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97 lines
2.0 KiB
97 lines
2.0 KiB
package middleware
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import (
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"net/http"
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"strings"
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"github.com/zenazn/goji/web"
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)
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type autoOptionsState int
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const (
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aosInit autoOptionsState = iota
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aosHeaderWritten
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aosProxying
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)
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// I originally used an httptest.ResponseRecorder here, but package httptest
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// adds a flag which I'm not particularly eager to expose. This is essentially a
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// ResponseRecorder that has been specialized for the purpose at hand to avoid
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// the httptest dependency.
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type autoOptionsProxy struct {
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w http.ResponseWriter
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c *web.C
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state autoOptionsState
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}
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func (p *autoOptionsProxy) Header() http.Header {
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return p.w.Header()
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}
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func (p *autoOptionsProxy) Write(buf []byte) (int, error) {
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switch p.state {
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case aosInit:
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p.state = aosHeaderWritten
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case aosProxying:
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return len(buf), nil
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}
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return p.w.Write(buf)
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}
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func (p *autoOptionsProxy) WriteHeader(code int) {
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methods := getValidMethods(*p.c)
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switch p.state {
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case aosInit:
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if methods != nil && code == http.StatusNotFound {
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p.state = aosProxying
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break
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}
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p.state = aosHeaderWritten
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fallthrough
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default:
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p.w.WriteHeader(code)
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return
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}
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methods = addMethod(methods, "OPTIONS")
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p.w.Header().Set("Allow", strings.Join(methods, ", "))
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p.w.WriteHeader(http.StatusOK)
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}
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// AutomaticOptions automatically return an appropriate "Allow" header when the
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// request method is OPTIONS and the request would have otherwise been 404'd.
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func AutomaticOptions(c *web.C, h http.Handler) http.Handler {
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fn := func(w http.ResponseWriter, r *http.Request) {
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if r.Method == "OPTIONS" {
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w = &autoOptionsProxy{c: c, w: w}
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}
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h.ServeHTTP(w, r)
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}
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return http.HandlerFunc(fn)
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}
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func getValidMethods(c web.C) []string {
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if c.Env == nil {
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return nil
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}
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v, ok := c.Env[web.ValidMethodsKey]
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if !ok {
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return nil
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}
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if methods, ok := v.([]string); ok {
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return methods
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}
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return nil
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}
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func addMethod(methods []string, method string) []string {
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for _, m := range methods {
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if m == method {
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return methods
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}
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}
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return append(methods, method)
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}
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