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MIT License
Copyright (c) 2021 TwiN
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.

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# g8
![build](https://github.com/TwiN/g8/workflows/build/badge.svg?branch=master)
[![Go Report Card](https://goreportcard.com/badge/github.com/TwiN/g8)](https://goreportcard.com/report/github.com/TwiN/g8)
[![codecov](https://codecov.io/gh/TwiN/g8/branch/master/graph/badge.svg)](https://codecov.io/gh/TwiN/g8)
[![Go version](https://img.shields.io/github/go-mod/go-version/TwiN/g8.svg)](https://github.com/TwiN/g8)
[![Go Reference](https://pkg.go.dev/badge/github.com/TwiN/g8.svg)](https://pkg.go.dev/github.com/TwiN/g8)
[![Follow TwiN](https://img.shields.io/github/followers/TwiN?label=Follow&style=social)](https://github.com/TwiN)
g8, pronounced gate, is a simple Go library for protecting HTTP handlers.
Tired of constantly re-implementing a security layer for each application? Me too, that's why I made g8.
## Installation
```console
go get -u github.com/TwiN/g8
```
## Usage
Because the entire purpose of g8 is to NOT waste time configuring the layer of security, the primary emphasis is to
keep it as simple as possible.
### Simple
Just want a simple layer of security without the need for advanced permissions? This configuration is what you're
looking for.
```go
authorizationService := g8.NewAuthorizationService().WithToken("mytoken")
gate := g8.New().WithAuthorizationService(authorizationService)
router := http.NewServeMux()
router.Handle("/unprotected", yourHandler)
router.Handle("/protected", gate.Protect(yourHandler))
http.ListenAndServe(":8080", router)
```
The endpoint `/protected` is now only accessible if you pass the header `Authorization: Bearer mytoken`.
If you use `http.HandleFunc` instead of `http.Handle`, you may use `gate.ProtectFunc(yourHandler)` instead.
If you're not using the `Authorization` header, you can specify a custom token extractor.
This enables use cases like [Protecting a handler using session cookie](#protecting-a-handler-using-session-cookie)
### Advanced permissions
If you have tokens with more permissions than others, g8's permission system will make managing authorization a breeze.
Rather than registering tokens, think of it as registering clients, the only difference being that clients may be
configured with permissions while tokens cannot.
```go
authorizationService := g8.NewAuthorizationService().WithClient(g8.NewClient("mytoken").WithPermission("admin"))
gate := g8.New().WithAuthorizationService(authorizationService)
router := http.NewServeMux()
router.Handle("/unprotected", yourHandler)
router.Handle("/protected-with-admin", gate.ProtectWithPermissions(yourHandler, []string{"admin"}))
http.ListenAndServe(":8080", router)
```
The endpoint `/protected-with-admin` is now only accessible if you pass the header `Authorization: Bearer mytoken`,
because the client with the token `mytoken` has the permission `admin`. Note that the following handler would also be
accessible with that token:
```go
router.Handle("/protected", gate.Protect(yourHandler))
```
To clarify, both clients and tokens have access to handlers that aren't protected with extra permissions, and
essentially, tokens are registered as clients with no extra permissions in the background.
Creating a token like so:
```go
authorizationService := g8.NewAuthorizationService().WithToken("mytoken")
```
is the equivalent of creating the following client:
```go
authorizationService := g8.NewAuthorizationService().WithClient(g8.NewClient("mytoken"))
```
### With client provider
A client provider's task is to retrieve a Client from an external source (e.g. a database) when provided with a token.
You should use a client provider when you have a lot of tokens and it wouldn't make sense to register all of them using
`AuthorizationService`'s `WithToken`/`WithTokens`/`WithClient`/`WithClients`.
Note that the provider is used as a fallback source. As such, if a token is explicitly registered using one of the 4
aforementioned functions, the client provider will not be used.
