diff --git a/example/main.go b/example/main.go index 269ea4f..d95ac93 100644 --- a/example/main.go +++ b/example/main.go @@ -5,11 +5,16 @@ import ( "net/http" "gitserver.in/patialtech/mux" + "gitserver.in/patialtech/mux/middleware" ) func main() { // create a new router r := mux.NewRouter() + r.Use(middleware.CORS(middleware.CORSOption{ + AllowedOrigins: []string{"*"}, + MaxAge: 60, + })) // you can use any middleware that is: "func(http.Handler) http.Handler" // so you can use any of it diff --git a/middleware/cors.go b/middleware/cors.go new file mode 100644 index 0000000..6e194cc --- /dev/null +++ b/middleware/cors.go @@ -0,0 +1,322 @@ +package middleware + +import ( + "net/http" + "strconv" + "strings" +) + +// copied from https://github.com/gorilla/handlers/blob/main/cors.go +// with some editing to fit in +// + +// CORSOption represents a functional option for configuring the CORS middleware. +type CORSOption struct { + // AllowedOrigins list, including "*" will allow all + AllowedOrigins []string + + // AllowedHeaders are a list of headers clients are allowed to use with. + // default: []string{"Accept", "Accept-Language", "Content-Language", "Origin"} + AllowedHeaders []string + + // AllowedMethods are a list of methods clients are allowed to use. + // + // default: []string{"HEAD", "GET", "POST"} + AllowedMethods []string + + ExposedHeaders []string + // MaxAge in seconds, max allowed value is 600 + MaxAge uint + AllowCredentials bool +} + +type cors struct { + h http.Handler + allowedHeaders []string + allowedMethods []string + allowedOrigins []string + allowedOriginValidator OriginValidator + exposedHeaders []string + maxAge uint + ignoreOptions bool + allowCredentials bool + optionStatusCode int +} + +// OriginValidator takes an origin string and returns whether that origin is allowed. +type OriginValidator func(string) bool + +var ( + defaultCorsOptionStatusCode = http.StatusOK + defaultCorsMethods = []string{http.MethodHead, http.MethodGet, http.MethodPost} + defaultCorsHeaders = []string{"Accept", "Accept-Language", "Content-Language", "Origin"} + // (WebKit/Safari v9 sends the Origin header by default in AJAX requests). +) + +const ( + corsOptionMethod string = http.MethodOptions + corsAllowOriginHeader string = "Access-Control-Allow-Origin" + corsExposeHeadersHeader string = "Access-Control-Expose-Headers" + corsMaxAgeHeader string = "Access-Control-Max-Age" + corsAllowMethodsHeader string = "Access-Control-Allow-Methods" + corsAllowHeadersHeader string = "Access-Control-Allow-Headers" + corsAllowCredentialsHeader string = "Access-Control-Allow-Credentials" + corsRequestMethodHeader string = "Access-Control-Request-Method" + corsRequestHeadersHeader string = "Access-Control-Request-Headers" + corsOriginHeader string = "Origin" + corsVaryHeader string = "Vary" + corsOriginMatchAll string = "*" +) + +// CORS provides Cross-Origin Resource Sharing middleware. +// Example: +// +// import ( +// "net/http" +// "gitserver.in/patialtech/mux/middleware" +// "gitserver.in/patialtech/mux" +// ) +// +// func main() { +// r := mux.NewRouter() +// r.Use(middleware.CORS(middleware.CORSOption{ +// AllowedOrigins: []string{"*"}, +// MaxAge: 60, +// })) +// +// r.Get("/", func(w http.ResponseWriter, r *http.Request) { +// w.Write([]byte("hello there")) +// }) +// +// r.Serve(func(srv *http.Server) error { +// srv.Addr = ":3001" +// slog.Info("listening on http://localhost" + srv.Addr) +// return srv.ListenAndServe() +// }) +// } +func CORS(opts