add getLinkStatus to determine whether an interface has an active link

1 files changed, 103 insertions, 0 deletions

diff --git a/isys/linkdetect.c b/isys/linkdetect.c
new file mode 100644
index 000000000..466cfd60d
--- /dev/null
+++ b/isys/linkdetect.c
@@ -0,0 +1,103 @@
+/*
+ * linkdetect.c - simple link detection
+ *
+ * heavily based on mii-tool.c from net-tools, just cut down to what we need
+ * for anaconda
+ *
+ * Copyright 2002 Red Hat, Inc.
+ * Copyright 2000 David A. Hinds -- dhinds@pcmcia.sourceforge.org
+ *
+ * Jeremy Katz <katzj@redhat.com>
+ *
+ * This software may be freely redistributed under the terms of the GNU
+ * general public license.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include <net/if.h>
+
+#include "mii.h"
+
+static struct ifreq ifr;
+
+static int mdio_read(int skfd, int location)
+{
+    struct mii_data *mii = (struct mii_data *)&ifr.ifr_data;
+    mii->reg_num = location;
+    if (ioctl(skfd, SIOCGMIIREG, &ifr) < 0) {
+	fprintf(stderr, "SIOCGMIIREG on %s failed: %s\n", ifr.ifr_name,
+		strerror(errno));
+	return -1;
+    }
+    return mii->val_out;
+}
+
+/* we don't need writing right now */
+#if 0
+static void mdio_write(int skfd, int location, int value)
+{
+    struct mii_data *mii = (struct mii_data *)&ifr.ifr_data;
+    mii->reg_num = location;
+    mii->val_in = value;
+    if (ioctl(skfd, SIOCSMIIREG, &ifr) < 0) {
+	fprintf(stderr, "SIOCSMIIREG on %s failed: %s\n", ifr.ifr_name,
+		strerror(errno));
+    }
+}
+#endif
+
+
+
+int get_link_status(char *ifname) {
+    struct mii_data *mii = (struct mii_data *)&ifr.ifr_data;
+    int sock, i, mii_val[32];
+
+    if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+        fprintf(stderr, "Error creating socket: %s\n", strerror(errno));
+        return -1;
+    }
+
+    /* Get the vitals from the interface. */
+    strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
+    if (ioctl(sock, SIOCGMIIPHY, &ifr) < 0) {
+	if (errno != ENODEV)
+	    fprintf(stderr, "SIOCGMIIPHY on '%s' failed: %s\n",
+		    ifname, strerror(errno));
+	return -1;
+    }
+
+    /* Some bits in the BMSR are latched, but we can't rely on being
+       the only reader, so only the current values are meaningful */
+    mdio_read(sock, MII_BMSR);
+    for (i = 0; i < 8; i++)
+	mii_val[i] = mdio_read(sock, i);
+
+    if (mii_val[MII_BMCR] == 0xffff) {
+	fprintf(stderr, "  No MII transceiver present!.\n");
+	return -1;
+    }
+
+    if (mii_val[MII_BMSR] & MII_BMSR_LINK_VALID)
+        return 1;
+    else
+        return 0;
+}
+
+#ifdef STANDALONE
+/* hooray for stupid test programs! */
+int main(int argc, char **argv) {
+    printf("link status of eth0 is %d\n", get_link_status("eth0"));
+}
+#endif