TLS: allow sub-classification via ALPN

In some rare cases, it is possible to sub-classify the flow via ALPN
matching. This is particularly usefull for asymmetric traffic where the
Client Hello doens't have the SNI.

For the time being there is only one rule, about ANYDESK.

4 files changed, 37 insertions, 9 deletions

diff --git a/src/lib/protocols/tls.c b/src/lib/protocols/tls.c
index a602fbeeb..869fe504b 100644
--- a/src/lib/protocols/tls.c
+++ b/src/lib/protocols/tls.c
@@ -1257,6 +1257,26 @@ void switch_extra_dissection_to_tls(struct ndpi_detection_module_struct *ndpi_st
 
 /* **************************************** */
 
+static void tls_subclassify_by_alpn(struct ndpi_detection_module_struct *ndpi_struct,
+				    struct ndpi_flow_struct *flow) {
+  /* Right now we have only one rule so we can keep it trivial */
+
+  if (!flow->protos.tls_quic.alpn)
+    return;
+
+  if(strlen(flow->protos.tls_quic.alpn) > NDPI_STATICSTRING_LEN("anydesk/") &&
+     strncmp(flow->protos.tls_quic.alpn, "anydesk/", NDPI_STATICSTRING_LEN("anydesk/")) == 0) {
+#ifdef DEBUG_TLS
+    printf("Matching ANYDESK via alpn\n");
+#endif
+    ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_ANYDESK,
+			       __get_master(ndpi_struct, flow), NDPI_CONFIDENCE_DPI);
+    flow->protos.tls_quic.subprotocol_detected = 1;
+  }
+}
+
+/* **************************************** */
+
 static void tlsCheckUncommonALPN(struct ndpi_detection_module_struct *ndpi_struct,
 				 struct ndpi_flow_struct *flow) {
   char * alpn_start = flow->protos.tls_quic.alpn;
@@ -2182,9 +2202,16 @@ int processClientServerHello(struct ndpi_detection_module_struct *ndpi_struct,
 #ifdef DEBUG_TLS
 		printf("Client TLS [ALPN: %s][len: %u]\n", alpn_str, alpn_str_len);
 #endif
-		if(flow->protos.tls_quic.alpn == NULL)
+		if(flow->protos.tls_quic.alpn == NULL) {
 		  flow->protos.tls_quic.alpn = ndpi_strdup(alpn_str);
 
+		  /* Without SNI matching we can try to sub-classify the flow via ALPN.
+		     Note that this happens only on very rare cases, not the common ones
+		     ("h2", "http/1.1", ...). Usefull for asymmetric traffic */
+		  if(!flow->protos.tls_quic.subprotocol_detected)
+	            tls_subclassify_by_alpn(ndpi_struct, flow);
+		}
+
 		ndpi_snprintf(ja3.client.alpn, sizeof(ja3.client.alpn), "%s", alpn_str);
 
 		/* Replace , with - as in JA3 */
diff --git a/tests/result/anydesk.pcapng.out b/tests/result/anydesk.pcapng.out
index 82659b032..59246fbcf 100644
--- a/tests/result/anydesk.pcapng.out
+++ b/tests/result/anydesk.pcapng.out
@@ -8,12 +8,12 @@ LRU cache ookla:      0/0/0 (insert/search/found)
 LRU cache bittorrent: 0/0/0 (insert/search/found)
 LRU cache zoom:       0/0/0 (insert/search/found)
 LRU cache stun:       0/0/0 (insert/search/found)
-LRU cache tls_cert:   4/8/0 (insert/search/found)
+LRU cache tls_cert:   3/6/0 (insert/search/found)
 LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 Automa host:          4/4 (search/found)
 Automa domain:        4/0 (search/found)
-Automa tls cert:      4/4 (search/found)
+Automa tls cert:      3/3 (search/found)
 Automa risk mask:     0/0 (search/found)
 Automa common alpns:  0/0 (search/found)
 Patricia risk mask:   14/0 (search/found)
diff --git a/tests/result/tls_client_certificate_with_missing_server_one.pcapng.out b/tests/result/tls_client_certificate_with_missing_server_one.pcapng.out
index 65d569510..1d8c26861 100644
--- a/tests/result/tls_client_certificate_with_missing_server_one.pcapng.out
+++ b/tests/result/tls_client_certificate_with_missing_server_one.pcapng.out
@@ -7,7 +7,7 @@ LRU cache ookla:      0/0/0 (insert/search/found)
 LRU cache bittorrent: 0/0/0 (insert/search/found)
 LRU cache zoom:       0/0/0 (insert/search/found)
 LRU cache stun:       0/0/0 (insert/search/found)
-LRU cache tls_cert:   0/3/0 (insert/search/found)
+LRU cache tls_cert:   0/1/0 (insert/search/found)
 LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 Automa host:          0/0 (search/found)
@@ -19,7 +19,8 @@ Patricia risk mask:   4/0 (search/found)
 Patricia risk:        0/0 (search/found)
 Patricia protocols:   4/0 (search/found)
 
