; |
| |
| // State for intercepting recv_trailing_metadata |
| grpc_closure recv_trailing_metadata_ready; |
| grpc_closure* original_recv_trailing_metadata_ready; |
| grpc_error_handle recv_trailing_metadata_ready_error; |
| bool seen_recv_trailing_metadata_ready = false; |
| }; |
| |
| struct channel_data { |
| bool surface_user_agent; |
| }; |
| |
| } // namespace |
| |
| static grpc_error_handle hs_filter_outgoing_metadata(grpc_metadata_batch* b) { |
| if (b->legacy_index()->named.grpc_message != nullptr) { |
| grpc_slice pct_encoded_msg = grpc_core::PercentEncodeSlice( |
| GRPC_MDVALUE(b->legacy_index()->named.grpc_message->md), |
| grpc_core::PercentEncodingType::Compatible); |
| if (grpc_slice_is_equivalent( |
| pct_encoded_msg, |
| GRPC_MDVALUE(b->legacy_index()->named.grpc_message->md))) { |
| grpc_slice_unref_internal(pct_encoded_msg); |
| } else { |
| grpc_metadata_batch_set_value(b->legacy_index()->named.grpc_message, |
| pct_encoded_msg); |
| } |
| } |
| return GRPC_ERROR_NONE; |
| } |
| |
| static void hs_add_error(const char* error_name, grpc_error_handle* cumulative, |
| grpc_error_handle new_err) { |
| if (new_err == GRPC_ERROR_NONE) return; |
| if (*cumulative == GRPC_ERROR_NONE) { |
| *cumulative = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_name); |
| } |
| *cumulative = grpc_error_add_child(*cumulative, new_err); |
| } |
| |
| // Metadata equality within this filter leverages the fact that the sender was |
| // likely using the gRPC chttp2 transport, in which case the encoder would emit |
| // indexed values, in which case the local hpack parser would intern the |
| // relevant metadata, allowing a simple pointer comparison. |
| // |
| // That said, if the header was transmitted sans indexing/encoding, we still |
| // need to do the right thing. |
| // |
| // Assumptions: |
| // 1) The keys for a and b_static must match |
| // 2) b_static must be a statically allocated metadata object. |
| // 3) It is assumed that the remote end is indexing, but not necessary. |
| // TODO(arjunroy): Revisit this method when grpc_mdelem is strongly typed. |
| static bool md_strict_equal(grpc_mdelem a, grpc_mdelem b_static) { |
| // Hpack encoder on the remote side should emit indexed values, in which case |
| // hpack parser on this end should pick up interned values, in which case the |
| // pointer comparison alone is enough. |
| // |
| if (GPR_LIKELY(GRPC_MDELEM_IS_INTERNED(a))) { |
| return a.payload == b_static.payload; |
| } else { |
| return grpc_slice_eq_static_interned(GRPC_MDVALUE(a), |
| GRPC_MDVALUE(b_static)); |
| } |
| } |
| |
| static grpc_error_handle hs_filter_incoming_metadata(grpc_call_element* elem, |
| grpc_metadata_batch* b) { |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| grpc_error_handle error = GRPC_ERROR_NONE; |
| static const char* error_name = "Failed processing incoming headers"; |
| |
| if (b->legacy_index()->named.method != nullptr) { |
| if (md_strict_equal(b->legacy_index()->named.method->md, |
| GRPC_MDELEM_METHOD_POST)) { |
| *calld->recv_initial_metadata_flags &= |
| ~(GRPC_INITIAL_METADATA_CACHEABLE_REQUEST | |
| GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST); |
| } else if (md_strict_equal(b->legacy_index()->named.method->md, |
| GRPC_MDELEM_METHOD_PUT)) { |
| *calld->recv_initial_metadata_flags &= |
| ~GRPC_INITIAL_METADATA_CACHEABLE_REQUEST; |
| *calld->recv_initial_metadata_flags |= |
| GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST; |
