httpd.c

/****************************************************************************
 * apps/netutils/webserver/httpd.c
 *
 * SPDX-License-Identifier: BSD-3-Clause
 * SPDX-FileCopyrightText: 2011-2012 Gregory Nutt. All rights reserved.
 * SPDX-FileCopyrightText: 2007-2009 Gregory Nutt. All rights reserved.
 * SPDX-FileCopyrightText: 2004 Adam Dunkels. All rights reserved.
 * SPDX-FileContributor: Gregory Nutt <gnutt@nuttx.org>
 * SPDX-FileContributor: Adam Dunkels <adam@dunkels.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/param.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#ifndef CONFIG_NETUTILS_HTTPD_SINGLECONNECT
#  include <pthread.h>
#endif

#include <arpa/inet.h>

#include "netutils/netlib.h"
#include "netutils/httpd.h"

#include "httpd.h"
#include "httpd_cgi.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#if !defined(CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE) && \
    defined(CONFIG_NETUTILS_HTTPD_SENDFILE)
#  error "Script support and CONFIG_NETUTILS_HTTPD_SENDFILE are mutually exclusive"
#endif

#if defined(CONFIG_NETUTILS_HTTPD_SENDFILE) && \
    defined(CONFIG_NETUTILS_HTTPD_MMAP)
#  error "CONFIG_NETUTILS_HTTPD_SENDFILE and CONFIG_NETUTILS_HTTPD_MMAP are mutually exclusive"
#endif

#define ISO_NL      0x0a
#define ISO_SPACE   0x20
#define ISO_BANG    0x21
#define ISO_PERCENT 0x25
#define ISO_PERIOD  0x2e
#define ISO_SLASH   0x2f
#define ISO_COLON   0x3a

#ifndef CONFIG_NETUTILS_HTTPD_PATH
#  define CONFIG_NETUTILS_HTTPD_PATH "/mnt"
#endif

#ifndef CONFIG_NETUTILS_HTTPD_ERRPATH
#  define CONFIG_NETUTILS_HTTPD_ERRPATH ""
#endif

/* The correct way to disable receive timeout errors is by setting the
 * timeout to zero.
 */

#ifndef CONFIG_NETUTILS_HTTPD_TIMEOUT
#  define CONFIG_NETUTILS_HTTPD_TIMEOUT 0
#endif

/* If timeouts are not enabled, then keep-alive is disabled.  This is to
 * prevent a rogue HTTP client from blocking the httpd indefinitely.
 */

#if !defined(CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE)
#  if CONFIG_NETUTILS_HTTPD_TIMEOUT == 0
#    define CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
#  endif
#endif

#ifdef CONFIG_NETUTILS_HTTPD_CLASSIC
#  ifndef CONFIG_NETUTILS_HTTPD_INDEX
#    ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
#      define CONFIG_NETUTILS_HTTPD_INDEX "index.shtml"
#    else
#      define CONFIG_NETUTILS_HTTPD_INDEX "index.html"
#    endif
#  endif
#endif

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

static int httpd_open(const char *name, struct httpd_fs_file *file)
{
#if defined(CONFIG_NETUTILS_HTTPD_CLASSIC)
  return httpd_fs_open(name, file);
#elif defined(CONFIG_NETUTILS_HTTPD_MMAP)
  return httpd_mmap_open(name, file);
#elif defined(CONFIG_NETUTILS_HTTPD_SENDFILE)
  return httpd_sendfile_open(name, file);
#else
#  error "No file handling method"
#endif
}

static int httpd_openindex(struct httpd_state *pstate)
{
  int ret;
  size_t z;

  z = strlen(pstate->ht_filename);
  if (z > 0 && pstate->ht_filename[z - 1] == '/')
    {
      pstate->ht_filename[--z] = '\0';
    }

