httpcaddyfile: Fix nested blocks; add handle directive; refactor

The fix that was initially put forth in #2971 was good, but only for
up to one layer of nesting. The real problem was that we forgot to
increment nesting when already inside a block if we saw another open
curly brace that opens another block (dispenser.go L157-158).

The new 'handle' directive allows HTTP Caddyfiles to be designed more
like nginx location blocks if the user prefers. Inside a handle block,
directives are still ordered just like they are outside of them, but
handler blocks at a given level of nesting are mutually exclusive.

This work benefitted from some refactoring and cleanup.

caddyconfig/caddyfile/dispenser.go

@@ -152,8 +152,10 @@ func (d *Dispenser) NextBlock(initialNestingLevel int) bool {
 		if !d.Next() {
 			return false // should be EOF error
 		}
-		if d.Val() == "}" {
+		if d.Val() == "}" && !d.nextOnSameLine() {
 			d.nesting--
+		} else if d.Val() == "{" && !d.nextOnSameLine() {
+			d.nesting++
 		}
 		return d.nesting > initialNestingLevel
 	}
@@ -262,9 +264,9 @@ func (d *Dispenser) NewFromNextTokens() *Dispenser {
 		if !openedBlock {
 			// because NextBlock() consumes the initial open
 			// curly brace, we rewind here to append it, since
-			// our case is special in that we want to include
+			// our case is special in that we want the new
-			// all the tokens including surrounding curly braces
+			// dispenser to have all the tokens including
-			// for a new dispenser to have
+			// surrounding curly braces
 			d.Prev()
 			tkns = append(tkns, d.Token())
 			d.Next()
@@ -273,12 +275,12 @@ func (d *Dispenser) NewFromNextTokens() *Dispenser {
 		tkns = append(tkns, d.Token())
 	}
 	if openedBlock {
-		// include closing brace accordingly
+		// include closing brace
 		tkns = append(tkns, d.Token())
-		// since NewFromNextTokens is intended to consume the entire
+
-		// directive, we must call Next() here and consume the closing
+		// do not consume the closing curly brace; the
-		// curly brace
+		// next iteration of the enclosing loop will
-		d.Next()
+		// call Next() and consume it
 	}
 	return NewDispenser(tkns)
 }

caddyconfig/httpcaddyfile/builtins.go

@@ -34,6 +34,7 @@ func init() {
 	RegisterHandlerDirective("redir", parseRedir)
 	RegisterHandlerDirective("respond", parseRespond)
 	RegisterHandlerDirective("route", parseRoute)
+	RegisterHandlerDirective("handle", parseHandle)
 }
 
 func parseBind(h Helper) ([]ConfigValue, error) {
@@ -76,7 +77,7 @@ func parseRoot(h Helper) ([]ConfigValue, error) {
 		route.MatcherSetsRaw = []caddy.ModuleMap{matcherSet}
 	}
 
-	return h.NewVarsRoute(route), nil
+	return []ConfigValue{{Class: "route", Value: route}}, nil
 }
 
 func parseTLS(h Helper) ([]ConfigValue, error) {
@@ -330,3 +331,34 @@ func parseRoute(h Helper) (caddyhttp.MiddlewareHandler, error) {
 
 	return sr, nil
 }
+
+func parseHandle(h Helper) (caddyhttp.MiddlewareHandler, error) {
+	var allResults []ConfigValue
+
+	for h.Next() {
+		for nesting := h.Nesting(); h.NextBlock(nesting); {
+			dir := h.Val()
+
+			dirFunc, ok := registeredDirectives[dir]
+			if !ok {
+				return nil, h.Errf("unrecognized directive: %s", dir)
+			}
+
+			subHelper := h
+			subHelper.Dispenser = h.NewFromNextTokens()
+
+			results, err := dirFunc(subHelper)
+			if err != nil {
+				return nil, h.Errf("parsing caddyfile tokens for '%s': %v", dir, err)
+			}
+			for _, result := range results {
+				result.directive = dir
+				allResults = append(allResults, result)
+			}
+		}
+
+		return buildSubroute(allResults, h.groupCounter)
+	}
+
+	return nil, nil
+}

caddyconfig/httpcaddyfile/directives.go

@@ -16,7 +16,6 @@ package httpcaddyfile
 
 import (
 	"encoding/json"
-	"fmt"
 	"sort"
 