| } else if (md_strict_equal(b->legacy_index()->named.method->md, |
| GRPC_MDELEM_METHOD_GET)) { |
| *calld->recv_initial_metadata_flags |= |
| GRPC_INITIAL_METADATA_CACHEABLE_REQUEST; |
| *calld->recv_initial_metadata_flags &= |
| ~GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST; |
| } else { |
| hs_add_error(error_name, &error, |
| grpc_attach_md_to_error( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Bad header"), |
| b->legacy_index()->named.method->md)); |
| } |
| b->Remove(GRPC_BATCH_METHOD); |
| } else { |
| hs_add_error(error_name, &error, |
| grpc_error_set_str( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing header"), |
| GRPC_ERROR_STR_KEY, ":method")); |
| } |
| |
| auto te = b->Take(grpc_core::TeMetadata()); |
| if (te == grpc_core::TeMetadata::kTrailers) { |
| // Do nothing, ok. |
| } else if (!te.has_value()) { |
| hs_add_error(error_name, &error, |
| grpc_error_set_str( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing header"), |
| GRPC_ERROR_STR_KEY, "te")); |
| } else { |
| hs_add_error(error_name, &error, |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Bad te header")); |
| } |
| |
| if (b->legacy_index()->named.scheme != nullptr) { |
| if (!md_strict_equal(b->legacy_index()->named.scheme->md, |
| GRPC_MDELEM_SCHEME_HTTP) && |
| !md_strict_equal(b->legacy_index()->named.scheme->md, |
| GRPC_MDELEM_SCHEME_HTTPS) && |
| !grpc_mdelem_static_value_eq(b->legacy_index()->named.scheme->md, |
| GRPC_MDELEM_SCHEME_GRPC)) { |
| hs_add_error(error_name, &error, |
| grpc_attach_md_to_error( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Bad header"), |
| b->legacy_index()->named.scheme->md)); |
| } |
| b->Remove(GRPC_BATCH_SCHEME); |
| } else { |
| hs_add_error(error_name, &error, |
| grpc_error_set_str( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing header"), |
| GRPC_ERROR_STR_KEY, ":scheme")); |
| } |
| |
| if (b->legacy_index()->named.content_type != nullptr) { |
| if (!grpc_mdelem_static_value_eq( |
| b->legacy_index()->named.content_type->md, |
| GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC)) { |
| if (grpc_slice_buf_start_eq( |
| GRPC_MDVALUE(b->legacy_index()->named.content_type->md), |
| EXPECTED_CONTENT_TYPE, EXPECTED_CONTENT_TYPE_LENGTH) && |
| (GRPC_SLICE_START_PTR(GRPC_MDVALUE( |
| b->legacy_index() |
| ->named.content_type->md))[EXPECTED_CONTENT_TYPE_LENGTH] == |
| '+' || |
| GRPC_SLICE_START_PTR(GRPC_MDVALUE( |
| b->legacy_index() |
| ->named.content_type->md))[EXPECTED_CONTENT_TYPE_LENGTH] == |
| ';')) { |
| /* Although the C implementation doesn't (currently) generate them, |
| any custom +-suffix is explicitly valid. */ |
| /* TODO(klempner): We should consider preallocating common values such |
| as +proto or +json, or at least stashing them if we see them. */ |
| /* TODO(klempner): Should we be surfacing this to application code? */ |
| } else { |
| /* TODO(klempner): We're currently allowing this, but we shouldn't |
| see it without a proxy so log for now. */ |
| char* val = grpc_dump_slice( |
| GRPC_MDVALUE(b->legacy_index()->named.content_type->md), |
| GPR_DUMP_ASCII); |
| gpr_log(GPR_INFO, "Unexpected content-type '%s'", val); |
| gpr_free(val); |
| } |
| } |
| b->Remove(GRPC_BATCH_CONTENT_TYPE); |
| } |
| |
| if (b->legacy_index()->named.path == nullptr) { |
| hs_add_error(error_name, &error, |
| grpc_error_set_str( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing header"), |
| GRPC_ERROR_STR_KEY, ":path")); |
| } else if (*calld->recv_initial_metadata_flags & |
