[PATCH] conf: Don't fail if the template interface doesn't have a MAC address

[PATCH] conf: Don't fail if the template interface doesn't have a MAC address

[Stefano Brivio]

...simply resort to using locally-administered address (LAA) as
host-side source, instead.

Pick 02:00:00:00:00:00, to make it clear that we don't actually care
about that address, and also to matchthe 00 (Administratively Assigned
Identifier) quadrant of SLAP (RFC 8948).

Otherwise, pasta refuses to start if the template is a tun or
Wireguard interface.

Link: https://bugs.passt.top/show_bug.cgi?id=49
Link: https://github.com/containers/podman/issues/22320
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 conf.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/conf.c b/conf.c
index 90d3436..3f30725 100644
--- a/conf.c
+++ b/conf.c
@@ -629,10 +629,12 @@ static unsigned int conf_ip4(unsigned int ifi,
 			    if_indextoname(ifi, ifname), strerror(-rc));
 			return 0;
 		}
+
+		if (MAC_IS_ZERO(mac))
+			memcpy(mac, MAC_LAA, ETH_ALEN);
 	}
 
-	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr) ||
-	    MAC_IS_ZERO(mac))
+	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr))
 		return 0;
 
 	return ifi;
@@ -688,11 +690,13 @@ static unsigned int conf_ip6(unsigned int ifi,
 			    if_indextoname(ifi, ifname), strerror(-rc));
 			return 0;
 		}
+
+		if (MAC_IS_ZERO(mac))
+			memcpy(mac, MAC_LAA, ETH_ALEN);
 	}
 
 	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ||
-	    IN6_IS_ADDR_UNSPECIFIED(&ip6->addr_ll) ||
-	    MAC_IS_ZERO(mac))
+	    IN6_IS_ADDR_UNSPECIFIED(&ip6->addr_ll))
 		return 0;
 
 	return ifi;
-- 
@@ -629,10 +629,12 @@ static unsigned int conf_ip4(unsigned int ifi,
 			    if_indextoname(ifi, ifname), strerror(-rc));
 			return 0;
 		}
+
+		if (MAC_IS_ZERO(mac))
+			memcpy(mac, MAC_LAA, ETH_ALEN);
 	}
 
-	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr) ||
-	    MAC_IS_ZERO(mac))
+	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr))
 		return 0;
 
 	return ifi;
@@ -688,11 +690,13 @@ static unsigned int conf_ip6(unsigned int ifi,
 			    if_indextoname(ifi, ifname), strerror(-rc));
 			return 0;
 		}
+
+		if (MAC_IS_ZERO(mac))
+			memcpy(mac, MAC_LAA, ETH_ALEN);
 	}
 
 	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ||
-	    IN6_IS_ADDR_UNSPECIFIED(&ip6->addr_ll) ||
-	    MAC_IS_ZERO(mac))
+	    IN6_IS_ADDR_UNSPECIFIED(&ip6->addr_ll))
 		return 0;
 
 	return ifi;
-- 
2.43.0