Merge helper fib* functions used for basic lookups.

Vast majority of rtalloc(9) users require only basic info from
route table (e.g. "does the rtentry interface match with the interface
  I have?". "what is the MTU?", "Give me the IPv4 source address to use",
  etc..).
Instead of hand-rolling lookups, checking if rtentry is up, valid,
  dealing with IPv6 mtu, finding "address" ifp (almost never done right),
  provide easy-to-use API hiding all the complexity and returning the
  needed info into small on-stack structure.

This change also helps hiding route subsystem internals (locking, direct
  rtentry accesses).
Additionaly, using this API improves lookup performance since rtentry is not
  locked.
(This is safe, since all the rtentry changes happens under both radix WLOCK
  and rtentry WLOCK).

Sponsored by:	Yandex LLC

1 files changed, 264 insertions, 0 deletions

diff --git a/sys/netinet6/in6_fib.c b/sys/netinet6/in6_fib.c
new file mode 100644
index 000000000000..70bd1772d781
--- /dev/null
+++ b/sys/netinet6/in6_fib.c
@@ -0,0 +1,264 @@
+/*-
+ * Copyright (c) 2015
+ * 	Alexander V. Chernikov <melifaro@FreeBSD.org>
+ *
+ * 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.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_inet.h"
+#include "opt_inet6.h"
+#include "opt_route.h"
+#include "opt_mpath.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/lock.h>
+#include <sys/rwlock.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+#include <sys/kernel.h>
+
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+#include <net/vnet.h>
+
+#ifdef RADIX_MPATH
+#include <net/radix_mpath.h>
+#endif
+
+#include <netinet/in.h>
+#include <netinet/in_var.h>
+#include <netinet/ip_mroute.h>
+#include <netinet/ip6.h>
+#include <netinet6/in6_fib.h>
+#include <netinet6/in6_var.h>
+#include <netinet6/nd6.h>
+#include <netinet6/scope6_var.h>
+
+#include <net/if_types.h>
+
+#ifdef INET6
+static void fib6_rte_to_nh_extended(struct rtentry *rte,
+    const struct in6_addr *dst, uint32_t flags, struct nhop6_extended *pnh6);
+static void fib6_rte_to_nh_basic(struct rtentry *rte, const struct in6_addr *dst,
+    uint32_t flags, struct nhop6_basic *pnh6);
+static struct ifnet *fib6_get_ifaifp(struct rtentry *rte);
+#define RNTORT(p)	((struct rtentry *)(p))
+
+/*
+ * Gets real interface for the @rte.
+ * Returns rt_ifp for !IFF_LOOPBACK routers.
+ * Extracts "real" address interface from interface address
+ * loopback routes.
+ */
+static struct ifnet *
+fib6_get_ifaifp(struct rtentry *rte)
+{
+	struct ifnet *ifp;
+	struct sockaddr_dl *sdl;
+
+	ifp = rte->rt_ifp;
+	if ((ifp->if_flags & IFF_LOOPBACK) &&
+	    rte->rt_gateway->sa_family == AF_LINK) {
+		sdl = (struct sockaddr_dl *)rte->rt_gateway;
+		return (ifnet_byindex(sdl->sdl_index));
+	}
+
+	return (ifp);
+}
+
+static void
+fib6_rte_to_nh_basic(struct rtentry *rte, const struct in6_addr *dst,
+    uint32_t flags, struct nhop6_basic *pnh6)
+{
+	struct sockaddr_in6 *gw;
+
+	/* Do explicit nexthop zero unless we're copying it */
+	memset(pnh6, 0, sizeof(*pnh6));
+
+	if ((flags & NHR_IFAIF) != 0)
+		pnh6->nh_ifp = fib6_get_ifaifp(rte);
+	else
+		pnh6->nh_ifp = rte->rt_ifp;
+
+	pnh6->nh_mtu = min(rte->rt_mtu, IN6_LINKMTU(rte->rt_ifp));
+	if (rte->rt_flags & RTF_GATEWAY) {
+		gw = (struct sockaddr_in6 *)rte->rt_gateway;
+		pnh6->nh_addr = gw->sin6_addr;
+		in6_clearscope(&pnh6->nh_addr);
+	} else
+		pnh6->nh_addr = *dst;
+	/* Set flags */
+	pnh6->nh_flags = fib_rte_to_nh_flags(rte->rt_flags);
+	gw = (struct sockaddr_in6 *)rt_key(rte);
+	if (IN6_IS_ADDR_UNSPECIFIED(&gw->sin6_addr))
+		pnh6->nh_flags |= NHF_DEFAULT;
+}
+
+static void
+fib6_rte_to_nh_extended(struct rtentry *rte, const struct in6_addr *dst,
+    uint32_t flags, struct nhop6_extended *pnh6)
+{
+	struct sockaddr_in6 *gw;
+
+	/* Do explicit nexthop zero unless we're copying it */
+	memset(pnh6, 0, sizeof(*pnh6));
+
+	if ((flags & NHR_IFAIF) != 0)
