From bb7cc9739c4e92e465ebae1bdf88029dc6f31244 Mon Sep 17 00:00:00 2001
From: crusader <crusader@atgame.net>
Date: Wed, 22 Aug 2018 15:10:45 +0900
Subject: [PATCH] wrapper for net.ip

---
 net/ip.go    |  64 +++++++++++++++++++++++++++++++
 net/ipnet.go | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 169 insertions(+)
 create mode 100644 net/ip.go
 create mode 100644 net/ipnet.go

diff --git a/net/ip.go b/net/ip.go
new file mode 100644
index 0000000..88d07a1
--- /dev/null
+++ b/net/ip.go
@@ -0,0 +1,64 @@
+package net
+
+import (
+	"net"
+)
+
+// Sub class net.IP so that we can add JSON marshalling and unmarshalling.
+type IP struct {
+	net.IP
+}
+
+// ParseIP returns an IP from a string
+func ParseIP(ip string) *IP {
+	addr := net.ParseIP(ip)
+	if addr == nil {
+		return nil
+	}
+	// Always return IPv4 values as 4-bytes to be consistent with IPv4 IPNet
+	// representations.
+	if addr4 := addr.To4(); addr4 != nil {
+		addr = addr4
+	}
+	return &IP{addr}
+}
+
+// Version returns the IP version for an IP, or 0 if the IP is not valid.
+func (i *IP) Version() int {
+	if i.To4() != nil {
+		return 4
+	} else if len(i.IP) == net.IPv6len {
+		return 6
+	}
+	return 0
+}
+
+// Network returns the IP address as a fully masked IPNet type.
+func (i *IP) Network() *IPNet {
+	// Unmarshaling an IPv4 address returns a 16-byte format of the
+	// address, so convert to 4-byte format to match the mask.
+	n := &IPNet{}
+	if ip4 := i.IP.To4(); ip4 != nil {
+		n.IP = ip4
+		n.Mask = net.CIDRMask(net.IPv4len*8, net.IPv4len*8)
+	} else {
+		n.IP = i.IP
+		n.Mask = net.CIDRMask(net.IPv6len*8, net.IPv6len*8)
+	}
+	return n
+}
+
+// MustParseIP parses the string into a IP.
+func MustParseIP(i string) IP {
+	var ip IP
+	err := ip.UnmarshalText([]byte(i))
+	if err != nil {
+		panic(err)
+	}
+	// Always return IPv4 values as 4-bytes to be consistent with IPv4 IPNet
+	// representations.
+	if ip4 := ip.To4(); ip4 != nil {
+		ip.IP = ip4
+	}
+	return ip
+}
diff --git a/net/ipnet.go b/net/ipnet.go
new file mode 100644
index 0000000..f75b5c2
--- /dev/null
+++ b/net/ipnet.go
@@ -0,0 +1,105 @@
+package net
+
+import (
+	"net"
+)
+
+// Sub class net.IPNet so that we can add JSON marshalling and unmarshalling.
+type IPNet struct {
+	net.IPNet
+}
+
+// Version returns the IP version for an IPNet, or 0 if not a valid IP net.
+func (i *IPNet) Version() int {
+	if i.IP.To4() != nil {
+		return 4
+	} else if len(i.IP) == net.IPv6len {
+		return 6
+	}
+	return 0
+}
+
+// IsNetOverlap is a utility function that returns true if the two subnet have an overlap.
+func (i *IPNet) IsNetOverlap(n net.IPNet) bool {
+	return n.Contains(i.IP) || i.Contains(n.IP)
+}
+
+// Network returns the masked IP network.
+func (i *IPNet) Network() *IPNet {
+	_, n, _ := ParseCIDR(i.String())
+	return n
+}
+
+func ParseCIDR(c string) (*IP, *IPNet, error) {
+	netIP, netIPNet, e := net.ParseCIDR(c)
+	if netIPNet == nil || e != nil {
+		return nil, nil, e
+	}
+	ip := &IP{netIP}
+	ipnet := &IPNet{*netIPNet}
+
+	// The base golang net library always uses a 4-byte IPv4 address in an
+	// IPv4 IPNet, so for uniformity in the returned types, make sure the
+	// IP address is also 4-bytes - this allows the user to safely assume
+	// all IP addresses returned by this function use the same encoding
+	// mechanism (not strictly required but better for testing and debugging).
+	if ip4 := ip.IP.To4(); ip4 != nil {
+		ip.IP = ip4
+	}
+
+	return ip, ipnet, nil
+}
+
+// Parse a CIDR or an IP address and return the IP, CIDR or error.  If an IP address
+// string is supplied, then the CIDR returned is the fully masked IP address (i.e /32 or /128)
+func ParseCIDROrIP(c string) (*IP, *IPNet, error) {
+	// First try parsing as a CIDR.
+	ip, cidr, err := ParseCIDR(c)
+	if err == nil {
+		return ip, cidr, nil
+	}
+
+	// That failed, so try parsing as an IP.
+	ip = &IP{}
+	if err2 := ip.UnmarshalText([]byte(c)); err2 == nil {
+		if ip4 := ip.IP.To4(); ip4 != nil {
+			ip.IP = ip4
+		}
+		n := ip.Network()
+		return ip, n, nil
+	}
+
+	// That failed too, return the original error.
+	return nil, nil, err
+}
+
+// String returns a friendly name for the network.  The standard net package
+// implements String() on the pointer, which means it will not be invoked on a
+// struct type, so we re-implement on the struct type.
+func (i *IPNet) String() string {
+	ip := &i.IPNet
+	return ip.String()
+}
+
+// MustParseNetwork parses the string into a IPNet.  The IP address in the
+// IPNet is masked.
+func MustParseNetwork(c string) IPNet {
+	_, cidr, err := ParseCIDR(c)
+	if err != nil {
+		panic(err)
+	}
+	return *cidr
+}
+
+// MustParseCIDR parses the string into a IPNet.  The IP address in the
+// IPNet is not masked.
+func MustParseCIDR(c string) IPNet {
+	ip, cidr, err := ParseCIDR(c)
+	if err != nil {
+		panic(err)
+	}
+	n := IPNet{}
+	n.IP = ip.IP
+	n.Mask = cidr.Mask
+	return n
+}