diff --git a/middleware/request_cors/config.go b/middleware/request_cors/config.go new file mode 100644 index 0000000..eeea1e9 --- /dev/null +++ b/middleware/request_cors/config.go @@ -0,0 +1,40 @@ +// Package request_cors ... +// +// Description : request_cors ... +// +// Author : go_developer@163.com<白茶清欢> +// +// Date : 2022-07-13 16:27 +package request_cors + +import "net/http" + +type cors struct { + allowAllOrigins bool + allowCredentials bool + allowOriginFunc func(string) bool + allowOrigins []string + normalHeaders http.Header + preflightHeaders http.Header + wildcardOrigins [][]string +} + +var ( + DefaultSchemas = []string{ + "http://", + "https://", + } + ExtensionSchemas = []string{ + "chrome-extension://", + "safari-extension://", + "moz-extension://", + "ms-browser-extension://", + } + FileSchemas = []string{ + "file://", + } + WebSocketSchemas = []string{ + "ws://", + "wss://", + } +) diff --git a/middleware/request_cors/cros.go b/middleware/request_cors/cros.go new file mode 100644 index 0000000..2893fdc --- /dev/null +++ b/middleware/request_cors/cros.go @@ -0,0 +1,277 @@ +// Package request_cors ... +// +// Description : 支持跨域的中间件 +// +// Author : go_developer@163.com<白茶清欢> +// +// Date : 2022-07-13 16:25 +package request_cors + +import ( + "errors" + "net/http" + "strings" + "time" + + "github.com/gin-gonic/gin" +) + +func newCors(config Config) *cors { + if err := config.Validate(); err != nil { + panic(err.Error()) + } + + for _, origin := range config.AllowOrigins { + if origin == "*" { + config.AllowAllOrigins = true + } + } + + return &cors{ + allowOriginFunc: config.AllowOriginFunc, + allowAllOrigins: config.AllowAllOrigins, + allowCredentials: config.AllowCredentials, + allowOrigins: normalize(config.AllowOrigins), + normalHeaders: generateNormalHeaders(config), + preflightHeaders: generatePreflightHeaders(config), + wildcardOrigins: config.parseWildcardRules(), + } +} + +func (cors *cors) applyCors(c *gin.Context) { + origin := c.Request.Header.Get("Origin") + if len(origin) == 0 { + // request is not a CORS request + return + } + host := c.Request.Host + + if origin == "http://"+host || origin == "https://"+host { + // request is not a CORS request but have origin header. + // for example, use fetch api + return + } + + if !cors.validateOrigin(origin) { + c.AbortWithStatus(http.StatusForbidden) + return + } + + if c.Request.Method == "OPTIONS" { + cors.handlePreflight(c) + defer c.AbortWithStatus(http.StatusNoContent) // Using 204 is better than 200 when the request status is OPTIONS + } else { + cors.handleNormal(c) + } + + if !cors.allowAllOrigins { + c.Header("Access-Control-Allow-Origin", origin) + } +} + +func (cors *cors) validateWildcardOrigin(origin string) bool { + for _, w := range cors.wildcardOrigins { + if w[0] == "*" && strings.HasSuffix(origin, w[1]) { + return true + } + if w[1] == "*" && strings.HasPrefix(origin, w[0]) { + return true + } + if strings.HasPrefix(origin, w[0]) && strings.HasSuffix(origin, w[1]) { + return true + } + } + + return false +} + +func (cors *cors) validateOrigin(origin string) bool { + if cors.allowAllOrigins { + return true + } + for _, value := range cors.allowOrigins { + if value == origin { + return true + } + } + if len(cors.wildcardOrigins) > 0 && cors.validateWildcardOrigin(origin) { + return true + } + if cors.allowOriginFunc != nil { + return cors.allowOriginFunc(origin) + } + return false +} + +func (cors *cors) handlePreflight(c *gin.Context) { + header := c.Writer.Header() + for key, value := range cors.preflightHeaders { + header[key] = value + } +} + +func (cors *cors) handleNormal(c *gin.Context) { + header := c.Writer.Header() + for key, value := range cors.normalHeaders { + header[key] = value + } +} + +// Config represents all available options