WebServer.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil;  c-file-style: "k&r"; c-basic-offset: 2; -*-

   Webduino, a simple Arduino web server
   Copyright 2009-2012 Ben Combee, Ran Talbott, Christopher Lee, Martin Lormes

   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   THE SOFTWARE.
*/

#ifndef WEBDUINO_H_
#define WEBDUINO_H_

#include <string.h>
#include <stdlib.h>

#include <EthernetClient.h>
#include <EthernetServer.h>

/********************************************************************
 * CONFIGURATION
 ********************************************************************/

#define WEBDUINO_VERSION 1007
#define WEBDUINO_VERSION_STRING "1.7"

#if WEBDUINO_SUPRESS_SERVER_HEADER
#define WEBDUINO_SERVER_HEADER ""
#else
#define WEBDUINO_SERVER_HEADER "Server: Webduino/" WEBDUINO_VERSION_STRING CRLF
#endif

// standard END-OF-LINE marker in HTTP
#define CRLF "\r\n"

// If processConnection is called without a buffer, it allocates one
// of 32 bytes
#define WEBDUINO_DEFAULT_REQUEST_LENGTH 32

// How long to wait before considering a connection as dead when
// reading the HTTP request.  Used to avoid DOS attacks.
#ifndef WEBDUINO_READ_TIMEOUT_IN_MS
#define WEBDUINO_READ_TIMEOUT_IN_MS 1000
#endif

#ifndef WEBDUINO_URL_PATH_COMMAND_LENGTH
#define WEBDUINO_URL_PATH_COMMAND_LENGTH 8
#endif

#ifndef WEBDUINO_FAIL_MESSAGE
#define WEBDUINO_FAIL_MESSAGE "<h1>EPIC FAIL</h1>"
#endif

#ifndef WEBDUINO_AUTH_REALM
#define WEBDUINO_AUTH_REALM "Webduino"
#endif // #ifndef WEBDUINO_AUTH_REALM

#ifndef WEBDUINO_AUTH_MESSAGE
#define WEBDUINO_AUTH_MESSAGE "<h1>401 Unauthorized</h1>"
#endif // #ifndef WEBDUINO_AUTH_MESSAGE

#ifndef WEBDUINO_SERVER_ERROR_MESSAGE
#define WEBDUINO_SERVER_ERROR_MESSAGE "<h1>500 Internal Server Error</h1>"
#endif // WEBDUINO_SERVER_ERROR_MESSAGE

// add '#define WEBDUINO_FAVICON_DATA ""' to your application
// before including WebServer.h to send a null file as the favicon.ico file
// otherwise this defaults to a 16x16 px black diode on blue ground
// (or include your own icon if you like)
#ifndef WEBDUINO_FAVICON_DATA
#define WEBDUINO_FAVICON_DATA { 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x10, \
                                0x10, 0x02, 0x00, 0x01, 0x00, 0x01, 0x00, \
                                0xb0, 0x00, 0x00, 0x00, 0x16, 0x00, 0x00, \
                                0x00, 0x28, 0x00, 0x00, 0x00, 0x10, 0x00, \
                                0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x01, \
                                0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0xff, 0x00, 0x00, 0x00, \
                                0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0x00, \
                                0x00, 0xff, 0xff, 0x00, 0x00, 0xcf, 0xbf, \
                                0x00, 0x00, 0xc7, 0xbf, 0x00, 0x00, 0xc3, \
                                0xbf, 0x00, 0x00, 0xc1, 0xbf, 0x00, 0x00, \
                                0xc0, 0xbf, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0xc0, 0xbf, 0x00, 0x00, 0xc1, 0xbf, \
                                0x00, 0x00, 0xc3, 0xbf, 0x00, 0x00, 0xc7, \
                                0xbf, 0x00, 0x00, 0xcf, 0xbf, 0x00, 0x00, \
                                0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                0x00, 0x00 }
#endif // #ifndef WEBDUINO_FAVICON_DATA

// add "#define WEBDUINO_SERIAL_DEBUGGING 1" to your application
// before including WebServer.h to have incoming requests logged to
// the serial port.
#ifndef WEBDUINO_SERIAL_DEBUGGING
#define WEBDUINO_SERIAL_DEBUGGING 0
#endif
#if WEBDUINO_SERIAL_DEBUGGING
#include <HardwareSerial.h>
#endif

