/*
 * Copyright (c) 2012, 2014-2019, 2021, Pelion and affiliates.
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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.
 */
/*
 * ipv6_routing_table.h
 *
 * Implements Neighbour Cache
 */

#ifndef IPV6_ROUTING_TABLE_H_
#define IPV6_ROUTING_TABLE_H_

#include "ns_list.h"
#include "Core/include/ns_address_internal.h"

/* Address Resolution and Neighbour Unreachablity Detection constants from
 * RFC 4861, updated by RFC 7048.
 */
#define MAX_MULTICAST_SOLICIT               3
#define MAX_UNICAST_SOLICIT                 5
#define MARK_UNREACHABLE                    3
#define MAX_RETRANS_TIMER                   60000   /* ms */
#define DELAY_FIRST_PROBE_TIME              5000    /* ms */
#define BACKOFF_MULTIPLE                    3

/* RFC 6775 parameters */
#define TENTATIVE_NCE_LIFETIME              20      /* s */

#define IPV6_ROUTE_DEFAULT_METRIC           128

/* XXX in the process of renaming this - it's really specifically the
 * IP Neighbour Cache  but was initially called a routing table */

typedef enum ip_neighbour_cache_state {
    IP_NEIGHBOUR_NEW,               /* Not yet used; no LL addr, no NS sent */
    IP_NEIGHBOUR_INCOMPLETE,
    IP_NEIGHBOUR_REACHABLE,
    IP_NEIGHBOUR_STALE,
    IP_NEIGHBOUR_DELAY,
    IP_NEIGHBOUR_PROBE,
    IP_NEIGHBOUR_UNREACHABLE
} ip_neighbour_cache_state_t;

/* RFC 6775 types */
typedef enum ip_neighbour_cache_type {
    IP_NEIGHBOUR_GARBAGE_COLLECTIBLE,
    IP_NEIGHBOUR_REGISTERED,
    IP_NEIGHBOUR_TENTATIVE
} ip_neighbour_cache_type_t;

typedef enum ipv6_route_src {
    ROUTE_ANY,          /* Unspecified - use in lookups */
    ROUTE_NONE,         /* Only occurs in incomplete destination cache entries */
    ROUTE_STATIC,
    ROUTE_LOOPBACK,
    ROUTE_USER,
    ROUTE_ARO,
    ROUTE_RADV,
    ROUTE_RPL_DIO,      /* Explicitly advertised in DIO RIO */
    ROUTE_RPL_DAO,      /* Explicitly advertised in DAO, Storing mode */
    ROUTE_RPL_DAO_SR,   /* Explicitly advertised in DAO, Root Source Routes in Non-Storing mode */
    ROUTE_RPL_SRH,      /* Not in routing table - used in buffers to represent on-link inferred from SRH */
    ROUTE_RPL_ROOT,     /* Implicit route to DODAG root */
    ROUTE_RPL_INSTANCE, /* Implicit instance-specific default upward route (not for general search) */
    ROUTE_RPL_FWD_ERROR, /* Not in routing table - used in buffers to represent Forwarding-Error bounce */
    ROUTE_MULTICAST,    /* Not in routing table - used to represent multicast interface selection */
    ROUTE_MPL,
    ROUTE_RIP,
    ROUTE_THREAD,
    ROUTE_THREAD_BORDER_ROUTER,
    ROUTE_THREAD_PROXIED_HOST,
    ROUTE_THREAD_PROXIED_DUA_HOST,
    ROUTE_THREAD_BBR,
    ROUTE_REDIRECT,     /* Only occurs in destination cache */
    ROUTE_MAX,
} ipv6_route_src_t;

struct buffer;

typedef struct ipv6_neighbour {
    uint8_t                         ip_address[16];             /*!< neighbour IP address */
    bool                            is_router: 1;
    bool                            from_redirect: 1;
    uint8_t                         retrans_count;
    ip_neighbour_cache_state_t      state;
    ip_neighbour_cache_type_t       type;
    addrtype_t                      ll_type;
    uint32_t                        timer;                      /* 100ms ticks */
    uint32_t                        lifetime;                   /* seconds */
    ns_list_link_t                  link;                       /*!< List link */
    NS_LIST_HEAD_INCOMPLETE(struct buffer) queue;
    uint8_t                         ll_address[];
} ipv6_neighbour_t;

