From ceca74ccc397795db68ca6ffbe49d65af2178a50 Mon Sep 17 00:00:00 2001

From: Martin Wilck <mwilck@suse.de>

Date: Sat, 11 Jul 2020 00:15:34 +0200

Subject: [PATCH] dracut-functions: add ip_params_for_remote_addr() helper

This helper function takes a remote IP address, and tries to

determine the dracut command line arguments ip= and ifname= that

will make this remote address reachable during boot.

Functionality was taken from the module-setup.sh scripts of 95iscsi and 95nfs,

cleaned up and fixed some issues in particular with statically configured

networks, where the old code would print the unsupported string

"$ifname:static".

---

 dracut-functions.sh | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++

 1 file changed, 114 insertions(+)

diff --git a/dracut-functions.sh b/dracut-functions.sh

index b5c28248..07ae88c0 100755

--- a/dracut-functions.sh

+++ b/dracut-functions.sh

@@ -728,3 +728,117 @@ btrfs_devs() {

         printf -- "%s\n" "$_dev"

         done

 }

+

+iface_for_remote_addr() {

+    set -- $(ip -o route get to "$1")

+    echo $3

+}

+

+local_addr_for_remote_addr() {

+    set -- $(ip -o route get to "$1")

+    echo $5

+}

+

+peer_for_addr() {

+    local addr=$1

+    local qtd

+

+    # quote periods in IPv4 address

+    qtd=${addr//./\\.}

+    ip -o addr show | \

+        sed -n 's%^.* '"$qtd"' peer \([0-9a-f.:]\{1,\}\(/[0-9]*\)\?\).*$%\1%p'

+}

+

+netmask_for_addr() {

+    local addr=$1

+    local qtd

+

+    # quote periods in IPv4 address

+    qtd=${addr//./\\.}

+    ip -o addr show | sed -n 's,^.* '"$qtd"'/\([0-9]*\) .*$,\1,p'

+}

+

+gateway_for_iface() {

+    local ifname=$1 addr=$2

+

+    case $addr in

+        *.*) proto=4;;

+        *:*) proto=6;;

+        *)   return;;

+    esac

+    ip -o -$proto route show | \

+        sed -n "s/^default via \([0-9a-z.:]\{1,\}\) dev $ifname .*\$/\1/p"

+}

+

+# This works only for ifcfg-style network configuration!

+bootproto_for_iface() {

+    local ifname=$1

+    local dir

+

+    # follow ifcfg settings for boot protocol

+    for dir in network-scripts network; do

+        [ -f "/etc/sysconfig/$dir/ifcfg-$ifname" ] && {

+            sed -n "s/BOOTPROTO=[\"']\?\([[:alnum:]]\{1,\}\)[\"']\?.*\$/\1/p" \

+                "/etc/sysconfig/$dir/ifcfg-$ifname"

+            return

+        }

+    done

+}

+

+is_unbracketed_ipv6_address() {

+    strglob "$1" '*:*' && ! strglob "$1" '\[*:*\]'

+}

+

+# Create an ip= string to set up networking such that the given

+# remote address can be reached

+ip_params_for_remote_addr() {

+    local remote_addr=$1

+    local ifname local_addr peer netmask= gateway ifmac

+

+    [[ $remote_addr ]] || return 1

+    ifname=$(iface_for_remote_addr "$remote_addr")

+    [[ $ifname ]] || {

+        berror "failed to determine interface to connect to $remote_addr"

+        return 1

+    }

+

+    # ifname clause to bind the interface name to a MAC address

+    if [ -d "/sys/class/net/$ifname/bonding" ]; then

+        dinfo "Found bonded interface '${ifname}'. Make sure to provide an appropriate 'bond=' cmdline."

+    elif [ -e "/sys/class/net/$ifname/address" ] ; then

+        ifmac=$(cat "/sys/class/net/$ifname/address")

+        [[ $ifmac ]] && printf 'ifname=%s:%s ' "${ifname}" "${ifmac}"

+    fi

+

+    bootproto=$(bootproto_for_iface "$ifname")

+    case $bootproto in

+        dhcp|dhcp6|auto6) ;;

+        dhcp4)

+            bootproto=dhcp;;

+        static*|"")

+            bootproto=;;

+        *)

+            derror "bootproto \"$bootproto\" is unsupported by dracut, trying static configuration"

+            bootproto=;;

+    esac

+    if [[ $bootproto ]]; then

+        printf 'ip=%s:%s ' "${ifname}" "${bootproto}"

+    else

+        local_addr=$(local_addr_for_remote_addr "$remote_addr")

+        [[ $local_addr ]] || {

+            berror "failed to determine local address to connect to $remote_addr"

+            return 1

+        }

+        peer=$(peer_for_addr "$local_addr")

+        # Set peer or netmask, but not both

+        [[ $peer ]] || netmask=$(netmask_for_addr "$local_addr")

+        gateway=$(gateway_for_iface "$ifname" "$local_addr")

+        # Quote IPv6 addresses with brackets

+        is_unbracketed_ipv6_address "$local_addr" && local_addr="[$local_addr]"

+        is_unbracketed_ipv6_address "$peer" && peer="[$peer]"

+        is_unbracketed_ipv6_address "$gateway" && gateway="[$gateway]"

+        printf 'ip=%s:%s:%s:%s::%s:none ' \

+               "${local_addr}" "${peer}" "${gateway}" "${netmask}" "${ifname}"

+    fi

+

+}