General review:

- Fix typos
- Follow some Go good practices
- Better documentation, more consistent godoc.org
- Refactoring

CHANGELOG.md

@@ -1,5 +1,5 @@
 v0.3.5 - 15 Sep 2013
-* Significally improved test coverage
+* Significantly improved test coverage
 * Fixed bug with redirect replay https://github.com/buger/gor/pull/15
 * Added limit on listener side
 * Improved stability (catch and log panic, instead of exiting)
@@ -7,8 +7,8 @@ v0.3.5 - 15 Sep 2013
 
 v0.3.3 - 22 Jun 2013
 * Using TCP instead of UDP for communication between Listener and Replay
-* Significally improved performance
-* Fixed bugs causing locking and message droping (concurrency issues)
+* Significantly improved performance
+* Fixed bugs causing locking and message dropping (concurrency issues)
 * Rewrote concurrency model to use more channels
 
 v0.3 - 10 Jun 2013

gor.go

@@ -8,27 +8,29 @@ package main
 import (
 	"flag"
 	"fmt"
-	"github.com/buger/gor/listener"
-	"github.com/buger/gor/replay"
 	"log"
 	"os"
 	"runtime/pprof"
 	"time"
+
+	"github.com/buger/gor/listener"
+	"github.com/buger/gor/replay"
 )
 
 const (
 	VERSION = "0.3.5"
 )
 
-var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")
-var memprofile = flag.String("memprofile", "", "write memory profile to this file")
+var (
+	mode       string
+	cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")
+	memprofile = flag.String("memprofile", "", "write memory profile to this file")
+)
 
 func main() {
 	defer func() {
 		if r := recover(); r != nil {
-			var ok bool
-			_, ok = r.(error)
-			if !ok {
+			if _, ok := r.(error); !ok {
 				fmt.Errorf("pkg: %v", r)
 			}
 		}
@@ -36,8 +38,6 @@ func main() {
 
 	fmt.Println("Version:", VERSION)
 
-	mode := "unknown"
-
 	if len(os.Args) > 1 {
 		mode = os.Args[1]
 	}

integration_test.go

@@ -1,18 +1,15 @@
 package main
 
 import (
-	"testing"
-
-	"github.com/buger/gor/listener"
-	"github.com/buger/gor/replay"
-
-	"time"
-
 	"fmt"
 	"net/http"
 	"strconv"
-
 	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/buger/gor/listener"
+	"github.com/buger/gor/replay"
 )
 
 func isEqual(t *testing.T, a interface{}, b interface{}) {
@@ -56,7 +53,7 @@ func (e *Env) startListener(port int, replayPort int) {
 	listener.Settings.Port = port
 
 	if e.ListenerLimit != 0 {
-		listener.Settings.ReplayAddress += "|" + strconv.Itoa(e.ListenerLimit)
+		listener.Settings.ReplayLimit = e.ListenerLimit
 	}
 
 	listener.Run()
@@ -65,6 +62,7 @@ func (e *Env) startListener(port int, replayPort int) {
 func (e *Env) startReplay(port int, forwardPort int) {
 	replay.Settings.Verbose = e.Verbose
 	replay.Settings.Host = "127.0.0.1"
+	replay.Settings.Address = "127.0.0.1:" + strconv.Itoa(port)
 	replay.Settings.ForwardAddress = "127.0.0.1:" + strconv.Itoa(forwardPort)
 	replay.Settings.Port = port
 

listener/listener.go

@@ -1,7 +1,7 @@
 // Listener capture TCP traffic using RAW SOCKETS.
 // Note: it requires sudo or root access.
 //
-// Rigt now it suport only HTTP
+// Right now it supports only HTTP
 package listener
 
 import (
@@ -16,16 +16,17 @@ import (
 	"time"
 )
 
-// Enable debug logging only if "--verbose" flag passed
+// Debug enables logging only if "--verbose" flag passed
 func Debug(v ...interface{}) {
 	if Settings.Verbose {
 		log.Println(v...)
 	}
 }
 
+// ReplayServer returns a connection to the replay server and error if some
 func ReplayServer() (conn net.Conn, err error) {
-	// Connection to reaplay server
-	conn, err = net.Dial("tcp", Settings.ReplayServer())
+	// Connection to replay server
+	conn, err = net.Dial("tcp", Settings.ReplayAddress)
 
 	if err != nil {
 		log.Println("Connection error ", err, Settings.ReplayAddress)
@@ -34,7 +35,7 @@ func ReplayServer() (conn net.Conn, err error) {
 	return
 }
 
