Support for zLib flow memory compression. Experimental.

Please use this feature only for testing purposes.
It will change or be removed in the future.

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

2 files changed, 309 insertions, 59 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 46df61753..997c45162 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,6 +6,7 @@ find_package(PkgConfig REQUIRED)
 option(ENABLE_SANITIZER "Enable ASAN/LSAN/UBSAN." OFF)
 option(ENABLE_SANITIZER_THREAD "Enable TSAN (does not work together with ASAN)." OFF)
 option(ENABLE_MEMORY_PROFILING "Enable dynamic memory tracking." OFF)
+option(ENABLE_ZLIB "Enable zlib support for nDPId (experimental)." OFF)
 option(BUILD_EXAMPLES "Build C examples." ON)
 option(BUILD_NDPI "Clone and build nDPI from github." OFF)
 option(NDPI_NO_PKGCONFIG "Do not use pkgconfig to search for libnDPI." OFF)
@@ -57,16 +58,19 @@ if(GIT_VERSION STREQUAL "" OR NOT IS_DIRECTORY "${CMAKE_SOURCE_DIR}/.git")
 endif()
 
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra")
-set(NDPID_C_FLAGS -DJSMN_STATIC=1 -DJSMN_STRICT=1)
+set(NDPID_DEFS -DJSMN_STATIC=1 -DJSMN_STRICT=1)
 if(ENABLE_MEMORY_PROFILING)
-    set(MEMORY_PROFILING_CFLAGS "-DENABLE_MEMORY_PROFILING=1"
-                                "-Duthash_malloc=nDPIsrvd_uthash_malloc"
-                                "-Duthash_free=nDPIsrvd_uthash_free")
-else()
-    set(MEMORY_PROFILING_CFLAGS "")
+    add_definitions("-DENABLE_MEMORY_PROFILING=1"
+                    "-Duthash_malloc=nDPIsrvd_uthash_malloc"
+                    "-Duthash_free=nDPIsrvd_uthash_free")
+endif()
+
+if(ENABLE_ZLIB)
+    set(ZLIB_DEFS "-DENABLE_ZLIB=1")
+    pkg_check_modules(ZLIB REQUIRED zlib)
 endif()
 
-if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+if(CMAKE_BUILD_TYPE STREQUAL "Debug" OR CMAKE_BUILD_TYPE STREQUAL "")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -g3 -fno-omit-frame-pointer -fno-inline")
 endif()
 
@@ -88,8 +92,12 @@ if(STATIC_LIBNDPI_INSTALLDIR STREQUAL "" AND BUILD_NDPI)
         libnDPI
         SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/libnDPI
         DOWNLOAD_COMMAND ""
-        CONFIGURE_COMMAND env CROSS_COMPILE_TRIPLET=${CROSS_COMPILE_TRIPLET}
-            MAKE_PROGRAM=make DEST_INSTALL=${CMAKE_BINARY_DIR}/libnDPI
+        CONFIGURE_COMMAND env
+            CFLAGS=${CMAKE_C_FLAGS}
+            LDFLAGS=${CMAKE_MODULE_LINKER_FLAGS}
+            CROSS_COMPILE_TRIPLET=${CROSS_COMPILE_TRIPLET}
+            MAKE_PROGRAM=make
+            DEST_INSTALL=${CMAKE_BINARY_DIR}/libnDPI
             ${CMAKE_CURRENT_SOURCE_DIR}/scripts/get-and-build-libndpi.sh
         BUILD_BYPRODUCTS ${CMAKE_BINARY_DIR}/libnDPI/lib/libndpi.a
         BUILD_COMMAND ""
@@ -142,14 +150,15 @@ else()
 endif()
 
