From 32ca4ddc4cb3a347fabed22aa09eb4dd3f256197 Mon Sep 17 00:00:00 2001
From: Luca Barbato <lu_zero@gentoo.org>
Date: Wed, 23 Feb 2022 12:24:30 +0100
Subject: [PATCH] Initial C API

---
 dgc/Cargo.toml    |  4 +++
 dgc/cbindgen.toml |  9 +++++
 dgc/src/capi.rs   | 83 +++++++++++++++++++++++++++++++++++++++++++++++
 dgc/src/lib.rs    |  4 +++
 4 files changed, 100 insertions(+)
 create mode 100644 dgc/cbindgen.toml
 create mode 100644 dgc/src/capi.rs

diff --git a/dgc/Cargo.toml b/dgc/Cargo.toml
index 2b8615d..8b28a62 100644
--- a/dgc/Cargo.toml
+++ b/dgc/Cargo.toml
@@ -10,6 +10,9 @@ repository = "https://github.com/rust-italia/dgc"
 readme = "README.md"
 license = "MIT"
 
+[features]
+capi = ["libc"]
+
 [dependencies]
 base45 = "3.0.0"
 base64 = "0.13.0"
@@ -22,6 +25,7 @@ serde = "1.0.130"
 serde_json = "1.0.64"
 thiserror = "1.0.30"
 x509-parser = { version = "0.12.0", features = ["verify"] }
+libc = { version = "0.2", optional = true }
 
 [dev-dependencies]
 hex = "0.4.3"
diff --git a/dgc/cbindgen.toml b/dgc/cbindgen.toml
new file mode 100644
index 0000000..0c2ebd8
--- /dev/null
+++ b/dgc/cbindgen.toml
@@ -0,0 +1,9 @@
+include_guard = "DGC_H"
+include_version = true
+language = "C"
+cpp_compat = true
+
+[export.rename]
+"ParseError" = "DgcParseError"
+"SignatureValidity" = "DgcValidity"
+"TrustList" = "DgcTrustList"
diff --git a/dgc/src/capi.rs b/dgc/src/capi.rs
new file mode 100644
index 0000000..6196706
--- /dev/null
+++ b/dgc/src/capi.rs
@@ -0,0 +1,83 @@
+use crate::{DgcContainer, ParseError, SignatureValidity, TrustList};
+
+/// Decodes the certificate and returns the [`DgcContainer`] data contained in it.
+///
+/// This function is recommended when you don't want to validate the signature but you
+/// are just interested in reading the content of the certificate.
+#[no_mangle]
+pub extern "C" fn dgc_decode(
+    data: *const u8,
+    len: usize,
+    container: *mut *mut DgcContainer,
+) -> *const ParseError {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_container_free(container: *mut *mut DgcContainer) {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_trustlist_new() -> *mut TrustList {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_trustlist_default() -> *mut TrustList {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_trustlist_add_from_certificate(
+    list: *mut TrustList,
+    cert: *mut u8,
+    len: usize,
+) -> bool {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_trustlist_free(list: *mut *mut TrustList) {
+    todo!()
+}
+
+/// Parses and validates a given certificate.
+///
+/// This function is a high level helper that allows you to extract the data from a
+/// certificate and at the same time it tries to validate the signature against a given
+/// trustlist.
+///
+/// This function will return an error if the certificate cannot be parsed or is invalid.
+/// If the certificate can be parsed correctly, this function returns a tuple containing a
+/// [`DgcContainer`] and a [`SignatureValidity`].
+///
+/// This design allows for permissive validation of the certificate signature.
+/// In fact, `SignatureValidity` can be used to determine if the signature is valid and even if it is
+/// invalid (or the validity cannot be assessed) you could still access all the information
+/// in the certificate.
+#[no_mangle]
+pub extern "C" fn dgc_validate(
+    data: *const u8,
+    len: usize,
+    trustlist: *const TrustList,
+    container: *mut *mut DgcContainer,
+    validity: *mut *mut SignatureValidity,
+) -> *const ParseError {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_signature_is_valid(error: *const SignatureValidity) -> bool {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_container_to_json(container: *const DgcContainer) -> *mut u8 {
+    todo!()
+}
+
+#[no_mangle]
+pub extern "C" fn dgc_json_free(json: *mut *mut u8) {
+    todo!()
+}
diff --git a/dgc/src/lib.rs b/dgc/src/lib.rs
index a3e88be..448f534 100644
--- a/dgc/src/lib.rs
+++ b/dgc/src/lib.rs
@@ -10,6 +10,10 @@ mod test;
 mod trustlist;
 mod vaccination;
 mod valuesets;
+
+#[cfg(feature = "capi")]
+mod capi;
+
 pub use crate::dgc::*;
 pub use cwt::*;
 pub use dgc_container::*;