-// Because its sub-program, Run acts as `main`
+// Run acts as `main` function of a listener
 func Run() {
 	if os.Getuid() != 0 {
 		fmt.Println("Please start the listener as root or sudo!")
@@ -43,7 +44,7 @@ func Run() {
 	}
 
 	fmt.Println("Listening for HTTP traffic on", Settings.Address+":"+strconv.Itoa(Settings.Port))
-	fmt.Println("Forwarding requests to replay server:", Settings.ReplayServer(), "Limit:", Settings.ReplayLimit)
+	fmt.Println("Forwarding requests to replay server:", Settings.ReplayAddress, "Limit:", Settings.ReplayLimit)
 
 	// Sniffing traffic from given address
 	listener := RAWTCPListen(Settings.Address, Settings.Port)

listener/listener_test.go

@@ -40,6 +40,6 @@ func TestSendMessage(t *testing.T) {
 	buf = buf[0:n]
 
 	if bytes.Compare(buf, msg.Bytes()) != 0 {
-		t.Errorf("Original and reveived requests does not match")
+		t.Errorf("Original and received requests does not match")
 	}
 }

listener/raw_tcp_listener.go

@@ -25,6 +25,7 @@ type RAWTCPListener struct {
 	port int    // Port to listen
 }
 
+// RAWTCPListen creates a listener to capture traffic from RAW_SOCKET
 func RAWTCPListen(addr string, port int) (listener *RAWTCPListener) {
 	listener = &RAWTCPListener{}
 
@@ -49,7 +50,7 @@ func (t *RAWTCPListener) listen() {
 			t.c_messages <- message
 			t.deleteMessage(message)
 
-		// We need to use channgels to process each packet to avoid data races
+		// We need to use channels to process each packet to avoid data races
 		case packet := <-t.c_packets:
 			t.processTCPPacket(packet)
 		}
@@ -58,7 +59,7 @@ func (t *RAWTCPListener) listen() {
 
 // Deleting messages that came from t.c_del_message channel
 func (t *RAWTCPListener) deleteMessage(message *TCPMessage) bool {
-	var idx int = -1
+	idx := -1
 
 	// Searching for given message in messages buffer
 	for i, m := range t.messages {
@@ -154,6 +155,7 @@ func (t *RAWTCPListener) processTCPPacket(packet *TCPPacket) {
 	message.c_packets <- packet
 }
 
+// Receive TCP messages from the listener channel
 func (t *RAWTCPListener) Receive() *TCPMessage {
 	return <-t.c_messages
 }

listener/settings.go

@@ -14,6 +14,7 @@ const (
 	defaultReplayAddress = "localhost:28020"
 )
 
+// ListenerSettings contain all the needed configuration for setting up the listener
 type ListenerSettings struct {
 	Port    int
 	Address string
@@ -27,14 +28,15 @@ type ListenerSettings struct {
 
 var Settings ListenerSettings = ListenerSettings{}
 
-func (s *ListenerSettings) ReplayServer() string {
-	host_info := strings.Split(s.ReplayAddress, "|")
+// ReplayServer generates ReplayLimit and ReplayAddress settings out of the replayAddress
+func (s *ListenerSettings) ReplayServer(replayAddress string) {
+	host_info := strings.Split(replayAddress, "|")
 
 	if len(host_info) > 1 {
 		s.ReplayLimit, _ = strconv.Atoi(host_info[1])
 	}
 
-	return host_info[0]
+	s.ReplayAddress = host_info[0]
 }
 
 func init() {
@@ -43,10 +45,10 @@ func init() {
 	}
 
 	flag.IntVar(&Settings.Port, "p", defaultPort, "Specify the http server port whose traffic you want to capture")
+	flag.StringVar(&Settings.Address, "ip", defaultAddress, "Specify IP address to listen")
 
