Common: Add HttpRequest to simplify HTTP requests

Too much boilerplate that is duplicated if we use curl directly.
Let's add a simple wrapper class that hides the implementation details
and just allows to simply make HTTP requests and get responses.

Source/Core/Common/HttpRequest.cpp

@@ -0,0 +1,120 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "Common/HttpRequest.h"
+
+#include <cstddef>
+#include <curl/curl.h>
+
+#include "Common/Logging/Log.h"
+
+namespace Common
+{
+class HttpRequest::Impl final
+{
+public:
+  enum class Method
+  {
+    GET,
+    POST,
+  };
+
+  Impl();
+
+  bool IsValid() const;
+  Response Fetch(const std::string& url, Method method, const u8* payload, size_t size);
+
+private:
+  std::unique_ptr<CURL, decltype(&curl_easy_cleanup)> m_curl{curl_easy_init(), curl_easy_cleanup};
+};
+
+HttpRequest::HttpRequest() : m_impl(std::make_unique<Impl>())
+{
+}
+
+HttpRequest::~HttpRequest() = default;
+
+bool HttpRequest::IsValid() const
+{
+  return m_impl->IsValid();
+}
+
+HttpRequest::Response HttpRequest::Get(const std::string& url)
+{
+  return m_impl->Fetch(url, Impl::Method::GET, nullptr, 0);
+}
+
+HttpRequest::Response HttpRequest::Post(const std::string& url, const std::vector<u8>& payload)
+{
+  return m_impl->Fetch(url, Impl::Method::POST, payload.data(), payload.size());
+}
+
+HttpRequest::Response HttpRequest::Post(const std::string& url, const std::string& payload)
+{
+  return m_impl->Fetch(url, Impl::Method::POST, reinterpret_cast<const u8*>(payload.data()),
+                       payload.size());
+}
+
+HttpRequest::Impl::Impl()
+{
+  if (!m_curl)
+    return;
+
+  // libcurl may not have been built with async DNS support, so we disable
+  // signal handlers to avoid a possible and likely crash if a resolve times out.
+  curl_easy_setopt(m_curl.get(), CURLOPT_NOSIGNAL, true);
+  curl_easy_setopt(m_curl.get(), CURLOPT_TIMEOUT, 3);
+#ifdef _WIN32
+  // ALPN support is enabled by default but requires Windows >= 8.1.
+  curl_easy_setopt(m_curl.get(), CURLOPT_SSL_ENABLE_ALPN, false);
+#endif
+}
+
+bool HttpRequest::Impl::IsValid() const
+{
+  return m_curl != nullptr;
+}
+
+static size_t CurlCallback(char* data, size_t size, size_t nmemb, void* userdata)
+{
+  auto* buffer = static_cast<std::vector<u8>*>(userdata);
+  const size_t actual_size = size * nmemb;
+  buffer->insert(buffer->end(), data, data + actual_size);
+  return actual_size;
+}
+
+HttpRequest::Response HttpRequest::Impl::Fetch(const std::string& url, Method method,
+                                               const u8* payload, size_t size)
+{
+  curl_easy_setopt(m_curl.get(), CURLOPT_POST, method == Method::POST);
+  curl_easy_setopt(m_curl.get(), CURLOPT_URL, url.c_str());
+  if (method == Method::POST)
+  {
+    curl_easy_setopt(m_curl.get(), CURLOPT_POSTFIELDS, payload);
+    curl_easy_setopt(m_curl.get(), CURLOPT_POSTFIELDSIZE, size);
+  }
+
+  std::vector<u8> buffer;
+  curl_easy_setopt(m_curl.get(), CURLOPT_WRITEFUNCTION, CurlCallback);
+  curl_easy_setopt(m_curl.get(), CURLOPT_WRITEDATA, &buffer);
+
+  const char* type = method == Method::POST ? "POST" : "GET";
+  const CURLcode res = curl_easy_perform(m_curl.get());
+  if (res != CURLE_OK)
+  {
+    ERROR_LOG(COMMON, "Failed to %s %s: %s", type, url.c_str(), curl_easy_strerror(res));
+    return {};
+  }
+
+  long response_code = 0;
+  curl_easy_getinfo(m_curl.get(), CURLINFO_RESPONSE_CODE, &response_code);
+  if (response_code != 200)
+  {
+    ERROR_LOG(COMMON, "Failed to %s %s: response code was %li", type, url.c_str(), response_code);
+    return {};
+  }
+
+  return buffer;
+}
+}  // namespace Common