Import udp_broadcast_relay-0.1.tar.gz

4 files changed, 742 insertions, 0 deletions

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..e77696a
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
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+                          675 Mass Ave, Cambridge, MA 02139, USA
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diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..a9287b2
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,2 @@
+udp_broadcast_relay: main.c
+	gcc -g main.c -o udp_broadcast_relay
diff --git a/README b/README
new file mode 100644
index 0000000..d40523b
--- /dev/null
+++ b/README
@@ -0,0 +1,62 @@
+UDP Broadcast Packet Relay
+==============================
+
+This program listens for packets on a specified UDP broadcast.
+When a packet is received, it sends that packet to all
+specified interfaces but the one it came from as though it
+originated from the original sender.  
+
+The primary purpose of this is to allow games on machines on
+separated local networks (Ethernet, WLAN) that use udp broadcasts
+to find each other to do so.
+
+INSTALL
+-------
+make ; cp udp_broadcast_relay /some/where
+
+
+USAGE
+-----
+/some/where/udp_broadcast_relay udp-port
+
+udp_broadcast_relay must be run as boot to be able to create a raw
+socket (necessary) to send packets though they originated from the
+original sender)
+
+
+COMPATIBILITY
+-------------
+- I run debian woody with Linux 2.4.20, and here it works.
+
+
+EXAMPLE
+-------
+/some/where/udp_broadcast_relay 2116  # forward Warcraft 3 broadcast packets
+
+
+BUGS/CRITICISM/PATCHES/ETC
+--------------------------
+web:	http://www.joachim-breitner.de/udp_forward_relay/
+e-mail: Joachim Breitner <mail@joachim-breitner.de>
+
+HISTORY
+------
+0.1	2003-09-15
+	Initial rewrite of udp_broadcast_fw
+
+CREDITS
+-------
+This is based upon udp_broadcast_fw:
+Web: http://www.serverquery.com/udp_broadcast_fw/
+Email: Nathan O'Sullivan <nathan@ausgamers.com>
+
+HISTORY of udp_broadcast_fw
+-------
+0.1.1 - 19 Feb 02
+	Moved fork() code to just before main loop so that errors would appear
+0.1   - 18 Feb 02
+	Initial release
+
+LICENSE
+-------
+This code is made available under the GPL. Read COPYING for more info.
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..a80ead6
--- /dev/null
+++ b/main.c
@@ -0,0 +1,339 @@
+/*
+******************************************************************
+udp_broadcast_relay
+	Relays UDP broadcasts to other networks, forging
+	the sender address.
+
+Copyright (c) 2003 Joachim Breitner <mail@joachim-breitner.de>
+
+Based upon:
+udp_broadcast_fw ; Forwards UDP broadcast packets to all local 
+	interfaces as though they originated from sender
+	
+Copyright (C) 2002  Nathan O'Sullivan
+
+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.
+******************************************************************
+
+Thanks:
+
+Arny <cs6171@scitsc.wlv.ac.uk> 
+- public domain UDP spoofing code
+http://www.netfor2.com/ip.htm
+- IP/UDP packet formatting info
+
+*/
+
+#define MAXIFS	256
+#define DPRINT  printf
+#define IPHEADER_LEN 20
+#define UDPHEADER_LEN 8
+#define HEADER_LEN (IPHEADER_LEN + UDPHEADER_LEN)
+#define DEBUG
+ 
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in_systm.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <errno.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <linux/if.h>
+#include <sys/ioctl.h>
+
+main(int argc,char **argv)
+{
+	/* We use two sockets - one for receiving broadcast packets (type UDP), and
+	   one for spoofing them (type RAW) */
+	int fd,rcv;
+
+	/* Structure holds info on local interfaces */
