WebServer.cpp

/*
  WebServer.cpp - Dead simple web-server.
  Supports only one simultaneous client, knows how to handle GET and POST.

  Copyright (c) 2014 Ivan Grokhotkov. All rights reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  Modified 8 May 2015 by Hristo Gochkov (proper post and file upload handling)
*/


#include <Arduino.h>
#include <esp32-hal-log.h>
#include <libb64/cdecode.h>
#include <libb64/cencode.h>
#include "esp_random.h"
#include "NetworkServer.h"
#include "NetworkClient.h"
#include "WebServer.h"
#include "FS.h"
#include "detail/RequestHandlersImpl.h"
#include "MD5Builder.h"
#include "SHA1Builder.h"
#include "base64.h"

static const char AUTHORIZATION_HEADER[] = "Authorization";
static const char qop_auth[] PROGMEM = "qop=auth";
static const char qop_auth_quoted[] PROGMEM = "qop=\"auth\"";
static const char WWW_Authenticate[] = "WWW-Authenticate";
static const char Content_Length[] = "Content-Length";
static const char ETAG_HEADER[] = "If-None-Match";

WebServer::WebServer(IPAddress addr, int port)
: _corsEnabled(false)
, _server(addr, port)
, _currentMethod(HTTP_ANY)
, _currentVersion(0)
, _currentStatus(HC_NONE)
, _statusChange(0)
, _nullDelay(true)
, _currentHandler(nullptr)
, _firstHandler(nullptr)
, _lastHandler(nullptr)
, _currentArgCount(0)
, _currentArgs(nullptr)
, _postArgsLen(0)
, _postArgs(nullptr)
, _headerKeysCount(0)
, _currentHeaders(nullptr)
, _contentLength(0)
, _clientContentLength(0)
, _chunked(false)
{
  log_v("WebServer::Webserver(addr=%s, port=%d)", addr.toString().c_str(), port);
}

WebServer::WebServer(int port)
: _corsEnabled(false)
, _server(port)
, _currentMethod(HTTP_ANY)
, _currentVersion(0)
, _currentStatus(HC_NONE)
, _statusChange(0)
, _nullDelay(true)
, _currentHandler(nullptr)
, _firstHandler(nullptr)
, _lastHandler(nullptr)
, _currentArgCount(0)
, _currentArgs(nullptr)
, _postArgsLen(0)
, _postArgs(nullptr)
, _headerKeysCount(0)
, _currentHeaders(nullptr)
, _contentLength(0)
, _clientContentLength(0)
, _chunked(false)
{
  log_v("WebServer::Webserver(port=%d)", port);
}

WebServer::~WebServer() {
  _server.close();
  if (_currentHeaders)
    delete[]_currentHeaders;
  RequestHandler* handler = _firstHandler;
  while (handler) {
    RequestHandler* next = handler->next();
    delete handler;
    handler = next;
  }
}

void WebServer::begin() {
  close();
  _server.begin();
  _server.setNoDelay(true);
}

void WebServer::begin(uint16_t port) {
  close();
  _server.begin(port);
  _server.setNoDelay(true);
}

String WebServer::_extractParam(String& authReq,const String& param,const char delimit){
  int _begin = authReq.indexOf(param);
  if (_begin == -1)
    return "";
  return authReq.substring(_begin+param.length(),authReq.indexOf(delimit,_begin+param.length()));
}

static String md5str(String &in){
  MD5Builder md5 = MD5Builder();
  md5.begin();
  md5.add(in);
  md5.calculate();
  return md5.toString();
}

bool WebServer::authenticateBasicSHA1(const char * _username, const char * _sha1Base64orHex) {
  return WebServer::authenticate([_username,_sha1Base64orHex](HTTPAuthMethod mode, String username, String params[])->String * {
    // rather than work on a password to compare with; we take the sha1 of the
    // password received over the wire and compare that to the base64 encoded
    // sha1 passed as _sha1base64. That way there is no need to have a
    // plaintext password in the code/binary (though note that SHA1 is well
    // past its retirement age). When that matches - we `cheat' by returning
    // the password we got in the first place; so the normal BasicAuth
    // can be completed. Note that this cannot work for a digest auth -
    // as there the password in the clear is part of the calculation.