-	flag.StringVar(&Settings.Address, "ip", defaultAddress, "Specifi IP address to listen")
-
-	flag.StringVar(&Settings.ReplayAddress, "r", defaultReplayAddress, "Address of replay server.")
+	replayAddress := flag.String("r", defaultReplayAddress, "Address of replay server.")
+	Settings.ReplayServer(*replayAddress)
 
 	flag.BoolVar(&Settings.Verbose, "verbose", false, "Log requests")
 }

listener/tcp_message.go

@@ -10,9 +10,9 @@ const MSG_EXPIRE = 200 * time.Millisecond
 // TCPMessage ensure that all TCP packets for given request is received, and processed in right sequence
 // Its needed because all TCP message can be fragmented or re-transmitted
 //
-// Each TCP Packet have 2 ids: acknowledgement - message_id, and sequence - packet_id
+// Each TCP Packet have 2 ids: acknowledgment - message_id, and sequence - packet_id
 // Message can be compiled from unique packets with same message_id which sorted by sequence
-// Message is received if we did't receive any packets for 200ms
+// Message is received if we didn't receive any packets for 200ms
 type TCPMessage struct {
 	Ack     uint32 // Message ID
 	packets []*TCPPacket
@@ -27,6 +27,7 @@ type TCPMessage struct {
 	c_del_message chan *TCPMessage
 }
 
+// NewTCPMessage pointer created from a Acknowledgment number and a channel of messages readuy to be deleted
 func NewTCPMessage(Ack uint32, c_del chan *TCPMessage) (msg *TCPMessage) {
 	msg = &TCPMessage{Ack: Ack}
 
@@ -54,12 +55,13 @@ func (t *TCPMessage) listen() {
 	}
 }
 
+// Timeout notifies message to stop listening, close channel and message ready to be sent
 func (t *TCPMessage) Timeout() {
 	t.c_closing <- 1     // Notify to stop listen loop and close channel
-	t.c_del_message <- t // Notify RAWListener that message is ready to be send to replay server
+	t.c_del_message <- t // Notify RAWListener that message is ready to be sent to replay server
 }
 
-// Sort packets in right orders and return message content
+// Bytes sorts packets in right orders and return message content
 func (t *TCPMessage) Bytes() (output []byte) {
 	mk := make([]int, len(t.packets))
 
@@ -78,7 +80,7 @@ func (t *TCPMessage) Bytes() (output []byte) {
 	return
 }
 
-// Add packet to the message and ensure packet uniquiness
+// AddPacket to the message and ensure packet uniqueness
 // TCP allows that packet can be re-send multiple times
 func (t *TCPMessage) AddPacket(packet *TCPPacket) {
 	if t.expired {

listener/tcp_packet.go

@@ -36,43 +36,41 @@ type TCPPacket struct {
 	Data []byte
 }
 
-func NewTCPPacket(b []byte) (p *TCPPacket) {
-	p = &TCPPacket{Data: b}
-	p.ParseFast()
+// NewTCPPacket pointer from data in []byte
+func NewTCPPacket(b []byte) (t *TCPPacket) {
+	t = &TCPPacket{Data: b}
+	t.ParseBasic()
 
-	return p
+	return t
 }
 
-// Inspired by: https://github.com/miekg/pcap/blob/master/packet.go
+// Parse TCP Packet, inspired by: https://github.com/miekg/pcap/blob/master/packet.go
 func (t *TCPPacket) Parse() {
+	t.ParseBasic()
 	t.SrcPort = binary.BigEndian.Uint16(t.Data[0:2])
 	t.DestPort = binary.BigEndian.Uint16(t.Data[2:4])
-	t.Seq = binary.BigEndian.Uint32(t.Data[4:8])
-	t.Ack = binary.BigEndian.Uint32(t.Data[8:12])
-	t.DataOffset = (t.Data[12] & 0xF0) >> 4
 	t.Flags = binary.BigEndian.Uint16(t.Data[12:14]) & 0x1FF
 	t.Window = binary.BigEndian.Uint16(t.Data[14:16])
 	t.Checksum = binary.BigEndian.Uint16(t.Data[16:18])
 	t.Urgent = binary.BigEndian.Uint16(t.Data[18:20])
-
-	t.Data = t.Data[t.DataOffset*4:]
 }
 
-// Parse only needed set of fields
-func (t *TCPPacket) ParseFast() {
+// ParseBasic set of fields
+func (t *TCPPacket) ParseBasic() {
 	t.Seq = binary.BigEndian.Uint32(t.Data[4:8])
 	t.Ack = binary.BigEndian.Uint32(t.Data[8:12])
-
 	t.DataOffset = (t.Data[12] & 0xF0) >> 4
+
 	t.Data = t.Data[t.DataOffset*4:]
 }
 
