/*
 * $Id$
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of opensips, a free SIP server.
 *
 * opensips 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
 *
 * opensips 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * History
 * --------
 *  2003-01-28  packet zero-termination moved to receive_msg (jiri)
 *  2003-02-10  undoed the above changes (andrei)
 *  2003-03-19  replaced all the mallocs/frees w/ pkg_malloc/pkg_free (andrei)
 *  2003-04-14  set sockopts to TOS low delay (andrei)
 *  2004-05-03  applied multicast support patch from janakj
 *              added set multicast ttl support (andrei)
 *  2004-07-05  udp_rcv_loop: drop packets with 0 src port + error msg.
 *              cleanups (andrei)
 *  2005-03-10  multicast options are now set for all the udp sockets (andrei)
 */


#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <errno.h>
#include <arpa/inet.h>
#ifdef __linux__
	#include <linux/types.h>
	#include <linux/errqueue.h>
#endif


#include "udp_server.h"
#include "socket_info.h"
#include "globals.h"
#include "config.h"
#include "dprint.h"
#include "receive.h"
#include "mem/mem.h"
#include "ip_addr.h"
#include "pt.h"


static callback_list* cb_list = NULL;

int register_udprecv_cb(callback_f* func, void* param, char a, char b)
{
	callback_list* new;

	new = (callback_list*) pkg_malloc(sizeof(callback_list));
	if(!new){
		LM_ERR("out of pkg memory\n");
		return -1;
	}
	memset(new, 0, sizeof(callback_list));

	new->func = func;
	new->param = param;
	new->a = a;
	new->b = b;
	new->next = NULL;

	if(!cb_list){
		cb_list = new;
	}else{
		new->next = cb_list;
		cb_list = new;
	}

	return 0;
}


#ifdef DBG_MSG_QA
/**
 * Do some message quality assurance.
 * Frequently, bugs in the server have been indicated by zero characters
 * or long whitespaces in generated messages; this debugging option
 * aborts if any such message is sighted.
 *
 * \param buf message buffer
 * \param len buffer length
 * \param return one if the buffer passes the check, zero otherwise
 */
static int dbg_msg_qa(char *buf, int len)
{
#define _DBG_WS_LEN 3
#define _DBG_WS "   "

	char *scan;
	int my_len, space_cnt;
	enum { QA_ANY, QA_SPACE, QA_EOL1 } state;

	my_len=len;
	scan=buf;
	state=QA_ANY;
	space_cnt=0;

	while(my_len) {
		switch(*scan) {
			case ' ':	if (state==QA_SPACE) {
							space_cnt++;
							if (space_cnt==4) {
								LM_CRIT("too many spaces\n");
								return 0;
							}
						} else space_cnt=0;
						state=QA_SPACE;
						break;

			case '\r':	/* ignore */
						space_cnt=0;
						break;

			case '\n': /* don't proceed to body on EoH */
						if (state==QA_EOL1) goto qa_passed;
						space_cnt=0;
						state=QA_EOL1;
						break;

			default:	space_cnt=0;
						state=QA_ANY;
						break;
		}
		scan++;
		my_len--;
	}


qa_passed:
	return 1;
}

#endif

#ifdef USE_MCAST

/**
 * Setup a multicast receiver socket, supports IPv4 and IPv6.
 * \param sock socket
 * \param addr receiver address
 * \return zero on success, -1 otherwise
 */
static int setup_mcast_rcvr(int sock, union sockaddr_union* addr)
{
	struct ip_mreq mreq;
#ifdef USE_IPV6
	struct ipv6_mreq mreq6;
#endif /* USE_IPV6 */

	if (addr->s.sa_family==AF_INET){
		memcpy(&mreq.imr_multiaddr, &addr->sin.sin_addr,
		       sizeof(struct in_addr));
		mreq.imr_interface.s_addr = htonl(INADDR_ANY);

		if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,&mreq,
			       sizeof(mreq))==-1){
			LM_ERR("setsockopt: %s\n", strerror(errno));
			return -1;
		}

#ifdef USE_IPV6
	} else if (addr->s.sa_family==AF_INET6){
		memcpy(&mreq6.ipv6mr_multiaddr, &addr->sin6.sin6_addr,
		       sizeof(struct in6_addr));
		mreq6.ipv6mr_interface = 0;
#ifdef __OS_linux
		if (setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6,
#else
		if (setsockopt(sock, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mreq6,
#endif
			       sizeof(mreq6))==-1){
			LM_ERR("setsockopt:%s\n",  strerror(errno));
			return -1;
		}

#endif /* USE_IPV6 */
	} else {
		LM_ERR("unsupported protocol family\n");
		return -1;
	}
	return 0;
}