    if (params == nullptr) {
      log_e("Something went wrong. params is NULL");
      return NULL;
    }

    uint8_t sha1[20];
    char sha1calc[48]; // large enough for base64 and Hex represenation
    String ret;
    SHA1Builder sha_builder;
    base64 b64;

    log_v("Trying to authenticate user %s using SHA1.", username.c_str());
    sha_builder.begin();
    sha_builder.add((uint8_t*) params[0].c_str(), params[0].length());
    sha_builder.calculate();
    sha_builder.getBytes(sha1);

    // we can either decode _sha1base64orHex and then compare the 20 bytes;
    // or encode the sha we calculated. We pick the latter as encoding of a
    // fixed array of 20 bytes is safer than operating on something external.
    if (strlen(_sha1Base64orHex) == 20 * 2) { // 2 chars per byte
      sha_builder.bytes2hex(sha1calc, sizeof(sha1calc), sha1, sizeof(sha1));
      log_v("Calculated SHA1 in hex: %s", sha1calc);
    } else {
      ret = b64.encode(sha1, sizeof(sha1));
      ret.toCharArray(sha1calc, sizeof(sha1calc));
      log_v("Calculated SHA1 in base64: %s", sha1calc);
    }

    return ((username.equalsConstantTime(_username)) &&
            (String((char*)sha1calc).equalsConstantTime(_sha1Base64orHex)) &&
            (mode == BASIC_AUTH) /* to keep things somewhat time constant. */
            ) ? new String(params[0]) : NULL;
  });
}

bool WebServer::authenticate(const char * _username, const char * _password) {
  return WebServer::authenticate([_username,_password](HTTPAuthMethod mode, String username, String params[])->String * {
    return username.equalsConstantTime(_username) ? new String(_password) : NULL;
  });
}

bool WebServer::authenticate(THandlerFunctionAuthCheck fn) {
  if (!hasHeader(FPSTR(AUTHORIZATION_HEADER))) {
    return false;
  }

  String authReq = header(FPSTR(AUTHORIZATION_HEADER));
  if (authReq.startsWith(AuthTypeBasic)) {
    log_v("Trying to authenticate using Basic Auth");
    bool ret = false;

    authReq = authReq.substring(6); // length of AuthTypeBasic including the space at the end.
    authReq.trim();

    /* base64 encoded string is always shorter (or equal) in length */
    char* decoded = (authReq.length() < HTTP_MAX_BASIC_AUTH_LEN) ? new char[authReq.length()] : NULL;
    if (decoded) {
      char* p;
      if (base64_decode_chars(authReq.c_str(), authReq.length(), decoded) && (p = index(decoded, ':')) && p) {
        authReq = "";
        /* Note: rfc7617 guarantees that there will not be an escaped colon in the username itself.
         * Note:  base64_decode_chars() guarantees a terminating \0
         */
        *p = '\0';
        char * _username = decoded, * _password = p + 1;
        String params[] = {
          _password,
          _srealm
        };
        String* password = fn(BASIC_AUTH, _username, params);

        if (password) {
          ret = password->equalsConstantTime(_password);
          // we're more concerned about the password; as the attacker already
          // knows the _pasword. Arduino's string handling is simple; it reallocs
          // even when smaller; so a memset is enough (no capacity/size).
          memset((void *)password->c_str(), 0, password->length());
          delete password;
        }
      }
      delete[] decoded;
    }
    authReq = "";
    log_v("Authentication %s", ret ? "Success" : "Failed");
    return ret;
  } else if (authReq.startsWith(AuthTypeDigest)) {
    log_v("Trying to authenticate using Digest Auth");
    authReq = authReq.substring(7);
    log_v("%s", authReq.c_str());