 find_package(PCAP "1.8.1" REQUIRED)
-target_compile_options(nDPId PRIVATE ${NDPID_C_FLAGS} -DGIT_VERSION=\"${GIT_VERSION}\" ${MEMORY_PROFILING_CFLAGS} "-pthread")
+target_compile_options(nDPId PRIVATE "-pthread")
+target_compile_definitions(nDPId PRIVATE -DGIT_VERSION=\"${GIT_VERSION}\" ${NDPID_DEFS} ${ZLIB_DEFS})
 target_include_directories(nDPId PRIVATE "${STATIC_LIBNDPI_INC}" "${NDPI_INCLUDEDIR}" "${NDPI_INCLUDEDIR}/ndpi")
 target_link_libraries(nDPId "${STATIC_LIBNDPI_LIB}" "${pkgcfg_lib_NDPI_ndpi}"
-                            "${pkgcfg_lib_PCRE_pcre}" "${pkgcfg_lib_MAXMINDDB_maxminddb}"
+                            "${pkgcfg_lib_PCRE_pcre}" "${pkgcfg_lib_MAXMINDDB_maxminddb}" "${pkgcfg_lib_ZLIB_z}"
                             "${GCRYPT_LIBRARY}" "${GCRYPT_ERROR_LIBRARY}" "${PCAP_LIBRARY}"
                             "-pthread")
 
-target_compile_options(nDPIsrvd PRIVATE ${NDPID_C_FLAGS} -DGIT_VERSION=\"${GIT_VERSION}\" ${MEMORY_PROFILING_CFLAGS})
+target_compile_definitions(nDPIsrvd PRIVATE -DGIT_VERSION=\"${GIT_VERSION}\" ${NDPID_DEFS})
 target_include_directories(nDPIsrvd PRIVATE
                            "${CMAKE_SOURCE_DIR}"
                            "${CMAKE_SOURCE_DIR}/dependencies"
@@ -161,17 +170,18 @@ target_include_directories(nDPId-test PRIVATE
                            "${CMAKE_SOURCE_DIR}/dependencies"
                            "${CMAKE_SOURCE_DIR}/dependencies/jsmn"
                            "${CMAKE_SOURCE_DIR}/dependencies/uthash/src")
-target_compile_options(nDPId-test PRIVATE ${NDPID_C_FLAGS} ${MEMORY_PROFILING_CFLAGS} "-Wno-unused-function" "-pthread")
+target_compile_options(nDPId-test PRIVATE "-Wno-unused-function" "-pthread")
+target_compile_definitions(nDPId-test PRIVATE ${NDPID_DEFS} ${ZLIB_DEFS})
 target_include_directories(nDPId-test PRIVATE "${STATIC_LIBNDPI_INC}" "${NDPI_INCLUDEDIR}" "${NDPI_INCLUDEDIR}/ndpi")
 target_compile_definitions(nDPId-test PRIVATE "-D_GNU_SOURCE=1" "-DNO_MAIN=1" "-Dsyslog=mock_syslog_stderr")
 target_link_libraries(nDPId-test "${STATIC_LIBNDPI_LIB}" "${pkgcfg_lib_NDPI_ndpi}"
-                                 "${pkgcfg_lib_PCRE_pcre}" "${pkgcfg_lib_MAXMINDDB_maxminddb}"
+                                 "${pkgcfg_lib_PCRE_pcre}" "${pkgcfg_lib_MAXMINDDB_maxminddb}" "${pkgcfg_lib_ZLIB_z}"
                                  "${GCRYPT_LIBRARY}" "${GCRYPT_ERROR_LIBRARY}" "${PCAP_LIBRARY}"
                                  "-pthread")
 
 if(BUILD_EXAMPLES)
     add_executable(nDPIsrvd-collectd examples/c-collectd/c-collectd.c)
-    target_compile_options(nDPIsrvd-collectd PRIVATE ${NDPID_C_FLAGS} ${MEMORY_PROFILING_CFLAGS})
+    target_compile_definitions(nDPIsrvd-collectd PRIVATE ${NDPID_DEFS})
     target_include_directories(nDPIsrvd-collectd PRIVATE
                                "${CMAKE_SOURCE_DIR}"
                                "${CMAKE_SOURCE_DIR}/dependencies"
@@ -179,7 +189,7 @@ if(BUILD_EXAMPLES)
                                "${CMAKE_SOURCE_DIR}/dependencies/uthash/src")
 
