martian

README

Martian Proxy

Martian Proxy is a programmable HTTP proxy designed to be used for testing.

Martian is a great tool to use if you want to:

• Verify that all (or some subset) of requests are secure
• Mock external services at the network layer
• Inject headers, modify cookies or perform other mutations of HTTP requests and responses
• Verify that pingbacks happen when you think they should
• Unwrap encrypted traffic (requires install of CA certificate in browser)

By taking advantage of Go cross-compilation, Martian can be deployed anywhere that Go can target.

Requirements

Go 1.9

Getting Started

Installation

Martian Proxy can be installed using go install

go get github.com/google/martian/ && \
go install github.com/google/martian/cmd/proxy

Start the Proxy

Assuming you've installed Martian, running the proxy is as simple as

$GOPATH/bin/proxy

If you want to see system logs as Martian is running, pass in the verbosity flag:

$GOPATH/bin/proxy -v=2

By default, Martian will be running on port 8080, and the Martian API will be running on 8181 . The port can be specified via flags:

$GOPATH/bin/proxy -addr=:9999 -api-addr=:9898

Logging

For logging of requests and responses a logging modifier is available or HAR logs are available if the -har flag is used.

HAR Logging

To enable HAR logging in Martian call the binary with the -har flag:

$GOPATH/bin/proxy -har

If the -har flag has been enabled two HAR related endpoints will be available:

GET http://martian.proxy/logs

Will retrieve the HAR log of all requests and responses seen by the proxy since the last reset.

DELETE http://martian.proxy/logs/reset

Will reset the in-memory HAR log. Note that the log will grow unbounded unless it is periodically reset.

Configure

Once Martian is running, you need to configure its behavior. Without configuration, Martian is just proxying without doing anything to the requests or responses. If enabled, logging will take place without additional configuration.

Martian is configured by JSON messages sent over HTTP that take the general form of:

{
  "header.Modifier": {
    "scope": ["response"],
    "name": "Test-Header",
    "value": "true"
  }
}

The above configuration tells Martian to inject a header with the name "Test-Header" and the value "true" on all responses.

Let's break down the parts of this message.

• [package.Type]: The package.Type of the modifier that you want to use. In this case, it's "header.Modifier", which is the name of the modifier that sets headers (to learn more about the header.Modifier, please refer to the modifier reference).

• [package.Type].scope: Indicates whether to apply to the modifier to requests, responses or both. This can be an array containing "request", "response", or both.

• [package.Type].[key]: Modifier specific data. In the case of the header modifier, we need the name and value of the header.

This is a simple configuration, for more complex configurations, modifiers are combined with groups and filters to compose the desired behavior.

To configure Martian, POST the JSON to http://martian.proxy/modifiers. You'll want to use whatever mechanism your language of choice provides you to make HTTP requests, but for demo purposes, curl works (assuming your configuration is in a file called modifier.json).

    curl -x localhost:8080 \
         -X POST \
         -H "Content-Type: application/json" \
         -d @modifier.json \
            "http://martian.proxy/configure"

Intercepting HTTPS Requests and Responses

Martian supports modifying HTTPS requests and responses if configured to do so.

In order for Martian to intercept HTTPS traffic a custom CA certificate must be installed in the browser so that connection warnings are not shown.

The easiest way to install the CA certificate is to start the proxy with the necessary flags to use a custom CA certificate and private key using the -cert and -key flags, or to have the proxy generate one using the -generate-ca-cert flag.

After the proxy has started, visit http://martian.proxy/authority.cer in the browser configured to use the proxy and a prompt will be displayed to install the certificate.

Several flags are available in examples/main.go to help configure MITM functionality:

-key=""
  PEM encoded private key file of the CA certificate provided in -cert; used
  to sign certificates that are generated on-the-fly
-cert=""
  PEM encoded CA certificate file used to generate certificates
-generate-ca-cert=false
  generates a CA certificate and private key to use for man-in-the-middle;
  most users choosing this option will immediately visit
  http://martian.proxy/authority.cer in the browser whose traffic is to be
  intercepted to install the newly generated CA certificate
-organization="Martian Proxy"
  organization name set on the dynamically-generated certificates during
  man-in-the-middle
-validity="1h"
  window of time around the time of request that the dynamically-generated
  certificate is valid for; the duration is set such that the total valid
  timeframe is double the value of validity (1h before & 1h after)

Check Verifiers

Let's assume that you've configured Martian to verify the presence a specific header in responses to a specific URL.

Here's a configuration to verify that all requests to example.com return responses with a 200 OK.

