httpd/genfiles_example/genfiles_example.c

/**
 * @file
 * HTTPD custom file system example for runtime generated files
 *
 * This file demonstrates how to add support for generated files to httpd.
 */

 /*
 * Copyright (c) 2017 Simon Goldschmidt
 * All rights reserved.
 *
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Simon Goldschmidt <goldsimon@gmx.de>
 *
 */

#include "lwip/opt.h"
#include "genfiles_example.h"

#include "lwip/apps/fs.h"
#include "lwip/def.h"
#include "lwip/mem.h"

#include <stdio.h>
#include <string.h>

/** define LWIP_HTTPD_EXAMPLE_GENERATEDFILES to 1 to enable this file system */
#ifndef LWIP_HTTPD_EXAMPLE_GENERATEDFILES
#define LWIP_HTTPD_EXAMPLE_GENERATEDFILES 0
#endif

#if LWIP_HTTPD_EXAMPLE_GENERATEDFILES

#if !LWIP_HTTPD_CUSTOM_FILES
#error This needs LWIP_HTTPD_CUSTOM_FILES
#endif
#if !LWIP_HTTPD_FILE_EXTENSION
#error This needs LWIP_HTTPD_FILE_EXTENSION
#endif
#if !LWIP_HTTPD_DYNAMIC_HEADERS
#error This needs LWIP_HTTPD_DYNAMIC_HEADERS
#endif

/* This is the page we send. It's not generated, as you see.
 * Generating custom things instead of memcpy is left to your imagination :-)
 */
const char generated_html[] =
"<html>\n"
"<head><title>lwIP - A Lightweight TCP/IP Stack</title></head>\n"
" <body bgcolor=\"white\" text=\"black\">\n"
"  <table width=\"100%\">\n"
"   <tr valign=\"top\">\n"
"    <td width=\"80\">\n"
"     <a href=\"http://www.sics.se/\"><img src=\"/img/sics.gif\"\n"
"      border=\"0\" alt=\"SICS logo\" title=\"SICS logo\"></a>\n"
"    </td>\n"
"    <td width=\"500\">\n"
"     <h1>lwIP - A Lightweight TCP/IP Stack</h1>\n"
"     <h2>Generated page</h2>\n"
"     <p>This page might be generated in-memory at runtime</p>\n"
"    </td>\n"
"    <td>\n"
"    &nbsp;\n"
"    </td>\n"
"   </tr>\n"
"  </table>\n"
" </body>\n"
"</html>";


void
genfiles_ex_init(void)
{
  /* nothing to do here yet */
}

int
fs_open_custom(struct fs_file *file, const char *name)
{
  /* this example only provides one file */
  if (!strcmp(name, "/generated.html")) {
    /* initialize fs_file correctly */
    memset(file, 0, sizeof(struct fs_file));
    file->pextension = mem_malloc(sizeof(generated_html));
    if (file->pextension != NULL) {
      /* instead of doing memcpy, you would generate e.g. a JSON here */
      memcpy(file->pextension, generated_html, sizeof(generated_html));
      file->data = (const char *)file->pextension;
      file->len = sizeof(generated_html) - 1; /* don't send the trailing 0 */
      file->index = file->len;
      /* allow persisteng connections */
      file->flags = FS_FILE_FLAGS_HEADER_PERSISTENT;
      return 1;
    }
  }
  return 0;
}

void
fs_close_custom(struct fs_file *file)
{
  if (file && file->pextension) {
    mem_free(file->pextension);
    file->pextension = NULL;
  }
}

#if LWIP_HTTPD_FS_ASYNC_READ
u8_t
fs_canread_custom(struct fs_file *file)
{
  LWIP_UNUSED_ARG(file);
  /* This example does not use delayed/async reading */
  return 1;
}

u8_t
fs_wait_read_custom(struct fs_file *file, fs_wait_cb callback_fn, void *callback_arg)
{
  LWIP_ASSERT("not implemented in this example configuration", 0);
  LWIP_UNUSED_ARG(file);
  LWIP_UNUSED_ARG(callback_fn);
  LWIP_UNUSED_ARG(callback_arg);
  /* Return
     - 1 if ready to read (at least one byte)
     - 0 if reading should be delayed (call 'tcpip_callback(callback_fn, callback_arg)' when ready) */
  return 1;
}

int
fs_read_async_custom(struct fs_file *file, char *buffer, int count, fs_wait_cb callback_fn, void *callback_arg)
{
  LWIP_ASSERT("not implemented in this example configuration", 0);
  LWIP_UNUSED_ARG(file);
  LWIP_UNUSED_ARG(buffer);
  LWIP_UNUSED_ARG(count);
  LWIP_UNUSED_ARG(callback_fn);
  LWIP_UNUSED_ARG(callback_arg);
  /* Return
     - FS_READ_EOF if all bytes have been read
     - FS_READ_DELAYED if reading is delayed (call 'tcpip_callback(callback_fn, callback_arg)' when done) */
  /* all bytes read already */
  return FS_READ_EOF;
}

#else /* LWIP_HTTPD_FS_ASYNC_READ */
int
fs_read_custom(struct fs_file *file, char *buffer, int count)
{
  LWIP_ASSERT("not implemented in this example configuration", 0);
  LWIP_UNUSED_ARG(file);
  LWIP_UNUSED_ARG(buffer);
  LWIP_UNUSED_ARG(count);
  /* Return
     - FS_READ_EOF if all bytes have been read
     - FS_READ_DELAYED if reading is delayed (call 'tcpip_callback(callback_fn, callback_arg)' when done) */
  /* all bytes read already */
  return FS_READ_EOF;
}

#endif /* LWIP_HTTPD_FS_ASYNC_READ */

#endif /* LWIP_HTTPD_EXAMPLE_GENERATEDFILES */