Fix compile issue and add -force flag to bypass VPN check

- Updated golang.org/x/net dependency to fix linking error with syscall.recvmsg
- Added -force flag to allow running the tool while connected to VPN
- Fixed linter errors: replaced deprecated ioutil with io/os, added error handling
- Added test, fmt, and lint targets to Makefile

cmd/mullvadclosest/main.go

@@ -2,8 +2,9 @@ package main
 
 import (
 	"encoding/json"
+	"flag"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"math"
 	"math/rand"
 	"net/http"
@@ -23,15 +24,15 @@ type RelayLatency struct {
 
 // MullvadIPResponse represents the response from the Mullvad IP check API
 type MullvadIPResponse struct {
-	IP                   string `json:"ip"`
-	Country              string `json:"country"`
-	City                 string `json:"city"`
-	Longitude            float64 `json:"longitude"`
-	Latitude             float64 `json:"latitude"`
-	MullvadExitIP        bool   `json:"mullvad_exit_ip"`
-	MullvadExitIPHostname string `json:"mullvad_exit_ip_hostname,omitempty"`
-	MullvadServerType    string `json:"mullvad_server_type,omitempty"`
-	Blacklisted          struct {
+	IP                    string  `json:"ip"`
+	Country               string  `json:"country"`
+	City                  string  `json:"city"`
+	Longitude             float64 `json:"longitude"`
+	Latitude              float64 `json:"latitude"`
+	MullvadExitIP         bool    `json:"mullvad_exit_ip"`
+	MullvadExitIPHostname string  `json:"mullvad_exit_ip_hostname,omitempty"`
+	MullvadServerType     string  `json:"mullvad_server_type,omitempty"`
+	Blacklisted           struct {
 		Blacklisted bool     `json:"blacklisted"`
 		Results     []string `json:"results"`
 	} `json:"blacklisted"`
@@ -46,7 +47,7 @@ func livenessWorker(id int, jobs <-chan Relay, results chan<- RelayLatency, wg *
 		if err == nil && isLive {
 			results <- RelayLatency{Relay: relay, Latency: latency}
 		}
-		bar.Add(1)
+		_ = bar.Add(1)
 	}
 }
 
@@ -61,7 +62,7 @@ func latencyWorker(id int, jobs <-chan RelayLatency, results chan<- RelayLatency
 				Latency: latency,
 			}
 		}
-		bar.Add(1)
+		_ = bar.Add(1)
 	}
 }
 
@@ -203,7 +204,7 @@ func CheckMullvadExitIP() (bool, error) {
 	}
 	defer resp.Body.Close()
 
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return false, fmt.Errorf("failed to read response body: %v", err)
 	}
@@ -217,6 +218,10 @@ func CheckMullvadExitIP() (bool, error) {
 }
 
 func main() {
+	// Define force flag
+	force := flag.Bool("force", false, "Force execution even when connected to VPN")
+	flag.Parse()
+
 	currentUser, err := user.Current()
 	if err != nil {
 		panic("Failed to get current user")
@@ -231,8 +236,9 @@ func main() {
 		panic(fmt.Sprintf("Error checking Mullvad exit IP: %v", err))
 	}
 
-	if isMullvadExitIP {
+	if isMullvadExitIP && !*force {
 		fmt.Println("This program is designed to test latency between your actual IP and the Mullvad VPN servers. Please disconnect from the VPN and run the program again.")
+		fmt.Println("Use -force flag to bypass this check.")
 		return
 	}
 

cmd/mullvadclosest/relays.go

@@ -3,7 +3,6 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"time"
 
@@ -46,7 +45,9 @@ func (r Relay) CheckLiveness() (bool, time.Duration, error) {
 	pinger.Count = 1
 	pinger.Timeout = 3 * time.Second // Increased timeout for the single ping
 	pinger.SetPrivileged(true)
-	pinger.Run()
+	if err := pinger.Run(); err != nil {
+		return false, 0, err
+	}
 	stats := pinger.Statistics()
 	if stats.PacketsRecv == 0 {
 		return false, 0, nil
@@ -64,7 +65,9 @@ func (r Relay) MeasureLatency() (time.Duration, error) {
 	pinger.Interval = 1 * time.Second // Adding interval between pings
 	pinger.Timeout = 10 * time.Second // Increased overall timeout
 	pinger.SetPrivileged(true)
-	pinger.Run()
+	if err := pinger.Run(); err != nil {
+		return 0, err
+	}
 	stats := pinger.Statistics()
 	return stats.MinRtt, nil
 }
@@ -110,7 +113,7 @@ func ParseRelayData() ([]Relay, error) {
 			return nil, fmt.Errorf("failed to read embedded file: %v", err)
 		}
 	} else {
-		fileData, err = ioutil.ReadFile(filePath)
+		fileData, err = os.ReadFile(filePath)
 		if err != nil {
 			return nil, fmt.Errorf("failed to read file: %v", err)
 		}