+	struct ifreq reqbuf;
+	int maxifs;
+		
+	/* list of addresses and interface numbers on local machine */
+	// struct sockaddr_in addr[MAXIFS];
+	struct {
+		struct sockaddr_in brdaddr;
+		int ifindex;
+	} ifs[MAXIFS];
+	
+	/* Address broadcast packet was sent from */
+	struct sockaddr_in rcv_addr;
+	
+	/* Incoming message read via rcvsmsg */
+	struct msghdr rcv_msg;
+	struct iovec iov;
+	u_char pkt_infos[16384];
+
+	int x=1, len;
+	
+	u_char gram[4096]=
+	{
+		0x45,	0x00,	0x00,	0x26,
+		0x12,	0x34,	0x00,	0x00,
+		0xFF,	0x11,	0,	0,
+		0,	0,	0,	0,
+		0,	0,	0,	0,
+		0,	0,	0,	0,
+		0x00,	0x12,	0x00,	0x00,
+		'1','2','3','4','5','6','7','8','9','0'
+	};
+
+	iov.iov_base = gram+ HEADER_LEN; 
+	iov.iov_len = 4006 - HEADER_LEN - 1;
+	
+	rcv_msg.msg_name = &rcv_addr;
+	rcv_msg.msg_namelen = sizeof(rcv_addr);
+	rcv_msg.msg_iov = &iov;
+	rcv_msg.msg_iovlen = 1;
+	rcv_msg.msg_control = pkt_infos;
+	rcv_msg.msg_controllen = sizeof(pkt_infos);
+	struct cmsghdr *cmsg;
+	int *ttlptr=NULL;
+	int rcv_ifindex;
+	
+	/* ARGS */
+	u_int16_t port;
+	u_char id;
+	u_char ttl;
+
+	if(argc < 5)
+	{
+		fprintf(stderr,"usage: %s id udp-port dev1 dev2 ...\n",*argv);
+		fprintf(stderr,"This program listens for broadcast packets on the specified udp-port\n"
+			"and then forwards them to each other given interface.  Packets are sent\n"
+			"such that they appear to have come from the original broadcaster. When using\n"
+			"multiple instances for the same port on the same network, they must have the\n"
+			"a different id.\n");
+		exit(1);
+	};
+	
+	if ((id = atoi(argv[1])) == 0)
+	{
+		fprintf (stderr,"ID argument not valid\n");
+		exit(1);
+	}
+	argc--;
+	argv++;
+
+	if (id < 1 || id > 99)
+	{
+		fprintf (stderr,"ID argument %i not between 1 and 99\n",id);
+		exit(1);
+	}
+	ttl = id+64;
+	gram[8] = ttl; 
+
+	if ((port = atoi(argv[1])) == 0)
+	{
+		fprintf (stderr,"Port argument not valid\n");
+		exit(1);
+	}
+	argc--;
+	argv++;
+
+	/* We need to find out what IP's are bound to this host - set up a temporary socket to do so */
+ 	if((fd=socket(AF_INET,SOCK_RAW,IPPROTO_RAW)) < 0)
+	{
+  		perror("socket");
+		fprintf(stderr,"You must be root to create a raw socket\n");
+  		exit(1);
+  	};
+	DPRINT ("ID: %i (ttl: %i), Port %i\n",id,ttl,port);
+
+	/* For each interface on the command line */
+	for (maxifs=0;argc>1;argc--,argv++)
+	{
+		strncpy(reqbuf.ifr_name,argv[1],IFNAMSIZ);
+
+		/* Request index for this interface */
+		if (ioctl(fd,SIOCGIFINDEX, &reqbuf) < 0) {
+			perror("ioctl(SIOCGIFINDEX)");
+			exit(1);
+		}
+		
+		/* Save the index for later use */	
+		ifs[maxifs].ifindex = reqbuf.ifr_ifindex;
+		
+		/* Request flags for this interface */
+		if (ioctl(fd,SIOCGIFFLAGS, &reqbuf) < 0) {
+			perror("ioctl(SIOCGIFFLAGS)");
+			exit(1);
+		}
+
+		/* if the interface is not up or a loopback, ignore it */
+		if ((reqbuf.ifr_flags & IFF_UP) == 0 ||
+		    (reqbuf.ifr_flags & IFF_BROADCAST) == 0||
+      		    (reqbuf.ifr_flags & IFF_LOOPBACK) )
+			continue;
+
+		/* Request the IP address for this interface */
+  		if (ioctl(fd,SIOCGIFBRDADDR, &reqbuf) < 0) {
+      			perror("ioctl(SIOCGIFBRDADDR)");
+      			exit(1);
+    		}
+
+		/* Save the address for later use */
+		bcopy(	(struct sockaddr_in *)&reqbuf.ifr_addr,
+			&ifs[maxifs].brdaddr,
+			sizeof(struct sockaddr_in) );
+
+		DPRINT("%s: %i / %s\n",
+			reqbuf.ifr_name,
+			ifs[maxifs].ifindex,
+			inet_ntoa(ifs[maxifs].brdaddr.sin_addr) );
+
+		maxifs++;
+	}
+	maxifs--;
+	
+	/* Free our allocated buffer and close the socket */
+	close(fd);
+
+	/* Create our broadcast socket */
+	if((rcv=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP)) < 0)