| GRPC_INITIAL_METADATA_CACHEABLE_REQUEST) { |
| /* We have a cacheable request made with GET verb. The path contains the |
| * query parameter which is base64 encoded request payload. */ |
| const char k_query_separator = '?'; |
| grpc_slice path_slice = GRPC_MDVALUE(b->legacy_index()->named.path->md); |
| uint8_t* path_ptr = GRPC_SLICE_START_PTR(path_slice); |
| size_t path_length = GRPC_SLICE_LENGTH(path_slice); |
| /* offset of the character '?' */ |
| size_t offset = 0; |
| for (offset = 0; offset < path_length && *path_ptr != k_query_separator; |
| path_ptr++, offset++) { |
| } |
| if (offset < path_length) { |
| grpc_slice query_slice = |
| grpc_slice_sub(path_slice, offset + 1, path_length); |
| |
| /* substitute path metadata with just the path (not query) */ |
| grpc_mdelem mdelem_path_without_query = grpc_mdelem_from_slices( |
| GRPC_MDSTR_PATH, grpc_slice_sub(path_slice, 0, offset)); |
| |
| (void)b->Substitute(b->legacy_index()->named.path, |
| mdelem_path_without_query); |
| |
| /* decode payload from query and add to the slice buffer to be returned */ |
| const int k_url_safe = 1; |
| grpc_slice_buffer read_slice_buffer; |
| grpc_slice_buffer_init(&read_slice_buffer); |
| grpc_slice_buffer_add( |
| &read_slice_buffer, |
| grpc_base64_decode_with_len( |
| reinterpret_cast<const char*> GRPC_SLICE_START_PTR(query_slice), |
| GRPC_SLICE_LENGTH(query_slice), k_url_safe)); |
| calld->read_stream.Init(&read_slice_buffer, 0); |
| grpc_slice_buffer_destroy_internal(&read_slice_buffer); |
| calld->have_read_stream = true; |
| grpc_slice_unref_internal(query_slice); |
| } else { |
| gpr_log(GPR_ERROR, "GET request without QUERY"); |
| } |
| } |
| |
| if (b->legacy_index()->named.host != nullptr && |
| b->legacy_index()->named.authority == nullptr) { |
| grpc_linked_mdelem* el = b->legacy_index()->named.host; |
| grpc_mdelem md = GRPC_MDELEM_REF(el->md); |
| b->Remove(el); |
| hs_add_error( |
| error_name, &error, |
| grpc_metadata_batch_add_head( |
| b, el, |
| grpc_mdelem_from_slices(GRPC_MDSTR_AUTHORITY, |
| grpc_slice_ref_internal(GRPC_MDVALUE(md))), |
| GRPC_BATCH_AUTHORITY)); |
| GRPC_MDELEM_UNREF(md); |
| } |
| |
| if (b->legacy_index()->named.authority == nullptr) { |
| hs_add_error(error_name, &error, |
| grpc_error_set_str( |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing header"), |
| GRPC_ERROR_STR_KEY, ":authority")); |
| } |
| |
| channel_data* chand = static_cast<channel_data*>(elem->channel_data); |
| if (!chand->surface_user_agent) { |
| b->Remove(grpc_core::UserAgentMetadata()); |
| } |
| |
| return error; |
| } |
| |
| static void hs_recv_initial_metadata_ready(void* user_data, |
| grpc_error_handle err) { |
| grpc_call_element* elem = static_cast<grpc_call_element*>(user_data); |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| calld->seen_recv_initial_metadata_ready = true; |
| if (err == GRPC_ERROR_NONE) { |
| err = hs_filter_incoming_metadata(elem, calld->recv_initial_metadata); |
| calld->recv_initial_metadata_ready_error = GRPC_ERROR_REF(err); |
| if (calld->seen_recv_message_ready) { |
| // We've already seen the recv_message callback, but we previously |
| // deferred it, so we need to return it here. |
| // Replace the recv_message byte stream if needed. |
| if (calld->have_read_stream) { |
| calld->recv_message->reset(calld->read_stream.get()); |
| calld->have_read_stream = false; |
| } |
| // Re-enter call combiner for original_recv_message_ready, since the |
