13 files changed, 649 insertions, 0 deletions
diff --git a/src/Makefile b/src/Makefile
new file mode 100644
index 0000000..23291a7
--- /dev/null
+++ b/src/Makefile
@@ -0,0 +1,18 @@
+CC=gcc
+CFLAGS+=-O2 -Wall -s
+OBJS=netdt.o arp.o iface.o param.o network.o
+
+all: $(OBJS)
+	$(CC) -I./includes $(CFLAGS) -o netdt $(OBJS)
+netdt.o: netdt.c ./includes/netdt.h ./includes/defs.h
+	$(CC) -I./includes $(CFLAGS) -c -o netdt.o netdt.c
+arp.o: arp.c ./includes/arp.h ./includes/defs.h
+	$(CC) -I./includes $(CFLAGS) -c -o arp.o arp.c
+iface.o: iface.c ./includes/iface.h
+	$(CC) -I./includes $(CFLAGS) -c -o iface.o iface.c
+param.o: param.c ./includes/param.h
+	$(CC) -I./includes $(CFLAGS) -c -o param.o param.c
+network.o: network.c ./includes/network.h
+	$(CC) -I./includes $(CFLAGS) -c -o network.o network.c
+clean:
+	rm -rf netdt $(OBJS)
diff --git a/src/arp.c b/src/arp.c
new file mode 100644
index 0000000..7ad7555
--- /dev/null
+++ b/src/arp.c
@@ -0,0 +1,145 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+ 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netinet/ether.h>
+#include <netinet/if_ether.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netpacket/packet.h>
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "netdt.h"
+#include "defs.h"
+#include "param.h"
+#include "iface.h"
+#include "network.h"
+
+void arp_generate_packet(struct in_addr, struct in_addr, struct ether_addr, u_int8_t *);
+
+int arp_init(int argc, char **argv)
+{
+	PDEBUG("arp_init called\n");
+	
+	extern struct param param;
+	struct in_addr sip, tip, netmask, tmp;
+	int sock_fd;
+	struct sockaddr_ll saddr_ll;
+	socklen_t sa_size = sizeof(struct sockaddr_ll);
+	struct ether_addr mac;
+	struct ether_arp *arp_header;
+	u_int8_t packet[sizeof(struct ether_header) + sizeof(struct ether_arp)];
+	//printf("%d\n", sizeof(packet)); exit(0);
+	
+	/* ETH_ALEN, ARPHDR_ETHER, ETHERTYPE_ARP */
+
+	if ( (sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ARP))) == -1) {
+		PDEBUG("ERROR: socket() failed\n");
+		fprintf(stderr, "Error: can't create socket\n");
+		exit(1);
+	}
+	if (fcntl(sock_fd, F_SETFL, O_NONBLOCK) == -1) {
+		PDEBUG("ERROR: fcntl() failed\n");
+		fprintf(stderr, "Error: can't make socket non-blocking\n");
+		close(sock_fd);
+		exit(1);
+	}
+	
+	iface_init(sock_fd, param.iface);
+
+	if ( (saddr_ll.sll_ifindex = iface_get_index()) == -1) {
+		fprintf(stderr, "Error: no such device %s\n", param.iface);
+		close(sock_fd);
+		exit(1);
+	}
+
+	/*
+	XXX
+	po situ veiksmu reiketu atlikti 
+	patikrinima ar yra teisingas IP adresas
+	*/
+	iface_get_ip(&sip);
+	iface_get_netmask(&netmask);
+	iface_get_mac(&mac);
+	
+	saddr_ll.sll_family = PF_PACKET;
+	saddr_ll.sll_halen = ETH_ALEN;
+	memset(&saddr_ll.sll_addr, 0, ETH_ALEN);
+	
+	net_calc_network(sip, netmask);
+	tip.s_addr = sip.s_addr & netmask.s_addr;
+	arp_header = (struct ether_arp*)(packet + sizeof(struct ether_header));
+	
+	fprintf(stdout, "Discovering network with %s/%s\n\n", inet_ntoa(sip), ether_ntoa(&mac));
+	
+	while ( (tip.s_addr = net_next_ip(tip)) != 0) {
+		//printf("%s\n", inet_ntoa(tip));
+		memset(packet, 0, sizeof(packet));
+		arp_generate_packet(sip, tip, mac, packet);
+		sendto(sock_fd, &packet, 42, 0, (struct sockaddr*)&saddr_ll, sizeof(struct sockaddr_ll));
+		usleep(param.packet_delay * 100);
+		if (recvfrom(sock_fd, &packet, 42, 0, (struct sockaddr*)&saddr_ll, &sa_size) == 42) {