CORSOption) func(http.Handler) http.Handler { + return func(h http.Handler) http.Handler { + ch := &cors{ + h: h, + allowedMethods: defaultCorsMethods, + allowedHeaders: defaultCorsHeaders, + allowedOrigins: []string{}, + optionStatusCode: defaultCorsOptionStatusCode, + } + + ch.setAllowedOrigins(opts.AllowedOrigins) + ch.setAllowedHeaders(opts.AllowedHeaders) + ch.setAllowedMethods(opts.AllowedMethods) + ch.setExposedHeaders(opts.ExposedHeaders) + ch.setMaxAge(opts.MaxAge) + ch.maxAge = opts.MaxAge + ch.allowCredentials = opts.AllowCredentials + + return ch + } +} + +func (ch *cors) ServeHTTP(w http.ResponseWriter, r *http.Request) { + origin := r.Header.Get(corsOriginHeader) + if !ch.isOriginAllowed(origin) { + if r.Method != corsOptionMethod || ch.ignoreOptions { + ch.h.ServeHTTP(w, r) + } + + return + } + + if r.Method == corsOptionMethod { + if ch.ignoreOptions { + ch.h.ServeHTTP(w, r) + return + } + + if _, ok := r.Header[corsRequestMethodHeader]; !ok { + w.WriteHeader(http.StatusBadRequest) + return + } + + method := r.Header.Get(corsRequestMethodHeader) + if !ch.isMatch(method, ch.allowedMethods) { + w.WriteHeader(http.StatusMethodNotAllowed) + return + } + + requestHeaders := strings.Split(r.Header.Get(corsRequestHeadersHeader), ",") + var allowedHeaders []string + for _, v := range requestHeaders { + canonicalHeader := http.CanonicalHeaderKey(strings.TrimSpace(v)) + if canonicalHeader == "" || ch.isMatch(canonicalHeader, defaultCorsHeaders) { + continue + } + + if !ch.isMatch(canonicalHeader, ch.allowedHeaders) { + w.WriteHeader(http.StatusForbidden) + return + } + + allowedHeaders = append(allowedHeaders, canonicalHeader) + } + + if len(allowedHeaders) > 0 { + w.Header().Set(corsAllowHeadersHeader, strings.Join(allowedHeaders, ",")) + } + + if ch.maxAge > 0 { + w.Header().Set(corsMaxAgeHeader, strconv.Itoa(int(ch.maxAge))) + } + + if !ch.isMatch(method, defaultCorsMethods) { + w.Header().Set(corsAllowMethodsHeader, method) + } + } else if len(ch.exposedHeaders) > 0 { + w.Header().Set(corsExposeHeadersHeader, strings.Join(ch.exposedHeaders, ",")) + } + + if ch.allowCredentials { + w.Header().Set(corsAllowCredentialsHeader, "true") + } + + if len(ch.allowedOrigins) > 1 { + w.Header().Set(corsVaryHeader, corsOriginHeader) + } + + returnOrigin := origin + if ch.allowedOriginValidator == nil && len(ch.allowedOrigins) == 0 { + returnOrigin = "*" + } else { + for _, o := range ch.allowedOrigins { + // A configuration of * is different from explicitly setting an allowed + // origin. Returning arbitrary origin headers in an access control allow + // origin header is unsafe and is not required by any use case. + if o == corsOriginMatchAll { + returnOrigin = "*" + break + } + } + } + w.Header().Set(corsAllowOriginHeader, returnOrigin) + + if r.Method == corsOptionMethod { + w.WriteHeader(ch.optionStatusCode) + return + } + ch.h.ServeHTTP(w, r) +} + +// AllowedOrigins sets the allowed origins for CORS requests, as used in the +// 'Allow-Access-Control-Origin' HTTP header. +// Note: Passing in a []string{"*"} will allow any domain. +func (ch *cors) setAllowedOrigins(origins []string) { + // look for "*" + for _, v := range origins { + if v == corsOriginMatchAll { + ch.allowedOrigins = []string{corsOriginMatchAll} + return + } + } + + ch.allowedOrigins = origins +} + +// setAllowedHeaders adds the provided headers to the list of allowed headers in a +// CORS request. +// This is an appended operation, so the headers Accept, Accept-Language, +// and