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// Copyright 2021 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 http is a simple client for interacting with witnesses over HTTP.
package http
import (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"net/url"
"os"
wit_api "github.com/google/certificate-transparency-go/internal/witness/api"
"k8s.io/klog/v2"
)
// ErrSTHTooOld is returned if the STH passed to Update needs to be updated.
var ErrSTHTooOld = errors.New("STH too old")
// Witness consists of the witness' URL and signature verifier.
type Witness struct {
URL *url.URL
}
// GetLatestSTH returns a recent STH from the witness for the specified log ID.
func (w Witness) GetLatestSTH(ctx context.Context, logID string) ([]byte, error) {
u, err := w.URL.Parse(fmt.Sprintf(wit_api.HTTPGetSTH, url.PathEscape(logID)))
if err != nil {
return nil, fmt.Errorf("failed to parse URL: %v", err)
}
req, err := http.NewRequest(http.MethodGet, u.String(), nil)
if err != nil {
return nil, fmt.Errorf("failed to create request: %v", err)
}
resp, err := http.DefaultClient.Do(req.WithContext(ctx))
if err != nil {
return nil, fmt.Errorf("failed to do http request: %v", err)
}
defer func() {
if err := resp.Body.Close(); err != nil {
klog.Errorf("Failed to close response body: %v", err)
}
}()
if resp.StatusCode == 404 {
return nil, os.ErrNotExist
} else if resp.StatusCode != 200 {
return nil, fmt.Errorf("bad status response: %s", resp.Status)
}
return io.ReadAll(resp.Body)
}
// Update attempts to clock the witness forward for the given logID.
// The latest signed STH will be returned if this succeeds, or if the error is
// http.ErrSTHTooOld. In all other cases no STH should be expected.
func (w Witness) Update(ctx context.Context, logID string, sth []byte, proof [][]byte) ([]byte, error) {
reqBody, err := json.MarshalIndent(&wit_api.UpdateRequest{
STH: sth,
Proof: proof,
}, "", " ")
if err != nil {
return nil, fmt.Errorf("failed to marshal update request: %v", err)
}
u, err := w.URL.Parse(fmt.Sprintf(wit_api.HTTPUpdate, url.PathEscape(logID)))
if err != nil {
return nil, fmt.Errorf("failed to parse URL: %v", err)
}
req, err := http.NewRequest(http.MethodPut, u.String(), bytes.NewReader(reqBody))
if err != nil {
return nil, fmt.Errorf("failed to create request: %v", err)
}
resp, err := http.DefaultClient.Do(req.WithContext(ctx))
if err != nil {
return nil, fmt.Errorf("failed to do http request: %v", err)
}
if resp.Request.Method != "PUT" {
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Redirections#permanent_redirections
return nil, fmt.Errorf("PUT request to %q was converted to %s request to %q", u.String(), resp.Request.Method, resp.Request.URL)
}
defer func() {
if err := resp.Body.Close(); err != nil {
klog.Errorf("Failed to close response body: %v", err)
}
}()
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("failed to read body: %v", err)
}
if resp.StatusCode != 200 {
if resp.StatusCode == 409 {
return body, ErrSTHTooOld
}
return nil, fmt.Errorf("bad status response (%s): %q", resp.Status, body)
}
return body, nil
}
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