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HTTPClient.h
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HTTPClient.h
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//===-- llvm/Support/HTTPClient.h - HTTP client library ---------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains the declarations of the HTTPClient, HTTPMethod,
/// HTTPResponseHandler, and BufferedHTTPResponseHandler classes, as well as
/// the HTTPResponseBuffer and HTTPRequest structs.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_HTTP_CLIENT_H
#define LLVM_SUPPORT_HTTP_CLIENT_H
#include "llvm/Support/Error.h"
#include "llvm/Support/MemoryBuffer.h"
namespace llvm {
enum class HTTPMethod { GET };
/// A stateless description of an outbound HTTP request.
struct HTTPRequest {
SmallString<128> Url;
HTTPMethod Method = HTTPMethod::GET;
bool FollowRedirects = true;
HTTPRequest(StringRef Url);
};
bool operator==(const HTTPRequest &A, const HTTPRequest &B);
/// A handler for state updates occurring while an HTTPRequest is performed.
/// Can trigger the client to abort the request by returning an Error from any
/// of its methods.
class HTTPResponseHandler {
public:
/// Processes one line of HTTP response headers.
virtual Error handleHeaderLine(StringRef HeaderLine) = 0;
/// Processes an additional chunk of bytes of the HTTP response body.
virtual Error handleBodyChunk(StringRef BodyChunk) = 0;
/// Processes the HTTP response status code.
virtual Error handleStatusCode(unsigned Code) = 0;
protected:
~HTTPResponseHandler();
};
/// An HTTP response status code bundled with a buffer to store the body.
struct HTTPResponseBuffer {
unsigned Code = 0;
std::unique_ptr<WritableMemoryBuffer> Body;
};
/// A simple handler which writes returned data to an HTTPResponseBuffer.
/// Ignores all headers except the Content-Length, which it uses to
/// allocate an appropriately-sized Body buffer.
class BufferedHTTPResponseHandler final : public HTTPResponseHandler {
size_t Offset = 0;
public:
/// Stores the data received from the HTTP server.
HTTPResponseBuffer ResponseBuffer;
/// These callbacks store the body and status code in an HTTPResponseBuffer
/// allocated based on Content-Length. The Content-Length header must be
/// handled by handleHeaderLine before any calls to handleBodyChunk.
Error handleHeaderLine(StringRef HeaderLine) override;
Error handleBodyChunk(StringRef BodyChunk) override;
Error handleStatusCode(unsigned Code) override;
};
/// A reusable client that can perform HTTPRequests through a network socket.
class HTTPClient {
#ifdef LLVM_ENABLE_CURL
void *Curl = nullptr;
#endif
public:
HTTPClient();
~HTTPClient();
static bool IsInitialized;
/// Returns true only if LLVM has been compiled with a working HTTPClient.
static bool isAvailable();
/// Must be called at the beginning of a program, while it is a single thread.
static void initialize();
/// Must be called at the end of a program, while it is a single thread.
static void cleanup();
/// Sets the timeout for the entire request, in milliseconds. A zero or
/// negative value means the request never times out.
void setTimeout(std::chrono::milliseconds Timeout);
/// Performs the Request, passing response data to the Handler. Returns all
/// errors which occur during the request. Aborts if an error is returned by a
/// Handler method.
Error perform(const HTTPRequest &Request, HTTPResponseHandler &Handler);
/// Performs the Request with the default BufferedHTTPResponseHandler, and
/// returns its HTTPResponseBuffer or an Error.
Expected<HTTPResponseBuffer> perform(const HTTPRequest &Request);
/// Performs an HTTPRequest with the default configuration to make a GET
/// request to the given Url. Returns an HTTPResponseBuffer or an Error.
Expected<HTTPResponseBuffer> get(StringRef Url);
};
} // end namespace llvm
#endif // LLVM_SUPPORT_HTTP_CLIENT_H