/*
 * Copyright (c) 2004-2013 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <sys/param.h>	/* for definition of NULL */
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <libkern/OSAtomic.h>

#include <machine/endian.h>

#define _IP_VHL
#include <net/if_var.h>
#include <net/route.h>
#include <net/kpi_protocol.h>

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet6/in6_var.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/ip_var.h>
#include <netinet6/ip6_var.h>
#include <netinet/kpi_ipfilter_var.h>


/*
 * kipf_lock and kipf_ref protect the linkage of the list of IP filters
 * An IP filter can be removed only when kipf_ref is zero
 * If an IP filter cannot be removed because kipf_ref is not null, then 
 * the IP filter is marjed and kipf_delayed_remove is set so that when 
 * kipf_ref eventually goes down to zero, the IP filter is removed
 */
decl_lck_mtx_data(static, kipf_lock_data);
static lck_mtx_t *kipf_lock = &kipf_lock_data;
static u_int32_t kipf_ref = 0;
static u_int32_t kipf_delayed_remove = 0;
u_int32_t kipf_count = 0;

__private_extern__ struct ipfilter_list	ipv4_filters = TAILQ_HEAD_INITIALIZER(ipv4_filters);
__private_extern__ struct ipfilter_list	ipv6_filters = TAILQ_HEAD_INITIALIZER(ipv6_filters);
__private_extern__ struct ipfilter_list	tbr_filters = TAILQ_HEAD_INITIALIZER(tbr_filters);

__private_extern__ void
ipf_ref(void)
{
	lck_mtx_lock(kipf_lock);
    kipf_ref++;
	lck_mtx_unlock(kipf_lock);
}

__private_extern__ void
ipf_unref(void)
{
	lck_mtx_lock(kipf_lock);

    if (kipf_ref == 0)
    	panic("ipf_unref: kipf_ref == 0\n");
    	
    kipf_ref--;
    if (kipf_ref == 0 && kipf_delayed_remove != 0) {
    	struct ipfilter *filter;

		while ((filter = TAILQ_FIRST(&tbr_filters))) {
			ipf_detach_func ipf_detach = filter->ipf_filter.ipf_detach;
			void* cookie = filter->ipf_filter.cookie;
			
			TAILQ_REMOVE(filter->ipf_head, filter, ipf_link);
			TAILQ_REMOVE(&tbr_filters, filter, ipf_tbr);
			kipf_delayed_remove--;

			if (ipf_detach) {
				lck_mtx_unlock(kipf_lock);
				ipf_detach(cookie);
				lck_mtx_lock(kipf_lock);
				/* In case some filter got to run while we released the lock */
				if (kipf_ref != 0)
					break;
			}			
		}
   	} 
	lck_mtx_unlock(kipf_lock);
}

static errno_t
ipf_add(
	const struct ipf_filter* filter,
	ipfilter_t *filter_ref,
	struct ipfilter_list *head)
{
	struct ipfilter	*new_filter;
	if (filter->name == NULL || (filter->ipf_input == NULL && filter->ipf_output == NULL))
		return EINVAL;
	
	MALLOC(new_filter, struct ipfilter*, sizeof(*new_filter), M_IFADDR, M_WAITOK);
	if (new_filter == NULL)
		return ENOMEM;
	
	lck_mtx_lock(kipf_lock);
	new_filter->ipf_filter = *filter;
	new_filter->ipf_head = head;
	
	TAILQ_INSERT_HEAD(head, new_filter, ipf_link);
	
	lck_mtx_unlock(kipf_lock);
	
	*filter_ref = (ipfilter_t)new_filter;