+// String output for a TCP Packet
 func (t *TCPPacket) String() string {
 	return strings.Join([]string{
 		"Source port: " + strconv.Itoa(int(t.SrcPort)),
 		"Dest port:" + strconv.Itoa(int(t.DestPort)),
 		"Sequence:" + strconv.Itoa(int(t.Seq)),
-		"Acknowledgement:" + strconv.Itoa(int(t.Ack)),
+		"Acknowledgment:" + strconv.Itoa(int(t.Ack)),
 		"Header len:" + strconv.Itoa(int(t.DataOffset)),
 
 		"Flag ns:" + strconv.FormatBool(t.Flags&TCP_NS != 0),

replay/replay.go

@@ -35,13 +35,14 @@ import (
 
 const bufSize = 4096
 
-// Enable debug logging only if "--verbose" flag passed
+// Debug enables logging only if "--verbose" flag passed
 func Debug(v ...interface{}) {
 	if Settings.Verbose {
 		log.Println(v...)
 	}
 }
 
+// ParseRequest in []byte returns a http request or an error
 func ParseRequest(data []byte) (request *http.Request, err error) {
 	buf := bytes.NewBuffer(data)
 	reader := bufio.NewReader(buf)
@@ -50,13 +51,13 @@ func ParseRequest(data []byte) (request *http.Request, err error) {
 	return
 }
 
-// Because its sub-program, Run acts as `main`
+// Run acts as `main` function of replay
 // Replay server listen to UDP traffic from Listeners
 // Each request processed by RequestFactory
 func Run() {
-	listener, err := net.Listen("tcp", Settings.Address())
+	listener, err := net.Listen("tcp", Settings.Address)
 
-	log.Println("Starting replay server at:", Settings.Address())
+	log.Println("Starting replay server at:", Settings.Address)
 
 	if err != nil {
 		log.Fatal("Can't start:", err)
@@ -97,7 +98,7 @@ func handleConnection(conn net.Conn, rf *RequestFactory) error {
 		case io.EOF:
 			read = false
 		case nil:
-			response = append(response, buf[0:n]...)
+			response = append(response, buf[:n]...)
 			if n < bufSize {
 				read = false
 			}

replay/request_factory.go

@@ -6,6 +6,8 @@ import (
 	"net/url"
 )
 
+// HttpResponse contains a host, a http request,
+// a http response and an error
 type HttpResponse struct {
 	host *ForwardHost
 	req  *http.Request
@@ -13,7 +15,7 @@ type HttpResponse struct {
 	err  error
 }
 
-// Class for processing requests
+// RequestFactory processes requests
 //
 // Basic workflow:
 //
@@ -26,7 +28,7 @@ type RequestFactory struct {
 	c_requests  chan *http.Request
 }
 
-// RequestFactory contstuctor
+// NewRequestFactory returns a RequestFactory pointer
 // One created, it starts listening for incoming requests: requests channel
 func NewRequestFactory() (factory *RequestFactory) {
 	factory = &RequestFactory{}
@@ -38,7 +40,7 @@ func NewRequestFactory() (factory *RequestFactory) {
 	return
 }
 
-// Disable redirects https://github.com/buger/gor/pull/15
+// customCheckRedirect disables redirects https://github.com/buger/gor/pull/15
 func customCheckRedirect(req *http.Request, via []*http.Request) error {
 	if len(via) >= 0 {
 		return errors.New("stopped after 2 redirects")
@@ -46,7 +48,7 @@ func customCheckRedirect(req *http.Request, via []*http.Request) error {
 	return nil
 }
 
-// Forward http request to given host
+// sendRequest forwards http request to a given host
 func (f *RequestFactory) sendRequest(host *ForwardHost, request *http.Request) {
 	client := &http.Client{
 		CheckRedirect: customCheckRedirect,
@@ -71,7 +73,7 @@ func (f *RequestFactory) sendRequest(host *ForwardHost, request *http.Request) {
 	f.c_responses <- &HttpResponse{host, request, resp, err}
 }
 
-// Handle incoming requests, and they responses
+// handleRequests and their responses
 func (f *RequestFactory) handleRequests() {
 	hosts := Settings.ForwardedHosts()
 

replay/request_stats.go

@@ -4,31 +4,31 @@ import (
 	"time"
 )
 
-// Stats stores in context of current timestamp
+// RequestStat stores in context of current timestamp
 type RequestStat struct {
 	timestamp int64
 
 	Codes map[int]int // { 200: 10, 404:2, 500:1 }
 
 	Count  int // All requests including errors
-	Errors int // Rquests with errors (timeout or host not reachable). Not include 50x errors.
+	Errors int // Requests with errors (timeout or host not reachable). Not include 50x errors.
 
