Implement most of static file server; refactor and improve Replacer

caddy.go

@@ -34,7 +34,7 @@ func Run(newCfg *Config) error {
 		// modules - essentially our new config's
 		// execution environment; be sure that
 		// cleanup occurs when we return if there
-		// was an error; otherwise, it will get
+		// was an error; if no error, it will get
 		// cleaned up on next config cycle
 		ctx, cancel := NewContext(Context{Context: context.Background(), cfg: newCfg})
 		defer func() {
@@ -139,7 +139,6 @@ type Config struct {
 	StorageRaw json.RawMessage `json:"storage"`
 	storage    certmagic.Storage
 
-	TestVal string                     `json:"testval"`
 	AppsRaw map[string]json.RawMessage `json:"apps"`
 
 	// apps stores the decoded Apps values,

modules/caddyhttp/caddyhttp.go

@@ -45,7 +45,13 @@ type App struct {
 func (app *App) Provision(ctx caddy2.Context) error {
 	app.ctx = ctx
 
+	repl := caddy2.NewReplacer()
+
 	for _, srv := range app.Servers {
+		// TODO: Test this function to ensure these replacements are performed
+		for i := range srv.Listen {
+			srv.Listen[i] = repl.ReplaceAll(srv.Listen[i], "")
+		}
 		err := srv.Routes.Provision(ctx)
 		if err != nil {
 			return fmt.Errorf("setting up server routes: %v", err)
@@ -78,6 +84,13 @@ func (app *App) Validate() error {
 		}
 	}
 
+	// each server's max rehandle value must be valid
+	for srvName, srv := range app.Servers {
+		if srv.MaxRehandles < 0 {
+			return fmt.Errorf("%s: invalid max_rehandles value: %d", srvName, srv.MaxRehandles)
+		}
+	}
+
 	return nil
 }
 
@@ -231,7 +244,7 @@ func (app *App) automaticHTTPS() error {
 				redirTo += "{request.uri}"
 
 				redirRoutes = append(redirRoutes, ServerRoute{
-					matchers: []RouteMatcher{
+					matchers: []RequestMatcher{
 						matchProtocol("http"),
 						matchHost(domains),
 					},
@@ -292,84 +305,9 @@ func (app *App) listenerTaken(network, address string) bool {
 
 var defaultALPN = []string{"h2", "http/1.1"}
 
-// Server is an HTTP server.
+// RequestMatcher is a type that can match to a request.
-type Server struct {
-	Listen                []string                    `json:"listen"`
-	ReadTimeout           caddy2.Duration             `json:"read_timeout"`
-	ReadHeaderTimeout     caddy2.Duration             `json:"read_header_timeout"`
-	HiddenFiles           []string                    `json:"hidden_files"` // TODO:... experimenting with shared/common state
-	Routes                RouteList                   `json:"routes"`
-	Errors                httpErrorConfig             `json:"errors"`
-	TLSConnPolicies       caddytls.ConnectionPolicies `json:"tls_connection_policies"`
-	DisableAutoHTTPS      bool                        `json:"disable_auto_https"`
-	DisableAutoHTTPSRedir bool                        `json:"disable_auto_https_redir"`
-
-	tlsApp *caddytls.TLS
-}
-
-type httpErrorConfig struct {
-	Routes RouteList `json:"routes"`
-	// TODO: some way to configure the logging of errors, probably? standardize
-	// the logging configuration first.
-}
-
-// ServeHTTP is the entry point for all HTTP requests.
-func (s Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if s.tlsApp.HandleHTTPChallenge(w, r) {
-		return
-	}
-
-	// set up the replacer
-	repl := NewReplacer(r, w)
-	ctx := context.WithValue(r.Context(), ReplacerCtxKey, repl)
-	r = r.WithContext(ctx)
-
-	// build and execute the main middleware chain
-	stack := s.Routes.BuildHandlerChain(w, r)
-	err := executeMiddlewareChain(w, r, stack)
-	if err != nil {
-		// add the error value to the request context so
-		// it can be accessed by error handlers
-		c := context.WithValue(r.Context(), ErrorCtxKey, err)
-		r = r.WithContext(c)
-		// TODO: add error values to Replacer
-
-		if len(s.Errors.Routes) == 0 {
-			// TODO: implement a default error handler?
-			log.Printf("[ERROR] %s", err)
-		} else {
-			errStack := s.Errors.Routes.BuildHandlerChain(w, r)
-			err := executeMiddlewareChain(w, r, errStack)
-			if err != nil {
-				// TODO: what should we do if the error handler has an error?
-				log.Printf("[ERROR] handling error: %v", err)
-			}
-		}
-	}
-}
-
-// executeMiddlewareChain executes stack with w and r. This function handles
-// the special ErrRehandle error value, which reprocesses requests through
-// the stack again. Any error value returned from this function would be an
-// actual error that needs to be handled.
-func executeMiddlewareChain(w http.ResponseWriter, r *http.Request, stack Handler) error {
-	const maxRehandles = 3
-	var err error
-	for i := 0; i < maxRehandles; i++ {
-		err = stack.ServeHTTP(w, r)
-		if err != ErrRehandle {
-			break
-		}
-		if i == maxRehandles-1 {
-			return fmt.Errorf("too many rehandles")
-		}
-	}
-	return err
-}
-
-// RouteMatcher is a type that can match to a request.
 // A route matcher MUST NOT modify the request.
-type RouteMatcher interface {
+type RequestMatcher interface {
 	Match(*http.Request) bool
 }
 
@@ -421,7 +359,6 @@ func parseListenAddr(a string) (network string, addrs []string, err error) {
 	if err != nil {
 		return
 	}
-	host = NewReplacer(nil, nil).Replace(host, "")
 	ports := strings.SplitN(port, "-", 2)
 	if len(ports) == 1 {
 		ports = append(ports, ports[0])
@@ -466,25 +403,6 @@ func joinListenAddr(network, host, port string) string {
 	return a
 }
 
-type middlewareResponseWriter struct {
-	*ResponseWriterWrapper
-	allowWrites bool
-}
-
-func (mrw middlewareResponseWriter) WriteHeader(statusCode int) {
-	if !mrw.allowWrites {
-		panic("WriteHeader: middleware cannot write to the response")
-	}
-	mrw.ResponseWriterWrapper.WriteHeader(statusCode)
-}
-
-func (mrw middlewareResponseWriter) Write(b []byte) (int, error) {
-	if !mrw.allowWrites {
-		panic("Write: middleware cannot write to the response")
-	}
-	return mrw.ResponseWriterWrapper.Write(b)
-}
-
 const (
 	// DefaultHTTPPort is the default port for HTTP.
 	DefaultHTTPPort = 80
@@ -493,6 +411,5 @@ const (
 	DefaultHTTPSPort = 443
 )
 
