/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * 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.
 */

#define CACHE_MAP_SIZE 1024
#define MAX_POLICIES 16

#define SRC_IP_MASK_FLAG     1
#define DST_IP_MASK_FLAG     2
#define SRC_PORT_MASK_FLAG   4
#define PROTO_MASK_FLAG      8

#define STRUCT_SIZE(name, size) _Static_assert(sizeof(name) == (size), "Incorrect struct size.")

// Retrieve the first (ie. high) 64 bits of an IPv6 address (in network order)
#define v6_hi_be64(v) (*(uint64_t*)&((v).s6_addr32[0]))

// Retrieve the last (ie. low) 64 bits of an IPv6 address (in network order)
#define v6_lo_be64(v) (*(uint64_t*)&((v).s6_addr32[2]))

// This returns a non-zero u64 iff a != b
#define v6_not_equal(a, b) ((v6_hi_be64(a) ^ v6_hi_be64(b)) \
                          | (v6_lo_be64(a) ^ v6_lo_be64(b)))

// Returns 'a == b' as boolean
#define v6_equal(a, b) (!v6_not_equal((a), (b)))

// TODO: these are already defined in packages/modules/Connectivity/bpf_progs/bpf_net_helpers.h.
// smove to common location in future.
static uint64_t (*bpf_get_socket_cookie)(struct __sk_buff* skb) =
        (void*)BPF_FUNC_get_socket_cookie;
static int (*bpf_skb_store_bytes)(struct __sk_buff* skb, __u32 offset, const void* from, __u32 len,
                                  __u64 flags) = (void*)BPF_FUNC_skb_store_bytes;
static int (*bpf_l3_csum_replace)(struct __sk_buff* skb, __u32 offset, __u64 from, __u64 to,
                                  __u64 flags) = (void*)BPF_FUNC_l3_csum_replace;
static long (*bpf_skb_ecn_set_ce)(struct __sk_buff* skb) =
        (void*)BPF_FUNC_skb_ecn_set_ce;

typedef struct {
    struct in6_addr src_ip;
    struct in6_addr dst_ip;
    uint32_t ifindex;
    __be16 src_port;
    __be16 dst_port_start;
    __be16 dst_port_end;
    uint8_t proto;
    int8_t dscp_val;  // -1 none, or 0..63 DSCP value
    uint8_t present_fields;
    uint8_t pad[3];
} DscpPolicy;
STRUCT_SIZE(DscpPolicy, 2 * 16 + 4 + 3 * 2 + 3 * 1 + 3);  // 48

typedef struct {
    struct in6_addr src_ip;
    struct in6_addr dst_ip;
    __u32 ifindex;
    __be16 src_port;
    __be16 dst_port;
    __u8 proto;
    __s8 dscp_val;  // -1 none, or 0..63 DSCP value
    __u8 pad[2];
} RuleEntry;
STRUCT_SIZE(RuleEntry, 2 * 16 + 1 * 4 + 2 * 2 + 2 * 1 + 2);  // 44