/* Neighbour Cache entries also store EUI-64 after ll_address if "recv_addr_reg"
 * is set for the cache. This is ADDR_EUI64_ZERO if unknown.
 */
#define ipv6_neighbour_eui64(ncache, entry) ((entry)->ll_address + (ncache)->max_ll_len)

typedef struct ipv6_route_info_cache {
    uint16_t                                metric; // interface metric
    uint8_t                                 sources[ROUTE_MAX];
} ipv6_route_interface_info_t;

typedef struct ipv6_neighbour_cache {
    bool                                    send_addr_reg : 1;
    bool                                    recv_addr_reg : 1;
    bool                                    send_nud_probes : 1;
    bool                                    probe_avoided_routers : 1;
    bool                                    recv_ns_aro : 1;
    bool                                    recv_na_aro : 1;
    bool                                    use_eui64_as_slla_in_aro : 1;
    bool                                    omit_na_aro_success : 1;
    bool                                    omit_na : 1; // except for ARO successes which have a separate flag
    int8_t                                  interface_id;
    uint8_t                                 max_ll_len;
    uint8_t                                 gc_timer;
    uint16_t                                link_mtu;
    uint32_t                                retrans_timer;
    uint32_t                                reachable_time;
    // Interface specific information for route
    ipv6_route_interface_info_t             route_if_info;
    //uint8_t                                   num_entries;
    NS_LIST_HEAD(ipv6_neighbour_t, link)    list;
} ipv6_neighbour_cache_t;

/* Macros for formatting ipv6 addresses into strings for route printing. */
/* Initialize a string buffer for the ipv6 address */
#define ROUTE_PRINT_ADDR_STR_BUFFER_INIT(str) char str[41] = "<null>"
/* Format and store ipv6 'addr' into 'str', and evaluate 'str' */
#define ROUTE_PRINT_ADDR_STR_FORMAT(str, addr) (ip6tos(addr, str), str)

/* Callback type for route print */
typedef void (route_print_fn_t)(const char *fmt, ...);

