DNS: evaluate all flow risks even if sub-classification is disabled

ntop · Feb 11, 2025 · c12006c · c12006c
1 parent 65c224e
commit c12006c
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Showing 13 changed files with 75 additions and 47 deletions.
diff --git a/doc/configuration_parameters.md b/doc/configuration_parameters.md
@@ -67,7 +67,7 @@ List of the supported configuration options:
 | "stun"       | "metadata.attribute.relayed_address"      | enable        | NULL      | NULL      | Enable/disable extraction of (xor-)relayed-address attribute for STUN flows. If it is disabled, STUN classification might be significant faster |
 | "stun"       | "metadata.attribute.peer_address"         | enable        | NULL      | NULL      | Enable/disable extraction of (xor-)peer-address attribute for STUN flows. If it is disabled, STUN classification might be significant faster; however sub-classification capability might be negatively impacted |
 | "bittorrent" | "metadata.hash"                           | enable        | NULL      | NULL      | Enable/disable extraction of hash metadata for Bittorrent flows. |
-| "dns"        | "subclassification"                       | enable        | NULL      | NULL      | Enable/disable sub-classification of DNS flows (via query/response domain name). If disabled, some flow risks are not checked |
+| "dns"        | "subclassification"                       | enable        | NULL      | NULL      | Enable/disable sub-classification of DNS flows (via query/response domain name). |
 | "dns"        | "process_response"                        | enable        | NULL      | NULL      | Enable/disable processing of DNS responses. By default, DNS flows are fully classified after the first request/response pair (or after the first response, if the request is missing). If this parameter is disabled, the flows are fully classified after the first packet, i.e. usually after the first request; in that case, some flow risks are not checked and some metadata are not exported |
 | "http"       | "process_response"                        | enable        | NULL      | NULL      | Enable/disable processing of HTTP responses. By default, HTTP flows are usually fully classified after the first request/response pair. If this parameter is disabled, the flows are fully classified after the first request (or after the first response, if the request is missing); in that case, some flow risks are not checked and some metadata are not exported |
 | "http"       | "subclassification"                       | enable        | NULL      | NULL      | Enable/disable sub-classification of HTTP flows |

diff --git a/src/include/ndpi_api.h b/src/include/ndpi_api.h
@@ -488,6 +488,7 @@ extern "C" {
    * @par    string_to_match_len = the length of the string
    * @par    ret_match           = completed returned match information
    * @par    master_protocol_id  = value of the ID associated to the master protocol detected
+   * @par    update_flow_classification = update or not protocol (sub)classification
    * @return the ID of the matched subprotocol
    *
    */
@@ -496,7 +497,8 @@ extern "C" {
 					char *string_to_match,
 					u_int string_to_match_len,
 					ndpi_protocol_match_result *ret_match,
-					u_int16_t master_protocol_id);
+					u_int16_t master_protocol_id,
+					int update_flow_classification);
 
   /**
    * Check if the string content passed match with a protocol

diff --git a/src/lib/ndpi_main.c b/src/lib/ndpi_main.c
@@ -10413,15 +10413,16 @@ u_int16_t ndpi_match_host_subprotocol(struct ndpi_detection_module_struct *ndpi_
 				      struct ndpi_flow_struct *flow,
 				      char *string_to_match, u_int string_to_match_len,
 				      ndpi_protocol_match_result *ret_match,
-				      u_int16_t master_protocol_id) {
+				      u_int16_t master_protocol_id,
+				      int update_flow_classification) {
   u_int16_t rc;
   ndpi_protocol_category_t id;
 
   if(!ndpi_str) return(-1);
 
   memset(ret_match, 0, sizeof(*ret_match));
 
-  rc = ndpi_automa_match_string_subprotocol(ndpi_str, flow,
+  rc = ndpi_automa_match_string_subprotocol(ndpi_str, update_flow_classification ? flow : NULL,
 					    string_to_match, string_to_match_len,
 					    master_protocol_id, ret_match);
   id = ret_match->protocol_category;
@@ -10430,13 +10431,12 @@ u_int16_t ndpi_match_host_subprotocol(struct ndpi_detection_module_struct *ndpi_
 				    string_to_match_len, &id) != -1) {
     /* if(id != -1) */ {
       ret_match->protocol_category = id;
-      if(flow)
-        flow->category = id;
+      flow->category = id;
       rc = master_protocol_id;
     }
   }
 
