360 lines
9.1 KiB
Go
360 lines
9.1 KiB
Go
// checkpoint is a package for checking version information and alerts
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// for a HashiCorp product.
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package checkpoint
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import (
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"crypto/rand"
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"encoding/binary"
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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mrand "math/rand"
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"net/http"
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"net/url"
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"os"
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"path/filepath"
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"reflect"
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"runtime"
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"strings"
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"time"
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"github.com/hashicorp/go-cleanhttp"
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)
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var magicBytes [4]byte = [4]byte{0x35, 0x77, 0x69, 0xFB}
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// CheckParams are the parameters for configuring a check request.
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type CheckParams struct {
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// Product and version are used to lookup the correct product and
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// alerts for the proper version. The version is also used to perform
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// a version check.
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Product string
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Version string
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// Arch and OS are used to filter alerts potentially only to things
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// affecting a specific os/arch combination. If these aren't specified,
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// they'll be automatically filled in.
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Arch string
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OS string
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// Signature is some random signature that should be stored and used
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// as a cookie-like value. This ensures that alerts aren't repeated.
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// If the signature is changed, repeat alerts may be sent down. The
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// signature should NOT be anything identifiable to a user (such as
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// a MAC address). It should be random.
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//
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// If SignatureFile is given, then the signature will be read from this
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// file. If the file doesn't exist, then a random signature will
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// automatically be generated and stored here. SignatureFile will be
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// ignored if Signature is given.
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Signature string
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SignatureFile string
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// CacheFile, if specified, will cache the result of a check. The
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// duration of the cache is specified by CacheDuration, and defaults
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// to 48 hours if not specified. If the CacheFile is newer than the
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// CacheDuration, than the Check will short-circuit and use those
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// results.
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//
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// If the CacheFile directory doesn't exist, it will be created with
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// permissions 0755.
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CacheFile string
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CacheDuration time.Duration
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// Force, if true, will force the check even if CHECKPOINT_DISABLE
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// is set. Within HashiCorp products, this is ONLY USED when the user
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// specifically requests it. This is never automatically done without
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// the user's consent.
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Force bool
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}
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// CheckResponse is the response for a check request.
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type CheckResponse struct {
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Product string
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CurrentVersion string `json:"current_version"`
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CurrentReleaseDate int `json:"current_release_date"`
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CurrentDownloadURL string `json:"current_download_url"`
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CurrentChangelogURL string `json:"current_changelog_url"`
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ProjectWebsite string `json:"project_website"`
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Outdated bool `json:"outdated"`
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Alerts []*CheckAlert
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}
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// CheckAlert is a single alert message from a check request.
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//
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// These never have to be manually constructed, and are typically populated
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// into a CheckResponse as a result of the Check request.
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type CheckAlert struct {
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ID int
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Date int
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Message string
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URL string
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Level string
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}
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// Check checks for alerts and new version information.
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func Check(p *CheckParams) (*CheckResponse, error) {
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if disabled := os.Getenv("CHECKPOINT_DISABLE"); disabled != "" && !p.Force {
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return &CheckResponse{}, nil
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}
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// If we have a cached result, then use that
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if r, err := checkCache(p.Version, p.CacheFile, p.CacheDuration); err != nil {
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return nil, err
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} else if r != nil {
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defer r.Close()
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return checkResult(r)
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}
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var u url.URL
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if p.Arch == "" {
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p.Arch = runtime.GOARCH
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}
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if p.OS == "" {
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p.OS = runtime.GOOS
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}
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// If we're given a SignatureFile, then attempt to read that.
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signature := p.Signature
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if p.Signature == "" && p.SignatureFile != "" {
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var err error
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signature, err = checkSignature(p.SignatureFile)
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if err != nil {
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return nil, err
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}
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}
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v := u.Query()
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v.Set("version", p.Version)
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v.Set("arch", p.Arch)
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v.Set("os", p.OS)
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v.Set("signature", signature)
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u.Scheme = "https"
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u.Host = "checkpoint-api.hashicorp.com"
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u.Path = fmt.Sprintf("/v1/check/%s", p.Product)
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u.RawQuery = v.Encode()
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req, err := http.NewRequest("GET", u.String(), nil)
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if err != nil {
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return nil, err
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}
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req.Header.Add("Accept", "application/json")
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req.Header.Add("User-Agent", "HashiCorp/go-checkpoint")
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client := cleanhttp.DefaultClient()
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resp, err := client.Do(req)
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != 200 {
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return nil, fmt.Errorf("Unknown status: %d", resp.StatusCode)
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}
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var r io.Reader = resp.Body
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if p.CacheFile != "" {
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// Make sure the directory holding our cache exists.
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if err := os.MkdirAll(filepath.Dir(p.CacheFile), 0755); err != nil {
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return nil, err
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}
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// We have to cache the result, so write the response to the
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// file as we read it.
