traefik/pkg/middlewares/stripprefix/strip_prefix.go

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package stripprefix
import (
"context"
"net/http"
"strings"
"github.com/opentracing/opentracing-go/ext"
"github.com/traefik/traefik/v2/pkg/config/dynamic"
"github.com/traefik/traefik/v2/pkg/log"
"github.com/traefik/traefik/v2/pkg/middlewares"
"github.com/traefik/traefik/v2/pkg/tracing"
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)
const (
// ForwardedPrefixHeader is the default header to set prefix.
ForwardedPrefixHeader = "X-Forwarded-Prefix"
typeName = "StripPrefix"
)
// stripPrefix is a middleware used to strip prefix from an URL request.
type stripPrefix struct {
next http.Handler
prefixes []string
forceSlash bool // TODO Must be removed (breaking), the default behavior must be forceSlash=false
name string
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}
// New creates a new strip prefix middleware.
func New(ctx context.Context, next http.Handler, config dynamic.StripPrefix, name string) (http.Handler, error) {
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log.FromContext(middlewares.GetLoggerCtx(ctx, name, typeName)).Debug("Creating middleware")
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return &stripPrefix{
prefixes: config.Prefixes,
forceSlash: config.ForceSlash,
next: next,
name: name,
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}, nil
}
func (s *stripPrefix) GetTracingInformation() (string, ext.SpanKindEnum) {
return s.name, tracing.SpanKindNoneEnum
}
func (s *stripPrefix) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
for _, prefix := range s.prefixes {
if strings.HasPrefix(req.URL.Path, prefix) {
req.URL.Path = s.getPrefixStripped(req.URL.Path, prefix)
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if req.URL.RawPath != "" {
req.URL.RawPath = s.getPrefixStripped(req.URL.RawPath, prefix)
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}
s.serveRequest(rw, req, strings.TrimSpace(prefix))
return
}
}
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s.next.ServeHTTP(rw, req)
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}
func (s *stripPrefix) serveRequest(rw http.ResponseWriter, req *http.Request, prefix string) {
req.Header.Add(ForwardedPrefixHeader, prefix)
req.RequestURI = req.URL.RequestURI()
s.next.ServeHTTP(rw, req)
}
func (s *stripPrefix) getPrefixStripped(urlPath, prefix string) string {
if s.forceSlash {
// Only for compatibility reason with the previous behavior,
// but the previous behavior is wrong.
// This needs to be removed in the next breaking version.
return "/" + strings.TrimPrefix(strings.TrimPrefix(urlPath, prefix), "/")
}
return ensureLeadingSlash(strings.TrimPrefix(urlPath, prefix))
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}
func ensureLeadingSlash(str string) string {
if str == "" {
return str
}
if str[0] == '/' {
return str
}
return "/" + str
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}