-// Interface guards
+// Interface guard
-var _ HTTPInterfaces = middlewareResponseWriter{}
 var _ caddy2.App = (*App)(nil)

modules/caddyhttp/caddyhttp_test.go

@@ -1,7 +1,6 @@
 package caddyhttp
 
 import (
-	"os"
 	"reflect"
 	"testing"
 )
@@ -115,11 +114,6 @@ func TestJoinListenerAddr(t *testing.T) {
 }
 
 func TestParseListenerAddr(t *testing.T) {
-	hostname, err := os.Hostname()
-	if err != nil {
-		t.Fatalf("Cannot ascertain system hostname: %v", err)
-	}
-
 	for i, tc := range []struct {
 		input         string
 		expectNetwork string
@@ -176,11 +170,6 @@ func TestParseListenerAddr(t *testing.T) {
 			expectNetwork: "tcp",
 			expectAddrs:   []string{"localhost:0"},
 		},
-		{
-			input:         "{system.hostname}:0",
-			expectNetwork: "tcp",
-			expectAddrs:   []string{hostname + ":0"},
-		},
 	} {
 		actualNetwork, actualAddrs, err := parseListenAddr(tc.input)
 		if tc.expectErr && err == nil {

modules/caddyhttp/matchers.go

@@ -6,6 +6,8 @@ import (
 	"net/http"
 	"net/textproto"
 	"net/url"
+	"path"
+	"path/filepath"
 	"regexp"
 	"strings"
 
@@ -23,7 +25,8 @@ type (
 	matchHeader       http.Header
 	matchHeaderRE     map[string]*matchRegexp
 	matchProtocol     string
-	matchStarlark string
+	matchStarlarkExpr string
+	matchTable        string
 )
 
 func init() {
@@ -60,8 +63,8 @@ func init() {
 		New:  func() (interface{}, error) { return new(matchProtocol), nil },
 	})
 	caddy2.RegisterModule(caddy2.Module{
-		Name: "http.matchers.caddyscript",
+		Name: "http.matchers.starlark_expr",
-		New:  func() (interface{}, error) { return new(matchStarlark), nil },
+		New:  func() (interface{}, error) { return new(matchStarlarkExpr), nil },
 	})
 }
 
@@ -91,8 +94,17 @@ outer:
 }
 
 func (m matchPath) Match(r *http.Request) bool {
-	for _, path := range m {
+	for _, matchPath := range m {
-		if strings.HasPrefix(r.URL.Path, path) {
+		compare := r.URL.Path
+		if strings.HasPrefix(matchPath, "*") {
+			compare = path.Base(compare)
+		}
+		// can ignore error here because we can't handle it anyway
+		matches, _ := filepath.Match(matchPath, compare)
+		if matches {
+			return true
+		}
+		if strings.HasPrefix(r.URL.Path, matchPath) {
 			return true
 		}
 	}
@@ -100,7 +112,7 @@ func (m matchPath) Match(r *http.Request) bool {
 }
 
 func (m matchPathRE) Match(r *http.Request) bool {
-	repl := r.Context().Value(ReplacerCtxKey).(*Replacer)
+	repl := r.Context().Value(caddy2.ReplacerCtxKey).(caddy2.Replacer)
 	return m.match(r.URL.Path, repl, "path_regexp")
 }
 
@@ -147,7 +159,7 @@ func (m matchHeader) Match(r *http.Request) bool {
 
 func (m matchHeaderRE) Match(r *http.Request) bool {
 	for field, rm := range m {
-		repl := r.Context().Value(ReplacerCtxKey).(*Replacer)
+		repl := r.Context().Value(caddy2.ReplacerCtxKey).(caddy2.Replacer)
 		match := rm.match(r.Header.Get(field), repl, "header_regexp")
 		if !match {
 			return false
@@ -188,7 +200,7 @@ func (m matchProtocol) Match(r *http.Request) bool {
 	return false
 }
 
-func (m matchStarlark) Match(r *http.Request) bool {
+func (m matchStarlarkExpr) Match(r *http.Request) bool {
 	input := string(m)
 	thread := new(starlark.Thread)
 	env := caddyscript.MatcherEnv(r)
@@ -225,7 +237,7 @@ func (mre *matchRegexp) Validate() error {
 	return nil
 }
 
-func (mre *matchRegexp) match(input string, repl *Replacer, scope string) bool {
+func (mre *matchRegexp) match(input string, repl caddy2.Replacer, scope string) bool {
 	matches := mre.compiled.FindStringSubmatch(input)
 	if matches == nil {
 		return false
@@ -234,14 +246,14 @@ func (mre *matchRegexp) match(input string, repl *Replacer, scope string) bool {
 	// save all capture groups, first by index
 	for i, match := range matches {
 		key := fmt.Sprintf("matchers.%s.%s.%d", scope, mre.Name, i)
-		repl.Map(key, match)
+		repl.Set(key, match)
 	}
 
 	// then by name
 	for i, name := range mre.compiled.SubexpNames() {
 		if i != 0 && name != "" {
 			key := fmt.Sprintf("matchers.%s.%s.%s", scope, mre.Name, name)
-			repl.Map(key, matches[i])
+			repl.Set(key, matches[i])
 		}
 	}
 
@@ -252,13 +264,13 @@ var wordRE = regexp.MustCompile(`\w+`)
 
 // Interface guards
 var (
-	_ RouteMatcher = (*matchHost)(nil)
+	_ RequestMatcher = (*matchHost)(nil)
-	_ RouteMatcher = (*matchPath)(nil)
+	_ RequestMatcher = (*matchPath)(nil)
-	_ RouteMatcher = (*matchPathRE)(nil)
+	_ RequestMatcher = (*matchPathRE)(nil)
-	_ RouteMatcher = (*matchMethod)(nil)
+	_ RequestMatcher = (*matchMethod)(nil)
-	_ RouteMatcher = (*matchQuery)(nil)
+	_ RequestMatcher = (*matchQuery)(nil)
-	_ RouteMatcher = (*matchHeader)(nil)
+	_ RequestMatcher = (*matchHeader)(nil)
-	_ RouteMatcher = (*matchHeaderRE)(nil)
+	_ RequestMatcher = (*matchHeaderRE)(nil)
-	_ RouteMatcher = (*matchProtocol)(nil)
+	_ RequestMatcher = (*matchProtocol)(nil)
-	_ RouteMatcher = (*matchStarlark)(nil)
+	_ RequestMatcher = (*matchStarlarkExpr)(nil)
 )

modules/caddyhttp/matchers_test.go

@@ -7,6 +7,8 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"testing"
+
+	"bitbucket.org/lightcodelabs/caddy2"
 )
 
 func TestHostMatcher(t *testing.T) {
@@ -131,6 +133,26 @@ func TestPathMatcher(t *testing.T) {
 			input:  "/other/",
 			expect: true,
 		},
+		{
+			match:  matchPath{"*.ext"},
+			input:  "foo.ext",
+			expect: true,
+		},
+		{
+			match:  matchPath{"*.ext"},
+			input:  "/foo/bar.ext",
+			expect: true,
+		},
+		{
+			match:  matchPath{"/foo/*/baz"},
+			input:  "/foo/bar/baz",
+			expect: true,
+		},
+		{
+			match:  matchPath{"/foo/*/baz/bam"},
+			input:  "/foo/bar/bam",
+			expect: false,
+		},
 	} {
 		req := &http.Request{URL: &url.URL{Path: tc.input}}
 		actual := tc.match.Match(req)
@@ -205,8 +227,8 @@ func TestPathREMatcher(t *testing.T) {
 
