RE: [Xen-devel] make network-bridge work in more environments

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> # Made network-bridge script work on ALL systems missing ifup/down.
> # This is done by defining ifup/down both to 'false' when they're
> # missing; then instead of attempting to parse the IP params from
> # the kernel command line, we get them from 'ip' instead.  So this 
> # works even with (for example) ip=dhcp on the kernel command line.
> #
> # Also made a few minor syntax changes (in particular, replaced "=="
> # with "=", and ">&foo" with ">foo 2>foo") so this works with more 
> # limited shells.

I like this patch, but how well tested is it?

Hacking the bridge script generally brings nothing but pain as users of
all sorts of distro you've never even heard of start complaining...

Ian

> # Signed-off-by: Ben Thomas <bjthomas3@xxxxxxxxx>
> #
> diff -Nru examples.orig/network-bridge examples/network-bridge
> --- examples.orig/network-bridge    2005-12-15 10:48: 
> 47.000000000 -0500
> +++ examples/network-bridge    2005-12-15 10:51:20.000000000 -0500
> @@ -68,48 +68,19 @@
>  vdev="veth${vifnum}"
>  vif0="vif0.${vifnum}"
>  
> -legacy_mask_to_prefix() {
> -    mask=$1
> -    first=${mask%%.*}
> -    second=${mask#*.}
> -    third=${second#*.}
> -    fourth=${third#*.}
> -    second=${second%%.*}
> -    third=${third%%.*}
> -    declare -i INT FULLMASK BIT
> -    INT=$((((($first*256)+$second)*256+$third)*256+$fourth)) 
> -    FULLMASK=4294967295
> -    BIT=1
> -    for bit in `seq 32 -1 0`; do
> -    if test $FULLMASK -eq $INT; then PREFIX=$bit; return; fi
> -    FULLMASK=$(($FULLMASK-$BIT))
> -    BIT=$((BIT*2))
> -    done
> -    echo "ERROR converting netmask $mask to prefix"
> -    exit 1
> -}
> -
> -parse_kernel_ip() {
> -    if egrep 'ip=[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+:' /proc/cmdline; then
> -    kip=`sed -e 
> 's!.*ip=\([0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+\):.*!\1!' /proc/cmdline` 
> -    kmask=`sed -e 
> 's!.*ip=[^:]*:[^:]*:[^:]*:\([^:]*\):.*!\1!' /proc/cmdline` 
> -    kgate=`sed -e 's!.*ip=[^:]*:[^:]*:\([^:]*\):.*!\1!' 
> /proc/cmdline`
> -    fi
> +get_ip_info() {
> +    addr_pfx=`ip addr show dev $1 | egrep '^ *inet' | sed -e 
> 's/ *inet //' -e 's/ .*//'` 
> +    gateway=`ip route show dev $1 | fgrep default | sed 
> 's/default via //'`
>  }
> -
> +    
>  do_ifup() {
>      if ! ifup $1 ; then
> -        if [ ${kip} ] ; then
> -            # use the addresses we grocked from /proc/cmdline 
> -            if [ -z "${kmask}" ]; then 
> -                PREFIX=32
> -            else 
> -                legacy_mask_to_prefix ${kmask}
> -            fi
> +        if [ ${addr_pfx} ] ; then
> +            # use the info from get_ip_info() 
>              ip addr flush $1
> -            ip addr add ${kip}/${PREFIX} dev $1
> +            ip addr add ${addr_pfx} dev $1
>              ip link set dev $1 up
> -            [ ${kgate} ] && ip route add default via ${kgate} 
> +            [ ${gateway} ] && ip route add default via ${gateway}
>          fi
>      fi
>  }
> @@ -171,7 +142,7 @@
>  #
>  link_exists()
>  {
> -    if ip link show "$1" >&/dev/null 
> +    if ip link show "$1" >/dev/null 2>/dev/null
>      then
>          return 0
>      else
> @@ -231,7 +202,7 @@
>  }
>  
>  op_start () {
> -    if [ "${bridge}" == "null" ] ; then 
> +    if [ "${bridge}" = "null" ] ; then
>      return
>      fi
>  
> @@ -259,9 +230,8 @@
>      preiftransfer ${netdev}
>      transfer_addrs ${netdev} ${vdev}
>      if ! ifdown ${netdev}; then 
> -        # If ifdown fails, take the IP details from the 
> kernel command
> -        # line.
> -        parse_kernel_ip
> +        # If ifdown fails, remember the IP details.
> +        get_ip_info ${netdev}
>          ip link set ${netdev} down 
>          ip addr flush ${netdev}
>      fi
> @@ -283,13 +253,13 @@
>      transfer_routes ${netdev} ${bridge}
>      fi
>  
> -    if [ ${antispoof} == 'yes' ] ; then
> +    if [ ${antispoof} = 'yes' ] ; then
>      antispoofing
>      fi
>  }
>  
>  op_stop () {
> -    if [ "${bridge}" == "null" ]; then
> +    if [ "${bridge}" = "null" ]; then
>      return
>      fi
>      if ! link_exists "$bridge"; then 
> @@ -301,7 +271,7 @@
>      mac=`ip link show ${netdev} | grep 'link\/ether' | sed 
> -e 's/.*ether \(..:..:..:..:..:..\).*/\1/'`
>      transfer_addrs ${netdev} ${pdev}
>      if ! ifdown ${netdev}; then
> -        parse_kernel_ip 
> +        get_ip_info ${netdev}
>      fi
>      ip link set ${netdev} down arp off
>      ip link set ${netdev} addr fe:ff:ff:ff:ff:ff
> diff -Nru examples.orig/xen-network-common.sh 
> examples/xen-network-common.sh 
> --- examples.orig/xen-network-common.sh    2005-12-15 
> 10:48:47.000000000 -0500
> +++ examples/xen-network-common.sh    2005-12-15 
> 10:52:38.000000000 -0500
> @@ -42,7 +42,7 @@
>    {
>      /sbin/ifup ${HWD_CONFIG_0} $1 
>    }
> -elif ! which ifup >&/dev/null
> +elif ! which ifup >/dev/null 2>/dev/null
>  then
>    if [ -e /etc/conf.d/net ]
>    then
> @@ -59,9 +59,18 @@
>        /etc/init.d/net.$1 stop
>      }
>    else
> -    logger -p "daemon.crit" -- \
> -      "You don't have ifup and don't seem to be running 
> Gentoo either!"
> -    exit 1
> +    preiftransfer()
> +    {
> +      true
> +    }
> +    ifup() 
> +    {
> +      false
> +    }
> +    ifdown()
> +    {
> +      false
> +    }
>    fi
>  else
>    preiftransfer()
> 
> 
> 
> 
> 
> 
> 
> 
> 

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