Content-Language are always allowed. +// Content-Type must be explicitly declared if accepting Content-Types other than +// application/x-www-form-urlencoded, multipart/form-data, or text/plain. +func (ch *cors) setAllowedHeaders(headers []string) { + for _, v := range headers { + normalizedHeader := http.CanonicalHeaderKey(strings.TrimSpace(v)) + if normalizedHeader == "" { + continue + } + + if !ch.isMatch(normalizedHeader, ch.allowedHeaders) { + ch.allowedHeaders = append(ch.allowedHeaders, normalizedHeader) + } + } +} + +// AllowedMethods can be used to explicitly allow methods in the +// Access-Control-Allow-Methods header. +// This is a replacement operation, so you must also +// pass GET, HEAD, and POST if you wish to support those methods. +func (ch *cors) setAllowedMethods(methods []string) { + if len(methods) == 0 { + return + } + + ch.allowedMethods = []string{} + for _, v := range methods { + normalizedMethod := strings.ToUpper(strings.TrimSpace(v)) + if normalizedMethod == "" { + continue + } + + if !ch.isMatch(normalizedMethod, ch.allowedMethods) { + ch.allowedMethods = append(ch.allowedMethods, normalizedMethod) + } + } +} + +// ExposedHeaders can be used to specify headers that are available +// and will not be stripped out by the user-agent. +func (ch *cors) setExposedHeaders(headers []string) { + ch.exposedHeaders = []string{} + for _, v := range headers { + normalizedHeader := http.CanonicalHeaderKey(strings.TrimSpace(v)) + if normalizedHeader == "" { + continue + } + + if !ch.isMatch(normalizedHeader, ch.exposedHeaders) { + ch.exposedHeaders = append(ch.exposedHeaders, normalizedHeader) + } + } +} + +// MaxAge determines the maximum age (in seconds) between preflight requests. A +// maximum of 10 minutes is allowed. An age above this value will default to 10 +// minutes. +func (ch *cors) setMaxAge(age uint) { + // Maximum of 10 minutes. + if age > 600 { + age = 600 + } + + ch.maxAge = age +} + +func (ch *cors) isOriginAllowed(origin string) bool { + if origin == "" { + return false + } + + if ch.allowedOriginValidator != nil { + return ch.allowedOriginValidator(origin) + } + + if len(ch.allowedOrigins) == 0 { + return true + } + + for _, allowedOrigin := range ch.allowedOrigins { + if allowedOrigin == origin || allowedOrigin == corsOriginMatchAll { + return true + } + } + + return false +} + +func (ch *cors) isMatch(needle string, haystack []string) bool { + for _, v := range haystack { + if v == needle { + return true + } + } + + return false +} diff --git a/middleware/helmet.go b/middleware/helmet.go new file mode 100644 index 0000000..87beeb1 --- /dev/null +++ b/middleware/helmet.go @@ -0,0 +1,351 @@ +package middleware + +import ( + "fmt" + "net/http" + "strings" +) + +// inspired from Helmet.js +// https://github.com/helmetjs/helmet/tree/main + +type ( + HelmetOption struct { + ContentSecurityPolicy CSP + + StrictTransportSecurity *TransportSecurity + + // "require-corp" will be the default policy + CrossOriginEmbedderPolicy Embedder + + // "same-origin" will be the default policy + CrossOriginOpenerPolicy Opener + + // "same-origin" will be the default policy + CrossOriginResourcePolicy Resource + + // "no-referrer" will be the default policy + ReferrerPolicy []Referrer + + OriginAgentCluster bool + + // set true to remove header "X-Content-Type-Options" + DisableSniffMimeType bool + + // set true for header "X-DNS-Prefetch-Control: off" + // + // default is "X-DNS-Prefetch-Control: on" + DisableDNSPrefetch bool + + // set