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headerfilter.go
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/
headerfilter.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 (
"github.com/zalando/skipper/filters"
"strings"
)
type headerType int
const (
setRequestHeader headerType = iota
appendRequestHeader
dropRequestHeader
setResponseHeader
appendResponseHeader
dropResponseHeader
depRequestHeader
depResponseHeader
)
// common structure for requestHeader, responseHeader specifications and
// filters
type headerFilter struct {
typ headerType
name, key, value string
}
// verifies that the filter config has two string parameters
func headerFilterConfig(typ headerType, config []interface{}) (string, string, error) {
switch typ {
case dropRequestHeader, dropResponseHeader:
if len(config) != 1 {
return "", "", filters.ErrInvalidFilterParameters
}
default:
if len(config) != 2 {
return "", "", filters.ErrInvalidFilterParameters
}
}
key, ok := config[0].(string)
if !ok {
return "", "", filters.ErrInvalidFilterParameters
}
var value string
if len(config) == 2 {
value, ok = config[1].(string)
if !ok {
return "", "", filters.ErrInvalidFilterParameters
}
}
return key, value, nil
}
// Deprecated: use setRequestHeader or appendRequestHeader
func NewRequestHeader() filters.Spec {
return &headerFilter{typ: depRequestHeader}
}
// Deprecated: use setRequestHeader or appendRequestHeader
func NewResponseHeader() filters.Spec {
return &headerFilter{typ: depResponseHeader}
}
// Returns a filter specification that is used to set headers for requests.
// Instances expect two parameters: the header name and the header value.
// Name: "setRequestHeader".
//
// If the header name is 'Host', the filter uses the `SetOutgoingHost()`
// method to set the header in addition to the standard `Request.Header`
// map.
func NewSetRequestHeader() filters.Spec {
return &headerFilter{typ: setRequestHeader}
}
// Returns a filter specification that is used to append headers for requests.
// Instances expect two parameters: the header name and the header value.
// Name: "appendRequestHeader".
//
// If the header name is 'Host', the filter uses the `SetOutgoingHost()`
// method to set the header in addition to the standard `Request.Header`
// map.
func NewAppendRequestHeader() filters.Spec {
return &headerFilter{typ: appendRequestHeader}
}
// Returns a filter specification that is used to delete headers for requests.
// Instances expect one parameter: the header name.
// Name: "dropRequestHeader".
func NewDropRequestHeader() filters.Spec {
return &headerFilter{typ: dropRequestHeader}
}
// Returns a filter specification that is used to set headers for responses.
// Instances expect two parameters: the header name and the header value.
// Name: "setResponseHeader".
func NewSetResponseHeader() filters.Spec {
return &headerFilter{typ: setResponseHeader}
}
// Returns a filter specification that is used to append headers for responses.
// Instances expect two parameters: the header name and the header value.
// Name: "appendResponseHeader".
func NewAppendResponseHeader() filters.Spec {
return &headerFilter{typ: appendResponseHeader}
}
// Returns a filter specification that is used to delete headers for responses.
// Instances expect one parameter: the header name.
// Name: "dropResponseHeader".
func NewDropResponseHeader() filters.Spec {
return &headerFilter{typ: dropResponseHeader}
}
func (spec *headerFilter) Name() string {
switch spec.typ {
case setRequestHeader:
return SetRequestHeaderName
case appendRequestHeader:
return AppendRequestHeaderName
case dropRequestHeader:
return DropRequestHeaderName
case setResponseHeader:
return SetResponseHeaderName
case appendResponseHeader:
return AppendResponseHeaderName
case dropResponseHeader:
return DropResponseHeaderName
case depRequestHeader:
return RequestHeaderName
case depResponseHeader:
return ResponseHeaderName
default:
panic("invalid header type")
}
}
func (spec *headerFilter) CreateFilter(config []interface{}) (filters.Filter, error) {
key, value, err := headerFilterConfig(spec.typ, config)
return &headerFilter{typ: spec.typ, key: key, value: value}, err
}
func (f *headerFilter) Request(ctx filters.FilterContext) {
switch f.typ {
case setRequestHeader:
ctx.Request().Header.Set(f.key, f.value)
if strings.ToLower(f.key) == "host" {
ctx.SetOutgoingHost(f.value)
}
case appendRequestHeader, depRequestHeader:
ctx.Request().Header.Add(f.key, f.value)
if strings.ToLower(f.key) == "host" {
ctx.SetOutgoingHost(f.value)
}
case dropRequestHeader:
ctx.Request().Header.Del(f.key)
}
}
func (f *headerFilter) Response(ctx filters.FilterContext) {
switch f.typ {
case setResponseHeader:
ctx.Response().Header.Set(f.key, f.value)
case appendResponseHeader, depResponseHeader:
ctx.Response().Header.Add(f.key, f.value)
case dropResponseHeader:
ctx.Response().Header.Del(f.key)
}
}