feature: header encoder filter

Signed-off-by: Sandor Szücs <[email protected]>

filters/builtin/builtin.go

@@ -139,6 +139,8 @@ func Filters() []filters.Spec {
 		NewSetPath(),
 		NewModRequestHeader(),
 		NewModResponseHeader(),
+		NewEncodeRequestHeader(),
+		NewEncodeResponseHeader(),
 		NewDropQuery(),
 		NewSetQuery(),
 		NewHealthCheck(),

filters/builtin/header_encode.go

@@ -0,0 +1,112 @@
+package builtin
+
+import (
+	log "github.com/sirupsen/logrus"
+	"github.com/zalando/skipper/filters"
+	xencoding "golang.org/x/text/encoding"
+	"golang.org/x/text/encoding/charmap"
+)
+
+type encodeTyp int
+
+const (
+	requestEncoder encodeTyp = iota + 1
+	responseEncoder
+)
+
+type encodeHeaderSpec struct {
+	typ encodeTyp
+}
+
+type encodeHeader struct {
+	typ     encodeTyp
+	header  string
+	encoder *xencoding.Encoder
+}
+
+func NewEncodeRequestHeader() *encodeHeaderSpec {
+	return &encodeHeaderSpec{
+		typ: requestEncoder,
+	}
+}
+func NewEncodeResponseHeader() *encodeHeaderSpec {
+	return &encodeHeaderSpec{
+		typ: responseEncoder,
+	}
+}
+
+func (spec *encodeHeaderSpec) Name() string {
+	switch spec.typ {
+	case requestEncoder:
+		return filters.EncodeRequestHeaderName
+	case responseEncoder:
+		return filters.EncodeResponseHeaderName
+	}
+	return "unknown"
+}
+
+func (spec *encodeHeaderSpec) CreateFilter(args []interface{}) (filters.Filter, error) {
+	if len(args) != 2 {
+		return nil, filters.ErrInvalidFilterParameters
+	}
+
+	header, ok := args[0].(string)
+	if !ok {
+		return nil, filters.ErrInvalidFilterParameters
+	}
+	to, ok := args[1].(string)
+	if !ok {
+		return nil, filters.ErrInvalidFilterParameters
+	}
+
+	var (
+		encoder *xencoding.Encoder
+	)
+
+	switch to {
+	case "ISO8859_1":
+		encoder = charmap.ISO8859_1.NewEncoder()
+	case "Windows1252":
+		encoder = charmap.Windows1252.NewEncoder()
+	}
+
+	return &encodeHeader{
+		typ:     spec.typ,
+		header:  header,
+		encoder: encoder,
+	}, nil
+}
+
+func (f *encodeHeader) Request(ctx filters.FilterContext) {
+	if f.typ != requestEncoder {
+		return
+	}
+
+	s := ctx.Request().Header.Get(f.header)
+	if s == "" {
+		return
+	}
+
+	sNew, err := f.encoder.String(s)
+	if err != nil {
+		log.Errorf("Failed to encode %q: %v", s, err)
+	}
+	ctx.Request().Header.Set(f.header, sNew)
+}
+
+func (f *encodeHeader) Response(ctx filters.FilterContext) {
+	if f.typ != responseEncoder {
+		return
+	}
+	s := ctx.Response().Header.Get(f.header)
+	if s == "" {
+		return
+	}
+
+	sNew, err := f.encoder.String(s)
+	if err != nil {
+		log.Errorf("Failed to encode %q: %v", s, err)
+	}
+	ctx.Response().Header.Set(f.header, sNew)
+
+}

filters/filters.go

@@ -230,6 +230,8 @@ const (
 	AppendContextResponseHeaderName            = "appendContextResponseHeader"
 	CopyRequestHeaderName                      = "copyRequestHeader"
 	CopyResponseHeaderName                     = "copyResponseHeader"
+	EncodeRequestHeaderName                    = "encodeRequestHeader"
+	EncodeResponseHeaderName                   = "encodeResponseHeader"
 	ModPathName                                = "modPath"
 	SetPathName                                = "setPath"
 	RedirectToName                             = "redirectTo"