src/core/ext/filters/client_channel/http_connect_handshaker.cc - platform/external/grpc-grpc - Git at Google

 /*
  *
  * Copyright 2016 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/client_channel/http_connect_handshaker.h"

 #include <string.h>

 #include "absl/strings/str_cat.h"

 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>

 #include "src/core/ext/filters/client_channel/client_channel.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/sync.h"
 #include "src/core/lib/http/format_request.h"
 #include "src/core/lib/http/parser.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/uri/uri_parser.h"

 namespace grpc_core {

 namespace {

 class HttpConnectHandshaker : public Handshaker {
  public:
   HttpConnectHandshaker();
   void Shutdown(grpc_error* why) override;
   void DoHandshake(grpc_tcp_server_acceptor* acceptor,
                    grpc_closure* on_handshake_done,
                    HandshakerArgs* args) override;
   const char* name() const override { return "http_connect"; }

  private:
   ~HttpConnectHandshaker() override;
   void CleanupArgsForFailureLocked();
   void HandshakeFailedLocked(grpc_error* error);
   static void OnWriteDone(void* arg, grpc_error* error);
   static void OnReadDone(void* arg, grpc_error* error);
   static void OnWriteDoneScheduler(void* arg, grpc_error* error);
   static void OnReadDoneScheduler(void* arg, grpc_error* error);

   Mutex mu_;

   bool is_shutdown_ = false;
   // Endpoint and read buffer to destroy after a shutdown.
   grpc_endpoint* endpoint_to_destroy_ = nullptr;
   grpc_slice_buffer* read_buffer_to_destroy_ = nullptr;

   // State saved while performing the handshake.
   HandshakerArgs* args_ = nullptr;
   grpc_closure* on_handshake_done_ = nullptr;

   // Objects for processing the HTTP CONNECT request and response.
   grpc_slice_buffer write_buffer_;
   grpc_closure request_done_closure_;
   grpc_closure response_read_closure_;
   grpc_http_parser http_parser_;
   grpc_http_response http_response_;
 };

 HttpConnectHandshaker::~HttpConnectHandshaker() {
   if (endpoint_to_destroy_ != nullptr) {
     grpc_endpoint_destroy(endpoint_to_destroy_);
   }
   if (read_buffer_to_destroy_ != nullptr) {
     grpc_slice_buffer_destroy_internal(read_buffer_to_destroy_);
     gpr_free(read_buffer_to_destroy_);
   }
   grpc_slice_buffer_destroy_internal(&write_buffer_);
   grpc_http_parser_destroy(&http_parser_);
   grpc_http_response_destroy(&http_response_);
 }

 // Set args fields to nullptr, saving the endpoint and read buffer for
 // later destruction.
 void HttpConnectHandshaker::CleanupArgsForFailureLocked() {
   endpoint_to_destroy_ = args_->endpoint;
   args_->endpoint = nullptr;
   read_buffer_to_destroy_ = args_->read_buffer;
   args_->read_buffer = nullptr;
   grpc_channel_args_destroy(args_->args);
   args_->args = nullptr;
 }

 // If the handshake failed or we're shutting down, clean up and invoke the
 // callback with the error.
 void HttpConnectHandshaker::HandshakeFailedLocked(grpc_error* error) {
   if (error == GRPC_ERROR_NONE) {
     // If we were shut down after an endpoint operation succeeded but
     // before the endpoint callback was invoked, we need to generate our
     // own error.
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Handshaker shutdown");
   }
   if (!is_shutdown_) {
     // TODO(ctiller): It is currently necessary to shutdown endpoints
     // before destroying them, even if we know that there are no
     // pending read/write callbacks.  This should be fixed, at which
     // point this can be removed.
     grpc_endpoint_shutdown(args_->endpoint, GRPC_ERROR_REF(error));
     // Not shutting down, so the handshake failed.  Clean up before
     // invoking the callback.
     CleanupArgsForFailureLocked();
     // Set shutdown to true so that subsequent calls to
     // http_connect_handshaker_shutdown() do nothing.
     is_shutdown_ = true;
   }
   // Invoke callback.
   ExecCtx::Run(DEBUG_LOCATION, on_handshake_done_, error);
 }