#endif /* USE_MCAST */

/**
 * Initialize a UDP socket, supports multicast, IPv4 and IPv6.
 * \param sock_info socket that should be bind
 * \return zero on success, -1 otherwise
 */
int udp_init(struct socket_info* sock_info)
{
	union sockaddr_union* addr;
	int optval;
#ifdef USE_MCAST
	unsigned char m_optval;
#endif

	addr=&sock_info->su;
	sock_info->proto=PROTO_UDP;
	if (init_su(addr, &sock_info->address, sock_info->port_no)<0){
		LM_ERR("could not init sockaddr_union\n");
		goto error;
	}

	sock_info->socket = socket(AF2PF(addr->s.sa_family), SOCK_DGRAM, 0);
	if (sock_info->socket==-1){
		LM_ERR("socket: %s\n", strerror(errno));
		goto error;
	}
	/* set sock opts? */
	optval=1;
	if (setsockopt(sock_info->socket, SOL_SOCKET, SO_REUSEADDR ,
					(void*)&optval, sizeof(optval)) ==-1){
		LM_ERR("setsockopt: %s\n", strerror(errno));
		goto error;
	}
	/* tos */
	optval=tos;
	if (setsockopt(sock_info->socket, IPPROTO_IP, IP_TOS, (void*)&optval,
			sizeof(optval)) ==-1){
		LM_WARN("setsockopt tos: %s\n", strerror(errno));
		/* continue since this is not critical */
	}
#if defined (__linux__) && defined(UDP_ERRORS)
	optval=1;
	/* enable error receiving on unconnected sockets */
	if(setsockopt(sock_info->socket, SOL_IP, IP_RECVERR,
					(void*)&optval, sizeof(optval)) ==-1){
		LM_ERR("setsockopt: %s\n", strerror(errno));
		goto error;
	}
#endif

#ifdef USE_MCAST
	if ((sock_info->flags & SI_IS_MCAST)
	    && (setup_mcast_rcvr(sock_info->socket, addr)<0)){
			goto error;
	}
	/* set the multicast options */
	if (addr->s.sa_family==AF_INET){
		m_optval = mcast_loopback;
		if (setsockopt(sock_info->socket, IPPROTO_IP, IP_MULTICAST_LOOP,
						&m_optval, sizeof(m_optval))==-1){
			LM_WARN("setsockopt(IP_MULTICAST_LOOP): %s\n", strerror(errno));
			/* it's only a warning because we might get this error if the
			  network interface doesn't support multicasting */
		}
		if (mcast_ttl>=0){
			m_optval = mcast_ttl;
			if (setsockopt(sock_info->socket, IPPROTO_IP, IP_MULTICAST_TTL,
						&m_optval, sizeof(m_optval))==-1){
				LM_ERR("setsockopt (IP_MULTICAST_TTL): %s\n", strerror(errno));
				goto error;
			}
		}
#ifdef USE_IPV6
	} else if (addr->s.sa_family==AF_INET6){
		if (setsockopt(sock_info->socket, IPPROTO_IPV6, IPV6_MULTICAST_LOOP,
						&mcast_loopback, sizeof(mcast_loopback))==-1){
			LM_WARN("setsockopt (IPV6_MULTICAST_LOOP): %s\n", strerror(errno));
			/* it's only a warning because we might get this error if the
			  network interface doesn't support multicasting */
		}
		if (mcast_ttl>=0){
			if (setsockopt(sock_info->socket, IPPROTO_IP, IPV6_MULTICAST_HOPS,
						&mcast_ttl, sizeof(mcast_ttl))==-1){
				LM_ERR("setssckopt (IPV6_MULTICAST_HOPS): %s\n",
						strerror(errno));
				goto error;
			}
		}
#endif /* USE_IPV6*/
	} else {
		LM_ERR("unsupported protocol family %d\n", addr->s.sa_family);
		goto error;
	}
#endif /* USE_MCAST */

	if (probe_max_sock_buff(sock_info->socket,0,MAX_RECV_BUFFER_SIZE,
				BUFFER_INCREMENT)==-1) goto error;

	if (bind(sock_info->socket,  &addr->s, sockaddru_len(*addr))==-1){
		LM_ERR("bind(%x, %p, %d) on %s: %s\n", sock_info->socket, &addr->s,
				(unsigned)sockaddru_len(*addr),	sock_info->address_str.s,
				strerror(errno));
	#ifdef USE_IPV6
		if (addr->s.sa_family==AF_INET6)
			LM_ERR("might be caused by using a link "
					" local address, try site local or global\n");
	#endif
		goto error;
	}
	return 0;