     add_executable(nDPIsrvd-captured examples/c-captured/c-captured.c utils.c)
-    target_compile_options(nDPIsrvd-captured PRIVATE ${NDPID_C_FLAGS} ${MEMORY_PROFILING_CFLAGS})
+    target_compile_definitions(nDPIsrvd-captured PRIVATE ${NDPID_DEFS})
     target_include_directories(nDPIsrvd-captured PRIVATE
                                "${CMAKE_SOURCE_DIR}"
                                "${CMAKE_SOURCE_DIR}/dependencies"
@@ -205,13 +215,11 @@ message(STATUS "nDPId GIT_VERSION........: ${GIT_VERSION}")
 message(STATUS "CROSS_COMPILE_TRIPLET....: ${CROSS_COMPILE_TRIPLET}")
 message(STATUS "CMAKE_BUILD_TYPE.........: ${CMAKE_BUILD_TYPE}")
 message(STATUS "CMAKE_C_FLAGS............: ${CMAKE_C_FLAGS}")
-message(STATUS "NDPID_C_FLAGS............: ${NDPID_C_FLAGS}")
-if(ENABLE_MEMORY_PROFILING)
-message(STATUS "MEMORY_PROFILING_CFLAGS..: ${MEMORY_PROFILING_CFLAGS}")
-endif()
+message(STATUS "NDPID_DEFS...............: ${NDPID_DEFS}")
 message(STATUS "ENABLE_SANITIZER.........: ${ENABLE_SANITIZER}")
 message(STATUS "ENABLE_SANITIZER_THREAD..: ${ENABLE_SANITIZER_THREAD}")
 message(STATUS "ENABLE_MEMORY_PROFILING..: ${ENABLE_MEMORY_PROFILING}")
+message(STATUS "ENABLE_ZLIB..............: ${ENABLE_ZLIB}")
 if(NOT BUILD_NDPI AND NOT STATIC_LIBNDPI_INSTALLDIR STREQUAL "")
 message(STATUS "STATIC_LIBNDPI_INSTALLDIR: ${STATIC_LIBNDPI_INSTALLDIR}")
 endif()
diff --git a/nDPId.c b/nDPId.c
index 427f3ab27..dc99acb14 100644
--- a/nDPId.c
+++ b/nDPId.c
@@ -18,6 +18,9 @@
 #include <sys/un.h>
 #include <syslog.h>
 #include <unistd.h>
+#ifdef ENABLE_ZLIB
+#include <zlib.h>
+#endif
 
 #include "config.h"
 #include "utils.h"
@@ -108,21 +111,31 @@ struct nDPId_flow_skipped
     struct nDPId_flow_basic flow_basic;
 };
 
+struct nDPI_data
+{
+    struct ndpi_flow_struct flow;
+    struct ndpi_id_struct src;
+    struct ndpi_id_struct dst;
+};
+
 struct nDPId_flow_info
 {
     struct nDPId_flow_extended flow_extended;
 
     uint8_t detection_completed : 1;
     uint8_t reserved_00 : 7;
-    uint8_t reserved_01[3];
+    uint8_t reserved_01[1];
+#ifdef ENABLE_ZLIB
+    uint16_t ndpi_compressed_size;
+#else
+    uint16_t reserved_02;
+#endif
     uint32_t last_ndpi_flow_struct_hash;
 
     struct ndpi_proto detected_l7_protocol;
     struct ndpi_proto guessed_l7_protocol;
 
-    struct ndpi_flow_struct * ndpi_flow;
-    struct ndpi_id_struct * ndpi_src;
-    struct ndpi_id_struct * ndpi_dst;
+    struct nDPI_data * ndpi;
 };
 
 struct nDPId_flow_finished
@@ -281,6 +294,11 @@ static uint64_t ndpi_memory_alloc_count = 0;
 static uint64_t ndpi_memory_alloc_bytes = 0;
 static uint64_t ndpi_memory_free_count = 0;
 static uint64_t ndpi_memory_free_bytes = 0;
+#ifdef ENABLE_ZLIB
+static uint64_t zlib_compressions = 0;
+static uint64_t zlib_decompressions = 0;
+static uint64_t zlib_compression_diff = 0;
+#endif
 #endif
 