| // surface code will release the call combiner for each callback it |
| // receives. |
| GRPC_CALL_COMBINER_START( |
| calld->call_combiner, calld->original_recv_message_ready, |
| GRPC_ERROR_REF(err), |
| "resuming recv_message_ready from recv_initial_metadata_ready"); |
| } |
| } else { |
| (void)GRPC_ERROR_REF(err); |
| } |
| if (calld->seen_recv_trailing_metadata_ready) { |
| GRPC_CALL_COMBINER_START(calld->call_combiner, |
| &calld->recv_trailing_metadata_ready, |
| calld->recv_trailing_metadata_ready_error, |
| "resuming hs_recv_trailing_metadata_ready from " |
| "hs_recv_initial_metadata_ready"); |
| } |
| grpc_core::Closure::Run(DEBUG_LOCATION, |
| calld->original_recv_initial_metadata_ready, err); |
| } |
| |
| static void hs_recv_message_ready(void* user_data, grpc_error_handle err) { |
| grpc_call_element* elem = static_cast<grpc_call_element*>(user_data); |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| calld->seen_recv_message_ready = true; |
| if (calld->seen_recv_initial_metadata_ready) { |
| // We've already seen the recv_initial_metadata callback, so |
| // replace the recv_message byte stream if needed and invoke the |
| // original recv_message callback immediately. |
| if (calld->have_read_stream) { |
| calld->recv_message->reset(calld->read_stream.get()); |
| calld->have_read_stream = false; |
| } |
| grpc_core::Closure::Run(DEBUG_LOCATION, calld->original_recv_message_ready, |
| GRPC_ERROR_REF(err)); |
| } else { |
| // We have not yet seen the recv_initial_metadata callback, so we |
| // need to wait to see if this is a GET request. |
| // Note that we release the call combiner here, so that other |
| // callbacks can run. |
| GRPC_CALL_COMBINER_STOP( |
| calld->call_combiner, |
| "pausing recv_message_ready until recv_initial_metadata_ready"); |
| } |
| } |
| |
| static void hs_recv_trailing_metadata_ready(void* user_data, |
| grpc_error_handle err) { |
| grpc_call_element* elem = static_cast<grpc_call_element*>(user_data); |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| if (!calld->seen_recv_initial_metadata_ready) { |
| calld->recv_trailing_metadata_ready_error = GRPC_ERROR_REF(err); |
| calld->seen_recv_trailing_metadata_ready = true; |
| GRPC_CALL_COMBINER_STOP(calld->call_combiner, |
| "deferring hs_recv_trailing_metadata_ready until " |
| "ater hs_recv_initial_metadata_ready"); |
| return; |
| } |
| err = grpc_error_add_child( |
| GRPC_ERROR_REF(err), |
| GRPC_ERROR_REF(calld->recv_initial_metadata_ready_error)); |
| grpc_core::Closure::Run(DEBUG_LOCATION, |
| calld->original_recv_trailing_metadata_ready, err); |
| } |
| |
| static grpc_error_handle hs_mutate_op(grpc_call_element* elem, |
| grpc_transport_stream_op_batch* op) { |
| /* grab pointers to our data from the call element */ |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| |
| if (op->send_initial_metadata) { |
| grpc_error_handle error = GRPC_ERROR_NONE; |
| static const char* error_name = "Failed sending initial metadata"; |
| hs_add_error( |
| error_name, &error, |
| grpc_metadata_batch_add_head( |
| op->payload->send_initial_metadata.send_initial_metadata, |
| &calld->status, GRPC_MDELEM_STATUS_200, GRPC_BATCH_STATUS)); |
| hs_add_error(error_name, &error, |
| grpc_metadata_batch_add_tail( |
| op->payload->send_initial_metadata.send_initial_metadata, |
| &calld->content_type, |
| GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC, |
| GRPC_BATCH_CONTENT_TYPE)); |
| hs_add_error(error_name, &error, |
| hs_filter_outgoing_metadata( |
