195 lines
5.4 KiB
Go
195 lines
5.4 KiB
Go
package headers
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import (
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"context"
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"fmt"
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"net/http"
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"regexp"
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"strconv"
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"strings"
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"github.com/traefik/traefik/v2/pkg/config/dynamic"
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"github.com/traefik/traefik/v2/pkg/log"
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"github.com/vulcand/oxy/v2/forward"
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)
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// Header is a middleware that helps setup a few basic security features.
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// A single headerOptions struct can be provided to configure which features should be enabled,
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// 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
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hasCustomHeaders bool
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hasCorsHeaders bool
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headers *dynamic.Headers
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allowOriginRegexes []*regexp.Regexp
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}
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// NewHeader constructs a new header instance from supplied frontend header struct.
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func NewHeader(next http.Handler, cfg dynamic.Headers) (*Header, error) {
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hasCustomHeaders := cfg.HasCustomHeadersDefined()
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hasCorsHeaders := cfg.HasCorsHeadersDefined()
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ctx := log.With(context.Background(), log.Str(log.MiddlewareType, typeName))
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handleDeprecation(ctx, &cfg)
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regexes := make([]*regexp.Regexp, len(cfg.AccessControlAllowOriginListRegex))
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for i, str := range cfg.AccessControlAllowOriginListRegex {
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reg, err := regexp.Compile(str)
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if err != nil {
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return nil, fmt.Errorf("error occurred during origin parsing: %w", err)
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}
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regexes[i] = reg
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}
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return &Header{
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next: next,
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headers: &cfg,
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hasCustomHeaders: hasCustomHeaders,
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hasCorsHeaders: hasCorsHeaders,
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allowOriginRegexes: regexes,
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}, nil
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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.
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if isPreflight := s.processCorsHeaders(rw, req); isPreflight {
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rw.WriteHeader(http.StatusOK)
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return
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}
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if s.hasCustomHeaders {
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s.modifyCustomRequestHeaders(req)
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}
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// If there is a next, call it.
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if s.next != nil {
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s.next.ServeHTTP(newResponseModifier(rw, req, s.PostRequestModifyResponseHeaders), req)
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}
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}
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// modifyCustomRequestHeaders sets or deletes custom request headers.
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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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switch {
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// Handling https://github.com/golang/go/commit/ecdbffd4ec68b509998792f120868fec319de59b.
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case value == "" && header == forward.XForwardedFor:
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req.Header[header] = nil
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case value == "":
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req.Header.Del(header)
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case strings.EqualFold(header, "Host"):
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req.Host = value
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default:
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req.Header.Set(header, value)
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}
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}
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}
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// PostRequestModifyResponseHeaders set or delete response headers.
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// This method is called AFTER the response is generated from the backend
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// and can merge/override headers from the backend response.
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func (s *Header) PostRequestModifyResponseHeaders(res *http.Response) error {
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// Loop through Custom response headers
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for header, value := range s.headers.CustomResponseHeaders {
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if value == "" {
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res.Header.Del(header)
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} else {
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res.Header.Set(header, value)
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}
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}
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if res != nil && res.Request != nil {
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originHeader := res.Request.Header.Get("Origin")
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allowed, match := s.isOriginAllowed(originHeader)
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if allowed {
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res.Header.Set("Access-Control-Allow-Origin", match)
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}
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}
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if s.headers.AccessControlAllowCredentials {
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res.Header.Set("Access-Control-Allow-Credentials", "true")
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}
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if len(s.headers.AccessControlExposeHeaders) > 0 {
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exposeHeaders := strings.Join(s.headers.AccessControlExposeHeaders, ",")
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res.Header.Set("Access-Control-Expose-Headers", exposeHeaders)
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}
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if !s.headers.AddVaryHeader {
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return nil
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}
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varyHeader := res.Header.Get("Vary")
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if varyHeader == "Origin" {
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return nil
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}
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if varyHeader != "" {
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varyHeader += ","
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}
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varyHeader += "Origin"
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res.Header.Set("Vary", varyHeader)
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return nil
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}
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// processCorsHeaders processes the incoming request,
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// and returns if it is a preflight request.
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// If not a preflight, it handles the preRequestModifyCorsResponseHeaders.
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func (s *Header) processCorsHeaders(rw http.ResponseWriter, req *http.Request) bool {
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if !s.hasCorsHeaders {
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return false
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}
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reqAcMethod := req.Header.Get("Access-Control-Request-Method")
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originHeader := req.Header.Get("Origin")
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if reqAcMethod != "" && originHeader != "" && req.Method == http.MethodOptions {
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// If the request is an OPTIONS request with an Access-Control-Request-Method header,
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// and Origin headers, then it is a CORS preflight request,
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// and we need to build a custom response: https://www.w3.org/TR/cors/#preflight-request
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if s.headers.AccessControlAllowCredentials {
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rw.Header().Set("Access-Control-Allow-Credentials", "true")
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}
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allowHeaders := strings.Join(s.headers.AccessControlAllowHeaders, ",")
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if allowHeaders != "" {
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rw.Header().Set("Access-Control-Allow-Headers", allowHeaders)
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}
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allowMethods := strings.Join(s.headers.AccessControlAllowMethods, ",")
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if allowMethods != "" {
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rw.Header().Set("Access-Control-Allow-Methods", allowMethods)
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}
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allowed, match := s.isOriginAllowed(originHeader)
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if allowed {
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rw.Header().Set("Access-Control-Allow-Origin", match)
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}
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rw.Header().Set("Access-Control-Max-Age", strconv.Itoa(int(s.headers.AccessControlMaxAge)))
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return true
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}
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return false
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}
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func (s *Header) isOriginAllowed(origin string) (bool, string) {
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for _, item := range s.headers.AccessControlAllowOriginList {
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if item == "*" || item == origin {
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return true, item
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}
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}
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for _, regex := range s.allowOriginRegexes {
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if regex.MatchString(origin) {
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return true, origin
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}
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}
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return false, ""
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}
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