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// Standard C++
#include <atomic>
#include <cerrno>
#include <csignal>
#include <cstdlib>
#include <cstring>
#include <exception>
#include <iostream>
#include <sstream>
#include <stdexcept>
#include <string>
#include <string_view>
#include <utility>
// FastCGI
#include <fcgiapp.h>
using namespace std;
namespace {
struct Configuration {
int value;
string listen_address;
};
struct RequestError : runtime_error {
RequestError(int status, const string& meldung)
: runtime_error(meldung)
, status(status)
{
}
int status;
};
atomic_bool quit{ false };
atomic_bool reload{ false };
void
signal_handler(int signal)
{
if ( signal == SIGINT || signal == SIGTERM ) {
quit = true;
}
else if ( signal == SIGHUP ) {
reload = true;
}
}
void
init_signal_handler()
{
struct sigaction sa;
memset(&sa, 0, sizeof sa);
sa.sa_handler = signal_handler;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGINT, &sa, NULL);
sigaction(SIGTERM, &sa, NULL);
sigaction(SIGHUP, &sa, NULL);
signal(SIGPIPE, SIG_IGN);
}
bool
load_configuration(Configuration& configuration)
{
cerr << "Load configuration ...\n";
configuration.value = 1;
configuration.listen_address = "127.0.0.1:5000";
return true;
}
void
escape_html(string_view str, ostream& out)
{
for ( auto chr: str ) {
switch ( chr ) {
case '<':
out << "<";
break;
case '>':
out << ">";
break;
case '&':
out << "&";
break;
case '\"':
out << """;
break;
default:
out << chr;
}
}
}
void
handle_request(char* env[], const Configuration&, string_view body, ostream& out)
{
const char* methode = FCGX_GetParam("REQUEST_METHOD", env);
out << "Content-Type: text/html; charset=utf-8\r\n\r\n";
out << "<h1>Verbindung erfolgreich verarbeitet!</h1>";
out << "<p>Methode: " << (methode ? methode : "?") << ", Body: " << body.size() << " Bytes</p>";
out << "<pre>";
for ( int i = 0; env[i] != NULL; ++i ) {
// Request-Daten dürfen nicht ungefiltert als HTML ausgegeben werden.
escape_html(env[i], out);
out << '\n';
}
out << "</pre>";
}
void
send_error(const FCGX_Request& request, int status, const char* meldung)
{
FCGX_FPrintF(request.out, "Status: %d\r\n", status);
FCGX_FPrintF(request.out, "Content-Type: text/plain; charset=utf-8\r\n\r\n");
FCGX_FPrintF(request.out, "%s\n", meldung);
}
string
read_request_body(const FCGX_Request& request)
{
string body;
char buffer[8192];
int gelesen;
while ( (gelesen = FCGX_GetStr(buffer, sizeof buffer, request.in)) > 0 ) {
body.append(buffer, gelesen);
}
return body;
}
} // namespace
int
main()
{
FCGX_Init();
Configuration configuration{};
if ( !load_configuration(configuration) ) {
cerr << "Die Konfiguration konnte nicht geladen werden.\n";
return EXIT_FAILURE;
}
auto socket = FCGX_OpenSocket(configuration.listen_address.c_str(), 20);
if ( socket == -1 ) {
cerr << "Fehler beim Erstellen des Listen-Sockets...\n";
return EXIT_FAILURE;
}
FCGX_Request request;
if ( FCGX_InitRequest(&request, socket, FCGI_FAIL_ACCEPT_ON_INTR) != 0 ) {
cerr << "Fehler beim Initialisieren...\n";
return EXIT_FAILURE;
}
init_signal_handler();
cout << "Handle Requests...\n";
while ( !quit ) {
if ( reload.exchange(false) ) {
Configuration new_configuration{};
if ( load_configuration(new_configuration) ) {
if ( new_configuration.listen_address != configuration.listen_address ) {
cerr << "Listen-Adresse geaendert, wirksam erst nach Neustart.\n";
}
configuration = std::move(new_configuration);
}
else {
cerr << "Neue Konfiguration nicht lesbar, die bisherige bleibt in Kraft.\n";
}
}
if ( FCGX_Accept_r(&request) < 0 ) {
if ( errno != EINTR ) {
cerr << "Fehler beim Annehmen der Verbindung: " << strerror(errno) << '\n';
break;
}
continue;
}
try {
const string body = read_request_body(request);
ostringstream response;
handle_request(request.envp, configuration, body, response);
const string_view text = response.view();
FCGX_PutStr(text.data(), static_cast<int>(text.size()), request.out);
}
catch ( const RequestError& e ) {
FCGX_FPrintF(request.err, "Anfrage abgebrochen (%d): %s\n", e.status, e.what());
send_error(request, e.status, e.what());
}
catch ( const exception& e ) {
FCGX_FPrintF(request.err, "Fehler beim Verarbeiten der Anfrage: %s\n", e.what());
send_error(request, 500, "Die Anfrage konnte nicht verarbeitet werden.");
}
FCGX_Finish_r(&request);
}
cout << "shutdown...\n";
}
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