# Go CORS handler [](https://godoc.org/github.com/rs/cors) [](https://raw.githubusercontent.com/rs/cors/master/LICENSE) [](https://travis-ci.org/rs/cors)
CORS is a `net/http` handler implementing [Cross Origin Resource Sharing W3 specification](http://www.w3.org/TR/cors/) in Golang.
## Getting Started
After installing Go and setting up your [GOPATH](http://golang.org/doc/code.html#GOPATH), create your first `.go` file. We'll call it `server.go`.
Parameters are passed to the middleware thru the `cors.New` method as follow:
```go
c:=cors.New(cors.Options{
AllowedOrigins:[]string{"http://foo.com"},
AllowCredentials:true,
})
// Insert the middleware
handler=c.Handler(handler)
```
***AllowedOrigins**`[]string`: 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. The default value is `*`.
***AllowedMethods**`[]string`: A list of methods the client is allowed to use with cross-domain requests.
***AllowedHeaders**`[]string`: A list of non simple headers the client is allowed to use with cross-domain requests. Default value is simple methods (`GET` and `POST`)
***ExposedHeaders**`[]string`: Indicates which headers are safe to expose to the API of a CORS API specification
***AllowCredentials**`bool`: Indicates whether the request can include user credentials like cookies, HTTP authentication or client side SSL certificates. The default is `false`.
***MaxAge**`int`: Indicates how long (in seconds) the results of a preflight request can be cached. The default is `0` which stands for no max age.
See [API documentation](http://godoc.org/github.com/rs/cors) for more info.
## Licenses
All source code is licensed under the [MIT License](https://raw.github.com/rs/cors/master/LICENSE).
XHandler is a bridge between [net/context](https://godoc.org/golang.org/x/net/context) and `http.Handler`.
It lets you enforce `net/context` in your handlers without sacrificing compatibility with existing `http.Handlers` nor imposing a specific router.
Thanks to `net/context` deadline management, `xhandler` is able to enforce a per request deadline and will cancel the context when the client closes the connection unexpectedly.
You may create your own `net/context` aware handler pretty much the same way as you would do with http.Handler.
Read more about xhandler on [Dailymotion engineering blog](http://engineering.dailymotion.com/our-way-to-go/).
// Bridge context aware handlers with http.Handler using xhandler.Handle()
http.Handle("/test",c.Handler(xh))
iferr:=http.ListenAndServe(":8080",nil);err!=nil{
log.Fatal(err)
}
}
```
### Using xmux
Xhandler comes with an optional context aware [muxer](https://github.com/rs/xmux) forked from [httprouter](https://github.com/julienschmidt/httprouter):
```go
packagemain
import(
"fmt"
"log"
"net/http"
"time"
"github.com/rs/xhandler"
"github.com/rs/xmux"
"golang.org/x/net/context"
)
funcmain(){
c:=xhandler.Chain{}
// Append a context-aware middleware handler
c.UseC(xhandler.CloseHandler)
// Another context-aware middleware handler
c.UseC(xhandler.TimeoutHandler(2*time.Second))
mux:=xmux.New()
// Use c.Handler to terminate the chain with your final handler
