/**
 * httpd.C: Generic HTTPd
 *
 * Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team
 * Rights to this code are as documented in COPYING.
 *
 *
 * Portions of this file were derived from sources bearing the following license:
 * Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team
 * Copyright © 2005-2007 Jilles Tjoelker et al.
 * Rights to this code are as documented in doc/pod/license.pod.
 *
 * $Id: httpd.C,v 1.10 2007/09/22 14:27:28 pippijn Exp $
 */

#include "atheme.h"
#include <libermyth.h>
#include <ermyth/module.h>
#include "httpd.h"
#include "datastream.h"
#include "connection.h"
#include "confparse.h"

#define REQUEST_MAX 65536	/* maximum size of one call */

static char const rcsid[] = "$Id: httpd.C,v 1.10 2007/09/22 14:27:28 pippijn Exp $";

static void on_config_ready (void);

REGISTER_MODULE ("rpc/httpd", false, "The Ermyth Team <http://ermyth.one09.net>");

static connection_t *listener;
pathvec pathhandlers;

/* conf stuff */
ConfTable::list_type conf_httpd_table;

static struct httpd_configuration
{
  char *host;
  char *www_root;
  int port;

  void clear ()
  {
    if (host != NULL)
      sfree (host);
    if (www_root != NULL)
      sfree (www_root);
    host = NULL;
    www_root = NULL;
  }
} httpd_config;

static int
conf_httpd_host (config_entry_t *ce)
{
  if (!ce->valid ())
    return -1;

  if (httpd_config.host != NULL)
    sfree (httpd_config.host);
  httpd_config.host = sstrdup (ce->vardata<char *> ());

  return 0;
}

static int
conf_httpd_www_root (config_entry_t *ce)
{
  if (!ce->valid ())
    return -1;

  if (httpd_config.www_root != NULL)
    sfree (httpd_config.www_root);
  httpd_config.www_root = sstrdup (ce->vardata<char *> ());

  return 0;
}

static int
conf_httpd_port (config_entry_t *ce)
{
  if (!ce->valid ())
    return -1;

  httpd_config.port = ce->vardata<int> ();

  return 0;
}

static int
conf_httpd (config_entry_t *ce)
{
  subblock_handler (ce, conf_httpd_table);
  return 0;
}

void
httpddata::clear (void)
{
  method[0] = '\0';
  filename[0] = '\0';
  if (requestbuf != NULL)
    {
      sfree (requestbuf);
      requestbuf = NULL;
    }
  if (replybuf != NULL)
    {
      sfree (replybuf);
      replybuf = NULL;
    }
  length = 0;
  lengthdone = 0;
  correct_content_type = false;
  expect_100_continue = false;
  sent_reply = false;
}

static int
open_file (char const *filename)
{
  char fname[256];

  if (strstr (filename, ".."))
    return -1;
  if (!strcmp (filename, "/"))
    filename = "/index.html";
  snprintf (fname, sizeof fname, "%s/%s", httpd_config.www_root, filename);
  return open (fname, O_RDONLY);
}

static void
process_header (connection_t *cptr, char *line)
{
  httpddata *hd;
  char *p;

  hd = static_cast<httpddata *> (cptr->userdata);
  p = strchr (line, ':');
  if (p == NULL)
    return;
  *p = '\0';
  p++;
  while (*p == ' ')
    p++;
  if (!strcasecmp (line, "Connection"))
    {
      p = strtok (p, ", \t");
      while (p != NULL)
        {
          if (!strcasecmp (p, "close"))
            {
              slog (LG_DEBUG, "process_header(): Connection: close requested by fd %d", cptr->fd);
              hd->connection_close = true;
            }
          p = strtok (NULL, ", \t");
        }
    }
  else if (!strcasecmp (line, "Content-Length"))
    hd->length = atoi (p);
  else if (!strcasecmp (line, "Content-Type"))
    {
      p = strtok (p, "; \t");
      hd->correct_content_type = p != NULL && (!strcasecmp (p, "text/xml") || !strcasecmp (p, "application/json"));
    }
  else if (!strcasecmp (line, "Expect"))
    hd->expect_100_continue = !strcasecmp (p, "100-continue");
}

static void
check_close (connection_t *cptr)
{
  httpddata *hd;

  hd = static_cast<httpddata *> (cptr->userdata);
  if (hd->connection_close)
    sendq_add_eof (cptr);
}

static void
send_error (connection_t *cptr, int errorcode, char const * const text, bool const sendentity)
{
  httpddata *hd;
  char buf1[300];
  char buf2[700];

