feat: add validator for IPv4 bind address / host:port

[rtomadpg]

Fixes Or Enhances

Here is a little PR to say thank you, for providing your framework.

Let's add a validator for IPv4 bind addresses.

Examples of valid input:

• :9000 for port 9000 on any IP address
• 1.2.3.4:7777 for port 7777 on specific IP address

My use case: I need this validator for an application's config including IP based socket listener addresses, like: :9999 or 127.0.0.1:9999

Make sure that you've checked the boxes below before you submit PR:

• Tests exist or have been written that cover this particular change.

@go-playground/validator-maintainers

[coveralls]

coverage: 74.316% (+0.03%) from 74.291%
when pulling e022a95 on rtomadpg:feat-add-ipv4port
into a947377 on go-playground:master.

[nodivbyzero]

More readable and concise implementation:

Suggested change

	ip, port, err := net.SplitHostPort(val)
	if err != nil {
	return false
	}
	// Port must be a iny <= 65535.
	if portNum, err := strconv.ParseInt(
	port, 10, 32,
	); err != nil || portNum > 65535 || portNum < 1 {
	return false
	}
	// If IP address is specified, it should match a valid IPv4 address
	if ip != "" {
	// we need to support older Golang versions, so we can not use netip.ParseAddr
	parsedIp := net.ParseIP(ip)
	return parsedIp != nil && parsedIp.To4() != nil
	}
	return true
	host, port, err := net.SplitHostPort(val)
	if err != nil {
	return false
	}
	// Validate port range (1-65535).
	if portNum, err := strconv.ParseUInt(port, 10, 32,); err != nil || portNum < 1 || portNum > 65535 {
	return false
	}
	// If no host is specified, return true (valid)
	if host == "" {
	return true
	}
	// Parse and validate IPv4 address
	ip := net.ParseIP(host)
	return ip != nil && ip.To4() != nil