Revamp of bridging code.

- Use sysfs to read bridge information from the system instead of
  parsing the brctl outputs.
- Allow setting of all bridge configuration parameters using new sysfs
  methods, modelled after bonding configuration. Also works for per-port
  bridge interface parameters.
- Document pre-starting an empty bridge for dynamic add.
- Check for interface existence before adding to bridge.
- Should fix bug #293046, #309185.

TODO

@@ -1,3 +1,5 @@
 - ensure all forks block, restore and unblock signals. needs review 
 
 - add support somehow for optional translations
+
+- oldnet[bridging]: Review setting of bridge configuration on dynamic interface add

doc/net.example.Linux.in

@@ -805,6 +805,18 @@
 #sethello 0
 #stp off"
 
+# You can also configure the bridge or bridge members via sysfs on 2.6 kernels
+# or newer. See the kernel bridge documentation for a description of these
+# options.
+#stp_state_br0="0"
+#forward_delay_br0="10"
+#hairpin_mode_eth0="1"
+
+# If you want to start an empty bridge, and then dynmically add ports to it you
+# MUST set the following variables (with the correct interface name).
+# If you get the error "Misconfigured static bridge detected", this means you.
+#bridge_br0=''
+
 #-----------------------------------------------------------------------------
 # RFC 2684 Bridge Support 
 # For RFC 2684 bridge support emerge net-misc/br2684ctl

net/bridge.sh

@@ -11,29 +11,56 @@ _config_vars="$_config_vars bridge bridge_add brctl"
 
 _is_bridge()
 {
-	# Ignore header line so as to allow for bridges named 'bridge'
-	brctl show 2>/dev/null | sed '1,1d' | grep -q "^${IFACE}[[:space:]]"
+	[ -d /sys/class/net/"${1:-${IFACE}}"/bridge ]
+	return $?
+}
+
+_is_bridge_port()
+{
+	[ -d /sys/class/net/"${1:-${IFACE}}"/brport ]
+	return $?
+}
+
+_bridge_ports()
+{
+	for x in /sys/class/net/"${1:-${IFACE}}"/brif/*; do
+		n=${x##*/}
+		echo $n
+	done
 }
 
 bridge_pre_start()
 {
-	local brif= iface="${IFACE}" e= x=
+	local brif= oiface="${IFACE}" e= x=
 	local ports="$(_get_array "bridge_${IFVAR}")"
 	local opts="$(_get_array "brctl_${IFVAR}")"
 	
+	# brif is used for dynamic add
 	eval brif=\$bridge_add_${IFVAR}
-	eval x=\${bridge_${IFVAR}-y\}
-	if [ -z "${brif}" -a -z "${opts}" ]; then
-		[ -n "${ports}" -o "${x}" != "y" ] || return 0
+	# ports is for static add
+	eval bridge_unset=\${bridge_${IFVAR}-y\}
+	eval brctl_unset=\${brctl_${IFVAR}-y\}
+	
+	# If we are not doing dynamic add on $IFACE, check for static ports.
+	if [ -z "${brif}" -a "${brctl_unset}" == 'y' ]; then
+		if [ -z "${ports}" -a "${bridge_unset}" == "y" ]; then
+			#eerror "Misconfigured static bridge detected (see net.example)"
+			return 0
+		fi
 	fi
 
-	[ -n "${ports}" ] && bridge_post_stop
+	# If the bridge was already up, we should clear it
+	[ "${bridge_unset}" != "y" ] && bridge_post_stop
 
 	(
+	# Normalize order of variables
 	if [ -z "${ports}" -a -n "${brif}" ]; then
+		# Dynamic mode detected
 		ports="${IFACE}"
 		IFACE="${brif}"
+		IFVAR=$(shell_var "${IFACE}")
 	else
+		# Static mode detected
 		ports="${ports}"
 		metric=1000
 	fi
@@ -46,6 +73,12 @@ bridge_pre_start()
 		fi
 	fi
 
