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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 headers
import (
"net/http"
"strings"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)
func init() {
caddy.RegisterModule(Headers{})
}
// Headers is a middleware which can mutate HTTP headers.
type Headers struct {
Request *HeaderOps `json:"request,omitempty"`
Response *RespHeaderOps `json:"response,omitempty"`
}
// CaddyModule returns the Caddy module information.
func (Headers) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
Name: "http.handlers.headers",
New: func() caddy.Module { return new(Headers) },
}
}
// HeaderOps defines some operations to
// perform on HTTP headers.
type HeaderOps struct {
Add http.Header `json:"add,omitempty"`
Set http.Header `json:"set,omitempty"`
Delete []string `json:"delete,omitempty"`
}
// RespHeaderOps is like HeaderOps, but
// optionally deferred until response time.
type RespHeaderOps struct {
*HeaderOps
Require *caddyhttp.ResponseMatcher `json:"require,omitempty"`
Deferred bool `json:"deferred,omitempty"`
}
func (h Headers) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
repl := r.Context().Value(caddy.ReplacerCtxKey).(caddy.Replacer)
apply(h.Request, r.Header, repl)
// request header's Host is handled specially by the
// Go standard library, so if that header was changed,
// change it in the Host field since the Header won't
// be used
if intendedHost := r.Header.Get("Host"); intendedHost != "" {
r.Host = intendedHost
r.Header.Del("Host")
}
if h.Response != nil {
if h.Response.Deferred || h.Response.Require != nil {
w = &responseWriterWrapper{
ResponseWriterWrapper: &caddyhttp.ResponseWriterWrapper{ResponseWriter: w},
replacer: repl,
require: h.Response.Require,
headerOps: h.Response.HeaderOps,
}
} else {
apply(h.Response.HeaderOps, w.Header(), repl)
}
}
return next.ServeHTTP(w, r)
}
func apply(ops *HeaderOps, hdr http.Header, repl caddy.Replacer) {
if ops == nil {
return
}
for fieldName, vals := range ops.Add {
fieldName = repl.ReplaceAll(fieldName, "")
for _, v := range vals {
hdr.Add(fieldName, repl.ReplaceAll(v, ""))
}
}
for fieldName, vals := range ops.Set {
fieldName = repl.ReplaceAll(fieldName, "")
for i := range vals {
vals[i] = repl.ReplaceAll(vals[i], "")
}
hdr.Set(fieldName, strings.Join(vals, ","))
}
for _, fieldName := range ops.Delete {
hdr.Del(repl.ReplaceAll(fieldName, ""))
}
}
// responseWriterWrapper defers response header
// operations until WriteHeader is called.
type responseWriterWrapper struct {
*caddyhttp.ResponseWriterWrapper
replacer caddy.Replacer
require *caddyhttp.ResponseMatcher
headerOps *HeaderOps
wroteHeader bool
}
func (rww *responseWriterWrapper) WriteHeader(status int) {
if rww.wroteHeader {
return
}
rww.wroteHeader = true
if rww.require == nil || rww.require.Match(status, rww.ResponseWriterWrapper.Header()) {
apply(rww.headerOps, rww.ResponseWriterWrapper.Header(), rww.replacer)
}
rww.ResponseWriterWrapper.WriteHeader(status)
}
func (rww *responseWriterWrapper) Write(d []byte) (int, error) {
if !rww.wroteHeader {
rww.WriteHeader(http.StatusOK)
}
return rww.ResponseWriterWrapper.Write(d)
}
// Interface guards
var (
_ caddyhttp.MiddlewareHandler = (*Headers)(nil)
_ caddyhttp.HTTPInterfaces = (*responseWriterWrapper)(nil)
)
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