```go
clientProvider := g8.NewClientProvider(func(token string) *g8.Client {
// We'll assume that the following function calls your database and returns a struct "User" that
// has the user's token as well as the permissions granted to said user
user := database.GetUserByToken(token)
if user != nil {
return g8.NewClient(user.Token).WithPermissions(user.Permissions)
}
return nil
})
authorizationService := g8.NewAuthorizationService().WithClientProvider(clientProvider)
gate := g8.New().WithAuthorizationService(authorizationService)
```
You can also configure the client provider to cache the output of the function you provide to retrieve clients by token:
```go
clientProvider := g8.NewClientProvider(...).WithCache(ttl, maxSize)
```
Since g8 leverages [TwiN/gocache](https://github.com/TwiN/gocache), you can also use gocache's
constants for configuring the TTL and the maximum size:
- Setting the TTL to `gocache.NoExpiration` (-1) will disable the TTL.
- Setting the maximum size to `gocache.NoMaxSize` (0) will disable the maximum cache size
If you're using a TTL and have a lot of tokens (100k+), you may want to use `clientProvider.StartJanitor()` to allow
the cache to passively delete expired entries. If you have to re-initialize the client provider after the janitor has
been started, make sure to stop the janitor first (`clientProvider.StopJanitor()`). This is because the janitor runs on
a separate goroutine, thus, if you were to re-create a client provider and re-assign it, the old client provider would
still exist in memory with the old cache. I'm only specifying this for completeness, because for the overwhelming
majority of people, the gate will be created on application start and never modified again until the application shuts
down, in which case, you don't even need to worry about stopping the janitor.
To avoid any misunderstandings, using a client provider is not mandatory. If you only have a few tokens and you can load
them on application start, you can just leverage `AuthorizationService`'s `WithToken`/`WithTokens`/`WithClient`/`WithClients`.
## AuthorizationService
As the previous examples may have hinted, there are several ways to create clients. The one thing they have
in common is that they all go through AuthorizationService, which is in charge of both managing clients and determining
whether a request should be blocked or allowed through.
| Function | Description |
|:-------------------|:---------------------------------------------------------------------------------------------------------------------------------|
| WithToken | Creates a single static client with no extra permissions |
| WithTokens | Creates a slice of static clients with no extra permissions |
| WithClient | Creates a single static client |
| WithClients | Creates a slice of static clients |
| WithClientProvider | Creates a client provider which will allow a fallback to a dynamic source (e.g. to a database) when a static client is not found |
Except for `WithClientProvider`, every functions listed above can be called more than once.
As a result, you may safely perform actions like this:
```go
authorizationService := g8.NewAuthorizationService().
WithToken("123").
WithToken("456").
WithClient(g8.NewClient("789").WithPermission("admin"))
gate := g8.New().WithAuthorizationService(authorizationService)
```
Be aware that g8.Client supports a list of permissions as well. You may call `WithPermission` several times, or call
`WithPermissions` with a slice of permissions instead.
### Permissions
Unlike client permissions, handler permissions are requirements.
A client may have as many permissions as you want, but for said client to have access to a handler protected by
permissions, the client must have all permissions defined by said handler in order to have access to it.
In other words, a client with the permissions `create`, `read`, `update` and `delete` would have access to all of these handlers:
```go
gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClient(g8.NewClient("mytoken").WithPermissions([]string{"create", "read", "update", "delete"})))
router := http.NewServeMux()
router.Handle("/", gate.Protect(homeHandler)) // equivalent of gate.ProtectWithPermissions(homeHandler, []string{})
router.Handle("/create", gate.ProtectWithPermissions(createHandler, []string{"create"}))
router.Handle("/read", gate.ProtectWithPermissions(readHandler, []string{"read"}))
router.Handle("/update", gate.ProtectWithPermissions(updateHandler, []string{"update"}))
router.Handle("/delete", gate.ProtectWithPermissions(deleteHandler, []string{"delete"}))
router.Handle("/crud", gate.ProtectWithPermissions(crudHandler, []string{"create", "read", "update", "delete"}))
```
But it would not have access to the following handler, because while `mytoken` has the `read` permission, it does not
have the `backup` permission:
```go
router.Handle("/backup", gate.ProtectWithPermissions(&testHandler{}, []string{"read", "backup"}))
```
## Rate limiting
To add a rate limit of 100 requests per second:
```
gate := g8.New().WithRateLimit(100)
```
## Special use cases
### Protecting a handler using session cookie
If you want to only allow authenticated users to access a handler, you can use a custom token extractor function
combined with a client provider.
