First commit

middleware/middleware.go

@@ -0,0 +1,105 @@
+// Package middleware provides some types and functions common among middleware.
+package middleware
+
+import (
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+type (
+	// Middleware is the middle layer which represents the traditional
+	// idea of middleware: it chains one Handler to the next by being
+	// passed the next Handler in the chain.
+	Middleware func(Handler) Handler
+
+	// Handler is like dns.Handler except ServeDNS may return an rcode
+	// and/or error.
+	//
+	// If ServeDNS writes to the response body, it should return a status
+	// code of 0. This signals to other handlers above it that the response
+	// body is already written, and that they should not write to it also.
+	//
+	// If ServeDNS encounters an error, it should return the error value
+	// so it can be logged by designated error-handling middleware.
+	//
+	// If writing a response after calling another ServeDNS method, the
+	// returned rcode SHOULD be used when writing the response.
+	//
+	// If handling errors after calling another ServeDNS method, the
+	// returned error value SHOULD be logged or handled accordingly.
+	//
+	// Otherwise, return values should be propagated down the middleware
+	// chain by returning them unchanged.
+	Handler interface {
+		ServeDNS(dns.ResponseWriter, *dns.Msg) (int, error)
+	}
+
+	// HandlerFunc is a convenience type like dns.HandlerFunc, except
+	// ServeDNS returns an rcode and an error. See Handler
+	// documentation for more information.
+	HandlerFunc func(dns.ResponseWriter, *dns.Msg) (int, error)
+)
+
+// ServeDNS implements the Handler interface.
+func (f HandlerFunc) ServeDNS(w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	return f(w, r)
+}
+
+// IndexFile looks for a file in /root/fpath/indexFile for each string
+// in indexFiles. If an index file is found, it returns the root-relative
+// path to the file and true. If no index file is found, empty string
+// and false is returned. fpath must end in a forward slash '/'
+// otherwise no index files will be tried (directory paths must end
+// in a forward slash according to HTTP).
+//
+// All paths passed into and returned from this function use '/' as the
+// path separator, just like URLs.  IndexFle handles path manipulation
+// internally for systems that use different path separators.
+/*
+func IndexFile(root http.FileSystem, fpath string, indexFiles []string) (string, bool) {
+	if fpath[len(fpath)-1] != '/' || root == nil {
+		return "", false
+	}
+	for _, indexFile := range indexFiles {
+		// func (http.FileSystem).Open wants all paths separated by "/",
+		// regardless of operating system convention, so use
+		// path.Join instead of filepath.Join
+		fp := path.Join(fpath, indexFile)
+		f, err := root.Open(fp)
+		if err == nil {
+			f.Close()
+			return fp, true
+		}
+	}
+	return "", false
+}
+
+// SetLastModifiedHeader checks if the provided modTime is valid and if it is sets it
+// as a Last-Modified header to the ResponseWriter. If the modTime is in the future
+// the current time is used instead.
+func SetLastModifiedHeader(w http.ResponseWriter, modTime time.Time) {
+	if modTime.IsZero() || modTime.Equal(time.Unix(0, 0)) {
+		// the time does not appear to be valid. Don't put it in the response
+		return
+	}
+
+	// RFC 2616 - Section 14.29 - Last-Modified:
+	// An origin server MUST NOT send a Last-Modified date which is later than the
+	// server's time of message origination. In such cases, where the resource's last
+	// modification would indicate some time in the future, the server MUST replace
+	// that date with the message origination date.
+	now := currentTime()
+	if modTime.After(now) {
+		modTime = now
+	}
+
+	w.Header().Set("Last-Modified", modTime.UTC().Format(http.TimeFormat))
+}
+*/
+
+// currentTime, as it is defined here, returns time.Now().
+// It's defined as a variable for mocking time in tests.
+var currentTime = func() time.Time {
+	return time.Now()
+}