 // This callback can be invoked inline while already holding onto the mutex. To
 // avoid deadlocks, schedule OnWriteDone on ExecCtx.
 void HttpConnectHandshaker::OnWriteDoneScheduler(void* arg, grpc_error* error) {
   auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
   grpc_core::ExecCtx::Run(
       DEBUG_LOCATION,
       GRPC_CLOSURE_INIT(&handshaker->request_done_closure_,
                         &HttpConnectHandshaker::OnWriteDone, handshaker,
                         grpc_schedule_on_exec_ctx),
       GRPC_ERROR_REF(error));
 }

 // Callback invoked when finished writing HTTP CONNECT request.
 void HttpConnectHandshaker::OnWriteDone(void* arg, grpc_error* error) {
   auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
   ReleasableMutexLock lock(&handshaker->mu_);
   if (error != GRPC_ERROR_NONE || handshaker->is_shutdown_) {
     // If the write failed or we're shutting down, clean up and invoke the
     // callback with the error.
     handshaker->HandshakeFailedLocked(GRPC_ERROR_REF(error));
     lock.Unlock();
     handshaker->Unref();
   } else {
     // Otherwise, read the response.
     // The read callback inherits our ref to the handshaker.
     grpc_endpoint_read(
         handshaker->args_->endpoint, handshaker->args_->read_buffer,
         GRPC_CLOSURE_INIT(&handshaker->response_read_closure_,
                           &HttpConnectHandshaker::OnReadDoneScheduler,
                           handshaker, grpc_schedule_on_exec_ctx),
         /*urgent=*/true);
   }
 }

 // This callback can be invoked inline while already holding onto the mutex. To
 // avoid deadlocks, schedule OnReadDone on ExecCtx.
 void HttpConnectHandshaker::OnReadDoneScheduler(void* arg, grpc_error* error) {
   auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
   grpc_core::ExecCtx::Run(
       DEBUG_LOCATION,
       GRPC_CLOSURE_INIT(&handshaker->response_read_closure_,
                         &HttpConnectHandshaker::OnReadDone, handshaker,
                         grpc_schedule_on_exec_ctx),
       GRPC_ERROR_REF(error));
 }