-TLS	17	5526	2
+TLS	8	2093	1
+AnyDesk	9	3433	1
 
 JA3 Host Stats: 
 		 IP Address                  	 # JA3C     
@@ -27,5 +28,5 @@ JA3 Host Stats:
 	2	 195.181.174.176          	 1      
 
 
-	1	TCP 195.181.174.176:443 <-> 192.168.1.128:48260 [proto: 91/TLS][IP: 0/Unknown][Encrypted][Confidence: DPI][cat: Web/5][3 pkts/1654 bytes <-> 6 pkts/1779 bytes][Goodput ratio: 87/78][0.04 sec][ALPN: anydesk/6.2.0/linux][bytes ratio: -0.036 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 3/0 10/8 17/20 7/9][Pkt Len c2s/s2c min/avg/max/stddev: 66/66 551/296 1514/1160 681/400][Risk: ** Missing SNI TLS Extn **][Risk Score: 50][TLSv1.2][JA3C: 29b5a018fa5992fe23560c16af0dc9fc][JA3S: e58f0b3c1e9eefb8ee4f92aeceee5858][Firefox][Cipher: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384][Plen Bins: 0,0,0,0,0,0,0,0,0,33,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,33,0,0,0,0,0,0,0,0,0,0,33,0,0]
+	1	TCP 195.181.174.176:443 <-> 192.168.1.128:48260 [proto: 91.252/TLS.AnyDesk][IP: 0/Unknown][Encrypted][Confidence: DPI][cat: RemoteAccess/12][3 pkts/1654 bytes <-> 6 pkts/1779 bytes][Goodput ratio: 87/78][0.04 sec][ALPN: anydesk/6.2.0/linux][bytes ratio: -0.036 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 3/0 10/8 17/20 7/9][Pkt Len c2s/s2c min/avg/max/stddev: 66/66 551/296 1514/1160 681/400][Risk: ** Missing SNI TLS Extn **** Desktop/File Sharing **][Risk Score: 60][Risk Info: Found AnyDesk][TLSv1.2][JA3C: 29b5a018fa5992fe23560c16af0dc9fc][JA3S: e58f0b3c1e9eefb8ee4f92aeceee5858][Firefox][Cipher: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384][Plen Bins: 0,0,0,0,0,0,0,0,0,33,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,33,0,0,0,0,0,0,0,0,0,0,33,0,0]
 	2	TCP 192.168.1.128:59754 <-> 192.168.1.181:7070 [proto: 91/TLS][IP: 0/Unknown][Encrypted][Confidence: DPI][cat: Web/5][6 pkts/1953 bytes <-> 2 pkts/140 bytes][Goodput ratio: 79/0][0.08 sec][bytes ratio: 0.866 (Upload)][IAT c2s/s2c min/avg/max/stddev: 0/6 15/6 54/6 20/0][Pkt Len c2s/s2c min/avg/max/stddev: 66/66 326/70 1352/74 469/4][Risk: ** Known Proto on Non Std Port **** TLS (probably) Not Carrying HTTPS **** Missing SNI TLS Extn **][Risk Score: 110][Risk Info: No ALPN][TLSv1.2][JA3C: 201999283915cc31cee6b15472ef3332][Firefox][Plen Bins: 0,0,0,0,0,0,0,0,50,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,50,0,0,0,0,0,0,0]
diff --git a/tests/result/tls_unidirectional.pcap.out b/tests/result/tls_unidirectional.pcap.out
index 4f8fa35e7..9fb332c02 100644
--- a/tests/result/tls_unidirectional.pcap.out
+++ b/tests/result/tls_unidirectional.pcap.out
@@ -7,7 +7,7 @@ LRU cache ookla:      0/0/0 (insert/search/found)
 LRU cache bittorrent: 0/0/0 (insert/search/found)
 LRU cache zoom:       0/0/0 (insert/search/found)
 LRU cache stun:       0/0/0 (insert/search/found)
-LRU cache tls_cert:   0/2/0 (insert/search/found)
+LRU cache tls_cert:   0/1/0 (insert/search/found)
 LRU cache mining:     0/0/0 (insert/search/found)
 LRU cache msteams:    0/0/0 (insert/search/found)
 Automa host:          1/1 (search/found)
@@ -19,13 +19,13 @@ Patricia risk mask:   4/0 (search/found)
 Patricia risk:        0/0 (search/found)
 Patricia protocols:   3/1 (search/found)
 