      {
        "url.Filter": {
          "scope": ["request", "response"],
          "host" : "example.com",
          "modifier" : {
            "status.Verifier": {
              "scope" : ["response"],
              "statusCode": 200
            }
          }
        }
      }

Once Martian is running, configured and the requests and resultant responses you wish to verify have taken place, you can verify your expectation that you only got back 200 OK responses.

To check verifications, perform

GET http://martian.proxy/verify

Failed expectations are tracked as errors, and the list of errors are retrieved by making a GET request to host:port/martian/verify, which will return a list of errors:

  {
      "errors" : [
          {
              "message": "response(http://example.com) status code verify failure: got 500, want 200"
          },
          {
              "message": "response(http://example.com/foo) status code verify failure: got 500, want 200"
          }
      ]
  }

Verification errors are held in memory until they are explicitly cleared by

POST http://martian.proxy/verify/reset

Martian as a Library

Martian can also be included into any Go program and used as a library.

Modifiers All The Way Down

Martian's request and response modification system is designed to be general and extensible. The design objective is to provide individual modifier behaviors that can arranged to build out nearly any desired modification.

When working with Martian to compose behaviors, you'll need to be familiar with these different types of interactions:

• Modifiers: Changes the state of a request or a response
• Filters: Conditionally allows a contained Modifier to execute
• Groups: Bundles multiple modifiers to be executed in the order specified in the group
• Verifiers: Tracks network traffic against expectations

Modifiers, filters and groups all implement RequestModifer, ResponseModifier or RequestResponseModifier (defined in martian.go).

ModifyRequest(req *http.Request) error

ModifyResponse(res *http.Response) error

Throughout the code (and this documentation) you'll see the word "modifier" used as a term that encompasses modifiers, groups and filters. Even though a group does not modify a request or response, we still refer to it as a "modifier".

We refer to anything that implements the modifier interface as a Modifier.

Parser Registration

Each modifier must register its own parser with Martian. The parser is responsible for parsing a JSON message into a Go struct that implements a modifier interface.

Martian holds modifier parsers as a map of strings to functions that is built out at run-time. Each modifier is responsible for registering its parser with a call to parse.Register in init().

Signature of parse.Register:

Register(name string, parseFunc func(b []byte) (interface{}, error))

Register takes in the key as a string in the form package.Type. For instance, cookie_modifier registers itself with the key cookie.Modifier and query_string_filter registers itself as querystring.Filter. This string is the same as the value of name in the JSON configuration message.

In the following configuration message, header.Modifier is how the header modifier is registered in the init() of header_modifier.go.

{
  "header.Modifier": {
    "scope": ["response"],
    "name" : "Test-Header",
    "value" : "true"
  }
}

Example of parser registration from header_modifier.go:

func init() {
  parse.Register("header.Modifier", modifierFromJSON)
}

func modifierFromJSON(b []byte) (interface{}, error) {
  ...
}

Adding Your Own Modifier

If you have a use-case in mind that we have not developed modifiers, filters or verifiers for, you can easily extend Martian to your very specific needs.

There are 2 mandatory parts of a modifier:

• Implement the modifier interface
• Register the parser

Any Go struct that implements those interfaces can act as a modifier.

Contact

For questions and comments on how to use Martian, features announcements, or design discussions check out our public Google Group at https://groups.google.com/forum/#!forum/martianproxy-users.

For security related issues please send a detailed report to our private core group at martianproxy-core@googlegroups.com.

Disclaimer

This is not an official Google product (experimental or otherwise), it is just code that happens to be owned by Google.

Documentation

Overview

Package martian provides an HTTP/1.1 proxy with an API for configurable request and response modifiers.