    // extracting required parameters for RFC 2069 simpler Digest
    String _username = _extractParam(authReq, F("username=\""), '\"');
    String _realm = _extractParam(authReq, F("realm=\""), '\"');
    String _uri = _extractParam(authReq, F("uri=\""), '\"');
    if (!_username.length())
      goto exf;

    String params[] = {
      _realm,
      _uri
    };
    String* password = fn(DIGEST_AUTH, _username, params);
    if (!password)
      goto exf;

    String _H1 = md5str(String(_username) + ':' + _realm + ':' + * password);
    // we're extra concerned; as digest request us to know the password
    // in the clear.
    memset((void *) password->c_str(), 0, password->length());
    delete password;
    _username = "";

    String _nonce = _extractParam(authReq, F("nonce=\""), '\"');
    String _response = _extractParam(authReq, F("response=\""), '\"');
    String _opaque = _extractParam(authReq, F("opaque=\""), '\"');

    if ((!_realm.length()) || (!_nonce.length()) || (!_uri.length()) || (!_response.length()) || (!_opaque.length()))
      goto exf;

    if ((_opaque != _sopaque) || (_nonce != _snonce) || (_realm != _srealm))
      goto exf;

    // parameters for the RFC 2617 newer Digest
    String _nc, _cnonce;
    if (authReq.indexOf(FPSTR(qop_auth)) != -1 || authReq.indexOf(FPSTR(qop_auth_quoted)) != -1) {
      _nc = _extractParam(authReq, F("nc="), ',');
      _cnonce = _extractParam(authReq, F("cnonce=\""), '\"');
    }

    log_v("Hash of user:realm:pass=%s", _H1.c_str());
    String _H2 = "";
    if (_currentMethod == HTTP_GET) {
      _H2 = md5str(String(F("GET:")) + _uri);
    } else if (_currentMethod == HTTP_POST) {
      _H2 = md5str(String(F("POST:")) + _uri);
    } else if (_currentMethod == HTTP_PUT) {
      _H2 = md5str(String(F("PUT:")) + _uri);
    } else if (_currentMethod == HTTP_DELETE) {
      _H2 = md5str(String(F("DELETE:")) + _uri);
    } else {
      _H2 = md5str(String(F("GET:")) + _uri);
    }
    log_v("Hash of GET:uri=%s", _H2.c_str());
    String _responsecheck = "";
    if (authReq.indexOf(FPSTR(qop_auth)) != -1 || authReq.indexOf(FPSTR(qop_auth_quoted)) != -1) {
      _responsecheck = md5str(_H1 + ':' + _nonce + ':' + _nc + ':' + _cnonce + F(":auth:") + _H2);
    } else {
      _responsecheck = md5str(_H1 + ':' + _nonce + ':' + _H2);
    }
    authReq = "";

    log_v("The Proper response=%s", _responsecheck.c_str());
    bool ret = _response == _responsecheck;
    log_v("Authentication %s", ret ? "Success" : "Failed");
    return ret;
  } else if (authReq.length()) {
    // OTHER_AUTH
    log_v("Trying to authenticate using Other Auth, authReq=%s", authReq.c_str());
    String* ret = fn(OTHER_AUTH, authReq, {});
    if (ret) {
      log_v("Authentication Success");
      return true;
    }
  }
exf:
  authReq = "";
  log_v("Authentication Failed");
  return false;
}

