/*
  PIM for Quagga
  Copyright (C) 2008  Everton da Silva Marques

  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 2 of the License, 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; see the file COPYING; if not, write to the
  Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  MA 02110-1301 USA
  
  $QuaggaId: $Format:%an, %ai, %h$ $
*/

#include <zebra.h>

#include "if.h"
#include "log.h"
#include "memory.h"

#include "pim_ssmpingd.h"
#include "pim_time.h"
#include "pim_sock.h"
#include "pim_str.h"
#include "pimd.h"

static const char * const PIM_SSMPINGD_REPLY_GROUP = "232.43.211.234";

enum {
  PIM_SSMPINGD_REQUEST = 'Q',
  PIM_SSMPINGD_REPLY   = 'A'
};

static void ssmpingd_read_on(struct ssmpingd_sock *ss);

void pim_ssmpingd_init()
{
  int result;

  zassert(!qpim_ssmpingd_list);

  result = inet_pton(AF_INET, PIM_SSMPINGD_REPLY_GROUP, &qpim_ssmpingd_group_addr);
  
  zassert(result > 0);
}

void pim_ssmpingd_destroy()
{
  if (qpim_ssmpingd_list) {
    list_free(qpim_ssmpingd_list);
    qpim_ssmpingd_list = 0;
  }
}

static struct ssmpingd_sock *ssmpingd_find(struct in_addr source_addr)
{
  struct listnode      *node;
  struct ssmpingd_sock *ss;

  if (!qpim_ssmpingd_list)
    return 0;

  for (ALL_LIST_ELEMENTS_RO(qpim_ssmpingd_list, node, ss))
    if (source_addr.s_addr == ss->source_addr.s_addr)
      return ss;

  return 0;
}

static void ssmpingd_free(struct ssmpingd_sock *ss)
{
  XFREE(MTYPE_PIM_SSMPINGD, ss);
}

static int ssmpingd_socket(struct in_addr addr, int port, int mttl)
{
  struct sockaddr_in sockaddr;
  int fd;

  fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
  if (fd < 0) {
    zlog_err("%s: could not create socket: errno=%d: %s",
	     __PRETTY_FUNCTION__, errno, safe_strerror(errno));
    return -1;
  }

  sockaddr.sin_family = AF_INET;
  sockaddr.sin_addr   = addr;
  sockaddr.sin_port   = htons(port);

  if (bind(fd, &sockaddr, sizeof(sockaddr))) {
    char addr_str[100];
    pim_inet4_dump("<addr?>", addr, addr_str, sizeof(addr_str));
    zlog_warn("%s: bind(fd=%d,addr=%s,port=%d,len=%zu) failure: errno=%d: %s",
	      __PRETTY_FUNCTION__,
	      fd, addr_str, port, sizeof(sockaddr),
	      errno, safe_strerror(errno));
    close(fd);
    return -1;
  }

  /* Needed to obtain destination address from recvmsg() */
  {
#if defined(HAVE_IP_PKTINFO)
    /* Linux IP_PKTINFO */
    int opt = 1;
    if (setsockopt(fd, SOL_IP, IP_PKTINFO, &opt, sizeof(opt))) {
      zlog_warn("%s: could not set IP_PKTINFO on socket fd=%d: errno=%d: %s",
		__PRETTY_FUNCTION__, fd, errno, safe_strerror(errno));
    }
#elif defined(HAVE_IP_RECVDSTADDR)
    /* BSD IP_RECVDSTADDR */
    int opt = 1;
    if (setsockopt(fd, IPPROTO_IP, IP_RECVDSTADDR, &opt, sizeof(opt))) {
      zlog_warn("%s: could not set IP_RECVDSTADDR on socket fd=%d: errno=%d: %s",
		__PRETTY_FUNCTION__, fd, errno, safe_strerror(errno));
    }
#else
    zlog_err("%s %s: missing IP_PKTINFO and IP_RECVDSTADDR: unable to get dst addr from recvmsg()",
	     __FILE__, __PRETTY_FUNCTION__);
    close(fd);
    return -1;
#endif
  }
  
  {
    int reuse = 1;
    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
		   (void *) &reuse, sizeof(reuse))) {
      zlog_warn("%s: could not set Reuse Address Option on socket fd=%d: errno=%d: %s",
		__PRETTY_FUNCTION__, fd, errno, safe_strerror(errno));
      close(fd);
      return -1;
    }
  }

  if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL,
		 (void *) &mttl, sizeof(mttl))) {
    zlog_warn("%s: could not set multicast TTL=%d on socket fd=%d: errno=%d: %s",
	      __PRETTY_FUNCTION__, mttl, fd, errno, safe_strerror(errno));
    close(fd);
    return -1;
  }

