From 185c5f1dfdb5c3317d0207c48eb1a202c662fde1 Mon Sep 17 00:00:00 2001
From: Sebastiaan van Stijn <github@gone.nl>
Date: Thu, 29 May 2025 14:53:46 +0200
Subject: [PATCH] nat: PortBinding: implement stringer

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
---
 nat/nat.go      | 10 ++++++++
 nat/nat_test.go | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/nat/nat.go b/nat/nat.go
index 1ffe0355..335f3f73 100644
--- a/nat/nat.go
+++ b/nat/nat.go
@@ -17,6 +17,16 @@ type PortBinding struct {
 	HostPort string
 }
 
+func (pb *PortBinding) String() string {
+	if pb.HostPort == "" {
+		return ""
+	}
+	if pb.HostIP == "" {
+		return pb.HostPort
+	}
+	return net.JoinHostPort(pb.HostIP, pb.HostPort)
+}
+
 // PortMap is a collection of PortBinding indexed by Port
 type PortMap map[Port][]PortBinding
 
diff --git a/nat/nat_test.go b/nat/nat_test.go
index 6ee59e1f..c13049a0 100644
--- a/nat/nat_test.go
+++ b/nat/nat_test.go
@@ -842,6 +842,68 @@ func TestStringer(t *testing.T) {
 	}
 }
 
+func TestPortBinding(t *testing.T) {
+	tests := []struct {
+		doc     string
+		binding *PortBinding
+		expect  string
+	}{
+		{
+			doc:     "no host mapping",
+			binding: &PortBinding{},
+			expect:  "",
+		},
+		{
+			doc: "ipv4 missing port",
+			binding: &PortBinding{
+				HostIP: "192.168.1.100",
+			},
+			expect: "",
+		},
+		{
+			doc: "ipv4",
+			binding: &PortBinding{
+				HostIP:   "192.168.1.100",
+				HostPort: "6000",
+			},
+			expect: "192.168.1.100:6000",
+		},
+		{
+			doc: "ipv6 missing port",
+			binding: &PortBinding{
+				HostIP: "::1",
+			},
+			expect: "",
+		},
+		{
+			doc: "ipv6",
+			binding: &PortBinding{
+				HostIP:   "::1",
+				HostPort: "6000",
+			},
+			expect: "[::1]:6000",
+		},
+		// FIXME(thaJeztah): this should be invalid
+		{
+			doc: "ipv6 with braces",
+			binding: &PortBinding{
+				HostIP:   "[::1]",
+				HostPort: "6000",
+			},
+			expect: "[[::1]]:6000",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.doc, func(t *testing.T) {
+			actual := tc.binding.String()
+			if actual != tc.expect {
+				t.Errorf("Expected %s got %s", tc.expect, actual)
+			}
+		})
+	}
+}
+
 func BenchmarkParsePortSpecs(b *testing.B) {
 	specs := [][]string{
 		{"1234/tcp", "2345/udp", "3456/sctp"},