?? ipt_multiport.c
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/* Kernel module to match one of a list of TCP/UDP ports: ports are in the same place so we can treat them as equal. *//* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */#include <linux/module.h>#include <linux/types.h>#include <linux/udp.h>#include <linux/skbuff.h>#include <linux/netfilter_ipv4/ipt_multiport.h>#include <linux/netfilter_ipv4/ip_tables.h>MODULE_LICENSE("GPL");MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");MODULE_DESCRIPTION("iptables multiple port match module");#if 0#define duprintf(format, args...) printk(format , ## args)#else#define duprintf(format, args...)#endif/* Returns 1 if the port is matched by the test, 0 otherwise. */static inline intports_match(const u_int16_t *portlist, enum ipt_multiport_flags flags, u_int8_t count, u_int16_t src, u_int16_t dst){ unsigned int i; for (i=0; i<count; i++) { if (flags != IPT_MULTIPORT_DESTINATION && portlist[i] == src) return 1; if (flags != IPT_MULTIPORT_SOURCE && portlist[i] == dst) return 1; } return 0;}static intmatch(const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, const void *matchinfo, int offset, int *hotdrop){ u16 ports[2]; const struct ipt_multiport *multiinfo = matchinfo; /* Must not be a fragment. */ if (offset) return 0; /* Must be big enough to read ports (both UDP and TCP have them at the start). */ if (skb_copy_bits(skb, skb->nh.iph->ihl*4, ports, sizeof(ports)) < 0) { /* We've been asked to examine this packet, and we can't. Hence, no choice but to drop. */ duprintf("ipt_multiport:" " Dropping evil offset=0 tinygram.\n"); *hotdrop = 1; return 0; } return ports_match(multiinfo->ports, multiinfo->flags, multiinfo->count, ntohs(ports[0]), ntohs(ports[1]));}/* Called when user tries to insert an entry of this type. */static intcheckentry(const char *tablename, const struct ipt_ip *ip, void *matchinfo, unsigned int matchsize, unsigned int hook_mask){ const struct ipt_multiport *multiinfo = matchinfo; if (matchsize != IPT_ALIGN(sizeof(struct ipt_multiport))) return 0; /* Must specify proto == TCP/UDP, no unknown flags or bad count */ return (ip->proto == IPPROTO_TCP || ip->proto == IPPROTO_UDP) && !(ip->invflags & IPT_INV_PROTO) && matchsize == IPT_ALIGN(sizeof(struct ipt_multiport)) && (multiinfo->flags == IPT_MULTIPORT_SOURCE || multiinfo->flags == IPT_MULTIPORT_DESTINATION || multiinfo->flags == IPT_MULTIPORT_EITHER) && multiinfo->count <= IPT_MULTI_PORTS;}static struct ipt_match multiport_match = { .name = "multiport", .match = &match, .checkentry = &checkentry, .me = THIS_MODULE,};static int __init init(void){ return ipt_register_match(&multiport_match);}static void __exit fini(void){ ipt_unregister_match(&multiport_match);}module_init(init);module_exit(fini);
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