for the middleware. +type Config struct { + AllowAllOrigins bool + + // AllowOrigins is a list of origins a cross-domain request can be executed from. + // If the special "*" value is present in the list, all origins will be allowed. + // Default value is [] + AllowOrigins []string + + // AllowOriginFunc is a custom function to validate the origin. It take the origin + // as argument and returns true if allowed or false otherwise. If this option is + // set, the content of AllowOrigins is ignored. + AllowOriginFunc func(origin string) bool + + // AllowMethods is a list of methods the client is allowed to use with + // cross-domain requests. Default value is simple methods (GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS) + AllowMethods []string + + // AllowHeaders is list of non simple headers the client is allowed to use with + // cross-domain requests. + AllowHeaders []string + + // AllowCredentials indicates whether the request can include user credentials like + // cookies, HTTP authentication or client side SSL certificates. + AllowCredentials bool + + // ExposeHeaders indicates which headers are safe to expose to the API of a CORS + // API specification + ExposeHeaders []string + + // MaxAge indicates how long (with second-precision) the results of a preflight request + // can be cached + MaxAge time.Duration + + // Allows to add origins like http://some-domain/*, https://api.* or http://some.*.subdomain.com + AllowWildcard bool + + // Allows usage of popular browser extensions schemas + AllowBrowserExtensions bool + + // Allows usage of WebSocket protocol + AllowWebSockets bool + + // Allows usage of file:// schema (dangerous!) use it only when you 100% sure it's needed + AllowFiles bool +} + +// AddAllowMethods is allowed to add custom methods +func (c *Config) AddAllowMethods(methods ...string) { + c.AllowMethods = append(c.AllowMethods, methods...) +} + +// AddAllowHeaders is allowed to add custom headers +func (c *Config) AddAllowHeaders(headers ...string) { + c.AllowHeaders = append(c.AllowHeaders, headers...) +} + +// AddExposeHeaders is allowed to add custom expose headers +func (c *Config) AddExposeHeaders(headers ...string) { + c.ExposeHeaders = append(c.ExposeHeaders, headers...) +} + +func (c Config) getAllowedSchemas() []string { + allowedSchemas := DefaultSchemas + if c.AllowBrowserExtensions { + allowedSchemas = append(allowedSchemas, ExtensionSchemas...) + } + if c.AllowWebSockets { + allowedSchemas = append(allowedSchemas, WebSocketSchemas...) + } + if c.AllowFiles { + allowedSchemas = append(allowedSchemas, FileSchemas...) + } + return allowedSchemas +} + +func (c Config) validateAllowedSchemas(origin string) bool { + allowedSchemas := c.getAllowedSchemas() + for _, schema := range allowedSchemas { + if strings.HasPrefix(origin, schema) { + return true + } + } + return false +} + +// Validate is check configuration of user defined. +func (c Config) Validate() error { + if c.AllowAllOrigins && (c.AllowOriginFunc != nil || len(c.AllowOrigins) > 0) { + return errors.New("conflict settings: all origins are allowed. AllowOriginFunc or AllowOrigins is not needed") + } + if !c.AllowAllOrigins && c.AllowOriginFunc == nil && len(c.AllowOrigins) == 0 { + return errors.New("conflict settings: all origins disabled") + } + for _, origin := range c.AllowOrigins { + if !strings.Contains(origin, "*") && !c.validateAllowedSchemas(origin) { + return errors.New("bad origin: origins must contain '*' or include " + strings.Join(c.getAllowedSchemas(), ",")) + } + } + return nil +} + +func (c Config) parseWildcardRules() [][]string { + var wRules [][]string + + if !c.AllowWildcard { + return wRules + } + + for _, o := range c.AllowOrigins { + if !strings.Contains(o, "*") { + continue + } + + if c := strings.Count(o, "*"); c > 1 { + panic(errors.New("only one * is allowed").Error()) + } + + i := strings.Index(o, "*") + if i == 0 { + wRules = append(wRules, []string{"*", o[1:]}) + continue + } + if i == (len(o) - 1) { + wRules = append(wRules, []string{o[:i-1], "*"}) + continue + } + + wRules = append(wRules, []string{o[:i], o[i+1:]}) + } + + return wRules +} + +// DefaultConfig returns a generic default configuration mapped to localhost. +func DefaultConfig() Config { + return Config{ + AllowMethods: []string{"GET", "POST", "PUT", "PATCH", "DELETE", "HEAD", "OPTIONS"}, + AllowHeaders: []string{"Origin", "Content-Length", "Content-Type"}, + AllowCredentials: false, + MaxAge: 12 * time.Hour, + } +} + +// Default returns the location middleware with default configuration. +func Default() gin.HandlerFunc { + config := DefaultConfig() + config.AllowAllOrigins = true + return New(config) +} + +// New returns the location middleware with user-defined custom configuration. +func New(config Config) gin.HandlerFunc { + cors := newCors(config) + return func(c *gin.Context) { + cors.applyCors(c) + } +} diff --git a/middleware/request_cors/util.go b/middleware/request_cors/util.go new file mode 100644 index 0000000..88b2319 --- /dev/null +++ b/middleware/request_cors/util.go @@ -0,0 +1,92 @@ +// Package request_cors ... +// +// Description : request_cors ... +// +// Author : go_developer@163.com<白茶清欢> +// +// Date : 2022-07-13 16:28 +package request_cors + +import ( + "net/http" + "strconv" + "strings" + "time" +) + +type converter func(string) string + +func generateNormalHeaders(c Config) http.Header { + headers := make(http.Header) + if c.AllowCredentials { + headers.Set("Access-Control-Allow-Credentials", "true") + } + if len(c.ExposeHeaders) > 0 { + exposeHeaders := convert(normalize(c.ExposeHeaders), http.CanonicalHeaderKey) + headers.Set("Access-Control-Expose-Headers", strings.Join(exposeHeaders, ",")) + } + if c.AllowAllOrigins { + headers.Set("Access-Control-Allow-Origin", "*") + } else { + headers.Set("Vary", "Origin") + } + return headers +} + +func generatePreflightHeaders(c Config) http.Header { + headers := make(http.Header) + if c.AllowCredentials { + headers.Set("Access-Control-Allow-Credentials", "true") + } + if len(c.AllowMethods) > 0 { + allowMethods := convert(normalize(c.AllowMethods), strings.ToUpper) + value := strings.Join(allowMethods, ",") + headers.Set("Access-Control-Allow-Methods", value) + } + if len(c.AllowHeaders) > 0 { + allowHeaders := convert(normalize(c.AllowHeaders), http.CanonicalHeaderKey) + value := strings.Join(allowHeaders, ",") + headers.Set("Access-Control-Allow-Headers", value) + } + if c.MaxAge > time.Duration(0) { + value := strconv.FormatInt(int64(c.MaxAge/time.Second), 10) + headers.Set("Access-Control-Max-Age", value) + } + if c.AllowAllOrigins { + headers.Set("Access-Control-Allow-Origin", "*") + } else { + // Always set Vary headers + // see https://github.com/rs/cors/issues/10, + // https://github.com/rs/cors/commit/dbdca4d95feaa7511a46e6f1efb3b3aa505bc43f#commitcomment-12352001 + + headers.Add("Vary", "Origin") + headers.Add("Vary", "Access-Control-Request-Method") + headers.Add("Vary", "Access-Control-Request-Headers") + } + return headers +} + +func normalize(values []string) []string { + if values == nil { + return nil + } + distinctMap := make(map[string]bool, len(values)) + normalized := make([]string, 0, len(values)) + for _, value := range values { + value = strings.TrimSpace(value) + value = strings.ToLower(value) + if _, seen := distinctMap[value]; !seen { + normalized = append(normalized, value) + distinctMap[value] = true + } + } + return normalized +} + +func convert(s []string, c converter) []string { + var out []string + for _, i := range s { + out = append(out, c(i)) + } + return out +}