/* -*- P4_16 -*- */
#include <core.p4>
#include <v1model.p4>

#include "headers.p4"
#include "parsers.p4"
#include "checksums.p4"
#include "settings.p4"


/*************************************************************************
**************  I N G R E S S   P R O C E S S I N G   *******************
*************************************************************************/

control MyIngress(inout headers hdr,
    inout metadata meta,
    inout standard_metadata_t standard_metadata) {

    /********************** GENERAL ACTIONS ***********************************/

    action drop() {
        mark_to_drop();
    }

	action set_egress_port (port_t out_port) {
        standard_metadata.egress_spec = out_port;
	}

    action controller_reply(task_t task) {
        meta.task = task;
        meta.ingress_port = standard_metadata.ingress_port;
        clone3(CloneType.I2E, 100, meta);
    }

    action controller_debug_table_id(table_t table_id) {
        meta.table_id = table_id;
        controller_reply(TASK_DEBUG);
    }

    action controller_debug() {
        controller_reply(TASK_DEBUG);
    }

    action multicast_pkg(mcast_t mcast_grp) {         /* Output PKG on correct ports (plural) */
        standard_metadata.mcast_grp = mcast_grp;
    }


    /********************** NAT64 / NAT46 ACTIONS ***********************************/

    /* changes for icmp6 -> icmp */
    action nat64_icmp6_generic()
    {
        hdr.icmp.setValid();
        hdr.ipv4.protocol = PROTO_ICMP; // overwrite generic same protocol assumption

        /* trigger checksumming */
        meta.switch_task = TASK_CHECKSUM_ICMP;

        meta.chk_icmp = 1;

        hdr.icmp6.setInvalid();

        /* not needed, as we don't translate them (yet/ever) */
        hdr.icmp6_na_ns.setInvalid();
        hdr.icmp6_option_link_layer_addr.setInvalid();
    }

    /* NAT64 protocol unspecific changes */
    action nat64_generic(ipv4_addr_t src, ipv4_addr_t dst) {
		hdr.ipv4.setValid();

        /* Stuff that might need to be fixed */
        hdr.ipv4.version        = (bit<4>)4;
        hdr.ipv4.diff_serv      = (bit<6>)0;                             // no ToS
		hdr.ipv4.ecn            = (bit<2>)0;                             // unsupported

        /* 5 is ok as long as we don't use options / padding /
        anything after the destination address */
        hdr.ipv4.ihl            = (bit<4>) 5;                            // internet header length: 4*5 = 20
        hdr.ipv4.totalLen       = (bit<16>) hdr.ipv6.payload_length + 20; // ok under above constraints

        hdr.ipv4.identification = (bit<16>) 0;                           // no support for fragments
        hdr.ipv4.flags          = (bit<3>)  0;                           // DF bit and more fragments, unsupported ATM
        hdr.ipv4.fragOffset     = (bit<13>) 0;                           // 0 as there are no fragments

        /* Stuff that should be fine */
		hdr.ethernet.ethertype  = TYPE_IPV4;

        hdr.ipv4.dst_addr       = dst;
        hdr.ipv4.src_addr       = src;

        hdr.ipv4.ttl            = hdr.ipv6.hop_limit;

        hdr.ipv4.protocol       = hdr.ipv6.next_header;

        hdr.ipv6.setInvalid();
	}

    /* nat64_prefix is the same as the matching key, but without the mask */
    action nat64_static(ipv6_addr_t v6_src, ipv4_addr_t v4_dst, ipv6_addr_t nat64_prefix) {
        ipv6_addr_t src_offset = hdr.ipv6.src_addr - v6_src;
        ipv4_addr_t src        = v4_dst + (ipv4_addr_t) src_offset;

        ipv4_addr_t dst        = (ipv4_addr_t) (hdr.ipv6.dst_addr - nat64_prefix);

        nat64_generic(src, dst);
    }

    /* From https://tools.ietf.org/html/rfc792 (IPv4)

Echo or Echo Reply Message

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |     Code      |          Checksum             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Identifier          |        Sequence Number        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Data ...
   +-+-+-+-+-


    From https://tools.ietf.org/html/rfc4443#section-4.1

4.1.  Echo Request Message

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |     Code      |          Checksum             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Identifier          |        Sequence Number        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Data ...
      +-+-+-+-+-

4.2.  Echo Reply Message

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |     Code      |          Checksum             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Identifier          |        Sequence Number        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Data ...
      +-+-+-+-+-


    Type / code are different in ICMP4 and ICMP6!

