1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
# gin-contrib/cors
[](https://github.com/gin-contrib/cors/actions/workflows/go.yml)
[](https://codecov.io/gh/gin-contrib/cors)
[](https://goreportcard.com/report/github.com/gin-contrib/cors)
[](https://godoc.org/github.com/gin-contrib/cors)
- [gin-contrib/cors](#gin-contribcors)
- [Overview](#overview)
- [Installation](#installation)
- [Quick Start](#quick-start)
- [Advanced Usage](#advanced-usage)
- [Custom Configuration](#custom-configuration)
- [DefaultConfig Reference](#defaultconfig-reference)
- [Default() Convenience](#default-convenience)
- [Configuration Reference](#configuration-reference)
- [Notes on Configuration](#notes-on-configuration)
- [Examples](#examples)
- [Advanced Options](#advanced-options)
- [Custom Origin Validation](#custom-origin-validation)
- [With Gin Context](#with-gin-context)
- [Helper Methods](#helper-methods)
- [Validation \& Error Handling](#validation--error-handling)
- [Important Notes](#important-notes)
---
## Overview
**CORS (Cross-Origin Resource Sharing)** middleware for [Gin](https://github.com/gin-gonic/gin).
- Enables flexible CORS handling for your Gin-based APIs.
- Highly configurable: origins, methods, headers, credentials, and more.
---
## Installation
```sh
go get github.com/gin-contrib/cors
```
Import in your Go code:
```go
import "github.com/gin-contrib/cors"
```
---
## Quick Start
Allow all origins (default):
```go
import (
"github.com/gin-contrib/cors"
"github.com/gin-gonic/gin"
)
func main() {
router := gin.Default()
router.Use(cors.Default()) // All origins allowed by default
router.Run()
}
```
> ⚠️ **Warning:** Allowing all origins disables cookies for clients. For credentialed requests, **do not** allow all origins.
---
## Advanced Usage
### Custom Configuration
Configure allowed origins, methods, headers, and more:
```go
import (
"time"
"github.com/gin-contrib/cors"
"github.com/gin-gonic/gin"
)
func main() {
router := gin.Default()
router.Use(cors.New(cors.Config{
AllowOrigins: []string{"https://foo.com"},
AllowMethods: []string{"PUT", "PATCH"},
AllowHeaders: []string{"Origin"},
ExposeHeaders: []string{"Content-Length"},
AllowCredentials: true,
AllowOriginFunc: func(origin string) bool {
return origin == "https://github.com"
},
MaxAge: 12 * time.Hour,
}))
router.Run()
}
```
---
### DefaultConfig Reference
Start with library defaults and customize as needed:
```go
import (
"github.com/gin-contrib/cors"
"github.com/gin-gonic/gin"
)
func main() {
router := gin.Default()
config := cors.DefaultConfig()
config.AllowOrigins = []string{"http://google.com"}
// config.AllowOrigins = []string{"http://google.com", "http://facebook.com"}
// config.AllowAllOrigins = true
router.Use(cors.New(config))
router.Run()
}
```
> **Note:** `Default()` allows all origins, but `DefaultConfig()` does **not**. To allow all origins, set `AllowAllOrigins = true`.
---
### Default() Convenience
Enable all origins with a single call:
```go
router.Use(cors.Default()) // Equivalent to AllowAllOrigins = true
```
---
## Configuration Reference
The middleware is controlled via the `cors.Config` struct. All fields are optional unless otherwise stated.
