wolfssl-src 0.2.0

//! Compile wolfSSL from source.
//!
//! This crate provides a [`Build`] API for compiling the wolfSSL C library
//! from source via the [`cc`] crate.  It is used by `wolfcrypt-sys` when
//! the `vendored` feature is enabled (similar to the `openssl-src` /
//! `openssl-sys` pattern).
//!
//! # Usage
//!
//! ```rust,no_run
//! let artifacts = wolfssl_src::Build::new().build();
//! println!("lib dir: {}", artifacts.lib_dir.display());
//! println!("include dir: {}", artifacts.include_dir.display());
//! ```
//!
//! The builder discovers wolfSSL sources in order:
//! 1. `source_dir()` programmatic override
//! 2. `WOLFSSL_SRC` environment variable
//! 3. Bundled submodule at `wolfssl-src/wolfssl/` (present after `git submodule update --init`)
//! 4. `pkg-config` (looks for a `wolfssl` package whose prefix contains source files)

use std::collections::HashSet;
use std::env;
use std::io::BufRead;
use std::path::{Path, PathBuf};

/// Result of a successful wolfSSL build.
pub struct Artifacts {
    /// Directory containing the compiled `libwolfssl.a`.
    pub lib_dir: PathBuf,
    /// wolfSSL source root — use as `-I` path for headers.
    pub include_dir: PathBuf,
    /// Directory containing `user_settings.h` — use as `-I` path.
    pub settings_include_dir: PathBuf,
    /// Parsed `#define` names from `user_settings.h`.
    pub defines: HashSet<String>,
}

/// Builder for compiling wolfSSL from source.
pub struct Build {
    /// Path to the wolfSSL source tree.
    source_dir: Option<PathBuf>,
    /// Enable FIPS build.
    fips: bool,
}

impl Build {
    pub fn new() -> Self {
        Build {
            source_dir: None,
            fips: false,
        }
    }

    /// Set the path to the wolfSSL source tree.
    /// If not set, defaults to `WOLFSSL_SRC` env var, then the bundled submodule, then `pkg-config`.
    pub fn source_dir(&mut self, dir: PathBuf) -> &mut Self {
        self.source_dir = Some(dir);
        self
    }

    /// Enable FIPS 140-3 build.
    pub fn fips(&mut self, enable: bool) -> &mut Self {
        self.fips = enable;
        self
    }

    /// Compile wolfSSL and return artifact paths.
    pub fn build(&self) -> Artifacts {
        let wolfssl_dir = self.resolve_source_dir();
        let settings_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));

        // Select user_settings header based on active feature.
        // Priority: cryptocb-pure > cryptocb-only > riscv-bare-metal > default.
        let user_settings_name = if cfg!(feature = "cryptocb-pure") {
            "user_settings_cryptocb_pure.h"
        } else if cfg!(feature = "cryptocb-only") {
            "user_settings_cryptocb_only.h"
        } else if cfg!(feature = "riscv-bare-metal") {
            "user_settings_riscv.h"
        } else {
            "user_settings.h"
        };
        let user_settings_path = settings_dir.join(user_settings_name);
        let mut defines = parse_defines(&user_settings_path);
        if self.fips {
            let fips_path = settings_dir.join("user_settings_fips.h");
            if !fips_path.exists() {
                panic!(
                    "FIPS build requested but {} does not exist. \
                     Create it with the required FIPS #defines.",
                    fips_path.display()
                );
            }
            defines.extend(parse_defines(&fips_path));
        }

