Commit ad0ad8f9 authored by ale's avatar ale

Add CORS support

The sso service endpoint should send the proper CORS headers and
respond to OPTIONS (for CORS prefetches) so that XmlHttpRequests on
authenticated sites can (partially) work.
parent 29862d1b
Pipeline #3506 passed with stages
in 4 minutes and 32 seconds
......@@ -15,11 +15,12 @@ import (
// Config data for the SSO service.
type Config struct {
SecretKeyFile string `yaml:"secret_key_file"`
PublicKeyFile string `yaml:"public_key_file"`
Domain string `yaml:"domain"`
AllowedServices []string `yaml:"allowed_services"`
AllowedExchanges []*struct {
SecretKeyFile string `yaml:"secret_key_file"`
PublicKeyFile string `yaml:"public_key_file"`
Domain string `yaml:"domain"`
AllowedServices []string `yaml:"allowed_services"`
AllowedCORSOrigins []string `yaml:"allowed_cors_origins"`
AllowedExchanges []*struct {
SrcRegexp string `yaml:"src_regexp"`
DstRegexp string `yaml:"dst_regexp"`
srcRx *regexp.Regexp
......
......@@ -23,6 +23,7 @@ import (
"github.com/gorilla/csrf"
"github.com/gorilla/mux"
"github.com/gorilla/sessions"
"github.com/rs/cors"
"git.autistici.org/id/auth"
authclient "git.autistici.org/id/auth/client"
......@@ -97,6 +98,7 @@ type Server struct {
renderer *renderer
urlPrefix string
homepageRedirectURL string
allowedOrigins []string
// User-configurable static data that we serve from memory.
siteLogo *staticContent
......@@ -130,6 +132,7 @@ func New(loginService *LoginService, authClient authclient.Client, config *Confi
loginService: loginService,
urlPrefix: urlPrefix,
homepageRedirectURL: config.HomepageRedirectURL,
allowedOrigins: config.AllowedCORSOrigins,
renderer: renderer,
}
if config.CSRFSecret != "" {
......@@ -445,8 +448,15 @@ func (h *Server) Handler() http.Handler {
}
})
// Add CORS headers around user-facing routes.
c := cors.New(cors.Options{
AllowedOrigins: h.allowedOrigins,
AllowCredentials: true,
MaxAge: 86400,
})
// User-facing routes require cache-busting and CSP headers.
root.PathPrefix(h.urlFor("/")).Handler(withDynamicHeaders(userh))
root.PathPrefix(h.urlFor("/")).Handler(withDynamicHeaders(c.Handler(userh)))
return root
}
......
Copyright (c) 2014 Olivier Poitrey <rs@dailymotion.com>
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.
# Go CORS handler [![godoc](http://img.shields.io/badge/godoc-reference-blue.svg?style=flat)](https://godoc.org/github.com/rs/cors) [![license](http://img.shields.io/badge/license-MIT-red.svg?style=flat)](https://raw.githubusercontent.com/rs/cors/master/LICENSE) [![build](https://img.shields.io/travis/rs/cors.svg?style=flat)](https://travis-ci.org/rs/cors) [![Coverage](http://gocover.io/_badge/github.com/rs/cors)](http://gocover.io/github.com/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`.
```go
package main
import (
"net/http"
"github.com/rs/cors"
)
func main() {
mux := http.NewServeMux()
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
w.Write([]byte("{\"hello\": \"world\"}"))
})
// cors.Default() setup the middleware with default options being
// all origins accepted with simple methods (GET, POST). See
// documentation below for more options.
handler := cors.Default().Handler(mux)
http.ListenAndServe(":8080", handler)
}
```
Install `cors`:
go get github.com/rs/cors
Then run your server:
go run server.go
The server now runs on `localhost:8080`:
$ curl -D - -H 'Origin: http://foo.com' http://localhost:8080/
HTTP/1.1 200 OK
Access-Control-Allow-Origin: foo.com
Content-Type: application/json
Date: Sat, 25 Oct 2014 03:43:57 GMT
Content-Length: 18
{"hello": "world"}
### Allow * With Credentials Security Protection
This library has been modified to avoid a well known security issue when configured with `AllowedOrigins` to `*` and `AllowCredentials` to `true`. Such setup used to make the library reflects the request `Origin` header value, working around a security protection embedded into the standard that makes clients to refuse such configuration. This behavior has been removed with [#55](https://github.com/rs/cors/issues/55) and [#57](https://github.com/rs/cors/issues/57).
