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// 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 maphandler
import (
"net/http"
"regexp"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)
func init() {
caddy.RegisterModule(Handler{})
}
// Handler is a middleware that maps a source placeholder to a destination
// placeholder.
//
// The mapping process happens early in the request handling lifecycle so that
// the Destination placeholder is calculated and available for substitution.
// The Items array contains pairs of regex expressions and values, the
// Source is matched against the expression, if they match then the destination
// placeholder is set to the value.
//
// The Default is optional, if no Item expression is matched then the value of
// the Default will be used.
//
type Handler struct {
// Source is a placeholder
Source string `json:"source,omitempty"`
// Destination is a new placeholder
Destination string `json:"destination,omitempty"`
// Default is an optional value to use if no other was found
Default string `json:"default,omitempty"`
// Items is an array of regex expressions and values
Items []Item `json:"items,omitempty"`
}
// CaddyModule returns the Caddy module information.
func (Handler) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.map",
New: func() caddy.Module { return new(Handler) },
}
}
// Provision will compile all regular expressions
func (h *Handler) Provision(_ caddy.Context) error {
for i := 0; i < len(h.Items); i++ {
h.Items[i].compiled = regexp.MustCompile(h.Items[i].Expression)
}
return nil
}
func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
// get the source value, if the source value was not found do no
// replacement.
val, ok := repl.GetString(h.Source)
if ok {
found := false
for i := 0; i < len(h.Items); i++ {
if h.Items[i].compiled.MatchString(val) {
found = true
repl.Set(h.Destination, h.Items[i].Value)
break
}
}
if !found && h.Default != "" {
repl.Set(h.Destination, h.Default)
}
}
return next.ServeHTTP(w, r)
}
// Item defines each entry in the map
type Item struct {
// Expression is the regular expression searched for
Expression string `json:"expression,omitempty"`
// Value to use once the expression has been found
Value string `json:"value,omitempty"`
// compiled expression, internal use
compiled *regexp.Regexp
}
// Interface guards
var (
_ caddy.Provisioner = (*Handler)(nil)
_ caddyhttp.MiddlewareHandler = (*Handler)(nil)
)
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