 	"github.com/caddyserver/caddy/v2"
@@ -28,7 +27,10 @@ import (
 // directiveOrder specifies the order
 // to apply directives in HTTP routes.
 var directiveOrder = []string{
+	"root",
+
 	"rewrite",
+
 	"strip_prefix",
 	"strip_suffix",
 	"uri_replace",
@@ -38,7 +40,10 @@ var directiveOrder = []string{
 	"request_header",
 	"encode",
 	"templates",
+
+	"handle",
 	"route",
+
 	"redir",
 	"respond",
 	"reverse_proxy",
@@ -46,6 +51,17 @@ var directiveOrder = []string{
 	"file_server",
 }
 
+// directiveIsOrdered returns true if dir is
+// a known, ordered (sorted) directive.
+func directiveIsOrdered(dir string) bool {
+	for _, d := range directiveOrder {
+		if d == dir {
+			return true
+		}
+	}
+	return false
+}
+
 // RegisterDirective registers a unique directive dir with an
 // associated unmarshaling (setup) function. When directive dir
 // is encountered in a Caddyfile, setupFunc will be called to
@@ -98,7 +114,7 @@ type Helper struct {
 	warnings     *[]caddyconfig.Warning
 	matcherDefs  map[string]caddy.ModuleMap
 	parentBlock  caddyfile.ServerBlock
-	groupCounter *int
+	groupCounter counter
 }
 
 // Option gets the option keyed by name.
@@ -130,8 +146,8 @@ func (h Helper) JSON(val interface{}) json.RawMessage {
 	return caddyconfig.JSON(val, h.warnings)
 }
 
-// MatcherToken assumes the current token is (possibly) a matcher, and
+// MatcherToken assumes the next argument token is (possibly) a matcher,
-// if so, returns the matcher set along with a true value. If the current
+// and if so, returns the matcher set along with a true value. If the next
 // token is not a matcher, nil and false is returned. Note that a true
 // value may be returned with a nil matcher set if it is a catch-all.
 func (h Helper) MatcherToken() (caddy.ModuleMap, bool, error) {
@@ -186,14 +202,13 @@ func (h Helper) GroupRoutes(vals []ConfigValue) {
 	}
 
 	// now that we know the group will have some effect, do it
-	groupNum := *h.groupCounter
+	groupName := h.groupCounter.nextGroup()
 	for i := range vals {
 		if route, ok := vals[i].Value.(caddyhttp.Route); ok {
-			route.Group = fmt.Sprintf("group%d", groupNum)
+			route.Group = groupName
 			vals[i].Value = route
 		}
 	}
-	*h.groupCounter++
 }
 
 // NewBindAddresses returns config values relevant to adding
@@ -202,12 +217,6 @@ func (h Helper) NewBindAddresses(addrs []string) []ConfigValue {
 	return []ConfigValue{{Class: "bind", Value: addrs}}
 }
 
-// NewVarsRoute returns config values relevant to adding a
-// "vars" wrapper route to the config.
-func (h Helper) NewVarsRoute(route caddyhttp.Route) []ConfigValue {
-	return []ConfigValue{{Class: "var", Value: route}}
-}
-
 // ConfigValue represents a value to be added to the final
 // configuration, or a value to be consulted when building
 // the final configuration.
@@ -228,7 +237,7 @@ type ConfigValue struct {
 	directive string
 }
 
-func sortRoutes(handlers []ConfigValue) {
+func sortRoutes(routes []ConfigValue) {
 	dirPositions := make(map[string]int)
 	for i, dir := range directiveOrder {
 		dirPositions[dir] = i
@@ -237,15 +246,21 @@ func sortRoutes(handlers []ConfigValue) {
 	// while we are sorting, we will need to decode a route's path matcher
 	// in order to sub-sort by path length; we can amortize this operation
 	// for efficiency by storing the decoded matchers in a slice
-	decodedMatchers := make([]caddyhttp.MatchPath, len(handlers))
+	decodedMatchers := make([]caddyhttp.MatchPath, len(routes))
 