	/* This will force TCP to re-evaluate its use of TSO */
	OSAddAtomic(1, &kipf_count);
	routegenid_update();

	return 0;
}

errno_t
ipf_addv4(
	const struct ipf_filter* filter,
	ipfilter_t *filter_ref)
{
	return ipf_add(filter, filter_ref, &ipv4_filters);
}

errno_t
ipf_addv6(
	const struct ipf_filter* filter,
	ipfilter_t *filter_ref)
{
	return ipf_add(filter, filter_ref, &ipv6_filters);
}

errno_t
ipf_remove(
	ipfilter_t filter_ref)
{
	struct ipfilter	*match = (struct ipfilter*)filter_ref;
	struct ipfilter_list *head;
	
	if (match == 0 || (match->ipf_head != &ipv4_filters && match->ipf_head != &ipv6_filters))
		return EINVAL;
	
	head = match->ipf_head;
	
	lck_mtx_lock(kipf_lock);
	TAILQ_FOREACH(match, head, ipf_link) {
		if (match == (struct ipfilter*)filter_ref) {
			ipf_detach_func ipf_detach = match->ipf_filter.ipf_detach;
			void* cookie = match->ipf_filter.cookie;
			
			/*
			 * Cannot detach when they are filters running
			 */
			if (kipf_ref) {
				kipf_delayed_remove++;
				TAILQ_INSERT_TAIL(&tbr_filters, match, ipf_tbr);
				match->ipf_filter.ipf_input = 0;
				match->ipf_filter.ipf_output = 0;
				lck_mtx_unlock(kipf_lock);
			} else {
				TAILQ_REMOVE(head, match, ipf_link);
				lck_mtx_unlock(kipf_lock);
				if (ipf_detach)
					ipf_detach(cookie);
				FREE(match, M_IFADDR);

				/* This will force TCP to re-evaluate its use of TSO */
				OSAddAtomic(-1, &kipf_count);
				routegenid_update();

			}
			return 0;
		}
	}
	lck_mtx_unlock(kipf_lock);
	
	return ENOENT;
}

int log_for_en1 = 0;

errno_t
ipf_inject_input(
	mbuf_t data,
	ipfilter_t filter_ref)
{
	struct mbuf	*m = (struct mbuf*)data;
	struct m_tag *mtag = 0;
	struct ip *ip = mtod(m, struct ip *);
	u_int8_t	vers;
	int hlen;
	errno_t error = 0;
	protocol_family_t proto;

	vers = IP_VHL_V(ip->ip_vhl);
	
	switch (vers) {
		case 4:
			proto = PF_INET;
			break;
		case 6:
			proto = PF_INET6;
			break;
		default:
			error = ENOTSUP;
			goto done;
	}
	
	if (filter_ref == 0 && m->m_pkthdr.rcvif == 0) {
		m->m_pkthdr.rcvif = lo_ifp;
		m->m_pkthdr.csum_data = 0;
		m->m_pkthdr.csum_flags = 0;
		if (vers == 4) {
			hlen = IP_VHL_HL(ip->ip_vhl) << 2;
			ip->ip_sum = 0;
			ip->ip_sum = in_cksum(m, hlen);
		}
	}
	if (filter_ref != 0) {
		mtag = m_tag_create(KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_IPFILT,
					 	   sizeof (ipfilter_t), M_NOWAIT, m);
		if (mtag == NULL) {
			error = ENOMEM;
			goto done;
		}	
		*(ipfilter_t*)(mtag+1) = filter_ref;
		m_tag_prepend(m, mtag);
	}
	
	error = proto_inject(proto, data);

done:
	return error;
}

static errno_t
ipf_injectv4_out(mbuf_t data, ipfilter_t filter_ref, ipf_pktopts_t options)
{
	struct route ro;
	struct ip	*ip;
	struct mbuf	*m = (struct mbuf*)data;
	errno_t error = 0;
	struct m_tag *mtag = NULL;
	struct ip_moptions *imo = NULL;
	struct ip_out_args ipoa = { IFSCOPE_NONE, { 0 }, 0, 0 };