 // Callback invoked for reading HTTP CONNECT response.
 void HttpConnectHandshaker::OnReadDone(void* arg, grpc_error* error) {
   auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
   ReleasableMutexLock lock(&handshaker->mu_);
   if (error != GRPC_ERROR_NONE || handshaker->is_shutdown_) {
     // If the read failed or we're shutting down, clean up and invoke the
     // callback with the error.
     handshaker->HandshakeFailedLocked(GRPC_ERROR_REF(error));
     goto done;
   }
   // Add buffer to parser.
   for (size_t i = 0; i < handshaker->args_->read_buffer->count; ++i) {
     if (GRPC_SLICE_LENGTH(handshaker->args_->read_buffer->slices[i]) > 0) {
       size_t body_start_offset = 0;
       error = grpc_http_parser_parse(&handshaker->http_parser_,
                                      handshaker->args_->read_buffer->slices[i],
                                      &body_start_offset);
       if (error != GRPC_ERROR_NONE) {
         handshaker->HandshakeFailedLocked(error);
         goto done;
       }
       if (handshaker->http_parser_.state == GRPC_HTTP_BODY) {
         // Remove the data we've already read from the read buffer,
         // leaving only the leftover bytes (if any).
         grpc_slice_buffer tmp_buffer;
         grpc_slice_buffer_init(&tmp_buffer);
         if (body_start_offset <
             GRPC_SLICE_LENGTH(handshaker->args_->read_buffer->slices[i])) {
           grpc_slice_buffer_add(
               &tmp_buffer,
               grpc_slice_split_tail(&handshaker->args_->read_buffer->slices[i],
                                     body_start_offset));
         }
         grpc_slice_buffer_addn(&tmp_buffer,
                                &handshaker->args_->read_buffer->slices[i + 1],
                                handshaker->args_->read_buffer->count - i - 1);
         grpc_slice_buffer_swap(handshaker->args_->read_buffer, &tmp_buffer);
         grpc_slice_buffer_destroy_internal(&tmp_buffer);
         break;
       }
     }
   }
   // If we're not done reading the response, read more data.
   // TODO(roth): In practice, I suspect that the response to a CONNECT
   // request will never include a body, in which case this check is
   // sufficient.  However, the language of RFC-2817 doesn't explicitly
   // forbid the response from including a body.  If there is a body,
   // it's possible that we might have parsed part but not all of the
   // body, in which case this check will cause us to fail to parse the
   // remainder of the body.  If that ever becomes an issue, we may
   // need to fix the HTTP parser to understand when the body is
   // complete (e.g., handling chunked transfer encoding or looking
   // at the Content-Length: header).
   if (handshaker->http_parser_.state != GRPC_HTTP_BODY) {
     grpc_slice_buffer_reset_and_unref_internal(handshaker->args_->read_buffer);
     grpc_endpoint_read(
         handshaker->args_->endpoint, handshaker->args_->read_buffer,
         GRPC_CLOSURE_INIT(&handshaker->response_read_closure_,
                           &HttpConnectHandshaker::OnReadDoneScheduler,
                           handshaker, grpc_schedule_on_exec_ctx),
         /*urgent=*/true);
     return;
   }
   // Make sure we got a 2xx response.
   if (handshaker->http_response_.status < 200 ||
       handshaker->http_response_.status >= 300) {
     error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
         absl::StrCat("HTTP proxy returned response code ",
                      handshaker->http_response_.status)
             .c_str());
     handshaker->HandshakeFailedLocked(error);
     goto done;
   }
   // Success.  Invoke handshake-done callback.
   ExecCtx::Run(DEBUG_LOCATION, handshaker->on_handshake_done_, error);
 done:
   // Set shutdown to true so that subsequent calls to
   // http_connect_handshaker_shutdown() do nothing.
   handshaker->is_shutdown_ = true;
   lock.Unlock();
   handshaker->Unref();
 }

 //
 // Public handshaker methods
 //

 void HttpConnectHandshaker::Shutdown(grpc_error* why) {
   {
     MutexLock lock(&mu_);
     if (!is_shutdown_) {
       is_shutdown_ = true;
       grpc_endpoint_shutdown(args_->endpoint, GRPC_ERROR_REF(why));
       CleanupArgsForFailureLocked();
     }
   }
   GRPC_ERROR_UNREF(why);
 }

 void HttpConnectHandshaker::DoHandshake(grpc_tcp_server_acceptor* /*acceptor*/,
                                         grpc_closure* on_handshake_done,
                                         HandshakerArgs* args) {
   // Check for HTTP CONNECT channel arg.
   // If not found, invoke on_handshake_done without doing anything.
   const grpc_arg* arg =
       grpc_channel_args_find(args->args, GRPC_ARG_HTTP_CONNECT_SERVER);
   char* server_name = grpc_channel_arg_get_string(arg);
   if (server_name == nullptr) {
     // Set shutdown to true so that subsequent calls to
     // http_connect_handshaker_shutdown() do nothing.
     {
       MutexLock lock(&mu_);
       is_shutdown_ = true;
     }
     ExecCtx::Run(DEBUG_LOCATION, on_handshake_done, GRPC_ERROR_NONE);
     return;
   }
   // Get headers from channel args.
   arg = grpc_channel_args_find(args->args, GRPC_ARG_HTTP_CONNECT_HEADERS);
   char* arg_header_string = grpc_channel_arg_get_string(arg);
   grpc_http_header* headers = nullptr;
   size_t num_headers = 0;
   char** header_strings = nullptr;
   size_t num_header_strings = 0;
   if (arg_header_string != nullptr) {
     gpr_string_split(arg_header_string, "\n", &header_strings,
                      &num_header_strings);
     headers = static_cast<grpc_http_header*>(
         gpr_malloc(sizeof(grpc_http_header) * num_header_strings));
     for (size_t i = 0; i < num_header_strings; ++i) {
       char* sep = strchr(header_strings[i], ':');

