1 files changed, 79 insertions, 0 deletions
diff --git a/src/libstore/download.hh b/src/libstore/download.hh
new file mode 100644
index 000000000000..62f3860b9dae
--- /dev/null
+++ b/src/libstore/download.hh
@@ -0,0 +1,79 @@
+#pragma once
+
+#include "types.hh"
+#include "hash.hh"
+
+#include <string>
+#include <future>
+
+namespace nix {
+
+struct DownloadRequest
+{
+    std::string uri;
+    std::string expectedETag;
+    bool verifyTLS = true;
+    enum { yes, no, automatic } showProgress = yes;
+    bool head = false;
+    size_t tries = 5;
+    unsigned int baseRetryTimeMs = 250;
+
+    DownloadRequest(const std::string & uri) : uri(uri) { }
+};
+
+struct DownloadResult
+{
+    bool cached = false;
+    std::string etag;
+    std::string effectiveUrl;
+    std::shared_ptr<std::string> data;
+};
+
+class Store;
+
+struct 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,
+        std::function<void(const DownloadResult &)> success,
+        std::function<void(std::exception_ptr exc)> failure) = 0;
+
+    std::future<DownloadResult> enqueueDownload(const DownloadRequest & request);
+
+    /* Synchronously download a file. */
+    DownloadResult download(const DownloadRequest & request);
+
+    /* 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. */
+    Path downloadCached(ref<Store> store, const string & uri, bool unpack, string name = "",
+        const Hash & expectedHash = Hash(), string * effectiveUri = nullptr);
+
+    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 string & s);
+
+/* Decode data according to the Content-Encoding header. */
+ref<std::string> decodeContent(const std::string & encoding, ref<std::string> data);
+
+}