NetEBCDICat.py

#!/usr/bin/env python3

#########################################################################
#					 NetEBCDICat										#
#########################################################################
# Script to communicate with netcat on OMVS (z/OS IBM Mainframe UNIX)	#
#																		#
# Requirements: Python, netcat-omvs running on a mainframe				#
# Created by: Soldier of Fortran (@mainframed767)						#
# Usage: This script will listen for or connect to a z/OS OMVS			#
# mainframe netcat session and translate the data from					#
# ASCII to EBCDIC and back												#
# Updates: 2024-03-22 BeS												#
#  - Porting to python3													#
#  - removing logo graphics												#
#  - fixing bytes v. string handling									#
#																		#
# Copyright GPL 2012													#
#########################################################################
###
# # Lots of help from http://4thmouse.com/index.php/2008/02/22/netcat-clone-in-three-languages-part-ii-python/
###


from select import select
import socket
import signal
import sys
import argparse #needed for argument parsing


#EBCDIC/ASCII converter, customize by me for use here
# from http://www.pha.com.au/kb/index.php/Ebcdic.py
a2e = [
			0,	1,	2,	3, 55, 45, 46, 47, 22,	5, 21, 11, 12, 13, 14, 15,
		 16, 17, 18, 19, 60, 61, 50, 38, 24, 25, 63, 39, 28, 29, 30, 31,
		 64, 79,127,123, 91,108, 80,125, 77, 93, 92, 78,107, 96, 75, 97,
		240,241,242,243,244,245,246,247,248,249,122, 94, 76,126,110,111,
		124,193,194,195,196,197,198,199,200,201,209,210,211,212,213,214,
		215,216,217,226,227,228,229,230,231,232,233, 74,224, 90, 95,109,
		121,129,130,131,132,133,134,135,136,137,145,146,147,148,149,150,
		151,152,153,162,163,164,165,166,167,168,169,192,106,208,161,	7,
		 32, 33, 34, 35, 36, 21,	6, 23, 40, 41, 42, 43, 44,	9, 10, 27,
		 48, 49, 26, 51, 52, 53, 54,	8, 56, 57, 58, 59,	4, 20, 62,225,
		 65, 66, 67, 68, 69, 70, 71, 72, 73, 81, 82, 83, 84, 85, 86, 87,
		 88, 89, 98, 99,100,101,102,103,104,105,112,113,114,115,116,117,
		118,119,120,128,138,139,140,141,142,143,144,154,155,156,157,158,
		159,160,170,171,172,173,174,175,176,177,178,179,180,181,182,183,
		184,185,186,187,188,189,190,191,202,203,204,205,206,207,218,219,
		220,221,222,223,234,235,236,237,238,239,250,251,252,253,254,255
		]

e2a = [
			0,	1,	2,	3,156,	9,134,127,151,141, 11, 11, 12, 13, 14, 15,
		 16, 17, 18, 19,157, 10,	8,135, 24, 25,146,143, 28, 29, 30, 31,
		128,129,130,131,132, 10, 23, 27,136,137,138,139,140,	5,	6,	7,
		144,145, 22,147,148,149,150,	4,152,153,154,155, 20, 21,158, 26,
		 32,160,161,162,163,164,165,166,167,168, 91, 46, 60, 40, 43, 33,
		 38,169,170,171,172,173,174,175,176,177, 93, 36, 42, 41, 59, 94,
		 45, 47,178,179,180,181,182,183,184,185,124, 44, 37, 95, 62, 63,
		186,187,188,189,190,191,192,193,194, 96, 58, 35, 64, 39, 61, 34,
		195, 97, 98, 99,100,101,102,103,104,105,196,197,198,199,200,201,
		202,106,107,108,109,110,111,112,113,114,203,204,205,206,207,208,
		209,126,115,116,117,118,119,120,121,122,210,211,212,213,214,215,
		216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,
		123, 65, 66, 67, 68, 69, 70, 71, 72, 73,232,233,234,235,236,237,
		125, 74, 75, 76, 77, 78, 79, 80, 81, 82,238,239,240,241,242,243,
		 92,159, 83, 84, 85, 86, 87, 88, 89, 90,244,245,246,247,248,249,
		 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,250,251,252,253,254,255
]