 static struct
@@ -302,6 +320,9 @@ static struct
     char * custom_ja3_file;
     char * custom_sha1_file;
     char json_sockpath[UNIX_PATH_MAX];
+#ifdef ENABLE_ZLIB
+    uint8_t enable_zlib_compression;
+#endif
     /* subopts */
     char * instance_alias;
     unsigned long long int max_flows_per_thread;
@@ -367,6 +388,163 @@ static void jsonize_flow_event(struct nDPId_reader_thread * const reader_thread,
                                struct nDPId_flow_info * const flow,
                                enum flow_event event);
 
+#ifdef ENABLE_ZLIB
+static int zlib_deflate(const void * const src, int srcLen, void * dst, int dstLen)
+{
+    z_stream strm = {0};
+    strm.total_in = strm.avail_in = srcLen;
+    strm.total_out = strm.avail_out = dstLen;
+    strm.next_in = (Bytef *)src;
+    strm.next_out = (Bytef *)dst;
+
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    strm.opaque = Z_NULL;
+
+    int err = -1;
+    int ret = -1;
+
+    err = deflateInit(&strm, Z_BEST_COMPRESSION);
+    if (err == Z_OK)
+    {
+        err = deflate(&strm, Z_FINISH);
+        if (err == Z_STREAM_END)
+        {
+            ret = strm.total_out;
+#ifdef ENABLE_MEMORY_PROFILING
+            __sync_fetch_and_add(&zlib_compressions, 1);
+            __sync_fetch_and_add(&zlib_compression_diff, srcLen - ret);
+#endif
+        }
+        else
+        {
+            deflateEnd(&strm);
+            return err;
+        }
+    }
+    else
+    {
+        deflateEnd(&strm);
+        return err;
+    }
+
+    deflateEnd(&strm);
+    return ret;
+}
+
+static int zlib_inflate(const void * src, int srcLen, void * dst, int dstLen)
+{
+    z_stream strm = {0};
+    strm.total_in = strm.avail_in = srcLen;
+    strm.total_out = strm.avail_out = dstLen;
+    strm.next_in = (Bytef *)src;
+    strm.next_out = (Bytef *)dst;
+
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    strm.opaque = Z_NULL;
+
+    int err = -1;
+    int ret = -1;
+
+    err = inflateInit2(&strm, (15 + 32)); // 15 window bits, and the +32 tells zlib to to detect if using gzip or zlib
+    if (err == Z_OK)
+    {
+        err = inflate(&strm, Z_FINISH);
+        if (err == Z_STREAM_END)
+        {
+            ret = strm.total_out;
+#ifdef ENABLE_MEMORY_PROFILING
+            __sync_fetch_and_add(&zlib_decompressions, 1);
+#endif
+        }
+        else
+        {
+            inflateEnd(&strm);
+            return err;
+        }
+    }
+    else
+    {
+        inflateEnd(&strm);
+        return err;
+    }
+
+    inflateEnd(&strm);
+    return ret;
+}
+
+static int ndpi_data_deflate(struct nDPId_flow_info * const flow_info)
+{
+    uint8_t tmpOut[sizeof(*flow_info->ndpi)];
+    int ret;
+
+    if (flow_info->ndpi_compressed_size != 0)
+    {
+        return -7;
+    }
+
+    ret = zlib_deflate(flow_info->ndpi, sizeof(*flow_info->ndpi), tmpOut, sizeof(tmpOut));
+    if (ret <= 0)
+    {
+        return ret;
+    }
+
+    struct nDPI_data * const new_ndpi_data = ndpi_malloc(ret);
+    if (new_ndpi_data == NULL)
+    {
+        return -8;
+    }
+    ndpi_free(flow_info->ndpi);
+    flow_info->ndpi = new_ndpi_data;
+
+    memcpy(flow_info->ndpi, tmpOut, ret);
+    flow_info->ndpi_compressed_size = ret;
+
+    return ret;
+}
+
+static int ndpi_data_inflate(struct nDPId_flow_info * const flow_info)
+{
+    uint8_t tmpOut[sizeof(*flow_info->ndpi)];
+    int ret;
+
+    if (flow_info->ndpi_compressed_size == 0)
+    {
+        return -7;
+    }
+
+    ret = zlib_inflate(flow_info->ndpi, flow_info->ndpi_compressed_size, tmpOut, sizeof(tmpOut));
+    if (ret <= 0)
+    {
+        return ret;
+    }
+
+    struct nDPI_data * const new_ndpi_data = ndpi_malloc(ret);
+    if (new_ndpi_data == NULL)
+    {
+        return -8;
+    }
+    ndpi_free(flow_info->ndpi);
+    flow_info->ndpi = new_ndpi_data;
+
+    memcpy(flow_info->ndpi, tmpOut, ret);
+    flow_info->ndpi_compressed_size = 0;
+
+    /*
+     * Do not use ndpi_id_struct's from ndpi_flow
+     * as they may not be valid anymore.
+     * nDPI only updates those pointers while processing packets!
+     * This is especially important when using compression
+     * to prevent use of dangling pointers.
+     */
+    flow_info->ndpi->flow.src = &flow_info->ndpi->src;
+    flow_info->ndpi->flow.dst = &flow_info->ndpi->dst;
+
+    return ret;
+}
+#endif
+
 static void ip_netmask_to_subnet(union nDPId_ip const * const ip,
                                  union nDPId_ip const * const netmask,
                                  union nDPId_ip * const subnet,
@@ -774,21 +952,16 @@ static struct nDPId_workflow * init_workflow(char const * const file_or_device)
 