Index

• func Init()
• type Context
  • func NewContext(req *http.Request) *Context
  • func TestContext(req *http.Request, conn net.Conn, bw *bufio.ReadWriter) (ctx *Context, remove func(), err error)
  • func (ctx *Context) APIRequest()
  • func (ctx *Context) Get(key string) (interface{}, bool)
  • func (ctx *Context) ID() string
  • func (ctx *Context) IsAPIRequest() bool
  • func (ctx *Context) Session() *Session
  • func (ctx *Context) Set(key string, val interface{})
  • func (ctx *Context) SkipLogging()
  • func (ctx *Context) SkipRoundTrip()
  • func (ctx *Context) SkippingLogging() bool
  • func (ctx *Context) SkippingRoundTrip() bool
• type MultiError
  • func NewMultiError() *MultiError
  • func (merr *MultiError) Add(err error)
  • func (merr *MultiError) Empty() bool
  • func (merr *MultiError) Error() string
  • func (merr *MultiError) Errors() []error
• type Proxy
  • func NewProxy() *Proxy
  • func (p *Proxy) Close()
  • func (p *Proxy) Closing() bool
  • func (p *Proxy) Serve(l net.Listener) error
  • func (p *Proxy) SetDial(dial func(string, string) (net.Conn, error))
  • func (p *Proxy) SetDownstreamProxy(proxyURL *url.URL)
  • func (p *Proxy) SetMITM(config *mitm.Config)
  • func (p *Proxy) SetRequestModifier(reqmod RequestModifier)
  • func (p *Proxy) SetResponseModifier(resmod ResponseModifier)
  • func (p *Proxy) SetRoundTripper(rt http.RoundTripper)
  • func (p *Proxy) SetTimeout(timeout time.Duration)
• type RequestModifier
• type RequestModifierFunc
  • func (f RequestModifierFunc) ModifyRequest(req *http.Request) error
• type RequestResponseModifier
  • func Noop(id string) RequestResponseModifier
• type ResponseModifier
• type ResponseModifierFunc
  • func (f ResponseModifierFunc) ModifyResponse(res *http.Response) error
• type Session
  • func (s *Session) Get(key string) (interface{}, bool)
  • func (s *Session) Hijack() (net.Conn, *bufio.ReadWriter, error)
  • func (s *Session) Hijacked() bool
  • func (s *Session) ID() string
  • func (s *Session) IsSecure() bool
  • func (s *Session) MarkInsecure()
  • func (s *Session) MarkSecure()
  • func (s *Session) Set(key string, val interface{})

Functions

func Init

func Init()

Init runs common initialization code for a martian proxy.

Types

type Context

type Context struct {
	// contains filtered or unexported fields
}

Context provides information and storage for a single request/response pair. Contexts are linked to shared session that is used for multiple requests on a single connection.

func NewContext

func NewContext(req *http.Request) *Context

NewContext returns a context for the in-flight HTTP request.

func TestContext

func TestContext(req *http.Request, conn net.Conn, bw *bufio.ReadWriter) (ctx *Context, remove func(), err error)

TestContext builds a new session and associated context and returns the context and a function to remove the associated context. If it fails to generate either a new session or a new context it will return an error. Intended for tests only.

func (*Context) APIRequest

func (ctx *Context) APIRequest()

APIRequest marks the requests as a request to the proxy API.

func (*Context) Get

func (ctx *Context) Get(key string) (interface{}, bool)

Get takes key and returns the associated value from the context.

func (*Context) ID

func (ctx *Context) ID() string

ID returns the context ID.

func (*Context) IsAPIRequest

func (ctx *Context) IsAPIRequest() bool

IsAPIRequest returns true when the request patterns matches a pattern in the proxy mux. The mux is usually defined as a parameter to the api.Forwarder, which uses http.DefaultServeMux by default.

func (*Context) Session

func (ctx *Context) Session() *Session

Session returns the session for the context.

func (*Context) Set

func (ctx *Context) Set(key string, val interface{})

Set takes a key and associates it with val in the context. The value is persisted for the duration of the request and is removed on the following request.

func (*Context) SkipLogging

func (ctx *Context) SkipLogging()

SkipLogging skips logging by Martian loggers for the current request.

func (*Context) SkipRoundTrip

func (ctx *Context) SkipRoundTrip()

SkipRoundTrip skips the round trip for the current request.

func (*Context) SkippingLogging

func (ctx *Context) SkippingLogging() bool

SkippingLogging returns whether the current request / response pair will be logged.

func (*Context) SkippingRoundTrip

func (ctx *Context) SkippingRoundTrip() bool

SkippingRoundTrip returns whether the current round trip will be skipped.

type MultiError

type MultiError struct {
	// contains filtered or unexported fields
}

MultiError is a collection of errors that implements the error interface.

func NewMultiError

func NewMultiError() *MultiError

NewMultiError returns a new MultiError.

func (*MultiError) Add

func (merr *MultiError) Add(err error)

Add appends an error to the error collection.

func (*MultiError) Empty

func (merr *MultiError) Empty() bool

Empty returns whether the *MultiError contains any errors.

func (*MultiError) Error

func (merr *MultiError) Error() string

Error returns the list of errors separated by newlines.

func (*MultiError) Errors

func (merr *MultiError) Errors() []error

Errors returns the error slice containing the error collection.