// declared in wiring.h
extern "C" unsigned long millis(void);

// declare a static string
#define P(name)   static const unsigned char name[] PROGMEM

// returns the number of elements in the array
#define SIZE(array) (sizeof(array) / sizeof(*array))

/********************************************************************
 * DECLARATIONS
 ********************************************************************/

/* Return codes from nextURLparam.  NOTE: URLPARAM_EOS is returned
 * when you call nextURLparam AFTER the last parameter is read.  The
 * last actual parameter gets an "OK" return code. */

typedef enum URLPARAM_RESULT { URLPARAM_OK,
                               URLPARAM_NAME_OFLO,
                               URLPARAM_VALUE_OFLO,
                               URLPARAM_BOTH_OFLO,
                               URLPARAM_EOS         // No params left
};

class WebServer: public Print
{
public:
  // passed to a command to indicate what kind of request was received
  enum ConnectionType { INVALID, GET, HEAD, POST, PUT, DELETE, PATCH };

  // any commands registered with the web server have to follow
  // this prototype.
  // url_tail contains the part of the URL that wasn't matched against
  //          the registered command table.
  // tail_complete is true if the complete URL fit in url_tail,  false if
  //          part of it was lost because the buffer was too small.
  typedef void Command(WebServer &server, ConnectionType type,
                       char *url_tail, bool tail_complete);

  // Prototype for the optional function which consumes the URL path itself.
  // url_path contains pointers to the seperate parts of the URL path where '/'
  //          was used as the delimiter.
  typedef void UrlPathCommand(WebServer &server, ConnectionType type,
                              char **url_path, char *url_tail,
                              bool tail_complete);

  // constructor for webserver object
  WebServer(const char *urlPrefix = "", int port = 80);

  // start listening for connections
  void begin();

  // check for an incoming connection, and if it exists, process it
  // by reading its request and calling the appropriate command
  // handler.  This version is for compatibility with apps written for
  // version 1.1,  and allocates the URL "tail" buffer internally.
  void processConnection();

  // check for an incoming connection, and if it exists, process it
  // by reading its request and calling the appropriate command
  // handler.  This version saves the "tail" of the URL in buff.
  void processConnection(char *buff, int *bufflen);

  // set command that's run when you access the root of the server
  void setDefaultCommand(Command *cmd);

  // set command run for undefined pages
  void setFailureCommand(Command *cmd);

  // add a new command to be run at the URL specified by verb
  void addCommand(const char *verb, Command *cmd);

  // Set command that's run if default command or URL specified commands do
  // not run, uses extra url_path parameter to allow resolving the URL in the
  // function.
  void setUrlPathCommand(UrlPathCommand *cmd);

  // utility function to output CRLF pair
  void printCRLF();

  // output a string stored in program memory, usually one defined
  // with the P macro
  void printP(const unsigned char *str);

  // inline overload for printP to handle signed char strings
  void printP(const char *str) { printP((unsigned char*)str); }

  // output raw data stored in program memory
  void writeP(const unsigned char *data, size_t length);

  // output HTML for a radio button
  void radioButton(const char *name, const char *val,
                   const char *label, bool selected);

  // output HTML for a checkbox
  void checkBox(const char *name, const char *val,
                const char *label, bool selected);

  // returns next character or -1 if we're at end-of-stream
  int read();

  // put a character that's been read back into the input pool
  void push(int ch);

  // returns true if the string is next in the stream.  Doesn't
  // consume any character if false, so can be used to try out
  // different expected values.
  bool expect(const char *expectedStr);

  // returns true if a number, with possible whitespace in front, was
  // read from the server stream.  number will be set with the new
  // value or 0 if nothing was read.
  bool readInt(int &number);

  // reads a header value, stripped of possible whitespace in front,
  // from the server stream
  void readHeader(char *value, int valueLen);

  // Read the next keyword parameter from the socket.  Assumes that other
  // code has already skipped over the headers,  and the next thing to
  // be read will be the start of a keyword.
  //
  // returns true if we're not at end-of-stream
  bool readPOSTparam(char *name, int nameLen, char *value, int valueLen);

  // Read the next keyword parameter from the buffer filled by getRequest.
  //
  // returns 0 if everything weent okay,  non-zero if not
  // (see the typedef for codes)
  URLPARAM_RESULT nextURLparam(char **tail, char *name, int nameLen,
                               char *value, int valueLen);