| op->payload->send_initial_metadata.send_initial_metadata)); |
| if (error != GRPC_ERROR_NONE) return error; |
| } |
| |
| if (op->recv_initial_metadata) { |
| /* substitute our callback for the higher callback */ |
| GPR_ASSERT(op->payload->recv_initial_metadata.recv_flags != nullptr); |
| calld->recv_initial_metadata = |
| op->payload->recv_initial_metadata.recv_initial_metadata; |
| calld->recv_initial_metadata_flags = |
| op->payload->recv_initial_metadata.recv_flags; |
| calld->original_recv_initial_metadata_ready = |
| op->payload->recv_initial_metadata.recv_initial_metadata_ready; |
| op->payload->recv_initial_metadata.recv_initial_metadata_ready = |
| &calld->recv_initial_metadata_ready; |
| } |
| |
| if (op->recv_message) { |
| calld->recv_message = op->payload->recv_message.recv_message; |
| calld->original_recv_message_ready = |
| op->payload->recv_message.recv_message_ready; |
| op->payload->recv_message.recv_message_ready = &calld->recv_message_ready; |
| } |
| |
| if (op->recv_trailing_metadata) { |
| calld->original_recv_trailing_metadata_ready = |
| op->payload->recv_trailing_metadata.recv_trailing_metadata_ready; |
| op->payload->recv_trailing_metadata.recv_trailing_metadata_ready = |
| &calld->recv_trailing_metadata_ready; |
| } |
| |
| if (op->send_trailing_metadata) { |
| grpc_error_handle error = hs_filter_outgoing_metadata( |
| op->payload->send_trailing_metadata.send_trailing_metadata); |
| if (error != GRPC_ERROR_NONE) return error; |
| } |
| |
| return GRPC_ERROR_NONE; |
| } |
| |
| static void hs_start_transport_stream_op_batch( |
| grpc_call_element* elem, grpc_transport_stream_op_batch* op) { |
| GPR_TIMER_SCOPE("hs_start_transport_stream_op_batch", 0); |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| grpc_error_handle error = hs_mutate_op(elem, op); |
| if (error != GRPC_ERROR_NONE) { |
| grpc_transport_stream_op_batch_finish_with_failure(op, error, |
| calld->call_combiner); |
| } else { |
| grpc_call_next_op(elem, op); |
| } |
| } |
| |
| /* Constructor for call_data */ |
| static grpc_error_handle hs_init_call_elem(grpc_call_element* elem, |
| const grpc_call_element_args* args) { |
| new (elem->call_data) call_data(elem, *args); |
| return GRPC_ERROR_NONE; |
| } |
| |
| /* Destructor for call_data */ |
| static void hs_destroy_call_elem(grpc_call_element* elem, |
| const grpc_call_final_info* /*final_info*/, |
| grpc_closure* /*ignored*/) { |
| call_data* calld = static_cast<call_data*>(elem->call_data); |
| calld->~call_data(); |
| } |
| |
| /* Constructor for channel_data */ |
| static grpc_error_handle hs_init_channel_elem(grpc_channel_element* elem, |
| grpc_channel_element_args* args) { |
| channel_data* chand = static_cast<channel_data*>(elem->channel_data); |
| GPR_ASSERT(!args->is_last); |
| chand->surface_user_agent = grpc_channel_arg_get_bool( |
| grpc_channel_args_find(args->channel_args, |
| const_cast<char*>(GRPC_ARG_SURFACE_USER_AGENT)), |
| true); |
| return GRPC_ERROR_NONE; |
| } |
| |
| /* Destructor for channel data */ |
| static void hs_destroy_channel_elem(grpc_channel_element* /*elem*/) {} |
| |
| const grpc_channel_filter grpc_http_server_filter = { |
| hs_start_transport_stream_op_batch, |
| grpc_channel_next_op, |
| sizeof(call_data), |
| hs_init_call_elem, |
| grpc_call_stack_ignore_set_pollset_or_pollset_set, |
| hs_destroy_call_elem, |
| sizeof(channel_data), |
| hs_init_channel_elem, |
| hs_destroy_channel_elem, |
| grpc_channel_next_get_info, |
| "http-server"}; |