Remove "zoom" cache (#2420)

This cache was added in b6b4967aa, when there was no real Zoom support.
With 63f349319, a proper identification of multimedia stream has been
added, making this cache quite useless: any improvements on Zoom
classification should be properly done in Zoom dissector.

Tested for some months with a few 10Gbits links of residential traffic: the
cache pretty much never returned a valid hit.

4 files changed, 1 insertions, 108 deletions

diff --git a/src/include/ndpi_private.h b/src/include/ndpi_private.h
index c5192f2be..ce689354d 100644
--- a/src/include/ndpi_private.h
+++ b/src/include/ndpi_private.h
@@ -157,9 +157,6 @@ struct ndpi_global_context {
   /* NDPI_PROTOCOL_BITTORRENT */
   struct ndpi_lru_cache *bittorrent_global_cache;
 
-  /* NDPI_PROTOCOL_ZOOM */
-  struct ndpi_lru_cache *zoom_global_cache;
-
   /* NDPI_PROTOCOL_STUN and subprotocols */
   struct ndpi_lru_cache *stun_global_cache;
   struct ndpi_lru_cache *stun_zoom_global_cache;
@@ -211,9 +208,6 @@ struct ndpi_detection_module_config_struct {
   int bittorrent_cache_num_entries;
   int bittorrent_cache_ttl;
   int bittorrent_cache_scope;
-  int zoom_cache_num_entries;
-  int zoom_cache_ttl;
-  int zoom_cache_scope;
   int stun_cache_num_entries;
   int stun_cache_ttl;
   int stun_cache_scope;
@@ -360,9 +354,6 @@ struct ndpi_detection_module_struct {
   /* NDPI_PROTOCOL_BITTORRENT */
   struct ndpi_lru_cache *bittorrent_cache;
 
-  /* NDPI_PROTOCOL_ZOOM */
-  struct ndpi_lru_cache *zoom_cache;
-
   /* NDPI_PROTOCOL_STUN and subprotocols */
   struct ndpi_lru_cache *stun_cache;
   struct ndpi_lru_cache *stun_zoom_cache;
diff --git a/src/include/ndpi_typedefs.h b/src/include/ndpi_typedefs.h
index aa59c5081..51b12595b 100644
--- a/src/include/ndpi_typedefs.h
+++ b/src/include/ndpi_typedefs.h
@@ -742,7 +742,6 @@ struct ndpi_automa_stats {
 typedef enum {
   NDPI_LRUCACHE_OOKLA = 0,
   NDPI_LRUCACHE_BITTORRENT,
-  NDPI_LRUCACHE_ZOOM,
   NDPI_LRUCACHE_STUN,
   NDPI_LRUCACHE_TLS_CERT,
   NDPI_LRUCACHE_MINING,
diff --git a/src/lib/ndpi_main.c b/src/lib/ndpi_main.c
index 3d897edfd..880e9e0fe 100644
--- a/src/lib/ndpi_main.c
+++ b/src/lib/ndpi_main.c
@@ -3224,8 +3224,6 @@ void ndpi_global_deinit(struct ndpi_global_context *g_ctx) {
       ndpi_lru_free_cache(g_ctx->ookla_global_cache);
     if(g_ctx->bittorrent_global_cache)
       ndpi_lru_free_cache(g_ctx->bittorrent_global_cache);
-    if(g_ctx->zoom_global_cache)
-      ndpi_lru_free_cache(g_ctx->zoom_global_cache);
     if(g_ctx->stun_global_cache)
       ndpi_lru_free_cache(g_ctx->stun_global_cache);
     if(g_ctx->stun_zoom_global_cache)
@@ -3738,22 +3736,6 @@ int ndpi_finalize_initialization(struct ndpi_detection_module_struct *ndpi_str)
                    ndpi_str->cfg.bittorrent_cache_num_entries);
     }
   }
-  if(ndpi_str->cfg.zoom_cache_num_entries > 0) {
-    if(ndpi_str->cfg.zoom_cache_scope == NDPI_LRUCACHE_SCOPE_GLOBAL) {
-      if(!ndpi_str->g_ctx->zoom_global_cache) {
-        ndpi_str->g_ctx->zoom_global_cache = ndpi_lru_cache_init(ndpi_str->cfg.zoom_cache_num_entries,
-                                                                 ndpi_str->cfg.zoom_cache_ttl, 1);
-      }
-      ndpi_str->zoom_cache = ndpi_str->g_ctx->zoom_global_cache;
-    } else {
-      ndpi_str->zoom_cache = ndpi_lru_cache_init(ndpi_str->cfg.zoom_cache_num_entries,
-                                                 ndpi_str->cfg.zoom_cache_ttl, 0);
-    }
-    if(!ndpi_str->zoom_cache) {
-      NDPI_LOG_ERR(ndpi_str, "Error allocating lru cache (num_entries %u)\n",
-                   ndpi_str->cfg.zoom_cache_num_entries);
-    }
-  }
   if(ndpi_str->cfg.stun_cache_num_entries > 0) {
     if(ndpi_str->cfg.stun_cache_scope == NDPI_LRUCACHE_SCOPE_GLOBAL) {
       if(!ndpi_str->g_ctx->stun_global_cache) {
@@ -4156,10 +4138,6 @@ void ndpi_exit_detection_module(struct ndpi_detection_module_struct *ndpi_str) {
        ndpi_str->bittorrent_cache)
       ndpi_lru_free_cache(ndpi_str->bittorrent_cache);
 