        // Collect source files
        let wolfcrypt_src = wolfssl_dir.join("wolfcrypt").join("src");
        let ssl_src = wolfssl_dir.join("src");

        let mut wolfcrypt_sources: Vec<&str> = if cfg!(feature = "cryptocb-pure") {
            CRYPTOCB_PURE_CORE_SOURCES.to_vec()
        } else if cfg!(feature = "cryptocb-only") {
            CRYPTOCB_ONLY_CORE_SOURCES.to_vec()
        } else {
            CORE_WOLFCRYPT_SOURCES.to_vec()
        };
        if self.fips {
            wolfcrypt_sources.extend_from_slice(FIPS_WOLFCRYPT_SOURCES);
        }
        if cfg!(feature = "cryptocb-pure") {
            append_cryptocb_pure_sources(&defines, &mut wolfcrypt_sources);
        } else if cfg!(feature = "cryptocb-only") {
            append_cryptocb_only_sources(&defines, &mut wolfcrypt_sources);
        } else {
            append_conditional_wolfcrypt_sources(&defines, &mut wolfcrypt_sources);
        }
        // cryptocb-only and cryptocb-pure: no SSL layer (no OPENSSL_EXTRA).
        // riscv-bare-metal: also no SSL layer (bare-metal builds are cryptocb-based).
        // Full builds: compile all ssl/ sources.
        let ssl_srcs: &[&str] = if cfg!(any(
            feature = "cryptocb-pure",
            feature = "cryptocb-only",
            feature = "riscv-bare-metal",
        )) {
            &[]
        } else {
            ssl_sources(&defines)
        };

        // Compile
        let mut build = cc::Build::new();
        build.include(&wolfssl_dir);

        // For bare-metal features, shadow the default user_settings.h with the
        // selected header so wolfSSL picks it up via -I ordering.
        // Priority: cryptocb-pure > cryptocb-only > riscv-bare-metal.
        if cfg!(any(
            feature = "riscv-bare-metal",
            feature = "cryptocb-only",
            feature = "cryptocb-pure"
        )) {
            let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
            let src_name = if cfg!(feature = "cryptocb-pure") {
                "user_settings_cryptocb_pure.h"
            } else if cfg!(feature = "cryptocb-only") {
                "user_settings_cryptocb_only.h"
            } else {
                "user_settings_riscv.h"
            };
            let src = settings_dir.join(src_name);
            let dst = out_dir.join("user_settings.h");
            std::fs::copy(&src, &dst).unwrap_or_else(|e| panic!("failed to copy {src_name}: {e}"));
            // OUT_DIR comes first so its user_settings.h takes precedence.
            build.include(&out_dir);

            // Add bare-metal stub headers (stdio.h, etc.) if available.
            if let Ok(stubs) = env::var("WOLFSSL_BARE_METAL_STUBS") {
                build.include(stubs);
            }

            // Compile bare-metal helper functions (string stubs used by both
            // user_settings_riscv.h and user_settings_cryptocb_only.h).
            let helpers = settings_dir.join("riscv_bare_metal_helpers.c");
            if helpers.exists() {
                build.file(&helpers);
                println!("cargo:rerun-if-changed={}", helpers.display());
            }
        }
        build.include(&settings_dir);

        build.define("WOLFSSL_USER_SETTINGS", None);
        if self.fips {
            build.define("HAVE_FIPS", None);
        }

        // Patch overlay: prefer files in `patches/` over the upstream source.
        // This carries local fixes (e.g. sp_521_div_9 quotient-correction) without
        // modifying the upstream wolfSSL tree.
        let patches_dir = settings_dir.join("patches");
        for src in &wolfcrypt_sources {
            let patched = patches_dir.join(src);
            let path = if patched.exists() {
                patched
            } else {
                let upstream = wolfcrypt_src.join(src);
                if !upstream.exists() {
                    panic!(
                        "required wolfcrypt source not found: {}",
                        upstream.display()
                    );
                }
                upstream
            };
            build.file(&path);
            println!("cargo:rerun-if-changed={}", path.display());
        }
        for src in ssl_srcs {
            let path = ssl_src.join(src);
            if !path.exists() {
                panic!("required wolfssl source not found: {}", path.display());
            }
            build.file(&path);
            println!("cargo:rerun-if-changed={}", path.display());
        }

        build.warnings(false);
        build.opt_level(2);
        build.compile("wolfssl");

        println!("cargo:rerun-if-changed={}", user_settings_path.display());
        println!("cargo:rerun-if-changed={}", patches_dir.display());
        if self.fips {
            println!(
                "cargo:rerun-if-changed={}",
                settings_dir.join("user_settings_fips.h").display()
            );
        }