       if (sep == nullptr) {
         gpr_log(GPR_ERROR, "skipping unparseable HTTP CONNECT header: %s",
                 header_strings[i]);
         continue;
       }
       *sep = '\0';
       headers[num_headers].key = header_strings[i];
       headers[num_headers].value = sep + 1;
       ++num_headers;
     }
   }
   // Save state in the handshaker object.
   MutexLock lock(&mu_);
   args_ = args;
   on_handshake_done_ = on_handshake_done;
   // Log connection via proxy.
   std::string proxy_name(grpc_endpoint_get_peer(args->endpoint));
   gpr_log(GPR_INFO, "Connecting to server %s via HTTP proxy %s", server_name,
           proxy_name.c_str());
   // Construct HTTP CONNECT request.
   grpc_httpcli_request request;
   request.host = server_name;
   request.ssl_host_override = nullptr;
   request.http.method = (char*)"CONNECT";
   request.http.path = server_name;
   request.http.version = GRPC_HTTP_HTTP10;  // Set by OnReadDone
   request.http.hdrs = headers;
   request.http.hdr_count = num_headers;
   request.http.body_length = 0;
   request.http.body = nullptr;
   request.handshaker = &grpc_httpcli_plaintext;
   grpc_slice request_slice = grpc_httpcli_format_connect_request(&request);
   grpc_slice_buffer_add(&write_buffer_, request_slice);
   // Clean up.
   gpr_free(headers);
   for (size_t i = 0; i < num_header_strings; ++i) {
     gpr_free(header_strings[i]);
   }
   gpr_free(header_strings);
   // Take a new ref to be held by the write callback.
   Ref().release();
   grpc_endpoint_write(
       args->endpoint, &write_buffer_,
       GRPC_CLOSURE_INIT(&request_done_closure_,
                         &HttpConnectHandshaker::OnWriteDoneScheduler, this,
                         grpc_schedule_on_exec_ctx),
       nullptr);
 }

 HttpConnectHandshaker::HttpConnectHandshaker() {
   grpc_slice_buffer_init(&write_buffer_);
   grpc_http_parser_init(&http_parser_, GRPC_HTTP_RESPONSE, &http_response_);
 }

 //
 // handshaker factory
 //

 class HttpConnectHandshakerFactory : public HandshakerFactory {
  public:
   void AddHandshakers(const grpc_channel_args* /*args*/,
                       grpc_pollset_set* /*interested_parties*/,
                       HandshakeManager* handshake_mgr) override {
     handshake_mgr->Add(MakeRefCounted<HttpConnectHandshaker>());
   }
   ~HttpConnectHandshakerFactory() override = default;
 };

 }  // namespace

 }  // namespace grpc_core

 void grpc_http_connect_register_handshaker_factory() {
   grpc_core::HandshakerRegistry::RegisterHandshakerFactory(
       true /* at_start */, grpc_core::HANDSHAKER_CLIENT,
       absl::make_unique<grpc_core::HttpConnectHandshakerFactory>());
 }
	/*
	*
	* Copyright 2016 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/client_channel/http_connect_handshaker.h"

	#include <string.h>

	#include "absl/strings/str_cat.h"