  {
    int loop = 0;
    if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP,
		   (void *) &loop, sizeof(loop))) {
      zlog_warn("%s: could not %s Multicast Loopback Option on socket fd=%d: errno=%d: %s",
		__PRETTY_FUNCTION__,
		loop ? "enable" : "disable",
		fd, errno, safe_strerror(errno));
      close(fd);
      return PIM_SOCK_ERR_LOOP;
    }
  }

  if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF,
		 (void *) &addr, sizeof(addr))) {
    zlog_warn("%s: could not set Outgoing Interface Option on socket fd=%d: errno=%d: %s",
	      __PRETTY_FUNCTION__, fd, errno, safe_strerror(errno));
    close(fd);
    return -1;
  }

  {
    long flags;

    flags = fcntl(fd, F_GETFL, 0);
    if (flags < 0) {
      zlog_warn("%s: could not get fcntl(F_GETFL,O_NONBLOCK) on socket fd=%d: errno=%d: %s",
		__PRETTY_FUNCTION__, fd, errno, safe_strerror(errno));
      close(fd);
      return -1;
    }

    if (fcntl(fd, F_SETFL, flags | O_NONBLOCK)) {
      zlog_warn("%s: could not set fcntl(F_SETFL,O_NONBLOCK) on socket fd=%d: errno=%d: %s",
		__PRETTY_FUNCTION__, fd, errno, safe_strerror(errno));
      close(fd);
      return -1;
    }
  }

  return fd;
}

static void ssmpingd_delete(struct ssmpingd_sock *ss)
{
  zassert(ss);
  zassert(qpim_ssmpingd_list);

  THREAD_OFF(ss->t_sock_read);

  if (close(ss->sock_fd)) {
    int e = errno;
    char source_str[100];
    pim_inet4_dump("<src?>", ss->source_addr, source_str, sizeof(source_str));
    zlog_warn("%s: failure closing ssmpingd sock_fd=%d for source %s: errno=%d: %s",
	      __PRETTY_FUNCTION__,
	      ss->sock_fd, source_str, e, safe_strerror(e));
    /* warning only */
  }

  listnode_delete(qpim_ssmpingd_list, ss);
  ssmpingd_free(ss);
}

static void ssmpingd_sendto(struct ssmpingd_sock *ss,
			    const char *buf,
			    int len,
			    struct sockaddr_in to)
{
  socklen_t tolen = sizeof(to);
  int sent;

  sent = sendto(ss->sock_fd, buf, len, MSG_DONTWAIT, &to, tolen);
  if (sent != len) {
    int e = errno;
    char to_str[100];
    pim_inet4_dump("<to?>", to.sin_addr, to_str, sizeof(to_str));
    if (sent < 0) {
      zlog_warn("%s: sendto() failure to %s,%d: fd=%d len=%d: errno=%d: %s",
		__PRETTY_FUNCTION__,
		to_str, ntohs(to.sin_port), ss->sock_fd, len,
		e, safe_strerror(e));
    }
    else {
      zlog_warn("%s: sendto() partial to %s,%d: fd=%d len=%d: sent=%d",
		__PRETTY_FUNCTION__,
		to_str, ntohs(to.sin_port), ss->sock_fd,
		len, sent);
    }
  }
}

static int ssmpingd_read_msg(struct ssmpingd_sock *ss)
{
  struct interface *ifp;
  struct sockaddr_in from;
  struct sockaddr_in to;
  socklen_t fromlen = sizeof(from);
  socklen_t tolen = sizeof(to);
  int ifindex = -1;
  char buf[1000];
  int len;

  ++ss->requests;

  len = pim_socket_recvfromto(ss->sock_fd, buf, sizeof(buf),
			      &from, &fromlen,
			      &to, &tolen,
			      &ifindex);
  if (len < 0) {
    char source_str[100];
    pim_inet4_dump("<src?>", ss->source_addr, source_str, sizeof(source_str));
    zlog_warn("%s: failure receiving ssmping for source %s on fd=%d: errno=%d: %s",
	      __PRETTY_FUNCTION__, source_str, ss->sock_fd, errno, safe_strerror(errno));
    return -1;
  }

  ifp = if_lookup_by_index(ifindex);

  if (buf[0] != PIM_SSMPINGD_REQUEST) {
    char source_str[100];
    char from_str[100];
    char to_str[100];
    pim_inet4_dump("<src?>", ss->source_addr, source_str, sizeof(source_str));
    pim_inet4_dump("<from?>", from.sin_addr, from_str, sizeof(from_str));
    pim_inet4_dump("<to?>", to.sin_addr, to_str, sizeof(to_str));
    zlog_warn("%s: bad ssmping type=%d from %s,%d to %s,%d on interface %s ifindex=%d fd=%d src=%s",
	      __PRETTY_FUNCTION__,
	      buf[0],
	      from_str, ntohs(from.sin_port),
	      to_str, ntohs(to.sin_port),
	      ifp ? ifp->name : "<iface?>",
	      ifindex, ss->sock_fd,
	      source_str);
    return 0;
  }

  if (PIM_DEBUG_SSMPINGD) {
    char source_str[100];
    char from_str[100];
    char to_str[100];
    pim_inet4_dump("<src?>", ss->source_addr, source_str, sizeof(source_str));
    pim_inet4_dump("<from?>", from.sin_addr, from_str, sizeof(from_str));
    pim_inet4_dump("<to?>", to.sin_addr, to_str, sizeof(to_str));
    zlog_debug("%s: recv ssmping from %s,%d to %s,%d on interface %s ifindex=%d fd=%d src=%s",
	       __PRETTY_FUNCTION__,
	       from_str, ntohs(from.sin_port),
	       to_str, ntohs(to.sin_port),
	       ifp ? ifp->name : "<iface?>",
	       ifindex, ss->sock_fd,
	       source_str);
  }

  buf[0] = PIM_SSMPINGD_REPLY;

