// writeError writes an error to w in response to req. If the error was
// generated because of a required macaroon that the client does not
// have, we mint a macaroon that, when discharged, will grant the client
// the right to execute the given operation.
//
// The logic in this function is crucial to the security of the service
// - it must determine for a given operation what caveats to attach.
func (srv *targetServiceHandler) writeError(w http.ResponseWriter, req *http.Request, operation string, verr error) {
fail := func(code int, msg string, args ...interface{}) {
if code == http.StatusInternalServerError {
msg = "internal error: " + msg
}
http.Error(w, fmt.Sprintf(msg, args...), code)
}
if _, ok := errgo.Cause(verr).(*bakery.VerificationError); !ok {
fail(http.StatusForbidden, "%v", verr)
return
}
// Work out what caveats we need to apply for the given operation.
// Could special-case the operation here if desired.
caveats := []checkers.Caveat{{
Location: srv.authEndpoint,
Condition: "member-of-group target-service-users",
}, {
Condition: "operation " + operation,
}}
// Mint an appropriate macaroon and send it back to the client.
m, err := srv.svc.NewMacaroon("", nil, caveats)
if err != nil {
fail(http.StatusInternalServerError, "cannot mint macaroon: %v", err)
return
}
httpbakery.WriteDischargeRequiredErrorForRequest(w, m, "", verr, req)
}
func (s *ClientSuite) TestVersion0Generates407Status(c *gc.C) {
m, err := macaroon.New([]byte("root key"), "id", "location")
c.Assert(err, gc.IsNil)
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
httpbakery.WriteDischargeRequiredErrorForRequest(w, m, "", errgo.New("foo"), req)
}))
defer srv.Close()
resp, err := http.Get(srv.URL)
c.Assert(err, gc.IsNil)
c.Assert(resp.StatusCode, gc.Equals, http.StatusProxyAuthRequired)
}
func (s *ClientSuite) TestVersion1Generates401Status(c *gc.C) {
m, err := macaroon.New([]byte("root key"), "id", "location")
c.Assert(err, gc.IsNil)
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
httpbakery.WriteDischargeRequiredErrorForRequest(w, m, "", errgo.New("foo"), req)
}))
defer srv.Close()
req, err := http.NewRequest("GET", srv.URL, nil)
c.Assert(err, gc.IsNil)
req.Header.Set(httpbakery.BakeryProtocolHeader, "1")
resp, err := http.DefaultClient.Do(req)
c.Assert(err, gc.IsNil)
c.Assert(resp.StatusCode, gc.Equals, http.StatusUnauthorized)
c.Assert(resp.Header.Get("WWW-Authenticate"), gc.Equals, "Macaroon")
}