true to remove header "X-Download-Options: noopen" + DisableXDownload bool + + // X-Frame-Options + XFrameOption XFrame + + // X-Permitted-Cross-Domain-Policies + // + // default value will be "none" + CrossDomainPolicies CDP + + // X-XSS-Protection + // + // default is off + XssProtection bool + } + + // CSP is Content-Security-Policy settings + // + // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/Sources + CSP struct { + // default-src, default value will be 'self' + DefaultSrc []string + // script-src, default value will be 'self' + ScriptSrc []string + // script-src-attr, default value will be 'none' + ScriptSrcAttr []string + // style-src, default value will be 'self' https: 'unsafe-inline' + StyleSrc []string + // img-src, default value will be 'self' data: + ImgSrc []string + // object-src, default value will be 'none' + ObjectSrc []string + // base-uri, default value will be 'self' + BaseUri []string + // font-src, default value will be 'self' https: data: + FontSrc []string + // form-action, default value will be 'self' + FormAction []string + // frame-ancestors, default value will be 'self' + FrameAncestors []string + + UpgradeInsecureRequests bool + } + + TransportSecurity struct { + // Age in seconts + MaxAge uint + IncludeSubDomains bool + Preload bool + } + + Embedder string + Opener string + Resource string + Referrer string + // CDP Cross-Domain-Policy + CDP string + XFrame string +) + +const ( + YearDuration = 365 * 24 * 60 * 60 + + // EmbedderDefault default value will be "require-corp" + EmbedderDefault Embedder = "" + EmbedderRequireCorp Embedder = "require-corp" + EmbedderCredentialLess Embedder = "credentialless" + EmbedderUnsafeNone Embedder = "unsafe-none" + + // OpenerDefault default value will be "same-origin" + OpenerDefault Opener = "" + OpenerSameOrigin Opener = "same-origin" + OpenerSameOriginAllowPopups Opener = "same-origin-allow-popups" + OpenerUnsafeNone Opener = "unsafe-none" + + // ResourceDefault default value will be "same-origin" + ResourceDefault Resource = "" + ResourceSameOrigin Resource = "same-origin" + ResourceSameSite Resource = "same-site" + ResourceCrossOrigin Resource = "cross-origin" + + NoReferrer Referrer = "no-referrer" + NoReferrerWhenDowngrade Referrer = "no-referrer-when-downgrade" + SameOrigin Referrer = "same-origin" + Origin Referrer = "origin" + StrictOrigin Referrer = "strict-origin" + OriginWhenCrossOrigin Referrer = "origin-when-cross-origin" + StrictOriginWhenCrossOrigin Referrer = "strict-origin-when-cross-origin" + UnsafeUrl Referrer = "unsafe-url" + + // CDPDefault default value is "none" + CDPDefault CDP = "" + CDPNone CDP = "none" + CDPMasterOnly CDP = "master-only" + CDPByContentType CDP = "by-content-type" + CDPAll CDP = "all" + + // XFrameDefault default value will be "sameorigin" + XFrameDefault XFrame = "" + XFrameSameOrigin XFrame = "sameorigin" + XFrameDeny XFrame = "deny" +) + +// Helmet headers to secure server response +func Helmet(opt HelmetOption) func(http.Handler) http.Handler { + return func(h http.Handler) http.Handler { + return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + w.Header().Add("Content-Security-Policy", opt.ContentSecurityPolicy.value()) + + // Cross-Origin-Embedder-Policy, if nil set default + if opt.CrossOriginEmbedderPolicy == EmbedderDefault { + w.Header().Add("Cross-Origin-Embedder-Policy", string(EmbedderRequireCorp)) + } else { + w.Header().Add("Cross-Origin-Embedder-Policy", string(opt.CrossOriginEmbedderPolicy)) + } + + // Cross-Origin-Opener-Policy, if