Add TCP Echo Server Example

.gitignore

@@ -4,3 +4,9 @@ compile_commands.json
 *.ll
 *.o
 *.skel.h
+
+# Rust
+**/debug/
+**/target/
+**/Cargo.lock
+**/*.rs.bk

README.md

@@ -4,8 +4,8 @@ This git repository contains a diverse set of **practical BPF examples** that
 solve (or demonstrate) a specific use-case using BPF.
 
 It is meant to ease doing **rapid prototyping and development**, writing C-code
-BPF programs using libbpf.  The goal is to make it **easier for developers** to
-get started coding.
+BPF programs using libbpf, or Rust BPF programs using Aya.
+The goal is to make it **easier for developers** to get started coding.
 
 Many developers struggle to get a working BPF build environment.  The repo
 enviroment makes it easy to build/compile BPF programs by doing the necessary

echo/.cargo/config.toml

@@ -0,0 +1,2 @@
+[alias]
+xtask = "run --package xtask --"

echo/.vim/coc-settings.json

@@ -0,0 +1,3 @@
+{
+  "rust-analyzer.linkedProjects": ["Cargo.toml", "echo-ebpf/Cargo.toml"]
+}

echo/.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+  "rust-analyzer.linkedProjects": ["Cargo.toml", "echo-ebpf/Cargo.toml"]
+}

echo/Cargo.toml

@@ -0,0 +1,2 @@
+[workspace]
+members = ["echo", "echo-tokio", "xtask"]

echo/README.md

@@ -0,0 +1,32 @@
+# echo
+
+Echo is an example that creates a TCP Echo Server using socket redirection.
+For comparison, a simple (naive) TCP Echo Server is also provided.
+
+
+## Prerequisites
+
+1. Install a rust stable toolchain: `rustup install stable`
+1. Install a rust nightly toolchain: `rustup install nightly`
+1. Install bpf-linker: `cargo install bpf-linker`
+
+## Running The eBPF Example
+
+```bash
+cargo xtask build-ebpf
+cargo xtask run
+```
+
+## Running the Native Example
+
+```bash
+cargo run --bin echo-tokio
+```
+
+## Interacting with the Example
+
+```bash
+nc localhost 41234
+```
+
+Any data sent will be echoed back to the client

echo/echo-ebpf/.cargo/config.toml

@@ -0,0 +1,6 @@
+[build]
+target-dir = "../target"
+target = "bpfel-unknown-none"
+
+[unstable]
+build-std = ["core"]

echo/echo-ebpf/.vim/coc-settings.json

@@ -0,0 +1,4 @@
+{
+    "rust-analyzer.cargo.target": "bpfel-unknown-none",
+    "rust-analyzer.checkOnSave.allTargets": false
+}

echo/echo-ebpf/.vscode/settings.json

@@ -0,0 +1,4 @@
+{
+    "rust-analyzer.cargo.target": "bpfel-unknown-none",
+    "rust-analyzer.checkOnSave.allTargets": false,
+}

echo/echo-ebpf/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "echo-ebpf"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+aya-bpf = { git = "https://github.com/aya-rs/aya", branch="main" }
+
+[[bin]]
+name = "echo"
+path = "src/main.rs"
+
+[profile.dev]
+panic = "abort"
+debug = 1
+opt-level = 2
+overflow-checks = false
+
+[profile.release]
+panic = "abort"
+
+[workspace]
+members = []

echo/echo-ebpf/rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel="nightly"

echo/echo-ebpf/src/main.rs

@@ -0,0 +1,45 @@
+#![no_std]
+#![no_main]
+
+use aya_bpf::{
+    bindings::sk_action,
+    macros::{map, stream_parser, stream_verdict},
+    maps::SockMap,
+    programs::SkBuffContext,
+};
+
+#[map(name = "sockmap")]
+static mut SOCKMAP: SockMap = SockMap::with_max_entries(1, 0);
+
+#[stream_parser]
+fn stream_parser(ctx: SkBuffContext) -> u32 {
+    match { try_stream_parser(ctx) } {
+        Ok(ret) => ret,
+        Err(ret) => ret,
+    }
+}
+
+fn try_stream_parser(ctx: SkBuffContext) -> Result<u32, u32> {
+    Ok(ctx.len())
+}
+
+#[stream_verdict]
+fn stream_verdict(ctx: SkBuffContext) -> u32 {
+    match unsafe { try_stream_verdict(ctx) } {
+        Ok(_) => sk_action::SK_PASS,
+        Err(_) => sk_action::SK_DROP,
+    }
+}
+
+unsafe fn try_stream_verdict(ctx: SkBuffContext) -> Result<u32, u32> {
+    match SOCKMAP.redirect_skb(&ctx, 0, 0) as u32 {
+        sk_action::SK_PASS => Ok(sk_action::SK_PASS),
+        sk_action::SK_DROP => Err(sk_action::SK_DROP),
+        _ => Err(sk_action::SK_DROP),
+    }
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    unsafe { core::hint::unreachable_unchecked() }
+}

echo/echo-tokio/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "echo-tokio"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+tokio = { version = "1.9.0", features = ["full"] }

