forked from seborama/govcr
/
cassette.go
513 lines (421 loc) · 12.1 KB
/
cassette.go
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package govcr
import (
"bytes"
"compress/gzip"
"crypto/tls"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"net/url"
"os"
"path/filepath"
"regexp"
"strings"
"sync"
"sync/atomic"
)
// request is a recorded HTTP request.
type request struct {
Method string
URL *url.URL
Header http.Header
Body []byte
}
// Request transforms internal "request" to a filter "Request".
func (r request) Request() Request {
res := Request{
Header: r.Header,
Body: r.Body,
Method: r.Method,
}
if r.URL != nil {
// res.URL = *r.URL
res.URL = *copyURL(r.URL)
}
return res
}
// response is a recorded HTTP response.
type response struct {
Status string
StatusCode int
Proto string
ProtoMajor int
ProtoMinor int
Header http.Header
Body []byte
ContentLength int64
TransferEncoding []string
Trailer http.Header
TLS *tls.ConnectionState
}
// Response returns the internal "response" to a filter "Response".
func (r response) Response(req Request) Response {
return Response{
req: req,
Body: r.Body,
Header: r.Header,
StatusCode: r.StatusCode,
}
}
// track is a recording (HTTP request + response) in a cassette.
type track struct {
Request request
Response response
ErrType string
ErrMsg string
// replayed indicates whether the track has already been processed in the cassette playback.
replayed bool
}
func (t *track) response(req *http.Request) (*http.Response, error) {
var (
err error
resp = &http.Response{}
)
// create a ReadCloser to supply to resp
bodyReadCloser := toReadCloser(t.Response.Body)
// create error object
switch t.ErrType {
case "*net.OpError":
err = &net.OpError{
Op: "govcr",
Net: "govcr",
Source: nil,
Addr: nil,
Err: errors.New(t.ErrType + ": " + t.ErrMsg),
}
case "":
err = nil
default:
err = errors.New(t.ErrType + ": " + t.ErrMsg)
}
if err != nil {
// No need to parse the response.
// By convention, when an HTTP error occurred, the response should be empty
// (or Go's http package will show a warning message at runtime).
return resp, err
}
// re-create the response object from track record
respTLS := t.Response.TLS
resp.Status = t.Response.Status
resp.StatusCode = t.Response.StatusCode
resp.Proto = t.Response.Proto
resp.ProtoMajor = t.Response.ProtoMajor
resp.ProtoMinor = t.Response.ProtoMinor
resp.Header = t.Response.Header
resp.Body = bodyReadCloser
resp.ContentLength = t.Response.ContentLength
resp.TransferEncoding = t.Response.TransferEncoding
resp.Trailer = t.Response.Trailer
// See notes on http.Response.Request - Body is nil because it has already been consumed
resp.Request = copyRequestWithoutBody(req)
resp.TLS = respTLS
return resp, nil
}
// newTrack creates a new track from an HTTP request and response.
func newTrack(req *http.Request, resp *http.Response, reqErr error) (*track, error) {
var (
k7Request request
k7Response response
)
// build request object
if req != nil {
bodyData, err := readRequestBody(req)
if err != nil {
return nil, err
}
k7Request = request{
Method: req.Method,
URL: req.URL,
Header: req.Header,
Body: bodyData,
}
}
// build response object
if resp != nil {
bodyData, err := readResponseBody(resp)
if err != nil {
return nil, err
}
k7Response = response{
Status: resp.Status,
StatusCode: resp.StatusCode,
Proto: resp.Proto,
ProtoMajor: resp.ProtoMajor,
ProtoMinor: resp.ProtoMinor,
Header: resp.Header,
Body: bodyData,
ContentLength: resp.ContentLength,
TransferEncoding: resp.TransferEncoding,
Trailer: resp.Trailer,
TLS: resp.TLS,
}
}
// build track object
var reqErrType, reqErrMsg string
if reqErr != nil {
reqErrType = fmt.Sprintf("%T", reqErr)
reqErrMsg = reqErr.Error()
}
track := &track{
Request: k7Request,
Response: k7Response,
ErrType: reqErrType,
ErrMsg: reqErrMsg,
}
return track, nil
}
// Stats holds information about the cassette and
// VCR runtime.
type Stats struct {
// TracksLoaded is the number of tracks that were loaded from the cassette.