 static void free_ndpi_structs(struct nDPId_flow_info * const flow_info)
 {
-    ndpi_free(flow_info->ndpi_dst);
-    flow_info->ndpi_dst = NULL;
-    ndpi_free(flow_info->ndpi_src);
-    flow_info->ndpi_src = NULL;
-    ndpi_free_flow(flow_info->ndpi_flow);
-    flow_info->ndpi_flow = NULL;
+    ndpi_free_flow_data(&flow_info->ndpi->flow);
+    ndpi_free(flow_info->ndpi);
+    flow_info->ndpi = NULL;
 }
 
 static int alloc_ndpi_structs(struct nDPId_flow_info * const flow_info)
 {
-    flow_info->ndpi_dst = (struct ndpi_id_struct *)ndpi_calloc(1, SIZEOF_ID_STRUCT);
-    flow_info->ndpi_src = (struct ndpi_id_struct *)ndpi_calloc(1, SIZEOF_ID_STRUCT);
-    flow_info->ndpi_flow = (struct ndpi_flow_struct *)ndpi_flow_malloc(SIZEOF_FLOW_STRUCT);
+    flow_info->ndpi = (struct nDPI_data *)ndpi_flow_malloc(sizeof(*flow_info->ndpi));
 
-    if (flow_info->ndpi_dst == NULL || flow_info->ndpi_src == NULL || flow_info->ndpi_flow == NULL)
+    if (flow_info->ndpi == NULL)
     {
         goto error;
     }
@@ -1068,7 +1241,7 @@ static int ndpi_workflow_node_cmp(void const * const A, void const * const B)
         return 1;
     }
 
-    /* Flows have the same hash */
+    /* flows have the same hash */
     if (flow_basic_a->l4_protocol < flow_basic_b->l4_protocol)
     {
         return -1;
@@ -1121,6 +1294,18 @@ static void process_idle_flow(struct nDPId_reader_thread * const reader_thread,
             {
                 struct nDPId_flow_info * const flow_info = (struct nDPId_flow_info *)flow_basic;
 
