build.rs

fn main() {
    #[cfg(target_os = "windows")]
    download_windows_npcap_sdk().unwrap();

    let git_output = std::process::Command::new("git")
        .args(["rev-parse", "--git-dir"])
        .output()
        .ok();
    let git_dir = git_output.as_ref().and_then(|output| {
        std::str::from_utf8(&output.stdout)
            .ok()
            .and_then(|s| s.strip_suffix('\n').or_else(|| s.strip_suffix("\r\n")))
    });

    // Tell cargo to rebuild if the head or any relevant refs change.
    if let Some(git_dir) = git_dir {
        let git_path = std::path::Path::new(git_dir);
        let refs_path = git_path.join("refs");
        if git_path.join("HEAD").exists() {
            println!("cargo:rerun-if-changed={}/HEAD", git_dir);
        }
        if git_path.join("packed-refs").exists() {
            println!("cargo:rerun-if-changed={}/packed-refs", git_dir);
        }
        if refs_path.join("heads").exists() {
            println!("cargo:rerun-if-changed={}/refs/heads", git_dir);
        }
        if refs_path.join("tags").exists() {
            println!("cargo:rerun-if-changed={}/refs/tags", git_dir);
        }
    }

    let git_output = std::process::Command::new("git")
        .args(["describe", "--always", "--tags", "--long", "--dirty"])
        .output()
        .ok();
    let git_info = git_output
        .as_ref()
        .and_then(|output| std::str::from_utf8(&output.stdout).ok().map(str::trim));
    let cargo_pkg_version = env!("CARGO_PKG_VERSION");

    // Default git_describe to cargo_pkg_version
    let mut git_describe = String::from(cargo_pkg_version);

    if let Some(git_info) = git_info {
        // If the `git_info` contains `CARGO_PKG_VERSION`, we simply use `git_info` as it is.
        // Otherwise, prepend `CARGO_PKG_VERSION` to `git_info`.
        if git_info.contains(cargo_pkg_version) {
            // Remove the 'g' before the commit sha
            let git_info = &git_info.replace('g', "");
            git_describe = git_info.to_string();
        } else {
            git_describe = format!("v{}-{}", cargo_pkg_version, git_info);
        }
    }

    println!("cargo:rustc-env=_GIT_INFO={}", git_describe);
}

// -- unfortunately netscanner need to download sdk because of Packet.lib for build locally
#[cfg(target_os = "windows")]
fn download_windows_npcap_sdk() -> anyhow::Result<()> {
    use anyhow::anyhow;

    use std::{
        env, fs,
        io::{self, Write},
        path::PathBuf,
    };

    use http_req::request;
    use zip::ZipArchive;

    println!("cargo:rerun-if-changed=build.rs");

    // get npcap SDK
    const NPCAP_SDK: &str = "npcap-sdk-1.13.zip";

    let npcap_sdk_download_url = format!("https://npcap.com/dist/{NPCAP_SDK}");
    let cache_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR")?).join("target");
    let npcap_sdk_cache_path = cache_dir.join(NPCAP_SDK);

    let npcap_zip = match fs::read(&npcap_sdk_cache_path) {
        // use cached
        Ok(zip_data) => {
            eprintln!("Found cached npcap SDK");
            zip_data
        }
        // download SDK
        Err(_) => {
            eprintln!("Downloading npcap SDK");

            // download
            let mut zip_data = vec![];
            let _res = request::get(npcap_sdk_download_url, &mut zip_data)?;

            // write cache
            fs::create_dir_all(cache_dir)?;
            let mut cache = fs::File::create(npcap_sdk_cache_path)?;
            cache.write_all(&zip_data)?;

            zip_data
        }
    };

    // extract DLL
    let lib_path = if cfg!(target_arch = "aarch64") {
        "Lib/ARM64/Packet.lib"
    } else if cfg!(target_arch = "x86_64") {
        "Lib/x64/Packet.lib"
    } else if cfg!(target_arch = "x86") {
        "Lib/Packet.lib"
    } else {
        panic!("Unsupported target!")
    };
    let mut archive = ZipArchive::new(io::Cursor::new(npcap_zip))?;
    let mut npcap_lib = archive.by_name(lib_path)?;

    // write DLL
    let lib_dir = PathBuf::from(env::var("OUT_DIR")?).join("npcap_sdk");
    let lib_path = lib_dir.join("Packet.lib");
    fs::create_dir_all(&lib_dir)?;
    let mut lib_file = fs::File::create(lib_path)?;
    io::copy(&mut npcap_lib, &mut lib_file)?;

    println!(
        "cargo:rustc-link-search=native={}",
        lib_dir
            .to_str()
            .ok_or(anyhow!("{lib_dir:?} is not valid UTF-8"))?
    );

    Ok(())
}