feat: add support for identity compression algorithm in confighttp

Author: farhan11166

config/confighttp/compression.go

@@ -66,6 +66,10 @@ var availableDecoders = map[string]func(body io.ReadCloser) (io.ReadCloser, erro
 		// Not a compressed payload. Nothing to do.
 		return nil, nil
 	},
+	"identity": func(io.ReadCloser) (io.ReadCloser, error) {
+		// Per RFC 7231 §3.1.2.2, "identity" means no encoding.
+		return nil, nil
+	},
 	"gzip": func(body io.ReadCloser) (io.ReadCloser, error) {
 		gr, err := gzip.NewReader(body)
 		if err != nil {
@@ -249,6 +253,9 @@ func httpContentDecompressor(h http.Handler, maxRequestBodySize int64, eh func(w
 	for _, dec := range enableDecoders {
 		enabled[dec] = availableDecoders[dec]
 
+		if dec == "" {
+			enabled["identity"] = availableDecoders["identity"]
+		}
 		if dec == "deflate" {
 			enabled["deflate"] = availableDecoders["zlib"]
 		}

config/confighttp/compression_test.go

@@ -638,7 +638,7 @@ func TestCompressionAlgorithmsEdgeCases(t *testing.T) {
 			compressionAlgorithms: []string{"", "gzip", "zstd"},
 			contentEncoding:       "identity",
 			body:                  testBody,
-			wantStatus:            http.StatusBadRequest, // BUG: should be http.StatusOK
+			wantStatus:            http.StatusOK, // BUG: should be http.StatusOK
 		},
 		{
 			name:                  "Mixed_Snappy_Rejected",