Current File : //home/waritko/go/src/cloud.google.com/go/httpreplay/internal/proxy/replay.go
// Copyright 2018 Google Inc. All Rights Reserved.
//
// 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.
// +build go1.8
package proxy
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"log"
"mime"
"mime/multipart"
"net/http"
"reflect"
"strings"
"github.com/google/martian/har"
"github.com/google/martian/martianlog"
)
// ForReplaying returns a Proxy configured to replay.
func ForReplaying(filename string, port int) (*Proxy, error) {
p, err := newProxy(filename)
if err != nil {
return nil, err
}
calls, initial, err := readLog(filename)
if err != nil {
return nil, err
}
p.mproxy.SetRoundTripper(replayRoundTripper{calls: calls})
p.Initial = initial
// Debug logging.
// TODO(jba): factor out from here and ForRecording.
logger := martianlog.NewLogger()
logger.SetDecode(true)
p.mproxy.SetRequestModifier(logger)
p.mproxy.SetResponseModifier(logger)
if err := p.start(port); err != nil {
return nil, err
}
return p, nil
}
// A call is an HTTP request and its matching response.
type call struct {
req *har.Request
reqBody *requestBody // parsed request body
res *har.Response
}
func readLog(filename string) ([]*call, []byte, error) {
bytes, err := ioutil.ReadFile(filename)
if err != nil {
return nil, nil, err
}
var f httprFile
if err := json.Unmarshal(bytes, &f); err != nil {
return nil, nil, err
}
ignoreIDs := map[string]bool{} // IDs of requests to ignore
callsByID := map[string]*call{}
var calls []*call
for _, e := range f.HAR.Log.Entries {
if ignoreIDs[e.ID] {
continue
}
c, ok := callsByID[e.ID]
switch {
case !ok:
if e.Request == nil {
return nil, nil, fmt.Errorf("first entry for ID %s does not have a request", e.ID)
}
if e.Request.Method == "CONNECT" {
// Ignore CONNECT methods.
ignoreIDs[e.ID] = true
} else {
reqBody, err := newRequestBodyFromHAR(e.Request)
if err != nil {
return nil, nil, err
}
c := &call{e.Request, reqBody, e.Response}
calls = append(calls, c)
callsByID[e.ID] = c
}
case e.Request != nil:
if e.Response != nil {
return nil, nil, errors.New("HAR entry has both request and response")
}
c.req = e.Request
case e.Response != nil:
c.res = e.Response
default:
return nil, nil, errors.New("HAR entry has neither request nor response")
}
}
for _, c := range calls {
if c.req == nil || c.res == nil {
return nil, nil, fmt.Errorf("missing request or response: %+v", c)
}
}
return calls, f.Initial, nil
}
type replayRoundTripper struct {
calls []*call
}
func (r replayRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
reqBody, err := newRequestBodyFromHTTP(req)
if err != nil {
return nil, err
}
for i, call := range r.calls {
if call == nil {
continue
}
if requestsMatch(req, reqBody, call.req, call.reqBody) {
r.calls[i] = nil // nil out this call so we don't reuse it
res := harResponseToHTTPResponse(call.res)
res.Request = req
return res, nil
}
}
return nil, fmt.Errorf("no matching request for %+v", req)
}
// Headers that shouldn't be compared, becuase they may differ on different executions
// of the same code, or may not be present during record or replay.
var ignoreHeaders = map[string]bool{}
func init() {
// Sensitive headers are redacted in the log, so they won't be equal to incoming values.
for _, h := range sensitiveHeaders {
ignoreHeaders[h] = true
}
for _, h := range []string{
"Content-Type", // handled by requestBody
"Date",
"Host",
"Transfer-Encoding",
"Via",
"X-Forwarded-For",
"X-Forwarded-Host",
"X-Forwarded-Proto",
"X-Forwarded-Url",
} {
ignoreHeaders[h] = true
}
}
// Report whether the incoming request in matches the candidate request cand.
func requestsMatch(in *http.Request, inBody *requestBody, cand *har.Request, candBody *requestBody) bool {
// TODO(jba): compare headers?
if in.Method != cand.Method {
return false
}
if in.URL.String() != cand.URL {
return false
}
if !inBody.equal(candBody) {
return false
}
// Check headers last. See DebugHeaders.
return headersMatch(in.Header, harHeadersToHTTP(cand.Headers), ignoreHeaders)
}
func harHeadersToHTTP(hhs []har.Header) http.Header {
// Unfortunately, the har package joins multiple header values with ", ",
// which isn't reversible if any of the values contains a comma.
