Add dashboard to steve

pkg/responsewriter/gzip.go

@@ -0,0 +1,70 @@
+package responsewriter
+
+import (
+	"bufio"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"reflect"
+	"strings"
+)
+
+type wrapWriter struct {
+	gzipResponseWriter
+
+	code int
+}
+
+type gzipResponseWriter struct {
+	io.Writer
+	http.ResponseWriter
+}
+
+func (g gzipResponseWriter) Write(b []byte) (int, error) {
+	// Header logic is kept here in case the user does not use WriteHeader
+	g.Header().Set("Content-Encoding", "gzip")
+	g.Header().Del("Content-Length")
+
+	return g.Writer.Write(b)
+}
+
+// Close uses gzip to write gzip footer if message is gzip encoded
+func (g gzipResponseWriter) Close(writer *gzip.Writer) {
+	if g.Header().Get("Content-Encoding") == "gzip" {
+		writer.Close()
+	}
+}
+
+// WriteHeader sets gzip encoding and removes length. Should always be used when using gzip writer.
+func (g gzipResponseWriter) WriteHeader(statusCode int) {
+	g.Header().Set("Content-Encoding", "gzip")
+	g.Header().Del("Content-Length")
+	g.ResponseWriter.WriteHeader(statusCode)
+}
+
+// Gzip creates a gzip writer if gzip encoding is accepted.
+func Gzip(handler http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			handler.ServeHTTP(w, r)
+			return
+		}
+		gz := gzip.NewWriter(w)
+
+		gzw := &wrapWriter{gzipResponseWriter{Writer: gz, ResponseWriter: w}, http.StatusOK}
+		defer gzw.Close(gz)
+
+		// Content encoding will be set once Write or WriteHeader is called, to avoid gzipping empty messages
+		handler.ServeHTTP(gzw, r)
+	})
+}
+
+// Hijack must be implemented to properly chain with handlers expecting a hijacker handler to be passed
+func (g *gzipResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	if hijacker, ok := g.ResponseWriter.(http.Hijacker); ok {
+		return hijacker.Hijack()
+	}
+	return nil, nil, fmt.Errorf("Upstream ResponseWriter of type %v does not implement http.Hijacker", reflect.TypeOf(g.ResponseWriter))
+}