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esp8266/libraries/ESP8266WebServer/src/ESP8266WebServer-impl.h
Zakary Kamal Ismail 0dbb04e881 Add HTTP_HEAD to HTTPMethod and parse it (#6413)
* Add HTTP_HEAD to HTTPMethod

* Parse the HTTP_HEAD variant of HTTPMethod from a method string

* Add HTTP_HEAD to the ESP8266WebServer constants

* Skip sending the content of the response if the HTTP method is HEAD method

* Convert the HTTP status code 418  to string
This status code is an easter egg from the IETF and is described in 
[RFC2324](https://tools.ietf.org/html/rfc2324#section-2.3.2)
2019-08-17 11:58:40 -07:00

742 lines
23 KiB
C++

/*
ESP8266WebServer.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 <libb64/cencode.h>
#include "WiFiServer.h"
#include "WiFiClient.h"
#include "ESP8266WebServer.h"
#include "FS.h"
#include "detail/RequestHandlersImpl.h"
//#define DEBUG_ESP_HTTP_SERVER
#ifdef DEBUG_ESP_PORT
#define DEBUG_OUTPUT DEBUG_ESP_PORT
#else
#define DEBUG_OUTPUT Serial
#endif
static const char AUTHORIZATION_HEADER[] PROGMEM = "Authorization";
static const char qop_auth[] PROGMEM = "qop=auth";
static const char qop_auth_quoted[] PROGMEM = "qop=\"auth\"";
static const char WWW_Authenticate[] PROGMEM = "WWW-Authenticate";
static const char Content_Length[] PROGMEM = "Content-Length";
template <typename ServerType>
ESP8266WebServerTemplate<ServerType>::ESP8266WebServerTemplate(IPAddress addr, int port)
: _server(addr, port)
, _currentMethod(HTTP_ANY)
, _currentVersion(0)
, _currentStatus(HC_NONE)
, _statusChange(0)
, _currentHandler(nullptr)
, _firstHandler(nullptr)
, _lastHandler(nullptr)
, _currentArgCount(0)
, _currentArgs(nullptr)
, _postArgsLen(0)
, _postArgs(nullptr)
, _headerKeysCount(0)
, _currentHeaders(nullptr)
, _contentLength(0)
, _chunked(false)
{
}
template <typename ServerType>
ESP8266WebServerTemplate<ServerType>::ESP8266WebServerTemplate(int port)
: _server(port)
, _currentMethod(HTTP_ANY)
, _currentVersion(0)
, _currentStatus(HC_NONE)
, _statusChange(0)
, _currentHandler(nullptr)
, _firstHandler(nullptr)
, _lastHandler(nullptr)
, _currentArgCount(0)
, _currentArgs(nullptr)
, _postArgsLen(0)
, _postArgs(nullptr)
, _headerKeysCount(0)
, _currentHeaders(nullptr)
, _contentLength(0)
, _chunked(false)
{
}
template <typename ServerType>
ESP8266WebServerTemplate<ServerType>::~ESP8266WebServerTemplate() {
_server.close();
if (_currentHeaders)
delete[]_currentHeaders;
RequestHandlerType* handler = _firstHandler;
while (handler) {
RequestHandlerType* next = handler->next();
delete handler;
handler = next;
}
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::begin() {
close();
_server.begin();
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::begin(uint16_t port) {
close();
_server.begin(port);
}
template <typename ServerType>
String ESP8266WebServerTemplate<ServerType>::_extractParam(String& authReq,const String& param,const char delimit) const {
int _begin = authReq.indexOf(param);
if (_begin == -1)
return emptyString;
return authReq.substring(_begin+param.length(),authReq.indexOf(delimit,_begin+param.length()));
}
template <typename ServerType>
bool ESP8266WebServerTemplate<ServerType>::authenticate(const char * username, const char * password){
if(hasHeader(FPSTR(AUTHORIZATION_HEADER))) {
String authReq = header(FPSTR(AUTHORIZATION_HEADER));
if(authReq.startsWith(F("Basic"))){
authReq = authReq.substring(6);
authReq.trim();
char toencodeLen = strlen(username)+strlen(password)+1;
char *toencode = new char[toencodeLen + 1];
if(toencode == NULL){
authReq = "";
return false;
}
char *encoded = new char[base64_encode_expected_len(toencodeLen)+1];
if(encoded == NULL){
authReq = "";
delete[] toencode;
return false;
}
sprintf(toencode, "%s:%s", username, password);
if(base64_encode_chars(toencode, toencodeLen, encoded) > 0 && authReq.equalsConstantTime(encoded)) {
authReq = "";
delete[] toencode;
delete[] encoded;
return true;
}