echo/echo-tokio/src/main.rs

@@ -0,0 +1,34 @@
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::TcpListener;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let listener = TcpListener::bind("127.0.0.1:41234").await?;
+
+    loop {
+        let (mut socket, _) = listener.accept().await?;
+
+        tokio::spawn(async move {
+            let mut buf = [0; 65535];
+
+            // In a loop, read data from the socket and write the data back.
+            loop {
+                let n = match socket.read(&mut buf).await {
+                    // socket closed
+                    Ok(n) if n == 0 => return,
+                    Ok(n) => n,
+                    Err(e) => {
+                        eprintln!("failed to read from socket; err = {:?}", e);
+                        return;
+                    }
+                };
+
+                // Write the data back
+                if let Err(e) = socket.write_all(&buf[0..n]).await {
+                    eprintln!("failed to write to socket; err = {:?}", e);
+                    return;
+                }
+            }
+        });
+    }
+}

echo/echo/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "echo"
+version = "0.1.0"
+edition = "2018"
+publish = false
+
+[dependencies]
+aya = { git = "https://github.com/aya-rs/aya", branch="main" }
+anyhow = "1.0.42"
+ctrlc = "3.2"
+structopt = { version = "0.3"}
+tokio = { version = "1.9.0", features = ["full"] }
+
+[[bin]]
+name = "echo"
+path = "src/main.rs"

echo/echo/src/main.rs

@@ -0,0 +1,46 @@
+use aya::maps::{MapRefMut, SockMap};
+use aya::programs::SkSkb;
+use aya::{include_bytes_aligned, Bpf};
+use tokio::io::AsyncReadExt;
+use tokio::signal;
+
+use std::convert::{TryFrom, TryInto};
+
+use tokio::net::TcpListener;
+
+#[tokio::main]
+async fn main() -> Result<(), anyhow::Error> {
+    #[cfg(debug_assertions)]
+    let mut bpf = Bpf::load(include_bytes_aligned!(
+        "../../target/bpfel-unknown-none/debug/echo"
+    ))?;
+    #[cfg(not(debug_assertions))]
+    let mut bpf = Bpf::load(include_bytes_aligned!(
+        "../../target/bpfel-unknown-none/release/echo"
+    ))?;
+    let mut sock_map = SockMap::<MapRefMut>::try_from(bpf.map_mut("sockmap")?)?;
+
+    let parser: &mut SkSkb = bpf.program_mut("stream_parser")?.try_into()?;
+    parser.load()?;
+    parser.attach(&sock_map)?;
+
+    let verdict: &mut SkSkb = bpf.program_mut("stream_verdict")?.try_into()?;
+    verdict.load()?;
+    verdict.attach(&sock_map)?;
+
+    let listener = TcpListener::bind("127.0.0.1:41234").await?;
+
+    println!("Server Listening on {}", listener.local_addr().unwrap());
+    // TODO: currently this will only accept one connection at a time. add up to map max_entries handlers
+    tokio::spawn(async move {
+        loop {
+            let (mut socket, _) = listener.accept().await.unwrap();
+            sock_map.set(0, &socket, 0).unwrap();
+            let mut buf = [0; 0];
+            socket.read(&mut buf[..]).await.unwrap();
+            sock_map.clear_index(&0).unwrap();
+        }
+    });
+    signal::ctrl_c().await?;
+    Ok(())
+}

echo/xtask/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "xtask"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+structopt = {version = "0.3", default-features = false }
+anyhow = "1"

echo/xtask/src/build_ebpf.rs

@@ -0,0 +1,64 @@
+use std::path::PathBuf;
+use std::process::Command;
+
+use structopt::StructOpt;
+
+#[derive(Debug, Copy, Clone)]
+pub enum Architecture {
+    BpfEl,
+    BpfEb,
+}
+
+impl std::str::FromStr for Architecture {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "bpfel-unknown-none" => Architecture::BpfEl,
+            "bpfeb-unknown-none" => Architecture::BpfEb,
+            _ => return Err("invalid target".to_owned()),
+        })
+    }
+}
+
+impl std::fmt::Display for Architecture {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            Architecture::BpfEl => "bpfel-unknown-none",
+            Architecture::BpfEb => "bpfeb-unknown-none",
+        })
+    }
+}
+
+#[derive(StructOpt)]
+pub struct Options {
+    /// Set the endianness of the BPF target
+    #[structopt(default_value = "bpfel-unknown-none", long)]
+    pub target: Architecture,
+    /// Build the release target
+    #[structopt(long)]
+    pub release: bool,
+}
+
+pub fn build_ebpf(opts: Options) -> Result<(), anyhow::Error> {
+    let dir = PathBuf::from("echo-ebpf");
+    let target = format!("--target={}", opts.target);
+    let mut args = vec![
+        "+nightly",
+        "build",
+        "--verbose",
+        target.as_str(),
+        "-Z",
+        "build-std=core",
+    ];
+    if opts.release {
+        args.push("--release")
+    }
+    let status = Command::new("cargo")
+        .current_dir(&dir)
+        .args(&args)
+        .status()
+        .expect("failed to build bpf program");
+    assert!(status.success());
+    Ok(())
+}

echo/xtask/src/main.rs

@@ -0,0 +1,32 @@
+mod build_ebpf;
+mod run;
+
+use std::process::exit;
+
+use structopt::StructOpt;
+#[derive(StructOpt)]
+pub struct Options {
+    #[structopt(subcommand)]
+    command: Command,
+}
+
+#[derive(StructOpt)]
+enum Command {
+    BuildEbpf(build_ebpf::Options),
+    Run(run::Options),
+}
+
+fn main() {
+    let opts = Options::from_args();
+
+    use Command::*;
+    let ret = match opts.command {
+        BuildEbpf(opts) => build_ebpf::build_ebpf(opts),
+        Run(opts) => run::run(opts),
+    };
+
+    if let Err(e) = ret {
+        eprintln!("{:#}", e);
+        exit(1);
+    }
+}