parsec-service 0.1.1

A language-agnostic API to secure services in a platform-agnostic way
Documentation 
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// Copyright (c) 2019, Arm Limited, All Rights Reserved
// SPDX-License-Identifier: Apache-2.0
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//          http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use super::backend_handler::BackEndHandler;
use crate::authenticators::ApplicationName;
use parsec_interface::requests::request::Request;
use parsec_interface::requests::ProviderID;
use parsec_interface::requests::{Response, ResponseStatus};
use std::collections::HashMap;
use std::io::{Error, ErrorKind, Result};

/// Component tasked with identifying the backend handler that can
/// service a request.
///
/// As such, it owns all the backend handlers and attempts to match
/// the fields in the request header to the properties of the handlers.
#[derive(Debug)]
pub struct Dispatcher {
    backends: HashMap<ProviderID, BackEndHandler>,
}

impl Dispatcher {
    /// Parses the `provider` field of the request header and attempts to find
    /// the backend handler to which the request must be dispatched.
    ///
    /// Returns either the response coming from the backend handler, or a response
    /// containing a status code consistent with the error encountered during
    /// processing.
    pub fn dispatch_request(
        &self,
        request: Request,
        app_name: Option<ApplicationName>,
    ) -> Response {
        if let Some(backend) = self.backends.get(&request.header.provider) {
            if let Err(status) = backend.is_capable(&request) {
                Response::from_request_header(request.header, status)
            } else {
                backend.execute_request(request, app_name)
            }
        } else {
            Response::from_request_header(request.header, ResponseStatus::ProviderNotRegistered)
        }
    }
}

#[derive(Debug, Default)]
pub struct DispatcherBuilder {
    backends: Option<HashMap<ProviderID, BackEndHandler>>,
}

impl DispatcherBuilder {
    pub fn new() -> Self {
        DispatcherBuilder { backends: None }
    }

    pub fn with_backend(
        mut self,
        provider_id: ProviderID,
        backend_handler: BackEndHandler,
    ) -> Self {
        let mut backends = self.backends.unwrap_or_default();
        let _ = backends.insert(provider_id, backend_handler);
        self.backends = Some(backends);

        self
    }

    pub fn with_backends(mut self, new_backends: HashMap<ProviderID, BackEndHandler>) -> Self {
        let mut backends = self.backends.unwrap_or_default();
        backends.extend(new_backends);
        self.backends = Some(backends);

        self
    }

    pub fn build(self) -> Result<Dispatcher> {
        Ok(Dispatcher {
            backends: self
                .backends
                .ok_or_else(|| Error::new(ErrorKind::InvalidData, "backends is missing"))?,
        })
    }
}