        Artifacts {
            lib_dir: PathBuf::from(env::var("OUT_DIR").unwrap()),
            include_dir: wolfssl_dir,
            settings_include_dir: settings_dir,
            defines,
        }
    }

    fn resolve_source_dir(&self) -> PathBuf {
        // 1. Programmatic override
        if let Some(ref dir) = self.source_dir {
            if !dir.exists() {
                panic!("wolfssl source dir does not exist: {}", dir.display());
            }
            return dir.clone();
        }

        // 2. WOLFSSL_SRC env var
        if let Ok(dir) = env::var("WOLFSSL_SRC")
            && !dir.is_empty()
        {
            let path = PathBuf::from(&dir);
            if !path.exists() {
                panic!("WOLFSSL_SRC={dir} does not exist");
            }
            return path;
        }

        // 3. Bundled submodule (wolfssl-src/wolfssl/ inside this crate)
        let bundled = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("wolfssl");
        if bundled.join("wolfcrypt/src").exists() {
            return bundled;
        }

        // 4. pkg-config
        if let Some(dir) = Self::find_via_pkg_config() {
            return dir;
        }

        panic!(
            "wolfSSL source not found. Either:\n  \
             - Run: git submodule update --init\n  \
             - Set WOLFSSL_SRC to the path of your wolfssl checkout\n  \
             - Install wolfssl-dev so that pkg-config can find it"
        );
    }

    /// Try to locate wolfSSL source via `pkg-config`.
    ///
    /// Queries `pkg-config --variable=prefix wolfssl` and checks whether the
    /// returned prefix contains a wolfSSL source tree (i.e. `wolfcrypt/src/`
    /// exists under it).  Falls back to the include directory if the prefix
    /// doesn't contain source files — some installs place the full tree
    /// under the include root.
    fn find_via_pkg_config() -> Option<PathBuf> {
        // Try the prefix first (works for source-tree installs like
        // ./configure --prefix=/opt/wolfssl && make install)
        if let Some(prefix) = pkg_config_var("prefix") {
            let path = PathBuf::from(&prefix);
            if path.join("wolfcrypt").join("src").exists() {
                return Some(path);
            }
        }

        // Fall back to includedir — strip the trailing /include (or
        // /include/wolfssl) to get the root.
        if let Some(incdir) = pkg_config_var("includedir") {
            let path = PathBuf::from(&incdir);
            // Try <includedir>/../ (e.g. /usr/local/include → /usr/local)
            if let Some(parent) = path.parent()
                && parent.join("wolfcrypt").join("src").exists()
            {
                return Some(parent.to_path_buf());
            }
        }

        None
    }
}

/// Query a pkg-config variable for the `wolfssl` package.
fn pkg_config_var(var: &str) -> Option<String> {
    let output = std::process::Command::new("pkg-config")
        .args(["--variable", var, "wolfssl"])
        .output()
        .ok()?;
    if !output.status.success() {
        return None;
    }
    let val = String::from_utf8(output.stdout).ok()?;
    let val = val.trim();
    if val.is_empty() {
        None
    } else {
        Some(val.to_string())
    }
}

impl Default for Build {
    fn default() -> Self {
        Self::new()
    }
}

// ================================================================
// Settings parser
// ================================================================

/// Parse a C header and return all `#define`d macro names.
///
/// Flat scan — does not evaluate `#if`/`#ifdef` guards.
pub fn parse_defines(path: &Path) -> HashSet<String> {
    let file =
        std::fs::File::open(path).unwrap_or_else(|e| panic!("cannot open {}: {e}", path.display()));
    let reader = std::io::BufReader::new(file);
    let mut defines = HashSet::new();
    for line in reader.lines() {
        let line = line.expect("read error");
        let trimmed = line.trim();
        let Some(rest) = trimmed.strip_prefix('#') else {
            continue;
        };
        let rest = rest.trim_start();
        let Some(rest) = rest.strip_prefix("define") else {
            continue;
        };
        if !rest.starts_with(|c: char| c.is_ascii_whitespace()) {
            continue;
        }
        let name = rest
            .trim_start()
            .split(|c: char| !c.is_ascii_alphanumeric() && c != '_')
            .next()
            .unwrap_or("");
        if !name.is_empty() {
            defines.insert(name.to_string());
        }
    }
    defines
}

