1 files changed, 46 insertions, 0 deletions
diff --git a/mtu.c b/mtu.c
new file mode 100644
index 0000000..975bf0e
--- /dev/null
+++ b/mtu.c
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2011 Daniel Drown
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * mtu.c - get interface mtu
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <net/if.h>
+
+#include "mtu.h"
+
+/* function: getifmtu
+ * returns the interface mtu or -1 on failure
+ * ifname - interface name
+ */
+int getifmtu(const char *ifname) {
+  int fd;
+  struct ifreq if_mtu;
+
+  fd = socket(AF_INET, SOCK_STREAM, 0);
+  if(fd < 0) {
+    return -1;
+  }
+  strncpy(if_mtu.ifr_name, ifname, IFNAMSIZ);
+  if_mtu.ifr_name[IFNAMSIZ - 1] = '\0';
+  if(ioctl(fd, SIOCGIFMTU, &if_mtu) < 0) {
+    return -1;
+  }
+  return if_mtu.ifr_mtu;
+}