 		// set up the fake request and its Replacer
 		req := &http.Request{URL: &url.URL{Path: tc.input}}
-		repl := NewReplacer(req, httptest.NewRecorder())
+		repl := newReplacer(req, httptest.NewRecorder())
-		ctx := context.WithValue(req.Context(), ReplacerCtxKey, repl)
+		ctx := context.WithValue(req.Context(), caddy2.ReplacerCtxKey, repl)
 		req = req.WithContext(ctx)
 
 		actual := tc.match.Match(req)
@@ -218,7 +240,7 @@ func TestPathREMatcher(t *testing.T) {
 
 		for key, expectVal := range tc.expectRepl {
 			placeholder := fmt.Sprintf("{matchers.path_regexp.%s}", key)
-			actualVal := repl.Replace(placeholder, "<empty>")
+			actualVal := repl.ReplaceAll(placeholder, "<empty>")
 			if actualVal != expectVal {
 				t.Errorf("Test %d [%v]: Expected placeholder {matchers.path_regexp.%s} to be '%s' but got '%s'",
 					i, tc.match.Pattern, key, expectVal, actualVal)
@@ -322,8 +344,8 @@ func TestHeaderREMatcher(t *testing.T) {
 
 		// set up the fake request and its Replacer
 		req := &http.Request{Header: tc.input, URL: new(url.URL)}
-		repl := NewReplacer(req, httptest.NewRecorder())
+		repl := newReplacer(req, httptest.NewRecorder())
-		ctx := context.WithValue(req.Context(), ReplacerCtxKey, repl)
+		ctx := context.WithValue(req.Context(), caddy2.ReplacerCtxKey, repl)
 		req = req.WithContext(ctx)
 
 		actual := tc.match.Match(req)
@@ -335,7 +357,7 @@ func TestHeaderREMatcher(t *testing.T) {
 
 		for key, expectVal := range tc.expectRepl {
 			placeholder := fmt.Sprintf("{matchers.header_regexp.%s}", key)
-			actualVal := repl.Replace(placeholder, "<empty>")
+			actualVal := repl.ReplaceAll(placeholder, "<empty>")
 			if actualVal != expectVal {
 				t.Errorf("Test %d [%v]: Expected placeholder {matchers.header_regexp.%s} to be '%s' but got '%s'",
 					i, tc.match, key, expectVal, actualVal)

modules/caddyhttp/replacer.go

@@ -1,119 +1,83 @@
 package caddyhttp
 
 import (
+	"fmt"
 	"net"
 	"net/http"
-	"os"
+	"path"
 	"strings"
 
 	"bitbucket.org/lightcodelabs/caddy2"
 )
 
-// Replacer can replace values in strings based
+// TODO: A simple way to format or escape or encode each value would be nice
-// on a request and/or response writer. The zero
+// ... TODO: Should we just use templates? :-/ yeesh...
-// Replacer is not valid; use NewReplacer() to
-// initialize one.
-type Replacer struct {
-	req    *http.Request
-	resp   http.ResponseWriter
-	custom map[string]string
-}
 
-// NewReplacer makes a new Replacer, initializing all necessary
+func newReplacer(req *http.Request, w http.ResponseWriter) caddy2.Replacer {
-// fields. The request and response writer are optional, but
+	repl := caddy2.NewReplacer()
-// necessary for most replacements to work.
-func NewReplacer(req *http.Request, rw http.ResponseWriter) *Replacer {
-	return &Replacer{
-		req:    req,
-		resp:   rw,
-		custom: make(map[string]string),
-	}
-}
 
-// Map sets a custom variable mapping to a value.
+	httpVars := func() map[string]string {
-func (r *Replacer) Map(variable, value string) {
+		m := make(map[string]string)
-	r.custom[variable] = value
+		if req != nil {
-}
+			m["http.request.host"] = func() string {
-
+				host, _, err := net.SplitHostPort(req.Host)
-// Replace replaces placeholders in input with the value. If
-// the value is empty string, the placeholder is substituted
-// with the value empty.
-func (r *Replacer) Replace(input, empty string) string {
-	if !strings.Contains(input, phOpen) {
-		return input
-	}
-
-	input = r.replaceAll(input, empty, r.defaults())
-	input = r.replaceAll(input, empty, r.custom)
-
-	return input
-}
-
-func (r *Replacer) replaceAll(input, empty string, mapping map[string]string) string {
-	for key, val := range mapping {
-		if val == "" {
-			val = empty
-		}
-		input = strings.ReplaceAll(input, phOpen+key+phClose, val)
-	}
-	return input
-}
-
-func (r *Replacer) defaults() map[string]string {
-	m := map[string]string{
-		"system.hostname": func() string {
-			// OK if there is an error; just return empty string
-			name, _ := os.Hostname()
-			return name
-		}(),
-	}
-
-	if r.req != nil {
-		m["request.host"] = func() string {
-			host, _, err := net.SplitHostPort(r.req.Host)
 				if err != nil {
-				return r.req.Host // OK; there probably was no port
+					return req.Host // OK; there probably was no port
 				}
 				return host
 			}()
-		m["request.hostport"] = r.req.Host // may include both host and port
+			m["http.request.hostport"] = req.Host // may include both host and port
-		m["request.method"] = r.req.Method
+			m["http.request.method"] = req.Method
-		m["request.port"] = func() string {
+			m["http.request.port"] = func() string {
 				// if there is no port, there will be an error; in
 				// that case, port is the empty string anyway
-			_, port, _ := net.SplitHostPort(r.req.Host)
+				_, port, _ := net.SplitHostPort(req.Host)
 				return port
 			}()
-		m["request.scheme"] = func() string {
+			m["http.request.scheme"] = func() string {
-			if r.req.TLS != nil {
+				if req.TLS != nil {
 					return "https"
 				}
 				return "http"
 			}()
-		m["request.uri"] = r.req.URL.RequestURI()
+			m["http.request.uri"] = req.URL.RequestURI()
-		m["request.uri.path"] = r.req.URL.Path
+			m["http.request.uri.path"] = req.URL.Path
+			m["http.request.uri.path.file"] = func() string {
+				_, file := path.Split(req.URL.Path)
+				return file
+			}()
+			m["http.request.uri.path.dir"] = func() string {
+				dir, _ := path.Split(req.URL.Path)
+				return dir
+			}()
 