  hd = static_cast<httpddata *> (cptr->userdata);
  if (errorcode < 100 || errorcode > 999)
    errorcode = 500;
  snprintf (buf2, sizeof buf2, "HTTP/1.1 %d %s\r\n", errorcode, text);
  snprintf (buf1, sizeof buf1, "HTTP/1.1 %d %s\r\n"
                               "Server: " PACKAGE_NAME "/%s\r\n"
                               "Content-Type: text/plain\r\n"
                               "Content-Length: %" PRIsize "\r\n\r\n%s",
                               errorcode, text, version, strlen (buf2), sendentity ? buf2 : "");
  sendq_add (cptr, buf1, strlen (buf1));
}

static char const * const
content_type (char const * const filename)
{
  char const *p;

  if (!strcmp (filename, "/"))
    return "text/html";

  p = strrchr (filename, '.');
  if (p == NULL)
    return "text/plain";
  p++;
  if (!strcasecmp (p, "html") || !strcasecmp (p, "htm"))
    return "text/html";
  else if (!strcasecmp (p, "txt"))
    return "text/plain";
  else if (!strcasecmp (p, "jpg") || !strcasecmp (p, "jpeg"))
    return "image/jpeg";
  else if (!strcasecmp (p, "gif"))
    return "image/gif";
  else if (!strcasecmp (p, "png"))
    return "image/png";
  return "application/octet-stream";
}

static void
httpd_recvqhandler (connection_t *cptr)
{
  char buf[BUFSIZE * 2];
  char outbuf[BUFSIZE * 2];
  int count;
  httpddata *hd;
  char *p;
  int in;
  struct stat sb;
  off_t count1;
  path_handler_t ph;
  bool is_get, is_post, handling_done = false;
  pathvec::iterator found, pvend = pathhandlers.end ();

  hd = static_cast<httpddata *> (cptr->userdata);

  if ((found = (std::find_if (pathhandlers.begin (), pvend, pathhandler_eq (hd->filename))))
      != pvend)
    {
      handling_done = true;
      ph = *found;
    }

  if (handling_done == true)
    {
      if (hd->requestbuf != NULL)
        {
          count = recvq_get (cptr, hd->requestbuf + hd->lengthdone, hd->length - hd->lengthdone);
          if (count <= 0)
            return;
          hd->lengthdone += count;
          if (hd->lengthdone != hd->length)
            return;
          hd->requestbuf[hd->length] = '\0';

          ph.handler (cptr, hd->requestbuf);

          hd->clear ();
          return;
        }
    }

  count = recvq_getline (cptr, buf, sizeof buf - 1);
  if (count <= 0)
    return;
  if (cptr->flags & CF_NONEWLINE)
    {
      slog (LG_INFO, "httpd_recvqhandler(): throwing out fd %d (%s) for excessive line length", cptr->fd, cptr->hbuf);
      send_error (cptr, 400, "Bad request", true);
      sendq_add_eof (cptr);
      return;
    }

  cnt.bin += count;
  if (buf[count - 1] == '\n')
    count--;
  if (count > 0 && buf[count - 1] == '\r')
    count--;
  buf[count] = '\0';

  if (hd->method[0] == '\0')
    {
      /* make sure they're not sending more requests after
       * declaring they're not sending any more */
      if (hd->connection_close)
        return;
      p = strtok (buf, " ");
      if (p == NULL)
        return;
      strlcpy (hd->method, p, sizeof hd->method);
      p = strtok (NULL, " ");
      if (p == NULL)
        return;
      strlcpy (hd->filename, p, sizeof hd->filename);
      p = strtok (NULL, "");
      if (p == NULL || !strcmp (p, "HTTP/1.0"))
        hd->connection_close = true;
      slog (LG_DEBUG, "httpd_recvqhandler(): request %s for %s", hd->method, hd->filename);
    }
  else if (count == 0)
    {
      is_get = !strcmp (hd->method, "GET");
      is_post = !strcmp (hd->method, "POST");

      if (!is_post && !is_get)
        {
          send_error (cptr, 501, "Method Not Implemented", true);
          sendq_add_eof (cptr);
          return;
        }

      hd->method[0] = '\0';

