#!/usr/bin/ksh93

#

# sshnfs - remote login client with NFSv4 forwarding

#

# Example usage:

# $ ksh sshnfs.ksh -o NFSURL=nfs://localhost/export/home/rmainz root@10.49.20.207 #

# $ ksh sshnfs.ksh -o NFSURL=nfs://localhost/export/home/rmainz -o NFSJumphost=derfwpc5131 root@10.49.20.207

#

# Written by Roland Mainz <roland.mainz@nrubsig.org>

#

#

# parse url

#

# returns:

# data.protocol

# data.host

# data.port (optional)

# data.path

#

function parse_url

{

	typeset url="$2"

	typeset leftover

	nameref data="$1"

	# ~(E) is POSIX extended regular expression matching (instead of

	# shell pattern)

	leftover="${url//~(Elr)(.+?):\/\/(.+?)(?:|:([[:digit:]]+))(?:\/(.*?))?/x}"

	# All parsed data should be captured via eregex in .sh.match - if

	# there is anything left then the input string did not properly match

	# the eregex

	[[ "$leftover" == 'x' ]] || { print -u2 -f $"%s: Parser error\n" "$0" ; return 1 ; }

	data.protocol="${.sh.match[1]}"

	data.host="${.sh.match[2]}"

	# bug: should be [[ -v .sh.match[3] }}, but ksh93u has bugs

	[[ "${.sh.match[3]}" != '' ]] && integer data.port="${.sh.match[3]}"

	data.path="${.sh.match[4]}"

	return 0

}

function parse_nfs_url

{

	typeset url="$2"

	nameref data="$1"

	parse_url data "$url" || return 1

	[[ "${data.protocol}" == 'nfs' ]]	|| { print -u2 -f $"%s: Not a NFS url\n" "$0" ; return 1 ; }

	[[ "${data.host}" != '' ]]		|| { print -u2 -f $"%s: NFS hostname missing\n" "$0" ; return 1 ; }

	[[ "${data.path}" != '' ]]		|| { print -u2 -f $"%s: NFS path missing\n" "$0" ; return 1 ; }

	if [[ ! -v data.port ]] ; then

		integer data.port=2049

	fi

	return 0

}

function main

{

	integer i

	compound c

	compound c.nfs_data

	integer c.forward_port=34049

	integer retval

	#set -o xtrace

	set -o nounset

	typeset c.args=( "$@" )

	for ((i=0 ; i < ${#c.args[@]} ; i++)) ; do

		if [[ "${c.args[i]}" == '-o' ]] ; then

			case "${c.args[i+1]-}" in

				'NFSURL='*)

					unset c.nfs_data

					typeset c.url="${c.args[i+1]#NFSURL=}"

					parse_nfs_url c.nfs_data "${c.url}" || return 1

					unset c.args[$i] c.args[$((i+1))]

					((i++))

					;;

				'NFSJumphost='*)

					[[ ! -v c.ssh_jumphost_args ]] && typeset -a c.ssh_jumphost_args

					c.ssh_jumphost_args+=( "-J" "${c.args[i+1]#NFSJumphost=}" )

					unset c.args[$i] c.args[$((i+1))]

					((i++))

					;;

			esac

		fi

	done

	# bug: should be [[ -v c.nfs_data ]], but ksh93u has bugs

	if [[ -v c.nfs_data.host ]] ; then

		# Forward NFS port from server to local machine

		# Notes:

		# - We use $ ssh -M ... # here as a way to terminate the port

		# forwarding process later using "-O exit" without the need

		# for a pid

		printf $"# Please enter the password for NFS server (%s)\n" \

			"root@${c.nfs_data.host}"

		ssh \

			-L "${c.forward_port}:localhost:${c.nfs_data.port}" \

			-M -S "$PWD/ssh-control-socket" \

			-N \

			-f -o ExitOnForwardFailure=yes \

			"${c.ssh_jumphost_args[@]}" \

			"root@${c.nfs_data.host}"

		if (( $? != 0 )) ; then

			printf $"%s: NFS forwarding ssh failed with error code %d\n" "$0" $?

			return 1

		fi

		#ssh -S "$PWD/ssh-control-socket" -O 'check' "root@${c.nfs_data.host}"

		printf $"# Use this to mount the directory:\n"

		printf $"# $ mkdir /mnt_nfs\n"

			33049 \

			"${c.nfs_data.path}"

		# add NFS forwarding options to main ssh argument list

		c.args=( "-R" "33049:localhost:${c.forward_port}" "${c.args[@]}" )

	fi

	ssh "${c.args[@]}" ; (( retval=$? ))

	if [[ -v c.nfs_data.host ]] ; then

		ssh -S "$PWD/ssh-control-socket" -O 'exit' "root@${c.nfs_data.host}"

	fi

	wait

	return $retval

}

main "$@"

# EOF.