-  if(flow && ndpi_str->risky_domain_automa.ac_automa != NULL) {
+  if(ndpi_str->risky_domain_automa.ac_automa != NULL) {
     u_int32_t proto_id;
     u_int16_t rc1 = ndpi_match_string_common(ndpi_str->risky_domain_automa.ac_automa,
 					     string_to_match, string_to_match_len,
@@ -10450,7 +10450,7 @@ u_int16_t ndpi_match_host_subprotocol(struct ndpi_detection_module_struct *ndpi_
   }
 
   /* Add punycode check */
-  if(flow && ndpi_check_punycode_string(string_to_match, string_to_match_len)) {
+  if(ndpi_check_punycode_string(string_to_match, string_to_match_len)) {
     char str[64] = { '\0' };
 
     strncpy(str, string_to_match, ndpi_min(string_to_match_len, sizeof(str)-1));
@@ -10477,7 +10477,7 @@ int ndpi_match_hostname_protocol(struct ndpi_detection_module_struct *ndpi_struc
     what = name, what_len = name_len;
 
   subproto = ndpi_match_host_subprotocol(ndpi_struct, flow, what, what_len,
-					 &ret_match, master_protocol);
+					 &ret_match, master_protocol, 1);
 
   if(subproto != NDPI_PROTOCOL_UNKNOWN) {
     ndpi_set_detected_protocol(ndpi_struct, flow, subproto, master_protocol, NDPI_CONFIDENCE_DPI);

diff --git a/src/lib/protocols/dns.c b/src/lib/protocols/dns.c
@@ -801,44 +801,39 @@ static void ndpi_search_dns(struct ndpi_detection_module_struct *ndpi_struct, st
       }
     }
 
-    if(len > 0) {
-      if(ndpi_struct->cfg.dns_subclassification_enabled || ndpi_struct->cfg.fpc_enabled) {
-        ndpi_protocol_match_result ret_match;
-
-        /* Avoid writing on flow (i.e. updating classification) if subclassification is disabled */
-        ret.proto.app_protocol = ndpi_match_host_subprotocol(ndpi_struct, ndpi_struct->cfg.dns_subclassification_enabled ? flow : NULL,
-						       flow->host_server_name,
-						       strlen(flow->host_server_name),
-						       &ret_match,
-						       NDPI_PROTOCOL_DNS);
-        /* Add to FPC DNS cache */
-        if(ndpi_struct->cfg.fpc_enabled &&
-           ret.proto.app_protocol != NDPI_PROTOCOL_UNKNOWN &&
-           ret.proto.app_protocol != NDPI_PROTOCOL_DNS &&
-           (flow->protos.dns.rsp_type == 0x1 || flow->protos.dns.rsp_type == 0x1c) && /* A, AAAA */
-           ndpi_struct->fpc_dns_cache) {
-            ndpi_lru_add_to_cache(ndpi_struct->fpc_dns_cache,
-                                  fpc_dns_cache_key_from_dns_info(flow), ret.proto.app_protocol,
-                                  ndpi_get_current_time(flow));
-        }
+    if(strlen(flow->host_server_name) > 0) {
+      ndpi_protocol_match_result ret_match;
+
+      /* Avoid updating classification if subclassification is disabled */
+      ret.proto.app_protocol = ndpi_match_host_subprotocol(ndpi_struct, flow,
+                                                           flow->host_server_name,
+                                                           strlen(flow->host_server_name),
+                                                           &ret_match,
+                                                           NDPI_PROTOCOL_DNS,
+                                                           ndpi_struct->cfg.dns_subclassification_enabled ? 1 : 0);
+      /* Add to FPC DNS cache */
+      if(ndpi_struct->cfg.fpc_enabled &&
+         ret.proto.app_protocol != NDPI_PROTOCOL_UNKNOWN &&
+         ret.proto.app_protocol != NDPI_PROTOCOL_DNS &&
+         (flow->protos.dns.rsp_type == 0x1 || flow->protos.dns.rsp_type == 0x1c) && /* A, AAAA */
+         ndpi_struct->fpc_dns_cache) {
+        ndpi_lru_add_to_cache(ndpi_struct->fpc_dns_cache,
+                              fpc_dns_cache_key_from_dns_info(flow), ret.proto.app_protocol,
+                              ndpi_get_current_time(flow));
+      }
 