-    if(!ndpi_str->cfg.zoom_cache_scope &&
-       ndpi_str->zoom_cache)
-      ndpi_lru_free_cache(ndpi_str->zoom_cache);
-
     if(!ndpi_str->cfg.stun_cache_scope &&
        ndpi_str->stun_cache)
       ndpi_lru_free_cache(ndpi_str->stun_cache);
@@ -7583,61 +7561,6 @@ int search_into_bittorrent_cache(struct ndpi_detection_module_struct *ndpi_struc
 
 /* ********************************************************************************* */
 
-/* #define ZOOM_CACHE_DEBUG */
-
-
-static u_int64_t make_zoom_key(struct ndpi_flow_struct *flow, int server) {
-  u_int64_t key;
-
-  if(server) {
-    if(flow->is_ipv6)
-      key = ndpi_quick_hash64((const char *)flow->s_address.v6, 16);
-    else
-      key = flow->s_address.v4;
-  } else {
-    if(flow->is_ipv6)
-      key = ndpi_quick_hash64((const char *)flow->c_address.v6, 16);
-    else
-      key = flow->c_address.v4;
-  }
-
-  return key;
-}
-
-/* ********************************************************************************* */
-
-static u_int8_t ndpi_search_into_zoom_cache(struct ndpi_detection_module_struct *ndpi_struct,
-					    struct ndpi_flow_struct *flow, int server) {
-
-  if(ndpi_struct->zoom_cache) {
-    u_int16_t cached_proto;
-    u_int64_t key;
-
-    key = make_zoom_key(flow, server);
-    u_int8_t found = ndpi_lru_find_cache(ndpi_struct->zoom_cache, key, &cached_proto,
-					 0 /* Don't remove it as it can be used for other connections */,
-					 ndpi_get_current_time(flow));
-
-#ifdef ZOOM_CACHE_DEBUG
-    printf("[Zoom] *** [TCP] SEARCHING key 0x%llx [found: %u]\n", (long long unsigned int)key, found);
-#endif
-
-    return(found);
-  }
-
-  return(0);
-}
-
-/* ********************************************************************************* */
-
-static void ndpi_add_connection_as_zoom(struct ndpi_detection_module_struct *ndpi_struct,
-					struct ndpi_flow_struct *flow) {
-  if(ndpi_struct->zoom_cache)
-    ndpi_lru_add_to_cache(ndpi_struct->zoom_cache, make_zoom_key(flow, 1), NDPI_PROTOCOL_ZOOM, ndpi_get_current_time(flow));
-}
-
-/* ********************************************************************************* */
-
 /*
   NOTE:
 
@@ -7707,15 +7630,6 @@ ndpi_protocol ndpi_detection_giveup(struct ndpi_detection_module_struct *ndpi_st
     ret.app_protocol = flow->detected_protocol_stack[0];
   }
 
