build: initial skeleton

Add initial build system integration.

crates/nss/Cargo.toml

@@ -0,0 +1,28 @@
+# SPDX-FileCopyrightText: Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
+# SPDX-License-Identifier: CC0-1.0
+
+[package]
+name = "parental-ctrls-nss"
+description = "linux-parental-controls: NSS module to block DNS queries to adult domains"
+
+license = { workspace = true }
+edition = { workspace = true }
+version = { workspace = true }
+authors = { workspace = true }
+homepage = { workspace = true }
+repository = { workspace = true }
+
+[lib]
+name = "nss_parental_ctrls"
+path = "src/lib.rs"
+crate-type = ["cdylib"]
+
+[profile.release]
+panic = "unwind" # We rely on this
+
+[build-dependencies]
+bindgen = { workspace = true }
+
+[dependencies]
+libc = { workspace = true }
+nix = { workspace = true }

crates/nss/build.rs

@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
+// SPDX-License-Identifier: EUPL-1.2
+
+use {std::env, std::path::PathBuf};
+
+fn main() {
+    println!("cargo:rerun-if-changed=wrapper.hpp");
+
+    // Required by NSS
+    println!("cargo:rustc-cdylib-link-arg=-Wl,-soname,libnss_parental_ctrls.so.2");
+
+    let bindings = bindgen::Builder::default()
+        .header("wrapper.hpp")
+        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
+        .newtype_enum("nss_status")
+        .allowlist_type("nss_status")
+        .newtype_enum("HErrno")
+        .allowlist_type("HErrno")
+        .newtype_enum("EaiRetcode")
+        .allowlist_type("EaiRetcode")
+        .allowlist_type("gaih_addrtuple")
+        .allowlist_function("__nss_configure_lookup")
+        .generate()
+        .expect("Unable to generate bindings");
+
+    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+    bindings
+        .write_to_file(out_path.join("bindings.rs"))
+        .expect("Couldn't write bindings!");
+}

crates/nss/src/helpers.rs

@@ -0,0 +1,8 @@
+// SPDX-FileCopyrightText: Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
+// SPDX-License-Identifier: EUPL-1.2
+
+pub fn set_if_valid<T>(ptr: *mut T, val: T) {
+    if !ptr.is_null() {
+        unsafe { *ptr = val };
+    }
+}