+#ifdef ENABLE_ZLIB
+                if (nDPId_options.enable_zlib_compression != 0 && flow_info->ndpi_compressed_size > 0)
+                {
+                    int ret = ndpi_data_inflate(flow_info);
+                    if (ret <= 0)
+                    {
+                        syslog(LOG_DAEMON | LOG_ERR, "zLib decompression failed with error code: %d", ret);
+                        return;
+                    }
+                }
+#endif
+
                 if (flow_info->detection_completed == 0)
                 {
                     uint8_t protocol_was_guessed = 0;
@@ -1128,7 +1313,7 @@ static void process_idle_flow(struct nDPId_reader_thread * const reader_thread,
                     if (ndpi_is_protocol_detected(workflow->ndpi_struct, flow_info->guessed_l7_protocol) == 0)
                     {
                         flow_info->guessed_l7_protocol = ndpi_detection_giveup(workflow->ndpi_struct,
-                                                                               flow_info->ndpi_flow,
+                                                                               &flow_info->ndpi->flow,
                                                                                1,
                                                                                &protocol_was_guessed);
                     }
@@ -1188,6 +1373,17 @@ static void check_for_idle_flows(struct nDPId_reader_thread * const reader_threa
                    (long long unsigned int)free_bytes,
                    (long long unsigned int)(alloc_count - free_count),
                    (long long unsigned int)(alloc_bytes - free_bytes));
+#ifdef ENABLE_ZLIB
+            uint64_t zlib_compression_count = __sync_fetch_and_add(&zlib_compressions, 0);
+            uint64_t zlib_decompression_count = __sync_fetch_and_add(&zlib_decompressions, 0);
+            uint64_t zlib_bytes_diff = __sync_fetch_and_add(&zlib_compression_diff, 0);
+
+            syslog(LOG_DAEMON,
+                   "MemoryProfiler (zLib): %llu compressions, %llu decompressions, %llu bytes difference",
+                   (long long unsigned int)zlib_compression_count,
+                   (long long unsigned int)zlib_decompression_count,
+                   (long long unsigned int)zlib_bytes_diff);
+#endif
         }
 #endif
 
@@ -1686,8 +1882,10 @@ static void jsonize_flow_event(struct nDPId_reader_thread * const reader_thread,
 
         case FLOW_EVENT_NOT_DETECTED:
         case FLOW_EVENT_GUESSED:
-            if (ndpi_dpi2json(
-                    workflow->ndpi_struct, flow->ndpi_flow, flow->guessed_l7_protocol, &workflow->ndpi_serializer) != 0)
+            if (ndpi_dpi2json(workflow->ndpi_struct,
+                              &flow->ndpi->flow,
+                              flow->guessed_l7_protocol,
+                              &workflow->ndpi_serializer) != 0)
             {
                 syslog(LOG_DAEMON | LOG_ERR,
                        "[%8llu, %4u] ndpi_dpi2json failed for not-detected/guessed flow",
@@ -1699,7 +1897,7 @@ static void jsonize_flow_event(struct nDPId_reader_thread * const reader_thread,
         case FLOW_EVENT_DETECTED:
         case FLOW_EVENT_DETECTION_UPDATE:
             if (ndpi_dpi2json(workflow->ndpi_struct,
-                              flow->ndpi_flow,
+                              &flow->ndpi->flow,
                               flow->detected_l7_protocol,
                               &workflow->ndpi_serializer) != 0)
             {
@@ -2516,8 +2714,8 @@ static void ndpi_process_packet(uint8_t * const args,
     {
         /* flow still not found, must be new or midstream */
 
-        union nDPId_ip const * netmask;
-        union nDPId_ip const * subnet;
+        union nDPId_ip const * netmask = NULL;
+        union nDPId_ip const * subnet = NULL;
         switch (flow_basic.l3_type)
         {
             case L3_IP:
@@ -2617,18 +2815,17 @@ static void ndpi_process_packet(uint8_t * const args,
             return;
         }
 
-        memset(flow_to_process->ndpi_flow,
-               0,
-               (SIZEOF_FLOW_STRUCT > sizeof(struct ndpi_flow_struct) ? SIZEOF_FLOW_STRUCT
-                                                                     : sizeof(struct ndpi_flow_struct)));
+        memset(flow_to_process->ndpi, 0, sizeof(*flow_to_process->ndpi));
 
