From b2830e8473e54ba56283d1839677b086dd378416 Mon Sep 17 00:00:00 2001
From: Owen <owen@txv.io>
Date: Sat, 22 Feb 2025 12:53:46 -0500
Subject: [PATCH] HP works!

---
 go.mod  |  1 +
 go.sum  |  2 ++
 main.go | 23 ++++++++++++++++-------
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/go.mod b/go.mod
index 0e8d553..c68b465 100644
--- a/go.mod
+++ b/go.mod
@@ -17,5 +17,6 @@ require (
 	github.com/vishvananda/netlink v1.3.0 // indirect
 	github.com/vishvananda/netns v0.0.4 // indirect
 	golang.org/x/crypto v0.31.0 // indirect
+	golang.org/x/exp v0.0.0-20250218142911-aa4b98e5adaa // indirect
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
 )
diff --git a/go.sum b/go.sum
index 4997342..e3f31ce 100644
--- a/go.sum
+++ b/go.sum
@@ -12,6 +12,8 @@ github.com/vishvananda/netns v0.0.4 h1:Oeaw1EM2JMxD51g9uhtC0D7erkIjgmj8+JZc26m1Y
 github.com/vishvananda/netns v0.0.4/go.mod h1:SpkAiCQRtJ6TvvxPnOSyH3BMl6unz3xZlaprSwhNNJM=
 golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
 golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
+golang.org/x/exp v0.0.0-20250218142911-aa4b98e5adaa h1:t2QcU6V556bFjYgu4L6C+6VrCPyJZ+eyRsABUPs1mz4=
+golang.org/x/exp v0.0.0-20250218142911-aa4b98e5adaa/go.mod h1:BHOTPb3L19zxehTsLoJXVaTktb06DFgmdW6Wb9s8jqk=
 golang.org/x/net v0.33.0 h1:74SYHlV8BIgHIFC/LrYkOGIwL19eTYXQ5wc6TBuO36I=
 golang.org/x/net v0.33.0/go.mod h1:HXLR5J+9DxmrqMwG9qjGCxZ+zKXxBru04zlTvWlWuN4=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/main.go b/main.go
index 1ece254..5748236 100644
--- a/main.go
+++ b/main.go
@@ -21,6 +21,7 @@ import (
 	"github.com/fosrl/olm/websocket"
 	"github.com/vishvananda/netlink"
 
+	"golang.org/x/exp/rand"
 	"golang.org/x/sys/unix"
 	"golang.zx2c4.com/wireguard/conn"
 	"golang.zx2c4.com/wireguard/device"
@@ -360,23 +361,31 @@ func FindAvailableUDPPort(minPort, maxPort uint16) (uint16, error) {
 		return 0, fmt.Errorf("invalid port range: min=%d, max=%d", minPort, maxPort)
 	}
 
-	for port := minPort; port <= maxPort; port++ {
-		// Create the UDP address to test
+	// Create a slice of all ports in the range
+	portRange := make([]uint16, maxPort-minPort+1)
+	for i := range portRange {
+		portRange[i] = minPort + uint16(i)
+	}
+
+	// Fisher-Yates shuffle to randomize the port order
+	rand.Seed(uint64(time.Now().UnixNano()))
+	for i := len(portRange) - 1; i > 0; i-- {
+		j := rand.Intn(i + 1)
+		portRange[i], portRange[j] = portRange[j], portRange[i]
+	}
+
+	// Try each port in the randomized order
+	for _, port := range portRange {
 		addr := &net.UDPAddr{
 			IP:   net.ParseIP("127.0.0.1"),
 			Port: int(port),
 		}
-
-		// Attempt to create a UDP listener
 		conn, err := net.ListenUDP("udp", addr)
 		if err != nil {
 			continue // Port is in use or there was an error, try next port
 		}
-
-		// Close the connection immediately
 		_ = conn.SetDeadline(time.Now())
 		conn.Close()
-
 		return port, nil
 	}