ethname

#!/bin/sh
#
#  * Copyright (c) 2016-2019 Eric Borisch <eborisch@gmail.com>
#  * All rights reserved.
#
# Self-contained rc.d script for re-naming devices based on their MAC address.
# Renaming is performed before interface bring-up -- netif -- so all
# configurations of the devices can be done with the new names.
#
# USAGE:
#  1)  Add the following to rc.conf:
#         ethname_enable="YES"
#         ethname_external_mac="aa:bb:cc:dd:ee:00"
#         ethname_private_mac="aa:bb:cc:dd:ee:01"
#  1a) You can optionally restrict handling to a set of defined names with:
#         ethname_names="external private"
#      otherwise all defined ethname_*_mac="" values are used
#  2)  Make sure any interfaces you want to rename have their drivers loaded or
#      compiled in. If ue0 is on axe0, for example, add 'if_load_axe="YES"' to
#      /boot/loader.conf. See the man page for your device (eg 'man axe') for
#      particulars.
#  3)  That's it. Use ifconfig_<name>="" settings with the new names.
#
# All other devices are untouched.
#
# Optional rc.conf settings:
#   ethname_timeout : Maximum wait time for devices to appear. [default=30]
#
# PROVIDE: ethname
# REQUIRE: FILESYSTEMS
# BEFORE: netif
# KEYWORD: nojail

# ethname version 2.0

. /etc/rc.subr

name=ethname
rcvar=ethname_enable
extra_commands="check"
check_cmd="en_check"

start_cmd="${name}_start"
stop_cmd=":"

load_rc_config ${name}
: ${ethname_names:=""}
: ${ethname_enable:=no}
: ${ethname_timeout:="30"}

en_str=""

# Will fill with mac interface [mac interface] ...]
en_map=""

# Will fill with original device names that match a managed mac address.
en_orig=""

# Total wait timeout; won't wait n*timeout for n devices, just timeout
en_waited=0

known_mac()
{
    echo "${en_map}" | grep -qi "$1"
}

to_lower()
{
    echo "$*" | tr "[:upper:]" "[:lower:]"
}


kv_lookup()
{
    # Called with $1=K, the key we want to find the value for, and $2:$3
    # $4:$5 ... forming pairs of key:value mappings
    local _K _key _value

    _K=$(to_lower "$1")
    [ -z "${_K}" ] && err 1 "Called kv_lookup() with missing args."
    shift
    while [ $# -ge 2 ]; do
        _key=$(to_lower "$1")
        _value=$2
        shift 2
        # Only supports non-zero-length keys/values
        [ -z "${_key}" -o -z "${_value}" ] && err 1 "Zero length values passed?"
        [ "${_key}" == "${_K}" ] && echo "${_value}" && return 0
    done
    return 1
}

good_mac() {
    echo "$1" | egrep -qi '^([0-9a-z]{2}:){5}[0-9a-z]{2}$' || \
      err 1 "Invalid MAC address defined: [$1]"
    return 0
}

good_devname() {
    echo "$1" | egrep -qi '^[a-z][a-z0-9_]+$' || \
      err 1 "Invalid device name defined: [$1]"
    return 0
}

breakout_map () {
    # This takes a single ethname_map variable (old interface) and breaks it
    # into the new interface (ethname_names and ethname_NAME_mac vars.)
    local _mac _name
    while [ $# -gt 0 ]; do
        _mac=$1
        _name=$2
        good_mac "${_mac}"
        good_devname "${_name}"
        shift 2
        # Params checked for validity above
        eval ethname_${_name}_mac="${_mac}"
        ethname_names="${ethname_names} ${_name}"
    done
}

en_prep()
{
    local _mac _name _dev _found
    local _compat=0

    if [ -z "${ethname_names}" ]; then
        # Compatibility code
        if [ ! -z "${ethname_map}" -a ! -z "${ethname_devices}" ]; then
            ethname_names=""
            warn "ethname: Using old interface. Please see documentation."
            breakout_map ${ethname_map}
            _compat=1
        else
            # Detect set ethname_*_mac names
            ethname_names=$(set | sed -En '/^ethname_([^=]+)_mac=.*/s//\1/p')
        fi
    fi

    # Transforms set of ethname_NAME_mac="" values into en_map="MAC NAME ..."
    # and en_orig="EXISTINGDEV ..."; a map of desired MAC:name mappings
    # and the devices with those MACs, respectively.

