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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 reverseproxy
import (
"fmt"
"net/http"
"strconv"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)
func init() {
caddy.RegisterModule(CopyResponseHandler{})
caddy.RegisterModule(CopyResponseHeadersHandler{})
}
// CopyResponseHandler is a special HTTP handler which may
// only be used within reverse_proxy's handle_response routes,
// to copy the proxy response. EXPERIMENTAL, subject to change.
type CopyResponseHandler struct {
// To write the upstream response's body but with a different
// status code, set this field to the desired status code.
StatusCode caddyhttp.WeakString `json:"status_code,omitempty"`
ctx caddy.Context
}
// CaddyModule returns the Caddy module information.
func (CopyResponseHandler) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.copy_response",
New: func() caddy.Module { return new(CopyResponseHandler) },
}
}
// Provision ensures that h is set up properly before use.
func (h *CopyResponseHandler) Provision(ctx caddy.Context) error {
h.ctx = ctx
return nil
}
// ServeHTTP implements the Handler interface.
func (h CopyResponseHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request, _ caddyhttp.Handler) error {
repl := req.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
hrc, ok := req.Context().Value(proxyHandleResponseContextCtxKey).(*handleResponseContext)
// don't allow this to be used outside of handle_response routes
if !ok {
return caddyhttp.Error(http.StatusInternalServerError,
fmt.Errorf("cannot use 'copy_response' outside of reverse_proxy's handle_response routes"))
}
// allow a custom status code to be written; otherwise the
// status code from the upstream response is written
if codeStr := h.StatusCode.String(); codeStr != "" {
intVal, err := strconv.Atoi(repl.ReplaceAll(codeStr, ""))
if err != nil {
return caddyhttp.Error(http.StatusInternalServerError, err)
}
hrc.response.StatusCode = intVal
}
// make sure the reverse_proxy handler doesn't try to call
// finalizeResponse again after we've already done it here.
hrc.isFinalized = true
// write the response
return hrc.handler.finalizeResponse(rw, req, hrc.response, repl, hrc.start, hrc.logger)
}
// CopyResponseHeadersHandler is a special HTTP handler which may
// only be used within reverse_proxy's handle_response routes,
// to copy headers from the proxy response. EXPERIMENTAL;
// subject to change.
type CopyResponseHeadersHandler struct {
// A list of header fields to copy from the response.
// Cannot be defined at the same time as Exclude.
Include []string `json:"include,omitempty"`
// A list of header fields to skip copying from the response.
// Cannot be defined at the same time as Include.
Exclude []string `json:"exclude,omitempty"`
includeMap map[string]struct{}
excludeMap map[string]struct{}
ctx caddy.Context
}
// CaddyModule returns the Caddy module information.
func (CopyResponseHeadersHandler) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.copy_response_headers",
New: func() caddy.Module { return new(CopyResponseHeadersHandler) },
}
}
// Validate ensures the h's configuration is valid.
func (h *CopyResponseHeadersHandler) Validate() error {
if len(h.Exclude) > 0 && len(h.Include) > 0 {
return fmt.Errorf("cannot define both 'exclude' and 'include' lists at the same time")
}
return nil
}
// Provision ensures that h is set up properly before use.
func (h *CopyResponseHeadersHandler) Provision(ctx caddy.Context) error {
h.ctx = ctx
// Optimize the include list by converting it to a map
if len(h.Include) > 0 {
h.includeMap = map[string]struct{}{}
}
for _, field := range h.Include {
h.includeMap[http.CanonicalHeaderKey(field)] = struct{}{}
}
// Optimize the exclude list by converting it to a map
if len(h.Exclude) > 0 {
h.excludeMap = map[string]struct{}{}
}
for _, field := range h.Exclude {
h.excludeMap[http.CanonicalHeaderKey(field)] = struct{}{}
}
return nil
}
// ServeHTTP implements the Handler interface.
func (h CopyResponseHeadersHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request, next caddyhttp.Handler) error {
hrc, ok := req.Context().Value(proxyHandleResponseContextCtxKey).(*handleResponseContext)
// don't allow this to be used outside of handle_response routes
if !ok {
return caddyhttp.Error(http.StatusInternalServerError,
fmt.Errorf("cannot use 'copy_response_headers' outside of reverse_proxy's handle_response routes"))
}
for field, values := range hrc.response.Header {
// Check the include list first, skip
// the header if it's _not_ in this list.
if len(h.includeMap) > 0 {
if _, ok := h.includeMap[field]; !ok {
continue
}
}
// Then, check the exclude list, skip
// the header if it _is_ in this list.
if len(h.excludeMap) > 0 {
if _, ok := h.excludeMap[field]; ok {
continue
}
}
// Copy all the values for the header.
for _, value := range values {
rw.Header().Add(field, value)
}
}
return next.ServeHTTP(rw, req)
}
// Interface guards
var (
_ caddyhttp.MiddlewareHandler = (*CopyResponseHandler)(nil)
_ caddyfile.Unmarshaler = (*CopyResponseHandler)(nil)
_ caddy.Provisioner = (*CopyResponseHandler)(nil)
_ caddyhttp.MiddlewareHandler = (*CopyResponseHeadersHandler)(nil)
_ caddyfile.Unmarshaler = (*CopyResponseHeadersHandler)(nil)
_ caddy.Provisioner = (*CopyResponseHeadersHandler)(nil)
_ caddy.Validator = (*CopyResponseHeadersHandler)(nil)
)
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