FreeBSD/Linux Kernel Cross Reference
sys/net/route/nhop.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2020 Alexander V. Chernikov
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    /*
     * This header file contains public definitions for the nexthop routing subsystem.
     */
    
    #ifndef _NET_ROUTE_NHOP_H_
    #define _NET_ROUTE_NHOP_H_
    
    #include <netinet/in.h>                 /* sockaddr_in && sockaddr_in6 */
    
    #include <sys/counter.h>
    
    enum nhop_type {
            NH_TYPE_IPV4_ETHER_RSLV = 1,    /* IPv4 ethernet without GW */
            NH_TYPE_IPV4_ETHER_NHOP = 2,    /* IPv4 with pre-calculated ethernet encap */
            NH_TYPE_IPV6_ETHER_RSLV = 3,    /* IPv6 ethernet, without GW */
            NH_TYPE_IPV6_ETHER_NHOP = 4     /* IPv6 with pre-calculated ethernet encap*/
    };
    
    #ifdef _KERNEL
    
    /*
     * Define shorter version of AF_LINK sockaddr.
     *
     * Currently the only use case of AF_LINK gateway is storing
     * interface index of the interface of the source IPv6 address.
     * This is used by the IPv6 code for the connections over loopback
     * interface.
     *
     * The structure below copies 'struct sockaddr_dl', reducing the
     * size of sdl_data buffer, as it is not used. This change
     * allows to store the AF_LINK gateways in the nhop gateway itself,
     * simplifying control plane handling.
     */
    struct sockaddr_dl_short {
            u_char  sdl_len;        /* Total length of sockaddr */
            u_char  sdl_family;     /* AF_LINK */
            u_short sdl_index;      /* if != 0, system given index for interface */
            u_char  sdl_type;       /* interface type */
            u_char  sdl_nlen;       /* interface name length, no trailing 0 reqd. */
            u_char  sdl_alen;       /* link level address length */
            u_char  sdl_slen;       /* link layer selector length */
            char    sdl_data[8];    /* unused */
    };
    
    #define NHOP_RELATED_FLAGS      \
            (RTF_GATEWAY | RTF_HOST | RTF_REJECT | RTF_BLACKHOLE | \
             RTF_FIXEDMTU | RTF_LOCAL | RTF_BROADCAST | RTF_MULTICAST)
    
    struct nh_control;
    struct nhop_priv;
    
    /*
     * Struct 'nhop_object' field description:
     *
     * nh_flags: NHF_ flags used in the dataplane code. NHF_GATEWAY or NHF_BLACKHOLE
     *   can be examples of such flags.
     * nh_mtu: ready-to-use nexthop mtu. Already accounts for the link-level header,
     *   interface MTU and protocol-specific limitations.
     * nh_prepend_len: link-level prepend length. Currently unused.
     * nh_ifp: logical transmit interface. The one from which if_transmit() will be
     *   called. Guaranteed to be non-NULL.
     * nh_aifp: ifnet of the source address. Same as nh_ifp except IPv6 loopback
     *   routes. See the example below.
     * nh_ifa: interface address to use. Guaranteed to be non-NULL. 
     * nh_pksent: counter(9) reflecting the number of packets transmitted.
     *
     * gw_: storage suitable to hold AF_INET, AF_INET6 or AF_LINK gateway. More
     *   details ara available in the examples below.
     *
     * Examples:
    *
    * Direct routes (routes w/o gateway):
    *  NHF_GATEWAY is NOT set.
    *  nh_ifp denotes the logical transmit interface ().
    *  nh_aifp is the same as nh_ifp
    *  gw_sa contains AF_LINK sa with nh_aifp ifindex (compat)
    * Loopback routes:
    *  NHF_GATEWAY is NOT set.
    *  nh_ifp points to the loopback interface (lo0).
    *  nh_aifp points to the interface where the destination address belongs to.
    *    This is useful in IPv6 link-local-over-loopback communications.
    *  gw_sa contains AF_LINK sa with nh_aifp ifindex (compat)
    * GW routes:
    *  NHF_GATEWAY is set.
    *  nh_ifp denotes the logical transmit interface.
    *  nh_aifp is the same as nh_ifp
    *  gw_sa contains L3 address (either AF_INET or AF_INET6).
    *
    *
    * Note: struct nhop_object fields are ordered in a way that
    *  supports memcmp-based comparisons.
    *
    */
   #define NHOP_END_CMP    (__offsetof(struct nhop_object, nh_pksent))
   
