Enable IPv6 port binding

Two areas needed tweaking to accomplish this: port parsing and
binding ports on the host.

Parsing is an obvious problem - we have to accomodate an IPv6
address enclosed by [] as well as a normal IPv4 address. It was
slightly complicated by the fact that we previously just counted
the number of colons in the whole port definition (a thousand
curses on whoever in the IPv6 standard body decided to reuse
colons for address separators), but did not end up being that
bad.

Libpod also (optionally) binds ports on the host to prevent their
reuse by host processes. This code was IPv4 only for TCP, and
bound to both for UDP (which I'm fairly certain is not correct,
and has been adjusted). This just needed protocols adjusted to
read "tcp4"/"tcp6" and "udp4"/"udp6" based on what we wanted to
bind to.

Fixes #5715

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 32 insertions, 4 deletions

diff --git a/libpod/oci_util.go b/libpod/oci_util.go
index 53567d2d0..8b40dad81 100644
--- a/libpod/oci_util.go
+++ b/libpod/oci_util.go
@@ -36,14 +36,30 @@ func bindPorts(ports []ocicni.PortMapping) ([]*os.File, error) {
 	var files []*os.File
 	notifySCTP := false
 	for _, i := range ports {
+		isV6 := net.ParseIP(i.HostIP).To4() == nil
+		if i.HostIP == "" {
+			isV6 = false
+		}
 		switch i.Protocol {
 		case "udp":
-			addr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", i.HostIP, i.HostPort))
+			var (
+				addr *net.UDPAddr
+				err  error
+			)
+			if isV6 {
+				addr, err = net.ResolveUDPAddr("udp6", fmt.Sprintf("[%s]:%d", i.HostIP, i.HostPort))
+			} else {
+				addr, err = net.ResolveUDPAddr("udp4", fmt.Sprintf("%s:%d", i.HostIP, i.HostPort))
+			}
 			if err != nil {
 				return nil, errors.Wrapf(err, "cannot resolve the UDP address")
 			}
 
-			server, err := net.ListenUDP("udp", addr)
+			proto := "udp4"
+			if isV6 {
+				proto = "udp6"
+			}
+			server, err := net.ListenUDP(proto, addr)
 			if err != nil {
 				return nil, errors.Wrapf(err, "cannot listen on the UDP port")
 			}
@@ -54,12 +70,24 @@ func bindPorts(ports []ocicni.PortMapping) ([]*os.File, error) {
 			files = append(files, f)
 
 		case "tcp":
-			addr, err := net.ResolveTCPAddr("tcp4", fmt.Sprintf("%s:%d", i.HostIP, i.HostPort))
+			var (
+				addr *net.TCPAddr
+				err  error
+			)
+			if isV6 {
+				addr, err = net.ResolveTCPAddr("tcp6", fmt.Sprintf("[%s]:%d", i.HostIP, i.HostPort))
+			} else {
+				addr, err = net.ResolveTCPAddr("tcp4", fmt.Sprintf("%s:%d", i.HostIP, i.HostPort))
+			}
 			if err != nil {
 				return nil, errors.Wrapf(err, "cannot resolve the TCP address")
 			}
 
-			server, err := net.ListenTCP("tcp4", addr)
+			proto := "tcp4"
+			if isV6 {
+				proto = "tcp6"
+			}
+			server, err := net.ListenTCP(proto, addr)
 			if err != nil {
 				return nil, errors.Wrapf(err, "cannot listen on the TCP port")
 			}