-	sort.SliceStable(handlers, func(i, j int) bool {
+	sort.SliceStable(routes, func(i, j int) bool {
-		iDir, jDir := handlers[i].directive, handlers[j].directive
+		iDir, jDir := routes[i].directive, routes[j].directive
 		if iDir == jDir {
 			// directives are the same; sub-sort by path matcher length
 			// if there's only one matcher set and one path (common case)
-			iRoute := handlers[i].Value.(caddyhttp.Route)
+			iRoute, ok := routes[i].Value.(caddyhttp.Route)
-			jRoute := handlers[j].Value.(caddyhttp.Route)
+			if !ok {
+				return false
+			}
+			jRoute, ok := routes[j].Value.(caddyhttp.Route)
+			if !ok {
+				return false
+			}
 
 			if len(iRoute.MatcherSetsRaw) == 1 && len(jRoute.MatcherSetsRaw) == 1 {
 				// use already-decoded matcher, or decode if it's the first time seeing it

caddyconfig/httpcaddyfile/httptype.go

@@ -41,7 +41,7 @@ type ServerType struct {
 func (st ServerType) Setup(originalServerBlocks []caddyfile.ServerBlock,
 	options map[string]interface{}) (*caddy.Config, []caddyconfig.Warning, error) {
 	var warnings []caddyconfig.Warning
-	groupCounter := new(int)
+	gc := counter{new(int)}
 
 	var serverBlocks []serverBlock
 	for _, sblock := range originalServerBlocks {
@@ -146,7 +146,7 @@ func (st ServerType) Setup(originalServerBlocks []caddyfile.ServerBlock,
 				warnings:     &warnings,
 				matcherDefs:  matcherDefs,
 				parentBlock:  sb.block,
-				groupCounter: groupCounter,
+				groupCounter: gc,
 			})
 			if err != nil {
 				return nil, warnings, fmt.Errorf("parsing caddyfile tokens for '%s': %v", dir, err)
@@ -169,7 +169,7 @@ func (st ServerType) Setup(originalServerBlocks []caddyfile.ServerBlock,
 
 	// each pairing of listener addresses to list of server
 	// blocks is basically a server definition
-	servers, err := st.serversFromPairings(pairings, options, &warnings)
+	servers, err := st.serversFromPairings(pairings, options, &warnings, gc)
 	if err != nil {
 		return nil, warnings, err
 	}
@@ -306,6 +306,7 @@ func (st *ServerType) serversFromPairings(
 	pairings []sbAddrAssociation,
 	options map[string]interface{},
 	warnings *[]caddyconfig.Warning,
+	groupCounter counter,
 ) (map[string]*caddyhttp.Server, error) {
 	servers := make(map[string]*caddyhttp.Server)
 
@@ -320,32 +321,32 @@ func (st *ServerType) serversFromPairings(
 		// case their matchers overlap; we do this somewhat naively by
 		// descending sort by length of host then path
 		sort.SliceStable(p.serverBlocks, func(i, j int) bool {
-			// TODO: we could pre-process the lengths for efficiency,
+			// TODO: we could pre-process the specificities for efficiency,
 			// but I don't expect many blocks will have SO many keys...
 			var iLongestPath, jLongestPath string
 			var iLongestHost, jLongestHost string
 			for _, key := range p.serverBlocks[i].block.Keys {
 				addr, _ := ParseAddress(key)
-				if length(addr.Host) > length(iLongestHost) {
+				if specificity(addr.Host) > specificity(iLongestHost) {
 					iLongestHost = addr.Host
 				}
-				if len(addr.Path) > len(iLongestPath) {
+				if specificity(addr.Path) > specificity(iLongestPath) {
 					iLongestPath = addr.Path
 				}
 			}
 			for _, key := range p.serverBlocks[j].block.Keys {
 				addr, _ := ParseAddress(key)
-				if length(addr.Host) > length(jLongestHost) {
+				if specificity(addr.Host) > specificity(jLongestHost) {
 					jLongestHost = addr.Host
 				}
-				if len(addr.Path) > len(jLongestPath) {
+				if specificity(addr.Path) > specificity(jLongestPath) {
 					jLongestPath = addr.Path
 				}
 			}
-			if length(iLongestHost) == length(jLongestHost) {
+			if specificity(iLongestHost) == specificity(jLongestHost) {
 				return len(iLongestPath) > len(jLongestPath)
 			}
-			return length(iLongestHost) > length(jLongestHost)
+			return specificity(iLongestHost) > specificity(jLongestHost)
 		})
 
