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, 31 insertions, 1 deletions

diff --git a/cmd/podman/common/util.go b/cmd/podman/common/util.go
index a3626b4e4..0d9f3ba26 100644
--- a/cmd/podman/common/util.go
+++ b/cmd/podman/common/util.go
@@ -71,14 +71,44 @@ func createPortBindings(ports []string) ([]specgen.PortMapping, error) {
 			return nil, errors.Errorf("invalid port format - protocol can only be specified once")
 		}
 
-		splitPort := strings.Split(splitProto[0], ":")
+		remainder := splitProto[0]
+		haveV6 := false
+
+		// Check for an IPv6 address in brackets
+		splitV6 := strings.Split(remainder, "]")
+		switch len(splitV6) {
+		case 1:
+			// Do nothing, proceed as before
+		case 2:
+			// We potentially have an IPv6 address
+			haveV6 = true
+			if !strings.HasPrefix(splitV6[0], "[") {
+				return nil, errors.Errorf("invalid port format - IPv6 addresses must be enclosed by []")
+			}
+			if !strings.HasPrefix(splitV6[1], ":") {
+				return nil, errors.Errorf("invalid port format - IPv6 address must be followed by a colon (':')")
+			}
+			ipNoPrefix := strings.TrimPrefix(splitV6[0], "[")
+			hostIP = &ipNoPrefix
+			remainder = strings.TrimPrefix(splitV6[1], ":")
+		default:
+			return nil, errors.Errorf("invalid port format - at most one IPv6 address can be specified in a --publish")
+		}
+
+		splitPort := strings.Split(remainder, ":")
 		switch len(splitPort) {
 		case 1:
+			if haveV6 {
+				return nil, errors.Errorf("invalid port format - must provide host and destination port if specifying an IP")
+			}
 			ctrPort = splitPort[0]
 		case 2:
 			hostPort = &(splitPort[0])
 			ctrPort = splitPort[1]
 		case 3:
+			if haveV6 {
+				return nil, errors.Errorf("invalid port format - when v6 address specified, must be [ipv6]:hostPort:ctrPort")
+			}
 			hostIP = &(splitPort[0])
 			hostPort = &(splitPort[1])
 			ctrPort = splitPort[2]