-		for field, vals := range r.req.Header {
+			for field, vals := range req.Header {
-			m["request.header."+strings.ToLower(field)] = strings.Join(vals, ",")
+				m["http.request.header."+strings.ToLower(field)] = strings.Join(vals, ",")
 			}
-		for _, cookie := range r.req.Cookies() {
+			for _, cookie := range req.Cookies() {
-			m["request.cookie."+cookie.Name] = cookie.Value
+				m["http.request.cookie."+cookie.Name] = cookie.Value
 			}
-		for param, vals := range r.req.URL.Query() {
+			for param, vals := range req.URL.Query() {
-			m["request.uri.query."+param] = strings.Join(vals, ",")
+				m["http.request.uri.query."+param] = strings.Join(vals, ",")
+			}
+
+			hostLabels := strings.Split(req.Host, ".")
+			for i, label := range hostLabels {
+				key := fmt.Sprintf("http.request.host.labels.%d", len(hostLabels)-i-1)
+				m[key] = label
 			}
 		}
 
-	if r.resp != nil {
+		if w != nil {
-		for field, vals := range r.resp.Header() {
+			for field, vals := range w.Header() {
-			m["response.header."+strings.ToLower(field)] = strings.Join(vals, ",")
+				m["http.response.header."+strings.ToLower(field)] = strings.Join(vals, ",")
 			}
 		}
 
 		return m
+	}
+
+	repl.Map(httpVars)
+
+	return repl
 }
-
-const phOpen, phClose = "{", "}"
-
-// ReplacerCtxKey is the context key for the request's replacer.
-const ReplacerCtxKey caddy2.CtxKey = "replacer"

modules/caddyhttp/routes.go

@@ -12,6 +12,7 @@ import (
 // middlewares, and a responder for handling HTTP
 // requests.
 type ServerRoute struct {
+	Group    string                     `json:"group"`
 	Matchers map[string]json.RawMessage `json:"match"`
 	Apply    []json.RawMessage          `json:"apply"`
 	Respond  json.RawMessage            `json:"respond"`
@@ -19,7 +20,7 @@ type ServerRoute struct {
 	Terminal bool `json:"terminal"`
 
 	// decoded values
-	matchers   []RouteMatcher
+	matchers   []RequestMatcher
 	middleware []MiddlewareHandler
 	responder  Handler
 }
@@ -37,7 +38,7 @@ func (routes RouteList) Provision(ctx caddy2.Context) error {
 			if err != nil {
 				return fmt.Errorf("loading matcher module '%s': %v", modName, err)
 			}
-			routes[i].matchers = append(routes[i].matchers, val.(RouteMatcher))
+			routes[i].matchers = append(routes[i].matchers, val.(RequestMatcher))
 		}
 		routes[i].Matchers = nil // allow GC to deallocate - TODO: Does this help?
 
@@ -64,9 +65,9 @@ func (routes RouteList) Provision(ctx caddy2.Context) error {
 	return nil
 }
 
-// BuildHandlerChain creates a chain of handlers by
+// BuildCompositeRoute creates a chain of handlers by
 // applying all the matching routes.
-func (routes RouteList) BuildHandlerChain(w http.ResponseWriter, r *http.Request) Handler {
+func (routes RouteList) BuildCompositeRoute(w http.ResponseWriter, r *http.Request) Handler {
 	if len(routes) == 0 {
 		return emptyHandler
 	}
@@ -74,17 +75,39 @@ func (routes RouteList) BuildHandlerChain(w http.ResponseWriter, r *http.Request
 	var mid []Middleware
 	var responder Handler
 	mrw := &middlewareResponseWriter{ResponseWriterWrapper: &ResponseWriterWrapper{w}}
+	groups := make(map[string]struct{})
 
 routeLoop:
 	for _, route := range routes {
+		// see if route matches
 		for _, m := range route.matchers {
 			if !m.Match(r) {
 				continue routeLoop
 			}
 		}
+
+		// if route is part of a group, ensure only
+		// the first matching route in the group is
+		// applied
+		if route.Group != "" {
+			_, ok := groups[route.Group]
+			if ok {
+				// this group has already been satisfied
+				// by a matching route
+				continue
+			}
+			// this matching route satisfies the group
+			groups[route.Group] = struct{}{}
+		}
+
+		// apply the rest of the route
 		for _, m := range route.middleware {
 			mid = append(mid, func(next HandlerFunc) HandlerFunc {
 				return func(w http.ResponseWriter, r *http.Request) error {
+					// TODO: This is where request tracing could be implemented; also
+					// see below to trace the responder as well
+					// TODO: Trace a diff of the request, would be cool too! see what changed since the last middleware (host, headers, URI...)
+					// TODO: see what the std lib gives us in terms of stack trracing too
 					return m.ServeHTTP(mrw, r, next)
 				}
 			})
@@ -111,3 +134,25 @@ routeLoop:
 
 	return stack
 }
+
+type middlewareResponseWriter struct {
+	*ResponseWriterWrapper
+	allowWrites bool
+}
+
+func (mrw middlewareResponseWriter) WriteHeader(statusCode int) {
+	if !mrw.allowWrites {
+		panic("WriteHeader: middleware cannot write to the response")
+	}
+	mrw.ResponseWriterWrapper.WriteHeader(statusCode)
+}
+
+func (mrw middlewareResponseWriter) Write(b []byte) (int, error) {
+	if !mrw.allowWrites {
+		panic("Write: middleware cannot write to the response")
+	}
+	return mrw.ResponseWriterWrapper.Write(b)
+}
+
+// Interface guard
+var _ HTTPInterfaces = middlewareResponseWriter{}