String WebServer::_getRandomHexString() {
  char buffer[33];  // buffer to hold 32 Hex Digit + /0
  int i;
  for(i = 0; i < 4; i++) {
    sprintf (buffer + (i*8), "%08lx", esp_random());
  }
  return String(buffer);
}

void WebServer::requestAuthentication(HTTPAuthMethod mode, const char* realm, const String& authFailMsg) {
  if(realm == NULL) {
    _srealm = String(F("Login Required"));
  } else {
    _srealm = String(realm);
  }
  if(mode == BASIC_AUTH) {
    sendHeader(String(FPSTR(WWW_Authenticate)), AuthTypeBasic + String(F(" realm=\"")) + _srealm + String(F("\"")));
  } else {
    _snonce=_getRandomHexString();
    _sopaque=_getRandomHexString();
    sendHeader(String(FPSTR(WWW_Authenticate)), AuthTypeDigest + String(F(" realm=\"")) +_srealm + String(F("\", qop=\"auth\", nonce=\"")) + _snonce + String(F("\", opaque=\"")) + _sopaque + String(F("\"")));
  }
  using namespace mime;
  send(401, String(FPSTR(mimeTable[html].mimeType)), authFailMsg);
}

void WebServer::on(const Uri &uri, WebServer::THandlerFunction handler) {
  on(uri, HTTP_ANY, handler);
}

void WebServer::on(const Uri &uri, HTTPMethod method, WebServer::THandlerFunction fn) {
  on(uri, method, fn, _fileUploadHandler);
}

void WebServer::on(const Uri &uri, HTTPMethod method, WebServer::THandlerFunction fn, WebServer::THandlerFunction ufn) {
  _addRequestHandler(new FunctionRequestHandler(fn, ufn, uri, method));
}

void WebServer::addHandler(RequestHandler* handler) {
    _addRequestHandler(handler);
}

void WebServer::_addRequestHandler(RequestHandler* handler) {
    if (!_lastHandler) {
      _firstHandler = handler;
      _lastHandler = handler;
    }
    else {
      _lastHandler->next(handler);
      _lastHandler = handler;
    }
}

void WebServer::serveStatic(const char* uri, FS& fs, const char* path, const char* cache_header) {
    _addRequestHandler(new StaticRequestHandler(fs, path, uri, cache_header));
}

void WebServer::handleClient() {
  if (_currentStatus == HC_NONE) {
    _currentClient = _server.accept();
    if (!_currentClient) {
      if (_nullDelay) {
        delay(1);
      }
      return;
    }

    log_v("New client: client.localIP()=%s", _currentClient.localIP().toString().c_str());

    _currentStatus = HC_WAIT_READ;
    _statusChange = millis();
  }

  bool keepCurrentClient = false;
  bool callYield = false;

  if (_currentClient.connected()) {
    switch (_currentStatus) {
    case HC_NONE:
      // No-op to avoid C++ compiler warning
      break;
    case HC_WAIT_READ:
      // Wait for data from client to become available
      if (_currentClient.available()) {
        if (_parseRequest(_currentClient)) {
          // because HTTP_MAX_SEND_WAIT is expressed in milliseconds,
          // it must be divided by 1000
          _currentClient.setTimeout(HTTP_MAX_SEND_WAIT); /* / 1000 removed, WifiClient setTimeout changed to ms */
          _contentLength = CONTENT_LENGTH_NOT_SET;
          _handleRequest();

          if (_currentClient.isSSE()) {
            _currentStatus = HC_WAIT_CLOSE;
            _statusChange = millis();
            keepCurrentClient = true;
          }
// Fix for issue with Chrome based browsers: https://github.com/espressif/arduino-esp32/issues/3652
//           if (_currentClient.connected()) {
//             _currentStatus = HC_WAIT_CLOSE;
//             _statusChange = millis();
//             keepCurrentClient = true;
//           }
        }
      } else { // !_currentClient.available()
        if (millis() - _statusChange <= HTTP_MAX_DATA_WAIT) {
          keepCurrentClient = true;
        }
        callYield = true;
      }
      break;
    case HC_WAIT_CLOSE:
      if (_currentClient.isSSE()) {
        // Never close connection
        _statusChange = millis();
      }
      // Wait for client to close the connection
      if (millis() - _statusChange <= HTTP_MAX_CLOSE_WAIT) {
        keepCurrentClient = true;
        callYield = true;
      }
    }
  }

