Filled out port usage counter.

net_freebsd.go

@@ -9,3 +9,20 @@ package main
 
 func setupPortForward(ip, port string) {
 }
+
+func portUsageCount(ports ...[]int) int {
+	const CMD = "sockstat -4c -p 22"
+	return 0
+}
+
+func portUsageCount(ports ...int) int {
+	cmd := "sockstat -4c"
+	for _, v := range ports {
+		cmd += " -p " + strconv.Itoa(v)
+	}
+	out, err := exec.Command(cmd).Output()
+	if err != nil {
+		log.Println("Port Usage Check: Could not run ", cmd)
+	}
+	return bytes.Count(out, []byte{'\n'}) - 1
+}

net_linux.go

@@ -8,10 +8,25 @@
 package main
 
 import (
+	"bytes"
 	"log"
+	"os/exec"
+	"strconv"
 )
 
 // just have this stub to allow building on Linux
 func setupPortForward(ip, port string) {
 	log.Print("Port forwarding not currently implemented for Linux/iptables")
 }
+
+func portUsageCount(ports ...int) int {
+	cmd := "sockstat -4c"
+	for _, v := range ports {
+		cmd += " -p " + strconv.Itoa(v)
+	}
+	out, err := exec.Command(cmd).Output()
+	if err != nil {
+		log.Println("Port Usage Check: Could not run ", cmd)
+	}
+	return bytes.Count(out, []byte{'\n'}) - 1
+}

net_test.go

@@ -0,0 +1,27 @@
+/*
+   Copyright 2016 gtalent2@gmail.com
+
+   This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/.
+*/
+package main
+
+import (
+	"net"
+	"strconv"
+	"testing"
+)
+
+func TestPortCount(t *testing.T) {
+	port := 49214
+	// listen on some port that nothing should be using for the sake of the test
+	go func() {
+		addr, _ := net.ResolveTCPAddr("tcp", "0.0.0.0:"+strconv.Itoa(port))
+		net.ListenTCP("tcp", addr)
+	}()
+
+	if portUsageCount(49214) != 1 {
+		t.Errorf("Port count usage reporting wrong number")
+	}
+}