1 files changed, 32 insertions, 2 deletions

diff --git a/devices.c b/devices.c
index 9293783..b7c1254 100644
--- a/devices.c
+++ b/devices.c
@@ -1,3 +1,21 @@
+/*
+    Mac-Telnet - Connect to RouterOS clients via MAC address
+    Copyright (C) 2010, Håkon Nessjøen <haakon.nessjoen@gmail.com>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    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.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
 #include <stdlib.h>
 #include <string.h>
 #include <malloc.h>
@@ -7,6 +25,8 @@
 #include <sys/ioctl.h>
 #include <net/if.h>
 
+/* Functions using NETDEVICE api */
+
 int getDeviceIndex(int sockfd, unsigned char *deviceName) {
 	struct ifreq ifr;
 
@@ -15,6 +35,7 @@ int getDeviceIndex(int sockfd, unsigned char *deviceName) {
 		return -1;
 	}
 
+	/* Return interface index */
 	return ifr.ifr_ifindex;
 }
 
@@ -26,8 +47,8 @@ int getDeviceMAC(const int sockfd, const unsigned char *deviceName, unsigned cha
 		return -1;
 	}
 
+	/* Fetch mac address */
 	memcpy(mac, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
-
 	return 1;
 }
 
@@ -36,26 +57,35 @@ int getDeviceIp(const int sockfd, const unsigned char *deviceName, struct sockad
 	struct ifreq *ifr;
 	int i,numDevices;
 
+	/*
+	 * Do a initial query without allocating ifreq structs
+	 * to count the number of ifreq structs to allocate memory for
+	*/
 	memset(&ifc, 0, sizeof(ifc));
 	if (ioctl(sockfd, SIOCGIFCONF, &ifc) != 0) {
 		return -1;
 	}
 
+	/*
+	 * Allocate memory for interfaces, multiply by two in case
+	 * the number of interfaces has increased since last ioctl
+	*/
 	if ((ifr = malloc(ifc.ifc_len * 2)) == NULL) {
 		perror("malloc");
 		exit(1);
 	}
 
 	ifc.ifc_req = ifr;
-
 	if (ioctl(sockfd, SIOCGIFCONF, &ifc) != 0) {
 		free(ifr);
 		return -1;
 	}
 
+	/* Iterate through all devices, searching for interface */
 	numDevices = ifc.ifc_len / sizeof(struct ifreq);
 	for (i = 0; i < numDevices; ++i) {
 		if (strcmp(ifr[i].ifr_name, deviceName) == 0) {
+			/* Fetch IP for found interface */
 			memcpy(ip, &(ifr[i].ifr_addr), sizeof(ip));
 			free(ifr);
 			return 1;