traefik/pkg/middlewares/headers/headers.go

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// Package headers Middleware based on https://github.com/unrolled/secure.
package headers
import (
"context"
"errors"
"net/http"
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"strconv"
"strings"
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"github.com/containous/traefik/v2/pkg/config/dynamic"
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"github.com/containous/traefik/v2/pkg/log"
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"github.com/containous/traefik/v2/pkg/middlewares"
"github.com/containous/traefik/v2/pkg/tracing"
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"github.com/opentracing/opentracing-go/ext"
"github.com/unrolled/secure"
)
const (
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typeName = "Headers"
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)
type headers struct {
name string
handler http.Handler
}
// New creates a Headers middleware.
func New(ctx context.Context, next http.Handler, config dynamic.Headers, name string) (http.Handler, error) {
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// HeaderMiddleware -> SecureMiddleWare -> next
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logger := log.FromContext(middlewares.GetLoggerCtx(ctx, name, typeName))
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logger.Debug("Creating middleware")
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hasSecureHeaders := config.HasSecureHeadersDefined()
hasCustomHeaders := config.HasCustomHeadersDefined()
hasCorsHeaders := config.HasCorsHeadersDefined()
if !hasSecureHeaders && !hasCustomHeaders && !hasCorsHeaders {
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return nil, errors.New("headers configuration not valid")
}
var handler http.Handler
nextHandler := next
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if hasSecureHeaders {
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logger.Debug("Setting up secureHeaders from %v", config)
handler = newSecure(next, config)
nextHandler = handler
}
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if hasCustomHeaders || hasCorsHeaders {
logger.Debug("Setting up customHeaders/Cors from %v", config)
handler = NewHeader(nextHandler, config)
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}
return &headers{
handler: handler,
name: name,
}, nil
}
func (h *headers) GetTracingInformation() (string, ext.SpanKindEnum) {
return h.name, tracing.SpanKindNoneEnum
}
func (h *headers) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
h.handler.ServeHTTP(rw, req)
}
type secureHeader struct {
next http.Handler
secure *secure.Secure
}
// newSecure constructs a new secure instance with supplied options.
func newSecure(next http.Handler, headers dynamic.Headers) *secureHeader {
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opt := secure.Options{
BrowserXssFilter: headers.BrowserXSSFilter,
ContentTypeNosniff: headers.ContentTypeNosniff,
ForceSTSHeader: headers.ForceSTSHeader,
FrameDeny: headers.FrameDeny,
IsDevelopment: headers.IsDevelopment,
SSLRedirect: headers.SSLRedirect,
SSLForceHost: headers.SSLForceHost,
SSLTemporaryRedirect: headers.SSLTemporaryRedirect,
STSIncludeSubdomains: headers.STSIncludeSubdomains,
STSPreload: headers.STSPreload,
ContentSecurityPolicy: headers.ContentSecurityPolicy,
CustomBrowserXssValue: headers.CustomBrowserXSSValue,
CustomFrameOptionsValue: headers.CustomFrameOptionsValue,
PublicKey: headers.PublicKey,
ReferrerPolicy: headers.ReferrerPolicy,
SSLHost: headers.SSLHost,
AllowedHosts: headers.AllowedHosts,
HostsProxyHeaders: headers.HostsProxyHeaders,
SSLProxyHeaders: headers.SSLProxyHeaders,
STSSeconds: headers.STSSeconds,
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FeaturePolicy: headers.FeaturePolicy,
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}
return &secureHeader{
next: next,
secure: secure.New(opt),
}
}
func (s secureHeader) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
s.secure.HandlerFuncWithNextForRequestOnly(rw, req, s.next.ServeHTTP)
}
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// Header is a middleware that helps setup a few basic security features.
// A single headerOptions struct can be provided to configure which features should be enabled,
// and the ability to override a few of the default values.