  // compare string against credentials in current request
  //
  // authCredentials must be Base64 encoded outside of Webduino
  // (I wanted to be easy on the resources)
  //
  // returns true if strings match, false otherwise
  bool checkCredentials(const char authCredentials[45]);

  // output headers and a message indicating a server error
  void httpFail();
  
  // output headers and a message indicating "401 Unauthorized"
  void httpUnauthorized();

  // output headers and a message indicating "500 Internal Server Error"
  void httpServerError();

  // output headers indicating "204 No Content" and no further message
  void httpNoContent();

  // output standard headers indicating "200 Success".  You can change the
  // type of the data you're outputting or also add extra headers like
  // "Refresh: 1".  Extra headers should each be terminated with CRLF.
  void httpSuccess(const char *contentType = "text/html; charset=utf-8",
                   const char *extraHeaders = NULL);

  // used with POST to output a redirect to another URL.  This is
  // preferable to outputting HTML from a post because you can then
  // refresh the page without getting a "resubmit form" dialog.
  void httpSeeOther(const char *otherURL);

  // implementation of write used to implement Print interface
  virtual size_t write(uint8_t);
  virtual size_t write(const char *str);
  virtual size_t write(const uint8_t *buffer, size_t size);
  size_t write(const char *data, size_t length);

  // tells if there is anything to process
  uint8_t available();

private:
  EthernetServer m_server;
  EthernetClient m_client;
  const char *m_urlPrefix;

  unsigned char m_pushback[32];
  char m_pushbackDepth;

  int m_contentLength;
  char m_authCredentials[51];
  bool m_readingContent;

  Command *m_failureCmd;
  Command *m_defaultCmd;
  struct CommandMap
  {
    const char *verb;
    Command *cmd;
  } m_commands[8];
  char m_cmdCount;
  UrlPathCommand *m_urlPathCmd;

  void reset();
  void getRequest(WebServer::ConnectionType &type, char *request, int *length);
  bool dispatchCommand(ConnectionType requestType, char *verb,
                       bool tail_complete);
  void processHeaders();
  void outputCheckboxOrRadio(const char *element, const char *name,
                             const char *val, const char *label,
                             bool selected);

  static void defaultFailCmd(WebServer &server, ConnectionType type,
                             char *url_tail, bool tail_complete);
  void noRobots(ConnectionType type);
  void favicon(ConnectionType type);
};

/* define this macro if you want to include the header in a sketch source
   file but not define any of the implementation. This is useful if
   multiple source files are using the Webduino class. */
#ifndef WEBDUINO_NO_IMPLEMENTATION

/********************************************************************
 * IMPLEMENTATION
 ********************************************************************/

WebServer::WebServer(const char *urlPrefix, int port) :
  m_server(port),
  m_client(255),
  m_urlPrefix(urlPrefix),
  m_pushbackDepth(0),
  m_cmdCount(0),
  m_contentLength(0),
  m_failureCmd(&defaultFailCmd),
  m_defaultCmd(&defaultFailCmd),
  m_urlPathCmd(NULL)
{
}

void WebServer::begin()
{
  m_server.begin();
}

void WebServer::setDefaultCommand(Command *cmd)
{
  m_defaultCmd = cmd;
}

void WebServer::setFailureCommand(Command *cmd)
{
  m_failureCmd = cmd;
}

void WebServer::addCommand(const char *verb, Command *cmd)
{
  if (m_cmdCount < SIZE(m_commands))
  {
    m_commands[m_cmdCount].verb = verb;
    m_commands[m_cmdCount++].cmd = cmd;
  }
}

void WebServer::setUrlPathCommand(UrlPathCommand *cmd)
{
  m_urlPathCmd = cmd;
}

size_t WebServer::write(uint8_t ch)
{
  return m_client.write(ch);
}

size_t WebServer::write(const char *str)
{
  return m_client.write(str);
}

size_t WebServer::write(const uint8_t *buffer, size_t size)
{
  return m_client.write(buffer, size);
}

size_t WebServer::write(const char *buffer, size_t length)
{
  return m_client.write((const uint8_t *)buffer, length);
}

void WebServer::writeP(const unsigned char *data, size_t length)
{
  // copy data out of program memory into local storage, write out in
  // chunks of 32 bytes to avoid extra short TCP/IP packets
  uint8_t buffer[32];
  size_t bufferEnd = 0;

