Introduce a new function parse_hn_line() that replaces the existing

hostname.if(5) parsing code in ifstart().
Add a -n option to netstart to only print the interface configuration
commands instead of executing them.
Add a HN_DIR variable, that points to the directory of the hostname.if
files (default /etc) that allows for future regression tests.
- add new parse_hn_line() function
- change ifstart()
- rename $if to $_if
- don't ifconfig or ifconfig create if -n option is used
- replace hostname.if(5) parsing code with new parse_hn_line()
- just print configuration commands if -n option is used
- autoconf now happens in ifstart(), remove ifv6autoconf()
- introduce HN_DIR variable for the hostname.if file location
- add handling of the -n option to only print config commands
- ensure -n is only used if interfaces are specified as parameters
Discussed with and positive feedback from many
'commit' deraadt@
OK sthen@

src/etc/netstart

@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$OpenBSD: netstart,v 1.176 2017/04/08 08:33:05 rpe Exp $
+#	$OpenBSD: netstart,v 1.177 2017/04/24 20:31:48 rpe Exp $
 
 # Turn off Strict Bourne shell mode.
 set +o sh
@@ -19,21 +19,80 @@ stripcom() {
 	done <$_file
 }
 
+# Parse and "unpack" a hostname.if(5) line given as positional parameters.
+# Fill the _cmds array with the resulting interface configuration commands.
+parse_hn_line() {
+	local _af=0 _name=1 _mask=2 _bc=3 _prefix=2 _c _cmd _prev _daddr
+	set -A _c -- "$@"
+	set -o noglob
+
+	case ${_c[_af]} in
+	''|*([[:blank:]])'#'*)
+		return
+		;;
+	inet)	((${#_c[*]} > 1)) || return
+		[[ ${_c[_name]} == alias ]] && _mask=3 _bc=4
+		[[ -n ${_c[_mask]} ]] && _c[_mask]="netmask ${_c[_mask]}"
+		if [[ -n ${_c[_bc]} ]]; then
+			_c[_bc]="broadcast ${_c[_bc]}"
+			[[ ${_c[_bc]} == *NONE ]] && _c[_bc]=
+		fi
+		_cmds[${#_cmds[*]}]="ifconfig $_if ${_c[@]}"
+		;;
+	inet6)	((${#_c[*]} > 1)) || return
+		if [[ ${_c[_name]} == autoconf ]]; then
+			_cmds[${#_cmds[*]}]="ifconfig $_if ${_c[@]}"
+			rtsolif="$rtsolif $_if"
+			return
+		fi
+		[[ ${_c[_name]} == alias ]] && _prefix=3
+		[[ -n ${_c[_prefix]} ]] && _c[_prefix]="prefixlen ${_c[_prefix]}"
+		_cmds[${#_cmds[*]}]="ifconfig $_if ${_c[@]}"
+		;;
+	dest)	((${#_c[*]} == 2)) && _daddr=${_c[1]} || return
+		_prev=$((${#_cmds[*]} - 1))
+		((_prev >= 0)) || return
+		set -A _c -- ${_cmds[_prev]}
+		_name=3
+		[[ ${_c[_name]} == alias ]] && _name=4
+		_c[_name]="${_c[_name]} $_daddr"
+		_cmds[$_prev]="${_c[@]}"
+		;;
+	dhcp)	_c[0]=
+		_cmds[${#_cmds[*]}]="ifconfig $_if ${_c[@]} down;dhclient $_if"
+		dhcpif="$dhcpif $_if"
+		;;
+	rtsol)	# XXX Support the rtsol keyword for some time to enable a smooth
+		# XXX transition to autoconf.
+		_c[0]=
+		_cmds[${#_cmds[*]}]="ifconfig $_if ${_c[@]} up"
+		_cmds[${#_cmds[*]}]="ifconfig $_if inet6 autoconf"
+		rtsolif="$rtsolif $_if"
+		;;
+	'!'*)	_cmd=$(print -- "${_c[@]}" | sed 's/\$if/'$_if'/g')
+		_cmds[${#_cmds[*]}]="${_cmd#!}"
+		;;
+	*)	_cmds[${#_cmds[*]}]="ifconfig $_if ${_c[@]}"
+		;;
+	esac
+	unset _c
+}
+
 # Start a single interface.
 # Usage: ifstart if1
 ifstart() {
-	# Note: Do not rename the 'if' variable which is documented as being
-	# usable in hostname.if(5) files.
-	local if=$1 _file=/etc/hostname.$1 _stat
+	local _if=$1 _file=$HN_DIR/hostname.$1 _cmds _i=0 _line _stat
+	set -A _cmds
 