// We hope for the best.
res := http.Header{}
for _, hh := range hhs {
res[hh.Name] = strings.Split(hh.Value, ", ")
}
return res
}
// Convert a HAR response to a Go http.Response.
// HAR (Http ARchive) is a standard for storing HTTP interactions.
// See http://www.softwareishard.com/blog/har-12-spec.
func harResponseToHTTPResponse(hr *har.Response) *http.Response {
return &http.Response{
StatusCode: hr.Status,
Status: hr.StatusText,
Proto: hr.HTTPVersion,
// TODO(jba): headers?
Body: ioutil.NopCloser(bytes.NewReader(hr.Content.Text)),
ContentLength: int64(len(hr.Content.Text)),
}
}
// A requestBody represents the body of a request. If the content type is multipart, the
// body is split into parts.
//
// The replaying proxy needs to understand multipart bodies because the boundaries are
// generated randomly, so we can't just compare the entire bodies for equality.
type requestBody struct {
mediaType string // the media type part of the Content-Type header
parts [][]byte // the parts of the body, or just a single []byte if not multipart
}
func newRequestBodyFromHTTP(req *http.Request) (*requestBody, error) {
defer req.Body.Close()
return newRequestBody(req.Header.Get("Content-Type"), req.Body)
}
func newRequestBodyFromHAR(req *har.Request) (*requestBody, error) {
if req.PostData == nil {
return nil, nil
}
var cth string
for _, h := range req.Headers {
if h.Name == "Content-Type" {
cth = h.Value
break
}
}
return newRequestBody(cth, strings.NewReader(req.PostData.Text))
}
// newRequestBody parses the Content-Type header, reads the body, and splits it into
// parts if necessary.
func newRequestBody(contentType string, body io.Reader) (*requestBody, error) {
if contentType == "" {
// No content-type header. There should not be a body.
if _, err := body.Read(make([]byte, 1)); err != io.EOF {
return nil, errors.New("no Content-Type, but body")
}
return nil, nil
}
mediaType, params, err := mime.ParseMediaType(contentType)
if err != nil {
return nil, err
}
rb := &requestBody{mediaType: mediaType}
if strings.HasPrefix(mediaType, "multipart/") {
mr := multipart.NewReader(body, params["boundary"])
for {
p, err := mr.NextPart()
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
part, err := ioutil.ReadAll(p)
if err != nil {
return nil, err
}
// TODO(jba): care about part headers?
rb.parts = append(rb.parts, part)
}
} else {
bytes, err := ioutil.ReadAll(body)
if err != nil {
return nil, err
}
rb.parts = [][]byte{bytes}
}
return rb, nil
}
func (r1 *requestBody) equal(r2 *requestBody) bool {
if r1 == nil || r2 == nil {
return r1 == r2
}
if r1.mediaType != r2.mediaType {
return false
}
if len(r1.parts) != len(r2.parts) {
return false
}
for i, p1 := range r1.parts {
if !bytes.Equal(p1, r2.parts[i]) {
return false
}
}
return true
}
// DebugHeaders helps to determine whether a header should be ignored.
// When true, if requests have the same method, URL and body but differ
// in a header, the first mismatched header is logged.
var DebugHeaders = false
func headersMatch(in, cand http.Header, ignores map[string]bool) bool {
for k1, v1 := range in {
if ignores[k1] {
continue
}
v2 := cand[k1]
if v2 == nil {
if DebugHeaders {
log.Printf("header %s: present in incoming request but not candidate", k1)
}
return false
}
if !reflect.DeepEqual(v1, v2) {
if DebugHeaders {
log.Printf("header %s: incoming %v, candidate %v", k1, v1, v2)
}
return false
}
}
for k2 := range cand {
if ignores[k2] {
continue
}
if in[k2] == nil {
if DebugHeaders {
log.Printf("header %s: not in incoming request but present in candidate", k2)
}
return false
}
}
return true
}
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