nil set default + if opt.CrossOriginOpenerPolicy == OpenerDefault { + w.Header().Add("Cross-Origin-Opener-Policy", string(OpenerSameOrigin)) + } else { + w.Header().Add("Cross-Origin-Opener-Policy", string(opt.CrossOriginOpenerPolicy)) + } + + // Cross-Origin-Resource-Policy, if nil set default + if opt.CrossOriginResourcePolicy == ResourceDefault { + w.Header().Add("Cross-Origin-Resource-Policy", string(ResourceSameOrigin)) + } else { + w.Header().Add("Cross-Origin-Resource-Policy", string(opt.CrossOriginResourcePolicy)) + } + + // Referrer-Policy + rpCount := len(opt.ReferrerPolicy) + if rpCount > 0 { + refP := make([]string, rpCount) + for i, r := range opt.ReferrerPolicy { + refP[i] = string(r) + } + w.Header().Add("Referrer-Policy", string(NoReferrer)) + } else { + // default no referer + w.Header().Add("Referrer-Policy", string(NoReferrer)) + } + + // Origin-Agent-Cluster + if opt.OriginAgentCluster { + w.Header().Add("Origin-Agent-Cluster", "?1") + } + + // Strict-Transport-Security + if opt.StrictTransportSecurity != nil { + var sb strings.Builder + + if opt.StrictTransportSecurity.MaxAge == 0 { + opt.StrictTransportSecurity.MaxAge = YearDuration + } + + sb.WriteString(fmt.Sprintf("max-age=%d", opt.StrictTransportSecurity.MaxAge)) + if opt.StrictTransportSecurity.IncludeSubDomains { + sb.WriteString("; includeSubDomains") + } + + if opt.StrictTransportSecurity.Preload { + sb.WriteString("; preload") + } + + w.Header().Add("Strict-Transport-Security", sb.String()) + } + + if !opt.DisableSniffMimeType { + // MIME types advertised in the Content-Current headers should be followed and not be changed + w.Header().Add("X-Content-Type-Options", "nosniff") + } + + if opt.DisableDNSPrefetch { + w.Header().Add("X-DNS-Prefetch-Control", "off") + } else { + w.Header().Add("X-DNS-Prefetch-Control", "on") + } + + if !opt.DisableXDownload { + // Instructs Internet Explorer not to open the file directly but to offer it for download first. + w.Header().Add("X-Download-Options", "noopen") + } + + // indicate whether a browser should be allowed to render a page in iframe | frame | embed | object + if opt.XFrameOption == XFrameDefault { + w.Header().Add("X-Frame-Options", string(XFrameSameOrigin)) + } else { + w.Header().Add("X-Frame-Options", string(opt.XFrameOption)) + } + + if opt.CrossDomainPolicies == CDPDefault { + w.Header().Add("X-Permitted-Cross-Domain-Policies", string(CDPNone)) + } else { + w.Header().Add("X-Permitted-Cross-Domain-Policies", string(opt.CrossDomainPolicies)) + } + + w.Header().Del("X-Powered-By") + + if opt.XssProtection { + // feature of IE, Chrome and Safari that stops pages from loading when they detect reflected + // cross-site scripting (XSS) attacks. + w.Header().Add("X-Xss-Protection", "1; mode=block") + } else { + // Following a decision by Google Chrome developers to disable Auditor, + // developers should be able to disable the auditor for older browsers and set it to 0. + // The X-XSS-PROTECTION header was found to have a multitude of issues, instead of helping the + // developers protect their application. + w.Header().Add("X-Xss-Protection", "0") + } + + h.ServeHTTP(w, r) + }) + } +} + +func (csp *CSP) value() string { + var sb strings.Builder + + // should be the first thing + if csp.UpgradeInsecureRequests { + sb.WriteString("upgrade-insecure-requests;") + } + + sb.WriteString(fmt.Sprintf( + "default-src %s; ", + cspNormalised(csp.DefaultSrc, []string{"self"}), + )) + + sb.WriteString(fmt.Sprintf( + "script-src %s; ", + cspNormalised(csp.ScriptSrc, []string{"self"}), + )) + + sb.WriteString(fmt.Sprintf( + "script-src-attr %s; ", + cspNormalised(csp.ScriptSrcAttr, []string{"none"}), + )) + + sb.WriteString(fmt.Sprintf( + "style-src %s; ", + cspNormalised(csp.StyleSrc, []string{"self", "https:", "unsafe-inline"}), + )) + + sb.WriteString(fmt.Sprintf( + "img-src %s; ", + cspNormalised(csp.ImgSrc, []string{"self", "data:"}), + )) + + sb.WriteString(fmt.Sprintf( + "object-src %s; ", + cspNormalised(csp.ObjectSrc, []string{"none"}), + )) + + sb.WriteString(fmt.Sprintf( + "base-uri %s; ", + cspNormalised(csp.BaseUri, []string{"self"}), + )) + + sb.WriteString(fmt.Sprintf( + "font-src %s; ", + cspNormalised(csp.FontSrc, []string{"self", "https:", "data:"}), + )) + + sb.WriteString(fmt.Sprintf( + "form-action %s; ", + cspNormalised(csp.FormAction, []string{"self"}), + )) + + sb.WriteString(fmt.Sprintf( + "frame-ancestors %s; ", + cspNormalised(csp.FrameAncestors, []string{"self"}), + )) + + return sb.String() +} + +func cspNormalised(v, defaultVal []string) string { + if len(v) == 0 { + v = defaultVal + } + + var sb strings.Builder + for _, val := range v { + val = strings.TrimSpace(val) + if val == "" { + continue + } + + sb.WriteString(" " + cspQuoted(val)) + } + + return strings.TrimSpace(sb.String()) +} + +func cspQuoted(v string) string { + switch v { + case "none", + "self", + "strict-dynamic", + "report-sample", + "inline-speculation-rules", + "unsafe-inline", + "unsafe-eval", + "unsafe-hashes", + "wasm-unsafe-eval": + return fmt.Sprintf("'%s'", v) + default: + return v + } +} diff --git a/middleware/helmet_test.go b/middleware/helmet_test.go new file mode 100644 index 0000000..4362074 --- /dev/null +++ b/middleware/helmet_test.go @@ -0,0 +1,50 @@ +package middleware + +import ( + "net/http" + "net/http/httptest" + "testing" + + "gitserver.in/patialtech/mux" +) + +func TestHelmet(t *testing.T) { + r := mux.NewRouter() + r.Get("/hello", func(writer http.ResponseWriter, request *http.Request) { + _, _ = writer.Write([]byte("hello there")) + }) + + endpoint := httptest.NewRequest(http.MethodGet, "/hello", nil) + + // test endpoint registered/reachable + w := httptest.NewRecorder() + r.ServeHTTP(w, endpoint) + if w.Code != http.StatusOK { + t.Error("not expecting status", w.Code) + return + } + + // no header test + w = httptest.NewRecorder() + r.ServeHTTP(w, endpoint) + csp := w.Header().Get("Content-Security-Policy") + // must not have a csp header, technically no header related to helmet but lets test with one. + if csp != "" { + t.Error("csp header not expected") + } + + // introduce helmet middleware + r.Use(Helmet(HelmetOption{})) + + // header tests.. + w = httptest.NewRecorder() + r.ServeHTTP(w, endpoint) + // csp and other headers are expected + csp = w.Header().Get("Content-Security-Policy") + // fmt.Printf("csp %s", csp) + if csp == "" { + t.Error("csp header missing") + } + + // TODO need more tests +} diff --git a/router.go b/router.go index b40ba1c..c2ca975 100644 --- a/router.go +++ b/router.go @@ -141,7 +141,16 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) { panic("mux: method ServeHTTP called on nil") } - r.mux.ServeHTTP(w, req) + h, pattern := r.mux.Handler(req) + if pattern == "" { + http.Error(w, "Not Found", http.StatusNotFound) + return + } + + // ensure we run all the middlewares + h = stack(r.middlewares, h) + // serve + h.ServeHTTP(w, req) } // stack middlewares(http handler) in order they are passed (FIFO)