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// Copyright The Notary Project Authors.
// 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 tspclient
import (
"bytes"
"context"
"fmt"
"io"
"net/http"
"net/url"
"time"
)
// maxBodyLength specifies the max content can be received from the remote
// server.
// The legnth of a regular TSA response with certificates is usually less than
// 10 KiB.
var maxBodyLength = 1 * 1024 * 1024 // 1 MiB
// const for MediaTypes defined in RFC 3161 3.4
const (
// MediaTypeTimestampQuery is the content-type of timestamp query.
// RFC 3161 3.4
MediaTypeTimestampQuery = "application/timestamp-query"
// MediaTypeTimestampReply is the content-type of timestamp reply
// RFC 3161 3.4
MediaTypeTimestampReply = "application/timestamp-reply"
)
// httpTimestamper is a HTTP-based timestamper.
type httpTimestamper struct {
httpClient *http.Client
endpoint string
}
// NewHTTPTimestamper creates a HTTP-based timestamper with the endpoint
// provided by the TSA.
// http.DefaultTransport is used if nil RoundTripper is passed.
func NewHTTPTimestamper(httpClient *http.Client, endpoint string) (Timestamper, error) {
if httpClient == nil {
httpClient = &http.Client{Timeout: 5 * time.Second}
}
tsaURL, err := url.Parse(endpoint)
if err != nil {
return nil, err
}
if tsaURL.Scheme != "http" && tsaURL.Scheme != "https" {
return nil, fmt.Errorf("endpoint %q: scheme must be http or https, but got %q", endpoint, tsaURL.Scheme)
}
if tsaURL.Host == "" {
return nil, fmt.Errorf("endpoint %q: host cannot be empty", endpoint)
}
return &httpTimestamper{
httpClient: httpClient,
endpoint: endpoint,
}, nil
}
// Timestamp sends the request to the remote TSA server for timestamping.
//
// Reference: RFC 3161 3.4 Time-Stamp Protocol via HTTP
func (ts *httpTimestamper) Timestamp(ctx context.Context, req *Request) (*Response, error) {
// sanity check
if err := req.Validate(); err != nil {
return nil, err
}
// prepare for http request
reqBytes, err := req.MarshalBinary()
if err != nil {
return nil, err
}
hReq, err := http.NewRequestWithContext(ctx, http.MethodPost, ts.endpoint, bytes.NewReader(reqBytes))
if err != nil {
return nil, err
}
hReq.Header.Set("Content-Type", MediaTypeTimestampQuery)
// send the request to the remote TSA server
hResp, err := ts.httpClient.Do(hReq)
if err != nil {
return nil, err
}
defer hResp.Body.Close()
// verify HTTP response
if hResp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("%s %q: https response bad status: %s", http.MethodPost, ts.endpoint, hResp.Status)
}
if contentType := hResp.Header.Get("Content-Type"); contentType != MediaTypeTimestampReply {
return nil, fmt.Errorf("%s %q: unexpected response content type: %s", http.MethodPost, ts.endpoint, contentType)
}
// read TSA response
lr := &io.LimitedReader{
R: hResp.Body,
N: int64(maxBodyLength),
}
respBytes, err := io.ReadAll(lr)
if err != nil {
return nil, err
}
if lr.N == 0 {
return nil, fmt.Errorf("%s %q: unexpected large http response, max response body size allowed is %d MiB", hResp.Request.Method, hResp.Request.URL, maxBodyLength/1024/1024)
}
var resp Response
if err := resp.UnmarshalBinary(respBytes); err != nil {
return nil, err
}
// validate response against RFC 3161
if err := resp.Validate(req); err != nil {
return nil, err
}
return &resp, nil
}
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