-        ndpi_src = flow_to_process->ndpi_src;
-        ndpi_dst = flow_to_process->ndpi_dst;
+        ndpi_src = &flow_to_process->ndpi->src;
+        ndpi_dst = &flow_to_process->ndpi->dst;
 
         is_new_flow = 1;
     }
     else
     {
+        /* flow already exists in the tree */
+
         struct nDPId_flow_basic * const flow_basic_to_process = *(struct nDPId_flow_basic **)tree_result;
         /* Update last seen timestamp for timeout handling. */
         flow_basic_to_process->last_seen = time_ms;
@@ -2651,15 +2848,30 @@ static void ndpi_process_packet(uint8_t * const args,
         }
         flow_to_process = (struct nDPId_flow_info *)flow_basic_to_process;
 
+#ifdef ENABLE_ZLIB
+        if (nDPId_options.enable_zlib_compression != 0 && flow_to_process->ndpi_compressed_size > 0)
+        {
+            int ret = ndpi_data_inflate(flow_to_process);
+            if (ret <= 0)
+            {
+                syslog(LOG_DAEMON | LOG_ERR,
+                       "zLib decompression failed for existing flow %u with error code: %d",
+                       flow_to_process->flow_extended.flow_id,
+                       ret);
+                return;
+            }
+        }
+#endif
+
         if (direction_changed != 0)
         {
-            ndpi_src = flow_to_process->ndpi_dst;
-            ndpi_dst = flow_to_process->ndpi_src;
+            ndpi_src = &flow_to_process->ndpi->dst;
+            ndpi_dst = &flow_to_process->ndpi->src;
         }
         else
         {
-            ndpi_src = flow_to_process->ndpi_src;
-            ndpi_dst = flow_to_process->ndpi_dst;
+            ndpi_src = &flow_to_process->ndpi->src;
+            ndpi_dst = &flow_to_process->ndpi->dst;
         }
     }
 
@@ -2695,7 +2907,7 @@ static void ndpi_process_packet(uint8_t * const args,
                          &flow_to_process->flow_extended,
                          PACKET_EVENT_PAYLOAD_FLOW);
 
-    if (flow_to_process->ndpi_flow->num_processed_pkts == nDPId_options.max_packets_per_flow_to_process - 1)
+    if (flow_to_process->ndpi->flow.num_processed_pkts == nDPId_options.max_packets_per_flow_to_process - 1)
     {
         if (flow_to_process->detection_completed != 0)
         {
@@ -2706,7 +2918,7 @@ static void ndpi_process_packet(uint8_t * const args,
             /* last chance to guess something, better then nothing */
             uint8_t protocol_was_guessed = 0;
             flow_to_process->guessed_l7_protocol =
-                ndpi_detection_giveup(workflow->ndpi_struct, flow_to_process->ndpi_flow, 1, &protocol_was_guessed);
+                ndpi_detection_giveup(workflow->ndpi_struct, &flow_to_process->ndpi->flow, 1, &protocol_was_guessed);
             if (protocol_was_guessed != 0)
             {
                 jsonize_flow_event(reader_thread, flow_to_process, FLOW_EVENT_GUESSED);
@@ -2719,7 +2931,7 @@ static void ndpi_process_packet(uint8_t * const args,
     }
 
     flow_to_process->detected_l7_protocol = ndpi_detection_process_packet(workflow->ndpi_struct,
-                                                                          flow_to_process->ndpi_flow,
+                                                                          &flow_to_process->ndpi->flow,
                                                                           ip != NULL ? (uint8_t *)ip : (uint8_t *)ip6,
                                                                           ip_size,
                                                                           time_ms,
@@ -2732,11 +2944,11 @@ static void ndpi_process_packet(uint8_t * const args,
         flow_to_process->detection_completed = 1;
         workflow->detected_flow_protocols++;
         jsonize_flow_event(reader_thread, flow_to_process, FLOW_EVENT_DETECTED);
-        flow_to_process->last_ndpi_flow_struct_hash = calculate_ndpi_flow_struct_hash(flow_to_process->ndpi_flow);
+        flow_to_process->last_ndpi_flow_struct_hash = calculate_ndpi_flow_struct_hash(&flow_to_process->ndpi->flow);
     }
     else if (flow_to_process->detection_completed == 1)
     {
-        uint32_t hash = calculate_ndpi_flow_struct_hash(flow_to_process->ndpi_flow);
+        uint32_t hash = calculate_ndpi_flow_struct_hash(&flow_to_process->ndpi->flow);
         if (hash != flow_to_process->last_ndpi_flow_struct_hash)
         {
             jsonize_flow_event(reader_thread, flow_to_process, FLOW_EVENT_DETECTION_UPDATE);
@@ -2744,11 +2956,24 @@ static void ndpi_process_packet(uint8_t * const args,
         }
     }
 