// ================================================================
// Source file lists
// ================================================================

const CORE_WOLFCRYPT_SOURCES: &[&str] = &[
    "aes.c",
    "arc4.c",
    "asn.c",
    "blake2b.c",
    "blake2s.c",
    "camellia.c",
    "cmac.c",
    "coding.c",
    "cpuid.c",
    "cryptocb.c",
    "dsa.c",
    "error.c",
    "hash.c",
    "logging.c",
    "md4.c",
    "md5.c",
    "memory.c",
    "pkcs7.c",
    "pkcs12.c",
    "random.c",
    "sha.c",
    "sha256.c",
    "signature.c",
    "sp_int.c",
    "sp_c32.c",
    "sp_c64.c",
    "srp.c",
    "wc_encrypt.c",
    "wc_port.c",
    "wolfmath.c",
];

const FIPS_WOLFCRYPT_SOURCES: &[&str] = &[
    "fips.c",
    "fips_test.c",
    "wolfcrypt_first.c",
    "wolfcrypt_last.c",
];

/// Core source files for a `cryptocb-only` build.
///
/// Excludes everything that is not needed when all cryptographic operations
/// are handled by CryptoCb callbacks:
///
/// - `sp_int.c`, `sp_c32.c`, `sp_c64.c` — SP big-integer math (the largest
///   contributors to code size; only needed for software ECC/RSA/DH).
/// - `wolfmath.c` — legacy mp_int math (same reason).
/// - `arc4.c`, `blake2b.c`, `blake2s.c`, `camellia.c`, `cmac.c` — unused
///   algorithms.
/// - `dsa.c`, `md4.c`, `md5.c` — disabled by NO_DSA / NO_MD4 / NO_MD5.
/// - `pkcs7.c`, `pkcs12.c`, `srp.c` — certificate containers not used in
///   firmware.
///
/// Keeps: `cryptocb.c` (mandatory), `wc_port.c` (platform), `error.c`,
/// `memory.c`, `logging.c`, `random.c` (DRBG structure), `hash.c` (routing),
/// `sha.c`, `sha256.c`, `aes.c`, `asn.c`, `coding.c`, `signature.c`,
/// `wc_encrypt.c`, `cpuid.c`.
const CRYPTOCB_ONLY_CORE_SOURCES: &[&str] = &[
    "aes.c",
    "asn.c",
    "coding.c",
    "cpuid.c",
    "cryptocb.c",
    "error.c",
    "hash.c",
    "logging.c",
    "memory.c",
    "random.c",
    "sha.c",
    "sha256.c",
    "signature.c",
    "wc_encrypt.c",
    "wc_port.c",
];

/// Core source files for a `cryptocb-pure` build.
///
/// Subset of [`CRYPTOCB_ONLY_CORE_SOURCES`] — removes everything not needed
/// when wolfSSL is used purely as a CryptoCb routing layer with no higher-level
/// API calls (no OpenSSL compat, no HKDF, no ASN.1 parser, no CPU feature
/// detection, no high-level encrypt/signature wrappers):
///
/// - `asn.c` — ASN.1 parser (absent: no WOLFSSL_ASN_TEMPLATE, no key import/export)
/// - `coding.c` — base64 encoding (absent: not needed for callback dispatch)
/// - `cpuid.c` — CPU feature detection (absent: not needed for bare-metal CryptoCb)
/// - `signature.c` — signature wrappers (absent: NO_SIG_WRAPPER is defined)
/// - `wc_encrypt.c` — high-level encrypt wrappers (absent: not needed for CryptoCb)
///
/// The ssl.c layer is also excluded (no OPENSSL_EXTRA).
const CRYPTOCB_PURE_CORE_SOURCES: &[&str] = &[
    "aes.c",
    "cryptocb.c",
    "error.c",
    "hash.c",
    "logging.c",
    "memory.c",
    "random.c",
    "sha.c",
    "sha256.c",
    "wc_port.c",
];