-TLS	27	7693	1
 Google	6	6972	1
+AnyDesk	27	7693	1
 
 JA3 Host Stats: 
 		 IP Address                  	 # JA3C     
 	1	 192.168.1.128            	 1      
 
 
-	1	TCP 192.168.1.128:48260 -> 195.181.174.176:443 [proto: 91/TLS][IP: 0/Unknown][Encrypted][Confidence: DPI][cat: Web/5][27 pkts/7693 bytes -> 0 pkts/0 bytes][Goodput ratio: 77/0][58.79 sec][ALPN: anydesk/6.2.0/linux][bytes ratio: 1.000 (Upload)][IAT c2s/s2c min/avg/max/stddev: 0/0 2023/0 10210/0 3873/0][Pkt Len c2s/s2c min/avg/max/stddev: 66/0 285/0 1514/0 460/0][Risk: ** Missing SNI TLS Extn **** Unidirectional Traffic **][Risk Score: 60][Risk Info: No server to client traffic][TLSv1.2][JA3C: 29b5a018fa5992fe23560c16af0dc9fc][Firefox][Plen Bins: 0,20,20,0,10,0,0,0,0,10,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,10,0,0,0,10,0,0,0,0,0,0,20,0,0]
+	1	TCP 192.168.1.128:48260 -> 195.181.174.176:443 [proto: 91.252/TLS.AnyDesk][IP: 0/Unknown][Encrypted][Confidence: DPI][cat: RemoteAccess/12][27 pkts/7693 bytes -> 0 pkts/0 bytes][Goodput ratio: 77/0][58.79 sec][ALPN: anydesk/6.2.0/linux][bytes ratio: 1.000 (Upload)][IAT c2s/s2c min/avg/max/stddev: 0/0 2023/0 10210/0 3873/0][Pkt Len c2s/s2c min/avg/max/stddev: 66/0 285/0 1514/0 460/0][Risk: ** Missing SNI TLS Extn **** Desktop/File Sharing **** Unidirectional Traffic **][Risk Score: 70][Risk Info: No server to client traffic / Found AnyDesk][TLSv1.2][JA3C: 29b5a018fa5992fe23560c16af0dc9fc][Firefox][Plen Bins: 0,20,20,0,10,0,0,0,0,10,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,10,0,0,0,10,0,0,0,0,0,0,20,0,0]
 	2	TCP 142.250.27.188:5228 -> 10.140.72.24:12654 [VLAN: 308][proto: 91.126/TLS.Google][IP: 126/Google][Encrypted][Confidence: DPI][cat: Web/5][6 pkts/6972 bytes -> 0 pkts/0 bytes][Goodput ratio: 94/0][0.16 sec][bytes ratio: 1.000 (Upload)][IAT c2s/s2c min/avg/max/stddev: 0/0 32/0 160/0 64/0][Pkt Len c2s/s2c min/avg/max/stddev: 78/0 1162/0 1418/0 490/0][Risk: ** Known Proto on Non Std Port **** Unidirectional Traffic **][Risk Score: 60][Risk Info: No client to server traffic][ServerNames: *.google.com,*.appengine.google.com,*.bdn.dev,*.cloud.google.com,*.crowdsource.google.com,*.datacompute.google.com,*.google.ca,*.google.cl,*.google.co.in,*.google.co.jp,*.google.co.uk,*.google.com.ar,*.google.com.au,*.google.com.br,*.google.com.co,*.google.com.mx,*.google.com.tr,*.google.com.vn,*.google.de,*.google.es,*.google.fr,*.google.hu,*.google.it,*.google.nl,*.google.pl,*.google.pt,*.googleadapis.com,*.googleapis.cn,*.googlevideo.com,*.gstatic.cn,*.gstatic-cn.com,googlecnapps.cn,*.googlecnapps.cn,googleapps-cn.com,*.googleapps-cn.com,gkecnapps.cn,*.gkecnapps.cn,googledownloads.cn,*.googledownloads.cn,recaptcha.net.cn,*.recaptcha.net.cn,widevine.cn,*.widevine.cn,ampproject.org.cn,*.ampproject.org.cn,ampproject.net.cn,*.ampproject.net.cn,google-analytics-cn.com,*.google-analytics-cn.com,googleadservices-cn.com,*.googleadservices-cn.com,googlevads-cn.com,*.googlevads-cn.com,googleapis-cn.com,*.googleapis-cn.com,googleoptimize-cn.com,*.googleoptimize-cn.com,doubleclick-cn.net,*.doubleclick-cn.net,*.fls.doubleclick-cn.net,*.g.doubleclick-cn.net,doubleclick.cn,*.doubleclick.cn,*.fls.doubleclick.cn,*.g.doubleclick.cn,dartsearch-cn.net,*.dartsearch-cn.net,googletraveladservices-cn.com,*.googletraveladservices-cn.com,googletagservices-cn.com,*.googletagservices-cn.com,googletagmanager-cn.com,*.googletagmanager-cn.com,googlesyndication-cn.com,*.googlesyndication-cn.com,*.safeframe.googlesyndication-cn.com,app-measurement-cn.com,*.app-measurement-cn.com,gvt1-cn.com,*.gvt1-cn.com,gvt2-cn.com,*.gvt2-cn.com,2mdn-cn.net,*.2mdn-cn.net,googleflights-cn.net,*.googleflights-cn.net,admob-cn.com,*.admob-cn.com,*.gstatic.com,*.metric.gstatic.com,*.gvt1.com,*.gcpcdn.gvt1.com,*.gvt2.com,*.gcp.gvt2.com,*.url.google.com,*.youtube-nocookie.com,*.ytimg.com,android.com,*.android.com,*.flash.android.com,g.cn,*.g.cn,g.co,*.g.co,goo.gl,www.goo.gl,google-analytics.com,*.google-analytics.com,google.com,googlecommerce.com,*.googlecommerce.com,ggpht.cn,*.ggpht.cn,urchin.com,*.urchin.com,youtu.be,youtube.com,*.youtube.com,youtubeeducation.com,*.youtubeeducation.com,youtubekids.com,*.youtubekids.com,yt.be,*.yt.be,android.clients.google.com,developer.android.google.cn,developers.android.google.cn,source.android.google.cn][JA3S: 84aaf6d03fc8c5bfb56d1d188735b268][Issuer: C=US, O=Google Trust Services LLC, CN=GTS CA 1C3][Subject: CN=*.google.com][Certificate SHA-1: 02:64:CA:2E:8A:2F:BB:C4:97:9D:A7:AC:2B:47:FF:DE:28:0E:71:B1][Validity: 2021-11-01 02:19:52 - 2022-01-24 02:19:51][Cipher: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256][Plen Bins: 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,20,0,0,0,0,0,80,0,0,0,0,0]