+  	{
+  		perror("socket");
+  		exit(1);
+  	};
+	x = 1;
+	if(setsockopt(rcv, SOL_SOCKET, SO_BROADCAST, (char*) &x, sizeof(int))<0){
+		perror("SO_BROADCAST on rcv");
+		exit(1);
+	};
+	if(setsockopt(rcv, SOL_IP, IP_RECVTTL, (char*) &x, sizeof(int))<0){
+		perror("IP_RECVTTL on rcv");
+		exit(1);
+	};
+	if(setsockopt(rcv, SOL_IP, IP_PKTINFO, (char*) &x, sizeof(int))<0){
+		perror("IP_PKTINFO on rcv");
+		exit(1);
+	};
+
+	/* We bind it to broadcast addr on the given port */
+	rcv_addr.sin_family = AF_INET;
+	rcv_addr.sin_port = htons(port);
+	rcv_addr.sin_addr.s_addr = INADDR_ANY;
+
+	if ( bind (rcv, (struct sockaddr *)&rcv_addr, sizeof(struct sockaddr_in) ) < 0 )
+	{
+		perror("bind");
+		fprintf(stderr,"A program is already bound to the broadcast address for the given port\n");
+		exit(1);
+	}
+	
+	/* Set up a raw socket for sending our packets through */
+	if((fd=socket(AF_INET,SOCK_RAW,IPPROTO_RAW)) < 0)
+  	{
+  		perror("socket");
+  		exit(1);
+  	};
+
+	/* Set dest port to that provided on command line */
+	*(u_short*)(gram+22)=(u_short)htons(port);
+	
+	x=1;
+	if (setsockopt(fd,SOL_SOCKET,SO_BROADCAST,(char*)&x,sizeof(x))<0)
+	{
+		perror("setsockopt SO_BROADCAST");
+		exit(1);
+  	};
+
+	/* Enable IP header stuff on the raw socket */
+	#ifdef IP_HDRINCL
+	x=1;
+	if (setsockopt(fd,IPPROTO_IP,IP_HDRINCL,(char*)&x,sizeof(x))<0)
+	{
+		perror("setsockopt IP_HDRINCL");
+		exit(1);
+  	};
+	#else
+	#error IP_HDRINCL support is required
+	#endif
+
+ 	/* Fork to background */
+  #ifndef DEBUG
+  if (fork())
+    exit(0);
+
+  fclose(stdin);
+  fclose(stdout);
+  fclose(stderr);
+  #endif
+
+  DPRINT("Done Initializing\n\n");
+
+	for (;;)
+	{
+		/* Receive a broadcast packet */
+		// x = sizeof(struct sockaddr_in);
+		// len = recvfrom(rcv,gram+ HEADER_LEN,4006 - HEADER_LEN - 1,0,&rcv_addr,&x);
+		len = recvmsg(rcv,&rcv_msg,0);
+		if (len <= 0) continue;	/* ignore broken packets */
+
+		/* Find the ttl */
+		ttlptr=NULL;
+		if (rcv_msg.msg_controllen>0)
+		  for (cmsg=CMSG_FIRSTHDR(&rcv_msg);cmsg;cmsg=CMSG_NXTHDR(&rcv_msg,cmsg)) {
+		    if (cmsg->cmsg_type==IP_TTL) {
+		      ttlptr = (int *)CMSG_DATA(cmsg);
+		    }
+		    if (cmsg->cmsg_type==IP_PKTINFO) {
+		      rcv_ifindex=((struct in_pktinfo *)CMSG_DATA(cmsg))->ipi_ifindex;
+		    }
+		  }
+
+		if (ttlptr == NULL) {
+			perror("TTL not found\n");
+			exit(1);
+		}
+		if (*ttlptr == ttl) {
+			DPRINT ("Got local packge (TTL %i) on interface %i\n",*ttlptr,rcv_ifindex);
+			continue;
+		}
+		
+
+		gram[HEADER_LEN + len] =0;
+		DPRINT("Got remote package:\n");
+		DPRINT("Content:\t%s\n",gram+HEADER_LEN);
+		DPRINT("TTL:\t\t%i\n",*ttlptr);
+		DPRINT("Interface:\t%i\n",rcv_ifindex);
+		DPRINT("From:\t\t%s:%d\n",inet_ntoa(rcv_addr.sin_addr),rcv_addr.sin_port);
+	
+		/* copy sender's details into our datagram as the source addr */	
+		bcopy(&(rcv_addr.sin_addr.s_addr),(gram+12),4);
+	  	*(u_short*)(gram+20)=(u_short)rcv_addr.sin_port;
+
+		/* set the length of the packet */
+		*(u_short*)(gram+24)=htons(8 + len);
+		*(u_short*)(gram+2)=htons(28+len);
+
+		/* Iterate through the local addresses and send packet to each one */
+		for (x=0;x<=maxifs;x++)
+		{
+			if (ifs[x].ifindex == rcv_ifindex) continue;
+
+			/* Set destination addr ip - port is set already*/
+			bcopy(&(ifs[x].brdaddr.sin_addr.s_addr),(gram+16),4);	
+
+			DPRINT ("Sent to %s:%d on interface %i\n", inet_ntoa(ifs[x].brdaddr.sin_addr),ntohs(*(u_short*)(gram+22)),ifs[x].ifindex);
+				
+			/* Send the packet */
+			if (sendto(fd,&gram,28+len,0,(struct sockaddr*)&ifs[x].brdaddr,sizeof(struct sockaddr)) < 0)
+				perror("sendto");
+		}
+		DPRINT ("\n");
+	}
+}