extern void ipv6_neighbour_cache_init(ipv6_neighbour_cache_t *cache, int8_t interface_id);
extern void ipv6_neighbour_cache_flush(ipv6_neighbour_cache_t *cache);
extern ipv6_neighbour_t *ipv6_neighbour_update(ipv6_neighbour_cache_t *cache, const uint8_t *address, bool solicited);
extern void ipv6_neighbour_set_state(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *entry, ip_neighbour_cache_state_t state);
extern ipv6_neighbour_t *ipv6_neighbour_used(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *entry);
extern ipv6_neighbour_t *ipv6_neighbour_lookup(ipv6_neighbour_cache_t *cache, const uint8_t *address);
extern ipv6_neighbour_t *ipv6_neighbour_lookup_by_interface_id(int8_t interface_id, const uint8_t *address);
extern ipv6_neighbour_t *ipv6_neighbour_lookup_or_create(ipv6_neighbour_cache_t *cache, const uint8_t *address);
extern ipv6_neighbour_t *ipv6_neighbour_lookup_or_create_by_interface_id(int8_t interface_id, const uint8_t *address);
extern void ipv6_neighbour_entry_remove(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *entry);
extern bool ipv6_neighbour_is_probably_reachable(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *n);
extern bool ipv6_neighbour_addr_is_probably_reachable(ipv6_neighbour_cache_t *cache, const uint8_t *address);
extern bool ipv6_neighbour_ll_addr_match(const ipv6_neighbour_t *entry, addrtype_t ll_type, const uint8_t *ll_address);
extern void ipv6_neighbour_invalidate_ll_addr(ipv6_neighbour_cache_t *cache, addrtype_t ll_type, const uint8_t *ll_address);
extern void ipv6_neighbour_delete_registered_by_eui64(ipv6_neighbour_cache_t *cache, const uint8_t *eui64);
extern bool ipv6_neighbour_has_registered_by_eui64(ipv6_neighbour_cache_t *cache, const uint8_t *eui64);
extern ipv6_neighbour_t *ipv6_neighbour_get_registered_by_eui64(ipv6_neighbour_cache_t *cache, const uint8_t *eui64);
extern void ipv6_neighbour_entry_update_unsolicited(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *entry, addrtype_t type, const uint8_t *ll_address/*, bool tentative*/);
extern ipv6_neighbour_t *ipv6_neighbour_update_unsolicited(ipv6_neighbour_cache_t *cache, const uint8_t *ip_address, addrtype_t ll_type, const uint8_t *ll_address);
extern void ipv6_neighbour_reachability_confirmation(const uint8_t ip_address[__static 16], int8_t interface_id);
extern void ipv6_neighbour_reachability_problem(const uint8_t ip_address[__static 16], int8_t interface_id);
extern void ipv6_neighbour_update_from_na(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *entry, uint8_t flags, addrtype_t ll_type, const uint8_t *ll_address);
extern void ipv6_neighbour_cache_fast_timer(ipv6_neighbour_cache_t *cache, uint16_t ticks);
extern void ipv6_neighbour_cache_slow_timer(ipv6_neighbour_cache_t *cache, uint8_t seconds);
extern void ipv6_neighbour_cache_print(const ipv6_neighbour_cache_t *cache, route_print_fn_t *print_fn);
extern void ipv6_router_gone(ipv6_neighbour_cache_t *cache, ipv6_neighbour_t *entry);
extern int8_t ipv6_neighbour_set_current_max_cache(uint16_t max_cache);
extern int8_t ipv6_destination_cache_configure(uint16_t max_entries, uint16_t short_term_threshold, uint16_t long_term_threshold, uint16_t lifetime);
extern int8_t ipv6_neighbour_cache_configure(uint16_t max_entries, uint16_t short_term_threshold, uint16_t long_term_threshold, uint16_t lifetime);

/* Backwards compatibility with test app */
#define ROUTE_RPL_UP ROUTE_RPL_DIO
#define ROUTE_RPL_DOWN ROUTE_RPL_DAO

typedef struct ipv6_route_info {
    ipv6_route_src_t                source;
    uint8_t                         source_id;
    int8_t                          interface_id;
    uint16_t                        pmtu;
    void                            *info;              // pointer to route provider's info
    uint8_t                         next_hop_addr[16];
} ipv6_route_info_t;

typedef struct ipv6_destination {
    /* Destination/path information */
    uint8_t                         destination[16];
#ifdef HAVE_IPV6_ND
    uint8_t                         redirect_addr[16];
    bool                            redirected;         // we have a redirect in force
#endif
    int8_t                          interface_id;       // fixed if link-local destination, else variable and gets set from redirect interface and/or last_neighbour interface
    uint16_t                        refcount;
    uint16_t                        lifetime;           // Life in GC calls, so 20s units
#ifndef NO_IPV6_PMTUD
    uint16_t                        pmtu;               // note this may be less than 1280 - upper layers may choose to send smaller based on this
    uint16_t                        pmtu_lifetime;      // seconds
#endif
#ifndef NO_IP_FRAGMENT_TX
    uint32_t                        fragment_id;
#endif
    ipv6_neighbour_t                *last_neighbour;    // last neighbour used (only for reachability confirmation)
    ns_list_link_t                  link;
} ipv6_destination_t;