If you depend on this behavior and understand the implications, you can restore it using the `AllowOriginFunc` with `func(origin string) {return true}`.
Please refer to [#55](https://github.com/rs/cors/issues/55) for more information about the security implications.
### More Examples
* `net/http`: [examples/nethttp/server.go](https://github.com/rs/cors/blob/master/examples/nethttp/server.go)
* [Goji](https://goji.io): [examples/goji/server.go](https://github.com/rs/cors/blob/master/examples/goji/server.go)
* [Martini](http://martini.codegangsta.io): [examples/martini/server.go](https://github.com/rs/cors/blob/master/examples/martini/server.go)
* [Negroni](https://github.com/codegangsta/negroni): [examples/negroni/server.go](https://github.com/rs/cors/blob/master/examples/negroni/server.go)
* [Alice](https://github.com/justinas/alice): [examples/alice/server.go](https://github.com/rs/cors/blob/master/examples/alice/server.go)
* [HttpRouter](https://github.com/julienschmidt/httprouter): [examples/httprouter/server.go](https://github.com/rs/cors/blob/master/examples/httprouter/server.go)
* [Gorilla](http://www.gorillatoolkit.org/pkg/mux): [examples/gorilla/server.go](https://github.com/rs/cors/blob/master/examples/gorilla/server.go)
* [Buffalo](https://gobuffalo.io): [examples/buffalo/server.go](https://github.com/rs/cors/blob/master/examples/buffalo/server.go)
* [Gin](https://gin-gonic.github.io/gin): [examples/gin/server.go](https://github.com/rs/cors/blob/master/examples/gin/server.go)
* [Chi](https://github.com/go-chi/chi): [examples/chi/server.go](https://github.com/rs/cors/blob/master/examples/chi/server.go)
## Parameters
Parameters are passed to the middleware thru the `cors.New` method as follow:
```go
c := cors.New(cors.Options{
AllowedOrigins: []string{"http://foo.com", "http://foo.com:8080"},
AllowCredentials: true,
// Enable Debugging for testing, consider disabling in production
Debug: 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. An origin may contain a wildcard (`*`) to replace 0 or more characters (i.e.: `http://*.domain.com`). Usage of wildcards implies a small performance penality. Only one wildcard can be used per origin. The default value is `*`.
* **AllowOriginFunc** `func (origin string) bool`: A custom function to validate the origin. It takes the origin as an argument and returns true if allowed, or false otherwise. If this option is set, the content of `AllowedOrigins` is ignored.
* **AllowOriginRequestFunc** `func (r *http.Request origin string) bool`: A custom function to validate the origin. It takes the HTTP Request object and the origin as argument and returns true if allowed or false otherwise. If this option is set, the content of `AllowedOrigins` and `AllowOriginFunc` is ignored
* **AllowedMethods** `[]string`: A list of methods the client is allowed to use with cross-domain requests. Default value is simple methods (`GET` and `POST`).
* **AllowedHeaders** `[]string`: A list of non simple headers the client is allowed to use with cross-domain requests.
* **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.
* **OptionsPassthrough** `bool`: Instructs preflight to let other potential next handlers to process the `OPTIONS` method. Turn this on if your application handles `OPTIONS`.
* **Debug** `bool`: Debugging flag adds additional output to debug server side CORS issues.
See [API documentation](http://godoc.org/github.com/rs/cors) for more info.
## Benchmarks
BenchmarkWithout 20000000 64.6 ns/op 8 B/op 1 allocs/op
BenchmarkDefault 3000000 469 ns/op 114 B/op 2 allocs/op
BenchmarkAllowedOrigin 3000000 608 ns/op 114 B/op 2 allocs/op
BenchmarkPreflight 20000000 73.2 ns/op 0 B/op 0 allocs/op
BenchmarkPreflightHeader 20000000 73.6 ns/op 0 B/op 0 allocs/op
BenchmarkParseHeaderList 2000000 847 ns/op 184 B/op 6 allocs/op
BenchmarkParse…Single 5000000 290 ns/op 32 B/op 3 allocs/op
BenchmarkParse…Normalized 2000000 776 ns/op 160 B/op 6 allocs/op
## Licenses
All source code is licensed under the [MIT License](https://raw.github.com/rs/cors/master/LICENSE).
/*
Package cors is net/http handler to handle CORS related requests
as defined by http://www.w3.org/TR/cors/
You can configure it by passing an option struct to cors.New:
c := cors.New(cors.Options{
AllowedOrigins: []string{"foo.com"},
AllowedMethods: []string{http.MethodGet, http.MethodPost, http.MethodDelete},
AllowCredentials: true,
})
Then insert the handler in the chain:
handler = c.Handler(handler)
See Options documentation for more options.
