/* * IP_MASQ_FTP CUSeeMe masquerading module * * * Version: @(#)$Id: ip_masq_cuseeme.c,v 1.4 1998/10/06 04:48:57 davem Exp $ * * Author: Richard Lynch * * * Fixes: * Richard Lynch : Updated patch to conform to new module * specifications * Nigel Metheringham : Multiple port support * Michael Owings : Fixed broken init code * Added code to update inbound * packets with correct local addresses. * Fixes audio and "chat" problems * Thanx to the CU-SeeMe Consortium for * technical docs * Steven Clarke : Small changes for 2.1 * * * * 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. * * Multiple Port Support * The helper can be made to handle up to MAX_MASQ_APP_PORTS (normally 12) * with the port numbers being defined at module load time. The module * uses the symbol "ports" to define a list of monitored ports, which can * be specified on the insmod command line as * ports=x1,x2,x3... * where x[n] are integer port numbers. This option can be put into * /etc/conf.modules (or /etc/modules.conf depending on your config) * where modload will pick it up should you use modload to load your * modules. * */ #include <linux/config.h> #include <linux/module.h> #include <asm/system.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/skbuff.h> #include <linux/in.h> #include <linux/ip.h> #include <linux/init.h> #include <net/protocol.h> #include <net/udp.h> /* #define IP_MASQ_NDEBUG */ #include <net/ip_masq.h> #pragma pack(1) /* CU-SeeMe Data Header */ typedef struct { u_short dest_family; u_short dest_port; u_long dest_addr; short family; u_short port; u_long addr; u_long seq; u_short msg; u_short data_type; u_short packet_len; } cu_header; /* Open Continue Header */ typedef struct { cu_header cu_head; u_short client_count; /* Number of client info structs */ u_long seq_no; char user_name[20]; char stuff[4]; /* flags, version stuff, etc */ }oc_header; /* client info structures */ typedef struct { u_long address; /* Client address */ char stuff[8]; /* Flags, pruning bitfield, packet counts etc */ } client_info; #pragma pack() /* * List of ports (up to MAX_MASQ_APP_PORTS) to be handled by helper * First port is set to the default port. */ static int ports[MAX_MASQ_APP_PORTS] = {7648}; /* I rely on the trailing items being set to zero */ struct ip_masq_app *masq_incarnations[MAX_MASQ_APP_PORTS]; /* * Debug level */ #ifdef CONFIG_IP_MASQ_DEBUG static int debug=0; MODULE_PARM(debug, "i"); #endif MODULE_PARM(ports, "1-" __MODULE_STRING(MAX_MASQ_APP_PORTS) "i"); static int masq_cuseeme_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms) { MOD_INC_USE_COUNT; return 0; } static int masq_cuseeme_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms) { MOD_DEC_USE_COUNT; return 0; } int masq_cuseeme_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr) { struct sk_buff *skb = *skb_p; struct iphdr *iph = skb->nh.iph; struct udphdr *uh = (struct udphdr *)&(((char *)iph)[iph->ihl*4]); cu_header *cu_head; char *data=(char *)&uh[1]; if (skb->len - ((unsigned char *) data - skb->h.raw) >= sizeof(cu_header)) { cu_head = (cu_header *) data; /* cu_head->port = ms->mport; */ if( cu_head->addr ) cu_head->addr = (u_long) maddr; if(ntohs(cu_head->data_type) == 257) IP_MASQ_DEBUG(1-debug, "Sending talk packet!\n"); } return 0; } int masq_cuseeme_in (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr) { struct sk_buff *skb = *skb_p; struct iphdr *iph = skb->nh.iph; struct udphdr *uh = (struct udphdr *)&(((char *)iph)[iph->ihl*4]); cu_header *cu_head; oc_header *oc; client_info *ci; char *data=(char *)&uh[1]; u_short len = skb->len - ((unsigned char *) data - skb->h.raw); int i, off; if (len >= sizeof(cu_header)) { cu_head = (cu_header *) data; if(cu_head->dest_addr) /* Correct destination address */ cu_head->dest_addr = (u_long) ms->saddr; if(ntohs(cu_head->data_type)==101 && len > sizeof(oc_header)) { oc = (oc_header * ) data; /* Spin (grovel) thru client_info structs till we find our own */ off=sizeof(oc_header); for(i=0; (i < oc->client_count && off+sizeof(client_info) <= len); i++) { ci=(client_info *)(data+off); if(ci->address==(u_long) maddr) { /* Update w/ our real ip address and exit */ ci->address = (u_long) ms->saddr; break; } else off+=sizeof(client_info); } } } return 0; } struct ip_masq_app ip_masq_cuseeme = { NULL, /* next */ "cuseeme", 0, /* type */ 0, /* n_attach */ masq_cuseeme_init_1, /* ip_masq_init_1 */ masq_cuseeme_done_1, /* ip_masq_done_1 */ masq_cuseeme_out, /* pkt_out */ masq_cuseeme_in /* pkt_in */ }; /* * ip_masq_cuseeme initialization */ __initfunc(int ip_masq_cuseeme_init(void)) { int i, j; for (i=0; (i<MAX_MASQ_APP_PORTS); i++) { if (ports[i]) { if ((masq_incarnations[i] = kmalloc(sizeof(struct ip_masq_app), GFP_KERNEL)) == NULL) return -ENOMEM; memcpy(masq_incarnations[i], &ip_masq_cuseeme, sizeof(struct ip_masq_app)); if ((j = register_ip_masq_app(masq_incarnations[i], IPPROTO_UDP, ports[i]))) { return j; } #if DEBUG_CONFIG_IP_MASQ_CUSEEME IP_MASQ_DEBUG(1-debug, "CuSeeMe: loaded support on port[%d] = %d\n", i, ports[i]); #endif } else { /* To be safe, force the incarnation table entry to NULL */ masq_incarnations[i] = NULL; } } return 0; } /* * ip_masq_cuseeme fin. */ int ip_masq_cuseeme_done(void) { int i, j, k; k=0; for (i=0; (i<MAX_MASQ_APP_PORTS); i++) { if (masq_incarnations[i]) { if ((j = unregister_ip_masq_app(masq_incarnations[i]))) { k = j; } else { kfree(masq_incarnations[i]); masq_incarnations[i] = NULL; IP_MASQ_DEBUG(1-debug, "CuSeeMe: unloaded support on port[%d] = %d\n", i, ports[i]); } } } return k; } #ifdef MODULE EXPORT_NO_SYMBOLS; int init_module(void) { if (ip_masq_cuseeme_init() != 0) return -EIO; return 0; } void cleanup_module(void) { if (ip_masq_cuseeme_done() != 0) IP_MASQ_DEBUG(1-debug, "ip_masq_cuseeme: can't remove module"); } #endif /* MODULE */