Merge pull request #110 from ken-schneider/main

[bugfix] Update windows buffer size

utils_windows.go

@@ -4,16 +4,33 @@
 package probing
 
 import (
+	"math"
+
 	"golang.org/x/net/ipv4"
 	"golang.org/x/net/ipv6"
 )
 
+const (
+	minimumBufferLength = 2048
+)
+
 // Returns the length of an ICMP message, plus the IP packet header.
+// Calculated as:
+// len(ICMP request data) + 2 * (len(ICMP header) + len(IP header))
+//
+// On Windows, the buffer needs to be able to contain:
+// - Response IP Header
+// - Response ICMP Header
+// - Request IP Header
+// - Request ICMP Header
+// - Request Data
 func (p *Pinger) getMessageLength() int {
 	if p.ipv4 {
-		return p.Size + 8 + ipv4.HeaderLen
+		calculatedLength := p.Size + (ipv4.HeaderLen+8)*2
+		return int(math.Max(float64(calculatedLength), float64(minimumBufferLength)))
 	}
-	return p.Size + 8 + ipv6.HeaderLen
+	calculatedLength := p.Size + (ipv6.HeaderLen+8)*2
+	return int(math.Max(float64(calculatedLength), float64(minimumBufferLength)))
 }
 
 // Attempts to match the ID of an ICMP packet.

utils_windows_test.go

@@ -0,0 +1,56 @@
+//go:build windows
+// +build windows
+
+package probing
+
+import "testing"
+
+func TestGetMessageLength(t *testing.T) {
+	tests := []struct {
+		description string
+		pinger      *Pinger
+		expected    int
+	}{
+		{
+			description: "IPv4 total size < 2048",
+			pinger: &Pinger{
+				Size: 24, // default size
+				ipv4: true,
+			},
+			expected: 2048,
+		},
+		{
+			description: "IPv4 total size > 2048",
+			pinger: &Pinger{
+				Size: 1993, // 2048 - 2 * (ipv4.HeaderLen + 8) + 1
+				ipv4: true,
+			},
+			expected: 2049,
+		},
+		{
+			description: "IPv6 total size < 2048",
+			pinger: &Pinger{
+				Size: 24,
+				ipv4: false,
+			},
+			expected: 2048,
+		},
+		{
+			description: "IPv6 total size > 2048",
+			pinger: &Pinger{
+				Size: 1953, // 2048 - 2 * (ipv6.HeaderLen + 8) + 1
+				ipv4: false,
+			},
+			expected: 2049,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.description, func(t *testing.T) {
+			actual := tt.pinger.getMessageLength()
+			if tt.expected != actual {
+				t.Fatalf("unexpected message length, expected: %d, actual %d", tt.expected, actual)
+			}
+		})
+	}
+}