#ifndef NO_IPV6_PMTUD
#define ipv6_destination_pmtu(d) ((d)->pmtu)
#else
#define ipv6_destination_pmtu(d) IPV6_MIN_LINK_MTU
#endif

void ipv6_destination_cache_print(route_print_fn_t *print_fn);
ipv6_destination_t *ipv6_destination_lookup_or_create(const uint8_t *address, int8_t interface_id);
ipv6_destination_t *ipv6_destination_lookup_or_create_with_route(const uint8_t *address, int8_t interface_id, ipv6_route_info_t *route_out);
void ipv6_destination_cache_timer(uint8_t ticks);
#ifdef HAVE_IPV6_ND
void ipv6_destination_redirect(const uint8_t *dest_addr, const uint8_t *sender_addr, const uint8_t *redirect_addr, int8_t interface_id, addrtype_t ll_type, const uint8_t *ll_address);
#endif
void ipv6_destination_cache_forced_gc(bool full_gc);
void ipv6_destination_cache_clean(int8_t interface_id);

/* Combined Routing Table (RFC 4191) and Prefix List (RFC 4861) */
/* On-link prefixes have the on_link flag set and next_hop is unset */
typedef struct ipv6_route {
    uint8_t             prefix_len;
    bool                on_link: 1;
    bool                search_skip: 1;
    bool                probe: 1;
    bool                info_autofree: 1;
    uint8_t             metric;             // 0x40 = RFC 4191 pref high, 0x80 = default, 0xC0 = RFC 4191 pref low
    ipv6_route_info_t   info;
    uint32_t            lifetime;           // (seconds); 0xFFFFFFFF means permanent
    uint16_t            probe_timer;
    ns_list_link_t      link;
    uint8_t             prefix[];           // variable length
} ipv6_route_t;

/* Callback type for route predicate */
typedef bool ipv6_route_predicate_fn_t(const ipv6_route_info_t *route, bool valid);

/* Callbacks for route providers that dynamically compute next hop */
typedef bool ipv6_route_next_hop_fn_t(const uint8_t *dest, ipv6_route_info_t *route_info);

uint8_t ipv6_route_pref_to_metric(int_fast8_t pref);
ipv6_route_t *ipv6_route_add(const uint8_t *prefix, uint8_t prefix_len, int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source, uint32_t lifetime, int_fast8_t pref);
ipv6_route_t *ipv6_route_add_with_info(const uint8_t *prefix, uint8_t prefix_len, int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source, void *info, uint8_t source_id, uint32_t lifetime, int_fast8_t pref);
ipv6_route_t *ipv6_route_add_metric(const uint8_t *prefix, uint8_t prefix_len, int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source, void *info, uint8_t source_id, uint32_t lifetime, uint8_t metric);
ipv6_route_t *ipv6_route_lookup_with_info(const uint8_t *prefix, uint8_t prefix_len, int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source, void *info, int_fast16_t source_id);
int_fast8_t ipv6_route_delete(const uint8_t *prefix, uint8_t prefix_len, int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source);
int_fast8_t ipv6_route_delete_with_info(const uint8_t *prefix, uint8_t prefix_len, int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source, void *info, int_fast16_t source_id);
ipv6_route_t *ipv6_route_choose_next_hop(const uint8_t *dest, int8_t interface_id, ipv6_route_predicate_fn_t *predicate);

void ipv6_route_table_change_next_hop_for_info(int8_t interface_id, const uint8_t *next_hop, ipv6_route_src_t source, void *info);
void ipv6_route_table_remove_interface(int8_t interface_id);
void ipv6_route_table_modify_router_metric(int8_t interface_id, const uint8_t *addr, ipv6_route_src_t source, uint8_t keep, uint8_t toggle);
void ipv6_route_table_remove_info(int8_t interface_id, ipv6_route_src_t source, void *info);
void ipv6_route_table_set_predicate_fn(ipv6_route_src_t src, ipv6_route_predicate_fn_t *fn);
void ipv6_route_table_set_next_hop_fn(ipv6_route_src_t src, ipv6_route_next_hop_fn_t *fn);
void ipv6_route_table_ttl_update(uint16_t seconds);
void ipv6_route_table_print(route_print_fn_t *print_fn);
void ipv6_route_table_set_max_entries(int8_t interface_id, ipv6_route_src_t source, uint8_t max_entries);
bool ipv6_route_table_source_was_invalidated(ipv6_route_src_t src);
void ipv6_route_table_source_invalidated_reset(void);

#endif /* IPV6_ROUTING_TABLE_H_ */