Add support for MFA with Duo's Universal Prompt (#4637)

* Add initial working Duo Universal Prompt support.

* Add db schema and models for Duo 2FA state storage

* store duo states in the database and validate during authentication

* cleanup & comments

* bump state/nonce length

* replace stray use of TimeDelta

* more cleanup

* bind Duo oauth flow to device id, drop redundant device type handling

* drop redundant alphanum string generation code

* error handling cleanup

* directly use JWT_VALIDITY_SECS constant instead of copying it to DuoClient instances

* remove redundant explicit returns, rustfmt

* rearrange constants, update comments, error message

* override charset on duo state column to ascii for mysql

* Reduce twofactor_duo_ctx state/nonce column size in postgres and maria

* Add fixes suggested by clippy

* rustfmt

* Update to use the make_http_request

* Don't handle OrganizationDuo

* move Duo API endpoint fmt strings out of macros and into format! calls

* Add missing indentation

Co-authored-by: Daniel García <dani-garcia@users.noreply.github.com>

* remove redundant expiry check when purging Duo contexts

---------

Co-authored-by: BlackDex <black.dex@gmail.com>
Co-authored-by: Daniel García <dani-garcia@users.noreply.github.com>

src/db/models/two_factor_duo_context.rs

@@ -0,0 +1,84 @@
+use chrono::Utc;
+
+use crate::{api::EmptyResult, db::DbConn, error::MapResult};
+
+db_object! {
+    #[derive(Identifiable, Queryable, Insertable, AsChangeset)]
+    #[diesel(table_name = twofactor_duo_ctx)]
+    #[diesel(primary_key(state))]
+    pub struct TwoFactorDuoContext {
+        pub state: String,
+        pub user_email: String,
+        pub nonce: String,
+        pub exp: i64,
+    }
+}
+
+impl TwoFactorDuoContext {
+    pub async fn find_by_state(state: &str, conn: &mut DbConn) -> Option<Self> {
+        db_run! {
+            conn: {
+                twofactor_duo_ctx::table
+                    .filter(twofactor_duo_ctx::state.eq(state))
+                    .first::<TwoFactorDuoContextDb>(conn)
+                    .ok()
+                    .from_db()
+            }
+        }
+    }
+
+    pub async fn save(state: &str, user_email: &str, nonce: &str, ttl: i64, conn: &mut DbConn) -> EmptyResult {
+        // A saved context should never be changed, only created or deleted.
+        let exists = Self::find_by_state(state, conn).await;
+        if exists.is_some() {
+            return Ok(());
+        };
+
+        let exp = Utc::now().timestamp() + ttl;
+
+        db_run! {
+            conn: {
+                diesel::insert_into(twofactor_duo_ctx::table)
+                    .values((
+                        twofactor_duo_ctx::state.eq(state),
+                        twofactor_duo_ctx::user_email.eq(user_email),
+                        twofactor_duo_ctx::nonce.eq(nonce),
+                        twofactor_duo_ctx::exp.eq(exp)
+                ))
+                .execute(conn)
+                .map_res("Error saving context to twofactor_duo_ctx")
+            }
+        }
+    }
+
+    pub async fn find_expired(conn: &mut DbConn) -> Vec<Self> {
+        let now = Utc::now().timestamp();
+        db_run! {
+            conn: {
+                twofactor_duo_ctx::table
+                    .filter(twofactor_duo_ctx::exp.lt(now))
+                    .load::<TwoFactorDuoContextDb>(conn)
+                    .expect("Error finding expired contexts in twofactor_duo_ctx")
+                    .from_db()
+            }
+        }
+    }
+
+    pub async fn delete(&self, conn: &mut DbConn) -> EmptyResult {
+        db_run! {
+            conn: {
+                diesel::delete(
+                    twofactor_duo_ctx::table
+                    .filter(twofactor_duo_ctx::state.eq(&self.state)))
+                    .execute(conn)
+                    .map_res("Error deleting from twofactor_duo_ctx")
+            }
+        }
+    }
+
+    pub async fn purge_expired_duo_contexts(conn: &mut DbConn) {
+        for context in Self::find_expired(conn).await {
+            context.delete(conn).await.ok();
+        }
+    }
+}