-        if(!ndpi_struct->cfg.dns_subclassification_enabled)
-          ret.proto.app_protocol = NDPI_PROTOCOL_UNKNOWN;
+      if(!ndpi_struct->cfg.dns_subclassification_enabled)
+        ret.proto.app_protocol = NDPI_PROTOCOL_UNKNOWN;
 
-        if(ret.proto.app_protocol == NDPI_PROTOCOL_UNKNOWN)
-	  ret.proto.master_protocol = checkDNSSubprotocol(s_port, d_port);
-        else
-	  ret.proto.master_protocol = NDPI_PROTOCOL_DNS;
+      if(ret.proto.app_protocol == NDPI_PROTOCOL_UNKNOWN)
+	ret.proto.master_protocol = checkDNSSubprotocol(s_port, d_port);
+      else
+	ret.proto.master_protocol = NDPI_PROTOCOL_DNS;
 
-        ndpi_check_dga_name(ndpi_struct, flow, flow->host_server_name, 1, 0);
-      } else {
-        ret.proto.master_protocol = checkDNSSubprotocol(s_port, d_port);
-        ret.proto.app_protocol = NDPI_PROTOCOL_UNKNOWN;
-      }
+      ndpi_check_dga_name(ndpi_struct, flow, flow->host_server_name, 1, 0);
 
       /* Category is always NDPI_PROTOCOL_CATEGORY_NETWORK, regardless of the subprotocol */
       flow->category = NDPI_PROTOCOL_CATEGORY_NETWORK;
-
     }
 
     /* Report if this is a DNS query or reply */

diff --git a/src/lib/protocols/fastcgi.c b/src/lib/protocols/fastcgi.c
@@ -210,7 +210,7 @@ static void ndpi_search_fastcgi(struct ndpi_detection_module_struct *ndpi_struct
       ndpi_match_host_subprotocol(ndpi_struct, flow,
                                   flow->host_server_name,
                                   strlen(flow->host_server_name),
-                                  &ret_match, NDPI_PROTOCOL_FASTCGI);
+                                  &ret_match, NDPI_PROTOCOL_FASTCGI, 1);
       ndpi_check_dga_name(ndpi_struct, flow,
                           flow->host_server_name, 1, 0);
       if(ndpi_is_valid_hostname((char *)packet->host_line.ptr,

diff --git a/src/lib/protocols/http.c b/src/lib/protocols/http.c
@@ -571,7 +571,7 @@ static void ndpi_http_parse_subprotocol(struct ndpi_detection_module_struct *ndp
 				    origin_hostname,
 				    origin_hostname_len,
 				    &ret_match,
-				    master_protocol);
+				    master_protocol, 1);
       }
     }
   }

diff --git a/src/lib/protocols/quic.c b/src/lib/protocols/quic.c
@@ -1460,7 +1460,7 @@ void process_chlo(struct ndpi_detection_module_struct *ndpi_struct,
       ndpi_match_host_subprotocol(ndpi_struct, flow,
                                   flow->host_server_name,
                                   strlen(flow->host_server_name),
-                                  &ret_match, NDPI_PROTOCOL_QUIC);
+                                  &ret_match, NDPI_PROTOCOL_QUIC, 1);
       flow->protos.tls_quic.client_hello_processed = 1; /* Allow matching of custom categories */
 
       ndpi_check_dga_name(ndpi_struct, flow,

diff --git a/tests/cfgs/dns_subclassification_and_process_response_disable/result/dns.pcap.out b/tests/cfgs/dns_subclassification_and_process_response_disable/result/dns.pcap.out
@@ -9,7 +9,7 @@ LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 LRU cache fpc_dns:    0/0/0 (insert/search/found)
 Automa host:          2/2 (search/found)
-Automa domain:        0/0 (search/found)
+Automa domain:        2/0 (search/found)
 Automa tls cert:      0/0 (search/found)
 Automa risk mask:     2/0 (search/found)
 Automa common alpns:  0/0 (search/found)

