1 files changed, 133 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/download.hh b/third_party/nix/src/libstore/download.hh
new file mode 100644
index 000000000000..cbfab5f40d22
--- /dev/null
+++ b/third_party/nix/src/libstore/download.hh
@@ -0,0 +1,133 @@
+#pragma once
+
+#include <future>
+#include <string>
+
+#include "libstore/globals.hh"
+#include "libutil/hash.hh"
+#include "libutil/types.hh"
+
+namespace nix {
+
+struct DownloadSettings : Config {
+  Setting<bool> enableHttp2{this, true, "http2",
+                            "Whether to enable HTTP/2 support."};
+
+  Setting<std::string> userAgentSuffix{
+      this, "", "user-agent-suffix",
+      "String appended to the user agent in HTTP requests."};
+
+  Setting<size_t> httpConnections{this,
+                                  25,
+                                  "http-connections",
+                                  "Number of parallel HTTP connections.",
+                                  {"binary-caches-parallel-connections"}};
+
+  Setting<unsigned long> connectTimeout{
+      this, 0, "connect-timeout",
+      "Timeout for connecting to servers during downloads. 0 means use curl's "
+      "builtin default."};
+
+  Setting<unsigned long> stalledDownloadTimeout{
+      this, 300, "stalled-download-timeout",
+      "Timeout (in seconds) for receiving data from servers during download. "
+      "Nix cancels idle downloads after this timeout's duration."};
+
+  Setting<unsigned int> tries{
+      this, 5, "download-attempts",
+      "How often Nix will attempt to download a file before giving up."};
+};
+
+extern DownloadSettings downloadSettings;
+
+struct DownloadRequest {
+  std::string uri;
+  std::string expectedETag;
+  bool verifyTLS = true;
+  bool head = false;
+  size_t tries = downloadSettings.tries;
+  unsigned int baseRetryTimeMs = 250;
+  bool decompress = true;
+  std::shared_ptr<std::string> data;
+  std::string mimeType;
+  std::function<void(char*, size_t)> dataCallback;
+
+  DownloadRequest(const std::string& uri) : uri(uri) {}
+
+  std::string verb() { return data ? "upload" : "download"; }
+};
+
+struct DownloadResult {
+  bool cached = false;
+  std::string etag;
+  std::string effectiveUri;
+  std::shared_ptr<std::string> data;
+  uint64_t bodySize = 0;
+};
+
+struct CachedDownloadRequest {
+  std::string uri;
+  bool unpack = false;
+  std::string name;
+  Hash expectedHash;
+  unsigned int ttl = settings.tarballTtl;
+
+  CachedDownloadRequest(const std::string& uri) : uri(uri) {}
+};
+
+struct CachedDownloadResult {
+  // Note: 'storePath' may be different from 'path' when using a
+  // chroot store.
+  Path storePath;
+  Path path;
+  std::optional<std::string> etag;
+  std::string effectiveUri;
+};
+
+class Store;
+
+struct Downloader {
+  virtual ~Downloader() {}
+
+  /* Enqueue a download request, returning a future to the result of
+     the download. The future may throw a DownloadError
+     exception. */
+  virtual void enqueueDownload(const DownloadRequest& request,
+                               Callback<DownloadResult> callback) = 0;
+
+  std::future<DownloadResult> enqueueDownload(const DownloadRequest& request);
+
+  /* Synchronously download a file. */
+  DownloadResult download(const DownloadRequest& request);
+
+  /* Download a file, writing its data to a sink. The sink will be
+     invoked on the thread of the caller. */
+  void download(DownloadRequest&& request, Sink& sink);
+
+  /* Check if the specified file is already in ~/.cache/nix/tarballs
+     and is more recent than ‘tarball-ttl’ seconds. Otherwise,
+     use the recorded ETag to verify if the server has a more
+     recent version, and if so, download it to the Nix store. */
+  CachedDownloadResult downloadCached(const ref<Store>& store,
+                                      const CachedDownloadRequest& request);
+
+  enum Error { NotFound, Forbidden, Misc, Transient, Interrupted };
+};
+
+/* Return a shared Downloader object. Using this object is preferred
+   because it enables connection reuse and HTTP/2 multiplexing. */
+ref<Downloader> getDownloader();
+
+/* Return a new Downloader object. */
+ref<Downloader> makeDownloader();
+
+class DownloadError : public Error {
+ public:
+  Downloader::Error error;
+  DownloadError(Downloader::Error error, const FormatOrString& fs)
+      : Error(fs), error(error) {}
+};
+
+bool isUri(const std::string& s);
+
+}  // namespace nix