-  /* Does it looks like Zoom? */
-  if(ret.app_protocol == NDPI_PROTOCOL_UNKNOWN &&
-     flow->l4_proto == IPPROTO_UDP && /* Zoom/UDP used for video */
-     ((ntohs(flow->s_port) == 8801 && ndpi_search_into_zoom_cache(ndpi_str, flow, 1)) ||
-      (ntohs(flow->c_port) == 8801 && ndpi_search_into_zoom_cache(ndpi_str, flow, 0)))) {
-    ndpi_set_detected_protocol(ndpi_str, flow, NDPI_PROTOCOL_ZOOM, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI_PARTIAL_CACHE);
-    ret.app_protocol = flow->detected_protocol_stack[0];
-  }
-
   /* Does it looks like Zoom (via STUN)? */
   if(ret.app_protocol == NDPI_PROTOCOL_UNKNOWN &&
      stun_search_into_zoom_cache(ndpi_str, flow)) {
@@ -8614,10 +8528,6 @@ static ndpi_protocol ndpi_internal_detection_process_packet(struct ndpi_detectio
 
   /* ndpi_reconcile_protocols(ndpi_str, flow, &ret); */
 
-  /* Zoom cache */
-  if((ret.app_protocol == NDPI_PROTOCOL_ZOOM) && (flow->l4_proto == IPPROTO_TCP))
-    ndpi_add_connection_as_zoom(ndpi_str, flow);
-
   if(ndpi_str->cfg.fully_encrypted_heuristic &&
      ret.app_protocol == NDPI_PROTOCOL_UNKNOWN && /* Only for unknown traffic */
      flow->packet_counter == 1 && packet->payload_packet_len > 0) {
@@ -10235,9 +10145,6 @@ int ndpi_get_lru_cache_stats(struct ndpi_global_context *g_ctx,
   case NDPI_LRUCACHE_BITTORRENT:
     ndpi_lru_get_stats(is_local ? ndpi_struct->bittorrent_cache : g_ctx->bittorrent_global_cache, stats);
     return 0;
-  case NDPI_LRUCACHE_ZOOM:
-    ndpi_lru_get_stats(is_local ? ndpi_struct->zoom_cache : g_ctx->zoom_global_cache, stats);
-    return 0;
   case NDPI_LRUCACHE_STUN:
     ndpi_lru_get_stats(is_local ? ndpi_struct->stun_cache : g_ctx->stun_global_cache, stats);
     return 0;
@@ -11270,10 +11177,6 @@ static const struct cfg_param {
   { NULL,            "lru.bittorrent.ttl",                      "0", "0", "16777215", CFG_PARAM_INT, __OFF(bittorrent_cache_ttl), NULL },
   { NULL,            "lru.bittorrent.scope",                    "0", "0", "1", CFG_PARAM_INT, __OFF(bittorrent_cache_scope), clbk_only_with_global_ctx },
 
-  { NULL,            "lru.zoom.size",                           "512", "0", "16777215", CFG_PARAM_INT, __OFF(zoom_cache_num_entries), NULL },
-  { NULL,            "lru.zoom.ttl",                            "0", "0", "16777215", CFG_PARAM_INT, __OFF(zoom_cache_ttl), NULL },
-  { NULL,            "lru.zoom.scope",                          "0", "0", "1", CFG_PARAM_INT, __OFF(zoom_cache_scope), clbk_only_with_global_ctx },
-
   { NULL,            "lru.stun.size",                           "1024", "0", "16777215", CFG_PARAM_INT, __OFF(stun_cache_num_entries), NULL },
   { NULL,            "lru.stun.ttl",                            "0", "0", "16777215", CFG_PARAM_INT, __OFF(stun_cache_ttl), NULL },
   { NULL,            "lru.stun.scope",                          "0", "0", "1", CFG_PARAM_INT, __OFF(stun_cache_scope), clbk_only_with_global_ctx },
diff --git a/src/lib/ndpi_utils.c b/src/lib/ndpi_utils.c
index f75eb3d9c..3314cbea2 100644
--- a/src/lib/ndpi_utils.c
+++ b/src/lib/ndpi_utils.c
@@ -3128,7 +3128,7 @@ int64_t ndpi_strtonum(const char *numstr, int64_t minval, int64_t maxval, const
 
 const char *ndpi_lru_cache_idx_to_name(lru_cache_type idx)
 {
-  const char *names[NDPI_LRUCACHE_MAX] = { "ookla", "bittorrent", "zoom", "stun",
+  const char *names[NDPI_LRUCACHE_MAX] = { "ookla", "bittorrent", "stun",
                                            "tls_cert", "mining", "msteams", "stun_zoom" };
 
   if(idx < 0 || idx >= NDPI_LRUCACHE_MAX)