  while (length--)
  {
    if (bufferEnd == 32)
    {
      m_client.write(buffer, 32);
      bufferEnd = 0;
    }

    buffer[bufferEnd++] = pgm_read_byte(data++);
  }

  if (bufferEnd > 0)
    m_client.write(buffer, bufferEnd);
}

void WebServer::printP(const unsigned char *str)
{
  // copy data out of program memory into local storage, write out in
  // chunks of 32 bytes to avoid extra short TCP/IP packets
  uint8_t buffer[32];
  size_t bufferEnd = 0;
  
  while (buffer[bufferEnd++] = pgm_read_byte(str++))
  {
    if (bufferEnd == 32)
    {
      m_client.write(buffer, 32);
      bufferEnd = 0;
    }
  }

  // write out everything left but trailing NUL
  if (bufferEnd > 1)
    m_client.write(buffer, bufferEnd - 1);
}

void WebServer::printCRLF()
{
  m_client.write((const uint8_t *)"\r\n", 2);
}

bool WebServer::dispatchCommand(ConnectionType requestType, char *verb,
        bool tail_complete)
{
  // if there is no URL, i.e. we have a prefix and it's requested without a 
  // trailing slash or if the URL is just the slash
  if ((verb[0] == 0) || ((verb[0] == '/') && (verb[1] == 0)))
  {
    m_defaultCmd(*this, requestType, "", tail_complete);
    return true;
  }
  // if the URL is just a slash followed by a question mark
  // we're looking at the default command with GET parameters passed
  if ((verb[0] == '/') && (verb[1] == '?'))
  {
    verb+=2; // skip over the "/?" part of the url
    m_defaultCmd(*this, requestType, verb, tail_complete);
    return true;
  }
  // We now know that the URL contains at least one character.  And,
  // if the first character is a slash,  there's more after it.
  if (verb[0] == '/')
  {
    char i;
    char *qm_loc;
    int verb_len;
    int qm_offset;
    // Skip over the leading "/",  because it makes the code more
    // efficient and easier to understand.
    verb++;
    // Look for a "?" separating the filename part of the URL from the
    // parameters.  If it's not there, compare to the whole URL.
    qm_loc = strchr(verb, '?');
    verb_len = (qm_loc == NULL) ? strlen(verb) : (qm_loc - verb);
    qm_offset = (qm_loc == NULL) ? 0 : 1;
    for (i = 0; i < m_cmdCount; ++i)
    {
      if ((verb_len == strlen(m_commands[i].verb))
          && (strncmp(verb, m_commands[i].verb, verb_len) == 0))
      {
        // Skip over the "verb" part of the URL (and the question
        // mark, if present) when passing it to the "action" routine
        m_commands[i].cmd(*this, requestType,
        verb + verb_len + qm_offset,
        tail_complete);
        return true;
      }
    }
    // Check if UrlPathCommand is assigned.
    if (m_urlPathCmd != NULL)
    {
      // Initialize with null bytes, so number of parts can be determined.
      char *url_path[WEBDUINO_URL_PATH_COMMAND_LENGTH] = {0};
      int part = 0;

      // URL path should be terminated with null byte.
      *(verb + verb_len) = 0;

      // First URL path part is at the start of verb.
      url_path[part++] = verb;
      // Replace all slashes ('/') with a null byte so every part of the URL
      // path is a seperate string. Add every char following a '/' as a new
      // part of the URL, even if that char is a '/' (which will be replaced
      // with a null byte).
      for (char * p = verb; p < verb + verb_len; p++)
      {
        if (*p == '/')
        {
          *p = 0;
          url_path[part++] = p + 1;
          // Don't try to assign out of array bounds.
          if (part == WEBDUINO_URL_PATH_COMMAND_LENGTH) break;
        }
      }
      m_urlPathCmd(*this, requestType, url_path,
                   verb + verb_len + qm_offset, tail_complete);
      return true;
    }
  }
  return false;
}

