copy and fix cors

server/web/cors/cors.go

@@ -0,0 +1,174 @@
+package cors
+
+import (
+	"errors"
+	"strings"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+// 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 and POST)
+	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
+
+	// AllowPrivateNetwork
+	AllowPrivateNetwork bool
+
+	// ExposedHeaders indicates which headers are safe to expose to the API of a CORS
+	// API specification
+	ExposeHeaders []string
+
+	// MaxAge indicates how long (in seconds) 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 origin == "*" {
+			c.AllowAllOrigins = true
+			return nil
+		} else 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"},
+		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)
+	}
+}