/*
 * Copyright 2017-present Open Networking Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef __CHECKSUMS__
#define __CHECKSUMS__

#include "headers.p4"

control verify_checksum_control(inout headers_t hdr,
                                inout local_metadata_t local_metadata) {
    apply {
        // Assume checksum is always correct.
    }
}

control compute_checksum_control(inout headers_t hdr,
                                 inout local_metadata_t local_metadata) {
    apply {
        update_checksum(hdr.ipv4.isValid(),
            {
                hdr.ipv4.version,
                hdr.ipv4.ihl,
                hdr.ipv4.dscp,
                hdr.ipv4.ecn,
                hdr.ipv4.len,
                hdr.ipv4.identification,
                hdr.ipv4.flags,
                hdr.ipv4.frag_offset,
                hdr.ipv4.ttl,
                hdr.ipv4.protocol,
                hdr.ipv4.src_addr,
                hdr.ipv4.dst_addr
            },
            hdr.ipv4.hdr_checksum,
            HashAlgorithm.csum16
        );

        // Need to recompute for the cloned packet.
        //TODO: https://github.com/p4lang/p4app/issues/43#issuecomment-378061934
        #ifdef __INT_HEADERS__
        update_checksum(hdr.report_ipv4.isValid(),
            {
                hdr.report_ipv4.version,
                hdr.report_ipv4.ihl,
                hdr.report_ipv4.dscp,
                hdr.report_ipv4.ecn,
                hdr.report_ipv4.len,
                hdr.report_ipv4.identification,
                hdr.report_ipv4.flags,
                hdr.report_ipv4.frag_offset,
                hdr.report_ipv4.ttl,
                hdr.report_ipv4.protocol,
                hdr.report_ipv4.src_addr,
                hdr.report_ipv4.dst_addr
            },
            hdr.report_ipv4.hdr_checksum,
            HashAlgorithm.csum16
        );
        #endif // __INT_HEADERS__
    }
}

#endif