diff options
| -rw-r--r-- | COPYING | 339 | ||||
| -rw-r--r-- | Makefile | 2 | ||||
| -rw-r--r-- | README | 62 | ||||
| -rw-r--r-- | main.c | 339 |
4 files changed, 742 insertions, 0 deletions
@@ -0,0 +1,339 @@ + GNU GENERAL PUBLIC LICENSE + Version 2, June 1991 + + Copyright (C) 1989, 1991 Free Software Foundation, Inc. + 675 Mass Ave, Cambridge, MA 02139, USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The licenses for most software are designed to take away your +freedom to share and change it. By contrast, the GNU General Public +License is intended to guarantee your freedom to share and change free +software--to make sure the software is free for all its users. This +General Public License applies to most of the Free Software +Foundation's software and to any other program whose authors commit to +using it. (Some other Free Software Foundation software is covered by +the GNU Library General Public License instead.) You can apply it to +your programs, too. + + When we speak of free software, we are referring to freedom, not +price. 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It is safest +to attach them to the start of each source file to most effectively +convey the exclusion of warranty; and each file should have at least +the "copyright" line and a pointer to where the full notice is found. + + <one line to give the program's name and a brief idea of what it does.> + Copyright (C) 19yy <name of author> + + 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., 675 Mass Ave, Cambridge, MA 02139, USA. + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this +when it starts in an interactive mode: + + Gnomovision version 69, Copyright (C) 19yy name of author + Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, the commands you use may +be called something other than `show w' and `show c'; they could even be +mouse-clicks or menu items--whatever suits your program. + +You should also get your employer (if you work as a programmer) or your +school, if any, to sign a "copyright disclaimer" for the program, if +necessary. Here is a sample; alter the names: + + Yoyodyne, Inc., hereby disclaims all copyright interest in the program + `Gnomovision' (which makes passes at compilers) written by James Hacker. + + <signature of Ty Coon>, 1 April 1989 + Ty Coon, President of Vice + +This General Public License does not permit incorporating your program into +proprietary programs. If your program is a subroutine library, you may +consider it more useful to permit linking proprietary applications with the +library. If this is what you want to do, use the GNU Library General +Public License instead of this License. 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 @@ -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. @@ -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"); + } +} |