dhcpcd-discuss

Hi,

OS info: OpenBSD 6.6 stable
DHCPCD version: dhcpcd-8.0.6 (installed from OpenBSD ports tree)

Recently I found that dhcpcd was having issues detecting a vlan 
interface entering the "up" state after unplugging and re-plugging the 
Ethernet cable.

After some debug, I found that RTM_IFINFO handler in src/if-bsd.c was 
treating the OpenBSD specific LINK_STATE_HALF_DUPLEX and 
LINK_STATE_FULL_DUPLEX values of "ifi_link_state" as "LINK_DOWN" states, 
due to them missing in the switch statement.

--------8<--- OpenBSD's net/if.h [1] -----------
#define LINK_STATE_UP		4	/* link is up */
#define LINK_STATE_HALF_DUPLEX	5	/* link is up and half duplex */
#define LINK_STATE_FULL_DUPLEX	6	/* link is up and full duplex */
--------8<--------------

Please find a patch that addresses this issue below.

cat patches/patch-src_if-bsd_c
--------8<--------------
$OpenBSD$

Index: src/if-bsd.c
--- src/if-bsd.c.orig
+++ src/if-bsd.c
@@ -1068,6 +1068,10 @@ if_ifinfo(struct dhcpcd_ctx *ctx, const struct 
if_msgh
                link_state = LINK_UNKNOWN;
                break;
        case LINK_STATE_UP:
+#if defined(__OpenBSD__)
+       case LINK_STATE_HALF_DUPLEX:
+       case LINK_STATE_FULL_DUPLEX:
+#endif
                link_state = LINK_UP;
                break;
        default:
--------8<--------------

I saw that there was also a LINK_STATE_IS_UP macro defined in OpenBSD's 
"/usr/include/net/if.h" [1], but since dhcpcd seemed to already be 
tracking the "UNKNOWN" state independently from up / down, I went with 
the approach above. I BCCed Stuart Henderson (the OpenBSD dhcpcd port 
maintainer), hoping he will chime in if he prefers a different approach.

Thanks,
Nate

[1] https://github.com/openbsd/src/blob/master/sys/net/if.h#L146