crates/nss/src/lib.rs

@@ -0,0 +1,133 @@
+// SPDX-FileCopyrightText: 2022 Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
+// SPDX-License-Identifier: EUPL-1.2
+
+mod helpers;
+mod nss_bindings;
+
+use {
+    crate::helpers::set_if_valid,
+    crate::nss_bindings::{HErrno, gaih_addrtuple, nss_status},
+    libc::{AF_INET, hostent, size_t, socklen_t},
+    nix::errno::Errno,
+    std::os::raw::{c_char, c_int, c_void},
+    std::ptr,
+};
+
+// -------------- by host ---------------
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _nss_parental_ctrls_gethostbyname4_r(
+    _name: *const c_char,
+    _pat: *mut *mut gaih_addrtuple,
+    _buffer: *mut c_char,
+    _buflen: size_t,
+    _errnop: *mut Errno,
+    _h_errnop: *mut HErrno,
+    _ttlp: *mut i32,
+) -> nss_status {
+    todo!()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _nss_parental_ctrls_gethostbyname3_r(
+    _name: *const c_char,
+    _af: c_int,
+    _host: *mut hostent,
+    _buffer: *mut c_char,
+    _buflen: size_t,
+    _errnop: *mut Errno,
+    _h_errnop: *mut HErrno,
+    _ttlp: *mut i32,
+    _canonp: *mut *mut char,
+) -> nss_status {
+    todo!()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _nss_parental_ctrls_gethostbyname2_r(
+    name: *const c_char,
+    af: c_int,
+    host: *mut hostent,
+    buffer: *mut c_char,
+    buflen: size_t,
+    errnop: *mut Errno,
+    h_errnop: *mut HErrno,
+) -> nss_status {
+    _nss_parental_ctrls_gethostbyname3_r(
+        name,
+        af,
+        host,
+        buffer,
+        buflen,
+        errnop,
+        h_errnop,
+        ptr::null_mut(),
+        ptr::null_mut(),
+    )
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _nss_parental_ctrls_gethostbyname_r(
+    name: *const c_char,
+    host: *mut hostent,
+    buffer: *mut c_char,
+    buflen: size_t,
+    errnop: *mut Errno,
+    h_errnop: *mut HErrno,
+) -> nss_status {
+    _nss_parental_ctrls_gethostbyname3_r(
+        name,
+        AF_INET,
+        host,
+        buffer,
+        buflen,
+        errnop,
+        h_errnop,
+        ptr::null_mut(),
+        ptr::null_mut(),
+    )
+}
+
+// ----------------- by addr -----------------
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _nss_parental_ctrls_gethostbyaddr2_r(
+    _addr: *const c_void,
+    _len: socklen_t,
+    _af: c_int,
+    _host: *mut hostent,
+    _buffer: *mut c_char,
+    _buflen: size_t,
+    errnop: *mut Errno,
+    h_errnop: *mut HErrno,
+    _ttlp: *mut i32,
+) -> nss_status {
+    set_if_valid(errnop, Errno::from_raw(0));
+    set_if_valid(h_errnop, HErrno::Success);
+
+    todo!()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _nss_parental_ctrls_gethostbyaddr_r(
+    addr: *const c_void,
+    len: socklen_t,
+    af: c_int,
+    host: *mut hostent,
+    buffer: *mut c_char,
+    buflen: size_t,
+    errnop: *mut Errno,
+    h_errnop: *mut HErrno,
+) -> nss_status {
+    _nss_parental_ctrls_gethostbyaddr2_r(
+        addr,
+        len,
+        af,
+        host,
+        buffer,
+        buflen,
+        errnop,
+        h_errnop,
+        ptr::null_mut(),
+    )
+}

crates/nss/src/nss_bindings.rs

@@ -0,0 +1,7 @@
+// SPDX-FileCopyrightText: Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
+// SPDX-License-Identifier: EUPL-1.2
+
+#![allow(dead_code)]
+#![allow(non_camel_case_types)]
+#![allow(non_upper_case_globals)]
+include!(concat!(env!("OUT_DIR"), "/bindings.rs"));

crates/nss/wrapper.hpp

@@ -0,0 +1,43 @@
+/*
+ * SPDX-FileCopyrightText: Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
+ * SPDX-License-Identifier: EUPL-1.2
+ */
+
+ #include <nss.h>
+ #include <netdb.h>
+
+ // Work around enums in netdb.h defined as macros instead :-p
+
+ enum class HErrno {
+     Success = 0,
+     HostNotFound = HOST_NOT_FOUND,
+     TryAgain = TRY_AGAIN,
+     NoRecovery = NO_RECOVERY,
+     NoData = NO_DATA,
+     #ifdef __USE_MISC
+     Internal = NETDB_INTERNAL,
+     #endif
+ };
+
+ enum class EaiRetcode {
+     Success = 0,
+     BadFlags = EAI_BADFLAGS,
+     NoName = EAI_NONAME,
+     Fail = EAI_FAIL,
+     Family = EAI_FAMILY,
+     SockType = EAI_SOCKTYPE,
+     Service = EAI_SERVICE,
+     Memory = EAI_MEMORY,
+     System = EAI_SYSTEM,
+     Overflow = EAI_OVERFLOW,
+     #ifdef __USE_GNU
+     NoData = EAI_NODATA,
+     AddrFamily = EAI_ADDRFAMILY,
+     InProgress = EAI_INPROGRESS,
+     Canceled = EAI_CANCELED,
+     NotCanceled = EAI_NOTCANCELED,
+     AllDone = EAI_ALLDONE,
+     Interrupted = EAI_INTR,
+     IdnEncode = EAI_IDN_ENCODE,
+     #endif /* __USE_GNU */
+ };