  ret = httpd_open(pstate->ht_filename, &pstate->ht_file);
#if defined(CONFIG_NETUTILS_HTTPD_SENDFILE) || \
    defined(CONFIG_NETUTILS_HTTPD_MMAP)
#  if defined(CONFIG_NETUTILS_HTTPD_INDEX)
  if (ret == ERROR && errno == EISDIR)
    {
      snprintf(pstate->ht_filename + z,
               sizeof pstate->ht_filename - z, "/%s",
               CONFIG_NETUTILS_HTTPD_INDEX);

      ret = httpd_open(pstate->ht_filename, &pstate->ht_file);
    }
#  endif
#endif

  return ret;
}

static int httpd_close(struct httpd_fs_file *file)
{
#if defined(CONFIG_NETUTILS_HTTPD_CLASSIC)
  return OK;
#elif defined(CONFIG_NETUTILS_HTTPD_MMAP)
  return httpd_mmap_close(file);
#elif defined(CONFIG_NETUTILS_HTTPD_SENDFILE)
  return httpd_sendfile_close(file);
#else
#  error "No file handling method"
#endif
}

#ifdef CONFIG_NETUTILS_HTTPD_DUMPBUFFER
static void httpd_dumpbuffer(FAR const char *msg, FAR const char *buffer,
                             unsigned int nbytes)
{
  /* CONFIG_DEBUG_FEATURES, CONFIG_DEBUG_INFO, and CONFIG_DEBUG_NET have to
   * be defined or the following does nothing.
   */

  ninfodumpbuffer(msg, (FAR const uint8_t *)buffer, nbytes);
}
#else
#  define httpd_dumpbuffer(msg,buffer,nbytes)
#endif

#ifdef CONFIG_NETUTILS_HTTPD_DUMPPSTATE
static void httpd_dumppstate(struct httpd_state *pstate, const char *msg)
{
#if defined(CONFIG_DEBUG_FEATURES) && defined(CONFIG_DEBUG_INFO) && defined(CONFIG_DEBUG_NET)
  ninfo("[%d] pstate(%p): [%s]\n", pstate->ht_sockfd, pstate, msg);
  ninfo("  filename:      [%s]\n", pstate->ht_filename);
  ninfo("  htfile len:    %d\n", pstate->ht_file.len);
  ninfo("  sockfd:        %d\n", pstate->ht_sockfd);
#ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
  ninfo("  scriptptr:     %p\n", pstate->ht_scriptptr);
  ninfo("  scriptlen:     %d\n", pstate->ht_scriptlen);
#endif
  ninfo("  sndlen:        %d\n", pstate->ht_sndlen);
#endif
}
#else
#  define httpd_dumppstate(pstate, msg)
#endif

#ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
static void next_scriptstate(struct httpd_state *pstate)
{
  char *p;
  p = strchr(pstate->ht_scriptptr, ISO_NL) + 1;
  pstate->ht_scriptlen -= (unsigned short)(p - pstate->ht_scriptptr);
  pstate->ht_scriptptr  = p;
}
#endif

#ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
static int handle_script(struct httpd_state *pstate)
{
  int len;
  char *ptr;
  int status;
  bool chunked_http_tx = 0;

#if defined(CONFIG_NETUTILS_HTTPD_ENABLE_CHUNKED_ENCODING)
  chunked_http_tx = pstate->ht_chunked;
#endif

  while (pstate->ht_file.len > 0)
    {
      /* Check if we should start executing a script */

      if (*pstate->ht_file.data == ISO_PERCENT &&
          *(pstate->ht_file.data + 1) == ISO_BANG)
        {
          pstate->ht_scriptptr = pstate->ht_file.data + 3;
          pstate->ht_scriptlen = pstate->ht_file.len - 3;
          if (*(pstate->ht_scriptptr - 1) == ISO_COLON)
            {
              if (httpd_open(pstate->ht_scriptptr + 1,
                             &pstate->ht_file) != OK)
                {
                  return ERROR;
                }

              status = httpd_send_datachunk(pstate->ht_sockfd,
                                            pstate->ht_file.data,
                                            pstate->ht_file.len,
                                            chunked_http_tx);
              DEBUGASSERT(status >= 0);
              UNUSED(status);

              httpd_close(&pstate->ht_file);
            }
          else
            {
              httpd_cgifunction f;

              f = httpd_cgi(pstate->ht_scriptptr);
              if (f != NULL)
                {
                  f(pstate, pstate->ht_scriptptr);
                }
            }

          next_scriptstate(pstate);

