Add Vss KVStore api.

Author: G8XSU

rust/api/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+async-trait = "0.1.77"
 prost = { version = "0.11.6", default-features = false, features = ["std", "prost-derive"] }
 bytes = "1.4.0"
 

rust/api/src/error.rs

@@ -0,0 +1,65 @@
+use std::error::Error;
+use std::fmt::{Display, Formatter};
+use std::io;
+/// When there is an error while writing to VSS storage, the response contains a relevant error code.
+/// A mapping for VSS server error codes. Refer to [`ErrorResponse`] docs for more
+/// information regarding each error code and corresponding use-cases.
+///
+/// [`ErrorResponse`]: crate::types::ErrorResponse
+#[derive(Debug)]
+pub enum VssError {
+	/// Please refer to [`ErrorCode::NoSuchKeyException`].
+	///
+	/// [`ErrorCode::NoSuchKeyException`]: crate::types::ErrorCode::NoSuchKeyException
+	NoSuchKeyError(String),
+
+	/// Please refer to [`ErrorCode::InvalidRequestException`].
+	///
+	/// [`ErrorCode::InvalidRequestException`]: crate::types::ErrorCode::InvalidRequestException
+	InvalidRequestError(String),
+
+	/// Please refer to [`ErrorCode::ConflictException`].
+	///
+	/// [`ErrorCode::ConflictException`]: crate::types::ErrorCode::ConflictException
+	ConflictError(String),
+
+	/// Please refer to [`ErrorCode::AuthException`].
+	///
+	/// [`ErrorCode::AuthException`]: crate::types::ErrorCode::AuthException
+	AuthError(String),
+
+	/// Please refer to [`ErrorCode::InternalServerException`].
+	///
+	/// [`ErrorCode::InternalServerException`]: crate::types::ErrorCode::InternalServerException
+	InternalServerError(String),
+}
+
+impl Display for VssError {
+	fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+		match self {
+			VssError::NoSuchKeyError(message) => {
+				write!(f, "Requested key does not exist: {}", message)
+			},
+			VssError::InvalidRequestError(message) => {
+				write!(f, "Request sent to VSS was invalid: {}", message)
+			},
+			VssError::ConflictError(message) => {
+				write!(f, "Version conflict in write operation: {}", message)
+			},
+			VssError::AuthError(message) => {
+				write!(f, "Authentication or Authorization failure: {}", message)
+			},
+			VssError::InternalServerError(message) => {
+				write!(f, "InternalServerError: {}", message)
+			},
+		}
+	}
+}
+
+impl Error for VssError {}
+
+impl From<io::Error> for VssError {
+	fn from(err: io::Error) -> Self {
+		VssError::InternalServerError(err.to_string())
+	}
+}

rust/api/src/kv_store.rs

@@ -0,0 +1,33 @@
+use crate::error::VssError;
+use crate::types::{
+	DeleteObjectRequest, DeleteObjectResponse, GetObjectRequest, GetObjectResponse,
+	ListKeyVersionsRequest, ListKeyVersionsResponse, PutObjectRequest, PutObjectResponse,
+};
+use async_trait::async_trait;
+
+pub(crate) const GLOBAL_VERSION_KEY: &str = "global_version";
+pub(crate) const INITIAL_RECORD_VERSION: i32 = 1;
+
+/// An interface that must be implemented by every backend implementation of VSS.
+#[async_trait]
+pub trait KvStore: Send + Sync {
+	/// Retrieves an object based on the provided request and user token.
+	async fn get(
+		&self, user_token: String, request: GetObjectRequest,
+	) -> Result<GetObjectResponse, VssError>;
+
+	/// Stores an object with the provided request and user token.
+	async fn put(
+		&self, user_token: String, request: PutObjectRequest,
+	) -> Result<PutObjectResponse, VssError>;
+
+	/// Deletes an object based on the provided request and user token.
+	async fn delete(
+		&self, user_token: String, request: DeleteObjectRequest,
+	) -> Result<DeleteObjectResponse, VssError>;
+
+	/// Lists the versions of keys based on the provided request and user token.
+	async fn list_key_versions(
+		&self, user_token: String, request: ListKeyVersionsRequest,
+	) -> Result<ListKeyVersionsResponse, VssError>;
+}

rust/api/src/lib.rs

@@ -1 +1,21 @@
+//! Hosts API contract for VSS.
+//!
+//! VSS is an open-source project designed to offer a server-side cloud storage solution specifically
+//! tailored for noncustodial Lightning supporting mobile wallets. Its primary objective is to
+//! simplify the development process for Lightning wallets by providing a secure means to store
+//! and manage the essential state required for Lightning Network (LN) operations.
+
+#![deny(rustdoc::broken_intra_doc_links)]
+#![deny(rustdoc::private_intra_doc_links)]
+#![deny(missing_docs)]
+
+/// Implements the error type ([`error::VssError`]) which is eventually converted to [`ErrorResponse`] and returned to the client.
+///
+/// [`ErrorResponse`]: types::ErrorResponse
+pub mod error;
+
+/// Contains [`kv_store::KvStore`] interface which needs to be implemented by every backend implementation of VSS.
+pub mod kv_store;
+
+/// Contains request/response types generated from the API definition of VSS.
 pub mod types;