    for _name in ${ethname_names}; do
        # Make sure ${_name} is good before eval call
        good_devname "${_name}"
        eval _mac=\$ethname_${_name}_mac

        [ -z "${_mac}" -a ${_compat} -eq 0 ] && \
            warn "ethname_${_name}_mac is not set in rc.conf!" && continue

        good_mac "${_mac}"

        # Enable ctrl-c for wait loop
        trap break SIGINT

        _found=0
        while [ ${en_waited} -lt ${ethname_timeout} ]; do
            for _dev in $(ifconfig -l ether); do
                if ifconfig ${_dev} | grep -qi "${_mac}"; then
                    en_map="${en_map} ${_mac} ${_name}"
                    en_orig="${en_orig} ${_dev}"
                    _found=1
                    break
                fi
            done
            [ ${_found} -eq 1 ] && break
            sleep 1
            warn "Waiting for a device with MAC [${_mac}] to appear..."
            en_waited=$((en_waited + 1))
        done

        trap - SIGINT

        [ ${_found} -eq 0 ] && \
            warn "Unable to locate device to rename [${_name}]!"
    done
}

en_check() {
    local _mac _name _orig
    local _n=1
    en_prep
    # Piping into a while loop, but we don't need any results from this loop to
    # be visible in this shell, so it's not an issue.
    echo "${en_map}" | xargs -n 2 echo | while read _mac _name; do
        _orig=$(echo "${en_orig}" | awk "{print \$${_n}}")
        if [ "${_orig}" = "${_name}" ]; then
            printf "Device with MAC [%s] already named '%s'\n" \
              "${_mac}" "${_name}"
        else
            printf "Will rename [%s] to [%s] with MAC [%s]\n" \
              "${_orig}" "${_name}" "${_mac}"
        fi
        _n=$((_n + 1))
    done
}

fix_name()
{
    # Can be called with or without a second argument (which is used as the new
    # name if provided.) If only one argument, lookup desired name in map.
    dev=$1
    name=$2

    # Make sure the device exists as an ifconfig device
    if ! ifconfig -l ether | grep -q "${dev}"; then
        en_str="could not find device."
        return 1
    fi

    # Grab MAC address
    mac=$(ifconfig ${dev} | awk '/ether/{print tolower($2)}')

    if [ ${#mac} -eq 0 ]; then
        en_str="unable to get MAC address"
        return 1
    fi

    # Make sure the MAC for this device is in our rename table.
    if ! known_mac "${mac}"; then
        en_str="no maching MAC in ethname_<NAME>_mac params."
        return 1
    fi

    # Find name from MAC -> dev_name table in map
    dname=$(kv_lookup ${mac} ${en_map})
    if [ "${dname}" == "${dev}" ]; then
        en_str="already has desired name."
        return 1
    fi

    # Use name from MAC -> dev_name table in map if $2 was empty
    : ${name:=${dname}}

    # We have everything we need. Now actual rename of the device.
    if ! ifconfig ${dev} name ${name} > /dev/null ; then
        en_str="return code: $?"
        return 2
    fi
}

ethname_start()
{
    local _n _m _prefix _x
    # Build the map of "mac name [mac name] [...]"
    en_prep

    # Don't report any other errors if we haven't been asked to do anything.
    if [ ${#en_orig} -eq 0 ]; then
        warn "Unable to locate any of the specified ethname_\*_mac addresses."
        exit 0
    fi

    # Rename interfaces; first into en_tmp_$_n with _n = 0, 1, ... to avoid any
    # possible collision with the desired names. (ex. ue0 -> ue1; ue1 -> ue0
    # renaming.)
    _prefix=en_$$_
    _n=0
    for _x in ${en_orig}; do
        if fix_name ${_x} ${_prefix}${_n}; then
            _n=$((_n+1))
        elif [ $? -eq 1 ]; then
            info "Skipping rename of [${_x}]: ${en_str}"
        else
            warn "Error during rename of [${_x}]: ${en_str}"
        fi
    done

    # Loop back over renamed devices and lookup their desired names.
    _m=0
    while [ ${_m} -lt ${_n} ]; do
        fix_name ${_prefix}${_m} || \
          warn "Error during renaming process. Stranded [${_prefix}${_m}]."
        _m=$((_m+1))
    done
}

run_rc_command "$1"

# vim: et:ts=4:sw=4