Add for public examination the beginnings of the per-host cache support

which will for the basis of RTF_PRCLONING's more efficient, better-
designed replacement.

1 files changed, 158 insertions, 0 deletions

diff --git a/sys/netinet/in_hostcache.c b/sys/netinet/in_hostcache.c
new file mode 100644
index 0000000..8b46959
--- /dev/null
+++ b/sys/netinet/in_hostcache.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright 1997 Massachusetts Institute of Technology
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose and without fee is hereby
+ * granted, provided that both the above copyright notice and this
+ * permission notice appear in all copies, that both the above
+ * copyright notice and this permission notice appear in all
+ * supporting documentation, and that the name of M.I.T. not be used
+ * in advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.  M.I.T. makes
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied
+ * warranty.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
+ * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
+ * SHALL M.I.T. 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.
+ *
+ *	$Id$
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/socket.h>
+#include <sys/socketvar.h>
+
+#include <net/hostcache.h>
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/route.h>
+
+#include <netinet/in.h>
+#include <netinet/in_hostcache.h>
+#include <netinet/tcp.h>
+#include <netinet/tcp_timer.h>
+#include <netinet/tcp_var.h>
+
+/*
+ * Manage the IP per-host cache (really a thin veneer over the generic
+ * per-host cache code).
+ */
+
+/* Look up an entry -- can be called from interrupt context. */
+struct in_hcentry *
+inhc_lookup(struct sockaddr_in *sin)
+{
+	struct hcentry *hc;
+
+	hc = hc_get((struct sockaddr *)sin);
+	return ((struct in_hcentry *)hc);
+}
+
+/* Look up and possibly create an entry -- must be called from user mode. */
+struct in_hcentry *
+inhc_alloc(struct sockaddr_in *sin)
+{
+	struct in_hcentry *inhc;
+	struct rtentry *rt;
+	int error;
+	/* xxx mutual exclusion for smp */
+
+	inhc = inhc_lookup(sin);
+	if (inhc != 0)
+		return inhc;
+
+	rt = rtalloc1(inhc->inhc_hc.hc_host, 1, 0);
+	if (rt == 0)
+		return 0;
+
+	MALLOC(inhc, struct in_hcentry *, sizeof *inhc, M_HOSTCACHE, M_WAITOK);
+	bzero(inhc, sizeof *inhc);
+	inhc->inhc_hc.hc_host = dup_sockaddr((struct sockaddr *)sin, 1);
+	if (in_broadcast(sin->sin_addr, rt->rt_ifp))
+		inhc->inhc_flags |= INHC_BROADCAST;
+	else if (((struct sockaddr_in *)rt->rt_ifa->ifa_addr)->sin_addr.s_addr
+		== sin->sin_addr.s_addr)
+		inhc->inhc_flags |= INHC_LOCAL;
+	else if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
+		inhc->inhc_flags |= INHC_MULTICAST;
+	inhc->inhc_pmtu = rt->rt_rmx.rmx_mtu;
+	inhc->inhc_recvpipe = rt->rt_rmx.rmx_recvpipe;
+	inhc->inhc_sendpipe = rt->rt_rmx.rmx_sendpipe;
+	inhc->inhc_ssthresh = rt->rt_rmx.rmx_ssthresh;
+	if (rt->rt_rmx.rmx_locks & RTV_RTT)
+		inhc->inhc_rttmin = rt->rt_rmx.rmx_rtt
+			/ (RTM_RTTUNIT / TCP_RTT_SCALE);
+	inhc->inhc_hc.hc_rt = rt;
+	error = hc_insert(&inhc->inhc_hc);
+	if (error != 0) {
+		RTFREE(rt);
+		FREE(inhc, M_HOSTCACHE);
+		return 0;
+	}
+	/*
+	 * We don't return the structure directly because hc_get() needs
+	 * to be allowed to do its own processing.
+	 */
+	return (inhc_lookup(sin));
+}
+
+/*
+ * This is Van Jacobson's hash function for IPv4 addresses.
+ * It is designed to work with a power-of-two-sized hash table.
+ */
+static u_long
+inhc_hash(struct sockaddr *sa, u_long nbuckets)
+{
+	u_long ip;
+
+	ip = ((struct sockaddr_in *)sa)->sin_addr.s_addr;
+	return ((ip ^ (ip >> 23) ^ (ip >> 17)) & ~(nbuckets - 1));
+}
+
+/*
+ * We don't need to do any special work... if there are no references,
+ * as the caller has already ensured, then it's OK to kill.
+ */
+static int
+inhc_delete(struct hcentry *hc)
+{
+	return 0;
+}
+
+/*
+ * Return the next increment for the number of buckets in the hash table.
+ * Zero means ``do not bump''.
+ */
+static u_long
+inhc_bump(u_long oldsize)
+{
+	if (oldsize < 512)
+		return (oldsize << 1);
+	return 0;
+}
+
+static struct hccallback inhc_cb = {
+	inhc_hash, inhc_delete, inhc_bump
+};
+
+int
+inhc_init(void)
+{
+	int error;
+
+	return (hc_init(AF_INET, &inhc_cb, 128, 0));
+}
+