delete[] toencode;
delete[] encoded;
} else if(authReq.startsWith(F("Digest"))) {
String _realm = _extractParam(authReq, F("realm=\""));
String _H1 = credentialHash((String)username,_realm,(String)password);
return authenticateDigest((String)username,_H1);
}
authReq = "";
}
return false;
}
template <typename ServerType>
bool ESP8266WebServerTemplate<ServerType>::authenticateDigest(const String& username, const String& H1)
{
if(hasHeader(FPSTR(AUTHORIZATION_HEADER))) {
String authReq = header(FPSTR(AUTHORIZATION_HEADER));
if(authReq.startsWith(F("Digest"))) {
authReq = authReq.substring(7);
#ifdef DEBUG_ESP_HTTP_SERVER
DEBUG_OUTPUT.println(authReq);
#endif
String _username = _extractParam(authReq,F("username=\""));
if(!_username.length() || _username != String(username)) {
authReq = "";
return false;
}
// extracting required parameters for RFC 2069 simpler Digest
String _realm = _extractParam(authReq, F("realm=\""));
String _nonce = _extractParam(authReq, F("nonce=\""));
String _uri = _extractParam(authReq, F("uri=\""));
String _response = _extractParam(authReq, F("response=\""));
String _opaque = _extractParam(authReq, F("opaque=\""));
if((!_realm.length()) || (!_nonce.length()) || (!_uri.length()) || (!_response.length()) || (!_opaque.length())) {
authReq = "";
return false;
}
if((_opaque != _sopaque) || (_nonce != _snonce) || (_realm != _srealm)) {
authReq = "";
return false;
}
// 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=\""));
}
#ifdef DEBUG_ESP_HTTP_SERVER
DEBUG_OUTPUT.println("Hash of user:realm:pass=" + H1);
#endif
MD5Builder md5;
md5.begin();
if(_currentMethod == HTTP_GET){
md5.add(String(F("GET:")) + _uri);
}else if(_currentMethod == HTTP_POST){
md5.add(String(F("POST:")) + _uri);
}else if(_currentMethod == HTTP_PUT){
md5.add(String(F("PUT:")) + _uri);
}else if(_currentMethod == HTTP_DELETE){
md5.add(String(F("DELETE:")) + _uri);
}else{
md5.add(String(F("GET:")) + _uri);
}
md5.calculate();
String _H2 = md5.toString();
#ifdef DEBUG_ESP_HTTP_SERVER
DEBUG_OUTPUT.println("Hash of GET:uri=" + _H2);
#endif
md5.begin();
if(authReq.indexOf(FPSTR(qop_auth)) != -1 || authReq.indexOf(FPSTR(qop_auth_quoted)) != -1) {
md5.add(H1 + ':' + _nonce + ':' + _nc + ':' + _cnonce + F(":auth:") + _H2);
} else {
md5.add(H1 + ':' + _nonce + ':' + _H2);
}
md5.calculate();
String _responsecheck = md5.toString();
#ifdef DEBUG_ESP_HTTP_SERVER
DEBUG_OUTPUT.println("The Proper response=" +_responsecheck);
#endif
if(_response == _responsecheck){
authReq = "";
return true;
}
}
authReq = "";
}
return false;
}
template <typename ServerType>
String ESP8266WebServerTemplate<ServerType>::_getRandomHexString() {
char buffer[33]; // buffer to hold 32 Hex Digit + /0
int i;
for(i = 0; i < 4; i++) {
sprintf (buffer + (i*8), "%08x", RANDOM_REG32);
}
return String(buffer);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::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)), String(F("Basic realm=\"")) + _srealm + String(F("\"")));
} else {
_snonce=_getRandomHexString();
_sopaque=_getRandomHexString();
sendHeader(String(FPSTR(WWW_Authenticate)), String(F("Digest 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);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::on(const String &uri, ESP8266WebServerTemplate<ServerType>::THandlerFunction handler) {
on(uri, HTTP_ANY, handler);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::on(const String &uri, HTTPMethod method, ESP8266WebServerTemplate<ServerType>::THandlerFunction fn) {
on(uri, method, fn, _fileUploadHandler);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::on(const String &uri, HTTPMethod method, ESP8266WebServerTemplate<ServerType>::THandlerFunction fn, ESP8266WebServerTemplate<ServerType>::THandlerFunction ufn) {
_addRequestHandler(new FunctionRequestHandler<ServerType>(fn, ufn, uri, method));
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::addHandler(RequestHandlerType* handler) {