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type Header struct {
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next http.Handler
hasCustomHeaders bool
hasCorsHeaders bool
headers *dynamic.Headers
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}
// NewHeader constructs a new header instance from supplied frontend header struct.
func NewHeader(next http.Handler, headers dynamic.Headers) *Header {
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hasCustomHeaders := headers.HasCustomHeadersDefined()
hasCorsHeaders := headers.HasCorsHeadersDefined()
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return &Header{
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next: next,
headers: &headers,
hasCustomHeaders: hasCustomHeaders,
hasCorsHeaders: hasCorsHeaders,
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}
}
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func (s *Header) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
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// Handle Cors headers and preflight if configured.
if isPreflight := s.processCorsHeaders(rw, req); isPreflight {
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return
}
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if s.hasCustomHeaders {
s.modifyCustomRequestHeaders(req)
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}
// If there is a next, call it.
if s.next != nil {
s.next.ServeHTTP(rw, req)
}
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}
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// modifyCustomRequestHeaders sets or deletes custom request headers.
func (s *Header) modifyCustomRequestHeaders(req *http.Request) {
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// Loop through Custom request headers
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for header, value := range s.headers.CustomRequestHeaders {
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if value == "" {
req.Header.Del(header)
} else {
req.Header.Set(header, value)
}
}
}
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// preRequestModifyCorsResponseHeaders sets during request processing time,
// all the CORS response headers that we already know that are supposed to be set,
// and which do not depend on a later state of the response.
// One notable example of a header that can only be modified later on is "Vary",
// And this is set in the post-response response modifier method
func (s *Header) preRequestModifyCorsResponseHeaders(rw http.ResponseWriter, req *http.Request) {
originHeader := req.Header.Get("Origin")
allowOrigin := s.getAllowOrigin(originHeader)
if allowOrigin != "" {
rw.Header().Set("Access-Control-Allow-Origin", allowOrigin)
}
if s.headers.AccessControlAllowCredentials {
rw.Header().Set("Access-Control-Allow-Credentials", "true")
}
if len(s.headers.AccessControlExposeHeaders) > 0 {
exposeHeaders := strings.Join(s.headers.AccessControlExposeHeaders, ",")
rw.Header().Set("Access-Control-Expose-Headers", exposeHeaders)
}
}
// PostRequestModifyResponseHeaders set or delete response headers.
// This method is called AFTER the response is generated from the backend
// and can merge/override headers from the backend response.
func (s *Header) PostRequestModifyResponseHeaders(res *http.Response) error {
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// Loop through Custom response headers
for header, value := range s.headers.CustomResponseHeaders {
if value == "" {
res.Header.Del(header)
} else {
res.Header.Set(header, value)
}
}
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if !s.headers.AddVaryHeader {
return nil
}
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varyHeader := res.Header.Get("Vary")
if varyHeader == "Origin" {
return nil
}
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if varyHeader != "" {
varyHeader += ","
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}
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varyHeader += "Origin"
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res.Header.Set("Vary", varyHeader)
return nil
}
// processCorsHeaders processes the incoming request,
// and returns if it is a preflight request.
// If not a preflight, it handles the preRequestModifyCorsResponseHeaders.
func (s *Header) processCorsHeaders(rw http.ResponseWriter, req *http.Request) bool {
if !s.hasCorsHeaders {
return false
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}
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reqAcMethod := req.Header.Get("Access-Control-Request-Method")
reqAcHeaders := req.Header.Get("Access-Control-Request-Headers")
originHeader := req.Header.Get("Origin")
if reqAcMethod != "" && reqAcHeaders != "" && originHeader != "" && req.Method == http.MethodOptions {
// If the request is an OPTIONS request with an Access-Control-Request-Method header,
// and Access-Control-Request-Headers headers, and Origin headers,
// then it is a CORS preflight request,
// and we need to build a custom response: https://www.w3.org/TR/cors/#preflight-request
if s.headers.AccessControlAllowCredentials {
rw.Header().Set("Access-Control-Allow-Credentials", "true")
}
allowHeaders := strings.Join(s.headers.AccessControlAllowHeaders, ",")
if allowHeaders != "" {
rw.Header().Set("Access-Control-Allow-Headers", allowHeaders)
}
allowMethods := strings.Join(s.headers.AccessControlAllowMethods, ",")
if allowMethods != "" {
rw.Header().Set("Access-Control-Allow-Methods", allowMethods)
}
allowOrigin := s.getAllowOrigin(originHeader)
if allowOrigin != "" {
rw.Header().Set("Access-Control-Allow-Origin", allowOrigin)
}
rw.Header().Set("Access-Control-Max-Age", strconv.Itoa(int(s.headers.AccessControlMaxAge)))
return true
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}
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s.preRequestModifyCorsResponseHeaders(rw, req)
return false
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}
func (s *Header) getAllowOrigin(header string) string {
switch s.headers.AccessControlAllowOrigin {
case "origin-list-or-null":
if len(header) == 0 {
return "null"
}
return header
case "*":
return "*"
default:
return ""
}
}