findunusedport writes to stdout an unused tcp port number.
Change-Id: Ic1c018413493f5bff453ccd1b8a7c7475469d606
diff --git a/tools/findunusedport/main.go b/tools/findunusedport/main.go
new file mode 100644
index 0000000..9d11884
--- /dev/null
+++ b/tools/findunusedport/main.go
@@ -0,0 +1,31 @@
+package main
+
+// findunusedport finds a random unused TCP port in the range 1k to 64k and prints it to standard out.
+
+import (
+ "fmt"
+ "math/rand"
+ "os"
+ "syscall"
+
+ "veyron2/vlog"
+)
+
+func main() {
+ rand.Seed(int64(os.Getpid()))
+ for i := 0; i < 1000; i++ {
+ port := 1024 + rand.Int31n(64512)
+ fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
+ if err != nil {
+ continue
+ }
+ sa := &syscall.SockaddrInet4{Port: int(port)}
+ if err := syscall.Bind(fd, sa); err != nil {
+ continue
+ }
+ syscall.Close(fd)
+ fmt.Println(port)
+ return
+ }
+ vlog.Fatal("can't find unused port")
+}