First, we'll create a function to extract the session ID from the session cookie. While a session ID does not
theoretically refer to a token, g8 uses the term `token` as a blanket term to refer to any string that can be used to
identify a client.
```go
customTokenExtractorFunc := func(request *http.Request) string {
sessionCookie, err := request.Cookie("session")
if err != nil {
return ""
}
return sessionCookie.Value
}
```
Next, we need to create a client provider that will validate our token, which refers to the session ID in this case.
```go
clientProvider := g8.NewClientProvider(func(token string) *g8.Client {
// We'll assume that the following function calls your database and validates whether the session is valid.
isSessionValid := database.CheckIfSessionIsValid(token)
if !isSessionValid {
return nil // Returning nil will cause the gate to return a 401 Unauthorized.
}
// You could also retrieve the user and their permissions if you wanted instead, but for this example,
// all we care about is confirming whether the session is valid or not.
return g8.NewClient(token)
})
```
Keep in mind that you can get really creative with the client provider above.
For instance, you could refresh the session's expiration time, which will allow the user to stay logged in for
as long as they're active.
You're also not limited to using something stateful like the example above. You could use a JWT and have your client
provider validate said JWT.
Finally, we can create the authorization service and the gate:
```go
authorizationService := g8.NewAuthorizationService().WithClientProvider(clientProvider)
gate := g8.New().WithAuthorizationService(authorizationService).WithCustomTokenExtractor(customTokenExtractorFunc)
```
If you need to access the token (session ID in this case) from the protected handlers, you can retrieve it from the
request context by using the key `g8.TokenContextKey`:
```go
http.Handle("/handle", gate.ProtectFunc(func(w http.ResponseWriter, r *http.Request) {
sessionID, _ := r.Context().Value(g8.TokenContextKey).(string)
// ...
}))
```

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package g8
import (
"sync"
)
// AuthorizationService is the service that manages client/token registry and client fallback as well as the service
// that determines whether a token meets the specific requirements to be authorized by a Gate or not.
type AuthorizationService struct {
clients map[string]*Client
clientProvider *ClientProvider
mutex sync.RWMutex
}
// NewAuthorizationService creates a new AuthorizationService
func NewAuthorizationService() *AuthorizationService {
return &AuthorizationService{
clients: make(map[string]*Client),
}
}
// WithToken is used to specify a single token for which authorization will be granted
//
// The client that will be created from this token will have access to all handlers that are not protected with a
// specific permission.
//
// In other words, if you were to do the following:
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithToken("12345"))
//
// The following handler would be accessible with the token 12345:
// router.Handle("/1st-handler", gate.Protect(yourHandler))
//
// But not this one would not be accessible with the token 12345:
// router.Handle("/2nd-handler", gate.ProtectWithPermissions(yourOtherHandler, []string{"admin"}))
//
// Calling this function multiple times will add multiple clients, though you may want to use WithTokens instead
// if you plan to add multiple clients
//
// If you wish to configure advanced permissions, consider using WithClient instead.
