Receive and send file via netcat tool

nctransfer

#!/bin/bash

# COMMANDS
# 1) Receive a file
# nctransfer r ListenPort ?FileToReceive?
#
# 2) Send a file
# nctransfer s ServerIP ServerPort FileToSend

if [ "$1" == "r" ]; then
# Receive mode

	# Check args number
	if [[ "$#" < 2 ]]; then
		echo "Error: missing parameters"
		echo "$0 r ListenPort ?FileToReceive?"
		exit
	fi

	# Listen Port
	myport="$2"
	
	# File name to transfer
	if [[ "$#" < 3 ]]; then
	# Received by the sender
		myfile="$(nc -vvv -l -p "$myport")"
	else
	# Decided by terminal
		nc -vvv -l -p "$myport" > /dev/null
		myfile="$3"
	fi

	# Netcat waiting file
	nc -vvv -l -p "$myport" > "$myfile"

	# Waiting for md5 hash
	mynchash="$(nc -vvv -l -p "$myport")"

	# Calculate md5 hash of received file
	myhash="$(md5sum "$myfile"|awk '{print $1}')"

	# Compare the md5 hash
	if [ "$mynchash" == "$myhash" ]; then
		echo Transfer completed successfully!
	else
		echo Transfer FAILED!
	fi

elif [ "$1" == "s" ]; then
# Send mode

	# Check args number
	if [[ "$#" < 4 ]]; then
		echo "Error: missing parameters"
		echo "$0 s ServerIP ServerPort FileToSend"
		exit
	fi

	# Server IP
	myip="$2"
	# Server Port
	myport="$3"
	# File to transfer
	myfile="$4"


	# Send the file name
	echo "$myfile" | nc -vvv -q 1 "$myip" "$myport"
	sleep 1

	if [ ! -e "$myfile" ]; then
	# Check if file exists
		echo "Error: $myfile doesn't exist"
		exit
	else
	# Calculate md5 hash of file
		myhash="$(md5sum "$myfile"|awk '{print $1}')"
	fi

	# Send the file
	nc -vvv -q 1 "$myip" "$myport" < "$myfile"
	sleep 1
	# Send the md5 hash
	echo "$myhash" | nc -vvv -q 1 "$myip" "$myport"

else
# Not defined mode
	echo "Error: Choose mode r(eceive) or s(end)"
	echo " - Receive: $0 r Port ?FileToReceive?"
	echo " - Send:    $0 s ServerIP ServerPort FileToSend"
fi