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caddy/modules/caddyhttp/headers/headers.go
Matthew Holt 005a11cf4b
headers: New 'request_header' directive; handle Host header specially
Before this change, only response headers could be manipulated with the
Caddyfile's 'header' directive.

Also handle the request Host header specially, since the Go standard
library treats it separately from the other header fields...
2019-09-11 18:48:37 -06:00

142 lines
4 KiB
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 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)
)