/* This file is part of tagr.
   Copyright (C) 2000, 2005, 2006, 2009 Max Bouglacoff, Sergey Poznyakoff

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/un.h>
#include <netdb.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <syslog.h>
#include <tagr.h>
#include <report.h>
#include <inttypes.h>
#include <c-strcase.h>
#include <wordsplit.h>

unsigned stream_idle_timeout = 10;

struct tagr_server
{
  struct tagr_server *next;
  char *id;
  enum tagr_server_type type;
  int fd;
  struct grecs_sockaddr addr;
};
  
static struct tagr_server *server_head, *server_tail;

struct server_class
{
  int (*srv_open) (struct tagr_server *);
  void (*srv_run) (struct tagr_server *);
  void (*srv_close) (struct tagr_server *);
};

static void
common_close (struct tagr_server *srv)
{
  close (srv->fd);
}

static int
setup_socket (struct tagr_server *srv)
{
  int rc;
  
  if ((rc = fcntl (srv->fd, F_GETFD, 0)) == -1
      || fcntl (srv->fd, F_SETFD, rc | FD_CLOEXEC) == -1)
    logmsg (L_ERR, _("cannot set close-on-exec: %s"),
	    strerror (errno));
  
  switch (srv->addr.sa->sa_family)
    {
    case PF_INET:
      {
	int yes = 1;
	if (setsockopt (srv->fd, SOL_SOCKET, SO_REUSEADDR,
			(void *) &yes, sizeof(yes)) == -1)
	  logmsg (L_ERR, _("setting reuseaddr failed: %s"),
		  strerror (errno));
      }
      break;

    case PF_UNIX:
      {
	struct sockaddr_un *s_un =
	  (struct sockaddr_un *) srv->addr.sa;
	if (unlink (s_un->sun_path))
	  logmsg (L_ERR, _("cannot remove socket %s: %s"),
		  s_un->sun_path, strerror (errno));
      }
    }
  
  if (bind (srv->fd, srv->addr.sa, srv->addr.len) < 0)
    {
      logmsg (L_ERR, "bind: %s", strerror (errno));
      close (srv->fd);
      srv->fd = -1;
      return 1;
    }
  return 0;
}  

static int udp_open (struct tagr_server *);
static void udp_run (struct tagr_server *);
static int tcp_open (struct tagr_server *);
static void tcp_run (struct tagr_server *);

struct server_class server_tab[] = {
  { udp_open, udp_run, common_close },
  { tcp_open, tcp_run, common_close }
};


void
register_server (const char *id,
		 enum tagr_server_type type, struct grecs_sockaddr addr)
{
  struct tagr_server *srv = xmalloc (sizeof (*srv));
  srv->id = xstrdup (id);
  srv->type = type;
  srv->fd = -1;
  srv->addr = addr;

  srv->next = NULL;
  if (server_tail)
    server_tail->next =srv;
  else
    server_head = srv;
  server_tail = srv;
}

void
open_servers ()
{
  struct tagr_server *prev = NULL;
  struct tagr_server *srv = server_head;
  
  while (srv)
    {
      struct tagr_server *next = srv->next;
      if (server_tab[srv->type].srv_open (srv))
	{
	  free (srv->id);
	  free (srv->addr.sa);
	  free (srv);
	  if (prev)
	    prev->next = next;
	  else
	    server_head = next;
	}
      else
	prev = srv;
      srv = next;
    }

  if (!server_head)
    logmsg (L_CRIT, _("no servers configured"));
  
  server_tail = prev;
}

void
close_servers ()
{
  struct tagr_server *srv = server_head;
  
  while (srv)
    {
      struct tagr_server *next = srv->next;
      server_tab[srv->type].srv_close (srv);
      free (srv->id);
      free (srv->addr.sa);
      free (srv);
      srv = next;
    }
  server_head = server_tail = NULL;
}

void
subprocess (void (*fun) (void *data), void *data, int fd)
{
  int child = 0;
  if (!single_process_option)
    {
      pid_t pid = fork ();
      if (pid > 0)
	return;
      else if (pid < 0)
	logmsg (L_ERR, _("cannot fork: %s"), strerror (errno));
      else
	{
	  signal (SIGHUP, SIG_DFL);
	  signal (SIGCHLD, SIG_DFL);
	  signal (SIGALRM, SIG_DFL);
	  child = 1;
	  if (fd != -1)
	    close (fd);
	}
    }
  fun (data);
  if (child)
    exit (0);
}


void
decode_buffer (void *recv_buffer)
{
  int i;
  Stat_reply *reply;
  Stat *sp;
  int child = 0;

  reply = (Stat_reply *) recv_buffer;
  reply->n_addr = ntohl (reply->n_addr);