// processConnection with a default buffer
void WebServer::processConnection()
{
  char request[WEBDUINO_DEFAULT_REQUEST_LENGTH];
  int  request_len = WEBDUINO_DEFAULT_REQUEST_LENGTH;
  processConnection(request, &request_len);
}

void WebServer::processConnection(char *buff, int *bufflen)
{
  int urlPrefixLen = strlen(m_urlPrefix);

  m_client = m_server.available();

  if (m_client) {
    m_readingContent = false;
    buff[0] = 0;
    ConnectionType requestType = INVALID;
#if WEBDUINO_SERIAL_DEBUGGING > 1
    Serial.println("*** checking request ***");
#endif
    getRequest(requestType, buff, bufflen);
#if WEBDUINO_SERIAL_DEBUGGING > 1
    Serial.print("*** requestType = ");
    Serial.print((int)requestType);
    Serial.print(", request = \"");
    Serial.print(buff);
    Serial.println("\" ***");
#endif

    // don't even look further at invalid requests.
    // this is done to prevent Webduino from hanging
    // - when there are illegal requests,
    // - when someone contacts it through telnet rather than proper HTTP,
    // - etc.
    if (requestType != INVALID)
    {
      processHeaders();
#if WEBDUINO_SERIAL_DEBUGGING > 1
      Serial.println("*** headers complete ***");
#endif

      if (strcmp(buff, "/robots.txt") == 0)
      {
        noRobots(requestType);
      }
      else if (strcmp(buff, "/favicon.ico") == 0)
      {
        favicon(requestType);
      }
    }
    // Only try to dispatch command if request type and prefix are correct.
    // Fix by quarencia.
    if (requestType == INVALID ||
        strncmp(buff, m_urlPrefix, urlPrefixLen) != 0)
    {
      m_failureCmd(*this, requestType, buff, (*bufflen) >= 0);
    }
    else if (!dispatchCommand(requestType, buff + urlPrefixLen,
             (*bufflen) >= 0))
    {
      m_failureCmd(*this, requestType, buff, (*bufflen) >= 0);
    }

#if WEBDUINO_SERIAL_DEBUGGING > 1
    Serial.println("*** stopping connection ***");
#endif
    reset();
  }
}

bool WebServer::checkCredentials(const char authCredentials[45])
{
  char basic[7] = "Basic ";
  if((0 == strncmp(m_authCredentials,basic,6)) && 
     (0 == strcmp(authCredentials, m_authCredentials + 6))) return true;
  return false;
}

void WebServer::httpFail()
{
  P(failMsg) =
    "HTTP/1.0 400 Bad Request" CRLF
    WEBDUINO_SERVER_HEADER
    "Content-Type: text/html" CRLF
    CRLF
    WEBDUINO_FAIL_MESSAGE;

  printP(failMsg);
}

void WebServer::defaultFailCmd(WebServer &server,
                               WebServer::ConnectionType type,
                               char *url_tail,
                               bool tail_complete)
{
  server.httpFail();
}

void WebServer::noRobots(ConnectionType type)
{
  httpSuccess("text/plain");
  if (type != HEAD)
  {
    P(allowNoneMsg) = "User-agent: *" CRLF "Disallow: /" CRLF;
    printP(allowNoneMsg);
  }
}

void WebServer::favicon(ConnectionType type)
{
  httpSuccess("image/x-icon","Cache-Control: max-age=31536000\r\n");
  if (type != HEAD)
  {
    P(faviconIco) = WEBDUINO_FAVICON_DATA;
    writeP(faviconIco, sizeof(faviconIco));
  }
}

void WebServer::httpUnauthorized()
{
  P(failMsg) =
    "HTTP/1.0 401 Authorization Required" CRLF
    WEBDUINO_SERVER_HEADER
    "Content-Type: text/html" CRLF
    "WWW-Authenticate: Basic realm=\"" WEBDUINO_AUTH_REALM "\"" CRLF
    CRLF
    WEBDUINO_AUTH_MESSAGE;

  printP(failMsg);
}

void WebServer::httpServerError()
{
  P(failMsg) =
    "HTTP/1.0 500 Internal Server Error" CRLF
    WEBDUINO_SERVER_HEADER
    "Content-Type: text/html" CRLF
    CRLF
    WEBDUINO_SERVER_ERROR_MESSAGE;

  printP(failMsg);
}

void WebServer::httpNoContent()
{
  P(noContentMsg) =
    "HTTP/1.0 204 NO CONTENT" CRLF
    WEBDUINO_SERVER_HEADER
    CRLF
    CRLF;