 	# Interface names must be alphanumeric only.  We check to avoid
 	# configuring backup or temp files, and to catch the "*" case.
-	[[ $if != +([[:alpha:]])+([[:digit:]]) ]] && return
+	[[ $_if != +([[:alpha:]])+([[:digit:]]) ]] && return
 
 	if [[ ! -f $_file ]]; then
 		echo "netstart: $_file: No such file or directory"
 		return
 	fi
+
 	# Not using stat(1), we can't rely on having /usr yet.
 	set -A _stat -- $(ls -nL $_file)
 	if [ "${_stat[0]#???????} ${_stat[2]} ${_stat[3]}" != "--- 0 0" ]; then
@@ -41,97 +100,30 @@ ifstart() {
 		chmod -LR o-rwx $_file
 		chown -LR root.wheel $_file
 	fi
-	# Check for ifconfig'able interface.
-	(ifconfig $if || ifconfig $if create) >/dev/null 2>&1 || return
-
-	# Now parse the hostname.* file.
-	while :; do
-		if [ "$cmd2" ]; then
-			# We are carrying over from the 'read dt dtaddr'
-			# last time.
-			set -- $cmd2
-			af=$1 name=$2 mask=$3 bcaddr=$4 ext1=$5 cmd2=
-			# Make sure and get any remaining args in ext2,
-			# like the read below.
-			i=1
-			while [ $i -lt 6 -a -n "$1" ]; do shift; let i=i+1; done
-			ext2="$@"
+
+	# Check for ifconfig'able interface, except if -n option is specified.
+	if ! $PRINT_ONLY; then
+		(ifconfig $_if || ifconfig $_if create) >/dev/null 2>&1 ||
+		return
+	fi
+
+	# Parse the hostname.if(5) file and fill _cmds array with interface
+	# configuration commands.
+	set -o noglob
+	while IFS= read -- _line; do
+		parse_hn_line $_line
+	done <$_file
+
+	# Apply the interface configuration commands stored in _cmds array.
+	while ((_i < ${#_cmds[*]})); do
+		if $PRINT_ONLY; then
+			print -r -- "${_cmds[_i]}"
 		else
-			# Read the next line or exit the while loop.
-			read af name mask bcaddr ext1 ext2 || break
+			eval "${_cmds[_i]}"
 		fi
-		# $af can be "dhcp", "up", "rtsol", an address family, commands,
-		# or a comment.
-		case "$af" in
-		"#"*|"")
-			# Skip comments and empty lines.
-			continue
-			;;
-		"!"*) # Parse commands.
-			cmd="${af#*!} ${name} ${mask} ${bcaddr} ${ext1} ${ext2}"
-			;;
-		"dhcp")
-			[ "$name" = "NONE" ] && name=
-			[ "$mask" = "NONE" ] && mask=
-			[ "$bcaddr" = "NONE" ] && bcaddr=
-			cmd="ifconfig $if $name $mask $bcaddr $ext1 $ext2 down"
-			cmd="$cmd;dhclient $if"
-			dhcpif="$dhcpif $if"
-			;;
-		"rtsol")
-			rtsolif="$rtsolif $if"
-			cmd="ifconfig $if $name $mask $bcaddr $ext1 $ext2 up"
-			;;
-		*)
-			read dt dtaddr
-			if [ "$name" = "alias" ]; then
-				# Perform a 'shift' of sorts.
-				alias=$name
-				name=$mask
-				mask=$bcaddr
-				bcaddr=$ext1
-				ext1=$ext2
-				ext2=
-			else
-				alias=
-			fi
-			cmd="ifconfig $if $af $alias $name"
-			case "$dt" in
-			dest)
-				cmd="$cmd $dtaddr"
-				;;
-			*)
-				cmd2="$dt $dtaddr"
-				;;
-			esac
-			case $af in
-			inet)
-				if [ ! -n "$name" ]; then
-					echo "/etc/hostname.$if: inet alone is invalid"
-					return
-				fi
-				[ "$mask" ] && cmd="$cmd netmask $mask"
-				if [ "$bcaddr" -a "X$bcaddr" != "XNONE" ]; then
-					cmd="$cmd broadcast $bcaddr"
-				fi
-				;;
-			inet6)
-				if [ ! -n "$name" ]; then
-					echo "/etc/hostname.$if: inet6 alone is invalid"
-					return
-				fi
-				[ "$mask" ] && cmd="$cmd prefixlen $mask"
-				cmd="$cmd $bcaddr"
-				;;
-			*)
-				cmd="$cmd $mask $bcaddr"
-				;;
-			esac
-			cmd="$cmd $ext1 $ext2"
-			;;
-		esac
-		eval "$cmd"
-	done <$_file
+		((_i++))
+	done
+	unset _cmds
 }
 
 # Start multiple interfaces by driver name.
@@ -196,6 +188,23 @@ fi
 FUNCS_ONLY=1 . /etc/rc.d/rc.subr
 _rc_parse_conf
 
+HN_DIR=${HN_DIR:-/etc}
+PRINT_ONLY=false
+USAGE="USAGE: ${0##*/} [-n] [interface ...]"
+while getopts ":n" opt; do
+	case $opt in
+	n)	PRINT_ONLY=true;;
+	*)	print -u2 "$USAGE"; exit 1;;
+	esac
+done
+shift $((OPTIND-1))
+
+# Option -n is only supported if interface names are specified as parameters.
+if $PRINT_ONLY && (($# == 0)); then
+	print -u2 "Missing parameters.\n$USAGE"
+	exit 1
+fi
+
 # If we were invoked with a list of interface names, just reconfigure these
 # interfaces (or bridges), add default routes and return.
 if (($# > 0)); then