modules/caddyhttp/server.go

@@ -0,0 +1,91 @@
+package caddyhttp
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+
+	"bitbucket.org/lightcodelabs/caddy2"
+	"bitbucket.org/lightcodelabs/caddy2/modules/caddytls"
+)
+
+// Server is an HTTP server.
+type Server struct {
+	Listen                []string                    `json:"listen"`
+	ReadTimeout           caddy2.Duration             `json:"read_timeout"`
+	ReadHeaderTimeout     caddy2.Duration             `json:"read_header_timeout"`
+	Routes                RouteList                   `json:"routes"`
+	Errors                httpErrorConfig             `json:"errors"`
+	TLSConnPolicies       caddytls.ConnectionPolicies `json:"tls_connection_policies"`
+	DisableAutoHTTPS      bool                        `json:"disable_auto_https"`
+	DisableAutoHTTPSRedir bool                        `json:"disable_auto_https_redir"`
+	MaxRehandles          int                         `json:"max_rehandles"`
+
+	tlsApp *caddytls.TLS
+}
+
+// ServeHTTP is the entry point for all HTTP requests.
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if s.tlsApp.HandleHTTPChallenge(w, r) {
+		return
+	}
+
+	// set up the replacer
+	repl := newReplacer(r, w)
+	ctx := context.WithValue(r.Context(), caddy2.ReplacerCtxKey, repl)
+	ctx = context.WithValue(ctx, TableCtxKey, make(map[string]interface{})) // TODO: Implement this
+	r = r.WithContext(ctx)
+
+	// build and execute the main handler chain
+	stack := s.Routes.BuildCompositeRoute(w, r)
+	err := s.executeCompositeRoute(w, r, stack)
+	if err != nil {
+		// add the error value to the request context so
+		// it can be accessed by error handlers
+		c := context.WithValue(r.Context(), ErrorCtxKey, err)
+		r = r.WithContext(c)
+		// TODO: add error values to Replacer
+
+		if len(s.Errors.Routes) == 0 {
+			// TODO: implement a default error handler?
+			log.Printf("[ERROR] %s", err)
+		} else {
+			errStack := s.Errors.Routes.BuildCompositeRoute(w, r)
+			err := s.executeCompositeRoute(w, r, errStack)
+			if err != nil {
+				// TODO: what should we do if the error handler has an error?
+				log.Printf("[ERROR] handling error: %v", err)
+			}
+		}
+	}
+}
+
+// executeCompositeRoute executes stack with w and r. This function handles
+// the special ErrRehandle error value, which reprocesses requests through
+// the stack again. Any error value returned from this function would be an
+// actual error that needs to be handled.
+func (s *Server) executeCompositeRoute(w http.ResponseWriter, r *http.Request, stack Handler) error {
+	var err error
+	for i := -1; i <= s.MaxRehandles; i++ {
+		// we started the counter at -1 because we
+		// always want to run this at least once
+		err = stack.ServeHTTP(w, r)
+		if err != ErrRehandle {
+			break
+		}
+		if i >= s.MaxRehandles-1 {
+			return fmt.Errorf("too many rehandles")
+		}
+	}
+	return err
+}
+
+type httpErrorConfig struct {
+	Routes RouteList `json:"routes"`
+	// TODO: some way to configure the logging of errors, probably? standardize
+	// the logging configuration first.
+}
+
+// TableCtxKey is the context key for the request's variable table.
+const TableCtxKey caddy2.CtxKey = "table"

modules/caddyhttp/staticfiles/browse.go

@@ -0,0 +1,205 @@
+package staticfiles
+
+import (
+	"net/http"
+)
+
+// Browse configures directory browsing.
+type Browse struct {
+}
+
+// ServeHTTP determines if the request is for this plugin, and if all prerequisites are met.
+// If so, control is handed over to ServeListing.
+func (b Browse) ServeHTTP(w http.ResponseWriter, r *http.Request) error {
+	// TODO: convert this handler
+	return nil
+
+	// // Browse works on existing directories; delegate everything else
+	// requestedFilepath, err := bc.Fs.Root.Open(r.URL.Path)
+	// if err != nil {
+	// 	switch {
+	// 	case os.IsPermission(err):
+	// 		return http.StatusForbidden, err
+	// 	case os.IsExist(err):
+	// 		return http.StatusNotFound, err
+	// 	default:
+	// 		return b.Next.ServeHTTP(w, r)
+	// 	}
+	// }
+	// defer requestedFilepath.Close()
+
+	// info, err := requestedFilepath.Stat()
+	// if err != nil {
+	// 	switch {
+	// 	case os.IsPermission(err):
+	// 		return http.StatusForbidden, err
+	// 	case os.IsExist(err):
+	// 		return http.StatusGone, err
+	// 	default:
+	// 		return b.Next.ServeHTTP(w, r)
+	// 	}
+	// }
+	// if !info.IsDir() {
+	// 	return b.Next.ServeHTTP(w, r)
+	// }
+
+	// // Do not reply to anything else because it might be nonsensical
+	// switch r.Method {
+	// case http.MethodGet, http.MethodHead:
+	// 	// proceed, noop
+	// case "PROPFIND", http.MethodOptions:
+	// 	return http.StatusNotImplemented, nil
+	// default:
+	// 	return b.Next.ServeHTTP(w, r)
+	// }
+
+	// // Browsing navigation gets messed up if browsing a directory
+	// // that doesn't end in "/" (which it should, anyway)
+	// u := *r.URL
+	// if u.Path == "" {
+	// 	u.Path = "/"
+	// }
+	// if u.Path[len(u.Path)-1] != '/' {
+	// 	u.Path += "/"
+	// 	http.Redirect(w, r, u.String(), http.StatusMovedPermanently)
+	// 	return http.StatusMovedPermanently, nil
+	// }
+
+	// return b.ServeListing(w, r, requestedFilepath, bc)
+}
+
+// func (b Browse) loadDirectoryContents(requestedFilepath http.File, urlPath string, config *Config) (*Listing, bool, error) {
+// 	files, err := requestedFilepath.Readdir(-1)
+// 	if err != nil {
+// 		return nil, false, err
+// 	}
+
+// 	// Determine if user can browse up another folder
+// 	var canGoUp bool
+// 	curPathDir := path.Dir(strings.TrimSuffix(urlPath, "/"))
+// 	for _, other := range b.Configs {
+// 		if strings.HasPrefix(curPathDir, other.PathScope) {
+// 			canGoUp = true
+// 			break
+// 		}
+// 	}
+
+// 	// Assemble listing of directory contents
+// 	listing, hasIndex := directoryListing(files, canGoUp, urlPath, config)
+
+// 	return &listing, hasIndex, nil
+// }
+
+// // handleSortOrder gets and stores for a Listing the 'sort' and 'order',
+// // and reads 'limit' if given. The latter is 0 if not given.
+// //
+// // This sets Cookies.
+// func (b Browse) handleSortOrder(w http.ResponseWriter, r *http.Request, scope string) (sort string, order string, limit int, err error) {
+// 	sort, order, limitQuery := r.URL.Query().Get("sort"), r.URL.Query().Get("order"), r.URL.Query().Get("limit")
+
+// 	// If the query 'sort' or 'order' is empty, use defaults or any values previously saved in Cookies
+// 	switch sort {
+// 	case "":
+// 		sort = sortByNameDirFirst
+// 		if sortCookie, sortErr := r.Cookie("sort"); sortErr == nil {
+// 			sort = sortCookie.Value
+// 		}
+// 	case sortByName, sortByNameDirFirst, sortBySize, sortByTime:
+// 		http.SetCookie(w, &http.Cookie{Name: "sort", Value: sort, Path: scope, Secure: r.TLS != nil})
+// 	}
+
+// 	switch order {
+// 	case "":
+// 		order = "asc"
+// 		if orderCookie, orderErr := r.Cookie("order"); orderErr == nil {
+// 			order = orderCookie.Value
+// 		}
+// 	case "asc", "desc":
+// 		http.SetCookie(w, &http.Cookie{Name: "order", Value: order, Path: scope, Secure: r.TLS != nil})
+// 	}
+
+// 	if limitQuery != "" {
+// 		limit, err = strconv.Atoi(limitQuery)
+// 		if err != nil { // if the 'limit' query can't be interpreted as a number, return err
+// 			return
+// 		}
+// 	}
+
+// 	return
+// }
+
+// // ServeListing returns a formatted view of 'requestedFilepath' contents'.
+// func (b Browse) ServeListing(w http.ResponseWriter, r *http.Request, requestedFilepath http.File, bc *Config) (int, error) {
+// 	listing, containsIndex, err := b.loadDirectoryContents(requestedFilepath, r.URL.Path, bc)
+// 	if err != nil {
+// 		switch {
+// 		case os.IsPermission(err):
+// 			return http.StatusForbidden, err
+// 		case os.IsExist(err):
+// 			return http.StatusGone, err
+// 		default:
+// 			return http.StatusInternalServerError, err
+// 		}
+// 	}
+// 	if containsIndex && !b.IgnoreIndexes { // directory isn't browsable
+// 		return b.Next.ServeHTTP(w, r)
+// 	}
+// 	listing.Context = httpserver.Context{
+// 		Root: bc.Fs.Root,
+// 		Req:  r,
+// 		URL:  r.URL,
+// 	}
+// 	listing.User = bc.Variables
+
+// 	// Copy the query values into the Listing struct
+// 	var limit int
+// 	listing.Sort, listing.Order, limit, err = b.handleSortOrder(w, r, bc.PathScope)
+// 	if err != nil {
+// 		return http.StatusBadRequest, err
+// 	}
+
+// 	listing.applySort()
+
+// 	if limit > 0 && limit <= len(listing.Items) {
+// 		listing.Items = listing.Items[:limit]
+// 		listing.ItemsLimitedTo = limit
+// 	}
+
+// 	var buf *bytes.Buffer
+// 	acceptHeader := strings.ToLower(strings.Join(r.Header["Accept"], ","))
+// 	switch {
+// 	case strings.Contains(acceptHeader, "application/json"):
+// 		if buf, err = b.formatAsJSON(listing, bc); err != nil {
+// 			return http.StatusInternalServerError, err
+// 		}
+// 		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+
+// 	default: // There's no 'application/json' in the 'Accept' header; browse normally
+// 		if buf, err = b.formatAsHTML(listing, bc); err != nil {
+// 			return http.StatusInternalServerError, err
+// 		}
+// 		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+
+// 	}
+
+// 	_, _ = buf.WriteTo(w)
+
+// 	return http.StatusOK, nil
+// }
+
+// func (b Browse) formatAsJSON(listing *Listing, bc *Config) (*bytes.Buffer, error) {
+// 	marsh, err := json.Marshal(listing.Items)
+// 	if err != nil {
+// 		return nil, err
+// 	}
+
+// 	buf := new(bytes.Buffer)
+// 	_, err = buf.Write(marsh)
+// 	return buf, err
+// }
+
+// func (b Browse) formatAsHTML(listing *Listing, bc *Config) (*bytes.Buffer, error) {
+// 	buf := new(bytes.Buffer)
+// 	err := bc.Template.Execute(buf, listing)
+// 	return buf, err
+// }