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f, err := os.Create(p.CacheFile)
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if err != nil {
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return nil, err
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}
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// Write the cache header
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if err := writeCacheHeader(f, p.Version); err != nil {
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f.Close()
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os.Remove(p.CacheFile)
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return nil, err
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}
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defer f.Close()
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r = io.TeeReader(r, f)
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}
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return checkResult(r)
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}
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// CheckInterval is used to check for a response on a given interval duration.
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// The interval is not exact, and checks are randomized to prevent a thundering
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// herd. However, it is expected that on average one check is performed per
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// interval. The returned channel may be closed to stop background checks.
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func CheckInterval(p *CheckParams, interval time.Duration, cb func(*CheckResponse, error)) chan struct{} {
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doneCh := make(chan struct{})
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if disabled := os.Getenv("CHECKPOINT_DISABLE"); disabled != "" {
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return doneCh
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}
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go func() {
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for {
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select {
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case <-time.After(randomStagger(interval)):
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resp, err := Check(p)
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cb(resp, err)
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case <-doneCh:
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return
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}
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}
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}()
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return doneCh
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}
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// randomStagger returns an interval that is between 3/4 and 5/4 of
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// the given interval. The expected value is the interval.
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func randomStagger(interval time.Duration) time.Duration {
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stagger := time.Duration(mrand.Int63()) % (interval / 2)
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return 3*(interval/4) + stagger
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}
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func checkCache(current string, path string, d time.Duration) (io.ReadCloser, error) {
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fi, err := os.Stat(path)
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if err != nil {
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if os.IsNotExist(err) {
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// File doesn't exist, not a problem
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return nil, nil
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}
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return nil, err
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}
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if d == 0 {
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d = 48 * time.Hour
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}
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if fi.ModTime().Add(d).Before(time.Now()) {
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// Cache is busted, delete the old file and re-request. We ignore
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// errors here because re-creating the file is fine too.
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os.Remove(path)
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return nil, nil
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}
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// File looks good so far, open it up so we can inspect the contents.
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f, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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// Check the signature of the file
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var sig [4]byte
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if err := binary.Read(f, binary.LittleEndian, sig[:]); err != nil {
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f.Close()
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return nil, err
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}
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if !reflect.DeepEqual(sig, magicBytes) {
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// Signatures don't match. Reset.
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f.Close()
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return nil, nil
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}
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// Check the version. If it changed, then rewrite
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var length uint32
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if err := binary.Read(f, binary.LittleEndian, &length); err != nil {
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f.Close()
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return nil, err
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}
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data := make([]byte, length)
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if _, err := io.ReadFull(f, data); err != nil {
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f.Close()
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return nil, err
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}
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if string(data) != current {
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// Version changed, reset
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f.Close()
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return nil, nil
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}
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return f, nil
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}
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func checkResult(r io.Reader) (*CheckResponse, error) {
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var result CheckResponse
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dec := json.NewDecoder(r)
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if err := dec.Decode(&result); err != nil {
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return nil, err
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}
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return &result, nil
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}
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func checkSignature(path string) (string, error) {
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_, err := os.Stat(path)
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if err == nil {
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// The file exists, read it out
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sigBytes, err := ioutil.ReadFile(path)
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if err != nil {
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return "", err
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}
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// Split the file into lines
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lines := strings.SplitN(string(sigBytes), "\n", 2)
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if len(lines) > 0 {
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return strings.TrimSpace(lines[0]), nil
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}
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}
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// If this isn't a non-exist error, then return that.
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if !os.IsNotExist(err) {
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return "", err
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}
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// The file doesn't exist, so create a signature.
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var b [16]byte
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n := 0
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for n < 16 {
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n2, err := rand.Read(b[n:])
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if err != nil {
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return "", err
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}
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n += n2
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}
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signature := fmt.Sprintf(
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"%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
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// Make sure the directory holding our signature exists.
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if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
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return "", err
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}
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// Write the signature
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if err := ioutil.WriteFile(path, []byte(signature+"\n\n"+userMessage+"\n"), 0644); err != nil {
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return "", err
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}
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return signature, nil
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}
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func writeCacheHeader(f io.Writer, v string) error {
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// Write our signature first
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if err := binary.Write(f, binary.LittleEndian, magicBytes); err != nil {
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return err
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}
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// Write out our current version length
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var length uint32 = uint32(len(v))
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if err := binary.Write(f, binary.LittleEndian, length); err != nil {
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return err
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}
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_, err := f.Write([]byte(v))
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return err
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}
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// userMessage is suffixed to the signature file to provide feedback.
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var userMessage = `
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This signature is a randomly generated UUID used to de-duplicate
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alerts and version information. This signature is random, it is
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not based on any personally identifiable information. To create
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a new signature, you can simply delete this file at any time.
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See the documentation for the software using Checkpoint for more
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information on how to disable it.
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`
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