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redirect.go
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/
redirect.go
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// Copyright 2015 Zalando SE
//
// 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 builtin
import (
"net/http"
"net/url"
"strings"
"github.com/zalando/skipper/filters"
)
type redirectType int
const (
redDeprecated redirectType = iota
redTo
redToLower
)
// Filter to return
type redirect struct {
typ redirectType
code int
location *url.URL
}
// NewRedirect returns a new filter Spec, whose instances create an HTTP redirect
// response. Marks the request as served. Instances expect two
// parameters: the redirect status code and the redirect location.
// Name: "redirect".
//
// This filter is deprecated, use RedirectTo instead.
func NewRedirect() filters.Spec { return &redirect{typ: redDeprecated} }
// NewRedirectTo returns a new filter Spec, whose instances create an HTTP redirect
// response. It shunts the request flow, meaning that the filter chain on
// the request path is not continued. The request is not forwarded to the
// backend. Instances expect two parameters: the redirect status code and
// the redirect location.
// Name: "redirectTo".
func NewRedirectTo() filters.Spec { return &redirect{typ: redTo} }
// NewRedirectLower returns a new filter Spec, whose instances create an HTTP redirect
// response, which redirects with a lowercase path. It is similar to redTo except that
// it converts the route path to lower while redirecting
// Name: "redirectToLower".
func NewRedirectLower() filters.Spec { return &redirect{typ: redToLower} }
// "redirect" or "redirectToLower" or "redirectTo"
func (spec *redirect) Name() string {
switch spec.typ {
case redDeprecated:
return RedirectName
case redToLower:
return RedirectToLowerName
default:
return RedirectToName
}
}
// Creates an instance of the redirect filter.
func (spec *redirect) CreateFilter(config []interface{}) (filters.Filter, error) {
invalidArgs := func() (filters.Filter, error) {
return nil, filters.ErrInvalidFilterParameters
}
if len(config) != 2 {
return invalidArgs()
}
code, ok := config[0].(float64)
if !ok {
return invalidArgs()
}
location, ok := config[1].(string)
if !ok {
return invalidArgs()
}
u, err := url.Parse(location)
if err != nil {
return invalidArgs()
}
return &redirect{spec.typ, int(code), u}, nil
}
func getRequestHost(r *http.Request) string {
h := r.Header.Get("Host")
if h == "" {
h = r.Host
}
if h == "" {
h = r.URL.Host
}
return h
}
func getLocation(ctx filters.FilterContext, location *url.URL, typ redirectType) string {
r := ctx.Request()
uc := *location
u := &uc
if u.Scheme == "" {
if r.URL.Scheme != "" {
u.Scheme = r.URL.Scheme
} else {
u.Scheme = "https"
}
}
u.User = r.URL.User
if u.Host == "" {
u.Host = getRequestHost(r)
}
if u.Path == "" {
u.Path = r.URL.Path
}
// Check if the redirect has to be case-insensitive
if typ == redToLower {
u.Path = strings.ToLower(u.Path)
}
if u.RawQuery == "" {
u.RawQuery = r.URL.RawQuery
}
return u.String()
}
func redirectWithType(ctx filters.FilterContext, code int, location *url.URL, typ redirectType) {
u := getLocation(ctx, location, typ)
ctx.Serve(&http.Response{
StatusCode: code,
Header: http.Header{"Location": []string{u}}})
}
// Redirect implements the redirect logic as a standalone function.
func Redirect(ctx filters.FilterContext, code int, location *url.URL) {
redirectWithType(ctx, code, location, redTo)
}
func (spec *redirect) Request(ctx filters.FilterContext) {
if spec.typ == redDeprecated {
return
}
redirectWithType(ctx, spec.code, spec.location, spec.typ)
}
// Sets the status code and the location header of the response. Marks the
// request served.
func (spec *redirect) Response(ctx filters.FilterContext) {
if spec.typ != redDeprecated {
return
}
u := getLocation(ctx, spec.location, spec.typ)
w := ctx.ResponseWriter()
w.Header().Set("Location", u)
w.WriteHeader(spec.code)
ctx.MarkServed()
}