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simple.go
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simple.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package auth
import (
"context"
"fmt"
"net/http"
)
// SimpleAuthConfig holds this configuration necessary for a simple auth implementation.
type SimpleAuthConfig struct {
Authentication authenticationConfig `yaml:"authentication"`
Authorization authorizationConfig `yaml:"authorization"`
}
// authenticationConfig holds this configuration necessary for a simple authentication implementation.
type authenticationConfig struct {
// This is an HTTP header that identifies the user performing the operation.
UserIDHeader string `yaml:"userIDHeader" validate:"nonzero"`
// This is an HTTP header that identifies the user originating the operation.
OriginatorIDHeader string `yaml:"originatorIDHeader"`
}
// authorizationConfig holds this configuration necessary for a simple authorization implementation.
// nolint: maligned
type authorizationConfig struct {
// This indicates whether reads should use a read whitelist.
ReadWhitelistEnabled bool `yaml:"readWhitelistEnabled,omitempty"`
// This is a list of users that are allowed to perform read operations.
ReadWhitelistedUserIDs []string `yaml:"readWhitelistedUserIDs,omitempty"`
// This indicates whether writes should use a write whitelist.
WriteWhitelistEnabled bool `yaml:"writeWhitelistEnabled,omitempty"`
// This is a list of users that are allowed to perform write operations.
WriteWhitelistedUserIDs []string `yaml:"writeWhitelistedUserIDs,omitempty"`
}
// NewSimpleAuth creates a new simple auth instance given using the provided config.
func (ac SimpleAuthConfig) NewSimpleAuth() HTTPAuthService {
return simpleAuth{
authentication: simpleAuthentication{
userIDHeader: ac.Authentication.UserIDHeader,
originatorIDHeader: ac.Authentication.OriginatorIDHeader,
},
authorization: simpleAuthorization{
readWhitelistEnabled: ac.Authorization.ReadWhitelistEnabled,
readWhitelistedUserIDs: ac.Authorization.ReadWhitelistedUserIDs,
writeWhitelistEnabled: ac.Authorization.WriteWhitelistEnabled,
writeWhitelistedUserIDs: ac.Authorization.WriteWhitelistedUserIDs,
},
}
}
type simpleAuth struct {
authentication simpleAuthentication
authorization simpleAuthorization
}
type simpleAuthentication struct {
userIDHeader string
originatorIDHeader string
}
func (a simpleAuthentication) authenticate(userID string) error {
if userID == "" {
return fmt.Errorf("must provide header: [%s]", a.userIDHeader)
}
return nil
}
// nolint: maligned
type simpleAuthorization struct {
readWhitelistEnabled bool
readWhitelistedUserIDs []string
writeWhitelistEnabled bool
writeWhitelistedUserIDs []string
}
func (a simpleAuthorization) authorize(authType AuthorizationType, userID string) error {
switch authType {
case NoAuthorization:
return nil
case ReadOnlyAuthorization:
return a.authorizeUserForRead(userID)
case WriteOnlyAuthorization:
return a.authorizeUserForWrite(userID)
case ReadWriteAuthorization:
if err := a.authorizeUserForRead(userID); err != nil {
return err
}
return a.authorizeUserForWrite(userID)
default:
return fmt.Errorf("unsupported authorization type %v passed to handler", authType)
}
}
func authorizeUserForAccess(userID string, whitelistedUserIDs []string, enabled bool) error {
if !enabled {
return nil
}
for _, u := range whitelistedUserIDs {
if u == userID {
return nil
}
}
return fmt.Errorf("supplied userID: [%s] is not authorized", userID)
}
func (a simpleAuthorization) authorizeUserForRead(userID string) error {
return authorizeUserForAccess(userID, a.readWhitelistedUserIDs, a.readWhitelistEnabled)
}
func (a simpleAuthorization) authorizeUserForWrite(userID string) error {
return authorizeUserForAccess(userID, a.writeWhitelistedUserIDs, a.writeWhitelistEnabled)
}
// Authenticate looks for a header defining a user name. If it finds it, runs the actual http handler passed as a parameter.
// Otherwise, it returns an Unauthorized http response.
func (a simpleAuth) NewAuthHandler(authType AuthorizationType, next http.Handler, errHandler errorResponseHandler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
var (
userID = r.Header.Get(a.authentication.userIDHeader)
originatorID = r.Header.Get(a.authentication.originatorIDHeader)
)
if originatorID == "" {
originatorID = userID
}
err := a.authentication.authenticate(originatorID)
if err != nil {
errHandler(w, http.StatusUnauthorized, err.Error())
return
}
err = a.authorization.authorize(authType, userID)
if err != nil {
errHandler(w, http.StatusForbidden, err.Error())
return
}
ctx := a.SetUser(r.Context(), originatorID)
next.ServeHTTP(w, r.WithContext(ctx))
})
}
// SetUser sets the user making the changes to the api.
func (a simpleAuth) SetUser(parent context.Context, userID string) context.Context {
return context.WithValue(parent, UserIDField, userID)
}
// GetUser fetches the ID of an api caller from the global context.
func (a simpleAuth) GetUser(ctx context.Context) (string, error) {
id := ctx.Value(UserIDField)
if id == nil {
return "", fmt.Errorf("couldn't identify user")
}
return id.(string), nil
}