  printP(noContentMsg);
}

void WebServer::httpSuccess(const char *contentType,
                            const char *extraHeaders)
{
  P(successMsg1) =
    "HTTP/1.0 200 OK" CRLF
    WEBDUINO_SERVER_HEADER
    "Access-Control-Allow-Origin: *" CRLF
    "Content-Type: ";

  printP(successMsg1);
  print(contentType);
  printCRLF();
  if (extraHeaders)
    print(extraHeaders);
  printCRLF();
}

void WebServer::httpSeeOther(const char *otherURL)
{
  P(seeOtherMsg) =
    "HTTP/1.0 303 See Other" CRLF
    WEBDUINO_SERVER_HEADER
    "Location: ";

  printP(seeOtherMsg);
  print(otherURL);
  printCRLF();
  printCRLF();
}

int WebServer::read()
{
  if (m_client == NULL)
    return -1;

  if (m_pushbackDepth == 0)
  {
    unsigned long timeoutTime = millis() + WEBDUINO_READ_TIMEOUT_IN_MS;

    while (m_client.connected())
    {
      // stop reading the socket early if we get to content-length
      // characters in the POST.  This is because some clients leave
      // the socket open because they assume HTTP keep-alive.
      if (m_readingContent)
      {
        if (m_contentLength == 0)
        {
#if WEBDUINO_SERIAL_DEBUGGING > 1
          Serial.println("\n*** End of content, terminating connection");
#endif
          return -1;
        }
      }

      int ch = m_client.read();

      // if we get a character, return it, otherwise continue in while
      // loop, checking connection status
      if (ch != -1)
      {
        // count character against content-length
        if (m_readingContent)
        {
          --m_contentLength;
        }

#if WEBDUINO_SERIAL_DEBUGGING
        if (ch == '\r')
          Serial.print("<CR>");
        else if (ch == '\n')
          Serial.println("<LF>");
        else
          Serial.print((char)ch);
#endif
        return ch;
      }
      else
      {
        unsigned long now = millis();
        if (now > timeoutTime)
        {
          // connection timed out, destroy client, return EOF
#if WEBDUINO_SERIAL_DEBUGGING
          Serial.println("*** Connection timed out");
#endif
          reset();
          return -1;
        }
      }
    }

    // connection lost, return EOF
#if WEBDUINO_SERIAL_DEBUGGING
    Serial.println("*** Connection lost");
#endif
    return -1;
  }
  else
    return m_pushback[--m_pushbackDepth];
}

void WebServer::push(int ch)
{
  // don't allow pushing EOF
  if (ch == -1)
    return;

  m_pushback[m_pushbackDepth++] = ch;
  // can't raise error here, so just replace last char over and over
  if (m_pushbackDepth == SIZE(m_pushback))
    m_pushbackDepth = SIZE(m_pushback) - 1;
}

void WebServer::reset()
{
  m_pushbackDepth = 0;
  m_client.flush();
  m_client.stop();
}

bool WebServer::expect(const char *str)
{
  const char *curr = str;
  while (*curr != 0)
  {
    int ch = read();
    if (ch != *curr++)
    {
      // push back ch and the characters we accepted
      push(ch);
      while (--curr != str)
        push(curr[-1]);
      return false;
    }
  }
  return true;
}

bool WebServer::readInt(int &number)
{
  bool negate = false;
  bool gotNumber = false;
  int ch;
  number = 0;

  // absorb whitespace
  do
  {
    ch = read();
  } while (ch == ' ' || ch == '\t');

  // check for leading minus sign
  if (ch == '-')
  {
    negate = true;
    ch = read();
  }

  // read digits to update number, exit when we find non-digit
  while (ch >= '0' && ch <= '9')
  {
    gotNumber = true;
    number = number * 10 + ch - '0';
    ch = read();
  }

  push(ch);
  if (negate)
    number = -number;
  return gotNumber;
}

void WebServer::readHeader(char *value, int valueLen)
{
  int ch;
  memset(value, 0, valueLen);
  --valueLen;

  // absorb whitespace
  do
  {
    ch = read();
  } while (ch == ' ' || ch == '\t');

  // read rest of line
  do
  {
    if (valueLen > 1)
    {
      *value++=ch;
      --valueLen;
    }
    ch = read();
  } while (ch != '\r');
  push(ch);
}

bool WebServer::readPOSTparam(char *name, int nameLen,
                              char *value, int valueLen)
{
  // assume name is at current place in stream
  int ch;
  // to not to miss the last parameter
  bool foundSomething = false;

