surrealdb-server 3.0.5

A scalable, distributed, collaborative, document-graph database, for the realtime web
Documentation 
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//! HTTP service layer for GraphQL.
//!
//! Implements an Axum [`Service`] that handles incoming GraphQL HTTP requests.
//! The service:
//!
//! 1. Checks that the GraphQL HTTP route is allowed by the datastore's capabilities.
//! 2. Validates that the session specifies a namespace and database.
//! 3. Retrieves (or generates) the GraphQL schema via [`GraphQLSchemaCache`].
//! 4. Injects the [`Datastore`](surrealdb_core::kvs::Datastore) and [`Session`] into the
//!    `async_graphql` request context so resolvers can access them.
//! 5. Executes the request -- either as a batch request or as a streaming `multipart/mixed`
//!    response, depending on the `Accept` header.

use std::convert::Infallible;
use std::task::{Context, Poll};

use async_graphql::http::is_accept_multipart_mixed;
use async_graphql::parser::types::OperationType;
use async_graphql::{Executor, ParseRequestError, Request as GraphQLInnerRequest, ServerError};
use async_graphql_axum::rejection::GraphQLRejection;
use async_graphql_axum::{GraphQLBatchRequest, GraphQLRequest, GraphQLResponse};
use axum::BoxError;
use axum::body::{Body, HttpBody};
use axum::extract::FromRequest;
use axum::http::{Request as HttpRequest, Response as HttpResponse};
use axum::response::IntoResponse;
use bytes::Bytes;
use futures_util::future::BoxFuture;
use http::header::{CONTENT_TYPE, HeaderValue};
use surrealdb_core::dbs::Session;
use surrealdb_core::dbs::capabilities::RouteTarget;
use surrealdb_core::gql::cache::GraphQLSchemaCache;
use surrealdb_core::gql::error::resolver_error;
use tower_service::Service;

use crate::ntw::error::Error as NetError;

/// Axum service that handles GraphQL HTTP requests.
///
/// Each instance holds a [`GraphQLSchemaCache`] that is shared across all
/// requests handled by this service.  The cache is cheap to clone (backed
/// by `Arc<RwLock<...>>`).
#[derive(Clone)]
pub struct GraphQLService {
	cache: GraphQLSchemaCache,
}

impl GraphQLService {
	/// Create a new GraphQL HTTP service with an empty schema cache.
	pub fn new() -> Self {
		GraphQLService {
			cache: GraphQLSchemaCache::default(),
		}
	}

	/// Return a clone of the underlying schema cache (cheap -- backed by `Arc`).
	pub(crate) fn cache(&self) -> GraphQLSchemaCache {
		self.cache.clone()
	}
}

impl<B> Service<HttpRequest<B>> for GraphQLService
where
	B: HttpBody<Data = Bytes> + Send + 'static,
	B::Data: Into<Bytes>,
	B::Error: Into<BoxError>,
{
	type Response = HttpResponse<Body>;
	type Error = Infallible;
	type Future = BoxFuture<'static, Result<Self::Response, Self::Error>>;

	fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
		Poll::Ready(Ok(()))
	}

	fn call(&mut self, req: HttpRequest<B>) -> Self::Future {
		let cache = self.cache.clone();
		let req = req.map(Body::new);

		Box::pin(async move {
			let state = req
				.extensions()
				.get::<crate::ntw::AppState>()
				.expect("state extractor should always succeed");

			let datastore = &state.datastore;

			// Check if capabilities allow querying the requested HTTP route
			if !datastore.allows_http_route(&RouteTarget::GraphQL) {
				warn!(
					"Capabilities denied HTTP route request attempt, target: '{}'",
					&RouteTarget::GraphQL
				);
				return Ok(
					NetError::ForbiddenRoute(RouteTarget::GraphQL.to_string()).into_response()
				);
			}

			let session =
				req.extensions().get::<Session>().expect("session extractor should always succeed");

			let Some(_ns) = session.ns.as_ref() else {
				return Ok(to_rejection(resolver_error("No namespace specified")).into_response());
			};
			let Some(_db) = session.db.as_ref() else {
				return Ok(to_rejection(resolver_error("No database specified")).into_response());
			};

			let schema = match cache.get_schema(datastore, session).await {
				Ok(e) => e,
				Err(e) => {
					info!(?e, "error generating schema");
					return Ok(to_rejection(e).into_response());
				}
			};

			// Clone Arc's before moving req (needed for GraphQL context)
			let datastore_ctx = datastore.clone();
			let session_ctx = std::sync::Arc::new(session.clone());

			let is_accept_multipart_mixed = req
				.headers()
				.get("accept")
				.and_then(|value| value.to_str().ok())
				.map(is_accept_multipart_mixed)
				.unwrap_or_default();

			if is_accept_multipart_mixed {
				let gql_req = match GraphQLRequest::<GraphQLRejection>::from_request(req, &()).await
				{
					Ok(r) => r,
					Err(err) => return Ok(err.into_response()),
				};
				let mut req_with_data = gql_req.into_inner().data(datastore_ctx).data(session_ctx);
				if request_is_subscription(&mut req_with_data) {
					let response = async_graphql::Response::from_errors(vec![ServerError::new(
						"Subscriptions require WebSocket transport on GET /graphql",
						None,
					)]);
					Ok(as_application_json(GraphQLResponse::from(response).into_response()))
				} else {
					Ok(as_application_json(
						GraphQLResponse::from(schema.execute(req_with_data).await).into_response(),
					))
				}
			} else {
				let gql_req =
					match GraphQLBatchRequest::<GraphQLRejection>::from_request(req, &()).await {
						Ok(r) => r,
						Err(err) => return Ok(err.into_response()),
					};
				let req_with_data = gql_req.into_inner().data(datastore_ctx).data(session_ctx);
				Ok(as_application_json(
					GraphQLResponse(schema.execute_batch(req_with_data).await).into_response(),
				))
			}
		})
	}
}

/// Check whether `req` represents a GraphQL subscription operation.
///
/// Takes `&mut` because `parsed_query()` lazily parses and caches the AST
/// inside the request. The request is not otherwise modified.
fn request_is_subscription(req: &mut GraphQLInnerRequest) -> bool {
	let operation_name = req.operation_name.clone();
	let Ok(doc) = req.parsed_query() else {
		return false;
	};

	match operation_name.as_deref() {
		Some(selected) => doc.operations.iter().any(|(name, op)| {
			name.is_some_and(|n| n.as_str() == selected)
				&& matches!(op.node.ty, OperationType::Subscription)
		}),
		None => doc
			.operations
			.iter()
			.next()
			.is_some_and(|(_, op)| matches!(op.node.ty, OperationType::Subscription)),
	}
}

fn as_application_json(mut response: HttpResponse<Body>) -> HttpResponse<Body> {
	response.headers_mut().insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
	response
}

/// Wrap an error as a GraphQL rejection (HTTP 400-level response).
fn to_rejection(err: impl std::error::Error + Send + Sync + 'static) -> GraphQLRejection {
	GraphQLRejection(ParseRequestError::InvalidRequest(Box::new(err)))
}