Add the first version of the context_id shared component.

Author: mikeconley

CHANGELOG.md

@@ -5,6 +5,10 @@
 ### Android
 - Added `RustComponentsInitializer.kt` to `init_rust_components`.
 
+### Context ID
+- Added the first version of a component for managing and rotating context IDs
+  sent to MARS / Merino.
+
 #### BREAKING CHANGE
 - Removed `Megazord.kt` and moved the contents to the new `RustComponentsInitializer.kt`.
 - 

Cargo.lock

@@ -4,6 +4,7 @@ resolver = "2"
 # Note: Any additions here should be repeated in default-members below.
 members = [
     "components/autofill",
+    "components/context_id",
     "components/crashtest",
     "components/example",
     #"components/example/cli",
@@ -94,6 +95,7 @@ exclude = [
 # use the full member set.
 default-members = [
     "components/autofill",
+    "components/context_id",
     "components/crashtest",
     "components/fxa-client",
     "components/init_rust_components",

Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "context_id"
+version = "0.1.0"
+edition = "2021"
+license = "MPL-2.0"
+
+[build-dependencies]
+uniffi = { version = "0.29.0", features=["build"]}
+
+[dependencies]
+chrono = "0.4"
+error-support = { path = "../support/error" }
+lazy_static = { version = "1.4" }
+log = "0.4"
+parking_lot = "0.12"
+serde = "1"
+serde_json = "1"
+thiserror = "1.0"
+uniffi = { version = "0.29.0" }
+url = "2"
+uuid = { version = "1.3", features = ["v4"]}
+viaduct = { path = "../viaduct" }
+
+[dev-dependencies]
+mockito = "0.31"
+viaduct-reqwest = { path = "../support/viaduct-reqwest" }

components/context_id/Cargo.toml

@@ -0,0 +1,19 @@
+# Context ID
+
+A context ID is a UUID that is used when making requests to MARS or to Merino to help reduce click fraud.
+
+The **Context ID Rust component** creates a shared mechanism for managing context IDs, and to allow them to be rotated after they have exceeded some age.
+
+It is currently under construction and not yet used.
+
+## Tests
+
+Tests are run with
+
+```shell
+cargo test -p context_id
+```
+
+## Bugs
+
+We use Bugzilla to track bugs and feature work. You can use [this link](bugzilla.mozilla.org/enter_bug.cgi?product=Firefox&component=New Tab Page) to file bugs in the `Firefox :: New Tab Page` bug component.

components/context_id/README.md

@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::error::ApiResult;
+
+#[uniffi::export(callback_interface)]
+pub trait ContextIdCallback: Sync + Send {
+    fn persist(&self, context_id: String, creation_date: i64) -> ApiResult<()>;
+    fn rotated(&self, old_context_id: String) -> ApiResult<()>;
+}
+
+pub struct DefaultContextIdCallback;
+impl ContextIdCallback for DefaultContextIdCallback {
+    fn persist(&self, _context_id: String, _creation_date: i64) -> ApiResult<()> {
+        Ok(())
+    }
+    fn rotated(&self, _old_context_id: String) -> ApiResult<()> {
+        Ok(())
+    }
+}

components/context_id/src/callback.rs

@@ -0,0 +1,40 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use error_support::{ErrorHandling, GetErrorHandling};
+
+pub type Result<T> = std::result::Result<T, Error>;
+pub type ApiResult<T> = std::result::Result<T, ApiError>;
+
+#[derive(Debug, thiserror::Error, uniffi::Error)]
+pub enum ApiError {
+    #[error("Something unexpected occurred.")]
+    Other { reason: String },
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Timestamp was invalid")]
+    InvalidTimestamp { timestamp: i64 },
+
+    #[error("URL parse error: {0}")]
+    UrlParseError(#[from] url::ParseError),
+
+    #[error("Viaduct error: {0}")]
+    ViaductError(#[from] viaduct::Error),
+
+    #[error("UniFFI callback error: {0}")]
+    UniFFICallbackError(#[from] uniffi::UnexpectedUniFFICallbackError),
+}
+
+// Define how our internal errors are handled and converted to external errors.
+impl GetErrorHandling for Error {
+    type ExternalError = ApiError;
+
+    fn get_error_handling(&self) -> ErrorHandling<Self::ExternalError> {
+        ErrorHandling::convert(ApiError::Other {
+            reason: self.to_string(),
+        })
+    }
+}