From a2951b0639297cdfae0de3212a6df3ef58603316 Mon Sep 17 00:00:00 2001
From: Sam Calder-Mason <sam.calder-mason@ethereum.org>
Date: Tue, 11 Jun 2024 14:37:31 +1000
Subject: [PATCH] feat: Support RFC9110 (#167)

* feat: Support RFC9110

* test: Add test cases for content type derivation and validation
---
 pkg/api/content_type.go      | 40 ++++++++++------
 pkg/api/content_type_test.go | 89 ++++++++++++++++++++++++++++++++++++
 pkg/api/response.go          |  2 +-
 3 files changed, 115 insertions(+), 16 deletions(-)
 create mode 100644 pkg/api/content_type_test.go

diff --git a/pkg/api/content_type.go b/pkg/api/content_type.go
index ff3163c9..015100cd 100644
--- a/pkg/api/content_type.go
+++ b/pkg/api/content_type.go
@@ -1,6 +1,9 @@
 package api
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 type ContentType int
 
@@ -20,27 +23,34 @@ func (c ContentType) String() string {
 	case ContentTypeSSZ:
 		return "application/octet-stream"
 	case ContentTypeUnknown:
-		return "unknown"
+		return "application/unknown"
 	}
 
 	return ""
 }
 
 func DeriveContentType(accept string) ContentType {
-	switch accept {
-	case "application/json":
-		return ContentTypeJSON
-	case "*/*":
-		return ContentTypeJSON
-	case "application/yaml":
-		return ContentTypeYAML
-	case "application/octet-stream":
-		return ContentTypeSSZ
-	// TODO(sam.caldermason): HACK to support Nimbus - what should we do here?
-	case "application/octet-stream,application/json;q=0.9":
-		return ContentTypeSSZ
+	// Split the accept header by commas to handle multiple content types
+	acceptTypes := strings.Split(accept, ",")
+	for _, acceptType := range acceptTypes {
+		// Split each type by semicolon to handle q-values
+		parts := strings.Split(acceptType, ";")
+		contentType := strings.TrimSpace(parts[0])
+
+		switch contentType {
+		case "application/json":
+			return ContentTypeJSON
+		case "*/*":
+			return ContentTypeJSON
+		case "application/yaml":
+			return ContentTypeYAML
+		case "application/octet-stream":
+			return ContentTypeSSZ
+		}
+	}
+
 	// Default to JSON if they don't care what they get.
-	case "":
+	if accept == "" {
 		return ContentTypeJSON
 	}
 
diff --git a/pkg/api/content_type_test.go b/pkg/api/content_type_test.go
new file mode 100644
index 00000000..0eaf9125
--- /dev/null
+++ b/pkg/api/content_type_test.go
@@ -0,0 +1,89 @@
+package api_test
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/ethpandaops/checkpointz/pkg/api"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDeriveContentType(t *testing.T) {
+	tests := []struct {
+		name     string
+		accept   string
+		expected api.ContentType
+	}{
+		{"JSON", "application/json", api.ContentTypeJSON},
+		{"Wildcard", "*/*", api.ContentTypeJSON},
+		{"YAML", "application/yaml", api.ContentTypeYAML},
+		{"SSZ", "application/octet-stream", api.ContentTypeSSZ},
+		{"Unknown", "application/unknown", api.ContentTypeUnknown},
+		{"Empty", "", api.ContentTypeJSON},
+		{"QValue JSON", "application/json;q=0.8", api.ContentTypeJSON},
+		{"QValue YAML", "application/yaml;q=0.5", api.ContentTypeYAML},
+		{"QValue Multiple", "application/json;q=0.8, application/yaml;q=0.5", api.ContentTypeJSON},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := api.DeriveContentType(tt.accept)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestValidateContentType(t *testing.T) {
+	tests := []struct {
+		name        string
+		contentType api.ContentType
+		accepting   []api.ContentType
+		expectError bool
+	}{
+		{"Valid JSON", api.ContentTypeJSON, []api.ContentType{api.ContentTypeJSON, api.ContentTypeYAML}, false},
+		{"Invalid JSON", api.ContentTypeJSON, []api.ContentType{api.ContentTypeYAML}, true},
+		{"Valid YAML", api.ContentTypeYAML, []api.ContentType{api.ContentTypeJSON, api.ContentTypeYAML}, false},
+		{"Invalid YAML", api.ContentTypeYAML, []api.ContentType{api.ContentTypeJSON}, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := api.ValidateContentType(tt.contentType, tt.accepting)
+			if tt.expectError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestNewContentTypeFromRequest(t *testing.T) {
+	tests := []struct {
+		name     string
+		accept   string
+		expected api.ContentType
+	}{
+		{"JSON", "application/json", api.ContentTypeJSON},
+		{"Wildcard", "*/*", api.ContentTypeJSON},
+		{"YAML", "application/yaml", api.ContentTypeYAML},
+		{"SSZ", "application/octet-stream", api.ContentTypeSSZ},
+		{"Unknown", "application/unknown", api.ContentTypeJSON},
+		{"Empty", "", api.ContentTypeJSON},
+		{"QValue JSON", "application/json;q=0.8", api.ContentTypeJSON},
+		{"QValue YAML", "application/yaml;q=0.5", api.ContentTypeYAML},
+		{"QValue Multiple", "application/json;q=0.8, application/yaml;q=0.5", api.ContentTypeJSON},
+		{"Nimbus example", "application/octet-stream,application/json;q=0.9", api.ContentTypeSSZ},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req, err := http.NewRequest("GET", "http://example.com", http.NoBody)
+			assert.NoError(t, err)
+			req.Header.Set("Accept", tt.accept)
+
+			result := api.NewContentTypeFromRequest(req)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
diff --git a/pkg/api/response.go b/pkg/api/response.go
index e7a71104..6af580b9 100644
--- a/pkg/api/response.go
+++ b/pkg/api/response.go
@@ -76,7 +76,7 @@ func NewBadRequestResponse(resolvers ContentTypeResolvers) *HTTPResponse {
 func NewUnsupportedMediaTypeResponse(resolvers ContentTypeResolvers) *HTTPResponse {
 	return &HTTPResponse{
 		resolvers:  resolvers,
-		StatusCode: http.StatusUnsupportedMediaType,
+		StatusCode: http.StatusNotAcceptable,
 		Headers:    make(map[string]string),
 		ExtraData:  make(map[string]interface{}),
 	}