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- // Copyright 2018 Google LLC
- //
- // 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 proxy
-
- import (
- "bytes"
- "encoding/json"
- "errors"
- "fmt"
- "io/ioutil"
- "log"
- "net/http"
- "reflect"
- "sync"
-
- "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
- }
- lg, err := readLog(filename)
- if err != nil {
- return nil, err
- }
- calls, err := constructCalls(lg)
- if err != nil {
- return nil, err
- }
- p.Initial = lg.Initial
- p.mproxy.SetRoundTripper(&replayRoundTripper{
- calls: calls,
- ignoreHeaders: p.ignoreHeaders,
- conv: lg.Converter,
- })
-
- // 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
- }
-
- func readLog(filename string) (*Log, error) {
- bytes, err := ioutil.ReadFile(filename)
- if err != nil {
- return nil, err
- }
- var lg Log
- if err := json.Unmarshal(bytes, &lg); err != nil {
- return nil, fmt.Errorf("%s: %v", filename, err)
- }
- if lg.Version != LogVersion {
- return nil, fmt.Errorf(
- "httpreplay: read log version %s but current version is %s; re-record the log",
- lg.Version, LogVersion)
- }
- return &lg, nil
- }
-
- // A call is an HTTP request and its matching response.
- type call struct {
- req *Request
- res *Response
- }
-
- func constructCalls(lg *Log) ([]*call, error) {
- ignoreIDs := map[string]bool{} // IDs of requests to ignore
- callsByID := map[string]*call{}
- var calls []*call
- for _, e := range lg.Entries {
- if ignoreIDs[e.ID] {
- continue
- }
- c, ok := callsByID[e.ID]
- switch {
- case !ok:
- if e.Request == nil {
- return 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 {
- c := &call{e.Request, e.Response}
- calls = append(calls, c)
- callsByID[e.ID] = c
- }
- case e.Request != nil:
- if e.Response != nil {
- return nil, errors.New("entry has both request and response")
- }
- c.req = e.Request
- case e.Response != nil:
- c.res = e.Response
- default:
- return nil, errors.New("entry has neither request nor response")
- }
- }
- for _, c := range calls {
- if c.req == nil || c.res == nil {
- return nil, fmt.Errorf("missing request or response: %+v", c)
- }
- }
- return calls, nil
- }
-
- type replayRoundTripper struct {
- mu sync.Mutex
- calls []*call
- ignoreHeaders map[string]bool
- conv *Converter
- }
-
- func (r *replayRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
- if req.Body != nil {
- defer req.Body.Close()
- }
- creq, err := r.conv.convertRequest(req)
- if err != nil {
- return nil, err
- }
- r.mu.Lock()
- defer r.mu.Unlock()
- for i, call := range r.calls {
- if call == nil {
- continue
- }
- if requestsMatch(creq, call.req, r.ignoreHeaders) {
- r.calls[i] = nil // nil out this call so we don't reuse it
- return toHTTPResponse(call.res, req), nil
- }
- }
- return nil, fmt.Errorf("no matching request for %+v", req)
- }
-
- // Report whether the incoming request in matches the candidate request cand.
- func requestsMatch(in, cand *Request, ignoreHeaders map[string]bool) bool {
- if in.Method != cand.Method {
- return false
- }
- if in.URL != cand.URL {
- return false
- }
- if in.MediaType != cand.MediaType {
- return false
- }
- if len(in.BodyParts) != len(cand.BodyParts) {
- return false
- }
- for i, p1 := range in.BodyParts {
- if !bytes.Equal(p1, cand.BodyParts[i]) {
- return false
- }
- }
- // Check headers last. See DebugHeaders.
- return headersMatch(in.Header, cand.Header, ignoreHeaders)
- }
-
- // 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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