	/* Make the IP header contiguous in the mbuf */
	if ((size_t)m->m_len < sizeof (struct ip)) {
		m = m_pullup(m, sizeof (struct ip));
		if (m == NULL)
			return (ENOMEM);
	}
	ip = (struct ip *)m_mtod(m);

	if (filter_ref != 0) {
		mtag = m_tag_create(KERNEL_MODULE_TAG_ID,
		    KERNEL_TAG_TYPE_IPFILT, sizeof (ipfilter_t), M_NOWAIT, m);
		if (mtag == NULL) {
			m_freem(m);
			return (ENOMEM);
		}
		*(ipfilter_t *)(mtag + 1) = filter_ref;
		m_tag_prepend(m, mtag);
	}

	if (options != NULL && (options->ippo_flags & IPPOF_MCAST_OPTS) &&
	    (imo = ip_allocmoptions(M_DONTWAIT)) != NULL) {
		imo->imo_multicast_ifp = options->ippo_mcast_ifnet;
		imo->imo_multicast_ttl = options->ippo_mcast_ttl;
		imo->imo_multicast_loop = options->ippo_mcast_loop;
	}

	if (options != NULL) {
		if (options->ippo_flags & IPPOF_SELECT_SRCIF)
			ipoa.ipoa_flags |= IPOAF_SELECT_SRCIF;
		if (options->ippo_flags & IPPOF_BOUND_IF) {
			ipoa.ipoa_flags |= IPOAF_BOUND_IF;
			ipoa.ipoa_boundif = options->ippo_flags >>
			    IPPOF_SHIFT_IFSCOPE;
		}
		if (options->ippo_flags & IPPOF_NO_IFT_CELLULAR)
			ipoa.ipoa_flags |= IPOAF_NO_CELLULAR;
		if (options->ippo_flags & IPPOF_BOUND_SRCADDR)
			ipoa.ipoa_flags |= IPOAF_BOUND_SRCADDR;
	}

	bzero(&ro, sizeof(struct route));

	/* Put ip_len and ip_off in host byte order, ip_output expects that */

#if BYTE_ORDER != BIG_ENDIAN
	NTOHS(ip->ip_len);
	NTOHS(ip->ip_off);
#endif

	/* Send; enforce source interface selection via IP_OUTARGS flag */
	error = ip_output(m, NULL, &ro,
	    IP_ALLOWBROADCAST | IP_RAWOUTPUT | IP_OUTARGS, imo, &ipoa);

	/* Release the route */
	ROUTE_RELEASE(&ro);

	if (imo != NULL)
		IMO_REMREF(imo);

	return (error);
}

#if INET6
static errno_t
ipf_injectv6_out(mbuf_t data, ipfilter_t filter_ref, ipf_pktopts_t options)
{
	struct route_in6 ro;
	struct ip6_hdr	*ip6;
	struct mbuf	*m = (struct mbuf*)data;
	errno_t error = 0;
	struct m_tag *mtag = NULL;
	struct ip6_moptions *im6o = NULL;
	struct ip6_out_args ip6oa = { IFSCOPE_NONE, { 0 }, 0, 0 };

	/* Make the IP header contiguous in the mbuf */
	if ((size_t)m->m_len < sizeof(struct ip6_hdr)) {
		m = m_pullup(m, sizeof(struct ip6_hdr));
		if (m == NULL)
			return (ENOMEM);
	}
	ip6 = (struct ip6_hdr*)m_mtod(m);

	if (filter_ref != 0) {
		mtag = m_tag_create(KERNEL_MODULE_TAG_ID,
		    KERNEL_TAG_TYPE_IPFILT, sizeof (ipfilter_t), M_NOWAIT, m);
		if (mtag == NULL) {
			m_freem(m);
			return (ENOMEM);
		}
		*(ipfilter_t *)(mtag + 1) = filter_ref;
		m_tag_prepend(m, mtag);
	}

	if (options != NULL && (options->ippo_flags & IPPOF_MCAST_OPTS) &&
	    (im6o = ip6_allocmoptions(M_DONTWAIT)) != NULL) {
		im6o->im6o_multicast_ifp = options->ippo_mcast_ifnet;
		im6o->im6o_multicast_hlim = options->ippo_mcast_ttl;
		im6o->im6o_multicast_loop = options->ippo_mcast_loop;
	}