   struct nhop_object {
           uint16_t                nh_flags;       /* nhop flags */
           uint16_t                nh_mtu;         /* nexthop mtu */
           union {
                   struct sockaddr_in              gw4_sa; /* GW accessor as IPv4 */
                   struct sockaddr_in6             gw6_sa; /* GW accessor as IPv6 */
                   struct sockaddr                 gw_sa;
                   struct sockaddr_dl_short        gwl_sa; /* AF_LINK gw (compat) */
                   char                            gw_buf[28];
           };
           struct ifnet            *nh_ifp;        /* Logical egress interface. Always != NULL */
           struct ifaddr           *nh_ifa;        /* interface address to use. Always != NULL */
           struct ifnet            *nh_aifp;       /* ifnet of the source address. Always != NULL */
           counter_u64_t           nh_pksent;      /* packets sent using this nhop */
           /* 32 bytes + 4xPTR == 64(amd64) / 48(i386)  */
           uint8_t                 nh_prepend_len; /* length of prepend data */
           uint8_t                 spare[3];
           uint32_t                spare1;         /* alignment */
           char                    nh_prepend[48]; /* L2 prepend */
           struct nhop_priv        *nh_priv;       /* control plane data */
           /* -- 128 bytes -- */
   };
   
   /*
    * Nhop validness.
    *
    * Currently we verify whether link is up or not on every packet, which can be
    *   quite costy.
    * TODO: subscribe for the interface notifications and update the nexthops
    *  with NHF_INVALID flag.
    */
   
   #define NH_IS_VALID(_nh)        RT_LINK_IS_UP((_nh)->nh_ifp)
   #define NH_IS_NHGRP(_nh)        ((_nh)->nh_flags & NHF_MULTIPATH)
   
   #define NH_FREE(_nh) do {                                       \
           nhop_free(_nh); \
           /* guard against invalid refs */                        \
           _nh = NULL;                                             \
   } while (0)
   
   struct weightened_nhop {
           struct nhop_object      *nh;
           uint32_t                weight;
           uint32_t                storage;
   };
   
   void nhop_free(struct nhop_object *nh);
   
   struct sysctl_req;
   struct sockaddr_dl;
   struct rib_head;
   
   /* flags that can be set using nhop_set_rtflags() */
   #define RT_SET_RTFLAGS_MASK     (RTF_PROTO1 | RTF_PROTO2 | RTF_PROTO3 | RTF_STATIC)
   #define RT_CHANGE_RTFLAGS_MASK  RT_SET_RTFLAGS_MASK
   
   struct nhop_object *nhop_alloc(uint32_t fibnum, int family);
   void nhop_copy(struct nhop_object *nh, const struct nhop_object *nh_orig);
   struct nhop_object *nhop_get_nhop(struct nhop_object *nh, int *perror);
   int nhop_get_unlinked(struct nhop_object *nh);
   
   void nhop_set_direct_gw(struct nhop_object *nh, struct ifnet *ifp);
   bool nhop_set_gw(struct nhop_object *nh, const struct sockaddr *sa, bool is_gw);
   
   
   void nhop_set_mtu(struct nhop_object *nh, uint32_t mtu, bool from_user);
   void nhop_set_rtflags(struct nhop_object *nh, int rt_flags);
   void nhop_set_pxtype_flag(struct nhop_object *nh, int nh_flag);
   void nhop_set_broadcast(struct nhop_object *nh, bool is_broadcast);
   void nhop_set_blackhole(struct nhop_object *nh, int blackhole_rt_flag);
   void nhop_set_pinned(struct nhop_object *nh, bool is_pinned);
   void nhop_set_redirect(struct nhop_object *nh, bool is_redirect);
   void nhop_set_type(struct nhop_object *nh, enum nhop_type nh_type);
   void nhop_set_src(struct nhop_object *nh, struct ifaddr *ifa);
   void nhop_set_transmit_ifp(struct nhop_object *nh, struct ifnet *ifp);
   