	#include <grpc/slice_buffer.h>
	#include <grpc/support/alloc.h>
	#include <grpc/support/log.h>
	#include <grpc/support/string_util.h>

	#include "src/core/ext/filters/client_channel/client_channel.h"
	#include "src/core/ext/filters/client_channel/resolver_registry.h"
	#include "src/core/lib/channel/channel_args.h"
	#include "src/core/lib/channel/handshaker_registry.h"
	#include "src/core/lib/gpr/string.h"
	#include "src/core/lib/gprpp/sync.h"
	#include "src/core/lib/http/format_request.h"
	#include "src/core/lib/http/parser.h"
	#include "src/core/lib/slice/slice_internal.h"
	#include "src/core/lib/uri/uri_parser.h"

	namespace grpc_core {

	namespace {

	class HttpConnectHandshaker : public Handshaker {
	public:
	HttpConnectHandshaker();
	void Shutdown(grpc_error* why) override;
	void DoHandshake(grpc_tcp_server_acceptor* acceptor,
	grpc_closure* on_handshake_done,
	HandshakerArgs* args) override;
	const char* name() const override { return "http_connect"; }

	private:
	~HttpConnectHandshaker() override;
	void CleanupArgsForFailureLocked();
	void HandshakeFailedLocked(grpc_error* error);
	static void OnWriteDone(void* arg, grpc_error* error);
	static void OnReadDone(void* arg, grpc_error* error);
	static void OnWriteDoneScheduler(void* arg, grpc_error* error);
	static void OnReadDoneScheduler(void* arg, grpc_error* error);

	Mutex mu_;

	bool is_shutdown_ = false;
	// Endpoint and read buffer to destroy after a shutdown.
	grpc_endpoint* endpoint_to_destroy_ = nullptr;
	grpc_slice_buffer* read_buffer_to_destroy_ = nullptr;

	// State saved while performing the handshake.
	HandshakerArgs* args_ = nullptr;
	grpc_closure* on_handshake_done_ = nullptr;

	// Objects for processing the HTTP CONNECT request and response.
	grpc_slice_buffer write_buffer_;
	grpc_closure request_done_closure_;
	grpc_closure response_read_closure_;
	grpc_http_parser http_parser_;
	grpc_http_response http_response_;
	};

	HttpConnectHandshaker::~HttpConnectHandshaker() {
	if (endpoint_to_destroy_ != nullptr) {
	grpc_endpoint_destroy(endpoint_to_destroy_);
	}
	if (read_buffer_to_destroy_ != nullptr) {
	grpc_slice_buffer_destroy_internal(read_buffer_to_destroy_);
	gpr_free(read_buffer_to_destroy_);
	}
	grpc_slice_buffer_destroy_internal(&write_buffer_);
	grpc_http_parser_destroy(&http_parser_);
	grpc_http_response_destroy(&http_response_);
	}

	// Set args fields to nullptr, saving the endpoint and read buffer for
	// later destruction.
	void HttpConnectHandshaker::CleanupArgsForFailureLocked() {
	endpoint_to_destroy_ = args_->endpoint;
	args_->endpoint = nullptr;
	read_buffer_to_destroy_ = args_->read_buffer;
	args_->read_buffer = nullptr;
	grpc_channel_args_destroy(args_->args);
	args_->args = nullptr;
	}

	// If the handshake failed or we're shutting down, clean up and invoke the
	// callback with the error.
	void HttpConnectHandshaker::HandshakeFailedLocked(grpc_error* error) {
	if (error == GRPC_ERROR_NONE) {
	// If we were shut down after an endpoint operation succeeded but
	// before the endpoint callback was invoked, we need to generate our
	// own error.
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Handshaker shutdown");
	}
	if (!is_shutdown_) {
	// TODO(ctiller): It is currently necessary to shutdown endpoints
	// before destroying them, even if we know that there are no
	// pending read/write callbacks. This should be fixed, at which
	// point this can be removed.
	grpc_endpoint_shutdown(args_->endpoint, GRPC_ERROR_REF(error));
	// Not shutting down, so the handshake failed. Clean up before
	// invoking the callback.
	CleanupArgsForFailureLocked();
	// Set shutdown to true so that subsequent calls to
	// http_connect_handshaker_shutdown() do nothing.
	is_shutdown_ = true;
	}
	// Invoke callback.
	ExecCtx::Run(DEBUG_LOCATION, on_handshake_done_, error);
	}

