utils.rs

// TODO: this is literally a copy of examples/utils.rs, but without an allow dead code attribute.
// The include logic does not allow having attributes in included files.

use getopts::{Matches, Options};
use std::env;
use std::fs::File;
use std::io;
use std::io::Write;
use std::process;
use std::str::{self, FromStr};
use std::time::{SystemTime, UNIX_EPOCH};

use smoltcp::phy::{Device, FaultInjector, Tracer};
use smoltcp::phy::{PcapMode, PcapWriter};
use smoltcp::time::Duration;

pub fn create_options() -> (Options, Vec<&'static str>) {
    let mut opts = Options::new();
    opts.optflag("h", "help", "print this help menu");
    (opts, Vec::new())
}

pub fn parse_options(options: &Options, free: Vec<&str>) -> Matches {
    match options.parse(env::args().skip(1)) {
        Err(err) => {
            println!("{}", err);
            process::exit(1)
        }
        Ok(matches) => {
            if matches.opt_present("h") || matches.free.len() != free.len() {
                let brief = format!(
                    "Usage: {} [OPTION]... {}",
                    env::args().nth(0).unwrap(),
                    free.join(" ")
                );
                print!("{}", options.usage(&brief));
                process::exit(if matches.free.len() != free.len() {
                    1
                } else {
                    0
                })
            }
            matches
        }
    }
}

pub fn add_middleware_options(opts: &mut Options, _free: &mut Vec<&str>) {
    opts.optopt("", "pcap", "Write a packet capture file", "FILE");
    opts.optopt(
        "",
        "drop-chance",
        "Chance of dropping a packet (%)",
        "CHANCE",
    );
    opts.optopt(
        "",
        "corrupt-chance",
        "Chance of corrupting a packet (%)",
        "CHANCE",
    );
    opts.optopt(
        "",
        "size-limit",
        "Drop packets larger than given size (octets)",
        "SIZE",
    );
    opts.optopt(
        "",
        "tx-rate-limit",
        "Drop packets after transmit rate exceeds given limit \
                                      (packets per interval)",
        "RATE",
    );
    opts.optopt(
        "",
        "rx-rate-limit",
        "Drop packets after transmit rate exceeds given limit \
                                      (packets per interval)",
        "RATE",
    );
    opts.optopt(
        "",
        "shaping-interval",
        "Sets the interval for rate limiting (ms)",
        "RATE",
    );
}

pub fn parse_middleware_options<D>(
    matches: &mut Matches,
    device: D,
    loopback: bool,
) -> FaultInjector<Tracer<PcapWriter<D, Box<dyn Write>>>>
where
    D: Device,
{
    let drop_chance = matches
        .opt_str("drop-chance")
        .map(|s| u8::from_str(&s).unwrap())
        .unwrap_or(0);
    let corrupt_chance = matches
        .opt_str("corrupt-chance")
        .map(|s| u8::from_str(&s).unwrap())
        .unwrap_or(0);
    let size_limit = matches
        .opt_str("size-limit")
        .map(|s| usize::from_str(&s).unwrap())
        .unwrap_or(0);
    let tx_rate_limit = matches
        .opt_str("tx-rate-limit")
        .map(|s| u64::from_str(&s).unwrap())
        .unwrap_or(0);
    let rx_rate_limit = matches
        .opt_str("rx-rate-limit")
        .map(|s| u64::from_str(&s).unwrap())
        .unwrap_or(0);
    let shaping_interval = matches
        .opt_str("shaping-interval")
        .map(|s| u64::from_str(&s).unwrap())
        .unwrap_or(0);

    let pcap_writer: Box<dyn io::Write>;
    if let Some(pcap_filename) = matches.opt_str("pcap") {
        pcap_writer = Box::new(File::create(pcap_filename).expect("cannot open file"))
    } else {
        pcap_writer = Box::new(io::sink())
    }

    let seed = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .subsec_nanos();

    let device = PcapWriter::new(
        device,
        pcap_writer,
        if loopback {
            PcapMode::TxOnly
        } else {
            PcapMode::Both
        },
    );

    let device = Tracer::new(device, |_timestamp, _printer| {
        #[cfg(feature = "log")]
        trace!("{}", _printer);
    });
    let mut device = FaultInjector::new(device, seed);
    device.set_drop_chance(drop_chance);
    device.set_corrupt_chance(corrupt_chance);
    device.set_max_packet_size(size_limit);
    device.set_max_tx_rate(tx_rate_limit);
    device.set_max_rx_rate(rx_rate_limit);
    device.set_bucket_interval(Duration::from_millis(shaping_interval));
    device
}