 	host *ForwardHost
 }
 
-// Ensure that current stats is actual (for current timestamp)
+// Touch ensures that current stats is actual (for current timestamp)
 func (s *RequestStat) Touch() {
 	if s.timestamp != time.Now().Unix() {
 		s.reset()
 	}
 }
 
-// Called on request start
+// IncReq is called on request start
 func (s *RequestStat) IncReq() {
 	s.Count++
 }
 
-// Called after response
+// IncResp is called after response
 func (s *RequestStat) IncResp(resp *HttpResponse) {
 	s.Touch()
 
@@ -40,11 +40,11 @@ func (s *RequestStat) IncResp(resp *HttpResponse) {
 	s.Codes[resp.resp.StatusCode]++
 }
 
-// Updated stats timestamp to current time and reset to zero all stats values
+// reset updates stats timestamp to current time and reset to zero all stats values
 // TODO: Further on reset it should write stats to file
 func (s *RequestStat) reset() {
-	if s.timestamp != 0 {        
-	   Debug("Host:", s.host.Url, "Requests:", s.Count, "Errors:", s.Errors, "Status codes:", s.Codes)
+	if s.timestamp != 0 {
+		Debug("Host:", s.host.Url, "Requests:", s.Count, "Errors:", s.Errors, "Status codes:", s.Codes)
 	}
 
 	s.timestamp = time.Now().Unix()
@@ -54,7 +54,7 @@ func (s *RequestStat) reset() {
 	s.Errors = 0
 }
 
-// RequestStat constructor
+// NewRequestStats returns a RequestStat pointer
 func NewRequestStats(host *ForwardHost) (stat *RequestStat) {
 	stat = &RequestStat{host: host}
 	stat.reset()

replay/settings.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 )
 
+// ForwardHost where to forward requests
 type ForwardHost struct {
 	Url   string
 	Limit int
@@ -14,15 +15,19 @@ type ForwardHost struct {
 	Stat *RequestStat
 }
 
+// ReplaySettings ListenerSettings contain all the needed configuration for setting up the replay
 type ReplaySettings struct {
 	Port int
 	Host string
 
+	Address        string
 	ForwardAddress string
 
 	Verbose bool
 }
 
+var Settings ReplaySettings = ReplaySettings{}
+
 // ForwardedHosts implements forwardAddress syntax support for multiple hosts (coma separated), and rate limiting by specifing "|maxRps" after host name.
 //
 //    -f "host1,http://host2|10,host3"
@@ -50,13 +55,11 @@ func (r *ReplaySettings) ForwardedHosts() (hosts []*ForwardHost) {
 	return
 }
 
-// Helper to return address with port, e.g.: 127.0.0.1:28020
-func (r *ReplaySettings) Address() string {
-	return r.Host + ":" + strconv.Itoa(r.Port)
+// SetAddress with port, e.g.: 127.0.0.1:28020
+func (r *ReplaySettings) SetAddress() {
+	r.Address = r.Host + ":" + strconv.Itoa(r.Port)
 }
 
-var Settings ReplaySettings = ReplaySettings{}
-
 func init() {
 	if len(os.Args) < 2 || os.Args[1] != "replay" {
 		return
@@ -66,14 +69,15 @@ func init() {
 		defaultPort = 28020
 		defaultHost = "0.0.0.0"
 
-		defaultAddress = "http://localhost:8080"
+		defaultForwardAddress = "http://localhost:8080"
 	)
 
 	flag.IntVar(&Settings.Port, "p", defaultPort, "specify port number")
 
 	flag.StringVar(&Settings.Host, "ip", defaultHost, "ip addresses to listen on")
 
-	flag.StringVar(&Settings.ForwardAddress, "f", defaultAddress, "http address to forward traffic.\n\tYou can limit requests per second by adding `|num` after address.\n\tIf you have multiple addresses with different limits. For example: http://staging.example.com|100,http://dev.example.com|10")
+	Settings.SetAddress()
+	flag.StringVar(&Settings.ForwardAddress, "f", defaultForwardAddress, "http address to forward traffic.\n\tYou can limit requests per second by adding `|num` after address.\n\tIf you have multiple addresses with different limits. For example: http://staging.example.com|100,http://dev.example.com|10")
 
 	flag.BoolVar(&Settings.Verbose, "verbose", false, "Log requests")
 }