	// This callback can be invoked inline while already holding onto the mutex. To
	// avoid deadlocks, schedule OnWriteDone on ExecCtx.
	void HttpConnectHandshaker::OnWriteDoneScheduler(void* arg, grpc_error* error) {
	auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
	grpc_core::ExecCtx::Run(
	DEBUG_LOCATION,
	GRPC_CLOSURE_INIT(&handshaker->request_done_closure_,
	&HttpConnectHandshaker::OnWriteDone, handshaker,
	grpc_schedule_on_exec_ctx),
	GRPC_ERROR_REF(error));
	}

	// Callback invoked when finished writing HTTP CONNECT request.
	void HttpConnectHandshaker::OnWriteDone(void* arg, grpc_error* error) {
	auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
	ReleasableMutexLock lock(&handshaker->mu_);
	if (error != GRPC_ERROR_NONE \|\| handshaker->is_shutdown_) {
	// If the write failed or we're shutting down, clean up and invoke the
	// callback with the error.
	handshaker->HandshakeFailedLocked(GRPC_ERROR_REF(error));
	lock.Unlock();
	handshaker->Unref();
	} else {
	// Otherwise, read the response.
	// The read callback inherits our ref to the handshaker.
	grpc_endpoint_read(
	handshaker->args_->endpoint, handshaker->args_->read_buffer,
	GRPC_CLOSURE_INIT(&handshaker->response_read_closure_,
	&HttpConnectHandshaker::OnReadDoneScheduler,
	handshaker, grpc_schedule_on_exec_ctx),
	/urgent=/true);
	}
	}

	// This callback can be invoked inline while already holding onto the mutex. To
	// avoid deadlocks, schedule OnReadDone on ExecCtx.
	void HttpConnectHandshaker::OnReadDoneScheduler(void* arg, grpc_error* error) {
	auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
	grpc_core::ExecCtx::Run(
	DEBUG_LOCATION,
	GRPC_CLOSURE_INIT(&handshaker->response_read_closure_,
	&HttpConnectHandshaker::OnReadDone, handshaker,
	grpc_schedule_on_exec_ctx),
	GRPC_ERROR_REF(error));
	}