The resulting handler is a standard net/http handler.
*/
package cors
import (
"log"
"net/http"
"os"
"strconv"
"strings"
)
// Options is a configuration container to setup the CORS middleware.
type Options struct {
// AllowedOrigins is 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.
// An origin may contain a wildcard (*) to replace 0 or more characters
// (i.e.: http://*.domain.com). Usage of wildcards implies a small performance penalty.
// Only one wildcard can be used per origin.
// Default value is ["*"]
AllowedOrigins []string
// AllowOriginFunc is a custom function to validate the origin. It take the origin
// as argument and returns true if allowed or false otherwise. If this option is
// set, the content of AllowedOrigins is ignored.
AllowOriginFunc func(origin string) bool
// AllowOriginFunc is a custom function to validate the origin. It takes the HTTP Request object and the origin as
// argument and returns true if allowed or false otherwise. If this option is set, the content of `AllowedOrigins`
// and `AllowOriginFunc` is ignored.
AllowOriginRequestFunc func(r *http.Request, origin string) bool
// AllowedMethods is a list of methods the client is allowed to use with
// cross-domain requests. Default value is simple methods (HEAD, GET and POST).
AllowedMethods []string
// AllowedHeaders is list of non simple headers the client is allowed to use with
// cross-domain requests.
// If the special "*" value is present in the list, all headers will be allowed.
// Default value is [] but "Origin" is always appended to the list.
AllowedHeaders []string
// ExposedHeaders indicates which headers are safe to expose to the API of a CORS
// API specification
ExposedHeaders []string
// MaxAge indicates how long (in seconds) the results of a preflight request
// can be cached
MaxAge int
// AllowCredentials indicates whether the request can include user credentials like
// cookies, HTTP authentication or client side SSL certificates.
AllowCredentials bool
// OptionsPassthrough instructs preflight to let other potential next handlers to
// process the OPTIONS method. Turn this on if your application handles OPTIONS.
OptionsPassthrough bool
// Debugging flag adds additional output to debug server side CORS issues
Debug bool
}
// Logger generic interface for logger
type Logger interface {
Printf(string, ...interface{})
}
// Cors http handler
type Cors struct {
// Debug logger
Log Logger
// Normalized list of plain allowed origins
allowedOrigins []string
// List of allowed origins containing wildcards
allowedWOrigins []wildcard
// Optional origin validator function
allowOriginFunc func(origin string) bool
// Optional origin validator (with request) function
allowOriginRequestFunc func(r *http.Request, origin string) bool
// Normalized list of allowed headers
allowedHeaders []string
// Normalized list of allowed methods
allowedMethods []string
// Normalized list of exposed headers
exposedHeaders []string
maxAge int
// Set to true when allowed origins contains a "*"
allowedOriginsAll bool
// Set to true when allowed headers contains a "*"
allowedHeadersAll bool
allowCredentials bool
optionPassthrough bool
}
// New creates a new Cors handler with the provided options.
func New(options Options) *Cors {
c := &Cors{
exposedHeaders: convert(options.ExposedHeaders, http.CanonicalHeaderKey),
allowOriginFunc: options.AllowOriginFunc,
allowOriginRequestFunc: options.AllowOriginRequestFunc,
allowCredentials: options.AllowCredentials,
maxAge: options.MaxAge,
optionPassthrough: options.OptionsPassthrough,
}
if options.Debug && c.Log == nil {
c.Log = log.New(os.Stdout, "[cors] ", log.LstdFlags)
}
// Normalize options
// Note: for origins and methods matching, the spec requires a case-sensitive matching.
// As it may error prone, we chose to ignore the spec here.
