portus 0.9.0

A Congestion Control Plane
Documentation 
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//! Message sent from datapath to CCP when a new flow starts.

use super::{AsRawMsg, HDR_LENGTH, RawMsg, u32_to_u8s};
use crate::{Error, Result};
use std::io::prelude::*;

pub(crate) const CREATE: u8 = 0;

#[derive(Clone, Debug, PartialEq)]
pub struct Msg {
    pub sid: u32,
    pub init_cwnd: u32,
    pub mss: u32,
    pub src_ip: u32,
    pub src_port: u32,
    pub dst_ip: u32,
    pub dst_port: u32,
    pub cong_alg: Option<String>,
}

impl AsRawMsg for Msg {
    fn get_hdr(&self) -> (u8, u32, u32) {
        (CREATE, HDR_LENGTH + 6 * 4 + 64, self.sid)
    }

    fn get_u32s<W: Write>(&self, w: &mut W) -> Result<()> {
        let mut buf = [0u8; 4];
        u32_to_u8s(&mut buf, self.init_cwnd as u32);
        w.write_all(&buf[..])?;
        u32_to_u8s(&mut buf, self.mss as u32);
        w.write_all(&buf[..])?;
        u32_to_u8s(&mut buf, self.src_ip as u32);
        w.write_all(&buf[..])?;
        u32_to_u8s(&mut buf, self.src_port as u32);
        w.write_all(&buf[..])?;
        u32_to_u8s(&mut buf, self.dst_ip as u32);
        w.write_all(&buf[..])?;
        u32_to_u8s(&mut buf, self.dst_port as u32);
        w.write_all(&buf[..])?;
        Ok(())
    }

    fn get_bytes<W: Write>(&self, w: &mut W) -> Result<()> {
        let mut buf = [0u8; 64];
        if let Some(c) = &self.cong_alg {
            if c.len() > 63 {
                return Err(Error(String::from("Cong alg name too long")));
            } else {
                buf.copy_from_slice(c.as_bytes());
            }
        }

        w.write_all(&buf)?;
        Ok(())
    }

    fn from_raw_msg(msg: RawMsg) -> Result<Self> {
        let u32s = unsafe { msg.get_u32s() }?;
        let b = msg.get_bytes()?;
        let cong_alg = if b[0] == 0 {
            None
        } else {
            let end = b.iter().position(|&c| c == b'\0').unwrap_or(b.len());
            if let Ok(s) = std::ffi::CStr::from_bytes_with_nul(&b[..end + 1]) {
                Some(s.to_str()?.to_owned())
            } else {
                None
            }
        };
        Ok(Msg {
            sid: msg.sid,
            init_cwnd: u32s[0],
            mss: u32s[1],
            src_ip: u32s[2],
            src_port: u32s[3],
            dst_ip: u32s[4],
            dst_port: u32s[5],
            cong_alg,
        })
    }
}

#[cfg(test)]
mod tests {
    macro_rules! check_create_msg {
        ($id: ident, $msg: expr_2021) => {
            check_msg!($id, super::Msg, $msg, crate::serialize::Msg::Cr(crm), crm);
        };
    }

    check_create_msg!(
        test_create_1,
        super::Msg {
            sid: 15,
            init_cwnd: 1448 * 10,
            mss: 1448,
            src_ip: 0,
            src_port: 4242,
            dst_ip: 0,
            dst_port: 4242,
            cong_alg: None,
        }
    );
}