   #define NH_ORIGIN_UNSPEC        0 /* not set */
   #define NH_ORIGIN_REDIRECT      1 /* kernel-originated redirect */
   #define NH_ORIGIN_KERNEL        2 /* kernel (interface) routes */
   #define NH_ORIGIN_BOOT          3 /* kernel-originated routes at boot */
   #define NH_ORIGIN_STATIC        4 /* route(8) routes */
   void nhop_set_origin(struct nhop_object *nh, uint8_t origin);
   uint8_t nhop_get_origin(const struct nhop_object *nh);
   
   uint32_t nhop_get_idx(const struct nhop_object *nh);
   uint32_t nhop_get_uidx(const struct nhop_object *nh);
   void nhop_set_uidx(struct nhop_object *nh, uint32_t uidx);
   enum nhop_type nhop_get_type(const struct nhop_object *nh);
   int nhop_get_rtflags(const struct nhop_object *nh);
   struct vnet *nhop_get_vnet(const struct nhop_object *nh);
   struct nhop_object *nhop_select_func(struct nhop_object *nh, uint32_t flowid);
   int nhop_get_upper_family(const struct nhop_object *nh);
   bool nhop_set_upper_family(struct nhop_object *nh, int family);
   int nhop_get_neigh_family(const struct nhop_object *nh);
   uint32_t nhop_get_fibnum(const struct nhop_object *nh);
   void nhop_set_fibnum(struct nhop_object *nh, uint32_t fibnum);
   uint32_t nhop_get_expire(const struct nhop_object *nh);
   void nhop_set_expire(struct nhop_object *nh, uint32_t expire);
   struct rib_head *nhop_get_rh(const struct nhop_object *nh);
   
   struct nhgrp_object;
   struct nhgrp_object *nhgrp_alloc(uint32_t fibnum, int family,
       struct weightened_nhop *wn, int num_nhops, int *perror);
   struct nhgrp_object *nhgrp_get_nhgrp(struct nhgrp_object *nhg, int *perror);
   void nhgrp_set_uidx(struct nhgrp_object *nhg, uint32_t uidx);
   uint32_t nhgrp_get_uidx(const struct nhgrp_object *nhg);
   uint8_t nhgrp_get_origin(const struct nhgrp_object *nhg);
   void nhgrp_set_origin(struct nhgrp_object *nhg, uint8_t origin);
   #endif /* _KERNEL */
   
   /* Kernel <> userland structures */
   
   /* Structure usage and layout are described in dump_nhop_entry() */
   struct nhop_external {
           uint32_t        nh_len;         /* length of the datastructure */
           uint32_t        nh_idx;         /* Nexthop index */
           uint32_t        nh_fib;         /* Fib nexhop is attached to */
           uint32_t        ifindex;        /* transmit interface ifindex */
           uint32_t        aifindex;       /* address ifindex */
           uint8_t         prepend_len;    /* length of the prepend */
           uint8_t         nh_family;      /* address family */
           uint16_t        nh_type;        /* nexthop type */
           uint16_t        nh_mtu;         /* nexthop mtu */
   
           uint16_t        nh_flags;       /* nhop flags */
           struct in_addr  nh_addr;        /* GW/DST IPv4 address */
           struct in_addr  nh_src;         /* default source IPv4 address */
           uint64_t        nh_pksent;
           /* control plane */
           /* lookup key: address, family, type */
           char            nh_prepend[64]; /* L2 prepend */
           uint64_t        nh_refcount;    /* number of references */
   };
   
   struct nhop_addrs {
           uint32_t        na_len;         /* length of the datastructure */
           uint16_t        gw_sa_off;      /* offset of gateway SA */
           uint16_t        src_sa_off;     /* offset of src address SA */
   };
   
   #define NHG_C_TYPE_CNHOPS       0x1     /* Control plane nhops list */
   #define NHG_C_TYPE_DNHOPS       0x2     /* Dataplane nhops list */
   struct nhgrp_container {
           uint32_t        nhgc_len;       /* container length */
           uint16_t        nhgc_count;     /* number of items */
           uint8_t         nhgc_type;      /* container type */
           uint8_t         nhgc_subtype;   /* container subtype */
   };
   
   struct nhgrp_nhop_external {
           uint32_t        nh_idx;
           uint32_t        nh_weight;
   };
   
   /*
    * Layout:
    * - nhgrp_external
    * - nhgrp_container (control plane nhops list)
    *   - nhgrp_nhop_external
    *   - nhgrp_nhop_external
    *   ..
    * - nhgrp_container (dataplane nhops list)
    *   - nhgrp_nhop_external
    *   - nhgrp_nhop_external
    */
   struct nhgrp_external {
           uint32_t        nhg_idx;        /* Nexthop group index */
           uint32_t        nhg_refcount;   /* number of references */
   };
   
   #endif

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