 		// create a subroute for each site in the server block
@@ -355,10 +356,7 @@ func (st *ServerType) serversFromPairings(
 				return nil, fmt.Errorf("server block %v: compiling matcher sets: %v", sblock.block.Keys, err)
 			}
 
-			siteSubroute := new(caddyhttp.Subroute)
-
 			// tls: connection policies and toggle auto HTTPS
-
 			autoHTTPSQualifiedHosts, err := st.autoHTTPSHosts(sblock)
 			if err != nil {
 				return nil, err
@@ -391,38 +389,13 @@ func (st *ServerType) serversFromPairings(
 				// TODO: consolidate equal conn policies
 			}
 
-			// vars: make sure these are linked in first so future
-			// routes can use the variables they define
-			for _, cfgVal := range sblock.pile["var"] {
-				siteSubroute.Routes = append(siteSubroute.Routes, cfgVal.Value.(caddyhttp.Route))
-			}
-
 			// set up each handler directive, making sure to honor directive order
 			dirRoutes := sblock.pile["route"]
-			sortRoutes(dirRoutes)
+			siteSubroute, err := buildSubroute(dirRoutes, groupCounter)
-
+			if err != nil {
-			// add all the routes piled in from directives
+				return nil, err
-			for _, r := range dirRoutes {
-				// as a special case, group rewrite directives so that they are mutually exclusive;
-				// this means that only the first matching rewrite will be evaluated, and that's
-				// probably a good thing, since there should never be a need to do more than one
-				// rewrite (I think?), and cascading rewrites smell bad... imagine these rewrites:
-				//     rewrite /docs/json/* /docs/json/index.html
-				//     rewrite /docs/*      /docs/index.html
-				// (We use this on the Caddy website, or at least we did once.) The first rewrite's
-				// result is also matched by the second rewrite, making the first rewrite pointless.
-				// See issue #2959.
-				if r.directive == "rewrite" {
-					route := r.Value.(caddyhttp.Route)
-					route.Group = "rewriting"
-					r.Value = route
-				}
-
-				siteSubroute.Routes = append(siteSubroute.Routes, r.Value.(caddyhttp.Route))
 			}
 
-			siteSubroute.Routes = consolidateRoutes(siteSubroute.Routes)
-
 			if len(matcherSetsEnc) == 0 && len(p.serverBlocks) == 1 {
 				// no need to wrap the handlers in a subroute if this is
 				// the only server block and there is no matcher for it
@@ -446,6 +419,98 @@ func (st *ServerType) serversFromPairings(
 	return servers, nil
 }
 
+func buildSubroute(routes []ConfigValue, groupCounter counter) (*caddyhttp.Subroute, error) {
+	for _, val := range routes {
+		if !directiveIsOrdered(val.directive) {
+			return nil, fmt.Errorf("directive '%s' is not ordered, so it cannot be used here", val.directive)
+		}
+	}
+
+	sortRoutes(routes)
+
+	subroute := new(caddyhttp.Subroute)
+
+	// get a group name for rewrite directives, if needed
+	var rewriteGroupName string
+	var rewriteCount int
+	for _, r := range routes {
+		if r.directive == "rewrite" {
+			rewriteCount++
+			if rewriteCount > 1 {
+				break
+			}
+		}
+	}
+	if rewriteCount > 1 {
+		rewriteGroupName = groupCounter.nextGroup()
+	}
+
+	// get a group name for handle blocks, if needed
+	var handleGroupName string
+	var handleCount int
+	for _, r := range routes {
+		if r.directive == "handle" {
+			handleCount++
+			if handleCount > 1 {
+				break
+			}
+		}
+	}
+	if handleCount > 1 {
+		handleGroupName = groupCounter.nextGroup()
+	}
+
+	// add all the routes piled in from directives
+	for _, r := range routes {
+		// as a special case, group rewrite directives so that they are mutually exclusive;
+		// this means that only the first matching rewrite will be evaluated, and that's
+		// probably a good thing, since there should never be a need to do more than one
+		// rewrite (I think?), and cascading rewrites smell bad... imagine these rewrites:
+		//     rewrite /docs/json/* /docs/json/index.html
+		//     rewrite /docs/*      /docs/index.html
+		// (We use this on the Caddy website, or at least we did once.) The first rewrite's
+		// result is also matched by the second rewrite, making the first rewrite pointless.
+		// See issue #2959.
+		if r.directive == "rewrite" {
+			route := r.Value.(caddyhttp.Route)
+			route.Group = rewriteGroupName
+			r.Value = route
+		}
+
+		// handle blocks are also mutually exclusive by definition
+		if r.directive == "handle" {
+			route := r.Value.(caddyhttp.Route)
+			route.Group = handleGroupName
+			r.Value = route
+		}
+
+		switch route := r.Value.(type) {
+		case caddyhttp.Subroute:
+			// if a route-class config value is actually a Subroute handler
+			// with nothing but a list of routes, then it is the intention
+			// of the directive to keep these handlers together and in this
+			// same order, but not necessarily in a subroute (if it wanted
+			// to keep them in a subroute, the directive would have returned
+			// a route with a Subroute as its handler); this is useful to
+			// keep multiple handlers/routes together and in the same order
+			// so that the sorting procedure we did above doesn't reorder them
+			if route.Errors != nil {
+				// if error handlers are also set, this is confusing; it's
+				// probably supposed to be wrapped in a Route and encoded
+				// as a regular handler route... programmer error.
+				panic("found subroute with more than just routes; perhaps it should have been wrapped in a route?")
+			}
+			subroute.Routes = append(subroute.Routes, route.Routes...)
+		case caddyhttp.Route:
+			subroute.Routes = append(subroute.Routes, route)
+		}
+	}
+
+	subroute.Routes = consolidateRoutes(subroute.Routes)
+
+	return subroute, nil
+}
+
 func (st ServerType) autoHTTPSHosts(sb serverBlock) ([]string, error) {
 	// get the hosts for this server block...
 	hosts, err := st.hostsFromServerBlockKeys(sb.block)
@@ -521,7 +586,6 @@ func matcherSetFromMatcherToken(
 		}
 		return m, true, nil
 	}
-
 	return nil, false, nil
 }
 
