StepHTTPServer: use the common/net pkg

common/http_config.go

@@ -9,8 +9,8 @@ import (
 // HTTPConfig contains configuration for the local HTTP Server
 type HTTPConfig struct {
 	HTTPDir     string `mapstructure:"http_directory"`
-	HTTPPortMin uint   `mapstructure:"http_port_min"`
-	HTTPPortMax uint   `mapstructure:"http_port_max"`
+	HTTPPortMin int    `mapstructure:"http_port_min"`
+	HTTPPortMax int    `mapstructure:"http_port_max"`
 }
 
 func (c *HTTPConfig) Prepare(ctx *interpolate.Context) []error {

common/step_http_server.go

@@ -3,11 +3,10 @@ package common
 import (
 	"context"
 	"fmt"
-	"log"
-	"math/rand"
-	"net"
+
 	"net/http"
 
+	"github.com/hashicorp/packer/common/net"
 	"github.com/hashicorp/packer/helper/common"
 	"github.com/hashicorp/packer/helper/multistep"
 	"github.com/hashicorp/packer/packer"
@@ -24,44 +23,35 @@ import (
 //   http_port int - The port the HTTP server started on.
 type StepHTTPServer struct {
 	HTTPDir     string
-	HTTPPortMin uint
-	HTTPPortMax uint
+	HTTPPortMin int
+	HTTPPortMax int
 
-	l net.Listener
+	l *net.Listener
 }
 
-func (s *StepHTTPServer) Run(_ context.Context, state multistep.StateBag) multistep.StepAction {
+func (s *StepHTTPServer) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
 	ui := state.Get("ui").(packer.Ui)
 
-	var httpPort uint = 0
 	if s.HTTPDir == "" {
-		state.Put("http_port", httpPort)
+		state.Put("http_port", uint(0))
 		return multistep.ActionContinue
 	}
 
 	// Find an available TCP port for our HTTP server
 	var httpAddr string
-	portRange := int(s.HTTPPortMax - s.HTTPPortMin)
-	for {
-		var err error
-		var offset uint = 0
-
-		if portRange > 0 {
-			// Intn will panic if portRange == 0, so we do a check.
-			// Intn is from [0, n), so add 1 to make from [0, n]
-			offset = uint(rand.Intn(portRange + 1))
-		}
-
-		httpPort = offset + s.HTTPPortMin
-		httpAddr = fmt.Sprintf("0.0.0.0:%d", httpPort)
-		log.Printf("Trying port: %d", httpPort)
-		s.l, err = net.Listen("tcp", httpAddr)
-		if err == nil {
-			break
-		}
+	var err error
+	s.l, err = net.ListenRangeConfig{
+		Min:     s.HTTPPortMin,
+		Max:     s.HTTPPortMax,
+		Addr:    "0.0.0.0",
+		Network: "tcp",
+	}.Listen(ctx)
+
+	if err != nil {
+		return multistep.ActionHalt
 	}
 
-	ui.Say(fmt.Sprintf("Starting HTTP server on port %d", httpPort))
+	ui.Say(fmt.Sprintf("Starting HTTP server on port %d", s.l.Port))
 
 	// Start the HTTP server and run it in the background
 	fileServer := http.FileServer(http.Dir(s.HTTPDir))
@@ -69,8 +59,8 @@ func (s *StepHTTPServer) Run(_ context.Context, state multistep.StateBag) multis
 	go server.Serve(s.l)
 
 	// Save the address into the state so it can be accessed in the future
-	state.Put("http_port", httpPort)
-	SetHTTPPort(fmt.Sprintf("%d", httpPort))
+	state.Put("http_port", s.l.Port)
+	SetHTTPPort(fmt.Sprintf("%d", s.l.Port))
 
 	return multistep.ActionContinue
 }