          /* The script is over, so we reset the pointers and continue
           * sending the rest of the file
           */

          pstate->ht_file.data = pstate->ht_scriptptr;
          pstate->ht_file.len  = pstate->ht_scriptlen;
        }
      else
        {
          /* See if we find the start of script marker in the block of HTML
           * to be sent
           */

          if (pstate->ht_file.len > HTTPD_IOBUFFER_SIZE)
            {
              len = HTTPD_IOBUFFER_SIZE;
            }
          else
            {
              len = pstate->ht_file.len;
            }

          if (*pstate->ht_file.data == ISO_PERCENT)
            {
              ptr = strchr(pstate->ht_file.data + 1, ISO_PERCENT);
            }
          else
            {
              ptr = strchr(pstate->ht_file.data, ISO_PERCENT);
            }

          if (ptr != NULL && ptr != pstate->ht_file.data)
            {
              len = (int)(ptr - pstate->ht_file.data);
              if (len >= HTTPD_IOBUFFER_SIZE)
                {
                  len = HTTPD_IOBUFFER_SIZE;
                }
            }

          status = httpd_send_datachunk(pstate->ht_sockfd,
                                        pstate->ht_file.data,
                                        len, chunked_http_tx);
          DEBUGASSERT(status >= 0);
          UNUSED(status);

          pstate->ht_file.data += len;
          pstate->ht_file.len  -= len;
        }
    }

#if defined(CONFIG_NETUTILS_HTTPD_ENABLE_CHUNKED_ENCODING)
  /* Chunked encoding terminator */

  status = httpd_send_datachunk(pstate->ht_sockfd, 0, 0, chunked_http_tx);
  DEBUGASSERT(status >= 0);
  UNUSED(status);
#endif

  return OK;
}
#endif

static int send_chunk(struct httpd_state *pstate, const char *buf, int len)
{
  int ret;

  do
    {
      httpd_dumpbuffer("Outgoing chunk", buf, len);
      ret = send(pstate->ht_sockfd, buf, len, 0);
      if (ret < 0)
        {
          return ERROR;
        }

      buf += ret;
      len -= ret;
    }
  while (len > 0);

  return OK;
}

static int httpd_senderror(struct httpd_state *pstate, int status)
{
  int ret;
  char msg[10 + 1];

  ninfo("[%d] sending error '%d'\n", pstate->ht_sockfd, status);

  if (status < 400 || status >= 600)
    {
      status = 500;
    }

#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
  if (status != 404)
    {
      pstate->ht_keepalive = false;
    }
#endif

  snprintf(pstate->ht_filename, sizeof pstate->ht_filename,
           "%s/%d.html", CONFIG_NETUTILS_HTTPD_ERRPATH, status);

  ret = httpd_openindex(pstate);

  if (httpd_send_headers(pstate, status,
                   ret == OK ? pstate->ht_file.len : sizeof msg - 1) != OK)
    {
      return ERROR;
    }

  if (ret != OK)
    {
      snprintf(msg, sizeof msg, "Error %d\n", status);

      ret = send_chunk(pstate, msg, sizeof msg - 1);
    }
  else
    {
#ifdef CONFIG_NETUTILS_HTTPD_CLASSIC
      ret = send_chunk(pstate, pstate->ht_file.data, pstate->ht_file.len);
#else
#ifdef CONFIG_NETUTILS_HTTPD_SENDFILE
      ret = httpd_sendfile_send(pstate->ht_sockfd, &pstate->ht_file);
#endif
#endif

      httpd_close(&pstate->ht_file);
    }

  return ret;
}

static int httpd_sendfile(struct httpd_state *pstate)
{
#ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
  char *ptr;
#endif
  int ret = ERROR;

  pstate->ht_sndlen = 0;

  ninfo("[%d] sending file '%s'\n", pstate->ht_sockfd, pstate->ht_filename);

