blob: f3ab456ec0cc1c389b733869faf8bbdb14a5a603 [file] [log] [blame]
// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package proxy
import (
// Replacement for the HAR logging that comes with martian. HAR is not designed for
// replay. In particular, response bodies are interpreted (e.g. decompressed), and we
// just want them to be stored literally. This isn't something we can fix in martian: it
// is required in the HAR spec (
// LogVersion is the current version of the log format. It can be used to
// support changes to the format over time, so newer code can read older files.
const LogVersion = "0.2"
// A Log is a record of HTTP interactions, suitable for replay. It can be serialized to JSON.
type Log struct {
Initial []byte // initial data for replay
Version string // version of this log format
Converter *Converter
Entries []*Entry
// An Entry single request-response pair.
type Entry struct {
ID string // unique ID
Request *Request
Response *Response
// A Request represents an http.Request in the log.
type Request struct {
Method string // http.Request.Method
URL string // http.Request.URL, as a string
Header http.Header // http.Request.Header
// We need to understand multipart bodies because the boundaries are
// generated randomly, so we can't just compare the entire bodies for equality.
MediaType string // the media type part of the Content-Type header
BodyParts [][]byte // http.Request.Body, read to completion and split for multipart
Trailer http.Header `json:",omitempty"` // http.Request.Trailer
// A Response represents an http.Response in the log.
type Response struct {
StatusCode int // http.Response.StatusCode
Proto string // http.Response.Proto
ProtoMajor int // http.Response.ProtoMajor
ProtoMinor int // http.Response.ProtoMinor
Header http.Header // http.Response.Header
Body []byte // http.Response.Body, read to completion
Trailer http.Header `json:",omitempty"` // http.Response.Trailer
// A Logger maintains a request-response log.
type Logger struct {
mu sync.Mutex
entries map[string]*Entry // from ID
log *Log
// newLogger creates a new logger.
func newLogger() *Logger {
return &Logger{
log: &Log{
Version: LogVersion,
Converter: defaultConverter(),
entries: map[string]*Entry{},
// ModifyRequest logs requests.
func (l *Logger) ModifyRequest(req *http.Request) error {
if req.Method == "CONNECT" {
return nil
ctx := martian.NewContext(req)
if ctx.SkippingLogging() {
return nil
lreq, err := l.log.Converter.convertRequest(req)
if err != nil {
return err
id := ctx.ID()
entry := &Entry{ID: id, Request: lreq}
if _, ok := l.entries[id]; ok {
panic(fmt.Sprintf("proxy: duplicate request ID: %s", id))
l.entries[id] = entry
l.log.Entries = append(l.log.Entries, entry)
return nil
// ModifyResponse logs responses.
func (l *Logger) ModifyResponse(res *http.Response) error {
ctx := martian.NewContext(res.Request)
if ctx.SkippingLogging() {
return nil
id := ctx.ID()
lres, err := l.log.Converter.convertResponse(res)
if err != nil {
return err
if e, ok := l.entries[id]; ok {
e.Response = lres
// Ignore the response if we haven't seen the request.
return nil
// Extract returns the Log and removes it. The Logger is not usable
// after this call.
func (l *Logger) Extract() *Log {
r := l.log
l.log = nil
l.entries = nil
return r
func toHTTPResponse(lr *Response, req *http.Request) *http.Response {
res := &http.Response{
StatusCode: lr.StatusCode,
Proto: lr.Proto,
ProtoMajor: lr.ProtoMajor,
ProtoMinor: lr.ProtoMinor,
Header: lr.Header,
Body: ioutil.NopCloser(bytes.NewReader(lr.Body)),
ContentLength: int64(len(lr.Body)),
res.Request = req
// For HEAD, set ContentLength to the value of the Content-Length header, or -1
// if there isn't one.
if req.Method == "HEAD" {
res.ContentLength = -1
if c := res.Header["Content-Length"]; len(c) == 1 {
if c64, err := strconv.ParseInt(c[0], 10, 64); err == nil {
res.ContentLength = c64
return res