FEAT: simple TCP port scanner (module)

related to: Oldes/Rebol-issues#1422

Author: Oldes

src/modules/port-scanner.reb

@@ -0,0 +1,100 @@
+Rebol [
+	Title:   "TCP Port scanner"
+	File:    %port-scanner.reb
+	Type:    module
+	Name:    port-scanner
+	Version: 1.0.0
+	Date:    16-Feb-2021
+	Exports: [scan-ports]
+	Note: {
+		If you use anything other than `localhost` you had better have permission
+		for the host name you do use, or you will suddenly be an *internet bad guy*.
+		Don't.}
+]
+
+; result:
+found: copy []
+
+; options:
+batch-size: 8000 ; higher batch size means higher CPU use!
+timeout: 0:0:0.5 ; setting timeout too low may result in not resolved opened ports!
+
+; actor:
+on-awake: func [event /local port id] [
+	port: event/port
+	;print [as-green "==TCP-event:" as-red event/type "port:" as-red port/spec/port-id]
+	switch/default event/type [
+		lookup  [open port]
+		connect [
+			id: port/spec/port-id
+			print ["Open port found:" as-red id]
+			append found id
+			false
+		]
+	][true]
+]
+
+scan-ports: function [
+	from [integer!] "lowest port numer"
+	to   [integer!] "max port number"
+	/host name [tuple! string!]
+][
+	clear found
+	checking: make block! batch-size
+	started: now/time/precise
+
+	if to < from [id: to to: from from: id]
+
+	id: low: 
+	from: max 1 from
+	to:   max 1 min to 65535
+
+	total: 1 + to - from
+
+	try/except [
+		ip: either tuple? name [ name ][
+			read join dns:// any [name 'localhost]
+		]
+	][
+		sys/log/error 'REBOL system/state/last-error
+		return none
+	]
+
+	print [
+		as-green "Using IP:"   as-yellow ip
+		as-green "timeout:"    as-yellow timeout
+		as-green "batch size:" as-yellow batch-size
+		newline
+	]
+
+	while [id <= to][
+		port: make port! compose [
+			scheme:  'tcp
+			host:    (ip)
+			port-id: (id)
+			awake:   :on-awake
+		]
+		open port
+		append checking port
+		if any [
+			id = to
+			batch-size = length? checking
+		][
+			print [as-green "Checking range:" as-yellow low "-" as-yellow id]
+			; wait some time...
+			wait timeout
+			; and check what was opened...
+			foreach port checking [ close port ]
+			clear checking
+			if id < to [ low: low + batch-size ]
+		]
+		++ id
+	]
+	checking: none
+	print ajoin [
+		as-green "^/Scan of " as-yellow total
+		as-green " ports finished in time: " as-yellow now/time/precise - started
+		as-green ".^/Found " as-red length? found as-green " listening TCP ports!^/"
+	]
+	found
+]

src/tests/test-port-scanner.r3

@@ -0,0 +1,21 @@
+Rebol [
+	Title: "Test async TCP port scanner"
+	File:  %test-port-scanner.r3
+	Date: 16-Feb-2021
+]
+
+scanner: import 'port-scanner
+	
+;- higher batch size means higher CPU use!
+;scanner/batch-size: 10000
+;- low timeout may result in not founding all listening ports!
+;- if the scenner is used on non local ip, the timeout should
+;- count with netword latency!
+;scanner/timeout: 0:0:0.25
+
+scan-ports/host 1 65535 127.0.0.1
+
+if system/options/script [
+	?? scanner/found
+	ask "^/DONE"
+]