+			if (arp_header->arp_op == htons(ARPOP_REPLY)) {
+				memcpy((void*)&tmp, (void*)&arp_header->arp_spa, 4);
+				fprintf(stdout, "%-15s %s\n", inet_ntoa(tmp),
+						ether_ntoa((struct ether_addr*)&arp_header->arp_sha));
+			}
+		}
+	}
+	return (0);
+}
+
+void arp_generate_packet(struct in_addr sip, struct in_addr tip, struct ether_addr smac, u_int8_t *packet)
+{
+	struct ether_header *eth_header;
+	struct ether_arp *arp_header;
+	
+	eth_header = (struct ether_header*)packet;
+	memset((void*)&eth_header->ether_dhost, 0xff, ETH_ALEN);	/* broadcast */
+	memcpy((void*)&eth_header->ether_shost, (void*)&smac.ether_addr_octet, ETH_ALEN);
+	eth_header->ether_type = htons(ETHERTYPE_ARP);
+	
+	arp_header = (struct ether_arp*)(packet + sizeof(struct ether_header));
+	arp_header->arp_hrd = htons(ARPHRD_ETHER);
+	arp_header->arp_pro = htons(ETHERTYPE_IP);
+	arp_header->arp_hln = ETH_ALEN;
+	arp_header->arp_pln = 4; /* reikia susiziureti ar nera kokios konstantos */
+	arp_header->arp_op = htons(ARPOP_REQUEST);
+	memcpy((void*)arp_header->arp_sha, (void*)&smac.ether_addr_octet, ETH_ALEN);
+	memcpy((void*)arp_header->arp_spa, (void*)&sip.s_addr, 4);
+	memcpy((void*)arp_header->arp_tpa, (void*)&tip.s_addr, 4);
+}
+
+void arp_usage(char *pname)
+{
+	fprintf(stderr, "The Network Discovery Tool " PROGRAM_VERSION " by " PROGRAM_AUTHOR "\n"
+			"Usage: %s arp <options>\n"
+					"Options:\n"
+					" -i <if>   Network interface\n"
+					" -t <time> Delay between packets\n"
+					" -h        Help screen\n"
+					, pname);
+	exit(0);
+}
diff --git a/src/iface.c b/src/iface.c
new file mode 100644
index 0000000..8c67218
--- /dev/null
+++ b/src/iface.c
@@ -0,0 +1,119 @@
+/* 
+ * The Network Discovery Tool
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Ultimate Network Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <netinet/ether.h>
+#include "iface.h"
+#include "defs.h"
+
+struct ifreq iface;
+
+struct interface
+{
+	int index,
+	    mtu,
+	    metric;
+	short flags;
+	struct in_addr ip, netmask, broadcast;
+	struct ether_addr mac;
+	
+} interface;
+	
+void iface_init(int socket, char *name)
+{
+	PDEBUG("iface_init() called\n");
+	memset(&iface, 0, sizeof(struct ifreq));
+	strncpy(iface.ifr_name, name, strlen(name));
+	
+	if (ioctl(socket, SIOCGIFINDEX, &iface) == -1)
+		interface.index = -1;
+	else {
+		interface.index = iface.ifr_ifindex;
+
+		if (ioctl(socket, SIOCGIFADDR, &iface) != -1)
+			//memcpy(&iface_ip, &(((struct sockaddr_in * )&iface.ifr_addr)->sin_addr), 4);
+			interface.ip = ((struct sockaddr_in * )&iface.ifr_addr)->sin_addr;
+
+		if (ioctl(socket, SIOCGIFNETMASK, &iface) != -1)
+			//memcpy(&iface_nmask, &(((struct sockaddr_in * )&iface.ifr_netmask)->sin_addr), 4);
+			interface.netmask = ((struct sockaddr_in * )&iface.ifr_netmask)->sin_addr;
+
+		if (ioctl(socket, SIOCGIFBRDADDR, &iface) != -1)
+			//memcpy(&iface_bcast, &(((struct sockaddr_in * )&iface.ifr_broadaddr)->sin_addr), 4);
+			interface.broadcast = ((struct sockaddr_in * )&iface.ifr_broadaddr)->sin_addr;
+
+		if (ioctl(socket, SIOCGIFHWADDR, &iface) != -1)
+			memcpy((void*)interface.mac.ether_addr_octet, (void*)&iface.ifr_hwaddr.sa_data, 6);
+
+		if (ioctl(socket, SIOCGIFMTU, &iface) != -1)
+			interface.mtu = iface.ifr_mtu;
+		
+		if (ioctl(socket, SIOCGIFFLAGS, &iface) != -1)
+			interface.flags = iface.ifr_flags;
+
+		if (ioctl(socket, SIOCGIFMETRIC, &iface) != -1)
