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@load frameworks/communication/listen
@load base/protocols/modbus
module Pasad;
redef Communication::listen_port = 47760/tcp;
redef Communication::listen_ssl = F;
## Global variables
global verbose=T;
## DATA STRUCTURES
export {
redef enum Log::ID += { LOG };
type Transaction: record {
start_address: count;
quantity: count;
};
type TransactionTable: table[count] of Transaction;
type Info: record {
transactions: TransactionTable &default=TransactionTable();
};
type RegisterData: record {
ip: addr &log;
uid: count &log;
regtype: string &log;
address: count &log;
register: count &log;
};
const enable_filtering : bool = F;
const filter_ip_addr : addr = 192.168.211.146;
const filter_mem_addr : count = 64;
}
redef record connection += {
pasad: Info &default=Info();
};
redef Communication::nodes += {
["pasad"] = [$host = 127.0.0.1, $events = /pasad/, $connect=F, $ssl=F]
};
## CUSTOM EVENTS
event pasad_register_received(data: RegisterData) {
Log::write(Pasad::LOG, data);
if(verbose)
print fmt("Received address=%d, register=%d", data$address, data$register);
}
event pasad_unmatched_response(tid: count) {
if(verbose)
print fmt("Unmatched response: tid=%d", tid);
}
## CUSTOM FUNCTIONS
function pasad_check_filter(ip: addr, start_address: count, quantity: count) : bool {
if (!enable_filtering)
return T;
if (ip != filter_ip_addr)
return F;
if (start_address == 0 && quantity == 0)
return T;
if (start_address > filter_mem_addr)
return F;
return filter_mem_addr < start_address + quantity;
}
function pasad_generate_event(transaction: Transaction, c: connection,
headers: ModbusHeaders, registers: ModbusRegisters, regtype: string,
i: count) {
local data = RegisterData(
$ip=c$id$resp_h,
$uid=headers$uid,
$regtype=regtype,
$address=transaction$start_address + i,
$register=registers[i]
);
event pasad_register_received(data);
}
function pasad_generate_events(transaction: Transaction, c: connection,
headers: ModbusHeaders, registers: ModbusRegisters, regtype: string) {
# TODO: check registers size
if (enable_filtering) {
if(verbose)
print fmt("%d %d %d", filter_mem_addr, transaction$start_address, transaction$quantity);
pasad_generate_event(transaction, c, headers, registers, regtype,
filter_mem_addr - transaction$start_address);
} else {
local i = 0;
while (i < transaction$quantity) {
pasad_generate_event(transaction, c, headers, registers, regtype, i);
++i;
}
}
}
## EVENT HANDLERS
event bro_init() &priority=5 {
Log::create_stream(Pasad::LOG, [$columns=RegisterData, $path="pasad-parsed"]);
}
event modbus_read_holding_registers_request(c: connection,
headers: ModbusHeaders, start_address: count, quantity: count) {
if (!pasad_check_filter(c$id$resp_h, start_address, quantity)) {
if(verbose)
print fmt("Filtered %s/%d/%d", c$id$resp_h, start_address, quantity);
return;
}
local tid = headers$tid;
local transaction = Transaction(
$start_address=start_address,
$quantity=quantity
);
c$pasad$transactions[tid] = transaction;
}
event modbus_read_holding_registers_response(c: connection,
headers: ModbusHeaders, registers: ModbusRegisters) {
if (!pasad_check_filter(c$id$resp_h, 0, 0)) {
if(verbose)
print fmt("Filtered %s", c$id$resp_h);
return;
}
local tid = headers$tid;
if (tid !in c$pasad$transactions) {
event pasad_unmatched_response(tid);
return;
}
local transaction = c$pasad$transactions[tid];
delete c$pasad$transactions[tid];
pasad_generate_events(transaction, c, headers, registers, "h");
}
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