Merge pull request #74 from debatecore/73-modify-cors-to-allow-including-credentials

[73] modify cors to allow including credentials

Author: jakubmanczak

README.md

@@ -11,7 +11,7 @@ You may also venture on your own, adapting the following instructions to your ne
 Set the following environment variables, via `.env` or your shell:
 - `DOCKER_DB_ROOT_PASSWORD` will be used as the password for the database root user.
 - `DATABASE_URL` is used for db connection. During development, this is `postgres://tau:tau@localhost:5432/tau`.
-- `SECRET` will be used as high entropy data used for generating tokens.
+- `FRONTEND_ORIGIN` will be used as an allowed [origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin) for the purpose of [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CORS). Must be a valid URL.
 
 Start the database with `docker compose --profile dev (up -d/down)`.
 Run the migrations via sqlx-cli with `sqlx run migrate` or by other means.
@@ -22,10 +22,11 @@ Compile and run the project with `cargo`.
 For deploying via docker, set the following environment variables:
 - `DOCKER_DB_PASSWORD` which will be used as the password for the backend's database access user.
 - `DOCKER_DB_ROOT_PASSWORD` will be used as the password for the database root user.
-- `SECRET` will be used as high entropy data used for generating tokens.
+- `FRONTEND_ORIGIN` will be used as an allowed [origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin) for the purpose of [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CORS). Must be a valid URL (`http://localhost:3000` by default).
 Then, run `docker compose --profile prod`.
 
 ### Optional configuration
+- `SECRET` will be used as additional high entropy data used for generating tokens. By default, tau uses system entropy and the current UNIX timestamp.
 - `PORT` will be used as the port the server listens on. The default is 2023.
 
 The following example `.env` file is geared for both scenarios:
@@ -34,6 +35,7 @@ DATABASE_URL=postgres://tau:tau@localhost:5432/tau
 SECRET=CENTRUMRWLYSONOSTARPOZNANCDNSBCD4L52SPM
 DOCKER_DB_ROOT_PASSWORD=superdoopersecretpasswordthatcannotbeleaked
 DOCKER_DB_PASSWORD=wedoingsecurityinhere
+FRONTEND_ORIGIN=https://example.com
 PORT=2019
 ```
 

compose.yaml

@@ -13,6 +13,7 @@ services:
       - DATABASE_URL=postgres://tau:${DOCKER_DB_PASSWORD}@db-prod:5432/tau
       - PORT=${PORT}
       - SECRET=${SECRET}
+      - FRONTEND_ORIGIN=${FRONTEND_ORIGIN}
     depends_on:
       db-prod:
         condition: service_healthy
@@ -49,6 +50,7 @@ services:
       - dbrootpassword
     environment:
       - POSTGRES_PASSWORD_FILE=/run/secrets/dbrootpassword
+      - FRONTEND_ORIGIN=http://localhost:3000
     volumes:
       - dbdevdata:/var/lib/postgresql/data
       - ./dbinit-dev.sh:/docker-entrypoint-initdb.d/dbinit-dev.sh

src/main.rs

@@ -1,7 +1,6 @@
 use axum::Router;
 use tokio::net::TcpListener;
 use tower_cookies::CookieManagerLayer;
-use tower_http::cors::{Any, CorsLayer};
 use tracing::error;
 use users::infradmin::guarantee_infrastructure_admin_exists;
 
@@ -25,7 +24,7 @@ async fn main() {
     let app = Router::new()
         .merge(routes::routes())
         .with_state(state)
-        .layer(CorsLayer::new().allow_origin(Any).allow_methods(Any))
+        .layer(setup::configure_cors())
         .layer(CookieManagerLayer::new());
 
     let addr = setup::get_socket_addr();

src/setup.rs

@@ -1,6 +1,8 @@
+use axum::http::{header::CONTENT_TYPE, HeaderValue, Method};
 use sqlx::{Pool, Postgres};
 use std::net::{Ipv4Addr, SocketAddrV4};
 use tokio::net::TcpListener;
+use tower_http::cors::CorsLayer;
 use tracing::{error, info, warn, Level};
 use tracing_subscriber::FmtSubscriber;
 
@@ -9,6 +11,7 @@ use crate::database;
 const CRYPTO_SECRET_CORRECT: &str = "Cryptographic SECRET is set.";
 const CRYPTO_SECRET_NOT_SET: &str = "Cryptographic SECRET is not set. This may lead to increased predictability in token generation.";
 const CRYPTO_SECRET_ERROR: &str = "Could not read SECRET. Is it valid UTF-8?";
+const FRONTEND_ORIGIN_NOT_SET: &str = "FRONTEND_ORIGIN is not set. Please provide a valid URL leading to an accepted origin.";
 
 pub fn initialise_logging() {
     let subscriber = FmtSubscriber::builder()
@@ -94,3 +97,33 @@ pub fn check_secret_env_var() {
         },
     }
 }
+
+pub fn configure_cors() -> CorsLayer {
+    let default_origin = "http://localhost:3000".to_owned();
+    let result = std::env::var("FRONTEND_ORIGIN");
+
+    #[cfg(not(debug_assertions))]
+    if result.is_err() {
+        error!("{}", FRONTEND_ORIGIN_NOT_SET);
+        panic!();
+    }
+
+    let frontend_origin = result.unwrap_or(default_origin);
+    info!(
+        "FRONTEND_ORIGIN set to {}. Requests made from any other origins will be disallowed at browser level",
+        &frontend_origin
+    );
+    let layer = CorsLayer::new()
+        .allow_origin(frontend_origin.parse::<HeaderValue>().unwrap())
+        .allow_methods([
+            Method::GET,
+            Method::POST,
+            Method::DELETE,
+            Method::PATCH,
+            Method::PUT,
+        ])
+        .allow_headers([CONTENT_TYPE])
+        .allow_credentials(true);
+
+    return layer;
+}