caddy/modules/caddyhttp/subroute.go
Matthew Holt 538ddb8587 reverseproxy: Enable response interception (#1447, #2920)
It's a raw, low-level implementation for now, but it's very flexible.
More sugar-coating can be added after error handling is more developed.
2020-05-27 10:17:45 -06:00

117 lines
3.5 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 caddyhttp
import (
"fmt"
"net/http"
"github.com/caddyserver/caddy/v2"
)
func init() {
caddy.RegisterModule(Subroute{})
}
// Subroute implements a handler that compiles and executes routes.
// This is useful for a batch of routes that all inherit the same
// matchers, or for multiple routes that should be treated as a
// single route.
//
// You can also use subroutes to handle errors from its handlers.
// First the primary routes will be executed, and if they return an
// error, the errors routes will be executed; in that case, an error
// is only returned to the entry point at the server if there is an
// additional error returned from the errors routes.
type Subroute struct {
// The primary list of routes to compile and execute.
Routes RouteList `json:"routes,omitempty"`
// If the primary routes return an error, error handling
// can be promoted to this configuration instead.
Errors *HTTPErrorConfig `json:"errors,omitempty"`
}
// CaddyModule returns the Caddy module information.
func (Subroute) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.subroute",
New: func() caddy.Module { return new(Subroute) },
}
}
// Provision sets up subrouting.
func (sr *Subroute) Provision(ctx caddy.Context) error {
if sr.Routes != nil {
err := sr.Routes.Provision(ctx)
if err != nil {
return fmt.Errorf("setting up subroutes: %v", err)
}
if sr.Errors != nil {
err := sr.Errors.Routes.Provision(ctx)
if err != nil {
return fmt.Errorf("setting up error subroutes: %v", err)
}
}
}
return nil
}
func (sr *Subroute) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error {
subroute := sr.Routes.Compile(next)
err := subroute.ServeHTTP(w, r)
if err != nil && sr.Errors != nil {
r = sr.Errors.WithError(r, err)
errRoute := sr.Errors.Routes.Compile(next)
return errRoute.ServeHTTP(w, r)
}
return err
}
// ResponseHandler pairs a response matcher with a route list.
// It is useful for executing handler routes based on the
// properties of an HTTP response that has not been written
// out to the client yet.
//
// To use this type, provision it at module load time, then
// when ready to use, match the response against its matcher;
// if it matches (or doesn't have a matcher), invoke the routes
// by calling `rh.Routes.Compile(next).ServeHTTP(rw, req)` (or
// similar).
type ResponseHandler struct {
// The response matcher for this handler. If empty/nil,
// it always matches.
Match *ResponseMatcher `json:"match,omitempty"`
// The list of HTTP routes to execute.
Routes RouteList `json:"routes,omitempty"`
}
// Provision sets up the routse in rh.
func (rh *ResponseHandler) Provision(ctx caddy.Context) error {
if rh.Routes != nil {
err := rh.Routes.Provision(ctx)
if err != nil {
return err
}
}
return nil
}
// Interface guards
var (
_ caddy.Provisioner = (*Subroute)(nil)
_ MiddlewareHandler = (*Subroute)(nil)
)