    */


    /* changes for icmp6 -> icmp */
    action nat46_icmp_generic()
    {
        hdr.icmp6.setValid();
        hdr.ipv6.next_header = PROTO_ICMP6;

        meta.chk_icmp6 = 1;

        hdr.icmp.setInvalid();
    }

    /* NAT46: protocol unspecific changes */
	action nat46_generic(ipv6_addr_t src, ipv6_addr_t dst) {
		hdr.ipv6.setValid();
        hdr.ipv4.setInvalid();

		hdr.ethernet.ethertype = TYPE_IPV6;

		hdr.ipv6.dst_addr = dst;
		hdr.ipv6.src_addr = src;

		hdr.ipv6.version = (bit<4>)6;
		hdr.ipv6.traffic_class = (bit<8>) hdr.ipv4.diff_serv;
		hdr.ipv6.flow_label = (bit<20>) 0;
		hdr.ipv6.payload_length = (bit<16>) hdr.ipv4.totalLen - 20;

		hdr.ipv6.next_header = hdr.ipv4.protocol;
		hdr.ipv6.hop_limit = hdr.ipv4.ttl;

	}


    /* matching key: v4_network specified again */
    action nat46_static(ipv6_addr_t v6_src, ipv4_addr_t v4_dst, ipv6_addr_t nat64_prefix) {
        ipv6_addr_t src = nat64_prefix + (ipv6_addr_t) hdr.ipv4.src_addr;

        ipv4_addr_t dst_offset = hdr.ipv4.dst_addr - v4_dst;
        ipv6_addr_t dst = v6_src + (ipv6_addr_t) dst_offset;

        nat46_generic(src, dst);
    }

    table nat64 {
        key = {
            hdr.ipv6.dst_addr: lpm;
        }
        actions = {
            controller_debug;
            nat64_static;
            controller_debug_table_id;
            NoAction;
        }
        size = NAT64_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_NAT64);
    }

    table nat46 {
        key = {
            hdr.ipv4.dst_addr: lpm;
        }
        actions = {
            controller_debug;
            nat46_static;
            controller_debug_table_id;
            NoAction;
        }
        size = NAT64_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_NAT46);
    }


    /********************** ICMP6 + NDP ***********************************/

    /* old/unused action */
    action icmp6_answer() {
        if(hdr.icmp6.isValid()) {
            if(hdr.icmp6.code == ICMP6_ECHO_REQUEST) {
                ipv6_addr_t tmp = hdr.ipv6.src_addr;
                hdr.ipv6.src_addr = hdr.ipv6.dst_addr;
                hdr.ipv6.dst_addr = tmp;
                hdr.icmp6.code = ICMP6_ECHO_REPLY;
            }
        }
    }

    action icmp6_neighbor_solicitation(ipv6_addr_t addr, mac_addr_t mac_addr) {
        /* egress = ingress */
        standard_metadata.egress_spec = standard_metadata.ingress_port;

        /* 1. IPv6 changes */
        hdr.ipv6.dst_addr = hdr.ipv6.src_addr;
        hdr.ipv6.src_addr = addr;

        /* 2. ICMP6 changes */
        hdr.icmp6.type = ICMP6_NA;
        hdr.icmp6.code = 0;
        hdr.icmp6.checksum = 42; // checksum is calculated in deparser - marking with 42 to see whether it is calculated

        /* 3. icmp6/neighbor advertisement: values taken from real world answers */
        hdr.icmp6_na_ns.router       = 0;
        hdr.icmp6_na_ns.solicitated  = 1;
        hdr.icmp6_na_ns.override     = 1;
        hdr.icmp6_na_ns.reserved     = 0;
        hdr.icmp6_na_ns.target_addr  = addr;

        /* 4. Link layer options */
        hdr.icmp6_option_link_layer_addr.type = ICMP6_NDP_OPT_TARGET_LL;
        hdr.icmp6_option_link_layer_addr.ll_length = 1; /* 1* 64 bit */
        hdr.icmp6_option_link_layer_addr.mac_addr = mac_addr;

        /* 5. Checksum trigger/info */
        meta.chk_icmp6_na_ns = 1;
        meta.cast_length = (bit<32>) hdr.ipv6.payload_length;
    }

    action icmp6_echo_reply() {
        mac_addr_t mac_tmp = hdr.ethernet.dst_addr;
        hdr.ethernet.dst_addr = hdr.ethernet.src_addr;
        hdr.ethernet.src_addr = mac_tmp;

        ipv6_addr_t addr_tmp = hdr.ipv6.dst_addr;
        hdr.ipv6.dst_addr = hdr.ipv6.src_addr;
        hdr.ipv6.src_addr = addr_tmp;

        hdr.icmp6.type = ICMP6_ECHO_REPLY;

        meta.chk_icmp6 = 1;

        meta.cast_length = (bit<32>) hdr.ipv6.payload_length;
    }

    table icmp6 {
        key = {
            hdr.ipv6.dst_addr: lpm;
            hdr.icmp6.type: exact;
        }
        actions = {
            controller_debug;
            icmp6_neighbor_solicitation;
            icmp6_echo_reply;
            controller_debug_table_id;
            NoAction;
        }
        size = ICMP6_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_ICMP6);
//        default_action = NoAction;
    }

    /********************** debugging / general support ***********************************/

    // table port2mcast {
    //     key = {
    //         standard_metadata.ingress_port : exact;
    //     }
    //     actions = {
	// 		multicast_pkg;
    //         controller_debug;
    //         NoAction;
    //     }
    //     size = NDP_TABLE_SIZE;
    //     default_action = NoAction;
    // }

