categories: add mmap .ndb backend for custom category lists

Introduce a compiled .ndb backend (mmap) for external custom category
matching, with LEGACY / NDB_ONLY / HYBRID modes, while keeping the
existing -G / Aho-Corasick list path unchanged.
Adds ndpi_load_category_ndb_file() / ndpi_unload_category_ndb(),
ndpiReader --category-ndb and --category-ndb-reload-interval, a
polling-based hot-reload helper, offline builder ndpi_gen_categories_bin,
shared hostname normalization (generator + runtime), and on-disk layout
in ndpi_categories_bin.h (domains plus IPv4/IPv6 prefix entries).
The generator writes the database atomically (temporary file + fsync +
rename) so ndpiReader can reload a new valid file without restart.

Author: fabiodepin

.gitignore

@@ -55,6 +55,7 @@
 /example/ndpiReader
 /example/ndpiReader.exe
 /example/ndpiSimpleIntegration
+/example/ndpi_gen_categories_bin
 /utils/Makefile
 /utils/hosts2domains
 /utils/print_rank

Makefile.am

@@ -19,7 +19,7 @@ EXTRA_DIST = README.md README.fuzzer.md CHANGELOG.md CONTRIBUTING.md \
 	autogen.sh wireshark windows utils packages dga \
 	influxdb/Makefile.in influxdb/metric_anomaly.c influxdb/README.txt \
 	rrdtool/Makefile.in rrdtool/README.txt rrdtool/rrd_anomaly.c rrdtool/rrd_similarity.c \
-	doc/requirements.txt doc/conf.py doc/flow_risks.rst doc/protocols.rst doc/guide/nDPI_QuickStartGuide.pages \
+	doc/requirements.txt doc/categories-ndb.md doc/conf.py doc/flow_risks.rst doc/protocols.rst doc/guide/nDPI_QuickStartGuide.pages \
 		doc/guide/nDPI_QuickStartGuide.pdf doc/img/logo.png doc/index.rst \
 		doc/Makefile doc/what_is_ndpi.rst \
 		doc/FAQ.rst \

configure.ac

@@ -279,7 +279,11 @@ echo "Setting API version to ${NDPI_API_VERSION}"
 AC_DEFINE_UNQUOTED(NDPI_GIT_RELEASE, "${GIT_RELEASE}", [GIT Release])
 AC_DEFINE_UNQUOTED(NDPI_GIT_DATE, "${GIT_DATE}", [Last GIT change])
 
-NDPI_CFLAGS="-W -Wall -Wextra -Wno-address-of-packed-member ${NDPI_CFLAGS}"
+NDPI_CFLAGS="-W -Wall -Wextra ${NDPI_CFLAGS}"
+dnl> gcc < 5 does not support -Wno-address-of-packed-member (unknown -Wno-* is fatal with -Werror)
+AX_CHECK_COMPILE_FLAG([-Wno-address-of-packed-member], [
+  NDPI_CFLAGS="${NDPI_CFLAGS} -Wno-address-of-packed-member"
+], [], [-Werror])
 
 dnl> MacOS brew.sh
 HOMEBREW_DIR=/opt/homebrew
@@ -408,6 +412,8 @@ if test -d ${srcdir}/../nDPI-custom; then :
    AC_MSG_RESULT([Compiling with custom nDPI protocols])
 fi
 
+dnl> example/ndpi_gen_categories_bin is linked without $(LIBS); Winsock must still be linked.
+NDPI_GEN_EXTRA_LIBS=
 case "$host" in
    *-*-mingw32*|*-*-msys)
       PCAP_INC=""
@@ -427,6 +433,7 @@ case "$host" in
       esac
       NDPI_CFLAGS="-D__USE_MINGW_ANSI_STDIO -D__STDC_FORMAT_MACROS ${NDPI_CFLAGS}"
       LIBS="${LIBS} -lws2_32"
+      NDPI_GEN_EXTRA_LIBS="-lws2_32"
       BUILD_MINGW=1
       EXE_SUFFIX=".exe"
       AS_IF([test "${enable_npcap+set}" != set && test "${with_only_libndpi+set}" != set],,
@@ -619,6 +626,7 @@ AC_SUBST(NDPI_API_VERSION)
 AC_SUBST(EXTRA_TARGETS)
 AC_SUBST(BUILD_MINGW)
 AC_SUBST(BUILD_MINGW_X64)
+AC_SUBST(NDPI_GEN_EXTRA_LIBS)
 AC_SUBST(BUILD_FUZZTARGETS)
 AC_SUBST(JSONC_CFLAGS)
 AC_SUBST(JSONC_LIBS)