// Allowed Origins
if len(options.AllowedOrigins) == 0 {
if options.AllowOriginFunc == nil && options.AllowOriginRequestFunc == nil {
// Default is all origins
c.allowedOriginsAll = true
}
} else {
c.allowedOrigins = []string{}
c.allowedWOrigins = []wildcard{}
for _, origin := range options.AllowedOrigins {
// Normalize
origin = strings.ToLower(origin)
if origin == "*" {
// If "*" is present in the list, turn the whole list into a match all
c.allowedOriginsAll = true
c.allowedOrigins = nil
c.allowedWOrigins = nil
break
} else if i := strings.IndexByte(origin, '*'); i >= 0 {
// Split the origin in two: start and end string without the *
w := wildcard{origin[0:i], origin[i+1:]}
c.allowedWOrigins = append(c.allowedWOrigins, w)
} else {
c.allowedOrigins = append(c.allowedOrigins, origin)
}
}
}
// Allowed Headers
if len(options.AllowedHeaders) == 0 {
// Use sensible defaults
c.allowedHeaders = []string{"Origin", "Accept", "Content-Type", "X-Requested-With"}
} else {
// Origin is always appended as some browsers will always request for this header at preflight
c.allowedHeaders = convert(append(options.AllowedHeaders, "Origin"), http.CanonicalHeaderKey)
for _, h := range options.AllowedHeaders {
if h == "*" {
c.allowedHeadersAll = true
c.allowedHeaders = nil
break
}
}
}
// Allowed Methods
if len(options.AllowedMethods) == 0 {
// Default is spec's "simple" methods
c.allowedMethods = []string{http.MethodGet, http.MethodPost, http.MethodHead}
} else {
c.allowedMethods = convert(options.AllowedMethods, strings.ToUpper)
}
return c
}
// Default creates a new Cors handler with default options.
func Default() *Cors {
return New(Options{})
}
// AllowAll create a new Cors handler with permissive configuration allowing all
// origins with all standard methods with any header and credentials.
func AllowAll() *Cors {
return New(Options{
AllowedOrigins: []string{"*"},
AllowedMethods: []string{
http.MethodHead,
http.MethodGet,
http.MethodPost,
http.MethodPut,
http.MethodPatch,
http.MethodDelete,
},
AllowedHeaders: []string{"*"},
AllowCredentials: false,
})
}
// Handler apply the CORS specification on the request, and add relevant CORS headers
// as necessary.
func (c *Cors) Handler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != "" {
c.logf("Handler: Preflight request")
c.handlePreflight(w, r)
// Preflight requests are standalone and should stop the chain as some other
// middleware may not handle OPTIONS requests correctly. One typical example
// is authentication middleware ; OPTIONS requests won't carry authentication
// headers (see #1)
if c.optionPassthrough {
h.ServeHTTP(w, r)
} else {
w.WriteHeader(http.StatusOK)
}
} else {
c.logf("Handler: Actual request")
c.handleActualRequest(w, r)
h.ServeHTTP(w, r)
}
})
}
// HandlerFunc provides Martini compatible handler
func (c *Cors) HandlerFunc(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != "" {
c.logf("HandlerFunc: Preflight request")
c.handlePreflight(w, r)
} else {
c.logf("HandlerFunc: Actual request")
c.handleActualRequest(w, r)
}
}
// Negroni compatible interface
func (c *Cors) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
if r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != "" {
c.logf("ServeHTTP: Preflight request")
c.handlePreflight(w, r)
// Preflight requests are standalone and should stop the chain as some other
// middleware may not handle OPTIONS requests correctly. One typical example
// is authentication middleware ; OPTIONS requests won't carry authentication
// headers (see #1)
if c.optionPassthrough {
next(w, r)
} else {
w.WriteHeader(http.StatusOK)
}
} else {
c.logf("ServeHTTP: Actual request")
c.handleActualRequest(w, r)
next(w, r)
}
}
// handlePreflight handles pre-flight CORS requests
func (c *Cors) handlePreflight(w http.ResponseWriter, r *http.Request) {
headers := w.Header()
origin := r.Header.Get("Origin")
if r.Method != http.MethodOptions {
c.logf(" Preflight aborted: %s!=OPTIONS", r.Method)
return
}
// Always set Vary headers
// see https://github.com/rs/cors/issues/10,
// https://github.com/rs/cors/commit/dbdca4d95feaa7511a46e6f1efb3b3aa505bc43f#commitcomment-12352001
headers.Add("Vary", "Origin")
headers.Add("Vary", "Access-Control-Request-Method")
headers.Add("Vary", "Access-Control-Request-Headers")
if origin == "" {
c.logf(" Preflight aborted: empty origin")
return
}
if !c.isOriginAllowed(r, origin) {
c.logf(" Preflight aborted: origin '%s' not allowed", origin)
return
}