TracksLoaded int32
// TracksRecorded is the number of new tracks recorded by VCR.
TracksRecorded int32
// TracksPlayed is the number of tracks played back straight from the cassette.
// I.e. tracks that were already present on the cassette and were played back.
TracksPlayed int32
}
// cassette contains a set of tracks.
type cassette struct {
Name string
Path string `json:"-"`
Tracks []track
trackSliceMutex *sync.RWMutex
// the following variables are not exported as they are not serialised
tracksLoaded int32
removeTLS bool
}
// newCassette creates a ready to use new cassette.
func newCassette(name string, path string) *cassette {
return &cassette{Name: name, Path: path, trackSliceMutex: &sync.RWMutex{}}
}
// isLongPlay returns true if the cassette content is compressed.
func (k7 *cassette) isLongPlay() bool {
return strings.HasSuffix(k7.Name, ".gz")
}
// TODO - this feels wrong - the cassette should just replay, not replace the track resp.req with the live req
// if it must be done, then it should be done somewhere else, either vcrTransport (or PCB, to be confirmed)
func (k7 *cassette) replayResponse(trackNumber int32, req *http.Request) (*http.Response, error) {
if trackNumber >= k7.NumberOfTracks() {
return nil, nil
}
k7.trackSliceMutex.Lock()
defer k7.trackSliceMutex.Unlock()
track := &k7.Tracks[trackNumber]
// mark the track as replayed so it doesn't get re-used
track.replayed = true
return track.response(req)
}
// saveCassette writes a cassette to file.
func (k7 *cassette) save() error {
k7.trackSliceMutex.Lock()
defer k7.trackSliceMutex.Unlock()
data, err := json.Marshal(k7)
if err != nil {
return err
}
tData, err := transformInterfacesInJSON(data)
if err != nil {
return err
}
var iData bytes.Buffer
if err := json.Indent(&iData, tData, "", " "); err != nil {
return err
}
filename := cassetteNameToFilename(k7.Name, k7.Path)
path := filepath.Dir(filename)
if err := os.MkdirAll(path, 0750); err != nil {
return err
}
gData, err := k7.gzipFilter(iData)
if err != nil {
return err
}
return ioutil.WriteFile(filename, gData, 0640)
}
// gzipFilter compresses the cassette data in gzip format if the cassette
// name ends with '.gz', otherwise data is left as is (i.e. de-compressed)
func (k7 *cassette) gzipFilter(data bytes.Buffer) ([]byte, error) {
if k7.isLongPlay() {
return compress(data.Bytes())
}
return data.Bytes(), nil
}
// gunzipFilter de-compresses the cassette data in gzip format if the cassette
// name ends with '.gz', otherwise data is left as is (i.e. de-compressed)
func (k7 *cassette) gunzipFilter(data []byte) ([]byte, error) {
if k7.isLongPlay() {
return decompress(data)
}
return data, nil
}
// addTrack adds a track to a cassette.
func (k7 *cassette) addTrack(track *track) {
if k7.removeTLS { // TODO: refactor this to be handled by the PCB?
track.Response.TLS = nil
}
k7.trackSliceMutex.Lock()
defer k7.trackSliceMutex.Unlock()
k7.Tracks = append(k7.Tracks, *track)
}
// Track retrieves the requested track number.
// '0' is the first track.
func (k7 *cassette) Track(trackNumber int32) track {
k7.trackSliceMutex.RLock()
defer k7.trackSliceMutex.RUnlock()
return k7.Tracks[trackNumber]
}
// Stats returns the cassette's Stats.
func (k7 *cassette) Stats() Stats {
stats := Stats{}
stats.TracksLoaded = atomic.LoadInt32(&k7.tracksLoaded)
stats.TracksRecorded = k7.NumberOfTracks() - stats.TracksLoaded
stats.TracksPlayed = k7.tracksPlayed() - stats.TracksRecorded
return stats
}
func (k7 *cassette) tracksPlayed() int32 {
replayed := int32(0)
k7.trackSliceMutex.RLock()
defer k7.trackSliceMutex.RUnlock()
for _, t := range k7.Tracks {
if t.replayed {
replayed++
}
}
return replayed
}
func (k7 *cassette) NumberOfTracks() int32 {
k7.trackSliceMutex.RLock()
defer k7.trackSliceMutex.RUnlock()
return int32(len(k7.Tracks))
}
// DeleteCassette removes the cassette file from disk.
