forgejo-federation/vendor/github.com/mholt/acmez/acme/http.go

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// Copyright 2020 Matthew Holt
//
// 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 acme
import (
"bytes"
"context"
"crypto"
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"regexp"
"runtime"
"strconv"
"strings"
"sync"
"time"
"go.uber.org/zap"
)
// httpPostJWS performs robust HTTP requests by JWS-encoding the JSON of input.
// If output is specified, the response body is written into it: if the response
// Content-Type is JSON, it will be JSON-decoded into output (which must be a
// pointer); otherwise, if output is an io.Writer, the response body will be
// written to it uninterpreted. In all cases, the returned response value's
// body will have been drained and closed, so there is no need to close it again.
// It automatically retries in the case of network, I/O, or badNonce errors.
func (c *Client) httpPostJWS(ctx context.Context, privateKey crypto.Signer,
kid, endpoint string, input, output interface{}) (*http.Response, error) {
if err := c.provision(ctx); err != nil {
return nil, err
}
var resp *http.Response
var err error
// we can retry on internal server errors just in case it was a hiccup,
// but we probably don't need to retry so many times in that case
internalServerErrors, maxInternalServerErrors := 0, 3
// set a hard cap on the number of retries for any other reason
const maxAttempts = 10
var attempts int
for attempts = 1; attempts <= maxAttempts; attempts++ {
if attempts > 1 {
select {
case <-time.After(250 * time.Millisecond):
case <-ctx.Done():
return nil, ctx.Err()
}
}
var nonce string // avoid shadowing err
nonce, err = c.nonce(ctx)
if err != nil {
return nil, err
}
var encodedPayload []byte // avoid shadowing err
encodedPayload, err = jwsEncodeJSON(input, privateKey, keyID(kid), nonce, endpoint)
if err != nil {
return nil, fmt.Errorf("encoding payload: %v", err)
}
resp, err = c.httpReq(ctx, http.MethodPost, endpoint, encodedPayload, output)
if err == nil {
return resp, nil
}
// "When a server rejects a request because its nonce value was
// unacceptable (or not present), it MUST provide HTTP status code 400
// (Bad Request), and indicate the ACME error type
// 'urn:ietf:params:acme:error:badNonce'. An error response with the
// 'badNonce' error type MUST include a Replay-Nonce header field with a
// fresh nonce that the server will accept in a retry of the original
// query (and possibly in other requests, according to the server's
// nonce scoping policy). On receiving such a response, a client SHOULD
// retry the request using the new nonce." §6.5
var problem Problem
if errors.As(err, &problem) {
if problem.Type == ProblemTypeBadNonce {
if c.Logger != nil {
c.Logger.Debug("server rejected our nonce; retrying",
zap.String("detail", problem.Detail),
zap.Error(err))
}
continue
}
}
// internal server errors *could* just be a hiccup and it may be worth
// trying again, but not nearly so many times as for other reasons
if resp != nil && resp.StatusCode >= 500 {
internalServerErrors++
if internalServerErrors < maxInternalServerErrors {
continue
}
}
// for any other error, there's not much we can do automatically
break
}
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return resp, fmt.Errorf("request to %s failed after %d attempts: %w",
endpoint, attempts, err)
}
// httpReq robustly performs an HTTP request using the given method to the given endpoint, honoring
// the given context's cancellation. The joseJSONPayload is optional; if not nil, it is expected to
// be a JOSE+JSON encoding. The output is also optional; if not nil, the response body will be read
// into output. If the response Content-Type is JSON, it will be JSON-decoded into output, which
// must be a pointer type. If the response is any other Content-Type and if output is a io.Writer,
// it will be written (without interpretation or decoding) to output. In all cases, the returned
// response value will have the body drained and closed, so there is no need to close it again.