+			interface.metric = iface.ifr_metric;
+	}
+	PDEBUG("iface_init() ended\n");
+}
+
+int inline iface_get_index()
+{
+	return (interface.index);
+}
+
+int inline iface_get_mtu()
+{
+	return (interface.mtu);
+}
+
+int inline iface_get_metric()
+{
+	return (interface.metric);
+}
+
+short inline iface_get_flags()
+{
+	return (interface.flags);
+}
+
+void inline iface_get_ip(struct in_addr *ip)
+{
+	(*ip) = interface.ip;
+}
+
+void inline iface_get_netmask(struct in_addr *netmask)
+{
+	(*netmask) = interface.netmask;
+}
+
+void inline iface_get_broadcast(struct in_addr *broadcast)
+{
+	(*broadcast) = interface.broadcast;
+}
+
+void inline iface_get_mac(struct ether_addr *mac)
+{
+	(*mac) = interface.mac;
+}
diff --git a/src/includes/arp.h b/src/includes/arp.h
new file mode 100644
index 0000000..d012894
--- /dev/null
+++ b/src/includes/arp.h
@@ -0,0 +1,27 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#ifndef __NETDT_ARP_H__
+#define __NETDT_ARP_H__ 1
+
+int arp_init(int, char **);
+void arp_usage(char *);
+
+#endif
diff --git a/src/includes/defs.h b/src/includes/defs.h
new file mode 100644
index 0000000..ac8a07c
--- /dev/null
+++ b/src/includes/defs.h
@@ -0,0 +1,31 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#ifndef __NETDT_DEFS_H__
+#define __NETDT_DEFS_H__ 1
+
+#undef PDEBUG
+#ifdef DEBUG
+#define PDEBUG(format, args...) fprintf(stderr, "DEBUG:%s:%d " format, __FILE__, __LINE__, ## args)
+#else
+#define PDEBUG(format, args...)
+#endif
+
+#endif
diff --git a/src/includes/iface.h b/src/includes/iface.h
new file mode 100644
index 0000000..da2f86a
--- /dev/null
+++ b/src/includes/iface.h
@@ -0,0 +1,39 @@
+/* 
+ * The Network Discovery Tool
+ * Copyright (C) 2005 Virtual Pointer
+ * 
+ * The Ultimate Network Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA. 
+ */
+
+#ifndef __NETDT_IFACE_H__
+#define __NETDT_IFACE_H__ 1
+
+/*
+ * /usr/include/bits/ioctls.h
+ */
+
+/* Initialize global interface variables, call first */
+void iface_init(int, char *);
+int inline iface_get_index();
+int inline iface_get_mtu();
+int inline iface_get_metric();
+short inline iface_get_flags();
+void inline iface_get_ip(struct in_addr *);
+void inline iface_get_netmask(struct in_addr *);
+void inline iface_get_broadcast(struct in_addr *);
+void inline iface_get_mac(struct ether_addr *);
+		
+#endif
diff --git a/src/includes/netdt.h b/src/includes/netdt.h
new file mode 100644
index 0000000..3763d37
--- /dev/null
+++ b/src/includes/netdt.h
@@ -0,0 +1,27 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#ifndef __NETDT_H__
+#define __NETDT_H__ 1
+
+#define PROGRAM_VERSION	"0.0.1"
+#define PROGRAM_AUTHOR	"Tadas Vilkeliskis"
+
+#endif
diff --git a/src/includes/network.h b/src/includes/network.h
new file mode 100644
index 0000000..0b6a984
--- /dev/null
+++ b/src/includes/network.h
@@ -0,0 +1,27 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#ifndef __NETDT_NETWORK_H__
+#define __NETDT_NETWORK_H__ 1
+
+void inline net_calc_network(struct in_addr, struct in_addr);
+in_addr_t net_next_ip(struct in_addr);
+
+#endif
diff --git a/src/includes/param.h b/src/includes/param.h
new file mode 100644
index 0000000..bf5789d
--- /dev/null
+++ b/src/includes/param.h
@@ -0,0 +1,33 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#ifndef __NETDT_PARAM_H__
+#define __NETDT_PARAM_H__ 1
+
+struct param
+{
+	char *iface;
+	int flags;
