# This file is part of bish-bosh. It is subject to the licence terms in the COPYRIGHT file found in the top-level directory of this distribution and at https://raw.githubusercontent.com/raphaelcohn/bish-bosh/master/COPYRIGHT. No part of bish-bosh, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the COPYRIGHT file.
# Copyright © 2014-2015 The developers of bish-bosh. See the COPYRIGHT file in the top-level directory of this distribution and at https://raw.githubusercontent.com/raphaelcohn/bish-bosh/master/COPYRIGHT.


core_usesIn bishbosh/connection write

bishbosh_connection_clientId_validateAndDefault()
{
	if core_variable_isSet bishbosh_clientId; then
		bishbosh_connection_validate_clientId
		return 0
	fi
	
	if core_variable_isUnset bishbosh_connect_cleanSession; then
		core_exitError $core_commandLine_exitCode_CONFIG "Clean Session is 0 and the option -i,--client-id or configuration setting bishbosh_clientId isn't set, either in configuration, SCRIPTLETS or any path under '$bishbosh_clientPath'."
	else
		core_validate_isBoolean $core_commandLine_exitCode_CONFIG 'configuration setting' bishbosh_connect_cleanSession "$bishbosh_connect_cleanSession"
		if core_variable_isFalse "$bishbosh_connect_cleanSession"; then
			core_exitError $core_commandLine_exitCode_CONFIG "Clean Session is 0 and the option -i,--client-id or configuration setting bishbosh_clientId isn't set, either in configuration, SCRIPTLETS or any path under '$bishbosh_clientPath'."
		fi
	fi
	
	if core_variable_isTrue bishbosh_randomClientId; then
		bishbosh_connection_clientId_random
	else
		core_message WARN "Clean Session is 1 and the client id is unset; defaulting to empty (''). This may be rejected by some MQTT servers."
		bishbosh_clientId=''
	fi
}

core_dependency_oneOf '*' openssl gpg base64 dd tr awk

bishbosh_connection_clientId_random()
{
	local potentialClientId
	local reducedClientId
	while true
	do
		potentialClientId="$(bishbosh_connection_clientId_randomBytesBase64EncodedALike 16)"
		reducedClientId="$(bishbosh_connection_validate_removeCharacters '+/' "$potentialClientId")"
		
		if [ ${#reducedClientId} = ${#potentialClientId}]; then
			bishbosh_clientId="$potentialClientId"
			return 0
		fi
	done
}

# Broken out because it might be possible to use a different technique
bishbosh_connection_clientId_randomBytesBase64EncodedALike_base64tr()
{
	# GNU base64 inserts line breaks, hence the use of tr -d '\n'.
	# This can be disabled in GNU base64, but the switches with Mac OS X base64 differ.
	base64 | tr -d '\n='
}

bishbosh_connection_clientId_randomBytesBase64EncodedALike()
{
	local count=$1

	# We use base64.
	# base85 / Ascii85 encoding would be more efficient but support is uncommon and requires non-MQTT safe characters
	
	if core_compatibility_whichNoOutput openssl; then
		openssl -base64 $count
		return 0
	fi
	
	if core_compatibility_whichNoOutput gpg; then
		gpg --armor --gen-random 1 $count
		return 0
	fi
	
	if core_compatibility_whichNoOutput base64; then
		if core_compatibility_whichNoOutput tr; then
			
			local randomFilePath
			for randomFilePath in /dev/urandom /dev/random
			do
				if [ -r "$randomFilePath" ]; then
					if core_compatibility_whichNoOutput dd; then
						dd bs=1 count=$count if="$randomFilePath" | bishbosh_connection_clientId_randomBytesBase64EncodedALike_base64tr
						return 0
					fi
					if core_compatibility_whichNoOutput head; then
						head -c $count | bishbosh_connection_clientId_randomBytesBase64EncodedALike_base64tr
						return 0
					fi
				fi
			done

			if core_variable_isSet RANDOM; then
				{
					local index
					while [ $index -lt $count ]
					do
						printf "\\$(printf '%o' $((RANDOM%256)))"
						index=$((index+1))
					done
				} | bishbosh_connection_clientId_randomBytesBase64EncodedALike_base64tr
				return 0
			fi
	
			if core_compatibility_whichNoOutput awk; then
				{
					local index
					while [ $index -lt $count ]
					do
						printf "\\$(printf '%o' $(echo | awk -v ORS='' '{ srand(); print int((rand()*1000000)%256)} '))"
						index=$((index+1))
					done
				} | bishbosh_connection_clientId_randomBytesBase64EncodedALike_base64tr
				return 0
			fi
			
		fi
	fi
	
	core_message WARN "Clean Session is 1, the client id is unset and there are not sources of randomness; defaulting to empty (''). This may be rejected by some MQTT servers."
	bishbosh_clientId=''
}