#ifdef CONFIG_NETUTILS_HTTPD_CGIPATH
    {
      httpd_cgifunction f;

      f = httpd_cgi(pstate->ht_filename);
      if (f != NULL)
        {
#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
          pstate->ht_keepalive = false;
#endif
          f(pstate, pstate->ht_filename);

          return OK;
        }
    }
#endif

  if (httpd_openindex(pstate) != OK)
    {
      nwarn("WARNING: [%d] '%s' not found\n",
           pstate->ht_sockfd, pstate->ht_filename);
      return httpd_senderror(pstate, 404);
    }

#ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
  ptr = strchr(pstate->ht_filename, ISO_PERIOD);
  if (ptr != NULL &&
      strncmp(ptr, ".shtml", strlen(".shtml")) == 0)
    {
#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
      pstate->ht_keepalive = false;
#endif
      if (httpd_send_headers(pstate, 200, -1) != OK)
        {
          goto done;
        }

      ret = handle_script(pstate);
      goto done;
    }
#endif

#ifdef CONFIG_NETUTILS_HTTPD_DIRLIST
  if (httpd_send_headers(pstate, 200, -1) != OK)
    {
      goto done;
    }
#else
  if (httpd_send_headers(pstate, pstate->ht_file.len == 0 ? 204 : 200,
                         pstate->ht_file.len) != OK)
    {
      goto done;
    }
#endif

#ifdef CONFIG_NETUTILS_HTTPD_CLASSIC
  ret = send_chunk(pstate, pstate->ht_file.data, pstate->ht_file.len);
#else
#ifdef CONFIG_NETUTILS_HTTPD_SENDFILE
  ret = httpd_sendfile_send(pstate->ht_sockfd, &pstate->ht_file);
#endif
#endif

done:
  httpd_close(&pstate->ht_file);
  return ret;
}

static inline int httpd_parse(struct httpd_state *pstate)
{
  char *o;

  enum
    {
      STATE_METHOD,
      STATE_HEADER,
      STATE_BODY
    } state;

  state = STATE_METHOD;
  o = pstate->ht_buffer;

  do
    {
      char *start;
      char *end;

      if (o == pstate->ht_buffer + sizeof pstate->ht_buffer)
        {
          nerr("ERROR: ht_buffer overflow\n");
          return 413;
        }

        {
          ssize_t r;

          r = recv(pstate->ht_sockfd, o,
            sizeof pstate->ht_buffer - (o - pstate->ht_buffer), 0);
          if (r == 0)
            {
              nwarn("WARNING: [%d] connection lost\n", pstate->ht_sockfd);
              return ERROR;
            }

#if CONFIG_NETUTILS_HTTPD_TIMEOUT > 0
          if (r == -1 && errno == EWOULDBLOCK)
            {
              nwarn("WARNING: recv timeout\n");
              return 408;
            }
#endif

          if (r == -1)
            {
              nerr("ERROR: [%d] recv failed: %d\n",
                   pstate->ht_sockfd, errno);
              return 400;
            }

          o += r;
        }

      /* Here o marks the end of the total block currently awaiting
       * processing.  There may be multiple lines in a block; next we deal
       * with each in turn.
       */

      for (start = pstate->ht_buffer;
           (end = memchr(start, '\r', o - start)), end != NULL;
           start = end)
        {
          *end = '\0';
          end++;