def AsciiToEbcdic(s):
# input is string, output bytes
		if len(s) == 0:
			return s

		new = bytearray()
		for i in range(len(s)):
			if type(s) == str:
				s = bytes(s.encode())
			new.append(a2e[s[i]])
		
		return bytes(new)

def EbcdicToAscii(s):
# intput is bytes, output string
		if len(s) == 0:  
			return s
		
		new = bytearray()
		for i in range(len(s)):
			if type(s) == str:
				s = bytes(s.encode())
			new.append(e2a[s[i]])
		
		new=bytes(new).decode('ascii')
		return new

# Nice colors for us to use
class bcolors:
		HEADER = '\033[95m'
		BLUE = '\033[94m'
		GREEN = '\033[92m'
		YELLOW = '\033[93m'
		RED = '\033[91m'
		ENDC = '\033[0m'

		def disable(self):
			self.HEADER = ''
			self.BLUE = ''
			self.GREEN = ''
			self.YELLOW = ''
			self.RED = ''
			self.ENDC = ''

# catch the ctrl-c to exit
def signal_handler(signal, frame):
	print('\nCTRL+C entered. Disconnecting!')
	sys.exit(0)

signal.signal(signal.SIGINT, signal_handler)
#################################################################

def main():
	#start argument parser
	parser = argparse.ArgumentParser(description='Script to communicate with netcat on OMVS (z/OS IBM Mainframe UNIX)',epilog="Translates ASCII <-> EBCDIC")
	parser.add_argument('-l','--listen',help='listen for incomming connections', default=False,dest='server',action='store_true')
	parser.add_argument('-i','--ip', help='remote host IP address',dest='ip')
	parser.add_argument('-p','--port', help='Port to listen on or to connect to',required=True,dest='port')
	args = parser.parse_args()
	results = parser.parse_args() # put the arg results in the variable results

	if not results.server:
		try:
			MFsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
			MFsock.connect( (results.ip, int(results.port)) )
		except Exception as e:
			print(bcolors.RED + "[ERR] could not connect to ",results.ip,":",results.port,"" + bcolors.ENDC)
			sys.exit(0)

	else:
		# if results.ip != "":
		# 	print(bcolors.YELLOW + "[WARN] You defined IP address", results.ip, "but have selected listening mode. Please choose one or the other. Exiting." + bcolors.ENDC)
		# 	sys.exit(-1)
		try:
			server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
			server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
			if(results.ip != None):
				server.bind((results.ip, int(results.port))) 
			else:
				server.bind((socket.gethostname(), int(results.port))) 
			server.listen(1)
			MFsock, address = server.accept()
		except Exception as e:
			print(bcolors.RED + "[ERR] could not open server on port:", results.port,"" + bcolors.ENDC)
			#print(bcolors.RED + "",e,"" + bcolors.ENDC)
			sys.exit(0)

	MFsock.setblocking(0)
	while(1):
		r, w, e = select(
			[MFsock, sys.stdin], 
			[], 
			[MFsock, sys.stdin])
		try:
			buffer = MFsock.recv(128)
			while( buffer  != b''):
				ascii_out = EbcdicToAscii(buffer)
				print(ascii_out,end='')
				buffer = MFsock.recv(128)
				if(buffer == b''):
					break;
		except socket.error:
			pass
		
		while(1):
			r, w, e = select([sys.stdin],[],[],0)
			if(len(r) == 0):
				break;
			c = input()
			if(c == ''):
				#print("$ ",end="")
				break;
			c += "\n"
			command = AsciiToEbcdic(c)
			if(MFsock.sendall(command) != None):
				break;

if __name__ == "__main__":
	main()