  if (!keepCurrentClient) {
    _currentClient = NetworkClient();
    _currentStatus = HC_NONE;
    _currentUpload.reset();
    _currentRaw.reset();
  }

  if (callYield) {
    yield();
  }
}

void WebServer::close() {
  _server.close();
  _currentStatus = HC_NONE;
  if(!_headerKeysCount)
    collectHeaders(0, 0);
}

void WebServer::stop() {
  close();
}

void WebServer::sendHeader(const String& name, const String& value, bool first) {
  String headerLine = name;
  headerLine += F(": ");
  headerLine += value;
  headerLine += "\r\n";

  if (first) {
    _responseHeaders = headerLine + _responseHeaders;
  }
  else {
    _responseHeaders += headerLine;
  }
}

void WebServer::setContentLength(const size_t contentLength) {
    _contentLength = contentLength;
}

void WebServer::enableDelay(boolean value) {
  _nullDelay = value;
}

void WebServer::enableCORS(boolean value) {
  _corsEnabled = value;
}

void WebServer::enableCrossOrigin(boolean value) {
  enableCORS(value);
}

void WebServer::enableETag(bool enable, ETagFunction fn) {
  _eTagEnabled = enable;
  _eTagFunction = fn;
}

void WebServer::_prepareHeader(String& response, int code, const char* content_type, size_t contentLength) {
    response = String(F("HTTP/1.")) + String(_currentVersion) + ' ';
    response += String(code);
    response += ' ';
    response += _responseCodeToString(code);
    response += "\r\n";

    using namespace mime;
    if (!content_type)
        content_type = mimeTable[html].mimeType;

    sendHeader(String(F("Content-Type")), String(FPSTR(content_type)), true);
    if (_contentLength == CONTENT_LENGTH_NOT_SET) {
        sendHeader(String(FPSTR(Content_Length)), String(contentLength));
    } else if (_contentLength != CONTENT_LENGTH_UNKNOWN) {
        sendHeader(String(FPSTR(Content_Length)), String(_contentLength));
    } else if(_contentLength == CONTENT_LENGTH_UNKNOWN && _currentVersion){ //HTTP/1.1 or above client
      //let's do chunked
      _chunked = true;
      sendHeader(String(F("Accept-Ranges")),String(F("none")));
      sendHeader(String(F("Transfer-Encoding")),String(F("chunked")));
    }
    if (_corsEnabled) {
        sendHeader(String(FPSTR("Access-Control-Allow-Origin")), String("*"));
        sendHeader(String(FPSTR("Access-Control-Allow-Methods")), String("*"));
        sendHeader(String(FPSTR("Access-Control-Allow-Headers")), String("*"));
    }
    sendHeader(String(F("Connection")), String(F("close")));

    response += _responseHeaders;
    response += "\r\n";
    _responseHeaders = "";
}

void WebServer::send(int code, const char* content_type, const String& content) {
    String header;
    // Can we asume the following?
    //if(code == 200 && content.length() == 0 && _contentLength == CONTENT_LENGTH_NOT_SET)
    //  _contentLength = CONTENT_LENGTH_UNKNOWN;
    if (content.length() == 0) {
        log_w("content length is zero");
    }
    _prepareHeader(header, code, content_type, content.length());
    _currentClientWrite(header.c_str(), header.length());
    if(content.length())
      sendContent(content);
}

void WebServer::send(int code, char* content_type, const String& content) {
  send(code, (const char*)content_type, content);
}

void WebServer::send(int code, const String& content_type, const String& content) {
  send(code, (const char*)content_type.c_str(), content);
}

void WebServer::send(int code, const char* content_type, const char* content)
{
    const String passStr = (String)content;
    if (strlen(content) != passStr.length()) {
       log_e("String cast failed.  Use send_P for long arrays");
    }
    send(code, content_type, passStr);
}

void WebServer::send_P(int code, PGM_P content_type, PGM_P content) {
    size_t contentLength = 0;