_addRequestHandler(handler);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::_addRequestHandler(RequestHandlerType* handler) {
if (!_lastHandler) {
_firstHandler = handler;
_lastHandler = handler;
}
else {
_lastHandler->next(handler);
_lastHandler = handler;
}
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::serveStatic(const char* uri, FS& fs, const char* path, const char* cache_header) {
_addRequestHandler(new StaticRequestHandler<ServerType>(fs, path, uri, cache_header));
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::handleClient() {
if (_currentStatus == HC_NONE) {
ClientType client = _server.available();
if (!client) {
return;
}
#ifdef DEBUG_ESP_HTTP_SERVER
DEBUG_OUTPUT.println("New client");
#endif
_currentClient = client;
_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)) {
_currentClient.setTimeout(HTTP_MAX_SEND_WAIT);
_contentLength = CONTENT_LENGTH_NOT_SET;
_handleRequest();
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:
// Wait for client to close the connection
if (millis() - _statusChange <= HTTP_MAX_CLOSE_WAIT) {
keepCurrentClient = true;
callYield = true;
}
}
}
if (!keepCurrentClient) {
_currentClient = ClientType();
_currentStatus = HC_NONE;
_currentUpload.reset();
}
if (callYield) {
yield();
}
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::close() {
_server.close();
_currentStatus = HC_NONE;
if(!_headerKeysCount)
collectHeaders(0, 0);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::stop() {
close();
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::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;
}
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::setContentLength(const size_t contentLength) {
_contentLength = contentLength;
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::_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")));
}
sendHeader(String(F("Connection")), String(F("close")));
response += _responseHeaders;
response += "\r\n";
_responseHeaders = "";
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::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;
_prepareHeader(header, code, content_type, content.length());
_currentClient.write((const uint8_t *)header.c_str(), header.length());
if(content.length())
sendContent(content);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::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);
_currentClient.write((const uint8_t *)header.c_str(), header.length());
if (contentLength) {
sendContent_P(content);
}
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::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);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::send(int code, char* content_type, const String& content) {
send(code, (const char*)content_type, content);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::send(int code, const String& content_type, const String& content) {
send(code, (const char*)content_type.c_str(), content);
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::sendContent(const String& content) {
if (_currentMethod == HTTP_HEAD) return;
const char * footer = "\r\n";
size_t len = content.length();
if(_chunked) {
char chunkSize[11];
sprintf(chunkSize, "%zx\r\n", len);
_currentClient.write((const uint8_t *)chunkSize, strlen(chunkSize));
}
_currentClient.write((const uint8_t *)content.c_str(), len);
if(_chunked){
_currentClient.write((const uint8_t *)footer, 2);
if (len == 0) {
_chunked = false;
}
}
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::sendContent_P(PGM_P content) {
sendContent_P(content, strlen_P(content));
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::sendContent_P(PGM_P content, size_t size) {
const char * footer = "\r\n";
if(_chunked) {
char chunkSize[11];
sprintf(chunkSize, "%zx\r\n", size);
_currentClient.write((const uint8_t *)chunkSize, strlen(chunkSize));
}
_currentClient.write_P(content, size);
if(_chunked){
_currentClient.write((const uint8_t *)footer, 2);