func DeleteCassette(cassetteName, cassettePath string) error {
filename := cassetteNameToFilename(cassetteName, cassettePath)
err := os.Remove(filename)
if os.IsNotExist(err) {
// the file does not exist so this is not an error since we wanted it gone!
err = nil
}
return err
}
// CassetteExistsAndValid verifies a cassette file exists and is seemingly valid.
func CassetteExistsAndValid(cassetteName, cassettePath string) bool {
_, err := readCassetteFromFile(cassetteName, cassettePath)
return err == nil
}
// cassetteNameToFilename returns the filename associated to the cassette.
func cassetteNameToFilename(cassetteName, cassettePath string) string {
if cassetteName == "" || cassetteName == ".gz" {
return ""
}
if cassettePath == "" {
cassettePath = defaultCassettePath
}
fPath, err := filepath.Abs(filepath.Join(cassettePath, adjustCassetteName(cassetteName)))
if err != nil {
log.Fatal(err)
}
return fPath
}
// adjustCassetteName moves the '.gz' suffix to the end of the cassette name
// instead of the middle
func adjustCassetteName(cassetteName string) string {
if strings.HasSuffix(cassetteName, ".gz") {
return strings.TrimSuffix(cassetteName, ".gz") + ".cassette.gz"
}
return cassetteName + ".cassette"
}
// transformInterfacesInJSON looks for known properties in the JSON that are defined as interface{}
// in their original Go structure and don't Unmarshal correctly.
//
// Example x509.Certificate.PublicKey:
// When the type is rsa.PublicKey, Unmarshal attempts to map property "N" to a float64 because it is a number.
// However, it really is a big.Int which does not fit float64 and makes Unmarshal fail.
//
// This is not an ideal solution but it works. In the future, we could consider adding a property that
// records the original type and re-creates it post Unmarshal.
func transformInterfacesInJSON(jsonString []byte) ([]byte, error) {
// TODO: precompile this regexp perhaps via a receiver
regex, err := regexp.Compile(`("PublicKey":{"N":)([0-9]+),`)
if err != nil {
return []byte{}, err
}
return []byte(regex.ReplaceAllString(string(jsonString), `$1"$2",`)), nil
}
func loadCassette(cassetteName, cassettePath string) (*cassette, error) {
k7, err := readCassetteFromFile(cassetteName, cassettePath)
if err != nil {
return nil, err
}
// provide an empty cassette as a minimum
if k7 == nil {
k7 = newCassette(cassetteName, cassettePath)
}
// initial stats
k7.tracksLoaded = k7.NumberOfTracks()
return k7, nil
}
// readCassetteFromFile reads the cassette file, if present.
func readCassetteFromFile(cassetteName, cassettePath string) (*cassette, error) {
filename := cassetteNameToFilename(cassetteName, cassettePath)
k7 := newCassette(cassetteName, cassettePath)
data, err := ioutil.ReadFile(filename)
if os.IsNotExist(err) {
return k7, nil
} else if err != nil {
return nil, err
}
cData, err := k7.gunzipFilter(data)
if err != nil {
return nil, err
}
// NOTE: Properties which are of type 'interface{}' are not handled very well
if err := json.Unmarshal(cData, k7); err != nil {
return nil, err
}
return k7, nil
}
// recordNewTrackToCassette saves a new track to a cassette.
func recordNewTrackToCassette(cassette *cassette, req *http.Request, resp *http.Response, httpErr error) error {
// create track
track, err := newTrack(req, resp, httpErr)
if err != nil {
return err
}
// mark track as replayed since it's coming from a live request!
track.replayed = true
// add track to cassette
cassette.addTrack(track)
// save cassette
return cassette.save()
}
// compress data and return the result
func compress(data []byte) ([]byte, error) {
var out bytes.Buffer
w := gzip.NewWriter(&out)
if _, err := io.Copy(w, bytes.NewBuffer(data)); err != nil {
return nil, err
}
if err := w.Close(); err != nil {
return nil, err
}
return out.Bytes(), nil
}
// decompress data and return the result
func decompress(data []byte) ([]byte, error) {
r, err := gzip.NewReader(bytes.NewBuffer(data))
if err != nil {
return nil, err
}
data, err = ioutil.ReadAll(r)
if err != nil {
return nil, err
}
return data, nil
}