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// Copyright 2018 Google LLC All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package transport
import (
"context"
"fmt"
"net/http"
"github.com/google/go-containerregistry/pkg/authn"
"github.com/google/go-containerregistry/pkg/name"
)
// New returns a new RoundTripper based on the provided RoundTripper that has been
// setup to authenticate with the remote registry "reg", in the capacity
// laid out by the specified scopes.
//
// Deprecated: Use NewWithContext.
func New(reg name.Registry, auth authn.Authenticator, t http.RoundTripper, scopes []string) (http.RoundTripper, error) {
return NewWithContext(context.Background(), reg, auth, t, scopes)
}
// NewWithContext returns a new RoundTripper based on the provided RoundTripper that has been
// set up to authenticate with the remote registry "reg", in the capacity
// laid out by the specified scopes.
// In case the RoundTripper is already of the type Wrapper it assumes
// authentication was already done prior to this call, so it just returns
// the provided RoundTripper without further action
func NewWithContext(ctx context.Context, reg name.Registry, auth authn.Authenticator, t http.RoundTripper, scopes []string) (http.RoundTripper, error) {
// When the transport provided is of the type Wrapper this function assumes that the caller already
// executed the necessary login and check.
switch t.(type) {
case *Wrapper:
return t, nil
}
// The handshake:
// 1. Use "t" to ping() the registry for the authentication challenge.
//
// 2a. If we get back a 200, then simply use "t".
//
// 2b. If we get back a 401 with a Basic challenge, then use a transport
// that just attachs auth each roundtrip.
//
// 2c. If we get back a 401 with a Bearer challenge, then use a transport
// that attaches a bearer token to each request, and refreshes is on 401s.
// Perform an initial refresh to seed the bearer token.
// First we ping the registry to determine the parameters of the authentication handshake
// (if one is even necessary).
pr, err := ping(ctx, reg, t)
if err != nil {
return nil, err
}
// Wrap t with a useragent transport unless we already have one.
if _, ok := t.(*userAgentTransport); !ok {
t = NewUserAgent(t, "")
}
// Wrap t in a transport that selects the appropriate scheme based on the ping response.
t = &schemeTransport{
scheme: pr.scheme,
registry: reg,
inner: t,
}
switch pr.challenge.Canonical() {
case anonymous, basic:
return &Wrapper{&basicTransport{inner: t, auth: auth, target: reg.RegistryStr()}}, nil
case bearer:
// We require the realm, which tells us where to send our Basic auth to turn it into Bearer auth.
realm, ok := pr.parameters["realm"]
if !ok {
return nil, fmt.Errorf("malformed www-authenticate, missing realm: %v", pr.parameters)
}
service := pr.parameters["service"]
bt := &bearerTransport{
inner: t,
basic: auth,
realm: realm,
registry: reg,
service: service,
scopes: scopes,
scheme: pr.scheme,
}
if err := bt.refresh(ctx); err != nil {
return nil, err
}
return &Wrapper{bt}, nil
default:
return nil, fmt.Errorf("unrecognized challenge: %s", pr.challenge)
}
}
// Wrapper results in *not* wrapping supplied transport with additional logic such as retries, useragent and debug logging
// Consumers are opt-ing into providing their own transport without any additional wrapping.
type Wrapper struct {
inner http.RoundTripper
}
// RoundTrip delegates to the inner RoundTripper
func (w *Wrapper) RoundTrip(in *http.Request) (*http.Response, error) {
return w.inner.RoundTrip(in)
}
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