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* [newlib-cygwin] Introduce nexthop objects and new routing KPI.
@ 2022-07-11 11:51 Sebastian Huber
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From: Sebastian Huber @ 2022-07-11 11:51 UTC (permalink / raw)
  To: newlib-cvs;h=86484e84d7be074b540c8e11650bed025692d71f

commit 86484e84d7be074b540c8e11650bed025692d71f
Author: Alexander V. Chernikov <>
Date:   Sun Apr 12 14:30:00 2020 +0000

    Introduce nexthop objects and new routing KPI.
    This is the foundational change for the routing subsytem rearchitecture.
     More details and goals are available in .
    This patch introduces concept of nexthop objects and new nexthop-based
     routing KPI.
    Nexthops are objects, containing all necessary information for performing
     the packet output decision. Output interface, mtu, flags, gw address goes
     there. For most of the cases, these objects will serve the same role as
     the struct rtentry is currently serving.
    Typically there will be low tens of such objects for the router even with
     multiple BGP full-views, as these objects will be shared between routing
     entries. This allows to store more information in the nexthop.
    New KPI:
    struct nhop_object *fib4_lookup(uint32_t fibnum, struct in_addr dst,
      uint32_t scopeid, uint32_t flags, uint32_t flowid);
    struct nhop_object *fib6_lookup(uint32_t fibnum, const struct in6_addr *dst6,
      uint32_t scopeid, uint32_t flags, uint32_t flowid);
    These 2 function are intended to replace all all flavours of
     <in_|in6_>rtalloc[1]<_ign><_fib>, mpath functions  and the previous
     fib[46]-generation functions.
    Upon successful lookup, they return nexthop object which is guaranteed to
     exist within current NET_EPOCH. If longer lifetime is desired, one can
     specify NHR_REF as a flag and get a referenced version of the nexthop.
     Reference semantic closely resembles rtentry one, allowing sed-style conversion.
    Additionally, another 2 functions are introduced to support uRPF functionality
     inside variety of our firewalls. Their primary goal is to hide the multipath
     implementation details inside the routing subsystem, greatly simplifying
     firewalls implementation:
    int fib4_lookup_urpf(uint32_t fibnum, struct in_addr dst, uint32_t scopeid,
      uint32_t flags, const struct ifnet *src_if);
    int fib6_lookup_urpf(uint32_t fibnum, const struct in6_addr *dst6, uint32_t scopeid,
      uint32_t flags, const struct ifnet *src_if);
    All functions have a separate scopeid argument, paving way to eliminating IPv6 scope
     embedding and allowing to support IPv4 link-locals in the future.
    Structure changes:
     * rtentry gets new 'rt_nhop' pointer, slightly growing the overall size.
     * rib_head gets new 'rnh_preadd' callback pointer, slightly growing overall sz.
    Old KPI:
    During the transition state old and new KPI will coexists. As there are another 4-5
     decent-sized conversion patches, it will probably take a couple of weeks.
    To support both KPIs, fields not required by the new KPI (most of rtentry) has to be
     kept, resulting in the temporary size increase.
    Once conversion is finished, rtentry will notably shrink.
    More details:
    * architectural overview:
    * list of the next changes:
    Reviewed by:    ae,glebius(initial version)
    Differential Revision:

 newlib/libc/sys/rtems/include/sys/socket.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/newlib/libc/sys/rtems/include/sys/socket.h b/newlib/libc/sys/rtems/include/sys/socket.h
index 30c606389..3431947cf 100644
--- a/newlib/libc/sys/rtems/include/sys/socket.h
+++ b/newlib/libc/sys/rtems/include/sys/socket.h
@@ -408,6 +408,7 @@ struct sockproto {
 #define	NET_RT_IFMALIST	4		/* return multicast address list */
 #define	NET_RT_IFLISTL	5		/* Survey interface list, using 'l'en
 					 * versions of msghdr structs. */
+#define NET_RT_NHOP	6		/* dump routing nexthops */
 #endif /* __BSD_VISIBLE */

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