[v9_10] DDoS mitigation features

3938.	[func]		Added quotas to be used in recursive resolvers
			that are under high query load for names in zones
			whose authoritative servers are nonresponsive or
			are experiencing a denial of service attack.

			- "fetches-per-server" limits the number of
			  simultaneous queries that can be sent to any
			  single authoritative server.  The configured
			  value is a starting point; it is automatically
			  adjusted downward if the server is partially or
			  completely non-responsive. The algorithm used to
			  adjust the quota can be configured via the
			  "fetch-quota-params" option.
			- "fetches-per-zone" limits the number of
			  simultaneous queries that can be sent for names
			  within a single domain.  (Note: Unlike
			  "fetches-per-server", this value is not
			  self-tuning.)
			- New stats counters have been added to count
			  queries spilled due to these quotas.

			These options are not available by default;
			use "configure --enable-fetchlimit" (or
			--enable-developer) to include them in the build.

			See the ARM for details of these options. [RT #37125]

bin/tests/system/fetchlimit/Makefile.in

@@ -0,0 +1,53 @@
+# Copyright (C) 2010-2012  Internet Systems Consortium, Inc. ("ISC")
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+# PERFORMANCE OF THIS SOFTWARE.
+
+srcdir =	@srcdir@
+VPATH =		@srcdir@
+top_srcdir =	@top_srcdir@
+
+@BIND9_VERSION@
+
+@BIND9_MAKE_INCLUDES@
+
+CINCLUDES =	${ISC_INCLUDES}
+
+CDEFINES =
+CWARNINGS =
+
+DNSLIBS =	
+ISCLIBS =	.
+
+DNSDEPLIBS =
+ISCDEPLIBS =
+
+DEPLIBS =
+
+LIBS =		@LIBS@
+
+TARGETS =	fetchlimit@EXEEXT@
+
+FILTEROBJS =	fetchlimit.@O@
+
+SRCS =		fetchlimit.c
+
+@BIND9_MAKE_RULES@
+
+all: fetchlimit@EXEEXT@
+
+fetchlimit@EXEEXT@: ${FILTEROBJS}
+	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ ${FILTEROBJS} ${LIBS}
+
+clean distclean::
+	rm -f ${TARGETS}
+