mirror of
https://github.com/caddyserver/caddy.git
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125 lines
3.4 KiB
Go
125 lines
3.4 KiB
Go
// Copyright 2015 Light Code Labs, LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package header provides middleware that appends headers to
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// requests based on a set of configuration rules that define
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// which routes receive which headers.
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package header
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import (
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"net/http"
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"strings"
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"github.com/caddyserver/caddy/caddyhttp/httpserver"
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)
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// Headers is middleware that adds headers to the responses
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// for requests matching a certain path.
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type Headers struct {
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Next httpserver.Handler
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Rules []Rule
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}
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// ServeHTTP implements the httpserver.Handler interface and serves requests,
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// setting headers on the response according to the configured rules.
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func (h Headers) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
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replacer := httpserver.NewReplacer(r, nil, "")
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rww := &responseWriterWrapper{
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ResponseWriterWrapper: &httpserver.ResponseWriterWrapper{ResponseWriter: w},
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}
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for _, rule := range h.Rules {
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if httpserver.Path(r.URL.Path).Matches(rule.Path) {
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for name := range rule.Headers {
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// One can either delete a header, add multiple values to a header, or simply
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// set a header.
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if strings.HasPrefix(name, "-") {
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rww.delHeader(strings.TrimLeft(name, "-"))
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} else if strings.HasPrefix(name, "+") {
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for _, value := range rule.Headers[name] {
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rww.Header().Add(strings.TrimLeft(name, "+"), replacer.Replace(value))
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}
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} else {
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for _, value := range rule.Headers[name] {
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rww.Header().Set(name, replacer.Replace(value))
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}
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}
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}
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}
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}
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return h.Next.ServeHTTP(rww, r)
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}
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type (
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// Rule groups a slice of HTTP headers by a URL pattern.
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Rule struct {
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Path string
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Headers http.Header
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}
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)
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// headerOperation represents an operation on the header
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type headerOperation func(http.Header)
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// responseWriterWrapper wraps the real ResponseWriter.
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// It defers header operations until writeHeader
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type responseWriterWrapper struct {
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*httpserver.ResponseWriterWrapper
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ops []headerOperation
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wroteHeader bool
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}
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func (rww *responseWriterWrapper) Header() http.Header {
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return rww.ResponseWriterWrapper.Header()
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}
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func (rww *responseWriterWrapper) Write(d []byte) (int, error) {
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if !rww.wroteHeader {
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rww.WriteHeader(http.StatusOK)
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}
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return rww.ResponseWriterWrapper.Write(d)
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}
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func (rww *responseWriterWrapper) WriteHeader(status int) {
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if rww.wroteHeader {
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return
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}
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rww.wroteHeader = true
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// capture the original headers
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h := rww.Header()
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// perform our revisions
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for _, op := range rww.ops {
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op(h)
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}
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rww.ResponseWriterWrapper.WriteHeader(status)
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}
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// delHeader deletes the existing header according to the key
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// Also it will delete that header added later.
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func (rww *responseWriterWrapper) delHeader(key string) {
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// remove the existing one if any
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rww.Header().Del(key)
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// register a future deletion
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rww.ops = append(rww.ops, func(h http.Header) {
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h.Del(key)
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})
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}
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// Interface guards
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var _ httpserver.HTTPInterfaces = (*responseWriterWrapper)(nil)
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