conf: Allow binding to ports on an interface without a specific address

Somebody might want to bind listening sockets to a specific
interface, but not a specific address, and there isn't really a
reason to prevent that. For example:

  -t %eth0/2022

Alternatively, we support options such as -t 0.0.0.0%eth0/2022 and
-t ::%eth0/2022, but not together, for the same port.

Enable this kind of syntax and add examples to the man page.

Reported-by: Paul Holzinger <pholzing@redhat.com>
Link: https://github.com/containers/podman/issues/14425#issuecomment-1485192195
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/conf.c b/conf.c
index 04e9956..f519a6a 100644
--- a/conf.c
+++ b/conf.c
@@ -263,7 +263,9 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 			ifname++;
 		}
 
-		if (inet_pton(AF_INET, buf, addr))
+		if (ifname == buf + 1)		/* Interface without address */
+			addr = NULL;
+		else if (inet_pton(AF_INET, buf, addr))
 			af = AF_INET;
 		else if (inet_pton(AF_INET6, buf, addr))
 			af = AF_INET6;