port randomization added for VNC + SSH on run

.gitignore

@@ -0,0 +1 @@
+*.pub

main.go

@@ -4,10 +4,10 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net"
 	"os"
 	"os/exec"
 	"path/filepath"
-	"strconv"
 	"strings"
 )
 
@@ -48,7 +48,7 @@ var osImages = map[string]OSImage{
 	},
 	"alpine": {
 		Name:     "alpine",
-		URL:      "https://dl-cdn.alpinelinux.org/alpine/v3.22/releases/cloud/generic_alpine-3.22.2-x86_64-uefi-cloudinit-r0.qcow2",
+		URL:      "https://dl-cdn.alpinelinux.org/alpine/v3.22/releases/cloud/generic_alpine-3.22.2-x86_64-bios-cloudinit-r0.qcow2",
 		Filename: "alpine-3.22.qcow2",
 		User:     "alpine",
 	},
@@ -121,15 +121,16 @@ Type YES (all caps) to confirm: `, name, dir)
 }
 
 
-func sshPort(name string) int {
-	if strings.HasPrefix(name, "vm") {
-		if n, err := strconv.Atoi(strings.TrimPrefix(name, "vm")); err == nil {
-			return 2220 + n
+func findFreePort() int {
+        l, err := net.Listen("tcp", "127.0.0.1:0")
+        if err != nil {
+                panic(err)
         }
-	}
-	return 2222
+        defer l.Close()
+        return l.Addr().(*net.TCPAddr).Port
 }
 
+
 func parseArg(args []string, key string) string {
 	for i := 0; i < len(args)-1; i++ {
 		if args[i] == key {
@@ -256,7 +257,13 @@ func startVM(name string) {
 		os.Remove(pidFile(name))
 	}
 
-	port := sshPort(name)
+	port :=  findFreePort()
+	vncPort := findFreePort()
+	vncDisplay := vncPort - 5900
+	if vncDisplay < 0 {
+		panic("invalid VNC port allocation")
+	}
+
 
 	cmd := exec.Command(
 		"qemu-system-x86_64",
@@ -267,7 +274,7 @@ func startVM(name string) {
 		"-smp", cpus,
 
 		"-vga", "virtio",
-		"-display", "vnc=0.0.0.0:1",
+		"-display", fmt.Sprintf("vnc=0.0.0.0:%d", vncDisplay),
 
 		"-drive", fmt.Sprintf("file=%s,if=virtio,format=qcow2", diskPath(name)),
 		"-drive", fmt.Sprintf("file=%s,if=virtio,format=raw", seedISOPath(name)),
@@ -285,7 +292,7 @@ func startVM(name string) {
 	}
 
 	fmt.Println("VM started:", name)
-	fmt.Println("VNC: localhost:5901")
+	fmt.Printf("VNC: vnc://127.0.0.1:%d\n", vncPort)
 	fmt.Printf("SSH: ssh <user>@localhost -p %d\n", port)
 }