          /* Here start and end are a single line within the current block */

          httpd_dumpbuffer("Incoming HTTP line", start, end - start);

          if (*end != '\n')
            {
              nwarn("WARNING: expected CRLF\n");
              return 400;
            }

          end++;

          switch (state)
          {
          char *v;

          case STATE_METHOD:
            if (0 != strncmp(start, "GET ", 4))
              {
                nwarn("WARNING: method not supported\n");
                return 501;
              }

            start += 4;
            v = start + strcspn(start, " ");

            if (0 != strcmp(v, " HTTP/1.0") && 0 != strcmp(v, " HTTP/1.1"))
              {
                nwarn("WARNING: HTTP version not supported\n");
                return 505;
              }

            /* TODO: url decoding */

            if (v - start >= sizeof pstate->ht_filename)
              {
                nerr("ERROR: ht_filename overflow\n");
                return 414;
              }

            *v = '\0';
            strlcpy(pstate->ht_filename, start, sizeof(pstate->ht_filename));
            state = STATE_HEADER;
            break;

          case STATE_HEADER:
            if (*start == '\0')
              {
                state = STATE_BODY;
                break;
              }

            v = start + strcspn(start, ":");
            if (*v != '\0')
              {
                *v = '\0', v++;
                v += strspn(v, ": ");
              }

            if (*start == '\0' || *v == '\0')
              {
                nwarn("WARNING: header parse error\n");
                return 400;
              }

            ninfo("[%d] Request header %s: %s\n",
                  pstate->ht_sockfd, start, v);

            if (0 == strcasecmp(start, "Content-Length") && 0 != atoi(v))
              {
                nwarn("WARNING: non-zero request length\n");
                return 413;
              }
#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
            else if (0 == strcasecmp(start, "Connection") &&
                     0 == strcasecmp(v, "keep-alive"))
              {
                pstate->ht_keepalive = true;
              }
#endif
            break;

          case STATE_BODY:

            /* Not implemented */

            break;
          }
       }

      /* Shuffle down for the next block */

      memmove(pstate->ht_buffer, start, o - start);
      o -= (start - pstate->ht_buffer);
    }
  while (state != STATE_BODY);

#ifdef CONFIG_NETUTILS_HTTPD_CLASSIC
  if (0 == strcmp(pstate->ht_filename, "/"))
    {
      strlcpy(pstate->ht_filename, "/" CONFIG_NETUTILS_HTTPD_INDEX,
              sizeof(pstate->ht_filename));
    }
#endif

  ninfo("[%d] Filename: %s\n", pstate->ht_sockfd, pstate->ht_filename);

  return 200;
}

/****************************************************************************
 * Name: httpd_handler
 *
 * Description:
 *   Each time a new connection to port 80 is made, a new thread is created
 *   that begins at this entry point.  There should be exactly one argument
 *   and it should be the socket descriptor (+1).
 *
 ****************************************************************************/

static void *httpd_handler(void *arg)
{
  struct httpd_state *pstate =
    (struct httpd_state *)malloc(sizeof(struct httpd_state));
  int sockfd = (intptr_t)arg;

  ninfo("[%d] Started\n", sockfd);

  /* Verify that the state structure was successfully allocated */

  if (pstate)
    {
      int status;

      /* Re-initialize the thread state structure */

      memset(pstate, 0, sizeof(struct httpd_state));
      pstate->ht_sockfd = sockfd;

#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
      do
        {
          pstate->ht_keepalive = false;
#endif
          /* Then handle the next httpd command */

          status = httpd_parse(pstate);
          if (status >= 400)
            {
              httpd_senderror(pstate, status);
            }
          else
            {
              httpd_sendfile(pstate);
            }

#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
        }
      while (pstate->ht_keepalive);
#endif