if (size == 0) {
_chunked = false;
}
}
}
template <typename ServerType>
String ESP8266WebServerTemplate<ServerType>::credentialHash(const String& username, const String& realm, const String& password)
{
MD5Builder md5;
md5.begin();
md5.add(username + ":" + realm + ":" + password); // md5 of the user:realm:password
md5.calculate();
return md5.toString();
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::_streamFileCore(const size_t fileSize, const String & fileName, const String & contentType)
{
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(200, contentType, emptyString);
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::arg(String name) const {
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 emptyString;
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::arg(int i) const {
if (i >= 0 && i < _currentArgCount)
return _currentArgs[i].value;
return emptyString;
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::argName(int i) const {
if (i >= 0 && i < _currentArgCount)
return _currentArgs[i].key;
return emptyString;
}
template <typename ServerType>
int ESP8266WebServerTemplate<ServerType>::args() const {
return _currentArgCount;
}
template <typename ServerType>
bool ESP8266WebServerTemplate<ServerType>::hasArg(const String& name) const {
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;
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::header(String name) const {
for (int i = 0; i < _headerKeysCount; ++i) {
if (_currentHeaders[i].key.equalsIgnoreCase(name))
return _currentHeaders[i].value;
}
return emptyString;
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::collectHeaders(const char* headerKeys[], const size_t headerKeysCount) {
_headerKeysCount = headerKeysCount + 1;
if (_currentHeaders)
delete[]_currentHeaders;
_currentHeaders = new RequestArgument[_headerKeysCount];
_currentHeaders[0].key = FPSTR(AUTHORIZATION_HEADER);
for (int i = 1; i < _headerKeysCount; i++){
_currentHeaders[i].key = headerKeys[i-1];
}
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::header(int i) const {
if (i < _headerKeysCount)
return _currentHeaders[i].value;
return emptyString;
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::headerName(int i) const {
if (i < _headerKeysCount)
return _currentHeaders[i].key;
return emptyString;
}
template <typename ServerType>
int ESP8266WebServerTemplate<ServerType>::headers() const {
return _headerKeysCount;
}
template <typename ServerType>
bool ESP8266WebServerTemplate<ServerType>::hasHeader(String name) const {
for (int i = 0; i < _headerKeysCount; ++i) {
if ((_currentHeaders[i].key.equalsIgnoreCase(name)) && (_currentHeaders[i].value.length() > 0))
return true;
}
return false;
}
template <typename ServerType>
const String& ESP8266WebServerTemplate<ServerType>::hostHeader() const {
return _hostHeader;
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::onFileUpload(THandlerFunction fn) {
_fileUploadHandler = fn;
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::onNotFound(THandlerFunction fn) {
_notFoundHandler = fn;
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::_handleRequest() {
bool handled = false;
if (!_currentHandler){
#ifdef DEBUG_ESP_HTTP_SERVER
DEBUG_OUTPUT.println("request handler not found");
#endif
}
else {
handled = _currentHandler->handle(*this, _currentMethod, _currentUri);
#ifdef DEBUG_ESP_HTTP_SERVER
if (!handled) {
DEBUG_OUTPUT.println("request handler failed to handle request");
}
#endif
}
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 = "";
}
template <typename ServerType>
void ESP8266WebServerTemplate<ServerType>::_finalizeResponse() {
if (_chunked) {
sendContent(emptyString);
}
}
template <typename ServerType>
const String ESP8266WebServerTemplate<ServerType>::responseCodeToString(const 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 418: return F("I'm a teapot");
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("");
}
}