canspam

#!/bin/bash
set -o errexit
set -o pipefail
set -o nounset
set -o noclobber

usage() {
    cat <<EOF
Usage: $0 [--help] [--jobs]

A thin wrapper around cangen to spam a CAN bus with fake data.

Optional arguments:
    --help, -h      Show this help and exit
    --iface, -i     The CAN interface to use. Defaults to can0
    --gap, -g       Gap between frames in milliseconds. Defaults to 1 (~70% busload)
    --burst, -b     Number of messages to send in burst. Defaults to 1
    --priority, -p  The priority to send the CAN spam at. Only applies if --random is not passed. Defaults to 6
    --random, -r    Send random data
EOF
}

kill_cangen() {
    # Kill all child processes
    pkill -P $$
}

main() {
    local can_interface="can0"
    local gap=1
    local burst=1
    local priority=6
    local random="false"
    local limit="false"

    while [[ $# -gt 0 ]]; do
        case "$1" in
        --help | -h)
            usage
            exit
            ;;
        --iface | -i)
            can_interface="$2"
            shift
            ;;
        --gap | -g)
            gap="$2"
            shift
            ;;
        --burst | -b)
            burst="$2"
            shift
            ;;
        --priority | -p)
            priority="$2"
            shift
            ;;
        --random | -r)
            random="true"
            ;;
        --limit | -l | -n)
            limit="$2"
            shift
            ;;
        *)
            echo "Unsupported argument: '$1'" >&2
            exit 1
            ;;
        esac
        shift
    done

    trap kill_cangen EXIT

    case "$priority" in
    [1-7]) ;;
    *)
        echo "Priority must be 1-7, not '$priority'" >&2
        exit 1
        ;;
    esac

    local -r fixed_data_args=(
        # Use FE as destination address, so that no one tries to read this silly message
        -I "$(python -c "print(hex((($priority & 0b111) << 26) | 0xEFFEFF)[2:])")"
        -D DEADBEEFDEADBEEF
    )
    local extra_args=()
    if [[ "$random" = "false" ]]; then
        extra_args+=("${fixed_data_args[@]}")
    fi
    if [[ "$limit" != "false" ]]; then
        extra_args+=(-n "$limit")
    fi

    cangen "$can_interface" -e -L 8 "${extra_args[@]}" -g "$gap" -i -c "$burst" &

    canbusload "$can_interface@250000" -rtbc
}

main "$@"