| Field | Type | Default | Description |
|-------------------------------|-----------------------------|-----------------------------------------------------------|-----------------------------------------------------------------------------------------------|
| `AllowAllOrigins` | `bool` | `false` | If true, allows all origins. Credentials **cannot** be used. |
| `AllowOrigins` | `[]string` | `[]` | List of allowed origins. Supports exact match, `*`, and wildcards. |
| `AllowOriginFunc` | `func(string) bool` | `nil` | Custom function to validate origin. If set, `AllowOrigins` is ignored. |
| `AllowOriginWithContextFunc` | `func(*gin.Context,string)bool` | `nil` | Like `AllowOriginFunc`, but with request context. |
| `AllowMethods` | `[]string` | `[]string{"GET", "POST", "PUT", "PATCH", "DELETE", "HEAD", "OPTIONS"}` | Allowed HTTP methods. |
| `AllowPrivateNetwork` | `bool` | `false` | Adds [Private Network Access](https://wicg.github.io/private-network-access/) CORS header. |
| `AllowHeaders` | `[]string` | `[]` | List of non-simple headers permitted in requests. |
| `AllowCredentials` | `bool` | `false` | Allow cookies, HTTP auth, or client certs. Only if precise origins are used. |
| `ExposeHeaders` | `[]string` | `[]` | Headers exposed to the browser. |
| `MaxAge` | `time.Duration` | `12 * time.Hour` | Cache time for preflight requests. |
| `AllowWildcard` | `bool` | `false` | Enables wildcards in origins (e.g. `https://*.example.com`). |
| `AllowBrowserExtensions` | `bool` | `false` | Allow browser extension schemes as origins (e.g. `chrome-extension://`). |
| `CustomSchemas` | `[]string` | `nil` | Additional allowed URI schemes (e.g. `tauri://`). |
| `AllowWebSockets` | `bool` | `false` | Allow `ws://` and `wss://` schemas. |
| `AllowFiles` | `bool` | `false` | Allow `file://` origins (dangerous; use only if necessary). |
| `OptionsResponseStatusCode` | `int` | `204` | Custom status code for `OPTIONS` responses. |
---
### Notes on Configuration
- Only one of `AllowAllOrigins`, `AllowOrigins`, `AllowOriginFunc`, or `AllowOriginWithContextFunc` should be set.
- If `AllowAllOrigins` is true, other origin settings are ignored and credentialed requests are not allowed.
- If `AllowWildcard` is enabled, only one `*` is allowed per origin string.
- Use `AllowBrowserExtensions`, `AllowWebSockets`, or `AllowFiles` to permit non-HTTP(s) protocols as origins.
- Custom schemas allow, for example, usage in desktop apps via custom URI schemes (`tauri://`, etc.).
- If both `AllowOriginFunc` and `AllowOriginWithContextFunc` are set, the context-specific function is preferred.
---
### Examples
#### Advanced Options
```go
config := cors.Config{
AllowOrigins: []string{"https://*.foo.com", "https://bar.com"},
AllowWildcard: true,
AllowMethods: []string{"GET", "POST"},
AllowHeaders: []string{"Authorization", "Content-Type"},
AllowCredentials: true,
AllowBrowserExtensions: true,
AllowWebSockets: true,
AllowFiles: false,
CustomSchemas: []string{"tauri://"},
MaxAge: 24 * time.Hour,
ExposeHeaders: []string{"X-Custom-Header"},
AllowPrivateNetwork: true,
}
```
#### Custom Origin Validation
```go
config := cors.Config{
AllowOriginFunc: func(origin string) bool {
// Allow any github.com subdomain or a custom rule
return strings.HasSuffix(origin, "github.com")
},
}
```
#### With Gin Context
```go
config := cors.Config{
AllowOriginWithContextFunc: func(c *gin.Context, origin string) bool {
// Allow only if a certain header is present
return c.Request.Header.Get("X-Allow-CORS") == "yes"
},
}
```
---
## Helper Methods
Dynamically add methods or headers to the config:
```go
config.AddAllowMethods("DELETE", "OPTIONS")
config.AddAllowHeaders("X-My-Header")
config.AddExposeHeaders("X-Other-Header")
```
---
## Validation & Error Handling
- Calling `Validate()` on a `Config` checks for misconfiguration (called internally).
- If `AllowAllOrigins` is set, you cannot also set `AllowOrigins` or any `AllowOriginFunc`.
- If neither `AllowAllOrigins`, `AllowOriginFunc`, nor `AllowOrigins` is set, an error is raised.
- If an `AllowOrigin` contains a wildcard but `AllowWildcard` is not enabled, or more than one `*` is present, a panic is triggered.
- Invalid origin schemas or unsupported wildcards are rejected.
---
## Important Notes
- **Enabling all origins disables cookies:** When `AllowAllOrigins` is enabled, Gin cannot set cookies for clients. If you need credential sharing (cookies, authentication headers), **do not** allow all origins.
- For detailed documentation and configuration options, see the [GoDoc](https://godoc.org/github.com/gin-contrib/cors).
|