+	# TODO: does this reset the bridge every time we add a interface to the
+	# bridge? We should probably NOT do that.
+
+	# Old configuration set mechanism
+	# Only a very limited subset of the options are available in the old
+	# configuration method. The sysfs interface is in the next block instead.
 	local IFS="$__IFS"
 	for x in ${opts}; do
 		unset IFS
@@ -57,21 +90,50 @@ bridge_pre_start()
 	done
 	unset IFS
 
+	# New configuration set mechanism, matches bonding
+	for x in /sys/class/net/"${IFACE}"/bridge/*; do
+		[ -f "${x}" ] || continue
+		n=${x##*/}
+		eval s=\$${n}_${IFVAR}
+		if [ -n "${s}" ]; then
+			einfo "Setting ${n}: ${s}"
+			echo "${s}" >"${x}" || \
+			eerror "Failed to configure $n (${n}_${IFVAR})"
+		fi
+	done
+
 	if [ -n "${ports}" ]; then
 		einfo "Adding ports to ${IFACE}"
 		eindent
 
-		local OIFACE="${IFACE}"
+		local BR_IFACE="${IFACE}"
 		for x in ${ports}; do
 			ebegin "${x}"
 			local IFACE="${x}"
+			local IFVAR=$(shell_var "${IFACE}")
+			if ! _exists "${IFACE}" ; then
+				eerror "Cannot add non-existent interface ${IFACE} to ${BR_IFACE}"
+				return 1
+			fi
+			# The interface is known to exist now
 			_set_flag promisc
 			_up
-			if ! brctl addif "${OIFACE}" "${x}"; then
+			if ! brctl addif "${BR_IFACE}" "${x}"; then
 				_set_flag -promisc
 				eend 1
 				return 1
 			fi
+			# Per-interface bridge settings
+			for x in /sys/class/net/"${IFACE}"/brport/*; do
+				[ -f "${x}" ] || continue
+				n=${x##*/}
+				eval s=\$${n}_${IFVAR}
+				if [ -n "${s}" ]; then
+					einfo "Setting ${n}@${IFACE}: ${s}"
+					echo "${s}" >"${x}" || \
+					eerror "Failed to configure $n (${n}_${IFVAR})"
+				fi
+			done
 			eend 0
 		done
 		eoutdent
@@ -86,27 +148,24 @@ bridge_post_stop()
 {
 	local port= ports= delete=false extra=
 
-	if _is_bridge; then
+	if _is_bridge "${IFACE}"; then
 		ebegin "Destroying bridge ${IFACE}"
 		_down
-		# Ignore header line so as to allow for bridges named 'bridge'
-		ports="$(brctl show 2>/dev/null | \
-			sed -n -e '1,1d' -e '/^'"${IFACE}"'[[:space:]]/,/^\S/ { /^\('"${IFACE}"'[[:space:]]\|\t\)/s/^.*\t//p }')"
+		for x in /sys/class/net/"${IFACE}"/brif/*; do
+			[ -s $x ] || continue
+			n=${x##*/}
+			ports="${ports} ${n}"
+		done
 		delete=true
 		iface=${IFACE}
 		eindent
 	else
-		# Work out if we're added to a bridge for removal or not
-		# Ignore header line so as to allow for bridges named 'bridge'
-		eval set -- $(brctl show 2>/dev/null | sed -e '1,1d' -e "s/'/'\\\\''/g" -e "s/$/'/g" -e "s/^/'/g")
-		local line=
-		for line; do
-			set -- ${line}
-			if [ "$3" = "${IFACE}" ]; then
-				iface=$1
-				break
-			fi
-		done
+		# We are taking down an interface that is part of a bridge maybe
+		ports="${IFACE}"
+		local brport_dir="/sys/class/net/${IFACE}/brport"
+		[ -d ${brport_dir} ] || return 0
+		iface=$(readlink ${brport_dir}/bridge)
+		iface=${iface##*/}
 		[ -z "${iface}" ] && return 0
 		extra=" from ${iface}"
 	fi