Linux: set broadcast flag by default for ipvlan interfaces.

Author: ido

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 for ipvlan interfaces.
 In most instances,
 .Nm
 will set this automatically.

src/if-linux.c

@@ -310,47 +310,57 @@ if_init(struct interface *ifp)
 	return if_writepathuint(ifp->ctx, path, 1) == -1 ? -1 : 0;
 }
 
-/* @maxlen should be greater than or equal to 32; see ethtool_drvinfo. */
-static int
-if_get_driver(const char *ifname, char *driver, const size_t maxlen)
+/* Returns number of bytes written to driver, 0 on error.
+ * @driverlen note that sizeof(ethtool_drvinfo.driver) = 32 */
+static size_t
+if_get_driver(const char *ifname, char *driver, const size_t driverlen)
 {
-	struct ifreq ifr;
+	struct ifreq ifr = { .ifr_flags = 0 };
 	struct ethtool_drvinfo drvinfo;
 	int fd;
-	if (!ifname || !*ifname)
-		return -1;
+	size_t n = 0;
 
 	fd = socket(AF_INET, SOCK_STREAM, 0);
 	if (fd == -1) {
-		logerr("if_get_driver: failed socket creation: %s", strerror(errno));
-		return -1;
+		logerr("%s: socket ifname=%s", __func__, ifname);
+		goto eexit;
 	}
-
 	memset(&ifr, 0, sizeof(ifr));
 	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 	drvinfo.cmd = ETHTOOL_GDRVINFO;
 	ifr.ifr_data = (void *)&drvinfo;
-	if (ioctl(fd, SIOCETHTOOL, &ifr) < 0) {
-		const int err = errno;
-		logerr("if_get_driver: failed ethtool ioctl on interface %s: %s",
-			ifname, strerror(errno));
-		close(fd);
-		return -1;
+	if (ioctl(fd, SIOCETHTOOL, &ifr) == -1) {
+		logerr("%s: SIOCETHTOOL ifname=%s", __func__, ifname);
+		goto eexit;
 	}
-	close(fd);
-	return strlcpy(driver, drvinfo.driver,
-		MIN(sizeof(drvinfo.driver), maxlen));
+	n = strlcpy(driver, drvinfo.driver, driverlen);
+eexit:
+	if (fd != -1)
+		close(fd);
+	return n;
 }
 
 static bool
-if_ipvlan(const char *ifname)
+if_cmp_driver(const char *ifname, const char *driver)
 {
-	char driver[32]; /* sizeof(ethtool_drvinfo.driver) = 32 */
-	if (if_get_driver(ifname, driver, sizeof(driver)) < 0) {
-		logerr("if_ipvlan: failed to get driver name %s.", ifname);
+	char ifdriver[32]; /* see ethtool_drvinfo.driver declaration */
+	size_t n = if_get_driver(ifname, ifdriver, sizeof(ifdriver));
+
+	if (n == 0) {
+		logerr("%s: if_get_driver ifname=%s", __func__, ifname);
 		return false;
 	}
-	return (strncmp(driver, "ipvlan", sizeof(driver)) == 0);
+	if (strncmp(ifdriver, driver, n) == 0)
+		return true;
+	return false;
+}
+
+static bool
+if_ipvlan(struct interface *ifp)
+{
+	if (if_cmp_driver(ifp->name, "ipvlan"))
+		return true;
+	return false;
 }
 
 int
@@ -359,10 +369,10 @@ if_conf(struct interface *ifp)
 	char path[sizeof(SYS_LAYER2) + IF_NAMESIZE];
 	int n;
 
-	/* Set broadcast flag for ipvlan interfaces. */
-	if (if_ipvlan(ifp->name)) {
+	/* 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);