MINOR: sample: Add converts to parses MQTT messages
This patch implements a couple of converters to validate and extract data from a
MQTT (Message Queuing Telemetry Transport) message. The validation consists of a
few checks as well as "packet size" validation. The extraction can get any field
from the variable header and the payload.
This is limited to CONNECT and CONNACK packet types only. All other messages are
considered as invalid. It is not a problem for now because only the first packet
on each side can be parsed (CONNECT for the client and CONNACK for the server).
MQTT 3.1.1 and 5.0 are supported.
Reviewed and Fixed by Christopher Faulet <cfaulet@haproxy.com>
diff --git a/doc/configuration.txt b/doc/configuration.txt
index a7dc4b6..a970711 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -15410,6 +15410,93 @@
This prefix is followed by a name. The separator is a '.'. The name may only
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
+mqtt_field_value(<packettype>,<fieldname or property ID>)
+ Returns value of <fieldname> found in input MQTT payload of type
+ <packettype>.
+ <packettype> can be either a string (case insensitive matching) or a numeric
+ value corresponding to the type of packet we're supposed to extract data
+ from.
+ Supported string and integers can be found here:
+ https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718021
+ https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901022
+
+ <fieldname> depends on <packettype> and can be any of the following below.
+ (note that <fieldname> matching is case insensitive).
+ <property id> can only be found in MQTT v5.0 streams. check this table:
+ https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901029
+
+ - CONNECT (or 1): flags, protocol_name, protocol_version, client_identifier,
+ will_topic, will_payload, username, password, keepalive
+ OR any property ID as a numeric value (for MQTT v5.0
+ packets only):
+ 17: Session Expiry Interval
+ 33: Receive Maximum
+ 39: Maximum Packet Size
+ 34: Topic Alias Maximum
+ 25: Request Response Information
+ 23: Request Problem Information
+ 21: Authentication Method
+ 22: Authentication Data
+ 18: Will Delay Interval
+ 1: Payload Format Indicator
+ 2: Message Expiry Interval
+ 3: Content Type
+ 8: Response Topic
+ 9: Correlation Data
+ Not supported yet:
+ 38: User Property
+
+ - CONNACK (or 2): flags, protocol_version, reason_code
+ OR any property ID as a numeric value (for MQTT v5.0
+ packets only):
+ 17: Session Expiry Interval
+ 33: Receive Maximum
+ 36: Maximum QoS
+ 37: Retain Available
+ 39: Maximum Packet Size
+ 18: Assigned Client Identifier
+ 34: Topic Alias Maximum
+ 31: Reason String
+ 40; Wildcard Subscription Available
+ 41: Subscription Identifiers Available
+ 42: Shared Subscription Available
+ 19: Server Keep Alive
+ 26: Response Information
+ 28: Server Reference
+ 21: Authentication Method
+ 22: Authentication Data
+ Not supported yet:
+ 38: User Property
+
+ Due to current HAProxy design, only the first message sent by the client and
+ the server can be parsed. Thus this converter can extract data only from
+ CONNECT and CONNACK packet types. CONNECT is the first message sent by the
+ client and CONNACK is the first response sent by the server.
+
+ Example:
+
+ acl data_in_buffer req.len ge 4
+ tcp-request content set-var(txn.username) \
+ req.payload(0,0),mqtt_field_value(connect,protocol_name) \
+ if data_in_buffer
+ # do the same as above
+ tcp-request content set-var(txn.username) \
+ req.payload(0,0),mqtt_field_value(1,protocol_name) \
+ if data_in_buffer
+
+mqtt_is_valid
+ Checks that the binary input is a valid MQTT packet. It returns a boolean.
+
+ Due to current HAProxy design, only the first message sent by the client and
+ the server can be parsed. Thus this converter can extract data only from
+ CONNECT and CONNACK packet types. CONNECT is the first message sent by the
+ client and CONNACK is the first response sent by the server.
+
+ Example:
+
+ acl data_in_buffer req.len ge 4
+ tcp-request content reject unless req.payload(0,0),mqtt_is_valid
+
mul(<value>)
Multiplies the input value of type signed integer by <value>, and returns
the product as an signed integer. In case of overflow, the largest possible