modules/caddyhttp/staticfiles/matcher.go

@@ -0,0 +1,54 @@
+package staticfiles
+
+import (
+	"net/http"
+	"os"
+	"path/filepath"
+
+	"bitbucket.org/lightcodelabs/caddy2"
+	"bitbucket.org/lightcodelabs/caddy2/modules/caddyhttp"
+)
+
+func init() {
+	caddy2.RegisterModule(caddy2.Module{
+		Name: "http.matchers.file",
+		New:  func() (interface{}, error) { return new(FileMatcher), nil },
+	})
+}
+
+// TODO: Not sure how to do this well; we'd need the ability to
+// hide files, etc...
+// TODO: Also consider a feature to match directory that
+// contains a certain filename (use filepath.Glob), useful
+// if wanting to map directory-URI requests where the dir
+// has index.php to PHP backends, for example (although this
+// can effectively be done with rehandling already)
+type FileMatcher struct {
+	Root  string   `json:"root"`
+	Path  string   `json:"path"`
+	Flags []string `json:"flags"`
+}
+
+func (m FileMatcher) Match(r *http.Request) bool {
+	// TODO: sanitize path
+	fullPath := filepath.Join(m.Root, m.Path)
+	var match bool
+	if len(m.Flags) > 0 {
+		match = true
+		fi, err := os.Stat(fullPath)
+		for _, f := range m.Flags {
+			switch f {
+			case "EXIST":
+				match = match && os.IsNotExist(err)
+			case "DIR":
+				match = match && err == nil && fi.IsDir()
+			default:
+				match = false
+			}
+		}
+	}
+	return match
+}
+
+// Interface guard
+var _ caddyhttp.RequestMatcher = (*FileMatcher)(nil)

modules/caddyhttp/staticfiles/staticfiles.go

@@ -1,7 +1,15 @@
 package staticfiles
 
 import (
+	"fmt"
+	weakrand "math/rand"
 	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
 
 	"bitbucket.org/lightcodelabs/caddy2"
 	"bitbucket.org/lightcodelabs/caddy2/modules/caddyhttp"
@@ -16,13 +24,298 @@ func init() {
 
 // StaticFiles implements a static file server responder for Caddy.
 type StaticFiles struct {
-	Root string
+	Root            string              `json:"root"` // default is current directory
+	IndexNames      []string            `json:"index_names"`
+	Files           []string            `json:"files"` // all relative to the root; default is request URI path
+	SelectionPolicy string              `json:"selection_policy"`
+	Fallback        caddyhttp.RouteList `json:"fallback"`
+	Browse          *Browse             `json:"browse"`
+	Hide            []string            `json:"hide"`
+	Rehandle        bool                `json:"rehandle"` // issue a rehandle (internal redirect) if request is rewritten
+	// TODO: Etag
+	// TODO: Content negotiation
 }
 
-func (sf StaticFiles) ServeHTTP(w http.ResponseWriter, r *http.Request) error {
+// Provision sets up the static files responder.
-	http.FileServer(http.Dir(sf.Root)).ServeHTTP(w, r)
+func (sf *StaticFiles) Provision(ctx caddy2.Context) error {
+	if sf.Fallback != nil {
+		err := sf.Fallback.Provision(ctx)
+		if err != nil {
+			return fmt.Errorf("setting up fallback routes: %v", err)
+		}
+	}
+	if sf.IndexNames == nil {
+		sf.IndexNames = defaultIndexNames
+	}
 	return nil
 }
 
