Windows alternative to netsh (#65)

* Included an alternative to netsh

* Cleaned up leftover logging and indentations

.gitignore

@@ -83,3 +83,7 @@ nohup.out
 
 # Temp files
 *~
+
+# binaries and binary folders
+bin/
+*.exe

os_configuration.go

@@ -11,7 +11,15 @@ package main
 // and the RSSI signal plus a boolean flag indicating if such content
 // was found in the given line.
 
-import "regexp"
+import (
+	"crypto/sha1"
+	"errors"
+	"encoding/hex"
+	"io"
+	"net/http"
+	"os"
+	"regexp"
+)
 
 // Regular expression matching standard (IEEE 802) MAC-48 addresses
 const macExpr = "([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})"
@@ -39,6 +47,70 @@ func GetConfiguration(os string, wlanInterface string) (OSConfig, bool) {
 	return config, ok
 }
 
+func ComputeSHA1Sum(filename string) (string, error) {
+	fd, err := os.Open(filename)
+
+	if err != nil {
+		return "", err
+	}
+	defer fd.Close()
+
+	h := sha1.New()
+	_, err = io.Copy(h, fd)
+	if err != nil {
+		return "", err
+	}
+
+	result := h.Sum(nil)
+
+	return hex.EncodeToString(result), nil
+}
+
+func DownloadVerifyFile(url string, target string, sha1sum string) (error) {
+	needsDownload := true
+
+	_, err := os.Stat(target)
+	if err == nil {
+		// File already exists, check if the hash matches
+		fileSum, _ := ComputeSHA1Sum(target)
+		if fileSum == sha1sum {
+			needsDownload = false
+		}
+	}
+
+	if needsDownload {
+		fd, err := os.Create(target)
+		if err != nil {
+			fd.Close()
+			return err
+		}
+
+		response, err := http.Get(url)
+		if err != nil {
+			return err
+		}
+		defer response.Body.Close()
+
+		n, err := io.Copy(fd, response.Body)
+		if err != nil {
+			return err
+		}
+
+		log.Info(n, "bytes downloaded.")
+		fd.Close()
+
+		fileSum, err := ComputeSHA1Sum(target)
+
+		if fileSum != sha1sum {
+			log.Warning("3rd party utility hash (" + fileSum + ") does NOT match expected hash (" + sha1sum + ").")
+			os.Remove(target)
+			return errors.New("Download failed")
+		}
+	}
+
+	return nil
+}
+
 func populateConfigurations(wlanInterface string) {
 	osConfigurations["darwin"] = OSConfig{
 		WifiScanCommand: "/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -s",
@@ -59,8 +131,61 @@ func populateConfigurations(wlanInterface string) {
 		}
 	}
 
-	osConfigurations["windows"] = OSConfig{
+
+	// Check for an alternative Windows wifi utility
+	_, err := os.Stat("bin")
+	if os.IsNotExist(err) {
+		// Create a bin folder
+		os.Mkdir("bin", os.ModePerm)
+	}
+	windowsConfig := OSConfig{
 		WifiScanCommand: "netsh wlan show network mode=bssid",
-		ScanConfig:      ScanParsingConfig{windowsFindMac, windowsFindRssi},
+		ScanConfig:	  ScanParsingConfig{windowsFindMac, windowsFindRssi},
+	}
+	needsPrompt := true
+
+	// Check if the alternative is downloaded
+	altSum := "5209b821e93d9a407b725b229223e53bb52495c9"
+	_, err = os.Stat("bin/windows-wlan-util.exe")
+	if err == nil {
+		// Verify the file
+		fileSum, _ := ComputeSHA1Sum("bin/windows-wlan-util.exe")
+		if fileSum == altSum {
+			windowsConfig = OSConfig{
+				WifiScanCommand: "bin/windows-wlan-util.exe query",
+				ScanConfig:	  ScanParsingConfig{windows2FindMac, windows2FindRssi},
+			}
+			needsPrompt = false
+		} else {
+			log.Warning("3rd party utility hash (" + fileSum + ") does NOT match expected hash (" + altSum + ").")
+		}
+	} else {
+		_, err := os.Stat("bin/windows-use-netsh")
+		if err == nil {
+			needsPrompt = false
+		}
+	}
+
+	if needsPrompt {
+		// Ask if the user wants to download the alternative
+		altUtil := getInput("Do you want to download a 3rd party utility for better wifi capture? (y/n)")
+		if altUtil == "y" {
+			err = DownloadVerifyFile(
+				"https://github.com/ScottSWu/windows-wlan-util/releases/download/v1.0/windows-wlan-util.exe",
+				"bin/windows-wlan-util.exe", "5209b821e93d9a407b725b229223e53bb52495c9")
+			if err == nil {
+				windowsConfig = OSConfig{
+					WifiScanCommand: "bin/windows-wlan-util.exe query",
+					ScanConfig:	  ScanParsingConfig{windows2FindMac, windows2FindRssi},
+				}
+			} else {
+				log.Warning("Failed to download 3rd party utility. You will be asked again next time.")
+			}
+		} else {
+			fd, _ := os.Create("bin/windows-use-netsh")
+			fd.Close()
+		}
 	}
+
+	osConfigurations["windows"] = windowsConfig
 }

windows2.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"strconv"
+	"strings"
+	"time"
+)
+
+// windows2 uses a third party alternative to netsh
+// See https://github.com/ScottSWu/windows-wlan-util for details
+
+func windows2FindMac(line string) (string, bool) {
+	return linuxFindMac(line)
+}
+
+func windows2FindRssi(line string) (int, bool) {
+	line = strings.Trim(line, " ")
+	space := strings.Index(line, " ")
+
+	if space == -1 {
+		return 0, false
+	}
+
+	rssi, err := strconv.ParseFloat(line[:space], 10)
+
+	// This is probably not the best place for this
+	// Rough timings suggest that finding ~30 access points takes around 10
+	// seconds. Thus for each MAC/Rssi value found, we should wait about 300 ms.
+	time.Sleep(300 * time.Millisecond)
+
+	return int(rssi), (err == nil)
+}