caddy/modules/caddyhttp/rewrite/caddyfile.go

// 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 rewrite

import (
	"strconv"
	"strings"

	"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)

func init() {
	httpcaddyfile.RegisterHandlerDirective("rewrite", parseCaddyfileRewrite)
	httpcaddyfile.RegisterHandlerDirective("uri", parseCaddyfileURI)
}

// parseCaddyfileRewrite sets up a basic rewrite handler from Caddyfile tokens. Syntax:
//
//     rewrite [<matcher>] <to>
//
// Only URI components which are given in <to> will be set in the resulting URI.
// See the docs for the rewrite handler for more information.
func parseCaddyfileRewrite(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
	var rewr Rewrite
	for h.Next() {
		if !h.NextArg() {
			return nil, h.ArgErr()
		}
		rewr.URI = h.Val()
		if h.NextArg() {
			return nil, h.ArgErr()
		}
	}
	return rewr, nil
}

// parseCaddyfileURI sets up a handler for manipulating (but not "rewriting") the
// URI from Caddyfile tokens. Syntax:
//
//     uri [<matcher>] strip_prefix|strip_suffix|replace <target> [<replacement> [<limit>]]
//
// If strip_prefix or strip_suffix are used, then <target> will be stripped
// only if it is the beginning or the end, respectively, of the URI path. If
// replace is used, then <target> will be replaced with <replacement> across
// the whole URI, up to <limit> times (or unlimited if unspecified).
func parseCaddyfileURI(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
	var rewr Rewrite
	for h.Next() {
		args := h.RemainingArgs()
		if len(args) < 2 {
			return nil, h.ArgErr()
		}
		switch args[0] {
		case "strip_prefix":
			if len(args) > 2 {
				return nil, h.ArgErr()
			}
			rewr.StripPathPrefix = args[1]
			if !strings.HasPrefix(rewr.StripPathPrefix, "/") {
				rewr.StripPathPrefix = "/" + rewr.StripPathPrefix
			}
		case "strip_suffix":
			if len(args) > 2 {
				return nil, h.ArgErr()
			}
			rewr.StripPathSuffix = args[1]
		case "replace":
			var find, replace, lim string
			switch len(args) {
			case 4:
				lim = args[3]
				fallthrough
			case 3:
				find = args[1]
				replace = args[2]
			default:
				return nil, h.ArgErr()
			}

			var limInt int
			if lim != "" {
				var err error
				limInt, err = strconv.Atoi(lim)
				if err != nil {
					return nil, h.Errf("limit must be an integer; invalid: %v", err)
				}
			}

			rewr.URISubstring = append(rewr.URISubstring, replacer{
				Find:    find,
				Replace: replace,
				Limit:   limInt,
			})
		default:
			return nil, h.Errf("unrecognized URI manipulation '%s'", args[0])
		}
	}
	return rewr, nil
}