BSD: Detect initial link state in ifa_data

Not all interfaces report media state to get the link state.
However, link state is available from getifaddrs(3) ifa_data
for AF_LINK addresses.

Testing shows that link state is also sent correctly via
route(4) messages for the same interface.

This makes pppoe(4) interfaces more reliable on FreeBSD and OpenBSD.

src/if-bsd.c

@@ -369,13 +369,34 @@ if_carrier(struct interface *ifp)
 		return LINK_UNKNOWN;
 
 	strlcpy(ifmr.ifm_name, ifp->name, sizeof(ifmr.ifm_name));
-	if (ioctl(ifp->ctx->pf_inet_fd, SIOCGIFMEDIA, &ifmr) == -1 ||
-	    !(ifmr.ifm_status & IFM_AVALID))
+	if (ioctl(ifp->ctx->pf_inet_fd, SIOCGIFMEDIA, &ifmr) == -1)
+		return LINK_UNKNOWN;
+
+	if (!(ifmr.ifm_status & IFM_AVALID))
 		return LINK_UNKNOWN;
 
 	return (ifmr.ifm_status & IFM_ACTIVE) ? LINK_UP : LINK_DOWN;
 }
 
+int
+if_carrier_ifadata(struct interface *ifp, void *ifadata)
+{
+	int carrier = if_carrier(ifp);
+	struct if_data *ifdata;
+
+	if (carrier != LINK_UNKNOWN || ifadata == NULL)
+		return carrier;
+
+	ifdata = ifadata;
+	switch (ifdata->ifi_link_state) {
+	case LINK_STATE_DOWN:
+		return LINK_DOWN;
+	case LINK_STATE_UP:
+		return LINK_UP;
+	}
+	return LINK_UNKNOWN;
+}
+
 static void
 if_linkaddr(struct sockaddr_dl *sdl, const struct interface *ifp)
 {

src/if-linux.c

@@ -517,6 +517,13 @@ if_carrier(struct interface *ifp)
 	return ifp->flags & IFF_RUNNING ? LINK_UP : LINK_DOWN;
 }
 
+int
+if_carrier_ifadata(struct interface *ifp, __unused void *ifadata)
+{
+
+	return if_carrier(ifp);
+}
+
 int
 if_getnetlink(struct dhcpcd_ctx *ctx, struct iovec *iov, int fd, int flags,
     int (*cb)(struct dhcpcd_ctx *, void *, struct nlmsghdr *), void *cbarg)

src/if-sun.c

@@ -245,6 +245,13 @@ err:
 	return LINK_UNKNOWN;
 }
 
+int
+if_carrier_ifadata(struct interface *ifp, __unused void *ifadata)
+{
+
+	return if_carrier(ifp);
+}
+
 int
 if_mtu_os(const struct interface *ifp)
 {

src/if.c

@@ -684,7 +684,7 @@ if_discover(struct dhcpcd_ctx *ctx, struct ifaddrs **ifaddrs,
 #endif
 
 		ifp->active = active;
-		ifp->carrier = if_carrier(ifp);
+		ifp->carrier = if_carrier_ifadata(ifp, ifa->ifa_data);
 		TAILQ_INSERT_TAIL(ifs, ifp, next);
 	}
 

src/if.h

@@ -160,6 +160,7 @@ int if_domtu(const struct interface *, short int);
 #define if_getmtu(ifp) if_domtu((ifp), 0)
 #define if_setmtu(ifp, mtu) if_domtu((ifp), (mtu))
 int if_carrier(struct interface *);
+int if_carrier_ifadata(struct interface *, void *);
 int if_pollinit(struct interface *ifp);
 
 #ifdef ALIAS_ADDR