  if (reply->n_addr > MAXADDR)
    {
      logmsg (L_NOTICE, _("got invalid packet: n_addr = %d"),
	      reply->n_addr);
      return;
    }
  reply->timestamp = ntohl (reply->timestamp);
  if (verbose_level)
    {
      char tbuf[sizeof("2009-04-01 00:00:00")];
      strftime (tbuf, sizeof tbuf, "%Y-%m-%d %H:%M:%S",
		gmtime (&reply->timestamp));
      logmsg (L_INFO, _("Received packet: %d %lu - %s"), reply->n_addr,
	      (unsigned long) reply->timestamp, tbuf);
    }
  
  sp = reply->stat;

  if (open_db (TAGR_DB_WR) == 0)
    {
      for (i = 0; i < reply->n_addr; i++, sp++)
	{
	  sp->in = ntohl (sp->in);
	  sp->out = ntohl (sp->out);
	  verbose (1, _("Monitor %s: %lu %lu"), sp->name, sp->in, sp->out);
	  report (sp, reply->timestamp);
	}
      close_db ();
    }
}

static int
udp_open (struct tagr_server *srv)
{
  srv->fd = socket (srv->addr.sa->sa_family, SOCK_DGRAM, 0);

  if (srv->fd < 0)
    {
      logmsg (L_ERR, "socket: %s", strerror (errno));
      return 1;
    }

  return setup_socket (srv);
}

static void
udp_run (struct tagr_server *srv)
{
  char recv_buffer[reply_size (MAXADDR)];
  struct sockaddr saremote;
  int salen = sizeof saremote;
  int rc = recvfrom (srv->fd, recv_buffer,
		     sizeof (recv_buffer), 0, &saremote, &salen);
  if (rc > 0)
    subprocess (decode_buffer, recv_buffer, -1);
  else if (rc < 0 && errno != EINTR)
    logmsg (L_ERR, "recvfrom: %s", strerror (errno));
}



static int
tcp_open (struct tagr_server *srv)
{
  srv->fd = socket (srv->addr.sa->sa_family, SOCK_STREAM, 0);

  if (srv->fd < 0)
    {
      logmsg (L_ERR, "socket: %s", strerror (errno));
      return 1;
    }

  if (setup_socket (srv))
    return 1;

  if (listen (srv->fd, 8))
    {
      logmsg (L_ERR, "listen: %s", strerror (errno));
      close (srv->fd);
      return 1;
    }
  return 0;
}

void
trim_crlf (char *buf)
{
  size_t len = strlen (buf);
  if (len > 0 && buf[len-1] == '\n')
    {
      buf[--len] = 0;
      if (len > 0 && buf[len-1] == '\r')
	buf[--len] = 0;
    }
}

static int
convert_ts (const char *str, time_t *pt)
{
  uintmax_t val;
  char *p;
  
  val = strtoumax (str, &p, 10);
  if (*p)
    return 1;
  *pt = val;
  if (*pt != val)
    return 1;
  return 0;
}
  
static int
convert_ulong (const char *str, unsigned long *pt)
{
  uintmax_t val;
  char *p;
  
  val = strtoumax (str, &p, 10);
  if (*p)
    return 1;
  *pt = val;
  if (*pt != val)
    return 1;
  return 0;
}

static RETSIGTYPE
sig_child_alrm (int sig)
{
  logmsg (L_NOTICE, _("child timed out"));
  exit (EX_TEMPFAIL);
}

enum tagr_dialog_state
  {
    initial_dialog_state,
    auth_dialog_state,
    quit_dialog_state
  };

struct tagr_dialog
{
  enum tagr_dialog_state state;
  FILE *in;
  FILE *out;
};

#define STATEMASK(n) (1u<<(n))
#define ANYSTATE ((unsigned)~0)

struct command
{
  const char *name;
  unsigned statemask;
  int minargs;
  int maxargs;
  void (*handler) (struct tagr_dialog *, struct command *,
		   struct wordsplit *);
};

static void
cmd_auth (struct tagr_dialog *dlg, struct command *cmd,
	  struct wordsplit *ws)
{
  if (tagr_auth (ws->ws_wordv[1], ws->ws_wordv[2]) == 0)
    {
      dlg->state = auth_dialog_state;
      fprintf (dlg->out, "+OK welcome, %s\r\n", ws->ws_wordv[1]);
    }
  else
    fprintf (dlg->out, "-ERR authorization failed\r\n");
}

static void
cmd_sample (struct tagr_dialog *dlg, struct command *cmd,
	    struct wordsplit *ws)
{
  Stat st;
  time_t t;
  
  if (strlen (ws->ws_wordv[1]) > MAX_NAME_LENGTH)
    {
      fprintf (dlg->out, "-ERR id too long\r\n");
      return;
    }