error:
	return -1;
}


/**
 * Main UDP receiver loop, processes data from the network, does some error
 * checking and save it in an allocated buffer. This data is then forwarded
 * to the receive_msg function. If an dynamic buffer is used, the buffer
 * must be freed in later steps.
 * \see receive_msg
 * \see main_loop
 * \return -1 for errors
 */
int udp_rcv_loop(void)
{
	int len;
#ifdef DYN_BUF
	char* buf;
#else
	static char buf [BUF_SIZE+1];
#endif
	char *tmp;
	union sockaddr_union* from;
	unsigned int fromlen;
	struct receive_info ri;
	callback_list* p;
	str msg;

	from=(union sockaddr_union*) pkg_malloc(sizeof(union sockaddr_union));
	if (from==0){
		LM_ERR("out of pkg memory\n");
		goto error;
	}
	memset(from, 0 , sizeof(union sockaddr_union));
	ri.bind_address=bind_address; /* this will not change, we do it only once */
	ri.dst_port=bind_address->port_no;
	ri.dst_ip=bind_address->address;
	ri.proto=PROTO_UDP;
	ri.proto_reserved1=ri.proto_reserved2=0;
	for(;;){
#ifdef DYN_BUF
		buf=pkg_malloc(BUF_SIZE+1);
		if (buf==0){
			LM_ERR("could not allocate receive buffer\n");
			goto error;
		}
#endif
		fromlen=sockaddru_len(bind_address->su);
		len=recvfrom(bind_address->socket, buf, BUF_SIZE, 0, &from->s,
											&fromlen);
		if (len==-1){
			if (errno==EAGAIN){
				LM_DBG("packet with bad checksum received\n");
				continue;
			}
			LM_ERR("recvfrom:[%d] %s\n", errno, strerror(errno));
			if ((errno==EINTR)||(errno==EWOULDBLOCK)|| (errno==ECONNREFUSED))
				continue; /* goto skip;*/
			else goto error;
		}

#ifndef NO_ZERO_CHECKS
		if (len<MIN_UDP_PACKET) {
			LM_DBG("probing packet received len = %d\n", len);
			continue;
		}
#endif

		/* we must 0-term the messages, receive_msg expects it */
		buf[len]=0; /* no need to save the previous char */

		ri.src_su=*from;
		su2ip_addr(&ri.src_ip, from);
		ri.src_port=su_getport(from);

		msg.s = buf;
		msg.len = len;

		/* run callbacks if looks like non-SIP message*/
		if( !isalpha(msg.s[0]) ){    /* not-SIP related */
			for(p = cb_list; p; p = p->next){
				if(p->b == msg.s[1]){
					if (p->func(bind_address->socket, &ri, &msg, p->param)==0){
						/* buffer consumed by callback */
						break;
					}
				}
			}
			if (p) continue;
		}

#ifdef DBG_MSG_QA
		if (!dbg_msg_qa(msg.s, msg.len)) {
			LM_WARN("an incoming message didn't pass test,"
						"  drop it: %.*s\n", msg.len, msg.s );
			continue;
		}
#endif

		if (ri.src_port==0){
			tmp=ip_addr2a(&ri.src_ip);
			LM_INFO("dropping 0 port packet from %s\n", tmp);
			continue;
		}

		update_stat( pt[process_no].load, +1 );

		/* receive_msg must free buf too!*/
		receive_msg( msg.s, msg.len, &ri);

		update_stat( pt[process_no].load, -1 );
	}

error:
	if (from) pkg_free(from);
	return -1;
}


/**
 * Main UDP send function, called from msg_send.
 * \see msg_send
 * \param source send socket
 * \param buf sent data
 * \param len data length in bytes
 * \param to destination address
 * \return -1 on error, the return value from sento on success
 */
int udp_send(struct socket_info *source, char *buf, unsigned len,
										union sockaddr_union*  to)
{
	int n, tolen;

#ifdef DBG_MSG_QA
	/* aborts on error, does nothing otherwise */
	if (!dbg_msg_qa( buf, len )) {
		LM_ERR("dbg_msg_qa failed\n");
		abort();
	}
#endif

	tolen=sockaddru_len(*to);
again:
	n=sendto(source->socket, buf, len, 0, &to->s, tolen);
#ifdef XL_DEBUG
	LM_INFO("status: %d\n", n);
#endif
	if (n==-1){
		LM_ERR("sendto(sock,%p,%d,0,%p,%d): %s(%d)\n", buf,len,to,tolen,
				strerror(errno),errno);
		if (errno==EINTR) goto again;
		if (errno==EINVAL) {
			LM_CRIT("invalid sendtoparameters\n"
			"one possible reason is the server is bound to localhost and\n"
			"attempts to send to the net\n");
		}
	}
	return n;
}