diff --git a/tests/cfgs/dns_subclassification_enable/config.txt b/tests/cfgs/dns_subclassification_enable/config.txt
@@ -0,0 +1 @@
+--cfg=dns,subclassification,1
diff --git a/tests/cfgs/dns_subclassification_enable/pcap/dns.pcap b/tests/cfgs/dns_subclassification_enable/pcap/dns.pcap
@@ -0,0 +1 @@
+../../default/pcap/dns.pcap
diff --git a/tests/cfgs/dns_subclassification_enable/result/dns.pcap.out b/tests/cfgs/dns_subclassification_enable/result/dns.pcap.out
@@ -0,0 +1,29 @@
+DPI Packets (UDP):	3	(1.50 pkts/flow)
+Confidence DPI              : 2 (flows)
+Num dissector calls: 2 (1.00 diss/flow)
+LRU cache ookla:      0/0/0 (insert/search/found)
+LRU cache bittorrent: 0/0/0 (insert/search/found)
+LRU cache stun:       0/0/0 (insert/search/found)
+LRU cache tls_cert:   0/0/0 (insert/search/found)
+LRU cache mining:     0/0/0 (insert/search/found)
+LRU cache msteams:    0/0/0 (insert/search/found)
+LRU cache fpc_dns:    1/0/0 (insert/search/found)
+Automa host:          3/3 (search/found)
+Automa domain:        3/0 (search/found)
+Automa tls cert:      0/0 (search/found)
+Automa risk mask:     1/0 (search/found)
+Automa common alpns:  0/0 (search/found)
+Patricia risk mask:   2/0 (search/found)
+Patricia risk mask IPv6: 0/0 (search/found)
+Patricia risk:        1/0 (search/found)
+Patricia risk IPv6:   0/0 (search/found)
+Patricia protocols:   4/0 (search/found)
+Patricia protocols IPv6: 0/0 (search/found)
+
+Google	3	226	1
+WhatsApp	2	310	1
+
+Acceptable                       5 536           2            
+
+	1	UDP 82.178.113.245:47255 <-> 82.178.158.181:53 [VLAN: 785][proto: 5.142/DNS.WhatsApp][IP: 0/Unknown][ClearText][Confidence: DPI][FPC: 5.142/DNS.WhatsApp, Confidence: DPI][DPI packets: 2][cat: Network/14][1 pkts/91 bytes <-> 1 pkts/219 bytes][Goodput ratio: 36/73][0.00 sec][Hostname/SNI: e7.whatsapp.net][169.45.219.235][PLAIN TEXT (whatsapp)][Plen Bins: 0,50,0,0,0,50,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
+	2	UDP 192.168.170.20:53 <-> 192.168.170.8:32795 [proto: 5.126/DNS.Google][IP: 0/Unknown][ClearText][Confidence: DPI][FPC: 5.126/DNS.Google, Confidence: DPI][DPI packets: 1][cat: Network/14][2 pkts/151 bytes <-> 1 pkts/75 bytes][Goodput ratio: 44/43][41.07 sec][Hostname/SNI: www.l.google.com][0.0.0.0][PLAIN TEXT (google)][Plen Bins: 0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
diff --git a/tests/cfgs/subclassification_disable/result/anydesk.pcapng.out b/tests/cfgs/subclassification_disable/result/anydesk.pcapng.out
@@ -10,7 +10,7 @@ LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 LRU cache fpc_dns:    2/4/0 (insert/search/found)
 Automa host:          4/4 (search/found)
-Automa domain:        0/0 (search/found)
+Automa domain:        4/0 (search/found)
 Automa tls cert:      0/0 (search/found)
 Automa risk mask:     2/0 (search/found)
 Automa common alpns:  1/0 (search/found)

diff --git a/tests/cfgs/subclassification_disable/result/dns.pcap.out b/tests/cfgs/subclassification_disable/result/dns.pcap.out
@@ -9,7 +9,7 @@ LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 LRU cache fpc_dns:    1/0/0 (insert/search/found)
 Automa host:          3/3 (search/found)
-Automa domain:        0/0 (search/found)
+Automa domain:        3/0 (search/found)
 Automa tls cert:      0/0 (search/found)
 Automa risk mask:     2/0 (search/found)
 Automa common alpns:  0/0 (search/found)