    if (content != NULL) {
        contentLength = strlen_P(content);
    }

    String header;
    char type[64];
    memccpy_P((void*)type, (PGM_VOID_P)content_type, 0, sizeof(type));
    _prepareHeader(header, code, (const char* )type, contentLength);
    _currentClientWrite(header.c_str(), header.length());
    sendContent_P(content);
}

void WebServer::send_P(int code, PGM_P content_type, PGM_P content, size_t contentLength) {
    String header;
    char type[64];
    memccpy_P((void*)type, (PGM_VOID_P)content_type, 0, sizeof(type));
    _prepareHeader(header, code, (const char* )type, contentLength);
    sendContent(header);
    sendContent_P(content, contentLength);
}

void WebServer::sendContent(const String& content) {
  sendContent(content.c_str(), content.length());
}

void WebServer::sendContent(const char* content, size_t contentLength) {
  const char * footer = "\r\n";
  if(_chunked) {
    char * chunkSize = (char *)malloc(11);
    if(chunkSize){
      sprintf(chunkSize, "%x%s", contentLength, footer);
      _currentClientWrite(chunkSize, strlen(chunkSize));
      free(chunkSize);
    }
  }
  _currentClientWrite(content, contentLength);
  if(_chunked){
    _currentClient.write(footer, 2);
    if (contentLength == 0) {
      _chunked = false;
    }
  }
}

void WebServer::sendContent_P(PGM_P content) {
  sendContent_P(content, strlen_P(content));
}

void WebServer::sendContent_P(PGM_P content, size_t size) {
  const char * footer = "\r\n";
  if(_chunked) {
    char * chunkSize = (char *)malloc(11);
    if(chunkSize){
      sprintf(chunkSize, "%x%s", size, footer);
      _currentClientWrite(chunkSize, strlen(chunkSize));
      free(chunkSize);
    }
  }
  _currentClientWrite_P(content, size);
  if(_chunked){
    _currentClient.write(footer, 2);
    if (size == 0) {
      _chunked = false;
    }
  }
}


void WebServer::_streamFileCore(const size_t fileSize, const String & fileName, const String & contentType, const int code)
{
  using namespace mime;
  setContentLength(fileSize);
  if (fileName.endsWith(String(FPSTR(mimeTable[gz].endsWith))) &&
      contentType != String(FPSTR(mimeTable[gz].mimeType)) &&
      contentType != String(FPSTR(mimeTable[none].mimeType))) {
    sendHeader(F("Content-Encoding"), F("gzip"));
  }
  send(code, contentType, "");
}

String WebServer::pathArg(unsigned int i) {
  if (_currentHandler != nullptr)
    return _currentHandler->pathArg(i);
  return "";
}

String WebServer::arg(String name) {
  for (int j = 0; j < _postArgsLen; ++j) {
    if ( _postArgs[j].key == name )
      return _postArgs[j].value;
  }
  for (int i = 0; i < _currentArgCount; ++i) {
    if ( _currentArgs[i].key == name )
      return _currentArgs[i].value;
  }
  return "";
}

String WebServer::arg(int i) {
  if (i < _currentArgCount)
    return _currentArgs[i].value;
  return "";
}

String WebServer::argName(int i) {
  if (i < _currentArgCount)
    return _currentArgs[i].key;
  return "";
}

int WebServer::args() {
  return _currentArgCount;
}

bool WebServer::hasArg(String  name) {
  for (int j = 0; j < _postArgsLen; ++j) {
    if (_postArgs[j].key == name)
      return true;
  }
  for (int i = 0; i < _currentArgCount; ++i) {
    if (_currentArgs[i].key == name)
      return true;
  }
  return false;
}