//
func (authorizationService *AuthorizationService) WithToken(token string) *AuthorizationService {
authorizationService.mutex.Lock()
authorizationService.clients[token] = NewClient(token)
authorizationService.mutex.Unlock()
return authorizationService
}
// WithTokens is used to specify a slice of tokens for which authorization will be granted
func (authorizationService *AuthorizationService) WithTokens(tokens []string) *AuthorizationService {
authorizationService.mutex.Lock()
for _, token := range tokens {
authorizationService.clients[token] = NewClient(token)
}
authorizationService.mutex.Unlock()
return authorizationService
}
// WithClient is used to specify a single client for which authorization will be granted
//
// When compared to WithToken, the advantage of using this function is that you may specify the client's
// permissions and thus, be a lot more granular with what endpoint a token has access to.
//
// In other words, if you were to do the following:
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClient(g8.NewClient("12345").WithPermission("mod")))
//
// The following handlers would be accessible with the token 12345:
// router.Handle("/1st-handler", gate.ProtectWithPermissions(yourHandler, []string{"mod"}))
// router.Handle("/2nd-handler", gate.Protect(yourOtherHandler))
//
// But not this one, because the user does not have the permission "admin":
// router.Handle("/3rd-handler", gate.ProtectWithPermissions(yetAnotherHandler, []string{"admin"}))
//
// Calling this function multiple times will add multiple clients, though you may want to use WithClients instead
// if you plan to add multiple clients
func (authorizationService *AuthorizationService) WithClient(client *Client) *AuthorizationService {
authorizationService.mutex.Lock()
authorizationService.clients[client.Token] = client
authorizationService.mutex.Unlock()
return authorizationService
}
// WithClients is used to specify a slice of clients for which authorization will be granted
func (authorizationService *AuthorizationService) WithClients(clients []*Client) *AuthorizationService {
authorizationService.mutex.Lock()
for _, client := range clients {
authorizationService.clients[client.Token] = client
}
authorizationService.mutex.Unlock()
return authorizationService
}
// WithClientProvider allows specifying a custom provider to fetch clients by token.
//
// For example, you can use it to fallback to making a call in your database when a request is made with a token that
// hasn't been specified via WithToken, WithTokens, WithClient or WithClients.
func (authorizationService *AuthorizationService) WithClientProvider(provider *ClientProvider) *AuthorizationService {
authorizationService.clientProvider = provider
return authorizationService
}
// IsAuthorized checks whether a client with a given token exists and has the permissions required.
//
// If permissionsRequired is nil or empty and a client with the given token exists, said client will have access to all
// handlers that are not protected by a given permission.
func (authorizationService *AuthorizationService) IsAuthorized(token string, permissionsRequired []string) bool {
if len(token) == 0 {
return false
}
authorizationService.mutex.RLock()
client, _ := authorizationService.clients[token]
authorizationService.mutex.RUnlock()
// If there's no clients with the given token directly stored in the AuthorizationService, fall back to the
// client provider, if there's one configured.
if client == nil && authorizationService.clientProvider != nil {
client = authorizationService.clientProvider.GetClientByToken(token)
}
if client != nil {
return client.HasPermissions(permissionsRequired)
}
return false
}

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package g8
// Client is a struct containing both a Token and a slice of extra Permissions that said token has.
type Client struct {
// Token is the value used to authenticate with the API.
Token string
// Permissions is a slice of extra permissions that may be used for more granular access control.
//
// If you only wish to use Gate.Protect and Gate.ProtectFunc, you do not have to worry about this,
// since they're only used by Gate.ProtectWithPermissions and Gate.ProtectFuncWithPermissions
Permissions []string
}
// NewClient creates a Client with a given token
func NewClient(token string) *Client {
return &Client{
Token: token,
}
}
// NewClientWithPermissions creates a Client with a slice of permissions
// Equivalent to using NewClient and WithPermissions
func NewClientWithPermissions(token string, permissions []string) *Client {
return NewClient(token).WithPermissions(permissions)
}
// WithPermissions adds a slice of permissions to a client
func (client *Client) WithPermissions(permissions []string) *Client {
client.Permissions = append(client.Permissions, permissions...)
