#include <mrapp.h>
#include <rte_icmp.h>
#include <rte_ip.h>

static void icmp_echo_request_entry(struct vdev_instance* vdi, queue_id_t sid,
	struct rte_mbuf * mbuf, struct in_addr s_in_addr, struct in_addr d_in_addr)
{
    /* 将原来的报文复制一份 */
    struct rte_mbuf * mbuf_cloned = rte_pktmbuf_alloc(vdi->direct_pool);
    char * _pkt_data = rte_pktmbuf_append(mbuf_cloned, rte_pktmbuf_data_len(mbuf));
    rte_memcpy(_pkt_data, rte_pktmbuf_mtod(mbuf, char *), rte_pktmbuf_data_len(mbuf));

    struct icmp_hdr * icmp_hdr = rte_pktmbuf_mtod_offset(mbuf_cloned, struct icmp_hdr *,
        sizeof(struct ether_hdr) + sizeof(struct ipv4_hdr));

	uint32_t cksum;
	icmp_hdr->icmp_type = IP_ICMP_ECHO_REPLY;
	cksum = ~icmp_hdr->icmp_cksum & 0xffff;
	cksum += ~htons(IP_ICMP_ECHO_REQUEST << 8) & 0xffff;
	cksum += htons(IP_ICMP_ECHO_REPLY << 8);
	cksum = (cksum & 0xffff) + (cksum >> 16);
	cksum = (cksum & 0xffff) + (cksum >> 16);
	icmp_hdr->icmp_cksum = ~cksum;

    struct ipv4_hdr * ip_hdr = rte_pktmbuf_mtod_offset(mbuf_cloned,
        struct ipv4_hdr *, sizeof(struct ether_hdr));

    ip_hdr->src_addr = d_in_addr.s_addr;
    ip_hdr->dst_addr = s_in_addr.s_addr;
    ip_hdr->hdr_checksum = 0;
    ip_hdr->hdr_checksum = rte_ipv4_cksum(ip_hdr);

    struct ether_addr ether_addr_swap;
    struct ether_hdr * eth_hdr = rte_pktmbuf_mtod(mbuf_cloned, struct ether_hdr *);
    ether_addr_copy(&eth_hdr->s_addr, &ether_addr_swap);
    ether_addr_copy(&eth_hdr->d_addr, &eth_hdr->s_addr);
    ether_addr_copy(&ether_addr_swap, &eth_hdr->d_addr);

    mrapp_packet_fast_send_burst(vdi, 0, &mbuf_cloned, 1);
	return;
}

int icmp_entry(struct mr_instance * instance, struct vdev_instance* vdi, 
    queue_id_t qid, struct rte_mbuf* mbufs_in[], int nr_mbufs_in)
{
	int handled_packets = 0;
	struct in_addr s_in_addr;
	struct in_addr d_in_addr;

	for (int i = 0; i < nr_mbufs_in; i++)
	{
		struct rte_mbuf * mbuf = mbufs_in[i];
		if (unlikely(mbuf == NULL)) continue;

        // 仅处理IPv4报文
		if (!RTE_ETH_IS_IPV4_HDR(mbuf->packet_type)) continue;
		
		// 校验IPv4报文类型
		struct ipv4_hdr * ip_hdr = rte_pktmbuf_mtod_offset(mbuf, struct ipv4_hdr *,
			sizeof(struct ether_hdr));

		if (ip_hdr->next_proto_id != IPPROTO_ICMP) continue;

        s_in_addr.s_addr = ip_hdr->src_addr;
        d_in_addr.s_addr = ip_hdr->dst_addr;

		struct icmp_hdr * icmp_hdr = rte_pktmbuf_mtod_offset(mbuf, struct icmp_hdr *,
            sizeof(struct ether_hdr) + sizeof(struct ipv4_hdr));

		// ICMP回显请求，其他请求不处理
		if (icmp_hdr->icmp_type == IP_ICMP_ECHO_REQUEST)
		{
			icmp_echo_request_entry(vdi, qid, mbuf, s_in_addr, d_in_addr);
		}

		handled_packets++;
	}

	return handled_packets;
}