mirror of
https://github.com/go-gitea/gitea.git
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241 lines
6.5 KiB
Go
241 lines
6.5 KiB
Go
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// Copyright 2020 Matthew Holt
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package acme full implements the ACME protocol specification as
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// described in RFC 8555: https://tools.ietf.org/html/rfc8555.
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//
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// It is designed to work smoothly in large-scale deployments with
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// high resilience to errors and intermittent network or server issues,
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// with retries built-in at every layer of the HTTP request stack.
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//
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// NOTE: This is a low-level API. Most users will want the mholt/acmez
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// package which is more concerned with configuring challenges and
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// implementing the order flow. However, using this package directly
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// is recommended for advanced use cases having niche requirements.
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// See the examples in the examples/plumbing folder for a tutorial.
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package acme
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import (
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"context"
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"fmt"
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"net/http"
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"sync"
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"time"
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"go.uber.org/zap"
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)
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// Client facilitates ACME client operations as defined by the spec.
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//
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// Because the client is synchronized for concurrent use, it should
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// not be copied.
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//
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// Many errors that are returned by a Client are likely to be of type
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// Problem as long as the ACME server returns a structured error
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// response. This package wraps errors that may be of type Problem,
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// so you can access the details using the conventional Go pattern:
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//
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// var problem Problem
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// if errors.As(err, &problem) {
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// log.Printf("Houston, we have a problem: %+v", problem)
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// }
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//
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// All Problem errors originate from the ACME server.
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type Client struct {
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// The ACME server's directory endpoint.
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Directory string
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// Custom HTTP client.
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HTTPClient *http.Client
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// Augmentation of the User-Agent header. Please set
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// this so that CAs can troubleshoot bugs more easily.
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UserAgent string
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// Delay between poll attempts. Only used if server
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// does not supply a Retry-Afer header. Default: 250ms
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PollInterval time.Duration
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// Maximum duration for polling. Default: 5m
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PollTimeout time.Duration
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// An optional logger. Default: no logs
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Logger *zap.Logger
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mu sync.Mutex // protects all unexported fields
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dir Directory
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nonces *stack
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}
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// GetDirectory retrieves the directory configured at c.Directory. It is
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// NOT necessary to call this to provision the client. It is only useful
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// if you want to access a copy of the directory yourself.
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func (c *Client) GetDirectory(ctx context.Context) (Directory, error) {
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if err := c.provision(ctx); err != nil {
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return Directory{}, err
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}
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return c.dir, nil
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}
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func (c *Client) provision(ctx context.Context) error {
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c.mu.Lock()
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defer c.mu.Unlock()
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if c.nonces == nil {
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c.nonces = new(stack)
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}
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err := c.provisionDirectory(ctx)
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if err != nil {
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return fmt.Errorf("provisioning client: %w", err)
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}
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return nil
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}
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func (c *Client) provisionDirectory(ctx context.Context) error {
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// don't get directory again if we already have it;
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// checking any one of the required fields will do
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if c.dir.NewNonce != "" {
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return nil
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}
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if c.Directory == "" {
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return fmt.Errorf("missing directory URL")
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}
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// prefer cached version if it's recent enough
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directoriesMu.Lock()
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defer directoriesMu.Unlock()
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if dir, ok := directories[c.Directory]; ok {
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if time.Since(dir.retrieved) < 12*time.Hour {
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c.dir = dir.Directory
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return nil
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}
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}
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_, err := c.httpReq(ctx, http.MethodGet, c.Directory, nil, &c.dir)
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if err != nil {
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return err
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}
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directories[c.Directory] = cachedDirectory{c.dir, time.Now()}
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return nil
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}
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func (c *Client) nonce(ctx context.Context) (string, error) {
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nonce := c.nonces.pop()
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if nonce != "" {
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return nonce, nil
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}
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if c.dir.NewNonce == "" {
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return "", fmt.Errorf("directory missing newNonce endpoint")
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}
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resp, err := c.httpReq(ctx, http.MethodHead, c.dir.NewNonce, nil, nil)
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if err != nil {
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return "", fmt.Errorf("fetching new nonce from server: %w", err)
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}
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return resp.Header.Get(replayNonce), nil
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}
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func (c *Client) pollInterval() time.Duration {
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if c.PollInterval == 0 {
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return defaultPollInterval
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}
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return c.PollInterval
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}
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func (c *Client) pollTimeout() time.Duration {
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if c.PollTimeout == 0 {
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return defaultPollTimeout
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}
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return c.PollTimeout
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}
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// Directory acts as an index for the ACME server as
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// specified in the spec: "In order to help clients
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// configure themselves with the right URLs for each
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// ACME operation, ACME servers provide a directory
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// object." §7.1.1
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type Directory struct {
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NewNonce string `json:"newNonce"`
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NewAccount string `json:"newAccount"`
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NewOrder string `json:"newOrder"`
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NewAuthz string `json:"newAuthz,omitempty"`
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RevokeCert string `json:"revokeCert"`
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KeyChange string `json:"keyChange"`
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Meta *DirectoryMeta `json:"meta,omitempty"`
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}
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// DirectoryMeta is optional extra data that may be
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// included in an ACME server directory. §7.1.1
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type DirectoryMeta struct {
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TermsOfService string `json:"termsOfService,omitempty"`
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Website string `json:"website,omitempty"`
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CAAIdentities []string `json:"caaIdentities,omitempty"`
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ExternalAccountRequired bool `json:"externalAccountRequired,omitempty"`
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}
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// stack is a simple thread-safe stack.
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type stack struct {
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stack []string
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stackMu sync.Mutex
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}
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func (s *stack) push(v string) {
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if v == "" {
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return
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}
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s.stackMu.Lock()
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defer s.stackMu.Unlock()
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if len(s.stack) >= 64 {
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return
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}
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s.stack = append(s.stack, v)
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}
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func (s *stack) pop() string {
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s.stackMu.Lock()
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defer s.stackMu.Unlock()
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n := len(s.stack)
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if n == 0 {
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return ""
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}
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v := s.stack[n-1]
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s.stack = s.stack[:n-1]
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return v
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}
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// Directories seldom (if ever) change in practice, and
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// client structs are often ephemeral, so we can cache
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// directories to speed things up a bit for the user.
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// Keyed by directory URL.
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var (
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directories = make(map[string]cachedDirectory)
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directoriesMu sync.Mutex
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)
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type cachedDirectory struct {
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Directory
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retrieved time.Time
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}
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// replayNonce is the header field that contains a new
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// anti-replay nonce from the server.
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const replayNonce = "Replay-Nonce"
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const (
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defaultPollInterval = 250 * time.Millisecond
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defaultPollTimeout = 5 * time.Minute
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)
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