//
// If there are any network or I/O errors, the request will be retried as safely and resiliently as
// possible.
func (c *Client) httpReq(ctx context.Context, method, endpoint string, joseJSONPayload []byte, output interface{}) (*http.Response, error) {
// even if the caller doesn't specify an output, we still use a
// buffer to store possible error response (we reset it later)
buf := bufPool.Get().(*bytes.Buffer)
defer bufPool.Put(buf)
var resp *http.Response
var err error
// potentially retry the request if there's network, I/O, or server internal errors
const maxAttempts = 3
for attempt := 0; attempt < maxAttempts; attempt++ {
if attempt > 0 {
// traffic calming ahead
select {
case <-time.After(250 * time.Millisecond):
case <-ctx.Done():
return nil, ctx.Err()
}
}
var body io.Reader
if joseJSONPayload != nil {
body = bytes.NewReader(joseJSONPayload)
}
var req *http.Request
req, err = http.NewRequestWithContext(ctx, method, endpoint, body)
if err != nil {
return nil, fmt.Errorf("creating request: %w", err)
}
if len(joseJSONPayload) > 0 {
req.Header.Set("Content-Type", "application/jose+json")
}
// on first attempt, we need to reset buf since it
// came from the pool; after first attempt, we should
// still reset it because we might be retrying after
// a partial download
buf.Reset()
var retry bool
resp, retry, err = c.doHTTPRequest(req, buf)
if err != nil {
if retry {
if c.Logger != nil {
c.Logger.Warn("HTTP request failed; retrying",
zap.String("url", req.URL.String()),
zap.Error(err))
}
continue
}
break
}
// check for HTTP errors
switch {
case resp.StatusCode >= 200 && resp.StatusCode < 300: // OK
case resp.StatusCode >= 400 && resp.StatusCode < 600: // error
if parseMediaType(resp) == "application/problem+json" {
// "When the server responds with an error status, it SHOULD provide
// additional information using a problem document [RFC7807]." (§6.7)
var problem Problem
err = json.Unmarshal(buf.Bytes(), &problem)
if err != nil {
return resp, fmt.Errorf("HTTP %d: JSON-decoding problem details: %w (raw='%s')",
resp.StatusCode, err, buf.String())
}
if resp.StatusCode >= 500 && joseJSONPayload == nil {
// a 5xx status is probably safe to retry on even after a
// request that had no I/O errors; it could be that the
// server just had a hiccup... so try again, but only if
// there is no request body, because we can't replay a
// request that has an anti-replay nonce, obviously
err = problem
continue
}
return resp, problem
}
return resp, fmt.Errorf("HTTP %d: %s", resp.StatusCode, buf.String())
default: // what even is this
return resp, fmt.Errorf("unexpected status code: HTTP %d", resp.StatusCode)
}
// do not retry if we got this far (success)
break
}
if err != nil {
return resp, err
}
// if expecting a body, finally decode it
if output != nil {
contentType := parseMediaType(resp)
switch contentType {
case "application/json":
// unmarshal JSON
err = json.Unmarshal(buf.Bytes(), output)
if err != nil {
return resp, fmt.Errorf("JSON-decoding response body: %w", err)
}
default:
// don't interpret anything else here; just hope
// it's a Writer and copy the bytes
w, ok := output.(io.Writer)
if !ok {
return resp, fmt.Errorf("response Content-Type is %s but target container is not io.Writer: %T", contentType, output)
}
_, err = io.Copy(w, buf)
if err != nil {
return resp, err
}
}
}
return resp, nil
}
// doHTTPRequest performs an HTTP request at most one time. It returns the response
// (with drained and closed body), having drained any request body into buf. If
// retry == true is returned, then the request should be safe to retry in the case
// of an error. However, in some cases a retry may be recommended even if part of
// the response body has been read and written into buf. Thus, the buffer may have
// been partially written to and should be reset before being reused.