	// Callback invoked for reading HTTP CONNECT response.
	void HttpConnectHandshaker::OnReadDone(void* arg, grpc_error* error) {
	auto* handshaker = static_cast<HttpConnectHandshaker*>(arg);
	ReleasableMutexLock lock(&handshaker->mu_);
	if (error != GRPC_ERROR_NONE \|\| handshaker->is_shutdown_) {
	// If the read failed or we're shutting down, clean up and invoke the
	// callback with the error.
	handshaker->HandshakeFailedLocked(GRPC_ERROR_REF(error));
	goto done;
	}
	// Add buffer to parser.
	for (size_t i = 0; i < handshaker->args_->read_buffer->count; ++i) {
	if (GRPC_SLICE_LENGTH(handshaker->args_->read_buffer->slices[i]) > 0) {
	size_t body_start_offset = 0;
	error = grpc_http_parser_parse(&handshaker->http_parser_,
	handshaker->args_->read_buffer->slices[i],
	&body_start_offset);
	if (error != GRPC_ERROR_NONE) {
	handshaker->HandshakeFailedLocked(error);
	goto done;
	}
	if (handshaker->http_parser_.state == GRPC_HTTP_BODY) {
	// Remove the data we've already read from the read buffer,
	// leaving only the leftover bytes (if any).
	grpc_slice_buffer tmp_buffer;
	grpc_slice_buffer_init(&tmp_buffer);
	if (body_start_offset <
	GRPC_SLICE_LENGTH(handshaker->args_->read_buffer->slices[i])) {
	grpc_slice_buffer_add(
	&tmp_buffer,
	grpc_slice_split_tail(&handshaker->args_->read_buffer->slices[i],
	body_start_offset));
	}
	grpc_slice_buffer_addn(&tmp_buffer,
	&handshaker->args_->read_buffer->slices[i + 1],
	handshaker->args_->read_buffer->count - i - 1);
	grpc_slice_buffer_swap(handshaker->args_->read_buffer, &tmp_buffer);
	grpc_slice_buffer_destroy_internal(&tmp_buffer);
	break;
	}
	}
	}
	// If we're not done reading the response, read more data.
	// TODO(roth): In practice, I suspect that the response to a CONNECT
	// request will never include a body, in which case this check is
	// sufficient. However, the language of RFC-2817 doesn't explicitly
	// forbid the response from including a body. If there is a body,
	// it's possible that we might have parsed part but not all of the
	// body, in which case this check will cause us to fail to parse the
	// remainder of the body. If that ever becomes an issue, we may
	// need to fix the HTTP parser to understand when the body is
	// complete (e.g., handling chunked transfer encoding or looking
	// at the Content-Length: header).
	if (handshaker->http_parser_.state != GRPC_HTTP_BODY) {
	grpc_slice_buffer_reset_and_unref_internal(handshaker->args_->read_buffer);
	grpc_endpoint_read(
	handshaker->args_->endpoint, handshaker->args_->read_buffer,
	GRPC_CLOSURE_INIT(&handshaker->response_read_closure_,
	&HttpConnectHandshaker::OnReadDoneScheduler,
	handshaker, grpc_schedule_on_exec_ctx),
	/urgent=/true);
	return;
	}
	// Make sure we got a 2xx response.
	if (handshaker->http_response_.status < 200 \|\|
	handshaker->http_response_.status >= 300) {
	error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
	absl::StrCat("HTTP proxy returned response code ",
	handshaker->http_response_.status)
	.c_str());
	handshaker->HandshakeFailedLocked(error);
	goto done;
	}
	// Success. Invoke handshake-done callback.
	ExecCtx::Run(DEBUG_LOCATION, handshaker->on_handshake_done_, error);
	done:
	// Set shutdown to true so that subsequent calls to
	// http_connect_handshaker_shutdown() do nothing.
	handshaker->is_shutdown_ = true;
	lock.Unlock();
	handshaker->Unref();
	}

	//
	// Public handshaker methods
	//

	void HttpConnectHandshaker::Shutdown(grpc_error* why) {
	{
	MutexLock lock(&mu_);
	if (!is_shutdown_) {
	is_shutdown_ = true;
	grpc_endpoint_shutdown(args_->endpoint, GRPC_ERROR_REF(why));
	CleanupArgsForFailureLocked();
	}
	}
	GRPC_ERROR_UNREF(why);
	}