+		pnh6->nh_ifp = fib6_get_ifaifp(rte);
+	else
+		pnh6->nh_ifp = rte->rt_ifp;
+
+	pnh6->nh_mtu = min(rte->rt_mtu, IN6_LINKMTU(rte->rt_ifp));
+	if (rte->rt_flags & RTF_GATEWAY) {
+		gw = (struct sockaddr_in6 *)rte->rt_gateway;
+		pnh6->nh_addr = gw->sin6_addr;
+		in6_clearscope(&pnh6->nh_addr);
+	} else
+		pnh6->nh_addr = *dst;
+	/* Set flags */
+	pnh6->nh_flags = fib_rte_to_nh_flags(rte->rt_flags);
+	gw = (struct sockaddr_in6 *)rt_key(rte);
+	if (IN6_IS_ADDR_UNSPECIFIED(&gw->sin6_addr))
+		pnh6->nh_flags |= NHF_DEFAULT;
+}
+
+/*
+ * Performs IPv6 route table lookup on @dst. Returns 0 on success.
+ * Stores basic nexthop info into provided @pnh6 structure.
+ * Note that
+ * - nh_ifp represents logical transmit interface (rt_ifp) by default
+ * - nh_ifp represents "address" interface if NHR_IFAIF flag is passed
+ * - mtu from logical transmit interface will be returned.
+ * - nh_ifp cannot be safely dereferenced
+ * - nh_ifp represents rt_ifp (e.g. if looking up address on
+ *   interface "ix0" pointer to "ix0" interface will be returned instead
+ *   of "lo0")
+ * - howewer mtu from "transmit" interface will be returned.
+ */
+int
+fib6_lookup_nh_basic(uint32_t fibnum, const struct in6_addr *dst, uint32_t scopeid,
+    uint32_t flags, uint32_t flowid, struct nhop6_basic *pnh6)
+{
+	struct radix_node_head *rh;
+	struct radix_node *rn;
+	struct sockaddr_in6 sin6;
+	struct rtentry *rte;
+
+	KASSERT((fibnum < rt_numfibs), ("fib6_lookup_nh_basic: bad fibnum"));
+	rh = rt_tables_get_rnh(fibnum, AF_INET6);
+	if (rh == NULL)
+		return (ENOENT);
+
+	/* Prepare lookup key */
+	memset(&sin6, 0, sizeof(sin6));
+	sin6.sin6_addr = *dst;
+	/* Assume scopeid is valid and embed it directly */
+	if (IN6_IS_SCOPE_LINKLOCAL(dst))
+		sin6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);
+
+	RADIX_NODE_HEAD_RLOCK(rh);
+	rn = rh->rnh_matchaddr((void *)&sin6, rh);
+	if (rn != NULL && ((rn->rn_flags & RNF_ROOT) == 0)) {
+		rte = RNTORT(rn);
+		/* Ensure route & ifp is UP */
+		if (RT_LINK_IS_UP(rte->rt_ifp)) {
+			fib6_rte_to_nh_basic(rte, dst, flags, pnh6);
+			RADIX_NODE_HEAD_RUNLOCK(rh);
+			return (0);
+		}
+	}
+	RADIX_NODE_HEAD_RUNLOCK(rh);
+
+	return (ENOENT);
+}
+
+/*
+ * Performs IPv6 route table lookup on @dst. Returns 0 on success.
+ * Stores extended nexthop info into provided @pnh6 structure.
+ * Note that
+ * - nh_ifp cannot be safely dereferenced unless NHR_REF is specified.
+ * - in that case you need to call fib6_free_nh_ext()
+ * - nh_ifp represents logical transmit interface (rt_ifp) by default
+ * - nh_ifp represents "address" interface if NHR_IFAIF flag is passed
+ * - mtu from logical transmit interface will be returned.
+ */
+int
+fib6_lookup_nh_ext(uint32_t fibnum, const struct in6_addr *dst,uint32_t scopeid,
+    uint32_t flags, uint32_t flowid, struct nhop6_extended *pnh6)
+{
+	struct radix_node_head *rh;
+	struct radix_node *rn;
+	struct sockaddr_in6 sin6;
+	struct rtentry *rte;
+
+	KASSERT((fibnum < rt_numfibs), ("fib6_lookup_nh_ext: bad fibnum"));
+	rh = rt_tables_get_rnh(fibnum, AF_INET6);
+	if (rh == NULL)
+		return (ENOENT);
+
+	/* Prepare lookup key */
+	memset(&sin6, 0, sizeof(sin6));
+	sin6.sin6_len = sizeof(struct sockaddr_in6);
+	sin6.sin6_addr = *dst;
+	/* Assume scopeid is valid and embed it directly */
+	if (IN6_IS_SCOPE_LINKLOCAL(dst))
+		sin6.sin6_addr.s6_addr16[1] = htons(scopeid & 0xffff);
+
+	RADIX_NODE_HEAD_RLOCK(rh);
+	rn = rh->rnh_matchaddr((void *)&sin6, rh);
+	if (rn != NULL && ((rn->rn_flags & RNF_ROOT) == 0)) {
+		rte = RNTORT(rn);
+		/* Ensure route & ifp is UP */
+		if (RT_LINK_IS_UP(rte->rt_ifp)) {
+			fib6_rte_to_nh_extended(rte, dst, flags, pnh6);
+			if ((flags & NHR_REF) != 0) {
+				/* TODO: Do lwref on egress ifp's */
+			}
+			RADIX_NODE_HEAD_RUNLOCK(rh);
+
+			return (0);
+		}
+	}
+	RADIX_NODE_HEAD_RUNLOCK(rh);
+
+	return (ENOENT);
+}
+
+void
+fib6_free_nh_ext(uint32_t fibnum, struct nhop6_extended *pnh6)
+{
+
+}
+
+#endif
+