type Proxy

type Proxy struct {
	// contains filtered or unexported fields
}

Proxy is an HTTP proxy with support for TLS MITM and customizable behavior.

func NewProxy

func NewProxy() *Proxy

NewProxy returns a new HTTP proxy.

func (*Proxy) Close

func (p *Proxy) Close()

Close sets the proxy to the closing state so it stops receiving new connections, finishes processing any inflight requests, and closes existing connections without reading anymore requests from them.

func (*Proxy) Closing

func (p *Proxy) Closing() bool

Closing returns whether the proxy is in the closing state.

func (*Proxy) Serve

func (p *Proxy) Serve(l net.Listener) error

Serve accepts connections from the listener and handles the requests.

func (*Proxy) SetDial

func (p *Proxy) SetDial(dial func(string, string) (net.Conn, error))

SetDial sets the dial func used to establish a connection.

func (*Proxy) SetDownstreamProxy

func (p *Proxy) SetDownstreamProxy(proxyURL *url.URL)

SetDownstreamProxy sets the proxy that receives requests from the upstream proxy.

func (*Proxy) SetMITM

func (p *Proxy) SetMITM(config *mitm.Config)

SetMITM sets the config to use for MITMing of CONNECT requests.

func (*Proxy) SetRequestModifier

func (p *Proxy) SetRequestModifier(reqmod RequestModifier)

SetRequestModifier sets the request modifier.

func (*Proxy) SetResponseModifier

func (p *Proxy) SetResponseModifier(resmod ResponseModifier)

SetResponseModifier sets the response modifier.

func (*Proxy) SetRoundTripper

func (p *Proxy) SetRoundTripper(rt http.RoundTripper)

SetRoundTripper sets the http.RoundTripper of the proxy.

func (*Proxy) SetTimeout

func (p *Proxy) SetTimeout(timeout time.Duration)

SetTimeout sets the request timeout of the proxy.

type RequestModifier

type RequestModifier interface {
	// ModifyRequest modifies the request.
	ModifyRequest(req *http.Request) error
}

RequestModifier is an interface that defines a request modifier that can be used by a proxy.

type RequestModifierFunc

type RequestModifierFunc func(req *http.Request) error

RequestModifierFunc is an adapter for using a function with the given signature as a RequestModifier.

func (RequestModifierFunc) ModifyRequest

func (f RequestModifierFunc) ModifyRequest(req *http.Request) error

ModifyRequest modifies the request using the given function.

type RequestResponseModifier

type RequestResponseModifier interface {
	RequestModifier
	ResponseModifier
}

RequestResponseModifier is an interface that is both a ResponseModifier and a RequestModifier.

func Noop

func Noop(id string) RequestResponseModifier

Noop returns a modifier that does not change the request or the response.

type ResponseModifier

type ResponseModifier interface {
	// ModifyResponse modifies the response.
	ModifyResponse(res *http.Response) error
}

ResponseModifier is an interface that defines a response modifier that can be used by a proxy.

type ResponseModifierFunc

type ResponseModifierFunc func(res *http.Response) error

ResponseModifierFunc is an adapter for using a function with the given signature as a ResponseModifier.

func (ResponseModifierFunc) ModifyResponse

func (f ResponseModifierFunc) ModifyResponse(res *http.Response) error

ModifyResponse modifies the response using the given function.

type Session

type Session struct {
	// contains filtered or unexported fields
}

Session provides information and storage about a connection.

func (*Session) Get

func (s *Session) Get(key string) (interface{}, bool)

Get takes key and returns the associated value from the session.

func (*Session) Hijack

func (s *Session) Hijack() (net.Conn, *bufio.ReadWriter, error)

Hijack takes control of the connection from the proxy. No further action will be taken by the proxy and the connection will be closed following the return of the hijacker.

func (*Session) Hijacked

func (s *Session) Hijacked() bool

Hijacked returns whether the connection has been hijacked.

func (*Session) ID

func (s *Session) ID() string

ID returns the session ID.

func (*Session) IsSecure

func (s *Session) IsSecure() bool

IsSecure returns whether the current session is from a secure connection, such as when receiving requests from a TLS connection that has been MITM'd.

func (*Session) MarkInsecure

func (s *Session) MarkInsecure()

MarkInsecure marks the session as insecure.

func (*Session) MarkSecure

func (s *Session) MarkSecure()

MarkSecure marks the session as secure.

func (*Session) Set

func (s *Session) Set(key string, val interface{})

Set takes a key and associates it with val in the session. The value is persisted for the entire session across multiple requests and responses.