/// Append the minimal set of conditional wolfcrypt sources for a
/// `cryptocb-only` build.
///
/// Only sources that provide type definitions or CryptoCb dispatch glue
/// for algorithms used by wolfcrypt-dpe are included.  All heavy algorithm
/// implementations (RSA, DH, Dilithium, ML-KEM, SHA-3, Ed25519, ChaCha, etc.)
/// are omitted.
fn append_cryptocb_only_sources(defines: &HashSet<String>, sources: &mut Vec<&'static str>) {
    // HMAC: needed for the Hmac struct layout and CryptoCb HMAC dispatch glue.
    if !defines.contains("NO_HMAC") {
        sources.push("hmac.c");
    }
    // SHA-384/SHA-512: needed for the wc_Sha384/wc_Sha512 struct layouts.
    if defines.contains("WOLFSSL_SHA512") || defines.contains("WOLFSSL_SHA384") {
        sources.push("sha512.c");
    }
    // ECC: needed for the ecc_key struct layout and CryptoCb ECC dispatch glue.
    if defines.contains("HAVE_ECC") {
        sources.push("ecc.c");
    }
    // HKDF: pure HMAC-based KDF; HMAC calls go through CryptoCb.
    if defines.contains("HAVE_HKDF") {
        sources.push("kdf.c");
    }
    // EVP API: required when OPENSSL_EXTRA is set for wolfcrypt-rs Rust bindings.
    if defines.contains("OPENSSL_EXTRA") || defines.contains("OPENSSL_ALL") {
        sources.push("evp.c");
    }
}

/// Append conditional wolfcrypt sources for a `cryptocb-pure` build.
///
/// Same algorithm-type guards as `cryptocb-only` but with OPENSSL_EXTRA and
/// HAVE_HKDF absent, so `evp.c` and `kdf.c` are never added.
fn append_cryptocb_pure_sources(defines: &HashSet<String>, sources: &mut Vec<&'static str>) {
    // HMAC: needed for the Hmac struct layout and CryptoCb HMAC dispatch glue.
    if !defines.contains("NO_HMAC") {
        sources.push("hmac.c");
    }
    // SHA-384/512: needed for the wc_Sha384/wc_Sha512 struct layouts.
    if defines.contains("WOLFSSL_SHA512") || defines.contains("WOLFSSL_SHA384") {
        sources.push("sha512.c");
    }
    // ECC: needed for the ecc_key struct layout and CryptoCb ECC dispatch glue.
    if defines.contains("HAVE_ECC") {
        sources.push("ecc.c");
    }
    // No evp.c: OPENSSL_EXTRA is not defined in user_settings_cryptocb_pure.h.
    // No kdf.c: HAVE_HKDF is not defined in user_settings_cryptocb_pure.h.
}