return client
}
// WithPermission adds a permission to a client
func (client *Client) WithPermission(permission string) *Client {
client.Permissions = append(client.Permissions, permission)
return client
}
// HasPermission checks whether a client has a given permission
func (client Client) HasPermission(permissionRequired string) bool {
for _, permission := range client.Permissions {
if permissionRequired == permission {
return true
}
}
return false
}
// HasPermissions checks whether a client has the all permissions passed
func (client Client) HasPermissions(permissionsRequired []string) bool {
for _, permissionRequired := range permissionsRequired {
if !client.HasPermission(permissionRequired) {
return false
}
}
return true
}

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package g8
import (
"errors"
"time"
"github.com/TwiN/gocache/v2"
)
var (
// ErrNoExpiration is the error returned by ClientProvider.StartCacheJanitor if there was an attempt to start the
// janitor despite no expiration being configured.
// To clarify, this is because the cache janitor is only useful when an expiration is set.
ErrNoExpiration = errors.New("no point starting the janitor if the TTL is set to not expire")
// ErrCacheNotInitialized is the error returned by ClientProvider.StartCacheJanitor if there was an attempt to start
// the janitor despite the cache not having been initialized using ClientProvider.WithCache
ErrCacheNotInitialized = errors.New("cannot start janitor because cache is not configured")
)
// ClientProvider has the task of retrieving a Client from an external source (e.g. a database) when provided with a
// token. It should be used when you have a lot of tokens, and it wouldn't make sense to register all of them using
// AuthorizationService's WithToken, WithTokens, WithClient or WithClients.
//
// Note that the provider is used as a fallback source. As such, if a token is explicitly registered using one of the 4
// aforementioned functions, the client provider will not be used by the AuthorizationService when a request is made
// with said token. It will, however, be called upon if a token that is not explicitly registered in
// AuthorizationService is sent alongside a request going through the Gate.
//
// clientProvider := g8.NewClientProvider(func(token string) *g8.Client {
// // We'll assume that the following function calls your database and returns a struct "User" that
// // has the user's token as well as the permissions granted to said user
// user := database.GetUserByToken(token)
// if user != nil {
// return g8.NewClient(user.Token).WithPermissions(user.Permissions)
// }
// return nil
// })
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClientProvider(clientProvider))
//
type ClientProvider struct {
getClientByTokenFunc func(token string) *Client
cache *gocache.Cache
ttl time.Duration
}
// NewClientProvider creates a ClientProvider
// The parameter that must be passed is a function that the provider will use to retrieve a client by a given token
//
// Example:
// clientProvider := g8.NewClientProvider(func(token string) *g8.Client {
// // We'll assume that the following function calls your database and returns a struct "User" that
// // has the user's token as well as the permissions granted to said user
// user := database.GetUserByToken(token)
// if user == nil {
// return nil
// }
// return g8.NewClient(user.Token).WithPermissions(user.Permissions)
// })
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClientProvider(clientProvider))
//
func NewClientProvider(getClientByTokenFunc func(token string) *Client) *ClientProvider {
return &ClientProvider{
getClientByTokenFunc: getClientByTokenFunc,
}
}
// WithCache adds cache options to the ClientProvider.
//
// ttl is the time until the cache entry will expire. A TTL of gocache.NoExpiration (-1) means no expiration
// maxSize is the maximum amount of entries that can be in the cache at any given time.
// If a value of gocache.NoMaxSize (0) or less is provided for maxSize, there will be no maximum size.
//
// Example:
// clientProvider := g8.NewClientProvider(func(token string) *g8.Client {
// // We'll assume that the following function calls your database and returns a struct "User" that
// // has the user's token as well as the permissions granted to said user
// user := database.GetUserByToken(token)
// if user != nil {
// return g8.NewClient(user.Token).WithPermissions(user.Permissions)
// }
// return nil
// })
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClientProvider(clientProvider.WithCache(time.Hour, 70000)))
//
func (provider *ClientProvider) WithCache(ttl time.Duration, maxSize int) *ClientProvider {
provider.cache = gocache.NewCache().WithEvictionPolicy(gocache.LeastRecentlyUsed).WithMaxSize(maxSize)
provider.ttl = ttl
return provider
}
// StartCacheJanitor starts the cache janitor, which passively deletes expired cache entries in the background.