reqMethod := r.Header.Get("Access-Control-Request-Method")
if !c.isMethodAllowed(reqMethod) {
c.logf(" Preflight aborted: method '%s' not allowed", reqMethod)
return
}
reqHeaders := parseHeaderList(r.Header.Get("Access-Control-Request-Headers"))
if !c.areHeadersAllowed(reqHeaders) {
c.logf(" Preflight aborted: headers '%v' not allowed", reqHeaders)
return
}
if c.allowedOriginsAll {
headers.Set("Access-Control-Allow-Origin", "*")
} else {
headers.Set("Access-Control-Allow-Origin", origin)
}
// Spec says: Since the list of methods can be unbounded, simply returning the method indicated
// by Access-Control-Request-Method (if supported) can be enough
headers.Set("Access-Control-Allow-Methods", strings.ToUpper(reqMethod))
if len(reqHeaders) > 0 {
// Spec says: Since the list of headers can be unbounded, simply returning supported headers
// from Access-Control-Request-Headers can be enough
headers.Set("Access-Control-Allow-Headers", strings.Join(reqHeaders, ", "))
}
if c.allowCredentials {
headers.Set("Access-Control-Allow-Credentials", "true")
}
if c.maxAge > 0 {
headers.Set("Access-Control-Max-Age", strconv.Itoa(c.maxAge))
}
c.logf(" Preflight response headers: %v", headers)
}
// handleActualRequest handles simple cross-origin requests, actual request or redirects
func (c *Cors) handleActualRequest(w http.ResponseWriter, r *http.Request) {
headers := w.Header()
origin := r.Header.Get("Origin")
if r.Method == http.MethodOptions {
c.logf(" Actual request no headers added: method == %s", r.Method)
return
}
// Always set Vary, see https://github.com/rs/cors/issues/10
headers.Add("Vary", "Origin")
if origin == "" {
c.logf(" Actual request no headers added: missing origin")
return
}
if !c.isOriginAllowed(r, origin) {
c.logf(" Actual request no headers added: origin '%s' not allowed", origin)
return
}
// Note that spec does define a way to specifically disallow a simple method like GET or
// POST. Access-Control-Allow-Methods is only used for pre-flight requests and the
// spec doesn't instruct to check the allowed methods for simple cross-origin requests.
// We think it's a nice feature to be able to have control on those methods though.
if !c.isMethodAllowed(r.Method) {
c.logf(" Actual request no headers added: method '%s' not allowed", r.Method)
return
}
if c.allowedOriginsAll {
headers.Set("Access-Control-Allow-Origin", "*")
} else {
headers.Set("Access-Control-Allow-Origin", origin)
}
if len(c.exposedHeaders) > 0 {
headers.Set("Access-Control-Expose-Headers", strings.Join(c.exposedHeaders, ", "))
}
if c.allowCredentials {
headers.Set("Access-Control-Allow-Credentials", "true")
}
c.logf(" Actual response added headers: %v", headers)
}
// convenience method. checks if a logger is set.
func (c *Cors) logf(format string, a ...interface{}) {
if c.Log != nil {
c.Log.Printf(format, a...)
}
}
// isOriginAllowed checks if a given origin is allowed to perform cross-domain requests
// on the endpoint
func (c *Cors) isOriginAllowed(r *http.Request, origin string) bool {
if c.allowOriginRequestFunc != nil {
return c.allowOriginRequestFunc(r, origin)
}
if c.allowOriginFunc != nil {
return c.allowOriginFunc(origin)
}
if c.allowedOriginsAll {
return true
}
origin = strings.ToLower(origin)
for _, o := range c.allowedOrigins {
if o == origin {
return true
}
}
for _, w := range c.allowedWOrigins {
if w.match(origin) {
return true
}
}
return false
}
// isMethodAllowed checks if a given method can be used as part of a cross-domain request
// on the endpoing
func (c *Cors) isMethodAllowed(method string) bool {
if len(c.allowedMethods) == 0 {
// If no method allowed, always return false, even for preflight request
return false
}
method = strings.ToUpper(method)
if method == http.MethodOptions {
// Always allow preflight requests
return true
}
for _, m := range c.allowedMethods {
if m == method {
return true
}
}
return false
}
// areHeadersAllowed checks if a given list of headers are allowed to used within
// a cross-domain request.
func (c *Cors) areHeadersAllowed(requestedHeaders []string) bool {
if c.allowedHeadersAll || len(requestedHeaders) == 0 {
return true
}
for _, header := range requestedHeaders {
header = http.CanonicalHeaderKey(header)
found := false
for _, h := range c.allowedHeaders {
if h == header {
found = true
}
}
if !found {
return false
}
}
return true
}
module github.com/rs/cors
package cors
import "strings"
const toLower = 'a' - 'A'
type converter func(string) string
type wildcard struct {
prefix string