String WebServer::header(String name) {
  for (int i = 0; i < _headerKeysCount; ++i) {
    if (_currentHeaders[i].key.equalsIgnoreCase(name))
      return _currentHeaders[i].value;
  }
  return "";
}

void WebServer::collectHeaders(const char* headerKeys[], const size_t headerKeysCount) {
  _headerKeysCount = headerKeysCount + 2;
  if (_currentHeaders)
     delete[]_currentHeaders;
  _currentHeaders = new RequestArgument[_headerKeysCount];
  _currentHeaders[0].key = FPSTR(AUTHORIZATION_HEADER);
  _currentHeaders[1].key = FPSTR(ETAG_HEADER);
  for (int i = 2; i < _headerKeysCount; i++){
    _currentHeaders[i].key = headerKeys[i-2];
  }
}

String WebServer::header(int i) {
  if (i < _headerKeysCount)
    return _currentHeaders[i].value;
  return "";
}

String WebServer::headerName(int i) {
  if (i < _headerKeysCount)
    return _currentHeaders[i].key;
  return "";
}

int WebServer::headers() {
  return _headerKeysCount;
}

bool WebServer::hasHeader(String name) {
  for (int i = 0; i < _headerKeysCount; ++i) {
    if ((_currentHeaders[i].key.equalsIgnoreCase(name)) &&  (_currentHeaders[i].value.length() > 0))
      return true;
  }
  return false;
}

String WebServer::hostHeader() {
  return _hostHeader;
}

void WebServer::onFileUpload(THandlerFunction fn) {
  _fileUploadHandler = fn;
}

void WebServer::onNotFound(THandlerFunction fn) {
  _notFoundHandler = fn;
}

void WebServer::_handleRequest() {
  bool handled = false;
  if (!_currentHandler){
    log_e("request handler not found");
  }
  else {
    handled = _currentHandler->handle(*this, _currentMethod, _currentUri);
    if (!handled) {
      log_e("request handler failed to handle request");
    }
  }
  if (!handled && _notFoundHandler) {
    _notFoundHandler();
    handled = true;
  }
  if (!handled) {
    using namespace mime;
    send(404, String(FPSTR(mimeTable[html].mimeType)), String(F("Not found: ")) + _currentUri);
    handled = true;
  }
  if (handled) {
    _finalizeResponse();
  }
  _currentUri = "";
}


void WebServer::_finalizeResponse() {
  if (_chunked) {
    sendContent("");
  }
}

String WebServer::_responseCodeToString(int code) {
  switch (code) {
    case 100: return F("Continue");
    case 101: return F("Switching Protocols");
    case 200: return F("OK");
    case 201: return F("Created");
    case 202: return F("Accepted");
    case 203: return F("Non-Authoritative Information");
    case 204: return F("No Content");
    case 205: return F("Reset Content");
    case 206: return F("Partial Content");
    case 300: return F("Multiple Choices");
    case 301: return F("Moved Permanently");
    case 302: return F("Found");
    case 303: return F("See Other");
    case 304: return F("Not Modified");
    case 305: return F("Use Proxy");
    case 307: return F("Temporary Redirect");
    case 400: return F("Bad Request");
    case 401: return F("Unauthorized");
    case 402: return F("Payment Required");
    case 403: return F("Forbidden");
    case 404: return F("Not Found");
    case 405: return F("Method Not Allowed");
    case 406: return F("Not Acceptable");
    case 407: return F("Proxy Authentication Required");
    case 408: return F("Request Time-out");
    case 409: return F("Conflict");
    case 410: return F("Gone");
    case 411: return F("Length Required");
    case 412: return F("Precondition Failed");
    case 413: return F("Request Entity Too Large");
    case 414: return F("Request-URI Too Large");
    case 415: return F("Unsupported Media Type");
    case 416: return F("Requested range not satisfiable");
    case 417: return F("Expectation Failed");
    case 500: return F("Internal Server Error");
    case 501: return F("Not Implemented");
    case 502: return F("Bad Gateway");
    case 503: return F("Service Unavailable");
    case 504: return F("Gateway Time-out");
    case 505: return F("HTTP Version not supported");
    default:  return F("");
  }
}