workflow/tutorial/tutorial-05-http_proxy.cc at master · ieafei/workflow · GitHub

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#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <utility>
#include "workflow/Workflow.h"
#include "workflow/HttpMessage.h"
#include "workflow/HttpUtil.h"
#include "workflow/WFHttpServer.h"
#include "workflow/WFFacilities.h"

struct tutorial_series_context
{
	std::string url;
	WFHttpTask *proxy_task;
	bool is_keep_alive;
};

void reply_callback(WFHttpTask *proxy_task)
{
	SeriesWork *series = series_of(proxy_task);
	tutorial_series_context *context =
		(tutorial_series_context *)series->get_context();
	auto *proxy_resp = proxy_task->get_resp();
	size_t size = proxy_resp->get_output_body_size();

	if (proxy_task->get_state() == WFT_STATE_SUCCESS)
		fprintf(stderr, "%s: Success. Http Status: %s, BodyLength: %zu\n",
				context->url.c_str(), proxy_resp->get_status_code(), size);
	else /* WFT_STATE_SYS_ERROR*/
		fprintf(stderr, "%s: Reply failed: %s, BodyLength: %zu\n",
				context->url.c_str(), strerror(proxy_task->get_error()), size);
}

void http_callback(WFHttpTask *task)
{
	int state = task->get_state();
	int error = task->get_error();
	auto *resp = task->get_resp();
	SeriesWork *series = series_of(task);
	tutorial_series_context *context =
		(tutorial_series_context *)series->get_context();
	auto *proxy_resp = context->proxy_task->get_resp();

	if (state == WFT_STATE_SUCCESS)
	{
		const void *body;
		size_t len;

		/* set a callback for getting reply status. */
		context->proxy_task->set_callback(reply_callback);

		/* Copy the remote webserver's response, to proxy response. */
		resp->get_parsed_body(&body, &len);
		resp->append_output_body_nocopy(body, len);
		*proxy_resp = std::move(*resp);
		if (!context->is_keep_alive)
			proxy_resp->set_header_pair("Connection", "close");
	}
	else
	{
		const char *err_string;

		if (state == WFT_STATE_SYS_ERROR)
			err_string = strerror(error);
		else if (state == WFT_STATE_DNS_ERROR)
			err_string = gai_strerror(error);
		else if (state == WFT_STATE_SSL_ERROR)
			err_string = "SSL error";
		else /* if (state == WFT_STATE_TASK_ERROR) */
			err_string = "URL error (Cannot be a HTTPS proxy)";

		fprintf(stderr, "%s: Fetch failed. state = %d, error = %d: %s\n",
				context->url.c_str(), state, error, err_string);

		/* As a tutorial, make it simple. And ignore reply status. */
		proxy_resp->set_status_code("404");
		proxy_resp->append_output_body_nocopy(
							"<html>404 Not Found.</html>", 27);
	}
}

void process(WFHttpTask *proxy_task)
{
	auto *req = proxy_task->get_req();
	SeriesWork *series = series_of(proxy_task);
	WFHttpTask *http_task; /* for requesting remote webserver. */

	tutorial_series_context *context = new tutorial_series_context;
	context->url = req->get_request_uri();
	context->proxy_task = proxy_task;

	series->set_context(context);
	series->set_callback([](const SeriesWork *series) {
		delete (tutorial_series_context *)series->get_context();
	});

	context->is_keep_alive = req->is_keep_alive();
	http_task = WFTaskFactory::create_http_task(req->get_request_uri(), 0, 0,
												http_callback);

	const void *body;
	size_t len;

	/* Copy user's request to the new task's reuqest using std::move() */
	req->set_request_uri(http_task->get_req()->get_request_uri());
	req->get_parsed_body(&body, &len);
	req->append_output_body_nocopy(body, len);
	*http_task->get_req() = std::move(*req);

	/* also, limit the remote webserver response size. */
	http_task->get_resp()->set_size_limit(200 * 1024 * 1024);

	*series << http_task;
}

static WFFacilities::WaitGroup wait_group(1);

void sig_handler(int signo)
{
	wait_group.done();
}

int main(int argc, char *argv[])
{
	unsigned short port;

	if (argc != 2)
	{
		fprintf(stderr, "USAGE: %s <port>\n", argv[0]);
		exit(1);
	}

	port = atoi(argv[1]);
	signal(SIGINT, sig_handler);

	struct WFServerParams params = HTTP_SERVER_PARAMS_DEFAULT;
	/* for safety, limit request size to 8MB. */
	params.request_size_limit = 8 * 1024 * 1024;

	WFHttpServer server(&params, process);

	if (server.start(port) == 0)
	{
		wait_group.wait();
		server.stop();
	}
	else
	{
		perror("Cannot start server");
		exit(1);
	}

	return 0;
}