@@ -659,14 +723,40 @@ func tryInt(val interface{}, warnings *[]caddyconfig.Warning) int {
 	return intVal
 }
 
-// length returns len(s) minus any wildcards (*). Basically,
+// specifity returns len(s) minus any wildcards (*) and
-// it's a length count that penalizes the use of wildcards.
+// placeholders ({...}). Basically, it's a length count
-// This is useful for comparing hostnames, but probably not
+// that penalizes the use of wildcards and placeholders.
-// paths so much (for example, '*.example.com' is clearly
+// This is useful for comparing hostnames and paths.
-// less specific than 'a.example.com', but is '/a' more or
+// However, wildcards in paths are not a sure answer to
-// less specific than '/a*'?).
+// the question of specificity. For exmaple,
-func length(s string) int {
+// '*.example.com' is clearly less specific than
-	return len(s) - strings.Count(s, "*")
+// 'a.example.com', but is '/a' more or less specific
+// than '/a*'?
+func specificity(s string) int {
+	l := len(s) - strings.Count(s, "*")
+	for len(s) > 0 {
+		start := strings.Index(s, "{")
+		if start < 0 {
+			return l
+		}
+		end := strings.Index(s[start:], "}") + start + 1
+		if end <= start {
+			return l
+		}
+		l -= end - start
+		s = s[end:]
+	}
+	return l
+}
+
+type counter struct {
+	n *int
+}
+
+func (c counter) nextGroup() string {
+	name := fmt.Sprintf("group%d", *c.n)
+	*c.n++
+	return name
 }
 
 type matcherSetAndTokens struct {

caddyconfig/httpcaddyfile/httptype_test.go

@@ -0,0 +1,33 @@
+package httpcaddyfile
+
+import "testing"
+
+func TestSpecificity(t *testing.T) {
+	for i, tc := range []struct {
+		input  string
+		expect int
+	}{
+		{"", 0},
+		{"*", 0},
+		{"*.*", 1},
+		{"{placeholder}", 0},
+		{"/{placeholder}", 1},
+		{"foo", 3},
+		{"example.com", 11},
+		{"a.example.com", 13},
+		{"*.example.com", 12},
+		{"/foo", 4},
+		{"/foo*", 4},
+		{"{placeholder}.example.com", 12},
+		{"{placeholder.example.com", 24},
+		{"}.", 2},
+		{"}{", 2},
+		{"{}", 0},
+		{"{{{}}", 1},
+	} {
+		actual := specificity(tc.input)
+		if actual != tc.expect {
+			t.Errorf("Test %d (%s): Expected %d but got %d", i, tc.input, tc.expect, actual)
+		}
+	}
+}

