RAW packet transmission function

src/transmitter.c

@@ -0,0 +1,102 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2012  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <netinet/if_ether.h>	/* {P,A}F_PACKET, ETH_P_*, socket, SOCK_RAW,
+				 * setsockopt, SOL_SOCKET, SO_BINDTODEVICE, sendto */
+#include <netinet/in.h>		/* htons */
+#include <netpacket/packet.h>	/* sockaddr_ll, PACKET_OTHERHOST */
+#include <stdio.h>		/* fprintf, stderr, perror */
+#include <unistd.h>		/* close */
+
+#include "ipv4.h"
+#include "transmitter.h"
+#include "wrapper.h"
+
+struct sockaddr_ll	socket_address;
+int			sock;
+
+/**
+ * Initialize socket and all needed properties. Should be called only once on program startup.
+ *
+ * @return		0 for success
+ * @return		1 for failure
+ */
+int transmission_init(void)
+{
+	unsigned char on = 1;
+
+	/* prepare settings for RAW socket */
+	socket_address.sll_family	= PF_PACKET;			/* RAW communication */
+	socket_address.sll_protocol	= htons(ETH_P_IP);		/* protocol above the ethernet layer */
+	socket_address.sll_ifindex	= interface.ifr_ifindex;	/* set index of the network device */
+	socket_address.sll_pkttype	= PACKET_OTHERHOST;		/* target host is another host */
+
+	/* initialize RAW socket */
+	if ((sock = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) == -1) {
+		fprintf(stderr, "[Error] Couldn't open RAW socket.\n");
+		perror("socket()");
+		return 1;
+	}
+
+	/* bind the socket to the interface */
+	if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, &interface, sizeof(struct ifreq)) == -1) {
+		fprintf(stderr, "[Error] Couldn't bind the socket to the interface.\n");
+		perror("setsockopt()");
+		return 1;
+	}
+
+	return 0;
+}
+
+/**
+ * Close socket. Should be called only once on program shutdown.
+ *
+ * @return		0 for success
+ * @return		1 for failure
+ */
+int transmission_quit(void)
+{
+	/* close the socket */
+	if (close(sock)) {
+		fprintf(stderr, "[Error] Couldn't close the transmission socket.\n");
+		perror("close()");
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+/**
+ * Send raw packet -- not doing any modifications to it.
+ *
+ * @param	data	Raw packet data, including ethernet header
+ * @param	length	Length of the whole packet in bytes
+ *
+ * @return		0 for success
+ * @return		1 for failure
+ */
+int transmit(unsigned char *data, unsigned int length)
+{
+	if (sendto(sock, data, length, 0, (struct sockaddr *) &socket_address, sizeof(struct sockaddr_ll)) != length) {
+		fprintf(stderr, "[Error] Couldn't send a RAW packet.\n");
+		perror("sendto()");
+		return 1;
+	}
+
+	return 0;
+}

src/transmitter.h

@@ -0,0 +1,28 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2012  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TRANSMITTER_H
+#define TRANSMITTER_H
+
+#include "ipv4.h"
+
+int transmission_init(void);
+int transmission_quit(void);
+int transmit(unsigned char *data, unsigned int length);
+
+#endif /* TRANSMITTER_H */

src/wrapper.c

@@ -1,6 +1,6 @@
 /*
  *  WrapSix
- *  Copyright (C) 2008-2011  Michal Zima <xhire@mujmalysvet.cz>
+ *  Copyright (C) 2008-2012  Michal Zima <xhire@mujmalysvet.cz>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU Affero General Public License as
@@ -33,12 +33,14 @@
 #include "ipv4.h"
 #include "ipv6.h"
 #include "nat.h"
+#include "transmitter.h"
 #include "wrapper.h"
 
 #define INTERFACE	"eth0"
 #define BUFFER_SIZE	65536
 #define PREFIX		"::"
 
+struct ifreq		interface;
 struct s_ipv6_addr	ndp_multicast_addr;
 struct s_ipv6_addr	wrapsix_ipv6_prefix;
 
@@ -46,7 +48,6 @@ int process(char *packet);
 
 int main(int argc, char **argv)
 {
-	struct ifreq		interface;
 	struct packet_mreq	pmr;
 
 	struct sockaddr_ll	addr;
@@ -85,6 +86,12 @@ int main(int argc, char **argv)
 	/* compute binary IPv6 address of WrapSix prefix */
 	inet_pton(AF_INET6, PREFIX, &wrapsix_ipv6_prefix);
 
+	/* initiate sending socket */
+	if (transmission_init()) {
+		fprintf(stderr, "[Error] Unable to initiate sending socket\n");
+		return 1;
+	}
+
 	/* initiate NAT tables */
 	nat_init();
 
@@ -103,6 +110,9 @@ int main(int argc, char **argv)
 	}
 
 	/* clean-up */
+	/* close sending socket */
+	transmission_quit();
+
 	/* empty NAT tables */
 	nat_quit();
 

src/wrapper.h

@@ -1,6 +1,6 @@
 /*
  *  WrapSix
- *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
+ *  Copyright (C) 2008-2012  Michal Zima <xhire@mujmalysvet.cz>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU Affero General Public License as
@@ -22,6 +22,7 @@
 #include "ipv4.h"
 #include "ipv6.h"
 
+extern struct ifreq		interface;
 extern struct s_ipv6_addr	ndp_multicast_addr;
 extern struct s_ipv6_addr	wrapsix_ipv6_prefix;