  strcpy (st.name, ws->ws_wordv[1]);
  if (convert_ts (ws->ws_wordv[2], &t)
      || convert_ulong (ws->ws_wordv[3], &st.in)
      || convert_ulong (ws->ws_wordv[4], &st.out))
    {
      fprintf (dlg->out, "-ERR invalid input\r\n");
      return;
    }

  if (open_db (TAGR_DB_WR))
    fprintf (dlg->out, "-TEMP database not available\r\n");
  else
    {
      report (&st, t);
      close_db ();
      fprintf (dlg->out, "+OK thank you\r\n");
    }
}

static void
cmd_quit (struct tagr_dialog *dlg, struct command *cmd,
	  struct wordsplit *ws)
{
  dlg->state = quit_dialog_state;
  fprintf (dlg->out, "+OK bye\r\n");
}

static struct command command_tab[] = {
  { "AUTH", STATEMASK (initial_dialog_state), 3, 3, cmd_auth },
  { "SAMPLE", STATEMASK (auth_dialog_state), 5, 5, cmd_sample },
  { "QUIT",   ANYSTATE, 1, 1, cmd_quit },
  { NULL }
};

static struct command *
find_command (const char *name)
{
  struct command *cmd;
  
  for (cmd = command_tab; cmd->name; cmd++)
    if (c_strcasecmp (cmd->name, name) == 0)
      return cmd;
  return NULL;
}
    

static void
tcp_server_loop (void *data)
{
  int fd = *(int*)data;
  struct tagr_dialog dlg;
  size_t bufsize = 0;
  char *buf = NULL;
  const char *authid;

  signal (SIGALRM, sig_child_alrm);

  dlg.state = initial_dialog_state;
  dlg.in = fdopen (fd, "r");
  dlg.out = fdopen (fd, "w");
  setvbuf (dlg.in, NULL, _IOLBF, 0);
  setvbuf (dlg.out, NULL, _IOLBF, 0);

  authid = tagr_auth_init ();
  fprintf (dlg.out, "+OK tagr experimental stream service %s\r\n", authid);
  while (dlg.state != quit_dialog_state
	 && getline (&buf, &bufsize, dlg.in) > 0)
    {
      struct wordsplit ws;
      struct command *cmd;
      
      alarm (stream_idle_timeout);
      trim_crlf (buf);
      if (wordsplit (buf, &ws, WRDSF_DEFFLAGS))
	{
	  logmsg (L_ERR, _("failed to parse input line"));
	  fprintf (dlg.out, "-ERR parsing failed\r\n");
	  continue;
	}

      if (ws.ws_wordc == 0)
	fprintf (dlg.out, "-ERR invalid input\r\n");
      else if (cmd = find_command (ws.ws_wordv[0]))
	{
	  if (!(STATEMASK (dlg.state) & cmd->statemask))
	    fprintf (dlg.out, "-ERR wrong state\r\n");
	  else if (ws.ws_wordc < cmd->minargs
	      || (cmd->maxargs > 0 && ws.ws_wordc > cmd->maxargs))
	    fprintf (dlg.out, "-ERR invalid number of arguments\r\n");
	  else
	    cmd->handler (&dlg, cmd, &ws);
	}
      else
	fprintf (dlg.out, "-ERR invalid input\r\n");	
      wordsplit_free (&ws);
    }
  
  free (buf);
  fclose (dlg.in);
  fclose (dlg.out);
  close (fd);
}

static void
tcp_run (struct tagr_server *srv)
{
  union
  {
    struct sockaddr sa;
    struct sockaddr_in s_in;
    struct sockaddr_un s_un;
  } addr;
  socklen_t len = sizeof (addr);
  
  int fd = accept (srv->fd, &addr.sa, &len);
  
  if (fd == -1)
    {
      logmsg (L_ERR, "accept: %s", strerror (errno));
      return;
    }

  subprocess (tcp_server_loop, &fd, srv->fd);
  close (fd);
}

void
server_loop ()
{
  fd_set read_fds;
  int max_fd = 0;
  struct tagr_server *srv;

  FD_ZERO (&read_fds);
  for (srv = server_head; srv; srv = srv->next)
    {
      FD_SET (srv->fd, &read_fds);
      if (srv->fd > max_fd)
	max_fd = srv->fd;
    }

  while (tagr_idle () == 0)
    {
      fd_set rfds = read_fds;
      int rc = select (max_fd + 1, &rfds, NULL, NULL, NULL);
      if (rc < 0)
	{
	  if (errno != EINTR)
	    logmsg (L_ERR, "select: %s", strerror (errno));
	  continue;
	}

      for (srv = server_head; srv; srv = srv->next)
	if (FD_ISSET (srv->fd, &rfds))
	  server_tab[srv->type].srv_run (srv);
    }
}