zeek/scripts/base/protocols/dnp3/main.zeek
Benjamin Bannier d5fd29edcd Prefer explicit construction to coercion in record initialization
While we support initializing records via coercion from an expression
list, e.g.,

    local x: X = [$x1=1, $x2=2];

this can sometimes obscure the code to readers, e.g., when assigning to
value declared and typed elsewhere. The language runtime has a similar
overhead since instead of just constructing a known type it needs to
check at runtime that the coercion from the expression list is valid;
this can be slower than just writing the readible code in the first
place, see #4559.

With this patch we use explicit construction, e.g.,

    local x = X($x1=1, $x2=2);
2025-07-11 16:28:37 -07:00

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##! A very basic DNP3 analysis script that just logs requests and replies.
@load ./consts
@load base/protocols/conn/removal-hooks
module DNP3;
export {
redef enum Log::ID += { LOG };
global log_policy: Log::PolicyHook;
type Info: record {
## Time of the request.
ts: time &log;
## Unique identifier for the connection.
uid: string &log;
## Identifier for the connection.
id: conn_id &log;
## The name of the function message in the request.
fc_request: string &log &optional;
## The name of the function message in the reply.
fc_reply: string &log &optional;
## The response's "internal indication number".
iin: count &log &optional;
};
## Event that can be handled to access the DNP3 record as it is sent on
## to the logging framework.
global log_dnp3: event(rec: Info);
## DNP3 finalization hook. Remaining DNP3 info may get logged when it's called.
global finalize_dnp3: Conn::RemovalHook;
}
redef record connection += {
dnp3: Info &optional;
};
const ports = { 20000/tcp , 20000/udp };
redef likely_server_ports += { ports };
event zeek_init() &priority=5
{
Log::create_stream(DNP3::LOG, Log::Stream($columns=Info, $ev=log_dnp3, $path="dnp3", $policy=log_policy));
Analyzer::register_for_ports(Analyzer::ANALYZER_DNP3_TCP, ports);
}
event dnp3_application_request_header(c: connection, is_orig: bool, application_control: count, fc: count)
{
if ( ! c?$dnp3 )
{
c$dnp3 = Info($ts=network_time(), $uid=c$uid, $id=c$id);
Conn::register_removal_hook(c, finalize_dnp3);
}
c$dnp3$ts = network_time();
c$dnp3$fc_request = function_codes[fc];
}
event dnp3_application_response_header(c: connection, is_orig: bool, application_control: count, fc: count, iin: count)
{
if ( ! c?$dnp3 )
{
c$dnp3 = Info($ts=network_time(), $uid=c$uid, $id=c$id);
Conn::register_removal_hook(c, finalize_dnp3);
}
c$dnp3$ts = network_time();
c$dnp3$fc_reply = function_codes[fc];
c$dnp3$iin = iin;
Log::write(LOG, c$dnp3);
delete c$dnp3;
}
hook finalize_dnp3(c: connection)
{
if ( ! c?$dnp3 )
return;
Log::write(LOG, c$dnp3);
delete c$dnp3;
}