      /* End of command processing -- Clean up and exit */

      free(pstate);
    }

  /* Exit the task */

  ninfo("[%d] Exiting\n", sockfd);
  close(sockfd);
  return NULL;
}

#ifdef CONFIG_NETUTILS_HTTPD_SINGLECONNECT
static void single_server(uint16_t portno, pthread_startroutine_t handler,
                          int stacksize)
{
  struct sockaddr_in myaddr;
  socklen_t addrlen;
  int listensd;
  int acceptsd;
#ifdef CONFIG_NET_SOLINGER
  struct linger ling;
#endif
#if CONFIG_NETUTILS_HTTPD_TIMEOUT > 0
  struct timeval tv;
#endif

  listensd = netlib_listenon(portno);
  if (listensd < 0)
    {
      return;
    }

  /* Begin serving connections */

  for (; ; )
    {
      addrlen = sizeof(struct sockaddr_in);
      acceptsd = accept4(listensd, (FAR struct sockaddr *)&myaddr, &addrlen,
                         SOCK_CLOEXEC);

      if (acceptsd < 0)
        {
          nerr("ERROR: accept failure: %d\n", errno);
          break;
        }

      ninfo("Connection accepted -- serving sd=%d\n", acceptsd);

      /* Configure to "linger" until all data is sent
       * when the socket is closed
       */

#ifdef CONFIG_NET_SOLINGER
      ling.l_onoff  = 1;
      ling.l_linger = 30;     /* timeout is seconds */
      if (setsockopt(acceptsd, SOL_SOCKET, SO_LINGER, &ling,
                     sizeof(struct linger)) < 0)
        {
          close(acceptsd);
          nerr("ERROR: setsockopt SO_LINGER failure: %d\n", errno);
          break;
        }
#endif

#if CONFIG_NETUTILS_HTTPD_TIMEOUT > 0
      /* Set up a receive timeout */

      tv.tv_sec  = CONFIG_NETUTILS_HTTPD_TIMEOUT;
      tv.tv_usec = 0;
      if (setsockopt(acceptsd, SOL_SOCKET, SO_RCVTIMEO, &tv,
                     sizeof(struct timeval)) < 0)
        {
          close(acceptsd);
          nerr("ERROR: setsockopt SO_RCVTIMEO failure: %d\n", errno);
          break;
        }
#endif

      /* Handle the request. This blocks until complete. */

      handler((FAR void *)acceptsd);
    }

  /* Close the sockets */

  close(acceptsd);
  close(listensd);
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: httpd_init
 ****************************************************************************/

void httpd_init(void)
{
#ifdef CONFIG_NETUTILS_HTTPD_CLASSIC
  httpd_fs_init();
#endif
}

/****************************************************************************
 * Name: httpd_listen
 ****************************************************************************/

int httpd_listen(void)
{
  /* Execute httpd_handler on each connection to port 80 */

#ifdef CONFIG_NETUTILS_HTTPD_SINGLECONNECT
  single_server(HTONS(80), httpd_handler, CONFIG_NETUTILS_HTTPDSTACKSIZE);
#else
  netlib_server(HTONS(80), httpd_handler, CONFIG_NETUTILS_HTTPDSTACKSIZE);
#endif

  /* the server accept loop only returns on errors */

  return ERROR;
}

/****************************************************************************
 * Name: httpd_send_datachunk
 ****************************************************************************/

int httpd_send_datachunk(int sockfd, void *data, int len, bool chunked)
{
  int ret = 0;
#if defined(CONFIG_NETUTILS_HTTPD_ENABLE_CHUNKED_ENCODING)
  char chunked_info[HTTPD_MAX_CHUNKEDLEN];
#endif