+// Validate ensures that sf has a valid configuration.
+func (sf *StaticFiles) Validate() error {
+	switch sf.SelectionPolicy {
+	case "",
+		"first_existing",
+		"largest_size",
+		"smallest_size",
+		"most_recently_modified":
+	default:
+		return fmt.Errorf("unknown selection policy %s", sf.SelectionPolicy)
+	}
+	return nil
+}
+
+func (sf *StaticFiles) ServeHTTP(w http.ResponseWriter, r *http.Request) error {
+	// TODO: Prevent directory traversal, see https://play.golang.org/p/oh77BiVQFti
+
+	// http.FileServer(http.Dir(sf.Directory)).ServeHTTP(w, r)
+
+	//////////////
+
+	// TODO: Still needed?
+	// // Prevent absolute path access on Windows, e.g.: http://localhost:5000/C:\Windows\notepad.exe
+	// // TODO: does stdlib http.Dir handle this? see first check of http.Dir.Open()...
+	// if runtime.GOOS == "windows" && len(reqPath) > 0 && filepath.IsAbs(reqPath[1:]) {
+	// 	return caddyhttp.Error(http.StatusNotFound, fmt.Errorf("request path was absolute"))
+	// }
+
+	repl := r.Context().Value(caddy2.ReplacerCtxKey).(caddy2.Replacer)
+
+	// map the request to a filename
+	pathBefore := r.URL.Path
+	filename := sf.selectFile(r, repl)
+	if filename == "" {
+		// no files worked, so resort to fallback
+		if sf.Fallback != nil {
+			fallback := sf.Fallback.BuildCompositeRoute(w, r)
+			return fallback.ServeHTTP(w, r)
+		}
+		return caddyhttp.Error(http.StatusNotFound, nil)
+	}
+
+	// if the ultimate destination has changed, submit
+	// this request for a rehandling (internal redirect)
+	// if configured to do so
+	// TODO: double check this against https://docs.nginx.com/nginx/admin-guide/web-server/serving-static-content/
+	if r.URL.Path != pathBefore && sf.Rehandle {
+		return caddyhttp.ErrRehandle
+	}
+
+	// get information about the file
+	info, err := os.Stat(filename)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return caddyhttp.Error(http.StatusNotFound, err)
+		} else if os.IsPermission(err) {
+			return caddyhttp.Error(http.StatusForbidden, err)
+		}
+		// TODO: treat this as resource exhaustion like with os.Open? Or unnecessary here?
+		return caddyhttp.Error(http.StatusInternalServerError, err)
+	}
+
+	// if the request mapped to a directory, see if
+	// there is an index file we can serve
+	if info.IsDir() && len(sf.IndexNames) > 0 {
+		filesToHide := sf.transformHidePaths(repl)
+
+		for _, indexPage := range sf.IndexNames {
+			indexPath := path.Join(filename, indexPage)
+			if fileIsHidden(indexPath, filesToHide) {
+				// pretend this file doesn't exist
+				continue
+			}
+
+			indexInfo, err := os.Stat(indexPath)
+			if err != nil {
+				continue
+			}
+
+			// we found an index file that might work,
+			// so rewrite the request path and, if
+			// configured, do an internal redirect
+			// TODO: I don't know if the logic for rewriting
+			// the URL here is the right logic
+			r.URL.Path = path.Join(r.URL.Path, indexPage)
+			if sf.Rehandle {
+				return caddyhttp.ErrRehandle
+			}
+
+			info = indexInfo
+			break
+		}
+	}
+
+	// if still referencing a directory, delegate
+	// to browse or return an error
+	if info.IsDir() {
+		if sf.Browse != nil {
+			return sf.Browse.ServeHTTP(w, r)
+		}
+		return caddyhttp.Error(http.StatusNotFound, nil)
+	}
+
+	// open the file
+	file, err := os.Open(info.Name())
+	if err != nil {
+		if os.IsNotExist(err) {
+			return caddyhttp.Error(http.StatusNotFound, err)
+		} else if os.IsPermission(err) {
+			return caddyhttp.Error(http.StatusForbidden, err)
+		}
+		// maybe the server is under load and ran out of file descriptors?
+		// have client wait arbitrary seconds to help prevent a stampede
+		backoff := weakrand.Intn(maxBackoff-minBackoff) + minBackoff
+		w.Header().Set("Retry-After", strconv.Itoa(backoff))
+		return caddyhttp.Error(http.StatusServiceUnavailable, err)
+	}
+	defer file.Close()
+
+	// TODO: Right now we return an invalid response if the
+	// request is for a directory and there is no index file
+	// or dir browsing; we should return a 404 I think...
+
+	// TODO: Etag?
+
+	// TODO: content negotiation? (brotli sidecar files, etc...)
+
+	// let the standard library do what it does best; note, however,
+	// that errors generated by ServeContent are written immediately
+	// to the response, so we cannot handle them (but errors here are rare)
+	http.ServeContent(w, r, info.Name(), info.ModTime(), file)
+
+	return nil
+}
+
+func (sf *StaticFiles) transformHidePaths(repl caddy2.Replacer) []string {
+	hide := make([]string, len(sf.Hide))
+	for i := range sf.Hide {
+		hide[i] = repl.ReplaceAll(sf.Hide[i], "")
+	}
+	return hide
+}
+
+func (sf *StaticFiles) selectFile(r *http.Request, repl caddy2.Replacer) string {
+	root := repl.ReplaceAll(sf.Root, "")
+	if root == "" {
+		root = "."
+	}
+
+	if sf.Files == nil {
+		return filepath.Join(root, r.URL.Path)
+	}
+
+	switch sf.SelectionPolicy {
+	// TODO: Make these policy names constants
+	case "", "first_existing":
+		filesToHide := sf.transformHidePaths(repl)
+		for _, f := range sf.Files {
+			suffix := repl.ReplaceAll(f, "")
+			// TODO: sanitize path
+			fullpath := filepath.Join(root, suffix)
+			if !fileIsHidden(fullpath, filesToHide) && fileExists(fullpath) {
+				r.URL.Path = suffix
+				return fullpath
+			}
+		}
+
+	case "largest_size":
+		var largestSize int64
+		var largestFilename string
+		var largestSuffix string
+		for _, f := range sf.Files {
+			suffix := repl.ReplaceAll(f, "")
+			// TODO: sanitize path
+			fullpath := filepath.Join(root, suffix)
+			info, err := os.Stat(fullpath)
+			if err == nil && info.Size() > largestSize {
+				largestSize = info.Size()
+				largestFilename = fullpath
+				largestSuffix = suffix
+			}
+		}
+		r.URL.Path = largestSuffix
+		return largestFilename
+
+	case "smallest_size":
+		var smallestSize int64
+		var smallestFilename string
+		var smallestSuffix string
+		for _, f := range sf.Files {
+			suffix := repl.ReplaceAll(f, "")
+			// TODO: sanitize path
+			fullpath := filepath.Join(root, suffix)
+			info, err := os.Stat(fullpath)
+			if err == nil && (smallestSize == 0 || info.Size() < smallestSize) {
+				smallestSize = info.Size()
+				smallestFilename = fullpath
+				smallestSuffix = suffix
+			}
+		}
+		r.URL.Path = smallestSuffix
+		return smallestFilename
+
+	case "most_recently_modified":
+		var recentDate time.Time
+		var recentFilename string
+		var recentSuffix string
+		for _, f := range sf.Files {
+			suffix := repl.ReplaceAll(f, "")
+			// TODO: sanitize path
+			fullpath := filepath.Join(root, suffix)
+			info, err := os.Stat(fullpath)
+			if err == nil &&
+				(recentDate.IsZero() || info.ModTime().After(recentDate)) {
+				recentDate = info.ModTime()
+				recentFilename = fullpath
+				recentSuffix = suffix
+			}
+		}
+		r.URL.Path = recentSuffix
+		return recentFilename
+	}
+
+	return ""
+}
+
+// fileExists returns true if file exists.
+func fileExists(file string) bool {
+	_, err := os.Stat(file)
+	return !os.IsNotExist(err)
+}
+
+func fileIsHidden(filename string, hide []string) bool {
+	nameOnly := filepath.Base(filename)
+	sep := string(filepath.Separator)
+
+	// see if file is hidden
+	for _, h := range hide {
+		// assuming h is a glob/shell-like pattern,
+		// use it to compare the whole file path;
+		// but if there is no separator in h, then
+		// just compare against the file's name
+		compare := filename
+		if !strings.Contains(h, sep) {
+			compare = nameOnly
+		}
+
+		hidden, err := filepath.Match(h, compare)
+		if err != nil {
+			// malformed pattern; fallback by checking prefix
+			if strings.HasPrefix(filename, h) {
+				return true
+			}
+		}
+		if hidden {
+			// file name or path matches hide pattern
+			return true
+		}
+	}
+
+	return false
+}
+
+var defaultIndexNames = []string{"index.html"}
+
+const minBackoff, maxBackoff = 2, 5
+
 // Interface guard
 var _ caddyhttp.Handler = (*StaticFiles)(nil)