modules/caddyhttp/autohttps.go

@@ -338,6 +338,9 @@ func (app *App) automaticHTTPSPhase2() error {
 		if err != nil {
 			return fmt.Errorf("%s: managing certificate for %s: %s", srvName, domains, err)
 		}
+
+		// no longer needed; allow GC to deallocate
+		srv.AutoHTTPS.domainSet = nil
 	}
 
 	return nil

modules/caddyhttp/matchers_test.go

@@ -199,7 +199,7 @@ func TestPathMatcher(t *testing.T) {
 		},
 		{
 			match:  MatchPath{"*.ext"},
-			input:  "/foo.ext",
+			input:  "/foo/bar.ext",
 			expect: true,
 		},
 		{

modules/caddyhttp/reverseproxy/fastcgi/caddyfile.go

@@ -81,7 +81,7 @@ func (t *Transport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 //
 //     php_fastcgi localhost:7777
 //
-// is equivalent to:
+// is equivalent to a route consisting of:
 //
 //     @canonicalPath {
 //         file {
@@ -104,8 +104,8 @@ func (t *Transport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 //         }
 //     }
 //
-// Thus, this directive produces multiple routes, each with a different
+// Thus, this directive produces multiple handlers, each with a different
-// matcher because multiple consecutive routes are necessary to support
+// matcher because multiple consecutive hgandlers are necessary to support
 // the common PHP use case. If this "common" config is not compatible
 // with a user's PHP requirements, they can use a manual approach based
 // on the example above to configure it precisely as they need.
@@ -114,7 +114,7 @@ func (t *Transport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 //
 //     php_fastcgi /subpath localhost:7777
 //
-// then the resulting routes are wrapped in a subroute that uses the
+// then the resulting handlers are wrapped in a subroute that uses the
 // user's matcher as a prerequisite to enter the subroute. In other
 // words, the directive's matcher is necessary, but not sufficient.
 func parsePHPFastCGI(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error) {
@@ -198,12 +198,13 @@ func parsePHPFastCGI(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error
 		HandlersRaw:    []json.RawMessage{caddyconfig.JSONModuleObject(rpHandler, "handler", "reverse_proxy", nil)},
 	}
 
+	subroute := caddyhttp.Subroute{
+		Routes: caddyhttp.RouteList{redirRoute, rewriteRoute, rpRoute},
+	}
+
 	// the user's matcher is a prerequisite for ours, so
 	// wrap ours in a subroute and return that
 	if hasUserMatcher {
-		subroute := caddyhttp.Subroute{
-			Routes: caddyhttp.RouteList{redirRoute, rewriteRoute, rpRoute},
-		}
 		return []httpcaddyfile.ConfigValue{
 			{
 				Class: "route",
@@ -215,20 +216,14 @@ func parsePHPFastCGI(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error
 		}, nil
 	}
 
-	// if the user did not specify a matcher, then
+	// otherwise, return the literal subroute instead of
-	// we can just use our own matchers
+	// individual routes, to ensure they stay together and
+	// are treated as a single unit, without necessarily
+	// creating an actual subroute in the output
 	return []httpcaddyfile.ConfigValue{
 		{
 			Class: "route",
-			Value: redirRoute,
+			Value: subroute,
-		},
-		{
-			Class: "route",
-			Value: rewriteRoute,
-		},
-		{
-			Class: "route",
-			Value: rpRoute,
 		},
 	}, nil
 }

modules/caddyhttp/rewrite/rewrite.go

@@ -50,7 +50,7 @@ type Rewrite struct {
 	// You can also use placeholders. For example, to preserve the existing
 	// query string, you might use: "?{http.request.uri.query}&a=b". Any
 	// key-value pairs you add to the query string will not overwrite
-	// existing values.
+	// existing values (individual pairs are append-only).
 	//
 	// To clear the query string, explicitly set an empty one: "?"
 	URI string `json:"uri,omitempty"`

modules/caddyhttp/routes.go

@@ -252,7 +252,6 @@ func wrapMiddleware(mh MiddlewareHandler) Middleware {
 
 		return HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
 			// TODO: This is where request tracing could be implemented
-			// 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 tracing too
 			return mh.ServeHTTP(w, r, nextCopy)
 		})