//
// Not really necessary unless you have a lot of clients (100000+).
//
// Even without the janitor, active eviction will still happen (i.e. when GetClientByToken is called, but the cache
// entry for the given token has expired, the cache entry will be automatically deleted and re-fetched from the
// user-defined getClientByTokenFunc)
func (provider *ClientProvider) StartCacheJanitor() error {
if provider.cache == nil {
// Can't start the cache janitor if there's no cache
return ErrCacheNotInitialized
}
if provider.ttl != gocache.NoExpiration {
return provider.cache.StartJanitor()
}
return ErrNoExpiration
}
// StopCacheJanitor stops the cache janitor
//
// Not required unless your application initializes multiple providers over the course of its lifecycle.
// In English, that means if you initialize a ClientProvider only once on application start and it stays up
// until your application shuts down, you don't need to call this function.
func (provider *ClientProvider) StopCacheJanitor() {
if provider.cache != nil {
provider.cache.StopJanitor()
}
}
// GetClientByToken retrieves a client by its token through the provided getClientByTokenFunc.
func (provider *ClientProvider) GetClientByToken(token string) *Client {
if provider.cache == nil {
return provider.getClientByTokenFunc(token)
}
if cachedClient, exists := provider.cache.Get(token); exists {
if cachedClient == nil {
return nil
}
// Safely typecast the client.
// Regardless of whether the typecast is successful or not, we return client since it'll be either client or
// nil. Technically, it should never be nil, but it's better to be safe than sorry.
client, _ := cachedClient.(*Client)
return client
}
client := provider.getClientByTokenFunc(token)
provider.cache.SetWithTTL(token, client, provider.ttl)
return client
}

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package g8
import (
"context"
"net/http"
"strings"
)
const (
// AuthorizationHeader is the header in which g8 looks for the authorization bearer token
AuthorizationHeader = "Authorization"
// DefaultUnauthorizedResponseBody is the default response body returned if a request was sent with a missing or invalid token
DefaultUnauthorizedResponseBody = "token is missing or invalid"
// DefaultTooManyRequestsResponseBody is the default response body returned if a request exceeded the allowed rate limit
DefaultTooManyRequestsResponseBody = "too many requests"
// TokenContextKey is the key used to store the token in the context.
TokenContextKey = "g8.token"
)
// Gate is lock to the front door of your API, letting only those you allow through.
type Gate struct {
authorizationService *AuthorizationService
unauthorizedResponseBody []byte
customTokenExtractorFunc func(request *http.Request) string
rateLimiter *RateLimiter
tooManyRequestsResponseBody []byte
}
// Deprecated: use New instead.
func NewGate(authorizationService *AuthorizationService) *Gate {
return &Gate{
authorizationService: authorizationService,
unauthorizedResponseBody: []byte(DefaultUnauthorizedResponseBody),
tooManyRequestsResponseBody: []byte(DefaultTooManyRequestsResponseBody),
}
}
// New creates a new Gate.
func New() *Gate {
return &Gate{
unauthorizedResponseBody: []byte(DefaultUnauthorizedResponseBody),
tooManyRequestsResponseBody: []byte(DefaultTooManyRequestsResponseBody),
}
}
// WithAuthorizationService sets the authorization service to use.
//
// If there is no authorization service, Gate will not enforce authorization.
func (gate *Gate) WithAuthorizationService(authorizationService *AuthorizationService) *Gate {
gate.authorizationService = authorizationService
return gate
}
// WithCustomUnauthorizedResponseBody sets a custom response body when Gate determines that a request must be blocked
func (gate *Gate) WithCustomUnauthorizedResponseBody(unauthorizedResponseBody []byte) *Gate {
gate.unauthorizedResponseBody = unauthorizedResponseBody
return gate
}
// WithCustomTokenExtractor allows the specification of a custom function to extract a token from a request.