modules/caddyhttp/staticresp.go

@@ -23,16 +23,16 @@ type Static struct {
 }
 
 func (s Static) ServeHTTP(w http.ResponseWriter, r *http.Request) error {
-	repl := r.Context().Value(ReplacerCtxKey).(*Replacer)
+	repl := r.Context().Value(caddy2.ReplacerCtxKey).(caddy2.Replacer)
 
 	// close the connection after responding
 	r.Close = s.Close
 
 	// set all headers, with replacements
 	for field, vals := range s.Headers {
-		field = repl.Replace(field, "")
+		field = repl.ReplaceAll(field, "")
 		for i := range vals {
-			vals[i] = repl.Replace(vals[i], "")
+			vals[i] = repl.ReplaceAll(vals[i], "")
 		}
 		w.Header()[field] = vals
 	}
@@ -46,7 +46,7 @@ func (s Static) ServeHTTP(w http.ResponseWriter, r *http.Request) error {
 
 	// write the response body, with replacements
 	if s.Body != "" {
-		fmt.Fprint(w, repl.Replace(s.Body, ""))
+		fmt.Fprint(w, repl.ReplaceAll(s.Body, ""))
 	}
 
 	return nil

modules/caddyhttp/table.go

@@ -0,0 +1,41 @@
+package caddyhttp
+
+import (
+	"net/http"
+
+	"bitbucket.org/lightcodelabs/caddy2"
+)
+
+func init() {
+	caddy2.RegisterModule(caddy2.Module{
+		Name: "http.middleware.table",
+		New:  func() (interface{}, error) { return new(tableMiddleware), nil },
+	})
+
+	caddy2.RegisterModule(caddy2.Module{
+		Name: "http.matchers.table",
+		New:  func() (interface{}, error) { return new(tableMatcher), nil },
+	})
+}
+
+type tableMiddleware struct {
+}
+
+func (t tableMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error {
+	// tbl := r.Context().Value(TableCtxKey).(map[string]interface{})
+
+	// TODO: implement this...
+
+	return nil
+}
+
+type tableMatcher struct {
+}
+
+func (m tableMatcher) Match(r *http.Request) bool {
+	return false // TODO: implement
+}
+
+// Interface guards
+var _ MiddlewareHandler = (*tableMiddleware)(nil)
+var _ RequestMatcher = (*tableMatcher)(nil)

replacer.go

@@ -0,0 +1,104 @@
+package caddy2
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+// Replacer can replace values in strings.
+type Replacer interface {
+	Set(variable, value string)
+	Delete(variable string)
+	Map(func() map[string]string)
+	ReplaceAll(input, empty string) string
+}
+
+// NewReplacer returns a new Replacer.
+func NewReplacer() Replacer {
+	rep := &replacer{
+		static: make(map[string]string),
+	}
+	rep.providers = []ReplacementsFunc{
+		defaultReplacements,
+		func() map[string]string { return rep.static },
+	}
+	return rep
+}
+
+type replacer struct {
+	providers []ReplacementsFunc
+	static    map[string]string
+}
+
+// Map augments the map of replacements with those returned
+// by the given replacements function. The function is only
+// executed at replace-time.
+func (r *replacer) Map(replacements func() map[string]string) {
+	r.providers = append(r.providers, replacements)
+}
+
+// Set sets a custom variable to a static value.
+func (r *replacer) Set(variable, value string) {
+	r.static[variable] = value
+}
+
+// Delete removes a variable with a static value
+// that was created using Set.
+func (r *replacer) Delete(variable string) {
+	delete(r.static, variable)
+}
+
+// ReplaceAll replaces placeholders in input with their values.
+// Values that are empty string will be substituted with the
+// empty parameter.
+func (r *replacer) ReplaceAll(input, empty string) string {
+	if !strings.Contains(input, phOpen) {
+		return input
+	}
+	for _, replacements := range r.providers {
+		for key, val := range replacements() {
+			if val == "" {
+				val = empty
+			}
+			input = strings.ReplaceAll(input, phOpen+key+phClose, val)
+		}
+	}
+	return input
+}
+
+// ReplacementsFunc is a function that returns replacements,
+// which is variable names mapped to their values. The
+// function will be evaluated only at replace-time to ensure
+// the most current values are mapped.
+type ReplacementsFunc func() map[string]string
+
+var defaultReplacements = func() map[string]string {
+	m := map[string]string{
+		"system.hostname": func() string {
+			// OK if there is an error; just return empty string
+			name, _ := os.Hostname()
+			return name
+		}(),
+		"system.slash": string(filepath.Separator),
+		"system.os":    runtime.GOOS,
+		"system.arch":  runtime.GOARCH,
+	}
+
+	// add environment variables
+	for _, keyval := range os.Environ() {
+		parts := strings.SplitN(keyval, "=", 2)
+		if len(parts) != 2 {
+			continue
+		}
+		m["env."+strings.ToUpper(parts[0])] = parts[1]
+	}
+
+	return m
+}
+
+// ReplacerCtxKey is the context key for a replacer.
+const ReplacerCtxKey CtxKey = "replacer"
+
+const phOpen, phClose = "{", "}"