diff options
Diffstat (limited to 'middleware/middleware.go')
| -rw-r--r-- | middleware/middleware.go | 102 |
1 files changed, 0 insertions, 102 deletions
diff --git a/middleware/middleware.go b/middleware/middleware.go deleted file mode 100644 index 9e236c6e0..000000000 --- a/middleware/middleware.go +++ /dev/null @@ -1,102 +0,0 @@ -// Package middleware provides some types and functions common among middleware. -package middleware - -import ( - "errors" - "fmt" - - "github.com/miekg/dns" - ot "github.com/opentracing/opentracing-go" - "golang.org/x/net/context" -) - -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. If the status code is not one of the following: - // - // * SERVFAIL (dns.RcodeServerFailure) - // - // * REFUSED (dns.RecodeRefused) - // - // * FORMERR (dns.RcodeFormatError) - // - // * NOTIMP (dns.RcodeNotImplemented) - // - // CoreDNS assumes *no* reply has yet been written. All other response - // codes signal other handlers above it that the response message 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(context.Context, dns.ResponseWriter, *dns.Msg) (int, error) - Name() string - } - - // HandlerFunc is a convenience type like dns.HandlerFunc, except - // ServeDNS returns an rcode and an error. See Handler - // documentation for more information. - HandlerFunc func(context.Context, dns.ResponseWriter, *dns.Msg) (int, error) -) - -// ServeDNS implements the Handler interface. -func (f HandlerFunc) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { - return f(ctx, w, r) -} - -// Name implements the Handler interface. -func (f HandlerFunc) Name() string { return "handlerfunc" } - -// Error returns err with 'middleware/name: ' prefixed to it. -func Error(name string, err error) error { return fmt.Errorf("%s/%s: %s", "middleware", name, err) } - -// NextOrFailure calls next.ServeDNS when next is not nill, otherwise it will return, a ServerFailure -// and a nil error. -func NextOrFailure(name string, next Handler, ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { - if next != nil { - if span := ot.SpanFromContext(ctx); span != nil { - child := span.Tracer().StartSpan(next.Name(), ot.ChildOf(span.Context())) - defer child.Finish() - ctx = ot.ContextWithSpan(ctx, child) - } - return next.ServeDNS(ctx, w, r) - } - - return dns.RcodeServerFailure, Error(name, errors.New("no next middleware found")) -} - -// ClientWrite returns true if the response has been written to the client. -// Each middleware to adhire to this protocol. -func ClientWrite(rcode int) bool { - switch rcode { - case dns.RcodeServerFailure: - fallthrough - case dns.RcodeRefused: - fallthrough - case dns.RcodeFormatError: - fallthrough - case dns.RcodeNotImplemented: - return false - } - return true -} - -// Namespace is the namespace used for the metrics. -const Namespace = "coredns" |