-    if (flow_to_process->ndpi_flow->num_processed_pkts == nDPId_options.max_packets_per_flow_to_process)
+    if (flow_to_process->ndpi->flow.num_processed_pkts == nDPId_options.max_packets_per_flow_to_process)
     {
         free_ndpi_structs(flow_to_process);
         flow_to_process->flow_extended.flow_basic.type = FT_FINISHED;
     }
+#ifdef ENABLE_ZLIB
+    else if (nDPId_options.enable_zlib_compression != 0)
+    {
+        int ret = ndpi_data_deflate(flow_to_process);
+        if (ret <= 0)
+        {
+            syslog(LOG_DAEMON | LOG_ERR,
+                   "zLib compression failed for flow %u with error code: %d",
+                   flow_to_process->flow_extended.flow_id,
+                   ret);
+        }
+    }
+#endif
 }
 
 static void run_pcap_loop(struct nDPId_reader_thread const * const reader_thread)
@@ -3120,11 +3345,14 @@ static int nDPId_parse_options(int argc, char ** argv)
         "\t  \tThis value is required for correct flow handling of\n"
         "\t  \tmultiple instances and should be unique.\n"
         "\t  \tDefaults to your hostname.\n"
+#ifdef ENABLE_ZLIB
+        "\t-z\tEnable flow memory zLib compression. (Experimental!)\n"
+#endif
         "\t-o\t(Carefully) Tune some daemon options. See subopts below.\n"
         "\t-v\tversion\n"
         "\t-h\tthis\n\n";
 
-    while ((opt = getopt(argc, argv, "hi:IEB:lc:dp:u:g:P:C:J:S:a:o:vh")) != -1)
+    while ((opt = getopt(argc, argv, "hi:IEB:lc:dp:u:g:P:C:J:S:a:zo:vh")) != -1)
     {
         switch (opt)
         {
@@ -3182,6 +3410,14 @@ static int nDPId_parse_options(int argc, char ** argv)
             case 'a':
                 nDPId_options.instance_alias = strdup(optarg);
                 break;
+            case 'z':
+#ifdef ENABLE_ZLIB
+                nDPId_options.enable_zlib_compression = 1;
+                break;
+#else
+                fprintf(stderr, "nDPId was built w/o zLib compression\n");
+                return 1;
+#endif
             case 'o':
             {
                 int errfnd = 0;
@@ -3283,6 +3519,12 @@ static int validate_options(char const * const arg0)
 {
     int retval = 0;
 
+#ifdef ENABLE_ZLIB
+    if (nDPId_options.enable_zlib_compression != 0)
+    {
+        fprintf(stderr, "%s: WARNING: zLib compression is an experimental feature! Expect random crashes.\n", arg0);
+    }
+#endif
     if (is_path_absolute("JSON socket", nDPId_options.json_sockpath) != 0)
     {
         retval = 1;
@@ -3423,7 +3665,7 @@ int main(int argc, char ** argv)
 
     openlog("nDPId", LOG_CONS | LOG_PERROR, LOG_DAEMON);
 #ifdef ENABLE_MEMORY_PROFILING
-    syslog(LOG_DAEMON, "size/processed-flow: %zu bytes\n", sizeof(struct nDPId_flow_info));
+    syslog(LOG_DAEMON, "size/flow: %zu bytes\n", sizeof(struct nDPId_flow_info) + sizeof(struct nDPI_data));
 #endif
 
     if (setup_reader_threads() != 0)