mqtt: test mqtt frames for truncated messages

tests/mqtt-frames-truncated/README.md

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+Description
+===========
+Test MQTT frames[Pdu, Header, Data] for truncated messages where msg_len > max_msg_size.
+
+PCAP
+====
+PCAP was shared by Sascha Steinbiss and was generated by setting up a Mosquitto server and recording communication between `mosquitto_sub` client and `local_broker` via a script.
+
+Redmine ticket
+==============
+https://redmine.openinfosecfoundation.org/issues/5731

tests/mqtt-frames-truncated/suricata.yaml

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+%YAML 1.1
+---
+
+outputs:
+  - eve-log:
+      enabled: yes
+      filetype: regular
+      filename: eve.json
+      types:
+        - mqtt
+        - alert
+        - frame
+
+app-layer:
+  protocols:
+    mqtt:
+      enabled: yes
+      max-msg-length: 60

tests/mqtt-frames-truncated/test.rules

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+alert mqtt any any -> any any (msg:"mqtt Frame 1"; frame:pdu; content:"|10 1c|"; startswith; sid:1;)
+alert mqtt any any -> any any (msg:"mqtt Frame 2"; frame:pdu; content:"|14|"; endswith; sid:2;)
+
+alert mqtt any any -> any any (msg:"mqtt Frame 3"; frame:header; content:"|10|"; sid:3;)
+alert mqtt any any -> any any (msg:"mqtt Frame 4"; frame:header; content:"|10 1c|"; sid:4;)
+
+alert mqtt any any -> any any (msg:"mqtt Frame 5"; frame:pdu; content:"|17 0C E2|"; sid:5;)
+alert mqtt any any -> any any (msg:"mqtt Frame 6"; frame:pdu; content:"|00 00 54 46|"; sid:6;)
+
+# pre-boundary test for truncated data
+alert mqtt any any -> any any (msg:"mqtt Frame 7"; frame:data; content:"|0a|"; sid:7;)
+
+# At boundary test for truncated data
+alert mqtt any any -> any any (msg:"mqtt Frame 8"; frame:data; content:"|00 04 4d 51 54 54 05|"; sid:8;)
+
+# post-boundary test for truncated data
+alert mqtt any any -> any any (msg:"mqtt Frame 9"; frame:data; content:"|c1 90 34|"; sid:9;)

tests/mqtt-frames-truncated/test.yaml

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+requires:
+  min-version: 7
+
+args:
+ - -k none
+
+checks:
+- filter:
+    count: 1
+    match:
+      alert.signature_id: 1
+      frame.type: "pdu"
+- filter:
+    count: 1
+    match:
+      alert.signature_id: 2
+      frame.type: "pdu"
+      frame.complete: true
+- filter:
+    count: 1
+    match:
+      alert.signature_id: 3
+      frame.type: "header"
+      frame.complete: true
+- filter:
+    count: 1
+    match:
+      alert.signature_id: 4
+      frame.type: "header"
+      frame.length: 2
+      frame.complete: true
+- filter:
+    count: 0
+    match:
+      alert.signature_id: 5
+- filter:
+    count: 0
+    match:
+      alert.signature_id: 6
+- filter:
+    count: 1
+    match:
+      alert.signature_id: 7
+- filter:
+    count: 1
+    match:
+      alert.signature_id: 8
+- filter:
+    count: 0
+    match:
+      alert.signature_id: 9