httpcaddyfile: Group try_files routes together (#2891)

This ensures that only the first matching route is used.

caddyconfig/httpcaddyfile/directives.go

@@ -16,6 +16,7 @@ package httpcaddyfile
 
 import (
 	"encoding/json"
+	"fmt"
 	"sort"
 
 	"github.com/caddyserver/caddy/v2"
@@ -97,6 +98,7 @@ type Helper struct {
 	warnings     *[]caddyconfig.Warning
 	matcherDefs  map[string]caddy.ModuleMap
 	parentBlock  caddyfile.ServerBlock
+	groupCounter *int
 }
 
 // Option gets the option keyed by name.
@@ -166,6 +168,32 @@ func (h Helper) NewRoute(matcherSet caddy.ModuleMap,
 	}
 }
 
+func (h Helper) GroupRoutes(vals []ConfigValue) {
+	// ensure there's at least two routes; group of one is pointless
+	var count int
+	for _, v := range vals {
+		if _, ok := v.Value.(caddyhttp.Route); ok {
+			count++
+			if count > 1 {
+				break
+			}
+		}
+	}
+	if count < 2 {
+		return
+	}
+
+	// now that we know the group will have some effect, do it
+	groupNum := *h.groupCounter
+	for i := 0; i < len(vals); i++ {
+		if route, ok := vals[i].Value.(caddyhttp.Route); ok {
+			route.Group = fmt.Sprintf("group%d", groupNum)
+			vals[i].Value = route
+		}
+	}
+	*h.groupCounter++
+}
+
 // NewBindAddresses returns config values relevant to adding
 // listener bind addresses to the config.
 func (h Helper) NewBindAddresses(addrs []string) []ConfigValue {

caddyconfig/httpcaddyfile/httptype.go

@@ -41,6 +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)
 
 	var serverBlocks []serverBlock
 	for _, sblock := range originalServerBlocks {
@@ -145,6 +146,7 @@ func (st ServerType) Setup(originalServerBlocks []caddyfile.ServerBlock,
 				warnings:     &warnings,
 				matcherDefs:  matcherDefs,
 				parentBlock:  sb.block,
+				groupCounter: groupCounter,
 			})
 			if err != nil {
 				return nil, warnings, fmt.Errorf("parsing caddyfile tokens for '%s': %v", dir, err)

modules/caddyhttp/fileserver/caddyfile.go

@@ -163,5 +163,10 @@ func parseTryFiles(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error)
 		result = append(result, makeRoute(try, "")...)
 	}
 
+	// ensure that multiple routes (possible if rewrite targets
+	// have query strings, for example) are grouped together
+	// so only the first matching rewrite is performed (#2891)
+	h.GroupRoutes(result)
+
 	return result, nil
 }