refactor: Optimize device check code, reuse it.

src/config.c

@@ -1,15 +1,15 @@
 /* IPwatchD - IP conflict detection tool for Linux
  * Copyright (C) 2007-2018 Jaroslav Imrich <jariq(at)jariq(dot)sk>
- * 
+ *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * version 2 as published by the Free Software Foundation.
- *  
+ *
  * 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,
@@ -70,9 +70,6 @@ int ipwd_read_config (const char *filename)
 	char variable[100];
 	char value[400];
 
-	pcap_t *h_pcap = NULL;
-	char errbuf[PCAP_ERRBUF_SIZE];
-
 	int iface_len = 0;
 
 	// Initialize structures with default values
@@ -224,7 +221,7 @@ int ipwd_read_config (const char *filename)
 				ipwd_message (IPWD_MSG_TYPE_ERROR, "Configuration parse error : file %s specified as user_script does not exist", value);
 				return (IPWD_RV_ERROR);
 			}
-	
+
 			if ((config.script = (char *) malloc ((strlen (value) + 1) * sizeof (char))) == NULL)
 			{
 				ipwd_message (IPWD_MSG_TYPE_ERROR, "Configuration parse error : malloc for user_script failed");
@@ -293,23 +290,13 @@ int ipwd_read_config (const char *filename)
 				ipwd_message (IPWD_MSG_TYPE_ERROR, "Not enough parameters in configuration file on line %d", linenum);
 				return (IPWD_RV_ERROR);
 			}
-
-			/* Check if device is valid ethernet device */
-			h_pcap = pcap_open_live (variable, BUFSIZ, 0, 0, errbuf);
-			if (h_pcap == NULL)
-			{
-				ipwd_message (IPWD_MSG_TYPE_ERROR, "IPwatchD is unable to work with interface \"%s\"", variable);
-				return (IPWD_RV_ERROR);
-			}
 
-			if (pcap_datalink (h_pcap) != DLT_EN10MB)
+			/* Check if device is valid ethernet device */
+			if (ipwd_check_dev (variable) != IPWD_RV_SUCCESS)
 			{
-				ipwd_message (IPWD_MSG_TYPE_ERROR, "Device \"%s\" is not valid ethernet interface", variable);
 				return (IPWD_RV_ERROR);
 			}
 
-			pcap_close (h_pcap);
-
 			/* Check mode value */
 			if ((strcasecmp (value, "active") != 0) && (strcasecmp (value, "passive") != 0))
 			{

src/devinfo.c

@@ -132,12 +132,8 @@ int ipwd_fill_devices (void)
 	int ifaces_num = 0;
 	int i = 0;
 
-	pcap_t *h_pcap = NULL;
-	char errbuf[PCAP_ERRBUF_SIZE];
-
 	memset (ifaces_buf, 0, sizeof (ifaces_buf));
 	memset (&ifc, 0, sizeof (ifc));
-	memset (errbuf, 0, PCAP_ERRBUF_SIZE);
 
 	/* Verify that devices structure is empty and configuration mode is automatic */
 	if ((devices.dev != NULL) || (devices.devnum != 0) || (config.mode != IPWD_CONFIGURATION_MODE_AUTOMATIC))
@@ -191,22 +187,11 @@ int ipwd_fill_devices (void)
 		}
 
 		/* Check if device is valid ethernet device */
-		h_pcap = pcap_open_live (iface->ifr_name, BUFSIZ, 0, 0, errbuf);
-		if (h_pcap == NULL)
-		{
-			ipwd_message (IPWD_MSG_TYPE_ERROR, "IPwatchD is unable to work with device \"%s\"", iface->ifr_name);
-			continue;
-		}
-
-		if (pcap_datalink (h_pcap) != DLT_EN10MB)
+		if (ipwd_check_dev (iface->ifr_name) != IPWD_RV_SUCCESS) 
 		{
-			ipwd_message (IPWD_MSG_TYPE_ERROR, "Device \"%s\" is not valid ethernet device", iface->ifr_name);
-			pcap_close (h_pcap);
 			continue;
 		}
 
-		pcap_close (h_pcap);
-
 		/* Put read values into devices structure */
 		if ((devices.dev = (IPWD_S_DEV *) realloc (devices.dev, (devices.devnum + 1) * sizeof (IPWD_S_DEV))) == NULL)
 		{
@@ -236,3 +221,34 @@ int ipwd_fill_devices (void)
 
 }
 
+
+//! Check if device is valid ethernet device
+/*!
+ * \param p_dev Name of the device (i.e. eth0)
+ * \return IPWD_RV_SUCCESS if successful IPWD_RV_ERROR otherwise
+ */
+int ipwd_check_dev (const char* p_dev)
+{
+	pcap_t *h_pcap = NULL;
+	char errbuf[PCAP_ERRBUF_SIZE];
+
+	memset (errbuf, 0, PCAP_ERRBUF_SIZE);
+
+	h_pcap = pcap_open_live (p_dev, BUFSIZ, 0, 0, errbuf);
+	if (h_pcap == NULL)
+	{
+		ipwd_message (IPWD_MSG_TYPE_ERROR, "IPwatchD is unable to work with interface \"%s\"", p_dev);
+		return (IPWD_RV_ERROR);
+	}
+
+	if (pcap_datalink (h_pcap) != DLT_EN10MB)
+	{
+		ipwd_message (IPWD_MSG_TYPE_ERROR, "Device \"%s\" is not valid ethernet interface", p_dev);
+		return (IPWD_RV_ERROR);
+	}
+
+	pcap_close (h_pcap);
+
+	return IPWD_RV_SUCCESS;
+
+}

src/ipwatchd.h

@@ -190,6 +190,7 @@ int ipwd_check_pidfile (void);
 /* devinfo.c */
 int ipwd_devinfo (const char *p_dev, char *p_ip, char *p_mac);
 int ipwd_fill_devices (void);
+int ipwd_check_dev (const char *p_dev);
 
 /* genarp.c */
 int ipwd_genarp (const char *dev, const char *p_sip, const char *p_smac, const char *p_dip, const char *p_dmac, int opcode);