    // /* Handle multicast registration of NDP */
    // table addr2mcast {
    //     key = {
    //         hdr.ipv6.dst_addr: exact;
    //     }
    //     actions = {
	// 		multicast_pkg;
    //         controller_debug;
    //         NoAction;
    //     }
    //     size = NDP_TABLE_SIZE;
    //     default_action = NoAction;
        // }

    /********************** ARP ***********************************/

    action arp_reply(mac_addr_t mac_addr) {
        /* swap */
        ipv4_addr_t ipv4_src = hdr.arp.dst_ipv4_addr;
        ipv4_addr_t ipv4_dst = hdr.arp.src_ipv4_addr;

        /* swap/add */
        mac_addr_t mac_src = mac_addr;
        mac_addr_t mac_dst = hdr.arp.src_mac_addr;

        /* fill the ethernet header */
        hdr.ethernet.dst_addr = mac_dst;
        hdr.ethernet.src_addr = mac_src;

        /* fill the arp header */
        hdr.arp.dst_mac_addr  = mac_dst;
        hdr.arp.src_mac_addr  = mac_src;

        /* swapping */
        hdr.arp.dst_ipv4_addr = ipv4_dst;
        hdr.arp.src_ipv4_addr = ipv4_src;

        hdr.arp.opcode = ARP_REPLY;
    }

    table v4_arp {
        key = {
            hdr.ethernet.dst_addr: exact;
            hdr.arp.opcode: exact;
            hdr.arp.dst_ipv4_addr: lpm;
        }
        actions = {
            controller_debug_table_id;
            arp_reply;
            NoAction;
        }
        size = ICMP6_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_ARP);
    }

    table v4_arp_egress {
        key = {
            hdr.arp.dst_ipv4_addr: lpm;
        }
        actions = {
            controller_debug_table_id;
            set_egress_port;
            NoAction;
        }
        size = ICMP6_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_ARP_EGRESS);
    }


	/********************** ROUTING (egress definiton) TABLES ***********************************/

    table v6_networks {
        key = {
            hdr.ipv6.dst_addr: lpm;
        }
        actions = {
			set_egress_port;
            controller_debug;
            controller_reply;
            controller_debug_table_id;
            NoAction;
        }
        size = ROUTING_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_V6_NETWORKS);
    }

    table v4_networks {
        key = {
            hdr.ipv4.dst_addr: lpm;
        }
        actions = {
			set_egress_port;
            controller_debug;
            controller_debug_table_id;
            NoAction;
        }
        size = ROUTING_TABLE_SIZE;
        default_action = controller_debug_table_id(TABLE_V4_NETWORKS);
    }

	/********************** APPLYING TABLES ***********************************/
    apply {
        if(hdr.ipv6.isValid()) {
            if(nat64.apply().hit) { /* generic nat64 done */
                if(hdr.icmp6.isValid()) {
                    nat64_icmp6_generic();

                    if(hdr.icmp6.type == ICMP6_ECHO_REPLY) {
                        hdr.icmp.type = ICMP_ECHO_REPLY;
                    }
                    if(hdr.icmp6.type == ICMP6_ECHO_REQUEST) {
                        hdr.icmp.type = ICMP_ECHO_REQUEST;
                    }
                }

                v4_networks.apply();       /* apply egress for IPv4 */
                exit;                      /* no further v6 processing */
            }

            icmp6.apply();       /* icmp6 echo, icmp6 ndp */

            v6_networks.apply(); /* regular egress / routing */
        } else if(hdr.ipv4.isValid()) {
            if(nat46.apply().hit) {
                if(hdr.icmp.isValid()) {
                    nat46_icmp_generic();

                    if(hdr.icmp.type == ICMP_ECHO_REPLY) {
                        hdr.icmp6.type = ICMP6_ECHO_REPLY;
                    }
                    if(hdr.icmp.type == ICMP_ECHO_REQUEST) {
                        hdr.icmp6.type = ICMP6_ECHO_REQUEST;
                    }
                }

                v6_networks.apply();
                exit;
            }
            v4_networks.apply();             /* regular routing, egress */
        } else if(hdr.arp.isValid()) {
            if(v4_arp.apply().hit) {
                v4_arp_egress.apply();
            }
        }
    }
}


/*************************************************************************
****************  E G R E S S   P R O C E S S I N G   *******************
*************************************************************************/

control MyEgress(inout headers hdr,
                 inout metadata meta,
                 inout standard_metadata_t standard_metadata) {
	apply {
        // ingress clone
        if (standard_metadata.instance_type == 1){
            hdr.cpu.setValid();
            hdr.cpu.task = meta.task;
            hdr.cpu.ethertype = hdr.ethernet.ethertype;
            hdr.cpu.ingress_port = (bit<16>) meta.ingress_port;
            hdr.cpu.table_id = meta.table_id;

            hdr.ethernet.ethertype = TYPE_CPU;
        }
	}
}

/*************************************************************************
***********************  S W I T C H  *******************************
*************************************************************************/

V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;