fn append_conditional_wolfcrypt_sources(
    defines: &HashSet<String>,
    sources: &mut Vec<&'static str>,
) {
    if defines.contains("HAVE_CHACHA") {
        sources.push("chacha.c");
    }
    if defines.contains("HAVE_CHACHA") && defines.contains("HAVE_POLY1305") {
        sources.push("chacha20_poly1305.c");
    }
    if defines.contains("HAVE_POLY1305") {
        sources.push("poly1305.c");
    }
    if defines.contains("HAVE_ECC") {
        sources.push("ecc.c");
    }
    if defines.contains("HAVE_ED25519") || defines.contains("HAVE_CURVE25519") {
        sources.push("curve25519.c");
        sources.push("fe_operations.c");
        sources.push("ge_operations.c");
    }
    if defines.contains("HAVE_ED25519") {
        sources.push("ed25519.c");
    }
    if defines.contains("HAVE_ED448") || defines.contains("HAVE_CURVE448") {
        sources.push("curve448.c");
        sources.push("fe_448.c");
        sources.push("ge_448.c");
    }
    if defines.contains("HAVE_ED448") {
        sources.push("ed448.c");
    }
    if !defines.contains("NO_DH") {
        sources.push("dh.c");
    }
    if !defines.contains("NO_RSA") {
        sources.push("rsa.c");
    }
    if !defines.contains("NO_HMAC") {
        sources.push("hmac.c");
    }
    if !defines.contains("NO_DES3") {
        sources.push("des3.c");
    }
    if defines.contains("WOLFSSL_SHA3") {
        sources.push("sha3.c");
    }
    if defines.contains("WOLFSSL_SHA512") || defines.contains("WOLFSSL_SHA384") {
        sources.push("sha512.c");
    }
    if defines.contains("HAVE_DILITHIUM") {
        sources.push("dilithium.c");
    }
    if defines.contains("WOLFSSL_HAVE_MLKEM") {
        sources.push("wc_mlkem.c");
        sources.push("wc_mlkem_poly.c");
    }
    if defines.contains("HAVE_HKDF") {
        sources.push("kdf.c");
    }
    if defines.contains("HAVE_PBKDF2") {
        sources.push("pwdbased.c");
    }
    if defines.contains("OPENSSL_EXTRA") || defines.contains("OPENSSL_ALL") {
        sources.push("evp.c");
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::io::Write;

    #[test]
    fn parse_defines_basic() {
        let mut f = tempfile::NamedTempFile::new().unwrap();
        writeln!(f, "#define HAVE_ECC").unwrap();
        writeln!(f, "#define HAVE_AES").unwrap();
        writeln!(f, "#define WOLFSSL_SHA256").unwrap();
        writeln!(f, "// not a define").unwrap();
        writeln!(f, "int x = 5;").unwrap();
        let defs = parse_defines(f.path());
        assert!(defs.contains("HAVE_ECC"), "missing HAVE_ECC: {:?}", defs);
        assert!(defs.contains("HAVE_AES"), "missing HAVE_AES: {:?}", defs);
        assert!(
            defs.contains("WOLFSSL_SHA256"),
            "missing WOLFSSL_SHA256: {:?}",
            defs
        );
        assert_eq!(defs.len(), 3, "unexpected defines: {:?}", defs);
    }

    #[test]
    fn parse_defines_with_values() {
        let mut f = tempfile::NamedTempFile::new().unwrap();
        writeln!(f, "#define WOLFSSL_MAX_STRENGTH 1").unwrap();
        writeln!(f, "#define HAVE_FIPS_VERSION 5").unwrap();
        let defs = parse_defines(f.path());
        assert!(defs.contains("WOLFSSL_MAX_STRENGTH"));
        assert!(defs.contains("HAVE_FIPS_VERSION"));
    }

    #[test]
    fn parse_defines_ignores_non_defines() {
        let mut f = tempfile::NamedTempFile::new().unwrap();
        writeln!(f, "#include <stdio.h>").unwrap();
        writeln!(f, "#ifdef HAVE_ECC").unwrap();
        writeln!(f, "#endif").unwrap();
        writeln!(f, "void foo(void);").unwrap();
        let defs = parse_defines(f.path());
        assert!(defs.is_empty(), "should have no defines: {:?}", defs);
    }

    #[test]
    fn parse_defines_empty_file() {
        let f = tempfile::NamedTempFile::new().unwrap();
        let defs = parse_defines(f.path());
        assert!(defs.is_empty());
    }
}

fn ssl_sources(defines: &HashSet<String>) -> &'static [&'static str] {
    if defines.contains("OPENSSL_EXTRA") || defines.contains("OPENSSL_ALL") {
        &[
            "pk.c",
            "pk_ec.c",
            "pk_rsa.c",
            "ssl.c",
            "ssl_api_pk.c",
            "ssl_asn1.c",
            "ssl_bn.c",
            "ssl_crypto.c",
            "ssl_load.c",
            "ssl_misc.c",
            "ssl_sk.c",
        ]
    } else {
        &[]
    }
}