136 lines
3.4 KiB
Go
136 lines
3.4 KiB
Go
package middleware
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import (
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"errors"
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"net/http"
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"strings"
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"github.com/labstack/echo"
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)
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type (
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// KeyAuthConfig defines the config for KeyAuth middleware.
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KeyAuthConfig struct {
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// Skipper defines a function to skip middleware.
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Skipper Skipper
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// KeyLookup is a string in the form of "<source>:<name>" that is used
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// to extract key from the request.
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// Optional. Default value "header:Authorization".
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// Possible values:
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// - "header:<name>"
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// - "query:<name>"
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KeyLookup string `json:"key_lookup"`
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// AuthScheme to be used in the Authorization header.
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// Optional. Default value "Bearer".
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AuthScheme string
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// Validator is a function to validate key.
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// Required.
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Validator KeyAuthValidator
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}
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// KeyAuthValidator defines a function to validate KeyAuth credentials.
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KeyAuthValidator func(string, echo.Context) (error, bool)
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keyExtractor func(echo.Context) (string, error)
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)
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var (
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// DefaultKeyAuthConfig is the default KeyAuth middleware config.
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DefaultKeyAuthConfig = KeyAuthConfig{
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Skipper: DefaultSkipper,
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KeyLookup: "header:" + echo.HeaderAuthorization,
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AuthScheme: "Bearer",
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}
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)
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// KeyAuth returns an KeyAuth middleware.
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//
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// For valid key it calls the next handler.
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// For invalid key, it sends "401 - Unauthorized" response.
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// For missing key, it sends "400 - Bad Request" response.
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func KeyAuth(fn KeyAuthValidator) echo.MiddlewareFunc {
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c := DefaultKeyAuthConfig
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c.Validator = fn
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return KeyAuthWithConfig(c)
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}
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// KeyAuthWithConfig returns an KeyAuth middleware with config.
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// See `KeyAuth()`.
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func KeyAuthWithConfig(config KeyAuthConfig) echo.MiddlewareFunc {
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// Defaults
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if config.Skipper == nil {
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config.Skipper = DefaultKeyAuthConfig.Skipper
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}
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// Defaults
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if config.AuthScheme == "" {
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config.AuthScheme = DefaultKeyAuthConfig.AuthScheme
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}
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if config.KeyLookup == "" {
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config.KeyLookup = DefaultKeyAuthConfig.KeyLookup
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}
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if config.Validator == nil {
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panic("key-auth middleware requires a validator function")
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}
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// Initialize
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parts := strings.Split(config.KeyLookup, ":")
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extractor := keyFromHeader(parts[1], config.AuthScheme)
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switch parts[0] {
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case "query":
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extractor = keyFromQuery(parts[1])
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}
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return func(next echo.HandlerFunc) echo.HandlerFunc {
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return func(c echo.Context) error {
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if config.Skipper(c) {
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return next(c)
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}
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// Extract and verify key
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key, err := extractor(c)
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if err != nil {
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return echo.NewHTTPError(http.StatusBadRequest, err.Error())
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}
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err, valid := config.Validator(key, c)
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if err != nil {
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return err
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} else if valid {
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return next(c)
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}
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return echo.ErrUnauthorized
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}
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}
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}
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// keyFromHeader returns a `keyExtractor` that extracts key from the request header.
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func keyFromHeader(header string, authScheme string) keyExtractor {
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return func(c echo.Context) (string, error) {
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auth := c.Request().Header.Get(header)
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if auth == "" {
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return "", errors.New("Missing key in request header")
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}
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if header == echo.HeaderAuthorization {
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l := len(authScheme)
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if len(auth) > l+1 && auth[:l] == authScheme {
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return auth[l+1:], nil
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}
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return "", errors.New("Invalid key in the request header")
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}
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return auth, nil
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}
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}
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// keyFromQuery returns a `keyExtractor` that extracts key from the query string.
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func keyFromQuery(param string) keyExtractor {
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return func(c echo.Context) (string, error) {
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key := c.QueryParam(param)
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if key == "" {
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return "", errors.New("Missing key in the query string")
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}
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return key, nil
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}
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}
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