[WIP] Linux: set broadcast flag by default for ipvlan interfaces.

src/common.h

@@ -63,6 +63,10 @@
 #define ROUNDUP4(a)		(1 + (((a) - 1) |  3))
 #define ROUNDUP8(a)		(1 + (((a) - 1) |  7))
 
+#ifndef FIELD_SIZEOF
+#define FIELD_SIZEOF(t, f) sizeof(((t *)0)->f)
+#endif
+
 /* Some systems don't define timespec macros */
 #ifndef timespecclear
 #define timespecclear(tsp)      (tsp)->tv_sec = (time_t)((tsp)->tv_nsec = 0L)

src/dhcpcd.8.in

@@ -651,7 +651,7 @@ of a randomly generated number.
 .It Fl J , Fl Fl broadcast
 Instructs the DHCP server to broadcast replies back to the client.
 Normally this is only set for non-Ethernet interfaces,
-such as FireWire and InfiniBand.
+such as FireWire and InfiniBand, and on Linux-based systems for ipvlan as well.
 In most instances,
 .Nm
 will set this automatically.

src/dhcpcd.c

@@ -470,7 +470,7 @@ configure_interface1(struct interface *ifp)
 
 	if (!(ifo->options & DHCPCD_IAID)) {
 		/*
-		 * An IAID is for identifying a unqiue interface within
+		 * An IAID is for identifying an unique interface within
 		 * the client. It is 4 bytes long. Working out a default
 		 * value is problematic.
 		 *

src/if-linux.c

@@ -42,6 +42,7 @@
 #include <linux/if_vlan.h>
 #include <linux/filter.h>
 #include <linux/netlink.h>
+#include <linux/ethtool.h> /* for ipvlan detection */
 #include <linux/sockios.h>
 #include <linux/rtnetlink.h>
 
@@ -309,12 +310,55 @@ if_init(struct interface *ifp)
 	return if_writepathuint(ifp->ctx, path, 1) == -1 ? -1 : 0;
 }
 
+/* Returns number of bytes written to driver, else 0 (error or indeterminate). */
+static size_t
+if_get_driver(struct interface *ifp, char *driver, const size_t driverlen)
+{
+	struct ethtool_drvinfo drvinfo = { .cmd = ETHTOOL_GDRVINFO };
+	struct ifreq ifr = { .ifr_data = (void *)&drvinfo };
+
+	strlcpy(ifr.ifr_name, ifp->name, sizeof(ifr.ifr_name));
+	if (ioctl(ifp->ctx->pf_inet_fd, SIOCETHTOOL, &ifr) != 0) {
+		logerr("%s: SIOCETHTOOL ifname=%s", __func__, ifp->name);
+		return 0; /* 0 means error or indeterminate driver name */
+	}
+	return strlcpy(driver, drvinfo.driver, driverlen);
+}
+
+static bool
+if_cmp_driver(struct interface *ifp, const char *driver)
+{
+	char ifdriver[FIELD_SIZEOF(struct ethtool_drvinfo, driver)];
+	size_t n = if_get_driver(ifp, ifdriver, sizeof(ifdriver));
+
+	if (n == 0) {
+		logerr("%s: if_get_driver ifname=%s", __func__, ifp->name);
+		return false;
+	}
+	if (strncmp(ifdriver, driver, n) == 0)
+		return true;
+	return false;
+}
+
+static bool
+if_ipvlan(struct interface *ifp)
+{
+	if (if_cmp_driver(ifp, "ipvlan"))
+		return true;
+	return false;
+}
+
 int
 if_conf(struct interface *ifp)
 {
 	char path[sizeof(SYS_LAYER2) + IF_NAMESIZE];
 	int n;
 
+	/* Set broadcast flag for ipvlan interfaces.
+	 * XXX: move this out to dhcpcd if needed on other platforms. */
+	if (if_ipvlan(ifp))
+		ifp->options->options |= DHCPCD_BROADCAST;
+
 	/* Some qeth setups require the use of the broadcast flag. */
 	snprintf(path, sizeof(path), SYS_LAYER2, ifp->name);
 	n = check_proc_int(ifp->ctx, path);