#if defined(CONFIG_NETUTILS_HTTPD_ENABLE_CHUNKED_ENCODING)
  /* Chunk prolog */

  if (chunked)
    {
      int chunked_info_len = snprintf(chunked_info, HTTPD_MAX_CHUNKEDLEN,
           "%X\r\n", len);
      ret = send(sockfd, chunked_info, chunked_info_len, 0);
      DEBUGASSERT(ret == chunked_info_len);
    }
#endif

  if (ret >= 0)
    {
      if (len == 0)
        {
          /* Lower layer does not tolerate buf = NULL even if len = 0
           * so just pass a dummy pointer.
           */

          data = &len;
        }

      ret = send(sockfd, data, len, 0);
      DEBUGASSERT(ret == len);
    }

#if defined(CONFIG_NETUTILS_HTTPD_ENABLE_CHUNKED_ENCODING)
  /* Chunk epilog */

  if (ret >= 0)
    {
      if (chunked)
        {
          ret = send(sockfd, "\r\n", 2, 0);
          DEBUGASSERT(ret == 2);
        }
    }
#endif

  return ret;
}

/****************************************************************************
 * Name: httpd_send_headers
 ****************************************************************************/

int httpd_send_headers(struct httpd_state *pstate, int status, int len)
{
  const char *mime;
  const char *ptr;
  char contentlen[HTTPD_MAX_CONTENTLEN] =
    {
      0
    };

  char header[HTTPD_MAX_HEADERLEN];
  int hdrlen;
  int i;

  static const struct
  {
    const char *ext;
    const char *mime;
  }

  a[] =
    {
#ifndef CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE
    {
      "shtml", "text/html"
    },
#endif

    {
      "html",  "text/html"
    },

    {
      "css",   "text/css"
    },

    {
      "txt",   "text/plain"
    },

    {
      "json",  "application/json"
    },

    {
      "js",    "text/javascript"
    },

    {
      "png",   "image/png"
    },

    {
      "gif",   "image/gif"
    },

    {
      "jpeg",  "image/jpeg"
    },

    {
      "jpg",   "image/jpeg"
    },

    {
      "mp3",   "audio/mpeg"
    },
    };

  ptr = strrchr(pstate->ht_filename, ISO_PERIOD);
  if (ptr == NULL)
    {
      mime = "application/octet-stream";
    }
  else
    {
      mime = "text/plain";

      for (i = 0; i < nitems(a); i++)
        {
          if (strncmp(a[i].ext, ptr + 1, strlen(a[i].ext)) == 0)
            {
              mime = a[i].mime;
              break;
            }
        }
    }

#ifdef CONFIG_NETUTILS_HTTPD_DIRLIST
  if (false == httpd_is_file(pstate->ht_filename))
    {
      /* we assume that it's a directory */

      mime = "text/html";
    }
#endif

  if (len >= 0)
    {
      snprintf(contentlen, HTTPD_MAX_CONTENTLEN,
               "Content-Length: %d\r\n", len);
    }
  else
    {
#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
      /* Length unknown ahead of time */

      pstate->ht_keepalive = false;
#endif
#if defined(CONFIG_NETUTILS_HTTPD_ENABLE_CHUNKED_ENCODING)
      /* Turn on chunked encoding */

      snprintf(contentlen, HTTPD_MAX_CONTENTLEN,
               "Transfer-Encoding: chunked\r\n");
      pstate->ht_chunked = true;
#endif
    }

  if (status == 413)
    {
      /* TODO: here we "SHOULD" include a Retry-After header */
    }

  /* Construct the header.
   *
   * REVISIT:  Wouldn't asprintf be a better option than a large stack
   * array?
   */

  hdrlen = snprintf(header, HTTPD_MAX_HEADERLEN,
                    "HTTP/1.0 %d %s\r\n"
#ifndef CONFIG_NETUTILS_HTTPD_SERVERHEADER_DISABLE
                    "Server: uIP/NuttX http://nuttx.org/\r\n"
#endif
                    "Connection: %s\r\n"
                    "Content-type: %s\r\n"
                    "%s"
                    "\r\n",
                    status,
                    status >= 400 ? "Error" : "OK",
#ifndef CONFIG_NETUTILS_HTTPD_KEEPALIVE_DISABLE
                    pstate->ht_keepalive ? "keep-alive" : "close",
#else
                    "close",
#endif
                    mime,
                    contentlen
                    );

  return send_chunk(pstate, header, hdrlen);
}