CBL-Mariner/SPECS/hyperv-daemons/hv_set_ifconfig

#!/usr/bin/env bash
#
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
#
# Script to configure the network interface based
# on the setting passed by hypervkvpd daemon
#
# This script works based on the kvp values supplied by the host.
# Network setting supplied by host is described in the below link.
# https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/tools/hv/hv_set_ifconfig.sh
#
# Usage: hv_set_ifconfig <ifcfg-eth*>
#

BKDIR=$(mktemp -td .netconfig.XXXXXX)
trap 'rm -rf ${BKDIR}' EXIT

# Network configuration entries
NETDIR="/etc/systemd/network"
NETCONFFILE="" # populated during execution

# Restart the network service
restart_net_service() {
    systemctl restart systemd-networkd
}

# Revert the network setting
restore_net_settings() {
    [[ -d ${BKDIR} ]] && {
        find "${BKDIR}" -maxdepth 1 -type f -exec cp {} "${NETDIR}" \;
    } || return 1

    [[ -f "${NETCONFFILE}" ]] && rm -f "${NETCONFFILE}"
    restart_net_service
}

# Backup the network setting to revert in case of failure
backup_net_settings() {
    find "${NETDIR}" -maxdepth 1 -type f -exec mv {} "${BKDIR}" >/dev/null 2>&1 \;
}

# Update IPv6 setting in network configuration
update_ipv6_conf() {

    local cfgfile="" ipaddr="" ipv6pfx="" gateway=""
    cfgfile=${1}

    # Update IPv6 address and netmask
    ipaddr_cnt=$(grep -c IPV6ADDR "${cfgfile}")
    for ((i=0; i<ipaddr_cnt; i++)); do
        ipaddr=$(grep -w "IPV6ADDR$i" "${cfgfile}" | cut -d'=' -f2)
        ipv6pfx=$(grep -w "IPV6NETMASK$i" "${cfgfile}" | cut -d'=' -f2)
        [[ -z ${ipv6pfx} ]] && ipv6pfx=64
        [[ ! -z ${ipaddr} ]] && {
            echo "Address=${ipaddr}/${ipv6pfx}" >> "${NETCONFFILE}"
        }
    done

    # Update GATEWAY
    gateway=$(awk -F "=" '/IPV6_DEFAULTGW/ {print $2}' "${cfgfile}")
    [[ ! -z "${gateway}" ]] && {
        echo "Gateway=${gateway}" >> "${NETCONFFILE}"
    }
}

# Update IPv4 setting in network configuration
update_ipv4_conf() {

    local cfgfile="" gateway="" ipaddr="" netmask=""
    local ipaddr_cnt=0 gateway_cnt=0
    cfgfile="${1}"

    # Update IPv4 address and netmask
    ipaddr_cnt=$(grep -c IPADDR "${cfgfile}")
    for ((i=0; i<ipaddr_cnt; i++)); do
        local pfx=24
        ipaddr=$(grep -w "IPADDR$i" "${cfgfile}" | cut -d'=' -f2)
        netmask=$(grep -w "NETMASK$i" "${cfgfile}" | cut -d'=' -f2)
        [[ ! -z "${netmask}" ]] && {
            pfx=0
            for num in ${netmask//\./ }; do
                local brep=0
                [[ "${num}" -eq 0 ]] && continue
                brep=$(bc <<< "obase=2; ${num}")
                brep=${brep//0/}
                pfx=$((pfx + ${#brep}))
            done
        }
        [[ ! -z "${ipaddr}" ]] && {
            echo "Address=${ipaddr}/${pfx}" >> "${NETCONFFILE}"
        }
    done

    # Update GATEWAY
    gateway_cnt=$(grep -c GATEWAY "${cfgfile}")
    gateway=$(awk -F "=" '/GATEWAY/ {print $2}' "${cfgfile}")
    [[ ! -z "${gateway}" ]] && {
        echo "Gateway=${gateway}" >> "${NETCONFFILE}"
    }

    for ((i=1; i<gateway_cnt; i++)); do
        gateway=$(grep -w "GATEWAY$i" "${cfgfile}" | cut -d'=' -f2)
        [[ ! -z "${gateway}" ]] && {
            echo "Gateway=${gateway}" >> "${NETCONFFILE}"
        }
    done

    return 0
}

# Generate the config file for updating the new configuration
generate_net_config() {

    # Network configuration
    #
    local cfgfile="" netifc="" hwaddr="" bootproto="" dns=""
    local dns_cnt=0

    cfgfile=${1}
    netifc=$(cut -d- -f2 <<< "${cfgfile}")
    hwaddr=$(awk -F "=" '/HWADDR/ {print $2}' "${cfgfile}")

    NETCONFFILE="${NETDIR}/98-static-${netifc}.network"

    # Generate the network configuration file
    {
        echo "[Match]"
        echo "Name=${netifc}"
        echo "MACAddress=${hwaddr}"
        echo ""
        echo "[Network]"
    } > "${NETCONFFILE}"

    bootproto=$(awk -F "=" '/BOOTPROTO/ {print $2}' "${cfgfile}")
    [[ ! -z "${bootproto}" && (${bootproto} == "DHCP") ]] && {
        echo "DHCP=yes" >> "${NETCONFFILE}"
    }

    # Update IPv4 configuration
    update_ipv4_conf "${cfgfile}"

    # Update IPv6 configuration
    update_ipv6_conf "${cfgfile}"

    # Update DNS
    dns_cnt=$(grep -c DNS "${cfgfile}")
    for ((i=1; i<=dns_cnt; i++)); do
        dns=$(grep "DNS$i" "${cfgfile}" | cut -d'=' -f2)
        [[ ! -z ${dns} ]] && {
            echo "DNS=${dns}" >> "${NETCONFFILE}"
        }
    done

    echo "" >> "${NETCONFFILE}"

    chmod 0644 "${NETCONFFILE}"
    return 0
}

# Entry point

# Check parameters
[[ -z "$1" || ! -f "$1" ]] && {
    echo "Usage: hv_set_ifconfig hv_config"
    exit 1
}

# Backup current setting to recover in case of failure
backup_net_settings

# Generate net config based on hv_config settings
generate_net_config "$1"

# Restart network service
restart_net_service || restore_net_settings

exit 0