From f2e90bef45f6253ddd7b49b3ce2706e1d0e36b65 Mon Sep 17 00:00:00 2001
From: bejaratommy <tommy@bejaranoinfra.io>
Date: Mon, 20 Apr 2026 15:25:12 +0000
Subject: [PATCH] feat: add joinHostPort and splitHostPort network functions

Fixes #472. Adds two new template functions that wrap Go's standard
library net.JoinHostPort and net.SplitHostPort:

- joinHostPort(host, port): combines host and port into host:port,
  correctly bracketing IPv6 addresses as [host]:port.
- splitHostPort(hostport): splits host:port into a map{host, port},
  handling IPv6 bracket notation transparently.
---
 CHANGELOG.md    |  6 ++++++
 docs/network.md | 21 +++++++++++++++++++++
 functions.go    |  4 ++++
 network.go      |  9 +++++++++
 network_test.go | 33 +++++++++++++++++++++++++++++++++
 5 files changed, 73 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b5ef766a..4c035c2e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Release 3.4.0 (unreleased)
+
+### Added
+
+- #472: Added `joinHostPort` and `splitHostPort` network functions
+
 ## Release 3.3.0 (2024-08-29)
 
 ### Added
diff --git a/docs/network.md b/docs/network.md
index ea6cfd7f..65cbfd48 100644
--- a/docs/network.md
+++ b/docs/network.md
@@ -9,3 +9,24 @@ The `getHostByName` receives a domain name and returns the ip address.
 ```
 getHostByName "www.google.com" would return the corresponding ip address of www.google.com
 ```
+
+## joinHostPort
+
+`joinHostPort` combines a host and port into a network address of the form `host:port`. For IPv6 addresses the host is enclosed in square brackets: `[host]:port`. This is the inverse of `splitHostPort`.
+
+```
+joinHostPort "192.0.2.1" "80"    -> "192.0.2.1:80"
+joinHostPort "2001:db8::1" "80"  -> "[2001:db8::1]:80"
+joinHostPort "example.com" "443" -> "example.com:443"
+```
+
+## splitHostPort
+
+`splitHostPort` splits a network address of the form `host:port` or `[host]:port` into its host and port components, returning a map with keys `host` and `port`. This is the inverse of `joinHostPort`.
+
+```
+{{- with splitHostPort "192.0.2.1:80" }}
+host: {{ .host }}
+port: {{ .port }}
+{{- end }}
+```
diff --git a/functions.go b/functions.go
index cda47d26..b99f832a 100644
--- a/functions.go
+++ b/functions.go
@@ -91,6 +91,8 @@ var nonhermeticFunctions = []string{
 
 	// Network
 	"getHostByName",
+	"joinHostPort",
+	"splitHostPort",
 }
 
 var genericMap = map[string]interface{}{
@@ -272,6 +274,8 @@ var genericMap = map[string]interface{}{
 
 	// Network:
 	"getHostByName": getHostByName,
+	"joinHostPort":  joinHostPort,
+	"splitHostPort": splitHostPort,
 
 	// Paths:
 	"base":  path.Base,
diff --git a/network.go b/network.go
index 108d78a9..5fe1eb31 100644
--- a/network.go
+++ b/network.go
@@ -10,3 +10,12 @@ func getHostByName(name string) string {
 	//TODO: add error handing when release v3 comes out
 	return addrs[rand.Intn(len(addrs))]
 }
+
+func joinHostPort(host, port string) string {
+	return net.JoinHostPort(host, port)
+}
+
+func splitHostPort(hostport string) map[string]string {
+	host, port, _ := net.SplitHostPort(hostport)
+	return map[string]string{"host": host, "port": port}
+}
diff --git a/network_test.go b/network_test.go
index 9c153f0a..91e5213c 100644
--- a/network_test.go
+++ b/network_test.go
@@ -16,3 +16,36 @@ func TestGetHostByName(t *testing.T) {
 	assert.NotNil(t, ip)
 	assert.NotEmpty(t, ip)
 }
+
+func TestJoinHostPort(t *testing.T) {
+	tests := []struct {
+		tpl      string
+		expected string
+	}{
+		{`{{joinHostPort "192.0.2.1" "80"}}`, "192.0.2.1:80"},
+		{`{{joinHostPort "2001:db8::1" "80"}}`, "[2001:db8::1]:80"},
+		{`{{joinHostPort "example.com" "443"}}`, "example.com:443"},
+	}
+	for _, tt := range tests {
+		result, err := runRaw(tt.tpl, nil)
+		assert.NoError(t, err)
+		assert.Equal(t, tt.expected, result)
+	}
+}
+
+func TestSplitHostPort(t *testing.T) {
+	tests := []struct {
+		tpl          string
+		expectedHost string
+		expectedPort string
+	}{
+		{`{{with splitHostPort "192.0.2.1:80"}}{{.host}}/{{.port}}{{end}}`, "192.0.2.1", "80"},
+		{`{{with splitHostPort "[2001:db8::1]:80"}}{{.host}}/{{.port}}{{end}}`, "2001:db8::1", "80"},
+		{`{{with splitHostPort "example.com:443"}}{{.host}}/{{.port}}{{end}}`, "example.com", "443"},
+	}
+	for _, tt := range tests {
+		result, err := runRaw(tt.tpl, nil)
+		assert.NoError(t, err)
+		assert.Equal(t, tt.expectedHost+"/"+tt.expectedPort, result)
+	}
+}