// If a custom token extractor is not specified, the token will be extracted from the Authorization header.
//
// For instance, if you're using a session cookie, you can extract the token from the cookie like so:
// authorizationService := g8.NewAuthorizationService()
// customTokenExtractorFunc := func(request *http.Request) string {
// sessionCookie, err := request.Cookie("session")
// if err != nil {
// return ""
// }
// return sessionCookie.Value
// }
// gate := g8.New().WithAuthorizationService(authorizationService).WithCustomTokenExtractor(customTokenExtractorFunc)
//
// You would normally use this with a client provider that matches whatever need you have.
// For example, if you're using a session cookie, your client provider would retrieve the user from the session ID
// extracted by this custom token extractor.
//
// Note that for the sake of convenience, the token extracted from the request is passed the protected handlers request
// context under the key TokenContextKey. This is especially useful if the token is in fact a session ID.
func (gate *Gate) WithCustomTokenExtractor(customTokenExtractorFunc func(request *http.Request) string) *Gate {
gate.customTokenExtractorFunc = customTokenExtractorFunc
return gate
}
// WithRateLimit adds rate limiting to the Gate
//
// If you just want to use a gate for rate limiting purposes:
// gate := g8.New().WithRateLimit(50)
//
func (gate *Gate) WithRateLimit(maximumRequestsPerSecond int) *Gate {
gate.rateLimiter = NewRateLimiter(maximumRequestsPerSecond)
return gate
}
// Protect secures a handler, requiring requests going through to have a valid Authorization Bearer token.
// Unlike ProtectWithPermissions, Protect will allow access to any registered tokens, regardless of their permissions
// or lack thereof.
//
// Example:
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithToken("token"))
// router := http.NewServeMux()
// // Without protection
// router.Handle("/handle", yourHandler)
// // With protection
// router.Handle("/handle", gate.Protect(yourHandler))
//
// The token extracted from the request is passed to the handlerFunc request context under the key TokenContextKey
func (gate *Gate) Protect(handler http.Handler) http.Handler {
return gate.ProtectWithPermissions(handler, nil)
}
// ProtectWithPermissions secures a handler, requiring requests going through to have a valid Authorization Bearer token
// as well as a slice of permissions that must be met.
//
// Example:
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClient(g8.NewClient("token").WithPermission("admin")))
// router := http.NewServeMux()
// // Without protection
// router.Handle("/handle", yourHandler)
// // With protection
// router.Handle("/handle", gate.ProtectWithPermissions(yourHandler, []string{"admin"}))
//
// The token extracted from the request is passed to the handlerFunc request context under the key TokenContextKey
func (gate *Gate) ProtectWithPermissions(handler http.Handler, permissions []string) http.Handler {
return gate.ProtectFuncWithPermissions(func(writer http.ResponseWriter, request *http.Request) {
handler.ServeHTTP(writer, request)
}, permissions)
}
// ProtectWithPermission does the same thing as ProtectWithPermissions, but for a single permission instead of a
// slice of permissions
//
// See ProtectWithPermissions for further documentation
func (gate *Gate) ProtectWithPermission(handler http.Handler, permission string) http.Handler {
return gate.ProtectFuncWithPermissions(func(writer http.ResponseWriter, request *http.Request) {
handler.ServeHTTP(writer, request)
}, []string{permission})
}
// ProtectFunc secures a handlerFunc, requiring requests going through to have a valid Authorization Bearer token.
// Unlike ProtectFuncWithPermissions, ProtectFunc will allow access to any registered tokens, regardless of their
// permissions or lack thereof.
