Fix GitHub API endpoint selection based on host parsing

include/vcpkg/base/downloads.h

@@ -37,6 +37,10 @@ namespace vcpkg
                                                  const std::string& github_repository,
                                                  const Json::Object& snapshot);
 
+    // Builds the dependency graph snapshots endpoint used for GitHub submission.
+    std::string github_dependency_graph_snapshots_uri(const Optional<std::string>& maybe_github_server_url,
+                                                      StringView github_repository);
+
     std::vector<int> url_heads(DiagnosticContext& context, View<std::string> urls, View<std::string> headers);
 
     struct AssetCachingSettings

src/vcpkg-test/downloads.cpp

@@ -53,6 +53,29 @@ TEST_CASE ("url_encode_spaces", "[downloads]")
             "https://example.com/a%20%20space/b?query=value&query2=value2");
 }
 
+TEST_CASE ("github_dependency_graph_snapshots_uri", "[downloads]")
+{
+    REQUIRE(github_dependency_graph_snapshots_uri(nullopt, "owner/repo") ==
+            "https://api.github.com/repos/owner/repo/dependency-graph/snapshots");
+
+    REQUIRE(github_dependency_graph_snapshots_uri(Optional<std::string>{"https://github.com"}, "owner/repo") ==
+            "https://api.github.com/repos/owner/repo/dependency-graph/snapshots");
+
+    REQUIRE(github_dependency_graph_snapshots_uri(Optional<std::string>{"https://github.com/"}, "owner/repo") ==
+            "https://github.com//api/v3/repos/owner/repo/dependency-graph/snapshots");
+
+    REQUIRE(github_dependency_graph_snapshots_uri(Optional<std::string>{"https://github.example.com"}, "owner/repo") ==
+            "https://github.example.com/api/v3/repos/owner/repo/dependency-graph/snapshots");
+
+    REQUIRE(github_dependency_graph_snapshots_uri(Optional<std::string>{"https://user:[email protected]:443"},
+                                              "owner/repo") ==
+        "https://user:[email protected]:443/api/v3/repos/owner/repo/dependency-graph/snapshots");
+
+    REQUIRE(
+        github_dependency_graph_snapshots_uri(Optional<std::string>{"https://github.com"}, "owner/repo with space") ==
+        "https://api.github.com/repos/owner/repo%20with%20space/dependency-graph/snapshots");
+}
+
 /*
  * To run this test:
  * - Set environment variables VCPKG_TEST_AZBLOB_URL and VCPKG_TEST_AZBLOB_SAS.

src/vcpkg/base/downloads.cpp

@@ -287,19 +287,7 @@ namespace vcpkg
                                                  const std::string& github_repository,
                                                  const Json::Object& snapshot)
     {
-        std::string uri;
-        if (auto github_server_url = maybe_github_server_url.get())
-        {
-            uri = *github_server_url;
-            uri.append("/api/v3");
-        }
-        else
-        {
-            uri = "https://api.github.com";
-        }
-
-        fmt::format_to(
-            std::back_inserter(uri), "/repos/{}/dependency-graph/snapshots", url_encode_spaces(github_repository));
+        const auto uri = github_dependency_graph_snapshots_uri(maybe_github_server_url, github_repository);
 
         CurlEasyHandle handle;
         CURL* curl = handle.get();
@@ -334,6 +322,34 @@ namespace vcpkg
         return response_code >= 200 && response_code < 300;
     }
 
+    std::string github_dependency_graph_snapshots_uri(const Optional<std::string>& maybe_github_server_url,
+                                                      StringView github_repository)
+    {
+        std::string uri;
+        constexpr StringLiteral github_com_url = "https://github.com";
+        constexpr StringLiteral api_github_com_url = "https://api.github.com";
+        if (auto github_server_url = maybe_github_server_url.get())
+        {
+            if (*github_server_url == github_com_url)
+            {
+                uri = api_github_com_url.data();
+            }
+            else
+            {
+                uri = *github_server_url;
+                uri.append("/api/v3");
+            }
+        }
+        else
+        {
+            uri = api_github_com_url.data();
+        }
+
+        fmt::format_to(
+            std::back_inserter(uri), "/repos/{}/dependency-graph/snapshots", url_encode_spaces(github_repository));
+        return uri;
+    }
+
     static size_t read_file_callback(char* buffer, size_t size, size_t nitems, void* param)
     {
         auto* file = static_cast<ReadFilePointer*>(param);