      if (!handling_done)
        {
          in = open_file (hd->filename);
          if (in == -1 || fstat (in, &sb) == -1 || !S_ISREG (sb.st_mode))
            {
              if (in != -1)
        	close (in);
              slog (LG_INFO, "httpd_recvqhandler(): 404 for %s", hd->filename);
              send_error (cptr, 404, "Not Found", is_get);
              check_close (cptr);
              return;
            }
          slog (LG_INFO, "httpd_recvqhandler(): 200 for %s", hd->filename);
          snprintf (outbuf, sizeof outbuf, "HTTP/1.1 200 OK\r\n"
                                           "Server: " PACKAGE_NAME "/%s\r\n"
                                           "Content-Type: %s\r\n"
                                           "Content-Length: %lu\r\n"
                                           "\r\n",
                                           version, content_type (hd->filename), sb.st_size);
          sendq_add (cptr, outbuf, strlen (outbuf));
          count1 = is_get ? sb.st_size : 0;
          while (count1 > 0)
            {
              count = sizeof outbuf;
              if (count > count1)
        	count = count1;
              count = read (in, outbuf, count);
              if (count <= 0)
        	break;
              sendq_add (cptr, outbuf, count);
              count1 -= count;
            }
          close (in);
          if (count1 > 0)
            {
              slog (LG_INFO, "httpd_recvqhandler(): disconnecting fd %d (%s), read failed on %s", cptr->fd, cptr->hbuf, hd->filename);
              cptr->flags |= CF_DEAD;
            }
          else
            check_close (cptr);
        }
      else
        {
          if (hd->length <= 0)
            {
              send_error (cptr, 411, "Length Required", true);
              sendq_add_eof (cptr);
              return;
            }
          if (hd->length > REQUEST_MAX)
            {
              send_error (cptr, 413, "Request Entity Too Large", true);
              sendq_add_eof (cptr);
              return;
            }
          if (!hd->correct_content_type)
            {
              send_error (cptr, 415, "Unsupported Media Type", true);
              sendq_add_eof (cptr);
              return;
            }
          if (hd->expect_100_continue)
            {
              snprintf (outbuf, sizeof outbuf, "HTTP/1.1 100 Continue\r\n"
                                               "Server: " PACKAGE_NAME "/%s\r\n"
                                               "\r\n", version);
              sendq_add (cptr, outbuf, strlen (outbuf));
            }
          hd->requestbuf = salloc<char> (hd->length + 1);
        }
    }
  else
    process_header (cptr, buf);
}

static void
httpd_closehandler (connection_t *cptr)
{
  httpddata *hd;

  slog (LG_DEBUG, "httpd_closehandler(): fd %d (%s) closed", cptr->fd, cptr->hbuf);
  hd = static_cast<httpddata *> (cptr->userdata);
  if (hd != NULL)
    {
      sfree (hd->requestbuf);
      delete hd;
    }
  cptr->userdata = NULL;
}

static void
do_listen (connection_t *cptr)
{
  connection_t *newptr;
  httpddata *hd;

  newptr = connection_t::accept_tcp (cptr, recvq_put, sendq_flush);
  slog (LG_DEBUG, "do_listen(): accepted httpd from %s fd %d", newptr->hbuf, newptr->fd);
  hd = new httpddata;
  newptr->userdata = hd;
  newptr->recvq_handler = httpd_recvqhandler;
  newptr->close_handler = httpd_closehandler;
}

static void
httpd_checkidle (void *arg)
{
  connection_t::list_type::iterator it, it_end = connection_t::list.end ();
  connection_t *cptr;

  if (listener == NULL)
    return;

  for (it = connection_t::list.begin (); it != it_end; ++it)
    {
      cptr = *it;
      if (cptr->listener == listener && cptr->last_recv + 300 < NOW)
        {
          if (sendq_nonempty (cptr))
            cptr->last_recv = NOW;
          else
            /* from a timeout function,
             * connection_t::close_soon() may take quite
             * a while, and connection_t::close() is safe
             * -- jilles */
            cptr->close ();
        }
    }
}

static void
on_config_ready (void)
{
  if (httpd_config.host != NULL && httpd_config.port != 0)
    {
      listener = connection_t::open_listener_tcp (httpd_config.host, httpd_config.port, do_listen);
      if (listener == NULL)
        slog (LG_ERROR, "httpd_config_ready(): failed to open listener on host %s port %d", httpd_config.host, httpd_config.port);
    }
  else
    slog (LG_ERROR, "httpd_config_ready(): httpd {} block missing or invalid");
  httpd_config.clear ();
}

bool
_modinit (module *m)
{
  event_add ("httpd_checkidle", httpd_checkidle, NULL, 60);

  /* This module needs a rehash to initialize fully if loaded
   * at run time */
  ConfTable::callback.ready.attach (on_config_ready);

  add_top_conf ("HTTPD", conf_httpd);
  add_conf_item ("HOST", conf_httpd_table, conf_httpd_host);
  add_conf_item ("WWW_ROOT", conf_httpd_table, conf_httpd_www_root);
  add_conf_item ("PORT", conf_httpd_table, conf_httpd_port);

  return true;
}

void
_moddeinit (void)
{
  event_delete (httpd_checkidle, NULL);
  listener->close_soon_children ();
  del_conf_item ("HOST", conf_httpd_table);
  del_conf_item ("WWW_ROOT", conf_httpd_table);
  del_conf_item ("PORT", conf_httpd_table);
  del_top_conf ("HTTPD");
  httpd_config.clear ();

  ConfTable::callback.ready.detach (on_config_ready);
}