1 files changed, 153 insertions, 0 deletions
diff --git a/caddyconfig/caddyfile/importargs.go b/caddyconfig/caddyfile/importargs.go
new file mode 100644
index 0000000..2e21a36
--- /dev/null
+++ b/caddyconfig/caddyfile/importargs.go
@@ -0,0 +1,153 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package caddyfile
+
+import (
+	"regexp"
+	"strconv"
+	"strings"
+
+	"go.uber.org/zap"
+
+	"github.com/caddyserver/caddy/v2"
+)
+
+// parseVariadic determines if the token is a variadic placeholder,
+// and if so, determines the index range (start/end) of args to use.
+// Returns a boolean signaling whether a variadic placeholder was found,
+// and the start and end indices.
+func parseVariadic(token Token, argCount int) (bool, int, int) {
+	if !strings.HasPrefix(token.Text, "{args[") {
+		return false, 0, 0
+	}
+	if !strings.HasSuffix(token.Text, "]}") {
+		return false, 0, 0
+	}
+
+	argRange := strings.TrimSuffix(strings.TrimPrefix(token.Text, "{args["), "]}")
+	if argRange == "" {
+		caddy.Log().Named("caddyfile").Warn(
+			"Placeholder "+token.Text+" cannot have an empty index",
+			zap.String("file", token.File+":"+strconv.Itoa(token.Line)), zap.Strings("import_chain", token.imports))
+		return false, 0, 0
+	}
+
+	start, end, found := strings.Cut(argRange, ":")
+
+	// If no ":" delimiter is found, this is not a variadic.
+	// The replacer will pick this up.
+	if !found {
+		return false, 0, 0
+	}
+
+	var (
+		startIndex = 0
+		endIndex   = argCount
+		err        error
+	)
+	if start != "" {
+		startIndex, err = strconv.Atoi(start)
+		if err != nil {
+			caddy.Log().Named("caddyfile").Warn(
+				"Variadic placeholder "+token.Text+" has an invalid start index",
+				zap.String("file", token.File+":"+strconv.Itoa(token.Line)), zap.Strings("import_chain", token.imports))
+			return false, 0, 0
+		}
+	}
+	if end != "" {
+		endIndex, err = strconv.Atoi(end)
+		if err != nil {
+			caddy.Log().Named("caddyfile").Warn(
+				"Variadic placeholder "+token.Text+" has an invalid end index",
+				zap.String("file", token.File+":"+strconv.Itoa(token.Line)), zap.Strings("import_chain", token.imports))
+			return false, 0, 0
+		}
+	}
+
+	// bound check
+	if startIndex < 0 || startIndex > endIndex || endIndex > argCount {
+		caddy.Log().Named("caddyfile").Warn(
+			"Variadic placeholder "+token.Text+" indices are out of bounds, only "+strconv.Itoa(argCount)+" argument(s) exist",
+			zap.String("file", token.File+":"+strconv.Itoa(token.Line)), zap.Strings("import_chain", token.imports))
+		return false, 0, 0
+	}
+	return true, startIndex, endIndex
+}
+
+// makeArgsReplacer prepares a Replacer which can replace
+// non-variadic args placeholders in imported tokens.
+func makeArgsReplacer(args []string) *caddy.Replacer {
+	repl := caddy.NewEmptyReplacer()
+	repl.Map(func(key string) (any, bool) {
+		// TODO: Remove the deprecated {args.*} placeholder
+		// support at some point in the future
+		if matches := argsRegexpIndexDeprecated.FindStringSubmatch(key); len(matches) > 0 {
+			// What's matched may be a substring of the key
+			if matches[0] != key {
+				return nil, false
+			}
+
+			value, err := strconv.Atoi(matches[1])
+			if err != nil {
+				caddy.Log().Named("caddyfile").Warn(
+					"Placeholder {args." + matches[1] + "} has an invalid index")
+				return nil, false
+			}
+			if value >= len(args) {
+				caddy.Log().Named("caddyfile").Warn(
+					"Placeholder {args." + matches[1] + "} index is out of bounds, only " + strconv.Itoa(len(args)) + " argument(s) exist")
+				return nil, false
+			}
+			caddy.Log().Named("caddyfile").Warn(
+				"Placeholder {args." + matches[1] + "} deprecated, use {args[" + matches[1] + "]} instead")
+			return args[value], true
+		}
+
+		// Handle args[*] form
+		if matches := argsRegexpIndex.FindStringSubmatch(key); len(matches) > 0 {
+			// What's matched may be a substring of the key
+			if matches[0] != key {
+				return nil, false
+			}
+
+			if strings.Contains(matches[1], ":") {
+				caddy.Log().Named("caddyfile").Warn(
+					"Variadic placeholder {args[" + matches[1] + "]} must be a token on its own")
+				return nil, false
+			}
+			value, err := strconv.Atoi(matches[1])
+			if err != nil {
+				caddy.Log().Named("caddyfile").Warn(
+					"Placeholder {args[" + matches[1] + "]} has an invalid index")
+				return nil, false
+			}
+			if value >= len(args) {
+				caddy.Log().Named("caddyfile").Warn(
+					"Placeholder {args[" + matches[1] + "]} index is out of bounds, only " + strconv.Itoa(len(args)) + " argument(s) exist")
+				return nil, false
+			}
+			return args[value], true
+		}
+
+		// Not an args placeholder, ignore
+		return nil, false
+	})
+	return repl
+}
+
+var (
+	argsRegexpIndexDeprecated = regexp.MustCompile(`args\.(.+)`)
+	argsRegexpIndex           = regexp.MustCompile(`args\[(.+)]`)
+)