	if (options != NULL) {
		if (options->ippo_flags & IPPOF_SELECT_SRCIF)
			ip6oa.ip6oa_flags |= IP6OAF_SELECT_SRCIF;
		if (options->ippo_flags & IPPOF_BOUND_IF) {
			ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;
			ip6oa.ip6oa_boundif = options->ippo_flags >>
			    IPPOF_SHIFT_IFSCOPE;
		}
		if (options->ippo_flags & IPPOF_NO_IFT_CELLULAR)
			ip6oa.ip6oa_flags |= IP6OAF_NO_CELLULAR;
		if (options->ippo_flags & IPPOF_BOUND_SRCADDR)
			ip6oa.ip6oa_flags |= IP6OAF_BOUND_SRCADDR;
	}

	bzero(&ro, sizeof(struct route_in6));

	/*
	 * Send  mbuf and ifscope information. Check for correctness
	 * of ifscope information is done while searching for a route in 
	 * ip6_output.
	 */
	error = ip6_output(m, NULL, &ro, IPV6_OUTARGS, im6o, NULL, &ip6oa);

	/* Release the route */
	ROUTE_RELEASE(&ro);

	if (im6o != NULL)
		IM6O_REMREF(im6o);

	return (error);
}
#endif /* INET6 */

errno_t
ipf_inject_output(
	mbuf_t data,
	ipfilter_t filter_ref,
	ipf_pktopts_t options)
{
	struct mbuf	*m = (struct mbuf*)data;
	u_int8_t	vers;
	errno_t		error = 0;

	/* Make one byte of the header contiguous in the mbuf */
	if (m->m_len < 1) {
		m = m_pullup(m, 1);
		if (m == NULL) 
			goto done;
	}
	
	vers = (*(u_int8_t*)m_mtod(m)) >> 4;
	switch (vers)
	{
		case 4:
			error = ipf_injectv4_out(data, filter_ref, options);
			break;
#if INET6
		case 6:
			error = ipf_injectv6_out(data, filter_ref, options);
			break;
#endif
		default:
			m_freem(m);
			error = ENOTSUP;
			break;
	}

done:	
	return error;
}

__private_extern__ ipfilter_t
ipf_get_inject_filter(struct mbuf *m)
{
	ipfilter_t filter_ref = 0;
	struct m_tag *mtag;
	
	mtag = m_tag_locate(m, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_IPFILT, NULL);
	if (mtag) {
		filter_ref = *(ipfilter_t *)(mtag+1);
		
		m_tag_delete(m, mtag);
	}
	return filter_ref;
}

__private_extern__ int
ipf_init(void)
{
	int error = 0;
	lck_grp_attr_t *grp_attributes = 0;
	lck_attr_t *lck_attributes = 0;
	lck_grp_t *lck_grp = 0;
	
	grp_attributes = lck_grp_attr_alloc_init();
	if (grp_attributes == 0) {
		printf("ipf_init: lck_grp_attr_alloc_init failed\n");
		error = ENOMEM;
		goto done;
	}
	
	lck_grp = lck_grp_alloc_init("IP Filter", grp_attributes);
	if (lck_grp == 0) {
		printf("ipf_init: lck_grp_alloc_init failed\n");
		error = ENOMEM;
		goto done;
	}
	
	lck_attributes = lck_attr_alloc_init();
	if (lck_attributes == 0) {
		printf("ipf_init: lck_attr_alloc_init failed\n");
		error = ENOMEM;
		goto done;
	}
	
	lck_mtx_init(kipf_lock, lck_grp, lck_attributes);

	done:
	if (lck_grp) {
		lck_grp_free(lck_grp);
		lck_grp = 0;
	}
	if (grp_attributes) {
		lck_grp_attr_free(grp_attributes);
		grp_attributes = 0;
	}
	if (lck_attributes) {
		lck_attr_free(lck_attributes);
		lck_attributes = 0;
	}
	
	return error;
}