  /* unicast reply */
  ssmpingd_sendto(ss, buf, len, from);

  /* multicast reply */
  from.sin_addr = qpim_ssmpingd_group_addr;
  ssmpingd_sendto(ss, buf, len, from);

  return 0;
}

static int ssmpingd_sock_read(struct thread *t)
{
  struct ssmpingd_sock *ss;
  int sock_fd;
  int result;

  zassert(t);

  ss = THREAD_ARG(t);
  zassert(ss);

  sock_fd = THREAD_FD(t);
  zassert(sock_fd == ss->sock_fd);

  result = ssmpingd_read_msg(ss);

  /* Keep reading */
  ss->t_sock_read = 0;
  ssmpingd_read_on(ss);

  return result;
}

static void ssmpingd_read_on(struct ssmpingd_sock *ss)
{
  zassert(!ss->t_sock_read);
  THREAD_READ_ON(master, ss->t_sock_read,
		 ssmpingd_sock_read, ss, ss->sock_fd);
}

static struct ssmpingd_sock *ssmpingd_new(struct in_addr source_addr)
{
  struct ssmpingd_sock *ss;
  int sock_fd;

  if (!qpim_ssmpingd_list) {
    qpim_ssmpingd_list = list_new();
    if (!qpim_ssmpingd_list) {
      zlog_err("%s %s: failure: qpim_ssmpingd_list=list_new()",
	       __FILE__, __PRETTY_FUNCTION__);
      return 0;
    }
    qpim_ssmpingd_list->del = (void (*)(void *)) ssmpingd_free;
  }

  sock_fd = ssmpingd_socket(source_addr, /* port: */ 4321, /* mTTL: */ 64);
  if (sock_fd < 0) {
    char source_str[100];
    pim_inet4_dump("<src?>", source_addr, source_str, sizeof(source_str));
    zlog_warn("%s: ssmpingd_socket() failure for source %s",
	      __PRETTY_FUNCTION__, source_str);
    return 0;
  }

  ss = XMALLOC(MTYPE_PIM_SSMPINGD, sizeof(*ss));
  if (!ss) {
    char source_str[100];
    pim_inet4_dump("<src?>", source_addr, source_str, sizeof(source_str));
    zlog_err("%s: XMALLOC(%zu) failure for ssmpingd source %s",
	     __PRETTY_FUNCTION__,
	     sizeof(*ss), source_str);
    close(sock_fd);
    return 0;
  }

  ss->sock_fd     = sock_fd;
  ss->t_sock_read = 0;
  ss->source_addr = source_addr;
  ss->creation    = pim_time_monotonic_sec();
  ss->requests    = 0;

  listnode_add(qpim_ssmpingd_list, ss);

  ssmpingd_read_on(ss);

  return ss;
}

int pim_ssmpingd_start(struct in_addr source_addr)
{
  struct ssmpingd_sock *ss;

  ss = ssmpingd_find(source_addr);
  if (ss) {
    /* silently ignore request to recreate entry */
    return 0;
  }

  {
    char source_str[100];
    pim_inet4_dump("<src?>", source_addr, source_str, sizeof(source_str));
    zlog_info("%s: starting ssmpingd for source %s",
	      __PRETTY_FUNCTION__, source_str);
  }

  ss = ssmpingd_new(source_addr);
  if (!ss) {
    char source_str[100];
    pim_inet4_dump("<src?>", source_addr, source_str, sizeof(source_str));
    zlog_warn("%s: ssmpingd_new() failure for source %s",
	      __PRETTY_FUNCTION__, source_str);
    return -1;
  }

  return 0;
}

int pim_ssmpingd_stop(struct in_addr source_addr)
{
  struct ssmpingd_sock *ss;

  ss = ssmpingd_find(source_addr);
  if (!ss) {
    char source_str[100];
    pim_inet4_dump("<src?>", source_addr, source_str, sizeof(source_str));
    zlog_warn("%s: could not find ssmpingd for source %s",
	      __PRETTY_FUNCTION__, source_str);
    return -1;
  }

  {
    char source_str[100];
    pim_inet4_dump("<src?>", source_addr, source_str, sizeof(source_str));
    zlog_info("%s: stopping ssmpingd for source %s",
	      __PRETTY_FUNCTION__, source_str);
  }

  ssmpingd_delete(ss);

  return 0;
}