//
// This method remembers any nonce returned by the server.
func (c *Client) doHTTPRequest(req *http.Request, buf *bytes.Buffer) (resp *http.Response, retry bool, err error) {
req.Header.Set("User-Agent", c.userAgent())
resp, err = c.httpClient().Do(req)
if err != nil {
return resp, true, fmt.Errorf("performing request: %w", err)
}
defer resp.Body.Close()
if c.Logger != nil {
c.Logger.Debug("http request",
zap.String("method", req.Method),
zap.String("url", req.URL.String()),
zap.Reflect("headers", req.Header),
zap.Int("status_code", resp.StatusCode),
zap.Reflect("response_headers", resp.Header))
}
// "The server MUST include a Replay-Nonce header field
// in every successful response to a POST request and
// SHOULD provide it in error responses as well." §6.5
//
// "Before sending a POST request to the server, an ACME
// client needs to have a fresh anti-replay nonce to put
// in the 'nonce' header of the JWS. In most cases, the
// client will have gotten a nonce from a previous
// request." §7.2
//
// So basically, we need to remember the nonces we get
// and use them at the next opportunity.
c.nonces.push(resp.Header.Get(replayNonce))
// drain the response body, even if we aren't keeping it
// (this allows us to reuse the connection and also read
// any error information)
_, err = io.Copy(buf, resp.Body)
if err != nil {
// this is likely a network or I/O error, but is it worth retrying?
// technically the request has already completed, it was just our
// download of the response that failed; so we probably should not
// retry if the request succeeded... however, if there was an HTTP
// error, it likely didn't count against any server-enforced rate
// limits, and we DO want to know the error information, so it should
// be safe to retry the request in those cases AS LONG AS there is
// no request body, which in the context of ACME likely includes an
// anti-replay nonce, which obviously we can't reuse
retry = resp.StatusCode >= 400 && req.Body == nil
return resp, retry, fmt.Errorf("reading response body: %w", err)
}
return resp, false, nil
}
func (c *Client) httpClient() *http.Client {
if c.HTTPClient == nil {
return http.DefaultClient
}
return c.HTTPClient
}
func (c *Client) userAgent() string {
ua := fmt.Sprintf("acmez (%s; %s)", runtime.GOOS, runtime.GOARCH)
if c.UserAgent != "" {
ua = c.UserAgent + " " + ua
}
return ua
}
// extractLinks extracts the URL from the Link header with the
// designated relation rel. It may return more than value
// if there are multiple matching Link values.
//
// Originally by Isaac: https://github.com/eggsampler/acme
// and has been modified to support multiple matching Links.
func extractLinks(resp *http.Response, rel string) []string {
if resp == nil {
return nil
}
var links []string
for _, l := range resp.Header["Link"] {
matches := linkRegex.FindAllStringSubmatch(l, -1)
for _, m := range matches {
if len(m) != 3 {
continue
}
if m[2] == rel {
links = append(links, m[1])
}
}
}
return links
}
// parseMediaType returns only the media type from the
// Content-Type header of resp.
func parseMediaType(resp *http.Response) string {
if resp == nil {
return ""
}
ct := resp.Header.Get("Content-Type")
sep := strings.Index(ct, ";")
if sep < 0 {
return ct
}
return strings.TrimSpace(ct[:sep])
}
// retryAfter returns a duration from the response's Retry-After
// header field, if it exists. It can return an error if the
// header contains an invalid value. If there is no error but
// there is no Retry-After header provided, then the fallback
// duration is returned instead.
func retryAfter(resp *http.Response, fallback time.Duration) (time.Duration, error) {
if resp == nil {
return fallback, nil
}
raSeconds := resp.Header.Get("Retry-After")
if raSeconds == "" {
return fallback, nil
}
ra, err := strconv.Atoi(raSeconds)
if err != nil || ra < 0 {
return 0, fmt.Errorf("response had invalid Retry-After header: %s", raSeconds)
}
return time.Duration(ra) * time.Second, nil
}
var bufPool = sync.Pool{
New: func() interface{} {
return new(bytes.Buffer)
},
}
var linkRegex = regexp.MustCompile(`<(.+?)>;\s*rel="(.+?)"`)