/*
 * sfe_ipv4_pppoe_br.c
 *	Shortcut forwarding engine - IPv4 PPPoE bridge implementation
 *
 * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <linux/skbuff.h>
#include <net/udp.h>
#include <linux/etherdevice.h>
#include <linux/version.h>

#include "sfe_debug.h"
#include "sfe_api.h"
#include "sfe.h"
#include "sfe_ipv4.h"
#include "sfe_pppoe.h"
#include "sfe_vlan.h"

/*
 * sfe_ipv4_recv_pppoe_bridge()
 *	Process PPPoE bridge packets using 3-tuple acceleration
 *
 */
int sfe_ipv4_recv_pppoe_bridge(struct sfe_ipv4 *si, struct sk_buff *skb, struct net_device *dev,
			      unsigned int len, struct iphdr *iph, unsigned int ihl, struct sfe_l2_info *l2_info)
{
	struct sfe_ipv4_connection_match *cm;
	u32 service_class_id;
	struct net_device *xmit_dev;
	int ret;
	bool fast_xmit;
	netdev_features_t features;

	rcu_read_lock();

	cm = sfe_ipv4_find_connection_match_rcu(si, dev, IPPROTO_RAW, iph->saddr, 0, iph->daddr, htons(sfe_l2_pppoe_session_id_get(l2_info)));
	if (unlikely(!cm)) {
		rcu_read_unlock();
		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_PPPOE_BR_NOT_IN_CME);
		DEBUG_TRACE("%px: no connection found in 3-tuple lookup for PPPoE bridge flow\n", skb);
		return 0;
	}

	/*
	 * Source interface validate.
	 */
	if (unlikely((cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_SRC_INTERFACE_CHECK) && (cm->match_dev != dev))) {
		if (!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_SRC_INTERFACE_CHECK_NO_FLUSH)) {
			struct sfe_ipv4_connection *c = cm->connection;
			DEBUG_TRACE("flush on source interface check failure\n");
			spin_lock_bh(&si->lock);
			ret = sfe_ipv4_remove_connection(si, c);
			spin_unlock_bh(&si->lock);

			if (ret) {
				sfe_ipv4_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
			}
		}
		rcu_read_unlock();
		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INVALID_SRC_IFACE);
		DEBUG_TRACE("exception the packet on source interface check failure\n");
		return 0;
	}

	/*
	 * Do we expect an ingress VLAN tag for this flow?
	 */
	if (unlikely(!sfe_vlan_validate_ingress_tag(skb, cm->ingress_vlan_hdr_cnt, cm->ingress_vlan_hdr, l2_info))) {
		rcu_read_unlock();
		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INGRESS_VLAN_TAG_MISMATCH);
		DEBUG_TRACE("VLAN tag mismatch. skb=%px\n", skb);
		return 0;
	}

	/*
	 * Check if skb has enough headroom to write L2 headers
	 */
	if (unlikely(skb_headroom(skb) < cm->l2_hdr_size)) {
		rcu_read_unlock();
		DEBUG_WARN("%px: Not enough headroom: %u\n", skb, skb_headroom(skb));
		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_NO_HEADROOM);
		return 0;
	}

	/*
	 * Restore PPPoE header back
	 */
	__skb_push(skb, PPPOE_SES_HLEN);

	/*
	 * Update traffic stats.
	 */
	atomic_inc(&cm->rx_packet_count);
	atomic_add(len, &cm->rx_byte_count);

	xmit_dev = cm->xmit_dev;
	skb->dev = xmit_dev;

	/*
	 * Check to see if we need to add VLAN tags
	 */
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_INSERT_EGRESS_VLAN_TAG)) {
		sfe_vlan_add_tag(skb, cm->egress_vlan_hdr_cnt, cm->egress_vlan_hdr);
	}

	/*
	 * Check to see if we need to write an Ethernet header.
	 */
	if (likely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_WRITE_L2_HDR)) {
		if (unlikely(!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_WRITE_FAST_ETH_HDR))) {
			dev_hard_header(skb, xmit_dev, ntohs(skb->protocol),
					cm->xmit_dest_mac, cm->xmit_src_mac, len);
		} else {
			/*
			 * For the simple case we write this really fast.
			 */
			struct ethhdr *eth = (struct ethhdr *)__skb_push(skb, ETH_HLEN);
			eth->h_proto = skb->protocol;
			ether_addr_copy((u8 *)eth->h_dest, (u8 *)cm->xmit_dest_mac);
			ether_addr_copy((u8 *)eth->h_source, (u8 *)cm->xmit_src_mac);
		}
	}

	/*
	 * Update priority of skb.
	 */
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PRIORITY_REMARK)) {
		skb->priority = cm->priority;
	}

	/*
	 * Mark outgoing packet.
	 */
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_MARK)) {
		skb->mark = cm->mark;
		/*
		 * Update service class stats if SAWF is valid.
		 */
		if (likely(cm->sawf_valid)) {
			service_class_id = SFE_GET_SAWF_SERVICE_CLASS(cm->mark);
			sfe_ipv4_service_class_stats_inc(si, service_class_id, len);
		}
	}

	/*
	 * For the first packets, check if it could got fast xmit.
	 */
	if (unlikely(!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_FAST_XMIT_FLOW_CHECKED)
				&& (cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_FAST_XMIT_DEV_ADMISSION))){
		cm->features = netif_skb_features(skb);
		if (likely(sfe_fast_xmit_check(skb, cm->features))) {
			cm->flags |= SFE_IPV4_CONNECTION_MATCH_FLAG_FAST_XMIT;
		}
		cm->flags |= SFE_IPV4_CONNECTION_MATCH_FLAG_FAST_XMIT_FLOW_CHECKED;
	}
	features = cm->features;

	fast_xmit = !!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_FAST_XMIT);

	rcu_read_unlock();

	this_cpu_inc(si->stats_pcpu->pppoe_bridge_packets_3tuple_forwarded64);
	this_cpu_inc(si->stats_pcpu->packets_forwarded64);

	/*
	 * We're going to check for GSO flags when we transmit the packet so
	 * start fetching the necessary cache line now.
	 */
	prefetch(skb_shinfo(skb));

	/*
	 * We do per packet condition check before we could fast xmit the
	 * packet.
	 */
	if (likely(fast_xmit && dev_fast_xmit(skb, xmit_dev, features))) {
		this_cpu_inc(si->stats_pcpu->packets_fast_xmited64);
		return 1;
	}

	/*
	 * Mark that this packet has been fast forwarded.
	 */
	skb->fast_forwarded = 1;

	/*
	 * Send the packet on its way.
	 */
	dev_queue_xmit(skb);

	return 1;
}