//
// Example:
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithToken("token"))
// router := http.NewServeMux()
// // Without protection
// router.HandleFunc("/handle", yourHandlerFunc)
// // With protection
// router.HandleFunc("/handle", gate.ProtectFunc(yourHandlerFunc))
//
// The token extracted from the request is passed to the handlerFunc request context under the key TokenContextKey
func (gate *Gate) ProtectFunc(handlerFunc http.HandlerFunc) http.HandlerFunc {
return gate.ProtectFuncWithPermissions(handlerFunc, nil)
}
// ProtectFuncWithPermissions secures a handler, requiring requests going through to have a valid Authorization Bearer
// token as well as a slice of permissions that must be met.
//
// Example:
// gate := g8.New().WithAuthorizationService(g8.NewAuthorizationService().WithClient(g8.NewClient("token").WithPermission("admin")))
// router := http.NewServeMux()
// // Without protection
// router.HandleFunc("/handle", yourHandlerFunc)
// // With protection
// router.HandleFunc("/handle", gate.ProtectFuncWithPermissions(yourHandlerFunc, []string{"admin"}))
//
// The token extracted from the request is passed to the handlerFunc request context under the key TokenContextKey
func (gate *Gate) ProtectFuncWithPermissions(handlerFunc http.HandlerFunc, permissions []string) http.HandlerFunc {
return func(writer http.ResponseWriter, request *http.Request) {
if gate.rateLimiter != nil {
if !gate.rateLimiter.Try() {
writer.WriteHeader(http.StatusTooManyRequests)
_, _ = writer.Write(gate.tooManyRequestsResponseBody)
return
}
}
if gate.authorizationService != nil {
var token string
if gate.customTokenExtractorFunc != nil {
token = gate.customTokenExtractorFunc(request)
} else {
token = extractTokenFromRequest(request)
}
if !gate.authorizationService.IsAuthorized(token, permissions) {
writer.WriteHeader(http.StatusUnauthorized)
_, _ = writer.Write(gate.unauthorizedResponseBody)
return
}
request = request.WithContext(context.WithValue(request.Context(), TokenContextKey, token))
}
handlerFunc(writer, request)
}
}
// ProtectFuncWithPermission does the same thing as ProtectFuncWithPermissions, but for a single permission instead of a
// slice of permissions
//
// See ProtectFuncWithPermissions for further documentation
func (gate *Gate) ProtectFuncWithPermission(handlerFunc http.HandlerFunc, permission string) http.HandlerFunc {
return gate.ProtectFuncWithPermissions(handlerFunc, []string{permission})
}
// extractTokenFromRequest extracts the bearer token from the AuthorizationHeader
func extractTokenFromRequest(request *http.Request) string {
return strings.TrimPrefix(request.Header.Get(AuthorizationHeader), "Bearer ")
}

42
vendor/github.com/TwiN/g8/ratelimiter.go generated vendored Normal file
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@ -0,0 +1,42 @@
package g8
import (
"sync"
"time"
)
// RateLimiter is a fixed rate limiter
type RateLimiter struct {
maximumExecutionsPerSecond int
executionsLeftInWindow int
windowStartTime time.Time
mutex sync.Mutex
}
// NewRateLimiter creates a RateLimiter
func NewRateLimiter(maximumExecutionsPerSecond int) *RateLimiter {
return &RateLimiter{
windowStartTime: time.Now(),
executionsLeftInWindow: maximumExecutionsPerSecond,
maximumExecutionsPerSecond: maximumExecutionsPerSecond,
}
}
// Try updates the number of executions if the rate limit quota hasn't been reached and returns whether the
// attempt was successful or not.
//
// Returns false if the execution was not successful (rate limit quota has been reached)
// Returns true if the execution was successful (rate limit quota has not been reached)
func (r *RateLimiter) Try() bool {
r.mutex.Lock()
defer r.mutex.Unlock()
if time.Now().Add(-time.Second).After(r.windowStartTime) {
r.windowStartTime = time.Now()
r.executionsLeftInWindow = r.maximumExecutionsPerSecond
}
if r.executionsLeftInWindow == 0 {
return false
}
r.executionsLeftInWindow--
return true
}