feat(referrers): support referrers API

src/OrasProject.Oras/Registry/Remote/Referrers.cs

@@ -119,14 +119,14 @@ internal static bool IsReferrersFilterApplied(string? appliedFilters, string req
         }
 
         var filters = Strings.Split(appliedFilters, ",");
-        for (int i = 0; i < filters.Length; ++i)
+        foreach (var filter in filters)
         {
-            if (filters[i] == requestedFilter)
+            if (filter == requestedFilter)
             {
                 return true;
             }
         }
-
+        
         return false;
     }
 

src/OrasProject.Oras/Registry/Remote/Repository.cs

@@ -50,6 +50,14 @@
     public RepositoryOptions Options => _opts;
 
     private int _referrersState = (int) Referrers.ReferrersState.Unknown;
+
+    /// <summary>
+    ///  _filterTypeArtifactType is the "artifactType" filter applied on the list of referrers.
+    ///
+    /// References:
+    ///   - Latest spec: https://github.com/opencontainers/distribution-spec/blob/v1.1.1/spec.md#listing-referrers
+    /// </summary>
+    private const string _filterTypeArtifactType = "artifactType";
 
     /// <summary>
     /// ReferrersState indicates the Referrers API state of the remote repository.
@@ -71,15 +79,15 @@
     /// <summary>
     /// ReferrerListPageSize specifies the page size when invoking the Referrers API.
     /// If zero, the page size is determined by the remote registry.
-    /// Reference: https://github.com/opencontainers/distribution-spec/blob/v1.1.0/spec.md#listing-referrers
+    /// Reference: https://github.com/opencontainers/distribution-spec/blob/v1.1.1/spec.md#listing-referrers
     /// </summary>
     public int ReferrerListPageSize; 
 
     /// <summary>
     /// _headerOciFiltersApplied is the "OCI-Filters-Applied" header.
     /// If present on the response, it contains a comma-separated list of the applied filters.
     /// Reference:
-    ///   - https://github.com/opencontainers/distribution-spec/blob/v1.1.0/spec.md#listing-referrers
+    ///   - https://github.com/opencontainers/distribution-spec/blob/v1.1.1/spec.md#listing-referrers
     /// </summary>
     private const string _headerOciFiltersApplied = "OCI-Filters-Applied";
 
@@ -409,8 +417,8 @@
         {   
             await ReferrersByApi(descriptor, artifactType, fn, cancellationToken).ConfigureAwait(false);
             if (ReferrersState == Referrers.ReferrersState.Supported)
             {
                 return;
             }
         }
         catch (NotSupportedException)
@@ -468,14 +476,13 @@
     {
         // If ReferrerListPageSize is greater than 0, modify the URL to include the page size query parameter
         if (ReferrerListPageSize > 0)
         {
-            // TODO
             var uriBuilder = new UriBuilder(url);
             var query = HttpUtility.ParseQueryString(uriBuilder.Query);
             query.Add("n", ReferrerListPageSize.ToString());
             uriBuilder.Query = query.ToString();
             url = uriBuilder.Uri;
         }
         using var response = await _opts.HttpClient.GetAsync(url, cancellationToken).ConfigureAwait(false);
         switch (response.StatusCode)
         {
@@ -507,7 +514,7 @@
         using var content = await response.Content.ReadAsStreamAsync(cancellationToken).ConfigureAwait(false);
         var referrersIndex = JsonSerializer.Deserialize<Index>(content);
         if (referrersIndex == null)
         {
             throw new InvalidResponseException($"{response.RequestMessage?.Method} {response.RequestMessage?.RequestUri}: failed to decode response");
         }
         var referrers = referrersIndex.Manifests;
@@ -515,7 +522,7 @@
         // If artifactType is specified, apply any filters based on the artifact type
         if (!string.IsNullOrEmpty(artifactType))
         {
-            if (!response.Headers.TryGetValues(_headerOciFiltersApplied, out var values) || !Referrers.IsReferrersFilterApplied(values.FirstOrDefault(), artifactType))
+            if (!response.Headers.TryGetValues(_headerOciFiltersApplied, out var values) || !Referrers.IsReferrersFilterApplied(values.FirstOrDefault(), _filterTypeArtifactType))
             {
                 // Filter the referrers based on the artifact type if necessary
                 referrers = Referrers.FilterReferrers(referrers, artifactType);
@@ -566,14 +573,17 @@
     {
         try
         {
-            var (desc, content) = await FetchAsync(referrersTag, cancellationToken).ConfigureAwait(false);
-            var index = JsonSerializer.Deserialize<Index>(content);
-            if (index == null)
+            var result = await FetchAsync(referrersTag, cancellationToken).ConfigureAwait(false);
+            using (var content = result.Item2)
             {
-                throw new JsonException($"null index manifests list for referrersTag {referrersTag}");
-            }
+                var index = JsonSerializer.Deserialize<Index>(content);
+                if (index == null)
+                {
+                    throw new JsonException($"null index manifests list for referrersTag {referrersTag}");
+                }
 
-            return (desc, index.Manifests);
+                return (result.Item1, index.Manifests);
+            }
         }
         catch (NotFoundException)
         {

tests/OrasProject.Oras.Tests/Remote/ReferrersTest.cs

@@ -248,7 +248,7 @@
             Referrers.ReferrerOperation.Add
         );
 
         var (updatedReferrers, updateRequired) = Referrers.ApplyReferrerChanges(oldReferrers, referrerChange);
         Assert.Single(updatedReferrers); 
         for (var i = 0; i < updatedReferrers.Count; ++i)
         {
@@ -272,7 +272,7 @@
     public void IsReferrersFilterApplied_AppliedFiltersNull_ReturnsFalse()
     {
         string? appliedFilters = null;
-        const string requestedFilter = "someFilter";
+        const string requestedFilter = "artifactType";
         var result = Referrers.IsReferrersFilterApplied(appliedFilters, requestedFilter);
         Assert.False(result);
     }
@@ -281,24 +281,24 @@
     public void IsReferrersFilterApplied_AppliedFiltersEmpty_ReturnsFalse()
     {
         const string appliedFilters = "";
-        const string requestedFilter = "someFilter";
+        const string requestedFilter = "artifactType";
         var result = Referrers.IsReferrersFilterApplied(appliedFilters, requestedFilter);
         Assert.False(result);
     }
 
     [Fact]
     public void IsReferrersFilterApplied_RequestedFilterNull_ReturnsFalse()
     {
-        const string appliedFilters = "filter1,filter2";
+        const string appliedFilters = "artifactType,annotation";
         string? requestedFilter = null;
         var result = Referrers.IsReferrersFilterApplied(appliedFilters, requestedFilter);
         Assert.False(result);
     }
 
     [Fact]
     public void IsReferrersFilterApplied_RequestedFilterEmpty_ReturnsFalse()
     {
-        const string appliedFilters = "filter1,filter2";
+        const string appliedFilters = "artifactType,annotation";
         const string requestedFilter = "";
         var result = Referrers.IsReferrersFilterApplied(appliedFilters, requestedFilter);
         Assert.False(result);
@@ -307,8 +307,8 @@
     [Fact]
     public void IsReferrersFilterApplied_RequestedFilterMatches_ReturnsTrue()
     {
-        const string appliedFilters = "filter1,filter2";
-        const string requestedFilter = "filter1";
+        const string appliedFilters = "artifactType,annotation";
+        const string requestedFilter = "artifactType";
 
         var result = Referrers.IsReferrersFilterApplied(appliedFilters, requestedFilter);
         Assert.True(result);