+	unsigned long packet_delay;
+};
+
+int get_opt(int, char **);
+
+#endif
diff --git a/src/netdt.c b/src/netdt.c
new file mode 100644
index 0000000..968b303
--- /dev/null
+++ b/src/netdt.c
@@ -0,0 +1,72 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <string.h>
+#include "defs.h"
+#include "param.h"
+#include "netdt.h"
+#include "arp.h"
+
+void usage(char *);
+void sigh(int);
+
+int main(int argc, char **argv)
+{
+	extern struct param param;
+#ifdef DEBUG
+	int i;
+	for (i = 0; i < argc; i++)
+		PDEBUG("Command line argv[%d] = %s\n", i, argv[i]);
+#endif
+	if (argc < 2) usage(argv[0]);
+
+	signal(SIGQUIT, sigh);
+	signal(SIGTERM, sigh);
+	signal(SIGINT, sigh);
+
+	if (get_opt(argc, argv) == -1) usage(argv[0]);
+	//PDEBUG("%s", param.iface);
+	if (strncmp(argv[1], "arp", 3) == 0) {
+		if ((param.flags & 0xFFFFFFFF) == 0xFFFFFFFF) arp_usage(argv[0]);
+		return (arp_init(argc, argv));
+	} else usage(argv[0]);
+	
+	return (0);
+}
+
+void usage(char *pname)
+{
+	fprintf(stderr, "The Network Discovery Tool " PROGRAM_VERSION " by " PROGRAM_AUTHOR "\n"
+			"Usage: %s <type> <options>\n"
+			"Types:\n"
+			" arp  Network discovery using ARP\n"
+			"Options:\n"
+			" -h   Help screen\n"
+			, pname);
+	exit(0);
+}
+
+void sigh(int type)
+{
+	exit(1);
+}
diff --git a/src/netdt.o b/src/netdt.o
new file mode 100644
index 0000000..1c5bcab
--- /dev/null
+++ b/src/netdt.o
diff --git a/src/network.c b/src/network.c
new file mode 100644
index 0000000..5f0bf42
--- /dev/null
+++ b/src/network.c
@@ -0,0 +1,42 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#include <netinet/in.h>
+
+struct network
+{
+	unsigned long start, end;
+} network;
+
+void inline net_calc_network(struct in_addr ip, struct in_addr netmask)
+{
+	network.start = ip.s_addr & netmask.s_addr; /* sitas isvis niekam nereikalingas, reikia sugalvoti kur i kisti */
+	network.end = ip.s_addr | (~netmask.s_addr);
+}
+
+in_addr_t net_next_ip(struct in_addr curr_ip)
+{
+	unsigned long curr;
+	curr = ntohl(curr_ip.s_addr);
+	if (curr + 1 <= ntohl(network.end)) {
+		curr++;
+		return (htonl(curr));
+	} else return (0);
+}
diff --git a/src/param.c b/src/param.c
new file mode 100644
index 0000000..3c7f5fb
--- /dev/null
+++ b/src/param.c
@@ -0,0 +1,69 @@
+/* 
+ * The Network Discovery Tool.
+ * Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
+ *
+ * The Network Discovery Tool 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+#include <unistd.h>
+#define _GNU_SOURCE
+#include <getopt.h>
+#include "param.h"
+ 
+struct param param;
+
+int get_opt(int argc, char **argv)
+{
+	extern char *optarg;
+	extern int optind, opterr, optopt;
+	int c;
+	
+	optind = 2;
+	
+	param.packet_delay = 90;
+	
+	while ( (c = getopt(argc, argv, "i:t:h")) != -1) {
+		switch (c) {
+			case 'i':
+				param.iface = optarg;
+				break;
+			case 't':
+				param.packet_delay = strtol(optarg, (char**)NULL, 10);
+				if (param.packet_delay == LONG_MIN || param.packet_delay == LONG_MAX) {
+					fprintf(stderr, "Error: incorrect packet delay, using defaults.\n");
+					param.packet_delay = 90;
+				}
+				break;
+			case 'h':
+				param.flags |= 0xFFFFFFFF; /* ijungiam paskutini bita */
+				break;
+			default:
+				//fprintf(stderr, "Unknown option -%c\n", optopt);
+				return (-1);
+				break;
+		}
+	}
+	
+	if (optind - 2 == 0) {
+		fprintf(stderr, "Error: too few arguments\n");
+		return (-1);
+	}
+	
+	return (0);
+}