  // clear out name and value so they'll be NUL terminated
  memset(name, 0, nameLen);
  memset(value, 0, valueLen);

  // decrement length so we don't write into NUL terminator
  --nameLen;
  --valueLen;

  while ((ch = read()) != -1)
  {
    foundSomething = true;
    if (ch == '+')
    {
      ch = ' ';
    }
    else if (ch == '=')
    {
      /* that's end of name, so switch to storing in value */
      nameLen = 0;
      continue;
    }
    else if (ch == '&')
    {
      /* that's end of pair, go away */
      return true;
    }
    else if (ch == '%')
    {
      /* handle URL encoded characters by converting back to original form */
      int ch1 = read();
      int ch2 = read();
      if (ch1 == -1 || ch2 == -1)
        return false;
      char hex[3] = { ch1, ch2, 0 };
      ch = strtoul(hex, NULL, 16);
    }

    // output the new character into the appropriate buffer or drop it if
    // there's no room in either one.  This code will malfunction in the
    // case where the parameter name is too long to fit into the name buffer,
    // but in that case, it will just overflow into the value buffer so
    // there's no harm.
    if (nameLen > 0)
    {
      *name++ = ch;
      --nameLen;
    }
    else if (valueLen > 0)
    {
      *value++ = ch;
      --valueLen;
    }
  }

  if (foundSomething)
  {
    // if we get here, we have one last parameter to serve
    return true;
  }
  else
  {
    // if we get here, we hit the end-of-file, so POST is over and there
    // are no more parameters
    return false;
  }
}

/* Retrieve a parameter that was encoded as part of the URL, stored in
 * the buffer pointed to by *tail.  tail is updated to point just past
 * the last character read from the buffer. */
URLPARAM_RESULT WebServer::nextURLparam(char **tail, char *name, int nameLen,
                                        char *value, int valueLen)
{
  // assume name is at current place in stream
  char ch, hex[3];
  URLPARAM_RESULT result = URLPARAM_OK;
  char *s = *tail;
  bool keep_scanning = true;
  bool need_value = true;

  // clear out name and value so they'll be NUL terminated
  memset(name, 0, nameLen);
  memset(value, 0, valueLen);

  if (*s == 0)
    return URLPARAM_EOS;
  // Read the keyword name
  while (keep_scanning)
  {
    ch = *s++;
    switch (ch)
    {
    case 0:
      s--;  // Back up to point to terminating NUL
      // Fall through to "stop the scan" code
    case '&':
      /* that's end of pair, go away */
      keep_scanning = false;
      need_value = false;
      break;
    case '+':
      ch = ' ';
      break;
    case '%':
      /* handle URL encoded characters by converting back
       * to original form */
      if ((hex[0] = *s++) == 0)
      {
        s--;        // Back up to NUL
        keep_scanning = false;
        need_value = false;
      }
      else
      {
        if ((hex[1] = *s++) == 0)
        {
          s--;  // Back up to NUL
          keep_scanning = false;
          need_value = false;
        }
        else
        {
          hex[2] = 0;
          ch = strtoul(hex, NULL, 16);
        }
      }
      break;
    case '=':
      /* that's end of name, so switch to storing in value */
      keep_scanning = false;
      break;
    }


    // check against 1 so we don't overwrite the final NUL
    if (keep_scanning && (nameLen > 1))
    {
      *name++ = ch;
      --nameLen;
    }
    else
      result = URLPARAM_NAME_OFLO;
  }

  if (need_value && (*s != 0))
  {
    keep_scanning = true;
    while (keep_scanning)
    {
      ch = *s++;
      switch (ch)
      {
      case 0:
        s--;  // Back up to point to terminating NUL
              // Fall through to "stop the scan" code
      case '&':
        /* that's end of pair, go away */
        keep_scanning = false;
        need_value = false;
        break;
      case '+':
        ch = ' ';
        break;
      case '%':
        /* handle URL encoded characters by converting back to original form */
        if ((hex[0] = *s++) == 0)
        {
          s--;  // Back up to NUL
          keep_scanning = false;
          need_value = false;
        }
        else
        {
          if ((hex[1] = *s++) == 0)
          {
            s--;  // Back up to NUL
            keep_scanning = false;
            need_value = false;
          }
          else
          {
            hex[2] = 0;
            ch = strtoul(hex, NULL, 16);
          }

