HTTP API client utility functions (get, post, etc.)

api/src/client.rs

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+// Copyright 2016 The Grin Developers
+//
+// 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.
+
+//! High level JSON/HTTP client API
+
+use hyper;
+use hyper::client::Response;
+use hyper::status::StatusClass;
+use serde::{Serialize, Deserialize};
+use serde_json;
+
+use rest::Error;
+
+/// Helper function to easily issue a HTTP GET request against a given URL that
+/// returns a JSON object. Handles request building, JSON deserialization and
+/// response code checking.
+pub fn get<'a, T>(url: &'a str) -> Result<T, Error>
+	where T: Deserialize
+{
+	let client = hyper::Client::new();
+	let res = check_error(client.get(url).send())?;
+	serde_json::from_reader(res)
+		.map_err(|e| Error::Internal(format!("Server returned invalid JSON: {}", e)))
+}
+
+/// Helper function to easily issue a HTTP POST request with the provided JSON
+/// object as body on a given URL that returns a JSON object. Handles request
+/// building, JSON serialization and deserialization, and response code
+/// checking.
+pub fn post<'a, IN, OUT>(url: &'a str, input: &IN) -> Result<OUT, Error>
+	where IN: Serialize,
+	      OUT: Deserialize
+{
+	let in_json = serde_json::to_string(input)
+		.map_err(|e| Error::Internal(format!("Could not serialize data to JSON: {}", e)))?;
+	let client = hyper::Client::new();
+	let res = check_error(client.post(url).body(&mut in_json.as_bytes()).send())?;
+	serde_json::from_reader(res)
+		.map_err(|e| Error::Internal(format!("Server returned invalid JSON: {}", e)))
+}
+
+// convert hyper error and check for non success response codes
+fn check_error(res: hyper::Result<Response>) -> Result<Response, Error> {
+	if let Err(e) = res {
+		return Err(Error::Internal(format!("Error during request: {}", e)));
+	}
+	let response = res.unwrap();
+	match response.status.class() {
+		StatusClass::Success => Ok(response),
+		StatusClass::ServerError => Err(Error::Internal(format!("Server error."))),
+		StatusClass::ClientError => Err(Error::Argument(format!("Argument error"))),
+		_ => Err(Error::Internal(format!("Unrecognized error."))),
+	}
+}