	void HttpConnectHandshaker::DoHandshake(grpc_tcp_server_acceptor* /acceptor/,
	grpc_closure* on_handshake_done,
	HandshakerArgs* args) {
	// Check for HTTP CONNECT channel arg.
	// If not found, invoke on_handshake_done without doing anything.
	const grpc_arg* arg =
	grpc_channel_args_find(args->args, GRPC_ARG_HTTP_CONNECT_SERVER);
	char* server_name = grpc_channel_arg_get_string(arg);
	if (server_name == nullptr) {
	// Set shutdown to true so that subsequent calls to
	// http_connect_handshaker_shutdown() do nothing.
	{
	MutexLock lock(&mu_);
	is_shutdown_ = true;
	}
	ExecCtx::Run(DEBUG_LOCATION, on_handshake_done, GRPC_ERROR_NONE);
	return;
	}
	// Get headers from channel args.
	arg = grpc_channel_args_find(args->args, GRPC_ARG_HTTP_CONNECT_HEADERS);
	char* arg_header_string = grpc_channel_arg_get_string(arg);
	grpc_http_header* headers = nullptr;
	size_t num_headers = 0;
	char** header_strings = nullptr;
	size_t num_header_strings = 0;
	if (arg_header_string != nullptr) {
	gpr_string_split(arg_header_string, "\n", &header_strings,
	&num_header_strings);
	headers = static_cast<grpc_http_header*>(
	gpr_malloc(sizeof(grpc_http_header) * num_header_strings));
	for (size_t i = 0; i < num_header_strings; ++i) {
	char* sep = strchr(header_strings[i], ':');

	if (sep == nullptr) {
	gpr_log(GPR_ERROR, "skipping unparseable HTTP CONNECT header: %s",
	header_strings[i]);
	continue;
	}
	*sep = '\0';
	headers[num_headers].key = header_strings[i];
	headers[num_headers].value = sep + 1;
	++num_headers;
	}
	}
	// Save state in the handshaker object.
	MutexLock lock(&mu_);
	args_ = args;
	on_handshake_done_ = on_handshake_done;
	// Log connection via proxy.
	std::string proxy_name(grpc_endpoint_get_peer(args->endpoint));
	gpr_log(GPR_INFO, "Connecting to server %s via HTTP proxy %s", server_name,
	proxy_name.c_str());
	// Construct HTTP CONNECT request.
	grpc_httpcli_request request;
	request.host = server_name;
	request.ssl_host_override = nullptr;
	request.http.method = (char*)"CONNECT";
	request.http.path = server_name;
	request.http.version = GRPC_HTTP_HTTP10; // Set by OnReadDone
	request.http.hdrs = headers;
	request.http.hdr_count = num_headers;
	request.http.body_length = 0;
	request.http.body = nullptr;
	request.handshaker = &grpc_httpcli_plaintext;
	grpc_slice request_slice = grpc_httpcli_format_connect_request(&request);
	grpc_slice_buffer_add(&write_buffer_, request_slice);
	// Clean up.
	gpr_free(headers);
	for (size_t i = 0; i < num_header_strings; ++i) {
	gpr_free(header_strings[i]);
	}
	gpr_free(header_strings);
	// Take a new ref to be held by the write callback.
	Ref().release();
	grpc_endpoint_write(
	args->endpoint, &write_buffer_,
	GRPC_CLOSURE_INIT(&request_done_closure_,
	&HttpConnectHandshaker::OnWriteDoneScheduler, this,
	grpc_schedule_on_exec_ctx),
	nullptr);
	}

	HttpConnectHandshaker::HttpConnectHandshaker() {
	grpc_slice_buffer_init(&write_buffer_);
	grpc_http_parser_init(&http_parser_, GRPC_HTTP_RESPONSE, &http_response_);
	}

	//
	// handshaker factory
	//

	class HttpConnectHandshakerFactory : public HandshakerFactory {
	public:
	void AddHandshakers(const grpc_channel_args* /args/,
	grpc_pollset_set* /interested_parties/,
	HandshakeManager* handshake_mgr) override {
	handshake_mgr->Add(MakeRefCounted<HttpConnectHandshaker>());
	}
	~HttpConnectHandshakerFactory() override = default;
	};

	} // namespace

	} // namespace grpc_core

	void grpc_http_connect_register_handshaker_factory() {
	grpc_core::HandshakerRegistry::RegisterHandshakerFactory(
	true /* at_start */, grpc_core::HANDSHAKER_CLIENT,
	absl::make_unique<grpc_core::HttpConnectHandshakerFactory>());
	}