libstore: Add the ability to use different auth methods with Http Binary Caches

src/libstore/filetransfer.cc

@@ -351,7 +351,9 @@ struct curlFileTransfer : public FileTransfer
             curl_easy_setopt(req, CURLOPT_PIPEWAIT, 1);
             #endif
             #if LIBCURL_VERSION_NUM >= 0x072f00
-            if (fileTransferSettings.enableHttp2)
+            // Our writeCallbackWrapper does not support rewinding which breaks
+            // negotiate/kerberos auth over http/2.
+            if (fileTransferSettings.enableHttp2 && request.authmethod != HttpAuthMethod::NEGOTIATE)
                 curl_easy_setopt(req, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
             else
                 curl_easy_setopt(req, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
@@ -397,6 +399,14 @@ struct curlFileTransfer : public FileTransfer
             curl_easy_setopt(req, CURLOPT_SOCKOPTFUNCTION, cloexec_callback);
             #endif
 
+            curl_easy_setopt(req, CURLOPT_HTTPAUTH, request.authmethod);
+            if (request.authmethod == HttpAuthMethod::NEGOTIATE) {
+                curl_easy_setopt(req, CURLOPT_USERNAME, "");
+                curl_easy_setopt(req, CURLOPT_PASSWORD, "");
+            } else if (request.authmethod == HttpAuthMethod::BEARER) {
+                curl_easy_setopt(req, CURLOPT_XOAUTH2_BEARER, request.bearer_token.c_str());
+            }
+
             curl_easy_setopt(req, CURLOPT_CONNECTTIMEOUT, fileTransferSettings.connectTimeout.get());
 
             curl_easy_setopt(req, CURLOPT_LOW_SPEED_LIMIT, 1L);

src/libstore/http-binary-cache-store.cc

@@ -9,6 +9,23 @@ namespace nix {
 
 MakeError(UploadToHTTP, Error);
 
+HttpAuthMethod parseHttpAuthMethod(const std::string &str) {
+    static const std::map<std::string, HttpAuthMethod> map = {
+        {"none", HttpAuthMethod::NONE},
+        {"basic", HttpAuthMethod::BASIC},
+        {"digest", HttpAuthMethod::DIGEST},
+        {"negotiate", HttpAuthMethod::NEGOTIATE},
+        {"ntlm", HttpAuthMethod::NTLM},
+        {"bearer", HttpAuthMethod::BEARER},
+        {"any", HttpAuthMethod::ANY},
+        {"anysafe", HttpAuthMethod::ANYSAFE}};
+    auto it = map.find(str);
+    if (it == map.end()) {
+       throw UsageError("option authmethod has invalid value '%s'", str);
+    }
+    return it->second;
+}
+
 
 StringSet HttpBinaryCacheStoreConfig::uriSchemes()
 {
@@ -152,11 +169,13 @@ class HttpBinaryCacheStore :
 
     FileTransferRequest makeRequest(const std::string & path)
     {
-        return FileTransferRequest(
+        auto request = FileTransferRequest(
             hasPrefix(path, "https://") || hasPrefix(path, "http://") || hasPrefix(path, "file://")
             ? path
             : config->cacheUri + "/" + path);
-
+        request.authmethod = parseHttpAuthMethod(config->authmethod);
+        request.bearer_token = config->bearer_token;
+        return request;
     }
 
     void getFile(const std::string & path, Sink & sink) override

src/libstore/include/nix/store/filetransfer.hh

@@ -1,6 +1,8 @@
 #pragma once
 ///@file
 
+#include "http-binary-cache-store.hh"
+
 #include <string>
 #include <future>
 
@@ -68,6 +70,8 @@ struct FileTransferRequest
     bool verifyTLS = true;
     bool head = false;
     bool post = false;
+    HttpAuthMethod authmethod = HttpAuthMethod::BASIC;
+    std::string bearer_token;
     size_t tries = fileTransferSettings.tries;
     unsigned int baseRetryTimeMs = RETRY_TIME_MS_DEFAULT;
     ActivityId parentAct;

src/libstore/include/nix/store/http-binary-cache-store.hh

@@ -1,7 +1,24 @@
-#include "nix/store/binary-cache-store.hh"
+#pragma once
+///@file
+
+#include "nix/util/types.hh"
+#include <curl/curl.h>
+
+#include "binary-cache-store.hh"
 
 namespace nix {
 
+enum struct HttpAuthMethod : unsigned long {
+    NONE = CURLAUTH_NONE,
+    BASIC = CURLAUTH_BASIC,
+    DIGEST = CURLAUTH_DIGEST,
+    NEGOTIATE = CURLAUTH_NEGOTIATE,
+    NTLM = CURLAUTH_NTLM,
+    BEARER = CURLAUTH_BEARER,
+    ANY = CURLAUTH_ANY,
+    ANYSAFE = CURLAUTH_ANYSAFE
+};
+
 struct HttpBinaryCacheStoreConfig : std::enable_shared_from_this<HttpBinaryCacheStoreConfig>,
                                     virtual Store::Config,
                                     BinaryCacheStoreConfig
@@ -20,6 +37,15 @@ struct HttpBinaryCacheStoreConfig : std::enable_shared_from_this<HttpBinaryCache
 
     static StringSet uriSchemes();
 
+    const Setting<std::string> authmethod{this, "basic", "authmethod",
+        R"(
+          libcurl auth method to use (`none`, `basic`, `digest`, `bearer`, `negotiate`, `ntlm`, `any`, or `anysafe`).
+          See https://curl.se/libcurl/c/CURLOPT_HTTPAUTH.html for more info.
+        )"};
+
+    const Setting<std::string> bearer_token{this, "", "bearer-token",
+        "Bearer token to use for authentication. Requires `authmethod` to be set to `bearer`."};
+
     static std::string doc();
 
     ref<Store> openStore() const override;

src/libstore/package.nix

@@ -72,6 +72,7 @@ mkMesonLibrary (finalAttrs: {
   propagatedBuildInputs = [
     nix-util
     nlohmann_json
+    curl
   ];
 
   mesonFlags =