        }
        break;
      }


      // check against 1 so we don't overwrite the final NUL
      if (keep_scanning && (valueLen > 1))
      {
        *value++ = ch;
        --valueLen;
      }
      else
        result = (result == URLPARAM_OK) ?
          URLPARAM_VALUE_OFLO :
          URLPARAM_BOTH_OFLO;
    }
  }
  *tail = s;
  return result;
}



// Read and parse the first line of the request header.
// The "command" (GET/HEAD/POST) is translated into a numeric value in type.
// The URL is stored in request,  up to the length passed in length
// NOTE 1: length must include one byte for the terminating NUL.
// NOTE 2: request is NOT checked for NULL,  nor length for a value < 1.
// Reading stops when the code encounters a space, CR, or LF.  If the HTTP
// version was supplied by the client,  it will still be waiting in the input
// stream when we exit.
//
// On return, length contains the amount of space left in request.  If it's
// less than 0,  the URL was longer than the buffer,  and part of it had to
// be discarded.

void WebServer::getRequest(WebServer::ConnectionType &type,
                           char *request, int *length)
{
  --*length; // save room for NUL

  type = INVALID;

  // store the HTTP method line of the request
  if (expect("GET "))
    type = GET;
  else if (expect("HEAD "))
    type = HEAD;
  else if (expect("POST "))
    type = POST;
  else if (expect("PUT "))
    type = PUT;
  else if (expect("DELETE "))
    type = DELETE;
  else if (expect("PATCH "))
    type = PATCH;

  // if it doesn't start with any of those, we have an unknown method
  // so just get out of here
  else
    return;

  int ch;
  while ((ch = read()) != -1)
  {
    // stop storing at first space or end of line
    if (ch == ' ' || ch == '\n' || ch == '\r')
    {
      break;
    }
    if (*length > 0)
    {
      *request = ch;
      ++request;
    }
    --*length;
  }
  // NUL terminate
  *request = 0;
}

void WebServer::processHeaders()
{
  // look for three things: the Content-Length header, the Authorization 
  // header, and the double-CRLF that ends the headers.

  // empty the m_authCredentials before every run of this function.
  // otherwise users who don't send an Authorization header would be treated
  // like the last user who tried to authenticate (possibly successful)
  m_authCredentials[0]=0;

  while (1)
  {
    if (expect("Content-Length:"))
    {
      readInt(m_contentLength);
#if WEBDUINO_SERIAL_DEBUGGING > 1
      Serial.print("\n*** got Content-Length of ");
      Serial.print(m_contentLength);
      Serial.print(" ***");
#endif
      continue;
    }

    if (expect("Authorization:"))
    {
      readHeader(m_authCredentials,51);
#if WEBDUINO_SERIAL_DEBUGGING > 1
      Serial.print("\n*** got Authorization: of ");
      Serial.print(m_authCredentials);
      Serial.print(" ***");
#endif
      continue;
    }

    if (expect(CRLF CRLF))
    {
      m_readingContent = true;
      return;
    }

    // no expect checks hit, so just absorb a character and try again
    if (read() == -1)
    {
      return;
    }
  }
}

void WebServer::outputCheckboxOrRadio(const char *element, const char *name,
                                      const char *val, const char *label,
                                      bool selected)
{
  P(cbPart1a) = "<label><input type='";
  P(cbPart1b) = "' name='";
  P(cbPart2) = "' value='";
  P(cbPart3) = "' ";
  P(cbChecked) = "checked ";
  P(cbPart4) = "/> ";
  P(cbPart5) = "</label>";

  printP(cbPart1a);
  print(element);
  printP(cbPart1b);
  print(name);
  printP(cbPart2);
  print(val);
  printP(cbPart3);
  if (selected)
    printP(cbChecked);
  printP(cbPart4);
  print(label);
  printP(cbPart5);
}

void WebServer::checkBox(const char *name, const char *val,
                         const char *label, bool selected)
{
  outputCheckboxOrRadio("checkbox", name, val, label, selected);
}

void WebServer::radioButton(const char *name, const char *val,
                            const char *label, bool selected)
{
  outputCheckboxOrRadio("radio", name, val, label, selected);
}

uint8_t WebServer::available(){
  return m_server.available();
}

#endif // WEBDUINO_NO_IMPLEMENTATION

#endif // WEBDUINO_H_